GB2140187A - Apparatus for testing and routing coins - Google Patents

Abstract

A coin enters the testing section of a microprocessor controlled mechanism for testing and routing coins of different denominations and is first classified according to its characteristic dimensions by sensor 2. The microprocessor then optimises the parameters of a second sensor 114 according to this classification, which forms part of a Maxwell Bridge circuit for determining the material content of the coin and hence its denomination. The coin then enters the separator section where it either passes through gate 86 into an escrow for temporary storage if it is a high value coin, or through gate 87-89 into one of three change tubes if it is a low value coin, or out through exit 109 into the return chute if it is not a valid coin. The microprocessor keeps a tally of the number of coins in each change tube in order to optimise their payout through dispense gates 106-108 or replenishment through gates 87- 89. Downtime due to the mechanism being out of change is minimised by combining the change tubes with an escrow 111 which can hold a number of coins of different denominations and empty them either through exit 109 into the return chute or through exit 110 into the cash box. <IMAGE>

Description

SPECIFICATION Apparatus for Testing and Routing Coins This invention relates to apparatus for testing and routing coins of different denominations and can be applied to different currencies. Such apparatus is widely used in various types of automatic vending equipment for providing goods and services.

Existing apparatus is known which uses electromagnetic means for testing coins and electromechanical means for routing them. The performance of such apparatus can be significantly improved by using the present invention.

Problems exist in testing and routing coins where coins of different denominations have similar dimensions or electrical/magnetic properties, for example difficulties are encountered when the United Kingdome 20p and 1 coins are used with the existing ip and 5p coins, because of their similar diameters.

According to the present invention there is provided apparatus for testing and routing coins comprising classification means for determining a characteristic dimension and/or a characteristic of the shape of a coin being tested, a bridge circuit having a signal source connected across one pair of diagonally opposite junctions, at least one signal detector connected across another pair of diagonally opposite junctions, and a component connected in one arm of the bridge circuit with an impedance which depends on the coin being tested, means for so setting an impedance in at least one arm of the bridge circuit in accordance with output signals from the classification means that the bridge circuit is balanced when the coin being tested has a predetermined thickness, electrical conductivity and magnetic permeability, and operational means connected to receive signals from the classification means and from the detector or detectrors and to take action dependent on the signals received, the operational means comprising routing means for routing the coins into different channels according to their denominations.

The said characteristic dimension can be either the diameter of a circular coin or the maximum dimension of one of the major surfaces of a noncircular coin or the thickness of a coin.

An advantage of apparatus according to the invention is that by setting the impedance of an arm of the bridge, the bridge circuit is adjusted by the classification means to be balanced only by a coin which has been classified as being of one, or possibly two, denominations. Thus a coin which is apparently of one denomination is tested as to thickness, electrical conductivity and magnetic permeability to determine if it is indeed of this denomination. If the classification means indicates two possible denominations the bridge circuit can resolve the ambiguity, for example by employing several parallel bridge arms and detectors simultaneously. The bridge circuit provides a convenient way of carrying out an exacting check on the validity of the coin being tested.

The means for determining the characteristic dimension of a coin may comprise either an inductor having an electro-magnetic field which is changed by an amount dependent on the characteristic dimension of a coin passing adjacent thereto, or an array of light beams positioned so as to test the characteristic dimension of the coin by sensing which light beams are interrupted.

The said component in one arm of the bridge with an impedance which depends upon the coin being tested may comprise an inductor so positioned that its electromagnetic field is interrupted by the passage of a coin adjacent thereto and its inductance accordingly depends on the electrical conductivity, magnetic permeability and thickness of the coin.

The operational means may include means for connecting selected networks of capacitors and resistors out of a plurality of such networks to set the impedance of one bridge arm, using for example optocouplers or field-effect transistors.

The frequency of the source may either be fixed or may be set using means for connecting selected capacitors out of a plurality of capacitors into the frequency determining portion of the source, using for example optocouplers or fieldeffect transistors.

The operational means may include a microprocessor or custom-designed integrated circuit or other form of logic circuit. The microprocessor may form at least part of one or more of the operational means, the classification means and the means for setting the frequency of the source and the impedance of at least one arm of the bridge circuit.

