GB2127479A - Security device - Google Patents

Abstract

This invention relates to a coded- card key device 1 having a plurality of infrared radiation transmitting non- visible radiation-transmitting zones 4 disposed in an individual spatial disposition combination selected from a large number of different possible such combinations, in a body which is substantially non-infra-red radiation- transmitting 3, for transmission of infra-red radiation from one side 7 to another side of opposed sides of the card 1. The invention also relates to a security device for use with a key device of the invention with a card receiving cavity 13 having infra-red radiation transmitting means 15, and infra-red detection means 16 generally opposite said transmitting means. The detection means are arranged in a security circuit for controlling a security switch means PB. <IMAGE>

Description

SPECIFICATION Security device The present invention relates to coded-card key operated security devices.

Coded-card key operated security devices are becoming increasingly important in a wide range of applications. Known systems however provide only limited numbers of possible combinations and/or require complex and expensive equipment for reading of the coding embodied in the card.

It is an object of the present invention to provide a new and economic form of coded-card key operated security device.

The present invention provides in one aspect a coded-card key device having a plurality of infrared radiation transmitting non-visible radiationtransmitting zones disposed in an individual spatial disposition combination selected from a large number of different possible such combinations, in a body which is substantially non-infra-red radiation-transmitting, for transmission of infra-red radiation from one side to another side of opposed sides of the card.

The outward appearance of the coded-card key device can be made substantially similar to other known card key devices so that it is not possible to ascertain the nature of the coding system used let alone the actuai individual code used. In addition the card can be made in a simple and economic manner by punching out or otherwise forming apertures in a conventional opaque card key blank and filling and/or screening the apertures with suitable infra-red radiation transmitting non-visible radiation-transmitting material.

The present invention provides in a further aspect a coded-card key operated security device comprising a body having a card receiving cavity having opposed transmitting and receiving sides, said transmitting side being provided with infrared radiation transmitting means, and said receiving side being provided with infra-red detection means generally opposite said transmitting means for detecting infra-red radiation at at least one zone disposed so as to be successively traversed by a plurality of infra-red transmitting and non-infra-red transmitting zones in a said coded card in use of the device, said detection means being arranged in a security circuit for controlilng a security switch means having unlocked and locked conditions so that reception of infra-red radiation by said means through a said coded-card having a correct individual combination of infra-red transmitting zones is necessary to transform said security switch means from its locked condition to its unlocked condition, and connection means for connecting said security circuit and infra-red transmitting means to an electrical power supply.

The security device of the invention including in particular the code reading means is also of a relatively simple and economic construction which does not require any complex timing and/or card feeding means to ensure that the code is 'read' at a specific rate to ensure that it is correctly identified.

Various applications of the present invention will be apparent to those skilled in the art including for example cash dispensing apparatus, and security doors. A particularly useful application though is in relation to motor vehicles for controlling for example the ignition circuit and/or the steering lock.

Further preferred features and advantages of the invention will appear from the following detailed description given by way of example of a preferred embodiment illustrated with reference to the accompanying drawings in which: Fig. 1 is a side view of a coded-card key of the invention; Fig. 2 is an elevation showing a side edge of the card key of Figure 1; Fig. 3 is a longitudinal section through the card-receiving aperture in the principal plane thereof of a card key-operated security device of the invention for use with the card-key of Figure 1; Fig. 4 is a transverse section through part of the device of Figure 3 on a slightly larger scale; and Fig. 5 is an electrical circuit diagram of the device of Figures 3 and 4 with certain parts omitted for the purposes of clarity.

Figures 1 and 2 show a coded-card key 1 for use with a card-key operated security device. The card key 1 is made up of a sandwich of two outer layers 2 of an infra-red radiation transmitting material separated by a middle layer 3 of a noninfra-red radiation transmitting material provided with a plurality of apertures 4 arranged in a predetermined combination of selected positions from a two dimensional array of four rows 5 and four columns 6, different selections of the available permutations of apertures in the array or grid of positions corresponding to different combinations.

The outer layers 2 of the card are conveniently made of a relatively rigid plastics material which is preferably substantially non-translucent with respect to visible radiation in order to substantially conceal the disposition of the apertures in the card for security purposes.

Known such materials are generally blackish in appearance.

The middle layer 3 may be made of any material but is non-infra-red radiation transmitting and may for example be of metal foil.

