Coin Discriminator

Abstract

A method and apparatus for discriminating between coins with respect to denomination and authenticity, employing means for performing two or more coin tests, means for storing a value dependent upon the results of the first coin test, and means for evaluating the results of the second coin test in a manner dependent upon the results of the first coin test.

Parent Case Text

This application is a continuation-in-part of my application Ser. No. 172,096, filed Aug. 16, 1971 now abandoned.

Description

This invention relates to coin discrimination devices and, more particularly, to a system for determining the denomination of coins and for rejecting undesired coins, counterfeit coins and non-coin objects.

Throughout this specification and in the appended claims, the term "coin" is intended to mean genuine coins, tokens, counterfeit coins, slugs, washers, and any other item which may be used by persons in an attempt to use coin-operated devices. An acceptable coin is an authentic coin of the monetary system in which the device is intended to operate and of a denomination which the device is intended selectively to receive for value.

It is one objective of this invention to provide a coin discrimination device which will accurately and reliably distinguish different denominations and which will reject unacceptable coins.

Another object of this invention is to provide a coin discrimination device having the capability of accepting a large number of coin denominations.

Another objective of this invention is to reduce the number of sensor device required in a coin discrimination device.

Another objective of this invention is to provide an electrical signal representative of the denomination of each acceptable coin for summation or actuation purposes.

SUMMARY

This invention is made in the context of the known concepts of distinguishing among differing coins by measuring characteristics dependent upon their physical dimensions, such as diameter, and their acceptance ratios. The acceptance ratio is defined as the ratio of the coin's electrical conductivity to its density.

This invention, in one form, utilizes the properties of the diameter of a coin and the velocity of the coin, after it has been subjected to a magnetic field, to determine its acceptability and denomination. When an electrically conductive coin enters the device, it is subjected to a relatively moving primary magnetic field. The coin's motion relative to the primary magnetic field induces eddy currents within the coin. The eddy currents produce secondary magnetic fields which interact with the primary magnetic field, producing a force on the coin. The effect of an electrically conductive non-ferromagnetic coin passing through a stationary magnetic field is the retardation of the velocity of the coin in an amount primarily dependent upon the acceptance ratio of the coin. A moving magnetic field, such as the impeller described below, may accelerate or regulate the velocity of a coin. The coin's velocity, when sensed downstream of the magnetic field, is a measure of coin authenticity and denomination. One means of examination of the coin velocity is a measurement dependent upon the time required for an edge of the coin to pass between two points at which detectors or sensors are located.

On means of measuring the diameter of a moving round or regular polygonal coin is to measure the time required for the coin to pass by a single sensor, providing a velocity dependent measurement of the chord of the coin at the height of the sensor above the coin support track. The chord of a coin can be measured in several other velocity dependent ways described below, all of which are referred to as chordal-velocity functions.

In one form of the present invention two signals are produced, each the result of one of two measurements. One signal is representative of a chordal-velocity function of the coin and one is representative of coin velocity. During the time period of the first measurement, a time dependent electrical signal such as pulses from a pulse source or clock is accumulated in a register. Based on a comparison of the number or value stored in the register following the first measurement with ranges of values representing various acceptable coin denominations a tentative determination can be made regarding which, if any, denomination of acceptable coin is being tested. During the time period of the second measurement, pulses or values are counted or accumulated and stored in a second register; the rate of change of the value of count stored in the second register being dependent upon the result of the tentative determination of coin denomination and instructions which are programmed or built into the coin discriminator. If the coin is an acceptable coin of the anticipated denomination, the total in that second register after the second measurement will be within an allowable range of the total stored in the first register. A signal is then provided to accept the coin.

Comparison of the result of the first and second measurements in this fashion in many cases permits the use of a more discriminating range of tolerance for acceptable coins than other techniques.

An advantageous way of storing the count numbers is to use a single up-down counter into which the number representative of the first measurement is counted and stored. The pulses representative of the second measurement are then used to reduce the number stored in the up-down counter. When an acceptable coin of the denomination indicated by the first measurement is tested, the number in the counter following both measurements will be within the predetermined acceptable tolerance of the starting value stored in the counter, e.g.: zero plus or minus some tolerance number.

In the drawings:

FIG. 1 is a front elevational and schematic block diagram of a coin discrimination device including a sensor array and electronic circuit in accordance with the first embodiment of this invention.

FIG. 2 is a front elevational diagram of the track and sensor array of the coin discrimination device of FIG. 1, indicating the outline of a typical coin at several positions.

FIG. 3a is a schematic block diagram of the two-bit counter and logic circuit of the first embodiment.

FIG. 3b is a schematic block diagram of the lower stages of the counter of the first embodiment.

FIG. 4 is a front elevational and schematic block diagram of a coin discrimination device including a sensor array and electronic circuit in accordance with the second embodiment.

FIG. 5 is a schematic block diagram of the divider and logic circuit of the second embodiment.

FIG. 6 is a schematic illustration of a linear motor coin impeller and coin sensors in accordance with the third embodiment.

FIG. 7 is a front elevational and schematic block diagram of a coin discrimination device including a sensor array, electronic circuit and a coin impeller in accordance with the third embodiment.

FIG. 8 is a schematic block diagram of an embodiment of a coin discrimination device which provides a predicted ratio to be used in determining coin authenticity and denomination.

It should be noted that the drawings are not intended to be dimensionally proportionate or scale representations of the devices illustrated. It will be clear to those skilled in the art, that, whereas the invention has been described in terms of AND and OR logic elements, alternative logical elements may be used without departing from the invention. Similarly, the word signal has been used in most cases to represent the relatively high output voltage of certain devices having two output voltages but the invention is not limited to the disclosed use of such signals.

First Embodiment

The coin discrimination device 10 is provided with an entrance slot for admitting coins, which fall to one end of the track 16 forming the bottom of a coin passage 15. An arresting pin 18 transverse of the coin passage 15 prevents coins from moving on through the coin passage 15 until it is removed.

It is often desirable to remove highly ferro-magnetic coins and objects, not part of the monetary system, before they go further. There are many coin scavengers known to the art which may be located in the path of coin travel for this purpose, for example the magnetic coin scavengers described in U. S. Pat. Nos. 1,956,066 and 3,168,180.

A coin presence sensor 21 is located in the vicinity of the arresting pin 18 in a position to sense the presence of any potentially acceptable coins stopped at the arresting pin. A suitable coin presence sensor 21 is a phototransistor placed on the one side of coin passage 15 opposite a source of light (not shown) on the other side of the passage; so positioned that any coin 20 to be further examined by the device will prevent light from passing from the light source to the sensor 21, i.e.: the sensor 21 will be obscured. An electrical signal from the sensor 21, representative of whether or not the sensor 21 is obscured, is transmitted to the start control 42. When the signal from the sensor 21 indicates that a coin is present, the start control 42 activates a solenoid (not shown) which retracts arrest pin 18 out of the way of the coin 20. At the same time a signal is sent from the start control 42 on lead 174 to reset the counter 160 to its starting condition.

