AU595942B2

AU595942B2 - Coin selecting apparatus

Info

Publication number: AU595942B2
Application number: AU79942/87A
Authority: AU
Inventors: Shinji Yokomori
Original assignee: Fuji Electric Co Ltd
Current assignee: Fuji Electric Co Ltd
Priority date: 1986-11-27
Filing date: 1987-10-20
Publication date: 1990-04-12
Anticipated expiration: 2007-10-20
Also published as: KR930011725B1; KR880006629A; JPH0668789B2; JPS63136188A; AU7994287A

Description

Fee: $145.00 APPLICATION ACCEPTED AND~Ii U"- AI.OWEV

F-

COMMONWEALTH OF AUSTRALIA FORM PATENTS ACT 1952 CO0M P LE TE SP E CIF IC A TIO N

FOR.OFFICE-USE:

Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: In Class 4),tIl ~J"d 13 correct for.

jjriJi t ing 4' 44 Priority:, Related Art: 44 44 1'ame of Applicant: Address of Applicant: ~Actual Inventor: FUJI ELECTRIC CO., LTD 1-1 TANABESHINDEN, KAWASAKI-KU,

KAWASAKI

210, J,,APAN SHINJI YOI(OMORI ddress for Service: SHELSTON WATERS, 55 Clarence Street, Sydney Complete Specification for the Invention entitled: "COIN SELECTING

APPARATUS"

The following statement is a full description of this invention, including the best method of performing it known to me/us:ev.4 V. (Signature of Declarant) Yoshihiko Nakazato To THE COMMISSIONER OF PATENTS.

'1 1. Title of the Invention Coin Selecting Apparatus 2. Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a coin selecting apparatus for judging the genuineness of a coin.

3. Brief Description of the Drawings Fig. 1 is a block diagram showing one example of the structure of the embodiment according to the present invention; Fig. 2 is an explanatory diagram showing the voltage changes in the embodiment of the present invention; Fig. 3 is a block diagram showing one example of the structure of the prior art; Fig. 4 is an explanatory diagram showing the impedance changes in the example of the prior art; and Fig. 5 is an explanatory diagram showing the voltage changes in the example of the prior art.

1 Coin; 20 2 Coin Passage; 3 Oscillator; 4 Differential Circuit; Rectifier; 6 Comparators; and 7 AND Gates.

l.- (P::ior Art) As a coin selecting apparatus, there is generally known an apparatus for judging the genuineness of a coin by disposing in a coin passage a coil sensor .jr detecting the impedance change when the coin passes thereover.

Fig. 3 shows one example of the structure of a selection circuit of the coin selecting apparatus of the above-specifieu kind according to the prior art. In Fig. 3, a coil sensor L1, a fixed coil L2 and two resistors R constitute together a bridge circuit, to which is supplied a sine wav- having a frequency suitable for the coin selection by an oscillator 3.

The level of the coil L2 is set at that of the coil L1 in the absence of a coin so that the difference of the voltage V 1

V

2 is zero if any coil is absent at a 2 the coil L1. This voltage difference is inputted through a differential amplifier 4 and a rectifier 5 to comparators 6. The change of the impedance of this structure when a coin 1 passes over the coil sensor L is shown in Fig. 4.

In Fig. 4, a point 0 indicates that the coin 1 is absent from the coil sensor LI, and points A, B and C S. indicate the maximum changes when coins A, B and C are put. Incidentally, these coins A, B and C have o* Il0 different external diameters, materials and S' d thicknesses. On the other hand, a point A' indicates the maximum change of a counterfeit coin.

Next, the changes of the output voltage V 3 of the S rectifier 5 when the coins A, B and C are put are shown c' in Fig. 5. The coin 1 is judged by the comparators 6 a and AND gates 7, depending upon whether or not that "voltage V 3 is within a predetermined range.

