Charging apparatus, process cartridge and image forming apparatus

A charging device comprising;

• a charging member configured and positioned to electrically charge a member to be charged which is adapted to form a nip with the member to be charged which has a surface layer having a volume resistivity of not less than 1×1014 Ωcm, said charging member having an elastic member and being movable with a peripheral speed difference relative to the member to be charged;
• and
• electroconductive particles carried on said charging member to the nip;
• and
• wherein the peripheral speed Vd (mm/sec) of the member to be charged, the peripheral speed Vc (mm/sec) of said charging member, the width N (mm) of the nip measured in a moving direction of said charging member, and the coverage ratio Rc of said electroconductive particles carried on said charging member, satisfy:
• N·Rc·|Vc−Vd|/Vd≧2.

A process cartridge detachably mountable to a main assembly of an image forming apparatus, said process cartridge comprising:

• a member to be charged which has a surface layer having a volume resistivity of 1×109-1×1014 Ωcm;
• a charging member configured and positioned to electrically charge said member to be charged which is adapted to form a nip with said member to be charged, said charging member having an elastic member and being movable with a peripheral speed difference relative to said member to be charged;
• and
• electroconductive particles carried on said charging member to the nip;
• and
• wherein the peripheral speed Vd (mm/sec) of said member to be charged, the peripheral speed Vc (mm/sec) of said charging member, the width N (mm) of the nip measured in a moving direction of said charging member, and the coverage ratio Rc of said electroconductive particles carried on said charging member, satisfy:
• N·Rc·|Vc−Vd|/Vd≧1.

An image forming apparatus comprising:

• a member to be charged which has a surface layer having a volume resistivity of 1×109-1×1014 Ωcm;
• a charging member configured and positioned to electrically charge a member to be charged which is adapted to form a nip with the member to be charged, said charging member having an elastic member and being movable with a peripheral speed difference relative to the member to be charged;
• and
• electroconductive particles carried on said charging member to the nip;
• and
• wherein the peripheral speed Vd (mm/sec) of the member to be charged, the peripheral speed Vc (mm/sec) of said charging member, the width N (mm) of the nip measured in a moving direction of said charging member, and the coverage ratio Rc of said electroconductive particles on said charging member, satisfy:
• N·Rc·|Vc−Vd|/Vd≧1.