In the present embodiment, the track 16 is sloped approximately 5.degree. downwardly from horizontal in the direction away from the entrance end having arrest pin 18. When the arrest pin 18 is moved aside, the electrically conductive non-ferromagnetic coin 20 moves down the track 16 under the force of gravity. A magnet 23 is located at a point further down the coin passage 15 than the arrest pin 18. Magnet 23 may be either a permanent magnet or an electromagnet, having a magnetic field component transverse to coin passage 15. As the coin 20 passes through the field from the magnet 23, the field induces eddy currents in a conductive coin which currents in turn produce a magnetic force. The action of the magnetic force between the coin 20 and the magnet 23 tends to slow the coin in an amount dependent upon the acceptance ratio of the coin. The velocity of a particular coin 20, having started from rest at the arresting pin 18, as it leaves the influence of the magnet 23 is primarily dependent upon the coin's acceptance ratio.

In order to determine the authenticity and denomination of coins, this embodiment relies upon two time related measurements, correlation of the data for the two measurements and comparison with data representative of the range of acceptable coins. While this description speaks of measuring time, I prefer to indirectly measure time by using electrical circuits which count pulses emitted from pulse sources at known time intervals.

The acceptance ratio of the coin and the diameter or a chord of the coin are two physical characteristics of the coin upon which the time measured in this embodiment depend. The velocity of a particular coin which has passed through the field magnet 23 is dependent upon the acceptance ratio. The time measurements desired are derived in coin discriminator 10 by occluding two coin presence sensors 66 and 67 spaced apart and located along the coin passage at a position where the coin velocity has been affected by coaction of the field of magnet 23 and the secondary magnetic field generated by eddy currents in the coin induced by motion in the field of magnet 23. Since the position of the two coin presence sensors 66 and 67 is fixed and known, the time between an event at the first sensor 66 and an event at the second sensor 67 has a linear dependence upon the average velocity of the coin during its passage between them and is, therefore, a function of the coin's acceptance ratio. For the purpose of this embodiment of the invention, the coin presence sensors 66 and 67 are phototransistors spaced apart in the direction of coin movement by a small enough distance so that both sensors 66 and 67 can be in an occluded state at the time (i.e.: concurrently occluded) from a light source (not shown) on the other side of the coin passage 15 during the passage of the smallest acceptable coin. A measurement of a function of the acceptance ratio can then be made by measuring the length of time that either one of the two sensors is occluded while the other sensor is not occluded (AB or AB). A measurement of a function of both acceptance ratio and chordal dimension of the coin can be made either (1) by measuring the total time that either one of the sensors is obscured (A or B) or (2) by measuring the total time that both of the sensors are obscured (AB). Since there are but two unknown variables, chordal dimension and velocity, any two of these three measurements will provide sufficient data to determine the characteristics of the coin. We prefer in this embodiment to first measure the time AB during which both sensors are occluded and then measure the period of time AB during which the second sensor 67(B) is occluded while the first sensor 66(A) is not. Coin discriminators may also be constructed in which the sensors are located so that one or more acceptable coins can not concurrently occlude both sensors, for which coins the duration of the time (AB after A) in which neither sensor is occluded, after the first sensor has been occluded and before the second sensor is occluded, may be employed for the first measurement.

Assuming the sensors 66 and 67 are at the same height h above the track 16, time AB is equal to the separation between the sensors divided by the average velocity of the trailing edge of a coin moving in the direction from sensor 66(A) to sensor 67(B). Time AB is equal to the difference between a chord across the coin at the height h of the sensors 66 and 67 above the track 16 and the separation between the sensors, divided by the average velocity V of the coin during the measurement period. Mathematically, these two times may be expressed:

AB = (C-S)/V and AB =S/V,

where S is the sensor spacing in the direction parallel to coin track 16, V is the coin's velocity and C is the chord length of the coin at the height h of the sensors 66 and 67 above the track, as indicated in FIG. 2. Sensors at two different heights can also be employed, in which case the time expressions can be easily calculated; for example AB = (C.sub.1 + C.sub.2 - 2S)/2V where C.sub.1 and C.sub.2 are the lengths of chords parallel to the track at sensor heights h.sub.1 and h.sub.2 respectively.

In FIG. 2, a coin moving toward the right in the figure on the track 16 past sensors 66 and 67 is shown by dashed outlines. The first coin outline 1 indicates the position of the coin at the beginning of period AB, the second outline 2 at the end of period AB, which is also the beginning of period AB, and the third outline 3 at the end of period AB.

When the first test or measurement of AB is completed, a tentative determination of the coin's denomination and authenticity is made. Subsequent tests then can be limited to the verification of authenticity and denomination with respect to the tentatively determined coin denomination or denominations.

If the result of the two tests are represented as quanta, such as numbers which can be stored in a counter; then the authenticity of a given denomination coin can be represented by a number, e.g.: the result of the first test, and a ratio of the two test results. In this embodiment, an up-down counter with provision for counting down at any of several powers of 2 is used. During the first time period AB, the amount in the counter is counted in one direction, up, at a fixed power of 2 as each pulse is received by the counter. During the second time period AB, the amount in the counter is counted in the other direction, down, as each pulse is received at a cyclical power of two, i.e. a predetermined sequence or cycle of powers of two as described below. The particular cycle of powers of two on successive counts is selected at the end of the first test with the expectation of producing a negligible positive or negative remainder for an authentic coin of the tentatively determined denomination.

The chord C along the line between the sensors is given by

C = .sqroot.4(D-h)h

where D is the coin diameter and h is the height of sensors 66 and 67 above the track 16. The several coin diameters are dictated by the currency, but the choice of appropriate sensor height h is of the device designer's chosing. For a three- or four-coin set it is possible to select a height h such that the chord lengths for the various coins will be nearly in an integral ratio to each other; the work "nearly" being used to indicate that most of the deviation from an exact integral ratio is attributable to the range of coin diameters which must be accepted to accommodate coin wear.

To ensure that success of the up-down counting technique, the spacing S between sensors 66 and 67 and the rate at which the number in the counter is increased during time period AB should be chosen so that the separations between sensors can be chosen to be multiples of 16 units on the scale of units in which the chord lengths of the several denominations are expressible as near integers.

If the sensor spacing S is taken as 16 units, and the chord length C of three coin denominations X, Y and Z are 32, 37 and 45 units respectively; then the chord length less sensor spacing (C-S) for coins X, Y and Z will be 16, 21 and 29 respectively and the ratios between first and second tests at a constant velocity V will be 16/16 = 1, 21/16 and 29/16 respectively. If in each given equal unit of time during the time period AB of the first test, the number in the counter is increased by 2.sup.4 = 16, then the cycle of powers of two for counting down during each such unit of time may be as follows:

AMOUNT COUNTED DOWN Tentatively Identified Cycle Step Number Denomination 1 2 3 4 Total Count X 2.sup.2 2.sup.2 2.sup.2 2.sup.2 16 Y 2.sup.3 2.sup.2 2.sup.3 2.sup.0 21 Z 2.sup.4 2.sup.0 2.sup.3 2.sup.2 29

when the coin being examined has been tentatively identified at the conclusion of the first test as a coin of denomination X; each time a pusle is received during the period of the second test, the amount in the counter is counted down by 2.sup.2 or four units since each of the cycle steps are the same. When the coin is tentatively identified as being of denomination Y, the amount in the counter is reduced by 2.sup.3 or eight units for the first pulse received, then four, then eight and then one unit for successive pulses. The cycle is then repeated for succeeding pulses. The effect of this four-step cycle of varying powers of two is to apply an average weight, dependent upon the result of the first test, to the pulses counted in the second test.

