GB2274531A

GB2274531A - Vehicle theft alarm

Info

Publication number: GB2274531A
Application number: GB9301508A
Authority: GB
Inventors: Richard Henry White
Original assignee: Individual
Current assignee: Individual
Priority date: 1993-01-26
Filing date: 1993-01-26
Publication date: 1994-07-27
Also published as: GB9301508D0

Abstract

A burglar alarm system for a motor vehicle connected by a remote communication link (18, 30) to a burglar alarm system installed in a building so as to cause the alarm (34) in the building to sound in response to detection of any tampering with the motor vehicle. Means are also provided in order to enable the driver to interchange between using the conventional vehicle alarm siren (22) and the building alarm siren (34) via the radio communication link (18, 30). <IMAGE>

Description

BURGLAR ALARM The present invention relates to a burglar alarm.

Background of the Invention Motor vehicle burglar alarms are known for detecting unauthorised entry or tampering with a motor vehicle. Such known alarms can sense vibration of the vehicle using a trembler switch, opening of a door, the hood or trunk, breaking of glass, or operation of the ignition switch.

Systems have also been proposed that use infra-red or ultrasonic detectors to sense the presence of an intruder within the passenger compartment.

Conventionally after a burglar alarm system has sensed an intruder or unauthorised tampering, the horn or a siren is made to sound, the headlights may be operated and an immobilisation system may be activated.

A problem with motor vehicle burglar alarm systems is that they tend to have a high false alarm rate. For this reason even when they do sound correctly, they tend to be ignored by the general public. As a result, the only person likely to respond to an alarm is the owner of the vehicle. However, the owner is often out of earshot and unaware of the operation of the burglar alarm.

For this reason, it has been proposed to use a radio communication link to operate a pager carried by the owner of the vehicle in order to warn the owner of the intrusion, even when he is too far from the vehicle to hear the sound of the vehicle siren. Even this however is not a very satisfactory system, as the owner may not be wearing the pager when the alarm sounds.

Summary of the invention With a view to mitigating the foregoing disadvantages, the present invention provides a burglar alarm system for a motor vehicle connected by a remote communication link with a burglar alarm system installed in a building so as to cause the alarm in the building to sound in response to detection of any tampering with the motor vehicle.

Burglar alarm systems installed in a building usually have a control panel that receives input signals from a variety of detectors for example infra-red detectors, ultra-sonic detectors, door and window micro-switches and operates a siren or telephones the police in response to detection of an intruder while the system is armed. Alarms fitted to a building also often have facility for a so-called panic switch that sounds an alarm even if the system is not armed, this switch being manually operated by the legitimate occupier of the building in the event of an emergency.

In the present invention, use is made of this existing facility in many building alarms, to respond to a signal received through a remote communication link from the vehicle alarm as though it were a depression of the panic switch, so as to sound the building alarm. Unlike vehicle alarms, building alarms are less likely to be disregarded, especially since the vehicle owner is likely to be within the building at that time.

Preferably, while the remote communication link is operating, the vehicle alarm is silenced so that no warning should be given to the would be thief that his presence within the vehicle has been detected. To this end, it advantageous to provide the vehicle alarm with a switch to enable the driver to select between a vehicle alarm signal and a remote alarm signal, depending on where the vehicle is left.

Brief description of the drawing The invention will now be described further, by way of example, with reference to the accompanying drawing which is a block diagram of a burglar alarm system of the present invention.

Description of the preferred embodiment In the single drawing, two large boxes drawn in dotted lines are used to distinguish between the components of the alarm system mounted on the vehicle and the those located within a building, the latter being an office or a residential home.

The vehicle alarm system comprises a control unit 10 connected to various sensors, the drawing showing a trembler switch 12 and a door switch 14 as typical examples. When a sensor detects an alarm condition, it sends a signal to the control unit which then activates a siren 22. The control unit 16 may typically comprise circuitry to control sensitivity, circuits for determining the length of time that an alarm is sounded by the siren 22. In addition, the control unit may operate the headlights or the indicators to give a visible warning. As so far described the vehicle alarm system is generally conventional and indeed any conventional system may be adapted for use in the present invention.

In the preferred embodiment of the invention, the signal to the siren can be re-directed by the use to a manually operable selector switch 16 to a radio transmitter 18 fitted with an antenna 20, which may the same aerial as used by the vehicle entertainment system or telephone. If the driver should operate the switch 16 on leaving the vehicle, then instead of emitting a sound in response to intrusion detection, the vehicle alarm system will transmit a radio signal from the antenna 20. The carrier frequency and superimposed modulation are determined by the radio transmitter 18. By transmitting an encoded signal of suitable length, one can ensure a sufficient number of combinations to avoid interference between users so that a vehicle should not cause an alarm to sound in the wrong building.

Within the building alarm installation, a control panel 24 receives input signals from various sensors, the examples illustrated being an infra-red detector 26 and a panic switch 28. When armed, the control panel 24 responds to a signal from the intrusion detector 26 to cause a siren 34 to sound. There may be internal and external sirens in the building and additionally the control panel may be connected to a telephone line to make an automatic direct call to a police station. The panic switch 28 is usually connected to make the siren 34 sound even when the building is occupied and the control panel 24 is not armed. As so far described, the building alarm system is conventional.

The building alarm also comprises a radio receiver 30 having an antenna 32 for picking up the radio signal emitted from the vehicle transmitter 18. The receiver 30 is tuned to the same carrier frequency and detects a code received over that frequency. If the code should match that programmed into the receiver and corresponding to the code transmitted by the transmitter 18, then the output from the receiver 30 is treated by the control panel 24 in the same way as the panic switch and an alarm is immediately sounded.

It can be seen from the foregoing description that the invention may be implemented by the addition of a remote communication link between a convention vehicle alarm system and a conventional building alarm system, and for this reason it is not believed necessary to describe other components of these two systems in detail. For example, the manner in which the systems are armed has not been described in detail but one may use a key, a keypad or an infrared remote control in the same way as conventional systems.

Furthermore, it will be appreciated that in a building, the control panel will usually give an indication of the area of the building which gave rise to an alarm and by inspection of the lights on the control panel the user will be able to distinguish between an intrusion into the building and one into the vehicle.

Claims

1. A burglar alarm system for a motor vehicle connected by a remote communication link to a burglar alarm system installed in a building so as to cause the alarm in the building to sound in response to detection of any tampering with the motor vehicle.

2. A burglar alarm system as claimed in claim 1, wherein the building alarm system includes a panic switch capable of sounding an alarm even when the system is not armed, and wherein a signal from the remote communication link is processed by the building alarm system in the same manner as activation of the panic switch.

3. A burglar alarm system as claimed in claim 1 or 2, wherein no sound is emitted in the motor vehicle when the remote communication link is activated.

4. A burglar alarm system as claimed in claim 3, in which the vehicle alarm system comprises a switch to enable the driver to select between a vehicle alarm signal and a remote alarm signal.

5. A burglar alarm system constructed, arranged and adapted to operate substantially as herein described with reference to and as illustrated in the accompanying drawing.