GB692299A - Improvements in and relating to electric incandescent lamps - Google Patents

Abstract

692,299. Electric incandescent lamps. BRITISH THOMSON-HOUSTON CO., Ltd. Jan. 17, 1952 [Jan. 25, 19511, No. 1376/52. Class 39(ii) In an electric incandescent lamp of the sealed beam type comprising a glass reflecting portion 2 and a cover glass 3 fusion-sealed together at their rims 4, 5 respectively, the leading-in wires 13 to the filament 14 are sealed within the fused seal of the rims and are made sufficiently rigid to provide filament-supporting portions 18 at their inner ends, which terminate within a pair of indentations 19 formed in the surface of the reflector 9. The leading-in wires are preferably of the composite or multi-section type comprising inner and outer portions 15, 16 of relatively inexpensive metal such as iron or nickel-plated iron butt-welded to an intermediate portion 17 of tungsten or molybdenum, or ironnickel-cobalt alloy or a nickel-iron or chrome-iron alloy, which comprises the sealed portion. The parts 2, 3 comprising the envelope are of pressed glass and formed with upstanding annular sealing ridges 6, 7 around the rims 4, 5 to facilitate. their subsequent fusion together, the portions into which the leading-wires are sealed being preferably formed with cooperating grooves 23, 24 providing a passage conforming to the cross-section of the intermediate portion 17 of the wires. The ends of the filament 14 may be either welded to the leading-in wires 13 or clamped within loops formed in the leading-in wires or in the upper ends of separate vertical supporting-braces to which leading-in wires are welded. To facilitate manufacture the mount 12 may be formed as a unit with a transverse insulating bridge or tie member 21 secured by end wires 22 to the vertical braces 18.