| 摘要 |
PURPOSE:To prevent an oscillation from becoming incomplete at starting time by limiting the upper limit of a feedback voltage to an integrator for controlling the operating timing of an auxiliary transistor at the secondary side of a feedback transformer, thereby suppressing the rise of the oscillating frequency at the starting time. CONSTITUTION:When an AC power source is turned ON to generate a DC output at a rectifier 3, a capacitor C1 is charged, a switching transistor 1b is conducted, and an inverter is started to start oscillation. Immediately after the starting, fluorescent lamps F1, F2 do not arrive at the discahrgeable state, a high feedback voltage generated at the secondary winding W2b of a trans former T1 is limited by a resistor R2b and a Zener diode ZD2b to charge a capacitor C3b. Accordingly, it can prevent an early storage due to the high feedback voltage, thereby suppressing the short oscillating period. Switching transistors Q1a, Q1b continue oscillation by alternately turning ON and OFF the auxiliary transistors Q2a, Q2b. |