Referring to the diagram of FIGS. 1 and 3a, either when both sensors 66 and 67 are not obscured, or when only sensor 66 is not obscured, AND gates 33 and 34 do not produce any output signal. When both sensors 66 and 67 are obscured, however, signals for inverters 31 and 32 are applied to both inputs of AND gate 33 which therefore provides an output signal, identified here as AB. This output is applied to the one input of AND gate 35 and clock pulses from clock 40 are applied to the other input of AND gate 35. The output of AND gate 35 on lead 45 is a stream of clock pulses, identified here as ab, continuing for the entire period that both sensors 66 and 67 are occluded. These pulses ab are applied directly to the 2.sup.2 stage 163 of the binary up-down counter 160 through OR gate 132. Signal AB is simultaneously applied to the "up count" input lead 175 of the counter 160. As a result, each clock pulse during the period when both sensors 66 and 67 are obscured causes the number stored in the counter to increase by a factor 2.sup.2.

Each of the upper stages 166 through 171 of the counter is connected to both of the decoders 180 and 190. The first decoder 180 is used in connection with the measurement of the duration of occlusion of both sensors 66 and 67. Whenever the number stored in the upper stages 166 through 171 of the counter 160 is equal to the number for an acceptable coin of given denomination X, Y and Z within the prescribed tolerance, flip-flops 182, 184 or 186 is set respectively. The corresponding flip-flop 183, 185 or 187, however, is not set unless signal AB from AND gate 33 is removed from the reset inputs of flip-flops 183, 185 and 187 while the associated flip-flops 182, 184 and 186 is producing an output signal. When the signal AB is removed from the reset of the flip-flops 183, 185 and 187 while a signal is applied to the set input of one of those flip-flops, that flip-flop is set thereby recording that the coin tested has satisfied the first test for its associated denomination coin.

As soon as sensor 66 is no longer occluded, AND gate 33 is no longer activated and signals AB and ab cease. AT the same time, AND gate 34 is activated by the application to its inputs of the signal from sensor 66 and the signal from sensor 67 which has been inverted by inverter 32. The output signal AB from AND gate 34 and the output signal of clock 40 are applied to the inputs of AND gate 36 which then delivers a stream of clock pulses ab on lead 46 for the entire period when sensor 66 is not occluded and sensor 67 is occluded.

The pulses ab from AND gate 36 are applied to the input of the two-bit counter 100, which is described in greater detail below. The two-bit counter 100 is one which directs one of the pulses ab to each of the four output leads 111, 112, 113 and 114 in succession. These leads 111 through 114 are connected to logic circuit 120. The outputs of flip-flops 183, 185 and 187 are also connected to logic circuit 120 by leads 181, 188 and 189, respectively. The logic circuit is composed of AND and OR gates which direct the pulses from the two-bit counter to one or another of the lower stages 161 through 165 of counter 160, the particular scheme for directing the pulses depending on which of the flip-flops 183, 185 or 187 is supplying a signal to the logic circuit 120. Details of the logic circuit 120 are described below.

Signal AB is applied to the "down-count" input lead 176 of the counter 160 simultaneously with the pulses from logic circuit 120. As a result, the pulses from the logic circuit 120 reduce the number stored in the counter 160. The logic circuit 120 is designed so that when the coin tested in an acceptable coin of the denomination indicated by the output of one of flip-flops 183, 185 and 187, set at the conclusion of the first test; at the conclusion of the second test the remainder stored in the counter 160 for an acceptable coin will be within a relatively small tolerance of the number stored at the start, zero in this example, Decoder 190 decodes the output of the upper stages 166 through 171 of the counter 160, and produces an output signal when the binary numbers stored in all of those stages is the same -- either all 0's or all 1's. In that case, of course, the number stored in the counter is zero within the tolerance of the maximum number, here 31 counts, which can be stored in the lower stages 161 and 165 of the counter 160. Different tolerances can be obtained by changes in which are decoded. For example, if stage 165 is also decoded the tolerance would be 15 counts, or alternatively if stage 166 is not decoded the tolerance would be 63 counts. By suitable arrangements of gates between outputs of the counter 160 and the second decoder 190, it is possible to obtain intermediate tolerances. Similar means may be employed in conjunction with the output signals from the flip-flops 183, 185 and 187 to provide for different tolerances for different denomination coins.

When decoder 190 produces an output signal setting flip-flop 191 which applies a signal to the input of AND gates 192, 194 and 196. One of these gates is also receiving an input signal from its respective flip-flop 183, 185 and 187. That AND gate will then produce an output signal. The outputs of the AND gates 192, 194 and 196 are connected respectively to the set inputs of flip-flops 193, 195 and 197. The reset input of these flip-flops is connected to the output of AND gate 34 which supplies signal AB the duration of the period when sensor 66 is not occluded while sensor 67 is occluded. If signal AB is applied to the reset input of the flip-flops 193, 195 and 197 when one of those flip-flops receives a set input signal from its respective AND gate 192, 194 and 196 respectively, the flip-flop will not be set. If, however, signal AB is not being applied to the reset input when such a signal is applied to the set input, the flip-flop will be set, indicating that the coin tested has passed both tests for a coin of the denomination associated with the flip-flop.

The outputs of flip-flops 193, 195 and 197 actuate the accumulator circuit 200, which accounts for the value of the coin examined and actuates the coin operated device 210 when coins summing to a predetermined total value have been examined and found acceptable

FIG. 3a shows details of a two-bit counter 100 and a logic circuit 120 for this embodiment of the invention. Two-bit counter receives pulses ab on lead 46 from AND gate 36 at the input of the flip-flop 101. When the first pulse is received after the flip-flop has been reset, a pulse is produced at the output terminal connected to the inputs of flip-flop 102 and AND gates 105 and 106. Similarly, flip-flop 102 produces an pulse at the output terminal connected to AND gate 106. The coincidence of pulses on the two inputs of AND gate 106 activates the gate and a pulse appears at its output. The next pulse received by flip-flop 101 causes a pulse to appear on its other output, which is connected to AND gates 103 and 104. Flip-flop 102 remains set a before, therefore a coincidence occurs on the inputs of AND gate 104. The third pulse received by flip-flop 101, causes a pulse to appear again on the first output terminal. Flip-flop 102 is thereby caused to produce a pulse on its output terminal connected to AND gates 105 and 103. Since a coincidence occurs on the input terminals of AND gate 105, a pulse appears at its output. When the fourth pulse appears at the input of flip-flop 101, an output pulse is produced at its second output terminal. Flip-flop 102 remains in the same state as on the previous pulse. There being a coincidence at the inputs of AND gate 103, a pulse appears at its output. The fifth input pulse restarts the cycle, and therefore causes a pulse to appear at the output of AND gate 106.

Logic circuit 120 "weights" the pulses during the period of the second measurement by directing them to the various stages of the up-down counter 160. One of the leads 181, 188 and 189 brings to the logic circuit 120 the signal identifying the possible denomination of the coin being tested from flip-flops 183, 185 and 187. When, for example, a signal appears on lead 189, AND gates 126, 127, 128 and 129 can pass pulses coming from AND gates 106, 104, 105 and 103 respectively of two bit counter 100. AND gates 126, 127, 128 and 129 are connected with OR gates 134, 130, 133 and 132 respectively, in accordance with a scheme which will produce a total change of 29 in the number stored in the counter 160 during the period of four input pulses to the two-bit counter 100. The output of AND gate 126 is connected to an input of OR gate 134, which in turn is connected to the 2.sup.4 stage 165 of the counter 160. The output of AND gate 127 is connected to the input of OR gate 130 which in turn is connected to the 2.sup.0 stage 161. The output of AND gate 128 is connected to the input of OR gate 133 which in turn is connected to 2.sup.3 stage 164. The output of AND gate 129 is connected to the input of OR gate 132, which in turn is connected to 2.sup.2 stage 163.

