A sheet stacker includes a pair of sheet holders, a sheet leading-edge aligner, a sheet stacking member, and control circuitry. A downstream side of the pair of sheet holders in a conveyance direction of a conveyed sheet is lowered along the conveyance direction. Each one of the pair of sheet holders is movable in an orthogonal direction to the conveyance direction. The pair of sheet holders hold both side-end portions of the sheet in the orthogonal direction. The sheet stacking member is disposed below the pair of sheet holders. A downstream side of the sheet stacking member in the conveyance direction is lowered along the conveyance direction. The sheet stacking member stacks the sheet dropped from the pair of sheet holders after a leading edge of the sheet is aligned by the leading-edge aligner. The control circuitry controls operations of the leading-edge aligner and the pair of sheet holders.

A sheet stacker includes a pair of sheet holders, a sheet leading-edge aligner, a sheet stacking member, and control circuitry. A downstream side of the pair of sheet holders in a conveyance direction of a conveyed sheet is lowered along the conveyance direction. Each one of the pair of sheet holders is movable in an orthogonal direction to the conveyance direction. The pair of sheet holders hold both side-end portions of the sheet in the orthogonal direction. The sheet stacking member is disposed below the pair of sheet holders. A downstream side of the sheet stacking member in the conveyance direction is lowered along the conveyance direction. The sheet stacking member stacks the sheet dropped from the pair of sheet holders after a leading edge of the sheet is aligned by the leading-edge aligner. The control circuitry controls operations of the leading-edge aligner and the pair of sheet holders.

A medium loading device includes a side end aligning member which is positioned at a standby position when a medium is ejected; and a control section. When a value based on first information relating to recording density of a medium to be ejected this time and at least one medium among the media ejected previously is equal to or greater than a threshold value, the control section specifies a first position, which overlaps the medium to be ejected this time, as the standby position, and when the value based on the first information is less than the threshold value, the control section specifies a second position, which does not overlap the medium to be ejected this time, as the standby position, and the control section adjusts the threshold value based on second information relating to at least one medium among the media recorded before the ejection at this time.

A recording material processing apparatus includes a guide shaft of which an axial direction extends in a recording material width direction intersecting a discharge direction of a recording material, and an alignment unit that moves along the guide shaft, in which the alignment unit includes a bearing portion that is movably fitted onto the guide shaft, an alignment portion that is provided to be exposed at an outer side in the discharge direction and comes into contact with an end surface of the recording material that is parallel to the discharge direction from an outer side of the recording material to align a position of the end surface, an arm portion that connects the bearing portion and the alignment portion to each other, and a protruding portion that protrudes from a surface of the arm portion to a position outside the recording material in the axial direction of the guide shaft and comes into contact with a surface of a device main body, which is parallel to the discharge direction, in a case where an external force is applied to the alignment unit with the alignment unit being at a position close to the surface.

A sheet post processing device includes a loading tray on which a sheet conveyed thereto is loaded, a side end edge binding stapler fixed at a position opposed to a side end edge, along a conveyance direction, of a sheet bundle of a plurality of sheets loaded on the loading tray, the side end edge binding stapler performing a first binding process on the side end edge, a conveyance unit that moves the sheet bundle on the loading tray in the conveyance direction, and a controller that controls the conveyance unit. The controller can cause the conveyance unit to move the sheet bundle in the conveyance direction so as to perform the first binding process on the sheet bundle with the side end edge binding stapler at a plurality of positions along the side end edge.

A sheet post-processing apparatus includes a first stapler and a second stapler having different thicknesses of sheets on which a binding process can be performed. A control unit can perform a manual staple mode. If the first stapler is selected as a stapler for performing the binding process in the manual staple mode, the control unit controls the alignment member moving mechanism to move alignment members to a position defining a first insertion position for guiding the sheets to a first placing position. If the second stapler is selected, the control unit controls the alignment member moving mechanism to move the alignment members to a position defining a second insertion position for guiding the sheets to a second placing position.

Provided is a book block aligning device that forms one processing line with paper processing devices on an upstream side and a downstream side, and is capable of stably performing alignment processing of a book block at a high speed. Provided is the book block aligning device comprising an air blowing control mechanism that controls start/stop of blowing of air from an air outlet, and an air volume of air, in accordance with timing when a book block passes through the air outlet opened in a conveying surface provided in a conveying path, and a vibration mechanism that vibrates a first conveying surface.

Provided is a book block aligning device that forms one processing line with paper processing devices on an upstream side and a downstream side, and is capable of stably performing alignment processing of a book block at a high speed. Provided is the book block aligning device comprising an air blowing control mechanism that controls start/stop of blowing of air from an air outlet, and an air volume of air, in accordance with timing when a book block passes through the air outlet opened in a conveying surface provided in a conveying path, and a vibration mechanism that vibrates a first conveying surface.

A medium ejection apparatus includes a placement mount on which media are placed, a restriction part that moves between a restriction position at which the restriction part restricts media ejected toward the placement mount and a retracted position retracted from the restriction position, and a processor that controls the restriction part by adjusting a restriction frequency on the basis of at least either an amount of movement of the restriction part from the retracted position to the restriction position or ejection intervals at which the media are ejected toward the placement mount, the restriction frequency being a frequency with which the restriction part performs a restriction operation for the media.

An example stacking system comprises a stacking member movable between a first position in which the stacking member is configured to partially support a first stack of printed substrates, and a second position in which the stacking member is disengaged from the first stack. A receptacle positioned below the stacking member is configured to hold a second stack of printed substrates. A controller is configured to cause the stacking member to move between the first position and the second position when the first stack satisfies a criterion, thereby depositing the first stack into the receptacle on top of the second stack.