GB493361A - Improvements in electric discharge devices - Google Patents

Abstract

493,361. Discharge lamps. GENERAL ELECTRIC CO., Ltd. (Patent-Treuhand-Ges. f³r Elektrische Gl³hlampen) April 5, 1937, Nos. 9636/37, 6263/38, and 6264/38. [Class 39 (i)] A discharge lamp containing either neon or neon and mercury vapour is arranged to have a nearly constant or slightly positive voltagecurrent characteristic. For this purpose the gas pressure, apart from mercury is from 4 to 8 mm., and the current density is not greater than 30 mA (sq. cm. of cross section of envelope) ; also to the neon are added argon and krypton or xenon, so that if the percentage of argon is y and krypton or xenon x, 2x+y lies between 0À2 and À05 if no mercury is present, and between 0À2 and 2 if mercury is present, the vapour pressure of the mercury not greatly exceeding À001 mm. Furthermore, if thermionic electrodes are employed the tube must be so long that the total characteristic is substantially that of the positive column. Preferably, however, the electrodes are hollow metal cylinders. To keep the mercury vapour pressure at the desired level the electrodes may be formed as nearlv closed canisters containing mercury. The canister may be polished highly on its outer surface, or covered with heat insulating material or a vacuum jacket, the 'discharge entering the mouth of the canister. Specific examples are given and Specifications 227,832, [Class 39 (i)], 395,851, 405,499, 418,027, 431,382, and 476,240, are referred to.