Wideband frequency compensation system in a sound motion picture projector

Claim 2

In combination with a motion picture projector having a projection station, film drive means located at said projection station for intermittently advancing a strip of film through said projection station to facilitate the projection of images on the film, and transducer means at a playback station spaced from said projection station for reproducing a constant frequency reference signal and an audio signal recorded on the film, motion damping means located between Said projection station and said playback station and adapted to engage a strip of film passing between said station for converting the intermittent motion of the film produced by said film drive means at said projection station into a relatively uniform but varying film motion at said playback station, storage means, sampling means responsive to a reference signal reproduced by said transducer means for storing samples of an audio signal reproduced by said transducer means in said storage means at a rate determined by the frequency of the reproduced reference signal, an audio output terminal, and output signal producing means for applying samples from said storage means to said output terminal at a rate determined by the average rate at which the reference signal is reproduced over a period that is long with respect to the average interval between the storage of samples in said storage means.

Claim 3

The apparatus of claim 1, further comprising means for holding a strip of film in tension along a path through said playback station and said projection station as the film is incrementally advanced by said drive means, and in which said motion damping means comprises resiliently biased film engaging means for applying a force to the film with a component normal to said path to vary the length of film between said playback station and said projection station.

Claim 4

The apparatus of claim 1, in which said storage means comprises an analog-to-digital converter having digital output terminals and an analog input terminal connected to said transducer means to receive a reproduced audio signal, a set of digital storage registers interconnected as a shift register, and a digital-to-analog converter having digital input terminals and an analog output terminal connected to said audio output terminal, said shift register having an output stage comprising one of said storage registers toward which the contents of said other registers are sequentially shifted upon the application of shift pulses to said shift register, said output stage being connected to said digital input terminals, said sampling means comprising gating means controlled by the contents of said shift register and responsive to a reference signal reproduced by said transducer means for connecting said digital output terminals to the nearest vacant stage of said shift register to said output stage as long as any of said stages is vacant, at a rate determined by the rate at which said reference signal was recorded, and said output signal producing means comprising means for applying shift pulses to said shift register.

Claim 5

The apparatus of claim 1, in which said film drive means comprises an intermittent film engaging element driven by a variable speed motor, and further comprising sensing means controlled by said sampling means and said output signal producing means for adjusting the speed of said motor to decrease any difference between the average rates of storing samples and applying the stored samples to said output terminal.

Claim 6

The apparatus of claim 1, in which said storage means comprises first and second shift registers, each having an input stage and an output stage, said sampling means comprising means for applying an information signal reproduced by said transducer means to said input stage of said first shift register and means for shifting the contents of said first shift register from stage to stage at a rate determined by the frequency of a reference signal reproduced by said transducer means, and said output signal producing means comprising means for shifting the contents of said second shift register from stage to stage at a rate determined by the rate at which the reference signal was recorded, means for transferring the contents of said first shift register to said second shift register each time said second shift register has been shifted once for each stage, and means for connecting said output stage of said second shift register to said audio output terminal.

Claim 7

The apparatus of claim 1, furtheR comprising integrating means controlled by said sampling means and said output signal producing means for producing a control signal in accordance with the average difference between said rates, and means responsive to said control signal for adjusting said output signal producing means to bring the rate at which samples are applied to said audio output terminal toward said average.

Claim 8

The apparatus of claim 6, in which said film drive means comprises a variable speed motor and means driven by said motor for intermittently advancing film at a rate determined by the speed of said motor, and further comprising means controlled by said sampling means and said output signal producing means for controlling the speed of said motor to reduce the difference between the rate at which samples are stored in said storage means and the rate at which samples are applied to said audio output terminal.

Claim 9

A sound motion picture projection system, comprising means forming a projection station at a first location, means forming a playback station comprising transducer means adapted to reproduce an audio signal at a second location spaced from said first location, means for mounting a strip of motion picture film on which a series of photographic images, an accompanying sound signal, and a pilot signal are recorded for movement along a path between said projection station and said playback station, incremental drive means at said projection station for incrementally moving a strip of film along said path, means located along said path between said projection station and said playback station for damping accelerations of film moving along said path to produce a relatively uniform film speed at said playback station when the film is moved incrementally past said playback station, means controlled by said transducer means for simultaneously reproducing separate sound and pilot signals from a strip of film moving past said playback station, means for storing samples of the reproduced sound signal at a rate determined by the frequency of said reproduced pilot signal, a loudspeaker, and means for applying stored samples from said storage means to said loudspeaker in the order in which they were stored at a second rate, and means effective when the number of samples stored exceeds the number of samples applied to said loudspeaker by a predetermined number for omitting a sample from said storage means.

