| 摘要 |
PROBLEM TO BE SOLVED: To realize a configuration that enables both image unevenness and deterioration of the developer to be restrained.SOLUTION: At least one magnetic pole out of a draw-up pole, a cut pole and a peel-off pole of a magnetic roll arranged in a developing sleeve 44 is subjected to processing in the following way. In a part corresponding to an image formation area of the developing sleeve 44 in the direction of its rotation axis, the magnetic force of the pertinent magnetic pole is increased on the downstream side, relative to the vicinity of the central part of the developing sleeve 44 in the direction of its rotation axis, of the developer conveying direction of a first conveying screw 46a. Further, the average value of the magnetic force in the downstream side of the developer conveying direction, where the magnetic force is increased, is kept at not less than 2.5 mT but not more than 10 mT relative to the average value of the magnetic force corresponding to a one-pitch equivalent of the magnetic force of the first conveying screw 46a in the vicinity of the central part.SELECTED DRAWING: Figure 13 |
