Device for discrimination of circular plate bodies

Abstract: A device for discriminating a circular plate body, which device comprises: a passage means adapted to guide and allow a circular plate body to orient vertically and fall naturally therewithin; a first coil means wound around the passage means; second and third core means each of which covers a respective opposing side of the first coil means; and second and third coil means, each wound around a respective one of said second and third core means.

Description: Field of the Invention The present invention relates to a device for discrimination of circular plate bodies such as, for example, currency coins having a circular plate form or medals or tokens with a circular plate form as may be used for game machines. More particularly, this invention relates to a device for discrimination of circular plate bodies by detecting the size and material of the body or its other characteristics. The invention is particularly suitable for being incorporated into the type of equipment that relies on coin or token insertion such as, for example, various vending machines, money changing machines or game machines. Background to the invention Devices for discrimination of circular plate bodies such as coins and tokens are variously known of relying upon electromagnetic principles to carry out their function. A coin or other circular plate body inserted into such devices alters the magnetic flux of a coil within the device. One example of such a prior device is disclosed in Japanese patent application number 7-46088. The above-cited prior device comprises a passage means to allow passage of coins; two coil means arranged on opposing sides of the passage means and cumulatively connected together; two coil means arranged on opposing sides of the passage means and differentially connected together; an oscillator means to provide a low frequency oscillation to the pair of cumulatively connected coil means and a second oscillator means to provide a high frequency oscillation to the pair of differentially connected coil means. However, this prior technology is not without its problems. It relies upon an inserted coin displacing a base member in the passageway into which the coin is inserted. This serves as a standard surface and it is critical that the coin has a precise relationship with the standard surface and passes smoothly among the coils. Amongst other drawbacks, this presents substantial limitations on the rate of operation of the device in discrimination of coins or the like. Further coin discriminating devices are disclosed in, for example, DE 2,916,123 and DE 2,146,184, in each of which a plurality of coils are used with differing directions of magnetic flux. It is a general objective of the present invention to provide a device for discrimination of circular plate bodies that overcomes or mitigates the aforementioned and other problems of the prior technology. It is an objective to improve the rate of discrimination and simplify the construction of the device and allow an inserted coin to fall naturally. Summary of the Invention According to the present invention there is provided a device for discrimination of a circular plate body, which device comprises: a passage means adapted to guide and allow a circular plate body to orient vertically and fall naturally; a first coil means wound around the passage means; a second and a third core means which each cover the first coil means on a respective opposing side of the passage means; and a second and a third coil means, each wound around a respective one of said second and third core means about axes parallel to the axis of the passage means. Preferably the coil means are configured such that the magnetic flux of the first coil means and the magnetic flux of the second and third coil means intersect normally in the passage means. Particularly preferably, the passage means is formed of a synthetic resin. Brief Description of the Drawings Preferred embodiments of the present invention will now be more particularly described, by way of example, with reference to the accompanying drawings, wherein: Figure 1A is a perspective view of a first preferred embodiment of the invention and Figure 1B is a longitudinal sectional view of the embodiment of Figure 1A from the front end; Figure 2A is a circuit diagram for the embodiment of Figure 1 and Figure 2B is a diagram illustrating the orientation of magnetic flux in the embodiment of Figure 1; Figure 3 is a block diagram for the device of the first preferred embodiment and further illustrating by dotted lines a modification to turn the device into a second preferred embodiment; Figure 4A is a longitudinal sectional view similar to Figure 1B but of a lower part of a third preferred embodiment and Figure 4B is a block diagram for the third preferred embodiment; and Figure 5A is an longitudinal sectional view of a fourth preferred embodiment from one side and Figure 5B is a longitudinal sectional view of the fourth preferred embodiment from the front end. Description of the Preferred Embodiments Referring to Figure 1, the first preferred embodiment comprises at its heart a passage means for guiding and allowing a circular plate body such as a coin to orient vertically and fall naturally. This passage means is a slotted body 11 in the form of a rectangular pipe, which incidentally resembles a plank, and which will hereinafter be referred to as slot body 11. This slot body 11 is suitably formed of a non metallic material such as, for example, rubber or wood or, most preferably, a synthetic resin. A passage 13 extends axially through the slot body 11 and it is through this that a coin 12 may be directed to fall freely and naturally as illustrated in Figure 1B. A first coil 21 for a sensor winds around the exterior of the slot body 11 and thereby surrounds the passage 13. A pair of arched metallic cores are each mounted to an opposing major face, or side wall, of the slot body 11 transverse to the longitudinal axis of the slot body 11 and overlying a respective part of the first coil 21. Each of the arched cores, 15, 16 is elongate, extending for the width of the major face of the slot body 11 and is arch-shaped - i.e. having a U-section form - for its length. Both cores 15, 16 are suitably of ferrite, iron or steel and each has wound around an