Claim 10

A sound motion picture projection system, comprising means forming a projection station at a first location, means forming a playback station comprising transducer means adapted to reproduce an audio signal at a second location spaced from said first location, means for mounting a strip of motion picture film on which a series of photographic images, an accompanying sound signal, and a pilot signal are recorded for movement along a path between said projection station and said playback station, incremental drive means at said projection station for incrementally moving a strip of film along said path, means located along said path between said projection station and said playback station for damping accelerations of film moving along said path to produce a relatively uniform film speed at said playback station when the film is moved incrementally past said playback station, means controlled by said transducer means for simultaneously reproducing separate sound and pilot signals from a strip of film moving past said playback station, means for storing samples of the reproduced sound signal at a rate determined by the frequency of said reproduced pilot signal, a loudspeaker, and means for applying stored samples from said storage means to said loudspeaker in the order in which they were stored at a second rate, and means effective when the number of samples stored exceeds the number of samples applied to said loudspeaker by a predetermined number for omitting a sample from said storage means.

Claim 11

Apparatus for reproducing a motion picture and an accompanying sound signal recorded on a strip of film simultaneously with a constant frequency pilot signal, comprising transducer means for simultaneously reproducing the sound signal and the pilot signal when the strip is moved past said transducer means, said signals being reproduced at frequencies dependent on the speed of said movement, projection means spaced from said transducer means for projecting optical images from images on the film when the film is incrementally moved past said projection means, film receiving means for mounting the film for movement past said transducer means and said projection means, film drive means adjacent said projection means and adapted to engage a strip of film mounted on said receiving means to incrementally advance the film past said projection means, motion damping means mounted between said transducer means and said projection means and adapted to engage a strip of film mounted on said receiving means to damp changes in the speed of the film past said transducer means when the film is incrementally advanced by said drive means, storage means responsive to said reproduced pilot signal for storing samples of said reproduced information signal at a first rate determined by the frequency of said reproduced pilot signal, a loudspeaker, means for applying samples from said storage means to said loudspeaker at a second rate determined by the average frequency at which said pilot signal is reproduced over a predetermined period, and means effective when said memory is filled to capacity for rejecting a saMple.

Claim 12

Apparatus for reproducing a motion picture and an accompanying sound signal recorded on a strip of film simultaneously with a constant frequency pilot signal, comprising transducer means for simultaneously reproducing the sound signal and the pilot signal when the strip is moved past said transducer means, said signals being reproduced at frequencies dependent on the speed of said movement, projection means spaced from said transducer means for projecting optical images from images on the film when the film is incrementally moved past said projection means, film receiving means for mounting the film for movement past said transducer means and said projection means, film drive means adjacent said projection means and adapted to engage a strip of film mounted on said receiving means to incrementally advance the film past said projection means, motion damping means mounted between said transducer means and said projection means and adapted to engage a strip of film mounted on said receiving means to damp changes in the speed of the film past said transducer means when the film is incrementally advanced by said drive means, storage means responsive to said reproduced pilot signal for storing samples of said reproduced information signal at a first rate determined by the frequency of said reproduced pilot signal, a loudspeaker, means for applying samples from said storage means to said loudspeaker at a second rate determined by the average frequency at which said pilot signal is reproduced over a predetermined period, and means effective when said memory is filled to capacity for rejecting a saMple.

