Patent US4897547A successfully refreshed from Google Patents.
US4897547A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Gate coupled input circuit
Assignee: Lockheed Martin Tactical Systems Inc
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Filing: 1986-09-26
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Granted: 1990-01-30
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Expires: 2006-09-26
Abstract
Abstract What is disclosed is a preamplifier used with each pyroelectric detector in an infrared imaging array system. The preamplifier transistor is a MOSFET transistor that can operate with zero volts between its source and gate terminals, and the preamplifier is biased either by a nonconducting diode that provides a high biasing impedance while the bias voltage is low enough to keep the diode below its conduction voltage; or an NPN transistor switch is periodically operated to place charge on the gate of the preamplifier transistor to maintain it at its bias level. When the bias transistor is not operated, the associated detector detects and a detector reading is taken from each detector in the array. NPN transistor switches can be manufactured consistently and their conduction level can be adjusted to balance the gain of all preamplifiers in the detector array.
Inventors
- 👤 Shigesato Iwasa
- 👤 Neal R. Butler
- 👤 Jeff L. McClelland
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 02:05
CPC Classifications
G; G01; G01J; G01J5/00; G01J5/48; G01J5/10; G01J5/28; G01J5/30; H; H04; H04N; H04N25/00; H04N25/20; H04N25/21
Claims Analysis
Total Claims: 30
Claim 1
Independent Claim
106 words
A circuit for use in a thermal imaging system comprising: an infrared detector for detecting an infrared signal impinging thereon, an amplifier having an input to which said detector is connected, and an output, said amplifier responding to said detector detecting an infrared signal to provide an amplified electrical signal representing said infrared signal at its output, and a diode connected in parallel with said detector, said diode always being operated in its nonconducting state and being used to bias both said detector and said amplifier, said nonconducting diode operating as a resistor having a resistance in the range of 10 12 to 10 15 ohms.
Claim 2
Dependent Claim
106 words
A circuit for use in a thermal imaging system comprising: an infrared detector for detecting an infrared signal impinging thereon, an amplifier having an input to which said detector is connected, and an output, said amplifier responding to said detector detecting an infrared signal to provide an amplified electrical signal representing said infrared signal at its output, and a diode connected in parallel with said detector, said diode always being operated in its nonconducting state and being used to bias both said detector and said amplifier, said nonconducting diode operating as a resistor having a resistance in the range of 10 12 to 10 15 ohms.
Claim 3
Dependent Claim
39 words
The invention in accordance with claim 1 further comprising: a transfer switch connected to the output of said amplifier, said transfer switch being operated to read out the amplified electrical signal representing said infrared signal impinging on said detector.
Claim 4
Dependent Claim
15 words
The invention in accordance with claim 2 wherein said detector is a temperature sensitive capacitor.
Claim 5
Dependent Claim
20 words
The invention in accordance with claim 3 wherein said detector is a pyroelectric detector utilizing lithium tantalate as the dielectric.
Claim 6
Dependent Claim
121 words
A circuit for use in a thermal imaging system comprising: an infrared detector for detecting an infrared signal impinging thereon, an amplifier having an input to which said detector is connected, and an output, said amplifier responding to said detector detecting an infrared signal to provide an amplified electrical signal representing said infrared signal at its output, and a bias bipolar transistor associated with and connected to the input of said amplifier, means for periodically operating said bias transistor to apply a voltage to said amplifier and said detector connected to the input thereof to charge them to a predetermined bias level, and said bias transistor then being disabled to permit said detector to detect said infrared signal impinging on it.
Claim 7
Dependent Claim
121 words
A circuit for use in a thermal imaging system comprising: an infrared detector for detecting an infrared signal impinging thereon, an amplifier having an input to which said detector is connected, and an output, said amplifier responding to said detector detecting an infrared signal to provide an amplified electrical signal representing said infrared signal at its output, and a bias bipolar transistor associated with and connected to the input of said amplifier, means for periodically operating said bias transistor to apply a voltage to said amplifier and said detector connected to the input thereof to charge them to a predetermined bias level, and said bias transistor then being disabled to permit said detector to detect said infrared signal impinging on it.
Claim 8
Dependent Claim
39 words
The invention in accordance with claim 5 further comprising: a transfer switch connected to the output of said amplifier, said transfer switch being operated to read out the amplified electrical signal representing said infrared signal impinging on said detector.
