US3743883A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Photodiode apparatus for reducing beam drift of a cathode ray tube display system
Assignee: Fairchild Semiconductor Corp
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Filing: 1971-01-15
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Granted: 1973-07-03
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Expires: 1991-01-15
Abstract
Abstract Apparatus for detecting and correcting drift and position errors of an electron beam due to electrical transients or mechanical vibration in a cathode ray tube display system including a diode array located in the path of the scanning electron beam. When the beam is properly directed, a predetermined output signal matrix from the diode array indicates that the beam is on target; if the beam drifts, a different output signal matrix indicates such drift and a servomechanism coupled to the diode array and to the beam deflection circuitry corrects the deflection of the beam in response to signals from the diode array.
Inventors
- 👤 J Burns
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 00:08
CPC Classifications
H; H04; H04N; H04N3/00; H04N3/10; H04N3/16; H04N3/22
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
183 words
Apparatus for detecting and correcting drift of an electron beam in a cathode ray tube display system having conventional beam deflection circuitry, comprising: a diode array means placed substantially adjacent the useable face area of a cathode ray tube in an area scanned by the electron beam such that said diode array produces directly a first set of predetermined output signals when said beam is properly directed and is substantially free from drift, but produces any one of a plurality of different sets of output signals if said beam has drifted off target, the change in sets of output signals being directly a result of said beam striking or failing to strike one or more diodes which normally would not have been struck, or which normally would have been struck, respectively, by said beam if said beam were on target; and means coupled to said beam deflection circuitry for correcting the deflection of said beam in response to signals from said diode array indicating said beam has drifted off target, thereby reducing beam drift and improving the beam deflection accuracy of the system.
Claim 2
Dependent Claim
183 words
Apparatus for detecting and correcting drift of an electron beam in a cathode ray tube display system having conventional beam deflection circuitry, comprising: a diode array means placed substantially adjacent the useable face area of a cathode ray tube in an area scanned by the electron beam such that said diode array produces directly a first set of predetermined output signals when said beam is properly directed and is substantially free from drift, but produces any one of a plurality of different sets of output signals if said beam has drifted off target, the change in sets of output signals being directly a result of said beam striking or failing to strike one or more diodes which normally would not have been struck, or which normally would have been struck, respectively, by said beam if said beam were on target; and means coupled to said beam deflection circuitry for correcting the deflection of said beam in response to signals from said diode array indicating said beam has drifted off target, thereby reducing beam drift and improving the beam deflection accuracy of the system.
Claim 3
Dependent Claim
48 words
The apparatus of claim 1 further characterized by said cathode ray display system having a portion of the face of the cathode ray tube exposed to viewing and a portion thereof blocked from view, the diode array means being placed in said portion which is blocked from view.
Claim 4
Dependent Claim
47 words
The apparatus of claim 1 further characterized by said diode array means being placed such that said electron beam fails to strike any of said diodes when said beam is on target, but strikes one or more of said diodes when said beam has drifted off target.
Claim 5
Dependent Claim
44 words
The apparatus of claim 3 further characterized by the addition of at least one more diode, said additional diode providing a positive output signal when said beam is on target and failing to provide such a signal when said beam has drifted off target.
Claim 6
Dependent Claim
18 words
The apparatus of claim 3 further characterized by said diode array means providing focus and astigmatism correction signals.
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) | 1976-07-02 | 1977-01-01 | 1977-07-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-07-02 | 1981-01-01 | 1981-07-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-07-02 | 1985-01-01 | 1985-07-03 | $7700.00 | Window Closed / Lapsed |