Equipment for stacking sheets with a stack support, input rollers for feeding entering sheets and transport belts with lower branches arranged above the stack support. A compensation mechanism modifies the height of the stack support, while the transport belts are motorized to drag the entering sheets with the lower branches and deposit the sheets on the stack support or on stacked sheets. An arrest member is provided for the entering sheets, a pressure member for the stack to be stacked and a sensor device for a last sheet of the stack. The arrest member arrests the sheets in stacking while the pressure member is contiguous to the stop member and operates on the last sheet of the stack with a stabilizing function and in which the compensation mechanism is servoized to the sensor, for maintaining constant the height of the last sheet of the stack from a reference plane.

A feeder includes a mount board that moves vertically while allowing sheet-shaped media to be stacked thereon; a transport device allows an uppermost one of the sheet-shaped media stacked on the mount board to be sucked by a suction portion to transport the uppermost medium to a transporter and to feed the uppermost medium to a destination; left and right edge air blowers blow air to transportation left and right edge portions of upper ones of the sheet-shaped media stacked; and a tip-end air blower blows air to below the uppermost medium sucked by the suction portion from a position downstream from a transportation leading end of the uppermost medium in a transport direction. When the uppermost medium is sucked by the suction portion, the feeder performs a first operation of spacing an upwardly bent transportation leading-end portion of a second uppermost medium apart downward from the sucked uppermost medium.

An image forming apparatus includes a sensor, a tray, a gear, a protruding portion, and a processor. The sensor has a light transmitting unit and light receiving units and is configured to generate an output signal in accordance with an amount of light received by the light receiving units. The gear is configured to rotate in accordance with an amount of sheets stacked on the tray. The protruding portion is configured to rotate with the gear and move into a light path of light emitted from the light emitting unit to the light receiving units to partially block the light, the protruding portion having a width that determines how much light in the light path is blocked and varies gradually from a first end thereof to a second end thereof. The processor is configured to determine the amount of sheets stacked on the tray based on the output signal.

A stacker module includes a lift table, a stacker configured to place sheets that are successively supplied thereto onto the top of a stack forming on the lift table, a controller configured to lower the lift table as the stack grows, a height-adjustable eject table, and an eject mechanism configured to transfer a completed stack from the lift table onto the eject table. The eject mechanism is height-adjustable for transferring stacks onto the eject table in different height positions of the lift table.

A stacker module includes a lift table, a stacker configured to place sheets that are successively supplied thereto onto the top of a stack forming on the lift table, a controller configured to lower the lift table as the stack grows, a height-adjustable eject table, and an eject mechanism configured to transfer a completed stack from the lift table onto the eject table. The eject mechanism is height-adjustable for transferring stacks onto the eject table in different height positions of the lift table.

Provided is a document conveying apparatus that properly discharges documents regardless of the amount of documents stacked on a discharge tray without complicated construction of a transmission mechanism for transmitting a driving force to conveying rollers. A conveying roller pair is provided at an end portion on an upstream side. A swing mechanism swings a discharge mechanism centered around a drive shaft of the conveying roller pair. An upper surface height measuring unit measures the height of the upper surface of documents stacked on the discharge tray. A control unit, by causing the swing mechanism to swing the discharge mechanism according to the height measured by the upper surface height measuring unit, performs control so that the difference between a discharge port and the upper surface of the documents stacked on the discharge tray is within a specified range.

Provided is a document conveying apparatus that properly discharges documents regardless of the amount of documents stacked on a discharge tray without complicated construction of a transmission mechanism for transmitting a driving force to conveying rollers. A conveying roller pair is provided at an end portion on an upstream side. A swing mechanism swings a discharge mechanism centered around a drive shaft of the conveying roller pair. An upper surface height measuring unit measures the height of the upper surface of documents stacked on the discharge tray. A control unit, by causing the swing mechanism to swing the discharge mechanism according to the height measured by the upper surface height measuring unit, performs control so that the difference between a discharge port and the upper surface of the documents stacked on the discharge tray is within a specified range.

A recording system includes a recording portion that performs recording on a medium, a stacking portion that stacks the medium recorded by the recording portion, and a processing portion that processes a bundle of media stacked on the stacking portion, in which a controller that controls feeding of the medium to the stacking portion determines a maximum number of sheets of media to be stacked on the stacking portion, based on information on swelling of the medium recorded by the recording portion.

A recording system includes a recording portion that performs recording on a medium, a stacking portion that stacks the medium recorded by the recording portion, and a processing portion that processes a bundle of media stacked on the stacking portion, in which a controller that controls feeding of the medium to the stacking portion determines a maximum number of sheets of media to be stacked on the stacking portion, based on information on swelling of the medium recorded by the recording portion.

An example method for estimating a media level of a media stack in a printer includes storing a media level model correlating a picker metric of a media picker to pick media from the media stack to the media level; measuring a current picker metric when the media picker picks the media from the media stack during a print job; adding the current picker metric to a historical data set; updating the media level model by generating a regression for the historical data set; and based on the current picker metric and the updated media level model, estimating a current media level of the media stack.