Patent US4012775A successfully refreshed from Google Patents.
US4012775A
Expired / Lapsed
US
⏱️ 0.0 years remaining
System for stabilizing cathode ray tube operation
Assignee: Thomson CSF Broadcast Inc
•
Filing: 1975-04-28
•
Granted: 1977-03-15
•
Expires: 1995-04-28
Abstract
Abstract The invention pertains to a video display apparatus which includes a cathode ray tube having at least one electron gun and means for deriving a source of excitatory voltage signal representative of picture information. In accordance with the invention there is provided a system for stabilizing the display intensity attributable to the electron gun comprising means coupling the source of voltage signal to the gun for generating a stabilized current in the gun, the level of current in the gun being substantially independent of variations in the operating characteristics of the gun. In the preferred embodiment of the invention a test signal is periodically applied at a predetermined level to the gun. A sampler samples the beam current of the gun during the test signal and generates a correction signal in accordance with the sample value. The correction signal is applied to the electron gun so as to stabilize its reference current level.
Inventors
- 👤 Clyde Smith
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 19:09
CPC Classifications
H; H04; H04N; H04N9/00; H04N9/64; H04N9/72
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
141 words
In a television display apparatus which includes a cathode ray tube having at least one electron gun and means for applying a television video signal to said electron gun; a system for stabilizing the display intensity attributable to said electron gun, comprising: means for generating first and second test signals during the vertical blanking intervals of said television video signal; means for applying said first and second test signals to said electron gun during first and second portions, respectively, of said vertical blanking intervals; means for sampling the beam current of said electron gun during said first and second portions and for generating first and second correction signals, respectively, in accordance with the sampled values; and means for applying said first and second correction signals to said electron gun so as to stabilize the reference current level of said electron gun.
Claim 2
Dependent Claim
141 words
In a television display apparatus which includes a cathode ray tube having at least one electron gun and means for applying a television video signal to said electron gun; a system for stabilizing the display intensity attributable to said electron gun, comprising: means for generating first and second test signals during the vertical blanking intervals of said television video signal; means for applying said first and second test signals to said electron gun during first and second portions, respectively, of said vertical blanking intervals; means for sampling the beam current of said electron gun during said first and second portions and for generating first and second correction signals, respectively, in accordance with the sampled values; and means for applying said first and second correction signals to said electron gun so as to stabilize the reference current level of said electron gun.
Claim 3
Dependent Claim
22 words
The system as defined by claim 1 wherein said first and second correction signals are applied to grids of said electron gun.
Claim 4
Dependent Claim
23 words
The system as defined by claim 2 wherein means are provided for maintaining the correction signals during the intervals between successive test signals.
Claim 5
Dependent Claim
24 words
The system as defined by claim 1 wherein means are provided for maintaining the correction signals during the intervals between the successive test signals.
Claim 6
Dependent Claim
22 words
The system as defined by claim 1 wherein said first and second test signals are at white and black level viedo, respectively.
Claim 7
Dependent Claim
23 words
The system as defined by claim 5 wherein said first correction signal is applied as a multiplying factor to said television video signal.
Claim 8
Dependent Claim
23 words
The system as defined by claim 6 wherein the corrected television video signal is applied to the control grid of said electron gun.
Claim 9
Dependent Claim
22 words
The system as defined by claim 6 wherein the corrected television video signal is applied to the cathode of said electron gun.
Claim 10
Dependent Claim
25 words
The system as defined by claim 6 wherein said second correction signal is applied as a DC reference level to the corrected television video signal.
Claim 11
Dependent Claim
26 words
The system as defined by claim 1 wherein said means for sampling the beam current comprises a resistor in series with the cathode of said gun.
Claim 12
Dependent Claim
155 words
In a video display apparatus which includes a cathode ray tube having a plurality of electron guns and means for applying a plurality of television video signals representative of color picture information to said electron guns; a system for balancing the color screen temperature of said cathode ray tube, comprising: means for generating first and second test signals during the vertical blanking intervals of said television video signal; means for applying said first and second test signals to said electron guns during first and second portions, respectively, of said vertical blanking intervals; means for sampling the beam current of each electron gun during said first and second portions and for generating first and second correction signals, respectively, for each electron gun in accordance with the sampled values; and means for applying said first and second correction signals to their respective electron guns so as to balance the screen color temperature of said cathode ray tube.
Claim 13
Dependent Claim
155 words
In a video display apparatus which includes a cathode ray tube having a plurality of electron guns and means for applying a plurality of television video signals representative of color picture information to said electron guns; a system for balancing the color screen temperature of said cathode ray tube, comprising: means for generating first and second test signals during the vertical blanking intervals of said television video signal; means for applying said first and second test signals to said electron guns during first and second portions, respectively, of said vertical blanking intervals; means for sampling the beam current of each electron gun during said first and second portions and for generating first and second correction signals, respectively, for each electron gun in accordance with the sampled values; and means for applying said first and second correction signals to their respective electron guns so as to balance the screen color temperature of said cathode ray tube.
Claim 14
Dependent Claim
22 words
The system as defined by claim 11 wherein said first and second correction signals are applied to grids of said electron guns.
Claim 15
Dependent Claim
23 words
The system as defined by claim 12 wherein means are provided for maintaining the correction signals during the intervals between successive test signals.
Claim 16
Dependent Claim
23 words
The system as defined by claim 11 wherein means are provided for maintaining the correction signals during the intervals between successive test signals.
Claim 17
Dependent Claim
22 words
The system as defined by claim 11 wherein said first and second test signals are at white and black level video, respectively.
Claim 18
Dependent Claim
27 words
The system as defined by claim 15 wherein said first correction signal is applied as a multiplying factor to each of said plurality of television video signals.
Claim 19
Dependent Claim
26 words
The system as defined by claim 16 wherein the corrected plurality of television video signals are applied to the control grids of their respective electron guns.
Claim 20
Dependent Claim
25 words
The system as defined by claim 16 wherein the corrected plurality of television video signals are applied to the cathodes of their respective electron guns.
Claim 21
Dependent Claim
24 words
The system as defined by claim 16 wherein said second correction signals are applied as DC reference levels to the corrected television video signals.
Claim 22
Dependent Claim
29 words
The system as defined by claim 11 wherein said means for sampling the beam current comprises a plurality of resistors in series with the cathode of said electron guns.
References Cited (Backward Citations)
US3479449A
Cited
US3612756A
Cited
US3602642A
Cited
US3735029A
Cited
US3855614A
Cited
US3873767A
Cited
US3898381A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-03-14 | 1980-09-13 | 1981-03-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-03-14 | 1984-09-13 | 1985-03-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-03-14 | 1988-09-13 | 1989-03-15 | $7700.00 | Window Closed / Lapsed |