GB531524A - Improvement in electric discharge devices with indirectly heated thermionic electrodes - Google Patents

Abstract

531,524. Discharge lamps. GENERAL ELECTRIC CO., Ltd. (Patent-Treuhand-Ges. fur Elektrische Gluhlampen). July 25, 1939, Nos. 21632 and 24825. [Class 39 (i)] A discharge lamp of the type in which the electrodes are heated by resistances in series with the main discharge is provided with directlyheated auxiliary electrodes for starting, the circuit arrangements being such that when the main electrodes are sufficiently heated the discharge shifts to them from the auxiliary electrodes. The Figure shows the heaters, 3, 31 connected to the main electrodes 2, 21 to which are also connected the auxiliary electrodes 7, 8. The electrodes 7, 8 are connected by a conductor 4 in which is included a resistance 6 of such magnitude that when the electrodes 7, 8 are hot the discharge passes between them. When the electrodes 2, 21 are hot the discharge shifts to them, the path between them being shorter than that between the electrodes 7, 8. The circuit through the electrodes 7, 8 is then opened by a thermal switch 5, or it may include a spark-gap of such length that the discharge will not pass it when a discharge has been established between the electrodes 2, 2<SP>1</SP>. A barretter may be connected in series with the main discharge and a resistance, the value of which falls with the passage of current through it in series with the auxiliary electrodes.