GB381142A - Improvements in electric incandescent lamps, electric discharge devices and the like - Google Patents

Abstract

381,142. Electric incandescent lamps and discharge devices with cut-outs. GENERAL ELECTRIC CO., Ltd., Magnet House, Kingsway, London.-(Assignees of Patent-Treuhand-Ges. f³r Elektrische Gl³hlampen; 11, Ehrenbergstrasse, Berlin.) June 30, 1932, No. 18513. Convention date, July 1, 1931. [Class 39 (ii).] In electric incandescent lamps, or electric discharge devices such as enclosed arc lamps, thermionic valves, rectifiers, or X-ray tubes, wherein the parts 7<1>, 8<1>, of the leading-in wires 7, 8 sealed into the pinch 9 of the foot-tube 3 have a coefficient of expansion substantially the same as the coefficient of expansion of the glass of the foot-tube and have a smaller cross section than other parts of the leading-in wire, the part 8<1> of smaller cross section is extended within the foot-tube to serve as a fuse. The leading-in wire may comprise a copper-sheathed nickel-iron wire, of which the portion forming the fuse is about half the diameter of the remainder, or the portion forming the seal wire and fuse may consist of a homogeneous wire, for example of platinum. The portion of a sheathed wire forming the fuse may have the sheath removed locally by melting or erosion to reduce the current intensity at which the fuse blows.