GB561281A - Improvements relating to metal vapour electric discharge lamps - Google Patents

Abstract

561,281. Glass manufacture. SIEMENS ELECTRIC LAMPS & SUPPLIES, Ltd., ALDINGTON, J. N., and MEADOWCROFT, A. J. Nov. 24, 1942, No. 16605. [Class 56] [Also in Group XXXVI] For attaching a fabricated hermetic seal 7, 8, 9, 10, 11, 12; Fig. 5, for supplying current to the electrodes 2, 3 of an H.P.M.V. or similar lamp, to the bulb 1 of the lamp, the tube 7 of the seal is blown to form a bulb 16 and the bulb is ground in a plane 7, Fig. 1 (not shown), to form an annular section of the same size as a similar section formed by grinding off a tubular extension 14 in the bulb 1. The ends of the tube 7 and bulb 1 are then mounted about a vertical axis and pressed together while being heated during rotation. The tube 7 and bulb 1 are of the same thickness and if necessary extra molten quartz can be added to the join to correct for inequalities of thickness so that the finished article will be substantially equal thickness throughout and so will have no great variations in temperature likely to cause breakage. The electrodes 2, 3 are mounted eccentrically of the bulb also to cause equalisation of the heating. The bulb 16 may be blown of oblate form and the planes at which the grinding of adjacent faces of the parts 1, 16 meet may be inclined so as to produce surfaces meeting at an acute angle, the angular space being filled up with molten quartz. In another form the bulb 16 is so formed that the inside of the cut flared part coincides with the inside of the annular section of the bulb 1, but the outer section of bulb 1 overlaps that of the bulb 16. The tube 7 of the seal envelopes the rod 8 of the anode 2 and the tube 7 is expanded at 9 to form a hermetic seal comprising foils 10 of molybdenum sealed between the expansion 9 and an inner quartz tube 11. The foils 10 are connected by a stout strip 12 of refractory metal to the source of current.