Inverter circuit for discharge lamps with a voltage step-up circuit for supplying the gate driver of the inverter switches

摘要

An inverter circuit for lighting discharge lamps with reduced power consumption is disclosed. The inverter circuit comprises: a transformer having a resonant circuit formed by a parasitic capacitance of a discharge lamp; an H-bridge circuit to drive a primary side of the transformer at a frequency which is less than a series resonant frequency of the resonant circuit, and at which phase difference in voltage and current at the primary side of the transformer falls within a predetermined range from its minimum; a logic circuit to produce, based on an output signal of an oscillating circuit, gate signals for driving the H-bridge circuit; and a step-up circuit to step up a DC supply voltage (Vcc) based on another output signal of the oscillating circuit, and to supply the logic circuit with the stepped up DC voltage as a supply voltage for producing the gate signals.