GB2259194A

GB2259194A - Security unit for electric plug

Info

Publication number: GB2259194A
Application number: GB9117792A
Authority: GB
Inventors: Alan Harper
Original assignee: Individual
Current assignee: Individual
Priority date: 1991-08-16
Filing date: 1991-08-16
Publication date: 1993-03-03
Also published as: GB9117792D0

Abstract

A security unit for a mains powered electrical device which device is connected to a mains supply by way of a plug and socket connection characterised in that the unit comprises: a dummy socket (13) adapted to receive the plug (11) so as to shroud the electrodes thereof; and a locking unit (19, 20) whereby the plug is retained in the dummy socket in a secured position to prevent the use of the plug in a supply socket. Typically the dummy socket incorporates a storage region for cable by means of which the plug can be connected to a mains powered electrical device, the storage region being at least partially shrouded by the locking unit, when in the secured position, to retain cable in the dummy socket so as to limit the amount of surplus cable available between the dummy socket and an electrical device to which the cable is, or is intended to be, attached. The locking unit additionally prevents access to the means for dismantling the plug. <IMAGE>

Description

SECURITY UNIT This invention relates to a security unit. In particular it is concerned with means for preventing the unauthorised use of equipment powered from an external electrical source.

Various types of mains powered electrical devices make use of a means for preventing or inhibiting unauthorised use of the device. Typically it is known for a satellite television receiver to have a code controlled operating system so that children cannot have unlimited access to programs received.

In other devices a key controlled isolating switch is used so that the device cannot be powered up without use of a key. However this requires the equipment involved to be specifically designed to incorporate the inhibition feature and most forms of electrically powered equipment do not lend themselves to ready modification to provide such a feature.

This invention is particularly, though not exclusively, concerned with mains powered equipment where a cable or flex extends from an anchorage on or within the equipment to a plug which is inserted into a mains powered socket to enable power to be fed to the equipment.

According to a first aspect of the present invention there is provided a security unit for a mains powered electrical device which device is connected to a mains supply by way of a plug and socket connection characterised in that the unit comprises a dummy socket adapted to receive the plug so as to shroud the electrodes thereof and a locking unit whereby the plug is retained in the dummy socket to prevent the use of the plug in a supply socket. The locking unit can further serve to prevent access to a part of the plug whereby the plug can be dismantled to give access to power conductors therein. Typically the locking unit is a key operated or combination lock.

According to a second aspect of the present invention a security unit according to the first aspect is further characterised in that the dummy socket incorporates a storage region for cable by means of which the plug can be connected to a mains powered electrical device, the storage region being at least partially shrouded by the locking unit to retain cable therein so as to reduce to a minimum the amount of free cable between the dummy socket and an electrical device to which the cable is attached.

An exemplary embodiment of the invention will now be described with reference to the accompanying drawing which is a perspective exploded view of a plug and associated security unit.

Plug 11 on a lead 12 serves to provide power to a conventional mains powered television set. During normal use the plug 11 is connected to a mains supply outlet socket mounted on a wall. In the event that use of the television set is to be curtailed for a period the plug 11 is removed from the wall socket and inserted into dummy socket 13. This comprises an insulated enclosure 14 pierced by an appropriately configured array of slots 15 which are of sufficient depth to ensure that when the plug 11 is fully inserted into the dummy socket the conducting pins 11A and 11B of the plug 11 and the earth pin 11C are fully shrouded within the enclosure 16 and cannot be contacted from outside the enclosure 16.

U-bolt 17 is then pushed into the enclosure 16 retain the plug 11 in the dummy socket 13 and a lock 19 operates to secure the U-bolt 17 against further movement thereby retaining the plug against withdrawal from the dummy socket. This prevents the further use of the plug 11 to provide power to the television set which can only be powered up again by using key 20 to release the lock, remove the U-bolt 17 so allowing the plug 11 to be removed from the dummy socket 15 and inserted in a power point.

By using a dummy socket as described unauthorised use of the television set is readily prevented. Clearly a variety of locks are available for use with a dummy socket of the general type described. Typically to avoid the need for a separate key 20 a built-in combination lock can be used. In addition instead of a separate U-bolt 17 the dummy socket can incorporate a movable but captive component to engage the plug.

In an alternative version of the plug within the enclosure 14 the slots 15 complementing power pins 11A and 11B are linked to one another by a conducting link within the enclosure so that any attempt to power up the mains powered unit from an alternative power source by some independent connection while the plug is inserted in the dummy socket to which the plug is attached will result in a short circuit arising by way of the conducting link between pins liA and 11B.

The exemplary embodiment is concerned with regulating use of a television set. However the present invention lends itself to securing any externally powered device making use of a plug and socket connection. These include a large piece of equipment when it would be inconvenient to move the equipment into an secure location such as a locked container or shed.

It will be understood that a plug and dummy socket could be cut from the end of a lead and a further plug attached to the cut cable end to enable the equipment to be powered up. However such action necessarily takes time and in any event it is subsequently apparent that such an unauthorised event has occurred. In a further embodiment of the present invention the enclosure of the dummy socket is shaped to provide a storage reel or at least storage volume so that the cable can be wound round or otherwise packed on or into the enclosure for retention by way of the locking means. This provides for the amount of any free length of cable between the plug and the electrical unit it feeds to be kept to a minimum. This serves to increasing the difficulty of making use of any part of the cable to feed the electrical unit.

Claims

1 A security unit for a mains powered electrical device which device is connected to a mains supply by way of a plug and socket connection characterised in that the unit comprises: a dummy socket adapted to receive a plug whereby the device receives power so as to shroud the electrodes of the plug; and a locking unit whereby a plug is retained in the dummy socket in a secured position to prevent the use of the plug in a supply socket.

2 A security unit as claimed in Claim 1 characterised in that the unit incorporates a storage region for cable attached to a plug engaged with the dummy socket, the storage region being at least partially shrouded by the locking unit, when in the secured position, to retain cable in the storage region so as to limit the amount of surplus cable available between the dummy socket and an electrical device to which the cable is, or is intended to be, attached.

3 A security unit as hereinbefore described with reference to and as illustrated in the accompanying drawings.

4 A security unit as claimed in any preceding claim wherein the locking unit is a key operated or combination lock.

5 A security unit as claimed in any preceding claim wherein the locking unit when in the secured position serves to shroud access to a part of the plug whereby the plug can be dismantled to give access to a power conductor therein.

6 An electrically powered device equipped with a security unit as claimed in any preceding claim.