| 摘要 |
PROBLEM TO BE SOLVED: To prevent the occurrence of the staining of image backgrounds in both end parts in the axial direction of a developing roll by locally increasing developer quantities in the both end parts in the axial direction of the developing roll. SOLUTION: The length L1 in the axial direction of a pole N1 used both for dividing/carrying a developer in a first developing roll 10 is set to be shorter than the length L2 in the axial direction of a pole N2 used both for dividing/ carrying the developer in a second developing roll 20. Thus, a magnetic force balance between the first and second developing rolls 10 and 20 is different from each other in the central parts and the both and parts in the respective rolls 10 and 20. Thus, the developer quantities are locally increased in the both end parts of the first and second developing rolls 10 and 20. Therefore, weakening of the nipping pressure with respect to the edge part of the developer is prevented from being dull in a developing part to prevent the occurrence of the staining of image backgrounds in the both end parts in the axial direction of the developer roll. |
