A sheet processing apparatus includes a sheet processing unit that processes a sheet placed on a placing tray, a discharge roller that discharges the sheet processed on the placing tray to a stacking tray, a conveyance roller that discharges a sheet to the placing tray or conveys a subsequent sheet from upstream to downstream of the discharge roller and switchback-conveys the subsequent sheet upstream again, and a standby path (branch path) that keeps the sheet switched back by the conveyance roller on standby. The subsequent sheet is conveyed to a downstream side of the discharge roller by the conveyance roller and then returned to an upstream side again by switchback conveyance. During the switchback conveyance, the discharge roller nips and discharges the sheets on the placing tray to the stacking tray.

A binding device includes a receptacle, an aligner, a moving mechanism, first and second binders, and a guide. The aligner aligns a bundle of recording media in a width direction thereof on the receptacle. The moving mechanism moves the aligner in the width direction. A maximum thickness of the bundle of recording media boundable in the second binder is smaller than that in the first binder. The guide is movable conforming to the maximum thickness of the bundle of recording media boundable in the first binder, and conforming to that in the second binder, to guide and direct the bundle of recording media to a receiving portion of the first binder when the first binder binds the bundle of recording media, and to a receiving portion of the second binder when the second binder binds the bundle of recording media, respectively. The guide is movable in conjunction with the aligner.

A binding member is provided and includes: upper teeth having a tooth form configured to form a convex-concave portion on a recording material bundle; and lower teeth having a tooth form configured to form the convex-concave portion on the recording material bundle, and paired with the upper teeth. At least one of the upper teeth and the lower teeth includes: a first tooth row having a first tooth form having a first shape suitable for binding a first binding number of sheets; and a second tooth row having a second tooth form having a second shape suitable for binding a second binding number of sheets which is smaller than the first binding number of sheets.

A binding apparatus includes: a first pressing part that presses a recording material bundle to bind the recording material bundle; a second pressing part that faces the first pressing part; and a pushout part that is formed as a member different from the second pressing part for pushing out the second pressing part toward the first pressing part. The second pressing part is supported to be movable with respect to the pushout part and, when pushed out by the pushout part, presses the recording material bundle.

A binding apparatus includes: a first pressing part that presses a recording material bundle; a second pressing part that faces the first pressing part and presses the recording material bundle; and a moving mechanism that swings at least one of the first pressing part and the second pressing part in a pressing direction to press the recording material bundle and causes the at least one of the first pressing part and the second pressing part to move further with respect to a pressing area of the recording material bundle in an entering and exiting direction where a recoding material or the recoding material bundle enters and exits the pressing area.

A binding unit includes a first pressing part that presses a recording material bundle to bind the recording material bundle, a second pressing part that faces the first pressing part, and a pushout part that pushes out the second pressing part toward the first pressing part by acting on the second pressing part using an upper shaft lever and by varying a distance from a start portion serving as a start point of pushout movement to the upper shaft lever. The start portion is formed integrally with a member at which the first pressing part is formed.

A binding apparatus includes: a first pressing part that presses a recording material bundle; and a second pressing part that is pushed out toward the first pressing part and presses the recording material bundle. When a recording material or the recording material bundle enters a pressing area where the first pressing part and the second pressing part face each other, at least one of the first pressing part and the second pressing part retreats more downstream than the pressing area in a direction where the recording material or the recording material bundle enters the pressing area.

A sheet binding processing apparatus including a crimp binding member that performs binding processing on a predetermined region of a sheet by sandwiching and pressing the sheet between an upper tooth and a lower tooth meshing with each other, and a detection unit that detects a state of the predetermined region of the sheet to be bound by the crimp binding member. If the detection unit detects that the predetermined region is not capable of binding, the binding processing on the predetermined region is prohibited.

A stapleless binding device includes a stapleless binding unit that performs a stapleless binding operation to form irregularities in a sheet stack by making forward and backward movements, a moving unit that relatively moves the stapleless binding unit or the sheet stack in a direction along one side of the sheet stack, and a holding unit that holds the sheet stack during the backward movement of the stapleless binding unit. The holding unit holds the sheet stack during the backward movement of the stapleless binding unit before the moving unit moves the stapleless binding unit or the sheet stack.

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.