MAGNET ROLLER, DEVELOPING DEVICE AND IMAGE FORMING APPARATUS

摘要

PROBLEM TO BE SOLVED: To prevent the occurrence of periodical density irregularities of a magnet on an image by an inexpensive configuration. SOLUTION: A magnet roller is equipped with: a sleeve which has a cylindrical outer circumferential surface carrying developer and a plurality of concave holes forming surface patterns which are not continuous in any directions on the respective outer circumferential surfaces; and the magnet which is provided in the sleeve and has a plurality of magnetic poles. The minimum partial area ratio of a plurality of partial area ratios obtained by dividing the outer circumferential surface of the sleeve into a plurality of regions parallel to a sleeve shaft and dividing the total area of the plurality of concave holes formed in each region by the area of each region is set at about 20% or more. COPYRIGHT: (C)2010,JPO&INPIT