Sheet alignment mechanism detecting stack height

A sheet processing device, comprising:

• an exit tray on which ejected sheets or ejected sheet sheaves subjected to stapling are stacked;
• and
• a sheet alignment mechanism configured to align at least the sheets stacked on the exit tray in a manner to move the sheets in a shifting direction orthogonal to an ejection direction in which a sheet is ejected and to a stacking direction in which a sheet is stacked,
• wherein the sheet alignment mechanism includes:
• a pair of alignment members capable of coming in contact with opposite end parts of at least the sheets in the shifting direction;
• and
• a pair of moving mechanisms configured to move the pair of alignment members in the shifting direction,
• when the stapling is performed on one end parts of sheet sheaves in the shifting direction, one of the pair of moving mechanisms moves an alignment member of the pair of alignment members, which is arranged correspondingly to the other end parts of the sheet sheaves in the shifting direction, to a receiving position,
• the receiving position is a position displaced in the shifting direction from a reference position to separate the alignment member from the sheet sheaves,
• the reference position is a position where the alignment member comes in contact with the other end parts of the sheet sheaves,
• the sheet alignment mechanism includes:
• a pair of rotation mechanisms;
• and
• a detection mechanism configured to detect a difference in amount of rotation between one and the other of the pair of alignment members as a height difference between first and second points on a topmost surface of the sheet sheaves,
• the first point is closer to the one end parts of the sheet sheaves than the second point,
• the second point is closer to the other end parts of the sheet sheaves than the first point,
• one of the pair of rotation mechanisms rotates one of the pair of alignment members, which is arranged correspondingly to the one end parts of the sheet sheaves, in the stacking direction about a rotary shaft extending in the shifting direction above the exit tray so that the one of the pair of alignment members comes in contact with the first point,
• the other of the pair of rotation mechanisms rotates the other of the pair of alignment members, which is arranged correspondingly to the other end parts of the sheet sheaves, in the stacking direction about the rotary shaft so that the other of the pair of alignment members comes in contact with the second point, and
• when a detection result of the detection mechanism is a preset value, one of the pair of moving mechanisms moves the alignment member arranged correspondingly to the other end parts of the sheet sheaves to the receiving position.

A sheet processing device, comprising:

• an exit tray on which ejected sheets or ejected sheet sheaves subjected to stapling are stacked;
• and
• a sheet alignment mechanism configured to align at least the sheets stacked on the exit tray in a manner to move the sheets in a shifting direction orthogonal to an ejection direction in which a sheet is ejected and to a stacking direction in which a sheet is stacked,
• wherein the sheet alignment mechanism includes:
• a pair of alignment members capable of coming in contact with opposite end parts of at least the sheets in the shifting direction;
• and
• a pair of moving mechanisms configured to move the pair of alignment members in the shifting direction,
• when the stapling is performed on one end parts of sheet sheaves in the shifting direction, one of the pair of moving mechanisms moves an alignment member of the pair of alignment members, which is arranged correspondingly to the other end parts of the sheet sheaves in the shifting direction, to a receiving position,
• the receiving position is a position displaced in the shifting direction from a reference position to separate the alignment member from the sheet sheaves,
• the reference position is a position where the alignment member comes in contact with the other end parts of the sheet sheaves, and
• a distance between the reference position and the receiving position is in a range from 10 mm to 20 mm.