US4101932A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Video preamplifier for camera operated in act mode
Assignee: Harris Corp
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Filing: 1977-10-06
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Granted: 1978-07-18
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Expires: 1997-10-06
Abstract
Abstract A video preamplifier for use in television cameras which have imaging tubes operated in an ACT mode. Circuitry is provided for sensing and amplifying the video signal without substantial interference from the large white pulses which are inherently part of the video signal of ACT operated imaging tubes. Two or more amplification stages are included with a clipping circuit interposed between them. The clipping circuit works only on relatively large signals and thus discriminately blocks the major portion of the white pulse while passing the remainder of the video signal without disturbance. Overloading problems in later amplification stages are thus substantially avoided.
Inventors
- 👤 Joseph F. Wiggin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 00:16
CPC Classifications
H; H04; H04N; H04N23/00; H04N23/40
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
125 words
An improved video preamplifier for use in a television camera having an imaging tube operated in an ACT mode for producing a video signal having large signal, unsuppressed white pulses interspersed periodically thereon due to said ACT operation, said imaging tube having a video output circuit, said improved video preamplifier comprising: first amplifier means serially connected to said video output circuit for providing first amplification of said video signal, including said unsuppressed white pulses, without being overdriven thereby; second amplifier means serially connected to said first amplifier means for second amplification of said video signal; and, clipping circuit means interposed between said first amplifier means and said second amplifier means for clipping said large signal white pulses to prevent overdriving of said second amplifier means.
Claim 2
Dependent Claim
125 words
An improved video preamplifier for use in a television camera having an imaging tube operated in an ACT mode for producing a video signal having large signal, unsuppressed white pulses interspersed periodically thereon due to said ACT operation, said imaging tube having a video output circuit, said improved video preamplifier comprising: first amplifier means serially connected to said video output circuit for providing first amplification of said video signal, including said unsuppressed white pulses, without being overdriven thereby; second amplifier means serially connected to said first amplifier means for second amplification of said video signal; and, clipping circuit means interposed between said first amplifier means and said second amplifier means for clipping said large signal white pulses to prevent overdriving of said second amplifier means.
Claim 3
Dependent Claim
42 words
An improved video preamplifier as set forth in claim 1 wherein said clipping circuit means comprises biasing means for establishing a fixed clipping voltage, and semiconductor means responsive to said biasing means for clipping said video signal at said fixed clipping voltage.
Claim 4
Dependent Claim
82 words
An improved video preamplifier as set forth in claim 2 wherein said semiconductor means comprises a diode having an anode and a cathode, said anode being connected to the input of said second amplifier means together with said biasing means, and said cathode being connected to the output of said first amplifier means whereby said diode is normally forward biased by said biasing means but becomes reverse biased when the output signal of said first amplifier means rises above said clipping voltage.
Claim 5
Dependent Claim
39 words
An improved video preamplifier as set forth in claim 1 wherein said first amplifier means has a very high input resistance and low input capacitance whereby the signal-to-noise ratio and frequency response of said improved video preamplifier are maximized.
Claim 6
Dependent Claim
57 words
An improved video preamplifier as set forth in claim 3 wherein said biasing means comprises a resistive voltage divider having two resistors connected in series between ground potential and a fixed voltage, with the junction of said two resistors being connected to said anode of said diode and also to the input of said second amplifier means.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-07-17 | 1982-01-16 | 1982-07-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-07-17 | 1986-01-16 | 1986-07-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-07-17 | 1990-01-16 | 1990-07-18 | $7700.00 | Window Closed / Lapsed |