DISCHARGE LAMP OPERATING DEVICE

摘要

A discharge lamp operating device provided with a high-frequency inverter, a plurality of discharge lamps, a detecting resistor connected between a terminal of the inverter and the ground, a circuit for integrating the voltage generated by the detecting resistor, an error amplifying operational amplifier that receives the integrated output as a negative input and a target value as a positive input, an inverter switching frequency control driver that operates according to the output of the operational amplifier, a frequency detecting comparator of which the output value changes depending upon the frequency of the output of the operational amplifier, and a control circuit for changing over the operating condition of the driver according to the output value of the frequency detecting comparator. Even when a plurality of lamps are fit, the circuit can be protected without detecting the last stage of the life of each lamp.