DEBIT CARD SYSTEM
TECHNICAL FIELD
This invention relates to a debit card system wherein the holder of the card applies his card to a machine which reads the card and delivers the user a product or renders him a service, whilst debiting a unit of value from the card. BACKGROUND
The card holder will have purchased his card (or cards) in advance and thereafter is able to use it to obtain the goods or services concerned. Thus the card is more properly termed a debit card (rather than a credit card) because of the payment in advance and subsequent debiting from the card (as opposed to the obtaining of goods or services on credit and the payment at later date) . By way of examples only, the reading machine may control a vending machine dispensing food or drink or petrol, or dispensing travel tickets for train or bus travel, or a machine providing entry to a car park, a car wash, a toll bridge etc, or it may comprise an electricity meter or a meter supplying other public utilities. DISCLOSURE OF INVENTION
In accordance with this invention, there is provided a debit card system comprising a machine for receiving a holder's debit card, said machine comprising means for responding to a unit of value recorded on the card and for debiting that unit of value from the card, characterised in that said responding and debiting means comprises means for reading the card and validly recognising a recorded unit of value and immediately thereupon effecting at least partial erasure of that record from the card.
Conveniently but not necessarily the card may carry a plurality of units of value recorded in magnetic form. Conveniently, the machine may include means for marking the card to provide the holder with a visible representation of the debited unit: this may comprise a punch which indents the card without severing even any small part from the card. This provides a simple means of marking and avoids the need to remove from the machine parts severed from successive cards. BRIEF DESCRIPTION OF THE DRAWINGS
An embodiment of this invention will now be described, by way of example only, with reference to the accompanying drawing, in which: FIGURE 1 is a plan view of a debit card for use in the system; and
FIGURE 2 is a schematic diagram of a machine for receiving and responding to the debit card. DETAILED DESCRIPTION Referring to Figure 1, the debit card is generally of the same size as a standard credit card and is formed with a magnetic strip 1, provided in the example shown on its face side. Lengthwise of the magnetic strip, the card is printed or otherwise marked with indicia 2 indicating a plurality of units of value, 20 units in the example shown. Alongside each such index mark, the magnetic strip is encoded with a unit of value, and the same encoding is reproduced identically alongside each and every index mark. Each magnetic encoding comprises 8, for example, clock pulses regularly spaced lengthwise of the magnetic strip. Then up to 8 code pulses are provided, each l80º prior to a respective clock pulse: the precise number, positions and combination of code pulses provides a code rendering the card acceptable only by machines programmed to respond to that particular code.
Referring to Figure 2, the machine comprises a front wall 10 formed with a slot 11 to receive a card 9. Behind this front wall, a pair of channel members 12 (one only visible in the drawing) are disposed at opposite ends of the slot, face each other and extend towards the back of the machine. Thus, as the card is passed faceup into the slot 11 (in the direction of the arrows shown in Figure 1 as marked on the card), its opposite edges are received in the respective channel members to guide the card. A photodetector 13 responds, when the leading edge of the card masks the photodetector from a light source 14, to activate electrical control circuitry to start an electric motor 15, the output spindle of which drives a wheel l6 carrying (on a common shaft) a pinch wheel 17. A magnetic read/erasure head 18 co-operates with the pinch wheel 17 and the latter serves to drive the card forwards into the machine.
As the card is driven forwards, the head 18 reads the first magnetic encoding to pass. Electronic control circuitry checks for the regular clock pulses in the correct positions, and also reads the code pulses and compares the corresponding code with the code by which the machine is programmed. As soon as the head has read the final clock pulse to pass, in the first magnetic encoding, it is able to compare the code with the programmed code and approve it to recognise the unit of value. If the first magnetic encoding is approved, then immediately the final clock pulse has been read, the electronic control circuitry applies an erasure pulse to the read head (comprising a single read-erase winding) which has the effect of erasing, from the first magnetic encoding on the card, at least the final clock pulse and preferably two or more clock pulses and one or more of the digital code pulses. In addition, the control circuit provides an output signal to dispense the product or deliver the service for which the machine is designed. Also, a solenoid 19 is energised to drive a punch 20 downwards against the bias of a spring 21: punch 20 extends through a hole in one side of channel member 12 and, upon actuation in this manner, its bottom end indents the plastic card at a position I (see Figure 1) alongside the respective index marking.
Immediately after this indenting, the electric motor is energised in the reverse sense to eject the card from the machine. Should the first magnetic encoding not be validly recognised (through the absence of one or more clock pulses or because the incorporated code does not match with that prescribed for the machine), then the motor will continue (without stopping) to drive the card so that the next magnetic encoding is read, and so on. If the card is driven in this manner until all of its magnetic encodings have been read (and none recognised), the card will abut a contact 22 at the back of the machine, or preferably passage of the trailing edge of the card will be detected by photodetector 13, for the electrical control to reverse the motor and eject the card from the machine. If the card has been properly used once and the first unit of value debited (by erasure of its final clock pulse), then the next time the card is used it will be driven past that first unit and onto the second unit, which should then be recognised and responded to, and then similarly cancelled, and the card indented and ejected.
The indentations made by the punch provide a convenient visible means for the holder to see at a glance how many of his units of value have been debited. The electrical control circuitry is further arranged that if the holder should grip his card and try to restrain it against being driven in by the motor, the motor will reverse after a few seconds time delay and eject the card. For erasure, a separate erase head may be provided to effect erasure, whether from the front side or from the back side of the card, but in any event the erase signal is applied immediately upon approval of the encoding which has just been read. As mentioned previously, one example is for the machine to comprise an electricity meter, arranged to respond to a unit of value recorded on a holder's card and provide a predetermined amount of electricity to the card holder's premises for each such unit of value (instead of the conventional arrangement requiring the insertion of a coin). Thus, the cards would be purchased from the electricity authority and then used when required to obtain the supply of electricity. The card might preferably carry a single unit of value which is then debxted upon use of the card in the meter and the meter may be arranged so as simply to require the card to be inserted to the correct position relative to the read and erase head or heads: the drive motor of Figure 2 would then be dispensed with. As a safety or convenience measure, the meter is preferably provided with a button or other switching device which is actuable to cause the meter to provide a further predetermined amount of electricity to the premises: in effect, the user will have thus obtained that amount of electricity on credit and the arrangement of the meter is such that balance is restored by use of one further card on the meter, and a second card will be required to obtain a further supply of electricity.
The effecting of at least partial erasure immediately upon reading and recognising a recorded unit of value leads to simplicity of the system, as the card can undergo no significant movement between the completion of the reading and the erasure and it is not necessary to incorporate a complex control to determine the location of the card where erasure is required (which would be the case if the erasure were effected at a later time). Moreover, the system is secure against the possibility of fraud because it is impossible to withdraw the card between the completion of reading and the immediately following erasure.