The vertical stack of trays in a movable tray sorter for sheets of paper exiting a copies is moved in a manner to enlarge the spacing between consecutive pairs of the trays to accept consecutive sheets of paper by moving the trays along a pair of helical coils, each of which has a turn of relatively...http://www.google.fr/patents/US5351947?utm_source=gb-gplus-shareBrevet US5351947 - Sheet sorting apparatus