Similarly, when lead 188 carries a signal from the output of flip-flop 185, AND gates 122, 123, 124 and 125 can be activated by pulses from the two-bit counter 100. These gates will then direct the pulses to OR gates 133, 132, 133 and 130 respectively; which in turn transmit the pulses to counter lower stages 164, 163, 164 and 161 respectively, changing the number stored in the counter by a total of 21 for every four pulses applied to the input of the two-bit counter 100.

In the event that the desired countdown number is the same as the count-up number, the two-bit counter may be bypassed and a single AND gate 121 will suffice to connect the ab pulses to the appropriate OR gate 132, when a signal appears on lead 181, and thence to the corresponding stage 163 of the counter 160.

The lower stages 161, 162, 163 and part of 164 of counter 160 are shown in greater detail in FIG. 3b, to illustrate up-down counter means having stages with parallel inputs. Assume that initially all of the flip-flops 411 421, 431 and 441 shown here have been reset to the "zero" state, i.e.: that output leads 417, 427, 437 and 447 each has a relatively high voltage relative to the other output leads 416, 426, 436 and 446 of the same flip-flops; in other words, that the counter has stored the binary number 0000. When a continuous signal is applied to the up-lead 175 and concurrently a pulse is applied to logic circuit output lead 135, the state of flip-flop 411 changes to a "one" and its output signal now appears on lead 416. Since none of the up AND gates 422, 432 and 442 or the down AND gates 423, 433 and 443 is activated, none of the other flip-flops 421, 431 and 441 is activated and able to be triggered; although the pulse is applied to the trigger input of each via OR gates 420, 430 and 440. The simultaneous application of signals from leads 175 and 416 on the inputs to AND gate 422 causes it to transmit a signal to AND gate 432 and via OR gate 424 to the activating gates of flip-flop 421 in the next higher counter stage 162. If another pulse then appeared on lead 135, it would trigger flip-flop 411 directly and be able to trigger flip-flop 421 via OR gate 420. AND gate 422 would no longer be activated and therefore flip-flop 421 would not be triggered by the next subsequent pulse on lead 135. It will be clear to those skilled in the art that during up-counting each higher stage is activated by AND gates in the group of gates 422, 432 and 442 so as to be triggered by the next pulse when all lower stages are in the "one" state; and that downcounting operates in a similar fashion, utilizing the downcount signal on lead 176, the down AND gates 423, 433 and 443, and the flip-flop output leads 417, 427 and 437. It will also be readily apparent from FIG. 5 that signals applied to lead 136 operate in the same fashion as signals applied to lead 135; however, signals on lead 136 can affect only the state of stage 162 and higher stages, and that the same holds true for leads 137 and 138 with respect to stages 163 and 164, respectively, as a result of the series of OR gates 420, 430 and 440.

Second Embodiment (FIGS. 4 and 5)

The coin discriminator 300 comprising a second embodiment of this invention is similar to the coin discriminator 10 of the first embodiment described above in that the criteria used for accepting and categorizing coins of predetermined denomination are the same and a related combinatorial circuit is utilized. The movements of the coin being examined by the coin discriminator 300 of this embodiment are the same as in the case of the coin discriminator 10 of the first embodiment, and the operation and location of the sensors 66 and 67 of the coin discriminator are also the same. Where the same number is employed to describe an element of two different embodiments of this invention, the element described is the same in both embodiments.

When either both sensors 66 and 67 are not obscured, or when only sensor 66 is not obscured, AND gates 33 and 34 do not produce any output signal. When both sensors 66 and 67 are obscured, however, signals from inverters 31 and 32 are applied to both inputs of AND gate 33 which therefore provides an output signal on lead 37, identified here as AB.

As soon as sensor 66 is no longer occluded, AND gate 33 is no longer activated and signal AB ceases. At the same time, AND gate 34 is activated by the application to its inputs of the signal from sensor 66 and the signal from sensor 67 which has been inverted by inverter 32. The output signal AB on lead 38 from AND gate 34 is then produced for the entire period when sensor 66 is not occluded and sensor 67 is occluded.

Referring now to FIG. 5, throughout the period of coin examination clock pulses flow at a predetermined, fixed rate through lead 341 from the pulse generator or clock 340 (shown in FIG. 4) to the divider 310. A divider 310 suitable for this embodiment is a chain of flip-flops 321, 322, 323, 324 and 325. Clock pulses from lead 341 are applied to the input of the first flip-flop 321, producing pulses alternatively on its two outputs. One output of flip-flop 321 is connected to divider output lead 311 and the other to the input of flip-flop 322. Similarly, the one output of flip-flop 322 is connected to the output lead 312 and the other to the input of flip-flop 323; one output of flip-flop 323 is connected to output lead 313 and the other to the input of flip-flop 324; and one output of flip-flop 324 is connected to output lead 314 and the other to the input of flip-flop 325. One output of flip-flop 325 is connected to output lead 315 and the other is unused. As a result 2.sup.4, 2.sup.3, 2.sup.2, 2.sup.1 and 2.sup.0 non-coincident pulses appear on divider output leads 311, 312, 313, 314 and 315, respectively, for every 2.sup.5 pulses applied to the input of flip-flop 311.

The output signal AB on lead 37 is applied to an input of OR gate 350 of the logic circuit 320. The AND gates 331 through 338 of the logic circuit 320 comprise a matrix for gating on pulses from the divider 310 when signals are received at the output of OR gate 350 or on lead 188 or lead 189. The outputs of AND gates 331 through 338 are all connected to the inputs of OR gate 355.

The signal at the output of OR gate 350 is applied to the one input and pulses from divider output lead 311 are applied to the other input of AND gate 331. The output of AND gate 331 is a stream of 2.sup.4 pulses (16 in decimal notation) for every 2.sup.5 clock pulses for the duration of signal AB. Since there are no input signals on lead 188 and 189, as will later be apparent, the pulses on logic circuit output lead 356 from OR gate 355 appear at the same rate as the pulses from AND gate 331. These pulses are applied directly to the pulse input of the binary up-down counter 360. Signal AB is simultaneously applied to the "up count" input lead 175 of the counter 360. As a result, for every 2.sup.5 clock pulses during the period when both sensors 66 and 67 are obscured causes the number stored in the counter to increase by 2.sup.4.

Each of the upper stages 366 through 371 of the counter is connected to both of the decoders 180 and 190. The first decoder 180 is used in connection with the measurement of the duration of occlusion of both sensors 66 and 67. Whenever the number stored in the upper stages 366 through 371 of the counter 360 is equal to the number for an acceptable coin of given denomination X, Y or Z within the prescribed tolerance, flip-flops 182, 184 or 186 is set respectively. The corresponding flip-flop 183, 185 or 187, however, is not set unless signal AB from AND gate 33 is removed from the reset inputs of flip-flops 183, 185 and 187 while its associated flip-flop 182, 184 or 186 is producing an output signal. When the signal AB is removed from the reset of the flip-flops 183, 185 and 187 while a signal is applied to the set input of one of those flip-flops, that flip-flop is set thereby recording that the coin tested has satisfied the first test for the indicated denomination coin.

