Abstract: A fully automatic paper sorter designed for use as an accessory to an office copier or copier/duplicator machine. The sorter bins have a concave configuration which takes advantage of paper curl developed in the copier to provide more efficient utilization of available bin space. A speed buffering arrangement permits the sorter to operate with copiers having various speeds of paper movement. A separate paper diverting gate is associated with each paper receiving bin, the gates being activated in succession by a rotating cam stack. A sophisticated paper monitoring and control system detects various types of paper jams, and responds either by shutting down the sorter immediately, or by routing subsequent paper sheets directly to a paper catch tray, depending upon the type of jam involved. When the capacity of the sorter is exceeded, excess sheets are routed to the paper catch tray.