This invention relates to vehicle security, and in this regard is particularly concerned with enhancing window- security of vehicles.

It is common to use laminated safety glass in vehicles to provide safety against shattering from the impact of stones and other objects thrown up from the roadway during use of the vehicle. Windows of such glass also provide resistance against attempts by persons of ill intent to break into the vehicle, but wht. eas laminated safety glass is appropriate for use for windscreens, such glass is not generally adopted for door or other wind- down windows, for safety as well as economic reasons.

More particularly, there is general acceptance in the design of vehicles that in the event of a vehicle being involved in an accident which jams the door-locks or otherwise prevents the doors being opened, it should be readily possible for occupants of the vehicle to escape through the window-apertures of the doors. Where the window cannot, because of the accident, be wound down or otherwise retracted into the door, there should be the possibility for the occupants still to make good their escape through the window-apertures in an emergency, by breaking the glass. For this reason, and also for economic reasons, it is not considered desirable to use laminated safety glass for door windows, but rather to use toughened glass that can be readily broken. The use of toughened glass instead of laminated safety glass for the door windows, thus has safety as well as economic advantage, but it has been found to offer insufficient security against attack by those of ill intent seeking to gain access to the vehicle interior; it is too easily broken.

It is an object of the present invention to provide a method for enhancing the security of a door or other wind-down window of a vehicle without prejudicing to any significant extent the ability to escape from within the vehicle, through the window-aperture.

According to one aspect of the present invention there is provided a method for enhancing the security of a door or other wind-down window installation of a vehicle, in which a plastics film is applied to the inside surface of the window glass to strengthen the glass against breaking from the outside, wherein the film is applied to cover substantially the whole of the inside surface of the glass but to leave it uncovered by the film within the bottom margin of the glass, the glass being left uncovered by the film within the bottom margin to the extent that a narrow strip of uncovered glass separates the bottom edge of the film from the holder that engages the bottom edge of the glass for raising and lowering the window.

The application of plastics film to the inside of a glass window for enhancing its security against breaking from the outside is well-known in a general context. Although the glass may be shattered by attack, the window does not yield; this is because the film holds the broken glass together within the window-aperture so that inward movement is resisted by the obstruction of glass shard upon glass shard. But if this benefit of resistance to attack is sought in the context of a vehicle by applying the film to the whole of the inside of the glass of the door or other wind-down window, break out through the window from the inside in an emergency, is made much more difficult. The film does not materially increase the force required to shatter the glass from the inside, but its presence in the window-aperture holding the shattered glass together, hampers escape.

it has been found, however, in accordance with the present invention, that the escape-difficulty created by the use of the film on the inside of the glass of a vehicle door or other wind-down window, can be overcome by leaving a narrow strip of glass uncovered above the glass holder within the bottom margin of the glass. This strip breaks when blows on the window from the inside of the vehicle shatter the film-covered glass, and because the glass of the strip is not film-covered, it allows the film with its attached glass within the window-aperture, to move slightly. This movement frees the film and glass sufficiently from the retaining channels or other surrounds of the window-aperture to allow the film carrying the glass to be pushed out safely by hand virtually in one piece from the window-aperture. The existence of the uncovered strip has not been found to affect materially the resistance of the window to attack from the outside.

According to another aspect of the invention there is provided a vehicle door or other wind-down window installation of a vehicle in which a plastics film adheres to the inside surface of the window glass to strengthen the glass against breaking from the outside, wherein the film covers substantially the whole of the inside surface of the glass apart from within the bottom margin of the glass to the extent that a narrow strip of uncovered glass separates the bottom edge of the film from the holder that engages the bottom edge of the glass for raising and lowering the window.

The separation of the bottom edge of the film from the holder in the method and installation of the invention may be substantially between 0.125 inch and 0.25 inch (3.175 mm and 6.35 mm) , and the film may be of micro- porous plastics material. Furthermore, the film may be a multi-ply polyester laminate, and may have a thickness

within the range of 0.001 inch to 0.012 inch (0.0254 mm to 0.3048 mm) .

