GB2348731A - Fault detection in currency handling mechanism for a vending machine - Google Patents

Abstract

A currency handling mechanism for a vending machine comprises a first controller 8 for issuing dispense instructions, a second controller 14 for controlling the operation of dispensing means for change or articles in the vending machine, a communications link 15 connecting the controllers 8, 14, and means for monitoring signals on the link 15 so that in the event of detection of a fault the second controller inhibits the operation of the dispensing means. The signals may be in the form of pulses, and errors may be in the form of missing or additional pulses. The dispensing means may include a DC motor which is braked on detection of a fault. In an alternative apparatus operation of dispensing means is halted on the detection of electronic noise.

Description

Currency Handling Mechanism for a Vending Machine The present invention relates to a currency handling mechanism for a vending machine.

Vending machines which automatically provide a product or service in exchange for payment are well known. Payment may, for example, be in the form of coins, banknotes or tokens, or made using a card such as a credit or debit card, which may be a smart card. In the following, all means of payment are covered by the term currency. Usually, the vending machines are controlled by a main controller, including at least a microprocessor and memories storing the control programs. The main controller receives signals from certain components of the vending machine and outputs signals to other components of the vending machine. For example, in some known vending machines, a coin tester measures characteristics such as diameter and material of coins inserted into the vending machine using electro-magnetic coin sensors. The signals output from the sensors are sent to the main controller where they are analysed to determine the validity and denomination of the inserted coin. If the coin is valid, the controller outputs signals to control the operation of gates within the coin mechanism to open a path directing the coin to the appropriate coin storage means within the coin mechanism.

Malfunctions can occur within the vending machine, the malfunctions including hardware or software failure within the currency handling mechanism. Also, the vending machine may be adversely affected by accidental external electro-magnetic interference, or by deliberate interference by a fraudster. It has been found that as a result the vending machine can give false credit, supply the wrong product or service, or pay out incorrect amounts of change. It has also been found that noise on the communications links within the coin mechanism can cause change to be dispensed incorrectly.

The present invention provides a currency handling mechanism for a vending machine comprising a first controller, a second controller for controlling the operation of dispensing means in the vending machine, the first and the second controller being connected together by a communications link, wherein signals on the communications link are monitored for indications of a fault, and the second controller is arranged such that it either prevents or suspends the operation of the dispensing means as appropriate when a fault is detected.

Other aspects of the invention are set out in the appended claims.

Embodiments of the invention will be described with reference to the accompanying drawings, of which: Fig. 1 is a schematic drawing of a vending machine; Fig. 2 is a block diagram of the coin mechanism of the vending machine of Fig. 1; Fig. 3 is a circuit diagram of a DC motor drive; Fig. 4 is a block diagram of a noise detecting circuit.

The arrangement of a coin mechanism within a vending machine is shown schematically in Fig. 1. The vending machine indicated generally by the reference numeral 1 includes a coin inlet 2 for receiving coins inserted as payment by a user. The coin inlet 2 is connected by a passageway 3 to the coin mechanism 4 which is for testing, storing and dispensing coins. The coin mechanism 4 is also connected to a coin outlet 6 for returning coins, including coins dispensed as change, to the user.

As shown in Fig. 2, the coin mechanism includes a central processing unit (CPU) 8. The CPU 8 includes a processor, a RAM, and associated circuitry. The CPU is connected to coin sensors 10 for sensing coins inserted into the vending machine, an accept gate 11 for directing a coin along either a coin reject path if it is deemed invalid or an accept path if it is deemed valid, and coin separators 12 for separating accepted coins according to their denomination to direct them to an appropriate one of four coin storage tubes (not shown) in the coin mechanism or to a cashbox (not shown). The CPU 8 is also connected to an interface board 14. In this embodiment, the CPU 8 and the interface board 14 are connected by a synchronous serial interface link (SSI) 15, but any suitable communications link can be used. The interface board 14 also includes a processor (not shown). The interface board 14 is connected to a keypad 16 for a customer or serviceman to input instructions to the vending machine and to a coin dispenser 18 for dispensing coins from the coin storage tubes as change. The interface board 14 and CPU 8 are also connected to a display 20 for displaying information such as the amount of credit that has been accrued. The interface board 14 is also connected to the vending machine I to send and receive signals including signals authorising the machine to dispense a particular item when sufficient payment has been received. The various communications links, other than the SSI 15, connecting the components described above are indicated by the reference number 22 in Fig. 2.