intermediate part of the length thereof a respective one of a pair of second and third coils 22 and 23 such that the second and third coils 22, 23 lie substantially co-planar with the first coil 21. The arched pair of cores 15, 16 are fixed on their respective opposing side wall of the slot body 11 by a suitable adhesive. The first coil 21 that winds around the slot body 11 and passage 13 is connected to a first oscillation circuit 31. The second and third coils 22 and 23 which are each wound around a respective one of the outlying arched cores 15 and 16 are connected together in series and further connected to a second oscillation circuit 32 (see Figure 2A and Figure 3). A detection circuit 33 is connected to the first oscillation circuit 31, a rectification circuit 35 is connected to the detection circuit 33 and the rectification circuit 35 is connected with an analogue to digital signal converter 37. In corresponding fashion, a detection circuit 34 is connected with the second oscillation circuit 32, a rectification circuit 36 is connected with the detection circuit 34, and the rectification circuit 36 is connected with an analogue to digital signal converter 37. The AD converter 37 is connected with a signal processing unit 38, such as a CPU, and a memory 39 and gate 41 are connected to the signal processing unit 38. In operation of the above described first embodiment, as illustrated in Figure 2B, a first magnetic flux 1 is generated by means of the first oscillation circuit 31 and extends longitudinally of the passage 13 through which a coin 12 inserted into the device falls. A second magnetic flux 2 is generated by means of the second oscillation circuit 32 and crosses the passage 13 of the falling coin 12. The magnetic flux 1 and 2 intersect normally as shown in Figure 2B and there is little or no interference between them. When the coin 12 passes through the passage 13 it alters the amplitude of a first oscillating signal from the first oscillation circuit 31 and also the amplitude of a second oscillating signal from the second oscillation circuit 32. The alteration of amplitude of the first oscillating signal by passage of the coin 12 is detected by the detection circuit 33 and rectified by rectification circuit 35 before being converted into digital data 3 by the A-D converter 37 and transmitted to the signal processing unit 38. In similar fashion, the altered amplitude of the second oscillating signal is detected by the detection circuit 34 and rectified by rectification circuit 36 before being converted to the second set of digital data 4 by the A-D converter 37 and transmitted to the signal processing unit 38. These stages are illustrated in Figure 3. The data 3 from the first coil 21 is primarily indicative of the cross sectional area of the coin 12 but also correlates to the material of the coin 12. On its own, therefore, the information obtained from the use of the first coil 21 can be employed to broadly authenticate a coin 12 passed through the device assuming that reference data for an authentic coin 12 have already been obtained and memorised in the memory 39. The set of data 4 arising from the pair of outlying coils 22-23 primarily corresponds to the diameter of the coin 12 but again also correlates to the material of the coin 12. This data 4 from the pair of outlying coils 22-23 may, therefore, also be used in its own right as a means for authentication of a coin 12. For the owners and operators, of vending machines, money changing machines, gaming machines and the like it is fundamentally important that the device incorporated into the machine for authenticating the user's payment coins or tokens is fully reliable and that the device can properly recognise fake coins or tokens. The combined use of the first sensor coil 21 and the pair of further sensor coils 22, 23 greatly enhances the discriminating power of the device enabling it to effectively discriminate authentic coins or tokens from fake ones as they fall naturally. Once the fallen coin has been thus authenticated a drive signal may be sent to gate 41 and the coin taken into a safe box (not shown). By way of a further enhancement to the device a second embodiment of the invention will now be described. As shown in dotted line on Figure 3, the second embodiment differs from the first in that a detection circuit 51 is connected between the latter part of oscillation circuit 31 and the signal processing unit 38. This further substantially improves the efficiency of the distinction of the coin 12. In this case, since the frequency change of the signal from the first oscillation 31 can be detected, the material of the falling coin 12 can be better distinguished. Turning now to Figure 4, this illustrates a third embodiment of the invention. In this third embodiment the first coil 21 and paired coils 22, 23 are augmented by a fourth coil 54 that winds around the slot body 11 at a level below the other three coils 21, 22, 23. In similar manner to the arrangement of the pair of arched cores 15, 16 overlying the first core 21 on the respective opposing sidewalls of the slot body 11, a pair of further arched cores 52, 53 are provided overlying the fourth conductor 54. Suitably, however, these cores 52, 53 although elongate are preferably relatively short. A third oscillation circuit 55 is connected with the coil 54, a detection circuit 56 is connected with the oscillation circuit 55, a rectification circuit 57 is connected with the detection circuit 56 and the rectification circuit 57 is connected with the A-D converter 37 (see Figure 3). Desirably, the third oscillation circuit 55 generates a signal having a lower frequency than that of the first and second oscillation circuits 31 and 32. When the falling coin 12 passes through the relevant section of the passage 13, the amplitude of the third oscillation signal generated by the third oscillation circuit 55 is altered. This alteration of the amplitude of the third oscillation signal is detected by the detection circuit.55, rectified by the rectification circuit 56 and converted to digital data by the A-D converter 37 and transmitted to the signal processing unit 38. This data primarily correlates to the material of the coin 12 and augments the data from the other coils 21-23, further enhancing the discriminating power of the device. Turning to Figure 5, this