US3924067A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatic beam current limiter with video hold-off
Assignee: Admiral Corp
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Filing: 1974-08-16
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Granted: 1975-12-02
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Expires: 1994-08-16
Abstract
Abstract An improved circuit for a television receiver which provides the combined function of limiting the brightness in the cathode ray tube and further including a turn-on delay which prevents the cathode ray tube from being injured due to high voltages being applied to the cathodes before they have had time to become sufficiently heated.
Inventors
- 👤 Blayne E Arneson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 07:41
CPC Classifications
H; H04; H04N; H04N5/00; H04N5/44; H04N5/57; H04N5/59
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
109 words
A circuit for automatic beam current limiting and video hold off for a television receiver including a cathode ray tube whose cathodes are unheated prior to turn on comprising, a power source, a video amplifier connected to supply drive to the cathode ray tube of said receiver, a brightness limiter means connected to said video amplifier to control its output, means for sensing the beam current in said cathode ray tube connected to said brightness limiter means to control its output, and time delay means connected to said brightness limiter means and said power source and delaying the application of power to said brightness limiter means at turn on.
Claim 2
Dependent Claim
109 words
A circuit for automatic beam current limiting and video hold off for a television receiver including a cathode ray tube whose cathodes are unheated prior to turn on comprising, a power source, a video amplifier connected to supply drive to the cathode ray tube of said receiver, a brightness limiter means connected to said video amplifier to control its output, means for sensing the beam current in said cathode ray tube connected to said brightness limiter means to control its output, and time delay means connected to said brightness limiter means and said power source and delaying the application of power to said brightness limiter means at turn on.
Claim 3
Dependent Claim
55 words
A circuit according to claim 1 wherein said brightness limiter means comprises a first transistor connected to control said video amplifier and said time delay means comprises a first resistor and a first capacitor connected across said power source and the control electrode of said first transistor coupled to said first resistor and said capacitor.
Claim 4
Dependent Claim
36 words
A circuit according to claim 2 including a second resistor connected between said means for sensing the beam current and said first resistor and the control electrode of said first transistor coupled to said second resistor.
Claim 5
Dependent Claim
29 words
A circuit according to claim 2 wherein said video amplifier comprises a second transistor with its collector-emitter circuit connected in series with the collector-emitter circuit of said first transistor.
Claim 6
Dependent Claim
65 words
A circuit according to claim 4 including a fourth resistor connected between said power source and said first capacitor and having a resistance substantially higher than said first resistor, and a diode coupled between said first capacitor and said control electrode of said first transistor for effectively disconnecting said first capacitor from said first transistor when said first capacitor has charged to a predetermined voltage.
Claim 7
Dependent Claim
23 words
A circuit according to claim 2 wherein said brightness limiter means includes a third transistor connected in Darlington fashion with said first transistor.
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) | 1978-12-01 | 1979-06-02 | 1979-12-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-01 | 1983-06-02 | 1983-12-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-01 | 1987-06-02 | 1987-12-02 | $7700.00 | Window Closed / Lapsed |