US3700794A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Improvements in or relating to television camera clamping arrangements
Assignee: BAE Systems Electronics Ltd
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Filing: 1970-09-28
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Granted: 1972-10-24
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Expires: 1990-09-28
Abstract
Abstract A video signal level clamping arrangement for a television camera in which input video signals are clamped to a fixed potential once during each line flyback. The clamped video signals are fed to a signal path into which signals are gated, each of the signals extending for at least the duration of one line flyback period. The resultant spurious free waveform is clamped to a further fixed potential source which is controlled such that it does not clamp during line flyback or outside field suppression. The waveform resulting from the last mentioned clamping is amplitude clipped to produce a stabilized D.C. level corresponding to a predetermined shade, e.g., black.
Inventors
- 👤 Peter William Loose
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 02:55
CPC Classifications
H; H04; H04N; H04N5/00; H04N5/14; H04N5/16; H04N5/18
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
160 words
A clamping arrangement for television cameras having a video signal output adapted to provide line-by-line clamping within a frame flyback period, comprising in combination: amplifier means for amplifying said video signal output; means for clamping the output of said amplifier means to a reference potential during periods between line scans to provide a D.C. level output from said amplifier means which is free of low frequency interference signal components; means for gating in pulses in the output of said amplifier means during substantially the whole of said periods thereby to produce a resultant waveform which includes said pulses, said pulses having an amplitude exceeding the maximum amplitude of spurious signals which may occur during such periods; means for clamping said resultant waveform to a fixed reference potential during a line scan period and outside said periods between line scans; and means for clipping the output of the last means to remove said pulses and provide a stabilized D.C. voltage level.
Claim 2
Dependent Claim
160 words
A clamping arrangement for television cameras having a video signal output adapted to provide line-by-line clamping within a frame flyback period, comprising in combination: amplifier means for amplifying said video signal output; means for clamping the output of said amplifier means to a reference potential during periods between line scans to provide a D.C. level output from said amplifier means which is free of low frequency interference signal components; means for gating in pulses in the output of said amplifier means during substantially the whole of said periods thereby to produce a resultant waveform which includes said pulses, said pulses having an amplitude exceeding the maximum amplitude of spurious signals which may occur during such periods; means for clamping said resultant waveform to a fixed reference potential during a line scan period and outside said periods between line scans; and means for clipping the output of the last means to remove said pulses and provide a stabilized D.C. voltage level.
Claim 3
Dependent Claim
26 words
A camera as claimed in claim 1 wherein the preliminary clamping is effected during a short period occurring approximately centrally within the time of line flyback.
Claim 4
Dependent Claim
39 words
A camera as claimed in claim 2 wherein the effective gating in of pulses is effected by including in said signal path a normally conductive circuit element and rendering The same non-conductive by the pulses to be gated in.
Claim 5
Dependent Claim
56 words
A camera as claimed in claim 3 wherein a normally forward-biassed diode is employed as said circuit element and the pulses to be gated in are utilized to render conductive a normally non-conductive switch element which, when conductive, connects one side of said diode to a reference potential source dimensioned to overcome the normal forward bias.
Claim 6
Dependent Claim
35 words
A camera as claimed in claim 4 wherein amplitude clipping is effected by a differential amplifier having one input fed with the waveform to be clipped and the other fed from a reference potential source.
Claim 7
Dependent Claim
91 words
A camera as claimed in claim 5 wherein the clamping of the wave form is the resultant of the aforesaid gating-in of pulses is effected by a clamping circuit constituted by a diode bridge the ends of one diagonal of which are connected respectively to a point at which said resultant appears and to a point of fixed potential and to the ends of the other diagonal of which are respectively applied opposite polarity waveforms occurring during the major part of a useful scanning line excursion taking place during field suppression.
Claim 8
Dependent Claim
21 words
A camera as claimed in claim 2 wherein gating in of pulses is effected by superimposing them in said signal path.
Claim 9
Dependent Claim
35 words
A camera as claimed in claim 7 wherein amplitude clipping is effected by a differential amplifier having one input fed with the waveform to be clipped and the other fed from a reference potential source.
Claim 10
Dependent Claim
93 words
A camera as claimed in claim 8 wherein the clamping of the wave form which is the resultant of the aforesaid gating in of pulses is effected by a clamping circuit constituted by a diode bridge the ends of one diagonal of which are connected respectively to a point at which said resultant appears and to a point of fixed potential and to the ends of the other diagonal of which are respectively applied opposite polarity waveforms occurring during the major part of a useful scanning line excursion taking place during field suppression.
Claim 11
Dependent Claim
20 words
A camera as claimed in claim 1 wherein the stabilized D.C. voltage level corresponds with a picture shade of black.
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) | 1975-10-24 | 1976-04-24 | 1976-10-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-10-24 | 1980-04-24 | 1980-10-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-10-24 | 1984-04-24 | 1984-10-24 | $7700.00 | Window Closed / Lapsed |