| 摘要 |
PROBLEM TO BE SOLVED: To prevent the degradation in image quality by improving ear cutting performance and sufficiently performing ear cutting. SOLUTION: The development unit for forming an image on a photoreceptor drum 21 by using a magnetic developer is equipped with a developing unit 22 which internally has the magnetic developer, a rotary sleeve 31 which is mounted on the developing unit 22, is internally provided with a plurality of magnets, and conveys the developer on the surface, and a stationary sleeve 32 which is arranged to face the rotary sleeve 31 and is internally provided with a mobile magnet 37. The positional relation of both the magnets including the distance between the magnet of the rotary sleeve 31 and the mobile magnet 37 of the stationary sleeve 32 is such that the ear cutting force F expressed by formula: F=kxml(T)xm<SP>2</SP>(T)/r<SP>2</SP>turns to 950×10<SP>-2</SP>(N) or over between the rotary sleeve 31 and the stationary sleeve 32 when the development is not performed. COPYRIGHT: (C)2007,JPO&INPIT |
