| 摘要 |
PURPOSE:To inexpensively obtain bright image quality without necessitating severe gap precision by providing a conductive elastic layer and a heat- shrinkable resin layer around a cylindrical shaft. CONSTITUTION:A developing roller 2 is constituted of the cylindrical shaft 3 formed from a metal such as steel or a stainless steel, the conductive elastic layer 4 provided around the shaft 3 and the conductive heat-shrinkable resin layer 9 provided around the elastic layer. The elastic layer is formed so that a ferromagnetic powder such as ferrite powder and an electroconductive agent such as carbon black are filled in a rubber material such as urethane. Sufficient bias voltage can not be impressed on the surface of the roller sometimes 2 because the elastic layer has certain insulating property even if the elastic layer is made conductive. Then, the conductive resin layer 9 is provided on the surface of the elastic layer 4. Thereby, the bias voltage impressed through the shaft 3 is sufficiently impressed on the surface of the roller 2 through the elastic layer 4. |
