GB543499A - Improvements in electron discharge tubes - Google Patents

Abstract

543,499. Cathode-ray tubes and circuits therefor; television. BRITISH THOMSON-HOUSTON CO., Ltd. Sept. 9, 1940, No. 14028. Convention date, Sept. 9, 1939. [Classes 39 (i), 40 (iii), and 40 (v)] [Also in Group XVIII] The light elements of large surfaces for reproducing, on a magnified scale and by electrical means, a light image, particularly in colour, of a remote object, comprise an envelope 10 with an elongated cathode 12, an anode 11 of sector shape, a number of mica discs 13, 14 dividing the space between the cathode and anode, and separate control grids 16, 17, 18 controlling the discharge independently in the different compartments of the envelope. The inner surface of the anode is coated with materials which fluoresce, preferably in different colours, under electron bombardment. An accelerating electrode 21 2 preferably in the form of a helix, is provided common to all the compartments. A modification is described in which the anode is of conical shape and faces the flat or convex end of a similarly shaped envelope. The lighting elements are assembled to form a large display board, and the control potentials are applied to the grids 16, 17, 18 by the circuit shown in Fig, 4. Impulses corresponding to the light and shade of the object to be reproduced are applied to the grids of amplifying valves 32, 33, 34, the output of which is applied to the corresponding lamp control grids. The duration of luminescence in each lamp section is increased by condensers 36, 37, 38 in series with the amplifier grids.