US3661466A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Photometric system for cameras
Assignee: Eastman Kodak Co
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Filing: 1970-06-25
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Granted: 1972-05-09
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Expires: 1990-06-25
Abstract
Abstract An exposure control system which automatically compensates for variations in background lighting by exposing a single photocell alternately to the subject and then to the background. A reversing switch is operated synchronously with the means for alternating the exposure of the photocell in such a manner to reverse the direction of the current through the exposure control synchronously with the alternation of the photocell exposure to the scene.
Inventors
- 👤 Allen G Stimson
- 👤 John H Eagle
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 09:22
CPC Classifications
G; G01; G01J; G01J1/00; G01J1/42; G01J1/4209; G01J1/4214
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
106 words
Exposure control apparatus, the combination comprising: an electric circuit including a photocell and an electric measuring instrument energized under control of said photocell; cyclically operable means for exposing said photocell to illumination successively from at least two different field angles which are in close proximity with respect to each other; and means for reversing the polarity of energization of said instrument in timed relation to the change from one of said field angles to the other at a rate which is relatively faster than the response time of said electrical measuring instrument so that said instrument measures the average of the output signals from said photocell.
Claim 2
Dependent Claim
106 words
Exposure control apparatus, the combination comprising: an electric circuit including a photocell and an electric measuring instrument energized under control of said photocell; cyclically operable means for exposing said photocell to illumination successively from at least two different field angles which are in close proximity with respect to each other; and means for reversing the polarity of energization of said instrument in timed relation to the change from one of said field angles to the other at a rate which is relatively faster than the response time of said electrical measuring instrument so that said instrument measures the average of the output signals from said photocell.
Claim 3
Dependent Claim
101 words
Exposure control apparatus comprising: a photocell; a transducer electrically connected with said photocell; a source of current for energizing said transducer under the control of said photocell; light-chopping means disposed to intercept illumination incident on said photocell for providing alternately different fields of view in close proximity for said photocell; and switching means for cyclically reversing the flow of current through said transducer in synchronization with the change of field of view by said chopping means at a rate relatively faster than the response time of said transducer, so that the transducer is energized by the average current through said photocell.
Claim 4
Dependent Claim
101 words
Exposure control apparatus comprising: a photocell; a transducer electrically connected with said photocell; a source of current for energizing said transducer under the control of said photocell; light-chopping means disposed to intercept illumination incident on said photocell for providing alternately different fields of view in close proximity for said photocell; and switching means for cyclically reversing the flow of current through said transducer in synchronization with the change of field of view by said chopping means at a rate relatively faster than the response time of said transducer, so that the transducer is energized by the average current through said photocell.
Claim 5
Dependent Claim
101 words
Exposure control apparatus comprising: photoresponsive means for providing an electrical signal related in magnitude to the level of illumination incident thereon; cyclically operable means for exposing said photoresponsive means alternately during successive cyclic periods to illumination from at least two different field angles in close proximity to render said photoresponsive means effective to alternately provide signals representative of the illumination incident thereon from said field angles, respectively; and means for measuring the average of said alternate signals over a time period relatively longer than the cyclic periods during which said photoresponsive means is exposed alternately to said two different field angles.
Claim 6
Dependent Claim
101 words
Exposure control apparatus comprising: photoresponsive means for providing an electrical signal related in magnitude to the level of illumination incident thereon; cyclically operable means for exposing said photoresponsive means alternately during successive cyclic periods to illumination from at least two different field angles in close proximity to render said photoresponsive means effective to alternately provide signals representative of the illumination incident thereon from said field angles, respectively; and means for measuring the average of said alternate signals over a time period relatively longer than the cyclic periods during which said photoresponsive means is exposed alternately to said two different field angles.
Claim 7
Dependent Claim
64 words
The exposure control apparatus of claim 3, wherein said measuring means further comprises an electrical measuring instrument energized under control of said photo-responsive means and means for reversing the polarity of energization of said instrument in timed relation to the change from one of said two field angles to the other, said electrical measuring instrument having a response time extending over said time period.
Claim 8
Dependent Claim
101 words
Exposure control apparatus comprising: an electric circuit including a photocell and an electrical measuring instrument energized under control of said photocell, cyclically operable means for exposing said photocell alternately to illumination from at least two different field angles in close proximity, and means for reversing the polarity of energization of said instrument in synchronization with the change from one of said two field angles to the other, said instrument having a response time slower than the rate at which said cyclically operable means changes the field angle of said photocell so that the instrument measures the average current through said photocell.
Claim 9
Dependent Claim
101 words
Exposure control apparatus comprising: an electric circuit including a photocell and an electrical measuring instrument energized under control of said photocell, cyclically operable means for exposing said photocell alternately to illumination from at least two different field angles in close proximity, and means for reversing the polarity of energization of said instrument in synchronization with the change from one of said two field angles to the other, said instrument having a response time slower than the rate at which said cyclically operable means changes the field angle of said photocell so that the instrument measures the average current through said photocell.
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) | 1975-05-09 | 1975-11-08 | 1976-05-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-05-09 | 1979-11-08 | 1980-05-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-05-09 | 1983-11-08 | 1984-05-09 | $7700.00 | Window Closed / Lapsed |