AN APPARATUS FOR DETECTING THE FLATNESS OF A PAPER SHEET

摘要

There is a sorting apparatus for mixed envelopes according to whether or not the envelopes are face-up, and whether or not they are upside-down. Each envelope is carried lengthwise and a parallel light beam is radiated on the envelope from the right and left oblique directions with respect to the carrying direction of the envelope. When the light beam is radiated on the backside of the envelope from the upper side of the envelope, the shadow of the flap is formed on the envelope. Whether or not the envelope is face-up and whether or not the envelope is rightside-up is determined by this shadow detection.