US3832044A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Film loop control system for sound motion pictures
Assignee: POLOROID CORP
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Filing: 1973-06-28
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Granted: 1974-08-27
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Expires: 1993-06-28
Abstract
Abstract A film transport control system for a sound motion picture production and sound editing system, comprising a combined motor and transformer which serves to supply power to the apparatus, including power for the projection lamp, to drive a program control shaft that controls operation of the system for photographic processing, projection and rewinding operations, and to drive an incremental film advance pawl. A DC motor drives a capstan, to move the film at uniform speed past a transducer head, under the control of a photocell illuminated at times by a loop formed in the film between the sound head and the projection drive pawl driven by the combined motor and transformer. The photocell controls the motor through a two stage amplifier comprising two filtering capacitors to provide a long time constant control over the average speed of the capstan to reduce wow and flutter.
Inventors
- 👤 R Deeran
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 11:22
CPC Classifications
G; G03; G03B; G03B31/00; G03B31/02
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
503 words
Film transport and illumination apparatus for a sound motion picture system utilizing strip film on which visual images and a sound track can be recorded, comprising incremental drive means operable to move the film strip past an optical station in increments corresponding to image frames, a capstan operable to move the film past a sound station at a substantially uniform speed dependent on the rate of rotation of said capstan, an induction motor having a stator and an output shaft, means connecting the output shaft of said induction motor to said incremental drive means to operate said drive means at a rate determined by the speed of said shaft, a primary winding on said stator, a secondary winding on said stator, a projection lamp connected in series with at least a portion of one of said windings, means for connecting a source of alternating current to said primary winding, a direct current motor having a winding and an output shaft, speed reduction means drivingly connecting the output shaft of said direct current motor to said capstan, direct current power supply means having first, second and third output terminals and input terminals energized by said secondary winding for producing first and second direct voltages, said first direct voltage being produced between said first and said third output terminals and said second direct voltage being produced between said second and said third input terminals, a first resistor connected in series with the winding of said direct current motor between said first and said third output terminals, a transistor having an emitter and a collector connected in parallel with said resistor, said transistor having a base, a first filter capacitor connected between the base and the collector of said first transistor, a second transistor having a collector, an emitter and a base, the collector and the emitter of said second transistor being connected between said second terminal and the base of said first transistor, a second resistor connected between the base of said second transistor and said third output terminal, a second filter capacitor connected between the base of said second transistor and said second output terminal, a photocell connected in parallel with said second filter capacitor, light source means for illuminating said photocell along a path adapted to be interrupted by a loop of film formed between said drive means when said uniform speed differs from the average speed of the film produced by said incremental drive means, whereby the resistance of said photocell is modulated at the rate of operation of said incremental drive means to modulate the amount of current flowing between the emitter and the collector of said second transistor at a rate determined by the capacitance of said second filter capacitor and thereby modulate the bias on said first transistor at a rate determined by the capacitance of said first filter capacitor, said capacitors and said speed reduction means being selected to make the response time of said capstan long relative to the rate of operation of said incremental drive means.
Claim 2
Dependent Claim
503 words
Film transport and illumination apparatus for a sound motion picture system utilizing strip film on which visual images and a sound track can be recorded, comprising incremental drive means operable to move the film strip past an optical station in increments corresponding to image frames, a capstan operable to move the film past a sound station at a substantially uniform speed dependent on the rate of rotation of said capstan, an induction motor having a stator and an output shaft, means connecting the output shaft of said induction motor to said incremental drive means to operate said drive means at a rate determined by the speed of said shaft, a primary winding on said stator, a secondary winding on said stator, a projection lamp connected in series with at least a portion of one of said windings, means for connecting a source of alternating current to said primary winding, a direct current motor having a winding and an output shaft, speed reduction means drivingly connecting the output shaft of said direct current motor to said capstan, direct current power supply means having first, second and third output terminals and input terminals energized by said secondary winding for producing first and second direct voltages, said first direct voltage being produced between said first and said third output terminals and said second direct voltage being produced between said second and said third input terminals, a first resistor connected in series with the winding of said direct current motor between said first and said third output terminals, a transistor having an emitter and a collector connected in parallel with said resistor, said transistor having a base, a first filter capacitor connected between the base and the collector of said first transistor, a second transistor having a collector, an emitter and a base, the collector and the emitter of said second transistor being connected between said second terminal and the base of said first transistor, a second resistor connected between the base of said second transistor and said third output terminal, a second filter capacitor connected between the base of said second transistor and said second output terminal, a photocell connected in parallel with said second filter capacitor, light source means for illuminating said photocell along a path adapted to be interrupted by a loop of film formed between said drive means when said uniform speed differs from the average speed of the film produced by said incremental drive means, whereby the resistance of said photocell is modulated at the rate of operation of said incremental drive means to modulate the amount of current flowing between the emitter and the collector of said second transistor at a rate determined by the capacitance of said second filter capacitor and thereby modulate the bias on said first transistor at a rate determined by the capacitance of said first filter capacitor, said capacitors and said speed reduction means being selected to make the response time of said capstan long relative to the rate of operation of said incremental drive means.
