US Patent 7312582 Electronic ballast

An electronic ballast for driving at least one lamp comprising a rectifying circuit operatively connectable to an AC line; a current drawing circuit connected across said rectifying circuit; and an inverter circuit connected to said rectifying circuit that supplies a lamp current to said at least one lamp; wherein said current drawing circuit draws current from said AC line when the instantaneous voltage of said AC line nears zero to reduce the total harmonic distortion of the input current drawn by said ballast.