GB751468A - Electrically conductive windshield - Google Patents

Abstract

751,468. Electrically heated windscreens. LIBBEY-OWENS-FORD GLASS CO. Nov. 22, 1954 [Dec. 1, 1953], No. 33664/54. Class 39(3). A windscreen for a motor car comprises a glass sheet with a substantially flat central part e substantially covered by a transparent coating 20 forming . an electric heating resistance terminating inwards of the end parts g of the windscreen, which are bent back, current being led to the coating by electrodes 21 along opposite margins of the coating: Two strips 21 of electrode material e.g. a silver flux are applied to a flat glass sheet inwards of two opposed edges, and the sheet is moved on a monorail into a furnace where it is heated almost to fusing point e.g. 1250‹F. to bake on the electrodes, and a solution of tin chloride is sprayed on to the hot glass to form a uniform coating of tin oxide. After cooling, the coated sheet is preferably matched with a second uncoated flat glass sheet to form a laminated sheet and carried on a mould into a furnace where the glass sheets are supported at opposite edges and sag into the mould to a shape shown in Fig. 5 and allowed, to cool slowly to anneal the glass. After cutting the glass to shape so that the electrodes are at the edges, the coating is removed at the bent ends e.g. by rinsing with chemicals. Where the electrodes converge towards a tapered end of a windscreen at j, Fig. 10, the coating is given a concave edge 44 to ensure even heating of the coating. Alternatively the whole windscreen may remain coated, except for a narrow passage across the screen at the ends of the electrodes, so that no current can pass into the coated end portions. The electrodes terminate inwardly of the bent ends of the windscreens, but when the coating is wholly removed at these ends, the electrodes may extend to the extremities of the windscreen at the same or opposite ends for connection to the current supply. A thin strip of coating may be removed centrally across the glass to divide it into two portions and the corresponding central parts of the electrodes are also removed, so that each portion may be independently supplied with current e.g. through rheostats. Two glass sheets, one coated, may be laminated with a bonding layer of thermoplastic, and the uncoated sheet is either slightly narrower than the coated sheet to allow a current lead to be soldered to the exposed electrodes, or the uncoated sheet is notched at its inner edge to allow attachment of leads in parallel to an electrode. The windscreen is mounted in a continuous groove '52 in a rubber or like channel 53, through which the current leads 61 pass and may be soldered to a flat metal plate 59, which is pressed by a bowed leaf spring 60 located in the bottom of the groove 52. In this case the electrode is extended at 58 to the outer edge of the coated sheet by applying a similar material to the edge of the glass continuously or at spaced points.