When AND gate 34 is activated by the application to its inputs of the signal from sensor 66 and the signal from sensor 67 which has been inverted by inverter 32; the output signal AB on lead 38 is applied via lead 176 to the down-count terminal of up-down counter 360, causing the counter 360 to count down on subsequent pulses received from logic circuit 320 on lead 356.

In the event that the first measurement was acceptable for one of the coins X,Y or Z, one of the leads 181, 188 or 189 will carry a signal indicative of potential acceptability of a coin of the type which it is associated.

The signals on each of the leads 181, 188 and 189 is connected to certain of the AND gates 331 through 338, directly in the case of leads 188 and 189 and indirectly via OR gate 350 in the case of lead 181; the particular locations of the AND gates in the matrix having been chosen to produce the desired ratio of pulses per unit time during the second measurement to those during the second measurement to those during the first measurement. When a signal indicative of coin X appears on lead 181, AND gate 331 is activated and 2.sup.4 pulses (16 pulses) for every unit of time represented by 2.sup.5 clock pulses appear at its output and are directed via OR gate 355 and lead 356 to the pulse input of up-down counter 360. When a signal indicative of coin Y appears on lead 188, AND gates 332, 333 and 334 are activated, gating on non-coincident pulses at rates of 2.sup.4, 2.sup.2 and 2.sup.0 per unit time respectively; producing 21 pulses per unit time which are similarly directed to counter 360. When a signal indicative of coin Z appears on lead 189, AND gates 335, 336, 337 and 338 are activated, gating on non-coincident pulses at rates of 2.sup.4, 2.sup.3, 2.sup.2 and 2.sup.0 respectively; producing 29 pulses per unit time which are similarly directed to counter 360. In the event that no signal is applied to leads 181, 188 and 189 during the period of signal AB, indicating that the coin being examined was not determined to be potentially of denomination X, Y or Z in the first measurement; no pulses are directed to counter 360 by logic circuit 320 during this period.

The logic circuit 320 is designed so that at the conclusion of the second test the remainder stored in the counter 360 will be within a relatively small tolerance of the number stored at the start of the first test, zero in this example, when the coin tested is an acceptable coin of the denomination indicated by the output of one of flip-flops 183, 184, and 185 which was set at the conclusion of the first test. The decoder 190 and subsequent stages of the coin discriminator 300 of this embodiment are the same as the corresponding elements of the coin sensor 10 of the first embodiment, and their operation is the same.

Third Embodiment

The coin discrimination device of this invention places coin sensors in or following a region of coin acceleration or deceleration. This third embodiment employs a linear motor or impeller 480 to produce an apparently moving magnetic field which is used to accelerate the non-magnetic, electrically conductive coins with which the device is used. The linear motor or impeller 480 is similar to a stator of a conventional cylindrical electric motor which has been cut along a radial plane and rolled out flat. As is illustrated in FIG. 6, such an impeller 480 comprises two series of coils, a first series including coils 482 and 484 and a second series including coils 486 and 488. While only two coils per series are illustrated, a greater number of coils is preferred, for example, about four per series. The coils are wound around a low carbon steel impeller core 490 having projecting pole pieces or core fingers 492 through 495 spaced longitudinally along the desired direction of coin travel. A low reluctance magnetic shunt or magnetic return path 498 is placed at the side of the coin track 499 opposite the impeller 480 to provide a uniform magnetic field across the coin passageway. The magnetic shunt may be made of a low carbon steel plate.

In order to produce a traveling magnetic field, it is necessary for adjacent fields to have a phase shift relationship. FIG. 6 illustrates a circuit which is suitable for providing approximately a 90.degree. phase shift between adjacent core fingers. It can be seen that the first series of coils 482, 484 is wound in alternating fashion, in other words, coil 482 is wound in a counterclockwise direction about core finger 492 while coil 484 is wound clockwise about core finger 494. The second series of coils 486, 488 similarly is wound in alternating fashion, namely coil 486 is wound counterclockwise about core finger 495.

Either the first series or the second series of coils can be individually selectively connected directly to a source of cyclically varying current, for example, chopped D.C. or single phase sinusoidal A.C. current source 500, such as by AND gate 502 and AND gate 504 respectively, which are controlled by signals from start control circuit 506. The two series are connected in parallel through a capacitor 508 thus placing the capacitor in series with the coil series not directly gated on. The capacitor 508 provides a 90.degree. phase shift between the two series of coils. Because of the reversed direction of windings of adjacent coils within a series and the phase shift between the coil series provided by the capacitor 508, the magnetic field is effectively traveling in one direction. For example, at one instant of time assuming the polarity of the first coil 482 is north, the polarity of coil 486 is north plus 90.degree., the polarity of coil 484 is south and the polarity of coil 488 is south plus 90.degree.. The thrust direction of impeller 480 is reversed by merely enabling the presently disabled AND gate and vice versa. This permits selection of a desired thrust direction for purposes described below.

To provide consistent coin tests, it is preferable to activate the impeller 480 each time at the same fixed point in the impeller current wave form. In this way the resultant coil acceleration and velocity is not dependent upon the particular moment of time when the coin is first exposed to the magnetic field of the impeller. The zero crossing detector 509 is designed to detect the zero crossing of the impeller current in the direction providing desired initial polarity. The zero crossing detector 509 includes a saturation amplifier, a diode and differentiator to select the desired direction of transition and a latching relay operated by the output of the differentiator.

Turning now to FIG. 7, a coin selector system 510 particularly suitable for electrically conductive, nonferromagnetic coins, utilizing a linear motor impeller 480, is schematically illustrated. A coin entering the system through an entrance slot 512 drops vertically downward through an entrance meander section 514 which slows the coin and removes most of its energy. The coin passes an arrival sensor 516 such as a photocell which senses the presence of the coin in the system and, through an amplifier 518, energizes a start control system 520 which, in turn, energizes the impeller 480 after a slight delay. After passing the arrival sensor 516 the coin drops onto a coin support track 522. The support track is designated with an initial short section 524 having an inclined slope of between 0.5.degree. - 5.0.degree., preferably approximately 1.5.degree., followed by a declining longer portion having a declination of approximately the same slope. The coin drops onto the initial portion 524 and, due to the inclination, rolls rearwardly (toward the left in FIG. 7) until it comes to rest against a wall 528. The system is designed with a delay in energizing the impeller such that the impeller is energized after sufficient time has elapsed for the coin to come to rest against the wall 528. The impeller is located with respect to the track 522 such that portions of at least two pole faces are adjacent the resting place of the smallest coin desired to be accepted by the coin selector. Once the impeller is energized, the coin, if electrically conductive and nonferromagnetic, will be caused to move along the track 522 by rolling up the inclining portion 524 and then down the declining portion 526. The coin movement is produced by eddy current induced in the coin which produces an associated magnetic field. The induced coin voltage is time derivative which causes the coin's magnetic field to have approximately a 90.degree. lagging phase shift resulting in an attraction between the forwardly adjacent coil and the coin which causes the coin to move toward that coil. The rate of acceleration of the coin and its velocity as it leaves the impeller 480 is determined by the coin's acceptance ratio for the reasons discussed above.

