GB2357541A

GB2357541A - Automotive glazing assembly with hydrophobic coating

Info

Publication number: GB2357541A
Application number: GB9930319A
Authority: GB
Inventors: Paul Arthur Holmes
Original assignee: Pilkington PLC
Current assignee: Pilkington Group Ltd
Priority date: 1999-12-22
Filing date: 1999-12-22
Publication date: 2001-06-27
Also published as: GB9930319D0

Abstract

A glazing assembly primarily for use in an automotive vehicle in conjunction with a wiper blade assembly, the glass [1] being provided, on its outer surface, with a hydrophobic coating [3] extending throughout the vision area and, in use, being swept by a reciprocating wiper blade assembly comprising one or more wiper blades [5] wherein the reversing points of the blade or blades lie outwardly of the hydrophobic coating [3].

Description

i 2357541 GLAZING ASSEMBL1 The present invention relates to a glazing

assembly for use in automotive vehicles. The assembly is primarily, but not essentially, intended for use in the front or rear windscreens of such vehicles.

It is known to provide sheets of glass with hydrophobic coatings, that is to say, with coatings which repel water. Such sheets have been used in the side windows, usually referred to as sidelights, of vehicles. Ideally, they would be employed in the front andlor rear windscreens as well. However, such coatings tend to have associated therewith problems of durability. This is accentuated by the fact that the coating is usually very thin - of the order of 30 nanometers.

The front windscreen and, in many cases, the rear windscreen of vehicles are swept by wiper blades. The blades adversely affect the durability of the coating, particularly in the regions in which the direction of travel of the blades is reversed. After a period of time, the wiper blade at least partially removes the coating layer and this tends to occur initially at the reversing points. This leaves a permanent mark on the windscreen which is unacceptable to the driver of the vehicle and, since it is a foreseeable problem, is usually unacceptable to the vehicle manufacturer. Moreover, such mark or marks are generally within the field of vision of the driver of the vehicle and can easily cause him or her to be distracted.

The windscreens of most motor vehicles are provided with an obscuration band or bands. This is usually either a strip extending all around the periphery of the windscreen or one or more strips extending along one or more edges of the windscreen. It is basically an ink, usually black, which is applied by screen-printing or any other suitable means. The purpose. of such band is twofold. Firstly, most windscreens are mounted in the vehicle by means of an adhesive. The opacity of the band protects the adhesive from attack by ultraviolet radiation. The other main reason for the provision of an obscuration band is aesthetic. The presence of such band means that the occupants of the vehicle cannot see the flange in which the windscreen is mounted or the adhesive used to attach the windscreen to the flange. Additionally, the obscuration band serves to conceal from view from the interior of the vehicle such components as bus- bars which are used to provide electrical current for such accoutrements as a heater for a front or rear windscreen.

2 The present invention seeks to provide a glazing assembly suitable for use as a windscreen in a vehicle in which the glazing is coated with a hydrophobic coating but in which the durability of the coating is not adversely affected by the action of wiper blades.

According to the present invention, there is provided a glazing assembly comprising at least one sheet of glass provided, on one major surface thereof, with a continuous hydrophobic coating extending throughout the vision area, the at least one glass sheet being, in use, swept by a wiper assembly having at least one reciprocating wiper blade, wherein the reversing points at the ends of the travel of the at least one wiper blade lie outside the coated area, and wherein each wiper blade, at its reversing points, lies substantially parallel to one or both of the lower edge and one of the side edges of the sheet of glass.

It has surprisingly been found that, by adopting such an arrangement, the removal of the hydrophobic coating by the wiper blade or blades is substantially n-iinimised. Ibis clearly prolongs the life of the hydrophobic coating and also means that the driver of the vehicle is not distracted by having portions of the glass, in his field of vision, covered by the hydrophobic coating whilst other areas are free from such coating because it has been removed. At this point, it should, perhaps, be pointed out that when water impinges on a sheet of glass which is provided with a hydrophobic coating, the water forms discrete droplets which are easily removed by the airflow over a moving vehicle, leaving a clear windscreen which the driver can see through. Without such coating, the water forms into a distorting film of variable thickness which is not removed by the airflow and which substantially reduces the clarity of vision.

In a preferred embodiment of the present invention, the sheet of glass is provided, around at least a portion of its periphery and on the same surface as the hydrophobic coating, with at least one obscuration band, the reversing points being located in the obscuration band.

In one embodiment of the present invention, the hydrophobic coating and the obscuration band overlap one another. In such a case, the reversing points are located in the obscuration band but externally of the hydrophobic coating.

3 However, it is preferred if the hydrophobic coating and obscuration band abut, but do not overlap, one another. In such a case, the reversing points for the wiper are located in the obscuration band. In either of these two cases, the hydrophobic coating may be applied to the glass by any suitable means such as dipping with the region which is not to be provided with such coating being masked or plasma etched or otherwise being obscured.

