GB432959A - Improvements in or relating to vehicle lamps - Google Patents

Abstract

432,959. Vehicle lamps. STUART, A. H., 10, Avon Road, Walthamstow, and ROCHE, B. V., 19, Charing Cross Road, both in London. Jan. 6, 1934, No. 561. [Classes 75 (ii) and 75 (iv)] In a vehicle lamp comprising a reflector built up from upper and lower half paraboloids which are so disposed with respect to the light source as to project a beam which is below a horizontal plane, visibility of the beam from aircraft is reduced by providing the lamp with a light filter having a high transmission for light of the shorter visible wavelengths which is liable to considerable scattering in the atmosphere (4000-5000 A.U.), and low transparency for light of longer wavelengths which is readily transmitted through the air (6000-7000 A.U.). The light source may comprise a short straight filament disposed horizontally along the axis of the lamp, and the lower half paraboloid may be arranged horizontally with its focus coincident with or in front of the front end of the filament, whilst the upper half paraboloid may be downwardly inclined so that its focus is substantially vertically below that of the lower half paraboloid. Alternatively, the upper half paraboloid may be arranged horizontally with its focus coincident with or to the rear of the rear end of the filament, whilst the lower half paraboloid may be downwardly inclined so that its focus is substantially vertically below that of the upper half paraboloid, or it may be displaced forwardly so that its focus coincides with or is in front of the front end of the filament. The Figure shows a combination of the last two arrangements. The upper and lower half paraboloids R1, R2 have foci F1, F2 respectively, a shield 5 which is dull black on all sides is provided on or near the bulb B to intercept forward and upward direct rays from the filament L, and a similar cowl C is fitted to the upper half of the lamp casing D. The front glass G may have a green tint to form the colour filter.