GB497880A - Electric incandescent lamp - Google Patents

Abstract

497,880. Electric incandescent lamps with internal reflectors. VEREINIGTE GLUHLAMPEN UND ELEKTRIZITATS AKT.-GES. Dec. 8, 1937, No. 33993. Convention date, Dec. 8, 1936. [Class 39 (ii)] In order to increase the efficiency of an electric incandescent lamp by increasing the proportion of input energy that is converted into visible radiation an optical arrangement is provided, either contained within or forming part of the lamp bulb and, in a measure which increases with increasing wave length, throws back the radiation on to the incandescent body. The optical arrangement consists of a device or devices having two different effects, namely, the dispersion of the light and the reflection back on to the incandescent body of the undeflected and undispersed part of the radiation. The dispersive media used may comprise opal glasses or opal quartzes the particles of which are of such small dimensions that the intensity of the dispersed radiation is at least proportional to the reciprocal of the square of the wave length of the radiation. The arrangement is preferably rotationally symmetrical, and may comprise a system of reflecting-prisms or pyramids with plane or, preferably, curved reflecting surfaces, arranged to form the surface of a cylindrical body with the lamp filament arranged along the axis thereof. The reflecting-members may themselves be made of opal glass or opal quartz, or alternatively, they may be made of transparent material and mounted on the outside of a rotation body made of opal material or of opal-flashed transparent material. In another arrangement a sheath of opal material is arranged around an incandescent body, and two or more layers of reflecting strips with gaps between them are provided in or upon the sheath, the arrangement of the strips being such that the gaps in one layer are covered by a strip in the other layer, so that the visible light is dispersed through the gaps and the infra-red radiation is reflected back on to the incandescent body. The device may be arranged in vacuum lamps or gas or vapour filled lamps.