Claim 13

In a sound motion picture projector, film support means for supporting a strip of film on which photographic images, an audio information signal, and a pilot signal have been synchronously recorded for movement back and forth along a path between a playback station and a projection station, film drive means adjacent said projection station for incrementally advancing a strip of film supported by said support means past said projection station, projection means adjacent said projection station for projecting the images recorded on the film, motion damping means located between said stations and adapted to engage a strip of film supported by said support means to produce a film speed past said playback station in accordance with the average speed of the film past said projection station when the film is incrementally advanced by said drive means, transducer means located at said playback station for simultaneously reproducing the information signal and the pilot signal from a strip of film moving past said playback station, storage means controlled by said transducer means for storing samples of the reproduced information signal at a first rate dependent on the frequency of the reproduced pilot signal, speaker means, means for supplying samples from said storage means to said speaker in the order in which they were stored and at a second rate dependent on the average of said first rate over a period that is long compared to the intervals between the storage of samples in said first means, and means responsive to a predetermined excess of samples applied to said storage means over samples supplied to said speaker for rejecting a sample from said storage means.

Claim 14

In a sound motion picture projector, film support means for supporting a strip of film on which photographic images, an audio information signal, and a pilot signal have been synchronously recorded for movement back and forth along a path between a playback station and a projection station, film drive means adjacent said projection station for incrementally advancing a strip of film supported by said support means past said projection station, projection means adjacent said projection station for projecting the images recorded on the film, motion damping means located between said stations and adapted to engage a strip of film supported by said support means to produce a film speed past said playback station in accordance with the average speed of the film past said projection station when the film is incrementally advanced by said drive means, transducer means located at said playback station for simultaneously reproducing the information signal and the pilot signal from a strip of film moving past said playback station, storage means controlled by said transducer means for storing samples of the reproduced information signal at a first rate dependent on the frequency of the reproduced pilot signal, speaker means, means for supplying samples from said storage means to said speaker in the order in which they were stored and at a second rate dependent on the average of said first rate over a period that is long compared to the intervals between the storage of samples in said first means, and means responsive to a predetermined excess of samples applied to said storage means over samples supplied to said speaker for rejecting a sample from said storage means.

Claim 15

A sound motion picture projection system, comprising means forming a projection station at a first location, means forming a playback station comprising transducer means adapted to reproduce an audio signal at a second location spaced from said first location, means for mounting a strip of motion picture film on which a series of photographic images, an accompanying sound signal, and a pilot signal are recorded for movement along a path between said projection station and said playback station, incremental drive means at said projection station for incrementally moving a strip of film along said path, means located along said path between said projection station and said playback station for damping accelerations of film moving along said path to produce a relatively uniform film speed at said playback station when the film is moved incrementally past said playback station, means controlled by said transducer means for simultaneously reproducing separate sound and pilot signals from a strip of film moving past said playback station, means for storing samples of the reproduced sound signal at a rate determined by the frequency of said reproduced pilot signal, a loudspeaker, and means for applying stored samples from said storage means to said loudspeaker in the order in which they were stored at an adjustable rate, and means responsive to the average difference between the rates at which said samples are stored and applied to said loudspeaker to control said adjustable rate to reduce said average difference.

Claim 16

A sound motion picture projection system, comprising means forming a projection station at a first location, means forming a playback station comprising transducer means adapted to reproduce an audio signal at a second location spaced from said first location, means for mounting a strip of motion picture film on which a series of photographic images, an accompanying sound signal, and a pilot signal are recorded for movement along a path between said projection station and said playback station, incremental drive means at said projection station for incrementally moving a strip of film along said path, means located along said path between said projection station and said playback station for damping accelerations of film moving along said path to produce a relatively uniform film speed at said playback station when the film is moved incrementally past said playback station, means controlled by said transducer means for simultaneously reproducing separate sound and pilot signals from a strip of film moving past said playback station, means for storing samples of the reproduced sound signal at a rate determined by the frequency of said reproduced pilot signal, a loudspeaker, and means for applying stored samples from said storage means to said loudspeaker in the order in which they were stored at an adjustable rate, and means responsive to the average difference between the rates at which said samples are stored and applied to said loudspeaker to control said adjustable rate to reduce said average difference.

