| 摘要 |
PURPOSE: To secure complete developing performance without disturbing an already formed toner image on a photoreceptor at the time of forming a multicolor image. CONSTITUTION: A magnet member 3 fixed and set in a rotatable non-magnetic sleeve 2 is provided with a developer regulating magnetic pole 6, a pair of developing magnetic poles 7 positioned on the downstream side of the magnetic pole 6 and consisting of a pair of magnetic poles having different polarity each other, where the magnetic pole having a different polarity from the magnetic pole 6 is arranged on an upstream side, and a pair of peeling and carrying magnetic poles 8 positioned on the downstream side of the pair of magnetic poles 7 and consisting of a pair of magnetic poles having the same polarity each other, which is different from the polarity of the magnetic pole on the downstream side of the pair of magnetic poles 7. In the vicinity of the interpole part of the pair of magnetic poles 7 on the sleeve 2, there exists an area where a component Fr in the normal direction of the magnetic force acting on developer G acts in a direction toward the center of a developer carrier 1 and a component Ft in the tangential direction of the magnetic force acts on the rotating direction of the sleeve 2, and further the ratio of the size of the components in the normal direction and the tangential direction of the magnetic force|Ft/Fr|may be >0.5. |
