Abstract:
A method and apparatus for discriminating among a plurality of coin denominations includes sensing the characteristics of a test coin with a test coin sensor and comparing the characteristics of the test coin with characteristics of a plurality of coin denominations thereby producing comparison signals. If the comparing results in a match between the characteristics of the test coin and characteristics of one of the coin denominations, then the test coin is declared to be the matched coin denomination. If the comparing results in matches between the characteristics of the test coin and characteristics of more than one of the coin denominations, then the matches are compared to each other to determine which of the matches represents a valid match. The test coin is declared to be the coin denomination which corresponds to the valid match.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to coin analyzers or discriminators and, more particularly, to coin analyzers that are capable of distinguishing among a plurality of coins. The invention is useful with various coin-operated machines; for example, video games, car washes, clothes washers and dryers, coin counters, and the like. 
     The invention in commonly assigned U.S. Pat. Nos. 4,884,672 and 5,056,644 provided the first commercially successful coin analyzer that was capable of detecting two coins, or a coin and token. In such commonly owned patents, a sample coin holder held two coin denominations or a coin and token adjacent to associated sample coin coil assemblies. A test coin coil assembly was located at a coin path. A circuit compared the effect on the magnetic field at the test coin assembly with the sample coin coil assemblies in order to determine when a match occurred between a test coin and one of the sample coins. The coin analyzer disclosed in these commonly assigned patents utilized analog circuitry to operate a kicker coil to accept a valid coin and in order to provide a credit indication of the amount of valid coins accepted. 
     Since the introduction of the Slug Buster II coin analyzer, which embodied the invention in the &#39;672 and &#39;644 patents, other multiple coin analyzers have been developed. These other coin analyzers typically utilize a microprocessor in combination with a test coil assembly and other input circuitry. The microprocessor stores characteristics of various coin denominations. When a coin is inserted in the coin path, the output of the test coil is applied to the microprocessor through the input circuitry. The microprocessor attempts to identify a match between the characteristics of the test coin and those stored within the microcomputer. If a match occurs, then a particular coin is deemed to have been identified. Such coin analyzers typically have a learning mode in which the coins to be identified are juxtaposed with the test coil while the microprocessor stores the parameters of each denomination coin. 
     One difficulty arises with coins of very similar characteristics. For example, the United States Mint introduced the Susan B. Anthony dollar coin which was made from a five-layer clad blank. The United States quarter is also made from a five-layer clad blank similar to that from which the Susan B. Anthony dollar is made. As a result, commercially available coin analyzers are incapable of accurately discriminating between a Susan B. Anthony dollar and a United States quarter. Other countries have such coins of similar properties. Also, coins from one country may have similar properties to a coin of another country. The inability of coin analyzers to distinguish between two coins having similar properties is a serious deficiency that heretofore has created a long-felt need in the art of coin analyzers. The present invention satisfies this long-felt need. 
     SUMMARY OF THE INVENTION 
     The present invention provides a coin discrimination apparatus and method which is capable of repeatedly and accurately discriminating between coins of similar properties, including, by way of example, United States quarters and Susan B. Anthony dollars. A coin discrimination apparatus, according to an aspect of the invention, includes a test coin sensor that is adapted to sense a coin to be detected and including a test coin coil assembly. A microprocessor-based control is responsive to the test coin coil assembly to determine whether a test coin at the test coin sensor matches any of a plurality of coin denominations including resolving matches of a test coin at the test coin sensor with more than one of the plurality of coin denominations. 
     According to another aspect of the invention, a coin discrimination apparatus includes a plurality of sample coin assemblies, each including a sample coin holder and a sample coil assembly. The sample coil assembly generates a sample field and senses a sample field with the holder holding a sample coin. The apparatus further includes a test coin sensor including a coin guide path and a test coil assembly. The test coil assembly generates a test field and senses a test field with a test coin at the guide path. The apparatus further includes a microprocessor-based control which compares the test coil assembly with each of the sample coil assemblies and determines whether a test coin at the guide path matches a sample coin at one of the sample coin holders. The microprocessor-based control resolves matches of a test guide at the guide path with sample coins at more than one of the sample coin holders. 
     This is accomplished, according to a more detailed aspect of the invention, by the control determining which of the coins at more than one of the sample coin assemblies indicates a match with a coin at the test coin sensor. Substantially throughout the duration, the test coin is at the test coin sensor. The control, according to this more-detailed aspect of the invention, determines which of the coins at more than one of the sample coin assemblies first indicates a match with the coin at the test coin sensor. 
