GB199049A - Improvements in or relating to lamps, search-lights and the like - Google Patents

Abstract

199,049. Smith, J. G. Feb. 8, 1922. Vehicle lamps; lantern obturators.- In a vehicle head-light, search-light, &c. having one or more reflectors or a combination of an equivalent lens and a reflector designed to produce a beam that will, as it leaves the lens or glass in front of the lamp, converge for a portion of its length and then diverge to give the desired illumination at the desired range, the converging rays converge over an obturator arranged in front of the source of light to form a shadow x, Fig. 1, in the portion a, b of the beam, but instead of meeting in a common point such rays are distributed through the portion b, c of the beam, so that no shadow of the obturator is produced within that portion of the beam. The obturator may be provided on its rear face, i.e. facing the source of light, with a flat or convex reflector, the source of light being placed in front of the focus, or may be in the form of a conical annular reflector, the source of light being arranged in this reflector as a ring filament, and the main reflector enlarged to produce a ring focus the same size as the filament, which is also placed in front of the focus. In a further modification, Fig. 4, the whole or the greater portion of the rays from the main reflector 1 are intercepted by a conical reflector 5 and reflected on to an annular reflector 9 which receive such rays and reflect them to produce the desired beam through a glass 16 having a central aperture in which the reflector 5 is secured by an annular nut 12. The reflectors 5 may be replaced by an annular optical reflector having its inner and outer edges of the same shape as the reflector. The obturator mav be applied to the surface of a converging lens when such a lens is used, the unobturated portion of the lens producing the desired beam.