Claim 17

Apparatus for reproducing a motion picture and an accompanying sound signal recorded on a strip of film simultaneously with a constant frequency pilot signal, comprising transducer means for simultaneously reproducing the sound signal and the pilot signal when the strip is moved past said transducer means, said signals being reproduced at frequencies dependent on the speed of said movement, projection means spaced from said transducer means for projecting optical images from images on the film when the film is incrementally moved past said projection means, film receiving means for mounting the film for movement past said transducer means and said projection means, film drive means adjacent said projection means and adapted to engage a strip of film mounted on said receiving means to incrementally aDvance the film past said projection means, motion damping means mounted between said transducer means and said projection means and adapted to engage a strip of film mounted on said receiving means to damp changes in the speed of the film past said transducer means when the film is incrementally advanced by said drive means, storage means responsive to said reproduced pilot signal for storing samples of said reproduced information signal at a first rate determined by the frequency of said reproduced pilot signal, a loudspeaker, adjustable means for applying samples from said storage means to said loudspeaker at a second rate, and integrating means responsive to the average difference between said rates to adjust said adjustable means to reduce said average difference.

Claim 18

Apparatus for reproducing a motion picture and an accompanying sound signal recorded on a strip of film simultaneously with a constant frequency pilot signal, comprising transducer means for simultaneously reproducing the sound signal and the pilot signal when the strip is moved past said transducer means, said signals being reproduced at frequencies dependent on the speed of said movement, projection means spaced from said transducer means for projecting optical images from images on the film when the film is incrementally moved past said projection means, film receiving means for mounting the film for movement past said transducer means and said projection means, film drive means adjacent said projection means and adapted to engage a strip of film mounted on said receiving means to incrementally aDvance the film past said projection means, motion damping means mounted between said transducer means and said projection means and adapted to engage a strip of film mounted on said receiving means to damp changes in the speed of the film past said transducer means when the film is incrementally advanced by said drive means, storage means responsive to said reproduced pilot signal for storing samples of said reproduced information signal at a first rate determined by the frequency of said reproduced pilot signal, a loudspeaker, adjustable means for applying samples from said storage means to said loudspeaker at a second rate, and integrating means responsive to the average difference between said rates to adjust said adjustable means to reduce said average difference.

Claim 19

In a sound motion picture projector, film support means for supporting a strip of film on which photographic images, an audio information signal, and a pilot signal have been synchronously recorded for movement back and forth along a path between a playback station and a projection station, film drive means adjacent said projection station for incrementally advancing a strip of film supported by said support means past said projection station, projection means adjacent said projection station for projecting the images recorded on the film, motion damping means located between said stations and adapted to engage a strip of film supported by said support means to produce a film speed past said playback station in accordance with the average speed of the film past said projection station when the film is incrementally advanced by said drive means, transducer means located at said playback station for simultaneously reproducing the information signal and the pilot signal from a strip of film moving past said playback station, storage means controlled by said transducer means for storing samples of the reproduced information signal at a first rate dependent on the frequency of the reproduced pilot signal, speaker means, adjustable means for supplying samples from said storage means to said speaker means in the order in which they were stored and at a second rate variable about the frequency at which the pilot signal was recorded, and integrating means responsive to the average difference between said rates for adjusting said adjustable means to reduce said difference.

Claim 20

In a sound motion picture projector, film support means for supporting a strip of film on which photographic images, an audio information signal, and a pilot signal have been synchronously recorded for movement back and forth along a path between a playback station and a projection station, film drive means adjacent said projection station for incrementally advancing a strip of film supported by said support means past said projection station, projection means adjacent said projection station for projecting the images recorded on the film, motion damping means located between said stations and adapted to engage a strip of film supported by said support means to produce a film speed past said playback station in accordance with the average speed of the film past said projection station when the film is incrementally advanced by said drive means, transducer means located at said playback station for simultaneously reproducing the information signal and the pilot signal from a strip of film moving past said playback station, storage means controlled by said transducer means for storing samples of the reproduced information signal at a first rate dependent on the frequency of the reproduced pilot signal, speaker means, adjustable means for supplying samples from said storage means to said speaker means in the order in which they were stored and at a second rate variable about the frequency at which the pilot signal was recorded, and integrating means responsive to the average difference between said rates for adjusting said adjustable means to reduce said difference.

Claim 21

In combination with a motion picture projector comprising projection means for projecting images from a strip of film incrementally moving past said projection means, transducer means located in spaced relation to said projection means for simultaneously reproducing an audio signal and a pilot signal recorded on a strip of film moved past said transducer means, and means mounted adjacent said projection means for incrementally advancing a strip of film past said projection means, motion damping means located between said projection means and said transducer means for smoothing the speed of film moving between said transducer means and said projection means, storage means controlled by said transducer means for storing samples of the reproduced audio signal at a rate determined by the frequency of the reproduced pilot signal, a speaker, a variable frequency oscillator, means controlled by said oscillator for supplying stored samples from said storage means to said speaker at a rate determined by the frequency of said oscillator, integrating means for detecting the average difference between the rates at which samples are stored and the rate at which samples are supplied to said speaker, and means controlled by said detecting means for varying the frequency of said oscillator to reduce said average difference.

