DOUBLE DUTY SENSOR FOR PAPER TRAY ELEVATORS
Original Publication Date: 1984-Apr-30
Included in the Prior Art Database: 2004-Apr-04
Xerox Disclosure Journal
Paddle wheel feeders that require an elevator to maintain paper stack height have a serious drawback. If any mechanical means is used to detect the top of the paper stack, feeding may be impaired or stopped due to the low drive force of the paddle wheel feeder. It is necessary to use an optical sensor to detect the top of the stack. Penetration can be maintained and no drag forces are added to the load of the paddle wheel. The disadvantage of the optical sensor is that if the associated electronics malfunctions, the paper stack may not be recognized by the optical sensor. The elevator would then continue to move the paper stack upward into the optical sensor first and then into the frame and other stationary parts of the feeder. Damage will .probably occur to the optical sensor, elevator parts and feeder parts.