US3873766A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatic horizontal frequency control circuits for television receivers
Assignee: Sony Corp
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Filing: 1974-02-13
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Granted: 1975-03-25
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Expires: 1994-02-13
Abstract
Abstract An automatic horizontal frequency control circuit for a television receiver suitable for monitoring an image of a video signal reproduced by a video tape recorder, in which a horizontal oscillator is controlled in its frequency with a control signal produced by a variable time constant circuit which is supplied with a signal obtained as a result of comparison of a horizontal synchronous signal with a horizontal output pulse. The time constant of the time constant circuit during a vertical blanking period is shortened as compared with the time constant during other periods, thereby to compensate for a skew distortion in the image caused by the time errors of the reproduced video signal from the video tape recorder within the vertical blanking period.
Inventors
- 👤 Akira Maeda
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 02:02
CPC Classifications
H; H04; H04N; H04N5/00; H04N5/04; H04N5/05
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
173 words
An automatic horizontal frequency control circuit for a television receiver comprising: a. oscillator means for producing a horizontal frequency signal; b. horizontal output circuit means connected to said oscillator means for producing a horizontal pulse in response to said horizontal frequency signal; c. phase comparator means connected to be supplied with a horizontal sync signal in a video signal and said horizontal pulse for comparison and producing an output signal varying in response to the result of the comparison; d. variable time constant circuit means connected between said phase comparator means and said oscillator means for producing a frequency control signal for said oscillator means from said output signal of said phase comparator means, said variable time constant circuit means having variable time constant; and e. control circuit means connected to said variable time constant circuit means for controlling it so as to have a first time constant and a second time constant during a vertical blanking period and other periods, respectively, said first time constant being shorter than said second time constant.
Claim 2
Dependent Claim
173 words
An automatic horizontal frequency control circuit for a television receiver comprising: a. oscillator means for producing a horizontal frequency signal; b. horizontal output circuit means connected to said oscillator means for producing a horizontal pulse in response to said horizontal frequency signal; c. phase comparator means connected to be supplied with a horizontal sync signal in a video signal and said horizontal pulse for comparison and producing an output signal varying in response to the result of the comparison; d. variable time constant circuit means connected between said phase comparator means and said oscillator means for producing a frequency control signal for said oscillator means from said output signal of said phase comparator means, said variable time constant circuit means having variable time constant; and e. control circuit means connected to said variable time constant circuit means for controlling it so as to have a first time constant and a second time constant during a vertical blanking period and other periods, respectively, said first time constant being shorter than said second time constant.
Claim 3
Dependent Claim
46 words
An automatic horizontal frequency control circuit according to claim 1, wherein said variable time constant circuit means comprises at least two time constant components each having different time constants, one of said time constant components being connected selectively to be operated by said control circuit means.
Claim 4
Dependent Claim
28 words
An automatic horizontal frequency control circuit according to claim 2, wherein said one of time constant components includes switch means controlled in its conductivity by said control means.
Claim 5
Dependent Claim
53 words
An automatic horizontal frequency control circuit according to claim 3, wherein said one of time constant components comprises a series connection of a capacitor and a diode provided in parallel to the other of said time constant components, said diode being made nonconductive only during the vertical blanking period by said control means.
Claim 6
Dependent Claim
43 words
An automatic horizontal frequency control circuit for a television receiver according to claim 1, further comprising a sync separator means for generating said horizontal sync signal and a vertical sync signal, and said horizontal sync signal being supplied to said phase comparator means.
Claim 7
Dependent Claim
45 words
An automatic horizontal frequency control circuit for a television receiver according to claim 5, further comprising a vertical oscillator means connected to said sync separator means and receiving said vertical sync signal therefrom, and a vertical output circuit means connected to said vertical oscillating means.
Claim 8
Dependent Claim
28 words
An automatic horizontal frequency control circuit according to claim 5, wherein a control signal in response to said vertical sync signal is supplied to said control circuit 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) | 1978-03-24 | 1978-09-23 | 1979-03-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-03-24 | 1982-09-23 | 1983-03-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-03-24 | 1986-09-23 | 1987-03-25 | $7700.00 | Window Closed / Lapsed |