Claim 22

In combination with a motion picture projector comprising projection means for projecting images from a strip of film incrementally moving past said projection means, transducer means located in spaced relation to said projection means for simultaneously reproducing an audio signal and a pilot signal recorded on a strip of film moved past said transducer means, and means mounted adjacent said projection means for incrementally advancing a strip of film past said projection means, motion damping means located between said projection means and said transducer means for smoothing the speed of film moving between said transducer means and said projection means, storage means controlled by said transducer means for storing samples of the reproduced audio signal at a rate determined by the frequency of the reproduced pilot signal, a speaker, a variable frequency oscillator, means controlled by said oscillator for supplying stored samples from said storage means to said speaker at a rate determined by the frequency of said oscillator, integrating means for detecting the average difference between the rates at which samples are stored and the rate at which samples are supplied to said speaker, and means controlled by said detecting means for varying the frequency of said oscillator to reduce said average difference.

Claim 23

A sound motion picture projection system, comprising means forming a projection station at a first location, means forming a playback station comprising transducer means adapted to reproduce an audio signal at a second location spaced from said first location, means for mounting a strip of motion picture film on which a series of photographic images, an accompanying sound signal, and a pilot signal are recorded for movement along a path between said projection station and said playback station, incremental drive means at said projection station for incrementally moving a strip of film along said path, means located along said path between said projection station and said playback station for damping accelerations of film moving along said path to produce a relatively uniform film speed at said playback station when the film is moved incrementally past said playback station, means controlled by said transducer means for simultaneously reproducing separate sound and pilot signals from a strip of film moving past said playback station, means for storing samples of the reproduced sound signal at a rate determined by the frequency of said reproduced pilot signal, a loudspeaker, and means for applying stored samples from said storage means to said loudspeaker in the order in which they were stored at a fixed rate.

Claim 24

A sound motion picture projection system, comprising means forming a projection station at a first location, means forming a playback station comprising transducer means adapted to reproduce an audio signal at a second location spaced from said first location, means for mounting a strip of motion picture film on which a series of photographic images, an accompanying sound signal, and a pilot signal are recorded for movement along a path between said projection station and said playback station, incremental drive means at said projection station for incrementally moving a strip of film along said path, means located along said path between said projection station and said playback station for damping accelerations of film moving along said path to produce a relatively uniform film speed at said playback station when the film is moved incrementally past said playback station, means controlled by said transducer means for simultaneously reproducing separate sound and pilot signals from a strip of film moving past said playback station, means for storing samples of the reproduced sound signal at a rate determined by the frequency of said reproduced pilot signal, a loudspeaker, and means for applying stored samples from said storage means to said loudspeaker in the order in which they were stored at a fixed rate.

Claim 25

Apparatus for reproducing a motion picture and an accompanying sound signal recorded on a strip of film simultaneously with a constant frequency pilot signal, comprising transducer means for simultaneously reproducing the sound signal and the pilot signal when the strip is moved past said transducer means, said signals being reproduced at frequencies dependent on the speed of said movement, projection means spaced from said transducer means for projecting optical images from images on the film when the film is incrementally moved past said projection means, film receiving means for mounting the film for movement past said transducer means and said projection means, film drive means adjacent said projection means and adapted to engage a strip of film mounted on said receiving means to incrementally advance the film past said projection means, motion damping means mounted between said transducer means and said projection means and adapted to engage a strip of film mounted on said receiving means to damp changes in the speed of the film past said transducer means when the film is incrementally advanced by said drive means, storage means responsive to said reproduced pilot signal for storing samples of said reproduced information signal at a first rate determined by the frequency of said reproduced pilot signal, a loudspeaker, and means for applying samples from said storage means to said loudspeaker at a rate determined by the frequency at which said pilot signal was recorded.

