GB2226678A - Coin discriminator - Google Patents

Abstract

A coin discriminator has an opening 2 to receive a coin. Entry of the coin pushes back a slider 4 to enable the coin to pass along a coin rundown path 5 to a pivotally mounted sensing arm 6 that is connected to a pivoted vane 8. The coin pivots the arm 6 by an amount dependent upon the diameter of the coin, and this movement is converted into a larger movement of the outer portion of the vane 8. The displacement of the vane is detected by an optical detector 10 which produces a number of electrical pulses dependent upon the number of holes 9 which are swept past it. Electrical contacts (17, 18) (Figure 3) are utilised to test whether the coin is metallic. <IMAGE>

Description

COIN DISCRININATOR DESCRIPTION The invention relates to a coin discriminator and has application to the provision of coin-operated services.

In particular, though not exclusively, the invention relates to a low cost and low power-consuming discriminator for accepting a variety of coins through a single slot and discriminating between a range of coins to be accepted and a range of coins (including fraudulent blanks) to be rejected. A particular aim of the invention is to provide a low cost coin discrimination while accepting some degradation of resistance to frauding. The invention therefore has applicatiqn to low cost coin-operated machines vending goods or services in a preferably supervised or "benign" environment and in particular to low cost supervised-environment paytelephones.

Traditionally, coin discriminators have divided into two main classes; mechanical and electronic. Because coins of very different monetary value may be physically similar, coin discriminators tend to be constructed either using large numbers of precision components or requiring extensive calibration or both.

Also whereas electronic measurements tend to be good at measuring some properties of a coin, such as metal type, they can be poor at measuring other properties of a coin such as its physical diameter. Diameter, however, is one of the key parameters of a coin. Also, the position of the coin at the point (or points) of measurement needs to be very accurately controlled.

The problems, particularly of accuracy of coin position at the point, or points of measurement, multiply as multi-coin discrimination through a single coin-entry slot is attempted, thereby tending to increase further the cost of the final coin discriminator.

The invention solves these problems and substantially reduces costs. It can make an accurate mechanical measurement of coin diameter by using the principle of leverage to convert small differences in diameter into large physical movements which can be measured with a relatively imprecise sensor.

Broadly stated, the present invention provides a coin discriminator comprising lever means including a first lever portion for being moved by a first amount dependent on a dimensional parameter of a coin under test, and a second lever portion driven as a function of movement of the first lever portion by a second amount greater than said first amount, and sensor means for sensing the movement of the second lever portion to provide a signal as a function of said coin parameter.

The invention is described below by way of example with reference to the accompanying drawings wherein: Figure 1 is a schematic diagram of the mechanical layout of a coin discriminator according to the invention; Figure 2 is an enlarged schematic view of a hook and peg arrangement shown in Figure 1; Figure 3 illustrates a coin passing metal contacts in the coin path; Figures 4 to 7 illustrate the sequence of mechanical operation of the discriminator shown in Figure 1; Figure 8 is a schematic waveform of a sequence of pulses produced by the sensor shown in Figures 1 to 5; and Figure 9 is a schematic block diagram of electrical circuits of the discriminator The mechanical layout of the coin discriminator is shown in Figure 1.The geometry of the layout shown is purely by way of example to show the principle of operation of the device and may vary substantially in individual practical realisations.

The coin discriminator consists of a body 1 in which is placed an opening for a coin rundown path, and a fixed anvil 3. The opening 2 is obstructed by a slider 4 which is constrained to move in the direction A-B and is biassed by spring force so as to obstruct the coin path. The movement is damped when moving from A to B, i.e. when pushing the coin into the mechanism, but undamped when moving from B to A when the coin is inserted.

The damper consists of a flexible bellows sealed at one end and with a non return diaphram at the other. When the coin is inserted the bellows is compressed expelling the air. As the slider moves forward pushing the coin into the mechanism its speed of entry is controlled by the amount of air allowed to bleed into the bellows through the valve. The coin rundown path in region 5 leads to a sensing arm 6 which partially blocks the coin path and is constrained to rotate about a pivot point 7. The sensing arm 6 is biassed by a spring to the position shown in Figure 1 providing maximum possible obstruction of the coin path. The sensing arm 6 is attached to (and preferentially is part of the same component as) a vane 8 which is arranged in a parallel plane to the coin rundown path region 5 and does not obstruct it in any way. An optical sensor is provided to sense movement of the vane 8.To this end the vane 8 is generally opaque but is pierced by small holes or provided with transparent windows 9 so arranged that when the vane rotates, a sensing beam from a light source projected across coin path exit 11 to an optical detector 10 is alternately obstructed and unobstructed. The sensing arm 6 and the vane 8 constitute first and second portions of a lever which as will be explained in detail hereinafter, is rotated by passage of a coin under test by an amount dependent upon its diameter. The coin engages and rotates the sensing arm by a relatively small amount, which is amplified into large movement of the vane 8.

