Patent ID: 8095053

Claim:
A transfer belt unit comprising: a transfer belt that is rotated to travel while carrying an image; a driving roller configured to rotate the transfer belt; a first detection roller that rotates when it is in contact with a first end in a width direction of the transfer belt; a second detection roller that rotates when it is in contact with a second end opposed to the first end of the transfer belt; a first transmitting portion that includes a lead screw which is rotated according to a rotation of the first detection roller or the second detection roller, and a rack pinion mechanism which is connected to the lead screw and rotated in a direction perpendicular to the rotation of the first detection roller or the second detection roller, and is configured to transmit the rotation of the first detection roller or the second detection roller; a steering roller that is connected to the rack pinion mechanism and tilted in a traveling direction of the transfer belt, and is configured to change a direction of the rotation and traveling of the transfer belt according to a rotation of the first detection roller or the second detection roller; and a steering supporting member configured to support the steering roller and being tilted in a traveling direction of the transfer belt together with the steering roller.