illustrates a fourth embodiment of the invention and which differs from the first embodiment in that the first coil surrounding the slot body 11 and the outlying pair of coils 22, 23 are augmented by a further pair of coils 65, 66 installed on the exterior of the slot body 11. Each of these coils 65, 66 lies in a plane substantially parallel to the axis of the passage 13. Each coil 65, 66 is wound around a respective central part 61, 62 of a respective core. In each case the central part 61, 62 has a small pipe form which defines a pot core and further has a larger peripheral flange part 63 ,64 formed on the outer end surface of the pipe-shaped central part 61, 62 and which approximately surrounds the respective coil 65, 66. The coils 65, 66 are connected together in series and are further connected to an oscillation circuit (not shown). A detection circuit (not shown) is connected to the oscillation circuit, a rectification circuit (not shown) is connected with the detection circuit and the rectification circuit is connected to the A-D converter 37 (see Figure 3). Desirably, the oscillation circuit connected to the coils 65-66 generates a signal which has a lower frequency than that of the first and second oscillation circuits 31-32. As shown on Figure 5, when the falling coin 12 passes through the relevant part of the passage 13, the amplitude of the oscillation signal of this latest oscillation circuit is altered. This amplitude change is detected by a detection circuit (not shown), rectified by a rectification circuit (not shown) and converted into digital data by the A-D converter 37 and transmitted to the signal processing unit 38. The data provided by the pair of fifth and sixth coils, 65-66 primarily relates to the material of the coin 12. This further augments the data from the original coils 21-23 to substantially enhance the distinguishing power of the device. For this fourth embodiment, as illustrated in Figure 5, the coils 65-66 need to be arranged to overlie sufficient of the passage 13 to ensure that at least a part of the smallest size of coin 12 to be distinguished will pass over and cover the central pipe-shaped core 61-62 as illustrated. Although the present invention is described above with respect to four preferred embodiments numerous alternative embodiments and modifications of the device in the invention are conceivable within the scope of the invention defined in the accompanying claims. By way of example, the passage 13 although preferably configured to be vertical in use may be slightly inclined. The passage 13 through the slot body 11 generally has its dimensions defined by the largest dimension of circulate plate body/coin to be accommodated. In the illustrated embodiments the slot body 11 has a rectangular cross sectional profile but this might, for example, be varied to a more rounded form of tube which would assist in installation and removal of the coil 21. The arched cores 15, 16, 52 and 53 are illustrated as having a "U" form but may alternatively have an "H" or "C" form in cross section amongst other shapes. The device of the present invention is very simple in construction and yet can momentarily discriminate a coin while the coin falls naturally. Accordingly the device of the present invention can be made relatively compact while achieving a high level of effectiveness and speed of discrimination. In the device of the present invention a first magnetic flux is generated along the direction of fall of the coin and a second magnetic flux is generated across the direction of fall of the coin. These two fluxes intersect each other. Orthogonal crossing of the magnetic flux from the first coil and the second and third coils provides a concentration of flux and greatly enhances the speed with which the device operates. Furthermore, the arrangement of the cores provides for a strong magnetic flux centring on the passing coin and avoiding or minimising external interference.

Claims: A device for discriminating a circular plate body (12), which device (Figure 1A) comprises: a passage means (13) adapted to guide and allow a circular plate body (12) to orient vertically and fall naturally therewithin; a first coil means (21) wound around the passage means (13); and second (22) and third (23) coil means, characterised by second and third core means (15) which each covers the first coil means (21) on a respective opposing side of the passage means (13), the second (22) and third (23) coil means, each being wound around a respective one of said second and third core means (15) about axes parallel to the axis of the passage means (13). A device as claimed in claim 1, wherein the second and third core means (15) are each elongate and extend for substantially the full width of a respective side wall of the passage means (13). A device as claimed in claim 1 or claim 2, wherein the magenetic flux generated by the first coil means (21) and the magnetic flux generated by the second (22) and third (23) coil means intersect normally in the passage means (13). A device as claimed in claim 1, 2 or 3, wherein the passage means (13) is formed of a non metallic material. A device as claimed in claim 4, wherein the passage means (13) is formed of a synthetic resin. A device as claimed in any preceding claim and which comprises a first oscillation circuit (31) to generated an oscillating signal, a detection circuit (33) to detect frequency changes in the oscillating signal and a detection circuit (34) to detect amplitude changes in the oscillating signal. A device as claimed in any preceding claim, which further comprises a fourth coil means (52) wound around the passage means at a level on the passage means above or below the first coil means (21). A device as claimed in any preceding claim, which device further comprises a further pair of coil means (65, 66), each of said further pair being on an opposing side of the passage means (13) and wound around a respective one of a further pair of cores (61, 62), which cores extend substantially perpendicularly to the axis of the passage means (13). A vending machine, money changing machine or gaming machine incorporating the device of any preceding claim.

Inventors: OHTOMO HIROSHI, OHTOMO, HIROSHI
Applicants: ASAHI SEIKO CO LTD, ASAHI SEIKO CO. LTD.
Application year: 1998
Main classification: G07D5
IPC codes: G07D5, G01N27