Sheets are set on the top face of a lift plate. A lift mechanism makes a lift plate ascend and descend. A sheet feeding roller and a distance sensor are provided over the lift plate. The distance sensor measures a distance (measured distance) to a measurement target placed below. Based on the measured distance before the lift plate is raised, the controller calculates a remaining quantity value indicating a remaining quantity of sheets. When, after the lift plate starts to rise, the recognized measured distance becomes equal to or smaller than the upper limit distance, the controller makes the lift mechanism stop raising the lift plate.

Sheets are set on the top face of a lift plate. A lift mechanism makes a lift plate ascend and descend. A sheet feeding roller and a distance sensor are provided over the lift plate. The distance sensor measures a distance (measured distance) to a measurement target placed below. Based on the measured distance before the lift plate is raised, the controller calculates a remaining quantity value indicating a remaining quantity of sheets. When, after the lift plate starts to rise, the recognized measured distance becomes equal to or smaller than the upper limit distance, the controller makes the lift mechanism stop raising the lift plate.

A discharge unit includes a first discharge guide which guides the sheet conveyed by the conveyance guide, a second discharge guide which includes the discharge opening, and guides the sheet guided by the first discharge guide toward the discharge tray, and a discharge roller and a discharge pinch roller which are provided in the second discharge guide. The first discharge guide is rotatable around a first axis which is parallel with an axial direction of the discharge roller. The second discharge guide is connected to the first discharge guide to be rotatable around a second axis which is parallel with the first axis. An angle at which the second discharge guide is inclined with respect to a sheet supporting surface in the discharge tray is constant while the discharge unit is moving from the third position up to the fourth position.

A discharge unit includes a first discharge guide which guides the sheet conveyed by the conveyance guide, a second discharge guide which includes the discharge opening, and guides the sheet guided by the first discharge guide toward the discharge tray, and a discharge roller and a discharge pinch roller which are provided in the second discharge guide. The first discharge guide is rotatable around a first axis which is parallel with an axial direction of the discharge roller. The second discharge guide is connected to the first discharge guide to be rotatable around a second axis which is parallel with the first axis. An angle at which the second discharge guide is inclined with respect to a sheet supporting surface in the discharge tray is constant while the discharge unit is moving from the third position up to the fourth position.

An image reading apparatus includes a supply tray which supports sheets and includes a movable plate configured to move in correspondence to reduction in a number of the sheets, a discharge tray which is located below the supply tray; a discharge unit which has a discharge opening for discharging the sheet and moves from a lower position and a higher position in correspondence to reduction in the number of the sheets supported on the supply tray, a controller which controls movements of the movable plate and the discharge unit, and a sheet detection unit which detects whether the sheets supported on the discharge tray is lower than a predetermined height. The controller determines a timing to move the discharge unit from the higher position toward the lower position based on a detection result of the sheet detection unit.

An image reading apparatus includes a supply tray which supports sheets and includes a movable plate configured to move in correspondence to reduction in a number of the sheets, a discharge tray which is located below the supply tray; a discharge unit which has a discharge opening for discharging the sheet and moves from a lower position and a higher position in correspondence to reduction in the number of the sheets supported on the supply tray, a controller which controls movements of the movable plate and the discharge unit, and a sheet detection unit which detects whether the sheets supported on the discharge tray is lower than a predetermined height. The controller determines a timing to move the discharge unit from the higher position toward the lower position based on a detection result of the sheet detection unit.

A paper stacking apparatus according to an embodiment of the present disclosure includes a stacking table, a first sensor, and a hardware processor. The stacking table includes an upper face on which papers are stacked, the stacking table being capable of being elevated and lowered by a drive mechanism. The first sensor is disposed at a first position and configured to detect the upper face of the stacking table or an upper face of stacked objects stacked on the stacking table. The hardware processor is coupled to the drive mechanism and the first sensor. The hardware processor is configured to determine that the stacking table is excessively elevated when an elapsed time after starting to detect the object by the first sensor is at least a first excessive-elevation determination value of time.

A paper stacking apparatus according to an embodiment of the present disclosure includes a stacking table, a first sensor, and a hardware processor. The stacking table includes an upper face on which papers are stacked, the stacking table being capable of being elevated and lowered by a drive mechanism. The first sensor is disposed at a first position and configured to detect the upper face of the stacking table or an upper face of stacked objects stacked on the stacking table. The hardware processor is coupled to the drive mechanism and the first sensor. The hardware processor is configured to determine that the stacking table is excessively elevated when an elapsed time after starting to detect the object by the first sensor is at least a first excessive-elevation determination value of time.

A sheet transport device includes a sheet load tray on which a sheet is loaded, a detector that detects whether or not the sheet exists on the sheet load tray, a feeder that feeds the sheet one-by-one from the sheet load tray, and a sheet-load-tray ascend-descend unit that moves the sheet in a sheet loading direction to set an uppermost sheet at a sheet feed position of the feeder, and a controller. In a case where the sheet is detected by the detector, the controller causes the sheet load tray to ascend or descend before the feeder starts to feed the sheet so that ascending-descending operation for moving the sheet load tray between the sheet feed position and a descent position located below the sheet feed position is performed at least once.

A sheet transport device includes a sheet load tray on which a sheet is loaded, a detector that detects whether or not the sheet exists on the sheet load tray, a feeder that feeds the sheet one-by-one from the sheet load tray, and a sheet-load-tray ascend-descend unit that moves the sheet in a sheet loading direction to set an uppermost sheet at a sheet feed position of the feeder, and a controller. In a case where the sheet is detected by the detector, the controller causes the sheet load tray to ascend or descend before the feeder starts to feed the sheet so that ascending-descending operation for moving the sheet load tray between the sheet feed position and a descent position located below the sheet feed position is performed at least once.