US4849782A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Focus detecting device
Assignee: Canon Inc
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Filing: 1986-06-24
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Granted: 1989-07-18
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Expires: 2006-06-24
Abstract
Abstract A focus detecting device having a field lens disposed near the predetermined imaging plane of an objective and a secondary imaging optical system disposed rearwardly of the field lens, whereby a pair of object images based on light beams passing through different portions of the pupil of the objective are formed and the respective object images are detected by photoelectric conversion element rows disposed rearwardly of the secondary imaging optical system to thereby discriminate the focus state of the objective from the amount of relative deviation of the object images is characterized in that a refracting portion for refracting the light beam in the direction of arrangement of the photoelectric conversion elements is provided in the secondary imaging optical system.
Inventors
- 👤 Takeshi Koyama
- 👤 Keiji Ohtaka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 08:14
CPC Classifications
G; G02; G02B; G02B7/00; G02B7/28; G02B7/34; G02B7/343
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
137 words
A device for detecting the state of focus adjustment of an objective, comprising: a field lens disposed in proximity to a prospective imaging plane of said objective; a plural-image forming optical system for forming a plurality of object images of varying relative positional relation from a light beam having passed through the objective, said plural-image forming optical system comprising a plurality of lenses each generating one of said object images; a sensor for producing a signal relating to the positional relation between said plurality of object images to discriminate the state of focus adjustment and for receiving the light beam forming said plurality of object images; and a refractor for refracting the light beam forming said plurality of object images only in the scanning direction of said sensor, said refractor being disposed apart from said field lens.
Claim 2
Independent Claim
137 words
A device for detecting the state of focus adjustment of an objective, comprising: a field lens disposed in proximity to a prospective imaging plane of said objective; a plural-image forming optical system for forming a plurality of object images of varying relative positional relation from a light beam having passed through the objective, said plural-image forming optical system comprising a plurality of lenses each generating one of said object images; a sensor for producing a signal relating to the positional relation between said plurality of object images to discriminate the state of focus adjustment and for receiving the light beam forming said plurality of object images; and a refractor for refracting the light beam forming said plurality of object images only in the scanning direction of said sensor, said refractor being disposed apart from said field lens.
Claim 3
Dependent Claim
48 words
A device according to claim 1, wherein said plural-image forming optical system is imaging lenses having optical axes parallel to each other, and said refracting means is a prism provided at an end of each of said imaging lenses and having flat planes inclined symmetrically to each other.
Claim 4
Dependent Claim
14 words
A device according to claim 2, wherein said imaging lenses are a single lens.
Claim 5
Dependent Claim
16 words
A device according to claim 2, wherein said imaging lenses comprise a plurality of single lenses.
Claim 6
Dependent Claim
132 words
A device according to claim 1, wherein said plural-image forming optical system is imaging single lenses having optical axes parallel to each other, said refracting means is a prism provided at an end of each of said imaging single lenses and having flat planes inclined symmetrically to each other, and the following conditions are satisfied: f/3<d<N·f··(β+1) 2°<|θ|<10° where f, d, N, β and θ are the focal length of the imaging single lens, the thickness of the imaging single lens along the optical axis thereof, the refractive index of the imaging single lens, the absolute value of the imaging lens, the absolute value of the imaging magnification of the imaging single lens, and the angle of inclination of the inclined surfaces with respect to a plane perpendicular to the optical axis, respectively.
Claim 7
Independent Claim
118 words
A device for detecting the state of focus adjustment of an objective, comprising: a field lens disposed on or near the predetermined imaging plane of the objective; a pair of imaging single lenses disposed rearwardly of said field lens and forming object images of varying relative positional relation; and a plurality of photosensors for producing a signal relating to the positional relation between the object images to discriminate the state of focus adjustment and for receiving a light pattern relating to said object images; one end of each of said imaging single lenses being spherical and the other end thereof being an inclined plane which refracts light in the direction of the arrangement of said plurality of photosensors.
Claim 8
Independent Claim
118 words
A device for detecting the state of focus adjustment of an objective, comprising: a field lens disposed on or near the predetermined imaging plane of the objective; a pair of imaging single lenses disposed rearwardly of said field lens and forming object images of varying relative positional relation; and a plurality of photosensors for producing a signal relating to the positional relation between the object images to discriminate the state of focus adjustment and for receiving a light pattern relating to said object images; one end of each of said imaging single lenses being spherical and the other end thereof being an inclined plane which refracts light in the direction of the arrangement of said plurality of photosensors.
Claim 9
Dependent Claim
19 words
A device according to claim 6, further comprising a mask having apertures corresponding to said imaging single lenses, respectively.
Claim 10
Dependent Claim
29 words
A device according to claim 7, wherein the optical axis positions of said imaging single lenses and the centers of said apertures are offset with respect to each other.
Claim 11
Dependent Claim
21 words
A device according to claim 6, wherein the refracting surfaces of said pair of imaging single lenses form a valley shape.
Claim 12
Dependent Claim
98 words
A device according to claim 6, wherein the refracting surfaces of said pair of imaging single lenses form a mountain shape, and wherein the following conditions are satisfied: f/3<d<N·f·(β+1) 2°<|θ|<10° where f, d, N, β and θ are the focal length of the imaging single lens, the thickness of the imaging single lens along the optical axis thereof, the refractive index of the imaging single lens, the absolute value of the imaging magnification of the imaging single lens, and the angle of inclination of the refracting surfaces with respect to a plane perpendicular to the optical axis, respectively.
References Cited (Backward Citations)
US3682071A
Cited
US4132888A
Cited
US4220406A
Cited
US4230401A
Cited
US4659917A
Cited
US4497561A
Cited
US4563576A
Cited
US4573784A
Cited
US4561570A
Cited
US4712901A
Cited
US4526458A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-07-17 | 1993-01-16 | 1993-07-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-07-17 | 1997-01-16 | 1997-07-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-07-17 | 2001-01-16 | 2001-07-18 | $7700.00 | Window Closed / Lapsed |