     A method of discriminating among a plurality of coin denominations includes sensing the characteristics of a test coin and comparing the characteristics of the test coin with characteristics of a plurality of coin denominations. If the comparing results in a match between the characteristics of the test coin and the characteristics of one of the coin denominations, then the test coin is declared to be that one of the coin denominations. If the comparing results in matches between the characteristics of the test coin and the characteristics of the test coin and the characteristics of more than one of the coin denominations, then the matches are compared to each other to determine which of the matches represents a valid match. The test coin which represents the valid one of the matches is declared the denomination of the test coin. 
     A method of discriminating denominations of coins, according to another aspect of the invention, includes providing a plurality of sample coin assemblies in a test coin sensor, each of the sample coin assemblies is adapted to hold a coin to be detected and includes a sample coin coil assembly. The test coin coil assembly is adapted to sense a coin to be detected and includes a test coin coil assembly. The method further includes comparing the test coin coil assembly with each of the sample coin coil assemblies with a microprocessor-based control and determining whether a test coin at the test coin sensor matches a sample coin at one of the sample coin assemblies. The method further includes determining whether any of the coins at more than one of the sample coin assemblies indicates a match with the coin at the test coil sensor during the entire time the test coin is at the coil sensor and which of the coins at more than one of the sample coin assemblies first indicates a match with a coin at the test coin sensor. 
     By resolving indications from multiple matches between the test coin and more than one denomination, the present invention is capable of determining which of the denominations truly matches the test coin. The present invention is capable of being scaled to accept one or more coin denominations and a token and can be expanded theoretically up to an unlimited number of coins and any combination of coins and tokens to be accepted. 
     These and other objects, advantages and features of this invention will become apparent upon review of the following specification in conjunction with the drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevation of a coin analyzer according to the invention; 
     FIG. 2 is a side elevation opposite that side shown in FIG. 1; 
     FIG. 3 is a sectional view taken along the lines III—III in FIG. 1; 
     FIG. 4 is a sectional view taken along the lines IV—IV in FIG. 3; 
     FIG. 5 is an end elevation indicated at V—V in FIG. 4; 
     FIG. 6 is a block diagram illustrating a microprocessor-based control according to the invention; 
     FIG. 7 is a diagram illustrating comparisons of multiple channels, each indicating a match with the test coin; 
     FIGS. 8 a - 8   c  are flowcharts illustrating a control algorithm according to the invention; and 
     FIGS. 9 a - 9   d  are a detailed electrical schematic diagram of the control in FIG.  6 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now specifically to the drawings, and the illustrative embodiments depicted therein, a coin analyzer  10  includes a chassis, or frame,  12  which defines a coin path, or guide path,  14  extending from a coin receiving slot  16  in a faceplate  17  and terminating in a coin reject slot  18  and a coin acceptance slot  20  (FIGS.  1 - 5 ). The term coin is intended to include not only legal tender, but, also, various tokens, and the like. The coin reject slot  18  is also in faceplate  17 . The coin acceptance slot  20  extends to a cash box (not shown). An electromagnetic device, referred to as a kicker coil  21 , is activated in order to deflect a coin inserted in coin path  14  to acceptance slot  20 . If kicker coil  21  is not activated, then the coin falls to coin rejection slot  18 . It should be understood that the invention could also be used with the reverse logic in which kicker coil  21  must be activated in order to reject a coin. 
     Coin analyzer  10  additionally includes a microprocessor-based control  22  including an electronic module  24 , a test coin sensor  26 , and a plurality of sample coin assemblies  28   a - 28   c . Test coin sensor  26  has a test coil assembly which generates a test field and senses a test field with a test coil in coin path  14 . In the illustrated embodiment, this is accomplished by separate field-generating coil  30   a  and sensing coil  30   b . However, other configurations of a test coil sensor known in the art may be employed such as one that both generates a field and senses the field with one coil. Each sample coil assembly  28   a - 28   c  includes a sample coin holder  32  and a sample coil assembly  34  which generates a sample field and senses a sample field as modified by the coin position in the associated sample coin holder  32 . In the illustrated embodiment, separate sample field-generating coils  36   a  and field-sensing coils  36   b  are provided. However, other sample coil configurations may be utilized. Test coil sensor, sense sample coil assembly and kicker coil  21  are generally as described in commonly assigned U.S. Pat. Nos. 4,884,672 and 5,056,644, the disclosures of which are hereby incorporated herein by reference. 
