GB2141567A

GB2141567A - Anti-hijack devices

Info

Publication number: GB2141567A
Application number: GB8316345A
Authority: GB
Inventors: Arjang Agahi
Original assignee: Individual
Current assignee: Individual
Priority date: 1983-06-15
Filing date: 1983-06-15
Publication date: 1984-12-19
Also published as: GB8316345D0

Abstract

An anti-hijack device for a motor vehicle has a memory device containing a preset coded signal, a comparator to which a coded signal can be applied and which compares the applied signal with that in the memory and a circuit for immobilising the engine of the motor vehicle and/or surrounding the alarm. If the lawful driver of the vehicle anticipates being hijacked, he operates the device which, at the end of a predetermined time interval, energises the circuit to immobilise the engine and/or alarm. If the danger passes, and the vehicle is not hijacked, the lawful driver introduces the correct coded signal into the comparator to stop the timer. <IMAGE>

Description

SPECIFICATION An anti-hijack device for a motor vehicle This invention relates to an anti-hijack device for a motor vehicle.

There is, unfortunately, a tendency for motor vehicles to be hijacked, that is, for the hijacker to threaten the driver sufficiently for him to leave the vehicle and allow it to be driven away by the hijacker. The hijacker may eventually abandon the vehicle. Hijacking is different from theft of a vehicle, where it is taken without consent and without the driver being present.

It is an object of the present invention to provide an anti-hijack device which can be fitted in a motor vehicle which lessens the value of the vehicle to a hijacker.

According to the present invention, an antihijack device for a motor vehicle comprises a memory device containing a preset coded signal, a comparator device arranged to compare a coded signal applied thereto with said coded signal in the memory device, means for applying the coded signal to the comparator device, a circuit for immobilising the engine, an alarm device, a timer, and means for initiating the timer, the device being such that, once the timer has been initiated, the circuit for immobilising the engine is energised and the alarm is sounded after a predetermined time interval unless, in the meantime, a coded signal, which is the same as the present signal in the memory device, is applied to the comparator device.

In use, the means for applying a coded signal to the comparator device and the means for initiating the timer are located in the vehicle at a position readily available to the driver. If the driver has any reason to believe that his vehicle is about to be hijacked, he simply operates the means for initiating the timer. If the vehicle is then hijacked and is driven away by the hijacker, the engine is immobilised after a predetermined interval and the alarm sounded, thus rendering the vehicle useless to the hijacker.

To enable the driver of the vehicle to prevent the engine from being immobilised if the vehicle is not hijacked, the driver applies a coded signal, which is fed to the comparator device, where it is compared with a coded signal in the memory device. If the correct coded signal is applied to the comparator, the circuit for immobilising the engine is not energised and the alarm is not sounded at the end of the predetermined time interval.

The means for applying a coded signal to the comparator is conveniently a push-button arrangement consisting of, say, ten push-buttons numbered 0-9, respectively, and by by operating, say, six of the ten buttons in sequence, a very large number of unique coded signals can be fed into the device. Alternatively, twenty six push-buttons may be provided, each labelled with a different letter of the alphabet. Again, by choosing a word of, say, six letters, a very large number of unique coded signals or passwords can be obtained by operating the push-buttons in sequence. If desired, ten push-buttons numbered 0-9 and twenty six push-buttons labelled A-Z may be provided so that the coded signal or password may consist of letters and numbers.

The anti-hijack device may be incorporated with an anti-theft device which operates to immobilise the engine and/or operate an alarm if entry is made to the vehicle and a correct password is not introduced into the comparator within a predetermined time interval. In this way, a vehicle can be ieft in a condition where, after a predetermined interval of time following the opening of a door of the vehicle, the alarm operates and/or the vehicle is immobilised unless the correct password is introduced into the comparator.

In order that the invention may be more readily uderstood, it will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a block diagram of the antihijack device; Figures 2A and 2B show alternative forms of keyboards by which coded signals can be applied to a comparator device; Figure 3 is a block diagram showing the modes of operation of the device; and Figure 4 shows the sequence of steps in the operation of a device in accordance with one embodiment of the present invention.

