Intermediate transfer unit and image forming apparatus therewith

An intermediate transfer unit comprising:

• an endless intermediate transfer belt that moves along a plurality of image forming portions;
• a driving roller that rotates the intermediate transfer belt;
• a tension roller that rotates by following the intermediate transfer belt while giving a predetermined tension to the intermediate transfer belt;
• and
• a roller supporting frame including a first supporting frame which supports on one end thereof one of the tension roller and the driving roller and a second supporting frame which supports on one end thereof another of the tension roller and the driving roller, the roller supporting frame having a coupling portion formed thereon which rotatably couples together an end part of the first supporting frame on which the one roller is not supported and an end part of the second supporting frame on which the other roller is not supported,
• wherein
• the coupling portion has a rotary shaft formed on the first supporting frame and a shaft hole formed in the second supporting frame to permit the rotary shaft to be inserted therein,
• the roller supporting frame is inserted inside the intermediate transfer belt in a first state where the first and second supporting frames are folded so as to form an acute angle, the roller supporting frame making the first supporting frame rotate with respect to the second supporting frame about the rotary shaft in a forward direction such that the roller supporting frame in the first state is brought into a second state where the first and second supporting frames extend linearly, the roller supporting frame having the intermediate transfer belt wound around the driving roller and the tension roller,
• the rotary shaft has a projection that projects from an outer circumferential face thereof in a radial direction,
• the shaft hole has a restricting wall portion which is formed outward of the rotary shaft in the radial direction, downstream of the projection in the forward direction, and
• as the first supporting frame in the second state rotates in the forward direction, the projection makes contact with the restricting wall portion to restrict rotation of the first supporting frame in the forward direction.