| 摘要 |
PROBLEM TO BE SOLVED: To secure a safe operation, by detecting the lamp-life ending stage of a discharge lamp. SOLUTION: Thermal fuses 4a1 to 4a4 are provided in respective lead wires on the power supply side and on the non-power supply side of a discharge lamp 4 in order to release filaments 4d when the lamp-life ending stage is detected in terms of temperature in the neighborhood of the filaments 4d of a luminous tube bulb 4b, and a feedback current to a main switch element of a self-excitation inverter circuit 3 for converting a direct current obtained by a rectifying part 2 into a high-frequency alternating current and performing high-frequency lighting of the discharge lamp 4, is taken out from the anti-power supply side and fed back to the inverter circuit 3. |
