In a saddle-stitching apparatus, when a sheet is transported to a center-folding unit, a folding blade moves from a retrieved position to a nip position between a pair of folding rollers. A forward end of the folding blade comes into contact with a fold of the sheet, so that the sheet is folded along the fold. When the sheet is attached to the nip position between the folding rollers, the folding rollers start rotating and then, the folding blade inserts the center-folded sheet between the folding rollers. After the center-fold finishing is completed, the rotations of the folding rollers stop in timing at which the folding blade is pulled out of the nip position between the folding rollers. When pulling the folding blade out of the nip position between the folding rollers, the rotations of the folding rollers restart.

A sheet processing apparatus that can suppress a reduction in a quality of a finish of a fold part of a stack of center-folded sheets without losing an ease of center-folding. The sheet processing apparatus comprises a creasing unit for forming a folding stripe on a sheet so as to facilitate folding the sheet, and an acquisition unit for acquiring information related to a thickness of the sheet. One or more sheets to be provided with folding stripes are determined, from among a plurality of sheets to be folded, according to the information related to the thickness of the sheets, and each of the determined one or more sheets are provided with a folding stripe.

A sheet processing apparatus that can suppress a reduction in a quality of a finish of a fold part of a stack of center-folded sheets without losing an ease of center-folding. The sheet processing apparatus comprises a creasing unit for forming a folding stripe on a sheet so as to facilitate folding the sheet, and an acquisition unit for acquiring information related to a thickness of the sheet. One or more sheets to be provided with folding stripes are determined, from among a plurality of sheets to be folded, according to the information related to the thickness of the sheets, and each of the determined one or more sheets are provided with a folding stripe.

A fold-enhancing device includes a pressing member, at least one retaining member, and a moving mechanism. The pressing member presses against a fold line of a recording-medium bundle folded into a booklet shape. The recording-medium bundle is obtained by stacking multiple sheets of recording media. The retaining member retains the recording-medium bundle and is provided at a position located away from the fold line in a direction intersecting the fold line and not in contact with the pressing member. The moving mechanism moves the pressing member and the retaining member in a direction extending along the fold line.

A fold-enhancing device includes a pressing member, at least one retaining member, and a moving mechanism. The pressing member presses against a fold line of a recording-medium bundle folded into a booklet shape. The recording-medium bundle is obtained by stacking multiple sheets of recording media. The retaining member retains the recording-medium bundle and is provided at a position located away from the fold line in a direction intersecting the fold line and not in contact with the pressing member. The moving mechanism moves the pressing member and the retaining member in a direction extending along the fold line.

A sheet folding apparatus having two-folding rollers each of whose outer diameter gradually decreases from the central part to each end part, a folding plate which can move forward to or backward from a nip between the two-folding rollers, and has a cutout part located at an edge part of the folding plate facing the nip between central parts of the two-folding rollers, wherein the cutout part does not reach the nip between the central parts of the two-folding rollers when the sheets are folded, and a folding plate support member which is placed at a position facing the nip between the central parts of the two-folding rollers, and can slide in a direction of moving closer to or away from the nip, wherein the folding plate support member projects from the cutout part when the sheets are set, and does not reach the nip when the sheets are folded.

A sheet folding apparatus having two-folding rollers each of whose outer diameter gradually decreases from the central part to each end part, a folding plate which can move forward to or backward from a nip between the two-folding rollers, and has a cutout part located at an edge part of the folding plate facing the nip between central parts of the two-folding rollers, wherein the cutout part does not reach the nip between the central parts of the two-folding rollers when the sheets are folded, and a folding plate support member which is placed at a position facing the nip between the central parts of the two-folding rollers, and can slide in a direction of moving closer to or away from the nip, wherein the folding plate support member projects from the cutout part when the sheets are set, and does not reach the nip when the sheets are folded.

A sheet processing apparatus includes a sheet holding unit, a sheet conveying unit configured to convey a plurality of sheets one by one onto the sheet holding unit during sheet processing, wherein the plurality of sheets includes a first sheet and a second sheet that is conveyed immediately after the first sheet, an adhesive applying unit configured to apply an adhesive material on the first sheet held on the sheet holding unit before the second sheet is conveyed onto the first sheet, and a pressing unit configured to press the second sheet against the first sheet after the second sheet is conveyed onto the first sheet.

A sheet processing apparatus includes a sheet holding unit, a sheet conveying unit configured to convey a plurality of sheets one by one onto the sheet holding unit during sheet processing, wherein the plurality of sheets includes a first sheet and a second sheet that is conveyed immediately after the first sheet, an adhesive applying unit configured to apply an adhesive material on the first sheet held on the sheet holding unit before the second sheet is conveyed onto the first sheet, and a pressing unit configured to press the second sheet against the first sheet after the second sheet is conveyed onto the first sheet.

A sheet folding apparatus for folding sheets comprising a curved conveyance path along which the sheets are moved successively in first and second opposite directions, the curved conveyance path being such that the sheets cannot naturally register to reach a folding position by simple effect of gravity, wherein to register the sheets before to fold them transport rollers having loaded the sheets in the first direction moves back in the second opposite direction for compressing the sheets against an adjustable low stop member to generate an elastic deformation of the sheets sufficient to compensate friction in the curved conveyance path and automatically register the sheets.