Patent US4519686A successfully refreshed from Google Patents.
US4519686A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Focusing screen of a camera
Assignee: Nikon Corp
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Filing: 1983-05-19
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Granted: 1985-05-28
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Expires: 2003-05-19
Abstract
Abstract A focusing screen capable of transmitting light therethrough and disposed between an objective lens and an eye-piece includes a surface formed with a large number of substantially hemispherical faces of irregular sizes disposed irregularly. The radius of curvature of the hemispherical faces is within the range of 8.5 to 52.8 μm and the height thereof is within the range of 1.5 to 3.6 μm.
Inventors
- 👤 Yasutomo Seki
- 👤 Toshio Akiyama
- 👤 Norio Nakabayashi
- 👤 Yutaka Iizuka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 08:49
CPC Classifications
G; G03; G03B; G03B13/00; G03B13/18; G03B13/24
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
71 words
A focusing screen capable of transmitting light therethrough and disposed between an objective lens and an eye-piece, said focusing screen comprising: a surface formed with a large number of substantially hemispherical faces of irregular sizes disposed irregularly, the radius of curvature of said hemispherical faces being within the range of 8.5 to 52.8 μm and the height thereof along the screen thickness being within the range of 1.5 to 3.6 μm.
Claim 2
Dependent Claim
71 words
A focusing screen capable of transmitting light therethrough and disposed between an objective lens and an eye-piece, said focusing screen comprising: a surface formed with a large number of substantially hemispherical faces of irregular sizes disposed irregularly, the radius of curvature of said hemispherical faces being within the range of 8.5 to 52.8 μm and the height thereof along the screen thickness being within the range of 1.5 to 3.6 μm.
Claim 3
Dependent Claim
38 words
A focusing screen according to claim 1, wherein the radius of curvature of said hemispherical faces is within the range of 16.7 to 26.5 μm and the height thereof is within the range of 1.65 to 3.30 μm.
Claim 4
Dependent Claim
71 words
A focusing screen capable of transmitting light therethrough and disposed between an objective lens and an eye-piece, said focusing screen comprising: a surface formed with a large number of substantially hemispherical projections of irregular sizes disposed irregularly, the radius of curvature of said hemispherical projections being within the range of 8.5 to 52.8 μm and the height thereof along the screen thickness being within the range of 1.5 to 3.6 μm.
Claim 5
Dependent Claim
71 words
A focusing screen capable of transmitting light therethrough and disposed between an objective lens and an eye-piece, said focusing screen comprising: a surface formed with a large number of substantially hemispherical projections of irregular sizes disposed irregularly, the radius of curvature of said hemispherical projections being within the range of 8.5 to 52.8 μm and the height thereof along the screen thickness being within the range of 1.5 to 3.6 μm.
Claim 6
Dependent Claim
21 words
A focusing screen according to claim 3, wherein said projections are disposed in close contact with one another on said surface.
Claim 7
Dependent Claim
34 words
A focusing screen according to claim 3, wherein said projections are disposed at predetermined intervals on said surface and the surface of said focusing screen between said projections is formed by a curved face.
Claim 8
Dependent Claim
34 words
A focusing screen according to claim 3, wherein said projections are disposed at predetermined intervals on said surface and the surface of said focusing screen between said projections is formed by a planar face.
Claim 9
Dependent Claim
71 words
A focusing screen capable of transmitting light therethrough and disposed between an objective lens and an eye-piece, said focusing screen comprising: a surface formed with a large number of substantially hemispherical depressions of irregular sizes disposed irregularly, the radius of curvature of said hemispherical depressions being within the range of 8.5 to 52.8 μm and the depth thereof along the screen thickness being within the range of 1.5 to 3.6 μm.
Claim 10
Dependent Claim
71 words
A focusing screen capable of transmitting light therethrough and disposed between an objective lens and an eye-piece, said focusing screen comprising: a surface formed with a large number of substantially hemispherical depressions of irregular sizes disposed irregularly, the radius of curvature of said hemispherical depressions being within the range of 8.5 to 52.8 μm and the depth thereof along the screen thickness being within the range of 1.5 to 3.6 μm.
Claim 11
Dependent Claim
18 words
A focusing screen according to claim 7, wherein said depressions are disposed at predetermined intervals on said 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) | 1988-05-27 | 1988-11-26 | 1989-05-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-05-27 | 1992-11-26 | 1993-05-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-05-27 | 1996-11-26 | 1997-05-28 | $7700.00 | Window Closed / Lapsed |