WO1981002178A1

WO1981002178A1 - Device for burglary alarm protected doors

Info

Publication number: WO1981002178A1
Application number: PCT/SE1981/000011
Authority: WO
Inventors: B Eriksson; K Karlsson
Original assignee: B Eriksson; K Karlsson
Priority date: 1980-01-24
Filing date: 1981-01-19
Publication date: 1981-08-06
Also published as: GB2089082A; SE8000582L; SE419879B; EP0053111A1; GB2089082B; NO152463C; NO152463B; NO813172L

Abstract

A device intended to be used to prevent unintentional triggering of an alarm system when unlocking a door to premises protected by a burglary alarm system, including a movable slide (4) located adjacent to the outer surface of the door (2), arranged to take up a position extending over a keyhole (10) in the door by means of tension applied from a spring member (9), and which by means of a locking member (6, 7), influenced by an electromagnet (8) connected to the alarm circuit, is locked in a position extending over the keyhole (10) when the alarm system is operational, said slide (4) being manually removable from the position extending over the keyhole (10) when the connecting conditions of the electromagnet (8) is altered in connection with disconnection of the alarm system. By utilising a time delay relay, or an electronical time delay circuit, connected between the electromagnet (8) and the alarm circuit, the state of the electromagnet (8) can be altered after a predetermined interval of time as from the moment the alarm system is disconnected, thereby again locking the slide (4) in the position extending over the keyhole (10), in order to prevent insertion of alien objects into the keyhole (10) when the alarm system is not in operation.

Description

Device for burglary alarm protected doors

The present invention relates to a device for burglary alarm protected doors, intended to prohibit unintentional triggering of the alarm.

In premises protected by buglary alarm systems, there are a large number of unintentional alarm triggerings, due to the fact that persons authorised to enter the protected premises often forget to disconnect the alarm circuit, before entering locked areas, protected by the alarm system. In order to reduce the risk for such unintended triggering of the alarm system, a warning device has previously been disclosed in US-PS 3,645,249, comprising a device mounted to the inside surface of a door, including a pivotable member engaged with the locking mechanism of the door. When the locking mechanism is arranged in a locked position, said member takes up a position in which an electrical switching means is actuated, whereby a lamp, extending from the device through a hole in the door communicating with the outside surface, is lit. The object of this device is thus to accomplish optical indication at the outer surface of the door of the fact that the locking mechanism is arranged in locked position (when the lamp^"is lit), and also to indicate when the locking mechanism is unlocked (when the lamp is switched off). However, such a warning device is not intended to be used in connection with an alarm system, but only to accomplish visual indication at the outer surface of a door with regard to whether the locking mechanism is arranged locked or unlocked.

The object of the present invention is to disclose an extremely simple device, arranged to faciliate use in connection with existing types of locks, arranged connected to an alarm circuit for the door, and prohibiting unintentional unlocking of the door, when the alarm circuit is in operation. The device according to the present invention also faciliates, according to a slightly modified embodiment, protection against insertion of alien objects into the keyhole of locking mechanism arranged in a door protected by an alarm system also during the time when the alarm circuit is not in operation. Unauthorised persons are thus prevented from inserting alien objects into the keyhole and thereby obstructing the function of the lock. The device according to the present is further extremely simple and reliable, and can be attached simply and in a minimum of time to all existing types of doors and loch mechanisms.

y^y^ An embodiment of a device according to the present invention is more fully described below with reference to the accompanying drawing.

Fig. 1 is a plan view of a portion of an outside door surface with a device according to the present invention arranged to protect the keyhole to the lock mechanism of the door.

Fig. 2 is a view corresponding to Fig. 1, showing the device according to the present invention in a position faciliating insertion of a key related to the lock mechanism of the door.

Fig. 3 is a plan view of an embodiment of a device according to the present invention with a protective surrounding housing removed.

Fig. 4 is a side view of the embodiment shown in Fig. 3, viewed in the direction indicated by IV - IV.

