GB504783A - Improvements in and relating to electric discharge devices - Google Patents

Abstract

504,783. Thermionic valves; valve circuits. BRITISH THOMSON-HOUSTON CO., Ltd. Oct. 22, 1937, No. 28892. Convention date, Oct. 22, 1936. [Classes 39 (i) and 40 (v)] In a gas or vapour filled valve the control electrode 17 between the anode 6 and cathode 7 is shielded by a pair of independent tubular members 23, 24 which enclose the entire discharge space and are provided with apertured baffles 26, 27. The members 23, 24 are supported from the tube stem 2 by means of conductive supports 28-31 carried by rings 33, 34 whereby suitable potentials may be applied thereto; if the member 24 is slightly positive with respect to the cathode while the member 23 is at a still higher potential, the discharge may be initiated on the application of a critical voltage to the electrode 17 irrespective of the voltage on the anode provided this is above a minimum value. This critical voltage may be made dependent on the light on a photo-electric tube 48 in a bridge 50 connected to the electrode 17. In a modification, the side walls 55, 56, Fig. 2, of the vessel form the tubular members carrying the baffles 64, 65 ; the walls are united by an insulating ring 57 sealed to the tubular members. The bias potentials are taken from a potentiometer connected to a transformer 70, the potential being limited by a glow discharge lamp 81. A trigger voltage may be applied by any device 76 to raise the negative bias in the control electrode 59. Specifications 282,712, [Class 39 (i)], 386,376, 445,593 and 473,666 are referred to.