GB2097164A

GB2097164A - A payment system with magnetic cards

Info

Publication number: GB2097164A
Application number: GB8209217A
Authority: GB
Original assignee: Wittenborg ApS
Current assignee: Wittenborg ApS
Priority date: 1981-03-31
Filing date: 1982-03-29
Publication date: 1982-10-27
Also published as: GB2097164B; DE3212049A1; DK146581A; DE3212049C2

Abstract

A payment system with a magnetic card reader for vending machines for a personal magnetic card of the dual- layer type with at least two magnetic tracks as means of payment comprising a lock mechanism (45) retaining the magnetic card (21) in the card reader (40) in such a manner that the card is only released when the card reader is in a starting position and an electronic control circuit with data processing means, preferably a programmed microcomputer, controlling the reading in and out of the data of the card by means of a number of sensors (A, B, C, D, E) and only allowing purchases of articles provided the data of the card have predetermined mutual relations. The data of the card must be synchronously arranged on two magnetic tracks, of which one track includes an amount and security code, whereas the second track includes a permanent identification code. The security code has a predetermined relationship to the amount and security code. Each code comprises preferably 10 figures repeated three times. These 10 figures are on one track composed of the value amount of the card, the security code, and a division sign and on the second track of the identification number of the system, the identification number of the card, and a division sign. The division sign is a special combination of 10 bits. In this manner it is very difficult to falsify the magnetic card, and with great certainty the system accepts a genuine card as means of payment. <IMAGE>

Description

SPECIFICATION A payment system with magnetic cards The invention relates to a payment system comprising a magnetic card reader for vending machines of the type whereby a customer by means of a personal magnetic card of the dual-layer type as means of payment may buy an article from a vending machine, said magnetic card reader comprising a magnetic head displaceable relative to an inserted magnetic card, a speed-measuring device transmitting a signal proportional to the speed of the magnetic head relative to the card and a lock mechanism.

It is known, e.g. from GB-PS No. 1,166, 085, to combine a vending machine with a magnetic card reader and a control unit allowing dispensation of an article from a vending machine, calculating the price of the article, registrating the value of the card of the customer in a built-in memory, and furthermore erasing a marking on the card of the customer, receiving the price of the dispensed article, subtracting the value thereof from the value on the card of the customer, and encoding a new balance on said card. The magnetic card of such a system may comprise two tracks, of which one track is used for an amount code, whereas the second track is used for a security code.In order to avoid improper use of the card, the customer must key a control number which is compared with the security code of the card within the vending machine, and when these codes do not conform, the card is rejected. However, this known security system only provides for the possibility of an unauthorized person trying to use the credit card.

In connection with payment systems of this type it is important to ensure that unauthorized persons cannot themselves encode magnetic cards of an appropriate type, and that a card owner cannot himself feed value to his card, e.g. by transferring information by means of various copying techniques. Moreover it is important to ensure that a card owner cannot remove his card from the vending machine after a purchase, but before the balance of the card has been corrected in accordance with the price of the purchased article, In addition, it should as far as possible be ensured that the information contained on the card is not lost, e.g. by a misreading or a typing error as a consequence of worn or messed up card(s), the encoding of which has been partially damaged by the cards having been situated adjacent a magnetic field.

Below the payment system according to the invention has substantially been mentioned in connection with a vending machine for the sake of convenience. The payment system may, however, also be used in connection with payment vending machines, preferably for coins or banknotes, whereby the customer can have the value of his magnetic card written up by paying an amount.

The object of the invention is to provide a system which is secured against the above ways of improper use, and which can distinguish between genuine and falsified cards, and which to the greatest possible extent also can read and accept a worn, but "genuine" magnetic card.

