GB2190700A - Security system with key - Google Patents

Abstract

A security system comprises a key with a strip 14 for insertion into a keyhole 9 and having a circuit 3 (e.g. on integrated circuit) for producing a characterising electrical signal, and a control unit 9 for testing the signal - if key and reference signals agree the state of a lock may be changed or identification at a pre-set position given. As shown, the key has contacts 4-6 and can draw power from power source 15 external to key via two of the contacts 4,5 when inserted in keyhole 9 to produce the characterising signal at another contact 6. Contacts 10-12 contactable with contacts 4-6 are metal balls mounted within bores provided in a barrel 8 provided with keyhole 9 and rotatable by the key. Conductive leads from contacts 10-12 are connected to rotating part of a switch 13. If key and reference signals agree a servo is operated - if they do not agree an alarm 18 is activated. <IMAGE>

Description

SPECIFICATION Security system with key This invention relates to security systems comprising keys that generate electrical signals which the system tests before it will allow access, switching, locking or unlocking as the case may be.

Key-operated security systems for e.g. motor vehicles, safes, buildings etc. are normally mechanical although there are of course many different varieties. While simple and familiarto operate, as mechanical devices they inevitably have certain manufacturing tolerances incorporated into their design and consequently after even a short period of use it may be found that one mechanical lock can be opened by a slightly worn key designed for a slightly different lock. Moreover the physical and mathematical limitations on the number of different combinations attainable with a conventional key style may mean that, allowing for wear, there may be onlytwenty orthirty substantially differing key types. Of course corresponding wear to the barrel or receptacle that receives the key makes the situation even worse.

To avoid these limitations of mechanical systems several types of electronic system have been proposed, and these have made a far greater range of clearly resolvable codes, formats and combinations available to the user. However there are drawbacks. One known system uses a key carrying a "bar-code" which can be read directly by the system, but the contents ofthese codes are liable to accidental erasure by electrical noise such as might well be met with in a car or an industrial environment. Another type of key generates its own characteristic electrical signal which is compared by the control system with a standard signal. In this casethe key itself is rathercumbersome, incorporating its own power source which tends to be unreliable.

Clearly it would be desirable to have a key-operated security system that avoids these problems ofthe known types while combining their virtues.

According to one aspect of the present invention a security system comprises a key having circuitry for producing a characterising electrical signal and a control unit having means fortesting the signal produced bythe key, wherein an interface for connecting the key electrically to the control unit comprises a keyhole and a signal contactthrough which signals may be fed to the control unit, and the key has a portion insertable in the keyhole and comprising a signal contact at which the produced signal is present and which is contactable with the signal contact ofthe interface when that portion of the key is inserted in the keyhole.

Preferably the interface comprises a rotatable barrel carrying the keyhole, which requires to be rotated from its rest position before signals are fed to the control unit from the signal contacts.

Thusthesystem may make availablethewide range of codes and signals available with electronic systems in combination with the familiar operating mode of an insertable key. The key itself may be made in a form similarto that of a conventional key for a mechanical lock, e.g. with a flat portion for insertion into the keyhole extending from a handle in the form of a flange, which itself may housethe signal producing circuitry of the key.

In another aspect the invention provides a security system comprising a key having circuitry for producing a characterising electrical signal and operable by contacting a signal contactofthe key with a signal contact of an interface to feed the signal to a control unitfortesting,wherein powerfor operating the signal-producing circuitry in the key is derived through respective contacts of the key and the interface from a power source that is not part of the key.

In this way the need for cumbersome and possible unreliable on-board power source in the key may be avoided. It is preferred that the key and interface are such that the key has a portion insertable in a keyhole of the interface, and in this case positive and ground contacts for connection to the power source may be provided spaced along the insertable portion ofthe key, corresponding contacts from the power source being provided in the keyhole.

Thus in a preferred aspect the invention provides a security system comprising: (1) a key device, preferably hand-held, capable of being put into or in contact with (2) an interfacethroughwhich it may receive power enabling it to transmit a preset signal, preferably of electronic type, through the interface to (3) a control unit which is within or connected to the interface and adapted to receive the signal and then analyse and compare it with a signal preset within the control unit. Then, if both the signals match in all respects, the control unit may for exampleoperate a slave circuitorcircuits controlling functions within a secured or securing element, while in the case of any unmatched signal it may activate an alarm or deterrent function.

In a further aspect the invention provides a key for such a security system, having a portion with a signal contact at which a characterising signal is produced by circuitrythat is part of the key, and which portion may be insertable in a keyhole of an interface such that the signal can be fed to a system control unit for testing, and/or provided with contactsforderiving power from an external power source via contacts on the interface with the control unit.

