GB462470A - Improvements in and relating to electric discharge lamps - Google Patents

Abstract

462,470. Discharge lamps. BRITISH THOMSON-HOUSTON CO., Ltd. Sept. 14, 1935, No. 25559. Convention date, Sept. 15, 1934. [Class 39 (i)] A glow-discharge lamp comprises indirectlyheated electrodes arranged in an envelope which is heated uniformly by a surrounding ballast resistance connected in series with the electrode heaters and housed in a second envelope. A lamp 10, Fig. 1, is provided with hollow nickel electrodes 22, coated internally with barium oxide, the heaters of which are connected in series by a molybdenum wire 24. A surrounding evacuated envelope 12 comprises a glass base 14 having nipples to which tubular terminals 16 are fused. The supporting conductors 17, 18 are secured to the terminals. The lamp 10 is supported on the conductor 17 and is registered at the other end by a leading-in wire 21 which engages in a nipple 28 in the outer envelope. A coiled tungsten filament 11 is supported by wires fused into glass beads which are supported through anchor wires by wires 26 secured to the leading-in wires through glass buttons 27. One end of the filament is connected to the conductor 18 and the other end is secured to one of the wires 26 which is connected to the leading-in wire 21. In a modification, a zigzag filament is supported by bent hooks fused into the glass buttons 27. In a further form, a coiled filament is supported by anchor wires fused into a glass tube 33, Fig. 3, which is spaced from the envelope 12 by springs 38 and from the envelope 10 by springs 37. The filling may consist of one or more of the metals sodium, cadmium, and mercury, together with a rare gas. The lamp may operate at a temperature of 250‹ C. and may be housed in a light-diffusing globe or the envelope 12 may be frosted. An incandescent filament may be used. U.S.A. Specification 1,956,591) is referred to.