US3884584A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatic switching system for photometric portions
Assignee: Canon Inc
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Filing: 1973-11-19
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Granted: 1975-05-20
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Expires: 1993-11-19
Abstract
Abstract An automatic switching system for photometric portions of an object, comprising the first light receiving device exclusively for light flux from central portion of the object, the second light receiving device for light flux from portions other than the central portion thereof, both of said devices respectively having at least a light receiving element of photo-electromotive force type. The system further comprises, connecting means for connecting said respective elements in series, a control circuit means for said connecting means with its output, said control circuit means having amplifier circuit to form output signal corresponding to partial brightness of the object, including switch means, detecting means, indicating means and the like.
Inventors
- 👤 Tokuichi Tsunekawa
- 👤 Takashi Uchiyama
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 04:26
CPC Classifications
G; G01; G01J; G01J1/00; G01J1/42; G01J1/4209; G01J1/4214
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
160 words
An automatic switching device of a photometry type in an automatic exposure control system of a camera comprising in combination; a first photosensitive means formed to sense only the light flux mainly emitted from the central portion of a scene object, said means having at least one first photosensitive element of a photo-electromotive power type for generating photoelectric current by sensing said light flux, a second photosensitive means formed to sense the light flux emitted from the peripheral portion of a scene object, said means having at least one photosensitive element of a photoelectromotive power type for generating photoelectric current by sensing said light flux, a connecting means for coupling said first and said second elements in series with each other, a control circuit means for coupling at the input thereof with said series-connected first and second elements, said circuit means having at least an amplifier circuit to form an output signal corresponding to the brightness of a scene object.
Claim 2
Dependent Claim
160 words
An automatic switching device of a photometry type in an automatic exposure control system of a camera comprising in combination; a first photosensitive means formed to sense only the light flux mainly emitted from the central portion of a scene object, said means having at least one first photosensitive element of a photo-electromotive power type for generating photoelectric current by sensing said light flux, a second photosensitive means formed to sense the light flux emitted from the peripheral portion of a scene object, said means having at least one photosensitive element of a photoelectromotive power type for generating photoelectric current by sensing said light flux, a connecting means for coupling said first and said second elements in series with each other, a control circuit means for coupling at the input thereof with said series-connected first and second elements, said circuit means having at least an amplifier circuit to form an output signal corresponding to the brightness of a scene object.
Claim 3
Dependent Claim
18 words
The automatic switching device according to claim 1, in which said first and second photosensitive means are photo-diodes.
Claim 4
Dependent Claim
22 words
The automatic switching device according to claim 1, in which said second photosensitive means comprises two elements which are connected in parallel.
Claim 5
Dependent Claim
34 words
The automatic switching device according to claim 1, in which said amplifier circuit is an operational amplifier circuit between whose input and output ends there is connected an element having a logarithmic compression characteristic.
Claim 6
Dependent Claim
73 words
The automatic switching device according to claim 1, including switching means for disconnecting said series-connected elements and for separately obtaining the output current of each element; first and second amplifier circuits, in which each element is respectively connected to the input thereof through said switching means; detecting means connected to said amplifier circuit outputs to detect the difference therebetween, and indicating means connected thereto for indicating when said difference exceeds a specified level.
Claim 7
Dependent Claim
73 words
The automatic switching device according to claim 1, including switching means for disconnecting said series-connected elements and separately obtaining the output current of each element; first and second amplifier circuits, in which each element is respectively connected to the input thereof through said switching means; a detecting circuit coupled to said amplifier circuit outputs to detect both outputs relatively; and at least two indicating means which are driven by said detecting circuit outputs.
Claim 8
Dependent Claim
23 words
The automatic switching device according to claim 6, in which said indicating means is a liquid crystal indicater arranged within a view finder.
Claim 9
Dependent Claim
25 words
The device according to claim 1 wherein the electric current in said series-connected elements is a function primarily of the morE dimly illuminated photosensitive element.
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) | 1978-05-19 | 1978-11-18 | 1979-05-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-19 | 1982-11-18 | 1983-05-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-19 | 1986-11-18 | 1987-05-20 | $7700.00 | Window Closed / Lapsed |