Claim 9
Dependent Claim
15 words
The invention in accordance with claim 6 wherein said detector is a temperature sensitive capacitor.
Claim 10
Dependent Claim
20 words
The invention in accordance with claim 7 wherein said detector is a pyroelectric detector utilizing lithium tantalate as the dielectric.
Claim 11
Dependent Claim
116 words
A circuit for use in a thermal imaging system comprising: an infrared detector for detecting an infrared signal impinging thereon, an amplifier having an input to which said detector is connected, and an output, said amplifier responding to said detector detecting an infrared signal to provide an amplified electrical signal representing said infrared signal at its output, and a bias transistor associated with and connected to the input of said amplifier, said bias transistor being operated as a switch to act as a high impedance resistor and being used to bias both said detector and said amplifier, said bias transistor operating as to have an impedance in the range of 10 12 to 10 15 ohms.
Claim 12
Dependent Claim
116 words
A circuit for use in a thermal imaging system comprising: an infrared detector for detecting an infrared signal impinging thereon, an amplifier having an input to which said detector is connected, and an output, said amplifier responding to said detector detecting an infrared signal to provide an amplified electrical signal representing said infrared signal at its output, and a bias transistor associated with and connected to the input of said amplifier, said bias transistor being operated as a switch to act as a high impedance resistor and being used to bias both said detector and said amplifier, said bias transistor operating as to have an impedance in the range of 10 12 to 10 15 ohms.
Claim 13
Dependent Claim
39 words
The invention in accordance with claim 9 further comprising a transfer switch connected to the output of said amplifier, said transfer switch being operated to read out the amplified electrical signal representing said infrared signal impinging on said detector.
Claim 14
Dependent Claim
15 words
The invention in accordance with claim 10 wherein said detector is a temperature sensitive capacitor.
Claim 15
Dependent Claim
20 words
The invention in accordance with claim 11 wherein said detector is a pyroelectric detector utilizing lithium tantalate as the dielectric.
Claim 16
Dependent Claim
156 words
A thermal imaging system upon which an infrared image is focused to be detected and to generate an electrical signal representing said image, said system comprising an array of a plurality of infrared detectors upon which said infrared image is focused for detecting said infrared image impinging thereon, said array being organized in rows and columns of closely spaced detectors, an amplifier associated with each of said detectors, each said amplifier having an input to which said detector is connected, and an output, said amplifiers responding to their associated detectors detecting an infrared image to provide an amplified electrical signal representing said infrared image at its output, and a diode connected in parallel with each of said detectors, said diodes always being operated in a nonconducting state and being used to bias said detectors and said amplifiers, said nonconducting diodes operating as resistors having a resistance in the range of 10 12 to 10 15 ohms
Claim 17
Dependent Claim
156 words
A thermal imaging system upon which an infrared image is focused to be detected and to generate an electrical signal representing said image, said system comprising an array of a plurality of infrared detectors upon which said infrared image is focused for detecting said infrared image impinging thereon, said array being organized in rows and columns of closely spaced detectors, an amplifier associated with each of said detectors, each said amplifier having an input to which said detector is connected, and an output, said amplifiers responding to their associated detectors detecting an infrared image to provide an amplified electrical signal representing said infrared image at its output, and a diode connected in parallel with each of said detectors, said diodes always being operated in a nonconducting state and being used to bias said detectors and said amplifiers, said nonconducting diodes operating as resistors having a resistance in the range of 10 12 to 10 15 ohms
Claim 18
Dependent Claim
46 words
The invention in accordance with claim 13 further comprising a transfer switch connected to the output of each of said amplifiers, said transfer switches being operated to read out the amplified electrical signal representing the portion of said infrared image impinging on each of said detectors.
Claim 19
Dependent Claim
14 words
The invention in accordance with claim 14 wherein said detectors are temperature sensitive capacitors.
Claim 20
Dependent Claim
19 words
The invention in accordance with claim 15 wherein said detectors are pyroelectric detectors utilizing lithium tantalate as the dielectric.