The apertures 4 may simply constitute voids within the card 1 or could be filled with an infrared radiation transmitting material such as a clear plastics material or even the same material as the outer layers.

One or other of the outer side faces 7 of the card 1 may conveniently be provided with appropriate visible information such as for example a coloured band 8 for use in indicating which way up or round the card should be inserted into the security device. Care should of course be taken though to ensure that any such markings do not interfere with infra-red transmission characteristics of the apertures 4.

The security device 8 shown in Figures 3 to 5 comprises a housing 9 having therein and outer support 10 for a plurality of rollers 11 disposed along opposed side edges 12 of a card receiving cavity 1 3 and an inner support 14 for supporting a column of four infra-red radiation transmitters 15 and a column of four infra-red radiation receivers 1 6 in opposed relation behind respective grid holes 22 in respective side faces 1 7 of the card receiving cavity 1 3.

One 1 8 of the rollers 11 is supported so as to stand proud of the others, on a contact member 1 9 reciprocably displacable between an extended position as shown in Figure 3 in which it is supported by resilient biasing means 20 in spaced apart relation to two contacts 21, and a retracted position substantially flush with the other rollers 11, into which it is displaced by the leading end of the card 1 as the latter is inserted into the cavity 1 3 against the biasing force of the spring 20, in which position said contact member completes a circuit between the two contacts 21 to activate the security device circuit and in particular the infra-red transmitters 1 5 to start emitting infrared radiation.As each column 6 of apertures 4 in the card 7 passes the column of grid holes 22 the receivers pick-up a code element comprising a particular combination if radiation pulses corresponding to the combination of apertures 4 e.g. in the case of the first column 4 the top receiver 16 and the third receiver 1 6 down from the top, only receive infra-red radiation. The reception of the infra-red radiation results in the transmission of signals from the various receivers 16 indicating whether or not any individual receiver has picked-up infra-red radiation and hence whether there is an aperture in a particular row 5 of the column 6 being examined at any given stage i.e. whether that code sub-element is 'hole' or 'not-hole', the whole column constituting a code element and all the columns together constituting the whole code.

These signals are then processed by an electrical circuit such as that shown in Figure 5 so as to produce an output which results in 'unlocking' a security switch means for example completing an operating circuit such as the ignition circuit of a vehicle or an electrically operated release means e.g. solenoid switch for unbolting a steering lock of a vehicle, only when the coding in the card key corresponds to a preset coding in the above-mentioned electrical circuit. If the coding does not correspond then not only does 'unlocking' not take place but advantageously an alarm means e.g. the horn or lights of a vehicle, is activated.

Further details of the circuit shown in figure 6 and its mode of operation will appear from the following description.

When the card is pushed in it will move along the rollers until it closes normally open switch SWA. This will supply a +ve to one of the inputs of the exclusive OR gate N1 (output=O when both inputs high). This switches on TR1 and thus D1 an infra-red emitting diode is powered. However such is the construction of the card that at the instant SWA is depressed infra-red blocking material (the middle layer) is present between the emitter and receiver so that the Darlington pair (gain=hfe TR2xhfe TR3) consisting of TR2 (infrared sensitive) and TR3, is to all intents and purposes switched off. Each of four gates N2 (only one shown for clarity) is an NAND gate having both inputs high so that its output remains low.A 4-input NOR gate N3 (output high only when all inputs low) holds a binary-to-decimal convertor (BDC) integated circuit ICI in the inhibited state by switching on TR4 drawing the +ve supply to the "enable" input of the BDC to earth.

When each column made up of one or more holes and any not-holes, passes the emitters/receivers a binary code element corresponding to the particular combination of hole(s) and not-hole(s) in said column will be presented to the BDC. When a hole is present the output of the corresponding gate N2 to the BDC is high and when a not-hole is present this output is low so that the binary code element will be in the form of a combination of high and low outputs.

After the first column of holes and not-holes has passed the emitters/receivers there is a row of infra-red blocking material so that N3 goes high inhibiting the BDC. As long as one of the rows in a column is a hole the output of N3 will be low, TR4 will thus be switched off and a +ve will appear at the enable input of the BDC.

