GB492554A - Improvements in or relating to electric lamps - Google Patents

Abstract

492,554. Discharge lamps. BIRDSEYE ELECTRIC CORPORATION. Aug. 4, 1937, No. 21531. Convention date, Aug. 7, 1936. [Class 39 (i)] [Also in Group XI] The bulb of an incandescent lamp or discharge lamp is provided with a reflecting- coating which has narrow slit-like apertures to transmit light, the bulb being roughened on its surface over the apertures in the coating and over an adjacent area, whereby an uniformly illuminated effect outside the coated area of the bulb is produced. In one form for use more particularly within a translucent globe 14, the bulb 10 is provided internally with a silvered coating 11 extending from the line of maximum diameter upwardly into the neck of the bulb. The coating is removed around a number of fine circumferential lines 13 which may be graduated in width or location to control the amount of light escaping therethrough. The outer surface of the bulb 10 is frosted uniformly over an area at least coextensive with the outer boundary of the internal silvered coating, the lower part 12 of the bulb below the line of maximum diameter being clear. In a modification the bulb is frosted continuously over its entire area and provided with an external silvered coating extending from the line of maximum diameter upwardly into the neck of the bulb. This silvered coating is removed along a fine line formed as a continuous spiral. In a further modification the entire surface of the bulb, with the exception of the tip or rounded end, is frosted, and the lower portion below the line of maximum diameter. s silvered internally, the silver being then removed from the unfrosted end portion, and in a series of meridian lines extending from the upper to the lower boundary of the silvered area. This lamp is adapted to be mounted within a conical translucent enclosure located apex downwardly.