GB404222A - Improvements in electric incandescent lamps - Google Patents

Abstract

404,222. Electric incandescent lamps with internal screens. GENERAL ELECTRIC CO., Ltd., Magnet House, Kingsway, London.-(Assignees of Patent-Treuhand-Ges. f³r Elektrische Gl³hlampen ; 11, Ehrenbergstrasse, Berlin.) July 11, 1933, No. 19650. Convention date, July 28, 1932. [Class 39 (ii).] In an electric incandescent lamp for a motor car headlight, of the type having a screen under one filament so that when the lamp is mounted-within a reflector the light emi ted from it is confined to less than a hemisphere opaque means are provided for intercepting the direct rays from this filament which otherwise would pass upwardly and outwardly near the upper front edge of the reflector, but not intercepting the reflected rays therefrom passing downwardly near the lower front edge of the reflector. The opaque means may comprise part of the screen 10 mounted under the auxiliary filament 9, but preferably consists of an approximately crescent - shaped opaque coating 12 on the lamp bulb, with its straight base parallel to or coincident with the horizontal middle plane of the lamp, the area covered being sufficient to screen off the cone a of direct rays from the auxiliary filament 9 without materially affecting the beam from the main filament 8. To increase the " near " beam from the auxiliary filament the front wall of the screen 10 may be provided with a small aperture below the tongue 11 to enable a beam b of direct rays to be emitted. The upper half of the bulb may be provided with a transparent coloured, for example yellow, coating 14 which may be applied as described in Specification 246,985, [Class 39 (ii), Electric lamps, Incandescent], the base of the area coated preferably being above the middle plane of the lamp. Specification 210,105, [Class 39 (ii), Electric lamps, Incandescent], is also referred to.