Patent ID: 7313350

Claim:
A developing apparatus that develops an electrostatic latent image formed on an image-bearing body with a developer into a visible image, comprising: a developer-bearing body having a surface on which a thin layer of the developer is formed, said developer-bearing body ( 51 ) being disposed such that the thin layer of the developer is brought into pressure contact with the image-bearing body; a developer-layer forming member that is in pressure contact with the surface of said developer-bearing body to form the thin layer of the developer on said developer-bearing body; a developer-supplying body that supplies the developer to the surface of said developer-bearing body; wherein the developer has particles such that (1) developer particles have a volume mean particle diameter DV in the range of 1 μm<DV<7 μm, (2) the developer particles have a roundness in the range of 0.9<roundness<0.97, (3) small-diameter particles not smaller than DV×0.5 μm represent not more than 20% of a total number of particles by number percentage, and (4) large-diameter particles not smaller than DV×2.0 μm represent not more than 1% of a total volume of particles by volume percentage; wherein the surface of said developer-bearing body has an average surface roughness Rz such that 1 μm<Rz<DV, Rz being ten-point height of irregularities.