GB1515583A - Lamps and their manufacture - Google Patents

Abstract

1515583 Discharge lamps THORN ELECTRICAL INDUSTRIES Ltd 18 Jan 1977 [21 Jan 1976] 02357/76 Heading H1D To locate accurately the light source of a lamp, e.g. a Xe or Hg high pressure compact source discharge lamp, a tube 10, e.g. of fused silica with an obstructing web 12 is held on accurately aligned W or Mo mandrels (not shown), wound with W or Mo wire 18. The tube is heated to cause it to collapse under vacuum and grip the wires, after which the mandrels are removed and replaced by rod members 22, 23 of the same size as the mandrels, forming parts of respectively the light source structure 20 and the termination. Mo foil 24 in sheet or strips is laid on the tube, connected to the two rods by welded wires 26, and a further winding 32 of W or Mo is wound round source support rod 23 and extended back on to the Mo foil 24. The whole assembly is fitted inside an extension sleeve 28 of the fused silica lamp envelope 30 and is sealed on a lathe, the sleeve being heated to collapse under vacuum to form a seal at point X, while the wire wrap 32 allows slight sliding of source rod 23 to relieve stress. In a modification the assembly is sealed inside a separate fused silica tube (Fig. 3, not shown) which is finally sealed into an enlarged extension sleeve of the lamp envelope, the seal being near the midpoint of the tube (Fig. 4, not shown) so that the sensitive inner end lies protected within the lamp envelope; a packing piece may cover the outer end. Increased gas pressure may be tolerated in the envelope.