The routing means may for example comprise means for separating low value coins of different denominations into changetubes combined with means for separating high value coins into an escrow for temporary storage means for dispensing change and means for emptying the contents of the escrow into either a cash-box or a return-chute. The routing means may be used independently of the bridge circuit and with other apparatus for testing coins.

The use of the microprocessor has clear advantages in logically analysing outputs from the classification means, in controlling the timing and sequencing of the routing means, in minimising the likelihood of the apparatus running out of change and in providing data acquisition facilities.

An embodiment of the apparatus is now described by way of example with reference to the following drawings, in which: Fig. 1 is a schematic illustration of testing and routing apparatus according to the invention, Fig. 2(a) and (b) are respectively front and side views of the testing section of the apparatus shown in Fig. 1, Fig. 3 is a circuit diagram of means for determining the diameter of a coin and providing signals to preselect the frequency of an oscillator shown in Fig. 6 and the appropriate arm of a bridge shown in Fig. 5, Fig. 4 is a block diagram of part of apparatus according to the invention, Fig. 5 is a circuit diagram of the multi-arm bridge shown in Fig. 4, Fig. 6 is a circuit diagram of the two-frequency oscillator shown in Fig. 4, Fig. 7 is a flow diagram of the programme stored in the ROM shown in Fig. 4, Fig. 8(a) and (b) are flow diagrams of a testing subroutine which forms part of the programme shown in Fig. 7, Fig. 9(a) and (b) are respectively schematics showing alternative arrangements of the light beams in relation to the edges of the various coins, Fig. 10 is a circuit diagram of an alternative multi-arm bridge shown in Fig. 4, and Fig. 11 (a) and (b) are flow diagrams of an alternative testing subroutine which forms part of the programme shown in Fig. 7.

In describing an embodiment of the invention, it is helpful to consider one particular set of coins (namely the United Kingdom 1 p, 2p, 5p, 1 Op, 20p, 50p and 1 coins) and to give an example of the way the preferred embodiment may be used in a typical automatic vending application.

In order to purchase goods or services, any combination of the above coins may be fed, one at a time, into a slot with dimensions slightly greater than the diameter of the 50p and the thickness of the 1 coin.

Referring to Fig. 1, the coins then enter the Testing Section of the apparatus through a hopper at the top and fall onto a track 1 composed of an inelastic material in order to prevent the coins from bouncing unduly. The track is inclined at a sufficient angle to the horizontal to ensure that the coins are able to roll freely down it. As the coins roll down the track they first encounter diameter testing means 2.

The diameter testing means are shown in more detail in Fig. 2. A rolling coin 3 intercepts a row of infra-red light beams A-G originating from a row of light emitting diodes (LED's) 4 10 positioned on one side of the track so that each LED illuminates a respective one of a row of phototransistors 11-1 7 positioned opposite the LED's on the other side of the track. The LED's and phototransistors are selected to have a similar spectral response. The light beams are located at progressively increasing distances from the track as the coin progresses down the track and one by one they are interrupted by the passage of the coin up to a point where the diameter is insufficient for the coin to interrupt the next beam.

Fig. 9(a) shows the positions of the individual light beams A-G with respect to the track and to the loci of the furthermost edges of each denomination of coin from the track. It can be seen that: a 1 p coin will interrupt beam A but not beam B, a 20p coin will interrupt beam B but not beam C, a 1 coin will interrupt beam C but not beam D, a 5p coin will interrupt beam D but not beam E, a 2p coin will interrupt beam E but not beam F, a lop coin will interrupt beam F but not beam G and a 50p coin will interrupt beam G The light beams A-G are also shown in the circuit of Fig. 3 between the row of LED's 21 10 and the corresponding row of phototransistors 11-17. As each of these phototransistors is sequentially occluded by a passing coin pulses are fed into the corresponding data input terminals of a programmable input/output device (PIO) 1 8 such as the Motorola MC6820.

