| 摘要 |
PROBLEM TO BE SOLVED: To secure safety and public standard by reducing inverter output when a discharge lamp fails and controlling output constantly when there is no discharge lamp. SOLUTION: Discharge lamp failure is detected by VL, IL detection circuits 9 and 10, and the presence or absence of the insertion of the discharge lamp is detected by a filament placement detection means 13. When the discharge lamp fails while a discharge lamp 7 is placed, output is reduced to and retained at the output lower limit of an inverter 12 (a first level), the above output reduction/retention is canceled when the discharge lamp 7 is removed, and the output of the inverter 12 is controlled to a constant set value (a second level), thus keeping the unloaded secondary voltage of the inverter 12 to be within a constant value of ±10% (nominal standard) for the scattering of circuit parts when the discharge lamp 7 is removed from the device after the discharge lamp failure is detected. |
