GB761180A - Method of manufacturing the screen structure of cathode ray tubes - Google Patents

Abstract

761,180. Colour television tube screens. PHILCO CORPORATION. July 9, 1954 [July 10, 1953], No. 20159/54. Drawings to Specification. Class 39(1). The indexing strips of a colour television tube are applied to the conductive layer of the screen by first depositing thereon a film of organic material and subsequently heating to vaporize it. Two methods are described. In the first the colour fluorescent strips are applied to the glass substrata preferably by a photographic method as described in Specification 713,908 an organic film e.g. of nitrocellulose, plasticizer, octyl acetate, water soluble alcohol and a volatile ester, is allowed to spread over it and when sufficiently tacky the conductive film is formed thereon by evaporation e.g. by heating a thin aluminium filament or by sputtering. A film of organic lacquer is sprayed or flowed onto the conductive film, applying as little pressure as possible. The material is the same as for the previous lacquer step but with more plasticizer and no alcohol. The plasticizer may be di-2- ethyl butyrate-triethylene glycol and iso-amyl acetate. The indexing strips are deposited by the same photographic method as for the phosphor strips using the same mask and exposing through the overlying phosphor and conductive films with a sufficiently intense illumination. The assembly is finally dried and baked to remove the organic materials. In the second method, a binder is applied with the phosphor materials and there is an intermediate baking step, i.e. after depositing the aluminium and before applying the second organic film, which may therefore be of low viscosity. The indexing strip may be of material with a high secondary emission e.g. the oxide of magnesium, barium, strontium or calcium or magnesium orthosilicate ; or of a luminescent material. Specifications 732,565 and 753,442 also are referred to.