With reference to the embodiment shown in Figs. 3 and 4, it include a base plate 1, arranged attachable to the outside surface of a door 2 b means of screws or similar. A surrounding housing 3, indicated by broken lines in Fig. 4, is also arranged attachable against the base plate 1. A the surface of the base plate 1 directed from the outside surface of the the door 2, a slide 4 is ovably arranged, having at one end portion a., part 5 directed from the -surface of the door.2. :The slide 4 is further arranged with a from the base plate 1 directed abutment member 6, agains which a co-acting and longitudinally extending locking member 7 is arran to take up contact with one end portion. Said locking member 7 is at the opposed end portion pivotably attached adjacent to an electromagnet 8, which electromagnet 8 is attached against the base plate 1. Furthermore, a spring member 9 is arranged to impose a force to the slide 4, arranged to move the slide 4 in such a direction, that the part 5 of the slide 4 directed from the surface of the door 2 takes up an adjacent position to the housing 3.

The above described embodiment of a device according to the present invention is attached as described against the surface of a door 2 adjacent to a keyhole 10 related to a locking mechanism in the door in such a way, that the slide 4, when it is in a position protruding from from the housing 3, covers the said keyhole 10, i.e. as shown in Fig. 1. The electromagnet 8 is electrically connected to existing burglary alarm system in such a way, that the electromagnet 8 is supplied electrical voltage when the alarm system is disconnected and not in function. When the alarm system is switched on, no voltage is supplied to the electro¬ magnet 8, whereby the the parts of the device take up the position shown

C

(y- \. in full lines in Fig. 3, i.e. the free end portion of the locking member 7 takes up a contact position with the abutment member 6, whereby the slide 4 is locked in a position protruding over and protecting the keyhole 10. When a door arranged with a device according to the present invention should be opened, a manual force is applied against the part 5 directed from the surface of the door 2, intended to move the slide 4 from the keyhole 10, and thus faciliate insertion of a key. Provided that the alarm circuit is disconnected, and thus there is no voltage supplied to the electromagnet 8, the locking member is located in the position shown by broken lines in Fig. 3, whereby the slide 4 can be moved from the keyhole 10 as desired.

However, if the alarm circuit is not disconnected, the keyhole 10 is protected by the slide 4 protruding from the housing 3, and said protruding part can not be manually moved to a position uncovering the keyhole 10, since the free end portion of the locking member 7 is in contact with the abutment member 6 on the slide 4. Accordingly, a person attempting to unlock the locking mechanism of the door is thus informed of the fact that the alarm system is not disconnected, and that it must be disconnected, before opening the door.

The spring member 9 always forces the slide 4 to take up a position adjacent to the housing 3, in which the part 5 directed from the surface of the door 2 is located in a position adjacent to the housing 3. As a result, the slide 4 will always, unless manually influenced when a key is about to be inserted into the locking mechanism of the door, protrude over the keyhole 10.

This makes it possible, according to a slightly modified embodiment, to use the device to prevent insertion of alien objects into the keyhole 10, when the alarm circuit is disconnected. Such a protection is achieved by connecting a time relay into the the electrical feeding circuit for the electromagnet 8, which only faciliates voltage feeding to the electro¬ magnet 8 during a restricted period of time as from the period of time when the alarm circuit is disconnected, whereby it is possible to unlock the lock mechanism of the door during said period of time, whereafter the slide 4 is locked in a position protecting the keyhole 10.

It should be emphasized, that the device according to the present invention only is intended to serve as a safety device intended to eliminate the risk for false alarms, caused by the opening of doors protected by an alarm system, and during the time when said alarm system is in operation. Accordingly, the device according to the present invent is not intended as a substitute for conventional alarm switches arranged by the door, even though the device according to the present invention can be regarded as a burglary preventive means in a restricted sense. Furthermore, it should also be emphasized, that the embodiment shown and described only is intended to serve as an example of an embodiment within the scope of the inventive thought, since obviously many modifications are possible with regard to mechanical design and utilized spring and locking members, and it could also be modified for use in connection with special types of doors and for specific purposes. It should also be mentioned, that the electromagnet 8 obviously can be arranged to operate in a reversed manner, i.e. voltage can be fed to the electromagnet 8 either to lock the slide 4 in a position protruding over a keyhole 10, or to unlock a locked position, taken up by means of a spring force acting against the locking member 7.

