GB388665A - Improvements in or relating to devices comprising an electric luminous discharge tube - Google Patents

Abstract

388,665. Discharge lamps. NAAMLOOZE VENNOOTSCHAP PHILIPS' GLOEILAMPENFABRIEKEN, 13D, Emmasingel, Eindhoven, Holland. July 28, 1932, No. 21302. Convention date, Aug. 19, 1931. [Class 39 (i).] Wire or strip-shaped auxiliary electrodes 8, 9 are arranged longitudinally inside the tube 1 and are connected to an auxiliary source of current 14 having a voltage higher than that of the source 16 to which the main electrodes 4, 5 are connected. The resistances 11, 12 may be each of 1000 to 10000 ohms. The electrodes 4, 5 may be oxide-coated filaments heated from the secondaries 17, 18 of a transformer the primary of which is connected to the supply 16. Leads 19, 20 connected to the centres of secondaries 17, 18 supply the main discharge current and an impedance 21 may be included. The auxiliary electrodes may be spaced and supported by a glass bead 10, or may overlap, preferably for less than one-third of the tube length. Parts of the auxiliary electrodes in the neighbourhood of the main electrodes may be encased in protecting tubes of porcelain, and a gauze grid, supported from the walls of the tube, may surround the centre 10 to prevent blackening of the tube. The connections are preferably arranged so that when the electrode 4 is negative, the auxiliary electrode 8 is positive. More than one pair of auxiliary electrodes may be provided. A cylindrical anode may surround each incandescent electrode and be connected to it, so that on the half-wave when the latter is positive this anode may receive the current. An example is cited in which a tube 1 metre long having a diameter of 40 mm. and a neon filling at a pressure of 1À8 mm. was started with a voltage of 180-190 volts. the voltage of the secondary winding 13 being then 360 volts.