COIN TESTING DEVICE This invention relates to coin testing devices. Electronic coin testing devices are now well known and very widely used and in most, if not all, cases they comprise two main parts which in an operating condition of the device define between them a narrow space in which coins travel edgewise, usually rolling on a coin track, and one or more coin sensors responsive to one or more characteristics of the coin travelling in the narrow space. The two parts are hinged together so as to be capable of relative movement apart from each other for access to the space between them, for the purpose of cleaning or for the release of coins which have become stuck. The sensors are most commonly in the form of inductive coils, usually mounted in pot cores. Sometimes a coil is mounted only to one side of the coin path and operates on its own. Another configuration consists of two coils located opposite each other across the coin path and driven either in series or in parallel by a common oscillator. In another configuration, two coils are located opposite each other across the coin path and one is driven by an oscillator whereas the other acts as a receiver to detect the magnetic field transmitted by the other which will have been influenced by one or more

characteristics of any coin passing between the two coils. The main coin characteristics which are measured using such sensors are diameter, thickness and material and the way in which they may be used in conjunction with examination circuitry to take measurements upon a coin, and to check the measured values -against reference values representative of acceptable coins, is described in more detail in, for example, GB -A- 2093620. In some coin testing devices, optical sensors are used as well as or instead of inductive sensors and these usually include a light transmitting device on one side of the coin path and a light detecting device on the other side of the path, so as to be able to detect the moments at which a coin arrives at or departs from the location of the sensor. Sensors of this type may be used to evaluate coin dimensions, or to control the timing of other events occurring in the coin testing device. For the purposes of this description and the claims which follow, the term "sensor element" will be used to refer to a component which is mounted as a unit, whether it is a complete sensor as for example a single coil operating independently, or only part of a . complete sensor as for example one of a pair of series or parallel connected coils, one of a pair of

transmitter/receiver coils, or one of a pair of transmitting/receiving optical devices.

For reliable operation of such testing devices, it is important for each sensor element to be in a known predetermined position relative to the path of the coin past it, for the two sens_ox elemen s., o . each pair, when they are co-operating in pairs (whether inductive or optical) to be accurately in register with each other and also to be accurately at a predetermined distance away from each other across the coin path. In many situations, the walls which define the coin path will be inclined to the vertical so that the coin will roll along the track in contact with one wall, and a test is applied to the coin using a single inductive sensor element which is located in the other wall. The output of the sensor element can then be indicative of the thickness of the coin, because the thicker the coin, the closer is its nearer surface to the sensor, but, of course, this relies upon the coin-contacting wall being exactly a predetermined distance away from the sensor.

In all the above situations, and in others, the accuracy and reliability of the device are in part dependent upon the two relatively movable parts of the device being accurately located.relative to each othor when the device is in its closed or operating

4 condition and for this accuracy of location to be maintained despite freguent opening of the device, which may be done clumsily and put strain on the hinge. 5 The hinge itself has normally had a major function in positioning the two parts relative,to. each other when they are closed together, so that any dimensional variations occurring in the manufacture of the hinge or of its assembly or any distortions in the

10 hinge which might be caused during clumsy operation in use, have produced corresponding geometrical variations between one device and another, or in an individual device at different times, and this has caused variations in performance between one device

15 and another and in the performance of an individual device at different times of its life.

An object of the present invention is to improve the accuracy and consistency with which the two main parts of an openable and closeable coin testing

20 device are located relative to each other when it is in its closed or operating condition by making these factors less sensitive to manufacturing variations and, where a hinge mechanism is used, substantially completely independent of any variations occurring in

25 the manufacture of, and/or distortion of, the hinge mechanism.

The invention provides a coin testing device comprising two parts which in an operating, closed, condition of the device define between them a narrow space in which coins travel edgewise, and one or more coin sensor elements mounted on at least one of the parts, the two parts being capable, of relative movement apart from each other for access to the space between them, characterised in that the two parts are provided with location-defining features at three positions which are spaced apart to form a triangle, that when the two parts are being brought together from their apart position they are sufficiently displaceable relative to each other to be able to adopt final closed positions determined only by contact between the location-defining features, and that means is provided for urging the parts towards each other at a position within said triangle. Because the parts are urged together at a position within the triangle, contact at all three positions is always ensured. Because there are only three contact positions, there is no possibility of one part rocking relative to the other part when they are pressed together, so that this particular potential source of performance variation during operation is eliminated.