The payment system according to the invention is characterised in, that in order to lock the card, the lock mechanism may be activated by a carrier for the magnetic head, and that the lock mechanism only is open when the carrier with the magnetic head is in a predetermined starting position, and that the magnetic card reader is connected to an electronic unit comprising an electronic control circuit with data processing means, preferably a programmed microcomputer, said control circuit being adapted in such a manner that when one or more sensors have detected the insertion of a card it implies that the magnetic head is displaced relative to the card from its starting position across a first and a second mgnetic track in the card and erases possible, not permanent information codes on the second track, and when a sensor detects that the card is not locked due to an error in the card or the machine, said control circuit implies that the magnetic head is returned to its starting position, and when a sensor detects that the magnetic head and the carrier have passed the entire information track and reached their second outer position, said control circuit implies that the magnetic head is returned towards its starting position at the same time as the information codes in the form of blocks including a plurality of figures and a division sign repeated several times in each track are read from both tracks and stored in a memory in the electronic control circuit, the data processing means of said control circuit examining the authencity of the card by determining whether the read information codes are substantially synchronously located on both tracks and possess a predetermined mutual relation, and if this is not the case said means imply that the magnetic head continues to its starting position and stops, whereby the lock mechanism of the carrier of the magnetic head is actuated to open in such a manner that the card may be removed, and that the control circuit further is adapted in such a manner that when the authencity of the information code is acceptable it carries the magnetic head again cross the card towards its second outer position at the same time as the information code on the first track is erased, and when the sensor detects that the magnetic head has reached its second outer position, said control circuit stops the magnetic head and waits a customer's buy of articles, the value of which is fcd to the data processing means of the electronic circuit, said means subsequently calculating a new balance which is converted into a new information code, and that the control circuit finally is adapted to imply that the magnetic head again is returned to its starting position at the same time as the magnetic head encodes the new information code into the first track in such a manner that said new code is synchronously located relative to the information code in the second track.

As a result, the arrangement of the card can be detected with high certainty by the system in such a manner that the reading of the card is only initiated if the card has been correctly inserted and consequently locked by the lock mechanism adapted for this purpose. Furthermore, the authencity of the card is thoroughiy examined, and a possible, not permanent piece of information on the permanent track of the card is erased before the actual reading of the two tracks is initiated. In this manner it is ensured that the card in fact is a dual-layer magnetic card.

Furthermore, the data processing means examine whether the information codes are synchronously located and have a predetermined mutual relation.

Before dispensing the desired article, the total balance is erased from the card in such a manner that the customer cannot gain any advantage by removing the card immediately upon the dispensation of the article. A new balance is not encoded into the card together with an associated security code until the dispensing of the article has been terminated, and the encoding is performed in accordance with rules, which are so special that it is very difficult to falsify such an amount and security code. These rules are mentioned later.

In the payment system according to the invention, the data processing means of the control circuit examining the authencity of the card may be adapted to recognize the division sign, preferably C7, in the information codes in the form of a predetermined bit-pattern, preferably 00111 11100, and when this bit-pattern has been recognized, to initiate a new registration in the memory means of the subsequently read bits. This bit-combination of the division sign differs from all other existing bit-combinations and may therefore be used to indicate the start of a new set of data.

A plastic card with inserted magnetizable stripes may be used as a magnetic card, as it is known in connection with credit cards. The card comprises a first and a second magnetic track. The magnetic cards must be of the type comprising two magnetizable layers, i.e. a first layer of a relatively low coercivity and a second layer of a relatively high coercivity, of which only the second layer can be coded in particular encoding apparatuses having particular, intense magnetic fields. A permanent identification code may be applied to the highcoercive layer, said identification code partly identifying the system for which the card is intended, whereas the last part of the code forms a personal ID-code. A variable code containing an amount code and a security code may be applied to the lowcoercive layer at each transaction, i.e. at each purchase or payment.Usually the security code is a mathematical function of the amount code and the personal code.

When writing the amount and security code, a reading is first performed on the permanent tracks until a particular bit-configuration appears and is recognized. immediately thereafter, the writing is initiated, and the amount and security code is synchronously arranged relative to the ID-code.

When reading, the magnetic head passes initially the magnetic tape on the card once, and during this passing the information, if any, is erased from the upper layer of the standard coercive force on the track of the ID-code. In this manner it is ensured that the card in fact is a dual-layer card.

Subsequently, both tracks are simultaneously read. When correct comprehensible information is read on both tracks, when said synchronous arrangement of the tracks has been proved, and when the security code forms the predetermined function of the amount and ID-code, the card is accepted, i.e. it is considered to be genuine.

