GB463621A - Improvements in reflectors for vehicle and like lamps - Google Patents

Abstract

463,621. Reflectors for vehicle &c. lamps. NIELSEN, F. July 1, 1935, No. 18782. Convention date, June 30, 1934. [Class 75 (ii)] A reflector, for a vehicle or like lamp, of the kind consisting of two half mirrors each lying on one side of a longitudinal plane and comprising two parabolic sections JT, TE of different parameters merging into one another and having separate foci A, B, is characterized in that for each half of the reflector, in a vertical plane, the foci are displaced vertically or substantially vertically and the common axis of generation of the two parabolic sections lies between the axes AC, BD of the said sections but never coincides with either of them. One or both of the inner parabolic sections may be replaced by continuous or discontinuous surfaces of such configuration that, in a vertical plane, incident rays parallel to the optical axis do not fall in a space defined at its upper limit by the focus of the remaining parabolic section and at its lower limit by the extreme lower end of the light source. Such a surface may be generated by means of the tangent TO, or by means of a circular arc TU with centre Z. The axes of generation of the two half mirrors may be coincident or parallel, and the foci of one half mirror may coincide with the corresponding foci of the other half mirror, or be spaced horizontally therefrom by a distance approximately equal to the longitudinal length-of the light source. The latter may comprise an electric light bulb with a plurality of selectively operable filaments, and is accommodated within the space defined by the focal lines of the two half mirrors. The surfaces of the two half mirrors may be made circular in cross-section by rotation about the axis of generation, but, in order that all reflected rays shall be below the horizontal, the cross-sectional curve may have normals which all lie beneath the light source or, at most, are tangential to it. Examples of such curves are archimedean spirals, evolvents about the circular or other cross-section of the light source, or curves approximating thereto. The radius vectors of the upper and lower half mirrors increase and decrease respectively from the vertical to the horizontal. Mechanical or electromagnetic means may be provided for moving the half mirrors in opposite directions longitudinally, either separately or simultaneously, for moving the light source laterally in an upward or downward direction beyond the axes AC, BD, or for tilting the whole projector upwards through a small angle. The Specification as open to inspection under Sect. 91 states also that the axis of generation may coincide with either of the axes of the two parabolic sections. This subject-matter does not appear in the Specification as accepted.