The output of the BDC will change as each column, corresponding to one code element, passes the emitters/receivers. These outputs are connected to the code element (1), (2), (3), and (4) inputs of an electronic key lock integrated (I.C.2) LS7220. Only when pins 3, 4, 5, 6, of the l.C.2 receive a +ve in that order will the output of the l.C.2 go high. The latter is however also conditional on a +ve or high input to a 'sense' pin 1 of the l.C.2 being maintained throughout the reading of all the code elements. If a dummy output of the l.C.2 is activated for any reason e.g.

by using a cord with one or more 'wrong' code elements producing a decimal output other than any of those corresponding to the l.C.1 output pins feeding l.C.2 input pins 3, 4, 5, 6, there is a drop of the sense input to the i.C.2 disabling it and C1 charges up. This will occur even if one or more 'correct' code elements have already been supplied to pin 3 and the succeeding input pins of l.C.2. Even if the correct code should now be entered, C1 will continue to discharge through R10 for a time period determined by R10 and C1 during which period the 2 =ve's at the gate of N4 will hold its output low thereby continuing to disable l.C.2. Therefore the system is particularly difficult to beat as the wrong combinations entered will close the system down completely for a predetermined period of time so that even the right "code" will be ineffective during this period.

When reading of the coded card has been completed and the whole code entered in the IC2 circuit output returns firstly to the exclusive OR gate N1, inhibiting the infra-red diode by switching off TR1. This saves power by switching off the infra-red diode emitters as soon as they are no longer required. The output also goes to TR5 via R9 to draw the +ve from the enable input of the BDC thereby inhibiting it. In addition the output goes to S/E to enable the steering lock release mechanism. Once the steering lock has been unlocked an output from S/R is supplied to push button switch PB 1 and operation of this will now bring on the lights, radio etc. of the car by clocking FF1 whose output goes high switching on TR5 and thus powering RLA (contacts normally open).The black circle is a symbol indicating generally the various apparatus in the car requiring electrical power.

In addition the following features will also usually be provided: Push-button PB2 stops the car and removes the supply to the lights and radio etc. It will of course be appreciated that the detailed design of the power supply and control of the less important ancillary facilities such as the radio and electric aerial to provide functioning thereof when the car is not running may be readily varied without departing from the scope of the present invention and are in no way essential to the present invention.

To cancel the code push-button PB3 removes the sense from the l.C.2. A car going into a garage for a service can be started and stopped without the need for the card to be given to the garage as long as the code has not been cancelled.

Push-button PB4 is used to control the starter motor of the vehicle in the normal way but is of course itself controlled by the security circuit.

It will be appreciated that the manufacture of 'both the coded card itself and the code-reading means is relatively simple and economic whilst offering a relatively high degree of security.

It will be appreciated that various modifications may be made to the above embodiments without departing from the scope of the present invention. In particular the coding may be in a different form being for example in a single linear bar-code of alternating bands of infra-red radiation-transmitting and non-i nfra-red radiation-transmitting materials of varying width in place of the two-dimensional array of infra-red radiation transmitting apertures. The advantage of this form of coding is that only a single infrared radiation transmitter and receiver system is required thereby enabling a more economic form of construction.

Fig. 6 is a longitudinal section on a considerably enlarged scale perpendicular to the plane of an alternative form of card of the invention based on the above principle. The card 31 comprises two outer layers 32 of infra-red radiation-transmitting plastics material between which is sandwiched a substantially co-extensive sheet of non-infra-red radiation-transmitting material 33 in which is provided a series of parallel spaced-apart slots 34 extending at rightangles to the longitudinal axis X-X of the card 31 (see Fig. 7 which is a plan view of one side of the card of Fig. 6) which axis corresponds to the direction of feeding F into the security device to be operated by the key card 31. The slots 34 are at more or less regular intervals but this is not essential.The slots 34 are however of two or more different widths, the coding comprising different predetermined combinations of narrower and wider slots 35, 36 respectively. Assuming only two different widths W wide and N narrow are used then there is obtained a binary coding NWWN N W or 011001 in the particular card shown.

The width of the wider slots 36 is generally similar to or greater than that of the infra-red radiation receiving aperture of the device on the receiver side (of the grid hole 22 in Fig. 4) whilst the width of the narrower slots 35 is made to be significantly narrower so that two distinctly different maximum infra-red radiation signal levels (high and low) are obtained at the single receiver. The narrower slots must though be sufficiently wide to produce a distinct signal level at the receiver.

It will be appreciated that the above combination of high and low signal levels can be achieved in other ways. One further example is illustrated in Figs. 8 and 9 which are corresponding views of another key card of the invention.

