| 摘要 |
640,475. Elongated-lamp fittings. BRITISH THOMSON-HOUSTON CO., Ltd., and SHURMER, H. V. Nov. 7, 1947, No. 29720. [Classes 75(ii) and 75(iv)] In a lighting fitting comprising two parallel elongated light sources 6, 7 arranged in a vertical plane one of the light sources 6 is disposed between an upper trough-like reflector 9 of arcuate section and a lower trough-like reflector 10 of inverted V section made reflecting on both its upper and lower surfaces and the second light source 7 is disposed within the lower reflector, the arrangement effecting a complete cut-off of the light flux at substantially 85-90 degrees to the downward vertical. The sides of the V-shaped reflector 10 are curved to provide a partparabolic section so that the upper surfaces of the reflector 10 and the arcuate reflector 9 together form a pair of substantially parabolic trough-like reflectors 1, 2 arranged back to back and having coincident focal lines 3. The upper and lower halves of these parabolic reflectors 1, 2 need not be parts of the same parabola or have their axes in the same direction. Specification 621,716 is referred to. |
