Power transmitting device for developing device and image forming apparatus with the same

摘要

A power transmitting device for a developing device of an image forming apparatus and an image forming apparatus with the same are disclosed. The power transmitting device includes a driving section with at least one rotational member which is rotated by a power supplied from an external source. The rotational member is movable between a coupled position where it couples with a developing roller and an uncoupled position where it is not coupled with a developing roller. A rotational shaft includes at least one cam which makes the rotational member move between the coupled position and an uncoupled position. A shaft driving section rotates the rotational shaft in one direction. The cam is provided with a cam surface with a first section. The first section is formed such that a line normal to the cam surface at the point that the cam causes the rotational member to begin to couple with the cam surface does not intersect a line connecting a rotational axis of the cam and a maximum stroke point MP of the cam except at the rotational axis of the cam.