US Patent 7970322 Developing roller, developing apparatus, and image forming apparatus

A developing roller includes a cylindrical sleeve that holds developer on a peripheral surface thereof, and a magnet roller being provided in the sleeve and having a plurality of magnetic poles. The sleeve includes a plurality of micro-recesses formed on the peripheral surface thereof, and the plurality of micro-recesses are arranged dispersedly in the axial direction and the circumferential direction of the sleeve. The densities of the micro-recesses in both end portions of the sleeve are larger than the density of the micro-recesses in a central portion of the sleeve.