In a particularly advantageous embodiment, at one said position said contact is such as to permit no relative movement of the closed parts, at a second said position said contact is such as to permit relative movement of the parts only along one axis which is substantially parallel to the plane of said space and extends generally towards said one position, and at the third said position said contact is such as to permit relative movement of the parts in a plane substantially parallel to the plane of said space.

Although the disadvantages of a hinge mechanism in locating the two parts are avoided, the convenience of a hinge mechanism for opening the parts relative to each other, may, in accordance with a further feature of the invention, be retained, since a hinge mechanism may be provided which enables the parts to be moved apart with a pivotal movement and supports one part relative to the other when they are apart, the hinge mechani≤m being coupled loosely to one of the parts so as to permit said relative displacement as they are closed together.

■- The hinge mechanism may comprise a hinge arm pivotally mounted to one part and loosely coupled to the other part. It should also be appreciated, of course, that the invention in its broadest aspect enables accurate

location of the two device parts even in a device designed without any hinge mechanism mechanically coupling the parts.

Preferably, the hinge arm extends to a location, on that part to which it is loosely coupled, which location lies within said triangle, and at that location is provided with a bearing surface for contacting that part, and biassing means biasses the hinge arm so that its bearing surface contacts that part to urge it towards to other part.

In order that the invention may be more clearly understood, a preferred embodiment will now be described, by way of example, with reference to the accompanying diagrammatic drawings in which: Figure 1 is a perspective view of a coin testing device in accordance with the invention,

Figure 2 is an exploded view of the device shown in Figure 1,

Figure 3 is a plan view of the inner wall of one main part of the device,

Figure 4 is a plan view of the inner wall of the other main part of the device,

Figure 5 is an elevation taken in the direction of arrow X in Figure l, and Figure 6 is a cross-section through the entire coin testing device in its Figure 1 configuration, but

taken along the line indicated for convenience at A-A in Figure 5.

The device shown in the drawings comprises two main parts which for convenience will be referred to as the body 2 and the lid 4, both being one-piece plastics mouldings. In the operating or closed condition of the device shown in Figure 1 the body and lid define between them a narrow space 6 of substantially uniform width. By means of a suitable coin entry arrangement such as a cup or chute, as is well known, coins will be delivered to the device substantially vertically and edgewise into the left hand end of the narrow space 6 as viewed in Figure 1.

The coin hits a coin track 8 which is the upper surface= of a flat protrusion 9 moulded integrally on the inner wall 10 of the lid in known fashion (see also Figure 4) . Coin track 8 slopes downwards towards the right as seen in Figures 1 and 2, the position of the coin track relative to the body 2 being indicated by the broken line 8 ¹ in Figures 2 and 3.

Three inductive sensor elements in the form of coils 12, 14 and 16 are mounted in conventional manner within the lid 4 on the back of its inner wall 10, at pre-determined positions above the level of the coin track 8. Three further sensor elements in the form of coils indicated in broken lines 12' , 14' and 16* are

similarly mounted inside the body 2 and, as mentioned, when the device is assembled and in its operating condition it is desired for the sensor elements to be located precisely opposite each other in pairs 12, 12'; 14, 14* ; and 16, 16• . The manner of operation of the sensor elements forms no part of the present invention, and there are many known ways of operating such sensors formed by such coils in co-operating pairs, such that a respective pair is responsive respectively primarily to diameter, thickness and material of the coin. The sensor signals are transmitted to validating or discriminating circuitry schematically illustrated in the body 2 at 18 which circuitry may in known manner check the sensor outputs against reference values to determine whether or not a coin is acceptable, and generate an accept signal to cause acceptance of the coin if it is acceptable, and normally also generate a signal to indicate the denomination of an acceptable coin. Again, the validation, technique forms no part of the present invention and therefore need not be described in further detail.

