Patent ID: 8626053

Claim:
A medium correcting device comprising: a first rotating body that has a circumferential surface moving circumferentially; a second rotating body that has a circumferential surface softer than the circumferential surface of the first rotating body and moving circumferentially as the circumferential surface of the first rotating body moves circumferentially while the circumferential surface of the second rotating body and the circumferential surface of the first rotating body press each other, the second rotating body and the first rotating body holding a recording medium passing in between; a first holding body that holds the first rotating body; a second holding body that holds the second rotating body, is detachably coupled to the first holding body, and becomes, when being coupled to the first holding body, a coupled body into which the first rotating body and the second rotating body are incorporated and which is housed in a housing body; a rotation shaft that is incorporated as a part of the coupled body and driven to rotate by a driving system of the housing body when the coupled body is housed in the housing body and the rotation shaft is connected to the driving system, the rotation shaft being disconnected and away from the driving system when the coupled body is removed from the housing body; an off-center cam that is eccentrically fixed to the rotation shaft and that presses one of the first rotating body and the second rotating body against the other by an amount of pressing according to an angle of the off-center cam, the off-center cam providing a larger amount of pressing when the angle of the off-center cam is one in which an eccentric direction of the off-center cam is downward than when the angle of the off-center cam is one in which the eccentric direction of the off-center cam is upward; and a center-of-gravity correction section that is fixed to the rotation shaft and that has a center of gravity thereof at a position deviated from the rotation shaft in a direction opposite to the eccentric direction of the off-center cam, the center-of-gravity correction section having a mass sufficient to cause the off-center cam to come to a rest position, in which the eccentric direction of the off-center cam points upwardly thereby providing a smaller amount of pressing, when the rotation shaft is disconnected from the driving system.