US3743770A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatic aperture corrector
Assignee: Singer Co
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Filing: 1971-08-02
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Granted: 1973-07-03
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Expires: 1991-08-02
Abstract
Abstract An automatic aperture correction circuit for a television camera using two transistors with matched RC time constant networks to provide for high frequency gain with little or no phase shift and also including a varicap diode whose capacitance is controlled by the target voltage to automatically regulate the amount of correction as a function of light level.
Inventors
- 👤 N Vidovic
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 01:55
CPC Classifications
H; H04; H04N; H04N5/00; H04N5/14; H04N5/20; H04N5/205; H04N5/208
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
196 words
An aperture correction circuit for a video signal in television camera comprising: a. a first transistor having the video signal provided as an input through a first capacitor to its base and through a second capacitor to a junction of first and second resistors connecting its emitter to ground, the output of said transistor being taken from its collector, said collector being connected through a third resistor to a voltage source; b. fourth and fifth resistors connected in series between said voltage source and ground and having their junction connected to the base of said first transistor; c. a third capacitor in parallel with said first and second resistors; and d. a second transistor having its base input connected to the output of said first transistor and having its emitter connected through a sixth resistor and fourth capacitor in parallel to said voltage source and its collector connected to ground through a seventh resistor, the output of said circuit being taken from said collectors; the time constant of said fourth capacitor times said sixth resistor being equal to the time constant of said first capacitor times the resistance of said fourth and fifth resistors in parallel.
Claim 2
Dependent Claim
196 words
An aperture correction circuit for a video signal in television camera comprising: a. a first transistor having the video signal provided as an input through a first capacitor to its base and through a second capacitor to a junction of first and second resistors connecting its emitter to ground, the output of said transistor being taken from its collector, said collector being connected through a third resistor to a voltage source; b. fourth and fifth resistors connected in series between said voltage source and ground and having their junction connected to the base of said first transistor; c. a third capacitor in parallel with said first and second resistors; and d. a second transistor having its base input connected to the output of said first transistor and having its emitter connected through a sixth resistor and fourth capacitor in parallel to said voltage source and its collector connected to ground through a seventh resistor, the output of said circuit being taken from said collectors; the time constant of said fourth capacitor times said sixth resistor being equal to the time constant of said first capacitor times the resistance of said fourth and fifth resistors in parallel.
Claim 3
Dependent Claim
14 words
The invention according to claim 1 wherein said voltage source is a positive Voltage.
Claim 4
Dependent Claim
25 words
The invention according to claim 1 and further including a low pass filter interposed between said video input signal and said first and second capacitors.
Claim 5
Dependent Claim
63 words
The invention according to claim 3 wherein said filter comprises a pi network comprising an inductor having fifth and sixth capacitors connecting its ends to ground and an input resistor equal in value to said first and second resistors in parallel connected to one end of said inductor and having its output to said first and second capacitors taken from the other end.
Claim 6
Dependent Claim
63 words
The invention according to claim 1 wherein said third capacitor comprises a reverse biased varicap diode in series with a coupling capacitor, of a size two orders of magnitude larger, connected between said diode and the emitter of said first transistor, and the junction of said diode and capacitor is connected through an eigth resistor to the target voltage of the television camera.
References Cited (Backward Citations)
US3421101A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-07-02 | 1977-01-01 | 1977-07-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-07-02 | 1981-01-01 | 1981-07-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-07-02 | 1985-01-01 | 1985-07-03 | $7700.00 | Window Closed / Lapsed |