| 摘要 |
PURPOSE:To aim at preventing an overcurrent and an overvoltage from being generated by generating a switch closing signal during the cycles before and after the zero cross of a resonance current, and then controlling the generating timing of a main signal according to a detected output. CONSTITUTION:When a switch SW31 is closed, the primary current bypasses the primary winding 6a of a transformer 6, so that voltage is not induced in the secondary winding 6b, and therefore, if the SW31 is closed in an arbitrary period of one impulse of the current wave form in the primary current, the output voltage can be controlled. In the case where there is a change in the tube current, in order to throttle the output completely, after the lapse of a prescribed time from the zero cross timing of a resonance current, by using a switch controlling means 25, the second switch-closing signal is generated and supplied to the SW31. The timing of generating this signal is controlled by a main controller 26 according to the results of detection made by a tube current detecting means 40 for an X-ray tube 9 and an a.c.-voltage detecting means 41 for the power supply 1. Thereby, an overcurrent and an overvoltage can be prevented from being generated.
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