A method, and a motor-vehicle door window installation, in accordance with the present invention, will now be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a side view of the vehicle-door installation from the inside of the vehicle, with the door-trim removed;

Figure 2 is an end elevation of the door installation of Figure 1, partly broken away;

Figure 3 is an enlarged view of part of the window of the door installation of Figure 1, from the inside; and

Figure 4 illustrates in end elevation, a detail of the top and side edges of the window of Figure 1.

Referring to Figures 1 and 2, a window-aperture l of the door is defined by a frame 2 that is of channel section for guiding and restraining the glass window 3 at its top and side edges. The window 3 is carried by a channel- section holder 4 of a wind-down mechanism 5 mounted within the body 6 of the door.

The window 3 with its bottom edge 7 slotted tightly into the holder 4, extends upwardly within the body 6 to project through a top opening 8 of the body 6 into the aperture 1. Resilient fillets 9 bear on the inner and outer surfaces of the window 3 to maintain a water-tight seal of the opening 8 irrespective of movement of the window 3 up and down within the aperture 1. The window 3, which is shown in the fully closed condition, is

driven up and down by operation (mechanical or electrical) of the mechanism 5.

As illustrated more clearly in Figures 3 and 4, the inside surface of the glass sheet 10 forming the window 3 is covered almost completely by a film 11 of transparent, micro-porous plastics material. The film 11 is a multi¬ ply polyester laminate having a thickness of 0.006 inch (0.1524 mm) such as marketed by Madico, Inc as their product LCL-600-XSR, and is bonded firmly to the inside surface of the glass sheet 10 using an acrylic pressure- sensitive adhesive.

The film 11 covers the whole of the inside surface of the glass sheet 10 to within some 0.125 inch to 0.25 inch (3.175 mm to 6.35 mm) of the top of the holder 4. The inside surface of the glass sheet 10 within the window- aperture 1 is in this way wholly covered by the film 11, and the only part of the sheet 10 that is left uncovered is at the bottom margin of the window 3 within the door- body 6. More particularly, the bottom edge 12 of the film 11 is spaced from the top of the holder 4 so as to leave a narrow strip 13 of uncovered glass directly above the holder 4.

Resistance of the window 3 to attack from the outside is enhanced significantly by the film 11 to the extent that the glass sheet 10 as covered on the inside by the film 11 will withstand blows from a hammer or other hand- carried implement with greater shatterproof-strength and for very much longer than otherwise would be the case. Nonetheless, blows applied from within the vehicle on the inside of the window 3 within the window-aperture 1, are effective to allow the window 3 to be pushed out and enable escape through the aperture 1. More particularly, when the glass within the aperture 1 of the window is shattered by the blows from the inside, the glass of the

strip 13 just above the holder 4, breaks too. The remainder of the window 3 is in consequence free to move downwards slightly, so that by pushing it outwardly within the aperture 1 it is released to a large extent from the frame 2. In this condition it is free to buckle outwardly and to be pushed out by hand clear of the window-aperture 1. The film 11 holds the shattered glass together as one, for increased safety.

The film 11 is readily applied to the window glass of the doors of newly-manufactured vehicles or by way of a service to owners of existing vehicles. In order to facilitate application, the film 11 is supplied already backed with a pressure-sensitive adhesive, so that after being cut to size it is ready for direct application to the inside surface of the glass window-sheet 10. The glass sheet 10 is cleaned thoroughly before application of the film 11, and all air and water trapped between the sheet 10 and film 11 is squeezed out to ensure that visibility through the window is unimpaired and that the film 11 remains strongly bonded to the glass sheet 10 in all conditions.

As indicated in Figure 4, the edge of the film 11 is bevelled along the top and sides of the window 3, in line with the bevel of the glass sheet 10. However, the edge of the film 11 may be set back slightly, say by about 0.04 inch (1 mm) or so, from the top and side edges of the glass sheet 10 on the inside surface, so as to leave a small margin of the inside surface of the glass sheet 10 clear of the film 11 at these edges within the channelling of the frame 2. This does not materially affect the resistance of the window to attack.

The film 11 may be clear or tinted, and in the latter case enables the advantages of tinting to be readily achieved with otherwise clear-glass windows.