GB469187A - Improvements in or relating to gas-filled electric discharge devices - Google Patents

Abstract

469,187. Discharge lamps. GENERAL ELECTRIC CO., Ltd. (Patent-Treuhand-Ges. fur Elektrische Gl³hlampen) Jan. 22, 1936, Nos. 2046/36 and 188/37. Drawings to Specification. [Class 39 (i)] A discharge lamp having a thermionic cathode is constructed to work on the positive portion of its voltage-current characteristic by correlating (i) the diameter of the part of the envelope through which the discharge takes place, (ii) the nature of the electrodes and the distance between them, and (iii) the nature of the filling and its pressure ; the features are selected so that the working remains on the positive part of the characteristic for a substantial range of current about the predetermined voltage for which the lamp is designed. A table is given showing diameters of envelope for fillings of helium, neon or krypton at varying pressures of from 0À5 to 3 mm. As an example a lamp with oxide-coated electrodes has an envelope 10 mm. in diameter, neon filling at 1À5 mm. and an electrode spacing of 85 cm., the applied voltage being 330, and the current 1À5 amps. The lamps are designed to run direct on supply mains but a small ballast resistance may be used; if desired use may be made of starting means such as (i) auxiliary electrodes, (ii) induction coil or (iii) a higher voltage circuit with impedance in series and switching means. To maintain the gas pressure constant the electrode chambers may be made at least three times the diameter of the main discharge space or the tube may be connected to an auxiliary reservoir. British Specification 376,220 and U.S.A. Specification 1,842,215 are referred to.