GB384555A - Improvements in or relating to luminous electric discharge tubes - Google Patents

Abstract

384,555. Discharge lamps. GENERAL ELECTRIC CO., Ltd., Magnet House, Kingsway, London.-(Assignees of Patent- Treuhand Ges. fur Elektrische Gl³hlampen; 11, Ehrenbergstrasse, Berlin.) May 12, 1932, No. 13715. Convention date, June 24, 1931. [Class 39 (i).] I n regulating the light of alternating - current luminous tubes by controlling the discharge period in each half-wave by varying the phase-shift on one or more electrostatic control electrodes near the main electrodes, the usual series resistance is omitted and the phase-shift is so controlled that the discharge only takes place during the descending part of each half-wave shortly before the potential drops to zero. The discharge starts at each point 3 of the potential curve 1 and a heavy current peak 4 occurs, no damage being done to the tube since the point 5 at which the voltage can no longer maintain the discharge is quickly reached. The tube may have a hot cathode and two anodes each with surrounding control electrodes, or may have two hot cathodes each with an adjacent control electrode. To facilitate starting at the point 3, a constant auxiliary ionization is maintained by a highfrequency discharge. Specification 371,673 is referred to.