Motor vehicles – With means for promoting safety of vehicle – its occupant or... – By preventing unauthorized or unintended access or use
Patent
1990-08-03
1992-04-14
Rice, Kenneth R.
Motor vehicles
With means for promoting safety of vehicle, its occupant or...
By preventing unauthorized or unintended access or use
307 102, 340426, B60R 2504, G08B 2900
Patent
active
051039320
DESCRIPTION:
BRIEF SUMMARY
THIS INVENTION relates to a security system for an environment.
FIELD OF THE INVENTION
In this specification the term "environment" shall be taken to include buildings, motor vehicles, boats, caravans, safes, and any other article to which a security system would be appropriate.
BACKGROUND OF THE INVENTION
There are many situations where it is desirable to inhibit unauthorised entry to, or unauthorised use of, environments such as buildings and motor vehicles. In the case of motor vehicles, ignition keys provide a basic level of security but they are not entirely satisfactory in that they can be easily circumvented to allow the engine of the vehicle to be started. There are proposals which provide an additional level of security, such proposals incorporating another form of security device in the motor vehicle such as a valve in the fuel supply line or a switch in the electrical wiring controlling the operation of the engine. For convenience, such other security devices are generally controlled by a solenoid or other switching device such as an electronic security alarm system, which can be energised or otherwise operated from a battery in the electrical system of the vehicle. While the presence of such other security devices does afford some additional security protection to the vehicle, it is still possible for the wiring of the control circuitry of such other security devices to be rearranged so as to actuate the solenoid or other switching device thereby to disarm the security system and to allow the engine to be started. Similar considerations apply to electronically controlled security locks for doors in environments such as buildings and safes.
The security devices described above are vulnerable because they operate at voltage levels which are available from the normal power supplies derived in the environment, such as a twelve volt supply typically used in the engine operating control circuit of motor vehicles. This normal power supply can therefore be used to facilitate disarming of the security device.
SUMMARY OF THE INVENTION
The present invention seeks to overcome the disadvantage described above by providing a security system which can only be disarmed using a voltage level which exceeds the voltage level normally derived from the environment in which the security system is installed.
In one form the invention resides in a security system for an environment from which a power supply at a first voltage level is derived, said security system comprising disarming means responsive only to a voltage level exceeding said first voltage level for disarming the security system and means for generating a second voltage level which exceeds said first voltage level and to which said disarming means is responsive.
Preferably, said disarming means comprises a solenoid, said second voltage level constituting an actuating voltage for actuating the solenoid and said first voltage level constitutes a holding voltage for holding the solenoid in an actuated condition upon termination of the second voltage.
Preferably said means for generating the second voltage level comprises a first electrical circuit to be energised by said power supply.
Preferably, said first electrical circuit includes a capacitor which is adapted to store charge while the security system is armed to provide a stored charge at said first voltage level, said capacitor being adapted to selectively deliver said stored charge in series with said first voltage level to provide said second voltage level for disarming the system.
Preferably, said power supply is derived from a second electrical circuit and switch means are provided for energising said first and second electrical circuits. The switch means may comprise a first switch incorporated in the first electrical circuit and a second switch incorporated in the second electrical circuit.
For the purpose of enhancing the level of the security, the first switch may in one arrangement be operable only in response to input of a valid security code into the security system. In this connect
REFERENCES:
patent: 4673914 (1987-06-01), Lee
patent: 4682062 (1987-07-01), Weinberger
patent: 4690240 (1987-09-01), Russo
patent: 4745897 (1988-05-01), Teseda
patent: 4888575 (1989-12-01), De Vauix
patent: 4901054 (1990-02-01), Waterman
Charters John D.
Hansen Niels K.
Myers Holdings Pty. Ltd.
Rice Kenneth R.
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