| abstract |
Provided is a developing device that has a long life, does not generate toner spills, and does not generate a rough image, and maintains an initial image quality. When the angle between a contact portion with a developer regulating member, a center of a developing roller, and a center of a supply stripping roller on a cross section of the developing roller at the time of contact development is represented by A, A is a setting of 40 ° ≦ A ≦ 70 °, and B is an angle formed by a straight line connecting the center of the supply stripping roller 5 and the center of the developing roller 3 with respect to a horizontal line passing through the center of the developing roller 3. Then, the supply stripping roller 5 is positioned below the horizontal line, and is set at 40 ° ≦ B ≦ 70 ° toward the upstream in the rotation direction of the developing roller 3, and the angle A and the fluidity index R of the developer are set. Satisfies R ≧ −A / 3 + 73 R ≦ 85, and the developer is arranged so that the weight average particle diameter of the developer is 4 μm to 12 μm. [Selection diagram] Fig. 1 |