DISCHARGE LAMP LIGHTING DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device composed by simplifying a circuit structure while meticulously controlling an operation state between a chopper circuit and an inverter circuit according to a light modulation level. SOLUTION: The D.C. output voltage of the chopper circuit 3 can be varied by controlling the on and off states of a switching element Q3. The inverter circuit 4 converts the D.C. output outputted from the chopper circuit 3 to a high-frequency voltage, and applies the high-frequency voltage to a discharge lamp La through a resonance circuit comprising a capacitor C1 and an inductor L1. The output voltage of the chopper circuit 3 and the operation frequency of the inverter circuit 4 are collectively controlled by a control signal from a microcomputer 20. The microcomputer 20 lowers the output voltage of the chopper circuit 3 as compared with a normal lighting time in light modulation, and is provided with a table that is so set as to raise the operation frequency of the inverter circuit 4. COPYRIGHT: (C)2005,JPO&NCIPI