Patent ID: 7802778

Claim:
A paper folding apparatus comprising: an accordion folding mechanism that folds a sheet fed from an image forming apparatus in an accordion shape by folding a mountain fold and a valley fold in a direction perpendicular to a sheet conveying direction; a size setting unit that sets a folding size of the mountain fold and the valley fold; and a size adjusting unit that compares a size of the sheet fed from the image forming apparatus with the folding size, and adjusts a folding width of a predetermined number of folds at a trailing end of the sheet to be equal to or smaller than the folding size set by the size setting unit, wherein the size adjusting unit calculates number of folds for folding the sheet with the folding size and the folding width of a last fold, which is a residual width, when the folding width of the last fold is smaller than a predetermined minimum folding width, subtracts one from the number of folds to increase the folding width of the last fold to a value larger than the minimum folding width, and sets the folding width of a last-but-one fold to a value obtained by subtracting an increased amount of the folding width of the last fold from the folding size.