Patent ID: 8342512

Claim:
A pick up device for paper sheets, comprising: an input unit configured to support a plurality of paper sheets in a stacked manner; a supply mechanism configured to move the plurality of placed paper sheets in a stacking direction and supply each paper sheet to an pick up position on the input unit; a pick up mechanism configured to pick up the paper sheet at the pick up position from the input unit one by one; a transfer mechanism configured to transfer the paper sheets picked up by the pick up mechanism along a convey path; a thickness detector configured to detect a thickness of each paper sheet picked up by the pick up mechanism; a paper sheet sensor configured to detect a density state of the paper sheets on an upstream side of the pick up position; and a control unit configured to determine a supply speed or a feed amount of the paper sheets by the supply mechanism in accordance with thickness information per unit time of the picked up paper sheets obtained from the thickness detector, and configured to determine whether the supply mechanism is to be operated or stopped based on density information of the paper sheets obtained from the paper sheet sensor, wherein the control unit is further configured to calculate an average value of thicknesses per unit time obtained by the thickness detector, to decrease the supply speed when the average value is lower than a predetermined reference value, and to increase the supply speed when the average value is higher than the predetermined reference speed.