Since dual-layer cards with a permanent ID-code are only accepted, it is impossible to falsify by copying the entire card. The encoding of a permanent code requires a very special machinery.

When copying onto another dual-layer card is made, the security code is incorrect since the second card has a different personal ID-code.

Furthermore, any type of manipulation with the encoding is very difficult due to the requirement concerning the synchronous arrangement of the tracks.

Both the permanent and the variable code are encoded in a particular format implying that a set of information may be represented several times in succession on a card, preferably four times. When reading a card, data are fed in series to the reading unit, i.e. one bit at a time, and each bit may be 0 to 1.

Each figure usually comprises five such bits, cf. the international standard of credit cards ISO 3554. Thus the reading unit must count the bits in groups of five.

It appears that when only one bit is lost during the reading, the reading unit is no longer synchronized with the data, whereby the bits are grouped and consequently misread. In connection with the standardized ISO format, the reading is initiated at the first bit = 1. When bit-errors occur, the synchronizing and all subsequent information are lost.

In connection with the new format according to the invention, each set of information is initiated with a predetermined starting code called a "sentinel". This sentinel comprises 10 bits and is characterised in that it can be distinguished from all other existing bit-combinations. Each time the reading unit receives 1 bit, a test is performed whether said bit together with the previous 9 bits f m a sentinel, and if so the reading of information is initiated. When one or more bit-errors appear on a set of information, only this set of information is lost since the unit automatically refinds into the synchronizing at the next sentinel. It appears, that this format allows deciphering of data from the card provided only one of the four sets of information is correctly read.

The invention will be described below with reference to the accompanying drawing, in which Figure 1 illustrates a block diagram of a payment system according to the invention connected to a vending machine, Figure 2 illustrates a block diagram of a payment system according to the invention connected to a coin mechanism and/or a banknote detector, Figure 3 is a side view of an embodiment of a magnetic card reader according to the invention, Figure 4 is a sectional view through a sled and a magnetic card in the card reader of Figure 3, Figure 5 illustrates an identification code according to the invention, Figure 6 illustrates the arrangement of an amount and security code relative to an identification code according to the invention, Figures 7to 16 are diagrammatical views of the various positions of the card reader, Figure 17 is an inclined top view of a second, preferred embodiment of the card reader according to the invention, but without a motor drive unit and an interface circuit, whereby part of the interface circuit has been removed so that the lock mechanism appears, Figure 18 is a bottom view of the embodiment of Figure 17, whereby the motor and print card with interfase circuit are included, the end position of the sled being indicated by dotted lines, Figure 19 is a side view of the embodiment of Figure 17, whereby an end plate has been partially removed so that the photo-coupler and the motor drive unit appear, and Figure 20 illustrates a block diagram of the interfase circuit.

Figure 1 illustrates a block diagram of an embodiment of a payment system according to the invention connected to a vending machine, whereby a customer by presenting his card, i.e. a magnetic card, may receive for instance cold or hot beverages from the vending machine. An electronic unit 10 is connected to a front display 20 for instance by means of a 1 6-wire flat cable 9, said front display being situated in such a manner that it is convenient for the customer to watch the payment transaction.

Furthermore, the electronic unit 10 is connected to a "card return"-button 30 through a three-wire cable 8, which the customer may serve when the purchase transaction has been terminated. A 34-wire flat cable 7 connects the electronic unit 10 with a card reader 40, in which a magnetic card may be inserted, read and amended. The electronic unit is furthermore connected to a vending machine 60, e.g. through an 18-wire cable 6, and to a voltage supply through an 8-wire cable 5, a transfromer 70, and a main switch 80.

Figure 2 illustrates a completely corresponding diagram of an embodiment of a writing-up terminal, whereby the customer when paying an amount in coins and/or banknotes can have his balance written up on his magnetic card. The system of Figure 2 corresponds exactly to the system of Figure 1 and is therefore not described again. It should, however, only be mentioned that through an 18-wire cable, the electronic unit 10 is connected to a coin mechanism 91 instead of to a vending machine, said coin mechanism recognizing predetermined current coins, and/or to a bank note detector 90.

