A sheet processing apparatus includes circuitry configured to acquire a size of a two-ply sheet, in which two sheets are bonded together at one end, and a size of an insertion sheet; and control a sheet processing operation based on the size of the two-ply sheet and the size of the insertion sheet. The sheet processing operation includes inserting the insertion sheet in the two-ply sheet.

An image forming system is configured to execute a printing process to a sheet based on a job for generating output products, and to print index information required for sorting the output products for the respective jobs on a partition sheet. A folding process unit is allowed to designate a folding position of the partition sheet so that at least a part of the index information printed on the respective partition sheets is visible from a predetermined direction.

An image forming apparatus includes an image forming unit, a heating rotary member, and a pressure rotary member that forms a nip portion with the heating rotary member to perform printing on a first recording material with a first width, a second recording material with a second width and has no image to be formed thereon, and a third recording material with the second width and has an image to be formed thereon. A time period from when the first recording material reaches the nip portion to when the second recording material that has no image to be formed thereon and follows the first recording material reaches the nip portion is shorter than a time period from when the first recording material reaches the nip portion to when the third recording material having an image to be formed thereon that follows the first recording material reaches the nip portion.

Provided is an image formation system including an image formation device and a post-processing device configured to convey a paper sheet on which an image has been formed at the image formation device or carry out post-processing thereon, including: a paper ejection tray on which the discharged paper sheet is placed; a jam detector configured to detect a jam of the paper sheet conveyed in a paper conveyance passage; a partition paper sheet inserter configured to insert a partition paper sheet on the paper ejection tray; and a control unit, wherein the control unit controls the partition paper sheet inserter such that, after the jam is detected and paper sheets to be removed, at least including a responsible paper sheet, are removed, the partition paper sheet is inserted on the paper ejection tray before the paper sheet remaining in the paper conveyance passage is discharged to the paper ejection tray.

An image forming apparatus 100 allowing insertion of an insert-sheet between discharged sheets of recording paper includes: an image forming unit 122 forming an image on the recording paper; an operation unit 130 designating an insertion position for inserting the insert-sheet; a discharge unit discharging the sheets of recording paper having images formed and the insert-sheet; and a control unit 102 controlling timing for inserting the insert-sheet. The insertion position is designated by a copy-by-copy basis with one copy being a set of sheets of recording paper having all images included in a job instructing image formation on the recording paper formed thereon. The control unit 102 controls the discharge unit such that the sheets of recording paper having the image formed thereon are discharged by the number determined from the insertion position and thereafter the insert-sheet is discharged. Thus, the insert-sheet can be inserted at an arbitrary position designated on the copy-by-copy basis, and the user can easily handle the output sheets of recording paper.

A control apparatus includes a grouping unit configured to divide a plurality of sheets, each associated with a plurality of pages included in a processing target job into groups, and a control unit to control feeding of a sheet from a feeding unit onto a conveyance path and refeeding of a sheet that has been conveyed on the conveyance path onto the conveyance path. The grouping unit sets a group size that is not less than a maximum sheet size used in the processing target job, and the grouping unit decides the group of the predetermined page as the first group. The grouping unit also decides the group of the predetermined page as a second group different from the first group, and the control unit controls feeding and refeeding for each group grouped in the grouping unit.

An image forming apparatus configured to change an interleaf control mode from a not confirmed sheet-feeding mode to a sheet-presence confirmed sheet-feeding mode when a remaining amount of recording sheets is less than a first threshold, wherein the image forming apparatus has a first mode of changing a feeding origin of a recording sheet, according to detection of absence of a recording sheet in a storage unit by a sheet presence/absence detection unit during execution of an image forming job, and a second mode of changing a feeding origin of a recording sheet, according to detection of a recording-sheet remaining amount of the storage unit less than a second threshold during execution of an image forming job, and wherein the second threshold is larger than the first threshold for changing an interleaf control mode.

A control unit of an image forming device determines a remaining amount threshold value, and selects a first mode or a second mode. In the first mode, a sheet feeding unit of the image forming device starts feeding a sheet based on presence/absence of an insertion sheet that is to be inserted by a inserter device immediately prior to a sheet fed from the sheet feeding unit. In the second mode, the sheet feeding unit starts feeding a sheet regardless of presence/absence of an insertion sheet that is to be inserted by the inserter device immediately prior to a sheet fed from the sheet feeding unit.

An image forming apparatus includes a storage unit that stores recording sheets, an image forming unit that forms an image on a recording sheet, an insertion unit that inserts an interleaving sheet between recording sheets, a first detection unit configured to detect presence or absence of a recording sheet in the storage unit, a second detection unit configured to detect a remaining amount of recording sheets in the storage unit, and a control unit configured to control sheet feeding start timing of the interleaving sheet based on detection results acquired by the first detection unit and the second detection unit

An image forming apparatus includes an image forming unit configured to form an image on a sheet, a sheet discharge tray, a sheet discharge unit positioned between the image forming unit and the sheet discharge tray to discharge a first sheet after an image has been formed on the first sheet by the image forming unit, onto the sheet discharge tray, and a control unit. The control unit is configured to cause a second sheet, which is a light blocking sheet, to be discharged onto the first sheet after the first sheet has been discharged onto the sheet discharge tray.