GB382159A - Improvements in light reflectors - Google Patents

Abstract

382,159. Reflectors. GENERAL ELECTRIC CO., Ltd., Magnet House, Kingsway, London.-(Assignees of Patent- Treuhand-Ges. fur Elektrische Gluhlampen; 11, Ehrenbergstrasse, Berlin.) Feb. 9, 1932, No. 3865. Convention date, March 27, 1931. [Classes 75 (ii) and 75 (iv).] The middle part a of a reflector is parabolic in cross section, and the outer part c, which has within its rim b an annular source of light or several sources of light arranged in a circle concentric with the axis of the reflector, is substantially elliptical in cross section, so that rays of light from the source are directed mainly into the focus f of the central parabolic part. As shown in Fig. 3, the outer part c is formed by the rotation of part of an ellipse, with one focus at f and the other at g, about the axis d, f. An annular luminous electric discharge tube h is located at the focal circle g. Two annular reflectors k, k<1>, shaped as parts of ellipsoids having their upper foci respectively at gl, g2, and their lower foci coincident at f, may, as shown, be placed in front of the outer edge of the main reflector, with associated annular sources of light h<1>, h2. In the form shown in Fig. 4, the upper part of the reflector is formed as several ellipsoidal members n placed obliquely to the axis f, d. Electric incandescent lamps o are arranged at the upper foci g. The annular discharge tubes may be replaced by smaller discharge tubes or several curved tubular incandescent lamps. For example, two discharge tubes may emit red light, and two blue light, the tubes being arranged alternately in a complete circle. In the form shown in Fig. 8, the vertex of the parabolic part a is replaced by a smaller parabolic reflector q with a white or coloured incandescent lamp r. A discharge tube emit. ting red light may be used, thus giving a red beam with a white core.