Abstract: A conductive roller includes: a core member including an outer surface along and about an axial line thereof; and a surface layer arranged along the outer surface of the core member. The surface layer includes a conductive portion, and a surface roughness imparting material in a form of particles dispersed in the conductive portion. An average particle size of the surface roughness imparting material is in a range of 6 micrometers or greater and less than 10 micrometers. The number of particles of the surface roughness imparting material per unit area of the surface layer is in a range of 3.5×105 particles per mm2 or greater and 7.5×105 particles per mm2 or less. An average thickness of the surface layer is in a range of 0.2 micrometers or greater and 5.5 micrometers or less.

Abstract: A conductive roller includes: a core member including an outer surface along and about an axial line thereof; and a surface layer arranged along the outer surface of the core member. The surface layer includes a conductive portion formed of a conductive resin composition, and a surface roughness imparting material in a form of particles dispersed in the conductive portion. An average particle size of the surface roughness imparting material is in a range of 6 micrometers or greater and 10 micrometers or less. The number of particles of the surface roughness imparting material per unit area of the surface layer is in a range of 1.0×104 particles per mm2 or greater and 2.0×106 particles per mm2 or less. An average thickness of the surface layer is in a range of 3.0 micrometers or greater and 15.0 micrometers or less.

Abstract: A charging roll includes a core, a rubber substrate arranged around the core, and a surface layer arranged around the rubber substrate. The surface layer includes a conductive matrix containing a base material formed of an insulator, and a conductive material dispersed in the base material, and particles of a surface roughness-imparting material dispersed in the conductive matrix. Each of the particles of the surface roughness-imparting material is formed of an insulator, is porous, and has a specific surface area of 8.7 m2/g or greater and 55 m2/g or less.

Abstract: A developing roll has a metal core, an elastic layer, and a surface layer. A value X is 65.6 N/mm3 or more and a value Y is 229 ?m or more. The value X is P1/(D1×A)?P2/(D2×A). P1 is the load to displace the roll 100 ?m when a metal probe is pressed against the roll. D1 is the displacement of the roll caused by the probe under the load P1. A is the area of the probe. P2 is the load to displace a material roll by 100 ?m when the probe presses against the material roll with the core and the elastic layer and without the surface layer. D2 is the displacement of the material roll caused by the probe under the load P2. The value Y is the displacement of the roll when the probe pierces the surface layer.

Abstract: A conductive roller includes: a core member including an outer surface along and about an axial line thereof; and a surface layer arranged along the outer surface of the core member. The surface layer includes a conductive portion formed of a conductive resin composition, and a surface roughness imparting material in a form of particles dispersed in the conductive portion. An average particle size of the surface roughness imparting material is in a range of 6 micrometers or greater and 10 micrometers or less. The number of particles of the surface roughness imparting material per unit area of the surface layer is in a range of 1.0×104 particles per mm2 or greater and 2.0×106 particles per mm2 or less. An average thickness of the surface layer is in a range of 3.0 micrometers or greater and 15.0 micrometers or less.

Abstract: An electroconductive roll includes a core member, a rubber base material disposed around the core member, and a surface layer disposed around the rubber base material. The arithmetic mean peak curvature Spc of a surface of the surface layer is equal to or greater than 1,880 (1/mm), and is equal to or less than 14,024 (1/mm).

Abstract: A conductive roller includes a base including an outer surface along and about an axial line thereof, and a surface layer arranged on the outer surface of the base. The surface layer includes particles. The ten-point height of irregularities Rz of the outer surface of the base is greater than or equal to 6.0 micrometers and less than or equal to 8.0 micrometers. A ten-point height of irregularities Rz of an outer surface of the surface layer is greater than or equal to 5.5 micrometers and less than or equal to 8.5 micrometers. The base included in the conductive roller preferably includes a core member and a conductive elastic layer arranged between the core member and the surface layer. The surface layer preferably includes a conductive portion including a resin material and a conductive agent.

Abstract: A conductive roller includes: a core member including an outer surface along and about an axial line thereof; and a surface layer arranged along the outer surface of the core member. The surface layer includes a conductive portion, and a surface roughness imparting material in a form of particles dispersed in the conductive portion. An average particle size of the surface roughness imparting material is in a range of 6 micrometers or greater and less than 10 micrometers. The number of particles of the surface roughness imparting material per unit area of the surface layer is in a range of 3.5×105 particles per mm2 or greater and 7.5×105 particles per mm2 or less. An average thickness of the surface layer is in a range of 0.2 micrometers or greater and 5.5 micrometers or less.

