| 摘要 |
PURPOSE:To prevent a developer on a sleeve surface from entering the space among both sleeve flanks and a side plate and lumping by bringing the front end part of a thin plate such as a doctor blade into contact with small-diameter parts at both ends of a sleeve. CONSTITUTION:The diameter D2 of the developing sleeve 4 is smaller than the external diameter D1 of the center part at the part almost corresponding to the weak magnetic force area B of a magnet in the sleeve 4 except in the width area A. A sponge seal 11 is provided between this small-diameter part D2 and the surface of a photosensitive drum. Then, thin plates 12 and 13 are provided at the part of the doctor blade 6 almost corresponding to the small-diameter part in contact with the part of the small-diameter part D2. Those plates 12 and 13 are made preferably of nonmagnetic materials which are about 0.05-1.00mm. thick such as polyester films and brass plates. The developer on the surface of the sleeve 4 which is specified with the center part of the blade 6 is stopped with the plates 12 and 13 even when spread toward both ends, and the majority is scraped, so that no developer enters the space among the sleeve 4 and side plates 8 and 9. |
