WO1992022878A1

WO1992022878A1 - Electronic reader for magnetic cards

Info

Publication number: WO1992022878A1
Application number: PCT/IT1992/000064
Authority: WO
Inventors: Ivano Faragli; Otello Manfucci
Original assignee: Emmepi Telematica E Sicurezza S.P.A.
Priority date: 1991-06-17
Filing date: 1992-06-16
Publication date: 1992-12-23
Also published as: ITRM910431A1; IT1246620B; ITRM910431A0

Abstract

The object of the invention is to provide an electronic reader for magnetic cards, of the type in which a magnetic card (24), equipped with numerous small magnets (26), which are disposed in a certain number of rows, is manually inserted therein for reading. In said reader, numerous elements for detecting the polarity of said small magnets (26) are disposed in a single row, equal in number to the number of small magnets disposed in one row, and the output of said detection elements is continously scanned at high speed during the advance of the magnetic card. Therefore, the polarities of the small magnets of each row are detected one at a time successively, while the magnetic card (24) is being manually advanced between its entrance position and its end-of-travel position.

Description

Electronic Reader for magnetic cards.

SPECIFICATION The present invention relates to an electronic reader for magnetic cards, which are best known among the experts in the field by the designation "badge". It is well-known that magnetic cards are being used more and more frequently for the identification of persons authorised to have access to particular locations or for the identification of users or of groups of users of particular services. Such cards contain, in general, information stored in the form of a magnetic-type elec¬ tronic key.

In particular, as they are preferred on account of their intrinsic security, magnetic cards are frequen¬ tly utilised in which numerous small magnets are present, these being disposed in a certain number of rows, and in which the information is constituted by the type of polarisation applied to each small magnet.

To read the information stored in the magnetic cards or badges, use has hitherto been made of numerous types of badge readers, in which the electronic key is read and decoded, which electronic key has been per¬ manently recorded on said card upon its first activation by the organisation which authorises the use thereof.

However, the badge readers which have been used hitherto exhibit numerous disadvantages: if use is made of magnetic cards having a magnetic strip there is, in general, a need for an extremely accurate mechanical-type transport mechanism which engages and advances the badge under the reader head and then returns it to a position in which said badge can be manually extracted from the device.

Such a mechanism :^:s, in general, susceptible to malfunctions and wear, • hus requiring maintenance at frequent intervals. However, if use if made of magnetic cards of the type incorporating sm&il magnets or magnetic zones, the readers may be of the static type, i.e. the badge may be manually inserted to reach its position of reading, where the polarity of the small magnets is read by a large number of sensors, in general one for each small magnet. The presence of such a large number of sensors makes readers of this type complicated and costly. The main object of the present invention is thus to provide an electronic reader for magnetic cards, which reader is of an advanced type and has no mechanical moving parts and has the benefits of enhanced speed and flexibility of use. A further object of the present invention is to provide an electronic reader for magnetic cards, having an extremely small number of reading sensors.

Yet a further object of the present invention is to provide an electronic reader for magnetic cards, which reader is capable of replacing the readers of standar¬ dised type which are currently commercially available, maintaining full functional compatibility therewith, so as to be able to replace them without modifications to the equipment in which the reader is used. A further object of the present invention is to provide an electronic reader for magnetic cards of modular structure, in order readily to permit the func¬ tional updating required for further applications.

Yet a further object of the present invention is to provide an electronic reader for magnetic cards of simple and cost-effective structure and construction, which requires less space and which is suitable for mass production.

The electronic reader for magnetic cards accord- ing to the present invention is characterised in that numerous elements for detecting the polarity of the small magnets are disposed in a single row, equal in number to the number of small magnets disposed in one row, and the output of the detection elements is continuously scanned at high speed during the advance of the magnetic card, the arrangement being such that the polarities of the small magnets of each row are detected, one at a time successively, while the magnetic card is being manually advanced between its entrance position and its end-of- travel position.

The principal advantage of the magnetic card reader according to the present invention thus consists in having eliminated the need for the presence of a mechanical device for transporting, advancing or positioning the magnetic card.

Yet a further advantage of the magnetic card reader according to the present invention consists in having considerably reduced the number of sensors, with a consequent reduction in the space required and in the costs.