     Electronic module  24  includes a solid-state electronic circuit  38  enclosed within a housing  40  which may be sealed to avoid the entry of moisture for particular applications, such as car washes, laundry machines, and the like. Electronic module  24  may additionally include a display  42  for use in setting up the operating parameters, such as programming the value for each channel established by its respective sample coin or token and other parameters. Display  42  additionally provides an audit function during operation of coin analyzer  10 , such as identifying the number of coins that have passed through the coin analyzer per channel and the like. Electronic module  24  additionally includes switches  44   a - 44   c  which are useful in programming electronic module  24 . Adjustment screws  46  are used to tune a particular coin in each of the sample coin holders  32  to the same coin position at test coin sensor  26 . 
     Sample coin assembly  28   b  is vertically reversed with respect to sample coins  28   a  and  28   c  in its position on chassis  12 . This provides preferable routing of wires to and from the sample coin holders as well as provides ease of access to the sample coin holders for inserting and removing sample coins therefrom. Additionally, sample coin assemblies  28   a - 28   c  are all horizontally aligned on chassis  12 . This facilitates use of coin analyzer  10  with either a short-drop faceplate or a long-drop faceplate. 
     Chassis  12  is made up of a baseplate  48  and a side panel  50 . As seen in FIGS. 4 and 5, side panel  50  includes an opening  52  through which rejected coins are diverted and an offset side portion  54  which, in combination with a back surface of housing  40 , defines a rejected coin path. The rejected coin path also includes a sloped lower surface  56  for supporting rejected coins. Side panel  50  additionally includes side extensions  58  extending from one side thereof in order to space baseplate  48  from side panel  50  defining coin paths  14  therebetween. Side panel  50  additionally includes oppositely directed side extension  60  in order to provide offset support for housing  40  defining a rejected coin path therebetween. In the illustrated embodiment, side panel  50  is made from a generally transparent plastic material in order to provide visual access to the coin path for observance of jams and the like. 
     Microprocessor-based control  22  includes coils  30   a  and  30   b  of test coin sensor  26  and a pair of coils  36   a   1  and  36   b   1  of one sample coil assembly  34 , a pair of coils  36   a   2  and  36   b   2 , which make up another sample coil assembly  34 , and another pair of coils  36   a   3  and  36   b   3 , which make up yet another sample coil assembly (FIGS. 6-9 b ). If more than three sample coil assemblies  34  are utilized, they would be connected in a similar fashion as those illustrated in FIG.  6 . Coils  30   a ,  36   a   1 ,  36   a   2  and  36   a   3  are electrically series connected between a voltage source Vcc and a differentiated square wave generator  60 . In this manner, coils  30   a ,  36   a   1 ,  36   a   2  and  36   a   3  generate an electromagnetic field which is coupled respectively with the test coin and the three sample coins in sample coin holders  28   a - 28   c . Each of the coils  30   b ,  36   b   1 ,  36   b   2  and  36   b   3  are sensing coils which sense magnetic fields generated by the respective field-generating coils  30   a ,  36   a   1 ,  36   a   2 , and  36   a   3  as modified by the respective test coin and sample coins juxtaposed with the coils. Each coil  30   b ,  36   b   1 ,  36   b   2  and  36   b   3  has a common terminal connected together with a junction  62  between resistors R 7 , R 8  and R 9 . The other junction of coil  30   b  is connected at  64  with a non-inverting input of compare circuits  66   a ,  66   b  and  66   c . The other terminal of coil  36   b   1  is supplied to the inverting input of compare circuit  66   a . The other terminal of coil  36   b   2  is applied to the inverting input of compare circuit  66   b . The other terminal of coil  36   b   3  is connected with the inverting input of compare circuit  66 . Outputs  68   a ,  68   b  and  68   c  of respective compare circuits  66   a - 66   c  are supplied as channel inputs to a microprocessor  70 . microprocessor  70  has an output made up of a plurality of display lines  73  to provide data to display  42 . Microprocessor  70  additionally has an output to kicker coil  21  through a suitable interface thereof. Microprocessor  70  additionally produces an output  72  in order to operate differentiated square wave generator  60 . This allows the microprocessor to control the manner of operation of differentiated square wave  60 . In the illustrated embodiment, differentiated square wave  60  is operated at a constant 6 kilohertz differentiated square wave. 
