Patent ID: 6983931

Claim:
A method of binding sheets, comprising: receiving a sheet from outside and conveying the sheet; receiving information on a size of the sheet; receiving and guiding the conveyed sheet; folding the conveyed sheet in two at a center portion thereof in a direction the sheet is conveyed so as to be a folded sheet and conveying the folded sheet with the folded portion of the folded sheet being a leading edge of the folded sheet with a sheet folding device, wherein a position where the conveyed sheet is stopped is set according to the size of the sheet so that the sheet is folded by the sheet folding device at the center portion of the sheet, and wherein the sheet to be conveyed is stopped at the position, so that the center portion of the sheet is downwardly slackened, the slackened center portion of the sheet is pinched into the sheet folding device, and thereby the sheet is folded in two at the center portion of the sheet by the sheet folding device, and wherein a leading edge of the sheet is detected, and the slackened center portion of the sheet is pushed toward the sheet folding device with a pushing device at a predetermined timing after the detection of the leading edge of the sheet, so that the slackened center portion of the sheet is pinched into the sheet folding device; receiving and jogging the conveyed folded sheet one after another so as to be stacked into a stack of folded sheets with a receiving/jogging device; binding the stack of stacked folded sheets at an edge portion of the stack of folded sheets at the side where the folded portion of each folded sheet of the stack of folded sheets is located with a binding device; and discharging the bound stack of folded sheets.