The present invention will be further clarified, hereinbelow, by the description of a practical embodiment of the electronic reader for magnetic cards according to the invention, said description being given on a purely illustrative and non-limiting basis, with reference to the accompanying drawings, in which:

Figure 1 is a view, in front elevation and on an enlarged scale, of the present reader and shows the orifice for insertion of the badge;

Figure 2 is a view, in plan and on an enlarged scale, of the present reader, with the badge which is being inserted therein; Figure 3 is a time graph and shows the progres¬ sion of the voltage to the sensors while the badge is inserted;

Figure 4 shows the electrical circuit diagram of the currently preferred embodiment of the present badge reader; and

Figures 5 to 8 are flow charts and serve to explain the operation of the present electronic badge reader.

Referring to the figures of the accompanying drawings, and in particular to Figures 1 and 2 thereof, it is seen that the electronic reader for magnetic cards of the invention exhibits an orifice 10 for the insertion of the badge, in proximity to which there are presented the elements for detecting the code of the badge, which elements are constituted, as will be further clarified hereinbelow, by five Hall-effect transistors 12a to 12e. A flexible element, in the form of a leaf spring 14, which is preferably made of plastic having a low coeffi¬ cient of friction, maintains the badge in its position closest to the detection elements when the badge is inserted into the orifice 10 of the reader and is manual¬ ly slid within the latter along suitable guides (not shown) .

The reader also has an optoelectronic entrance barrier formed by a diode 16, emitting in the infrared, and by a phototransistor 18, as well as an optoelectronic end-of-travel barrier formed by a diode 20, emitting in the infrared, and by a phototransistor 22.

Provision is made for the optional positioning of a lens on one or more members of the optoelectronic barriers to alleviate or to resolve entirely the problems of transmission of the beams of infrared radiations which are caused by opacifying deposits of grease or powder, in particular those transported by the magnetic card.

The badge 24, of known type and not forming part of the present invention, is intended to be used in combination with the present reader, and is constituted by a plastic identity card (see Figure 2) in which forty small magnets 26 are embedded. The small magnets 26 are disposed in eight rows of five small magnets each, in such a manner as to form a matrix of small magnets 26_mn, where the index m indicates the number of the sensor, the index number 1 corresponding to the sensor 12a placed in the lowest position, when viewing Figure 2, and the index n indicates the number of the row, the row number 1 being the row placed at the left hand end, again referring to Figure 2. The small magnets are polarised in the course of the manufacture of the magnetic card, in one of their two possible conditions, N-S or S-N, and the magnetic card, in its entirety, constitutes a high security card, on which it is possible to perform a positive verification. The present reader acquires the magnetic code impressed in the magnetic card by scanning the polarity of the forty small magnets, as will be described in greater detail hereinbelow.

To the type of polarisation of the forty small magnets 26, which are disposed as hereinabove described, corresponds the value of forty information bits which are read and are combined in a suitable manner so as to form that which is here referred to as the code of the badge, or DATA_Badge in the flow charts, it of course being possible to have a different code associated with each particular badge.

In other words, the direction of polarisation of the (m,n)-th small magnet determines the value of the i-th bit of the DATA_Badge logic code, in accordance with a suitable conversion table between the position of the small magnet in the badge and the position of the bit in the DATA_Badge logic code. Obviously, when, during its insertion into the present reader, the badge 24 reaches its entrance posi¬ tion, as soon as insertion has taken place, the badge interrupts the optoelectronic entrance barrier, while, when said badge 24 reaches its end-of-travel position,it interrupts the optoelectronic end-of-travel barrier.

Figure 3 shows the progression, with time, of the magnitude v_±(t) of the output voltage of one of the five Hall-effect transistors 12_if when the badge 24 is advanced under the sensitive element of said transistor. Clearly, the magnetic field which describes the polarisation of the small magnets in the badge 24 causes a positive or negative peak of v^t) corresponding to its alignment with the transistor 12_t and the type of peak is dependent upon the direction of polarisation of the small magnet. The acquisition algorithm implemented in the reader samples the five signals v_£(t) in order to recog¬ nise the presence of the peaks: in order to mask the conversion noise, a suitable threshold value and a suitable hysteresis value are defined, as will be descri¬ bed in greater detail hereinbelow.

