GB827077A - Improvements in and relating to bowl refractors for elongated light sources - Google Patents

Abstract

827,077. Luminaires. HOLOPHANE Ltd. March 1, 1957 [March 1, 1956], No. 6484/56. Class 75(2) A luminaire for use with an elongated light source has a surface consisting of two part spherical sections 11 joined by a part. cylindrical or part toroidal section 12, all three sections being generated by the same circular arc, the middle section having light controlling ribs 17 each of which lies in the trace of a point on the generating arc and the two end sections each having two sets of circular arcuate controlling ribs 16 one within the other on opposite sides of the longitudinal median plane of the bowl. The ribs may run continuously over one end section, the middle section and the other end section. The system of ribs may be completely symmetrical and may be in the form of refracting prisms on the inside surface of the bowl. Some of the prisms may be of curved cross section or may be slightly spaced apart to provide some diffusion of the light. The bowl may be continued upwards to an eliptical opening by a surface having axial prismatic ribs 15. A pair of light controlling reflector panels 22 having straight or curved prisms may be provided inside the bowl and the ends of the bowl may also carry horizontal reflecting prisms on the outside. The internal panels may be inclined to the axis of the bowl Reflectors 21 may be arranged above the light source. The bowl may be supported by a flange 14 on its rim resting on a rubber gasket 24 in a frame 25 hinged to an upper metal fitting 27 having a tubular portion at one end adapted to fit on a horizontal arm on the lamp standard, the lamp holder 35 being also mounted on the fitting 27.