GB620495A - Improvements relating to light projectors - Google Patents

Abstract

620,495. Reflectors; light projectors. WHITING, J. G. June 18, 1946, No. 18287. [Classes 75(ii) and 75(iv)] A light projector of general paraboloidal form comprises a plurality of concavely curved reflecting areas extending transversely across the projector, the curvature of the areas being such that the rays reflected by each area from a light source at the focus of the projector converge along an individual generally transversely extending curved line. A reflector 18 is fitted in the conical end 11 of a casing 10 supported in the frame structure 19 of a vehicle and comprises horizontally disposed elongated areas 34a, 34b &c. each of which is concavely curved in vertical section, the lower edges of the areas 34a &c. being parabolas formed by the intersections of planes inclined to the horizontal and paraboloids of different parameters each having the electric filament 36 as focus. Each area 34a &c. is developed upwards from the parabola forming its lower edge to form a surface which reflects crossed rays such as 35g and 38g all the rays in the same vertical plane crossing at a point 39g, and all such points of convergence for any one area 34a &c. lie on a substantially parabolic curve. The rays 35g &c. reflected from the lower edges of each reflecting area are substantially parallel to the longitudinal axis 37 of the reflector but the rays reflected by the central portion of the lower edge of any one area are vertically above the rays reflected from the side portions of the lower edge of the same area. Metal or other shields 26 transversely curved so that the curvature is greater at the front 67, Fig. 3, than at the rear end 27 are disposed in a parallel generally horizontal arrangement within the casing so that each shield projects by a different amount into the reflector and light from each reflecting area 34a &c passes between a pair of these shields; light from a condensing lens 31 in the lamp bulb passes through the space between the middle pair of shields. Different effects may be obtained by painting the shields different colours or by polishing them or by making then. translucent. The relative vertical heights of the areas 34a &c. and the relative spacing of the shields 26 may be varied. The front of the casing 10 is closed by a glass plate 20 held against a gasket 21 in the vehicle frame 19 by means of a bezel ring 22.