This is detected by means of detector 10, which can be a relatively imprecise measuring device in relation to the variations of actual coin diameter.

A locking lever 12 is constrained to rotate about a pivot point 13. The locking lever 12 features a peg 14 which projects across the coin path 5 and which retracts into a recess 3a in the underside of the coin entry anvil 3 when the locking lever rotates. The locking lever 12 also includes a hook 15 and is biassed by spring force such that in its rest position the hook mates to a peg 16 which projects from the sensing arm 6. This arrangement is shown in more detail in Figure 2. The peg 16 can only be released from the arm 12 by movement downwardly so as to release from the hook 15.

Referring to Figure 3, two metal contacts 17, 18 project into the coin path at a position downstream of the sensing arm 6. A coin 19 completes an electrical circuit between the contacts 17, 18 only if it is conductive.

Figures 4 to 7 demonstrate the sequence of operation of the coin mechanism upon insertion of a coin.

In Figure 4, insertion of a coin 19 into the coin rundown path opening 2, forces the slider 14 back against its spring as the coin is urged against the coin entry anvil 3. Continued insertion of the coin brings the coin to the point where its entire diameter is disposed between the slider 4 and the anvil 3.

Thereafter the movement of the coin further into the mechanism is maintained by the spring force on the slider 4 as the slider returns to its rest position 4.

The acceleration of the coin at this point controlled by the damper (not shown) on the slider. Thus the coin moves along the path and contacts the sensing arm 6 and the locking lever 12. The coin releases the sending arm 6 from the locking leverl 12, but only if the coin contacts both of the arm 6 and lever 12 simultaneously, thus ensuring that the coin is in the correct position to have its diameter measured, as will now be explained.

In Figure 5, the coin 19 moves forward to deflect the locking lever peg 14 into the recess 3a beneath the coin entry anvil 3 upon release of the sensing arm 6 from the locking lever 12. Further movement of the coin then causes the sensing arm 6 to deflect thereby causing a sequence of obstructions and unobstructions of the light path to the optical detector 10 as the vane 8 rotates past it. This sequence of obstructions and unobstructions for the optical sensor is counted by the associated electronics described hereinafter with reference to Figure 8 and is a measure of the diameter of the coin.

In Figure 6, the coin 19 has passed the sensing arm 6 which has returned to its rest position with a corresponding sequence of obstructions and unobstructions of the optical detector 10. The locking lever 12 has also returns to its rest position to lock the sensing arm 6 again. The geometries of coin path 11 and vane 8 are such that the vane has returned to its rest -position leaving the optical detector 10 unobstructed for a period of time before the coin arrives at the point where it obstructs the optical sensor.

The coin 19 at this stage makes contact with the metal detector contacts 17, 18 (Figure 3), permitting the electronics to conform that the coin is electrically conductive, hence reducing the risk of fraudulent use of non-metallic discs and the like.

In Figure 7, the coin is just leaving the coin discriminator via the coin path exit 11 and is just clearing the optical detector 10 having obstructed it in the final part of its passage.

Figure 8 shows the output signal produced by the optical sensor 10 for the sequence of obstructions and unobstructions produced by movement of the holes 9 in the vane 8 past the optical detector 10 for coins of different diameters. The output signal contains a sections 20 including a sequence of pulses produced by the coin deflecting the sensing arm 6 forwardly, a section 21 produced by the backswing of the sensing arm 6 as it returns to its rest position, section 22 where the sensing arm 6 has returned to its rest position when the coin is still moving towards the optical detector 10 which is therefore unobstructed, and section 23 where the passage of the coin itself obstructs the detector 10 prior to leaving the mechanism.

Figure 7 is a block diagram of the electronics associated with the discriminator, which consist of the optical detector 10, a buffer 24, a counter 25, a microprocessor 25 and a memory 27 which is preferably non-volatile. The actual realisation of the electronics may vary since in some instances some functions may be more conveniently performed by software and in other instances by hardware.

