WO1997008025A2

WO1997008025A2 - Anti-theft device

Info

Publication number: WO1997008025A2
Application number: PCT/GB1996/002056
Authority: WO
Inventors: Jeffrey Moss Woolf
Original assignee: Jeffrey Moss Woolf
Priority date: 1995-08-23
Filing date: 1996-08-23
Publication date: 1997-03-06
Also published as: WO1997008025A3; GB9517232D0; AU6827396A

Abstract

A windscreen for a motor vehicle which incorporates over all or part of the windscreen, an electrochromatic material which renders all or part of the windscreen opaque when a sensor is activated by unauthorised entry or excessive disturbance. Preferably the window is kept transparent by means of an electric current flowing through the eletrochromatic part of the windscreen and optionally only part of the windscreen is rendered opaque to spell out a warning message.

Description

Anti-Theft Device

This invention relates to a device for improving the safety of motor vehicles to make them more difficult to steal.

Many devices have been disclosed for the prevention of the theft of vehicles. These devices usually comprise alarms, car immobilising devices or improved locks. However, all these devices can be circumvented, after which the vehicle can be driven away without it being noticeable to other road users that the vehicle has been stolen.

I have now invented a device which identifies a stolen vehicle when it is being driven.

According to the invention there is provided a windscreen for a motor vehicle which windscreen comprises, over at least part of its area, transparent material which is rendered opaque by the variation of an electric current passing through the said material, the electric current being controlled by a sensor which is activated by unauthorised disturbance of the vehicle whereby the transparent material is rendered opaque.

Materials which change their transparency to light as the consequence of passing an electric current through them are generally known as electrochromatic materials. One type of this material is in the form of an electrochromatic glass which comprises a laminate of glass interlayered with a crystalline or microcrystalline compound which changes its opaqueness on the passage of an electric current, one form of this type of material is commercially available under the Registered Trade Mark 'Priva-Lite'. This is a laminated glazing composed of two or more high-grade panes interlayered with 'Taliq' liquid crystal film and is supplied by Glaceries de Saint-Roch S.A.

In electrochromatic material the degree of transparency can be altered by passing an electric current through it. In the device of the present invention the material is preferably set up so that it is transparent as long as the current flows through i.; however, when the current is turned off, the material becomes opaque. The entire windscreen can be made of electrochromatic material and, if desired, the material can be incorporated as part of a laminated windscreen.

As the voltage required by the electrochromatic material is less than one volt and is normally of the order of a few milli-volts, the material can be connected to the car electrical circuit without any problems or alternatively it can have its own power source e.g. from a battery. The connections can be made using conventional electrodes.

The sensor can be any of the conventional sensors used in car alarm systems which can be activated by excessive disturbance to the vehicle or by any unauthorised entry into the vehicle. Unlike alarm systems which, even if noticed, can be turned off by breaking the circuit, the present device will render the windscreen opaque until the electric current is restored, which is more difficult to accomplish than turning off or disconnecting a circuit.

The only effective method of disabling the device and enabling a thief to drive the vehicle is for the thief to break the windscreen which would immediately be apparent and would indicate that the vehicle has been stolen.

In a variation of the invention and to provide a safety feature in case the device of the present invention is accidentally activated, there can be a small porfon of t'.ie windscreen which could stay transparent to enable a driver to see. The fact that the rest of the windscreen is opaque would be sufficiently obvious to indicate that the vehicle was being drive by an unauthorised driver. However, if a laminated windscreen is used in the vehicle then the electrochromatic material can be incoφorated in the windscreen in such a way that the words "stolen" or some other word can appear when the device is activated.

There can also, or alternatively, be a hidden secondary power source which coi'ld be activated in case of accidental triggering of the device so that the windscreen can be reset to transparent.

The device of the present invention can be incorporated in a vehicle when it is manufactured or it can be added later as a replacement windscreen. The incorporation ofthe windscreen ofthe present invention would mean that a car thief would have difficulty in driving away quickly and unobtrusively, because he would clearly not wish to draw attention to himself by driving a car with a broken windscreen or a windscreen which showed that the car had been stolen.

In an alternative embodiment of the invention, all the windows of a vehicle are made of an electrochromatic glass which is rendered opaque when the car is locked and not in use. When the ignition is turned on the windows become transparent. This means that the interior of a parked car cannot be seen, so a casual thief would not be able to see possessions or a radiocassette etc. inside a car. By use of suitable connections, by passing the ignition switch e.g. b" "hot wiring" the car would not render the glass transparent and is an extra security feature.

This embodiment would also help keep the interior of a vehicle cool in strong sunlight.

As well as use as a windscreen where it is most effective the device of the present invention can also be used with another window to indicate that the vehicle has been stolen, although this would normally only be useful for windows that cannot be wound down e.g. rear windows.

Claims

1. A windscreen for a motor vehicle which windscreen comprises, over at least part of its area, transparent material which is rendered opaque by the variation of an electric current passing through the said material, the electric current being controlled by a sensor which is activated by unauthorised disturbance of the vehicle whereby the transparent material is rendered opaque.

2. A windscreen as claimed in claim 1 in which substantially the entire windscreen is made of an electrochromatic material.

3. A windscreen as claimed in claim 1 in which a part of the windscreen is composed of an electrochromatic material.

4. A windscreen as claimed in any one of claims 1 to 3 in which the electrochromatic part of the windscreen comprises two or more sheets of glass interlayered with an electrochromatic crystal film.

5. A windscreen as claimed in any one of the preceding claims 1 to 4 which is substantially transparent whilst an electric current flows through the electrochromatic part of the windscreen and when the current is turned off, that part ofthe windscreen becomes substantially opaque.

6. A vehicle in which there is a windscreen as claimed in any one of claims 1 to

5.

7. A vehicle as claimed in claim 6 in which there is a power source independent of the car ignition or battery which provides the electric current to the electrochromatic part ofthe windscreen.

8. A vehicle as claimed in claim 6 or 7 in which the sensor is activated by excessive disturbance to the vehicle or by any unauthorised entry into the vehicle

9. A vehicle as claimed in any one of claims 6 to 8 in which some or all the windows of a vehicle are made of an electrochromatic material.