US4301474A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Residual clamp error compensation circuit
Assignee: Tektronix Inc
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Filing: 1980-04-14
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Granted: 1981-11-17
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Expires: 2000-04-14
Abstract
Abstract An apparatus for matching the blanking levels of two television video signals is disclosed. When the vertical interval reference signal or any other signal (e.g., sync) is inserted on a program video signal their blanking levels should be matched. The apparatus described accomplishes this by matching the blanking level of the signal being inserted to that of the program video. The match is produced by sampling the residual clamping error of a slow clamp on the program channel and adding it to the signal being inserted. Therefore, the noise which would have been added to the program video is added to the inserted signal instead and therefore will not be visible in the television picture.
Inventors
- 👤 David J. Jurgensen
- 👤 Roger A. Marin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 14:03
CPC Classifications
H; H04; H04N; H04N5/00; H04N5/14; H04N5/16
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
120 words
An apparatus for matching the blanking level of a first video signal to a second video signal wherein said first video signal is being inserted on said second video signal, the apparatus comprising: a clamping circuit coupled to receive said second video signal and clamp said second video signal to a predetermined dc voltage level, said clamping circuit also produces an error voltage representative of the residual error of said clamping circuit; means for combining coupled to receive said error voltage and said first video signal to produce a compensated first video signal; and switching between means for switching said clamped second video signal and said compensated first video signal to an output terminal at the command of control signal.
Claim 2
Independent Claim
120 words
An apparatus for matching the blanking level of a first video signal to a second video signal wherein said first video signal is being inserted on said second video signal, the apparatus comprising: a clamping circuit coupled to receive said second video signal and clamp said second video signal to a predetermined dc voltage level, said clamping circuit also produces an error voltage representative of the residual error of said clamping circuit; means for combining coupled to receive said error voltage and said first video signal to produce a compensated first video signal; and switching between means for switching said clamped second video signal and said compensated first video signal to an output terminal at the command of control signal.
Claim 3
Dependent Claim
17 words
The apparatus according to claim 1 wherein said first video signal is a vertical interval reference signal.
Claim 4
Dependent Claim
17 words
The apparatus according to claim 2 wherein said second video signal is a television program video signal.
Claim 5
Dependent Claim
30 words
The apparatus according to claim 3 wherein said switching means connects said vertical interval reference signal to said output terminal during a predetermined line of said television program video signal.
Claim 6
Dependent Claim
14 words
The apparatus according to claim 1 wherein said clamping circuit comprises a slow clamp.
Claim 7
Dependent Claim
14 words
The apparatus according to claim 5 wherein said slow clamp comprises a feedback clamp.
Claim 8
Dependent Claim
14 words
The apparatus according to claim 1 wherein said switching means comprises an electronic switch.
Claim 9
Dependent Claim
53 words
In an apparatus for matching the blanking levels of a first video signal and a second video signal wherein one of said video signals is to be inserted on the other one thereof, the improvement comprising: varying the blanking level of the inserted signal to match the blanking level of the other signal.
Claim 10
Dependent Claim
53 words
In an apparatus for matching the blanking levels of a first video signal and a second video signal wherein one of said video signals is to be inserted on the other one thereof, the improvement comprising: varying the blanking level of the inserted signal to match the blanking level of the other signal.
Claim 11
Dependent Claim
26 words
The apparatus according to claim 8 wherein said inserted signal comprises a vertical interval reference signal and said other signal comprises a television program video signal.
Claim 12
Dependent Claim
89 words
Apparatus for matching the blanking level of a second video signal to the blanking level of a first video signal before combination thereof, comprising: circuit means for clamping said first video signal to a predetermined voltage level and for generating an error signal representative of any difference between said predetermined voltage level and said clamped voltage level; and means for combining said error signal and said second video signal to match the blanking level of said second video signal to the blanking level of said clamped first video signal.
Claim 13
Dependent Claim
89 words
Apparatus for matching the blanking level of a second video signal to the blanking level of a first video signal before combination thereof, comprising: circuit means for clamping said first video signal to a predetermined voltage level and for generating an error signal representative of any difference between said predetermined voltage level and said clamped voltage level; and means for combining said error signal and said second video signal to match the blanking level of said second video signal to the blanking level of said clamped first video signal.
References Cited (Backward Citations)
US3619495A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-11-16 | 1985-05-18 | 1985-11-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-11-16 | 1989-05-18 | 1989-11-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-11-16 | 1993-05-18 | 1993-11-17 | $7700.00 | Window Closed / Lapsed |