GB498092A - Improvements relating to incandescent electric lamps - Google Patents

Abstract

498,092. Electric incandescent lamp filaments. DYCK, A. VAN. Nov. 18, 1937, Nos. 31749 and 31750. Convention dates, Nov. 18, 1936 and Oct. 29, 1937. [Class 39 (ii)] Illuminating bodies or filaments are made by coiling helically into compact shape a long thin sleeve or tube having its walls formed of a number of fine wires of refractory metal, woven, plaited, or braided together. For example the wires may be plaited upon a mandrel, preferably of cylindrical cross-section, and then coiled helically upon a secondary mandrel, these mandrels consisting of brass, copper, steel or molybdenum, so that either or both of them may be removed chemically or otherwise, in known manner, after completion of the filament. Alternatively the mandrels may consist of infusible and refractory materials, e.g. asbestos, which are bad conductors of electricity but adapted to emit luminous radiation. The fine wires or component elements of the metal sleeves may be of circular, oval, rectangular, or other cross-section. The example shows a method of forming a metal sleeve by winding wires 1, 2 along parallel helices upon a mandrel a with wires 3, 4 along parallel helices of opposite hand to the first two, these pairs of helices crossing one another. When completed the wires form a closely plaited sheath upon the mandrel, as shown in Fig. 2.