Fig. 4 shows the PIO 18 and further PIO 19 connected to the bus of a microprocessor 20 such as the Motorola MC6802. Also connected to the bus are a read-only-memory (ROM) 21 and a random-access-memory (RAM) 22. The ROM 21 contains not only the programme of Fig. 7 but also certain application-specific information such as the values of each denomination of coin which can be tested, the prices of goods or services being provided and the designation of individual change tubes. The RAM 22 not only stores transient input and output data but also stores other variable information such as the cumulative value of accepted coins and the numbers of coins in each change tube. The PIO 18 receives input pulses from the phototransistors 11-1 7 of the diameter determining means 23.These input pulses are analysed by the microprocessor 20 which generates appropriate output pulses depending on the diameter, and hence the probable denomination of the coin. The output pulses are sent to a Double-frequency Oscillator 24 and a Multi-arm Bridge 25 in order to preselect the operational parameters of the bridge circuit described below. The PIO 1 9 interfaces with Solenoids and Relays 26 which are also described later.

Fig. 3 also shows how the output signals from the microprocessor are sent via PIO 1 8 to the driver transistors 27-33 which drive the LED's 34-40, each of which is optically coupled to a respective one of the phototransistors 41-47 shown in Fig. 5. Each LED/Phototransistor pair is available in a single component known as an optocoupler. In addition, if the coin is of high conductance, such as a 1 p, 2p, or 1 coin, a further signal is sent via the output terminal 48 of PIO 18 in Fig. 3 to a driver transistor 49 in Fig. 6 which drives another LED 50, which in turn is optically-coupled to a phototransistor 51. The optocouplers are used to preselect the operational parameters of the bridge circuit in a manner described below.

Referring back to Fig. 1, as a coin rolls further down the track it next interrupts the electromagnetic field of an inductor 114. The inductor is shown in more detail in Fig. 2(a) and (b) where it can be seen that the inductor comprises an identical pair of ferrite pot-cores 52 each containing a coil 53, positioned on opposite sides of the track so that they face each other and are completely occluded from each other by the passage of any denomination of coin 54 between them. The coils are connected in series so that when a coin passes between them it changes their mutual inductance due to a change in the electromagnetic coupling between them.

According to the classical theory of skin effect:

where: A=Skin Depth ,u=Relative Magnetic Permeability f=Frequency in Hz p=Specific Resistivity in Qcmx10-6 It follows that for non-magnetic UK coins (y=1) the attenuation in electromagnetic coupling and hence the change in mutual inductance of the inductor 114 will be a function of the electrical conductivity, magnetic permeability and thickness of the coin.

Referring to Fig. 5 it can be seen that the inductor 114 forms one arm of a Maxwell Bridge in which the counter-balancing arm (across points X, Y) consists of a fixed capacitor 55' in parallel with a fixed resistor 55 and one of seven preselected networks 56-62 each consisting of a capacitor in parallel with a resistor with values corresponding to a particular denomination of coin (as shown). Signals from PIO 18 are used to preselect one of the seven networks by switching on one of the seven phototransistors 41-47. The bridge also comprises a signal source 63 (connected across points W, X). While a fixed frequency source may be found to be satisfactory for some applications, a double-frequency source will, in general given greater discrimination.

Referring to Fig. 6 it can be seen that the double-frequency signal source is a Hartley Oscillator employing an output transformer 65 in a feedback circuit of transistor 66. The primary winding of the transformer 65 forms a resonant circuit with the three capacitors 67-69. The Hartley Oscillator is conventional except in so far as part of the capacitance of its resonant circuit (the capacitor 68) can be shorted out by means of a phototransistor 51. A signal on driver transistor 49 will cause an LED 50 to emit light, thereby causing phototransistor 51 to conduct and short out the capacitor 68.

This will have the effect of increasing the total capacitance of the resonant circuit and therefore decreasing the frequency of oscillation of the signal source. In the case of coins of high electrical conductance (1p, 2p and 1) the skin effect formula gives an optimum frequency of the order of 1 KHz and in the case of coins of low electrical conductance (5p, 10p, 20p and 50p) an optimum frequency of the order of 1 OKHz, so the ratio of the capacity of the capacitor 68 to the capacity of the capacitors 67 and 69 can be chosen accordingly.

Referring back to Fig. 5 it can be seen that by preselecting the frequency of the source and also the value of the network across X, Y it can be arranged that the bridge will be brought into balance for a particular denomination of coin.