With reference, now, to Figure 4 as well, it is seen that the present badge reader comprises a type 87C51 microprocessor 28, which is equipped, internally, with its own read only memory (ROM) , with its own random access memory (RAM) and with two internal timers, as well as with a serial port and with three input/output paral¬ lel ports, and with two hardware interrupt terminals INTO and INT1, all the input/output and interrupt terminals being capable of being fully configured via software.

An analog/digital converter 30 is also present, for the sampling and the acquisition of the output voltages of the transistors 12. In order to concentrate the flux lines of the magnetic field generated by the small magnets 26 and thus to amplify their action on the transistors 12, there are provided five ferromagnetic elements 32 (see Figure 1), which are appropriately embedded in a plastic support (not shown) which is disposed immediately above the transistors 12.

In a variant embodiment, not shown, for the purpose of further increasing the concentration of the flux lines of the magnetic fields provision is made for the ferromagnetic elements to have a conformation such as to permit the complete closure of a magnetic circuit com¬ prising the small magnet and the pertinent detection element.

The present badge reader is further equipped with a connector 34 for connection to the main or "host" equipment; it further has a connector 36 for further expansions, to which all the terminals of the micro¬ processor 28 lead and on which all the effective signals are available. In this way, it is possible to make use of the connector 36, for example, for the management of other small peripherals, in a manner compatible with the hardware and software resources available within the system. A description will now be given of the operation of the present badge reader, with reference, in addition, to the flow charts of Figures 5 to 8.

On power-up or in response to the reset hardware, the microprocessor 28 starts the main program, the flow chart of which is shown in Figure 5; as the first opera¬ tion, the hardware is initialised and tested: if the optoelectronic entrance barrier, formed by the emitter diode 16 and by the phototransistor 18, is not activated, i.e. there is no badge inserted, which corresponds to having a zero CARD_START logic signal on the INT1 physi¬ cal terminal of the microprocessor 28, the latter starts the initialisation procedure.

An LED 38 (see Figure 4), which emits in the visible spectrum, is active for 5 s during the initiali¬ sation and is then caused to flash for 2 s, to indicate the end of the initialisation operation. If the hardware has failed, the LED 38 is maintained active; neverthe¬ less, the microprocessor continues to effect the polling of the GO/NO physical line and again attempts the test when it receives a GO or NO_GO logic command on the GO/NO physical line from the host equipment via the connector 34, as will be more precisely stated hereinbelow.

During the SELF_TEST procedure, the microproces- sor 28 tests the hardware: a check is made on the check¬ sum of the code in EPROM; the writing and the re-reading of all the locations of the RAM are executed; the analog/ digital converter 30 is activated in its internal self- test mode; the neutral voltage of the Hall-effect tran- sistors 12 is read, and this must be included within the conversion window of the converter 30. In the event of failure, a frame containing the error code is prepared.

During the neutral periods, in which it is in its

"IDLE" mode with low consumption, the microprocessor 28 is periodically interrupted by the timer number 0 and executes the interrupt routine shown in Figure 6, during which, inter alia, it updates periodically, approximately every 10 s, the value of the neutral voltage present on the transistors 12.

The insertion of the badge 24 interrupts the optoelectronic entrance barrier: the phototransistor 18 changes condition and activates the interrupt number 1 terminal INT1 of the microprocessor 28, delivering thereto a CARD_START active logic signal. Thus, the microprocessor 28 recognises the change of the CARD_START signal as soon as the badge engages the reader: this initiates the routine of reading the DATA_Badge code of the badge 24, and the reader thus acquires the code of the badge which is being inserted.

The five sensors are scanned cyclically until the peak point of the magnetic field is located; at this point, the reading of the row of small magnets is effected. As the speed of operation of the microprocessor 28 is far greater than the speed with which the user manages to pass the badge into the reader, the acquisi¬ tion of the output of the transistors does in any case take place at high speed as compared with the speed of insertion of the badge.

The reader correctly reads the badge 24 if the insertion time is less than 2 s and the acquisition process is terminated upon the occurrence of any one of the following events: a) recognition takes place of when the badge 24 reaches its end-of-travel, as it interrupts the end-of- travel barrier: the phototransistor 22 becomes darkened and thus makes available the information of end-of-travel reached, corresponding to the FC terminal of the micro- processor 28, in the form of a Badge IN_logic signal; b) there is no CARD_START signal corresponding to the INT1 physical terminal; c) nine rows of small magnets 26 are acquired; d) the maximum acquisition time which, as has already been stated, is equal to 2 s, expires.

