GB575175A - Improvements relating to incandescent electric lamps - Google Patents

Abstract

575,175. Incandescent lamps. SIEMENS ELECTRIC LAMPS & SUPPLIES Ltd., and ALDING- TON, J. N. Feb. 11, 1944, No. 2592. [Class 39 (ii)] A brilliant light source for an incandescent lamp comprises a number of separate but electrically and mechanically similar helically coiled filaments 19 lying co-planar with one another between a pair of conductors 8, 9 to which the ends of the filaments are connected. each helix being so arranged that equipotential points on neighbouring filaments may be in contact as shown in Fig. 2. The filaments may be of the single coil or coiled-coil variety. The pitch of the filament helix, where it comprises a single coil or the secondary helix of a coiled-coil filament preferably lies between 115 per cent. and 190 per cent. of the diameter of the single coil or of the diameter of the primary helix of the coiled-coil. The ends of filaments are secured to the conductors 8, 9 by spot welding, or by means of clamping members 11 or 12, Figs. 2, 3 and 4. For long filaments, an intermediate support may be provided, consisting, e.g., of a wire helix of which the indivdual turns are interlinked with equipotential points on the filaments. This helix may be supported at intervals on a metal rod. A mirror may be formed on the interior of the lamp to produce an image adjacent to, and appearing as a continuation of the source. Groups of co-planar filaments may be arranged at desired angles to one another to emit light in different directions. A gas filling with a mixture of gases to provide high thermal conductivity may be used according to the Provisional Specification.