US4037133A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Compensation of cathode ray tube for moire
Assignee: Electrohome Ltd
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Filing: 1976-04-12
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Granted: 1977-07-19
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Expires: 1996-04-12
Abstract
Abstract In a video signal receiving apparatus that employs tracking focus moire is eliminated by preventing the DC voltage of the focus electrode from increasing beyond the critical level at which moire will occur.
Inventors
- 👤 John Joseph Sennik
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 09:23
CPC Classifications
H; H04; H04N; H04N3/00; H04N3/10; H04N3/16; H04N3/26; H04N5/00; H04N5/14; H04N5/21
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
109 words
In a video signal receiving apparatus of a type having a cathode ray tube with a focus electrode, and means for supplying a DC voltage to said focus electrode, said DC voltage varying in response to changes in the beam current of said cathode ray tube in a direction to maintain the electron beam of said cathode ray tube focused, the improvement comprising means responsive to said DC voltage reaching a critical level where a further increase thereof will result in moire for maintaining said DC voltage below said critical level despite any additional changes in said beam current tending to increase said DC voltage above said critical level.
Claim 2
Dependent Claim
109 words
In a video signal receiving apparatus of a type having a cathode ray tube with a focus electrode, and means for supplying a DC voltage to said focus electrode, said DC voltage varying in response to changes in the beam current of said cathode ray tube in a direction to maintain the electron beam of said cathode ray tube focused, the improvement comprising means responsive to said DC voltage reaching a critical level where a further increase thereof will result in moire for maintaining said DC voltage below said critical level despite any additional changes in said beam current tending to increase said DC voltage above said critical level.
Claim 3
Dependent Claim
74 words
The invention according to claim 1 wherein said cathode ray tube has a high voltage anode, said means for supplying a DC voltage comprising a high voltage power supply, said power supply being connected to said high voltage anode and having a sufficiently high internal impedance that the output voltage thereof varies in response to changes in the beam current of said cathode ray tube, thereby providing said DC voltage for said focus electrode.
Claim 4
Dependent Claim
51 words
The invention according to claim 2 wherein said means responsive to said DC voltage comprises a diode having anode and cathode electrodes, means for supplying said DC voltage to said anode and means for supplying to said cathode a DC voltage substantially equal to said DC voltage at said critical level.
Claim 5
Dependent Claim
100 words
In a video signal receiving apparatus of a type having a cathode ray tube with a focus electrode and a dynamic tracking focus network for varying the DC voltage supplied to said focus electrode in response to changes in the beam current of said cathode ray tube in a direction to maintain the electron beam of said cathode ray tube focused, the improvement comprising means for inhibiting operation of said dynamic tracking focus network when said DC voltage is about to exceed a critical value beyond which moire will occur and for keeping said DC voltage below said critical value.
Claim 6
Dependent Claim
100 words
In a video signal receiving apparatus of a type having a cathode ray tube with a focus electrode and a dynamic tracking focus network for varying the DC voltage supplied to said focus electrode in response to changes in the beam current of said cathode ray tube in a direction to maintain the electron beam of said cathode ray tube focused, the improvement comprising means for inhibiting operation of said dynamic tracking focus network when said DC voltage is about to exceed a critical value beyond which moire will occur and for keeping said DC voltage below said critical value.
References Cited (Backward Citations)
US3432718A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-07-18 | 1981-01-17 | 1981-07-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-07-18 | 1985-01-17 | 1985-07-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-07-18 | 1989-01-17 | 1989-07-19 | $7700.00 | Window Closed / Lapsed |