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Patent US3903451A successfully refreshed from Google Patents.
US3903451A
Expired / Lapsed
US
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Gating network for image intensifier
Assignee: United States Department of the Army
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Filing: 1974-04-30
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Granted: 1975-09-02
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Expires: 1994-04-30
Abstract
Abstract An electronic analog gating means for an image intensifier in which transmitted pulsed illumination that is returned from targets down range are gated through the image intensifier in an analog manner according to the inverse square law in illumination drop off in distance. The image intensifier is enabled in distinct incremental time elements which correspond to and are inclusive within the time that it takes for illumination to travel to and from corresponding incremental depths of range. The distinct incremental time elements are produced by comparing a series of linear ramps, which are produced at the same frequency as the transmitted pulsed illumination, with an increasing parabolic square function curve that repeats every one-tenth of a second to produce at least ten viewings per second on the nearest target to eliminate flicker but producing an increasing number of viewings of increasing distant targets. The electronic analog gating means is duty cycled to permit illumination reflected from these targets to be amplified in proportion to the square of the distances to the targets, and thus provide an effective equal illumination of all targets down range. By changing certain portions of the parabolic curve, the effective illumination reflected from a selected range, represented by one of the incremental time elements, may be emphasized by gating the image intensifier on more often than normal at that specific incremental time element.
Inventors
- 👤 John T Hall
- 👤 Donald Nichols
- 👤 Peter W Vanatta
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 14:13
CPC Classifications
G; G01; G01S; G01S17/00; G01S17/88; G01S17/89
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
357 words
An electronic analog gating system for cyclically controlling the enable time of an image intensifier over repetitive cyclically controlled periods of returned illumination pulses to provide viewings of the nearest target at a repetitive rate just above the perceptible flicker rate and increasing the number of viewings of target to the maximum range of the image intensifier in accordance with the inverse square law of drop off in illumination, the system comprising: a master clock for producing a train of trigger pulses therefrom; light pulse producing means comprising a pulsed illuminator having an input connected to said train of trigger pulses and an output producing a train of light pulses at the same frequency as said trigger pulses wherein said train of light pulses are directed parallel to the optical axis of said image intensifier; an effective brightness correction circuit having an input connected to receive said train of trigger pulses and a first and a second output therefrom, wherein said correction circuit includes at said frist output a trailing edge producing means for producing plurality of evenly spaced trailing edge pulses that are delayed by the time required for said pulsed illumination to travel to and from the farthest target downrange and includes at said second output a leading edge producing means for producing a plurality of leading edge pulses that are advancing in time between each subsequent trailing edge pulse over said repetitive cyclically controlled periods; and a high voltage electronic gate having a first and second input and an output connected to the image intensifier control voltage with said first input receiving said plurality of evenly spaced trailing edge pulses to disenable said image intensifier and said second input receiving said plurality of leading edge pulses to enable said image intensifier wherein the total enable time of said image intensifier is cyclically advancing in time of light pulse travel to and from downrange targets and is the integrated sum of all the leading edge to trailing edge enable times through each of said cyclically controlled period whereby integrated viewings of targets downrange are increased according to the inverse square law of illumination drop off.
Claim 2
Dependent Claim
357 words
An electronic analog gating system for cyclically controlling the enable time of an image intensifier over repetitive cyclically controlled periods of returned illumination pulses to provide viewings of the nearest target at a repetitive rate just above the perceptible flicker rate and increasing the number of viewings of target to the maximum range of the image intensifier in accordance with the inverse square law of drop off in illumination, the system comprising: a master clock for producing a train of trigger pulses therefrom; light pulse producing means comprising a pulsed illuminator having an input connected to said train of trigger pulses and an output producing a train of light pulses at the same frequency as said trigger pulses wherein said train of light pulses are directed parallel to the optical axis of said image intensifier; an effective brightness correction circuit having an input connected to receive said train of trigger pulses and a first and a second output therefrom, wherein said correction circuit includes at said frist output a trailing edge producing means for producing plurality of evenly spaced trailing edge pulses that are delayed by the time required for said pulsed illumination to travel to and from the farthest target downrange and includes at said second output a leading edge producing means for producing a plurality of leading edge pulses that are advancing in time between each subsequent trailing edge pulse over said repetitive cyclically controlled periods; and a high voltage electronic gate having a first and second input and an output connected to the image intensifier control voltage with said first input receiving said plurality of evenly spaced trailing edge pulses to disenable said image intensifier and said second input receiving said plurality of leading edge pulses to enable said image intensifier wherein the total enable time of said image intensifier is cyclically advancing in time of light pulse travel to and from downrange targets and is the integrated sum of all the leading edge to trailing edge enable times through each of said cyclically controlled period whereby integrated viewings of targets downrange are increased according to the inverse square law of illumination drop off.
Claim 3
Dependent Claim
215 words
An electronic anAlog gating system as set forth in claim 1 wherein said effective brightness correction circuit comprises a timer that produces said plurality of evenly spaced trailing edge pulses and wherein said plurality of leading edge pulses are produced by a circuit comprising a comparator circuit having a first and a second input and an output, a ramp voltage producing means having said train of trigger pulses applied to an input and a plurality of equal amplitude ramp voltages that are produced at the same time and repetition rate as said trigger pulses are applied to said second input of said comparator, a parabolic square function generator having an input and an output, and a free running clock having a pulsed output therefrom at the repetitive cyclically controlled periods that is applied to said input of said parabolic square function generator whereby a parabolic curve having a maximum amplitude of said plurality of equal amplitude ramp voltages and a period of said cyclically controlled periods is produced at the output of said square function generator and is applied to said first input to said comparator in which the output to said comparator has a plurality of leading edge pulses moving forward in time between subsequent trailing edge pulses over said repetitive cyclically controlled periods.
Claim 4
Dependent Claim
56 words
An electronic analog gating system as set forth in claim 2 wherein said train of trigger pulses, said train of illumination pulses, said evenly spaced trail edge pulses, and said plurality of equal amplitude ramp voltages are at a frequency of 5 kilo-Hertz and the frequency of repetitive cyclically controlled period is ten times per second.
Claim 5
Dependent Claim
19 words
An electronic analog gating system as set forth in claim 3 wherein said timer is a one shot multivibrator.
Claim 6
Dependent Claim
18 words
An electronic analog gating system as set forth in claim 4 wherein said pulsed illuminator is a laser.
Claim 7
Dependent Claim
19 words
An electronic analog gating system as set forth in claim 5 wherein said laser is a gallium arsenide laser.
Claim 8
Dependent Claim
19 words
An electronic analog gating system as set forth in claim 4 wherein said pulsed illuminator is a flash lamp.
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) | 1978-09-01 | 1979-03-03 | 1979-09-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-01 | 1983-03-03 | 1983-09-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-01 | 1987-03-03 | 1987-09-02 | $7700.00 | Window Closed / Lapsed |