GB512803A - Improvements in or relating to double-walled electric lamps - Google Patents

Abstract

512,803. Electric incandescent lamps. SOC. ANON. POUR LES APPLICATIONS DE L'ELECTRICITE ET DES GAZ RARES ETABLISSEMENTS CLAUDE-PAZ & SILVA. March 16. 1938, No. 8166. Convention date, Jan. 28. [Class 39 (ii)] In a double-walled lamp the outer bulb E is partly filled with a liquid within which the inner bulb i is immersed, the properties of the liquid being such that, during the operation of the lamp. it boils and emits vapours. which condense on the inner wall of the part of the outer bulb above the level of the liquid. Saturated hydrocarbons or mixtures of such hydrocarbons, such as the oil 'known under the Registered Trade Mark "Vaseline," may be used for the cooling liquid. Alternatively, in order to absorb the infra red rays. a weak solution of copper sulphate in water may be used. A coloured liquid may be used to obtain coloured light. Luminescent liquids may also be used. In a modification for use as a projection lamp the bulbs are so shaped that the liquid between them forms an element of an optical projection system. A ring of porous material may be disposed at the upper end of the immersed bulb to ensure regular boiling in the upper part of the liquid, and the upper part of the outer bulb may be made of metal and provided with cooling-fins which may either be enclosed in the projector or extend to the outside thereof. A fuse f<1> may be provided in one leading-in wire as a guard against excessive heating, and a fuse f<2> in the other wire as an excess current fuse. The inner bulb may contain a filling of xenon and nitrogen, and the space above the liquid in the outer bulb may be filled with nitrogen at a pressure of 1 c.m. of mercury.