GB314545A - Improvements in or relating to vehicle and like lamps - Google Patents

Abstract

314,545. Soc. pour la Fabrication des Projecteurs Electriques Marchal. June 30, 1928, [Convention date]. No Patent granted (Sealing fee not paid). Vehicle and like lamps.-A vehicle or like lamp is provided with a reflector in the form of a body of revolution comprising two parabolic elements a, b, the foci of which coincide with two sources of light either of which may be illuminated at will to provide a powerful beam or less powerful beam. In the form shown in Fig. 1, the reflector comprises two parabolic portions a, b united in a plane substantially perpendicular to its axis. The portions a, b have unequal focal lengths, non- coincident foci f<1>, f<2>, and may or may not have a common axis. In the form shown in Fig. 2, the portions a, b are separated by a reflecting or non-reflecting portion c which may be in the form of a surface of revolution, the generating curve of which may be a circular arc the centre of which may be at either of the foci f<1>, f<2>, preferably the focus f<1>. In this form the focal lengths may be equal. The projected beams may be diffused by providing striations on the reflector, on the front glass, or on both the reflector and the front glass. The sources of light may comprise two electric lamp filaments, which may be arranged in a single bulb. A screen d, which may be arranged inside the bulb,. may be employed to prevent rays of light from the filament located at the focus f<2> from falling on the lower half of the reflector. According to the Specification as open to inspection under Sect. 91 (3) (a) the portion b may be pivoted and operated by appropriate mechanism to incline it downwardly or laterally, a bulb may be so mounted that its single filament may be brought into coincidence with either of the foci f<1>, f<2>. and the striations on the reflector or glass are preferably vertical. This subject-matter does not appear in the Specification as accepted.