In a yet further aspect a combination of key and interface as defined above, e.g. with the interface comprising a rotatable barrel with a keyhole, is provided.

An embodiment ofthe invention will now be described by way of example, with reference to the accompanying drawings in which: Figure lisa perspective view of a partially disassembled key, and Figure2 is a schematic iilustration of the remainder of a security system for operation with the key of Figure 1, including a broken-away schematic perspective view of a keyhole-and-barrel interface assembiy.

Referring firstly to Figure 1,a key embodying one aspect of the invention the general overall shape and appearance of a key for a conventional normal mechanical lock, with a flat rigid elongate strip 14 of uniform rectangular cross-section for insertion in a keyhole, and a widerflange-shaped headformed from two detachable halves, 1,2 by which the key may be held and turned.

Spaced along both the upper and lowerflat surfaces ofthe strip 14 are three sets of rectangular electrical contact areas 4,5,6,4a,5a,6a - contacts 4a,5a and 6a are shown dotted as these are on the lower surface of the strip as shown. Thus the disposition ofthe contact areas on the upper and lower surfaces is identical. The key may be e.g. of reinforced plastics material with the contact areas being e.g. gold or nickel plated. The head 1,2 need not be in two halves, but may be e.g. injection moulded around the circuit 3.

Extending along the centre ofthe strip 14from each contact area to the head 1,2 of the key are respective conducting leads 19, and these connect two the appropriate terminals of a signal - producing circuit 3. The circuit may be an integrated circuit such as, for example, a LM567 phase-lock loop integrated circuit of known type which will provide a coded electrical signal e.g. a steady oscillation of predetermined amplitude and frequency when power is supplied to it. However other circuits may of course be used provided thattheycan provide a suitable characterising signal - a variety of other suitable circuits is already known for use in the field of electronic security systems.

In this embodiment the contact areas are connected to the circuit 3 in such a way that power supply (positive and ground) to the circuit is via contact areas 4 and 5 adjacentthe head 1,2 while the signal is produced atthe end contact area 6; of course the contact areas themselves are essentially similar and any ofthe others could be used forthe signal ratherthan the power supply. In this way the possible numberof "different" keys can be increased without needing even to alter the signal characteristic.

Referring now to Figure 2, apparatus to receive the key of Figure 1 comprises a cylindrical barrel 8generally similarto a conventional mechanical lock barrel - rotatably mounted in a cylindrical sleeve 7.

The barrel 8 be, for example, injection moulded in plastics. A keyhole 9, in the form of an axially elongate rectangular slot opens at one end ofthe barrel 8, and the inner conformation of the keyhole 9 substantially matches the exterior conformation of the insertable strip 14 of the key, so that when inserted the key can be used to rotate the barrel 8 in the manner that is familiar and therefore convenient to people accustomed to operating mechanical locks. Means (not shown) are provided to resiliently return the barrel Sto the rest position shown relative to the sleeve 7.

Spaced along one side of the upper inner surface ofthe keyhole 9 and projecting slightly into it are three sprung electrical contacts 10,11,12. These are disposed so as to make contact with the respective contacts 4,5,6 or4a,5a,6a on the key when this is inserted into the keyhole 9 (the disposition of the key contacts when inserted is shown in broken lines), and it will be seen that the identical disposition of contacts on each face of the key means that the latter will operate satisfactorily whichever way up it is inserted into the keyhole 9. In the illustrated embodiment the electrical contacts 10,11,12 are metal bails mounted on short springs within bores provided in the barrel 8.

For clarity the electrical switch connections from the interface contacts 10,11,12 are shown only schematically, since they may be by conventional switching means. In this case, conductive leads from the three contacts extend to the rear end of the barrel 8where they are connected to the rotating part (not shown) of a circular "wafer" switch 13 whose case is fixed to the rear of the sleeve 7. The switch 13 is set up such that a small initial rotation of the barrel 8 by the inserted key initiates supply of electric power from external power source 15 to both the circuit 3 in the key (by switched connection of the positive and ground contacts 10,11 on the key with the source 15) and also to the control unit 16.The control unit 16 contains a reference circuit, similarto that in the key, and a comparatorfor comparing a signal received from the key with that produced by the reference circuit. By supplying powerfirstto these circuits they are enabled to "warm-up" and stabilisetheirsignal output before furtherturning of the key connects the contacting signal contacts 6,12 of the key and interface by means of the wafer switch 13, to the control unit. The comparator of the control unit 16 then compares the key and reference signals and, if they agree exactly, actuates e.g. an electromechanical servo 17 which could be for changing the state of a lock. If the signals do not agree the comparator might be connected so as to activate an alarm 18 to show that an incorrect key was being used.The wafer switch 13 also provides for the signal from the key to be cut off after a predetermined time so as to make the signal more difficult to fake.