20 [Problem to Be Solved by the Invention 1 o- Incidentally, the aforementioned coin selecting circuit of the prior art is followed by a defect that the coin A and the counterfeit coin A' cannot be discriminated because the impedance differences from the point 0 take a substantially equal value when the maximum change point A' of the counterfeit coin is located at the maximum change point A of the genuine 3 coin, for example, as shown in Fig. 4.

It is, therefore, an object of the present invention to solve the above-specified problem and to provide a coin selecting apparatus which can perform a genuineness discrimination in high accuracy.

(Means for Solving the Problemj In order to achieve this object, the present invention is characterized by comprising: means for having its impedance changing in response to passage of a coin; first detection means for detecting the change of the impedance in terms of a first voltage change; first comparison means for comparing whether or not the first voltage change detected by said first detection means is within a predetermined range; second detection means for detecting the change of said impedance in terms of a second voltage change; second comparison means for comparing whether or not the second voltage change detected by said second detection means is within a predetermined range; and judgement means for judging that said coin is genuine if the comparisons of said first comparison means and said second comparison means have revealed that both said first and second voltage changes are within said predetermined ranges.

(Operations) 4

V-

According to the present invention, the change of the impedance of the impedance change detection means due to the passage of a coin is determined in terms of first and second voltage changes by the first and second detection means, and these voltage changes are compared with predetermined threshold values. If the individual voltage changes are within predetermined ranges, it is judged by the judgement means that the coin having passed is genuine, so that a higher o0 discrimination quality can be attained.

Embodimentj a0 Fig. 1 shows one example of the structure according to the embodiment of the present invention.

A first bridge circuit is composed of a coil a sensor L1, a fixed coil L2 and a resistor R, and a second bridge circuit is composed of the coil sensor p o" LI, a fixed coil L3 and a resistor R. These bridge circuits are fed with sine waves from an oscillator 3.

o" 4 The level of the coil L2 is set at that of the 4 20 coil sensor L1 in the absence of the coin, the IV A level corresponding to the point O in Fig. 4, whereas the level of the coil L3 is set at a lower level than the coil L2, the level corresponding to the point O' in Fig. 4. The voltage difference of V- V 2 is fed through a differential amplifier 4 and a rectifier 5 and is inputted as a voltage V 3 into a comparator 6.

In this comparator 6, the voltage V 3 is compared with a predetermined voltage range such as VA+ and VA- in the case of a coin A, VB+ and V

B

in the case of a coin B, and VC+ and V

C

in the case of a coin C.

The output voltage of V1' V 2 from the second bridge circuit is fed through the differential amplifier 4 and through the rectifier 5 and is inputted as a voltage V 3 into a comparator 6 so that it is compared with a predetermined voltage range VA+' and V

A

in the case of the coin A, V and VB-' in the case of the coin B, and VC+' and VC-' in the case of the coin The voltage changes when the coin A and its counterfeit coin A' are put are shown in Fig.

2.

As shown in Fig. 2, the coins A and A' have different spacings from the position 0' so that the peak value of the voltage V

C

becomes accordingly i different. As a result, the coin A has its peak value between and VA so that an AND gate 7A' produces an output The counterfeit coin A' fails to have its peak value within that range so that the output of the AND gate 7A' fails to take the value This is because the output voltage of the second bridge circuit for the counterfeit coin makes a higher voltage change for the genuine coin even if the output voltage from the first bridge circuit is substantially equal to that for the genuine coin, and vice versa. However, the counterfeit coin can be reliably discriminated from the genuine one with a high selection accuracy in view of the output of an AND gate 8A which is made receptive of the octputs «of those AND gates 7A and 7A'.

(Effects of the Invention As has been described hereinbefore, according to the present invention, the values of the impedance changes of the coil sensors due to the influences of the coin are detected in terms of two kinds of values of the voltage changes, and whether or not the individual voltage values detected are within the predetermined ranges can be judged. Thus, the present invention can enjoy an effect that the accuracy of the coin detection can be improved.

*4 s 7

Claims

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