US3600511A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for controlling the operating potential of a vidicon
Assignee: RCA Licensing Corp
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Filing: 1969-07-03
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Granted: 1971-08-17
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Expires: 1989-07-03
Abstract
Abstract The video signal derived from a vidicon target electrode, after preamplification, is applied to the control gate input electrode of a field effect transistor where it is clamped by a pair of diodes and where combined horizontal and vertical blanking pulses are added to it by another diode at the transistor drain electrode and a pedestal component derived from a pedestal control circuit is added at the transistor source electrode to produce a clamped composite signal. The composite signal is clipped at a fixed level by a series diode coupled between the drain electrode of the field effect transistor and the base electrode of an emitter follower transistor, the emitter electrode being coupled to an output amplifier and to the input transistor of a peak detector including a diode and a second field effect transistor, the source output electrode of which is coupled to a transistor which supplies the operating potential for the vidicon target electrode through a coupling circuit comprising a capacitor and having a first branch including a relatively small value resistor and a diode which is forward biased for operating potential decreases, thereby forming with the capacitor a short time constant, fast reacting circuit; the coupling circuit having a second branch including a relatively large value resistor which forms with the capacitor a long time constant, slow recovery circuit for operating potential increases which reverse bias the diode. The vidicon target electrode operating potential also is applied to the input gate electrode of a third field effect transistor having an output source electrode which is coupled to the pedestal control circuit.
Inventors
- 👤 John Andrew Cooksey
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 21:58
CPC Classifications
H; H04; H04N; H04N5/00; H04N5/14; H04N5/16; H04N5/18; H04N5/185; H04N23/00; H04N23/70; H04N23/749
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
172 words
In a television system including a pickup tube having a photoconductive video signal producing electrode, an automatic control system for said pickup tube comprising: control signal developing means for producing, from said video signal derived from said pickup tube electrode, a first control signal having an amplitude varying directly with amplitude changes of said produced video signal resulting from variations of said subject illumination; voltage-developing means responsive to said variable amplitude first control signal for developing a video signal producing electrode operating potential varying in magnitude inversely to amplitude variations of said first control signal; and means including a coupling circuit having an input terminal coupled to said voltage developing means and an output terminal coupled to said pickup tube electrode for applying said operating potential to said electrode, said coupling circuit having a relatively fast reaction time in applying magnitude decreases of said developed operating potential to said pickup tube electrode and a relatively slow recovery time in applying magnitude increases of said developed operating potential to said pickup tube electrode.
Claim 2
Dependent Claim
172 words
In a television system including a pickup tube having a photoconductive video signal producing electrode, an automatic control system for said pickup tube comprising: control signal developing means for producing, from said video signal derived from said pickup tube electrode, a first control signal having an amplitude varying directly with amplitude changes of said produced video signal resulting from variations of said subject illumination; voltage-developing means responsive to said variable amplitude first control signal for developing a video signal producing electrode operating potential varying in magnitude inversely to amplitude variations of said first control signal; and means including a coupling circuit having an input terminal coupled to said voltage developing means and an output terminal coupled to said pickup tube electrode for applying said operating potential to said electrode, said coupling circuit having a relatively fast reaction time in applying magnitude decreases of said developed operating potential to said pickup tube electrode and a relatively slow recovery time in applying magnitude increases of said developed operating potential to said pickup tube electrode.
Claim 3
Dependent Claim
55 words
A television pickup tube automatic control system as defined in claim 1, wherein: said coupling circuit comprises a diode, capacitor and resistor network having a relatively short time constant in response to said decreases of said developed operating potential and a relatively long time constant in response to said increases of said developed operating potential.
Claim 4
Dependent Claim
64 words
A television pickup tube automatic control system as defined in claim 2, wherein: said network comprises a capacitor connected to said output terminal effectively in shunt with said pickup tube video signal producing electrode; a first resistor connected between said output and input terminals of said network; and a second resistor and a diode connected in series between said input and output network terminals.
Claim 5
Dependent Claim
148 words
A television pickup tube automatic control system as defined in claim 3, wherein: said second resistor has a relatively small value; said diode is connected in such polarity that it is forward biased in response to increases of said first control signal amplitude which produce decreases in the operating potential of said pickup tube video signal producing electrode, thereby providing said network with said relatively short time constant and enabling said fast reaction time in decreasing said operating potential of said pickup tube electrode for amplitude increases of said video signal, said diode being reverse biased in response to decreases of said first control signal amplitude; and said second resistor has a relatively large value, thereby providing said network with said relatively long time constant and enabling said slow recovery time in increasing said operating potential of said pickup tube electrode for amplitude decreases of said video signal.
Claim 6
Dependent Claim
184 words
A television pickup tube automatic control system as defined in claim 4, wherein; a composite Signal is derived from the photoconductive signal-producing electrode of said pickup tube including the subject representative video signal component and a dark current component which is produced even in the absence of any illumination of said electrode; pedestal-inserting means for adding to said composite signal a pedestal component having a normal amplitude equal to the difference between said composite signal representing subject black and including said dark current component under normal subject illumination and a clipping level, said dark current component and, hence, said pedestal component amplitudes varying directly with variations of said operating potential of said pickup tube electrode; clipping means coupled to said pedestal inserting means for clipping said composite signal obtained therefrom at said clipping level; and automatic pedestal amplitude-controlling means responsive to a second control signal derived from said pickup tube electrode operating potential for varying said pedestal component amplitude inversely to said electrode-operating potential variations to restore said pedestal component substantially to its normal amplitude, thereby effectively nullifying said dark current component amplitude variations.
Claim 7
Dependent Claim
109 words
A television pickup tube automatic control system as defined in claim 5, wherein: said pedestal-inserting means includes normal amplitude-controlling means comprising a potentiometer and a fixed resistor connected as a first voltage divider to a source of unidirectional potential, said potentiometer being adjusted to establish said normal pedestal component amplitude; and said automatic pedestal amplitude controlling means comprising a transistor having an input electrode connected for response to said second control signal and an output electrode connected to the junction point of said potentiometer and said fixed resistor of said pedestal inserting means to effectively alter the adjustment of said potentiometer, thereby changing the amplitude of said pedestal component.
Claim 8
Dependent Claim
78 words
A television pickup tube automatic control system as defined in clam 6, wherein: said second control signal is derived from said pickup tube electrode operating potential by means comprising a second voltage divider connected to the output terminal of said coupling circuit to said pickup tube electrode and including a variable resistor and at least one fixed resistor; and means including said variable resistor and at least one fixed to establish the amplitude of said second control signal.
Claim 9
Dependent Claim
78 words
A television pickup tube automatic control system as defined in clam 6, wherein: said second control signal is derived from said pickup tube electrode operating potential by means comprising a second voltage divider connected to the output terminal of said coupling circuit to said pickup tube electrode and including a variable resistor and at least one fixed resistor; and means including said variable resistor and at least one fixed to establish the amplitude of said second control signal.
Claim 10
Dependent Claim
49 words
A television pickup tube automatic control system as defined in claim 7, and additionally including; means for clamping said signal derived from said pickup tube electrode at a predetermined voltage level; and means for peak detecting said signal relative to said clamping level to develop said first control signal.
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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) | 1974-08-16 | 1975-02-15 | 1975-08-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-08-16 | 1979-02-15 | 1979-08-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-08-16 | 1983-02-15 | 1983-08-17 | $7700.00 | Window Closed / Lapsed |