GB715904A - Improvements in or relating to circuit arrangements for igniting two or more gas or vapour-filled discharge tubes - Google Patents

Abstract

715,904. Rectifying: ignition circuits for discharge tubes. PHILIPS ELECTRICAL INDUSTRIES. Ltd. Dec. 10, 1951 [Dec. 13, 1950], No. 28874/51. Classes 38(2) and 38(4) In a circuit arrangement for igniting two or more gas- or vapour - filled discharge tubes 1 ... 3 connected e.g. as a rectifier, each tube having a cold e.g. mercury cathode 4 ... 6 and an immersed ignition electrode 7 ... 9 of the resistive or capacitive type, wherein the tube cathodes are interconnected and each tube has an associated ignition circuit comprising a source, e.g. capacitors 10 . . . 12, and, for determining the ignition instant, a controllable auxiliary discharge path 13 ... 15, each path being provided between a separate anode 16 ... 18 and a common cathode 23 of a single multi-anode gas- or vapourfilled auxiliary discharge tube 22, each ignition circuit also includes a separate transformer 24 . . . 26 of which the first 27 ... 29 and second 30 ... 32 windings are in series connection in the anode and cathode leads respectively of the associated discharge path, and the transformers are such that upon the passage of ignition current through any one path the total impedance of its associated transformer windings is less than the impedance of either winding prior to the passage of such current. The discharge tubes 1 . . . 3 and the auxiliary discharge tube 22 each having interconnected cathodes and a common cathode respectively; this characteristic of the transformers ensures that only the tube e.g. whose auxiliary discharge path 13 is opened shall pass current of an igniting value, the then higher impedance of the transformer windings 31, 32 of the other tubes 2, 3 preventing the current through them from attaining a tube igniting value. Each transformer either may saturate with the passage of ignition current, or may have its two windings of a 1 : 1 ratio with their ampere - turns oppositely directed. The source of ignition voltage alternatively may be a single source in a common cathode lead of the discharge tubes 1 ... 3, or of the auxiliary discharge tube 22. The capacitors 10 ... 12 may be charged with A.C. or D.C. In another modification. Fig. 3 (not shown), the small current which passes through the transformer windings of tubes which are not to be ignited 2, 3 in the foregoing example, is reduced by a voltage neutralizing arrangement of chokes and a transformer.