Whenever the bridge is brought into balance a null detector 64 connected across points Y, Z of the bridge will give an output signal which is fed into an input terminal 70 of the PIO 1 8 shown in Fig. 3, thereby providing an accurate check on the validity of the denomination of the coin as indicated by the diameter determining means.

It is helpful now to refer to a flow-diagram of the programme stored in the ROM 21 as shown in Fig. 7. As soon as the apparatus is powered-up the programme commences with an instruction START 71, the next instruction RESET CREDIT 72 sets the value of the credit stored in the RAM 22 to zero. An instruction 73 diverts the programme into a TESTING SUBROUTINE 74 shown in detail in Fig. 8(a). The subroutine starts with a loop which periodically tests the first photocell A with the question A DARK? 75 to see if a coin has arrived. If the answer is no (indicated by N) the programme goes around the loop again via a brief WAIT state 76. However, if the answer is yes (indicated by Y) the arrival of a coin is noted by the instruction SET ARRIVAL 77 which starts a timing subroutine (not shown) and then moves on to test the second photocell B with the question B DARK? 78.If the photocell B does not go dark during a specified time interval, the microprocessor classifies the coin as probably being a 1 p and gives the instruction SET 1 p ARM 79 to connect in the arm of the bridge associated with the 1 p coin and the instruction SET FREQ.=1 KHz 80 to set the frequency of the source to 1KHz. The programme then tests if the bridge is brought into balance within a prescribed interval with the question BALANCE? 81. If the answer is yes the subroutine gives a result VALID 1 p 82. If, however, the bridge does not balance, the answer is no and the subroutine gives a result RETURN 83 and the programme reverts to the start of the TESTING SUBROUTINE 74.

Although a complete subroutine for testing all seven denominations of coins is given in Fig. 8(a) and (b) further description is unnecessary since the branches of the programme describing the other coins are similar to that of the 1 p.

Returning to Fig. 7, when a valid coin has been confirmed the programme now gives the instruction CREDIT VALUE OF VALID COIN 84 which increments the value of the appropriate address in the RAM 22 and the instruction DISPLAY VALUE 85 which displays to the user the total credited value of the coins which have been accepted on a display (not shown).

Referring back to Fig. 1, instruction 85 coincides with the point where the coin enters the Separator Section of the apparatus and falls onto a second track. The floor of this track comprises four gates 86-89 which can be opened using solenoids activated by signals from the PIO 19 allowing the coin to fall into one of four selected channels.

Returning to Fig. 7, the programme now checks whether the user has pressed the return button by the question RETURN BUTTON? 90. If the answer is no the programme then checks if the coin is a high value coin by the question HIGH VALUE COIN? 91. if the answer is yes, then the instruction OPEN ESCROW GATE 92 will route the coin directly into the escrow by opening gate 86 in Fig. 1. If the answer is no then the coin must be a low value one and may be used to replenish the changetubes by opening one of the gates 87-89 in Fig. 1. In this case the programme will give the instruction SELECT CHANGE TUBE 93 according to the denomination of coin accepted and then go on to check whether the respective changetube is full by the question CHANGETUBE FULL? 94.It does this by checking a number stored in a designated address of the RAM 22 and seeing if it exceeds a predetermined level. If it does then the programme proceeds to the instruction OPEN ESCROW GATE 92. If it does not then the programme proceeds to the instruction REPLENISH CHANGETUBE 95 and the appropriate one of the gates 87-89 in Fig. 1 will be opened at the appropriate time and the coin will fall into the respective changetube.

The next question which the programme asks is has the user pressed a selection button PRICE SELECTION? 96. If the answer is negative then the programme returns to the TESTING SUBROUTINE 73 and awaits the arrival of further coins. If a selection button has been pressed then the programme next asks whether the cumulated credit equals or exceeds the price of the goods selected CREDIT2PRICE? 97. If it does not then the transaction is terminated and coins to the value credited are returned by the instructions RETURN ESCROW COINS 98 and DISPENSE CHANGETUBE CREDIT 99. If the credit equals or exceeds the price then the programme will give the instruction EMPTY ESCROW 100 and the contents of the escrow will be emptied into the cash-box chute 110 (Fig. 1).