When a customer inserts a coin into the coin inlet, it passes the coin sensors, which output signals representing features of the coin, such as the material, diameter and thickness. These signals are received by the CPU 8 which carries out tests to determine the validity and denomination of the coin using stored reference values representing different denominations of coins.

If the tests indicate that the coin is not a valid coin of an acceptable denomination, the accept gate 11 stays closed and diverts the coin to a coin reject path from where it travels to the coin outlet 6. If the coin is deemed valid, the CPU 8 operates to open the accept gate 11 and controls the separator mechanism 12 to direct the coin along a path to an appropriate coin storage tube.

Various types of coin validators are known. Examples of such validators are described in, amongst others, GB 1 397 083, GB 1 443 934, GB 2 254 948, GB 2 094 008 and GB 2 288 266, the contents of which documents are incorporated herein by reference. Similarly, coin separators are known.

An example of a coin separator is shown in GB 2 326 963 A. Coin storage means in the form of coin tubes is described in GB 2 246 897 A, the contents of which are incorporated herein by reference.

When change is required for a given vend operation, the CPU 8 outputs instructions to the interface board 14, which controls the coin dispenser 18. The coin dispenser 18, as described in EP 0 678 207 A, the contents of which are incorporated herein by reference, includes four dispenser arms, one for each coin storage tube, and two motors for controlling the dispenser arms. The motors and the dispenser arms are arranged so that driving the first motor forwards operates the dispenser arm for the first tube to dispense from that tube, and driving the first motor in reverse causes a coin to be dispensed from the second coin storage tube. Similarly, driving the second motor forwards dispenses coins from the third coin storage tube and driving the second motor in reverse dispenses coins from the fourth coin storage tube.

Fig. 3 is a circuit diagram of a DC motor drive. Such a motor drive is used for each of the motors for the dispensers respectively. The drive has four switches SWA, SWB, SWC and SWD. A first pair of switches SWA, SWC are connected in series across a power supply, and the other pair of switches SWB and SWC are also connected in series across the power supply. A permanent magnet DC motor 30 is connected to the junction of the first pair of switches SWA, SWC and the junction of the other pair of switches SWB, SWD to provide a circuit having an'H'configuration. The switches are used to control the motor. When all the switches are open, the motor is free. When SWA and SWD are closed (and SWB and SWC are open) the motor is driven forward. When SWB and SWC are closed, the motor is driven in reverse.

When SWC and SWD are closed and SWA and SWB are open, or when SWA and SWB are closed and SWC and SWD are open, the motor is braked.

As described above, operation of the coin dispensers 18 and the vending of products is effected by the interface board 14 under the control of instructions sent from the CPU 8 along the communications link 15 between the CPU 8 and the interface board 14. In normal operation of the vending machine, data is continually sent from the CPU 8 to the interface board 14 along the communications link 15. According to the present embodiment of the invention, signals on this link are monitored to identify faults in the hardware or software of the coin mechanism, or noise interference. When the signals indicate that there is a fault or noise, the interface board 14 holds its outputs in a safe state, or places them in a safe state. In this embodiment, a safe state is one in which the coin dispenser 18 is not dispensing and there is no output instruction to vend a product.

Data is sent between the CPU 8 and the interface board 14 as pulses in predetermined patterns. For example, in standby mode, when no vend operation is taking place, a stream of regular pulses is sent by the CPU 8, each pulse being of a predetermined width and each pair of pulses being separated by a first predetermined interval. An instruction, and other data, is represented by different pulse patterns, having different pulse intervals and different pulse widths from the pulses in the standby mode. For example, an instruction to turn on a motor for dispensing change is in the form of a group of 16 pulses.

As described above, in normal operation, the communications link is always active and data pulses are sent continually. Furthermore, there is a predetermined known expected upper limit on the interval between pulses on the communications link during normal operation. In this embodiment, the longest expected time between data pulses is 2 ms. The controller on the interface board 14 continuously monitors data pulses on the communications link, and if it is determined that a period more than twice the longest expected time between data pulses has elapsed without receipt of a data pulse, then the controller decides that a fault has occurred. The controller then outputs a signal indicating that a fault has occurred. As long as this signal is output, then all the components controlled by the interface are disabled. More specifically, the motors 30 for the dispensers 18 are held in an off state, by holding switches SWA, SWB, SWC and SWD open, so that no coins are dispensed, and the output to the product dispenser is also held in an off state.

