Patent ID: 8165499

Claim:
An image forming apparatus comprising: an apparatus main assembly; a unit detachably mountable to said apparatus main assembly; a first coupling, provided on said apparatus main assembly, for being rotated by power from a driving source; and a second coupling, provided on said unit, for being rotated by engaging with said first coupling, wherein either one of said first coupling and said second coupling has a recessed shape and the other coupling has a projected shape, at least one of an outer peripheral portion of the projected-shape coupling and an inner peripheral surface of the recessed-shape coupling having an inclined surface, wherein at least one of said first coupling and said second coupling is retractable toward a direction parallel to a rotation shaft thereof, and wherein said image forming apparatus has a structure such that a rotation shaft of said second coupling is more movable than a rotation shaft of said first coupling in a disengaging direction of said unit by a force exerted in the disengaging direction of said unit when said unit is pulled out from said apparatus main assembly in a direction perpendicular to the rotation shaft of said first coupling and then by movement of the rotation shaft, at least one of said first coupling and said second coupling is retracted along the inclined surface in the direction parallel to the rotation shaft.