GB770549A - Improvements in or relating to electric lighting fittings for street lighting - Google Patents

Abstract

770,549. Reflectors for street lamps. GENERAL ELECTRIC CO., Ltd. Aug. 12, 1955 [Aug. 17, 1954], No. 23931/54. Classes 75(2) and 75(4) In an electric lighting fitting for street lighting of the kind comprising a pairof reflectors 2 equally spaced on either side of a light source 1 to provide a light distribution in vertical planes having on each side of the fitting a peak of intensity in a preferred direction, for example 20 degrees below the horizontal, with the light intensity falling off at'smaller angles to a negligible value at 10 degrees below the horizontal, the upper parts of the reflectors 2 are curved concavely in vertical sections to direct light into or below the preferred directions and the lower part of each reflector is formed as a skirt 4 which in vertical sections is everywhere substantially flat or slightly convex and the tangent to the upper end of which makes a greater acute angle with the vertical than does the tangent to the upper part of the reflector where it adjoins the skirt. The light reflected by the skirts is directed below the preferred directions. The upper parts of the reflectors are made of vertically fluted silvered glass and are concave in horizontal planes with curvatures which would produce, with smooth surfaces, parallel light distributions. Each skirt 4 comprises a plane strip of polished metal bent into polygonal form to conform substantially to the horizontal curvature of the upper part of the reflector and is attached by clips to the inside surface of the lower rim of the upper part of the reflector. In a modification the skirt is formed integrally with the upper part of the reflector and has a concave curvature in horizontal planes corresponding to the curvature of the upper part. The flutes on the upper part are continued to the lower edge of the skirt.