Claim 3
Dependent Claim
272 words
In combination with a sound motion picture system having a film drive pawl driven by an induction motor at a relatively fixed rate to move a strip of film incrementally past a projection station and a projection lamp at said projection station energized by a winding on said induction motor, a sound drive system for driving the strip of film through a sound station at uniform speed, comprising capstan means adapted to engage the film, a DC motor for driving said capstan means at a speed determined by the amount of current supplied to said DC motor and a motor speed control circuit for said DC motor comprising a source of voltage, a fixed resistor connected between said DC motor and said source to supply a first component of current to said DC motor to operate said capstan means at a speed causing film motion below the average film speed produced by said film drive pawl, first amplifying means responsive to a first applied signal to supply additional current to said DC motor in amounts determined by said first applied signal, first filter means for damping changes in the amplitude of a signal applied to said first amplifying means, second amplifying means responsive to a second applied signal to apply a first signal to said first amplifying means, second filter means for damping changes in the amplitude of a signal applied to said second amplifying mEans, and sensing means responsive to the length of a strip of film between said stations for applying a second signal to said second amplifying means fluctuating at said rate of operation of said film drive pawl.
Claim 4
Dependent Claim
272 words
In combination with a sound motion picture system having a film drive pawl driven by an induction motor at a relatively fixed rate to move a strip of film incrementally past a projection station and a projection lamp at said projection station energized by a winding on said induction motor, a sound drive system for driving the strip of film through a sound station at uniform speed, comprising capstan means adapted to engage the film, a DC motor for driving said capstan means at a speed determined by the amount of current supplied to said DC motor and a motor speed control circuit for said DC motor comprising a source of voltage, a fixed resistor connected between said DC motor and said source to supply a first component of current to said DC motor to operate said capstan means at a speed causing film motion below the average film speed produced by said film drive pawl, first amplifying means responsive to a first applied signal to supply additional current to said DC motor in amounts determined by said first applied signal, first filter means for damping changes in the amplitude of a signal applied to said first amplifying means, second amplifying means responsive to a second applied signal to apply a first signal to said first amplifying means, second filter means for damping changes in the amplitude of a signal applied to said second amplifying mEans, and sensing means responsive to the length of a strip of film between said stations for applying a second signal to said second amplifying means fluctuating at said rate of operation of said film drive pawl.
Claim 5
Dependent Claim
273 words
A film transport system for moving a strip of motion picture film uniformly past a sound station and incrementally past a projection station, comprising capstan means located at said sound station and adapted to engage the film and move it through said sound station when said capstan means is driven by a shaft at a speed determined by the speed of the shaft, a DC motor having a shaft connected to said capstan means, an induction motor having an output shaft and an energizing winding, incremental film transport means located at said projection station, connected to the output shaft of said induction motor and adapted to engage the film and move it incrementally through said projection station at an average speed determined by the speed of said induction motor output shaft, circuit means for supplying alternating current to the energizing winding of said induction motor, sensing means located between said stations and responsive to the length of the film between said stations for producing a control signal in accordance with said length that fluctuates at the frequency of operation of said incremental drive means, and two stage amplifying means controlled by said signal for supplying direct current to said DC motor at a rate tending to keep the average length of the film between said stations constant, a first stage of said amplifying means comprising filter means for damping fluctuations in said signal with a first variable time constant, and a second stage of said amplifying means comprising means for damping the damped signal from said first stage with a time constant substantially greater than the maximum time constant of said first stage.
