| 摘要 |
PROBLEM TO BE SOLVED: To provide a developing device which can be miniaturized by making the diameter of a developing sleeve small and stably secure excellent sealability by preventing the increase of torque caused by the increase of the rotational torque of the developing sleeve. SOLUTION: The developing device 11 is constituted to provide the developing sleeve 6 which includes a magnet roller 7 and carries toner (developing) 13 having magnetic grains (carriers) to a developing region to develop an electrostatic latent image formed on a photoreceptive drum (image carrier) 10. In such a case, the magnet roller 7 is composed of the rare earth resin magnet and a magnetic seal consists of a magnet 8 surrounding at least a part of the outer periphery of the sleeve 6, so that the leakage of the toner 13 from the end part of the sleeve 6 can be prevented by the magnetic seal. Thus, the rare earth resin magnet having an excellent magnetic characteristic is used for the magnet roller 7, so that the diameter of the sleeve 6 can be made so small as to miniaturize the developing device 11. Further, the magnet 8 is used for attaining magnetic sealing against the toner, which prevents the increase of the torque of the sleeve 6 and secures the excellent sealabilitly. |