If the cumulated credit exceeds the price then the difference will be dispensed in the form of change from the changetubes by the instruction DISPENSE CHANGE 101. In order to complete the transaction the next instruction VEND 102 will actuate an appropriate relay so that goods or services are automatically provided.

If during the programme the user decides to press the return button, the cumulative credited value of accepted coins will be returned by the instructions RETURN ESCROW COINS 103 and DISPENSE CHANGETUBE CREDIT 104. On completion of the programme a final RETURN 105 instruction returns the programme to its initial state START 71.

Referring back to Fig. 1 , the Change Dispenser Section of the apparatus will now be described.

The channels beneath gates 87-89 are of a circular cross-section (not shown), slightly larger than the diameter of the selected coins and have previously been referred to as changetubes. Coins entering these tubes through gates 87-89 form a vertical stack in each tube. The tubes are interchangeable for different denominations of coins.

On receipt of appropriate signals from the PlO 1 9 corresponding to instructions 99, 101 or 104 in the programme (Fig. 7) coins are dispensed one at a time from the base of the changetubes by means of solenoid-activated blades (shown schematically as 106-108 in Fig. 1) and fall into the return chute 109. The exact combination of coins dispersed will depend on the number of coins in each changetube stored in the RAM 22.

The programme will ensure that change is provided so as to minimise the chances of one of the changetubes becoming empty. If the lowest denomination of changetube is empty then an output signal from PIO 1 9 will switch on an "exact-change" light (not shown) but visible to the user of the apparatus.

The Escrow Section of the apparatus in Fig. 1 will now be described. Coins which pass through the gate 86 enter the escrow section and fall onto a horizontal platform 111 supported by two spring loaded solenoids (not shown) which forms the base of the escrow where the coins are temporarily stored. By activating one of these solenoids the platform can be tilted to the right so that the contents of the escrow are tipped into the cash-box chute 11 0. By activating the other solenoid the platform can be tilted to the left so that the contents of the escrow are tipped into the return-chute 1 09.

An important additional feature of the apparatus is its data retrieval capability. The MC 6802 microprocessor has a small amount of onboard RAM (not shown) which can retain data in a low power standby-mode facilitating memory retention in the event of a power failure. The onboard RAM is therefore used to store information which is useful to the machine operator such as the total value of coins in the cash-box, the number of products vended by type, and the number of coins of each denomination accepted.

The machine operator can gain access to this data at any time by pressing a data retrieval button on the back of the apparatus (not shown) in order to display in sequence the contents of selected addresses in the on-board RAM.

Having described a specific embodiment of the invention it will be clear that the invention can be put into practice in many other ways. Some examples of possible variants are now given.

For currencies where different denominations of coins have only small differences in their diameters or shapes so that allowing for wear and bounce it is difficult to classify them uniquely using the embodiment described above, the following variant described with reference to Figs. 9(b), 10, 11 (a) and 11 (b) may be used.

Fig. 9(b) shows a small but significant variation in the location of the light beams compared with Fig. 9(a). The light beams shown in Fig. 9(b) are used in conjunction with a form of logic known as "fuzzy" logic which deals with probabilities rather than certainties. For example, while it is probable that a coin which occludes light beam A but not light beam B is 1 p, it is also possible that it might be a worn 20p. Accordingly, the arm of the bridge shown previously across points X, Y in Fig. 5 can be split into two sets of parallel arms. This is shown in Fig. 10 where one set of parallel arms is across X1, Y1 and the other set is across X2, Y2.

The advantage of this is that by using a single bridge with a single signal source, tests can be made simultaneously for two denominations of coins using two null detectors (D1) 112 and (D2) 113. By arranging that the balance arms are situated alternately in one set and the other in an order corresponding to coins of increasing diameter the overall coin acceptance of the apparatus can be enhanced. A testing subroutine for this variant is shown in Figs. (a) and 11(b) which is self explanatory from the earlier testing subroutine.

Other variants will now be described: The optocouplers or field-effect transistors may form part of an integrated circuit or be replaced by some other form of switching device with high isolation.

The Maxwell Bridge may be replaced by an Owens Bridge or another inductance bridge.

