GB236155A - Improvements in or relating to electric gasfilled discharge tubes - Google Patents

Abstract

236,155. Naamlooze Vennootschap Philips' Gloeilampenfabrieken. June 25, 1924, [Convention date]. Vacuum tubes; vacuum apparatus with reflecting surfaces; low-pressure metallic-vapour apparatus.-Electric discharge tubes in which a light - radiating positive column appears and which comprise two electrodes within a sealed envelope filled with a rare gas in contact with the electrodes are operated at 500 volts or above and are provided with one or more conductive members extending over a considerable length of the tube and along or in the wall thereof out of contact with the gas. Each conductive member may comprise a conductive layer 6, Fig. 1, such as aluminium paste or a silver mirror reflecting light in a predetermined direction, or a copper or other metal wire or band 20, Fig. 3, arranged helically around the tube, disposed within the walls of the tube or enclosed in an insulating tube within the discharge tube. An auxiliarycapacitive discharge between the conductive members or between one member and an electrode lowers the initiating and operating high voltage of the main discharge and permits a reduction in the resistance in series with the tube. At least one conductive member may be connected with one electrode of the tube and two members, such as two helices with their ends near together at the centre of the tube, may be connected to the two electrodes. One member connected to the electrode may be connected to earth, as in Fig. 3, so that nearly the whole tube is at earth potential, the member extending close to the other electrode. Alternatively, the auxiliary discharge may be produced by a voltage separate from the main discharge voltage and preferably of such phase that the auxiliary voltage is a maximum when the main discharge can be initiated. Two conductive layers 6, 7, Fig. 1, on opposite sides of the outer surface of the tube may be supplied with voltage from a transformer 13 separate from the transformer 10 supplying the main discharge, between the electrodes 4, 5 in widened parts 2, 3 of the tube. To prevent discharges along the outer wall of the tube when two conductive members are used, one at least is arranged inside the tube. Several tubes may be connected in parallel across a single transformer. Specification 154,199 is referred to. The Specification as open to inspection under Sect. 91 (3) (a) comprises also the mixture of a small quantity of mercury or like vapour with the gas. This subject-matter does not appear in the Specification as accepted.