Key-operated locking device

Abstract

 Key-operated locking device e.g. for electrically actuated vehicle door locks in which only the correctly cut key (21) will displace a row of tumblers or wards (22) to bring apertures (26) therein into alignment. A light emitter (16) emits a light beam through the apertures as the key is inserted and if alignment is correct the beam is sensed by light responsive sensor (17) to generate a signal applied in a control circuit to release the door lock and/or operate other equipment.

Description

[0001] This invention relates to key-operated locking devices of the kind which include a housing containing a plurality of spring-loaded tumblers, the housing being formed with a key slot into which a key can be inserted for engagement with the tumblers such that insertion of the correct key into the slot causes the tumblers to be moved into the appropriate positions for operation of the device whereas insertion of anything other than the correct key does not effect the required movements of the tumblers. A device of the above kind is hereinafter referred to for convenience as a lbcking device of the kind specified.

[0002] In conventional locking devices of the kind specified, the tumblers are housed within a rotatable cylinder with the arrangement such that the tumblers project from the cylinder for engagement with the side walls of channels formed in the housing to prevent rotation of the cylinder unless the correct key has been inserted. Such devices have, however, two main limitations. The first is that they can be picked by an expert lock-picker. The second is that they can be forced using a metal blade inserted into the key slot and a torque wrench to rotate the blade and effect shearing of the ends of the tumblers.

[0003] Thus, although existing locking devices of the kind specified are cost-effective and are extremely widely employed in, for example, the autonotive industry, the degree of security which they afford is somewhat limited. It is accordingly an object of the present invention to provide a locking device of the kind specified which is resistant to both picking and forcing and thus affords a higher degree of security than existing devices.

[0004] According to the invention there is provided a locking device of the kind specified in which the tumblers are formed with apertures arranged so that they are in alignment only when a correct key is inserted, and in which light transmitter and receiver means are provided for sensing when the apertures are in alignment and for generating an appropriate signal.

[0005] The light transmitter and receiver means may comprise an infra-red emitter and an infra-red sensor with switch means arranged for actuation by an inserted key to cause operation of the emitter. The tumblers are preferably arranged in a row with the emitter positioned at one end of the row and the sensor arranged at the other end of the row. Thus, when the correct key is inserted, the tumblers are moved- into positions in which the apertures are aligned to permit the uninterrupted passage of an infra-red beam from the emitter to the sensor. On the other hand, if the switch means has been actuated by insertion of something other'than a correct key, the beam will be interrupted by one or more of the tumblers.

[0006] In an alternative arrangement, the emitter and the sensor are located at the same end of the row of tumblers and the transmitter is arranged to emit a directional beam through the apertures when in alignment, the beam then being reflected by a reflector which is so positioned at the other end of the row of tumblers that the beam is directed on to the sensor.

[0007] The apertures in the tumblers are preferably of elongate rectangular form with the dimension of each aperture in the direction of tumbler movement substantially less than the dimension of the aperture transversely of the tumbler. The dimension of the aperture in the direction of tumbler movement is preferably of the order of half the difference in the heights of the different cuts of the key.

[0008] The switch means for actuating the infra-red emitter may be located at the innermost end of the key insertion slot so as to be operated by the tip of an inserted key. Alternatively, the switch means may be positioned at the side of the key insertion slot such that it is engaged by the key as the key approaches the fully inserted condition.

[0009] The infra-red sensor is preferably connected to a master control circuit remote from the device. In order to simplify assembly of the device the printed circuit board may provide the mountings for not only the infra-red emitter and sensor, but also for the key-actuated switch means.

[0010] As a further feature which assists in simplification of the device, the housing may comprise two plastic mouldings one of which is in the form of a ribbed spine which defines the key insertion slot, and the other of which is in the form of an outer body defining the outer walls of the tumbler compartments and providing mountings for the infra-red transmitter and sensor.

[0011] The invention will now be described by way of example with reference to the accompanying drawings which illustrate a car locking device and in which:-

Figure 1 is a vertical longitudinal sectional view of a key-operated device showing the key in position,

Figure 2 is a transverse sectional view of the device, and

Figure 3 is a horizontal sectional view of the device.

[0012] The device shown in the drawings is intended to be installed tn the B post of a motor vehicle and includes a moulded plastics body 10 which has a pair of apertured lugs 11 whereby the device can be mounted by suitable fasteners on a mounting element within the B post. The device housing comprises, in addition to the body 10, a cover 12 which is also formed as a plastics moulding and has a snap-fit connection with the body. To this end, the cover 12 is formed with two pairs of tongue formation 13 which terminate in inwardly directed wedge formation which engage in appropriately positioned apertures in the body 10.

[0013] The cover 12 contains a prtnted circuit board 14 which is located slidably within the cover 12 by engagement of its edges in inwardly facing channels in the side walls of the cover. The printed circuit board 14 carries the electrical componentry of the device and these include a disc-type actuating switch 15, an infra-red emitter 16 and a photo-transistor 17.

[0014] The device housing includes a third moulded plastics component in the form of a spine 18 which includes a portion 19 which provides a key insertion slot and a portion 20 which provides a downwardly facing datum surface engaged by the upper edge of an inserted key 21 so that, as the key 21 is inserted, it is guided throughout its range of movement at the end of which the tip of the key 21 engages the switch 15 to actuate the infra-red emittor 16 for a controlled period as determined by a timing circuit of a master control circuit remote from the device.

