GB317833A - Improvements in and relating to multiple filament incandescent lamps - Google Patents

Abstract

317,833. British Thomson-Houston Co., Ltd., (Assignees of Severin, C.). Aug. 23, 1928, [Convention date]. Multiple-filament lamps; making lamps.-Two filaments 20, 21 of high candle-power are arranged at equal distances from the base of the bulb and a third filament 22 of low candle-power is placed nearer to the base and approximately in the plane of one of the main filaments, with which it may be connected electrically in series. The main filaments may be in parallel planes, as shown. Also, in a bulb having at least three filaments, they are supported by two pairs of leading-in conductors 12 sealed into the stem and arranged parallel and equally spaced from each other in the pinch. The parts may be assembled in a stem-making machine of the kind described in Specification 223,204, the pinching-jaws 13, 14, Fig. 4, being shaped to form a cruciform pinch about the four wires 12, as shown in Fig. 2. The position of the exhaust aperture through the pinch, in a stem of the kind described in Specification 147,293, is determined by a lug 16 on the jaw 14. Since the filaments 20, 21 lie on opposite sides of the axis of the bulb, the bulb socket 42 of the lamp reflector 41, Fig. 12, is made eccentric with respect to the axis thereof to enable the filament 21 to lie at the focus and in the axis of the reflector. Three unequallyspaced cap pins are provided on the base to ensure the correct positioning of the filaments. Specification 303,114 also is referred to.