Patent ID: 7925192

Claim:
A developing roller comprising: a developing sleeve; and a magnet roller disposed within the developing sleeve to attract developer to an outer surface of the developing sleeve by magnetic force, the outer surface of the developing sleeve having a plurality of recesses configured with a predetermined circular or elliptic shape in plan view regularly arranged therein so as not to overlap and so as to convey the developer, wherein adjacent ones of the plurality of recesses are arranged on the developing sleeve regularly at a specific interval in each of a circumferential and a longitudinal direction, a longitudinal direction of each of the recesses in the outer surface of the developing sleeve is parallel to a longitudinal direction of the developing sleeve, and each of the recesses in the outer surface of the developing sleeve has a substantially V-shaped cross section in a circumferential direction of the developing sleeve and has an arc-shaped cross section in the longitudinal direction of the developing sleeve.