GB408113A - Improvements in or relating to glasses for vehicle lamps - Google Patents

Abstract

408,113. Vehicle lamps. BOSCH AKT.- GES., R., 4, Militõrstrasse, Stuttgart, Germany. June 22, 1933, No. 17748. Convention date, June 24, 1932. [Class 75 (ii).] Lantern, fronts.-A front glass for a vehicle lamp, adapted to produce a substantially uniform illumination over a relatively wide angle by means of an ordinary parabolic reflector, is formed with separate groups of vertically disposed grooves or flutings of different dispersive power, each group producing a beam of light which does not substantially overlap its neighbour, the axes of the said beams radiating at different angles from a focal point, and the groups which produce the lateral beams being of prismatic cross-section. In one form, both the parabolic reflector and the glass of the lamp are slightly downwardly inclined and the rear face of the glass is formed with a central field of cylindrical flutings 9, Fig. 3, which produce a pair of beams YXP, Fig. 11, an upper field of prisms 7, 8 which produce a pair of beams PXQ, and a lower field of prisms 10 which produce a pair of beams QXR, the axes of these beams being disposed at approximately 5‹, 25‹, and 40‹ respectively to the axis XY of the lamp. The front face of the glass is formed with vertical cylindrical flutings 5, which are staggered with respect to, and of somewhat larger radius of curvature than, the flutings 9, so as to blend the six beams together, with or without horizontal cylindrical flutings 6 of greater radius of curvature than the flutings 5 and disposed opposite the prisms 10 so as to cause a weak dispersion upwards and downwards of the beams which are strongly deflected laterally. In modifications, the prisms 7, 8 may be combined, the groups of flutings may be disposed side by side, and the flutings 6 may be replaced by downwardly refracting prisms. The glass may be flat or of spherical curvature, or it may be V-shaped in plan so as to reduce its wind-resistance. Fig. 7 shows a glass formed with an overhanging part 11 which may be frosted or formed with flutings 13 to disperse the upwardly directed rays.