| 摘要 |
PURPOSE:To prevent the generation of a streak on an image and the soiling of the detecting surface of a developer concentration detecting means even if the means is incorporated in a member having a shape so as to be along a developer carrier from a developer supplying position to a layer thickness regulating position. CONSTITUTION:The part of a developer returning member 1 on which the detection window 8 of the developer concn. sensor 7 is disposed is not formed to a surface having curvature but to a plane along the axial direction of a developing sleeve 3. Then, the plane and the detecting surface 8a of the detection window 8 of the developer concn. sensor 7 almost coincide, and the developer concn. sensor 7 is incorporated in the developer returning member 1 to prevent the generation of ruggedness on the plane including the detecting surface 8a of the developer concn. sensor 7 in the developer returning member 1 facing oppositely the developing sleeve 3. |
