GB1578767A - Coin checking apparatus - Google Patents

Description

(54) COIN CHECKING APPARATUS (71) We, NIPPON COINCO Co. Lid., a company incorporated under the laws of Japan, of 5-8, Kitaaoyama 2-chome, Minatoku, Tokyo-to, Japan, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to an electronic coin checking apparatus.

Accurate checking of genuine and counterfeit coins is one of the important problems encountered with automatic dispensers and money exchange machines. In order to improve the accuracy of checking, it is desirable to check all characteristics of inserted coins (material, surface embossed pattern, outer diameter, etc.) so as to check that the coins are genuine. An electronic coin checking apparatus has recently been proposed wherein such characteristics as the material and the surface pattern are electronically examined. However, the diameter can be inspected only by mechanical means so that, where various types of coins are to be checked, it is necessary to provide independent coin sorting passages for checking coins of different diameters, thus complicating the construction and increasing the size of the apparatus.

According to the present invention, there is provided coin checking apparatus comprising: a coin passage for receiving coins inserted into the apparatus; two detecting coils surrounding the coin passage and connected in series opposition, the output of which coils changes when influenced by a coin passing along the coin passage, the detecting coils being the secondary coils of a differential transformer also having a primary coil surrounding the coin passage; an integration circuit for performing a substantially constant integration of the output of the detecting coils; and an evaluating circuit for determining whether a coin passing along the coin passage is genuine or counterfeit from the result of the integration performed by the integration circuit.

In order that the present invention may be more fully understood, an embodiment of coin checking apparatus according to the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a longitudinal sectional view of a coin detector of the embodiment; Figure 2 is a block diagram of the embodiment; Figure 3 is a graph showing measured levels obtained using this embodiment; and Figures 42 to 4f show time diagrams serving to explain the operation of this embodiment.

Referring to Figure 1, the coin detector 1 of the embodiment comprises a differential transformer including two secondary coils 3 and 4 wound about a coin passage 2 and having a spacing smaller than the diameter of the smallest coin to be checked and a primary coil 5 surrounding the secondary coils 3 and 4. The secondary coils are connected in series opposition and excited by a signal having a predetermined frequency (about 200 KHz) and suitable to detect the material of the coins so that a measured level corresponding to the variation in the coupling coefficient caused by the passage of a coin 6 falling as shown by an arrow x can be produced by the secondary windings.

Figure 2 shows the coin detector 1 coupled to a coin detection circuit which substantially integrates the measured level provided by the coin detector 1 and discriminates a genuine coin from a counterfeit coin on the bases of the result of the integration. Since whether the coin is genuine or counterfeit is judged on the basis of the total area of the measured level, it is possible to reject a counterfeit coin prepared to give a similar (but not identical) measured level with high accuracy.

In this coin inspecting apparatus, in order to perform a substantially constant integration, the detected level L10 above a predetermined level K1 is integrated as shown in Figure 4a. The integration is carried out by sequentially adding the detected levels L11 above the reference level K.

keterring to Figure 2 the primary coil of the detector 1 is excited by a high frequency oscillator 7, the two secondary coils producing an analogue output in accordance with the variation in the coupling coefficient caused by the passage of a coin through the coin passage.

The output from the detector 1 is applied to a level detector 17 and a digital voltmeter 60 via an amplifier 8. The purpose of the digital voltmeter 60 is to convert the analogue measured level into a digital signal and, when applied with a pulse from an AND gate circuit 61, it supplies the converted digital signal to a counter 62. The level detector 17 produces a signal " 1 when the level of the output from the detector 1 becomes higher than a predetermined level K; when the output level is as shown in Figure 4a, it produces an output as shown in Figure 4b. The output from the level detector 17 is applied to one input of the AND gate 61 so as to cause it to produce clock pulses t as shown in Figure 4c.In this manner, the clock pulses t produced by the AND gate 61 when the output level of the detector 17 is higher than level K, are applied to the digital voltmeter 60.

The detected level of the coin converted into a digital signal by the voltmeter 60 is sampled at the timing of the clock pulses t and applied to the counter 62 which sequentially integrates the digital signal (binary value) and stores the result of the integration. When the detected level L11 of the coin (Figure 4a) decreases below the predetermined level K1, the AND gate 61 is disenabled so that the clock pulses t are not supplied to the digital voltmeter 60. As a consequence, the digital voltmeter does not produce any output, thus terminating the integrating operation of the counter 62.

Thus, the substantially constant integration of the detected level L10 above the predetermined level K1 is completed.

The output from the level detector 17 is also applied to a delay flip-flop circuit 63 and an inverter 69. The delay flip-flop circuit delays the output by one clock pulse as shown in Figure 4d while the inverter produces an inverted signal which is applied to an AND gate 70 as shown in Figure 4e. The output pulse from the AND gate 70 as shown in Figure 4f is applied to the counter 62 so as to cause it to produce the result of integration stored therein at the timing of the output pulse.

The outputs from the counter 62 is also applied to digital comparators 71 to 76.

When the result of integration of the counter 62 is larger than the set values A1 Bl, C1, D1, E1 and F1 of respective comparators, each of these comparators produces an output signal " 1 ". The comparators 71 to 76 are set with the upper and lower limits of the result of integration for certain expected coins.The upper limit set value of a 100 Yen coin is A1 while the lower limit set value is 131. The upper and lower limit set values of a 50 Yen coin are C1 and D1, and the upper and lower limit set values of a 10 Yen coin are E1 and F1. Conse- quently, so long as the result of integration of the detected level of a coin lies in a range between the associated upper limit set value and the lower limit set value, the coin is judged as genuine.