The Hartley Oscillator may be replaced by a Colpitts Oscillator or another sinusoidal voltage generator, and instead of using one or two frequencies only, multiple frequencies may be used.

The pair of pot-cores 52 in the inductor may be replaced by a C-core whose electromagnetic field is interrupted by a coin passing through its gap or many other shapes of ferrite inductor.

The diameter classification means may be replaced by a shape classification means where the light beams may be positioned in a non-linear array in order to test coins belonging to currencies where some of the coins have either a non-circular shape or have holes in the middle, or by a thickness determining means or any combination of the above.

The Motorola MC 6802 microprocessor and its associated MC 6820 PIO devices may be replaced by other suitable eight-bit microprocessor and PIO devices.

The apparatus may be arranged to be suitable for use with another currency provided the coins are made of metal and capable of rolling.

Claims (14)

1. Apparatus for testing and routing coins comprising classification means for determining a characteristic dimension and/or characteristic of the shape of a coin being tested, a bridge circuit having a signal source connected across one pair of diagonally opposite junctions, at least one signal detector connected across another pair of diagonally opposite junctions, and a component connected in one arm of the bridge circuit with an impedance which depends on the coin being tested, means for so setting an impedance in at least one arm of the bridge circuit in accordance with output signals from the classification means that the bridge circuit is balanced when the coin being tested has a predetermined thickness, electrical conductivity and magnetic permeability, and operational means connected to receive signals from the classification means and from the detector or detectors and to take action dependent on the signals received, the operational means comprising routing means for routing the coins into different channels according to their denominations.

2. Apparatus according to claim 1 wherein the signal source has a variable frequency output and the means for setting an impedance in an arm of the bridge is also arranged to set the frequency of the source in accordance with output signals from the classification means.

3. Apparatus according to claim 1 or 2 wherein the classification means is constructed to determine the diameter of a circular coin and/or the maximum dimension of one of the major surfaces of a non-circular coin or the thickness of a coin.

4. Apparatus according to any preceding claim wherein the classification means comprises a path taken by coins under test, and a plurality of pairs of light sources and light sensors defining the positions of an array of light beams, between the source and the sensor of respective pairs, the sources and sensors being positioned to test the characteristic dimension and/or shape of a coin passing along the path by sensing which light beams are interrupted.

5. Apparatus according to claim 1,2 or 3 wherein the classification means comprises an inductor having an impedance which depends on the characteristic dimension and/or shape of a coin passing along the path taken by coins under test.

6. Apparatus according to any preceding claim wherein the said component connected in one arm of the bridge comprises an inductor so positioned that its impedance is changed by the passage of a coin adjacent thereto and accordingly depends on the electrical conductivity, magnetic permeability and thickness of the coin.

7. Apparatus according to any preceding claim wherein the operational means includes means for connecting a selected network of capacitors and resistors from a plurality of such networks to set the impedance of one arm of the bridge.

8. Apparatus according to claim 3, or any of claims 4 to 7, in so far as dependent on claim 3, wherein the frequency of the source is set by means for connecting selected capacitors from a plurality of capacitors into a frequency determining portion of the source.

9. Apparatus according to claim 7 or 8 wherein the means for connecting a selected network or selected capacitors comprises optocouplers or field-effect transistors.

10. Apparatus according to any preceding claim wherein at least part of one or more of the operational means, the classification means and the means for setting the impedance of at least one arm of the bridge circuit is formed by a microprocessor.

11. Apparatus according to any preceding claim wherein the routing means comprises means for separating low value coins of different denominations into changetubes combined with means for separating high value coins into an escrow for temporary storage, means for dispensing change and means for emptying the contents of the escrow into either a cash-box or a return chute.

1 2. Apparatus according to any preceding claim wherein the bridge circuit comprises several parallel bridge arms and detectors.

1 3. Apparatus for routing coins comprising means for separating low value coins of different denominations into changetubes combined with means for separating high value coins into an escrow for temporary storage, means for dispensing change and means for emptying the contents of the escrow into either a cash-box or a return chute.

14. Apparatus for testing and routing coins substantially as hereinbefore described with reference to the accompanying drawings.