The electronic unit 10 comprises a current supply print, a keyboard 12 for keying data into the system, a display 13 showing the art and/or price of an article, an interfase-print capable of adapting the system to the various types of vending machines, and a control circuit including a microcomputer with a program and an interfase circuit for the card reader 40. Figure 3 illustrates an embodiment of the magnetic card reader 40. It is built into a chassis 41 with a slot 42, through which the magnetic card 21 is insertable sideways and preferably upright. In this chassis, a guide 62 is mounted which comprises a sled 43 displaceable by means of a spindle 63. The spindle 63 may rotate in both directions and is driven by a coupling 79 of a motor 54. The motor 54 may be activated by a control circuit 15 in the electronic unit 10.A magnetic head 44 is pivotably suspended, possibly on gimbals in a manner known per se, on the sled 43.

A lock mechanism 45 comprises a spring F. At one end, the spring F is secured to the chassis 41 of the magnetic card reader and at the opposite end to a rod member 58 comprising a plurality, preferably three, of rocker arms 66, 67, 67, cf. Figures 3 and 4.

One end of these rocker arms is pivotably secured to the rod member 58. Substantially in the middle of the rocker arms, said rocker arms are fixed in their respective centres of rotation relative to the chassis of the magnetic card reader. The opposite end of the first rocker arm 66 may a but the carrier of the magnetic head, i.e. the sled 43, whereas the other rocker arms 67 at their opposite ends are shaped as locking pins 55 which may engage corresponding holes in the magnetic card 21. When influenced by the elastic force F, the rod member 58 with the rocker arms 66 and 67 are pressed into one outer position, in which the locking pins engage the holes in the magnetic card.Only when the sled in its starting position presses on the first rocker arm 66 and consequently counteracts the elastic force F and presses the lock mechanism into its second outer position, the locking pins 55 on the remaining rocker arms disengage the holes of the magnetic card.

Therefore the card can only be removed when the carrier 43 of the magnetic head is in its starting position 46. The lock mechanism may also be shaped as a spring-loaded frame provided with locking pins 55.

A plurality of sensors, at least five, A, B, C, D, and E, which e.g. may be photocells or microswitches are electrically connected to the electronic control circuit in the electronic unit 10, e.g. through a 34-wire flat cable 7, and mechanically secured relative to the chassis 41. These sensors detect whether the sled is in its upper position, i.e. the starting position 46, whether the magnetic head 44 is clear of the magnetic card 21, whether the magnetic card has been inserted in the magnetic card reader and has been completely inserted, whether the sled 43 is in its bottom position, and whether the lock mechanism 45 engages in such a manner that the card is locked. Furthermore, a speed sensor 52 is provided, e.g. a photocoupler comprising a light diode and a detector extending across a performed disc 77. This perforated disc is mounted on the shaft of the motor 54 in such a manner that the photoelectric detector transmits a row of pulses, the frequency of which depends on the number of revolutions of the motor.

In this manner it is possible to synchronize the writing speed with the speed of the sled in such a manner that a correct bit-density of the written information ia obtained.

As magnetic tape, the 3M dual-layer high coercive type may be used, which is particular by the fact that the lower layer of the tape may contain information not immediately erasable or amendable since a thirteen times higher magnetic field intensity is necessary for amendment than the field intensity necessary in connection with standard magnetic tapes. A card 21 with magnetic tape is initially encoded a permanent individual identification code.

This encoding must be performed on particular encoding machines with a particularly high magnetic field intensity. The code is applied to one magnetic track 82 in the magnetic layer which is particular by its particularly high coercivity. The code may for instance appear as illustrated in Figure 5, whereby it comprises a number of four figures specific to the system in question, and a number also of four figures and specific to each card. Consequently this code may be considered a personal customer number or an identification code, a socalled ID-code. Subsequently, a division sign called "Wittenborg's separator" or a "sentinel" follows, which comprises two figures, viz. C7, whereafter the ten figures are repeated three more times. In this manner the track comprises a total of forty characters, each character being represented in the form of five bits, i.e. 200 bits in total.When the customer receives his card, this piece of information has been permanently encoded.

