| 摘要 |
PURPOSE:To prevent the fogging of an image and the oversupplying of toner in a printer using an electrophotographic system. CONSTITUTION:The surface potential of a photosensitive drum 1 uniformly electrified by a main electrifier 3, is measured by a surface potential sensor 4, and the image potential of the photosensitive drum 1, after being outputted with a laser beam 5 out of a printing guarantee region, is measured by a surface potential sensor 7, so that a potential difference between the surface potential sensors 4 and 7, before after an exposure, is controlled, and when the potential difference is out of a specified range, abnormality is informed to the side of a device main body. Therefore, a laser exposure is executed in a place out of the printing guarantee region in the main scanning direction for printing, of the photosensitive drum 1 (for instance, the solid image of 8mm width), the image potential is measured by the surface potential sensor 7. |
