GB456402A - Improvements in or relating to gaseous discharge lamps - Google Patents

Abstract

456,402. Discharge lamps. ELECTRICAL RESEARCH PRODUCTS, Inc., 195, Broadway, New York, U.S.A. Feb. 20, 1936, No. 5137. Convention date, March 9, 1935. [Class 39 (i)] Apparatus for light signalling comprises a gaseous discharge lamp having an anode, a cathode and a unit for heating the cathode to electron-emitting temperature electrically connected at one end to the cathode, a source supplying signal potentials to the anode and cathode, and a source supplying constant heating current for the heating unit in series through the heating unit and the cathode. In the lamp shown an open cylindrical cathode 6 surrounds the heating coil 5, one end of which is connected to the cathode. A cylindrical screen 8 surrounds the cathode and is provided at one end with a conical extension 9 ending in a capillary opening 10 which faces a similar opening in the disc-like anode 12. Anode 12 and screen 8 are supported from stem clamps 13. The heater 5 is supplied from a source of continuous current, the negative side being connected to the cathode to prevent positive ion bombardment of the heating unit. Signal impulses are applied to the positively-biassed anode through a transformer. The filling may be neon, helium or argon at 5-10 mms. pressure, together with mercury or 2-5 per cent of nitrogen or hydrogen. The cathode is made of, or externally coated with, electron-emissive material. In a modification the cathode completely encloses the heating coil. Curves are given showing the voltage-current characteristic of the lamp, and comparing the powerlight output curve with that of a similarly constructed cold cathode lamp.