GB679219A - Improvements in or relating to electric incandescent lamps and fittings therefor - Google Patents

Abstract

679,219. Vehicle headlights; incandescent lamps. PHILIPS ELECTRICAL INDUSTRIES, Ltd. April 6, 1950 [April 13, 1949], No. 8764/50. Classes 39(ii) and 75(iv) In an electric incandescent lamp 3 comprising a filament 5 and a screen 6 inside the bulb adapted to prevent radiation of light from the filament to one-half of the space surrounding the lamp an outer corrector screen 13 in the form of an opaque strip covers the bulb where the latter is intersected by the plane through the filament and the edge of the inner screen 6, or in a projector lamp, such as a vehicle headlight, having an incandescent lamp with a filament in a non-focal position in a reflector and a screen inside the bulb for preventing escape of light to one-half of the space around the lamp an outer corrector-screen prevents escape of light in the plane passing through the edge of the inner screen and the filament; the outer correctorscreen in both cases corrects any maladjustment in the relative positions of inner screen and filament. The latter alternative form of the invention is exemplified by a headlight comprising a reflector, a front glass and an incandescent lamp with an unscreened filament at the focus of the reflector and a screened filament in a non-focal position to give a dipped beam, and the outer corrector-screen is constituted by either an opaque strip applied to the front glass or a non-reflecting strip applied to the reflector along a horizontal meridian. The incandescent lamp 3 exemplifying the first form of the invention is fitted into the reflector 1 of a headlight so that the main filament 4 is at the focus and the screened filament 5 is in front of the focus and above the reflector axis. The corrector-screen 13 is formed by covering the bulb with a stencil and spraying with paint or lacquer or by sticking a strip of opaque material to the bulb or by soldering the ends of a metal strip curved around the bulb to the bulb cap 14 or to the reflector; the width of the corrector-screen preferably does not exceed one-fifth or one-tenth of its spacing from the filament. The part of the corrector-screen which intercepts forwardly-directed non-reflected light may be omitted. A ring for attaching the bulb to its holder is positioned accurately relative to the filaments and then soldered to the bulb cap.