GB854263A - Improvements in and relating to lighting appliances incorporating light controlling plates - Google Patents

Abstract

854,263. Street lighting fittings; reflectors. HOLOPHANE Ltd. Nov. 21, 1956 [Nov. 22, 1955], No. 35604/56. Classes 75(2) and 75(4). A lighting fitting, especially for street lighting comprises a compact light source and a reflecting plate of transparent material having prismatic reflecting ribs on its back surface of curvedcontour and such that light incident on the active faces of the prisms is redirected into a beam, the major axis of which lies in a preferred direction, the light source being located relatively close to the plate but at a distance from its front surface not less than half the minimum dimension of the plate. Where two plates are used, one on each side of the light source, their width may be chosen so as to avoid mutual interference with the reflected rays. In order to utilize light falling beyond the edges of the plates, these may be extended by straight or curved pieces having parallel horizontal prisms to re-direct the light downwards. To avoid interference of the light beam by the source, e.g. a fluorescent lamp bulb, the faces of the plates opposite to the source may be provided with vertical prisms to spread the light laterally. Fig. 11 shows a form of lamp having a fluorescent bulb 1 carried in a casing 6 closed by end plates 8. A metallic reflector 5 is carried on the top of the casing, below which are two reflecting plates 2 having a pattern of circular prisms 3 on the side remote from the bulb 1. Parallel vertical prisms 3<SP>111</SP> are provided on the side of the plates facing the bulb to divert the reflected light to either side of the bulb. The lamp holder may be carried by a movable support 18 and the fitting mounted on a light standard by stirrups 17.