GB496662A - A luminous screen for cathode ray oscillographs and methods of making the same - Google Patents

Abstract

496,662. Cathode - ray tubes. FISCHER, F., and LATTMANN, M. June 3, 1937, No. 15456. Convention date, June 4, 1936. Drawings to Specification. [Class 39 (i)] An incandescent screen comprises a mosaic layer which, to obtain low thermal conduction, is arranged on an organic cell-structure composed of a material of high melting point. Organic tissue, e.g. elder pith, is boiled in a solution of sodium tungstate, tungsten oxide is precipitated by adding a suitable precipitant, and the tissue is submitted to slow combustion to form a cell-structure of tungsten oxide which is reduced to tungsten by heating in hydrogen. The cell-structure may consist of carbonized velvet, or of tungsten or tantalum or carbides thereof. A reduced copy of a drawing of the mosaic screen may be prepared on a metal or cellulose plate in such manner that a depression is produced which corresponds to each mosaic element. A paste containing the material of the mosaic is placed in the depressions. The plate is then placed on the cellstructure and is removed by etching, treatment in a gas or by evaporation to leave the paste which is reduced to metal by heating in hydrogen. The screen is bombarded by electrons to sinter the mosaic elements and to evaporate a part of the cell-structure between the mosaic elements to increase the thermal insulation therebetween.