Patent US4494853A successfully refreshed from Google Patents.
US4494853A
Expired / Lapsed
US
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Photometric method for cameras
Assignee: Konica Minolta Inc
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Filing: 1981-07-23
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Granted: 1985-01-22
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Expires: 2001-07-23
Abstract
Abstract In cameras having an automatic exposure control of the through-the-lens photometric type, light exposure is determined by a photoreceptor responsive in turn to photometric sensitivity distribution. Such distribution can be determined by overall photometry, weighted photometry and spot photometry as controlled through the use of an electro-optical element serving as a focusing screen between the reflected incoming light and the photoreceptor. The photometric mode is varied by changing the applied voltage on the electro-optical element.
Inventors
- 👤 Koji Watanabe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 14:00
CPC Classifications
G; G03; G03B; G03B7/00; G03B7/08; G03B7/099; G03B7/0993; G03B7/0997; G03B7/09971; G03B7/09976
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
91 words
The method of varying photometric sensitivity distribution in a camera having an automatic exposure control of the through-the-lens photometric type in which the amount of exposure is determined by a photoreceptor, which includes the steps of passing the light from the picture area to the photoreceptor and to a view finder through a focusing screen comprising an electro-optical element, and varying the photometric sensitivity distribution by controlling the voltage applied to said electro-optical element, whereby an operator is able to confirm the focusing situation and photometry range through said view finder.
Claim 2
Independent Claim
91 words
The method of varying photometric sensitivity distribution in a camera having an automatic exposure control of the through-the-lens photometric type in which the amount of exposure is determined by a photoreceptor, which includes the steps of passing the light from the picture area to the photoreceptor and to a view finder through a focusing screen comprising an electro-optical element, and varying the photometric sensitivity distribution by controlling the voltage applied to said electro-optical element, whereby an operator is able to confirm the focusing situation and photometry range through said view finder.
Claim 3
Dependent Claim
22 words
Method according to claim 1 in which the photometric sensitivity distribution is varied according to an overall weight, or spot photometry pattern.
Claim 4
Dependent Claim
119 words
In a camera having an automatic exposure control of the through-the-lens photometric type in which the amount of exposure is determined by a photoreceptor, the combination of a view finder, means controlling the photometric sensitivity distribution of the camera comprising a focusing screen in the form of an electro-optical element, a mirror directing incoming light upon said electro-optical element, a prism supporting said photoreceptor and adapted to direct light from said electro-optical element to said photoreceptor and to said view finder, and a source of driving voltage applied to said electro-optical element for controlling the distribution of the intensity of light therefrom, whereby an operator is able to confirm the focusing situation and photometry range through said view finder.
Claim 5
Dependent Claim
119 words
In a camera having an automatic exposure control of the through-the-lens photometric type in which the amount of exposure is determined by a photoreceptor, the combination of a view finder, means controlling the photometric sensitivity distribution of the camera comprising a focusing screen in the form of an electro-optical element, a mirror directing incoming light upon said electro-optical element, a prism supporting said photoreceptor and adapted to direct light from said electro-optical element to said photoreceptor and to said view finder, and a source of driving voltage applied to said electro-optical element for controlling the distribution of the intensity of light therefrom, whereby an operator is able to confirm the focusing situation and photometry range through said view finder.
Claim 6
Dependent Claim
32 words
In a camera according to claim 3, in which said focusing screen is an electro-optical element, and in which said last means comprises means varying the driving voltage applied to said element.
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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) | 1988-01-22 | 1988-07-23 | 1989-01-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-01-22 | 1992-07-23 | 1993-01-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-01-22 | 1996-07-23 | 1997-01-22 | $7700.00 | Window Closed / Lapsed |