The mode of operation of the system is described below in greater details.

On a writing-up terminal, cf. Figure 2, the customer may pay an amount either through a coin mechanism or through a banknote detector. Subsequently, an amount at his disposal or a balance of the card is encoded on the first magnetic track 81.

Below this balance is called the amount code and is immediately followed by a security code related both to the amount code and to the permanent individual ID-code on the second track 82. Usually the security code is a mathematical function of the amount code and the ID-code, and usually it is the sum ofthetwo numbers.

The amount and security code is synchronously situated on the first track 81 relative to the identification code on the second track 82, cf. Figure 6. When reading a card, the card is only accepted provided the security code forms the correct relationship between the ID-code and the amount code, and provided the amount and security code has been correctly arranged relative to the identification code, whereby a securing against falsification is provided.

In the system, the card is encoded with the amount and security codefourtimes in such a mannerthat each of the four codes is individually readable, whereby the card may be read and accepted provided only one of the codes is intact. Upon the reading and the acceptance of a card, the read information is stored in the memory of the system in the electronic control circuit 15, whereafter the amount and security code of the card is erased prior to a purchase by the card as means of payment. In this manner the customer has no advantage of trying to remove the card from the card reader of the vending machine before the new amount code has been applied.Furthermore, no code from a previous writing exists, which possibly cannot be written upon with a new code due to difficulties in reading the ID-code, with which the amount and security code must be synchronously arranged.

Below the mode of operation of the card reader is described with reference to Figures 7 and 16 illustrating the various positions of the card reader from the moment a card is inserted into the card reader and until the transaction has been terminated.

In Figure 6 the card has been inserted, and the card reader is ready to start. In this position, the sensor A detects that the sled is in its starting position, the sensor B that the magnetic head is clear of the card one or more sensors C that the card is inserted, the sensor D that the sled is not in its bottom position, and the sensor E that the locking pins are not yet engaging. The electronic control circuit receives signals from the sensors and transmits corresponding activating signals to the sled motor and the reading (and writing) unit with the magnetic head 44.

As the sled starts to move downwards, cf. Figure 7, the locking pins 55 engage the holes in the magnetic card. If the procedure is not possible for some reason, e.g. because the holes are covered by an additionally applied material, the sled returns at once to its starting position. The expressions "downwards" and "upwards" are used at present for the sake of convenience, but should not be considered a restriction of the invention. The card reader may, of course, also be turned in such a manner that the card is horizontally or possibly obliquely located, as well as the sled may have its starting position at the bottom and instead start to move upwards. In the preferred embodiment, the card is, however, inserted through a vertical slot, and the starting position of the sled is the upper position thereof.

During the downward movement of the sled, cf.

Figure 8, the not permanent information, if any, is erased frown the second magnetic track 82 with the ID-code. In this manner it is ensured that the remaining information on this track is the permanent code and only this code. When the card is not a dual-layer card with a permanent code, the card is rejected at the subsequent reading. When the sled has reached its bottom position, cf. Figure 9, this positioning is registrated by the D which subsequently amends its signal to the electronic control circuit 15. Then the circuit changes the direction of rotation of the driving motor 54 of the sled, and the sled 43 thereby moves upwards towards its starting position, cf. Figure 10. During the upward movement of the sled, both tracks 81, 82 are simultaneously read, i.e. both the amount and security code and the identification code, and registered in the memory means.

When the reading has been terminated, cf. Figure 1 1,the electronic control circuit 15 determines whether at least one of the codes on each track 81, 82 is acceptable, i.e. whether the amount and security code is synchronously arranged relative to the ID-code, and whether the security code has the predetermined mathematical relationship to the IDcode. When this is not the case, the sled 43 is moved to its starting position 46, and the card may subsequently be moved by pressing down the "card return" - button.

When the card is acceptable, the sled 43 starts to move downward again in a manner controlled by the electronic circuit 15, cf. Figure 12, and this time the amount and security code is erased from the first relatively weak magnetic track 81.

