Patent ID: 7127200

Claim:
A developing roller comprising an elastic layer and a surface layer, wherein; said surface layer has at least a nitrogen-atom-containing resin, organic-compound particles (M) and organic-compound particles (N), said organic-compound particles (N) are nitrogen-containing heterocyclic-compound particles, said the organic-compound particles (M) and the organic-compound particles (N) have a volume resistivity of 1.0×10 9 Ω·cm or more, a number-average particle diameter of said organic-compound particles (N) in said surface layer is smaller than a number-average particle diameter of said organic-compound particles (M) in said surface layer, and a universal hardness A (N/mm 2 ) of the surface of said elastic layer and a universal hardness B (N/mm 2 ) of the surface of said developing roller satisfy the relationship of the following expression: 0.9≦ B/A ≦1.8, where the universal hardness A (N/mm 2 ) and the universal hardness B (N/mm 2 ) are measured at an indentation depth of 40 μm in the vertical direction from the surface of the elastic layer and the surface of the developing roller, respectively.