An image forming apparatus includes a storage unit to store recording sheets, an image forming unit, an insertion unit, including an interleaving sheet tray on which an interleaving sheet is to be stacked, and to insert the interleaving sheet fed from the interleaving sheet tray between recording sheets conveyed from the image forming unit. The control unit selects between a first mode and a second mode to execute based on a detected remaining amount of recording sheets in the storage unit. The first mode is a mode for feeding the interleaving sheet, which is to be inserted, from the interleaving sheet tray regardless of whether a presence of the recording sheet in the storage unit is detected. The second mode is a mode for feeding the interleaving sheet from the interleaving sheet tray based on that presence of the recording sheet in the storage unit is detected.

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.

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.

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.

In accordance with an embodiment, an image forming apparatus comprises a first printing unit configured to execute printing with non-decolorable first toner on an image receiving medium, a second printing unit configured to execute printing with decolorable second toner on the image receiving medium, and a control module configured to print an image according to image information on the image receiving medium with the first printing unit, and execute printing on a cover paper of the image receiving medium with the second printing unit.

An aligning unit stores a paper bundle that is formed by inserting a medium that is different from printed body text paper sheets conveyed from a printer into the printed body text paper sheets. A manual paper feeding unit stores a medium that is manually fed. A conveyance control unit makes the medium be conveyed from the manual paper feeding unit to the aligning unit after the body text paper sheets that include a page specified by a print job are stored in the aligning unit and before the body text paper sheet conveyed from the printer immediately afterwards is stored in the aligning unit.

A paperboard includes plural stacked paper layers. The surface electrical resistance of an image forming surface of the paperboard in an electrophotographic system is 110.sup.13 or less after humidity control in an environment of 20 C. and 10% RH.

An image forming system is described which is capable of assembling an output product which consists of sheets having uniform sheet widths by appropriately performing a trimming process even if the output product is made from a plurality of paper types. The image forming system consists of an image forming apparatus configured to form an image on a sheet; a finisher provided with a slit unit for trimming edges of sheets and capable of assembling an output product by joining the trimmed sheets, and a control unit for controlling the image forming apparatus and the finisher. When a book cover (standard paper type sheet) is supplied, the control unit trims the paper edges by a designated trimming width. Conversely, when a book body (non-standard paper type sheet) is supplied, the control unit trims the paper edges by a designated trimming width to which an offset amount is added.