GB801586A - Improvements in operating circuits for electric discharge lamps - Google Patents

Abstract

801,586. Supply systems for space-discharge lamps. METROPOLITAN-VICKERS ELECTRICAL CO., Ltd. May 13, 1955 [Oct. 22, 1954], No. 30538/54. Class 38 (4). In a circuit arrangement for starting and operating a C.P. fluorescent discharge lamp 2 in which a D.C. source 1 provides the lamp operating potential and an alternating potential pre-heats one electrode 5 of the lamp, the preheating circuit includes inductance 10 and capacitance 8 of such reactions as to be substantially resonant at the alternating potential frequency and the inductance 10 furthermore is series connected with the D.C. source 1 and lamp-discharge space so that, during starting, the potential drop created across the inductance by the flow of alternating current is added to the D.C. source potential to produce a lamp discharge initiating voltage. As shown the lamp is ballasted by a resistor 6, and there is operated in parallel with it one or more lamps 2, each having individual ballasting resistor 6<SP>1</SP> and pre-heating circuit components 8<SP>1</SP>, 10<SP>1</SP>. The inductance may form the primary winding of a transformer, the secondary winding 13 of which pre-heats during starting the other lamp electrode 41 which during operation is an anode. The source 7 of alternating potential may be a vibrator or a small alternator, and when the invention is used for traction vehicle lighting the D.C. source may be a battery or a motor generator set. The pre-heating circuits are controlled by normally open switches 9, 9<SP>1</SP>, shown as manually operable. Individual normannly closed switches 11, 11<SP>1</SP> permit interrupting the lamp discharges but if all the lamps are to be switched off simultaneously these switches may be replaced by a single switch, not shown, connected in either of the D.C. source leads 3, 3<SP>1</SP>. The Provisional Specification states that the alternating potential may be an intermittant potential.