DESCRIPTION

This invention relates to an optically coded token detection system and a token therefor and has particular but not exclusive application to coin validation systems utilising both tokens and genuine coins.

It is well known to use both coins and tokens in coin operated amusement machines, the tokens being typically minted from brass or similar materials. Many unsecure tokens of similar dimensions are in circulation and are sometimes undesirably being used in machines to which they do not belong, at great loss to the machine owner.

In order to improve security, the tokens have been provided with a groove in a characteristic position and machines belonging to a particular owner are provided with a token entry opening covered by a plate which includes a slot having a shape corresponding to that of

the grooved token. Two types of grooved tokens have been used hitherto. The first type of token has a groove that extends across a circular face of the token in a predetermined chordal position. The groove needs to align with a corresponding projection in the slot of the cover plate to be acceptable. This type of token is inconvenient to use because it must be manually aligned with the projection in the cover plate slot and must be slid into the opening, with a possibility of sticking at coin entry.

The second type of grooved token is formed with a profiled rim to cooperate with a correspondingly formed entry slot in the cover plate. However, the registration between the token and the entry slot can be defrauded by using tokens which are slightly thinner or of smaller diameter than the true token.

With both of these mechanically keyed tokens, it has been necessary to provide two entry slots on the amusement machines, one for normal coins and one fitted with a cover plate to accept the token. Conventionally, this has required the fitting of two coin validators, one for coins and one for the tokens.

With the increasing use of electronic coin validation, it has been necessary to retain two coin entry slots each fitted with detection means prior to the main electronic validator. An example of such an arrangement is described in our UK Patent Application No. 8631054 filed 31st December 1986.

It has in the past been proposed to use an optical code on a token and an example of such an arrangement is disclosed in UK-A-1 164 170.

The present invention provides a simpler optically coded token detection system wherein the tokens are inexpensive to manufacture and detection of the code is readily achieved.

In accordance with the present invention, there is provided an optically coded token detection system comprising a token formed with at least one surface undulation thereon, optical detection means, and means defining a passageway for the token past the detector means, the detector means including a source of optical radiation and a detector for detecting radiation reflected by the token from the source upon

passage of the token past the detector means, the undulation on the token being so arranged as to alter selectively the amount of radiation reflected from the source by the token to the detector, whereby to provide an indication of the presence or absence of said undulation.

Thus, one or more undulations can be provided on the token to provide it with a characteristic code.

Conveniently, the token comprises a disc shaped me eber having opposed planar surfaces and the undulation(s) comprise one or more concentric circular grooves formed in the planar surfaces.

The grooves may have side walls inclined at respective different angles to the planar surface of the disc shaped token and the detecting means may be configured to provide different characteristic signals in response to the detected angle of the groove side wall.

Alternatively, the surface undulations can comprise projections formed on a surface of the token.

In order that the invention may be more fully understood embodiments thereof will now be described by way of example with reference to the accompanying drawings in which:

Figure 1 is a schematic illustration of one form of token for use in a system according to the invention;

Figure 2 illustrates schematically a first embodiment of detecting means; Figure 3 illustrates output waveforms produced by the detecting means of Figure 2, for a groove having one inclined side wall and one side wall orthogonal to the planar surface of the token;

Figure 4 illustrates schematically the output waveforms produced for a groove having two inclined side walls;

Figure 5 illustrates schematically a second form of detecting means utilising a single optical source and detector; and

Figure 6 illustrates schematically a practical form of the invention embodied in a coin validator for discriminating between acceptable tokens and coins, and frauds.

Referring firstly to Figure 1, this shows a token 1 for use in a system according to the invention. The token consists of a discoidal blank of a base metal which has been formed by stamping so as to include in its planar surfaces a number of concentric grooves 2 to 6 that define a characteristic code. This code can be defined by the presence or absence of a groove together with the inclination of the side walls of each groove, as will be explained in more detail hereinafter.

In use, the token rolls past a detection station 7 in the direction of arrow A, so as to detect the characteristic code. The detecting station 7 detects the presence or absence of the grooves on the token and may also detect the inclination of side walls of the grooves.

Thus, in the arrangement shown in Figure 1, the radially outermost groove 1 and the radially innermost groove 6 can be used to define "start" and "stop" bits for the code and the presence of further grooves between the grooves 1 and 6 define further bits within the code. It will be seen that when the token rolls past the detector 7, the code will be detected in a

first occurrence for the leading sector of token 1 and for a second occurrence for the trailing sector, in a reverse bit sequence. After appropriate processing and storing, these two detections can be compared for error checking purposes.

Referring now to Figure 2, this shows an example of the detecting station 7 in more detail. Three optical sensors SI, S2, S3 are provided, each comprising an infrared source and an infrared detector embodied in a single unit. The sensors SI, S2, S3 are shown disposed adjacent to the token 1, which is represented in. partial cross section. For the purpose of illustration the token 1 is shown to include a relatively wide groove 8 (corresponding to one of the grooves 2 to 6 shown in Figure 1) that has a floor portion 9 coplanar with planar disc shaped outer surface 10 of the token. The groove also has side walls 11, 12 disposed at 45° to the planar surface 1.

