US3562409A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Circuit arrangements including a color display cathode-ray tube of the index type
Assignee: US Philips Corp
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Filing: 1968-06-13
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Granted: 1971-02-09
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Expires: 1988-06-13
Abstract
Abstract A circuit for ensuring the minimum level flow of current in an indexing type color cathode ray display tube in order to prevent loss of the indexing signal during a scanning period. A gate is provided to prevent application of video signals to the display tube during the first few lines of each field, and during this time a control signal is produced from the indexing signal corresponding to the desired black level. The control signal thus produced is applied to the display tube for the remainder of the field.
Inventors
- 👤 Kenneth George Freeman
- 👤 Michael Compton French
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 23:15
CPC Classifications
H; H04; H04N; H04N9/00; H04N9/12; H04N9/16; H04N9/22; H04N9/24
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
159 words
A circuit arrangement for automatically reducing fluctuations which would otherwise occur in the amplitude of a signal which would be derived from scanning the indexing strips of a color display cathode ray tube of the index type in the absence of a video signal applied to the tube, said arrangement comprising said tube, a video channel coupled to a control electrode of said tube, characterized in that the circuit arrangement comprises a gate in series with the video channel and means for deriving a control signal from said tube during at least a part of the times when the gate is blocked, which control signal varies with said amplitude, means for coupling said control signal to said tube during each line scan to reduce fluctuations in said amplitude, and means for blocking said gate during field scan starting times and rendering it conducting during the scan of the remainder of the lines of the fields on the tube Screen.
Claim 2
Dependent Claim
159 words
A circuit arrangement for automatically reducing fluctuations which would otherwise occur in the amplitude of a signal which would be derived from scanning the indexing strips of a color display cathode ray tube of the index type in the absence of a video signal applied to the tube, said arrangement comprising said tube, a video channel coupled to a control electrode of said tube, characterized in that the circuit arrangement comprises a gate in series with the video channel and means for deriving a control signal from said tube during at least a part of the times when the gate is blocked, which control signal varies with said amplitude, means for coupling said control signal to said tube during each line scan to reduce fluctuations in said amplitude, and means for blocking said gate during field scan starting times and rendering it conducting during the scan of the remainder of the lines of the fields on the tube Screen.
Claim 3
Dependent Claim
30 words
An arrangement as claimed in claim 1 wherein said field scan starting times are the periods at the start of each field scan when the first few lines are scanned.
Claim 4
Dependent Claim
94 words
An arrangement as claimed in claim 1 wherein the field scan starting times include times when at least a portion of a line lying on the tube screen at substantially the start of a field is scanned, the arrangement including means for deriving an indexing signal in response to the scanning of the indexing strips by the tube electron beam, an amplifier for amplifying said indexing signal and a frequency divider, the inputs of said means for deriving a control signal and of said frequency divider being coupled with the output of said amplifier.
Claim 5
Dependent Claim
32 words
An arrangement as claimed in claim 1 wherein the control signal is arranged to be coupled to the tube via a part of the video channel subsequent to the video channel gate.
Claim 6
Dependent Claim
48 words
An arrangement as claimed in claim 1 wherein the means for deriving the control signal includes a second gate in series therewith, which second gate is arranged to conduct during said field scan starting times and to be blocked during said remainder of the lines of the fields.
Claim 7
Dependent Claim
129 words
An arrangement as claimed in claim 5 including means for deriving an output in response to the scanning of the indexing strips by the tube electron beam and with its output coupled to a reset terminal of a bistable circuit, means for coupling the trailing edge of the field flyback pulses to a trigger terminal of said bistable circuit, an output of said bistable circuit being arranged to block the video channel gate, and an output of the bistable circuit being coupled to a trigger input terminal of a monostable circuit having an ''''on'''' period equal to the time it is desired to open the second gate each time, the output of the monostable circuit being arranged to block the video channel gate and to open the second gate.
Claim 8
Dependent Claim
56 words
An arrangement as claimed in claim 3 wherein the means for deriving a control signal comprises a peak-detector, a DC reference voltage source, and a comparator for comparing the peak-detector output with the DC reference, the resultant circuit coupling the peak-detector output with the tube having an integration time long compared with a field scan period.
Claim 9
Dependent Claim
45 words
An arrangement as claimed in claim 7 wherein the peak-detector has an integration time long compared with a line scan period, the comparator output being coupled to said tube via a second peak detector having an integration time long compared with a field scan period.
Claim 10
Dependent Claim
136 words
In a color television receiver of the type having an indexing type color display tube, a source of video signals, means applying said signals to said tube, means for deriving indexing signals from said tube, and a source of field flyback pulses; the improvement comprising means connected to said source of flyback pulses and said means for producing said indexing signal for producing a control signal responsive to the level of said indexing signals during only predetermined lines of each field, said means for applying said video signals to said tube comprising gate means, means for blocking said gate means during said predetermined lines, and means for maintaining current in said tube at a predetermined minimum level comprising means for applying said control signal to said tube during the remainder of the lines of each field.
Claim 11
Dependent Claim
136 words
In a color television receiver of the type having an indexing type color display tube, a source of video signals, means applying said signals to said tube, means for deriving indexing signals from said tube, and a source of field flyback pulses; the improvement comprising means connected to said source of flyback pulses and said means for producing said indexing signal for producing a control signal responsive to the level of said indexing signals during only predetermined lines of each field, said means for applying said video signals to said tube comprising gate means, means for blocking said gate means during said predetermined lines, and means for maintaining current in said tube at a predetermined minimum level comprising means for applying said control signal to said tube during the remainder of the lines of each field.
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) | 1974-02-08 | 1974-08-10 | 1975-02-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-02-08 | 1978-08-10 | 1979-02-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-02-08 | 1982-08-10 | 1983-02-09 | $7700.00 | Window Closed / Lapsed |