US4414574A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Video amplifier with blank stretching
Assignee: Electrohome Ltd
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Filing: 1981-12-04
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Granted: 1983-11-08
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Expires: 2001-12-04
Abstract
Abstract A video amplifier is provided whose mode of operation varies depending on the level of the video signal from a condition where maximum positive voltage is applied to the cathode of the cathode ray tube (CRT) to ensure blanking, through operation as a differential amplifier, and finally to operation as a common emitter amplifier over the full brightness level range of the display on the CRT screen.
Inventors
- 👤 Harry W. Verlinden
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 21:52
CPC Classifications
H; H03; H03F; H03F3/00; H03F3/45; H03F3/45071; H04; H04N; H04N5/00; H04N5/14; H04N5/148
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
187 words
A video amplifier comprising first and second NPN transistors having base, collector and emitter electrodes; means connecting said collector electrode of said first transistor to a source of positive potential via a first resistor; means connecting said collector electrode of said second transistor to a source of positive pontential; means for connecting said emitter electrode to each other and via a first resistive network to a source of negative potential and via a second resistive network including a variable resistor to a terminal at a potential less positive than said positive potentials and less negative than said negative potential; a network for biasing on said second transistor connected to said base electrode of said second transistor; an input terminal connected to the base electrode of said first transistor; means for supplying to said input terminal a video input signal varying between a blanking level, a black level and a maximum brightness level, the maximum brightness level being more positive than the black level and the black level being more positive than the blanking level; and an output terminal connected to said collector electrode of said first transistor.
Claim 2
Dependent Claim
187 words
A video amplifier comprising first and second NPN transistors having base, collector and emitter electrodes; means connecting said collector electrode of said first transistor to a source of positive potential via a first resistor; means connecting said collector electrode of said second transistor to a source of positive pontential; means for connecting said emitter electrode to each other and via a first resistive network to a source of negative potential and via a second resistive network including a variable resistor to a terminal at a potential less positive than said positive potentials and less negative than said negative potential; a network for biasing on said second transistor connected to said base electrode of said second transistor; an input terminal connected to the base electrode of said first transistor; means for supplying to said input terminal a video input signal varying between a blanking level, a black level and a maximum brightness level, the maximum brightness level being more positive than the black level and the black level being more positive than the blanking level; and an output terminal connected to said collector electrode of said first transistor.
Claim 3
Dependent Claim
187 words
A video amplifier comprising first and second NPN transistors having base, collector and emitter electrodes; means connecting said collector electrode of said first transistor to a source of positive potential via a first resistor; means connecting said collector electrode of said second transistor to a source of positive potential; means for connecting said emitter electrodes to each other and via a first resistive network including a variable resistor to a source of negative potential and via a second resistive network to a terminal at a potential less positive than said positive potentials and less negative than said negative potential; a network for biasing on said second transistor connected to said base electrode of said second transistor; an input terminal connected to the base electrode of said first transistor; means for supplying to said input terminal a video input signal varying between a blanking level, a black level and a maximum brightness level, the maximum brightness level being more positive than the black level and the black level being more positive than the blanking level; and an output terminal connected to said collector electrode of said first transistor.
Claim 4
Dependent Claim
187 words
A video amplifier comprising first and second NPN transistors having base, collector and emitter electrodes; means connecting said collector electrode of said first transistor to a source of positive potential via a first resistor; means connecting said collector electrode of said second transistor to a source of positive potential; means for connecting said emitter electrodes to each other and via a first resistive network including a variable resistor to a source of negative potential and via a second resistive network to a terminal at a potential less positive than said positive potentials and less negative than said negative potential; a network for biasing on said second transistor connected to said base electrode of said second transistor; an input terminal connected to the base electrode of said first transistor; means for supplying to said input terminal a video input signal varying between a blanking level, a black level and a maximum brightness level, the maximum brightness level being more positive than the black level and the black level being more positive than the blanking level; and an output terminal connected to said collector electrode of said first transistor.
Claim 5
Dependent Claim
16 words
A video amplifier according to claim 2 wherein said second resistive network includes a variable resistor.
References Cited (Backward Citations)
US3458652A
Cited
DE2347192A1
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-11-07 | 1987-05-09 | 1987-11-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-11-07 | 1991-05-09 | 1991-11-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-11-07 | 1995-05-09 | 1995-11-08 | $7700.00 | Window Closed / Lapsed |