Patent ID: 6359395
Filing Date: 2002-03-19
Classification: G05F,H02M,H05B,Y02B

Abstract:
A control circuit that interconnects an output line to a gas discharge lamp, said control circuit being connected to a source of DC voltage, having first and second terminals, said control circuit being powered by a DC voltage applied from said source of DC voltage across a pair of input lines, the control circuit comprising:a basic control circuit comprising: a smoothing capacitor connected across said pair of input lines, a pair of switching devices connected in series across said pair of input lines, said output line being connected to the junction of said pair of serially connected switching devices, there being a switching control associated with the switching devices for switching the switching devices to conduct alternatively between positive and negative ones of said pair of input lines at a predetermined high frequency, there being a finite time between each of the switching during which both of said switching devices are in a non-conductive state, a resonant load including gas discharge lamp connected at a first end to said output line, a return path for connecting a second end of said load circuit to both of said pair of input lines; an electromagnetic interference suppression circuit connected between said source of DC voltage and said basic control circuit, comprising: a unidirectional device serially connected between said first terminal of said source of DC voltage and a first of said pair of input lines to prevent current from flowing from said basic control circuit to said source of DC voltage, and a filter capacitor connected across said first and said second terminals of said source of DC voltage.