While a suitable application for the coin discrimination device of this invention would be to use it with sensors positioned to sense coins after leaving the impeller 480, in this embodiment the sensors are located within the accelerating region of the impeller 480. In this discussion two spaced photosensitive devices 532 and 533 are used as sensors. A single source of collimated light (not shown) is located on the opposite side of the track 522 from the sensors 532 and 533, which are located within pole pieces 494 and 495 of the impeller 480. The sensors 532 and 533 are connected to electronic circuit 550, which may be the circuitry following the sensors other than the arrival sensors disclosed in any of the previous embodiments.

This embodiment applies the same sensing and counting techniques and devices as the first two embodiments; however, when the sensors 532 and 533 are located within the region of acceleration or deceleration, the simpler formulae described with respect to the earlier embodiments are not applicable. The optimum sensor positions and ratios between the count numbers of the first and second tests are, therefore, most easily determined empirically.

A useful variation of the coin selector employing means to accelerate coins, such as an impeller, can be constructed with only one sensor in the coin examining system. The impeller accelerates the coin in a manner deendent upon the coin's properties from a known velocity at a known position, for example, resting against a wall on a track, similar to wall 528 and track 522 in FIG. 7, so that the coin moves along the track and past a sensor which, for example, may be located in the position of sensor 532 or sensor 533. The duration of two periods, the one dependent at least upon the coin's average velocity between the starting point and the sensor and the other dependent upon a chordal velocity function may be employed with any of the circuit techniques previously described to identify genuine coins of permissible denominations. The period of time from the start of acceleration of the coin from rest to the first occlusion of the sensor and the period of occlusion of the sensor are particularly suitable for this purpose.

As an alternative to turning off the impeller after a given number of cycles, the impeller force can be reversed at that time to apply a decelerating force on the coin for a further fixed period of time. This latter technique can be used to provide an even greater separation between coins of differing characteristics, such as denomination and authenticity.

Fourth Embodiment

The coin discriminator 600 comprising a fourth embodiment of the present invention is illustrated in FIG. 8. Where the same number is employed to describe an element of this embodiment as was used with a previous embodiment, the element is the same in both embodiments.

Throughout the period of coin examination clock pulses flow at a predetermined, fixed rate, e.g., at a frequency of 3 MHz, from the pulse generator or clock 640 through lead 641 to a counter, six-bit counter 610, i.e., a counter having a capacity of six-bits which is equivalent to a count of 64 in decimal notation. The output pulses which are produced by the six-bit counter 610 when it is filled to its capacity are applied to the unit input 661 of an up-down counter 660.

During the time period when the up-down counter 660 is counting up, the six-bit counter 610 is initially preset to a predetermined number, in this example 30, by conventional logic circuitry 620. 34 additional clock pulses can then be counted by the counter before an output pulse is produced. The output pulse or overflow from the six-bit counter 610 is the input to the up-down counter 660. At overflow the six-bit counter 610 is automatically cleared and is preset to 30 by signals on leads 611-616 from logic circuitry 620 and further counting proceeds. Thus, the content of the up-down counter 660 at the end of the counting up period will be 1/(64-30) or 1/34 of the number of 3 MHz pulses fed to the six-bit counter 610.

The content or count in the up-down counter 660 at the end of the counting up period tentatively identifies the coin and thus establishes the predicted ratio of the section time interval T.sub.2 (counting down) to the first time interval T.sub.1 (counting up). This predicted ratio for the coin determines the quantity with which the six-bit counter 610 is preset or preloaded by logic circuitry 620 each time it overflows during the period of counting down. For example, if the nominal value of T.sub.1 for a given coin denomination is 0.68 second and T.sub.2 is 0.90 second, and the preset during up counting is 30; then the expected ratio for that denomination is T.sub.1 /T.sub.2 = 34/45. Since approximately the same number of pulses must be supplied to the up-down counter during up and down counting if the coin is to be accepted, the preset or preload of the six-bit counter is used to compensate for the difference in the number of pulses supplied by the clock 640 in the two periods. Since the preload during the period of counting up was 64-34=30; the preload during counting down should be 64-45=19. The authenticity and denomination of the coin is established if the content of the up-down counter 660 is at or near the value at the start of counting up, typically zero, at the end of the counting down period.

The signals for clearing the up-down counter 660 and defining the counting up period and the counting down period are fed into the up-down counter 660 by lead lines 37, 178 and 38, 176 as previously described. Lead 37a feeds a signal to logic circuitry 620 to cause presetting of the six-bit counter 610 to the desired preset during the first time interval or counting up period, e.g.: 32. During the second time interval or counting-down period, a signal on one of leads 181, 188 or 189 causes presetting of the six-bit counter to the desired preset for that period; the particular lead 181, 188 or 189 which is activated and the preset thereby established depending on the tentative determination at the end of the counting-up period.

At the conclusion of each counting period, the content of the up-down counter 660 is transmitted to the decoders 180 and 190 where the content is compared with expected values. The operation and construction of decoders 180 and 190 and the following circuitry is as previously described in connection with FIGS. 1 and 4.

Claims

I claim:

1. A method of discriminating among coins with respect to denomination, authenticity and the like comprising the steps of

examining a first characteristic of a coin and producing a first value which is a quantitative function of said first characteristic,

examining a second characteristic of the coin and producing a second value which is a quantitative function of said second characteristic,

comparing the first value with the second value, and

producing an output signal indicating whether the difference between the compared values is within a predetermined range.

2. The method of claim 1 wherein first and second values are each represented by a first and a second electrical pulse signal, respectively.

3. The method of claim 2 which includes the steps of counting the pulses comprising the first pulse signal and establishing the pulse rate of the second signal as a function of the total count of the first pulse signal.

4. The method of claim 3 which includes the steps of counting the pulses of one pulse signal in a first counter, counting the pulses of another pulse signal in a second counter, and comparing totals of the counters.

5. The method of claim 3 which includes the steps of counting the pulses of the first pulse signal in one direction into an up-down counter, counting the pulses of the second pulse signal in the opposite direction into that counter, and comparing the remainder in the counter with a predetermined range.

6. The method of claim 3 wherein the second signal is produced by the steps of presetting a counter, counting the pulses from a pulse source into the counter, and producing a pulse each time the counter reaches a predetermined number.

7. The method of claim 3 which includes the steps of preloading a first counter to a predetermined number, counting the pulses from a pluse source into the first counter, producing an output pulse from the first counter each time it is filled, and counting the output pulses of the first counter with a further counter.

8. The method of claim 7 in which a first counter produces pulses comprising the first pulse signal during one period of time and pulses comprising the second pulse signal during another period of time, and in which the first counter is preloaded during counting of the pulses of the first pulse signal with a first predetermined number and preloaded during counting of the pulses of the second pulse signal with a second predetermined number which is dependent upon the total count of the first pulse signal in the second counter.

9. The method of claim 2 which includes the steps of counting the pulses comprising the first pulse signal and counting the pulses comprising the second pulse signal in accordance with a weight dependent upon the total count of the first signal.

10. The method of claim 9 wherein the weights accorded the pulses in counting are each powers of two.

11. A method of discriminating among coins with respect to denomination and authenticity comprising the steps of

causing a coin to move at a velocity dependent upon the interaction of the coin with a relatively moving magnetic field,

producing at least two values derived from at least two signals, each signal being representative of a time necessary for the coin to move a distance, at least one of the distances being dependent upon the diameter of the coin being examiner,

comparing the values with each other, and

producing an output signal if the difference between the compared values is within a predetermined range.

