GB472240A - Improvements in cathode ray tubes - Google Patents

Abstract

472,240. Cathode - ray tubes; television. NAAMLOOZE VENNOOTSCHAP PHILIPS' GLOEILAMPENFABRIEKEN. March 20, 1936, No. 8398. Convention date, June 14, 1935. [Classes 39 (i) and 40 (iii)] The picture screen consists of highly refractory metal, such as molybdenum or tungsten, having a thickness less than 20 Á and disposed without a backing in a cathode-ray tube so as to be struck and brought to incandescence by the cathode-ray. The screen consists of a plate 6 Á thick or a gauze of braided wires or parallel wires 8 on a frame 9. High potentials of the order of 10,000 volts are used and the ray may be accelerated between the anode and the screen. To avoid difficulties due to the production of ions, a directly heated cathode of tungsten or thoriated tungsten may be used instead of an indirectly heated cathode. The picture is so brilliant that it can be projected on an enlarged scale; a green filter may be arranged in the projection system to absorb red rays. Protective constructions known in X-ray apparatus may be adopted in view of the high voltages and the possible production of X-rays. Specifications 452,368 and 452,406 are referred to. The Specification as open to inspection under Sect. 91 comprises also screens of other refractory material, such as porcelain. This subject-matter does not appear in the Specification as accepted.