Sheet conveying apparatus

An image forming system comprising:

• a conveying unit for conveying sheets in a predetermined conveying direction;
• a conveying belt configured to convey the sheet passed from the conveying unit and extending in the predetermined conveying direction;
• a plurality of balls that are arranged in the predetermined conveying direction so as to contact the sheet conveyed by the conveying belt and configured to be rotatable in any direction while contacting the sheet conveyed by the conveying belt, the plurality of balls being disposed on the conveying belt via the sheet;
• a pair of guides that are disposed at both sides relative to the conveying belt in a width direction crossing the predetermined conveying direction, the pair of guides each having a support surface that supports an end portion of the sheet conveyed by the conveying belt in the width direction and a guide surface that faces an end edge of the conveying belt in the width direction;
• a guide moving unit configured to move the pair of guides to a guide position that guides the end portion of the sheet supported by the support surface while being conveyed by the conveying belt and to a retracting position that is retracted further away from the end edge of the in the width direction than the guide position;
• an image forming part that forms an image on a sheet conveyed by the conveying belt;
• and
• a control unit that controls the conveying unit, the conveying belt and the guide moving unit, wherein
• the control unit is configured to control such that:
• for a sheet having a first sheet length in the predetermined conveying direction, the guide moving unit locates the pair of guides at the retracting position when the sheet is passed from the conveying unit to the conveying belt, and then makes the pair of guides reach the guide position from the retracting position in a state while the sheet is being conveyed by the conveying belt, and in a state where a front end of the sheet is located between upstream and downstream ends of the guide surface in the predetermined conveying direction, and
• for a sheet having a second sheet length longer than the first sheet length, the guide moving unit locates the pair of guides at the retracting position when the sheet is passed from the conveying unit to the conveying belt, and then makes the pair of guides reach the guide position from the retracting position in a state while the sheet is being conveyed by the conveying belt and in a state where the front end of the sheet is located further downstream from the downstream end of the guide surface in the predetermined conveying direction.