Patent ID: 8152156

Claim:
A rotation-body controlling apparatus comprising: a first motor configured to rotate a first rotation body; a second motor configured to rotate a second rotation body; a first rotation amount detecting portion configured to detect a rotation amount of the first rotation body rotated in synchronization with the first motor; a second rotation amount detecting portion configured to detect a rotation amount of a rotation shaft rotated in synchronization with the second rotation body; a transmitting mechanism configured such that a rotation of the first rotation body is transmittable to the rotation shaft; a changing portion configured to selectively change a state of the transmitting mechanism between (a) a transmitting state in which the rotation of the first rotation body is transmitted to the rotation shaft and (b) a non-transmitting state in which the rotation of the first rotation body is not transmitted to the rotation shaft; a target-rotation-amount obtaining portion configured to obtain a target rotation amount of the first rotation body; an origin-position detecting portion configured to detect an origin position of a rotation phase of the first rotation body on the basis of a phase of the first rotation body at a time when the second rotation amount detecting portion has detected a rotation of the rotation shaft, where the state of the transmitting mechanism is changed to the transmitting state by the changing portion; a current-rotation-phase determining portion configured to determine a current rotation phase of the first rotation body on the basis of the origin position detected by the origin-position detecting portion; and a target-rotation-amount correcting portion configured to correct the target rotation amount determined on the basis of the current rotation phase determined by the current-rotation-phase determining portion.