Thus in use the user inserts his key into the barrel, which produces no response; turning the key from its rest position in a specified direction power is supplied to the key circuitry and the signal released to the control unitwhich examines itand if it isthe correct signal executes an appropriate response.

Because ofthe versatility of e.g. wafer-type switches a single key and barrel combination could be used to control several switching actions. For example in a motor vehicle ignition systems the key could operate accessory, ignition and starter facilities at various stagesthroughthearctoturn by means of an appropriate type of wafer switch operated by the barrel.

Several potential advantages of the described system will be apparent. For example, the key and barrel need not be affected by wear and tear to the same degree as a conventional mechanical lock, and any wear which does occur does not affect the resolution achieved by the control unit orthe signal code in the key.

The barrel need not be linked mechanically to a lock and so anyone attempting to operate that lock by turning the whole barrel will not gain access.

The system allows simplicity of use in an orthodox and convenient manner, coupled with the advantage of the range of combinations availablewith electronic circuits.

The system need not rely on the key having its own internal power source, thus eliminating an inherent weak point of many of the purely electronic systems currently available.

The system may be adapted for use in applications which have a requirementforvarious levels of access e.g. in the computing industry which wishes to give differing levels of access to different users.

Another possible application is to control and monitorthe security of e.g. a factory or bankvault, giving a patrol man a set indentication at pre-set positions throughout the building.

By appropriate choise of circuitrythe system may only operate iftwo different keys are used, one after theotherwithin a predetermined period.

The barrel element could be a direct replacement for an existing mechanical lock barrel, the key a direct replacement for an existing mechanical key.

Becausethesystem may be adapted to fulfil several functions at once or individually, this can be useful in that one unit may be used to replace one or more conventional types of mechanical device.

Claims (19)

1. A security system comprising a key having ci rcuitry for producing a characterising electrical signal and a control unit having means for testing the signal produced bythe key, wherein an interface for connecting the key electrically to the control unit comprises a keyhole and a signal contact for connection to the control unit, and the key has a portion insertable in the keyhole comprising a signal contact at which the signal is produced and which is contactable with the signal contact of the interface when that portion of the key is inserted in the keyhole.

2. A system according to claim 1 wherein the interface comprises a barrel in which the keyhole is provided and which is rotatable by the key when inserted to connectthe signal contacts to the control unit.

3. A system according to claim 2 wherein the interface includes a switch operable by rotation of the barrel to connect the signal contacts to the control unit.

4. Asystem according to claim 2orclaim3 wherein the interface includes a switch operable by rotation of the barrel with the key to connect at least one of the control unit and the key circuitryto a power source.

5. A system according to claim 3 and claim 4 wherein during rotation ofthe barrel the switch operates to connect the power source before the signal contacts are connected to the control unit.

6. A system according to any preceding claim wherein electrical power for operating the signal-producing circuitry in the key is derived through respective power-supply contacts of the key andtheinterfacefrom a powersourceoutsidethe key.

7. A system according to claim 6 wherein the key signal and power-supply contacts are separate contacts spaced along the insertable portion ofthe key in its direction of insertion.

8. A system according to claim 7 wherein the insertable portion of the key has at least one signal contact and at least one power-supply contact.

9. A system according to any preceding claim wherein the portion of the key insertable in the keyhole is a substantially flat strip with substantially flush metailic areas defining the or each contact.

10. Asystem according to claim 9 wherein each face ofthe flat strip has an identical disposition of contactswherebythe key maybe inserted and operated either way up in the keyhole.

11. A system according to any preceding claim wherein the key has a handle-forming fiange in which the signal-producing circuitry is housed.

12. A security system comprising a key having circuitry for producing a characterising electrical signal and operable by contacting a signal contact of the key with a signal contact of an interface to feed the signal to a control u nit fortesting, wherein power for operating the signal-producing circuitry in the key is derived through respective contacts ofthe key and the interface from a power source that is not part ofthe key.

13. Asystem according to claim 12 wherein the interface comprises a keyhole and the key has a portion carrying said signal contact that is insertable in the keyhole such that the respective signal contacts of key and interface are contactable.

14. Asystem according to any preceding claim wherein the control unit is adapted to test the electrical signal from the key by comparing it with an electrical signal produced bythecontrol unit and actuate a function-controlling slave system only if the signals match.

15. A system according to claim 14 wherein the control unit actuates an alarm ifthe signals do not match.

16. A key for for a security system according to any one ofthe preceding claims.

17. In combination, a key and interfacefora security system according to any one of the preceding claims.

18. A security system substantially as herein described with reference to and as shown in the drawings.

19. A key for a security system, substantially as herein described with reference to and as shown in Figure 1 of the drawings.