Claim 6
Dependent Claim
273 words
A film transport system for moving a strip of motion picture film uniformly past a sound station and incrementally past a projection station, comprising capstan means located at said sound station and adapted to engage the film and move it through said sound station when said capstan means is driven by a shaft at a speed determined by the speed of the shaft, a DC motor having a shaft connected to said capstan means, an induction motor having an output shaft and an energizing winding, incremental film transport means located at said projection station, connected to the output shaft of said induction motor and adapted to engage the film and move it incrementally through said projection station at an average speed determined by the speed of said induction motor output shaft, circuit means for supplying alternating current to the energizing winding of said induction motor, sensing means located between said stations and responsive to the length of the film between said stations for producing a control signal in accordance with said length that fluctuates at the frequency of operation of said incremental drive means, and two stage amplifying means controlled by said signal for supplying direct current to said DC motor at a rate tending to keep the average length of the film between said stations constant, a first stage of said amplifying means comprising filter means for damping fluctuations in said signal with a first variable time constant, and a second stage of said amplifying means comprising means for damping the damped signal from said first stage with a time constant substantially greater than the maximum time constant of said first stage.
Claim 7
Dependent Claim
40 words
The apparatus of claim 3, in which said sensing means comprises a radiation responsive impedance and means for irradiating said radiation responsive impedance over a path interrupted by a length of film between said stations greater than a predetermined length.
Claim 8
Dependent Claim
122 words
The apparatus of claim 4, in which said first stage comprises a source of DC voltage, a resistor, a capacitor, and an amplifying device having a pair of load terminals and a control terminal, said source having terminals connected in series with said radiation responsive impedance and said resistor, said capacitor being connected in parallel with said radiation responsive device, and means connecting one load terminal and the control terminal of said amplifying device in parallel with said capacitor, whereby said first time constant is determined primarily by said capacitor, said resistor and said radiation responsive impedance, and the other of said load terminals and one terminal of said source comprise output terminals for applying said damped signal to said second stage.
Claim 9
Dependent Claim
113 words
The apparatus of claim 4, in which said second stage comprises a source of DC voltage, a resistor, a capacitor, and an amplifying device having a pair of load terminals and a control terminal, said source having terminals connected in series with said DC motor and said resistor, the load terminals of said amplifying device being connected in parallel with said resistor, and said cpacitor being connected between a first of said load terminals and said control terminal, said second time constant being determined in part by said capacitor, and said control terminal and one of said load terminals comprising input terminals to which the damped signal from said first stage is applied.
Claim 10
Dependent Claim
265 words
The apparatus of claim 4, in which said first stage comprises a first source of DC voltage, a first resistor, a first capacitor, and a first amplifying device having a pair of load terminals and a control terminal, said first source having terminals connected in series with radiation responsive impedance and said first resistor, said first capacitor being connected in parallel with Said radiation responsive device, and means connecting one load terminal and the control terminal of said first amplifying device in parallel with said first capacitor, whereby said first time constant is determined by said first capacitor and said radiation responsive impedance, the other of the load terminals of said first amplifying means and one terminal of said first source comprising output terminals for applying said damped signal to said second stage, and in which said second stage comprises a second source of DC voltage, a second resistor, a second capacitor, and a second amplifying device having a pair of load terminals and a control terminal, said second source having terminals connected in series with said DC motor and said second resistor, the load terminals of said second amplifying device being connected in parallel with said second resistor, and said second capacitor being connected between a first of the load terminals and the control terminal of said second amplifying device, said second time constant being determined in part by said second capacitor, and the control terminal and one of the load terminals of said second source comprising input terminals of said second stage to which said output terminals of said first stage are connected.
Claim 11
Dependent Claim
349 words
A sound motion picture system, comprising means forming a projection station at a first location, a projection lamp located at said projection station, a film drive claw located at said projection station, means forming a sound station at a second location, a film drive capstan located at said sound station, means for guiding a strip of film over a path from said capstan to said claw, said path including a region in which the film is free to form a loop of variable length, an induction motor, means operated by said motor for driving said claw, capstan drive means comprising a DC motor for driving said capstan at a speed determined by an applied current, said induction motor comprising a set of windings linked by a common core, means connecting at least a part of one of said windings in series with said lamp, first and second input terminals connected to one of said windings and adapted to be excited by an alternating voltage to cause the excitation of all of said windings, means responsive to the length of a loop of film in said region for producing an output signal in accordance with said length and fluctuating at the rate of operation of said film drive claw, means connected to one of said windings for producing a DC voltage, means controlled by said DC voltage for producing a component of current adequate to drive said DC motor at a speed below the speed required to move film at the average rate at which film is moved by said drive claw, first amplifying and filtering means controlled by said output signal for producing a damped control signal in accordance with said output signal but fluctuating at a first lower rate than said output signal, second amplifying and filtering means controlled by said DC voltage and said damped control signal for producing a control current component in accordance with said damped control signal but fluctuating at a second rate lower than said first lower rate, and circuit means for applying the sum of said current components to said DC motor.
