GB2195141A

GB2195141A - A device for protecting a key- hole of a lock for a closure member

Info

Publication number: GB2195141A
Application number: GB08622719A
Authority: GB
Inventors: Eric Cooper; Anthony George Payne
Original assignee: Thorn EMI Protech Ltd
Current assignee: Thorn Security Ltd
Priority date: 1986-09-20
Filing date: 1986-09-20
Publication date: 1988-03-30
Anticipated expiration: 2006-09-20
Also published as: GB2195141B; GB8622719D0

Abstract

The closure member, for example, a door of a safe or other security enclosure or a drawer of a desk is protected by an alarm system against unauthorized opening; the device 1 has a shutter 9 displaceable between a down position to cover the keyhole 2 and a raised position and a stop member 11 abuts against shutter 9 to retain it in down position. The stop member 11 is retractable by a solenoid 13 which however can only be activated by a switch 15 whilst the closure member alarm system is disenabled-this prevents false alarms. Shutter 9 is slidable in a runner 10 in wall 3 of a U-shaped part of a casing and is retained in the raised position by a knob 19 locatable in a hole 20. A microswitch 18 is positioned adjacent shutter 9 to cause an alarm to sound if shutter 9 is forcefully pushed upwards. <IMAGE>

Description

SPECIFICATION A device for protecting a key-hole This invention relates to a device for protecting a key-hole of a lock for a closure member, such as a door or drawer, and, in particular, wherein the opening of the closure member is detectable by an alarm system.

Key-hole protectors for door locks are generally used for, for example, safes or other security enclosures, and may comprise a shutter mechanism which inhibits unauthorised access to the key-hole of the lock.

It is also common practice, in these situations, to employ an alarm system for detecting unauthorised opening of the door lock, in addition to the key-hole protector.

Whilst such an alarm is generally intended to detect unauthorised opening of the door, false alarms can be caused by authorised opening of the door, via authorised actuation of the key-hole protector.

It is therefore an object of the present invention to provide a device for protecting a key-hole of a lock for a closure member, which device substantially alleviates the problem of false alarms caused by authorised opening of the closure member.

Accordingly, the present invention provides a device for protecting a key-hole of a lock for a closure member, wherein opening of the closure member is detectable by an alarm system, said device including a shutter displaceable between a first position for covering said key-hole and a second position for permitting access to said key-hole, and means for inhibiting displacement of the shutter from said first position to said second position until said alarm system is disenabled.

Preferably, the inhibiting means comprises a stop member, which abuts against the shutter and is controlled by a solenoid, the solenoid being actuable to retract the stop member from the abutment position to permit displacement of the shutter only whilst the alarm system is disenabled.

The present device therefore inhibits authorised access to the key-hole, and thus to opening of the closure member, prior to the alarm system being disenabled, thereby alleviating the risk of false alarms.

The invention will now be further described by way of example only with reference to the accompanying drawings, wherein: Figure 1 shows schematically a plan view of the interior of a device, in accordance with the present invention, with the shutter in the first position, Figure 2 shows schematically the device, as shown in Fig. 1, with the shutter in the second position, and Figure 3 shows schematically an end view in the direction A of the device as shown in Fig. 1 or 2.

Fig. 1 shows a device 1 for protecting a key-hole 2 of a lock (not shown) of a closure member, for example, a door of a safe or other security enclosure (also not shown) or a drawer, for example, of a desk. A casing of the device 1 comprises a U-shaped part 2, forming rear wall 3 and side walls 4, 5, and two end pieces 6, 7 secured to part 2 by screws 8.

A shutter 9, preferably made from steel, is slidable in a runner 10 in the rear wall 3 and, in the position shown in Fig. 1, the shutter projects through the end piece 7 to cover the key-hole 2.

The shutter 9 is securely retained in this down position by a stop member 11, which abuts against a raised portion 12 of the shutter 9. The stop member 11 is controlled by a solenoid 13, which is secured to the side wall 5 by a nut 14 and is electrically connected to a switch 15 by wires 16, 17.

A microswitch 18 is positioned adjacent the shutter 9, so that it is activated to cause an alarm to sound whenever the shutter 9 is forcefully pushed upwards in an attempt to gain unauthorised access to the key-hole 2.

Referring now also to Fig. 2, activation of the solenoid 13 effects retraction of the stop member 11 to the position shown in Fig. 2, so that the shutter 9 can be pushed upwards into the casing to permit authorised access to the key-hole 2.

To retain the shutter 9 in this up position, a knob 19 protruding from the side wall 4 is pushed inwardly from an extended position shown in Fig. 1 to locate in a hole 20 in the side of the shutter 9.

The shutter 9 is returned to the down position, as in Fig. 1, to cover the key-hole 2 by pulling out the knob 19 from the hole 20 and allowing the shutter 9 to slide under gravity over the key-hole. The stop member 11 then returns under the action of spring 21 to the abutment position in Fig. 1, to retain securely the shutter 9 in its down position.

Fig. 3 shows an end view of the device 1, revealing aperture 22 in end piece 7, through which the shutter 9 slides.

The closure member, (not shown), of which the key-hole 2 is a part, is generally protected by an alarm system (not shown) against unauthorised opening. However, false alarms could occur by authorised opening of the closure member, via actuation of the device 1, to gain access to the key-hole 2, whilst the alarm system is enabled.

To inhibit the occurrence of such false alarms, the solenoid 13 can only be activated by the switch 15, to retract the stop member 11 from its position in Fig. 1, whilst the alarm system is disenabled. In this way, authorised access to the key-hole 2, and thus to open the closure member, is only possible after the alarm system has been disenabled, thereby preventing a false alarm. The device, when in use, is provided with a top cover (not shown) having a push-button (also not shown), which effects activation of the switch 15. The cover is secured to the device by conventional tamper-proof mechanisms, and the device is similarly secured to the closure member (not shown) and also connected to an alarm to detect forceful removal of the device from the closure member.

Claims

1. A device for protecting a key-hole of a lock for a closure member, wherein opening of the closure member is detectable by an alarm system, said device including a shutter displaceable between a first position for covering said key-hole and a second position for permitting access to said key-hole, and means for inhibiting displacement of the shutter from said first position to said second position until said alarm system is disenabled.

2. A device as claimed in Claim 1 wherein said inhibiting means comprises a stop member, which abuts against the shutter, and a solenoid actuable to retract the stop member from the abutment position to permit said displacement only whilst the alarm system is disenabled.

3. A device as claimed in Claim 1 or 2 and including switching means actuable to sound an alarm when the shutter is forcefully displaced to said second position to gain unauthorised access to said key-hole.

4. A device as claimed in any preceding claim wherein said shutter is displaceable under gravity from said second position to said first position.

5. A device as claimed in any preceding claim and including means for retaining said shutter in said second position.

6. A device for protecting a key-hole of a lock for a closure member, said device being substantially as herein described with reference to the accompanying drawings.

CLAIMS Amendments to the claims have been filed, and have the following effect: Claims 1 and 3 above have been deleted or textually amended.

New or textually amended claims have been filed as follows: Claims 4-6 above have been re-numbered as 3-5 and their appendancies corrected.

1. A device for protecting a key-hole of a lock for a closure member, wherein opening of the closure member is detectable by an alarm system, said device including a shutter displaceable between a first position for covering said key-hole and a second position for permitting access to said key-hole, means for inhibiting displacement of the shutter from said first position to said second position until said alarm system is disenabled, and switching means actuable to sound an alarm when the shutter is forcefully displaced to said second position to gain unauthorised access to said key-hole.