Motion picture film projectors

Claim 1

A FILM PROJECTOR, OPERABLE AT NORMAL PROJECTION SPEED OR AT SLOW MOTION SPEED, COMPRISING, IN COMBINATION, A FIRST SHAFT; DRIVING MEANS ROTATING SAID FIRST SHAFT AT A FIRST SUBSTANTIALLY CONSTANT SPEED; A SECOND SHAFT; MEANS DRIVINGLY INTERCONNECTING SAID FIRST AND SECOND SHAFTS FOR ROTATION OF SAID SECOND SHAFT BY SAID FIRST SHAFT AT A SECOND SUBSTANTIALLY CONSTANT SPEED DIFFERING FROM AND HAVING A FIXED RATIO TO SAID FIRST CONSTANT SPEED, WHEREBY SAID FIRST AND SECOND SHAFTS ARE IN ANGULAR COINCIDENCE ONCE DURING EACH NUMBER OF REVOLUTIONS OF SAID FIRST SHAFT EQUAL TO SAID RATIO; A SHUTTER FIXEDLY INTERCONNECTED TO SAID FIRST SHAFT FOR CONSTANT OPERATION IN SYNCHRONISM THEREWITH AT SAID FIRST SUBSTANTIALLY CONSTANT SPEED; INTERMITTENT FILM ADVANCING MECHANISM OPERABLE TO ADVANCE THE FILM, AND SELECTIVELY CONTROLLED, AS TO SPEED OF FILM ADVANCE, BY EITHER SAID FIRST SHAFT OR SAID SECOND SHAFT; SELECTOR MEANS SELECTIVELY OPERABLE TO SHIFT THE CONTROL OF SAID FILM ADVANCING MEANS BETWEEN SAID FIRST SHAFT AND SAID SECOND SHAFT; ELECTRICALLY OPERABLE MEANS EFFECTIVE, WHEN ENERGIZED, TO OPERATE SAID SELECTOR MEANS TO SHIFT CONTROL OF SAID FILM ADVANCING MECHANISM FROM SAID SECOND SHAFT TO SAID FIRST SHAFT; AN ENERGIZING CIRCUIT FOR SAID ELECTRICALLY OPERABLE MEANS; A CONTROL CIRCUIT FOR SAID ENERGIZING CIRCUIT INCLUDING A NORMALLY OPEN SWITCH MEANS CONTROLLING SAID ENERGIZING CIRCUIT; AND CAM MEANS FIXED TO SAID SECOND SHAFT AND CLOSING SAID NORMALLY OPEN SWITCH MEANS ONCE DURING EACH REVOLUTION OF SAID SECOND SHAFT, WHEN SAID FIRST AND SECOND SHAFTS ARE IN SUCH ANGULAR COINCIDENCE.