12. The method of claim 11 wherein first and second values are each represented by first and a second electrical pulse signal, respectively.

13. The method of claim 12 which includes the steps of counting the pulses comprising the first pulse signal and establishing the pulse rate of the second signal as a function of the total count of the first signal.

14. The method of claim 13 which includes the steps of counting the pulses of one pulse signal in a first counter, counting the pulses of another pulse signal in a second counter, and comparing totals of the counters.

15. The method of claim 13 which includes the steps of counting the pulses of the first pulse signal in one direction into an up-down counter, counting the pulses of the second pulse signal in the opposite direction into that counter, and comparing the remainder in the counter with a predetermined range.

16. The method of claim 13 wherein the second signal is produced by the steps of presetting a counter, counting the pulses from a pulse source into the counter, and producing a pulse each time the counter reaches a predetermined number.

17. The method of claim 13 which includes the steps of preloading a first counter to a prdetermined number, counting the pulses from a pulse source into the first counter, producing an output pulse from the first counter each time it is filled, and counting the output pulses of the first counter with a further counter.

18. The method of claim 17 in which a first counter produces pulses comprising the first pulse signal during one period of time and pulses comprising the second pulse signal during another period of time, and in which the first counter is preloaded during counting of the pulses of the first pulse signal with a first predetermined number and preloaded during counting of the pulses of the second pulse signal with a second predetermined number which is dependent upon the total count of the first signal in the second counter.

19. The method of claim 12 which includes the steps of counting the pulses comprising the first pulse signal and counting the pulses comprising the second pulse signal in accordance with a weight dependent upon the total count of the first signal.

20. The method of claim 19 wherein the weights accorded the pulses in counting are each powers of two.

21. The method of claim 11 which includes the steps of producing a signal representing the duration of coin presence sensing by a single sensor, and producing another signal representing the duration of concurrent coin presence sensing by at least two sensors.

22. The methodof claim 21 wherein first and second values are each represented by a first and a second electrical pulse signal, respectively.

23. The method of claim 22 which includes the steps of counting the pulses comprising the first pulse signal and establishing the pulse rate of the second pulse signal as a function of the total count of the first pulse signal.

24. The method of claim 23 which includes the steps of counting the pulses of one pulse signal in a first counter, counting the pulses of another pulse signal in a second counter, and comparing totals of the counters.

25. The method of claim 23 which includes the steps of counting the pulses of the first pulse signal in one direction into an up-down counter, counting the pulses of the second pulse signal in the opposite direction into that counter, and comparing the remainder in the counter with a predetermined range.

26. The method of claim 23 wherein the second pulse signal is produced by the steps of presetting a counter, and producing a pulse each time the counter reaches a predetermined number.

27. The method of claim 23 which includes the steps of preloading a first counter to a predetermined number, counting the pulses from a pulse source into the first counter, producing an output pulse from the first counter each time it is filled, and counting the output pulses of the first counter with a further counter.

28. The method of claim 27 in which a first counter produces pulses comprising the first pulse signal during one period of time and pulses comprising the second pulse signal during another period of time, and in which the first counter is preloaded during counting of the pulses of the first pulse signal with a first predetermined number and preloaded during counting of the pulses of the second pulse signal with a second predetermined number which is dependent upon the total count of the first pulse signal by the second counter.

29. The method of claim 22 which includes the steps of counting the pulses comprising the first pulse signal and counting the pulses comprising the second pulse signal in accordance with a weight dependent upon the total count of the first pulse signal.

30. The method of claim 29 wherein the weights accorded the pulses in counting are each powers of two.

31. The method of claim 11 which includes the steps of producing one signal representing the duration of a period following the sensing of coin presence by one sensor, during which neither that sensor or a second sensor senses the presense of a coin and producing another signal representing the duration of sensing of coin presence by a single sensor.

32. The method of claim 31 wherein first and second values are each represented by a first and a second electrical pulse signal, respectively.

33. The method of claim 32 which includes the steps of counting the pulses comprising the first pulse signal and establishing the pulse rate of the the pulses pulse signal as a function of the total count of the first pulse signal.

34. The method of claim 33 which includes the steps of counting the pulses of one pulse signal in a first counter, counting the pulses of another pulse signal in a second counter, and comparing totals of the counters.

35. The method of claim 33 which includes the steps of counting the pulses of the first pulse signal in one direction into an up-down counter, counting the pulses of the second pulse signal in the opposite direction into that counter, and comparing the remainder in the counter with a predetermined range of values.

36. The method of claim 33 wherein the second pulse signal is produced by the steps of presetting a counter, counting the pulses from a pulse source into the counter, and producing a pulse each time the counter reaches a predetermined number.

37. The method of claim 33 which includes the steps of preloading a first counter to a predetermined number, counting the pulses from a pulse source into the first counter, producing an output pulse from the first counter each time it is filled, and counting the output pulses of the first counter with a further counter.

38. The method of claim 37 in which a first counter produces pulses comprising the first pulse signal during one period of time and pulses comprising the second pulse signal during another period of time, and in which the first counter is preloaded during counting of the pulses of the first pulse signal with a first predetermined number and preloaded during counting of the pulses of the second pulse signal with a second predetermined number which is dependent upon the total count of the first pulse signal in the second counter.

39. The method of claim 32 which includes the steps of counting the pulses comprising the first pulse signal and counting the pulses comprising the second pulse signal in accordance with a weight dependent upon the total count of the first pulse signal.

40. The method of claim 39 wherein the weights accorded the pulses in counting are each powers of two.

41. A device for discriminating among coins with respect to denomination, authenticity and the like comprising

means for examining a first characteristic of a coin, and

means for producing a first value which is a function of said first characteristic,

means for examining a second characteristic of the coin, and

means for producing a second value which is a function of said second characteristic,

a comparator connected to the means for producing the first value and the means for producing the second value, which compares the first value with the second value and produces an output signal indicating whether the difference between the compared values is within a predetermined range.

42. A device for discriminating among coins with respect to denomination, authenticity and the like comprising

a pulse generator,

first means for examining a characteristic of a coin,

a first gate having inputs connected to receive signals from the pulse generator and the first examining means,

second means for examining another characteristic of the coin,

a second gate having inputs connected to receive signals from the pulse generator and the second examining means,

a first pulse counter connected to receive signals from the first gate,

a second pulse counter connected to receive signals from the second gate,

means for comparing the outputs of the first and second counters.

43. The device of claim 42 wherein a single updown counter comprises the first and second counters and the remainder is compared with a predetermined tolerable range.

44. The device of claim 43 further comprising a logic circuit connecting the inputs of two or more stages of the up-down counter are each connected to an output of the third counter.

45. The device of claim 42 further comprising a third counter interposed between one of the gates and the counter receiving signals from that gate.

46. The device of claim 43 further comprising a third counter interposed between one of the gates and the up-down counter.

47. The device of claim 46 further comprising a logic circuit connecting the output of the third counter to an input of the up-down counter.

48. The device of claim 45 further comprising a logic circuit connecting an output of the third counter to an input of another counter.

49. The device of claim 42 further comprising a logic circuit connecting two or more inputs of the second counter are each connected to an output of the third counter.