Claim 12
Dependent Claim
349 words
A sound motion picture system, comprising means forming a projection station at a first location, a projection lamp located at said projection station, a film drive claw located at said projection station, means forming a sound station at a second location, a film drive capstan located at said sound station, means for guiding a strip of film over a path from said capstan to said claw, said path including a region in which the film is free to form a loop of variable length, an induction motor, means operated by said motor for driving said claw, capstan drive means comprising a DC motor for driving said capstan at a speed determined by an applied current, said induction motor comprising a set of windings linked by a common core, means connecting at least a part of one of said windings in series with said lamp, first and second input terminals connected to one of said windings and adapted to be excited by an alternating voltage to cause the excitation of all of said windings, means responsive to the length of a loop of film in said region for producing an output signal in accordance with said length and fluctuating at the rate of operation of said film drive claw, means connected to one of said windings for producing a DC voltage, means controlled by said DC voltage for producing a component of current adequate to drive said DC motor at a speed below the speed required to move film at the average rate at which film is moved by said drive claw, first amplifying and filtering means controlled by said output signal for producing a damped control signal in accordance with said output signal but fluctuating at a first lower rate than said output signal, second amplifying and filtering means controlled by said DC voltage and said damped control signal for producing a control current component in accordance with said damped control signal but fluctuating at a second rate lower than said first lower rate, and circuit means for applying the sum of said current components to said DC motor.
Claim 13
Dependent Claim
313 words
A sound motion picture system, comprising means forming a projection station at a first location, a projection lamp located at said projection station, a film drive claw located at said projection station, means forming a sound station at a second location, a film drive capstan located at said sound station, means for guiding a strip of film over a path from said capstan to said claw, said path including a region in which the film is free to form a loop of variable length, an induction motor, means operated by said motor for driving said claw, capstan drive means comprising a DC motor for driving said capstan at a speed determined by an applied current, said induction motor comprising a set of windings linked by a comMon core, means connecting at least a part of one of said windings in series with said lamp, first and second input terminals connected to one of said windings and adapted to be excited by an alternating voltage to cause the excitation of all of said windings, means connected to one of said windings for delivering an applied current to said DC motor, said applied current delivering means including means responsive to the length of a loop of film in said region for delivering an applied current to said DC motor selected to cause said capstan to drive the film at a speed below the average speed of the film being produced by said film drive claw when the length of a loop of film in said region is greater than a predetermined length and for delivering an applied current to said DC motor selected to cause said capstan to drive the film at a speed above the average speed of the film being produced by said film drive claw when the length of a loop of film in said region is greater than the predetermined length.
Claim 14
Dependent Claim
313 words
A sound motion picture system, comprising means forming a projection station at a first location, a projection lamp located at said projection station, a film drive claw located at said projection station, means forming a sound station at a second location, a film drive capstan located at said sound station, means for guiding a strip of film over a path from said capstan to said claw, said path including a region in which the film is free to form a loop of variable length, an induction motor, means operated by said motor for driving said claw, capstan drive means comprising a DC motor for driving said capstan at a speed determined by an applied current, said induction motor comprising a set of windings linked by a comMon core, means connecting at least a part of one of said windings in series with said lamp, first and second input terminals connected to one of said windings and adapted to be excited by an alternating voltage to cause the excitation of all of said windings, means connected to one of said windings for delivering an applied current to said DC motor, said applied current delivering means including means responsive to the length of a loop of film in said region for delivering an applied current to said DC motor selected to cause said capstan to drive the film at a speed below the average speed of the film being produced by said film drive claw when the length of a loop of film in said region is greater than a predetermined length and for delivering an applied current to said DC motor selected to cause said capstan to drive the film at a speed above the average speed of the film being produced by said film drive claw when the length of a loop of film in said region is greater than the predetermined length.
Claim 15
Dependent Claim
47 words
The system of claim 9 wherein said applied current delivering means additionally includes means for making the time of response of said capstan to changes in the length of the film loop in said region long relative to the rate of operation of said film drive claw.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-08-26 | 1978-02-25 | 1978-08-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-08-26 | 1982-02-25 | 1982-08-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-08-26 | 1986-02-25 | 1986-08-27 | $7700.00 | Window Closed / Lapsed |