Patent ID: 8657276

Claim:
A sheet processing apparatus comprising: a conveying unit configured to convey a sheet; a first detection unit and a second detection unit arranged in a sheet width direction orthogonal to a sheet conveying direction and configured to detect an edge of the conveyed sheet in the sheet width direction, respectively; a first shift unit configured to cause said first detection unit and said second detection unit to shift in the sheet width direction; a second shift unit configured to cause the sheet to shift in the sheet width direction; a first determination unit configured to determine, by causing said first shift unit to cause said first detection unit and said second detection unit to shift, during conveyance of the sheet by said conveying unit, a first position of the edge of the sheet in the sheet width direction, the first position being detected by said first detection unit, and then a second position of the edge of the sheet in the sheet width direction, the second position being detected by said second detection unit; a second determination unit configured to determine a third position of the edge of the sheet in the sheet width direction, the third position being closer to a trailing edge of the sheet than the second position is, based on the first position and the second position determined by said first determination unit, and an amount of conveyance of the sheet till the second position is detected after the first position is detected; and a correction unit configured to correct a displacement of the sheet in the sheet width direction, by causing said second shift unit to shift the sheet in the sheet width direction, according to the third position determined by said second determination unit.