50. A device for discriminating among coins with respect to denomination, authenticity and the like comprising

a coin passageway along which coins can pass,

a magnetic field generator producing a magnetic field in a region of the passageway,

at least two coin presence sensors responsive to the passage of coins in the passageway,

a pulse generator,

a logic circuit connected to two sensors and the pulse generator, and

means for comparing two values produced by the logic circuit with each other comprising

two pulse counters each connected to receive signals from an output of the logic circuit.

51. The device of claim 50 wherein the two counters comprise a single up-down counter and the value comparing means further comprise a comparator for comparing the remainder in the up-down counter with a predetermined range.

52. The device of claim 50 further comprising a further counter interposed between the logic circuit and a counter.

53. The device of claim 52 further comprising a furthe logic circuit connecting an output of the further counter to an input of the counter.

54. The device of claim 52 wherein the inputs of two or more stages of the counter are each connected to the output of the further counter.

55. The device of claim 50 wherein the logic circuit comprises a first subcircuit arranged to produce a signal representing the duration of coin presence sensing by a single sensor, and a second subcircuit arranged to produce a signal representing the concurrent coin presence sensing by at least two sensors.

56. The device of claim 55 wherein the two counters comprise a single up-down counter and further comprising a comparator for comparing the remainder in the up-down counter with a predetermined range.

57. The device of claim 55 further comprising a further counter interposed between the logic circuit and a counter.

58. The device of claim 57 further comprising a further logic circuit connecting an output of the further counter to an input of the counter.

59. The device of claim 57 wherein the inputs of two or more stages of the counter are each connected to the output of the further counter.

60. The device of claim 50 wherein the logic circuit comprises

a first subcircuit arranged to produce a signal representing the duration of a period in which neither of two sensors senses the presence of a coin following the sensing of the presence of a coin by one of the sensors; and

a second subcircuit arranged to produce another signal representing the duration of coin presence sensing by a sensor.

61. The device of claim 60 wherein the two counters comprise a single up-down counter and further comprising a comparator for comparing the remainder in the up-down counter with a predetermined range.

62. The device of claim 60 further comprising a further counter interposed between the logic circuit and a counter.

63. The device of claim 62 further comprising a further logic circuit connecting an output of the further counter to an input of the counter.

64. The device of claim 62 wherein the inputs of two or more stages of the counter are each connected to the output of the further counter.

65. The method of claim 11 which includes the steps of producing a signal representing the duration of coin presence sensing by a single sensor, and producing another signal representing the duration of coin presence sensing by at least one sensor while another sensor is not sensing the presence of a coin.

66. The method of claim 65 wherein first and second values are each represented by a first and a second electrical pulse signal, respectively.

67. The method of claim 66 which includes the steps of counting the pulses comprising the first pulse signal and establishing the pulse rate of the second pulse signal as a function of the total count of the first pulse signal.

68. The method of claim 67 which includes the steps of counting the pulses of one pulse signal in a first counter, counting the pulses of another pulse signal in a second counter, and comparing totals of the counters.

69. The method of claim 67 which includes the steps of counting the pulses of the first pulse signal in one direction into an up-down counter, counting the pulses of the second pulse signal in the opposite direction into that counter, and comparing the remainder in the counter with a predetermined range.

70. The method of claim 67 wherein the second pulse signal is produced by the steps of presetting a counter, and producing a pulse each time the counter reaches a predetermined number.

71. The method of claim 67 which includes the steps of preloading a first counter to a predetermined number, counting the pulses from a pulse source into the first counter, producing an output pulse from the first counter each time it is filled, and counting the output pulses of the first counter with a further counter.

72. The methodof claim 71 in which a first counter produces pulses comprising the first pulse signal during one period of time and pulses comprising the second pulse signal during another period of time, and in which the first counter is preloaded during counting of the pulses of the first pulse signal with a first predetermined number and preloaded during counting of the pulses of the second pulse signal with a second predetermined number which is dependent upon the total count of the first pulse signal by the second counter.

73. The method of claim 66 which includes the steps of counting the pulses comprising the first pulse signal and counting the pulses comprising the second pulse signal in accordance with a weight dependent upon the total count of the first pulse signal.

74. The method of claim 73 wherein the weights accorded the pulses in counting are each powers of two.

75. The device of claim 50 wherein the logic circuit comprises a first subcircuit arranged to produce a signal representing the duration of coin presence sensing by a single sensor, and a second subcircuit arranged to produce a signal representing the duration of coin presence sensing by one sensor while another sensor does not sense the presence of a coin.

76. The device of claim 75 wherein the two counters comprise a single up-down counter and further comprising a comparator for comparing the remainder in the up-down counter with a predetermined range.

77. The device of claim 75 further comprising a further counter interposed between the logic circuit and a counter.

78. The device of claim 77 further comprising a further logic circuit connecting an output of the further counter to an input of the counter.

79. The device of claim 77 wherein the inputs of two or more stages of the counter are each connected to the output of the further counter.

80. The method of claim 11 which includes the steps of producing a signal representing the duration of concurrent coin presence sensing by at least two sensors, and producing another signal representing the duration of coin presence sensing by at least one sensor while another sensor is not sensing the presence of a coin.

81. The method of claim 80 wherein first and second values are each represented by a first and a second electrical pulse signal, respectively.

82. The method of claim 81 which includes the steps of counting the pulses comprising the first pulse signal and establishing the pulse rate of the second pulse signal as a function of the total count of the first pulse signal.

83. The method of claim 82 which includes the steps of counting the pulses of one pulse signal in a first counter, counting thepulses of another pulse signal in a second counter, and comparing totals of the counters.

84. The method of claim 82 which includes the steps of counting the pulses of the first pulse signal in one direction into an up-down counter, counting the pulses of the second pulse signal in the opposite direction into that counter, and comparing the remainder in the counter with a predetermined range.

85. The method of claim 82 wherein the second pulse signal is produced by the steps of presetting a counter, and producing a pulse each time the counter reaches a predetermined number.

86. The method of claim 82 which includes the steps of preloading a first counter to a predetermined number, counting the pulses from a pluse source into the first counter, producing an output pulse from the first counter each time it is filled, and counting the output pulses of the first counter with a further counter.

87. The method of claim 86 in which a first counter produces pulses comprising the first pulse signal during one period of time and pulses comprising the second pulse signal during another period of time, and in which the first counter is preloaded during counting of the pulses of the first pulse signal with a first predetermined number and preloaded during counting of the pulses of the second pulse signal with a second predetermined number which is dependent upon the total count of the first pulse signal by the second counter.

88. The method of claim 81 which includes the steps of counting the pulses comprising the first pulse signal and counting the pulses comprising the second pulse signal in accordance with a weight dependent upon the total count of the first pulse signal.

89. The method of claim 88 wherein the weights accorded the pulses in counting are each powers of two.

90. The device of claim 50 wherein the logic circuit comprises a first subcircuit arranged to produce a signal representing the concurrent coin presence sensing by at least two sensors, and a second subcircuit arranged to produce a signal representing the duration of coin presence sensing by one sensor while another sensor does not sense the presence of a coin.

91. The device of claim 90 wherein the two counters comprise a single up-down counter and further comprising a comparator for comparing the remainder in the up-down counter with a predetermined range.

92. The device of claim 90 further comprising a further counter interposed between the logic circuit and a counter.

93. The device of claim 92 further comprising a further logic circuit connecting an output of the further counter to an input of the counter.

94. The device of claim 92 wherein the inputs of two or more stages of the counter are each connected to the output of the further counter.