| 摘要 |
PURPOSE:To prevent a flame failure when a discharge lamp is deeply dimmed at a low temperature. CONSTITUTION:The output voltage of an inverter circuit 1 is detected by a power detecting means 3, and the output voltage of the inverter circuit 1 is compared with an output reference voltage source E1 by an operation amplifier OP13 and outputted via feedback. The lamp voltage of fluorescent lamps FL1, FL2 is detected by a lamp voltage detecting means 4, and the lamp voltage is compared with a lamp reference voltage source E2 by the operation amplifier OP13. When the lamp voltage is higher than the lamp reference voltage source E2, it is lowered by an operation amplifier OP12. Transistors Q1, Q2 are controlled by the output from the operation amplifier OP3. Even if the voltage of the fluorescent lamps FL1, FL2 rises at a low temperature, the detected lamp voltage is lowered relatively to the lamp reference voltage source E2, thus the lamp voltage can be corrected, and the flame failure of the fluorescent lamps FL1, FL2 can be prevented. |