After termination of the erasing, i.e. when the sled is in its bottom position, this positioning is detected by the sensor D, cf. Figure 13. Now the system is ready to perform the desired transaction, i.e. either to dispense an article or to receive money, e.g. on the basis of data encoded by the customer on the keyboard 12 of the electronic unit. Subsequently, the electronic unit calculated the new amount and security code, and the sled starts to move upwards again, cf. Figure 14, in a manner controlled by the electronic circuit. During the upward movement of the sled, the magnetic head 44 encodes the new amount and security code into the first track 81.

The lock mechanism 45 is not opened until the sled has returned to its starting position 46, cf. Figure 15, and said opening is performed by the locking pins tilting out of the holes 57 in the card corresponding thereto.

The above amount and security code and the lock mechanism used render it very difficult to perform falsifications. Since dual-layer cards having a permanent ID-code are only accepted, it is impossible to falsify a card by copying the entire card, unless a very particular machinery is employed. If it is tried to copy onto another dual-layer card, the security code is incorrect, since the second card has another ID-code. Furthermore, any manipulation is particularly difficult due to the requirement of the synchronized arrangement of the tracks. The complete erasing of any amount on the card before the dispensing of the article ensures that the customer does not try to remove his card until the correct new balance has been encoded.

The invention may be varied in many ways without thereby deviating from the scope thereof.

The card reader may for instance be constructed in such a manner that the magnetic card is displaced without release of the card and while the reading head is retained.

Figures 17 to 20 illustrate a preferred embodiment of the card reader according to the invention. The reference numerals of Figures 17 to 20 correspond, when possible, to the reference numerals of Figures 1 to 4 plus 100. The card reader comprises an aluminium frame with a slot 142, through which a magnetic card is insertable.This card readerfurthermore comprises a movable, motor-driven sled 143 with a sound head 144, a lock mechanism 145 preventing the card from being removed when the sled is displaced from its starting position, five sensors D, A, B, C, E detecting the presence of the card and the positions of the sled, a speed-sensor 176, 177 synchronizing the writing speed in such a manner that a correct bit density of the written information is obtained, an interface circuit 110 with a decoding circuit and.an actuating circuitforthe sound head, an actuating circuit for the motor 154, and buffer circuits for the sensors A-E.

The construction and mode of operation of this card reader is not described in details, since the card reader corresponds exactly to the previously described card reader, apart from the fact that the lock mechanism 145 and the interface circuit 110 connecting the card reader to the remaining electronic circuits of the vending machine, which are described below.

In this embodiment, the lock mechanism comprises an elongated rectangular frame 240, cf. Figure 17, tilting about turning pins 242. A plate member 244 having locking pins 155 is loosely mounted on top 243 of one long side of the tilting frame. These locking pins 155 may slide downwards into the holes of the card adapted for this purpose. The other long side of the tilting frame does not appear apart from a short arm 245 at the starting position of the sled. The arm may co-operate with a pivotal wheel 246 on the sled 143. The arm 245 comprises a horizontal contact surface in such a height that the wheel 246 of the sled presses the arm 245 downwards when the sled returns to its starting position in such a manner that the frame tilts about the turning pins 242.In this manner the first long side with the locking pins 155 of the tilting frame tilts upwards and is released from the holes of the card. The arm 245 is quite short and obliquely cut in such a manner that the wheel of the sled may slide upwards on the arm when the sled returns to its starting position, and in such a manner that the wheel of the sled only presses the arm in the starting position of the sled. The frame is springloaded by a spring F pressing the arm 245 upwards when the sled is not in its starting position, whereby the card is locked. A sensor E is located within the long side of the frame and opposite the loosely mounted plate member 244. This sensor E presses inwards when the long side with the locking pin 155 of the frame tilts downwards and locks the card.