In Figs. 8 and 9 like parts are identified by like reference numbers. In this case in place of the sheet of infra-red blocking material 33 with slots of varying width there are employed a first sheet of infra-red blocking material 37 with a plurality of slots 38 of substantially equal width and a second sheet 39 of a partial infra-red blocking material. The latter may be a relatively thin sheet of a poor infra-red transmitting material e.g. paper or a thicker sheet of a somewhat better infra-red transmitting material.

The partial infra-red blocking sheet 39 is provided with a plurality of slots 40 aligned with those 38 of the first sheet but usually fewer in number so that there is obtained in the card a number of code elements comprising high infrared signal transmitting elements 41 in which apertures 38, 40 in both sheets 37, 39 are aligned and low infra-red signal transmitting elements 42 in which only the aperture 38 in the first sheet 37 is present.

The resulting code obtained in the key card of Figs. 8 and 9 may be seen to be the same as that in the key card of Figs. 6 and 7 viz 011001 (reading from the leading end 43 of the card to the trailing end 44.

It will be appreciated that although in the above cards the individual code-elements are shown to be spaced apart and physically separated this is not strictly essential in the case of adjacent dissimilar elements i.e. 'high' and 'low' elements. In general though such separation-by infra-red blocking material zones-is usually preferred for ease of manufacture and to facilitate encoding with different codes.

Fig. 10 is a partial circuit diagram for the code reading part of a security device similar to that of Figs. 4 and 5 for use with key cards of the type shown in Figs. 6 to 9.

A first part of the circuit including an infra-red sensitive transmitterTRl,variable resistance Or 1, capacitor C1 and amplifier Al produces an output voltage substantially proportional to the infra-red radiation transmitted by a given codeelement (e.g. 41 or 42). This output is supplied to two Schmitt triggers A2 and A3 set to respond to predetermined 'low' and 'high' voltages corresponding to '1' and '0' code elements, respectively, in the key card. lU the presence of a '0' code element only A3 is switched on whereas in the presence of a '1' code element both A2 and A3 are switched on. In the case of inter-element blocking material zones neither trigger is switched on. The triggers A2, A3 are arranged so that their outputs go low when they are triggered.

The schmitt triggers A2, A3 are arranged so that when they are triggered their outputs go low and in turn bias off transistors TR2, TR3 causing the voltages at their collectors Y, X to go high. In the absence of any card code elements both X and Y will be at logic 0. In the presence of a 'low' code element Y will go high while X remains at logic 0 and in the presence of a 'high' code element both X and Y will go high. In the latter case the AND gate N 1 output will go to logic 1.

Each time that either X or Y goes high a monostable circuit element sends a pulse to: a) a decade counter DC, which is incremented by 1 with each pulse, and b) a shift register SR, enabling it to "hold" the logic appearing at its data input at the moment it receives the pulse.

A further pulse is now not possible until X and Y both go to zero (i.e. no code element is present between the emitter and receiver) and then either X goes, or both X and Y go high once more as the next code element is read.

When a 'low' code element is 'read' only X goes high and the output of the AND gate N 1 is low i.e. logic 0. The monostable circuit element sends a pulse to the decade counter and a pulse to the shift register which holds logic 0.

When a 'high' code element is read both X and Y go high and as indicated above the AND gate N1 output will go to logic 1. The monostable circuit element sends a pulse to the decade counter and a pulse to the shift register which holds logic 1.

The shift register is used to convert the serially read 'high' and 'low' code elements of the card into a parallel data form which is then converted into a 'parallel' data from which can then be decoded by a Binary-to-Decimal converter.

After all the key card code elements have been serially read they may be read in parallel at the outputs Q1--Q4 of the shift register SR and the decade counter DC incremented a corresponding number of times so that its Q4 output is now high.

The latter output now enables the Binary to Decimal Converter BDC to read the Ol to Q4 outputs off the shift register SR. The decade counter Q4 output is also supplied to an AND gate N5. Meanwhile the inter-code element zone following the last code element of the key card will have caused NOR gate N2 to go high (both X and Y being low) so now the AND gate N5 will have two high inputs so that its output will go to logic 1 and now reset the shift register SR and decade counter DC. This in turn now removes the supply to AND gate N5 from the decade counter DC which has now been returned to its original state with Qo of the decade counter DC high.

