GB384626A - Improvements in or relating to luminous electric discharge tubes - Google Patents

Abstract

384,626. Discharge lamps. GENERAL ELECTRIC CO., Ltd., Magnet House, Kingsway, London.-(Assignees of Patent- Treuhand-Ges. fur Elektrische Gl³hlampen; 11, Ehrenbergstrasse, Berlin.) Sept. 13, 1932, No. 25476. Convention date, Sept. 16, 1931. [Class 39 (i).] In the method of starting discharge lamps described in Specification 353,372 wherein the heated electrodes are connected in series in a common heating circuit, the connection is broken by means of the discharge current which flows through a heating winding to operate a thermal switch. The electrodes 2, 3, Fig. 1, are connected in series through a resistance 11 and a switch 16 which consists of a gas-filled glass envelope containing a bimetallic strip 17, contacts 18, 19 and a heating winding 15. In a modification, the heater 15, Fig. 2, is adapted to expand gases in a tube 21 to move a mercury column 22 to break the connection between contacts 23, 24 in the cathode-heating circuit. If high-frequency apparatus is used for starting, the high-frequency circuit may contain switch contacts situated below the contacts 18, 19, Fig. 1, or may contain the contact 23, Fig. 2, and an additional switch contact' situated below the contact 24 so that the operation of the thermal switch causes the high-frequency circuit to be interrupted after the series connection of the electrodes has been broken.