GB499120A - Improvements in and relating to electric lamps - Google Patents

Abstract

499,120. Two-part couplings ; uniting metal to vitreous material by heat. BRITISH THOMSON-HOUSTON CO., Ltd. May 20, 1938, No. 15132. Convention date, May 22, 1937. [Classes 36 and 38 (i)] [Also in Group XL] A tubular lamp of the general type described in Specifications 428,414, [Group XI], 452,191, and 485,329, [Group XL], has the end caps made in two or more concentric portions insulated from one another and having their outer surfaces forming a substantially smooth continuation of one another, so that a filament electrode can be connected from one to another of the portions, or, for a multiple filament lamp, filaments may connect the corresponding portions at opposite ends of the lamp. The portions consist of a disc 11 and ring 12 of a chromium iron, or iron nickel cobalt alloy sealed together by a ring 15 of glass and sealed to the end of the tube 10 of the lamp. Supports 16, 17 attached to the disc and ring carry a coiled coil tungsten filament 18 with the primary mandrel in place and coated with barium or strontium oxides. An evacuation orifice 19 is sealed by glass 20. The tube may contain neon or argon and a small quantity of mercury 21, and may be coated with fluorescent zinc or cadmium silicate, or calcium tungstate. The disc 11 and ring 12 may be stamped from a single sheet, the glass from the end of the tube 10 serving to seal them together, and a ring being stamped out between their adjacent edges so that when they are arranged as a smooth surface the insulation bridges the gap between them. Specification 439,593, [Group XI], also is referred to.