US4050085A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatic light control system
Assignee: Raytheon Co
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Filing: 1969-06-04
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Granted: 1977-09-20
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Expires: 1989-06-04
Abstract
Abstract A system to automatically regulate input light and television camera tube gain to maximize scene viewing continuity while protecting against overloads. An electro-optical input assembly, an image intensifier, SEC vidicon and video pre-amplifier produce required video signals. The signals are fed along a common path comprising a keyed clamp and field gating circuit, parallelly connected peak and average detectors, detector output weighting, amplifying and attenuator circuits. The path branches to a control function stage and a high voltage power supply to form a fast vidicon accelerating voltage adjusting loop. The path also branches to iris threshold and dead zone stages, to cause an iris motor to control the iris position in accordance with ambient durational and transient light conditions.
Inventors
- 👤 Paul R. Prince
- 👤 Bernard J. Skehan
- 👤 Jay M. Hansen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 14:07
CPC Classifications
H; H04; H04N; H04N23/00; H04N23/70; H04N23/72
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
166 words
An electro-optical system comprising: a. a lens system having an iris diaphragm, b. a television camera to convert light energy to video output signals, c. said television camera further comprising a non-linear gain determining element, d. a first feedback loop responsive to said video output signals to stably control said gain determining element to provide optimum operation below overloading of said camera said first loop including a compensating circuit having a non linearity substantially inverse to said non-linear gain of said non-linear gain determining element, e. a second feedback loop responsive to said video output signals to adjust said iris diaphragm to admit an amount of light energy for optimum video output signals below overloading of said camera, and, f. a dead zone circuit to inhibit actuation of said second feedback loop from adjusting said iris diaphragm until the energy in said video output signals changes a predetermined increment above or below a level of energy set for said optimum operation below overloading of said camera.
Claim 2
Dependent Claim
166 words
An electro-optical system comprising: a. a lens system having an iris diaphragm, b. a television camera to convert light energy to video output signals, c. said television camera further comprising a non-linear gain determining element, d. a first feedback loop responsive to said video output signals to stably control said gain determining element to provide optimum operation below overloading of said camera said first loop including a compensating circuit having a non linearity substantially inverse to said non-linear gain of said non-linear gain determining element, e. a second feedback loop responsive to said video output signals to adjust said iris diaphragm to admit an amount of light energy for optimum video output signals below overloading of said camera, and, f. a dead zone circuit to inhibit actuation of said second feedback loop from adjusting said iris diaphragm until the energy in said video output signals changes a predetermined increment above or below a level of energy set for said optimum operation below overloading of said camera.
Claim 3
Dependent Claim
69 words
The electro-optical system of claim 1 wherein said first and second feedback loops comprise a detector responsive to said video output signals to rapidly provide a corresponding light control level, and a switchable field gate to selectively present a low output impedance in switch closed condition and to present a substantially open circuit to said detector means in switch open condition to provide an average over the switchable field.
Claim 4
Dependent Claim
66 words
The electro-optical system of claim 1 wherein said first feedback loop comprises: power supply means to supply voltage to said gain determining element to provide camera operation accordingly, and non-linear control function means to regulate said power supply means for non-linear control of said gain determining element to provide camera operation at a point for optimum signal to noise ratio, resolution, stability, and camera tube protection.
Claim 5
Dependent Claim
56 words
The electro-optical system of claim 3 wherein said non-linear control function means comprises: means saturable at low level input to cause early shifting of said power supply means to provide high operating voltage level output to said gain determining element to thereby provide gain at low input light levels with a high signal to noise ratio.
Claim 6
Dependent Claim
45 words
The electro-optical system of claim 1 further comprising: a. iris motor shaft means to position said iris diaphragm, and b. cam means to provide approximately linear logarithmic increasing and attenuation of light admitted by said iris diaphragm with variation of angular position of said shaft.
Claim 7
Dependent Claim
121 words
The electro-optical system of claim 1, and further comprising: an electrical path common to said first and second loops, said path including: keyed clamp means responsive to said video output from said camera to reestablish the level of said video output signals, video peak and video average detectors each responsive to video output from said keyed clamp means to provide an output voltage level indicative of the strength of said video output signals, adjustable weighting function means connected to the outputs of said video peak and video average detectors to provide a composite output voltage level between the average level and peak level, and attenuator means responsive to said composite output voltage level to provide an adjustable light control voltage level.
