Startervorrichtung fuer eine Entladungslampe

摘要

1,269,255. Control systems for fluorescent lamps. MATSUSHITA ELECTRIC INDUSTRIAL CO. Ltd. 6 Aug., 1969 [6 Aug., 1968], No. 39329/69. Heading H2H. A system for starting and operating a discharge lamp 13 comprises a reverse blocking thyristor 16 connected in series with 'the filaments 14, 13 of the lamp and the ballast impedance 11, the breakdown voltage of the thyristor 16 being less than the voltage of the supply 8 but greater than the running voltage of the lamp. The ballast 11 is provided with a second winding 12 and in order to ensure adequate heating of the filaments 14, 15 the ballast is arranged to saturate so as to increase the heating current. On closing a switch 10 the thyristor 16 breaks down and half wave current flows in the series circuit to heat the filaments 14, 15. When these are sufficiently heated the lamp 13 strikes whereupon the voltage across the thyristor 16 falls and the thyristor becomes non conductive thereby breaking the heating circuit for the filaments. The thyristor may be replaced by a series combination of a symmetrical 'diode thyristor and a diode.