Sprocketed film transport

In a film transport wherein sound film with sprocket holes is moved between a supply hub and take-up hub past a readout station by the use of a single main sprocket wheel which moves the sound film in an arc of the reader station, the improvement of a sprocket wheel drive comprising:

• a stepping motor which advances its armature by a predetermined fractional revolution for each input pulse, said armature directly connected to the sprocket wheel to rotate the sprocket wheel at the same speed as the armature;
• a flywheel;
• a friction clutch coupling the flywheel to the armature;
• and
• energizing means for applying pulses at predetermined rates to said stepping motor,
• said energizing means being selectively operable to transport film incrementally or continuously, said flywheel being operable during continuous film transport to eliminate any deviations from uniform linear film motion.

In a system for recording sound on a film, the improvement comprising:

• a rotatably mounted wheel;
• means for guiding the film in wrap partially about the wheel;
• first and second sound heads mounted inside said wheel within the arc of the film path portion which wraps about the wheel, said heads spaced from each other circumferentially about the axis of rotation of the wheel;
• means for driving said wheel including
• a stepping motor which advances its armature by a predetermined fractional revolution for each input pulse, said armature being directly connected to said wheel to rotate the wheel at the same speed as the armature;
• a flywheel;
• a friction clutch coupling the flywheel to the armature, for reducing irregularities in armature movement at constant speed operation while facilitating starting of the motor;
• and
• energizing means for applying pulses at predetermined rates to said motor,
• whereby said wheel is capable of alternatively moving film in increments of motion and continuously without irregularities.

Apparatus for mixing and editing sprocketed motion picture and sound film comprising:

• a machine frame;
• a first pair of hubs rotatably mounted on said frame adapted to receive sprocketed motion picture film;
• a second pair of hubs rotatably mounted on said frame adapted to receive a sprocketed sound film;
• first and second sprocket wheels rotatably mounted on said frame;
• first means for guiding motion picture film from around a first hub of said first hub pair, partially about said first sprocket wheel, and thence around the other hub of said first hub pair;
• a prism positioned coaxially with said first sprocket wheel;
• means for shining light through a motion picture film portion wrapped about said first sprocket wheel and through said prism;
• second means for guiding sound film from around a first hub of said second hub pair, partially about said second sprocket wheel, and thence around the other hub of said second hub pair;
• at least a read transducer positioned within said second sprocket wheel within the arc of the second film path portion which partially wraps around said second sprocket wheel;
• means for shining light through a film portion wrapped about the sprocket wheel and through the prism;
• first and second motor means respectively coupled to said first and second sprocket wheel, each of said motor means including a stepping motor having a shaft directly connected to a sprocket wheel to rotate it at the same speed as said motor shaft, a flywheel, and a clutch frictionally coupling said flywheel to said motor shaft to permit slippage between them so that each stepping motor can suddenly start without suddenly rotating its flywheel while allowing its flywheel to minimize stepping motion of said shaft after shaft is at full speed;
• and
• synchronizing means for driving said first and second motor means from a common source to maintain the picture film and sound film in a predetermined synchronized