Patent ID: 7356295

Claim:
A developer-carrying member to transport a developer having a carrier to a developing area facing an image carrying member in an image forming apparatus, the developer-carrying member comprising: a sleeve configured to carry the developer on a surface of the sleeve; wherein the surface of the sleeve is formed with a plurality of grooves extending in an axial direction of the sleeve, and wherein the surface of the sleeve receives a surface treatment to make concave and convex portions thereon, and wherein the surface treatment forms a shape of a plurality of concave and convex shaped portions which prevents abrasion of the carrier on the surface of the sleeve; wherein the surface of the sleeve has a maximum roughness Rmax of one-sixth or greater than a particle diameter of the carrier, and a surface index of 1.5 or greater, wherein the surface index is expressed by an equation of surface index = R max/( L total âˆ’LL ), wherein LL is a measurement range length selected from a roughness profile of the surface of the sleeve, L total is a total surface distance of the developer-carrying member in the measurement-range length LL, and Rmax is a maximum roughness of the sleeve surface, and wherein Rmax is defined by a difference between a maximum roughness value and a minimum roughness value on a roughness profile of the surface of the sleeve.