Abstract: A developing roll has a metal core, an elastic layer, and a surface layer, A value X is 65.6 N/mm3 or more and a value Y is 229 ?m or more. The value X is P1/(D2×A) P2/(D2× A). P1 is the load to displace the roll by 100 ?m when a metal probe is pressed against the roll. D1 is the displacement of the roll caused by the probe under the load P1. A is the area of the probe. P2 is the load to displace a material roll by 100 ?m when the probe is pressed against the material roll with the core and the elastic layer and without the surface layer. D2 is the displacement of the material roll caused by the probe under the load P2. The value Y is the displacement of the developing roll when the probe pierces the surface layer.

Abstract: A charging roll includes a core member, a rubber base material disposed around the core member, and a surface layer disposed around the rubber base material. The average of heights of contours of convex portions on a surface of the surface layer relative to an average cylindrical surface obtained by averaging surface irregularities of the surface layer is equal to or greater than 0.8 micrometers and is equal to or less than 2.1 micrometers. The average of intervals between apexes of the convex portions on the surface of the surface layer is equal to or greater than 6.6 micrometers and is equal to or less than 11.5 micrometers.

Abstract: An electroconductive roll includes a core member, a rubber base material disposed around the core member, and a surface layer disposed around the rubber base material. The surface area of the surface layer per unit projected area is equal to or greater than 1.255, and is equal to or less than 6.635.

Abstract: A charging roll includes a core member, a rubber base material disposed around the core member, and a surface layer disposed around the rubber base material. The average of heights of contours of convex portions on a surface of the surface layer relative to an average cylindrical surface obtained by averaging surface irregularities of the surface layer is equal to or greater than 2.0 micrometers and is equal to or less than 8.4 micrometers. The average of intervals between apexes of the convex portions on the surface of the surface layer is equal to or greater than 6.7 micrometers and is equal to or less than 39.8 micrometers.

Abstract: A charging roll includes a core member, a rubber base material disposed around the core member, and a surface layer disposed around the rubber base material. The ten point height of irregularities RZ of a surface of the surface layer is equal to or greater than 3.9 micrometers, and is equal to or less than 6.1 micrometers. The mean spacing between peaks Sm of the surface of the surface layer is equal to or greater than 12.5 micrometers and is equal to or less than 13.5 micrometers.

Abstract: A charging roll includes a core member, a rubber base material disposed around the core member, and a surface layer disposed around the rubber base material. The average of heights of contours of convex portions on a surface of the surface layer relative to an average cylindrical surface obtained by averaging surface irregularities of the surface layer is equal to or greater than 0.8 micrometers and is equal to or less than 2.1 micrometers. The average of intervals between apexes of the convex portions on the surface of the surface layer is equal to or greater than 6.6 micrometers and is equal to or less than 11.5 micrometers.

Abstract: A charging roll includes a core member, a rubber base material disposed around the core member, and a surface layer disposed around the rubber base material. The average of heights of contours of convex portions on a surface of the surface layer relative to an average cylindrical surface obtained by averaging surface irregularities of the surface layer is equal to or greater than 2.0 micrometers and is equal to or less than 8.4 micrometers. The average of intervals between apexes of the convex portions on the surface of the surface layer is equal to or greater than 6.7 micrometers and is equal to or less than 39.8 micrometers.

Abstract: A charging roll includes a core member, a rubber base material disposed around the core member, and a surface layer disposed around the rubber base material. The ten point height of irregularities RZ of a surface of the surface layer is equal to or greater than 3.9 micrometers, and is equal to or less than 6.1 micrometers. The mean spacing between peaks Sm of the surface of the surface layer is equal to or greater than 12.5 micrometers and is equal to or less than 13.5 micrometers.

Abstract: A charging roll includes a core member, a rubber base material disposed around the core member, and a surface layer disposed around the rubber base material. The ten point height of irregularities RZ of a surface of the surface layer is equal to or greater than 6.5 micrometers, and is equal to or less than 11.7 micrometers. The mean spacing between peaks Sm of the surface of the surface layer is equal to or greater than 16.5 micrometers and is equal to or less than 18.8 micrometers.

Abstract: An electroconductive roll includes a core member, a rubber base material disposed around the core member, and a surface layer disposed around the rubber base material. The density of peaks Spd of the surface of the surface layer is equal to or greater than 93,406 (1/mm2), and is equal to or less than 153,027 (1/mm2).

Abstract: An electroconductive roll includes a core member, a rubber base material disposed around the core member, and a surface layer disposed around the rubber base material. The surface area of the surface layer per unit projected area is equal to or greater than 1.255, and is equal to or less than 6.635.

Abstract: An electroconductive roll includes a core member, a rubber base material disposed around the core member, and a surface layer disposed around the rubber base material. The density of peaks Spd of the surface of the surface layer is equal to or greater than 93,406 (1/mm2), and is equal to or less than 153,027 (1/mm2).