A sheet stacker includes a sheet stacking portion, a guide portion, and an air blower. The sheet stacking portion is configured to stack a sheet bundle. The guide portion is configured to receive a leading end of a sheet conveyed toward the sheet stacking portion and guide the sheet downstream in a sheet conveyance direction in which the sheet is conveyed. The air blower is disposed above the sheet stacking portion and configured to blow air toward the sheet on a downstream side, in the sheet conveyance direction, from a position at which the guide portion receives the leading end of the sheet.

A sheet stacker includes a sheet stacking portion, a guide portion, and an air blower. The sheet stacking portion is configured to stack a sheet bundle. The guide portion is configured to receive a leading end of a sheet conveyed toward the sheet stacking portion and guide the sheet downstream in a sheet conveyance direction in which the sheet is conveyed. The air blower is disposed above the sheet stacking portion and configured to blow air toward the sheet on a downstream side, in the sheet conveyance direction, from a position at which the guide portion receives the leading end of the sheet.

A suction fan of a sheet feeder sucks in air through a sheet feeding belt to generate flotation air. The suction fan uses the flotation air to attract set sheets by suction. A belt motor rotates a sheet feeding belt and feeds out a sheet of the set sheets. An interval measurer measures a sheet-to-sheet interval when the suction fan is attracting the sheet by suction. Based on an output of the interval measurer, a controller recognizes the sheet-to-sheet interval. Based on the recognized sheet-to-sheet interval, the controller adjusts a flow rate of the flotation air.

A suction fan of a sheet feeder sucks in air through a sheet feeding belt to generate flotation air. The suction fan uses the flotation air to attract set sheets by suction. A belt motor rotates a sheet feeding belt and feeds out a sheet of the set sheets. An interval measurer measures a sheet-to-sheet interval when the suction fan is attracting the sheet by suction. Based on an output of the interval measurer, a controller recognizes the sheet-to-sheet interval. Based on the recognized sheet-to-sheet interval, the controller adjusts a flow rate of the flotation air.

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.

A medium processing apparatus includes a processing unit that performs processing on a sheet-like medium; an outer wall on which a discharge port, from which the medium processed by the processing unit is discharged, is open; a stacking portion that has a stacking surface on which the medium discharged from the discharge port is stacked; a suction unit that sucks air on the stacking surface via a suction port provided below the discharge port; and a control unit that controls a workload of the suction unit. The control unit reduces the workload of the suction unit according to an open area of the suction port which is occluded by the medium stacked on the stacking portion and is decreased.

A medium processing apparatus includes a processing unit that performs processing on a sheet-like medium; an outer wall on which a discharge port, from which the medium processed by the processing unit is discharged, is open; a stacking portion that has a stacking surface on which the medium discharged from the discharge port is stacked; a suction unit that sucks air on the stacking surface via a suction port provided below the discharge port; and a control unit that controls a workload of the suction unit. The control unit reduces the workload of the suction unit according to an open area of the suction port which is occluded by the medium stacked on the stacking portion and is decreased.

A sheet feeding parameter management system includes: a plurality of air sheet feeding apparatuses each including an air sheet feeder that feeds a sheet and enabled to change a sheet feeding parameter; and a management apparatus connected to the plurality of air sheet feeding apparatuses, wherein each of the plurality of air sheet feeding apparatuses includes: a sheet type information acquisitor that acquires sheet type information; and a hardware processor that: adjusts the sheet feeding parameter; and transmits the sheet type information and the sheet feeding parameter to the management apparatus, and the management apparatus includes the hardware processor that: causes a storage to store an adjustment result associated with the sheet type information and the sheet feeding parameter; and sets, based on the adjustment result, for an air sheet feeding apparatus to be processed among the plurality of air sheet feeding apparatuses.

A sheet feeding parameter management system includes: a plurality of air sheet feeding apparatuses each including an air sheet feeder that feeds a sheet and enabled to change a sheet feeding parameter; and a management apparatus connected to the plurality of air sheet feeding apparatuses, wherein each of the plurality of air sheet feeding apparatuses includes: a sheet type information acquisitor that acquires sheet type information; and a hardware processor that: adjusts the sheet feeding parameter; and transmits the sheet type information and the sheet feeding parameter to the management apparatus, and the management apparatus includes the hardware processor that: causes a storage to store an adjustment result associated with the sheet type information and the sheet feeding parameter; and sets, based on the adjustment result, for an air sheet feeding apparatus to be processed among the plurality of air sheet feeding apparatuses.

In order to properly suppress a discharge defect corresponding to an image ratio of a sheet, in the case where a coefficient of friction is different according to the image ratio of an image on the sheet, an air blowing section is arranged to blow air toward a downstream side in a transport direction from between a downstream-side end portion of a first stacking section and an upstream-side end portion of a second stacking section. When an image ratio of an image on a sheet by an image forming apparatus is a first value, the air blowing section sets an air quantity blown to the sheet at a first air quantity F1, while when the image ratio is a second value higher than the first value, setting the air quantity blown to the sheet at a second air quantity F2 larger than the first air quantity F1.