GB2336624A

GB2336624A - Warning device for key operated locks

Info

Publication number: GB2336624A
Application number: GB9808893A
Authority: GB
Inventors: Richard Manning; William Hill
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-04-25
Filing date: 1998-04-25
Publication date: 1999-10-27
Anticipated expiration: 2018-04-25
Also published as: GB9808893D0; GB2336624B

Abstract

A lock assembly comprising: i. a lock openable by a key 17; ii. a moving member 11 urged towards a rest position by a resilient biasing means the moving member being displaced from the rest position by insertion of the key in the lock; iii. a proximity detector for detecting magnetic fields for detecting whether the moving member is in the rest position; and iv. an alarm activated when the proximity detector detects the moving member is displaced from the rest position.

Description

1 2336624 WARNING DEP7CE FOR KEY OPERA TED LOCKS

Field of the Invention

This invention relates to warnmig device for key operated locks. By s way of non-limiting example the invention relates to alarms for signaling whether a key has been accidentally left in the key-hole of a house door. It will however be apparent to those skilled in the art that the invention is not so limited. The invention has application Mi other areas for example safe doors or vehicle ignitions. Furthermore while the invention is illustrated by io reference to embodiments in which an alarm sounds when a key is left in a lock it will be apparent to the skilled that the invention can be used with modification to sound an alarm when a key is inserted in a lock. This embodiment of the invention may be particularly useful in household medicine cabinets by sounding an alarm if a child seeks to open the cabinet.

Backeround A considerable proportion of thefts are opportunist. That is to say that the thief commits the crime, possibly unpremeditatedly, because the 2 chance presents itself. If the opportunity were not there the thief would not attempt the theft. A common example of this is the theft of vehicles while the key is left in the ignition or from buildings while the key is left---inthe door. In many cases the key holder leaves the key in the lock accidentally s for example while rushing to answer the telephone inside a house. In other cases the key holder thinks that the risk may be worth taking since they will leave the keys unattended for only a few minutes. Attempts have previously been made to provide lock alarms in which a signal is generated if keys are left in a lock. An example is our own prior ioapplication GB 95 037 80.0. While the arrangement set forth in this application is satisfactory in operation it is a little expensive in construction. The invention seeks to provide an inexpensive lock alarm.

Statement of the Invention is According to an aspect of the invention there is provided a lock assembly comprising:

i. a lock openable, by a key; 3 ii. a moving member urged towards a rest position by a resilient biasing means the moving member being displaced from the rest position by insertion of the key in the lock; iii. a proximity detector for detecting whether the moving member is in the rest position; and iv. an alarm activated when the proximity detector detects the moving member is displaced from the rest position.

According to an aspect of the invention there is provided a lock io assembly comprising:

i. a lock openable by a key; is ii. a proximity detector urged towards a rest position by a resilient biasing means the proximity detector being displaced from the rest position by insertion of the key in the lock; iii. means for activating the proximity detector when the proximity detector is urged away from the rest position; and iv. an alarm activated when the proximity detector is displaced from the rest position and is activated by the activating means.

4 Brief Description of the Fizures

Embodiments, of the invention will be described by way of nonlimiting example by reference to the accompanying figures of which Figure 1 is a plan view of a lock and key of a first embodiment received in a door frame, Figure 2 is a partially sectioned side elevation of the embodiment of figure 1, Figure 3 is an end view of the embodiment of figures 1 and 2, Figure 4 is a plan view of a lock and key of a second embodiment io received M" a door frame, Figure 5 is a partially sectioned side elevation of the embodiment of figure 4, and Figure 6 is an end view of the embodiment of figures 4 and 5.

is Description of Preferred Embodiments

Referring first to the embodiment of figures 1 to 3 there is provided a key barrel 1. Key barrel 1 may be of generally conventionally form and its construction will not be described in further detail since the skilled worker will have little difficulty in devismig suitable embodiments. As illustrated key barrel 1 is of the type commonly sold under the YALE@ trademark but the invention is not to be construed as so limited. Extending rearwardly of the barrel is a lock blade 16. In the illustrated embodiment key barrel 1 is retained by barrel seating ring 2 which may comprise bronze. The invention is not so limited.

Spacer sleeves 3 conveniently of steel extend rearwardly of the barrel and spaced apart from one another and the centre line of the barrel 1. Positioning disc 4 which can be made of plastics such as acetate is io carried by spacer sleeves. Screw threaded fasteners 5,6 which can be made of steel retain the assembly in the door frame in conjunction with lock plate 10 and washers 12.

As can be most clearly seen from figure 3 a reed switch 7 is provided at the rear of the barrel. The contacts of reed switch 7 are connected to an alarm circuit (not shown) for sounding an alarm buzzer or issuing other alarms. As will become apparent herefflafter other proximity detectors can be used. Magnetic field detectors such as reed switches or Hall efFect sensors are however preferred. Adjacent the proximity

6 detector 7 there is provided a movable means 8 detectable by the Proximity detector 7. Where, as in the illustrated embodiment, the proximity detector is a magnetic proximity detector movable means 8 may comprise a magnet especially a permanent magnet. Where other kinds of s proximity detector are used it will be necessary to provide other kinds of movable means. As will become apparent to the skilled worker components 7 and 8 can be transposed. That is to say the proximity detector can be movable and the means for actuated the proximity detector can be static.