The interface circuit 110 for the card readed is mounted in connection with the aluminium frame 101 of the card reader, cf. Figure 19, and a block diagram of the circuit is illustrated in Figure 20. In turn, the interface circuit is connected to the electronic control circuit through the connector 51. The interface circuit comprises decoding and actuating circuits 322 for the sound head 144, an actuating circuit 320 for the motor 154, and buffer amplifiers 321 for the sensors A, B, C, D, and E, as well as the photocoupler 177, 176. Figures 17 and 18 are diagrammatical views of the arrangement of the sensors. These sensors are directly connectable with the actuating circuit of the motor for the control of the sled.The sensor D is for instance connected to the actuating circuit in such a manner that the direction of the motor current is turned when the sled has reached its bottom position. The actuating circuit of the motor is furthermore connected to the actuating circuit of the writing head for track two in such a manner that a not permanent piece of information, if any, on track two is erased, e.g.

during the forward movement of the sled.

This card reader can read and write on every deformed or partially mechanically deficient cards.

The card reader can be adpated to move forward and backward as many times as desired, e.g. in order to erase low-coercive signals, if any, on the highcoercive track two of the card and consequently to reject low-coercive false copies of the card. When the old amount code is to be erased, the tone head switch is controlled by a simultaneous reading of the high-coercive track two. In this manner it is no longer possible that an erasing could be prevented by inserting for instance a thin piece of sheet material between the sound head and the card. The card reader can perform several attempts of writing the new amount code if the first time is unsuccessful.

If the code has not been written when the sound head reaches its top position after the writing, the reader stops before the card is released and the display shows "help". Then the customer can activats the "card return"-button once more, and the reader moves downwards and tries to write once more. The writing can be indirectly checked since the sound head switch always can be secured by control-reading the high-coercive track two. The amount is not erased from the memory in the electronic control unit until it has been written on the card. Unknown magnetic cards, if any, such as bank cards are not acceptable by the aparatus because these cards do not have holes corresponding to the locking pins of the card reader.An additional advantage of the card reader is, that unknown means inserted therein may either be removed from the front or be pushed through the reader and fall down into the bottom of the vending machine. If the movement of the reader is blocked, this circumstance is registered by the speed-sensor 176 whereafterthe sled motor stops and the display shows "help". The blocking object may then merely be removed and by a pressing down on the "card return"-button be returned to the starting position.

The card reader according to the invention provides a novel security against falsifications of the card as a consequence of the particular security code being a relationship between the balance and the identity code and as a consequence of the synchronizing. These two properties preventtogetherthe possibility: of copying the amount code onto a second medium, of using the cash deposit of the card and subsequently of copying the original amount code back again from the second medium.

Furthermore, the system is particularly advantageous in that the particular division sign C7 permits refinding to synchronous reading between the two tracks if bits are lost during the reading. The security system used may, of course, be combined with a control of the identity of the user, e.g. by the user himself keying his identity number on the keyboard of the vending terminal.

Claims

1. A payment system comprising a magnetic card reader for vending machines of the type whereby a customer by means of a personal magnetic card of the dual-layer type as means of payment may buy an article from a vending machine, said magnetic card reader comprising a magnetic head displaceable relative to an inserted magnetic card, a speed-measuring device transmitting a signal proportional to the speed of the magnetic head relative to the card, and a lock mechanism, characterised in, that in order to lock the card, the lock mechanism may be activated by a carrier for the magnetic head, and that the lock mechanism only is open when the carrier with the magnetic head is in a predetermined starting position, and that the magnetic card reader is connected to an electronic unit comprising an electronic control circuit with data processing means, preferably a programmed microcomputer, said control circuit being adapted in such a manner that when one or more sensors have detected the insertion of a card it implies that the magnetic head is displaced relative to the card from its starting position across a first and a second magnetic track in the card and erases possible, not permanent information codes on the second track, and when a sensor detects that the card is not locked due to an error in the card or the machine, said control circuit implies that the magnetic head is returned to its starting position, and when a sensor detects that the magnetic head and the carrier have passed the entire information track and reached their second outer position, said control circuit implies that the magnetic head is returned towards its starting position at the same time as the information codes in the form of blocks including a plurality of figures and a division sign repeated several times in each track are read from both tracks and stored in a memory in the electronic control circuit, the data processing means of said control circuit examining the authencity of the card by determining whether the read information codes are substantially synchronously located on both tracks and possess a predetermined mutual relation, and if this is not the case said means imply that the magnetic head continues to its starting position and stops, whereby the lock mechanism of the carrier of the magnetic head is acutated to open in such a manner that the card may be removed, and that the control circuit further is adapted in such a manner that when the authencity of the information code is acceptable it carries the magnetic head again across the card towards its second outer position at the same time as the information code on the first track is erased, and when the sensor detects that the magnetic head has reached its second outer position, said control circuit stops the magnetic head and awaits a customer's buy of articles, the value of which is fed to the data processing means of the electronic circuit, said means subsequently calculating a new balance which is converted into a new information code, and that the control circuit finally is adapted to imply that the magnetic head again is returned to its starting position at the same time as the magnetic head encodes the new information code into the first track in such a manner that said new code is synchronously located relative to the information code in the second track.

