| 摘要 |
PROBLEM TO BE SOLVED: To turn off a switching transistor(TR) before the end of a blanking line period by revising a duty cycle of the switch in response to a feedback signal representing fluctuation of a load energized by a stabilized DC voltage. SOLUTION: When a switching TR Q1 is conductive in the scanning mode, an output of an error amplifier 33 is at H initially and the TR Q1 is conductive by charges given to a capacitor C1 through a resistor R3. AN output of the amplifier 33 changes to an L level at a request point of time, the TR Q1 is turned off and the charged of the gate is eliminated via a resistor R1. When a catch diode D6 is conductive in the circuit, a capacitor C3 is charged and when the combination of an unregulated B+ voltage and the blanking line pulse rise after the end of the blanking period, the charge is given to a capacitor C2 connecting to the gate of the TR Q1 by feeding the charge from the capacitor C3 to the capacitor C2. |
