DRIVE CIRCUIT FOR HIGH-INTENSITY DISCHARGE LAMP

摘要

PURPOSE: An HID(High Intensity Discharge) lamp driving circuit is provided to secure stable driving of the HID lamp by preventing an overvoltage after ignition of the HID lamp. CONSTITUTION: A power supply unit(1) rectifies AC power to DC power. An inverter(2) converts the DC power to the driving power of the lamp according to a switching driving signal. A control value generator(4) outputs a driving control signal for controlling a switching driving signal. An error amplifier(5) outputs the voltage in proportion to the difference between the output of the control value generator and the current transformer. A start frequency setting circuit(9) controls an initial voltage applied to the lamp. A voltage controlled oscillator(6) outputs the frequency corresponding to the output voltage of the start frequency set circuit and the output voltage of an error amplifier.