Sheet processing apparatus and image forming system

A sheet processing apparatus comprising:

• a sheet supporting portion configured to support a discharged sheet;
• a sheet processing unit configured to perform processing on a sheet bundle composed of a plurality of sheets discharged on the sheet supporting portion;
• a first sheet conveyance path for guiding the sheet to the sheet supporting portion;
• a second sheet conveyance path that branches from the first sheet conveyance path at a branch portion on the first sheet conveyance path and merges with the first sheet conveyance path at a merging portion upstream, in a sheet conveying direction, of a discharge port to the sheet supporting portion;
• a guide unit configured to selectively guide the sheet to the first sheet conveyance path or the second sheet conveyance path in the branch portion;
• and
• a control unit configured to control the guide unit,
• wherein the control unit controls the guide unit so as to
• guide a first sheet conveyed first in the sheet bundle to be processed by the sheet processing unit to the second sheet conveyance path, and guide a second sheet following the first sheet to the first sheet conveyance path to merge the first and second sheets in an overlapping manner at the merging portion, and
• guide at least one of sheets following the second sheet among a plurality of sheets constituting the sheet bundle to the second sheet conveyance path, and
• wherein the sheet processing unit is in a non-processing state of not performing the processing on a sheet bundle on the sheet supporting portion, when a leading edge of the sheet to be guided to the second sheet conveyance path reaches the branch portion among the sheets following the second sheet.

An image forming system comprising:

• an image forming unit configured to form an image on a sheet;
• a sheet supporting portion on which a sheet on which the image is formed by the image forming unit is discharged and supported;
• a sheet processing unit configured to perform processing on a sheet bundle composed of a plurality of sheets discharged on the sheet supporting portion;
• a first sheet conveyance path for guiding the sheet to the sheet supporting portion;
• a second sheet conveyance path that branches from the first sheet conveyance path at a branch portion on the first sheet conveyance path and merges with the first sheet conveyance path at a merging portion upstream, in a sheet conveying direction, of a discharge port to the sheet supporting portion;
• a guide unit configured to selectively guide the sheet to the first sheet conveyance path or the second sheet conveyance path in the branch portion;
• and
• a control unit configured to control the guide unit,
• wherein a path length of the second sheet conveyance path between the branch portion and the merging portion is longer than a path length of the first sheet conveyance path between the branch portion and the merging portion, and
• wherein the control unit controls the guide unit so as to
• guide a first sheet conveyed first in the sheet bundle to be processed by the sheet processing unit to the second sheet conveyance path, and guide a second sheet following the first sheet to the first sheet conveyance path to merge the first and second sheets in an overlapping manner at the merging portion, and
• guide at least one of sheets following the second sheet among a plurality of sheets constituting the sheet bundle to the second sheet conveyance path.