| 摘要 |
PROBLEM TO BE SOLVED: To provide a developing device which securely prevents leakage of magnetic developer at both ends of a developer carrier by means of magnetic plates, provided on both the ends of the developer carrier, and a magnetic brush formed by magnet plates and a magnet roller in the developer carrier. SOLUTION: A magnet plate 22 is set outside a magnetic plate 18 encircling, but not in contact with, the periphery of each end of a developing sleeve 10, and also encircles, but not in contact with, the periphery of the developing sleeve 10. The magnetic-pole structure of the internal surface of each magnet plate 22 facing the developing sleeve 10 in the axial direction of the developing sleeve has such a magnetic-pole arrangement that, in terms of the repulsion magnetic pole N3 of the magnet roller and the N 22, magnetic brushes of developer are not formed between the surface of the developing sleeve of the magnet roller where the magnetic pole N3 is situated upstream in the direction of the rotation of the developing sleeve and the part of the magnet plate corresponding to it, and between the surface of the developing sleeve 10 outside the magnetic pole N3 and the part of the magnet plate 22 corresponding to it. |
