| 摘要 |
PURPOSE:To prevent securely a charge on an image carrier from leaking owing to the contact of a developer magnetic brush with an image carrier by smoothing the surface of the sleeve of a developing roller positioned at the upstream side of the image carrier in its moving direction. CONSTITUTION:The sleeve 1441 of the 1st developing roller 1311 has its surface 1441a worked into a smooth surface of about 3mum in roughness and a developer magnetic brush 1351 on the sleeve 1441 is easily removed. The sleeve 1442 of the 2nd developing roller 1312 has its surface 1442 roughened to 10-200mum and a higher bristle-upstanding state than the developer magnetic brush 1351 formed by the 1st developing roller 1311 is obtained. Consequently, when images are developing by the 2nd developing roller positioned at the downstream side of the image carrier in its moving direction, a charge on the image carrier is prevented securely from leaking owing to the contact of the developer magnetic brush of the 1st developing roller with the image carrier. |