If one of the dispenser motors 30 is already in operation when a fault is detected (because a dispense instruction had been received but not completed before the fault was detected) then the motor 30 is braked using the switches SWA, SWB, SWC and SWD as described above to halt the dispensing operation. That is because the instruction to dispense may have been caused or influenced by the detected fault. Alternatively, the motor 30 may be simply turned off. It is preferable to brake the motor, because momentum may cause the dispensers to continue to move if the motor is simply turned off.

A mechanical fault that can occur within a vending machine is when a cable connecting the CPU 8 and the interface board 14 is dislodged. In such a situation, either there is no communication between the CPU 8 and the interface board 14, or there is a risk that any data being transmitted is incorrect. Monitoring the gaps between data pulses can give an indication of such a situation. It is important to turn off the coin dispenser 18 and the vend control in such an event because, for example, when the cable is detached from the CPU 8 there is a risk that spurious external noise signals are transmitted along the link to the interface which is then interpreted as an instruction to dispense a product or some change. According to the present embodiment, however, the coin mechanism identifies that there is a problem and switches off the vending operations.

Subsequently, the cable may go back into position if, for example, the vending machine 1 is jostled. In that case the controller on the interface board 14 monitors the received data for a predetermined amount of time to check that it is in an acceptable form and then the outputs of the interface are returned to normal operation. If the fault does not correct itself, the interface board 14 holds its outputs in the safe state until the machine is visited and repaired by a serviceman.

The controller on the interface board 14 also monitors the pulse patterns in other ways to identify a fault. In this embodiment, a dispense operation is transmitted in the form of a pattern of 16 pulses, of predetermined widths and at predetermined intervals. A hardware or software fault or external interference may cause one or more of the pulses not to be transmitted correctly, or an additional pulse or pulses to appear. The interface controller monitors the signals for missing or additional pulses in expected pulse patterns. If missing or additional pulses are detected, so that the pulses do not correspond to any known data, then the pulses are ignored. For example, in the case given above where an instruction to turn on the first motor in a forward direction is given by 16 pulses of a predetermined width and at predetermined intervals, if only 15 pulses are received, then the instruction is ignored and the motor is not turned on. If erroneous patterns continue to be received over a predetermined period, then the interface decides that there is a serious fault, and holds the outputs in a safe state until a serviceman visits the machine.

The processor on the interface board 14 also checks the actual data received for errors. More specifically, the processor identifies errors in the received data using error correction methods including checksums, and by identifying the presence of address data that do not correspond to valid addresses. Isolated errors may simply be ignored, but if the error rate is above a predetermined level, the interface controller decides that there is a serious fault and holds the outputs in a safe state until a serviceman visits the machine. Alternatively, the interface board 14 may wait for a predetermined period and then start receiving and checking data again, the process being repeated until the error rate falls below the predetermined threshold, when normal operation can recommence.

In a second embodiment, the coin mechanism 4 is as described in the first embodiment and includes a circuit for detecting noise in the environment.

The circuit is for detecting noise that could interfere with the operation of the coin mechanism giving rise, for example, to false dispense operations. Such noise includes deliberate interference by a fraudster.

A block diagram of the noise detecting circuit is shown in Fig. 4. The circuit has an aerial 102 for receiving high frequency signals in the environment. The aerial is connected to the input of a filter 104, which is a high pass filter for passing the high frequency noise signals. The output of the filter 104 is connected to a level detector in the form of a comparator 106.

More specifically, the output of the filter is connected to one input of the comparator 106 and compared with a fixed level connected to the other input of the comparator 106. The output of the comparator 106 is connected to a monostable device 108. The monostable device 108 is adjustable and in this embodiment is set to a period of 0.5 seconds. The output of the monostable device 108 is connected to the interface board 14.

In operation, the aerial 102 continuously monitors the environment and picks up external signals that may influence the operation of the coin mechanism 4. Signals from the aerial 102 are filtered by the high pass filter 104 to identify the more troublesome high frequency signals. Furthermore, the high frequency signals are input to the comparator 106 to identify whether or not the amplitude of the signals exceeds a given predetermined value V.

