SECURITY SYSTEM FOR VEHICLES

Abstract: A security system for a vehicle, comprising a control unit (1), for processing control signals, and having at least a first state, indicative of normal operation of the vehicle, and a second state, indicative that the vehicle has been the subject of unauthorised interference, a radio transmitter (5) connected to the control unit, and adapted, on receipt of a first control signal from the control unit (1), to produce a first radio signal, indicative of unauthorised interference with the vehicle, means (2) for producing, on receipt of a second control signal from the control unit (1), a visual indication visible from outside the vehicle, or an audible indication audible from outside the vehicle, indicative of unauthorised interference with the vehicle, means (3) for immobilising the vehicle, on receipt of a third control signal from the control unit (1), means (7) for sensing unauthorised interference with the vehicle, and for producing an indication to the control unit (1) to switch the said control unit (1) to the said second state, on receipt thereof, means (8) for sensing whether or not the vehicle is active, means (1) for inhibiting production of the said third control signal when the vehicle is active, a radio receiver (4) adapted to receive an interrogation signal from an interrogator transmitter (10), means (1) for distinguishing different types of interrogation signals, and for producing a response which varies in dependence upon the type of interrogation signal received, wherein the control unit (1) is adapted to produce the said first, second, and third control signals only on receipt of a said interrogation signal.

Description: Securitv system for vehicles This invention relates to security systems, and in particular to security systems incorporating alarms, intended for vehicles, especially road vehicles such as cars and commercial vehicles. Many types of alarm systems for vehicles have been devised in recent years, in response to increasing thefts of and from motor vehicles. Many systems in common use provide for the remote arming of an alarm system, for example using a radio transmitter carried on the person, for example on a key fob. Most systems in common use are of the type which, when triggered by unauthorized interference with the vehicle, simply cause an audible alarm to sound, and/or provide a visual indication, for example by flashing of indicator lights, that the vehicle has been tampered with. More sophisticated systems which have been proposed ir_.recp.nt years transmit a radio signal, which wr.y b-- picked up by a police receiver, in order to enable a stolen vehicle to be located and/or tracked. Most such systems are- complex ones, in which vehicles can be tracked from long distances, using complex direction finding (DF) techniques. For example, EP-A-0245555 discloses a system in which vehicles are equipped with a transponder or transceiver, which may be tracked by appropriately-equipped police direction-finding tracking vehicles. US-A-4990890 discloses a security system for monitoring a number of vehicles, each of which includes an immobilizer and a transceiver. The system includes a number of security stations which detect signals emitted by vehicles when unauthorized interference is detected. The signals identifying the vehicles are stored and transmitted to a base station, in response to a polling signal. The affected vehicles are then immobilized by means of a signal from the base station, or from one of the security stations, at an appropriate time or location. GB-B-2119552 discloses a security system which includes a radio transmitter located in the vehicle, and a surveillance radio receiver located at a point remote from the vehicle, in which the surveillance receiver can transmit a signal to a receiver in the vehicle, which causes the vehicle to stop. In accordance with a first aspect of the present invention, there is provided a security system for a vehicle, comprising a control unit for processing control signals, and having at least a first state, indicative of normal operation of the vehicle, and a second state, indicative that the vehicle has been the subject of unauthorised interference (for example, that the vehicle has been broken into, or that the engine has been started whilst the system is "armed"), a radio transmitter connected to the control unit,, and adapted, on receipt of a first control signal from the control unit, to produce a first radio signal, indicative of unauthorised interference with the vehicle, means for producing, on receipt of a second control signal from the control unit, a visual indication visible from outside the vehicle, or an audible indication audible from outside the vehicle, indicative of unauthorised interference with the vehicle, means for immobilising the vehicle, on receipt of a third control signal from the control unit, means for sensing unauthorised interference with the vehicle, and for producing an indication to the control unit to switch the said control unit to the said second state, on receipt thereof, means for sensing whether or not the vehicle is active, (for example whether the vehicle is moving, or whether or not the vehicle's engine is running), means for inhibiting production of the said third control signal when the vehicle is active, a radio receiver adapted to receive an interrogation signal from an interrogator transmitter, means for distinguishing different types of interrogation signals, and for producing a response which varies in dependence upon the type of interrogation signal received wherein the control unit is adapted to produce the said first, second, and third control signals only on receipt of a said interrogation signal. The security system in accordance with the i vention includes a control unit for processing control signals, and in particular for producing control signals for controlling respectively a radio transmitter, and a visual and/or audible indicator that the vehicle has been stolen or otherwise tampered with, and for