GB436060A - Improvements in or relating to electric discharge devices - Google Patents

Abstract

436,060. Thermionic valves. STANDARD TELEPHONES & CABLES, Ltd., 63, Aldwych, London.-(Assignees of Rockwood, G. H.; 563, Argyle Avenue, Orange, New Jersey, U.S.A.) March 18, 1935, No. 8352. Convention date, Oct. 3, 1934. [Class 39 (i)] In a discharge tube having an ionizable filling such as argon at 0À25 mm. pressure and comprising an equipotential cathode 15, and a cylindrical control electrode 28 surrounding the cathode and having a perforation 29 therein opposite which a rod anode 32 is positioned, a deionization electrode 35 surrounds the cathode and is operated with a momentary large negative bias from a low impedance source. This electrode 35 may be formed of turns spaced apart about 0À5 mm. or a close mesh grid may be used. The electrode 28 controls the initiation of the discharge and may be included in a high impedance circuit ; it is supported from the pinch by a rod 26, which from its upper end carries a glass bead 25 which supports the upper end of the cathode and also the electrode 35. A second bead 40 also supported on the rod 26 supports the electrode 35 at its lower end. A support wire may extend from the bead 25 to the anode, whose lower end is encased in a glass shield 34 to prevent electron flow from the lower end of the cathode. In a modification, wherein two anodes having different breakdown characteristics are used-this being effected by having apertures 48, 49, Fig. 4, in the control cylinder of different sizes-the electrodes are spaced by two mica discs 53, 54. The two metal rod anodes 55, 56 are fixed to the upper disc by eyelets 57. The cylindrical control electrode 47 is supported by two rods 51 fixed to the pinch and welded to the electrode ; one of these rods is connected to a contact prong 14. The leads for the filament heater are enclosed in a bell-shaped shield 62. The deionization electrode 66 is supported by wires 77. U.S.A. Specification 1,921,004 is referred to.