     In operation, when a test coin traverses coin path  14 , it passes between coils  30   a  and  30   b . Each coil  36   b   1 ,  36   b   2  and  36   b   3  produces a signal which is compared with coil  30   b  by compare circuits  66   a - 66   c . If the test coin substantially matches the magnetic characteristics of one or more of the sample coins, the respective compare circuits  66   a - 66   c  will change output states on respective channel line  68   a - 68   c  as the test coin traverses  30   a  and  30   b . The output of compare circuits  66   a - 66   c  changes state only during the periods when a substantial similarity between the characteristics of the test coil and the respective sample coils. Therefore, each channel  68   a - 68   c  may change states only a portion of the time that the test coin is juxtaposed with test coils  30   a  and  30   b  and may change states multiple times during the traversing of coils  30   a ,  30   b  by the test coin. Also, if two or more of the sample coins are similar in property, more than one channel line  68   a - 68   c  may change states as a test coin traverses coils  30   a ,  30   b . For example, if a United States quarter is positioned in one of the sample coin holders  32  and a Susan B. Anthony dollar is positioned in another sample coin bolder  32 , it is possible that the respective outputs may both change states as a United States quarter or a Susan B. Anthony dollar traverses coin path  14 . 
     Channels  68   a - 68   c  are monitored by microprocessor  70  which includes a program  74  to determine which sample coin the test coin matches. If the test coin matches one of the sample coins, microprocessor  70  actuates kicker coil  21  to pass the coin or token to the cash box (not shown). Microprocessor  70  continuously samples outputs  68   a - 68   c  and begins to store the samples when one output changes state. Microprocessor  70  stores multiple samples of all outputs that are made during the period that a typical coin traverses the test coin sensor  26 . 
     In the illustrative embodiment, 10 samples are stored for all channels  68   a - 68   c  extending for a duration of 20 milliseconds, although other sample rates and periods may be selected by the skilled artisan. Diagram (1) in FIG. 7 shows the 2 millisecond samples stored by the microprocessor. Typically, one channel  68   a - 68   c  will change state as a test coin traverses test coin sensor  26 . However, if two or more sample coins have similar properties, more than one test channel  68   a - 68   c  may change states as illustrated in FIG.  7 . Diagrams (2) and (3) in FIG. 7 illustrate the situation where two output channels change state throughout the entire time that a test coin traverses test coin sensor  26 . Diagrams (4) and (5) in FIG. 7 illustrate the situation where one channel, in this case, channel A, momentarily changes state, but then returns to its original state, and then changes state again as the test coin passes the test coin sensor  26 . In diagrams (2) and (3) in FIG. 7, microprocessor  70  selects channel A as the proper match to the test coin. The reason is that, in the circumstance where both channels change state and maintain that change of state, the first channel to change states will be selected for reasons that will be discussed below. In the case of diagrams (4) and (5) where one channel momentarily changes state, but dips back to an original state prior to once again changing state, the microprocessor  70  selects the channel which maintains its change of state throughout the sampling process. Microprocessor  70  selects channel B, even though channel A initially changes state before channel B for reasons that will now be discussed. 
     The basis for the logic used by microprocessor  70  is as follows. When two channels change state and maintain the change of state throughout the test coin sampling, the first to change state is considered to produce the strongest signal and, therefore, the proper match with the test coin. When, however, one channel momentarily changes state, but reverts to its original state, and then again changes state, the channel which maintains the change of state is selected. This logic is based upon the belief that two coins of similar property are more likely to give an erroneous match indication during the leading and trailing edge of the coin as the coin traverses the sample coin assembly. For example, it has been discovered that the United States Susan B. Anthony dollar has very similar characteristics to a quarter at the leading and trailing edge of the dollar, but not when the dollar is centrally juxtaposed with the test coin sensor. Other relationships of multiple-activated channels may suggest themselves to the skilled artisan. 
     A flowchart of the control program run on microprocessor  70  is illustrated in FIGS. 8 a  and  8   b . Control program  74  begins by monitoring the phototransistor positioned downstream of coin acceptance slot  20 . If it is determined at  80  that the phototransistor is on, indicating that no coin is blocking the phototransistor, the program samples at  82  all coin channels on outputs  68   a - 68   c . If no channels are on, then the control program continues to sample all of the coin channels at a periodic rate. When it is determined at  84  that a coin channel is on, the microprocessor samples and saves the states of all three channels once every 2 milliseconds for a total of 20 milliseconds. When it is determined at  86  that a coin is present, the program determines at  90  whether channel  1  was on at any time and both channels  2  and  3  were off during all samples. If this condition is true, the program determines at  92  that the test coin matches channel  1 . If this condition is not true, then the program determines at  94  whether channel  2  was on at any time and both channels  1  and  3  were off during all samples. If this is true, then the program determines at  96  that the test coin matches  2 . If this is not true, then the program determines at  98  whether channel  3  was on at any time and both channels and  1  and  2  were off during all samples. If this is true, then the program determines at  100  that the test coin matches channel  3 . If this is not true, then the program concludes at  102  that there were signals on multiple channels and requires further evaluation to determine which of the matches is the correct match. 