immobilizing the vehicle. The control unit contains a flag (referred to, for convenience, as the "stolen" flag) which can be set to indicate that the vehicle has been the subject of unauthorized interference. Unauthorized interference is detected by means of a sensor, which can be of generally conventional type, for example ultrasonic, vibration sensing, or a circuit for detecting unauthorized interference with the ignition system. A radio transmitter is connected to the control unit and, on receipt of the appropriate control signal from the control unit is able to transmit a radio signal, which may be picked up by a police receiver, indicating that the vehicle has been" stolen. The control signal which activates the transmitter is issued when the control unit receives a suitable interrogation signal whilst the "stolen" flag is set. A switching circuit is also provided for providing a visual and/or audible indication (normally by sounding the vehicle horn, or flashing the indicator lights in a specific sequence). According to an alternative aspect of the invention a vehicle theft indicator includes a receiver unit adapted to receive a predetermined signal, a transmitter adapted to interrogate the receiver unit whereupon the receiving unit will, depending on the result of the interrogation, do nothing or initiate an emitter unit adapted to emit a signal receivable by an outside receiver or which actuates a warning or alarm device. The transmitter may be fixed in the vehicle or may be mobile or portable. Thus, the inside receiver may receive a predetermined signal initiated by the owner of the vehicle or an authorized user by actuating a switch or by making a certain noise or other activity, in which case the interrogation will result in no further action; but, in the absence of such a predetermined signal, the interrogation will cause the emission of the warning or transmitted signal. Alternatively, a predetermined signal may be initiated unknown to an unauthorized driver, for example a switch associated with the clutch, steering wheel, seat or the like, and this will cause an adverse interrogation -D- resulting in the emission of a warning, alarm or transmittable signal. The outside receiver may be located at any suitable place such as a police station or a central depot. The various parts of the security system may be hidden within the vehicle or disguised in some suitable form, in order to render them less readily detectable by a thief. A preferred embodiment of the invention will now be described in detail with reference to the accompanying drawings, in which:- Figure 1 is a schematic diagram of a vehicle security system in accordance with the present invention, and Figure 2 is a schematic diagram of an interrogator unit incorporating a transmitter, for interrogating the security system of Figure I. The security system of Figure 1 comprises a control module (1), connected to an alarm control module [ 2 ) . an immobilizer control module (3), a receiver module (4), a transmitter module (5) and a pager module (6) . The receiver module (4) has a first channel (channel 1) for receiving a signal from a portable transmitter, intended to be carried by an authorized user of the vehicle, for example on a key fob, in a handbag or the like. The portable transmitter is a low powered device, with a range of 1 to 2 metres, and transmits a low power signal containing an identity code specific to the vehicle, in intermittent bursts, for example for a period of approximately 10 milliseconds in each period of 1 to 2 seconds. Transmission for only one percent of the time results in increased battery life for the portable transmitter. The portable transmitter is such that transmission is automatic, and no manipulation has to be carried out by the driver in order to activate the transmitter. If channel 1 of the receiver (4) does not receive periodic transmission from the portable transmitter (i.e. when such a signal is not received by the receiver for longer than a predetermined period of time), a flag is set in the processing module (1), indicating that the device is "armed". If an attempt is made to enter the vehicle, or start the engine whilst the device is armed, the "stolen" flag is set in the processing module (1). In an alternative embodiment, arming and disarming of the device may be carried out by manual operation of the portable transmitter by the operator. When the device is armed, a control signal is sent by the processing module to the i mobilizer control module (3) in order to immobilize the vehicle, for example by disconnection of the ignition, fuel pump or the like. A sensing module (7) detects unauthorized interference with the vehicle, the sensing module may employ, for example, for example door contacts, vibration detectors, ultrasonic detectors. Thermal sensors for detecting the engine temperature, or other electrical detectors linked to the vehicle electrical system, in particular the ignition system, may be employed, in order to detect whether, notwithstanding the operation of the immobilizer 3, the engine has been started by bypassing the immobilizer. On receipt of a signal from sensing module (7), when the processing module is in the "armed" state, a flag is set in processing module ( 1 ) indicating that the vehicle has been "stolen". The processing module does not however send a control signal to alarm module (2) or to transmitter module (5) immediately, but instead simply awaits interrogation by a police interrogator unit, as will be described hereinafter. A typical police interrogator unit is illustrated in Figure 2, and consists of a transmitter module (10), a receiver module (11), and a processor module (12). When operational, transmitter module (10) continuously transmits a pulsed signal, which may be received by any vehicle security system in accordance with the invention which is in the immediate vicinity (normally within a range of 50-100 metres or so). The transmitted signals are received by channel 2 of receiver module ( 4 ) in the vehicle security system. Two