A sheet aligning mechanism includes first and second conveyance mechanisms disposed on first and second sides of a sheet conveyance path, respectively. A nip is formed between the first and second conveyance mechanisms. The first conveyance mechanism includes a first roller, a second roller, and a first conveyance belt wound around the first and second rollers. The first and second rollers are configured to rotate in a first direction along a sheet conveying direction for sheet conveyance, and stop rotation or rotate in a second direction opposite to the first direction for sheet alignment. The first conveyance belt includes an extended region between the first and second rollers in an extending direction inclined with respect to the sheet conveying direction, such that a width of the sheet conveyance path becomes narrower towards the nip in the sheet conveying direction.

A medium-transporting device includes: a medium-support section that has a first mounting surface inclined relative to a horizontal plane; a transport path for transporting a medium; a discharge stacker that is configured to switch between an extended state in which a second mounting surface that is inclined relative to the horizontal plane and that receives the medium discharged along the transport path is formed and a stored state in which the second mounting surface is stored in the medium-transporting device, a control section is configured to perform first control of switching the discharge stacker from the extended state to the stored state after the medium is discharged to the second mounting surface and second control of not switching the discharge stacker from the extended state to the stored state such that the medium remains mounted on the second mounting surface.

A medium-transporting device includes: a medium-support section that has a first mounting surface inclined relative to a horizontal plane; a transport path for transporting a medium; a discharge stacker that is configured to switch between an extended state in which a second mounting surface that is inclined relative to the horizontal plane and that receives the medium discharged along the transport path is formed and a stored state in which the second mounting surface is stored in the medium-transporting device, a control section is configured to perform first control of switching the discharge stacker from the extended state to the stored state after the medium is discharged to the second mounting surface and second control of not switching the discharge stacker from the extended state to the stored state such that the medium remains mounted on the second mounting surface.

Provided is a stacker including a stacking shelf on which printed paper from a printer is received and stacked, a lifting and lowering mechanism that lifts and lowers the stacking shelf, and a stacker control unit that controls the lifting and lowering mechanism. The stacker control unit controls the lifting and lowering mechanism to lift and lower the stacking shelf to a first predetermined height corresponding to the printer at a receiving position for receiving the paper from the printer, and to lift and lower the stacking shelf to a second predetermined height corresponding to a sheet processing machine at a paper supply position for supplying paper to the sheet processing machine, the paper supply position being different from the receiving position.

A post-processing apparatus includes a post-processing device, an ejection device, and an ejection tray. The post-processing device executes post-processing on a medium on which an image is formed by an image forming apparatus. The ejection device ejects the medium on which the post-processing is executed by the post-processing device. The ejection tray holds the medium ejected by the ejection device. The ejection tray includes a main tray having an upper face inclined downward in an ejection direction, and a movable tray being rotatably supported by the main tray between a stacking position at which the medium ejected by the ejection device remains stacked on the upper face of the main tray and an ejection position at which the medium ejected by the ejection device slides along the upper face of the main tray.

A post-processing apparatus includes a post-processing device, an ejection device, and an ejection tray. The post-processing device executes post-processing on a medium on which an image is formed by an image forming apparatus. The ejection device ejects the medium on which the post-processing is executed by the post-processing device. The ejection tray holds the medium ejected by the ejection device. The ejection tray includes a main tray having an upper face inclined downward in an ejection direction, and a movable tray being rotatably supported by the main tray between a stacking position at which the medium ejected by the ejection device remains stacked on the upper face of the main tray and an ejection position at which the medium ejected by the ejection device slides along the upper face of the main tray.

A sheet discharge apparatus includes a pivot member pivoting in an up-down direction by being pressed by a sheet discharged from a sheet discharging portion, with the pivot member retained by being in contact with an uppermost sheet supported on the sheet supporting portion. A control unit changes a sheet interval between a preceding sheet and a succeeding sheet and executes a first discharge operation in which at least one sheet is discharged, and a second discharge operation in which sheets are discharged by the sheet discharging portion at a first sheet interval such that the pivot member does not contact with an uppermost sheet supported on the sheet supporting portion during the second discharge operation, and the control unit acquires a number of sheets to be discharged in the second discharge operation based on a detected position of the pivot member detected during the first discharge operation.

A sheet discharge apparatus includes a pivot member pivoting in an up-down direction by being pressed by a sheet discharged from a sheet discharging portion, with the pivot member retained by being in contact with an uppermost sheet supported on the sheet supporting portion. A control unit changes a sheet interval between a preceding sheet and a succeeding sheet and executes a first discharge operation in which at least one sheet is discharged, and a second discharge operation in which sheets are discharged by the sheet discharging portion at a first sheet interval such that the pivot member does not contact with an uppermost sheet supported on the sheet supporting portion during the second discharge operation, and the control unit acquires a number of sheets to be discharged in the second discharge operation based on a detected position of the pivot member detected during the first discharge operation.

A paper stacking device includes: a stacker on which paper is stacked; a paper ejector that ejects the paper toward the stacker; an aligning plate that is provided on a side of the paper stacked on the stacker, and aligns a side end of the paper; and a paper floating member that is provided in the aligning plate, and supports, from below, the side end of the paper ejected from the paper ejector, wherein the paper floating member is switched, in conjunction with a movement in upward and downward directions of the aligning plate, between: a paper floating position that advances from a side of the side end of the paper to an ejection route of the paper, and causes the paper ejected from the paper ejector to float from uppermost paper stacked on the stacker; and a retreat position that retreats from the ejection route.

A paper stacking device includes: a stacker on which paper is stacked; a paper ejector that ejects the paper toward the stacker; an aligning plate that is provided on a side of the paper stacked on the stacker, and aligns a side end of the paper; and a paper floating member that is provided in the aligning plate, and supports, from below, the side end of the paper ejected from the paper ejector, wherein the paper floating member is switched, in conjunction with a movement in upward and downward directions of the aligning plate, between: a paper floating position that advances from a side of the side end of the paper to an ejection route of the paper, and causes the paper ejected from the paper ejector to float from uppermost paper stacked on the stacker; and a retreat position that retreats from the ejection route.