GB2164188A - Apparatus for testing coins of various values - Google Patents

Abstract

Apparatus for testing coins of various values includes a first detector (6) for testing the coin alloy, which detector successively receives a.c. voltages of various frequencies from an audio frequency generator (15). A stopper is disposed in a rolling track for the coins, and a second test detector (8) is disposed downstream of the stopper, for testing the diameter of the coins. An evaluation means (22) controls the audio frequency generator (15) and change-over switches (16, 17, 18) for transmitting a test voltage (UoC) to a voltage detector (21), and stores the output voltage (Um) thereof in a memory (26). When the apparatus is set in operation, prior to the coin testing operation, calibration of the test detectors (6, 8) is carried out in order to render ageing, stray effects and fluctuation in temperature inoperative. After calibration and all operations of testing a coin, the associated values in the memory (6) are compared and a corresponding signal is produced. <IMAGE>

Description

SPECIFICATION Apparatusfortesting coins of various values The present invention relates to an apparatus for testing coins of various values.

A coin testing apparatus is described in Swiss patent application No. 29 04/84-0. In that apparatus, each coin which is introduced through a single slot provided is tested by means of five test signals before a desired service is triggered by the coin. In that arrangement, the test signals are supplied by a metal detector, a test detector to which two voltages of differentfrequencies are applied when the coin is stationary, atestdetectorforthe rolling coin and a weight detector, and are evaluated in an evaluation means before the coin is put into a coin collection means in orderto permit the service to be performed, or a coin which is not acceptable is passed into a return dish.

According to the invention, there is provided apparatus for testing coins of various values, the apparatus comprising a first test detector fortesting the alloy ofthe coins which is operative successively to receive voltages of different frequencies from an audio frequency generator, a stopper disposed in a rolling trackforthe coins to roll along, a second test detector disposed downstream of the stopper for testing the diameter of the coins, and an evaluation means for the two test detectors, wherein the evaluation means is operative to control the audio frequency generator by means of a first control circuit and, by means of second and third control circuits, is operative to actuate change-over switches for supplying a test voltage to a voltage detector, andwherein the outputvoltage ofthevoltage detector is supplied to a memoryoftheevaluation means.

A preferred embodiment of the invention is capable of determining the alloy and the diameter of the coin and of permitting satisfactory coin testing, by means of an inexpensive control device, with the coin testing operation being unaffected bythe influences of temperature, ageing and externally originating stray effects.

The invention will now be described, byway of example, with reference to the accompanying draw ing, in which: Figure lisa simplified perspective view of a testing apparatus for testing the alloy and diameter of a coin; and Figure 2 shows a block circuit diagram of the testing apparatus.

Thetesting apparatus 1 shown in Figure 1 has a rolling track 2 down which a coin 3 rolls. Two bar cores 4 and 5 of a first test detector 6 for testing the alloy are arranged in a transverse direction, relative to the rolling track 2. Disposed adjoining thefirsttest detector 6, on the rolling track 2, is a stopper 7which controls the movement of the coin 3through the first detector 6 and subsequently through a second test detector 8 which is responsive to the diameter of the coin 3 introduced. The second test detector3 compris es two magnetic cores 9 and 10 which are arranged on both sides ofthe rolling track 2 and in mirror image relationship therewith and which are of square or rectangular cross-section and which are in an on-edge relationship with the rolling track 2.A respective winding 11 and 12 is disposed on each of the bar cores 4 and 5 while a respective winding 13 and 14 is disposed on each of the magnetic cores 9 and 10. The windings 11,12,13 12, 13 and l4areconnectedto earth on one side.

The block circuit diagram shown in Figure 2 represents an audio-frequency generator 15, a change-overswitch 16which can be applied to the windings 11 and 13, a further change-over switch 17 forswitchingthewindings 12 and 14, a phase comparator 18, a peak voltage detector 19, a changeover switch 20 connecting to the outputs of the phase comparator 18 and the peakvoltage detector 19, a voltage comparator shown in the form of a voltage detector 21, and an evaluation means 22.