The glass to which the hydrophobic coating and, if present, the obscuration band, is applied may be a single sheet or a sheet assembly such as a laminate. It will be readily apparent that, in such a case that the coating and obscuration band must be provided on the surface which, in use, forms the external surface of the glass.

The invention will be further described, by way of illustration only, with reference to the accompanying drawings, in which:- Figure 1 is a view of a first embodiment of a glazing assembly in accordance with the present invention in the form of a windscreen used in conjunction with a single wiper blade; and Figure 2 is a view similar to Figure 1 of a second embodiment of a glazing assembly in accordance with the present invention in the form of a windscreen used in conjunction with two wiper blades.

In Figure 1, there is shown a windscreen generally referenced 1. Around the periphery thereof is an obscuration band 2. The obscuration band is in the form of an ink which is applied to the glass in a manner well known in the art. The obscuration band 2, which is well known in the art, is opaque and has two major effects. Firstly, it prevents the occupants of the vehicle from seeing the mounting of the windscreen in the body of the vehicle and also hides from view components such as electrical bus- bars which act as conductors for other accessories, such as heaters, which are not relevant to the present invention. Secondly, the ink is selected so as to have ultraviolet radiation absorbing properties such that the adhesive used to bond the windscreen in place does not degrade when the vehicle in which the windscreen is mounted is used.

The external surface of the glass 1 is provided with a hydrophobic coating 3. Such coating is of a known composition and the outermost surface thereof is a fluoroalkylalkylsilane. The coating 3 extends up to, but not into the obscuration band 2 4 and is continuous. In the context of the present invention, "continuous" means that the coating has no gaps in it.

A wiper assembly including a wiper blade 5 which has two reversing positions 5a and 5b, both of which lie adjacent the lower edge 6 of the windscreen 1. It will be observed that the positions 5a and 5b are both located in the obscuration band 2. In other words, they are located outwardly of the hydrophobic coating 3. By providing such an arrangement, the life of the hydrophobic coating is substantially extended.

A slightly modified embodiment is shown in Figure 2 in which like reference numerals are used to denote like parts. However in this arrangement, two wiper blades 7 are employed, one of which is not shown for the sake of clarity.

In this embodiment, the wiper blades are mounted so that each has a first reversing position 7a which lies adjacent a lateral edge 8 of the windscreen 1 and the other reversing point lies adjacent the lower edge 6 of the windscreen. Moreover, the hydrophobic coating 3, in this embodiment, extends into the obscuration band 2. It will, however be noted that the reversing points 7a and 7b, although lying in the obscuration band 2, lie outwardly of the hydrophobic coating 3.

It will be readily apparent to those skilled in the art that various minor modifications can be made to the present invention without departing from the scope thereof Thus, the arrangement shown in Figure 1 could be simply altered so that the two wiper blades described with reference to Figure 2 are provided. Similarly, the Figure 2 embodiment can also be used in combination with a single wiper blade of the type shown in Figure 1. Still further, the obscuration band shown in Figures 1 and 2 extends completely around the periphery of the windscreen. It may, if desired only extend along the two side edges of the windscreen or even be omitted completely. Furthermore, if an obscuration band or bands are provided, the hydrophobic coating and the obscuration band or bands may overlap or abut one another irrespective of the number of wiper blades employed.

Claims

1. A glazing assembly comprising at least one sheet of glass provided, on one major surface thereof, with a continuous hydrophobic coating extending throughout the vision area, the at least one glass sheet being swept, in use, by a wiper assembly having at least one reciprocating wiper blade, the reversing points at the ends of the travel of the at least one wiper blade lying outside the coated area and wherein each wiper blade, at its reversing points, lies substantially parallel to one or both of the lower edge and one of the side edges of the sheet of glass.

2. A glazing assembly as claimed in Claim 1 in which the sheet of glass is provided, around at least a portion of its periphery, with at least one obscuration band, the reversing points being located in the obscuration band.

3. A glazing assembly as claimed in Claim 2 wherein the hydrophobic coating and obscuration band overlap one another.

4. A glazing assembly as claimed in Claim 2 wherein the hydrophobic coating and at least one obscuration band abut one another.

5. A glazing assembly as claimed in any preceding claim in which the hydrophobic coating is applied to the glass by dipping with the region not to be coated being masked or plasma etched.

6. A glazing assembly as claimed in any preceding claim in which the glass is a laminated windscreen comprising an inner glass sheet, an interlayer and an outer glass sheet, the hydrophobic coating being provided on the outer major surface of the outer glass sheet.

7. A glazing. assembly as claimed in Claim 1 substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.