Dimmable electronic gas discharge lamp ballast

Claim 1

A two-wire electronic dimming ballast arrangement for one or more gas discharge lamps comprising: a source of variable pulse width square wave electric power; a source of full-wave rectified AC; single inverter means adapted to be driven by said variable pulse width electric power; first transformer means for supplying electric power of substantially constant voltage to the heating filaments of said one or more gas discharge lamps connected to the output of said inverter means; control means for modulating the pulse width of said variable pulse width square wave electric power driving said inverter means; distortion suppression means for suppressing current abberations and achieving substantially a unity power factor associated with said control means, said distortion suppression means further comprising: first signal generating means for generating a continuous signal indicative of the instantaneous value of the voltage of said full-wave rectified AC, second signal generating means for generating a continuous signal indicative of the instantaneous value of the current of said full-wave rectified AC, comparator means in said control means having first and second inputs connected to the outputs of said first and second signal generating means, respectively, said comparator means generating an error signal output therefrom indicative of any phase or shape difference between said rectified voltage and said rectified current and wherein any error signal output from said comparator induces said control means to modulate the pulse width of said variable pulse width electric power driving said inverter in a manner such that the drawn current changes shape to match said voltage; and dimming means associated with said first signal generating means for modulating the output of said one or more gas discharge lamps by modulating the output of said first signal generating means.