GB2226901A - Alarm system - Google Patents

Abstract

An alarm system comprises a modular network which utilises the electrical mains wiring of the building to transmit digital information between various parts of the system, the network including an alarm device disposed outside the building and also coupled to the mains wiring circuit for receiving its alarm trigger instructions.

Description

DESCRIPTION ALArM SYSTEM The present invention relates to alarm systems and ,1 is concerned particularly with intruder alarm systems, although it may also be applied to other alarm systems, such as fire, dangerous gases and the like.

Currently known alarms fall into two principal types.

The first type is the "custon-fitted" intruder/fire alarm which involves a plurality of sensors fitted strategically around a building and hand wired by specially fitted cabling to a central control box which turn is hand wired by further cabling to an outside alarm box housing a bell r other audible and/or visible alarm device. Such syste=s have the disadvantages that they involve skilled labour to fit and have to be individually tailored to the buildings so that the cost ov installation is high - often more than the cost of the equipment itself. Furthermore, such systems need to be checked regularly in SitU and this often involves expensive maintenance contracts.

The second known type can be termed "D.I.Y alarm systems", not involving customized wiring. These include devices such as infra-red smoke or intruder warms which have an internal audible alarm device such as a bell or siren. More sophisticated devices, often used as body alarms, involve a sensor device, which is plugged into the building mains wiring circuit via any of the existing mains sockets or plugs, and a receiver device which is plugged into the wiring circuit in another part of the building. Activation of the sensor in the first part of the building, e.g. a bedroon, then triggers an internal alarm in the sensor disposed in the other part of the building, the building mains wring circuit being used to transfer digital signals between the sensor and receiver to trigger the alarm.

Unlike the "custom-fitted" type of alarm, the above described "D.I.Y type" using the mains wiring circuit to transfer inforra'ion between the plugged-in units have the advantage that it is not permanently fitted to the building but is portable and can be removed to new premises without difficulty in the event of the cwner/ tenant moving. however, the existing systems of this type do have the disadvantage that the alarm is -isposed wholly within the building it is attempting to protect.

It may therefore be easily ignored by neighbours who may not hear it, or the neighbours may be unaware from which property, flat or room the alarm is sounding, thereby reducing the prospects of outside help. Also, at night, if the occupant is in bed, the intruder may not =e deterred but may enter the room containing the alarm destroy the alarm and attack the occupant. Furthermore, if the premises are empty, an alarm, sounding inside the premises, could be disabled without necessarily raising public attention.

It is an object of the present invention to provide an alarm system of the second type which overcomes the abovedescribed disadvantages of the known devices.

In accordance with the present invention, there is provided an alarm system comprising a modular network which uses the electrical mains wiring in a house or building on which to transmit digital information between various parts of the system, the system including one or more sensors for dispcsition at suitable locations within the house or building, a control unit and one or more alarm devices, at least one of which alarm devices is disposed outside of the house or building, the sensor(s), control unit and alarm(s) being individually connectible to the mains wiring system of the house or building by way of the existing mains outlet sockets of the wiring system.

The sensor(s), control unit and alarm device(s) are preferably powered from the normal electrical supply and include battery back-up (preferably of the continuous rechargeable kind from the power supply itself).

The sensors preferably contain transmitters, and the alarm receivers, of digital information suitably and uniquely encoded with the identification of the sensor and the alarm.

The various units elements can be arranged for direct plug-in to a normal household socket or alternatively have a cable connection to a standard power supply plug or other convenient means. In a typical arrangement the sensors are arranged where intruders might be expected.

The control unit can be located anywhere the user can conveniently set the controls and be repositioned as may be required. The control means included in the unit can include on/off for the whole system and a, preferably, programmable means for detecting and directing sensor information to the appropriate alarms, or alternatively warning lights on the control box.

The invention is described further hereinafter, by way of example only, with reference to the accompanying drawing which is a simplified block diagram of an alarm system in accordance with the present invention.

A system in accordance with the present invention comprises a modular network which utilises the electrical mains wiring of the housing or building to transmit digital information between various parts of the system, the network including an alarm device disposed outside the building and also coupled to the mains wiring circuit for receiving its alarm trigger instructions.

