A controller drives a floating unit and a conveyor to perform a sheet feed operation, during the sheet feed operation, acquires an amount of received light at a detector during floating of sheets floated by the floating unit each time each sheet is conveyed by the conveyor, and perform a following control of lifting a stacking tray upon the acquired amount of received light being less than a threshold value. The controller, after start of the sheet feed operation, samples amounts of received light at the detector during floating of the sheets floated by the floating unit, performs a threshold value determination process of determining the threshold value by using the sampled amounts of received light, and starts the following control upon determining the threshold value.

A post-processing device includes an output unit that outputs a medium; a stacking unit on which the medium that is output is stacked; and a blow-out unit that is disposed below the output unit and that blows gas toward the medium that is output, wherein an amount of the gas blown is adjusted in accordance with a type of the medium.

A post-processing device includes an output unit that outputs a medium; a stacking unit on which the medium that is output is stacked; and a blow-out unit that is disposed below the output unit and that blows gas toward the medium that is output, wherein an amount of the gas blown is adjusted in accordance with a type of the medium.

A sheet feeding apparatus includes a sheet supporting unit, a sheet feed unit, an air separation unit configured to separate the uppermost sheet by blowing the air onto a side surface of the sheet bundle supported by the sheet supporting unit, a velocity detection unit configured to detect actual velocity of a sheet fed by the sheet feed unit, a drive load detection unit configured to detect an actual drive load for feeding the sheet by the sheet feed unit, and a controller configured to control the sheet feed unit and the air separation unit. In a case where the sheet is fed by the sheet feed unit, the controller is configured to control an operation of the air separation unit depending on the actual velocity of the sheet detected by the velocity detection unit and the actual drive load detected by the drive load detection unit.

A sheet transport device includes a processor configured to change lifting control for lifting sheets on a tray, which are to be floated up and handed over, from normal state control to small-quantity state control in a case where it is detected that the remaining number of sheets on the tray is small.

A sheet transport device includes a processor configured to change lifting control for lifting sheets on a tray, which are to be floated up and handed over, from normal state control to small-quantity state control in a case where it is detected that the remaining number of sheets on the tray is small.

An image forming apparatus includes an image forming device, a transport route, a purge transport route, an image forming transport route, a transport roller, and a blowing machine. The image forming device forms an image on a sheet. The transport route extends to a predetermined position. The purge transport route extends to a downstream side in a sheet transport direction, from the predetermined position. The image forming transport route is branched from the purge transport route at the predetermined position, and extends toward the image forming device. The transport roller transports the sheet along the transport route, and along one of the purge transport route and the image forming transport route. The blowing machine delivers the sheet to one of the purge transport route and the image forming transport route, by blowing air to the sheet being transported along the transport route.

A sheet stacker includes a tray to store a stack of sheets, a conveyor above the tray, a leading end guide above the tray, and an air exhaust. The conveyor conveys a sheet in a conveyance direction. The leading end guide is downstream from the conveyor in the conveyance direction. The leading end guide guides the sheet from the conveyor to the tray. The air exhaust exhausts air above an upper surface of the stack of sheets on the tray to an upstream from the tray in the conveyance direction. Further, the leading end guide holds a leading end of the sheet conveyed by the conveyor at a holding position and releases the leading end of the sheet at a release position downstream from the holding position in the conveyance direction.

A sheet stacker includes a tray to store a stack of sheets, a conveyor above the tray, a leading end guide above the tray, and an air exhaust. The conveyor conveys a sheet in a conveyance direction. The leading end guide is downstream from the conveyor in the conveyance direction. The leading end guide guides the sheet from the conveyor to the tray. The air exhaust exhausts air above an upper surface of the stack of sheets on the tray to an upstream from the tray in the conveyance direction. Further, the leading end guide holds a leading end of the sheet conveyed by the conveyor at a holding position and releases the leading end of the sheet at a release position downstream from the holding position in the conveyance direction.

A sheet feeding apparatus includes: a placer that allows a plurality of sheets to be placed on the placer; an air feeder including a front-end fan that generates an airflow from a front-edge side in a sheet feeding direction of a bundle of sheets placed on the placer toward the bundle of sheets; an attracting conveyor that attracts an uppermost sheet separated by the air feeder from the bundle of sheets placed on the placer and conveys the uppermost sheet; a detector that detects, in the conveyance of the uppermost sheet by the attracting conveyor, an amount of co-feeding of a next sheet together with the uppermost sheet; and a hardware processor that executes air-volume control to the front-end fan such that an air volume of the front-end fan increases with an increase in the amount of co-feeding detected by the detector.