Patent ID: 8357078

Claim:
A sheet folding apparatus comprising: a conveying roller pair configured to convey a sheet; a conveying path provided on a downstream side of the conveying roller pair, an opening being formed in a part of the conveying path if the sheet is triple-folded and being closed if the sheet is double-folded; a retracting conveying path, an inlet of which is opened to the opening of the conveying path and an outlet of which is closed by a stopper, the retracting conveying path leading a front end of the sheet, which is conveyed through the conveying path, from the inlet to the stopper and temporarily retracting a front of the sheet if the sheet is triple-folded; a first folding roller pair disposed near the inlet of the retracting conveying path, the first folding roller pair nipping, if the sheet is triple-folded, a bend caused by pushing of the sheet led by the conveying rollers into the retracting conveying path to form a first fold and nipping, if the sheet is double-folded, the front end of the sheet, which is conveyed through the closed conveying path, and conveying the sheet further downstream; and a second folding roller pair configured to further form a second fold in the sheet on which the first fold is formed to triple-fold the sheet, and form only the second fold in the sheet on which the first fold is not formed to double-fold the sheet.