Image Forming Apparatus

An image forming apparatus comprising:

• a body casing;
• at least two rollers in the body casing;
• an endless belt looped around the at least two rollers, the belt having an outer surface and an inner surface;
• a cleaning unit disposed outside the loop of the belt, the cleaning unit including a case, a cleaning mechanism disposed within the case, and at least one cam, the cleaning mechanism including a cleaning member that is positioned to face the outer surface of the belt;
• a backup member that is positioned to face the inner surface of the belt;
• and
• a pressure force adjusting mechanism coupled to the backup member for adjusting a pressure force between the backup member and the belt, the pressure force adjusting mechanism comprising a cam-follower in contact with the at least one cam;
• wherein the cam-follower adjusts the pressure force adjusting mechanism between a first mode where the backup member presses the belt by a first pressure force and a second mode where the backup member presses the belt by a second pressure force by rotation of the at least one cam;
• and
• wherein the first pressure force is larger than the second pressure force.