GB420922A - Improvements in street lighting apparatus - Google Patents

Abstract

420,922. Prismatic refractors for street lamps. HOLOPHANE, Ltd., and ENGLISH, S., Holophane House, Elverton Street, Vincent Square, London. July 5, 1933, No. 19089. [Class 75 (ii)] A dish-refractor 1, shown in Fig. 1 and adapted to be positioned beneath the light source of a street - lamp, is provided with a series of radial prisms 5 arranged about predetermined axes to produce an asymmetric distribution of light in horizontal planes, combined with concentric horizontal prisms 4, which are so arranged and of such strength that light which would normally fall in the region of the lamp, is spread to greater distances from it. Similar light distribution may alternatively, as shown in Figs. 5 and 8, be effected solely by series of arcuate lenticular lenses 6, which lie in parallel planes and are provided on one surface of a dish refractor. When radial and horizontal prisms are used, the two sets may be formed, as shown, on one piece of glass, or separately on two pieces. In the case of a refractor used in a gas lamp, a slot 7 shown in Fig. 7, is provided to facilitate the removal of the refractor. The refractor shown in Fig. 8 may be used in combination with the dome refractor 8 of Specification 380,318. Specifications 235,797 and 285,327, [both in Class 75 (ii)], also are referred to.