| 摘要 |
PURPOSE:To stabilize the power of a discharge lamp by converting the DC output of a DC converter into AC via an inverter so as to supply the discharge tube, and controlling the output of the converter so as to be constant power based on the detected results of the voltage and the current of the converter output. CONSTITUTION:The voltage and the current of a converter 6 output are detected by a voltage detector 7 and a current detector 8, and these detected signals are operated by an arithmetic circuit 9 so as to be sent to a PWM control circuit 10. Next, the signal is compared with a standard signal in the circuit 10 so as to PWM-control the converter 6 and control an output voltage. In this way, the output voltage decreases in the converter 6 when the impedance of a load discharge lamp 3 is low while it increases when the impedance is high, the output is kept constant within a reversible range, regardless of the impedance of the discharge lamp 3. It is thereby possible to stabilize the power of the discharge lamp 3 by a simple circuit configuration and prevent deterioration owing to an excess input. |
