Intermittent rotary motion device

In a film strip projector including a projector aperture for framing the film to be projected and an output drive shaft for driving the film strip through the projector, a film strip drive means, comprising:

• a rotatable drive gear having two segmental arcuate toothed portions on the periphery, clearance means adjacent the end of said toothed portions, said clearance means including a detent formed adjacent each end of the segmented arcuate toothed portions, and a generally cylindrical surface about the remaining periphery of the drive gear;
• drive means connected to said drive gear for rotating the drive gear;
• a driven gear including a plurality of arcuate toothed portions spaced apart by a cam locking means, said cam locking means including a pair of spaced apart protrusions for engaging the cylindrical surface of the drive gear, the engaging protrusions protruding radially outwardly a greater distance than the gear teeth on the toothed portions of the drive gear, said toothed portions engaging the toothed portions of the rotatable drive gear and said protrusions engaging said clearance means for positive movement of the cam locking means into engagement with said cylindrical surface of the drive gear whereby rotation of the drive gear by the drive means causes the toothed portions of said drive gear to sequentially engage one of the toothed portions of said driven gear and cause rotation thereof to a predetermined angle whereafter the protrusions of the next adjacent cam locking means engage the cylindrical surface of the drive gear to prevent rotational movement of the driven gear during the period that the cam locking means engages the cylindrical surface of the drive gear, said driven gear being connected to the film strip output drive shaft to sequentially drive the film strip, frame by frame, through the film strip projector.

An intermittent rotary motion device, comprising:

• a rotatable drive gear having at least one segmental arcuate toothed portion about its periphery, a cylindrical surface substantially about the remaining periphery of the gear and a detent formed in the cylindrical surface adjacent each end of the segmental arcuate toothed portion, said detents protruding radially inwardly a greater distance than the root diameter of the toothed portion;
• drive means drivingly connected to said drive gear;
• and
• a driven gear including a plurality of arcuate toothed portions each of which is spaced apart by a cam locking means for engagement with the cylindrical surface of said drive gear to provide lost motion therebetween, said cam locking means including a pair of spaced apart arcuate tip portions for engaging the cylindrical surface of the drive gear, the engaging tip portions protruding radially outwardly a greater distance than the gear teeth on the toothed portions of the driven gear so as to mesh and engage the detents of said drive gear adjacent the toothed portion thereof, whereby continued rotation of the drive gear by the drive means causes the toothed portion of the drive gear to sequentially engage one of the toothed portions of said driven gear to cause rotation thereof through an angle determined by the length of the toothed portions thereof whereafter the arcuate tip portions of the next adjacent cam locking means are driven by the detent to engage the cylindrical surface of the drive gear and prevent rotational movement of the driven gear through the period that the cam locking means engages the drive gear.