Referring to the drawing, the system comprises three principal types of element. Firstly, the system includes one or more sensors 10, which can be, for example, infra-red, ultra-sonic, microwave, pressure pads and the like which, in use, are connected directly to existing mains sockets (either wall and/or ceiling mounted) by integral plug portions or by way of a cable and flying plug. Secondly, the system includes a control unit 16 which acts as a transmitter/ receiver of encoded digital information which again can be connected to the mains distributed wiring system 12 by way of an integral plug portion or flying plug lead.

Thirdly, the system includes one or more alarm devices 14, such as a bell, siren, or flashing light which is adapted to be mounted outside the house/building but which is again connected to the main wiring system 12, usually by way of a cable and flying mains plug.

Further alarm devices can be located inside the house/ building as required.

The abovedescribed devices 10,14,16 can be powered from the normal electricity supply to which they are connected. However, they preferably include individual battery back-up to provide power in the event that the mains supply is switched off or fails. Such batteries are preferably of the continuously rechargeable kind, charged by the mains power supply itself. It is particularly important for the alarm devices to have their own internal batteries to enable them to continue to provide an alarm signal in the event that the mains supply is removed or the electrical connection of such alarm device to the mains wiring system 12 is broken.

The sensors 10 contain transmitters, and the alarm receivers, of digital information suitably and uniquely encoded with the identification of the sensor and the alarm. In a typical arrangement, the sensor(s) 10 are arranged where intruders might be expected and the control unit 16 is located anywhere in the building that the user can conveniently set the controls. The control unit can be repositioned whenever required simply by removing it from one socket of the wiring system 12 and introducing it to another. The control means included in the control device 16 can include an on/off control for the whole system and a, preferably programmable, means for detecting and directing sensor information to the appropriate alarms or warning lights on the control unit.

Advantageously, the on/off function is controlled by way of some form of locking means available only to the user or other authorised person. For example, the lock could be in the form of a mechanical key or an electrical combination lock where the user has to insert a pre-programmed number and/or word onto a key-paJd in ,1 order to gain access to the control functions, e.g. to stop the alarm sounding. In this case, for example, one needs to tap the numbered and/or letter code into the con-trol pad, in order to generate a signal along the house wiring to stop the alarm.

The system could also include one or more panic buttons again connected at convenient locations to the wiring system 12 and/or at the control unit 16 itself.

Thus, for example, if an occupant is in a bedroom and hears or sees a potential intruder, then a panic button could be pressed in that bedroom so as to generate a signal in the wiring system 12 to set of the alarm, which could only be stopped by someone inserting the key or code.

The great advantages of the abovedescribed system are its flexibility and the fact that it can be removed very easily if the occupant moves premises. An obvious advantage of a movable control unit is that it can, if desired, be moved around the building with the occupiers. When leaving the building unattended the control box is left in the most convenient plug, for example in the garage.

Claims (9)

1. An alarm system comprising a modular network which uses the electrical mains wiring in a house or building on which to transmit digital infomation between various parts of the systems the system including one or ignore sensors for disposition at suitable locations within the house or building, control unit and one or more alarm devices; at least one of which alarm devices is disposed outside of the house or building, the sensor(s), control unit and alarm(s) being individually connectible to the mains wiring system of the house or building by way of the existing mains outlet sockets of the wiring system.

2. An alarm system as claimed in claim 1, wherein the sensors contain transmitters, > and the alarm contains receivers, of digital information suitably and uniquely encoded with the identification of the sensor and the alarm.

3. An alarm system as claimed in claim 1 or 2, in which the sensor(s), control unit and alarm device(s) are powered from the normal electrical supply and include battery back-up.

4. An alarm system as claimed in claim 3, in which the battery back-up is of the continuously rechargeable kind adapred to be charged from the mains electrical supply.

5. An alarm system as claimed in claim 3 or 4, wherein the sensor(s), control unit and alarm device(s) are arranged for direct plug-in to a normal household socket or have a cable connection to a standard power supply plug or the like.

6. An alarm system as claimed in any of claims 1 to 5, wherein a control means included in the control unit incorporates an on/off control for the whole alarm system.

7. An alarm system as claimed in claim 6, in which the control means includes a means for detecting and directing sensor information to the appropriate alarms.

8. An alarm system as claimed in claim 7, in which said control means for detecting and directing sensor information is programmable.

9. An alarm system substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing