| 摘要 |
PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device capable of ensuring control of an inverter circuit even if a discharge lamp is disconnected. SOLUTION: The condition of a fluorescent lamp FL is detected by a starting malfunction detecting circuit 7, when not started, and by a closing life detecting circuit 5, when in a closing life, to decrease the output of an inverter circuit 3. When either one of the filaments FL1, FL2 of the fluorescent lamp FL is disconnected, a capacitor C3 is disconnected, so that a current in a primary winding Tr1a for a drive transformer Tr1 can flow in a ballast choke L2, a resistor R3, a resistor R4, a resistor R2, the primary winding Tr1a for the drive transformer Tr1 and a DC cut capacitor C2, in sequence. The capacity of the DC cut capacitor C2 is sufficiently large and negligible and, if values for the resistor R3 and the resistor R4 are increased in the condition that there is almost no capacitor component, self-excitation oscillation cannot be maintained and the oscillation of the inverter circuit 3 is stopped. |
