Automotive Windshield

The present invention relates to a windshield for automotive vehicles which comprises on its external side in the area wiped by the wiper blades one or more scraping edges for the wiper blades. The scraping edges may advantageously consist of enamel-type material which may be intimately bonded to the windshield glass surface by screen printing. Varying amounts of metal particles may be added to the enamel in order to make it conductive and available to be connected to the electrical system of the vehicle to thaw accumulated ice and snow.

The improved automotive windshield of the present invention is not only useful for cleaning windshield wiper blades during use, it is also useful to thaw snow or ice which has accumulated on the lower part of the windshield thereby freeing the windshield wiper of such impediments.

The present invention relates to a windshield for automotive vehicles. More particularly, the present invention relates to a windshield for automotive vehicles having one or more scraping edges to remove dirt particles from the wiper blades. Heretofore, windshield constructions which sought to incorporate a windshield wiper blade cleaning feature, formed scraping edges through the means of grooves approximately 2 mm. wide and 1 mm. deep which were ground into the glass plate. The purpose of the scraping edges formed by the grooves of the prior art was, as in the present invention, to remove from the wiper blades the dirt particles and water adhering to them. This ensures on the one hand that the area wiped by the windshield blade is not continually made dirty again by the dirt and water adhering to the wiper blade. In addition, the grooves greatly reduced the danger of damage to the glass surface which is due to the fact that the dirt particles are frequently hard and granular substances which adhere to the wiper blades and roughen the surface by a grinding action. New dirt particles adhere to such roughened and scratched surfaces which, together with the roughness, cause dispersion of light at the windshield. Of course, dispersion phenomena reduce the distance of perception during night travel. It was possible to largely eliminate or at least greatly reduce these disadvantages by providing a scraping edge formed by grooves for the wiper blades.

However, the grinding of a groove into the glass surface in order to provide a scraping edge not only involves considerable costs in labor, it also has the additional disadvantage that it considerably reduces the strength of the windshield. In certain glass types, for example thermally or chemically prestressed glass plates, it is not possible at all to grind such grooves after the plates are finished, because this would result in the total destruction of the glass plates.

It is the purpose of the invention to design a windshield of this type in such a manner that it can even be made from prestressed glass plates and that no substantial weakening of the surface takes place. These ends are effected by having the scraping edges formed by strip-shaped profiles which are provided on the surface of the glass plate in raised form.

The present invention will now be described in more detail in conjunction with the figures wherein:

FIG. 1 is a view of a windshield according to the invention with schematically shown windshield wipers;

FIG. 2 is a cross section along line II--II of the windshield shown in FIG. 1;

FIG. 3 is a cross section through another embodiment of a windshield according to the invention;

FIG. 4 is another embodiment of the geometric shape as a profile;

FIG. 5 is the view of a windshield in which the profiles forming the scraping edges serve simultaneously as heating conductors;

FIG. 6 is the view of a windshield comprising separate profiles for the wiping edges and for the heating conductors;

FIG. 7 is a plate comprising profiles for subsequent installation on a windshield; and

FIG. 8 is a further embodiment of a windshield according to the invention.

FIGS. 1 and 2 show a windshield 1 of laminated glass which is installed in window frame 2 of the car body. The car body comprises wiper arms 3 supporting wiper blades 4, here shown in the rest position. On the exterior side of the glass surface strip-shaped profiles 5 are located above the rest or parked position of the wiper blades 4. The length of these profiles 5 is approximately equal to the length of the wiper blades 4. They are arranged in the shape of a roof and each partial section encloses such an angle with the horizontal that on one hand the wiper blade forms an acute angle with the profiles when it passes over the profile and on the other hand the angle is sufficient to let the water scraped from the windshield wiper run off easily to both sides. As shown, the scraping edges of the profiles have the form of an inverted V with an obtuse angle included between the two arms of the inverted V.

Cross section and dimensions of profiles 5 are shown in FIG. 2. It can be seen, in particular, that the cross section of the profiles is wedge-shaped or sawtooth-shaped, with the surface forming the scraping edge itself approximately perpendicular to the surface of the glass plate. The height H of the profiles is approximately 1 mm, the width B approximately 2 to 3 mm, and the distance A between the perpendicular surfaces of two parallel profiles approximately 10 mm.

The purpose of the invention can be achieved without the windshield wiper blades passing over the scraping edge in each cycle of movement. It is, for example, quite sufficient if the windshield wiper blades pass over the scraping edges only after a certain number of cycles. A control circuit, not shown, for the wiper movement can be provided for this purpose which ensures that in a normal cycle the wiper blade reverses direction above the scraping edge without passing over or touching this edge and that it passes the scraping edge only in each tenth cycle.

