US3974520A
Expired / Lapsed
US
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Chrominance subcarrier phase control system
Assignee: Sony Corp
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Filing: 1975-04-22
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Granted: 1976-08-10
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Expires: 1995-04-22
Abstract
Abstract In a color video signal processing system having an automatic phase control circuit for correcting effects of angular errors, that is, time axis variations, in the chrominance subcarrier, the loop gain of the automatic phase control circuit is increased for each vertical blanking interval, as compared with the loop gain during each vertical trace of scanning interval of the color video signal, so as to eliminate visible hue aberrations from the color television picture that results from the processed color video signal. Variations in the frequency and/or phase of the chrominance subcarrier are desirably eliminated in a frequency converter by means of a frequency converting signal provided by the automatic phase control circuit which includes a variable frequency oscillator under the control of a control or error voltage from a phase comparator comparing the chrominance subcarrier with the output of a stable local oscillator, and the change in the loop gain of such automatic phase control circuit is effected by selectively attenuating the output of the stable local oscillator supplied to the phase comparator, or by selectively controlling a bias voltage of the variable frequency oscillator.
Inventors
- 👤 Kunihiro Kuroyanagi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 15:39
CPC Classifications
H; H04; H04N; H04N9/00; H04N9/79; H04N9/80; H04N9/82; H04N9/83
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
77 words
A color video signal processing system for correcting effects of angular errors in the subcarrier of the chrominance component of a color video signal, comprising: A. frequency converting means receiving said chrominance component of the color video signal for frequency converting the chrominance subcarrier by means of a frequency converting signal applied to said frequency converting means; and B. an automatic phase control loop circuit comprising: 1. a reference signal source for producing a reference signal, 2.
Claim 2
Dependent Claim
77 words
A color video signal processing system for correcting effects of angular errors in the subcarrier of the chrominance component of a color video signal, comprising: A. frequency converting means receiving said chrominance component of the color video signal for frequency converting the chrominance subcarrier by means of a frequency converting signal applied to said frequency converting means; and B. an automatic phase control loop circuit comprising: 1. a reference signal source for producing a reference signal, 2.
Claim 3
Dependent Claim
84 words
a phase comparator for phase comparing the chrominance subcarrier with said reference signal and providing a control voltage in response to a deviation of said chrominance subcarrier from said reference signal, 3. means for producing said frequency converting signal including a variable frequency oscillator having its output phase controlled by said control voltge from said phase comparator, and 4. means for changing the gain of said loop circuit to one value for the vertical blanking interval and a different value for the vertical trace
Claim 4
Dependent Claim
84 words
a phase comparator for phase comparing the chrominance subcarrier with said reference signal and providing a control voltage in response to a deviation of said chrominance subcarrier from said reference signal, 3. means for producing said frequency converting signal including a variable frequency oscillator having its output phase controlled by said control voltge from said phase comparator, and 4. means for changing the gain of said loop circuit to one value for the vertical blanking interval and a different value for the vertical trace
Claim 5
Dependent Claim
45 words
interval, respectively, of said color video signal. 2. A color video signal processing system according to claim 1; in which the gain of said loop circuit is increased for each said vertical blanking interval as compared with said gain for each said vertical trace interval.
Claim 6
Dependent Claim
64 words
A color video signal processing system according to claim 1; in which said means for changing the gain of said loop circuit includes means for relatively greatly attenuating the level of said reference signal applied to said comparator during each said vertical trace interval and for reducing the level attenuation of said reference signal applied to said comparator during each said vertical blanking interval.
Claim 7
Dependent Claim
112 words
A color video signal processing system according to claim 1; in which said means for changing the gain of said loop circuit includes level attenuating means, switch means having a first condition for applying said reference signal directly to said comparator and a second condition for applying said reference signal to said comparator through said attenuating means, means for separating a vertical synchronizing signal from the color video signal, and means for controlling said switch means in dependence on the separated vertical synchronizing signal so as to dispose said switch means in said first condition during each said vertical blanking interval and in said second condition during each said vertical trace interval.
Claim 8
Dependent Claim
114 words
A color video signal processing system according to claim 1; in which said means for changing the gain of said loop circuit includes variable level attenuating means through which said reference signal is applied from said reference signal source to said comparator, means for separating a vertical synchronizing signal from the color video signal, and means for controlling said level attenuating means in response to the separated vertical synchronizing signal so as to cause relatively great attenuation of the level of said reference signal applied to said comparator during each said vertical trace interval and reduced attenuation of said level of the reference signal applied to said comparator during each said vertical blanking interval.
Claim 9
Dependent Claim
86 words
A color video signal processing system according to claim 1; in which said means for changing the gain of said loop circuit includes means for separating a vertical synchronizing signal from the color video signal, and means for varying a bias voltage for said variable frequency oscillator in dependence on the separated vertical synchronizing signal so that the gain of said output of the variable frequency oscillator is increased for each said vertical blanking interval as compared with said gain for each said vertical trace interval.
Claim 10
Dependent Claim
22 words
A color video signal processing system according to claim 1; in which said color video signal is a PAL color television signal.
Claim 11
Dependent Claim
61 words
A color video signal processing system according to claim 1; in which said chrominance component, as received by said frequency converting means, has a frequency band substantially lower than a normal frequency band therefor, and said frequency converting signal is effective, in said frequency converting means, to restore said chrominance component from said lower frequency band to said normal frequency band.
Claim 12
Dependent Claim
60 words
A color video signal processing system according to claim 8; in which said color video signal is selectively a PAL color television signal and an NTSC color television signal; and further comprising means for deactivating said means for changing the gain of said output of the variable frequency oscillator when said color video signal is an NTSC color television signal.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-08-10 | 1980-02-09 | 1980-08-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-08-10 | 1984-02-09 | 1984-08-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-08-10 | 1988-02-09 | 1988-08-10 | $7700.00 | Window Closed / Lapsed |