Electrophotographic roller, process cartridge and electrophotographic apparatus
First Claim
1. An electrophotographic roller, comprising an electro-conductive substrate and an electro-conductive elastic layer as a surface layer on the electro-conductive substrate,wherein the elastic layer comprises a binder and retains a bowl-shaped resin particle having an opening in the state where the opening is exposed on a surface of the electrophotographic roller,the surface of the electrophotographic roller comprisesa concave portion derived from the opening of the bowl-shaped resin particle exposed on the surface anda convex portion derived from an edge of the opening of the bowl-shaped resin particle exposed on the surface,a part of the surface of the electrophotographic roller is constituted by the elastic layer,when the electrophotographic roller is pressed on a glass plate so that a load per unit area of a nip formed by the electrophotographic roller and the glass plate is 6.5 g/mm2 or more and 14.3 g/mm2 or less, and a square region having a side whose length is equal to a length of the nip in a direction along a circumferential direction of the electrophotographic roller is put in the nip,in the square region,the convex portion and the glass plate are in contact with each other, and a number of the contact portion is 8 or more, an average value Save of areas of the contact portion is 10 μ
- m2 or more and 111 μ
m2 or less,a variation coefficient S of the areas of the contact portion satisfies the following Expression (1), anda variation coefficient D of areas of Voronoi regions each including the contact portion satisfies the following Expression (2);
0.68≤
S≤
1.00
Expression (1)
0.85≤
D≤
1.20.
Expression (2)
1 Assignment
0 Petitions
Accused Products
Abstract
The electrophotographic roller has a surface layer comprising an electro-conductive elastic layer on an electro-conductive substrate. The opening of a bowl-shaped resin particle is exposed on the surface of the electrophotographic roller. The number of contact portions of the convex portion with the glass plate in a square region where a length of a nip in a direction along the circumferential direction of the electrophotographic roller of a nip formed by pressing the roller on the glass plate with a specific load applied as the length of one side and is located at any position in the nip is 8 or more. The average value of the areas of the contact portions is 10 μm2 to 111 μm2. The variation coefficient of the areas of the contact portions and the variation coefficient D of the areas of a plurality of Voronoi regions each including a contact portion satisfy specific relationships.
26 Citations
15 Claims
-
1. An electrophotographic roller, comprising an electro-conductive substrate and an electro-conductive elastic layer as a surface layer on the electro-conductive substrate,
wherein the elastic layer comprises a binder and retains a bowl-shaped resin particle having an opening in the state where the opening is exposed on a surface of the electrophotographic roller, the surface of the electrophotographic roller comprises a concave portion derived from the opening of the bowl-shaped resin particle exposed on the surface and a convex portion derived from an edge of the opening of the bowl-shaped resin particle exposed on the surface, a part of the surface of the electrophotographic roller is constituted by the elastic layer, when the electrophotographic roller is pressed on a glass plate so that a load per unit area of a nip formed by the electrophotographic roller and the glass plate is 6.5 g/mm2 or more and 14.3 g/mm2 or less, and a square region having a side whose length is equal to a length of the nip in a direction along a circumferential direction of the electrophotographic roller is put in the nip, in the square region, the convex portion and the glass plate are in contact with each other, and a number of the contact portion is 8 or more, an average value Save of areas of the contact portion is 10 μ - m2 or more and 111 μ
m2 or less,a variation coefficient S of the areas of the contact portion satisfies the following Expression (1), and a variation coefficient D of areas of Voronoi regions each including the contact portion satisfies the following Expression (2);
0.68≤
S≤
1.00
Expression (1)
0.85≤
D≤
1.20.
Expression (2) - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
- m2 or more and 111 μ
-
13. A process cartridge attachable to and detachable from a main body of an electrophotographic apparatus, comprising an electrophotographic photosensitive member and an electrophotographic roller,
wherein the electrophotographic roller comprises an electro-conductive substrate and an electro-conductive elastic layer as a surface layer on the electro-conductive substrate, the elastic layer comprises a binder and retains support a bowl-shaped resin particle having an opening in the state where the opening is exposed on a surface of the electrophotographic roller, the surface of the electrophotographic roller comprises a concave portion derived from the opening of the bowl-shaped resin particle exposed on the surface and a convex portion derived from an edge of the opening of the bowl-shaped resin particle exposed on the surface, a part of the surface of the electrophotographic roller is constituted by the elastic layer, when the electrophotographic roller is pressed on a glass plate so that a load per unit area of a nip formed by the electrophotographic roller and the glass plate is 6.5 g/mm2 or more and 14.3 g/mm2 or less, and a square region having a side whose length is equal to a length of the nip in a direction along a circumferential direction of the electrophotographic roller is put in the nip, in the square region, the convex portion and the glass plate are in contact with each other, and a number of the contact portion is 8 or more, an average value Save of areas of the contact portion is 10 μ - m2 or more and 111 μ
m2 or less,a variation coefficient S of the areas of the contact portion satisfies the following Expression (1), and a variation coefficient D of areas of Voronoi regions each including the contact portion satisfies the following Expression (2);
0.68≤
S≤
1.00;
Expression (1)
0.85≤
D≤
1.20.
Expression (2) - View Dependent Claims (14)
- m2 or more and 111 μ
-
15. An electrophotographic apparatus, comprising an electrophotographic roller and an electrophotographic photosensitive member,
wherein the electrophotographic roller comprises an electro-conductive substrate and an electro-conductive elastic layer as a surface layer on the electro-conductive substrate, the elastic layer comprises a binder and retains a bowl-shaped resin particle having an opening in the state where the opening is exposed on a surface of the electrophotographic roller, the surface of the electrophotographic roller comprises a concave portion derived from the opening of the bowl-shaped resin particle exposed on the surface and a convex portion derived from an edge of the opening of the bowl-shaped resin particle exposed on the surface, a part of the surface of the electrophotographic roller is constituted by the elastic layer, when the electrophotographic roller is pressed on a glass plate so that a load per unit area of a nip formed by the electrophotographic roller and the glass plate is 6.5 g/mm2 or more and 14.3 g/mm2 or less, and a square region having a side whose length is equal to a length of the nip in a direction along a circumferential direction of the electrophotographic roller of the nip is put in the nip, in the square region, the convex portion and the glass plate are in contact with each other, and a number of the contact portion is 8 or more, an average value Save of areas of the contact portion is 10 μ - m2 or more and 111 μ
m2 or less,a variation coefficient S of the areas of the contact portion satisfies the following Expression (1), and a variation coefficient D of areas of Voronoi regions each including the contact portion satisfies the following Expression (2);
0.68≤
S≤
1.00;
Expression (1)
0.85≤
D≤
1.20.
Expression (2)
- m2 or more and 111 μ
Specification