| 摘要 |
PURPOSE:To make the securing of the amount of developing agent carried for development compatible with the setting of a narrow gap between a latent image carrier and a sleeve and further, to essentially improve developability, while reducing the cost of a device. CONSTITUTION:In a type having a developing agent carrier 1 having a magnet roll 3 fixedly installed in a rotatable nonmagnetic sleeve 2, developing agent moving magnetic poles 5 are provided on the part of the magnet roll 3 corresponding to a part except an effective developing region E of the developing agent carrier 1 and extended parts F adjacent thereto, while a magnet sheet 6 constituted in such a manner that plural groups of magnetic poles 6a and 6b having a different polarity are alternately arranged is attached to the part of the magnet roll 3 corresponding to the effective developing region E of the developer carrier 1 and the extended regions F adjacent thereto. Moreover, a magnetic shield member 7 for shielding a magnetic field from the developing agent moving magnetic pole 5, affecting the magnet sheet 6 is provided as necessary. |