[0015] Formations of the main body 10 define a plurality of compartments in which moulded plastic wards 22 are located. In the particular embodiment illustrated there are eight wards 22 acted upon individually by helical ward springs 23, The ward springs 23 surround pins projecting from the lower edges of the wards and are located in pockets formed in the lower wall of the body 10, the body 10 and spine 18 being attached to each other by rivets 24.

[0016] Each ward 22 is of generally rectangular configuration and is formed with a central rectangular aperture 25 through which the key blade is passed. The key can be either a single-entry key or a double-entry key. If a single entry key, the upper edge surface thereof will be straight and the different cuts will be in the lower edge of the key 21. If the key.21 is a double-entry key, the portion thereof immediately adjacent the tip of the key will extend for the full key height so as to provide firm guidance for the key during its insertion.

[0017] The apertures 25 in the different wards 22 are all of the same dimensions and positions, the wards 22 differing from one another in the disposition of an aperture 26 formed in the upper portion of the ward. As indicated in Figure 2 there are three different possible positions for the aperture 26 and there will be three cut conditions for the or each cut edge of the key. As indicated in Figure 1, the infra-red emittor 16 and the photo transistor 17 are so arranged that a straight-line beam 27 from the emittor 16 will, assuming there are no obstructions between the emittor 16 and the photo transistor 17, cause the generation of an output signal by the phototransistor 17. This output signal generated by the phototransistor 17 is received by the master control circuit and is effective to cause the application of an output signal of predetermined duration to, for example, electric motors contained in the vehicle door latches, electric actuators for the door latches or other electrical actuators or motors of the vehicle.

[0018] Because of the different positions of the apertures 26 in the wards 22, the beam 27 will only be uninterrupted when the correct key has been inserted and the wards 22 have been displaced against the actions of the ward springs 23 to bring the apertures 26 into alignment. When any other key is inserted, the switch 15 will be operated to actuate the emitter 16 for a predetermined period as controlled by the timing circuitry on the printed circuit board 14 but no output signal will be generated since some at least of the wards will be positioned to interrupt the beam 21.

[0019] It will not be possible to pick the lock since no indication is given of the correct positions of the wards, as is the case in respect of a rotatable tumbler device. Neither will it be possible to force the lock by inserting a blade into the key slot and applying a torque to the blade.

[0020] In order to prevent the entry of dust and dirt into the key entry slot, the portion 19 of spine 18 includes a mounting for a rotary shutter 28 which is acted upon by a helical spring 29. The shutter 28 includes a quadrant-shaped closure member which is normally acted on by the spring loading to be biassed into a position in which it closes the key entry slot whereas, when the key is inserted, the closure member is displaced and free key entry is permitted.

[0021] One of the concerns which a number of vehicle manufacturers have expressed concerning the use of electrical locking systems, is that unless a mechanical release system is provided, there is a danger that, if the vehicle battery becomes flat or the battery leads are disconnected, the motorist will be locked out of his vehicle. Of course, if a back-up mechanical system is provided, this can be picked or forced and no increased level of security is provided by the use of the high security device of the Invention. The device can accordingly include a mounting for an auxiliary power input 30 which is carried by the cover 12. A small round aperture is formed in the B-post panel and a removable access plug 31, which fits over the power input 30, enters this aperture. In the event of a failure of the vehicle battery, a power supply can be applied to the input 30 to operate the device and to operate the vehicle door latch motor or _Qther item controlled by the device.

Claims

1. A locking device of the kind specified wherein the tumblers are formed with apertures arranged so that they are in alignment only when a correct key is inserted, the device including light transmitting means and light receiving means for sensing whether the apertures are in alignment and for generating a signal in response to alignment thereof.

2. A device as in Claim 1 wherein the transmitting and receiving means comprise an infra-red emitter and an infra-red sensor respectively.

3. A device as in Claim 1 or 2 wherein the transmitting means is located at one end of a row of the tumblers and the receiving means is located at the other end.

4. A device as in Claim 1 or 2 including a reflector located at one end of a row of the tumblers, the transmitting and receiving means both being located at the other end of the row whereby a Fight beam emitted by the transmitting means will be reflected back to the receiving means if the tumblers are in alignment.

5. A device as in any preceding claim including switch means for actuation by an inserted key to cause operation of the transmitting means.

6. A device as in Claim 5 wherein the switch means is located at the inner end of the key slot so as to be actuated by the tip of the inserted key.

7. A device as in Claim 5 wherein the switch means is located at the side of the key slot so as to be actuated by the key as the latter approaches a fully inserted position.

8. A device as in any preceding claim including timing means energising the light transmitting means for a predetermined period on insertion of the key.

9. A device as in any preceding claim wherein the tumblers are of elongate rectangular form and a first dimension of each aperture in the direction of tumbler movement is substantially less than a second dimension thereof transversely of said direction.

10. A device as in Claim 9 wherein the first dimension is substantially half the difference in height of different cuts of the key.

11. A device as in any preceding claim including a printed circuit board mounting the light transmitting and receiving means.

12. A device as in any preceding claim including a control circuit operable in response to said signal for actuating electrically powered equipment in use.

13. A device as in any preceding claim including a housing comprising first and second parts, one of which defines a slot into which the key is inserted and the other of which defines locations for the tumblers and mounts the transmitting and receiving means.

14. A device as in any preceding claim including an auxiliary power input accessible where the key can be inserted for connection to an auxiliary power source to energise the light transmitting means.

15. A motor vehicle door locking system including a device as in any preceding claim.

16. A motor vehicle including a device or a locking system as in any preceding claim.

Drawing