US3564330A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Device for providing exposure control for a camera
Assignee: United States Department of the Air Force
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Filing: 1969-03-28
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Granted: 1971-02-16
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Expires: 1989-03-28
Abstract
Abstract A device to provide an exposure control signal which may be used directly to control camera exposure or may be used to provide a meter indication which may be used to control the iris setting or exposure time of the camera makes use of an electron image correlator, which is normally used to obtain correlation between two electron images, to provide a first signal proportional to photocathode current, which is related to integrated scene brightness. The first signal is used to control the write time of the correlation tube storage element. The first signal is modified by a second signal which is a function of scene detail of the lower brightness portion of the scene which is obtained by adjusting the storage element, backing electrode potential to maximize the correlation function. The second signal is subtracted from the first signal to obtain the exposure control signal.
Inventors
- 👤 Harry O Pfeiffer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 14:46
CPC Classifications
H; H04; H04N; H04N23/00; H04N23/70; H04N23/71
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
238 words
In combination with an image correlation system having an image storage tube; with a photocathode; an image storage element having a backing electrode, and collector electrode adjacent the storage element; an output means and means, including an electron image deflection means and means for applying a nutation signal of a predetermined frequency to the deflection means, for providing a correlation between a first electron image stored on said storage element and a second electron image directed toward said storage element from said photocathode, a system for providing a film exposure control signal for scenes wherein the brightness range exceeds the brightness latitude of the photographic film, comprising: means for providing a first stored voltage signal proportional to the photocathode current with the photocathode illuminated by said scene; means responsive to said stored signal for controlling the write time of the image storage tube as a function of scene brightness; means responsive to the output of said image storage tube for adjusting the backing electrode potential in response to said output to maximize the correlation signal output of said image storage tube and for storing a second voltage signal proportional to derivative energy in said scene; computer means responsive to the difference of the first stored voltage signal and the second stored voltage signal for providing an output exposure signal as a function of integrated scene brightness and of the maximum spatial derivative energy of the scene being photographed.
Claim 2
Dependent Claim
238 words
In combination with an image correlation system having an image storage tube; with a photocathode; an image storage element having a backing electrode, and collector electrode adjacent the storage element; an output means and means, including an electron image deflection means and means for applying a nutation signal of a predetermined frequency to the deflection means, for providing a correlation between a first electron image stored on said storage element and a second electron image directed toward said storage element from said photocathode, a system for providing a film exposure control signal for scenes wherein the brightness range exceeds the brightness latitude of the photographic film, comprising: means for providing a first stored voltage signal proportional to the photocathode current with the photocathode illuminated by said scene; means responsive to said stored signal for controlling the write time of the image storage tube as a function of scene brightness; means responsive to the output of said image storage tube for adjusting the backing electrode potential in response to said output to maximize the correlation signal output of said image storage tube and for storing a second voltage signal proportional to derivative energy in said scene; computer means responsive to the difference of the first stored voltage signal and the second stored voltage signal for providing an output exposure signal as a function of integrated scene brightness and of the maximum spatial derivative energy of the scene being photographed.
Claim 3
Dependent Claim
92 words
The device as recited in claim 1 wherein the means for controlling the write time of the image storage tube includes: an integrating circuit for producing a write time ramp voltage; a dual level trigger circuit responsive to the write time ramp voltage for producing a pulse whose width is determined by the slope of said write time ramp voltage; means responsive to the output of said dual level trigger circuit for applying a write potential to said photocathode for the duration of the output pulse of said dual level trigger circuit.
Claim 4
Dependent Claim
32 words
The device as recited in claim 2 wherein said means for applying a write potential to the photocathode is a flip-flop circuit, responsive to the output of the dual level trigger circuit.
Claim 5
Dependent Claim
69 words
The device as recited in claim 1 wherein said means for adjusting the backing electrode potential of said storage element includes, a summing amplifier including means for applying a fixed nominal bias voltage to said backing electrode and means responsive to the output of said image storage tube to supply a second bias voltage to said summing amplifier for maximizing the correlation signal output of said image storage tube.
Claim 6
Dependent Claim
72 words
The device as recited in claim 4 wherein said means for maximizing the correlation signal includes a precision peak detector; a backing electrode ramp generator responsive to the output of said peak detector for producing the second bias voltage applied to the summing amplifier whereby the backing electrode bias increases, as the output voltage of the backing electrode ramp generator increases, to maximize the correlation signal output of the image storage tube.
Claim 7
Dependent Claim
69 words
The device as recited in claim 3 wherein said means for adjusting the backing electrode potential of said storage element includes, a summing amplifier including means for appLying a fixed nominal bias voltage to said backing electrode and means responsive to the output of said image storage tube to supply a second bias voltage to said summing amplifier for maximizing the correlation signal output of said image storage tube.
Claim 8
Dependent Claim
72 words
The device as recited in claim 6 wherein said means for maximizing the correlation signal includes a precision peak detector; a backing electrode ramp generator responsive to the output of said peak detector for producing the second bias voltage applied to the summing amplifier whereby the backing electrode bias increases, as the output voltage of the backing electrode ramp generator increases, to maximize the correlation signal output of the image storage tube.
Claim 9
Dependent Claim
23 words
The device as recited in claim 7 including an indicating means and means for applying said output exposure signal to said indicating means.
Claim 10
Dependent Claim
46 words
The device as recited in claim 7 including a camera lens iris control; means for supplying said output exposure signal to said camera lens iris control; means for supplying a signal proportional to aperture number and a signal proportional to exposure time to said computer 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) | 1974-02-15 | 1974-08-17 | 1975-02-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-02-15 | 1978-08-17 | 1979-02-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-02-15 | 1982-08-17 | 1983-02-16 | $7700.00 | Window Closed / Lapsed |