DEVELOPING ROLLER, DEVELOPING ASSEMBLY, PROCESS CARTRIDGE AND ELECTROPHOTOGRAPHIC IMAGE FORMING APPARATUS
First Claim
1. A developing roller comprising a mandrel, an elastic-material layer and a cover layer as a surface layer which covers the elastic-material layer, whereinthe developing roller has an Asker-C hardness of 40°
- or more and 85°
or less at the surface of the cover layer;
the cover layer has a thickness of 15 nm or more and 5,000 nm or less; and
Martens hardness H1 (N/mm2) at the surface of the developing roller, Martens hardness H2 (N/mm2) of the elastic-material layer and the thickness d (mm) of the cover layer satisfy a relationship of the following expression (1);
400≦
(H1−
H2)/d≦
2,000
(1).
1 Assignment
0 Petitions
Accused Products
Abstract
A developing roller is provided which is soft enough to enable toners to be kept from deteriorating with time and cannot easily cause permanent set. The developing roller includes a mandrel, an elastic-material layer and a cover layer as a surface layer which covers the elastic-material layer. Asker-C hardness at the surface of the cover layer is from 40° to 85°. The cover layer has a thickness of from 15 nm to 5,000 nm. Martens hardness H1 (N/mm2) at the surface of the developing roller, Martens hardness H2 (N/mm2) of the elastic-material layer and the thickness d (mm) of the cover layer satisfy the relationship of the following expression (1):
400≦(H1−H2)/d≦2,000 (1).
14 Citations
8 Claims
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1. A developing roller comprising a mandrel, an elastic-material layer and a cover layer as a surface layer which covers the elastic-material layer, wherein
the developing roller has an Asker-C hardness of 40° - or more and 85°
or less at the surface of the cover layer;the cover layer has a thickness of 15 nm or more and 5,000 nm or less; and Martens hardness H1 (N/mm2) at the surface of the developing roller, Martens hardness H2 (N/mm2) of the elastic-material layer and the thickness d (mm) of the cover layer satisfy a relationship of the following expression (1);
400≦
(H1−
H2)/d≦
2,000
(1). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
- or more and 85°
Specification