GB1049627A - Miniature incandescent electric lamp and method of its manufacture - Google Patents

Abstract

1,049,627. Casting composite contacts for electric lamps; moulds. PATENT-TREUHAND - GESELLSCHAFT FœR ELEKTRISCHE GLœHLAMPEN m.b.H. Sept. 1, 1965 [Sept. 1, 1964], No. 37346/65. Heading B3F. [Also in Divisions H1 and H2] An electric lamp, Fig. 1 (not shown), with an elongated glass envelope 1, has the lead-in conductor at one or both ends formed as a small metal tube 3 sealed into the glass envelope, the tubes being pinched off and further sealed by a bead 4 of solder given a cone shape to form a base contact. In making the lamp, a mount, Fig. 4 or 5 (not shown), consisting of a tungsten filament 2 extending between two copper tubes 3, is introduced into the envelope through openings in the ends while it is held in rotating jaws 7. The upper end is then sealed and the upper tube is moved downwards to form a recessed surface at the end of the envelope 1, Fig. 9 (not shown). The lower end is then similarly sealed and formed with a recess. The ends of the glass envelope may also be formed by tools to have small indentations 16, 16<SP>1</SP>, Figs. 7, 8 (not shown). After pinching off the tubes a ring of solder, Fig. 10 (not shown), is placed round the preheated and fluxed end of each tube 3 and melted into the recess and indentations. A mould, Fig. 12 (not shown), with cooling-air ducts 23 and having a conical inner surface connected to a vacuum channel 22, is then applied to the end for forming the solder.