A sheet processing apparatus includes a plurality of roller pairs, a single driving force supply source, and a drive transmission mechanism. The plurality of roller pairs include a first roller pair, a second roller pair, and a third roller pair. The single driving force supply source supplies a driving force to the first roller pair, the second roller pair, and the third roller pair. The drive transmission mechanism transmits the driving force to the first roller pair and the second roller pair in a manner such that a rotation direction of the first roller pair is not switched even in a case in which a direction of the driving force is switched such that a rotation direction of the second roller pair is switched when the first roller pair and the second roller pair are driven by the driving force from the driving force supply source.

An embodiment of this disclosure provides a folding apparatus configured to stack and fold a designated number of sheets at a time. The folding apparatus includes a conveyor configured to sequentially convey the designated number of sheets, a stacker configured to temporarily store a sheet conveyed by the conveyor to stack the designated number of sheets, a sheet folding device configured to fold the designated number of sheets at a time, and control circuitry. The control circuitry is configured to cause the sheet folding device to fold the stored sheet in response to an occurrence of a sheet jam upstream from the stacker in a direction of sheet conveyance, in processing the designated number of sheets.

An embodiment of this disclosure provides a folding apparatus configured to stack and fold a designated number of sheets at a time. The folding apparatus includes a conveyor configured to sequentially convey the designated number of sheets, a stacker configured to temporarily store a sheet conveyed by the conveyor to stack the designated number of sheets, a sheet folding device configured to fold the designated number of sheets at a time, and control circuitry. The control circuitry is configured to cause the sheet folding device to fold the stored sheet in response to an occurrence of a sheet jam upstream from the stacker in a direction of sheet conveyance, in processing the designated number of sheets.

A sheet folding apparatus includes a conveyance member to convey a sheet from an ejection member at a first speed lower than a conveyance speed by the ejection member or a second speed substantially same as or higher than the conveyance speed; a registration member; a pair of first and second rollers to rotate in forward and reverse directions; a plurality of folding rollers downstream from the second roller, to rotate in forward and reverse directions to fold the sheet; and circuitry to determine whether the sheet is equal to or smaller than a reference length from an exit position from the ejection member to a folding start position downstream from the pair of the first and second rollers. The circuitry performs first-speed folding when the sheet is equal to or smaller than the reference length and performs second-speed folding when the sheet is longer than the reference length.

A sheet folding apparatus includes a conveyance member to convey a sheet from an ejection member at a first speed lower than a conveyance speed by the ejection member or a second speed substantially same as or higher than the conveyance speed; a registration member; a pair of first and second rollers to rotate in forward and reverse directions; a plurality of folding rollers downstream from the second roller, to rotate in forward and reverse directions to fold the sheet; and circuitry to determine whether the sheet is equal to or smaller than a reference length from an exit position from the ejection member to a folding start position downstream from the pair of the first and second rollers. The circuitry performs first-speed folding when the sheet is equal to or smaller than the reference length and performs second-speed folding when the sheet is longer than the reference length.

A sheet folding processing apparatus suppresses an increase in size and cost of the apparatus and performs folding processing on continuously conveyed sheets. In the sheet folding processing apparatus, a sheet conveyed by a feeding roller pair and hang in a loop shape in a loop forming space is pushed into a nipping portion of a folding roller pair by a pushing plate, so that the sheet is folded in a Z-shape to form a plurality of fold lines. The sheet is conveyed in the conveyance direction until the sheet rear end passes through the feeding roller pair, and after the sheet rear end is stored in a loop forming space by moving the pushing plate from a position for pushing the sheet into a nipping portion to a retracting position, the reinforcing processing of the fold line of the sheet is performed by an additional folding unit.

A sheet folding processing apparatus suppresses an increase in size and cost of the apparatus and performs folding processing on continuously conveyed sheets. In the sheet folding processing apparatus, a sheet conveyed by a feeding roller pair and hang in a loop shape in a loop forming space is pushed into a nipping portion of a folding roller pair by a pushing plate, so that the sheet is folded in a Z-shape to form a plurality of fold lines. The sheet is conveyed in the conveyance direction until the sheet rear end passes through the feeding roller pair, and after the sheet rear end is stored in a loop forming space by moving the pushing plate from a position for pushing the sheet into a nipping portion to a retracting position, the reinforcing processing of the fold line of the sheet is performed by an additional folding unit.

A sheet folding processing apparatus performs folding processing on continuously conveyed sheets without lowering productivity. A sheet folding processing apparatus includes a conveyance roller pair, a folding roller pair forming a plurality of fold lines by bending a sheet conveyed from the conveyance roller pair in Z-shape, an additional folding roller and a lower folding guide arranged downstream of the folding roller pair to face each other and pressing the fold line of the sheet in corporation with each other, and a controller controlling operation of the above. The controller controls the folding roller pair to convey the sheet with the fold line downstream in a conveyance direction until the fold line passes through the additional folding position by a predetermined conveyance amount, to return the sheet upstream by reversely rotating the folding roller pair, and to position the fold line to the additional folding position for additional folding processing.

A sheet folding processing apparatus performs folding processing on continuously conveyed sheets without lowering productivity. A sheet folding processing apparatus includes a conveyance roller pair, a folding roller pair forming a plurality of fold lines by bending a sheet conveyed from the conveyance roller pair in Z-shape, an additional folding roller and a lower folding guide arranged downstream of the folding roller pair to face each other and pressing the fold line of the sheet in corporation with each other, and a controller controlling operation of the above. The controller controls the folding roller pair to convey the sheet with the fold line downstream in a conveyance direction until the fold line passes through the additional folding position by a predetermined conveyance amount, to return the sheet upstream by reversely rotating the folding roller pair, and to position the fold line to the additional folding position for additional folding processing.

A sheet postprocessing device includes a sheet conveying passage, a sheet tray, an inlet guide, a processing device, and a blowing device. Though the sheet conveying passage, a sheet on which an image has been formed is conveyed. The sheet tray is arranged downstream of the sheet conveying passage and has sheets stacked on it. The inlet guide is arranged at the downstream end of the sheet conveying passage and guides a sheet to the sheet tray. The processing device performs predetermined processing on a sheet stacked on the sheet tray. The blowing device blows air, from the upstream side in the sheet conveying direction, between the top face of the top-most sheet in the sheets stacked on the sheet tray and the bottom face of the subsequent sheet sent from the inlet guide into the sheet tray.