Claim 8
Dependent Claim
87 words
The electro-optical system of claim 6, said common electrical path further including: a field gate switch coupled between the output of said keyed clamp means and the input to said video peak and video average detectors to present low impedance to said detector means in periods of switch closed condition and to present high, substantially open, impedance to said detector means in periods of switch open condition to enable a true average output of said field gate switches to be selected independently of the time of gating.
Claim 9
Dependent Claim
135 words
An electro-optical system comprising: a lens system having an iris diaphragm, a television camera to convert light energy to video output signals, said television camera further comprising a gain determining element, a first feedback loop responsive to said video output signals to stably control said gain determining element to provide optimum operation below overloading of said camera, a second feedback loop responsive to said video output signals to adjust said iris diaphragm to admit an amount of light energy for optimum video output signals below overloading of said camera, a first concentrically graded neutral density filter, a second neutral density filter having a transmission of the order of negative powers of ten, and means to mechanically couple said second neutral density filter for insertion into and out of the light path of said lens system.
Claim 10
Dependent Claim
135 words
An electro-optical system comprising: a lens system having an iris diaphragm, a television camera to convert light energy to video output signals, said television camera further comprising a gain determining element, a first feedback loop responsive to said video output signals to stably control said gain determining element to provide optimum operation below overloading of said camera, a second feedback loop responsive to said video output signals to adjust said iris diaphragm to admit an amount of light energy for optimum video output signals below overloading of said camera, a first concentrically graded neutral density filter, a second neutral density filter having a transmission of the order of negative powers of ten, and means to mechanically couple said second neutral density filter for insertion into and out of the light path of said lens system.
Claim 11
Dependent Claim
89 words
The electro-optical system of claim 8, and further comprising: a. position sensing means to provide an output representative of the position of said iris diaphragm, b. switching logic means enabled to be responsive to the output of said position sensing means to generate a signal when said position sensing means exceeds predetermined limits, and c. a neutral density filter actuator responsive to enabling of said switching logic means to selectively insert and remove said second mechanically coupled filter into and out of the light path through said lens system.
Claim 12
Dependent Claim
29 words
The electro-optical system of claim 1 wherein: a. said television camera comprises a secondary electron conduction vidicon, and b. said gain determining element comprises a secondary electron conduction photocathode.
Claim 13
Dependent Claim
144 words
A television system comprising: a. a first optical variable attenuation element, b. an image intensifier coupled to intensify the images passing through said optical variable attenuation element, c. an electronic variable gain element coupled to said image intensifier to convert the images from said image intensifer to electrical signals, d. means to detect said electrical signals to provide an automatic light control voltage, e. a first feedback loop comprising means rapidly responsive to said automatic light control voltage to control said electronic variable gain element to effect optimum gain operation below overloading of said gain element, and f. a second feedback loop comprising means less rapidly responsive to said automatic light control voltage than said first feedback loop to control said optical variable gain element to provide in conjunction with said first feedback loop a constant optimum illumination on said electronic variable gain element.
Claim 14
Dependent Claim
144 words
A television system comprising: a. a first optical variable attenuation element, b. an image intensifier coupled to intensify the images passing through said optical variable attenuation element, c. an electronic variable gain element coupled to said image intensifier to convert the images from said image intensifer to electrical signals, d. means to detect said electrical signals to provide an automatic light control voltage, e. a first feedback loop comprising means rapidly responsive to said automatic light control voltage to control said electronic variable gain element to effect optimum gain operation below overloading of said gain element, and f. a second feedback loop comprising means less rapidly responsive to said automatic light control voltage than said first feedback loop to control said optical variable gain element to provide in conjunction with said first feedback loop a constant optimum illumination on said electronic variable gain element.
Claim 15
Dependent Claim
69 words
The system of claim 11, said second feedback loop further comprising: a. threshold means responsive to said automatic light control voltage to provide a signal upon departure from its value during said optimum gain operation, and b. dead zone means responsive to exceeding of a predetermined increment by said departure signal to selectively actuate or inhibit varying of said optical variable gain element in accordance with said departure signal.
