Full-bridge inverter for discharge lamp lighting device with varied transistor zero voltage period

摘要

A discharge lamp lighting device employs first and second series circuits, each series circuit including two switching elements and a connecting point located therebetween. The first and second series circuits are both connected in parallel across a DC voltage source. A load circuit, including a discharge lamp, is connected between the two connecting points in the first and second series circuits. ON/OFF timing of the switching elements in the first series circuit varies between in-phase and 180 degrees out-of-phase from ON/OFF timing of the switching elements in the second series circuit. The ON period ratio of the switching elements is different in at least one of the first and second series circuits. The device allows dimming of the discharge lamp over a wide range, and lighting of the discharge lamp with a small supplied power.