GB798724A - Improvements in or relating to image converting devices - Google Patents

Abstract

798,724. Photo-electric devices. GENERAL ELECTRIC CO., Ltd. April 12, 1956 [April 18, 1955], No. 11113/55. Class 37. [Also in Group XL (a)] An electroluminescent device for converting cathode - rays, X - rays, ultra-violet and infra-red radiations into visible light comprises a first insulating layer 1 of glass or synthetic resin having a multiplicity of small holes 3 formed therein, the walls of which consist of photo - conductive material 7, e.g. selenium, antimony trisulphide zinc lead or cadmium sulphide or cadmium selenide, and an electroluminescent layer 5 extends over the ends of holes 3, with or without an opaque insulating or conducting intermediate layer 6, e.g. black cellulose paint. The phosphor is powdered copper activated zinc sulphide. A transparent conducting layer or grid 4 on a glass plate 2 covers the layer 5 and a similar conducting coating 8 is formed over the apertured plate 1. If the coating 8 is apertured, it may be of opaque conducting material, e.g. aluminium. The end of each photo-conductive cell near the electroluminescent layer may be surrounded by conductive material which is insulated from the other conductive deposits. The apertures 3 may be frusto-conical, dome- or trumpet-shaped and they are formed in the glass plate by coating with layers of wax and fishglue/ammonium bichromate respectively, exposing through a suitable negative, washing to remove unhardened fishglue, dissolving away the wax at the exposed places and etching the glass at these points with hydrofluoric acid. If the plate is of synthetic resin the holes are formed by pressing. The photo-conductive material is deposited in the holes by thermal evaporation. The electroluminescent material may be deposited as a, mosaic as dots corresponding to the apertures.