In other respects the remainder of the circuit is similar to that described previously. It should be noted though that the LS7220 integrated circuit output is also used to hold the shift register SR and decade counter DC in their initial states once the key card insertion and reading has been completed to avoid the possibility of any system errors due to reading of the card 'backwards' as it is withdrawn.

It will be appreciated that, especially in the case of the second type of embodiment, the card can be made of relatively small size, for example, small enough to be accommodated within a conventional steering column lock barrel, provided the transmitter and receiver means are arranged to have sufficiently high resolution. In such case, manufacture of the card may conveniently be carried out with the aid of photographic etching processes of the general type in the production of miniaturized printed circuits, to produce the required IR-permeable and non-IR-permeable zones pattern. Advantageously the card is provided with mechanical engagement means for example a suitably shaped aperture for engagement with a gripping mechanism for prevention of accidental withdrawal of the key card e.g. when the vehicle is on the move.

Fig. 11 is a shematic block diagram of an arrangement for use with a card key of the general type used in Figs. 6 to 9.

The use of an analogue to digital convertor (A/D), a microprocessor (MPU), read only memory (ROM) and random access memory (RAM) allows analysis of the receiver signal as the card passes between the emitter and receiver (shown in Fig.

10) as follows: As the card passes the amount of infra-red radiation reaching the receiver vanes in intensity (as does the duration of a particular intensity if the card shown in Fig. 6 8 7 is used). The A/D converts the signal from the amplifier into 8-bit words which are stored by the MPU in the RAM, using a routine stored in the ROM, which itself contains the "security code".

A microswitch(s) at the end of chamber signals to the MPU (via the ROM) that the coded area has entirely passed between the emitter and receiver.

The MPU then compares the data contained in the RAM with values stored in the ROM. If the card in Figs. 6 & 7 is used the MPU tries to match the intensity Vs time profile of the RAM data. If the movement of the card has been smooth with roughly constant velocity during the passing of the coded information the MPU can determine the width of the infra-red permeable area by comparing the number of addresses in the RAM corresponding to a particular intensity with those directly preceding and proceeding. The narrow i.r. permeable slots in Fig. 7 are narrower than the interslot i.r. opaque bands, whereas the broad i.r.

permeable slots are of a similar width to the interslot i.r. opaque bands, allowing a comparison which is not too velocity sensitive since the "standard" as to what constitutes a broad or narrow band is itself the inter-band area which logically must proceed and proceed each slot, save the first and last band.

If the card, as in Figs. 8 and 9, is used the MPU is concerned with the intensity profile of the receiver signal. As before the "reference" or "standard" is provided by the inter-band areas, and the profile of the signal is compared with the code contained in the ROM.

Fig. 12 is a semi-schematic circuit diagram of circuitry used to decode the coding information contained in a card of the general type of that in Figs. 1 and 2. An oscillator provides high intensity pulsed infra-red radiation via a series of infra-red emitting diodes (e.g. 4 to match the number of rows of coded information (infra-red opaque areas (or "holes" or "not" "holes" when the card's middle layer is infra-red impermeable with holes spatially arranged). The signal is approximately 400Hz in frequency. Each receiver ((4 off) photodiode or phototransistor) signal is amplified and passed to a phase-locked loop whose central frequency has been set to correspond to the frequency of the oscillator which is providing pulsed infra-red radiation via the emitters.In this way the receiver circuit is less susceptible to ambient infra-red levels because the phaselocked loop will present a logical "1" at its output only when the input signal (from the amplifier) is of a specific frequency (400Hz or greater).

The following is a detailed description of the decoding of information contained on the card, the middle layer of the card being infra-red permeable with a spatial disposition of infra-red opaque areas. The emitter-receiver-amplifier configuration is such that an infra-red opaque area passing between any emitter and its respective receiver will cause a logical "0" at the output of the phase locked loop corresponding to this emitter-receiver-amplifier configuration.

Switch A of Fig. 3 (contacts N/O normally open) has been closed by entry of the card in to the chamber depicted in Fig. 3, with the result that a flip-flop (not shown)-mediated debounced signal "enables" the oscillator- emitter and receiver-amplifier-phase-locked loop circuits. The coded section of the central layer has not yet passed between the emitters and receivers. As a result the output of each of the 4 phase-locked loop will be a logical "1".