The outputs from the comparators 71, 73 and 75 which compare the upper limits are applied to inputs of AND gates 82, 83 and 84 respectively through inverters 79, 80 and 81, while the outputs from the comparators 72, 74 and 76 which compare the lower limits are applied directly to the other inputs of the AND gates 82, 83 and 84 respectively.

The AND gates 82, 83 and 84 correspond to 100, 50 and 10 Yen coins respectively.

When the result of integration is within a predetermined range intermediate one of the upper limits and the associated lower limit, the associated AND gate 82, 83 or 84 produces an output signal "1". Thus it is judged whether the coin under inspection is genuine or counterfeit, as well as the type of the coin.

The output from the AND gate 70 is delayed by a delay circuit 85 to obtain a reset signal R which is used to reset to o the result of integration of the counter 62, thus preparing for the next inspection.

Although in the above described embodiment a circuit was shown in which a digital integration is made, it will be clear that it is possible to construct the circuit to perform an analogue integration.

It will be apparent from Figure 3 that if, for example, a genuine 50 Yen coin having an aperture has a characteristic level shown by the curve R50, a genuine 50 Yen coin having an aperture can be discriminated from a solid counterfeit 50 Yen coin having a characteristic level curve P50 which is the same as that of the genuine coin by the above described integration method.

The coin checking apparatus described above with reference to the drawings preferably also incorporates means for verifying the material of a coin and means for verifying the surface pattern of a coin.

The embodiment described above is also described in the Applicants' co-pending Application No. 49863/76 Serial No.

1 587 766 which is concerned with a different invention to the present application.

WHAT WE CLAIM IS:- 1. Coin checking apparatus comprising: a coin passage for receiving coins inserted into the apparatus; two detecting coils surrounding the coin passage and connected in series opposition, the output of which coils changes when influenced by a coin passing along the coin passage, the detecting coils being the secondary coils of a differential transformer also having a primary coil surrounding the coin passage; an integration circuit for performing a substantially constant integration of the output of the detecting coils; and an evaluating circuit for determining whether a coin passing along the coin passage is genuine or counterfeit from the result of the integration performed by the integration circuit.

2. Apparatus according to claim 1, wherein a high frequency oscillator is connected to the primary coil.

3. Apparatus according to claim 1 or 2, wherein the integration circuit includes a digital voltmeter for converting the analogue output from the detecting coils into a digital signal, and a counter for counting the pulses of the digital signal.

4. Apparatus according to claim 3, wherein the integration circuit further includes a level detector for producing an output when the output from the detecting coils exceeds a predetermined value and means responsive to the output from the level detector for applying clock pulses to the digital voltmeter to cause the digital voltmeter to sample the analogue output from the detecting coils.

5. Apparatus according to any preceding claim, wherein the evaluating circuit comprises a plurality of digital comparators coupled to the output of the integration circuit.

6. Apparatus according to claim 5, for checking coins of a number of different diameters, wherein the evaluating circuit comprises a corresponding number of pairs of digital comparators, the comparators of each pair being set with the upper and lower limits respectively of the result of integration obtained with a genuine coin having a diameter within an associated range.

7. Apparatus according to any preceding claim, wherein the detecting coils are spaced along the coin passage a distance less than the diameter of the smallest coin intended to be inserted into the apparatus.

8. Coin checking apparatus substantially as hereinbefore described with reference to, and/or as illustrated in, the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (8)

**WARNING** start of CLMS field may overlap end of DESC **. verifying the material of a coin and means for verifying the surface pattern of a coin. The embodiment described above is also described in the Applicants' co-pending Application No. 49863/76 Serial No.

1 587 766 which is concerned with a different invention to the present application.

WHAT WE CLAIM IS:- 1. Coin checking apparatus comprising: a coin passage for receiving coins inserted into the apparatus; two detecting coils surrounding the coin passage and connected in series opposition, the output of which coils changes when influenced by a coin passing along the coin passage, the detecting coils being the secondary coils of a differential transformer also having a primary coil surrounding the coin passage; an integration circuit for performing a substantially constant integration of the output of the detecting coils; and an evaluating circuit for determining whether a coin passing along the coin passage is genuine or counterfeit from the result of the integration performed by the integration circuit.

2. Apparatus according to claim 1, wherein a high frequency oscillator is connected to the primary coil.

3. Apparatus according to claim 1 or 2, wherein the integration circuit includes a digital voltmeter for converting the analogue output from the detecting coils into a digital signal, and a counter for counting the pulses of the digital signal.

4. Apparatus according to claim 3, wherein the integration circuit further includes a level detector for producing an output when the output from the detecting coils exceeds a predetermined value and means responsive to the output from the level detector for applying clock pulses to the digital voltmeter to cause the digital voltmeter to sample the analogue output from the detecting coils.

5. Apparatus according to any preceding claim, wherein the evaluating circuit comprises a plurality of digital comparators coupled to the output of the integration circuit.

6. Apparatus according to claim 5, for checking coins of a number of different diameters, wherein the evaluating circuit comprises a corresponding number of pairs of digital comparators, the comparators of each pair being set with the upper and lower limits respectively of the result of integration obtained with a genuine coin having a diameter within an associated range.

7. Apparatus according to any preceding claim, wherein the detecting coils are spaced along the coin passage a distance less than the diameter of the smallest coin intended to be inserted into the apparatus.

8. Coin checking apparatus substantially as hereinbefore described with reference to, and/or as illustrated in, the accompanying drawings.