| 摘要 |
PURPOSE:To accurately detect an electric potential and to control it with high precision even if unevenness in electrification occurs in the main scanning direction of an image carrier by detecting the surface electric potential of the image carrier with the aid of an electric potential sensor at plural spots in the main scanning direction of the image carrier. CONSTITUTION:Electrification is sequentially and uniformly executed on a photosensitive drum 1 which rotates in a direction shown with an arrow by a primary electrifier 2, and other electrifiers 5-7 being in off-state, turn a preexposure unit 9 on. Meanwhile, an electric potential sensor 11 starts the measurement of the surface electric potential from one end of the photosensitive drum 1 while fetching data and it is moved in the main scanning direction of the photosensitive drum 1 with the aid of an electric potential sensor driving means 12 to measure to another end. Next, the data is inputted in an electric potential control circuit 14 through an electric potential measurement circuit 13 and it is arithmetically processed to transmit a signal to a primary electrifying transformer 17 and control the corona total current which is impressed on the primary electrifier 2, so that the specified proper surface electric potential can be obtained on the photosensitive drum 1. Even if the unevenness of the surface electric potential occurs in the main scanning direction, the accurate measurement can be possible, thereby executing the excellent control. |
