US4829332A
Expired / Lapsed
US
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Focus detecting optical system
Assignee: Pentax Corp
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Filing: 1988-03-21
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Granted: 1989-05-09
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Expires: 2008-03-21
Abstract
Abstract An optical system for use in a focus detecting apparatus has a photographing lens for forming an image of an object, a condenser lens disposed behind, with respect to the photographic lens, a plane corresponding to a photographing film surface, and a pair of split optical elements located behind the condenser lens for splitting the image of the object. The split optical elements are symmetrical with respect to a meridional plane of the condenser lenses. Using a line sensor, a relative positional shift of the images is detected by the optical system to determine a focal position. The optical system has a sufficiently large spherical aberration that the diameter of the minimum circle of confusion at the maximum contrast position is larger than the width of one bit of the line sensor.
Inventors
- 👤 Osamu Shindo
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 20:42
CPC Classifications
G; G02; G02B; G02B7/00; G02B7/28; G02B7/34; G02B7/346
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
128 words
An optical system for use in a focus detecting device comprising: a photographing lens for forming an image of an object; a condenser lens disposed behind a plane equivalent to a photographing film surface; and a pair of split optical elements, located behind said condenser lens for forming images of the object, said optical elements being symmetrical with the meridional plane of said condenser lens; a line sensor having a plurality of photosensitive elements for detecting portions of the images of the object which are formed by said split optical elements, wherein said optical system has an aberration such that the diameter of the minimum circle of confusion at the maximum contrast position is larger than the width of one of said photosensitive elements of said line sensor.
Claim 2
Dependent Claim
128 words
An optical system for use in a focus detecting device comprising: a photographing lens for forming an image of an object; a condenser lens disposed behind a plane equivalent to a photographing film surface; and a pair of split optical elements, located behind said condenser lens for forming images of the object, said optical elements being symmetrical with the meridional plane of said condenser lens; a line sensor having a plurality of photosensitive elements for detecting portions of the images of the object which are formed by said split optical elements, wherein said optical system has an aberration such that the diameter of the minimum circle of confusion at the maximum contrast position is larger than the width of one of said photosensitive elements of said line sensor.
Claim 3
Dependent Claim
30 words
The apparatus of claim 1, wherein said line sensor has a light receiving surface disposed at the maximum contrast position, and said photosensitive elements are disposed at said photosensitive surface.
Claim 4
Dependent Claim
105 words
In an optical system for use in a focus detecting device having means for forming an image of an object, means for splitting the image of an object into two images, and means for detecting a relative positional shift of the two images of the object, said means for detecting including a line sensor having a plurality of photosensitive elements for detecting portions of the images, the improvement wherein the optical system has an aberration such that the diameter of the minimum circle of confusion at the maximum contrast position is larger than the width of one of said photosensitive elements of said line sensor.
Claim 5
Dependent Claim
105 words
In an optical system for use in a focus detecting device having means for forming an image of an object, means for splitting the image of an object into two images, and means for detecting a relative positional shift of the two images of the object, said means for detecting including a line sensor having a plurality of photosensitive elements for detecting portions of the images, the improvement wherein the optical system has an aberration such that the diameter of the minimum circle of confusion at the maximum contrast position is larger than the width of one of said photosensitive elements of said line sensor.
Claim 6
Dependent Claim
30 words
The apparatus of claim 3, wherein said line sensor has a light receiving surface disposed at the maximum contrast position, and said photosensitive elements are disposed at said photosensitive surface.
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) | 1992-05-08 | 1992-11-07 | 1993-05-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-05-08 | 1996-11-07 | 1997-05-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-05-08 | 2000-11-07 | 2001-05-09 | $7700.00 | Window Closed / Lapsed |