GB463299A - Improvements in or relating to electric circuit arrangements for electric discharge devices - Google Patents

Abstract

463,299. Control systems for discharge lamps. GENERAL ELECTRIC CO., Ltd., RYDE, J. W., and RANDALL, J. T. June 7, 1935, Nos. 16651 and 17617. [Class 38 (iv)] [Also in Group XL] An electric gas or vapour discharge tube of the type having at least one of main electrodes thermionic and at least one auxiliary electrode 3 adjacent to it is flashed by transferring the discharge from the main thermionic electrode alternately to the other main electrode and the auxiliary electrode Where the lamp is operated on D.C. with its anode cold and its cathode thermionic, the lamp is flashed by connecting an auxiliary cold electrode 3 near the cathode 2 to the anode by a switch 7 through a low impedance path. An auxiliary thermionic electrode may in addition be provided near the anode in which case flashing is effected by connecting the auxiliary electrodes together. In a modification, supplied with A.C. in which both the main electrodes are thermionic, cold auxiliary electrodes are connected to the adjacent main electrodes through impedances carefully selected so that when the auxiliary electrodes are connected together through a low impedance path the discharge passes only between the main and auxiliary electrodes. If the auxiliary electrodes are made thermionic the connection between them and their adjacent main electrodes may be omitted. Only one of the auxiliary electrodes may be utilized for this purpose by connecting one of these electrodes to the main electrode remote from it through the control switch. The other auxiliary electrode may be omitted if not required for other purposes. Auxiliary starting means such as a Tesla coil may be provided and arranged to be operative when the switch 7 is open. The primary of the Tesla coil may or may not be connected in series with the stabilizing choke 4 of the tube. Additional starting electrodes may be provided or the auxiliary electrodes may be used for starting in which case the switch 7 may be arranged to insert an impedance between the electrodes when it is open. The thermionic main electrodes may be rods of alkaline earth silicates surrounded by tungsten heating spirals. The auxiliary electrodes may be combs or discs of molybdenum. Specifications 360,872 and 395,804, [both in Group XL], are referred to.