GB399121A - Lighting device - Google Patents

Abstract

399,121. Vehicle &c. lamps. RIVIER, L., Jouxtens, Mezery, Vaud, Switzerland. April 28, 1933, No. 12400. Convention date, May 13, 1932. Addition to 374,911. [Classes 39 (ii) and 75 (iv).] In a vehicle or like lamp in which a portion of the light emitted by a source is concentrated by a reflector to the focus of a parabolic reflector which projects a parallel beam, the said focus approximately coinciding with one edge of a screening member which is adapted to intercept those rays which would not pass through the said focus and which would be projected upwardly by the parabolic reflector, as described in the parent Specification, the first mentioned reflector is constituted by a portion of an electric lamp bulb having an ellipsoidal reflecting surface and a filament placed at one focus of the ellipsoid. In the form shown in Fig. 1, the front glass 2 of a paraboloidal reflector 1 carries an electric lamp bulb 4 having an ellipsoidal reflecting surface 6, the foci of which coincide respectively with the filaments 5 and the focus 8 of the reflector 1, the bulb also having a transparent portion 7 which is spherical about the focus 8 as centre, and a screen 13 is arranged with its upper edge coinciding with the focus 8. The screen 13 may be inclined or at right-angles to the common axis of the ellipsoid 6 and the paraboloid 1, it may be plane, stepped, curved, or made in two parts at right-angles to each other, and the intercepted rays may be absorbed or reflected back into the ellipsoid. The screen may be carried by a lever 12 pivoted to a support 10 which is adjustably mounted in a sleeve 9, and the lever may be held in an inoperativeposition by a spring and pulled into the operative position by means of an electromagnet 11. Alternatively, the transparent portion of the bulb may be convex with the screen and both foci of the ellipsoid located within the bulb, and the axis of the bulb may be arranged at rightangles to that of a part paraboloidal reflector. In the form shown in Fig. 3, a number of bulbs 18 are arranged with their axes at acute angles to that of a paraboloidal reflector 21 having its focus 20 coinciding with the centre of an adjustable opening in an absorbing diaphragm 23 and with the conical ends of a pair of cylindrical screens 22.