Discharge lamp lighting apparatus

Abstract

There is provided highly efficient discharge lamp lighting apparatus capable of reducing its cost by reducing high withstand voltage components on the secondary side of a high voltage transformer and stabilizing, its circuit operation. A discharge lamp lighting apparatus () comprises a high voltage transformer (), a switching circuit () for driving the primary side of the high voltage transformer (), and a triangular wave generation circuit () for determining the operation frequency of the switching circuit (). The triangular wave generation circuit () includes a frequency switching means () for switching the operation frequency of the switching circuit () between before and after the lighting of a discharge lamp (). At the secondary side of the high voltage transformer (), a resonant circuit having a capacitance component consisting of only a parasitic capacitance (C) is also formed. Before the lighting of the discharge lamp (), the switching circuit () is operated at a frequency around the series resonance frequency of the resonant circuit on the secondary side. After the lighting of the discharge lamp (), the switching circuit () is operated at a frequency around the frequency at which the phase difference between the voltage and the current on the primary side becomes minimum.