| 摘要 |
PROBLEM TO BE SOLVED: To avoid image quality deterioration due to fallen toner from a suction duct while avoiding suction of scattered toner at a conveyance pole by the suction duct.SOLUTION: An image forming apparatus includes: a developing roller 43b that rotates in a reverse direction of a photosensitive drum 22 at a part facing the photosensitive drum 22; and a suction duct 50 that is opened and provided upward the developing roller 43b and sucks toner T unused by the developing. When X (m) is a distance from a center Z4-1 of a conveyance pole Z4 to a position that is located at a rotation-direction downstream side of a sleeve 43bb and where a straight line L formed by connecting the rotation center of the developing roller 43b to the tip of the suction duct 50 crosses with the sleeve 43bb, R (m) is the spike length of the toner T on the conveyance pole Z4, W (m/s) is a peripheral speed of the developing roller 43b, and k is a coefficient, the apparatus satisfies the following relationship: 0≤X≤R+kRW (where k=10-12). |
