Charging member, process cartridge using the same and electrophotographic apparatus

• US 5,713,067 A
• Filed: 12/19/1995
• Issued: 01/27/1998
• Est. Priority Date: 12/22/1994
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Funabashi, Eiji, Mizoe, Kiyoshi, Ishihara, Yuzi, Ashibe, Tsunenori
• Primary Examiner(s): BEATTY, ROBERT B
• Application Number:
  US08/575,701
• Time in Patent Office: 770 Days
• Field of Search: 355/219, 355/274, 355/275, 492/18, 492/53, 492/56, 361/225, 399/176
• US Class Current: 399/176
• CPC Class Codes: G03G 15/0233 Structure, details of the charging member, e.g. chemical composition, surface properties

Abstract

A charging member for charging a charge-receiving member, such as an electrophotographic photosensitive member, by disposing the charging member in contact with the charge-receiving member and applying a voltage to the charging member is constituted by disposing an electroconductive support, an elastic layer, and a surface coating layer having a tensile modulus of above 2000 kgf/cm² to at most 30000 kgf/cm² in this order. The coating layer may preferably contain an acrylic polymer-modified urethane resin. The charging member is effective in providing the charge-receiving member with a nip portion showing a uniform electric resistance distribution for a long period to provide excellent images.

Claims

1. A charging roller, which is disposed in contact with a charge-receiving member and is supplied with a voltage to charge the charge-receiving member, said charging roller comprising:

a electroconductive support;

an elastic layer disposed on said electroconductive support; and

a coating layer disposed on said elastic layer,

said coating layer being a surface layer and having a tensile modulus of above 2000 kgf/cm² to at most 30000 kgf/cm².

2. A charging roller according to claim 1, wherein said coating layer comprises a polymeric substance and an electroconductive filler.

3. A charging roller according to claim 2, wherein said polymeric substance comprises an acrylic polymer-modified urethane resin.

4. A charging roller according to claim 1 or 2, wherein said elastic layer has a hardness of 20-60 degrees.

5. A charging roller according to claim 4, wherein said elastic layer has a hardness of 30-45 degrees.

6. A charging roller according to claim 1 or 2, wherein said elastic layer comprises a foamed material.

7. A charging roller according to claim 1 or 2, wherein the charge-receiving member comprises an electrophotographic photosensitive member.

8. A process cartridge detachably mountable to an electrophotographic apparatus main body, said cartridge comprising:

an electrophotographic photosensitive member;

a charging roller disposed in contact with said photosensitive member and supplied with a voltage to charge said photosensitive member; and

at least one of developing means and cleaning means for acting on said photosensitive member,

said charging roller including an electroconductive support, an elastic layer disposed on said electroconductive support, and a coating layer disposed on said elastic layer,

said coating layer being a surface layer and having a tensile modulus of above 2000 kgf/cm² to at most 30000 kgf/cm², and

said photosensitive member, said charging roller and said at least one of developing means and cleaning means being integrally supported to form said cartridge.

9. A cartridge according to claim 8, wherein said coating layer comprises a polymeric substance and an electroconductive filler.

10. A cartridge according to claim 9, wherein said polymeric substance comprises an acrylic polymer-modified urethane resin.

11. A cartridge according to claim 8 or 9, wherein said elastic layer has a hardness of 20-60 degrees.

12. A cartridge according to claim 11, wherein said elastic layer has a hardness of 30-45 degrees.

13. A cartridge according to claim 8 or 9, wherein said elastic layer comprises a foamed material.

14. An electrophotographic apparatus, comprising:

an electrophotographic photosensitive member;

a charging roller disposed in contact with said photosensitive member and supplied with a voltage to charge said photosensitive member;

exposure means for exposing said photosensitive member;

developing means for developing a latent image formed on said photosensitive member; and

transfer means for transferring a developed image to a recording material,

said charging roller including an electroconductive support, an elastic layer disposed on said electroconductive support, and a coating layer disposed on said elastic layer, and

said coating layer being a surface layer and having a tensile modulus of above 2000 kgf/cm² to at most 30000 kgf/cm².

15. An apparatus according to claim 14, wherein said coating layer comprises a polymeric substance and an electroconductive filler.

16. An apparatus according to claim 15, wherein said polymeric substance comprises an acrylic polymer-modified urethane resin.

17. An apparatus according to claim 14 or 15, wherein said elastic layer has a hardness of 20-60 degrees.

18. An apparatus according to claim 17, wherein said elastic layer has a hardness of 30-45 degrees.

19. An apparatus according to claim 14 or 15, wherein said elastic layer comprises a foamed material.