The switching arm of the change-over switch 16 is connected to an output ofthe generator 15. Afurther connection of the generator 75 is to a first input ofthe phase comparator 18 of which a second input is connected to the switching arm ofthe change-over switch 17 which is also connected to an input ofthe peakvoltage detector 19. The switching arm ofthe switch 20 is connected to the voltage detector 21.

The generator 15 includes a frequency synthesizer with a quartz oscillator (not shown) for a highfrequency a.c. voltage, and a frequency divider (also not shown) having a plurality oftappings. The phase comparator has two inputs ofwhich the first is connected to the output of the generator 15 and the second is connected to the switching arm of the change-over switch 16. A voltage Uoc corresponding to the maximum phase difference Acp occurs at the output ofthe phase comparator 18.

The peak voltage detector 19 includes at its output a lowpassfilterwhosetimeconstantcan be altered by means of a control circuit 24. Avoltage which is also denoted by Ucc occurs at the output of the peak voltage detector 19. A low pass filter (not shown) is disposed in the input to the voltage detector 21.

The evaluation means 22 includes inter alia three control circuits 23,24 and 25 and a memory 26. The first control circuit 23 is connected to the generator 15.

Besides the time constant ofthe peak voltage detector 19,the second control circuit 24 controls thetwo change-over switches 16 and 17. The change-over switch 20 is controlled by the control circuit 25. The voltage detector 21 is connected to the memory 26 in the evaluation means 22. The evaluation means preferably comprises a microprocessor.

The testing apparatus operates in the following manner.

The evaluation means 22 and the generator 15 are connected to a switch for setting the arrangement in operation, for example a cradle switch of a telephone.

When the arrangement is set in operation, a calibration process in respect of the testing apparatus 1 is set in operation, prior to the coin testing process, by switching overthe overall control means in the evaluation means 22. That takers place in three phases.

In the first phase, the control circuit23 in the evaluation means 22 controls the generator 15 in such a way that it successively producestwo a.c. voltages Up at different frequencies, for example 6.25 kHz and 12.5 kHz. In that operation, the corresponding tapping in the frequency divider of the generator 15 is connected to the output ofthe generator 15. An alloy in a coin 3 comprising copperornickel responds to the firstfrequencyof6.25 kHzwhile iron as an alloy constituent responds to the second frequency of 12.5 kHz.The control circuit 24 in the evaluation means 22, by means ofthe switch 16, connects the generator 15 to the winding 11 ofthe bar core 4 in the first test detector 6, while by means ofthe switch 17, the winding 12 ofthe barcore Softhefirsttest detector 6 is connected tothe peak voltage detector 19 and a connection is made between the peak voltage detector 19 and thevoltage detector 21, by means ofthe switch 20. The voltage Ucc measured bythe peakvoltage detector 19 is measured inthevoltagedetector2l 21.The amplitude ofthe a.c. voltage ofthe generator 5 is now altered until a predetermined voltage (for example 2.5 V) is attained in the voltage detector 21.The set value ofthe a.c. voltage ofthe generator 15 is now stored, in accordancewith the selected frequencies, in the memory 26 ofthe evaluation means 22.

in the second phase,the generator 15 is caused to output a voltage Up at a frequency of 12.5 kHz. In that phase, the switches 16 and 17 remain in the same position as in the first phase. However, the switch 20 connects the phase comparator 18to the voltage detector 21. The phase shift between the voltage Up at the output ofthe generator 15 and a voltage Us atthe winding ? 2 is converted inthe phasecomparator 18 into a corresponding output voltage Uac. That produces in the voltage detector21 an outputvoltage Urn which is written into the memory 26 ofthe evaluation means 22.

In the third phase, the voltage Up ofthe generator 15 is applied by means ofthe switch 16 to the winding 13 ofthe magnetic core 9 ofthe second test detector 8.