Referring to Fig. 1, a device in accordance with one embodiment of the present invention consists of a processor 1 and a keyboard 2.

The keyboard is located inside the vehicle, conveniently on the dashboard, and the processor is located elsewhere, conveniently in an inaccessible position within the engine compartment of the vehicle. The processor and the keyboard are connected by an electrical cable 3. From the processor 1, there is a connection 4 to the horn or other audible alarm on the vehicle, and a connection 5 to a circuit for immobilising the electrical circuit of the engine of the vehicle. The processor receives signals on lines 6, 7 and 8 from switches on the doors, from the ignition switch, and from a switch or switches on the boot and bonnet of the vehicle, respectively.

The processor is connected to the battery of the vehicle. It will be appreciated that the connections to the horn and immobilising relay are made from the processor and, if the cable link 3 between the keyboard and the processor is cut, the processor is still con nected to the immobilising relay and the horn rely. The door switch detects whether a door is open or closed and it may take the form of the courtesy light switch, which is connected to the doors of most modern vehicles.

Alternative forms of keyboard are shown in Fig. 2. In Fig. 2A, there are basically ten push-buttons labelled 0-9, a number of light emitting diodes 10 which indicate that certain operations have been made and other switches 'CL' and 'ON' which will be referred to later. In Fig. 2B, thirty six switches each carrying a reference number or reference letter are provided in addition to the LEDs 10 and the switches 'CL' and 'ON'.

Referring to Fig. 3, the device has two modes of operation, namely, an operating mode and a programming mode. The operating mode will be discussed first.

Operating Mode Referring to Fig. 4, the device has five operating states, namely, Rest state; Active state; Pause state; Triggered state; and Standby state.

Normally the device is in the Rest state and stays in this state indefinitely unless instructed to change by a signal being applied via the keyboard. If the driver of the vehicle has reason to believe that his vehicle is about to be hijacked, he simply presses a key on the keyboard a predetermined number of times, for example, the key 9 could be operated three times to give a code signal 999. Any other convenient signal could be arranged. As soon as this signal is introduced into the processor from the keyboard, the device moves to the Active state. As soon as this state is initiated, a timer is started. If the driver then appreciates that his fears were unfounded and he is not likely to have his vehicle taken from him, he stops the timer by introducing a coded signal into the comparator which is the same as the signal which has previously been stored in the memory device.

For example, this signal may consist of six digits, and, when the password has been keyed into the keyboard, the signal is compared with the stored signal in the memory and, if the two signals are the same, the timer is stopped and the device returns to the Rest state.

On the other hand, if a hijacker stops the vehicle and forces the driver to hand over the vehicle to him, the driver does not introduce the coded signal to stop the timer and the hijacker does not know that the timer has been started. Just prior to the end of a predetermined timing period of, say, three minutes, a pulsating tone is generated as a warning in case the legal driver is still in charge of the vehicle and there is still time for him to enter the correct password. If the password is not entered immediately, and assuming that the ignition switch of the engine is on, i.e. the engine is running, the device moves to the Triggered state. If the ignition switch is off, the device moves to the Pause state and, after a delay, moves to the Triggered state. In this Triggered state, the engine is immobilised.The vehicle horn is also energised to indicate to all that the vehicle has been hijacked. The vehicle re mains in this Triggered state indefinitely, un less all the doors of the vehicle are closed and the ignition switch is turned off. In this case, the device changes to the Standby state. Any further attempt to operate the vehicle returns the device directly to the Triggered state in which the engine is immobilised and the alarm is energised.

