GB311282A - Improvements in and relating to electric discharge devices - Google Patents

Abstract

311,282. Spanner, H. J., and D÷ring, U. May 8, 1928, [Convention date]. Drawings to Specification. Vacuum tubes.-In a gas discharge device such as a lamp, the cathode consists of a capsule or shell containing an auxiliary electrode and resistance material, such as a mixture of carbon or the material known by the registered Trade Mark Carborundum and oxides of zirconium or beryllium, a heating current being passed through the resistance. The discharge and heating circuits may be connected in parallel or in series, and the current through the heating circuit may be opened by hand or electromagnetically, when the full discharge has started. A resistance may be connected in series with the heating circuit. Two or more cathodes may be disposed in chambers offset from the main path of the discharge so as to provide an extended source of light. The envelope may be of glass or of quartz or other material transparent to ultra-violet rays, or the glass may contain, or be covered with, fluorescent or coloured material. The cathode is preferably coated with barium, strontium, caesium, or rubidium, for example in the form of oxide, and associated with an amphoteric oxide such as zirconium, aluminium, chromium, nickel or copper oxide. The filling may be neon with iodine or bromine. The Specification as open to inspection under Sect. 91 (3) (a) comprises also a device having a cathode heated by a glow discharge from an internal electrode, or by an internal heating element consisting of a tungsten coil wound in grooves on a tubular support of sintered zirconium, aluminium, magnesium or beryllium oxide. This subject-matter does not appear in the Specification as accepted.