C.

Claims

C L A I M S

1. Device for burglary alarm protected doors intended to prevent unintentional unlocking of the locking mechanism of a door when the alarm circuit is in operation, characterised in that it includes a slideably movable slide (4) located adjacent to the outside surface of a door (2), at a first position extending over a keyhole (10) related to a lock mechanism arranged in the door, and in a second position not obstructing said keyhole (10), an electromagnet (8) being arranged connected to the alarm circuit, arranged to influence a locking member (6, 7) when the alarm circuit is in operation in such a way, that the slide (4) is locked in a position extending over the keyhole (10), and when the alarm circuit is disconnected.influence the locking member (6, 7) in such a way, that the slide (4) can be manually moved from the locked position to a position in which the keyhole (10) is unobstructed, thus faciliating insertion of a key related to the lock mechanism.

2. Device according to claim 1, characterised in that a spring member (9) is arranged to move the slide (4) to a position covering the keyhole

(10), when the slide (4) is not manually influenced.

3. Device according to claim 1 or 2, characterised in that the locking member comprises of an abutment member (6) arranged at the slide (4), co-acting with a locking member (7), which by means of the magnetic field from the electromagnet (8) when a voltage is supplied, or dis¬ connected, lock the slide (4) when the alarm system is in operation.

4. Device according to any of claims 1 - 3, characterised in that the locking member (6, 7) is arranged to lock the slide (4) in a position protecting the keyhole (10) when a voltage is supplied to the electro¬ magnet (10) .

5. Device according to any of claims 1 - 3, characterised in that the locking member (6, 7) is arranged to lock the slide (4) in a position protecting the keyhole (10) when no voltage is supplied^'to the electro¬ magnet (10) . 5. Device according to any of claims 1 - 5, characterised in that the locking member (6, 7) is arranged to take up an opposed position in relation to the position taken up by the magnetic field from the electromagnet (8) by means of the force applied from a spring member.

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7. Device according to any of claims 1 - 6, characterised in that the slide (4) is arranged with a part (5) extending from the surface of the door (2) at the end portion opposed to the portion covering the key hole, arranged to faciliate application of a manual force for 0 moving the slide (4) in direction from the keyhole (10).

8. Device according to any of claims 1 - 7, characterised in that it includes a base plate (1), attachable against the outer surface of a door by means of screws or similar, said base plate (1) being arranged 5 to serve as attachment member for parts included in the device, and also as a distance member, causing the slide (4) to be located at a predetermined distance from the outer surface of the door (2).

9. Device according to claim 1, 2, 3, 4, 6, 7 or 8, characterised in 0 that a time delay relay, or an electronical time delay circuit, is arranged in the voltage feeding circuit for the electromagnet (8), and that said relay or circuit is arranged to re-establish the voltage fed to the electromagnet (8) after a predetermined interval of time from the moment when the alarm circuit is disconnected, and thereby, even 5 though the alarm circuit is not in operation, lock the slide (4) in a position extending over the keyhole (10).

10. Device according to claim 1, 2, 3, 5, 6, 7 or 8, characterised in that a time delay relay, or an electronical time delay circuit, is 0 arranged in the voltage feeding circuit for the electromagnet (8), and that said relay or circuit is arranged to interrupt the voltage fed to the electromagnet (8) after a predetermined interval of time from the moment when the alarm circuit is disconnected, and thereby, even though the alarm circuit is not in operation, lock the slide (4) in a 5 position extending over the keyhole (10).