US3739178A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatic bright source protection circuit and power supply circuit for an image intensifier
Assignee: United States Department of the Army
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Filing: 1972-05-16
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Granted: 1973-06-12
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Expires: 1992-05-16
Abstract
Abstract A bright source protection circuit and regulated power supply for an image intensifier tube in which the amount of screen current is sensed at the gate of an enhanced mode FET and the FET, in turn, controls voltage regulated oscillators in which the outputs of the oscillators furnish bias voltages to the cathode, to the electrodes on the microchannel plate, and to the screen within the image intensifier wherein these bias voltages change inversely to any change in the screen current. Since screen current flows in direct proportion to the amount of illumination emanating from the source being viewed, the brightness of the source being viewed by an operator looking through the image intensifier remains constant at the output of the image intensifier tube. A clamping circuit between the cathode and the input electrode of a microchannel plate clamps the cathode operational voltage within the stable region of the cathode current-voltage characteristics. Pulsing outputs of the voltage controlled oscillators are transformer coupled to three voltage multipliers that provide separate direct current voltages to the cathode, to the input and to the output electrodes of a microchannel plate, and to the screen.
Inventors
- 👤 Te Chow Sen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 21:12
CPC Classifications
H; H01; H01J; H01J43/00; H01J43/04; H01J43/06; H01J43/18; H01J43/24; H01J43/246; H01J43/30; H04; H04N; H04N23/00; H04N23/70; H04N23/75
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
374 words
An automatic bright source protection and power supply circuit for holding the output of an image intensifier constant, the circuit comprising: a direct current voltage source; a microchannel plate power supply oscillator for converting said direct current voltage source at its input to an output alternating current voltage; a cathode and screen power supply oscillator for converting said direct current voltage source at its input to an output alternating current voltage; a first constant current source for supplying base current to said microchannel plate power supply oscillator; a second constant current source for supplying base current to said cathode and screen power supply oscillator; a first two-stage voltage multiplier for converting said alternating current voltage at the output of said cathode and screen power supply oscillator to a direct current voltage connected between said cathode and a microchannel; a second two-stage voltage multiplier for converting said alternating current voltage at the output of said microchannel plate power supply oscillator to a direct current voltage connected across the microchannel plate; a 10-stage voltage multiplier for converting said alternating current voltage at the output of said cathode and screen power supply oscillator to a direct current voltage that is applied to the screen of said image intensifier tube; a first transformer coupling means for coupling and amplifying the alternating current voltage output from said microchannel plate power supply oscillator to the input of said second twostage voltage multiplier and to the input of said first constant current source; a second transformer coupling means for coupling and amplifying the alternating current voltage output from said cathode and screen power supply oscillator to the inputs of said first twostage voltage miltiplier and said 10-stage voltage multiplier and to the input of said second constant current source; a clamping circuit connected between said cathode and the input to said microchannel plate for limiting the voltage therebetween to a value which limits the cathode to operate only in its stable region; and an automatic brightness control circuit wherein said automatic brightness control circuit monitors the amount of screen current and controls the direct current voltage input to the image intensifier inversely to the amount of screen current for keeping the screen current and the output of the image intensifier constant.
Claim 2
Dependent Claim
374 words
An automatic bright source protection and power supply circuit for holding the output of an image intensifier constant, the circuit comprising: a direct current voltage source; a microchannel plate power supply oscillator for converting said direct current voltage source at its input to an output alternating current voltage; a cathode and screen power supply oscillator for converting said direct current voltage source at its input to an output alternating current voltage; a first constant current source for supplying base current to said microchannel plate power supply oscillator; a second constant current source for supplying base current to said cathode and screen power supply oscillator; a first two-stage voltage multiplier for converting said alternating current voltage at the output of said cathode and screen power supply oscillator to a direct current voltage connected between said cathode and a microchannel; a second two-stage voltage multiplier for converting said alternating current voltage at the output of said microchannel plate power supply oscillator to a direct current voltage connected across the microchannel plate; a 10-stage voltage multiplier for converting said alternating current voltage at the output of said cathode and screen power supply oscillator to a direct current voltage that is applied to the screen of said image intensifier tube; a first transformer coupling means for coupling and amplifying the alternating current voltage output from said microchannel plate power supply oscillator to the input of said second twostage voltage multiplier and to the input of said first constant current source; a second transformer coupling means for coupling and amplifying the alternating current voltage output from said cathode and screen power supply oscillator to the inputs of said first twostage voltage miltiplier and said 10-stage voltage multiplier and to the input of said second constant current source; a clamping circuit connected between said cathode and the input to said microchannel plate for limiting the voltage therebetween to a value which limits the cathode to operate only in its stable region; and an automatic brightness control circuit wherein said automatic brightness control circuit monitors the amount of screen current and controls the direct current voltage input to the image intensifier inversely to the amount of screen current for keeping the screen current and the output of the image intensifier constant.
Claim 3
Dependent Claim
37 words
An automatic bright source protection and power supply circuit as set forth in claim 1 wherein said microchannel plate power supply socillator oscillator said cathode and screen power supply oscillator comprise base control voltage regulated N-P-N transistors.
Claim 4
Dependent Claim
46 words
An automatic bright source protection and power supply circuit as set forth in claim 2 wherein the input to said second two-stage voltage miltiplier from said first transformer coupling means is 300 to 500 peak-to-peak volts that is converted to 600 to 1,000 direct current volts.
Claim 5
Dependent Claim
42 words
An automatic bright source protection and power supply circuit as set forth in claim 3 wherein the input to said first two-stage voltage multiplier from said second transformer coupling means is 100 peak-to-peak volts that is converted to 200 direct current volts.
Claim 6
Dependent Claim
41 words
An antomatic bright source protection and power supply circuit as set forth in claim 4 wherein the input to said 10-stage voltage miltiplier from said second transformer coupling means is 500 peak-to-peak volts that is converted to 5,000 direct current volts.
Claim 7
Dependent Claim
68 words
An automatic bright source protection and power supply circuit as set forth in claim 5 wherein said automatic brightness control circuit comprises a FET having iTs gate connected to a sensing resistor that detects the amount of screen current and its source terminal at ground potential with its drain terminal connected to the base of said base control voltage regulated N-P-N transistor of said microchannel plate power oscillator.
Claim 8
Dependent Claim
111 words
An automatic bright source protection and power supply circuit as set forth in claim 6 wherein said clamping circuit comprises a cathode current limiting resistor connected between said cathode and said first two-stage voltage multiplier and a serially connected diode and resistor in parallel with said cathode current limiting resistor with a resistor connected between the input electrode of the microchannel plate and the junction of the serially connected diode and resistor for limiting the voltage between said cathode and the input electrode of said microchannel plate whereby any change in source brightness being viewed by said image intensifier tube does not change the cathode operating characteristic to an unstable condition.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-06-11 | 1976-12-11 | 1977-06-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-11 | 1980-12-11 | 1981-06-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-11 | 1984-12-11 | 1985-06-12 | $7700.00 | Window Closed / Lapsed |