| 摘要 |
PROBLEM TO BE SOLVED: To stabilize the development property such as the reproducibility of thin line, the depolarization in the development, or the like without lowering the developing performance, by specifying the magnitude of the magnetic flux density in the normal direction, of the magnetic poles containing a developing area, and an angle containing the developing area. SOLUTION: In interpole development, a developing area is set between the magnetic poles of the polarities different from each other, when the closest distance between an image forming member and a developing sleeve is 400-700μm, the magnetic flux density in the normal direction, of the developing sleeve face of the magnetic pole is 700-1200 gauss, the difference in the magnetic flux densities in the normal direction of the developing sleeve faces between the both magnetic poles, is not more than 100 gauss, and an opening angle of the lines of magnetic force in the normal direction, of the both magnetic poles, containing the developing area is 60-90 deg.. Further the widths D, E in the distribution of the magnetic force, of 50% point A, A' of the magnetic flux density in the normal direction, is less than 60 deg., and the widths F, G in the distribution of the magnetic force of 80% point B, B' of the magnetic flux density is not more than 40 deg.. Further the difference between the widths D, E and F, G in the distribution of the magnetic force in the less than 50% and 80% of magnetic flux density in the normal direction on the developing sleeve of the both magnetic poles, is less than 20%. |
