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US3670100A
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Automatic reference level set for television cameras
Assignee: Telemation Inc
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Filing: 1971-03-29
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Granted: 1972-06-13
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Expires: 1991-03-29
Abstract
Abstract Methods and apparatus for automatically establishing the voltage levels in a television camera which represent signal amplitude levels corresponding to the black and white reference levels by sensing the voltage level of a video signal channel as the image of the scene to be televised is scanned, comparing the sensed signal with a reference signal and establishing a digital signal indicative of whether the voltage of the sensed signal is greater or less than that of the reference, storing the digital information and, if desired, altering the information stored upon command from the comparator, establishing an output voltage signal having a magnitude determined by the stored or altered digital information and modifying the black and white levels from the camera.
Inventors
- 👤 John A Briggs
- 👤 Ronald C Ward
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 18:33
CPC Classifications
H; H04; H04N; H04N5/00; H04N5/14; H04N5/16
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
135 words
Apparatus for establishing and maintaining the video white and black levels in a television camera, said apparatus comprising: sensing means sensing the instantaneous voltage levels of a video signal from the camera image pickup tube; reference means establishing a reference signal as a basis of comparison; comparison means connected to compare the video signal from said camera pickup tube to the reference signal and emitting a digital signal indicative of whether the voltage of the sensed signal is greater or less than the reference signal; counter means to store digital information; means modifying the digital information present in the counter by command from the comparator; digital-to-analog converter means to convert the digital information stored to an analog control signal; means to modify video signal voltages representing white and black levels with the analog control signal.
Claim 2
Dependent Claim
135 words
Apparatus for establishing and maintaining the video white and black levels in a television camera, said apparatus comprising: sensing means sensing the instantaneous voltage levels of a video signal from the camera image pickup tube; reference means establishing a reference signal as a basis of comparison; comparison means connected to compare the video signal from said camera pickup tube to the reference signal and emitting a digital signal indicative of whether the voltage of the sensed signal is greater or less than the reference signal; counter means to store digital information; means modifying the digital information present in the counter by command from the comparator; digital-to-analog converter means to convert the digital information stored to an analog control signal; means to modify video signal voltages representing white and black levels with the analog control signal.
Claim 3
Dependent Claim
56 words
The apparatus of claim 1 further comprising: latch means connected between said comparison means and said counter means to limit the rate of change of the counter means information during each field scan of said sensing means, and reset means connected to reset said latch means upon completion of each field scan by said sensing means.
Claim 4
Dependent Claim
48 words
The apparatus of claim 1 wherein: said comparison means emit one binary signal when the value of the sensed voltage is greater than that of the reference signal and emit an opposite binary signal when the value of sensed voltage is less than that of the reference signal.
Claim 5
Dependent Claim
40 words
The apparatus of claim 3 wherein: said counter means comprise an up/down counter which counts up upon receipt of one binary signal from said comparison means and counts down upon receipt of the opposite binary signal from said comparison means.
Claim 6
Dependent Claim
15 words
The apparatus of claim 3 wherein: said counter means comprise at least one unidirectional counter.
Claim 7
Independent Claim
125 words
The method of maintaining the video voltage levels in a television camera, said method comprising the steps of: sensing the voltage level of a video signal as the image from scene to be televised is scanned; establishing a reference signal having a voltage indicative of a selected reference level; comparing the sensed signal with said reference signal and establishing a digital signal indicative of whether the voltage of the sensed signal is greater or less than that of said reference signal; counting in a desired direction upon command by the digital signal for control purposes during a predetermined interval of time; establishing a feedback voltage signal proportional to the count during said interval; and using the feedback voltage signal to modify set peak voltage levels.
Claim 8
Independent Claim
125 words
The method of maintaining the video voltage levels in a television camera, said method comprising the steps of: sensing the voltage level of a video signal as the image from scene to be televised is scanned; establishing a reference signal having a voltage indicative of a selected reference level; comparing the sensed signal with said reference signal and establishing a digital signal indicative of whether the voltage of the sensed signal is greater or less than that of said reference signal; counting in a desired direction upon command by the digital signal for control purposes during a predetermined interval of time; establishing a feedback voltage signal proportional to the count during said interval; and using the feedback voltage signal to modify set peak voltage levels.
References Cited (Backward Citations)
US3557305A
Cited
US3571508A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-06-13 | 1975-12-13 | 1976-06-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-06-13 | 1979-12-13 | 1980-06-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-06-13 | 1983-12-13 | 1984-06-13 | $7700.00 | Window Closed / Lapsed |