     Program  74  then searches at  104  for samples for the first channel that was on and searches for samples for the second channel that was on. It is then determined at  106  whether the first channel was still on when the second channel was on. If it is determined at  106  that the first channel was still on when the second channel was on, the program determines at  108  that the test coin is the first channel seen. If it is determined at  106  that the first channel was not still on when the second channel was on, then it is determined at  110  whether the first channel was not on when the second channel was on. If the first channel was not on when the second channel was on, then the test coin is determined to be the second channel seen. If the determination at  110  is negative, the control rejects the coin (not shown). Likewise, if the control senses that more than two channels are on, the control concludes that the coin analyzer is not functioning properly and rejects the coin. 
     After a determination is made ( 92 ,  96 ,  100 ,  108 ,  112 ) of which channel matches the test coin, the control then turns the kicker coil on at  114  in order to let the coin pass through. The control then waits at  116  for the phototransistor to be on which indicates that a coin has dropped all the way through. If the phototransistor does not come on for 350 milliseconds, the control no longer waits for the phototransistor to be on. The kicker coil is turned off at  118  and it is determined at  120  whether the phototransistor is on. If it is determined at  120  that the photo-transistor is on, then the proper number of credit pulses is issued for the coin at  122 . Also, the audit total for the coin is updated. If it is determined at  120  that the phototransistor is not on, then all inputs are ignored for 1 second at  124 . 
     The microprocessor-based control  22  is illustrated in detail in FIGS. 9 a  and  9   b  in which FIG. 9 a  generally represents inputs to microprocessor  70  and FIG. 9 b  generally represents outputs of microprocessor  70 . In the illustrated embodiment, microprocessor  70  is a Microchip PIC series 8-bit microprocessor with 2K of internal ROM and used with an erasable read-only non-volatile memory array. Each compare circuit  66   a - 66   c  is made up of an operational amplifier whose output is supplied through a capacitor to a junction of two diodes. The other terminal of one diode is supplied to a potentiometer which is adjusted by one of adjustment screws  46 . The second terminal of the other diode is supplied as an input to the microprocessor. In this manner, the circuitry, including the sending and receiving coils, and the detecting circuitry is similar to that shown in commonly assigned U.S. Pat. Nos. 4,884,672 and 5,056,644. As an alternative, the output of each operational amplifier could be supplied directly as an input to microprocessor  70 . Instead of discrete logic states, the signal supplied to microprocessor  70  would represent an analog signal that increases or decreases as a substantial match is produced between the test coin and the sample coin in the respective sample coin holder. The microprocessor would process the analog signals to determine when a match occurs between the test coin and a sample coin in a manner that would be apparent to the skilled artisan. While this alternative embodiment has the advantage of eliminating certain components, it would increase the amount of program code required by microprocessor  70  to evaluate the outputs of the compare circuits. 
     Other variations may suggest themselves to the skilled artisan. For example, although control circuit  22  is illustrated with a microprocessor, an application specific integrated circuit (ASIC), logic array, or analog circuitry could be substituted for the microprocessor. As previously observed, although three sample coin holders are illustrated, fewer or a greater number of sample coin holders could be utilized. The present invention is adaptable for use in both a long-drop and a short-drop frame and is capable of use with any combination of coin denomination and token. It has been discovered that not only is the coin analyzer  10  capable of discriminating between coins of similar characteristics, it provides other improvement over the Slug Buster II marketed by Parker Engineering &amp; Manufacturing, Inc. of Grand Rapids, Mich. The sample coins in coin analyzer  10  can be readily positioned without the necessity for adjustment of the position of the coin, such as by the use of shims and the like. Alternatively, if shims are used to accurately position the sample coins in the sample coin holders, the requirements for potentiometers VR 1 -VR 3  and associated adjustment screws, used to adjust the potentiometers, can be eliminated and replaced with fixed resistors. 
     Although the invention is illustrated for use with technology which compares the output of a test coin sensor with sample coin assemblies, its principles could be applied to other technologies. For example, the principles of the invention could be used with a microprocessor-based control which compares the output of a test coin sensor with parameters of coin denominations stored in memory associated with the microprocessor, such as of the type disclosed in U.S. Pat. Nos. 5,433,310 and 5,909,793, the disclosures of which are hereby incorporated herein by reference. 
     Changes and modifications in the specifically described embodiments can be carried out without departing from the principles of the invention which is intended to be limited only by the scope of the appended claims, as interpreted according to the principles of patent law including the doctrine of equivalents.