The radiation sources of the sensors SI, S2, S3 are arranged to direct radiation e.g. infrared radiation in the direction of solid lines 13, 14, 15. If the token surfaces reflect radiation along the solid lines

16, 17, 18, each of the associated detectors on the sensors SI, S2, S3 provides a relatively high electrical output. However, if radiation is reflected along the dotted lines 19, 20, 21, it does not reach the detectors and hence a corresponding relatively low output is produced. The optical axis of the sensors SI and S3 are arranged at 45° to the plane of the token whereas the optical axis of the sensor S2 is arranged at 90° to the token's planar surface 10. Thus, from Figure 2 it will be seen that for the sensor SI, a relatively high electrical output is produced when the inclined surface 11 becomes aligned with its optical axis; otherwise it produces a relatively low output. Similarly, for the sensor S3, the oppositely inclined surface 12 will produce a high output. For sensor S2, a high output is produced in the presence of the planar floor 9. However the planar surface 10 produces reflection along dotted line 20 and consequently a low output is produced.

The resulting output waveforms from the sensors SI, S2 and S3 can be seen from Figure 4, as the token rolls past the detecting station 7. Also shown in Figure 4 is the differential output of sensor S2. Those skilled

in the art will appreciate that the differential output of S2 can be logically combined with the output of sensors SI and S3 to detect unambiguously the passage of the groove 8 past the detecting station 7.

Figure 3 shows corresponding waveforms for a groove which has only one inclined sidewall together with one orthogonal side wall 22. It will be seen that the sensors SI - S3 provide a different set of outputs which can be used to detect unambiguously the presence of such a groove in the token.

A simpler form of the detecting station 8 is shown in Figure 5. In this embodiment, a single sensor S4 is provided with its optical axis X-X' arranged orthogonal to a side wall of a V-shaped groove 23 formed in the token 1. Typically, the side walls of the groove are formed at 45° to the surface 10 of the token. When the side wall of the groove becomes aligned with the optical axis X-X' of the sensor S4, a relatively high output is provided by its optical detector, as shown in Figure 5a. However, as shown in Figure 5b, in the absence of the groove, light is reflected away from the

detector in the direction of the dotted line so that the detector provides a relatively low output.

In the foregoing embodiments it will be appreciated that the depth of the groove will determine the amount of light deflected away from the sensors when the groove is not present, and also the duration of the rising and falling edges and the duration of the pulses out of the 45° sensors Si, S3 and S4. Therefore, the deeper the groove the better the signal to noise ratio.

In order to improve performance, the surface of the token may be provided with a reflective coating, e.g. a nickel coating. By utilising infrared radiation, the effect of dirt on the token surface is minimised.

The inclined arrangement of the sensors SI, S3, S4 provide protection against fraud. One possible way of attempting to defraud the system would be to photocopy the token and paste a copy thereof onto a washer. However, the resulting two dimensional arrangement would not trigger operation of the sensor S4 or the sensors SI, S3 and thus would not be successful.

Referring now to Figure 6, a schematic realisation of a coin validator incorporating a token acceptor, in accordance with the invention, is shown wherein a coin rundown path 25 has a coin inlet opening 26 and leads to a coin acceptor chute 27 for acceptable coins and tokens and a coin reject chute 28. Acceptable coins are detected by means of inductive sensing coils 29 to 31. Coil 29 is of a relatively small diameter and disposed on one side of the coin rundown path. Coil 30 is of a larger diameter and is disposed on the opposite side of the coin rundown path to coil 29. Coil 31 surrounds the coil rundown path 25. The coils 29 to 31 are driven at respective different frequencies by validation and drive circuitry 32. An example of a suitable form of coin validator is described in our UK-A-2 169 429 to which reference is directed. Broadly, the coils are energised to form an inductive coupling with a coin as it passes along the rundown path 25 and the degree of interaction is compared with stored values corresponding to acceptable coins by means of a microprocessor in the circuitry 32. Upon detection of an acceptable coin, the microprocessor commands a solenoid operated gate 33 to open and allow the coin to pass down the passageway 27; otherwise the coin is

rejected along passageway 28. In accordance with the invention, the validation and drive circuits 32 additionally are arranged to energise the infrared source(s) of the detector arrangement 7. Also, the microprocessor in the circuitry 32 is responsive to the condition of the sensors SI - S3 (or S4). Thus, for tokens, the microprocessor receives a digital code produced in response to the outputs of SI - S3 or S4, corresponding to the code formed on the token 1. This code is compared with stored values thereof by means of the microprocessor and the solenoid operated gate 33 is controlled either to reject or accept the token in dependence upon the comparison carried out by the microprocessor. Thus, a single coin entry opening 26 can be provided both for tokens and coins i.e. without the need for separate entry slots as in the prior art.

The stored value of the code can be programmed into the memory circuits associated with the microprocessor by a software driven arrangement used for setting acceptable coin values. Alternatively, a much simpler arrangement can be used wherein DIL switches 34 are connected to the circuitry to define a digital code corresponding to

the token. This allows a very simple form of re-programming in the field, for different token codes Also, it will be appreciated that the token detection system need not be incorporated into a conventional validator but could instead comprise a separate modular unit for use with a conventional validator.

Many modifications and variations will be apparent to those skilled in the art. Thus, whilst the described embodiments utilise grooves, it will be appreciated that a similar effect could be provided by ridges formed on the surface of the token. Furthermore, different types of optical detecting stations could be utilised. Light could be directed to the token by means of optical fibres to provide greater accuracy of focusing. Also, purpose designed plastic lens systems may be provided. Furthermore, the code may be formed on both disc surfaces and two detecting stations 7 may be provided on opposite sides of the passageway to improve the accuracy of detection.