The acquisition is considered to be correct only if case a) occurs and the number of rows recognised is eight. If the acquisition is correct, the LED 38 flashes until receipt of the GO or NO_GO command. If acquisition errors are present, the LED 38 remains extinguished, except in the event of the detection of an erroneous maximum value on the sensors 12, in which case it is provided that the LED 38 remains active: nevertheless, in all cases a frame containing the located error code is prepared.

Thus, following the interrogation by the host equipment, the present electronic reader for magnetic cards is capable of delivering on its physical output line TX not only the DATA_Badge logic code in the case where the correct reading of a badge has taken place, but also the error codes relating to a certain number of logic errors due both to defective operation of the reader and, especially, to poor handling of the badge by the user or even to attempts to tamper with the equipment.

Such error codes, which are presented at the output of the badge reader, relate to: I) erroneous neutral level on the sensors;

II) erroneous maximum value on the sensors;

III) erroneous number of rows acquired;

IV) erroneous extraction of the badge;

V) erroneous insertion of the badge; VI) exceeding of the time limit during the acquisition of the code of the badge.

The analog-type components, such as the sensors 12 and the converter 30, are subject to dispersion of the characteristic operational electrical parameters; this is taken into account by periodically effecting an automatic compensating calibration. In particular, during the ZERO procedure (see Figure 6), the output level of the sensors in the absence of any magnetic field is detected; the difference in sensitivity to the magnetic field and the mechanical tolerances affect the response of the sensors of the transistors 12 to the magnetic field generated by the small magnets 26: thus, the system is operated in such a manner that the acquisition algorithm adjusts the intervention threshold as a function of the maximum level measured.

In the testing phase, by means of the LED 38 it is possible to monitor the correct operation of the hardware: immediately after power-up and on reset hard¬ ware, testing takes place of the hardware resources of the microprocessor 28, the analog/digital converter 30 and the Hall sensors 12, specifically for the purpose of testing their behaviour in the absence of any magnetic field; moreover, when the badge 24 is inserted, a check is made that the sensitivity of the sensors is sufficient.

A circuit formed by a capacitor 42, by a transis¬ tor 44, by an inverter 46 and by their associated com- ponents (see Figure 4) serves to bring about the automa¬ tic reset hardware of the microprocessor 28 in the case where no readings of the data take place for a certain length of time, which obviously indicates the blocking or in any case the malfunction of the microprocessor 28. In fact, during regular operation, the capacitor 42 is periodically discharged upon each reading by the micro¬ processor 28, as the RD physical terminal is brought to low level during the reading, while it is charged so as to cause the change of condition of the inverter 46, and thus the reset hardware, if" the microprocessor 28 does not execute reading operations for a predetermined time interval. If the operation is regular, RD is periodically forced down for the period of 10 μs during the interrupt routine of the timer 0, which routine is shown in Figure 6.

Via the interrupt routine of the serial port, the flow chart of which is shown in Figure 7, the micro¬ processor 28 responds to the polling effected by the host equipment: if the badge 24 has been inserted, then it transmits the DATA_Badge via the serial port; after a G0/N0_G0 command, it transmits NA ; if the badge 24 has not been inserted, then it transmits NAK; thus, if the badge 24 is inserted and subsequently extracted before - li ¬

the first polling, then it transmits the DATA_Badge in response to the first polling, while it transmits NAK in response to the subsequent pollings, until such time as another badge is inserted. If acquisition errors are present, in response to the first polling it transmits a frame containing the error code.

Following a change of condition on the GO/NO physical line of the connector 34, the reader accepts that the host equipment has correctly acquired the badge code (DATA_Badge) and extinguishes the LED 38, if it was active. It should be specified that the GO/NO physical line of the connector 34, on which the GO/NO_GO logic signal travels, is used as input line for the handshake with the host, with TTL voltage level, and represents a GO logic command if low for the period of 8 to 11 ms, while it represents a NO_GO logic command if low for the period of at least 20 ms.