Consequently the 4 inputs to the 4 input AND gate N7, namely A, B, C s D will each be at logic "1", resulting in an output from N7 which appears at Z. This signal is flip-flop (not shown) debounced and a positive is sent to point X, which a) removes the reset signal to the binary counter b) removes the reset signal to the decade counter c) removes the reset signal to the 4-bit latch d) removes the reset signal to the flip-flop FF e) "enables" the ROM (read only memory).

The circuit is thus essentially "in limbo", awaiting the arrival of the 1 st coded column of the card.

When the 1 st coded column passes between the emitters and the receivers, by previous definition, one or all of the outputs of phaselocked loops 1 to 4 will go low, i.e. each of A, B, C 8 D may be at logic "1" or "0" depending on the coding of the column. As a result T, U, V and W will, by action of inverters NI 1-N 14, be the complement of A, B, C 8 D and be presented to the 4-bit latch (essentially 4 separate latches joined by a common reset line) which will hold the information at E, F, G 8 H.

The following "elaborate" method ensures that the coded areas on the column need not be at exactly the same horizontal distance from the front of the card i.e. that the arrival of 1 or more coded areas displaced vertically at approximately the same distance from the front of the card will suffice.

Although E, F, C G & H now hold a 4 bit word (any except "(ii") this information can not be read until the infra-red radiation pulsed from each emitter is received (i.e. an inter-columnar area is passing between the emitters and receivers). This is achieved in the following manner.

When any block of infra-red radiation occurs the output of N7 will go low, the output of N9 will go high clocking the flip-flop FF sending Q high to one gate of (and gate) N1 0. In addition 0 of FF goes low, ensuring that AND gate N8 will not give a logical "1" at its output (to reset FF) even if N7 has a logical "1" at its output, when the intercolumnar region of the card passes between the emitters and receivers i.e. N7 goes high the signal is presented to the other gate of N10 resulting in the output of N10 going high, triggering a monostable which clocks the binary counter. It is after this point that the information of the recently passed column is read and compared to the ROM contents.

The ROM is a 4-bit device with at least 5 addresssable 4-bit words (one is a "system at rest 4-bit word namely "Q-the word itself is arbitrary excepting "1111", say "QWQ"", the other 4 (or more) 4-bit words will contain the code, in a modified form (see below)) These 4-bit words are accessed by means of the binary counter which will "page" each 4-bit word in sequential order as the counter is incremented, by means of 0$ to Q7. The code is stored in the ROM, as the complement of the information which should be presented at E, F, G & H during the correct entry of the code by means of the card.

This can be explained as follows. After the first column has passed between the emitters and receivers the absence of any block of infra-red radiation will cause an output from the monostable triggered by an output from Uni 0. This clocks the binary counter enabling location 1 of the ROM to be read. This data appears at I, J, K Et L. If this data is the complement of E, F, G 8 H the outputs from exclusive-OR gates N1-N4 will cause the output of 4 input AND gate N5 to go high, triggering a monostable which clocks a decade counter. The clock signal "carry out" from the decade counter resets FF (via N8) and the 4 bit latch. The system is now "primed" to accept the next piece of coded information. In our simple example 4 columns represent 4 code digits .'.Q4 of the decade counter will be resultant on 4 columns of coded areas having passed between the emitters and receivers, compared to the ROM contents and found to be the correct sequence of code digits, with the decade counter incremented at each occasion.

The system will not accept "$,$,$,$" or "1,1,1,1" (4-input AND gate N15 in this latter case will reset both the binary and decade counters) as code digits. Nor should the ROM contain any 4-bit words of "1,1,1,1".

The selected output from the decade counter (04 in the previous paragraph) can be used to enable an electrical steering lock to be unlocked, by means of a transistor-switched relay (N/O contacts) to reset the entire decoding circuit the power is removed from point X.

The use of the phase loop locked circuitry in the above design has the advantage of eliminating any possible erroneous readings due to the receiver(s) responding to ambient IR radiation.