FIG. 3 shows an embodiment in which below two profiles 5 whose inclined surface is sloped upward there is provided another profile 6 whose inclined surface is sloped downward. In this manner a discharge channel 7 for the water scraped from the wiper blades is formed between the lower of the two profiles 5 and profile 6. The scraping edge formed by profile 6 ensures that, when the wiper blade moves downwards, the dirt adhering to its lower surface is removed from the wiper blade, while it is the purpose of the scraping edges formed by profiles 5 to remove, when the wiper blade moves upwards, the dirt adhering to the upper surface of said wiper blade and to flush this dirt from the wiper blade with the aid of the water dragged along by the wiper blade.

In principle the profiles may also have other geometrical shapes. They may, for example, be straight or curved over their entire length. Care must only be taken to ensure that the profile is positioned at a sufficient angle with the horizontal to facilitate the running off of the water which has been removed from the wiper blade. In the embodiment shown in FIG. 4, three profiles 10 are placed one above the other, which are essentially straight-lined and comprise merely at one end a section 10' with the opposite slope.

Profiles 5 and 10 consist of enamel-type material intimately bonded to the glass surface. Such materials, commercially available under the description "ceramic baking enamels", are applied in the form of paste to the cold glass plate by means of a suitable process. Screen printing has proved to be a suitable application process, for example. The desired cross section of the profiles is achieved by suitable design of the screen printing template or by printing several layers on top of each other. The applied enamel paste is dried and then baked at high temperatures. As temperatures of approximately 580.degree. to 650.degree. C. are required for the baking enamels, the baking is preferably done in connection with the heating which is in any event required for the bending and/or prestressing of the glass plates. A suitable baking enamel with a baking range between 580.degree. and 620.degree. C. is, for example, obtainable from BLYTHE COLOURS B.V. under catalog number 39.269/5/63.

Enamels made conductive by containing varying amounts of metal particles may also be suitable as materials of the profiles. Profiles 13 may therefore be applied as continuous conductors extending over the entire width of windshield 12, as shown in FIG. 5. At their lateral ends the profiles 13 are connected to bus bars 14 which are connected to the electrical system of the vehicle by suitable connectors. In the embodiment shown in FIG. 5, three profiles 13 placed parallel to each other are electrically connected in parallel and thus form a narrow heatable area over the entire width of the lower part of the windshield which is used to thaw the snow accumulating on this part of the windshield i.e., to free the windshield wiper by thawing the snow.

FIG. 6 shows a different embodiment in which there are provided in the lower part of the windshield, in the area of the rest position of the wipers, heating conductors 17 which are electrically connected with each other and with the connectors 20 connecting them with the electrical system of the vehicle by the wider connector sections 18, 19. Profiles 21 are located above the heating conductors 17 in a roof-like arrangement, which profiles have only the function of acting as scraping edges for the wiper blades. This design ensures that the water removed by profiles 21 can run off the profiles without interference.

In the embodiment shown in FIG. 7, profiles 23 with wedge-shaped cross sections are integral parts of a plate 24 which is subsequently attached as a whole to the windshield. Plate 24 with profiles 23 may, in particular, consist of a sufficiently hard transparent plastic. Plate 24 is glued to windshield 26 by means of adhesive layer 25.

It is particularly advantageous to provide the strip-shaped profiles according to the invention in the lower area of windshields used on car bodies where the lower part of the windshield is hidden by the engine hood. In such recessed windshields the wiper, too, lies in its rest position below the level of the hood. In this arrangement the strip-shaped profiles according to the invention can be placed so low on the windshield that they are covered by the hood and are not visible.

FIG. 8, finally, shows partly as a view, partly in cross section another embodiment of a windshield comprising an electric heating device in its lower part in order to free by heating the wiper located there, when it is frozen so that it cannot move or when snow has accumulated there which interferes with the movement of the wiper. In this design an imprinted strip baked onto the glass plate and consisting of a conductive silver compound is used as heating conductor 31. In order to protect heating conductor 31 and simultaneously make the glass plate opaque in this area, a layer 32 consisting of an opaque ceramic baking enamel which absorbs radiant heat is applied over heating conductor 31 in a relatively wide area as described in German Patent Application No. P 29 02 748. The black baking enamel obtainable from BLYTHE COLOURS B.V. under catalog number 39.269/5/63 is again used as baking enamel. It is applied by screen printing. In the same printing operation used for applying layer 32, profiles 33 and 34 are applied, which form the scraping edges for the wiper blades. Lower profile 33 is joined to layer 32 without interruption. As a result of this design a run-off surface for the water scraped off by the scraping edge of profile 34, which causes the water to flow to the side to a point outside the area wiped by the wiper blade.