The TX physical line of the connector 34 is used as serial output line for the DATA_TX data of the reader to the host equipment. The line exhibits TTL voltage levels and the data are transmitted in serial form, for example using 8 data bits, 1 stop bit, and no parity, the data rate being 1200 ba d.

The RX line of the connector 34 is used as input for the handshake with the host equipment, with TTL voltage level, and the ENABLE/Polling logic signal on this line represents a polling request logic command if low for the period of at least 10 ms, while the reader proceeds in continuous transmission if the logic condi- tion of the line remains fixed at the low level. This line can also be used as serial input for particular applications.

In general, however, the present badge reader makes use of a serial interface for transmission alone, i.e. in simplex, by means of which transfer takes place, to the host equipment, of the packets containing the code of the badge, or DATA_Badge, which has been acquired. This interface is also employed in the test phase. The reader passes into a degraded mode (DGM) or IDLE after 30 s of absence of polling by the host equip¬ ment: the LED 38 is active and the reader is predisposed to await a G0/N0_G0 command from the host equipment. When this command is received, it determines the execution of the reset of the reader, which also comprises the execu¬ tion of the SELF_TEST procedure, as shown in Figure 5.

The firmware of the reader includes a number of test and failure search procedures, to be implemented suitably in the test phase. Such procedures are called up by setting four selection microswitches, which form part of a bank 40 of microswitches (dip switch) .

The following functions are in fact provided: if the microswitches are all open, the Dip_Switch logic variable is set to zero and the normal working program is executed; if only the first microswitch is closed, the Dip_Switch logic variable is set to one and the func¬ tional test program is executed (see Figure 8) . Continu¬ ing, depending upon the setting, if Dip_Switch = 2 the level of the sensors 12 is output; if Dip_Switch = 3, the neutral level of the sensors 12 is output; if Dip_Switch = 4, the difference between the current level of the sensors 12 and their neutral level is output; finally, if Dip_Switch = 5, the nominal data of the firmware are output. In this manner, the microswitches 40 permit the selection between the operative program and the test programs which are available within the firmware of the badge reader.

When all the microswitches are open, as has been stated already, the normal working program is executed, during which the reader is in communication with the host via its connector 34 and receives the commands from the latter: via the ENABLE/Polling logic signal from the host, which is present on the RX line of the reader, which is maintained at low logic level for at least 10 ms, the host requests the polling and the reader responds, as has already been seen, by passing the DATA_badge if this is available, or the frame relating to the error which has occurred, or NAK if the DATA_Badge is not available.

For the operation in execution of the tests, i.e. when the microswitches 40 are not all open, provision is also made for the possibility of connection with a personal computer, without engaging the host.

Naturally, many of the constructional and application details of the preferred embodiment of the present magnetic card reader may readily be modified, specifically by virtue of its modular construction.

By way of example, the number of sensors 12 may readily be increased or reduced in order to utilise cards different from that described, in particular cards which have a different number of small magnets in each row. ' Moreover, for the utilisation of magnetic cards having a different number of rows of small magnets, it is simply necessary to carry out modifications to the firmware of the reader.

Moreover, in a variant embodiment (not shown) use has been made of a number of optoelectronic barriers, equal in number to the number of rows of small magnets 26, in order to locate the instant of precise alignment of the small magnets with the sensor of the pertinent detection element. This arrangement clearly gives a lightening of the management software of the micro¬ processor, the function of detecting the instant at which to effect the reading of the peaks of the voltage j(t) having been delegated to the hardware.

It is obvious that further numerous and differing variants and modifications can be carried out by persons skilled in the art to the embodiment of the present invention hereinbefore described, without departing from the spirit thereof. Thus, it is understood that such variants and modifications shall all fall within the scope of the invention.

Claims

1. Electronic reader for magnetic cards, of the type in which a magnetic card (24), equipped with numerous small magnets (26), which are disposed in a certain number of rows, is manually inserted therein for reading, characterised in that numerous elements for detecting the polarity of said small magnets (26) are disposed in a single row, equal in number to the number of small magnets disposed in one row, and the output of said- detection elements is continuously scanned at high speed during the advance of the magnetic card, the arrangement being such that the polarities of the small magnets of each row are detected one at a time successively, while the magnetic card (24) is being manually advanced between its entrance position and its end-of-travel position.

