GB487462A - Improvements in and relating to vapour electric discharge devices - Google Patents

Abstract

487,462. Metal - vapour lamps. BRITISH THOMSON-HOUSTON CO., Ltd. July 14, 1937, No. 19544. Convention date, July 16, 1936. [Class 39 (i)] [Also in Group XXXV] In an electric discharge device of the type comprising a liquid pool cathode 3, Fig. 1, of mercury, gallium, sodium, cadmium, &c., an anode 2, a fixed ignition electrode 6 coacting with an anchoring electrode 4 of porous capillary material, such as described in Specification 481,078, and means for impressing a cyclically alternating potential between the cathode and the anode and ignition electrode, means are provided for making the ignition discharge of a non-oscillatory character and for regulating it in predetermined timed relation to the alternations of the main circuit. As shown in Fig. 3, the potential is impressed on the ignition electrode from a transformer 20 through a circuit including a resistance 23, a condenser C, and a resistance R, such that the inductance of the circuit is less than the product of the capacity of the condenser C and the square of the resistance R and also that the peak current in the spark exceeds approximately half an ampere. Fig. 3 shows an arrangement for modifying the characteristics of an alternating potential supplied from an input circuit 16 to a load connected at 17. The regulating system consists of two discharge devices 1, 1<1> in reverse arrangement. The transformer 20 is in circuit with a phase shifting transformer 19 of usual construction. The ignition electrode 6 is a strip with a tapering edge directed to the anchoring electrode. In a modification the resistance 23 may be replaced by a thermionic rectifier.