| 摘要 |
An electrophotographic printer maintains a surface potential of a photosensitive drum at a constant value even when a photosensitive layer corresponding to a surface of the photosensitive drum wears down. The electrophotographic printer includes a charging power supply 3, a charging roller 1, a photosensitive drum 2, a discharge unit 11, a charging current detection unit 4, a transfer power supply 9, a transfer roller 8, a transfer current detection unit 14, an arithmetic and control unit 12, and a memory unit 13. The arithmetic and control unit controls the photosensitive drum to make a plurality of revolutions in a state when the discharge unit is turned off in an initial operation of the electrophotographic printer, controls the charging power supply to generate a charging voltage to obtain a charging current as the surface potential -Vsf of the photosensitive drum, obtains a transfer current detected by the transfer current detection unit, calculates the charging current needed in obtaining the obtained transfer current in a state when the discharge unit is turned on, and stores the calculated charging voltage in the memory unit, and in a real printing procedure, the arithmetic and control unit rotates the photosensitive drum in the state where the discharge unit is turned on, and equalizes the charging voltage output from the charge power supply to a value stored in the memory unit.
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