Charging member and charging device

• US 6,555,210 B1
• Filed: 04/14/1999
• Issued: 04/29/2003
• Est. Priority Date: 04/14/1998
• Status: Expired due to Term

• Current Assignee: Bridgestone Corporation
• Original Assignee: Bridgestone Corporation
• Inventors: Masuda, Yoshitomo, Yakushiji, Gaku, Kawagoe, Takahiro
• Primary Examiner(s): Kelly, Cynthia H.
• Assistant Examiner(s): Nguyen, Kimberly T.
• Application Number:
  US09/291,761
• Time in Patent Office: 1,476 Days
• Field of Search: 428/212, 428/421, 399/302, 399/168, 399/174, 399/176, 399/50, 492/53, 361/225, 430/66
• US Class Current: 428/212
• CPC Class Codes: G03G 15/0233 Structure, details of the charging member, e.g. chemical composition, surface properties
• CPC Class Codes: Y10T 428/24942 including components having same physical characteristic in differing degree
• CPC Class Codes: Y10T 428/3154 Of fluorinated addition polymer from unsaturated monomers

Abstract

A new charging member which is durable enough to exhibit stable performance over a long period of time without deterioration by the sticking of toner particles. It is characterized by its surface having a universal hardness no higher than 10 N/mm² at a depth equivalent to the diameter of toner particles.

Claims

1. A charging member for charging a latent image supporting body in electrophotoprocess;

wherein said charging member has a surface whose universal hardness is no higher than 10 N/mm² at a depth equivalent to the diameter of toner particles.

3. A charging member as defined in claim 1, whose surface recovers from deformation such that the ratio of elastic energy to the sum of elastic energy and plastic energy is no less than 0.4 when it experiences deformation for measurement of universal hardness.

4. A charging member as defined in claim 1, which comprises an elastic layer and one or more outer layers formed thereon, with or without an intermediate layer interposed between them.

5. A charging member as defined in claim 4, which satisfies the condition of H¹/H²<

50, where H¹ is a universal hardness at a depth corresponding to the thickness of the outermost layer and H² is a universal hardness at a depth 10 times as much as said depth corresponding to the thickness of the outermost layer.

6. A charging member as defined in claim 4, which satisfies the condition that the ratio of the storage modulus (E′

) of one layer to the storage modulus (E′

) of its adjacent layer is no larger than 500.

7. A charging member as defined in claim 6, in which the elastic layer has a storage modulus (E′

) no higher than 5×

10⁷ dyn/cm.

8. A charging member as defined in claim 7, in which each layer as a constituent of the outer layer has a storage modulus no higher than 2.5×

10¹⁰ dyn/cm².

9. A charging member as defined in claim 4, in which the elastic layer has a storage modulus no higher than 5×

10⁷ dyn/cm² and a tan δ

smaller than 0.3 as the ratio of loss modulus (E″

) to storage modulus (E′

).

10. A charging member as defined in claim 9, in which the outer layer has a tan δ

of 0.15-0.5 as the ratio of loss modulus (E″

) to storage modulus (E′

).

11. A charging member as defined in claim 4, in which at least the outermost layer of the outer layers is a coating film of water-based resin and has water insolubility no lower than 70% calculated from the equation (1) below),

12. A charging member as defined in claim 1, in which the surface has an Ascar C hardness no higher than 65°

.

13. A charging member as defined in claim 1, in which the surface has a surface roughness Rz no higher than 4 μ

m in terms of 10-point average according to JIS.

14. A charging member as defined in claim 4, in which the elastic layer is of urethane foam having a density of 0.05-0.9 g/cm³.

15. A charging member as defined in claim 4, in which the outer layer contains one or more water-based resins selected from fluoro resin, polyvinyl acetal resin, vinylidene chloride resin, urethane resin, polyester resin, and acrylic resin.

16. A charging member as defined in claim 4, in which the coating layer contains carbon containing no less than 5% oxygen and having a pH no lower than 5.

17. A charging member as defined in claim 16, in which the outermost layer of the outer layers is a coating film of water-based fluoro resin which contains carbon containing no less than 5% oxygen and having a pH no lower than 5.

18. A charging device for charging a latent image supporting body in electrophotoprocess;

wherein said charging device includes the charging member defined in claim 1 or 2.

2. A charging member for charging a latent image supporting body in electrophotoprocess;

wherein said charging member has a surface whose universal hardness is no higher than 10 N/mm² at a depth of 7 μ

m.