| 摘要 |
PURPOSE:To increase X-ray dose and improve the linearity of the relation between exposure time and dose by making the rise time characteristics of a tube voltage waveform good without the degradation of stationary characteristics in a case of stabilizing the tube voltage waveform by feedback- control. CONSTITUTION:The positive input (b) of an error amplifier 12 is an additive signal of a voltage set value Vset and an output (a) of a voltage generator 21 whose output a becomes larger than the voltage set value Vset only at the time of starting X-ray exposure. For this reason the output (d) of the error amplifier 12 increases not gradually but abruptly. The increase of the output (d) of the error amplifier 12 means the increase of supply energy to the load from a DC-DC converter. Therefore, as shown by solid line, the output (d) of the error amplifier 12 increasing abruptly right after the start of X-ray exposure, power to the load can be supplied not only by the discharge of energy charged in a smoothing capacitor 5 beforehand, but also from the DC-DC converter. Consequently, the voltage of the smoothing capacitor 5 does not happen to decrease and can be controlled to a predetermined voltage.
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