Fig. 13 is a somewhat schematic view of a steering column lock in which a key card security device of the invention may be used. The lock comprises a bolt 71 which is shown engaged in a keeper 72 in the steering column 73. In order to retract the bolt 71 electrical power is supplied (under the direct or indirect control of a key card security device circuit of the invention) to an electromagnetic coil 74 surrounding the bolt 71 via suitable power and earth connections 75, 76 whereupon a head 77 provided at an end 78 of the bolt member 71 remote from the Keeper 72 is displaced, against the biasing force of a return spring 79, past a spring biased 80 latch member 81. The latch member 81 is arranged for reciprocal movement at right angles to the main bolt member 71 and engages the forward side 82 of said bolt head 77 to retain the bolt 71 in its retracted unlocked position. Retraction of the latch member 81 is effected with the aid of an electromagnet 83 controlled by a respective circuit 84 (not shown in detail) arranged to activate the electromagnet 83 upon withdrawal of the key card from the key card receiving cavity in the security device e.g. in the lock barrel.

Claims (19)

Claims

1. A coded-card key device having a plurality of infra-red radiation transmitting non-visible radiation-transmitting zones disposed in an individual spatial disposition combination selected from a larger number of different possible such combinations, in a body which is substantially non-infra-red radiation-transmitting, for transmission of infra-red radiation from one side to another side of opposed sides of the card.

2. A key device as claimed in claim 1, wherein said zones are arranged in a two-dimensional array of rows and columns.

3. A key device as claimed in claim 1 wherein said zones are disposed in a linear array.

4. A key device as claimed in claim 3 wherein the infra-red radiation transmitting zones comprise zones having at least two different infrared radiation transmission levels.

5. A key device as claimed in claim 4 wherein the infra-red radiation transmitting zones comprise zones of at least two different widths.

6. A key device as claimed in any one of claims 1 to 5 comprising at least one inner layer of substantially non-infra-red radiation transmitting material with a plurality of apertures therein providing said infra-red transmitting zones, and at least two outer layers of infra-red radiation transmitting no-visible radiation transmitting material.

7. A key device as claimed in claim 6 wherein the non-infra-red radiation transmitting material is a metal foil.

8. A key device as claimed in claim 6 or claim 7 wherein said at least two outer layers are of an infra-red radiation transmitting non-visible radiation transmitting plastics material.

9. A key device as claimed in any of claims 1 to 8 which is provided with a mechanical engagement means for engagement with a retaining means, in use of the device, so as to resist accidental withdrawal of the key device from a coded-card-key operated device.

10. A key device as claimed in claim 9 wherein the mechanical engagement means comprises at least one aperture and/or recess in the key device.

11. A coded-card key operated security device comprising a body having a card receiving cavity having opposed transmitting and receiving sides, said transmitting side being provided with infrared radiation transmitting means, and said receiving side being provided with infra-red detection means generally opposite said transmitting means for detecting infra-red radiation at at least one zone disposed so as to be successively traversed by a plurality of infra-red transmitting and non-infra-red transmitting zones in a said coded card in use of the device, said detection means being arranged in a security circuit for controlling a security switch means having unlocked and locked conditions so that reception of infra-red radiation by said means through a said coded-card having a correct individual combination of infra-red transmitting zones is necessary to transform said security switch means from its locked condition to its unlocked condition, and connection means for connecting said security circuit and infra-red transmitting means to an electrical power supply.

12. A security device as claimed in claim 11 wherein is provided a plurality of infra-red radiation detection means spaced apart transversely of the key card insertion axis of the card receiving cavity for detecting infra-red radiation transmitted through correspondingly transversely spaced apart infra-red transmitting zones in said card.

13. A security device as claimed in claim 11 or claim 12 wherein is provided an alarm means formed and arranged so as to be activated when an incorrectly coded key card is inserted into the security device.

14. A vehicle steering column lock having a bolt means arranged to be normally held in a locking position, for engagement with the steering column in use of the lock, said bolt means being retractable to an unlocked position by an electrically operated drive means controlled by a security device according to claim 11.

1 5. A steering column lock as claimed in claim 14 wherein said drive means comprises an electromagnet.

16. A steering column lock as claimed in claim 1 4 or claim 1 5 wherein is provided a latch means for retaining the bolt means in its unlocked position until positive disengagement of said latch means takes place.

1 7. A coded-card key device substantially as described hereinbefore with particular reference to Figs. 1 and 2, or Figs. 6 to 9.

1 8. A coded-card key operated security device substantially as described hereinbefore with particular reference to Figs. 3 to 5, Fig. 10, or Fig.

12 of the accompanying drawings.

19. A vehicle steering column lock substantially as described hereinbefore with particular reference to Fig. 1 3 and Figs. 3 to 5, Fig. 10, or Fig. 12 of the accompanying drawings.