The winding 14 ofthe magnetic core 10 of the second test detector8 is connected to the peak voltage detector 19 bytheswitch 17 and the detector 19 is connected to the voltage detector 21 by means ofthe switch 20. The setvalue ofthe amplitude ofthe a.c.

voltage ofthe generator 15 is derived as described in the first phase, and stored in the memory 26 ofthe evaluation means 22.

The three phases ofthe calibration process are effected afterthearrangement is set in operation, before an introduced coin 3 comes in. The introduced coin 3 is stopped on the rolling track2 between the bar cores 4and 5 by the stopper 7. The bar cores 4 and 5 are of such a dimension that the cross-section thereof is also fully covered bythefaces ofthe smallest coin 3 which is stationary atthat point. The entire operation of testing the introduced coins 3 takes place as in the calibration process, in three phases. The generator 15 is programmed for each measuring operation, with the corresponding amplitude value found in the calibration phase.The individually ascertained voltages Urn at the output ofthe voltage detector 21 are stored in the memory 26 ofthe evaluation means 22 until the entire operation oftesting the coins 3 is concluded.

Onlythemagneticproperties of the alloy of the coin 3 are tested in thefirstplace by means ofthewindings 11 and 12 ofthe barcores 4 and 5 ofthetestdetector 6, with the coin 3 stationary. Asthe introduced coin 3 bounces when it is stopped by the stopper7, the measurements ofthefirst phase are repeated until three successive measurements give the same result.

It is only then that the measuring program continues.

In the first phase ofthe coin testing operation, as in the calibration process, an a.c. voltage is successively applied atthe frequencies of 6.25 kHz and 12.5 kHzto the winding 11 of the bar core 4 of the test detector 6.

The alloy ofthe core 3 induces attenuated voltages Us in the winding 12 ofthe bar core 5, the winding 12 being coupledto the winding 11 in the manner of a transformer. The voltages Us are measured and stored as described in thefirstphas.e.

Directlyfollowing the opening ofthe rolling track 2 shown in Figure 1, by an actuating magnet (not shown)forthestopper7,the measuring operation of the second phase is carried out by means ofthetest detector 6, as soon as the coin 3 begins two move on the inclined rolling track 2, while the coin 3 is still at a low speed. In that operation, in a similar manner to the calibration process,the phase comparator 18 mea- suresthe shift in phase ofthe a.c. voltage U5,with the higherof thefrequencies of the first phase, that is to sayforexample 12.5 kHz, atthe output ofthe winding 12, relative to the output voltage Up ofthe generator 15.The phase-dependent voltage Uoc detected is transmitted to an input ofthevoltage detector 21, with the switch 20 in the associated position.The voltage Urn atthe output ofthe voltage detector21,which corresponds to the maximum phase-dependent voltage Ucc, is stored in the memory 26 ofthe evaluation means 22. The corresponding value is dependent on the nature ofthe alloy ofthe coin 3, the thickness thereofand its diameter.

The coin 3then rolls on through the space between the magnetic cores 9 and lOin Figure 1, wherein the testing operation in regard to core diameter is carried out. The winding 13 on the magnetic core 9 is connected to the output ofthe generator 15 in this third phase ofthe coin testing process, by means of the switch 16. The generator 15, underthe influence of the control circuit 23 of the evaluation means 22, provides an a.c. voltage Up at a higherfrequencythan inthefirsttwo phases, for example 62.5 kHz, atwhich the nature ofthe alloy ofthe coin3exerts at most a very slightinfluence on measuring the coin diameter.

Depending on the respective diameterofthe coin 3, a voltage Us of greater or lesser magnitude occurs atthe associated winding 1 4 of the magnetic core 10. The voltage Us is transmitted by means of the switch 17 to the peak voltage detector 19. That voltage U5 passes through a minimum when thecentre ofthe coin 3 passes throug h the space between the magnetic cores 9 and 10. The minimum voltage Us represents a criterion in respect of coin diameter. In this third phase, the time constant ofthe peak voltage detector 19 is reduced by the control circuit 24 in the evaluation means 22. In that way, the peak voltage detector 19 is capable offollowing the rapidly varying input a.c.

voltage U5. The outputvoltage Uoc ofthe peakvoltage detector 19 is transmitted to the voltage detector 21 by means ofthe switch 20 and the voltage Urn at the output thereof is transmitted to the memory 26 ofthe evaluation means 22.

