| 摘要 |
PURPOSE:To suppress an overcurrent porduced due to an overload by controlling the output of an oscillator which drives a swithcing transistor that excites a high voltage transformer at the overload state time. CONSTITUTION:When an overcurrent flows between high voltage output terminals 40 and 41 due to shortcircuit state or the like, a voltage drop is produced at a resistor 37. At this time, the output pulse width from a control ID 47 is reduced by an overcurrent detecting OP amplifier 49, and the output can be temporarily stopped. When a corona discharge phenomenon occurs, the applied voltage of an inverting input terminal of a comparator 25 instantaneously rises, a control transistor is conducted, with the result that a thyristor 17 is triggered. Then, another control transistor is conducted. In this manner, a main transistor 32 is stopped, and a high voltage between the terminals 40 and 41 is stopped. |
