| 摘要 |
PURPOSE:To obtain an AC high voltage output with low cost, compactness and having a few very low frequency level change by providing a means controlling an output intensity control means so that a secondary side load current or voltage is a constant value. CONSTITUTION:A high tension current flowing to a load 18 is detected as a voltage via a detection resistor 19. The detected voltage is rectified and smoothed by a diode 84C, a capacitor 84 and a resistor 84B, and a value corresponding to a negative current component of transformers 14A, 14B is led to an inverting input of an error amplifier 25A comprising an operational amplifier 25A. A reference potential formed by resistors 22, 23 and an applied inverting input are compared in the amplifier 25A. That is, when the difference between the positive and negative components of the high voltage output of a non- inverting input is higher, a low level is outputted, and when converse, a high level is outputted and when the both are at equipotential, the stable state is kept. Thus, the center potential of the control signal subject to phase shift in pulse modulation circuits 27A, 27B is controlled in response to the negative component of the high voltage synthesis output.
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