2. A payment system with a magnetic card reader and an electronic control circuit as claimed in claim 1, characterised in that the data processing means of the control circuit are adapted to recognize the division sign, preferably C7, in the formation code in the form of a predetermined bit-pattern (00111 11100), and when said bit-pattern has been recognized to initiate a new registration and storing in memory means of the subsequently read bits.

3. A payment system as claimed in claim 1, characterised in that the magnetic head of the magnetic card reader is spherically suspended, i.e.

on gimbals in its carrier preferably shaped as a sled, which through a spindle and a coupling may be displaced by a motor controlled by the electronic control circuit.

4. A payment system as claimed in one or more of the preceding claims 1-3, characterised in that the lock mechanism comprises a plurality of locking pins which may engage corresponding holes in the magnetic card, said lock mechanism only opening, i.e. retracting the locking pin, when the carrier, preferably a sled, of the magnetic head is in its starting position relative to the card.

5. A magnetic card for a payment system as claimed in one or more of the preceding claims, said magnetic card comprising at least two tracks, each with two layers of magnetic material, of which one layer has a standard coercivity, whereas the second layer has an essentially higher coercivity, characterised in that one track, the standard track, of the card is encoded with an amount and security code comprising a plurality of figures in a block and a division sign repeated several times on the same track, and that the second track, the permanent track, of the card is provided with an identification code for the system and a "personal" identification for the card (ID-code) including the same number of figures and division signs and also being repeated several times on the same track, and whereby the security code is a mathematical function of the amount code and of the personal identification code, and whereby the amount and security code at the encoding is synchronously located relative to the permanent identification code.

6. A magnetic card as claimed in claim 5, characterised in that the amount code, the security code, the ID-code of the system, and the "personal" ID-code of the card comprise four figures each, and that the division sign comprises two characters, preferably (C7), and whereby the amount code, the security code, and the division sign are repeated three times on the first track, and whereby the ID-code of the system and the personal ID-code and the division sign are repeated three times on the second track.

7. A method for encoding a magnetic card, preferably for use in a payment system as claimed in claim 1,andwherebythe magnetic card comprises at least two tracks, each with two layers of magnetic material, of which one layer has a standard coercivity, whereas the second layer has an essentially higher coercivity, characterised in that one track of the card, preferably the standard track, is encoded with an amount and security code comprising a plurality of figures and division signs repeated several times on the same track, and that the second track of the card, the permanent track, is encoded with an identification code for the system and a personal identification code for the card including the same number of figures and a division sign and also being repeated several times on the same track, and whereby the security code is formed as a mathematical function of the amount code and the personal identification code, and whereby the amount and security code is synchronously located relative to the permanent identification code.

8. A method for encoding magnetic cards as claimed in claim 7, characterised in that the amount and security code is encoded in the form of four figures indicating the amount, and four figures indicating the security code as well as the division sign including figures (C7), said ten figures being repeated four times immediately in succession on the same track, and that the indentification code is encoded in the form of four figures indicating the identification code of the system and being equal for all cards for a predetermined type of system, as well as four figures indicating a personal ID-code differing on all cards in a predetermined type of system, and whereby the security code is calculated as the sum of the amount code and the personal ID-code.

9. A payment system substantially as described above with reference to the accompanying drawing.

10. A magnetic card substantially as described above with reference to the accompanying drawing.

11. A method for encoding magnetic cards substantially as described above with reference to the accompanying drawing.