Provided is a sheet stacking apparatus, including: a placement portion on which a sheet is placed; a conveyance portion conveying a sheet placed on the placement portion; a regulation portion regulating a position of a sheet conveyed by the conveyance portion through contact with the sheet; and a pressing portion pressing a sheet regulated in position by the regulation portion, the pressing portion pressing a sheet regulated in position by the regulation portion at a first pressing position and a second pressing position, the second pressing position being spaced apart from the placement portion in a thickness direction of sheets placed on the placement portion by a distance which is longer than a distance between the placement portion and the first pressing position, in which an area of pressing a sheet at the first pressing position is larger than an area of pressing a sheet at the second pressing position.

A sheet processing apparatus that forms a folding line on a sheet includes first and second folding rollers that form a folding line on the sheet by rotating a bent sheet while pinching from sheet surfaces and a first pressing unit that presses the second folding roller against the first folding roller in an arbitrary portion in a rotating shaft direction of the second folding roller.

There is provided a stacking apparatus capable of stably conveying and stacking sheets without occurrence of damage or buckling of the sheets in the structure of discharging the curled sheets one by one. In regard to each of a plurality of clamp guides which project toward stacking trays from a conveyor to guide sheets S, the projecting position varies in accordance with a size and an amount of stacked sheets on the stack trays. The stacking tray comprises an inclined surface and a curved surface. An upper guide is located to face the inclined surface by a predetermined interval, and the upper guide is located not to face the curved surface or is located to face it by an interval larger than a predetermined interval.

There is provided a stacking apparatus capable of stably conveying and stacking sheets without occurrence of damage or buckling of the sheets in the structure of discharging the curled sheets one by one. In regard to each of a plurality of clamp guides which project toward stacking trays from a conveyor to guide sheets S, the projecting position varies in accordance with a size and an amount of stacked sheets on the stack trays. The stacking tray comprises an inclined surface and a curved surface. An upper guide is located to face the inclined surface by a predetermined interval, and the upper guide is located not to face the curved surface or is located to face it by an interval larger than a predetermined interval.

A sheet feeder, which is incorporated in an image forming apparatus, includes an endless attraction belt that is rotatably disposed facing a top surface of a sheet stack, a belt charger to attract an uppermost sheet of the sheet stack, and a sheet separator to press the attraction belt against the sheet stack, bend a contact region to which the uppermost sheet is attracted and contacted to the attraction belt, and separate the uppermost sheet from a subsequent sheet or other sheet of the sheet stack. In this configuration, a curvature of a contact surface of the sheet separator with respect to the attraction belt is changeable.

A sheet feeder, which is incorporated in an image forming apparatus, includes an endless attraction belt that is rotatably disposed facing a top surface of a sheet stack, a belt charger to attract an uppermost sheet of the sheet stack, and a sheet separator to press the attraction belt against the sheet stack, bend a contact region to which the uppermost sheet is attracted and contacted to the attraction belt, and separate the uppermost sheet from a subsequent sheet or other sheet of the sheet stack. In this configuration, a curvature of a contact surface of the sheet separator with respect to the attraction belt is changeable.

A sheet processing apparatus that forms a folding line on a sheet includes first and second folding rollers that form a folding line on the sheet by rotating a bent sheet while pinching from sheet surfaces and a first pressing unit that presses the second folding roller against the first folding roller in an arbitrary portion in a rotating shaft direction of the second folding roller.

A conveyor device, including: a first roller; a second roller disposed under the first roller and configured to be movable between a nip position at which the second roller cooperates with the first roller to nip a sheet therebetween so as to discharge the sheet in a discharge direction and a separated position located at a height level lower than the nip position; a cover configured to be movable between a first position and a second position located at a height level lower than the first position, the cover including a downstream wall which at least partially covers a downstream portion of the second roller located at the nip position when the cover is located at the first position; and a moving mechanism configured to move the second roller between the nip position and the separated position and to move the cover between the first position and the second position.

A conveyor device, including: a first roller; a second roller disposed under the first roller and configured to be movable between a nip position at which the second roller cooperates with the first roller to nip a sheet therebetween so as to discharge the sheet in a discharge direction and a separated position located at a height level lower than the nip position; a cover configured to be movable between a first position and a second position located at a height level lower than the first position, the cover including a downstream wall which at least partially covers a downstream portion of the second roller located at the nip position when the cover is located at the first position; and a moving mechanism configured to move the second roller between the nip position and the separated position and to move the cover between the first position and the second position.

A media stacker may comprises a stacking platform; and a pair of a guiding tracks above the stacking platform and extending from a media receiving side of the media stacker in a media advance direction along opposite sides of a media transport path; wherein at least one guiding track of the pair of guiding tracks is movable between a support position and a release position to guide and support the media sheet above the stacking platform and to release the media sheet to drop from the guiding track to the stacking platform.