Claim 16
Dependent Claim
94 words
In a television system having a television camera tube to produce video output: a. a camera tube gain determining electrode, b. a source of camera tube operating voltage, c. means to couple said source to said electrode, d. means responsive to the video output to generate corresponding level signals, e. non-linear control function means saturable at low video output levels to regulate said source to provide rapid increase of source voltage coupled to said electrode so that maximum system gain is achieved before target current from said camera tube is reduced to low levels.
Claim 17
Dependent Claim
94 words
In a television system having a television camera tube to produce video output: a. a camera tube gain determining electrode, b. a source of camera tube operating voltage, c. means to couple said source to said electrode, d. means responsive to the video output to generate corresponding level signals, e. non-linear control function means saturable at low video output levels to regulate said source to provide rapid increase of source voltage coupled to said electrode so that maximum system gain is achieved before target current from said camera tube is reduced to low levels.
Claim 18
Dependent Claim
91 words
In a television system having a television camera tube to produce video output: a camera tube gain determining electrode, a source of camera tube operating voltage, means to couple said source to said electrode, means responsive to the video output to generate the corresponding level signals, and non-linear control function means saturable at low video output levels to regulate said source to provide an increase of source voltage coupled to said electrode so that maximum system gain is achieved before target current from said camera tube is reduced to low levels.
Claim 19
Dependent Claim
91 words
In a television system having a television camera tube to produce video output: a camera tube gain determining electrode, a source of camera tube operating voltage, means to couple said source to said electrode, means responsive to the video output to generate the corresponding level signals, and non-linear control function means saturable at low video output levels to regulate said source to provide an increase of source voltage coupled to said electrode so that maximum system gain is achieved before target current from said camera tube is reduced to low levels.
Claim 20
Dependent Claim
34 words
The system of claim 11 in which said first optical variable attenuation element comprises an iris having a mechanical control, in which the attenuation vs position of said control has a linear log characteristic.
Claim 21
Dependent Claim
62 words
The system recited in claim 11 in which said electronic variable gain element comprises an SEC vidicon, and said means rapidly responsive to said automatic light control voltage comprises a power supply connected to control the cathode voltage of said vidicon, and a power supply control function circuit connected to receive said automatic light control voltage and to control said power supply.
Claim 22
Dependent Claim
70 words
Apparatus as recited in claim 18 in which said power supply control function circuit comprises: a direct coupled amplifier with a non-linear limiting circuit at one extreme and a cutoff circuit at the other extreme, the non-linearity of said control function circuit being adjusted substantially to compensate for the non-linearities of said vidicon to cause the gain of said vidicon to vary inversely and linearly with said light control voltage.
Claim 23
Dependent Claim
92 words
Apparatus as recited in claim 16 in which said power supply control function circuit comprises: a direct coupled amplifier; first, substantially constant, feedback means from the output to the input of said amplifier; first non-linear means, including a first non-linear valve, connected between the output and input of said amplifier, said valve being adjustable to control the threshold of said amplifier; and second non-linear means connected between the output and the input of said amplifier, including a second non-linear valve, said second valve being adjustable to control the saturation of said amplifier.
Claim 24
Dependent Claim
131 words
Apparatus as recited in claim 17 in which: said first non-linear means comprises a resistor-diode circuit in series with the emitter-collector path of a first transistor, the base of said first transistor being connected to an adjustable, diode, circuit and to sources of biasing voltage to adjust the threshold of said amplifier; and said second non-linear means comprises a diode in series with the collector-emitter path of a second transistor, the base of said second transistor being connected to a second adjustable, diode, biasing circuit including a voltage source to control the saturation of said amplifier; the diodes and transistor of said first non-linear means being oppositely poled, from the output to the input of said amplifier, relative to the polarity of said diode and transistor of said second non-linear means.
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) | 1980-09-19 | 1981-03-21 | 1981-09-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-09-19 | 1985-03-21 | 1985-09-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-09-19 | 1989-03-21 | 1989-09-20 | $7700.00 | Window Closed / Lapsed |