The anti-hijack device can also be used in conjunction with an anti-theft device. When the device is in the Rest state, on pressing the 'ON" switch on the keyboard, the driver of the vehicle takes the first step to use the antitheft device. One of the doors is opened to allow the driver to leave the vehicle and, when it is closed, the device changes to the Standby state. As soon as any one of the doors of the vehicle is re-opened, the device moves from the Standby state to the Pause state, whereupon a timer is started. If the correct password is introduced into the processor through the keyboard, the timer is stopped and the device returns to its Rest state.If, however, the door has been opened by an unauthorised person, it is unlikely that he will be able to introduce the correct password into the processor before the end of the predetermined time interval and, at the end of this interval, the device moves from the Pause state to the Triggered state. In this state, the vehicle is immobilised and the alarm is sounded.

Programming Mode When this anti-hijack device is installed and connected to the power supply of the vehicle, is initiates in the programming mode. In this mode, the password, which has to be determined by the user, is programmed into the device. The process of programming consists of three essential steps illustrated in Fig. 3.

The 'CL' 'switch on the keyboard is pressed to ensure the beginning of the memory file is at hand. The desired combination of letters and/ or numbers is entered into the keyboard in the correct sequence. This can be up to a total of fiteen letters and/or numbers. The 'ON' switch on the keyboard is pressed and immediately afterwards, still holding the 'ON' switch depressed, the 'CL' switch is pressed and then both are released. The password entered is then retained in the memory and the device moves to the operating mode. The password may be changed at any time and as many times as desired. In order to re-programme the device, it must be returned to the programming mode. The process involves three steps. The device is promoted to either the active, pause or triggered state, the old password is entered into the keyboard and, as soon as it is accepted and a green LED on the keyboard is activated, the 'CL' switch is pressed and held until the device acknow ledges changeover to the programming mode by transmitting a pulsed tone through the speaker. The device is now in the program ming mode and the desired new password may be programmed.

If the power supply is disconnected from the anti-hijack device, the password is retained for limited period of, say, one hour. If the supply is reconnected during this period, the operating mode is still at hand and the password still effective, If, however, the reconnection takes place after this period, the system initiates in the programming mode ready to accept the new password.

Claims

1. An anti-hijack device for a ,motor vehicle comprising a memory device containing a preset coded signal; a comparator device arranged to compare a coded signal applied thereto with the coded signal in the memory device; means for applying a coded signal to the comparator device; a circuit for immobilising the engine of the motor vehicle and/or sounding an alarm; a timer; and means for initiating the timer; the device being such that once the timer has been initiated, the circuit for immobilising the engine and/or sounding the alarm is energised after a predetermined time interval unless, in the meantime, a coded signal, which is the same as the preset signal in the memory device, is applied to the comparator device.

2. An anti-hijack device as claimed in claim 1, in which the means for applying a coded signal to the comparator device comprises a keyboard connected electrically to the comparator device.

3. An anti-hijack device as claimed in claim 2, in which the keyboard has pushbutton switches numbered 0-9, respectively.

4. An anti-hijack device as claimed in claim 2 or 3, in which the keyboard has pushbutton switches labelled A-Z, respectively.

5. An anti-hijack device as claimed in claim 2, in which the means for initiating the timer comprises one or more keys of the keyboard.

6. An anti-hijack device as claimed in any preceding claim, in which the device is such that, if at the end of the predetermined time interval the engine ignition switch has been turned off and the doors of the vehicle are closed, the circuit for immobilising the engine and/or sounding the alarm is not energised until the end of a further predetermined time interval.

7. An anti-hijack device as claimed in any preceding claim, in which the preset coded signal in the memory device can be changed by the user of the device.

8. An anti-hijack device as claimed in any preceding claim, in combination with an antitheft device.

9. The combination of an anti-hijack device and anti-theft device as claimed in claim 8, in which the anti-theft device has means by which it can be put in a standby condition when the vehicle is left with the doors closed and the engine ingition switch turned off, the device causing the circuit for immobilising the engine and/or sounding the alarm to be energised after a predetermined time perioe has elapsed if a door of the vehicle is opened and a coded signal which is the same as the preset signal in the memory device is not applied to the comparator device before the end of the predetermined time period.

10. An anti-hijack device for a motor vehicle substantially as hereinbefore described with reference to the accompanying drawings.