| 摘要 |
A paper discharge device includes: an end fence to restrict leading end positions of paper sheets discharged to a paper receiving tray; a lift mechanism to lower the paper receiving tray by a prescribed distance upon reach of a top surface position of the paper sheets stacked on the paper receiving tray to a reference position; an ultrasonic sensor to emit an ultrasonic wave in a horizontal direction toward the paper receiving tray from upstream of the paper receiving tray in a discharge direction in a prescribed height range including the reference position and portions above and below the reference position, and receive a reflected wave from a detection target; and a detector to detect the top surface position on a basis of changes in a reception level of the reflected wave over an elapsed time from an emission of the ultrasonic wave. |
