GB395224A - Improvements in or relating to devices comprising a luminous electric discharge tube - Google Patents

Abstract

395,224. Discharge lamps. NAAMLOOZE VENNOOTSCHAP PHILIPS' GLOEILAMPENFABRIEKEN, 13D, Emmasingel, Eindhoven, Holland. Nov. 3, 1932, No. 31025. Convention date, Nov. 13, 1931. [Class 39 (i).] A lamp having a negative current voltage characteristic, more particularly having a positive column discharge, is furnished with a grid and is supplied with a current taking periodically the value zero without series resistances, and the circuit is such that the grid voltage becomes negative in or before the period when the discharge current is zero and does not become zero or positive until some time after the moment when the anode potential becomes positive, at which time the anode potential is still increasing. The tube may be supplied with continuous current from a circuit which is periodically broken by an interrupter. The grid is connected to a negative voltage through an interrupter so constructed that at the moment when the discharge current becomes zero the grid has supplied to it a negative voltage this grid remaining negative during a given time. In a modification, as shown in the Figure, the tube is supplied from an alternating voltage 5 which supplies also a circuit including the primary 7 of a transformer, and a resistance 8 and inductance 9 in parallel. The secondary 10 of the transformer is connected through a resistance 11 to the grid 4 which may be a ring sealed to the glass wall. Adjustment of the resistance 8 varies the phase difference between grid and anode voltages and thereby the time of striking of the current in each half-cycle, whereby the average luminosity of the tube is varied. Specification 384,555 is referred to.