| 摘要 |
PROBLEM TO BE SOLVED: To properly control the voltage of DC component even when one or both of vertical voltage width and vertical voltage time ratio are changed by controlling the voltage of the DC component to be superposed according to at least one of the vertical voltage width and vertical voltage time ratio. SOLUTION: A voltage setting part 210 sets the Vp-p or vertical voltage time ratio of a rectangular wave AC voltage or a DC voltage to be superposed on the basis of imaging condition and controls a DC control circuit 220 and a rectangular wave AC control circuit 230. On the basis of the Vp-p center voltage, Vp-p value or the vertical time ratio of rectangular wave AC voltage calculated on the basis of imaging conditions, the DC voltage to be superposed is gained to control a DC control circuit 220. The DC control circuit 220 and the rectangular wave AC control circuit 230 are controlled on the basis of the vertical voltage time ratio, Vp-p value or Vp-p center voltage set by the voltage setting part 210 so as to output a proper voltage as development bias VDB.
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