GB119470A - Improvements relating to Lamps for Lighting. - Google Patents

Abstract

119,470. Evans, H. R. Sept. 21, 1917, [Convention date]. Vehicular and like lanterns. -A motor-car headlight, flood light, or other lamp is provided with two substantially spherical reflecting-surfaces facing each other and having their centres substantially at the light source, and with a parabolic reflecting-surface, which intercepts rays reflected from the spherical surfaces and reflects them forwardly. The light source may be elongated and of narrow crosssection, and arranged transversely to the axis of the reflector, so that, while the light rays issuing from the lamp are spaced out laterally, there is only a slight vertical divergence. Fig. 1 shows an incandescent lamp bulb having a transversely arranged elongated filament 2, such as a coil of tungsten wire or a single strand of uncoiled wire, located substantially at the common centre of curvature of the front and rear spherical parts 3, 4 of the bulb, and at the focus of a parabolically curved part 5 of the bulb. The rear of the bulb is provided with a protective metallic backing 12, and the front spherical part 3 is provided with a hemispherical cap 13 held in place by a hooked spring 13<1>. The spherical parts 3, 4 and the parabolic part 5 of the bulb are silvered externally, or the inner surfaces of the backing and the cap are silvered, the remaining annular part 14 of the bulb being left transparent. The annular part 14 may be provided with a disk of prismatic glass at its lower part for throwing some of the rays downwardly, and a part of the silvering of the spherical part 3 or of any other part of the bulb may be removed and a corresponding opening left in the protective cap or backing to allow light to pass in any definite direction. The electric connexions are rendered waterproof if desired by a rubber gasket compressed between the lamp base 8 and the socket 6, and by a rubber tube 9 clamped to the cable and to the socket 6. In a modification, a spherical lamp bulb 20, Fig. 7, having a centrally-arranged elongated filament, is located within a parabolic reflector, and has its front and rearward parts 23, 21 silvered; or, alternatively, two separately mounted spherical reflecting-surfaces are employed.