| 摘要 |
PROBLEM TO BE SOLVED: To provide a characteristic for preventing filming with toner and to improve durability by specifying each capacitance of the whole of a developing roller and an elastic layer. SOLUTION: The elastic layer 3 is concentrically provided on the periphery of a shaft made of metal such as SUS and an aluminum alloy and the outer periphery of the elastic layer 3 is covered with a surface layer 4. In such a case, there is a case where a resistance adjusting layer for adjusting the electric resistance of the developing roller 1, a primer layer for improving the stickability between the elastic layer 3 and the surface layer 4, etc., are included therebetween. Then, the developing roller 1 is constituted so that the capacitance C1 of the surface layer 4 after the covering has a value of <=2.5 nF and the capacitance C2 of the elastic layer 3 has a value of 0.8<=20 nF. Therefore, the filming with the toner on the surface of the developing roller is prevented. Thus, on the surface of the developing roller, a uniform thin toner layer only of the toner contributing to development can be formed. |
