| 摘要 |
PURPOSE:To reduce stress exerted on circuit components when attaching and detaching a discharge lamp by providing output control means for a power charge detecting circuit and an inverter circuit. CONSTITUTION:A capacity C6 is charged when power is charged, and a power charge detecting circuit 7 detects it and converts the output of an inverter G6 to L by means of C8R14 for a fixed period of time. In an actuating circuit 2, a trigger Q3 is actuated by charging of C5 so that the output of a comparator IC3 is maintained at L. This output signal is input to an AND gate G2 together with the output signal of the G6 and is input to the R terminal of the counter IC2 of a preheating timer 4 through predetermined gates G7, G3, and the Q output is input to the -R terminal of an R-SFF9 via G8. In an ocsillating circuit 3, a monostable multivibrator IC1 decides the 'on' period of Q2 from the charging current of C7, and, in a preheating setting circuit 5, Q5 and G6 constitute a current mirror and the charging current of C7 is at its maximum when Q7 is on. Switching of Q7 is controlled by the Q output of the FF9 of a preheating tire 4. With this constitution, the output of G6 switches the preheating setting circuit 5 to the preheating mode before oscillation starts so that stress to be exerted on the circuit is reduced at the disconnection and re-installation of a discharge lamp. |
