| 摘要 |
767,952. Street lamp reflectors. HOLOPHANE, Ltd. Dec. 6, 1954 [Sept. 4, 1953], No. 24528/53. Classes 75(2 )and 75(4) A refractor for use e.g. in a street lamp with a short tubular light source, e.g. 2 to 5 inches with a refractor 12 inches long, or with a small number, e.g. 2 or 3 individual sources mounted close together in line, the light source axis being horizontal, is of closed form, e.g. barrel shaped, about the light source axis and has axial prisms for controlling the light distribution in vertical planes and at least one band of vertical prisms for redirecting the light making a small angle with said axis into a direction at a greater angle. As shown, the vertical prism bands 21 are on the external surface of the barrel-shaped refractor and the axial prisms, Fig. 3 on the internal surface. With a plurality of light sources LC, there may be additional bands of vertical prisms between each two adjacent sources. The lowest zone on the external surface of the refractor may have a band of longitudinal or circumferential doublereflecting prisms, in the latter case for throwing light to the side of the street. The bands of vertcal prisms 21 may be on the internal surface and the longitudinal prisms on the external surface. The axial internal prisms, Fig. 3, from the line 25 downwards, are of increasing strength as their distance from line 25 increases so as to elevate the light falling upon them. From line 25 upwards the prisms refract the light down wards and increase in strength as their distance from line 25 increases, so that light emitted by the source or sources below an angle of, say 75 degrees from the nadir is elevated to redirect it along the street, while light emitted by the source or sources above the horizontal and just below the horizontal is depressed into useful directions. The prisms in the lower part of the upper zone from line 25 are preferably of curved contour. Above the line 26 beyond which no useful redirection of light can be effected by refracting prisms an internal reflector 27, Fig. 3 may be provided to return the light in a downward direction to be dealt with by the lower prisms and the prisms 'above the line 26 may be omitted. The barrel is made up of two parts 11, 12, slightly tapered and butted together at their larger ends, the part 11 having a recess 13, Fig. 2, to receive the plain end of the part 12 and is strengthened by a flange 14. A flanged metal plate 15 seats on a flanged annular wall on the outer end of each part, the whole being drawn together by rods 16, and nuts 17. The plates 15 serve to fix the refractor to a lantern frame and so support lampholders. Specifications 406,141, 496,979, 690,502 and 761,365 are referred to. |
