| 摘要 |
PURPOSE:To prevent an inverter circuit from being applied with stress when a discharge lamp is not lighted and recover the discharge lamp to the original lighted state for the temporary drop of the power voltage. CONSTITUTION:The potential of a connection point of resistors R2, R3 dividing the both-end voltage of a capacitor C0 serving as the DC power source of an inverter circuit 1 is compared with the reference voltage by a comparator CP. When a timer circuit 4 counting the startable time of a discharge lamp D is operated after a power source is turned on, a switching transistor Q is turned on, and a resistor R5 is connected in parallel with the resistor R3. While the timer circuit 4 is operated, the input voltage to the noninverted input end when the output of the comparator CP of a reset circuit 6 becomes the H-level can be set lower than that after the counting is completed. Even if the power voltage drops while the timer circuit 4 is operated, the reset circuit 6 is not operated, and the reset circuit 6 can be set to be operated when the power voltage drops after the counting is completed. |
