GB442400A - Improvements in electric discharge lamps - Google Patents

Abstract

442,400. Discharge lamps. GENERAL ELECTRIC CO., Ltd., Magnet House, Kingsway, London.-(Assignees of Patent - Treuhand-Ges. fur Elektrische Gl³hlampen; 11, Ehrenbergstrasse, Berlin) March 15, 1935, No. 8091. Convention date, March 28, 1934. [Class 39 (i)] In a luminous electric discharge lamp of the type adapted to be operated on alternating-current and comprising a tube, filled with rare gas and possibly metal vapour, the walls of which are of phosphorescent material or bear such material on their inner surfaces, the device comprises either two thermionic electrodes and one non-thermionic electrode, or one thermionic and two non-thermionic electrodes, so arranged and connected to the supply terminals that a discharge passes through part or the whole of the tube only when the potential difference between the supply terminals has one predetermined sign. The phosphorescent material glows during the extinguished half cycles, flicker is reduced and the material is used efficiently. In the form shown a discharge - heated thermionic electrode 2<1> and two non - thermionic electrodes 3<1> are arranged in a tube 1 having phosphorescent material 5 on its inner wall. Electrode 21 is connected to one end and electrodes 31 to the other end of a transformer 6. In a modification, the central thermionic electrode is heated externally by a tapping from the centre of the transformer secondary and one non-thermionic electrode is connected to each end. In another modification the electrode 2<1> is replaced by a non-thermionic, and 3<1> by thermionic electrodes. Two chokes 16, 17, or a single choke in the primary circuit of the transformer may be employed A filling of rare gas and mercury is used. The Specification as open to inspection under Sect. 91 describes also a tube having one thermionic and one non-thermionic electrode and containing zinc sulphide or silicate. Specifications 310,895, [Class 39 (i)], 387,130, and 388,560 are referred to. This subject-matter does not appear in the Specification as accepted.