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Patent US4942418A successfully refreshed from Google Patents.
US4942418A
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Focus condition detecting device
Assignee: Minolta Co Ltd
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Filing: 1989-05-22
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Granted: 1990-07-17
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Expires: 2009-05-22
Abstract
Abstract An automatic focusing divice for a camera is disclosed. The automatic focusing device has sensing means for sensing light intensity distributions within narrow and wide areas of a field of view of an objective lens, respectively and can be operated in either operation mode of one-shot AF mode and continuous AF mode. When the one-shot AF mode is designated, said narrow area which is narrower than said wide area is automatically selected for focus condition detection and, when the continuous AF mode is designated, said wide area is automatically selected.
Inventors
- 👤 Toshio Norita
- 👤 Tokuji Ishida
- 👤 Masataka Hamada
- 👤 Toshihiko Karasaki
- 👤 Nobuyuki Taniguchi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 10:07
CPC Classifications
G; G02; G02B; G02B7/00; G02B7/28; G02B7/34
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
209 words
An automatic focus detection device, comprising: an objective lens for forming displaced first and second images; first and second image signal generating means, having first and second sensors positioned to receive the first and second images and adapted to generate first and second image signals corresponding to the light intensity distributions of the images on the first and second sensors, respectively; correlation calculating means for calculating correlation between the first and second image signals while repeatedly shifting the second image signal relative to the first image signal by a given pitch to provide a correlation value of each shift with the corresponding amount of each shift; best correlation finding means for finding a best correlation among the plurality of calculated correlations to produce a best correlation value; contract detecting means for detecting the contrast of one of the images on the first and second sensors; interpolation detecting means for carrying out an interpolation calculation to find a true best correlation in accordance with the detected contrast and a correlation in front of and another correlation behind the best correlation along the shifting direction, and focusing condition detecting means for detecting the focusing condition of the objective lens with respect to the object in accordance with the true best correlation.
Claim 2
Dependent Claim
209 words
An automatic focus detection device, comprising: an objective lens for forming displaced first and second images; first and second image signal generating means, having first and second sensors positioned to receive the first and second images and adapted to generate first and second image signals corresponding to the light intensity distributions of the images on the first and second sensors, respectively; correlation calculating means for calculating correlation between the first and second image signals while repeatedly shifting the second image signal relative to the first image signal by a given pitch to provide a correlation value of each shift with the corresponding amount of each shift; best correlation finding means for finding a best correlation among the plurality of calculated correlations to produce a best correlation value; contract detecting means for detecting the contrast of one of the images on the first and second sensors; interpolation detecting means for carrying out an interpolation calculation to find a true best correlation in accordance with the detected contrast and a correlation in front of and another correlation behind the best correlation along the shifting direction, and focusing condition detecting means for detecting the focusing condition of the objective lens with respect to the object in accordance with the true best correlation.
Claim 3
Dependent Claim
65 words
An automatic focus detecting device as claimed in claim 1, wherein said interpolation detecting means includes means for calculating interpolation on the basis of the following equation: ##EQU9## wherein XM 1 represents interpolation; 1M represents amount of shift corresponding to the best correlation; H(1M-1) represents correlation in front of the best correlation; H(1M+1) represents correlation behind the best correlation, and C represents the calculated contrast.
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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) | 1993-07-16 | 1994-01-15 | 1994-07-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-07-16 | 1998-01-15 | 1998-07-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-07-16 | 2002-01-15 | 2002-07-17 | $7700.00 | Window Closed / Lapsed |