types of interrogator unit are provided, intended respectively for use by vehicle based police patrols and foot police patrols. Each type of interrogator unit transmits a different code which can be received by channel 2 of receiver (4). The response of control unit (1) varies depending upon the nature of the signal received, and _pou the signal received from a movement sensing module ( 8 ) associated with the security system. The simplest type of .interrogator unit, intended for use by foot patrols, continuously transmits a first pulsed code (referred to for convenience as "code A") whenever in operation, and a second code (referred to for convenience as "code B" ) on operation of a "reveal" button (13) located on the interrogator unit. When "code A" is received by a stationary vehicle, the control unit (1) causes the appropriate signal to be sent to alarm module (2) to cause the car horn to emit a characteristic signal, and the car indicators to flash alternately, in order to indicate that the vehicle has been stolen. This operates without any intervention from the police officer concerned. Thus, if the policeman on foot carrying the interrogator unit comes within range of a stationary stolen vehicle, he receives both an audible and visual indication of the presence of the stolen vehicle. Both the audible and visual signals continue for a period of 30 seconds, and then both cease. If the officer wishes to repeat the audible and visual sequence, he actuates the "reveal" button on the interrogator unit, which causes "code B" to be transmitted to the receiver module (4), causing the sequence to be repeated. Codes A and B have no effect on a moving vehicle (as determined by movement sensing module (8) ) . The second type of interrogator unit is functionally identical with the first type, except that the two types of code transmitted are distinct from those transmitted by the first type, and will be referred to, for convenience, as "code C" and "code D". The secord type of interrogator unit is intended to be carried by a vehicle-based police control, which is capable of pursuing a stolen vehicle. Λ.. with the first type of interrogator unit, the default state is that a code ("code C" ) is transmitted con inuously. When "code C" is received by a vehicle which is stationary (as determined by movement sensing module (8)), the vehicle responds in the same way as when it receives "code A", namely by actuation of the visual and/or audible alarm. Although it is also possible for the same sort of audible and visual signals to be given when "code C" is received by a moving vehicle, this is generally undesirable because of the possible hazardous resulting effect on other drivers in the vicinity, and thus the danger to road safety. Instead, control unit (1) sends a control signal to transmitter module (5), which causes an acknowledgement signal to be transmitted by transmitter module ( 5), which can be received by the receiver module (11) in the interrogator unit. Receipt of this signal causes an audible and visual display at the interrogator unit (i.e. causes a buzzer to operate and an LED or similar device to indicate receipt of the signal). Thus, police officers in the mobile unit are alerted to the presence of a stolen vehicle. Depression of the "reveal" button (13) on the interrogator unit can then be used to cause "code D" to be transmitted in order to cause a visual and/or audible signal from the stolen vehicle, thus enabling positive identification. The range of the interrogator/security system combination is such that only vehicles within a radius of approximately 100 metres from the interrogator unit respond to the interrogator signal. This has the dual effect of removing the need for the interrogator unit to be able to cope with conflicting signals from two or more stolen vehicles in the area, and also reduces the general congestion of the airwaves in the vicinity. In a further preferred embodiment, as illustrated in Figure 1, the security system comprises a. pager module (6). The pager module (6) is adapted to receive a signal from a national or regional paging network, to enable independent activation of the control unit to "flag" the vehicle as stolen. Thus, if the unique "key fob" transmitter (20) should be lost or stolen, a telephone call from the owner of the car to a pager operator can be used to authorize the transmission to the vehicle of the unique numeric code. On receipt of this code by paging module ( 6) , a signal is sent to the control unit to set the "stolen" flag. Operation is thereafter the same as when the "stolen" flag is set by absence of the key fob transmitter. Means may preferably be provided for causing the immobilizer control module (3) to operate immediately when the vehicle comes to a standstill. Once the "stolen" flag has been set by the pager, cancellation of the flag can only be caused by a second unique code being transmitted by the paging company, at the request of the vehicle owner. The immobilizer control module (3) may be located in a variety of alternative locations in the vehicle, and may be capable of immobilizing the vehicle in a variety of ways, for example by disabling the fuel pump, or disabling the ignition. The interrogator unit may be provided with means for varying the transmission power and hence the range at which vehicles will respond, in order to allow for varying environmental conditions. The interrogator unit, whether of the first design intended to be carried in the pocket of a police officer, or of the second design intended for use in a police car, may transmit the relevant code A, B, C, or D intermittently, for example in bursts of approximately 10 milliseconds, in each period of 1 to 2 seconds. In a preferred embodiment, the interrogator includes an immobilizer button (14) able to activate the immobilizer immediately at the will of the police officer at an appropriate time when such immobilization will not generate a road safety hazard. Various other specific arrangements are possible within the scope of the appended claims.

