Charging member with electro-conductive elastic layer having exposed bowl-shaped resin particles, process cartridge and electrophotographic apparatus

• US 10,025,216 B2
• Filed: 03/30/2016
• Issued: 07/17/2018
• Est. Priority Date: 04/03/2015
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Uematsu, Atsushi, Taniguchi, Tomohito, Watanabe, Masahiro, Miyagawa, Noboru, Sato, Taichi, Aoyama, Takehiko
• Primary Examiner(s): Royer, William J
• Application Number:
  US15/546,826
• Publication Number:
  US 20180024460A1
• Time in Patent Office: 839 Days
• Field of Search: 399176
• CPC Class Codes: G03G 15/0233 Structure, details of the charging member, e.g. chemical composition, surface properties

Abstract

Provided is a charging member capable of suppressing the occurrence of an image defect due to the non-uniform abrasion of a photosensitive member and a stain, in a long-term use.

The charging member includes an electro-conductive elastic layer as a surface layer.

The electro-conductive elastic layer contains a binder and a bowl-shaped resin particle having an opening. The surface of the charging member has a concavity and a protrusion derived from the bowl-shaped resin particle. The relations represented by the following formulae are satisfied,

$0.2\le S=\frac{S5-S1}{S1}\le 0.5$$0.15\le d=\frac{d5-d1}{d1}\le 0.5$
wherein, when the charging member is pressed onto a glass plate with 100 (g) load, S1 is the average value of contact areas, d1 is the average value of heights of spaces formed in a contact region; and when the load is changed to 500 (g), S5 is the average value of contact areas, d5 is the average value of heights of spaces.

Claims

1. A charging member comprising:

an electro-conductive substrate; and

an electro-conductive elastic layer as a surface layer on the substrate,

wherein

the electro-conductive elastic layer

comprises a binder, and

retains a bowl-shaped resin particle having an opening, so that the opening of the bowl-shaped resin particle is exposed at a surface of the charging member;

the surface of the charging member comprises;

a concavity derived from the opening of the bowl-shaped resin particle exposed at the surface, and

a protrusion derived from an edge of the opening of the bowl-shaped resin particle exposed at the surface;

a part of the surface of the charging member is constituted by the electro-conductive elastic layer; and

relations represented by the following formulae (1) and (2) are satisfied,

2. The charging member according to claim 1, wherein,

when

Martens hardness of the binder on the surface of the charging member is defined as M1, and

Martens hardness of the binder immediately beneath a bottom of the concavity derived from the opening of the bowl-shaped resin particle on the surface of the charging member is defined as M2,

a value of M2/M1 is less than 1.

3. A process cartridge comprising a charging member and an electrophotographic photosensitive member and being configured to be attachable to and detachable from a main body of an electrophotographic apparatus,

wherein

the charging member comprises:

an electro-conductive substrate; and

an electro-conductive elastic layer as a surface layer on the substrate,

wherein

the electro-conductive elastic layer

comprises a binder, and

retains a bowl-shaped resin particle having an opening, so that the opening of the bowl-shaped resin particle is exposed at a surface of the charging member;

the surface of the charging member comprises;

a concavity derived from the opening of the bowl-shaped resin particle exposed at the surface, and

a protrusion derived from an edge of the opening of the bowl-shaped resin particle exposed at the surface;

a part of the surface of the charging member is constituted by the electro-conductive elastic layer; and

relations represented by the following formulae (1) and (2) are satisfied,

4. The process cartridge according to claim 3, wherein,

when

Martens hardness of the binder on the surface of the charging member is defined as M1, and

Martens hardness of the binder immediately beneath a bottom of the concavity derived from the opening of the bowl-shaped resin particle on the surface of the charging member is defined as M2,

a value of M2/M1 is less than 1.

5. An electrophotographic apparatus comprising a charging member and an electrophotographic photosensitive member,

wherein

the charging member comprises:

an electro-conductive substrate; and

an electro-conductive elastic layer as a surface layer on the substrate,

wherein

the electro-conductive elastic layer

comprises a binder, and

retains a bowl-shaped resin particle having an opening, so that the opening of the bowl-shaped resin particle is exposed at a surface of the charging member;

the surface of the charging member comprises;

a concavity derived from the opening of the bowl-shaped resin particle exposed at the surface, and

a protrusion derived from an edge of the opening of the bowl-shaped resin particle exposed at the surface;

a part of the surface of the charging member is constituted by the electro-conductive elastic layer; and

relations represented by the following formulae (1) and (2) are satisfied,

6. The electrophotographic apparatus according to claim 5, wherein,

when

Martens hardness of the binder on the surface of the charging member is defined as M1, and

Martens hardness of the binder immediately beneath a bottom of the concavity derived from the opening of the bowl-shaped resin particle on the surface of the charging member is defined as M2,

a value of M2/M1 is less than 1.