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US3659040A
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A control system for a color synchronizing signal oscillator in a magnetic recording and reproducing apparatus
Assignee: Victor Company of Japan Ltd
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Filing: 1969-09-29
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Granted: 1972-04-25
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Expires: 1989-09-29
Abstract
Abstract A control system for a color synchronizing signal oscillator used with a magnetic color video signal recording and reproducing apparatus which prevents a color step out, when a color video signal having a timing variation is demodulated. In this system, the phases of a color burst signal of the color video signal and an output signal of a voltage control oscillator are compared with each other. A phase error voltage is produced corresponding to the phase difference between the two signals, and this voltage is sampled by sampling pulses. The sampled phase error voltage is held during one horizontal scanning period and then supplied to the voltage control oscillator to control its oscillation frequency so that color synchronization may be effected satisfactorily.
Inventors
- 👤 Mitsuo Fujita
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 01:36
CPC Classifications
H; H04; H04N; H04N9/00; H04N9/79; H04N9/87; H04N9/898; H04N9/44; H04N9/455
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
333 words
A control system for a color synchronizing signal oscillator used in magnetic video signal recording and reproducing apparatus, said system comprising means for separating a horizontal synchronizing signal from a color video signal reproduced by magnetic recording and reproducing apparatus, means responsive to said horizontal synchronizing signal for producing a burst flag, means responsive to said flag for gating a burst signal from said color video signal, voltage control oscillator means having a center frequency substantially equal to the frequency of a chrominance subcarrier, phase comparing means for comparing the phase of the output signal of said voltage control oscillator means with the phase of said burst signal and generating a phase error signal having a voltage corresponding to the phase difference between the two compared signals, means responsive to said burst flag for generating first sampling pulses, first sampling and holding means responsive to said first sampling pulses for sampling said phase error signal and holding the sampled phase error signal during one horizontal scanning period, first control means for controlling the oscillating frequency of said voltage control oscillator means in response to the voltage level of the output signal of said first sampling and holding means, means responsive to the horizontal synchronizing signal for generating a trapezoid waveform signal, the beginning point of the forwardly inclined portion of said waveform synchronized with the horizontal synchronizing signal, means responsive to the horizontal synchronizing signal for generating second sampling pulses which are delayed in time with respect to the responding horizontal synchronizing signal to a position which is in phase within the forwardly inclined portion of said trapezoid waveform signal, second sampling and holding means responsive to said second sampling pulses for sampling said trapezoid waveform signal and holding the sampled trapezoid waveform signal, and second coNtrol means for controlling the oscillating frequency of said voltage control oscillator means in response to the voltage level of the output signal of said second sampling and holding means in addition to the first control means.
Claim 2
Dependent Claim
333 words
A control system for a color synchronizing signal oscillator used in magnetic video signal recording and reproducing apparatus, said system comprising means for separating a horizontal synchronizing signal from a color video signal reproduced by magnetic recording and reproducing apparatus, means responsive to said horizontal synchronizing signal for producing a burst flag, means responsive to said flag for gating a burst signal from said color video signal, voltage control oscillator means having a center frequency substantially equal to the frequency of a chrominance subcarrier, phase comparing means for comparing the phase of the output signal of said voltage control oscillator means with the phase of said burst signal and generating a phase error signal having a voltage corresponding to the phase difference between the two compared signals, means responsive to said burst flag for generating first sampling pulses, first sampling and holding means responsive to said first sampling pulses for sampling said phase error signal and holding the sampled phase error signal during one horizontal scanning period, first control means for controlling the oscillating frequency of said voltage control oscillator means in response to the voltage level of the output signal of said first sampling and holding means, means responsive to the horizontal synchronizing signal for generating a trapezoid waveform signal, the beginning point of the forwardly inclined portion of said waveform synchronized with the horizontal synchronizing signal, means responsive to the horizontal synchronizing signal for generating second sampling pulses which are delayed in time with respect to the responding horizontal synchronizing signal to a position which is in phase within the forwardly inclined portion of said trapezoid waveform signal, second sampling and holding means responsive to said second sampling pulses for sampling said trapezoid waveform signal and holding the sampled trapezoid waveform signal, and second coNtrol means for controlling the oscillating frequency of said voltage control oscillator means in response to the voltage level of the output signal of said second sampling and holding means in addition to the first control means.
Claim 3
Dependent Claim
36 words
The control system as defined in claim 1 further comprising phase modulator means for phase-modulating the output signal of said voltage control oscillator means responsive to the output signal of the first sampling and holding means.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-04-25 | 1975-10-25 | 1976-04-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-04-25 | 1979-10-25 | 1980-04-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-04-25 | 1983-10-25 | 1984-04-25 | $7700.00 | Window Closed / Lapsed |