Claim 21
Dependent Claim
179 words
A thermal imaging system upon which an infrared image is focused to be detected and to generate an electrical signal representing said image, said system comprising: an array of a plurality of infrared detectors upon which said infrared image is focused for detecting said infrared image impinging thereon, said array being organized in rows and columns of closely spaced detectors, an amplifier associated with each of said detectors, each said amplifier having an input to which its associated detector is connected and each amplifier having an output, each said amplifier responding to its associated detector detecting a portion of said infrared image to provide an amplified electrical signal representing said portion of said infrared image at its output, and a bias bipolar transistor associated with and connected to the input of each of said amplifiers, said bias transistors being periodically operated and applying a voltage to bias their associated amplifiers and detectors to a predetermined bias level, and said bias transistors then being disabled to permit said detectors to detect said infrared image impinging on the array of detectors.
Claim 22
Dependent Claim
179 words
A thermal imaging system upon which an infrared image is focused to be detected and to generate an electrical signal representing said image, said system comprising: an array of a plurality of infrared detectors upon which said infrared image is focused for detecting said infrared image impinging thereon, said array being organized in rows and columns of closely spaced detectors, an amplifier associated with each of said detectors, each said amplifier having an input to which its associated detector is connected and each amplifier having an output, each said amplifier responding to its associated detector detecting a portion of said infrared image to provide an amplified electrical signal representing said portion of said infrared image at its output, and a bias bipolar transistor associated with and connected to the input of each of said amplifiers, said bias transistors being periodically operated and applying a voltage to bias their associated amplifiers and detectors to a predetermined bias level, and said bias transistors then being disabled to permit said detectors to detect said infrared image impinging on the array of detectors.
Claim 23
Dependent Claim
46 words
The invention in accordance with claim 17 further comprising a transfer switch connected to the output of each of said amplifiers, said transfer switches being operated to read out the amplified electrical signal representing the portion of said infrared image impinging on each of said detectors.
Claim 24
Dependent Claim
15 words
The invention in accordance with claim 18 wherein said detector is a temperature sensitive capacitor.
Claim 25
Dependent Claim
20 words
The invention in accordance with claim 19 wherein said detector is a pyroelectric detector utilizing lithium tantalate as the dielectric.
Claim 26
Dependent Claim
176 words
A thermal imaging system upon which an infrared image is focused to be detected and to generate an electrical signal representing said image, said system comprising: an array of a plurality of infrared detectors upon which said infrared image is focused for detecting said infrared image impinging thereon, said array being organized in rows and columns of closely spaced detectors, an amplifier associated with each of said detectors, each said amplifier having an input to which its associated detector is connected and each amplifier having an output, each said amplifier responding to its associated detector detecting a portion of said infrared image to provide an amplified electrical signal representing said portion of said infrared image at its output, and a bias transistor associated with and connected to the input of each of said amplifiers, said bias transistors being operated as a switch act as high impedance resistors and being used to bias said detectors and said amplifiers, said bias transistors operating as to have an impedance in the range of 10 12 to 10 15 ohms.
Claim 27
Dependent Claim
176 words
A thermal imaging system upon which an infrared image is focused to be detected and to generate an electrical signal representing said image, said system comprising: an array of a plurality of infrared detectors upon which said infrared image is focused for detecting said infrared image impinging thereon, said array being organized in rows and columns of closely spaced detectors, an amplifier associated with each of said detectors, each said amplifier having an input to which its associated detector is connected and each amplifier having an output, each said amplifier responding to its associated detector detecting a portion of said infrared image to provide an amplified electrical signal representing said portion of said infrared image at its output, and a bias transistor associated with and connected to the input of each of said amplifiers, said bias transistors being operated as a switch act as high impedance resistors and being used to bias said detectors and said amplifiers, said bias transistors operating as to have an impedance in the range of 10 12 to 10 15 ohms.
Claim 28
Dependent Claim
46 words
The invention in accordance with claim 21 further comprising a transfer switch connected to the output of each of said amplifiers, said transfer switches being operated to read out the amplified electrical signal representing the portion of said infrared image impinging on each of said detectors.
Claim 29
Dependent Claim
14 words
The invention in accordance with claim 22 wherein said detectors are temperature sensitive capacitors.
Claim 30
Dependent Claim
19 words
The invention in accordance with claim 23 wherein said detectors are pyroelectric detectors utilizing lithium tantalate as the dielectric.
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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) | 1993-01-29 | 1993-07-31 | 1994-01-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-01-29 | 1997-07-31 | 1998-01-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-01-29 | 2001-07-31 | 2002-01-30 | $7700.00 | Window Closed / Lapsed |