If there are no high frequency signals greater than the predetermined value V, then the signal from the monostable 108 is low and the interface board 14 operates normally.

If the comparator 106 identifies a high frequency signal having an amplitude higher than the predetermined value, then it outputs the noise above that threshold. The output of the comparator 106 then triggers the monostable device 108, which outputs a pulse. When the output from the monostable device 108 is high, the interface 14 recognises the signal indicating that noise is present. The interface 14 then holds its outputs in a safe state, or puts them in a safe state, as described above.

When the noise above the threshold ends, the pulse from the monostable device 108 continues for the set period, in this case 0.5 seconds from the end of the noise, then the output from the monostable 108 goes low, and the interface board 14 returns to normal operation.

The noise detecting circuit of the second embodiment may be used either in conjunction with the detection of errors in the signals on the communications link as described in the first embodiment or without that aspect of the first embodiment.

Various modifications to the embodiments described above are possible. For example, the coin mechanism may be arranged to monitor signals on links other than the communications link between the CPU 8 and the interface board 14, such as the link between the coin sensors 10 and the CPU 8. The interface board 14 may perform different operations in response, such as outputting an error message on the display. Instead of a permanent magnet DC motor for the dispenser drives, other motors can be used such as an AC motor or a solenoid.

Claims (18)

Claims

1. A currency handling mechanism for a vending machine comprising a first controller for issuing dispense instructions, a second controller for controlling the operation of dispensing means in the vending machine, the first and the second controller being connected together by a communications link, wherein signals on the communications link are monitored for indications of a fault, and the second controller is such that it inhibits the operation of the dispensing means when a fault is detected.

2. A currency handling mechanism as claimed in claim 1 comprising means for dispensing currency, wherein the second controller inhibits the operation of the currency dispensing means when a fault is detected.

3. A currency handling mechanism as claimed in claim 2 wherein the currency dispensing means is braked if it is operating when a fault is detected.

4. A currency handling mechanism as claimed in claim 2 or claim 3 wherein the currency dispensing means comprises at least one motor, and the motor is turned or held off or braked when a fault is detected.

5. A currency handling mechanism as claimed in any one of claims 1 to 4 wherein the timing of intervals between pulses on the communications link is monitored for indications of a fault.

6. A currency handling mechanism as claimed in any one of claims 1 to 5 wherein data received by the second controller are monitored for errors indicating a fault.

7. A currency handling mechanism as claimed in any one of claims 1 to 6 for handling coins and comprising a coin sensor.

8. A vending machine comprising a currency handling mechanism as claimed in any one of claims 1 to 7.

9. A vending machine comprising a first controller, a communications link connected to said first controller, and means for monitoring a signal on said communications link for signals indicating a fault, wherein a vend operation is inhibited when a fault is so detected.

10. A vending machine as claimed in claim 9 wherein the vending of a product or service selected by a user is prevented or suspended when a fault is detected.

11. A vending machine as claimed in claim 9 or claim 10 comprising a second controller for controlling means for dispensing items to a user, the first and second controller being connected together by a communications link, wherein the second controller operates to disable the dispensing means when a fault is detected.

12. A vending machine as claimed in any one of claims 9 to 11 wherein the first controller is a main controller for controlling the vending machine and includes means for generating signals dependent on the currency inserted into the vending machine.

13. A vending machine as claimed in any one of claims 9 to 12 wherein the means for dispensing items to a user comprises means for dispensing selected products or services to a user, and the product or service dispensing means is disabled when a fault is detected.

14. A vending machine as claimed in any one of claims 9 to 13 wherein the means for dispensing items to a user includes at least one dispenser for dispensing change, and the change dispenser is disabled when a fault is detected.

15. A currency handling mechanism for a vending machine comprising a controller for controlling the operation of dispensing means in the vending machine and means for monitoring the environment for noise, wherein the controller is arranged such that it inhibits the operation of the dispensing means when noise is detected.

16. A method of operating a currency handling mechanism including first and second controllers, the second controller being for operating dispensing means, the method comprising monitoring a communications link between the first and second controllers for signals indicating a fault and inhibiting the operation of the dispensing means when a fault is detected.

17. A coin mechanism substantially as hereinbefore described and as shown in the accompanying drawings.

18. A method of operating a coin mechanism substantially as hereinbefore described with reference to the accompanying drawings.