Nevertheless the block diagram describes in principle the operations which are to be performed.

The output of the optical detector 10 is converted into a sequence of electrical pulses of suitable voltage waveform by the buffer 24 which then feed into the counter 25. Upon completion of the sequences of pulses due to movement of the sensing arm as shown as 20 and 21 in Figure 8, the count of pulses is read by the microprocessor 25. The output of optical detector 10 is als monitored by the microprocessor to determine from sections 22 and 23 of the signal sequence that the coin has passed from the coin exit path to the cashbox of the host machine and the counter is then reset ready for entry of a subsequent coin. The whole sequence preferentially occurs within a time-out period or timeout periods applied by the microprocessor to minimise the risk of fraud either by external manipulation of the sensing arm or by other methods.

The count read by the microprocessor 26 from the counter 25 is then compared with values stored within the memory 27. If the value matches one which has been pre-determined as being that of a valid coin, the value of the coin is used to give credit for vending of goods or services in the host machine.

Whilst the principle of measurement described hereinbefore is used to measure coin diameter it could be used to measure coin thickness. Also, both diameter and thickness could be measured by a combination of two such sensing arms in a device with enhanced discrimination.

It is also possible for optimum security against fraudulent slugs to combine the mechanical measurement of coin parameters as described with a more sophisticated metal detector than the electrodes 17, 18 described hereinbefore.

Finally, the measurement of the deflection of the sensing arm need not be by counting a sequence of obstructions of an optical sensor as described, but could be done by a variety of other techniques such as making the vane to be one plate of a variable capacitor and measuring the change in capacitance, connecting the vane to a rotational potentiometer and measuring the change in voltage, or causing the sensing arm to move a permeable core within a sensing coil and measuring the change in inductance.

Claims (15)

1. A coin discriminator comprising lever means including a first lever portion for being moved by a first amount dependent on a dimensional parameter of a coin under test, and a second lever portion driven as a function of movement of the first lever portion by a second amount greater than said first amount, and sensor means for sensing the movement of the second lever portion to provide a signal as a function of said coin parameter.

2. A coin discriminator according to claim 1 including releasable latching means for holding said lever means in a predetermined relationship to the sensor means, said latching means being operative to release the lever means in response to contact by a coin under test.

3. A coin discriminator according to claim 1 or 2 wherein the first lever portion includes a sensing arm operative to be pivoted through an angle dependent upon said dimensional parameter of the coin under test, and the second lever portion includes a vane to be pivoted by movement of the sensing arm.

4. A coin discriminator according to claim 3 wherein the sensor means comprises an optical detector, a light source, and a plurality of translucent and non-translucent portions in the vane, whereby the optical detector produces electrical pulses in dependence upon the movement of the vane.

5. A coin discriminator according to claim 4 including spring means acting on the lever means such that in response to the coin the vane is rotated through an angle such that the optical detector produces a first sequence of pulses, and then the vane is returned by the spring means through said angle such that the detector produces a second sequence of pulses.

6. A coin discriminator according to claim 4 or 5 including electrical counting means for counting said pulses.

7. A coin discriminator according to claim 4, 5 or 6, including means for comparing the number of the pulses with at least one stored value thereof to determine coin authenticity.

8. A coin discriminator according to any preceding claim including metal detection means for detecting metallic content of the coin.

9. A coin discriminator according to claim 8 wherein the metal detection means includes at least one electrode for forming a brushing electrical contact with the coin under test, and test circuit means for passing a current through the contact and the coin to determine if the coin is electrically conductive.

10. A coin discriminator according to any preceding claim including a body member containing a coin rundown path for coins under test, an opening to the coin rundown path, a slider for obturating the path opening and so arranged that when a coin is pressed against the opening the slider moves to permit entry of the coin and thereafter closes the opening.

11. A coin discriminator according to claim 10 including damper means for controlling the rate of closure of the slider means to control acceleration of the coin along the coin rundown path.

12. A coin discriminator according to any preceding claim wherein said dimensional parameter is coin diameter.

13. A coin discriminator according to any one of claims 1 to 11 wherein said dimensional parameter is coin thickness

14. A coin discriminator substantially as hereinbefore described with reference to the accompanying drawings.

15. A telephone set including a coin discriminator according to any preceding claim.