GB585960A - Improvements in gaseous electric discharge devices - Google Patents

Abstract

585,960. Discharge lamps. BRITISH THOMSON - HOUSTON CO., Ltd. July 25, 1944, No. 14200. Convention date, Dec. 26, 1942. [Class 39 (i)] For easy starting in an electric discharge lamp the spacing between the anode 12 and the cathode 11 is not greater than two mms., preferably one mm., and the distance B across which the discharge extends in operation between the anode and one end of the cathode is substantially greater than two mms., but less than five mms., preferably 3-5 mms. The electron-emissive cathode 11, preferably a triple coil as described in Specification 561,177, and activated according to a procedure given, is preheated to initiate the discharge. It is supported on its leads 13, 14. The anode 12, preferably a thin ribbon of nickel or molybdenum is supported by the lead 15 and may surround or partially surround the cathode. Alternatively, the anode may be a wire forming an extension of the lead 15. Suitable dimensions for the cathode and anode of the specific lamp shown are given. The filling is a mixture of a small amount of mercury and argon at a pressure of, e.g. 0.5-8 mms. of mercury. The envelope 10 may contain a fluorescent material and the lamp base is described in Specification 303,114, [Class 39 (ii)]. The lamp shown starts at 12 volts and has an arc voltage of from 6.25 to 8.5 volts.