GB503082A - Improvements relating to electric incandescent lamps - Google Patents

Abstract

503,082. Luminescent materials. SIEMENS ELECTRIC LAMPS & SUPPLIES, Ltd., and ALDINGTON, J. N. Sept. 28, 1937, No. 26238. [Class 39 (i)] An electric incandescent lamp with a metal filament has a bulb of transparent or translucent material which is provided with a coating of luminescent material adapted to be excited by radiations from the filament of not less than 3,200 Angstrom units to transform these radiations into visible radiations. The material of the bulb determines whether the luminescent material is applied to the inside or outside thereof, e.g. if the bulb is opaque to ultra-violet radiations the luminescent material is applied to the inside surface. In the case of a quartz bulb the luminescent material may be applied to the inside or outside, or both inside and outside. The luminescent effect is increased if the size of the bulb is greater than that used for ordinary nitrogen-argon filled lamps of the same wattage, the diameter of the bulb being about 1¢ to 2 times the diameter of the ordinary lamp. The luminescent material is applied as powder to an adhesive sprayed on the bulb, or the powder may be mixed with a vaporizable binder and the mixture applied to the bulb in a layer and then dried. Blue fluorescence may be obtained by using a material in the zincsulphide class, and orange to red by materials in the zinc-cadmium-sulphide class, one of the phosphorogens, manganese, silver, copper, or bismuth also being used.