| 摘要 |
PROBLEM TO BE SOLVED: To securely light a discharge lamp when the lamp is re-mounted after it is removed. SOLUTION: As a discharge lamp 41 is lighted, when the lamp is removed, this is detected by an abnormality detection circuit 7 to start counting by a timer circuit 10. A comparator circuit 9 outputs a detection signal to a control circuit 5 and a timer reset circuit 11 once a counted time has reached a set value. An output of an inverter circuit 3 is thus stopped, and the time circuit 10 is reset. One filament of the discharge lamp 41 is mounted, and a filament mount detection circuit 8 detects this, then the comparator circuit 9 is reset to operate the inverter circuit 3. At this point, the abnormality detection circuit 7 detects abnormality to start counting by the timer circuit 10 again from a reset condition, where the counted value will not reach the set value before the other filament of the discharge lamp 41 is mounted on a load circuit 4, thereby the inverter circuit 3 continues correct operation to light the discharge lamp 41. |