Claims: CLAIMS 1. A security system for a vehicle, comprising a control unit (1), for processing control signals, and having at least a first state, indicative of normal operation of the vehicle, and a second state, indicative that the vehicle has been the subject of unauthorised interference, a radio transmitter (5) connected to the control unit, and adapted, on receipt of a first control signal from the control unit (1), to produce a first radio signal, indicative of unauthorised interference with the vehicle, means (2) for producing, on receipt of a second control signal from the control unit (1), a visual indication visible from outside the vehicle, or an audible indication audible from outside the vehicle, indicative of unauthorised interference with the vehicle, means (3) for immobilising the vehicle, on receipt of a third control signal fr " om the control unit (1), means (7) for sensing unauthorised interference with the vehicle, and for producing an indication to the cuntrol unit (1) to switc the said control unit (1) to the said second state, on receipt thereof, means (8) for sensing whether or not the vehicle is active, means (1) for inhibiting production of the said third control signal when the vehicle is active, a radio receiver (4) adapted to receive an interrogation signal from an interrogator transmitter (10), means (1) for distinguishing different types of interrogation signals, and for producing a response which varies in dependence upon the type of interrogation signal received wherein the control unit ( 1 ) is adapted to produce the said first, second, and third control signals only on receipt of a said interrogation signal. 2. A system as claimed in Claim 1, wherein the activity sensing means (8) is adapted to sense whether or not the vehicle engine is running. 3. A system as claimed in Claim 1 or Claim 2, wherein the means for producing an indication of unauthorised interference with the vehicle includes a portable transmitter (20) for producing a second radio signal, and adapted to be carried by an authorized user of the vehicle, and a receiver (4) connected to the control unit for receiving the said second radio signal, and wherein means are provided for switching the control unit to the said second state, if the said second radio signal is not received by the said receiver (4) for longer than a predetermined period of time. 4. A system as claimed in any one of the preceding claims, wherein the control means is such that a first type of interrogation signal causes activation only of the said radio transmitter (5), and a second type of interrogation signal causes operation only of the said visual and/or audible warning (2). 5. A system as claimed in any one of the preceding claims, including an interrogation transmitter (10,11,12) as defined in Claim 6, wherein the system is such that the said at least one of the said first. second and third control signals is produced only when the said interrogation transmitter is within a range of 100 metres of the said receiver therefor. 6. A system as claimed in Claim 5, wherein the said interrogation transmitter (10,11,12) is adapted to produce a continuous or repetitive interrogation signal for reception by the said vehicle-mounted system. 7. A system as claimed in any one of the preceding claims, including means (9) for receiving a fourth radio signal, and for causing the control unit (1) to switch immediately to the said-second state, on receipt thereof.

Inventors: PARNABY MICHAEL BOYDEN, PARNABY, MICHAEL, BOYDEN
Applicants: AUTOWATCH UK LIMITED, MERCURY PAGING LIMITED, AUTOWATCH (UK) LIMITED
Application year: 1992
Main classification: B60R25
IPC codes: B60R25