GB856930A - Improvements in or relating to information storage devices - Google Patents

Abstract

856,930. Coating by vapour deposition. SOC D'ELECTRONIQUE ET D'AUTOMATISME S.A. March 4, 1957, No. 7080/57. Class 82(2) [Also in Groups XXXVI and XL(a)] An information storage element comprises an electroluminescent and visible-light luminescent layer 1 and a photoresistive layer 2 between a pair of translucent electrodes 3 and 4. The material of the luminescent layer 1 can be a complex of oxides and/or sulphides, e.g. zinc oxide actuated by samarium oxide. The material of the photo-resistive layer 2 can be silicon, germanium or tin oxide or antimony oxide. The electrodes 3 and 4 can be film deposits of aluminium. In making the storage element a film of aluminium is formed by an evaporation process in vacuum on a plate of high melting point glass and a plate bearing a coating of antimony is placed opposite the film. The coating of antimony can be formed by evaporation into the plate in a vacuum of, e.g. 10-4 mms., from crucibles arranged at the four apices of a virtual surface parallel to the plate. An oxygen atmosphere is established under a constant low pressure and a D.C. voltage applied across the antimony-supporting plate and the aluminium film to form a layer of antimony oxide on the aluminium film. The antimony-coated plate is replaced by a plate coated as above described with an alloy of zinc and 1% samarium and the discharge process repeated to form on the layer ofantimony oxide a layer of zinc oxide activated by samarium oxide. A further aluminium film is evaporated on to this layer. A raster generator is made by depositing on a supporting plate, of a high melting' point dielectric material, such as glass, ceramics or enamelled metal. a network of conductors by a serigraphy process (through a silk screen) by painting with a mixture of pulverulent silver and enamel of low melting point in an essential, oil, and heating the plate in a H.F. induction oven. The conductors are then thickened by a rhodium deposition and optically polished. A layer of luminescent material comprising zinc oxide and 1% of copper oxide is formed over the network by the process previously described. A further conductor network is deposited on the luminescent layer by evaporating thereon a continuous film of aluminium and photo-etching the film.