Slide projector with slide actuated shutter

Claim 1

IN A SLIDE PROJECTOR, SLIDE-SHIFTING MEANS FOR SHIFTING A SLIDE TO AND FROM A PROJECTING POSITION WHERE A LIGHT BEAM PASSES THROUGH THE SLIDE, LIGHT-BLOCKING MEANS, SUPPORT MEANS SUPPORTING SAID LIGHT-BLOCKING MEANS FOR MOVEMENT BETWEEN A NON-BLOCKING POSITION WHERE SAID LIGHTBLOCKING MEANS DOES NOT BLOCK THE LIGHT BEAM AND A BLOCKING POSITION WHERE SAID LIGHT-BLOCKING MEANS BLOCKS THE LIGHT BEAM TO PREVENT THE LATTER FROM PASSING BEYOND THE PROJECTOR, AND POSITIONING MEANS OPERATIVELY CONNECTED TO SAID LIGHT-BLOCKING MEANS AND RESPONDING ONLY TO MOVEMENT OF A SLIDE TO AND FROM SAID PROJECTING POSITION FOR POSITIONING SAID LIGHT-BLOCKING MEANS IN SAID NON-BLOCKING AND BLOCKING POSITIONS THEREOF, RESPECTIVELY, SO THAT IF SAID SLIDE-SHIFTING MEANS IS ACTUATED WITHOUT A SLIDE SAID LIGHTBLOCKING MEANS WILL REMAIN IN SAID BLOCKING POSITION THEREOF, SAID POSITIONING MEANS NORMALLY POSITIONING SAID LIGHT-BLOCKING MEANS IN SAID BLOCKING POSITION THEREOF AND BEING SITUATED IN THE PATH OF MOVEMENT OF A SLIDE TO SAID PROJECTING POSITION TO BE ENGAGED AND MOVED BY SAID SLIDE FOR DISPLACING SAID LIGHT-BLOCKING MEANS FROM SAID BLOCKING TO SAID NON-BLOCKING POSITION THEREOF DURING MOVEMENT OF A SLIDE INTO SAID PROJECTING POSITION THEREOF, AND SAID POSITIONING MEANS COACTING WITH SAID SLIDE, DURING ENGAGEMENT THEREWITH AND MOVEMENT THEREBY, FOR MOVING WITH BUT NOT WITH RESPECT TO SAID SLIDE TO ELIMINATE RELATIVE MOVEMENT BETWEEN SAID POSITIONING MEANS AND SLIDE WHEN THE LATTER ENGAGES AND MOVES SAID POSITIONING MEANS AND THUS PREVENT RUBBING OF SAID SLIDE DURING ENGAGEMENT THEREOF WITH SAID POSITIONING MEANS.