The body 2 and lid 4 contact each other only through location-defining features which are at three positions spaced apart to form a triangle. At the first position, the contact is between the sides of a

flat-topped cone 20 integrally moulded on the lid 4 (in Figure 2 the lid is shown as though partly transparent so as to illustrate the cone, and see also Figure 6) and the sides of a conical recess 20' in the body 2. The conical angle of the recess is the same as that of the cone. The second contact is between the sides of a cone 22 the same as cone 20 and moulded on the inner wall 10 of the lid 4, and the walls of a linear or elongated recess 22' in body 2, this recess having sloping sides at an angle equal to the angle of the cone 22. The third contact is between the tip of a third cone 24 the same as cones 20 and 22 moulded on the inner wall 10 of the lid 4, and a flat surface 24' which is the base of a recess in the body 2, but which might i_n fact be a part of the main surface of the body 2. The location-defining effect of the cones 20, 22 and 24, recesses 20' and 22*, and surface 24' will be explained later, but it is mentioned here that ideally the three types of contact would be respectively point-to-point, point-to-line and point- to-surface. The use of small surfaces instead of points and a line closely approximates to this and is adopted to minimise the effects of wear on the components which are normally made of plastics. The lid 4 is urged towards the body 2 at a position within the triangle, and indeed close to the

centre of the triangle, by the free end 26 of a hinge arm 28 bearing on the tip of another integral cone 30 on the lid 4, via a bearing surface which is a concave surface 32 within the free end 26. This pressure, since it lies within the triangle formed by the three contact positions., insures that constant contact between the two parts is always made at those positions so long as the device is in its operating condition and so the alignment and spacing given by the three-position contact arrangement is maintained constant.

The hinge mechanism including the hinge arm 28 just referred to will now be further described. A hinge mounting 34 has two feet 36 of T-shaped cross- section as shown in Figure 2 and these feet push into slots (not shown, but mirror images of the slots 38 indicated in the lid 4) in the back of body 2, thus fixing the hinge mounting 34 to the body 2. This fixing need not be highly accurate since as will become apparent it has no effect on the relative positioning of lid 4 and body 2 in the operating condition. The hinge mounting 34 has two arms 38 which on their inner sides are formed with opposed recesses 40 (only one visible in Figure 2) into which fit pivot pegs 42 which project from opposite sides of the other end of the hinge arm 28, so that the hinge

12 arm 28 is pivotally mounted to the body 2.

A peg 44 having a conical leading end 46 and a head 48 ^* is a strong interference fit in a socket 50 moulded inside the lid 4 and the shank 52 of the peg 5 44 passes loosely through an aperture 54 intermediate the two ends of the hinge arm 28 and nearer to its free end 26. Thus, the peg 44 only loosely couples the lid 4 to the hinge arm 28. A tension spring 56 has one end hooked over a hook-like formation 58 which

10 is integral with the hinge mounting 34 (see Figures 2 and 6) and the other end hooked over a hook 60 integral with the hinge arm 28.

Spring 56 biasses the hinge arm 28 anti-clockwise as seen in Figure 6 and hence the bearing surface 32

15 at the end of the hinge arm constantly presses on the cone 30 to maintain the three-position contact between the lid and the body. However, there is sufficient looseness between peg 44 and aperture 54, and sufficient play available between the cone 30 and

20 bearing, surface 32, that when the lid and body are being brought together from their open position they are sufficiently displaceable relative to each other that they are free to adopt final closed positions determined only by the contacts between the location-

25 defining features. Consequently the hinge mechanism pays no part in determining the relative locations of

the lid and body except simply to hold them together. The relative displaceability of the two parts could be achieved by not mechanically connecting them by a hinge at all. This would effectively be the case if the peg 44 were omitted, in which case lid 4 would be freely releasable from the body 2 and hinge arm 28 would serve only to apply a holding pressure.

The point-type contact at 20, 20' determines completely the spacing between, and the relative positions of (both in the vertical and horizontal directions) , the lid 4 and body 2 at that position. If, due to manufacturing variations, there is a slight variation in the distance between the tip of cone 20 and the tip of cone 22 on the lid, the cone 22 will still locate properly at some point along the length of elongated recess 22', and because the longitudinal axis of the recess 22* intersects recess 20' as indicated by the chain-dotted line in Figure 3, this variation will not produce any variation in the angular orientation of lid 4 relative to body 2. If the axis of recess 22* extends generally towards recess 20* but does not actually intersect it, this angular invariability will still be partly, but not completely, achieved. Also, at contact 22, 22* the spacing between lid 4 and body 2 is independent of the exact position at which cone 22 sits in recess 22'

because of the uniform linear nature of the recess, so spacing at this position is well controlled.

