| 摘要 |
PROBLEM TO BE SOLVED: To obtain stable photographing tube current in a short preparing period, even if a preheating value of a filament is varied by controlling the heating current of the filament with a target heating current value in photographing generated with a overshoot value corrected with an overshoot correcting means and a value set with a photographing heating current setting means. SOLUTION: An overshoot value from an overshoot circuit 8 is multiplied by a correcting gain, corresponding to a preheating value from a gain table memory 9 with a multiplication circuit 10 to prepare a correcting overshoot value. A heating value from a regular heating/preheating switching switch 7 and the correcting overshoot value prepared with the multiplication circuit 10 are added with an adding circuit 11 to prepare a heating target value. A current feedback control circuit 12 controls an inverter circuit 2, so that a current value detected with a current detecting circuit 6 matches with a target value prepared with the adding circuit 11.
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