2. Reader according to Claim 1, characterised in that the elements for detecting .the polarity of the small magnets (26) are constituted by Hall-effect transistors (12).

3. Reader according to Claim 1 or 2, characterised in that a microprocessor (28) is used to effect the continuous scanning, at high speed, of a signal corre¬ lated with the output of said elements for detecting the polarity of the small magnets (26).

4. Reader according to Claims 2 and 3, characterised in that an analog/digital converter (30) is interposed between the outputs of said Hall-effect transistors (12) and said microprocessor (28), said analog/digital con¬ verter (30) delivering to said microprocessor (28) a digital signal correlated with the analog output of said Hall-effect transistors (12).

5. Reader according to Claim 4, characterised in that said microprocessor (28) acquires, during the reading of the magnetic card, the output of said analog/ digital converter (30) continuously at high speed and detects the presence of the peaks of the output signal of said Hall-effect transistors (12), which correspond to the instant of alignment of the small magnets (26) of a row with the Hall-effect transistor (12) detection elements.

6. Reader according to any one of Claims 3 to 5, characterised in that said microprocessor (28) periodi- cally acquires the value of the neutral voltage present on said transistors (12) in the absence of any magnetic field and adjusts the intervention threshold as a func¬ tion of the maximum level measured.

7. Reader according to Claim 6, characterised in that said microprocessor (28) detects and transmits upon request to the host equipment the errors relating to one or more of the following conditions: erroneous neutral level on the sensors; erroneous maximum value on the sensors; erroneous number of rows acquired; erroneous extraction of the badge; erroneous insertion of the badge; exceeding of the time limit during the acquisition of the code of the badge.

8. Reader according to any one of Claims 3 to 7, characterised in that a reset hardware circuit (42, 44, 46) is provided, which automatically commences operation in the event of blockage or of malfunction of said microprocessor (28).

9. Reader according to any one of Claims 3 to 8, characterised in that there is provided an optoelectronic entrance barrier which reveals the insertion of a mag¬ netic card in said reader and causes the start of the routine for the acquisition of the code of the magnetic card by said microprocessor (28).

10. Reader according to Claim 9, characterised in that said optoelectronic entrance barrier is constituted by a diode (16) emitting in the infrared and by a photo¬ transistor (18).

11. Reader according to any one of Claims 3 to 10, characterised in that there is provided an optoelectronic end-of-travel barrier which reveals the reaching of the end-of-travel by the magnetic card and thereby interrupts the process of acquisition of the code of the magnetic card by said microprocessor (28).

12. Reader according to Claim 11, characterised in that said optoelectronic end-of-travel barrier is con¬ stituted by a diode (20) emitting in the infrared and by a phototransistor (22).

13. Reader according to Claim 10 or 12, characterised in that at least one (16, 18, 20, 22) of the members of said optoelectronic barriers is equipped with an antidust protective lens.

14. Reader according to any one of the preceding claims, characterised in that numerous ferromagnetic elements (32), numbering one for each one of said detec¬ tion elements, are disposed in proximity to said detec¬ tion elements, the arrangement being such that said ferromagnetic elements (32) concentrate the flux lines of the magnetic field generated by said small magnets (26).

15. Reader according to Claim 14, characterised in that said ferromagnetic elements (32) have a conformation incorporating a closed magnetic circuit, each comprising a small magnet (26) which is being explored and the pertinent detection element.

16. Reader according tfo any one of Claims 1 to 4, characterised in that there are provided numerous optoelectronic barriers, equal in number to the number of rows of small magnets (26) to be explored, the arrange- πent being such that the darkening of each optoelectronic barrier locates the instant of precise alignment of the small magnets (26) of a row with the sensors of the pertinent detection elements.

17. Reader according to any one of the preceding claims, characterised in that a leaf spring (14) urges the magnetic card which is being explored towards said detection elements.

18. Reader according to any one of Claims 3 to 17, characterised in that the firmware of said microprocessor (28) includes test and failure search procedures to be implemented in the test phase, and such procedures are called up by suitably setting a number of selection microswitches forming part of a bank (40) of microswitches.

19. Electronic reader for magnetic cards, substan¬ tially as hereinbefore described with reference to the accompanying drawings.