The only remaining freedom for relative movement is for rotation about the chain-dotted line joining recess 20' and recess 22' in Figure 3 and such rotation is prevented by contact of the tip of cone 24 on flat surface 24' . There is the possibility of variations in the distance of cone 24 from cone 20 and also from cone 22 due to manufacturing inconsistencies, but the size and flatness of surface 24' enable these variations to be accommodated without any "misfitting" occurring and without any tendency to disturb either the relative angles of lid 4 and body 2 or the spacing between them. In the above description the term "freedom for relative movement" has been employed, which is a term well understood in the art. It will be appreciated that such relative movement does not occur in an individual coin testing device when it is in its closed or operating condition. What does occur is the accommodation of manufacturing tolerances which vary between the lids and bodies of different devices. The references to relative movement are believed to be a graphic and helpful way of indicating this. - In the above manner, and assuming that the six coils are correctly positioned in body 2 and lid 4,

precise registration of each coil with the opposite one is ensured, the spacing between the two coils of each pair and also the spacing between each coil and the opposite wall of the narrow space 6 are precisely controlled, and the position, relative to body coils 12* , 14' and 16' , of the path of a coin rolling on track 8 of lid 4 is precisely determined, all by the operation of the three-position contact arrangement described, and without being influenced by any variations in the manufacture of hinge mounting 34, hinge arm 28, their connections to the body 2 and lid 4, and their assembly together. It should be mentioned that the device is intended to be mounted at an inclination to the vertical so that coins roll on track 8 in constant contact with the inner wall of body 2 thus stabilising their path. This can also be achieved, as known, by mounting the device vertically but having the inner walls inclined within it.

It can been seen from Figures 1 and 2 that one pair of coils 16, 16" are oval such that they can respond to the position, relative to the coin track, of the upper edge of the coin when it is centred between those coils. The coin will then, depending upon its diameter, occlude the coils from their lower limits up to the top edge of the coin so that the proportion of the coils occluded will depend upon the

diameter of the coin. The fact that the linear contact 22, 22' lies on an axis intersecting the point contact, 20, 20', and that line extends substantially in the saae direction as the coin track, minimises in particular the extent to which manufacturing variations will adversely affect the operation of sensors of this type, which respond to the position relative . to a sensor element, and in a direction generally perpendicular to the coin track, of a part of the coin. This is because the ability of variations in the spacing between cones 20 and 22 to cause relative rotation of lid and body about cone 20 in the plane of the coin path is eliminated so accurate relative positioning of a sensor element on one of them and the coin track on the other is improve .

When it is desired to open the lid 4 away from the body 2, the initial movement can be translation rather than pivotal movement, because of the limited amount of angular movement available between lid 4 and hinge arm 28 due to the loose coupling between them. This facilitates the release of stuck coins from between lid 4 and body 2 since they can be moved a limited distance apart, even at the hinge end, without the fax end having to swing very far. This is an advantage in certain restricted locations where the

testing device might be fitted. Further opening, for example for cleaning, requires that the lid 4 pivots round and up with the hinge arm 28 and eventually the centre of tension spring 56 passes through the axis of pegs 42 giving an over-centre action so that the spring can hold the lid 4 open at just over 90° to the body 2.

The testing device shown may be given a different configuration. The hinge mounting 34 may have its feet 36 fitted into the T-shaped slots 38 in lid 4 instead of the slots in body 2, in which case the hinge arm 28 will reach round from the lid to the far side of the body 2 as viewed in Figures 1 and 2. It can be seen from Figure 6 that body 2 is provided with a cone 32' and a socket 50' identical to, and in identical positions to, cone 32 and socket 50 on the lid 4, so that the peg 44 can be used to loosely secure hinge arm 28 to body 2 by fitting into socket 50', and the free end 26 of hinge arm 28 will press body 2 against lid 4 by bearing on cone 32'. In this configuration, it would be the part 4 that would be stationary in the installation of the coin testing device and the part 2 would become the movable or openable part. Thus, both parts are capable of serving either as a stationary body or as an openable lid.