Claim 26

Apparatus for reproducing a motion picture and an accompanying sound signal recorded on a strip of film simultaneously with a constant frequency pilot signal, comprising transducer means for simultaneously reproducing the sound signal and the pilot signal when the strip is moved past said transducer means, said signals being reproduced at frequencies dependent on the speed of said movement, projection means spaced from said transducer means for projecting optical images from images on the film when the film is incrementally moved past said projection means, film receiving means for mounting the film for movement past said transducer means and said projection means, film drive means adjacent said projection means and adapted to engage a strip of film mounted on said receiving means to incrementally advance the film past said projection means, motion damping means mounted between said transducer means and said projection means and adapted to engage a strip of film mounted on said receiving means to damp changes in the speed of the film past said transducer means when the film is incrementally advanced by said drive means, storage means responsive to said reproduced pilot signal for storing samples of said reproduced information signal at a first rate determined by the frequency of said reproduced pilot signal, a loudspeaker, and means for applying samples from said storage means to said loudspeaker at a rate determined by the frequency at which said pilot signal was recorded.

Claim 27

In a sound motion picture projector, film support means for supporting a strip of film on which photographic images, an audio information signal, and a pilot signal have been synchronously recorded for movement back and forth along a path between a playback station and a projection station, film drive means adjacent said projection station for incrementally advancing a strip of film supported by said support means past said projection station, projection means adjacent said projection station for projecting the images recorded on the film, motion damping means located between said stations and adapted to engage a strip of film supported by said support means to produce a film speed past said playback station in accordance with the average speed of the film past said projection station when the film is incrementally advanced by said drive means, transducer means located at said playback station for simultaneously reproducing the information signal and the pilot signal from a strip of film moving past said playback station, storage means controlled by said transducer means for storing samples of the reproduced information signal at a rate dependent on the frequency of the reproduced pilot signal, speaker means, and means for supplying samples from said storage means to said speaker in the order in which they were stored and at a rate dependent on the frequency at which the pilot signal was recorded.

Claim 28

In a sound motion picture projector, film support means for supporting a strip of film on which photographic images, an audio information signal, and a pilot signal have been synchronously recorded for movement back and forth along a path between a playback station and a projection station, film drive means adjacent said projection station for incrementally advancing a strip of film supported by said support means past said projection station, projection means adjacent said projection station for projecting the images recorded on the film, motion damping means located between said stations and adapted to engage a strip of film supported by said support means to produce a film speed past said playback station in accordance with the average speed of the film past said projection station when the film is incrementally advanced by said drive means, transducer means located at said playback station for simultaneously reproducing the information signal and the pilot signal from a strip of film moving past said playback station, storage means controlled by said transducer means for storing samples of the reproduced information signal at a rate dependent on the frequency of the reproduced pilot signal, speaker means, and means for supplying samples from said storage means to said speaker in the order in which they were stored and at a rate dependent on the frequency at which the pilot signal was recorded.

Claim 29

In combination with a motion picture projector comprising projection means for projecting imAges from a strip of film incrementally moving past said projection means, transducer means located in spaced relation to said projection means for simultaneously reproducing an audio signal and a pilot signal recorded on a strip of film moved past said transducer means, and means mounted adjacent said projection means for incrementally advancing a strip of film past said projection means, motion damping means located between said projection means and said transducer means for smoothing the speed of film moving between said transducer means and said projection means, storage means controlled by said transducer means for storing samples of the reproduced audio signal at a rate determined by the frequency of the reproduced pilot signal, a speaker, and means for supplying stored samples from said storage means to said speaker at a rate determined by the frequency at which the pilot signal was recorded.

Claim 30

In combination with a motion picture projector comprising projection means for projecting imAges from a strip of film incrementally moving past said projection means, transducer means located in spaced relation to said projection means for simultaneously reproducing an audio signal and a pilot signal recorded on a strip of film moved past said transducer means, and means mounted adjacent said projection means for incrementally advancing a strip of film past said projection means, motion damping means located between said projection means and said transducer means for smoothing the speed of film moving between said transducer means and said projection means, storage means controlled by said transducer means for storing samples of the reproduced audio signal at a rate determined by the frequency of the reproduced pilot signal, a speaker, and means for supplying stored samples from said storage means to said speaker at a rate determined by the frequency at which the pilot signal was recorded.