Afterallthetesting operations in respect ofthe coin 3, by means of the test detectors 6 and 8, have been carried out, a computing means in the evaluation circuit 22 detects whether the stored measurement values are all within the associated minimum and maximum values stored in the memory 26. Ifthe result of that testing operation by the evaluation circuit 22 is positive, a signal for putting thetested coins 3 into the coin collection means and for releasing the corresponding service appears atthe output 27 ofthe evaluation means 22 or, in the other situation, a blocking signal in regard to the service in question and a signal for diverting the coins 3 into the return dish appearatthe output 27.

Itwill be appreciated that, prior to or subsequently to the operation of checking the alloy and the diameter ofthe coin 3, furthertesting operations, for example forseparating out plastics discs orfortheweight of the coin 3, may be performed. However, such testing operations are less affected by changes in temperature, ageing or externally originating stray effects, againstwhich the apparatus according to the invention provides particularly good protection.

Claims (9)

1. Apparatusfortesting coins of various values, the apparatus comprising a firsttest detectorfor testing the alloy of the coins which is operative successively to receive voltages of differentfrequenciesfrom an audio frequency generator, a stopper disposed in a rolling trackforthe coins to roll along, a second test detector disposed downstream of the stopperfortesting the diameter ofthe coins, and an evaluation means for the two test detectors, wherein the evaluation means is operativeto control the audio frequency generator by means of a first control circuit and, by means of second and third control circuits, is operative to actuate change-over switches for supplying a testvoltageto a voltage detector, and wherein the output of the voltage detector is supplied two a memory of the evaluation means.

2. Apparatus according to claim 1, wherein a change-over switch forthe overall procedural control in the evaluation means is of such a naturethat calibration ofthe test detectors is effected in each case priortotesting a coin.

3. Apparatus according to claim 1,wherein after the calibration operation and after all operations of testing a coin have been carried out, the associated values in the memory are compared bythe evaluation means and a corresponding signal is output by the evaluation means.

4. Apparatus according to claim 1,whereinforthe purposes of generating an a.c. voltage of a given frequency by means of the control circuit in the audio frequency generator, the evaluation means makes a connection between a tapping of a frequency divider which is actuated by a higher quartzfrequency, to the output ofthe audio frequency generator, and the amplitude ofthe audio frequency generator is altered by means ofthe control circuit.

5. Apparatus according to claim 1, wherein the change-over switches which are controlled bythe second control circuit can selectively make a connection forthe signal of the audiofrequency generator by way of the first test detector to a phase comparator or a peakvoltage detector or by way of the second test detector to the peak voltage detector.

6. Apparatus according to claim 1, wherein the change-over switch which is controlled bythethird control circuit can selectively make a connection ofthe phase comparator orthe peakvoltage detectorto the voltage detector.

7. Apparatus according to claim 1, wherein the voltage detector is a voltage comparator in which the voltage applied to an input is processed and the voltage atthe outputthereof is supplied to the memory in the evaluation means.

8. Apparatus according to claim 6, wherein for the purposes of calibration and for testing a coin, in a first phase,two voltages of differentfrequenciesfrom the audio frequency generator are successively supplied by way of the first test detector to the peak voltage detector, then, in a second phase, a voltage at the higher ofthetwo frequencies is supplied byway of the first test detectorto the phase comparator, and finally in a third phase, a voltage at a higherfrequencythan in thefirsttwo phases is supplied by way ofthe second test detector to the peak voltage detector.

9. Apparatusfortesting coins of various values, the apparatus being substantially as herein described with reference to and as illustrated in the accompanying drawing.