GB487011A - Improvements in or relating to reflecting electric incandescent lamps - Google Patents

Abstract

487,011. Electric incandescent lamps. BIRDSEYE ELECTRIC CORPORATION. Sept. 1, 1937, No. 23929. Convention date, Sept. 11, 1936. [Class 39 (ii)] A lamp bulb is shaped and coated to present a reflecting surface which is formed by revolving a parabola 10-12 about the axis 24- 26 of the lamp at a constant distance therefrom so that the focus of the parabola describes a circle about the axis of the lamp, the filament 14-16 being located in the plane of the focal points of the parabolic surface, there being also a concave globular reflecting-surface of different curvature, indicated by its trace 10-30, located behind the focal plane of the parabolic portion of the bulb and shaped so as to aid in reflecting rays from the,lamp in a cone of divergent rays of intensity diminishing from the centre outwardly. In the example the parabolic portion is continued in the form of a flattened hemisphere or semi-ellipsoid, with a correspondingly curved internal reflector 32 mounted in the neck of the bulb, but spaced from the wall thereof to allow the passage of convection currents. The filament may be substantially circular, or of Vee or other shape having all its parts located in the plane perpendicular to the axis of the mount and disposed within the limits of the circle which is the locus of the focal points of the paraboloid. Preferably the reflecting surface is located on the inner surface of the bulb and may consist of a deposit of metallic silver.