| 摘要 |
PURPOSE:To turn ON or OFF the output of a high voltage transformer without stopping the output of an oscillator by controlling a switching circuit by a supply voltage to the switching circuit for driving the transformer. CONSTITUTION:When a high voltage output switch SW is OFF, a transistor Tr4 is turned ON by the voltage generated at both ends of a resistor 10, and a transistor Tr3 is turned OFF. Since a power source Vcc is not supplied to a transformer T2, an output is not generated at the secondary side of the transformer T2, and a flyback transformer T1 is not driven. Since the high voltage output is not generated at this time, one input of an error amplifier 6 is not 0, the output becomes maximum, and a control circuit 5 controls the frequency of an oscillator 4 so that the output becomes maximum. Thus, the output of the transformer T1 can be controlled without disconnecting the output of the oscillator 4.
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