GB962630A - Improvements in or relating to high pressure mercury vapour electric discharge lamps - Google Patents

Abstract

962,630. Discharge lamps. GENERAL ELECTRIC CO. Ltd. Sept. 29, 1961 [Sept. 2, 1960], No. 30344/60. Heading H1D. A high-pressure mercury vapour discharge lamp of the type having a quartz or hard glass envelope supported within a sealed glass outer jacket, the inner surface of the outer jacket being preferably coated with fluorescent material, is manufactured by heating the envelope and its associated support means to a temperature of not less than 400‹ C., preferably at 600‹ to 700‹ C. for about 30 seconds, in a non- oxidizing atmosphere, preferably forming gas comprising a mixture of three volumes of nitrogen and one volume of hydrogen, immediately prior to their mounting and sealing within the outer jacket. The heating step is stated to remove surface films of grease and other contaminations which adhere to the outer surface of the discharge envelope and its associated support means during manufacture. The outer jacket can be evacuated or filled with a non-oxidizing gas such as nitrogen. The lamp can be as described in Specification 828,020, having a tubular quartz discharge envelope supported between mild steel holders attached to iron support wires which are welded to nickel support wires set into the pinched end of a boro-silicate glass foot-tube through which are sealed tungsten leads to the envelope electrode seal conductors, and an auxiliary electrode resistor mounted on a mica disc secured to the support wires near the pinch, the pinch being provided with an exhaust tube and the foot-tube being sealed into a glass outer jacket coated internally with fluoroescent material.