Patent ID: 9346649
Filing Date: 2016-05-24
CPC Classification: B65H

Claim Text:
1. A finisher comprising: an ejection port from which sheets of paper are ejected; a stacking tray on which the sheets of paper ejected from the ejection port are stacked; a light-emitting element configured to emit light to the top sheet of a paper stack on the stacking tray; a light-receiving element configured to receive light that is emitted from the light-emitting element and then reflected off the top sheet of the paper stack on the stacking tray; a communication section configured to perform data communication with an image forming apparatus and acquires a coverage rate of a side of the top sheet of the paper stack on the stacking tray, the side being exposed to light emitted from the light-emitting element; and a paper-amount determination section configured to determine whether or not the amount of paper stacked on the stacking tray exceeds a predetermined allowable stack capacity of the stacking tray by comparing a predetermined threshold value with an amount of light received by the light-receiving element, wherein the paper-amount determination section corrects the threshold value by using the coverage rate acquired by the communication section, compares the corrected threshold value with the amount of light received by the light-receiving element, and determines that the amount of paper stacked on the stacking tray exceeds the allowable stack capacity of the stacking tray if the light amount is equal to or greater than the corrected threshold value.