Stacking devices for sheet articles

Claim 1

A MACHINE FOR STACKING OPAQUE FLEXIBLE SHEET ARTICLES, SUCH AS HIDES AND SKINS, COMPRISING A MAIN ENDLESS CONVEYOR WITH A SUBSTANTIALLY FLAT ARTICLE-CARRYING PORTION HAVING A FIRST SIDE AND A SECOND SIDE AND AN OUTLET END, AND BEING AT LEAST IN PART TRANSPARENT TO LIGHT IN THE VICINITY OF SAID OUTLET END, SAID ARTICLES BEING DISPOSED AT RANDOM ON ONE OF SAID FIRST AND SECOND SIDES OF SAID ARTICLE-CARRYING PORTION OF SAID MAIN CONVEYOR TO BE CARRIED THEREBY TOWARDS SAID OUTLET END AT A GIVEN LINEAR SPEED; TWO STATIONARY MAIN LIGHT-EMITTING SURFACES DISPOSED ON THE FIRST SIDE OF SAID ARTICLE-CARRYING PORTION OF SAID MAIN CONVEYOR IN THE VICINITY OF THE OUTLET END THEREOF AND EXTENDING ACROSS THE FULL WIDTH THEREOF SUBSTANTIALLY SYMMETRICALLY WITH RESPECT TO A LINE TRANSVERSE TO SAID ARTICLE-CARRYING PORTION OF SAID MAIN CONVEYOR AND CLOSE TO SAID LINE SO AS TO ILLUMINATE THE ARTICLES CARRIED BY SAME, SAID SURFACES HAVING A SUBSTANTIALLY UNIFORMLY DISTRIBUTED LUMINOSITY AND SAID SURFACES EACH HAVING A DIMENSION LONGITUDINALLY OF SAID ARTICLE-CARRYING PORTION OF SAID MAIN CONVEYOR AT LEAST EQUAL TO HALF THE MAXIMUM LENGTH OF THE ARTICLES TO BE STACKED; TWO MAIN PHOTOELECTRIC CELLS DISPOSED ON THE SECOND SIDE OF SAID ARTICLECARRYING PORTION OF SAID MAIN CONVEYOR, EACH TO RECEIVE LIGHT SUBSTANTIALLY FROM ONE ONLY OF SAID MAIN LIGHTEMITTING SURFACES; COMPARING MEANS TO COMPARE THE VOLTAGES EMITTED BY SAID MAIN PHOTO-ELECTRIC CELLS AND TO DEDUCE FROM SUCH COMPARISON THE PASSAGE ACROSS SAID TRANSVERSE LINE OF THE APPROXIMATE CENTER OF THE SURFACE OF AN ARTICLE CARRIED BY SAID MAIN ARTICLE-CARRYING PORTION OF SAID MAIN CONVEYOR BETWEEN SAID MAIN LIGHT-EMITTING SURFACES AND SAID CELLS; A STACKING SUPPORT DISPOSED IN THE VICINITY OF THE OUTLET END OF SAID ARTICLE-CARRYING PORTION OF SAID MAIN CONVEYOR AND ON WHICH THE ARTICLES CARRIED BY SAID CONVEYOR ARE TO BE STACKED; DEPOSITING MEANS TO RECEIVE THE ARTICLES FROM THE OUTLET END OF SAID ARTICLECARRYING PORTION OF SAID MAIN CONVEYOR AND TO DEPOSIT SAME ON SAID SUPPORT; DRIVING MEANS TO DRIVE SAID DEPOSITING MEANS; AND MEANS TO ACTUATE SAID DRIVING MEANS A PRE-DETERMINED TIME AFTER SAID COMPARING MEANS HAVE DETECTED PASSAGE OF THE APPROXIMATE CENTER OF THE SURFACE OF AN ARTICLE ACROSS SAID TRANSVERSE LINE TO SUBSTANTIALLY REGULARLY STACK SAME ON SAID SUPPORT.