Developing roller, electrophotographic process cartridge, and electrophotographic image forming apparatus

摘要

A developing roller is provided having an elastic layer and a surface layer superposed thereon. The surface layer is formed of a resin material containing nitrogen atoms, and contains at least two types of particles, organic-compound particles (M) and organic-compound particles (N). The particles (N) are composed of nitrogen-containing heterocyclic-compound particles. The number-average particle diameter of the particles (N) in the surface layer is smaller than the number-average particle diameter of the particles (M) in the surface layer. Where the universal hardness of the elastic layer is represented by A and the universal hardness of the developing roller is represented by B, they satisfies 0.9<=B/A<=1.8.