GB438227A - Improvements in incandescent cathodes particularly for gasfilled discharge tubes - Google Patents

Abstract

438,227. Thermionic cathodes. NAAMLOOZE VENNOOTSCHAP PHILIPS' GLOEILAMPENFABRIEKEN, Emmasingel, Eindhoven, Holland. Aug. 16, 1934, No. 23668. Convention date, Sept. 7, 1933. [Class 39 (i)] To obtain large emissive surface on cathodes for use in gas filled discharge tubes the cathode may be formed from a strip 1, Fig. 1, in the form of a comb which is rolled up a number of times around a central rod 3, Fig. 2, the teeth 2, &c., being coated with emissive material ; the strip 1 may be of tungsten and the teeth of nickel. A heater wire 4 also oxide coated surrounds the rolled up body, the strip being welded to one lead 6 to form the cathode lead. In another form a corrugated sheet 9, Fig. 4, is welded to a backing band 8 and then rolled up about a central rod the whole being coated. Such a body may be enclosed in and heated by a directly-heated, helical cathode 12 consisting of two tungsten wires 13, Fig. 5, surrounded by nickel wire, the whole being nickeled and coated with emissive material. The rolled body 9 is spaced from the helical body 12 by four insulating tubes 18, through which lead wires 19 may be threaded to make contact between the upper end of the band 8 and the central rod 10, which acts as the cathode lead. Specification 421,280 is referred to.