To change master-servant relationship between rollers without making a conveying amount of paper (conveying speed) among a plurality of rollers and to more certainly prevent deterioration of recording quality by more finely adjusting the master-servant relationship between the rollers.

The power transmission device 50 transmits power from a rotation body 53 to a first body 54 to be driven and a second body 55 to be driven. When drive torque of the first body 54 to be driven is reduced, a stretching amount of a tension spring 56 is reduced, thereby, an open angle θ of a wire member 57 is reduced, the wire member fastens a cylinder part 55a and transmission torque to the second body 55 to be driven is increased. On the contrary, when drive torque of the first body 54 to be driven is increased, a stretching amount of the tension spring 56 is increased, thereby, the open angle θ of the wire member 57 is increased, fastening of the cylinder part 55a by the wire member 57 is relaxed and transmission torque to the second body 55 to be driven is reduced.

COPYRIGHT: (C)2008,JPO&INPIT