Star washer 9 is received over lock blade 16. The purpose of this component will become apparent hereinafter.

Means 11 for moving the means for actuating the proximity detector is relative to the proximity detector 8 are provided. In the illustrated embodiment moving means 11 comprises a mushroom headed member slidingly received in positioning disc 4. Blade rotating member 13 is provided received over lock blade 16. Rotation of lock blade 16 rotates blade rotating member 13. Blade rotating member 13 is provided with t> 7 circumferential groove in which is received the head of moving member 11. Push rod 14 extends rearwardly of the barrel 1 and abuts blade rotating member 13. A resilient bias means 15, in the illustrated embodiment a helical spring, lies intermediate star washer 9 and blade rotating member 13 and urges blade rotating member 13 against the push rod 14. The head of moving member 11 is captive in the circumferential groove of blade rotating member and accordingly moving member 11 and hence magnet 8 are biased by the resilient bias.

In use, key 17 is inserted in the key hole. To unlock the door the key is rotated. However insertion of the key into the key hole displaces push rod 14 rearwardly overcoming resilient bias 15. Magnet 8 is brought toward-the reed switch 7 activating a timer in the alarm circuit. If the key is withdrawn before a predetermined time delay expires resilient bias 15 urges magnet 7 away from the reed switch deactivating alarm circuit. If key 17 is not removed and is let go of resilient bias 15 is not strong enough to urge the key from the key hole. Consequently magnet 8 stays proximate the reed switch 7 keepmig the timer activated. Once the time delay has expired the circuit issues an alarm for example by sounding a 8 buzzer. The user is thereby alerted to the fact that the key has been left in the lock and can remove it.

It will be apparent from the foregoing that the kind of proximity s sensor employed is not of the essence of the invention. Those skilled in the art will have no difficulty in devising other proximity sensors such as optical readers reading contrasting stripes.

The embodiment of figures 4 to 6 is broadly similar although lo somewhat simpler in construction. Only differences from the previous embodiments will be described.

Blade rotating member 13 need not in this embodiment be provided with a circumferential groove. Received on blade rotating member 13 is is magnet ring 100. When the key 17 is inserted in the key hole it displaces pushrod 14 rearwardly. Pushrod 14 abuts blade rotating member 13 and urges it rearwardly against the resilient bias of helical spring 15. The magnet ring 100 is thus moved toward proximity detector 7 where it is detected and the alarm activated as hereinbefore described.

9 As will be apparent the proximity detector and the member detected can be transposed.

Claims

1. A lock assembly comprising: i. a lock openable by a key; ii. a moving member urged towards a rest position by a resilient biasing means the moving member being displaced from the rest position by insertion of the key in the lock; iii. a proximity detector for detecting whether the moving member is in the rest position; and iv. an alarm activated when the proximity detector detects the lo moving member is displaced from the rest position.

2. A lock assembly comprising: i. a lock openable by a key; ii. a proximity detector urged towards a rest position by a is resilient biasing means the proximity detector being displaced from the rest position by insertion of the key in the lock; iii. means for activating the proximity detector when the proximity detector is urged away from the rest position; and 11 iv. an alarm activated when the proximity detector is displaced from the rest position and is activated by the activating means.

3. An assembly as claimed in claim 1 or claim 2 wherein the proximity s detector is a detector for magnetic field.

4. An assembly as claimed in claim 2 wherein the proximity detector is a Hall eflect switch or a switch.

5. An assembly as claimed 'm any one of the preceding claims wherein the alarm includes a delay delaying activation of the claim.

6. A lock assembly substantially as described herein by reference to any one of Figs. 4 to 6.

6. A lock assembly substantially as described herein by reference to any one of Figs. 1 to 3.

is

7. A lock assembly substantially as described herein by reference to any one of Figs. 4 to 6.

Amendments to the claims have been filed as follows CLAIMS 1. A lock assembly comprising:

1. a lock openable by a key; ii, a moving member urged towards a rest position by a resilient s biasing means the moving member being displaced from the rest position by insertion of the key in the lock; ul. a proximity detector for detecting magnetic fields for detecting whether the moving member is in the rest position; and iv. an alarm activated when the proximity detector detects the io moving member is displaced from the rest position.

2. A lock assembly comprising:

coo i. a lock openable by a key; ii. a proximity detector for detecting a magnetic field urged towards a rest position by a resilient biasing means the proximity detector being displaced from the rest position by insertion of the key in the lock; iii. means for activating the proximity detector when the proximity detector is urged away from the rest position; and 12 iv. an alarm activated when the proximity detector is displaced from the rest position and is activated by the activating means.

3. An assembly as claimed in claim 1 or claim 2 wherein the proximity detector is a Hall effect switch or a switch.

4. An assembly as claimed Mi any one of the preceding claims wherein the alarm includes a delay delaying activation of the claim.

A lock assembly substantially as described herein by reference to any one of Figs. 1 to 3.