GB500988A - Improvements in circuits for operating electric discharge devices - Google Patents

Abstract

500,988. Discharge lamps etc.; switches. GENERAL ELECTRIC CO., Ltd. (Patent- Treuhand-Ges. f³r Elektrische Gl³hlampen) Oct. 27, 1937, No. 29391. [Class 39 (i)] [Also. in Group XXXVII] In a circuit arrangement of the type in which a main circuit carries the main discharge current of an electric discharge device and a subsidiary circuit is adapted to carry for example, a starting current for heating an electrode or the current in an inductive circuit whose breaking provides a starting impulse, and is adapted to be made as, or just before, the main circuit is made and to be broken a predetermined time afterwards, the switches for the main and subsidiary circuits are mechanically linked together, so that the closing of the main switch closes the subsidiary switch also, and the latter is of the kind in which, on operation, a flow of mercury first closes contacts and then re-opens them after a predetermined interval. The subsidiary switch 8, Fig. 2, is in the circuit of the thermionic cathodes 18 of a discharge lamp 17, and is in parallel with the discharge path. The switch 8, comprising a tube through which are sealed two contacts 9, Fig. 1, and which join bulbs 10, contains enough mercury to fill one of the bulbs, and is carried on a spindle 2. The contacts 9 are connected by spring pieces 15, 16 to contact plates 13. A bridge plate 6 carried by the spindle connects contact plates 5 and constitutes the main switch 20. In the position of the main switch shown the switch 8 would, actually, be perpendicular to the plane of the paper, so that when the main switch 20 is closed the subsidiary switch is closed for a period depending on the dimensions of the tube. 'Specification 955/05, [Class 391, is referred to.