US5089835A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Phase-type diffusing plate
Assignee: Canon Inc
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Filing: 1990-02-21
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Granted: 1992-02-18
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Expires: 2010-02-21
Abstract
Abstract A focusing screen suited to be used in the camera, having three plane portions of different heights in each of small areas, wherein the plane portion A, the plane portion B and the plane portion C are arranged in the order from the lowest height, and letting the height of the plane portion B measured from the plane portion A be denoted by d B , the height of the plane portion C from the plane portion A by d C , and the area ratios of the plane portions A, B and C to the entire area by S A , S B and S C (where S A +S B +S C =1) respectively, the following conditions are satisfied 1.6<d.sub.C /d.sub.B <2.5 0.35<S.sub.B <0.5 whereby the color tint is minimized for good optical performance.
Inventors
- 👤 Nozomu Kitagishi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 23:16
CPC Classifications
G; G03; G03B; G03B13/00; G03B13/18; G03B13/24
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
119 words
A phase-type diffusing plate comprising: three plane portions of different heights in small areas, wherein the plane portion A, the plane portion B and the plane portion C are arranged in the order from the lowest height, and letting the height of said plane portion B relative to said plane portion A be denoted by d B , the height of said plane portion C relative to said plane portion A by d C , and the area ratios of said plane portions A, B and C by S A , S B and S C to the entire area (where S A +S B +S C =1) respectively, the following conditions are satisfied: 1.6<d.sub.C /d.sub.B <2.5 0.35<S.sub.B <0.5
Claim 2
Dependent Claim
119 words
A phase-type diffusing plate comprising: three plane portions of different heights in small areas, wherein the plane portion A, the plane portion B and the plane portion C are arranged in the order from the lowest height, and letting the height of said plane portion B relative to said plane portion A be denoted by d B , the height of said plane portion C relative to said plane portion A by d C , and the area ratios of said plane portions A, B and C by S A , S B and S C to the entire area (where S A +S B +S C =1) respectively, the following conditions are satisfied: 1.6<d.sub.C /d.sub.B <2.5 0.35<S.sub.B <0.5
Claim 3
Dependent Claim
17 words
A phase-type diffusing plate according to claim 1, satisfying the following condition: 0.46<S.sub.A /S.sub.C <0.95 0.35<S.sub.B <0.5.
Claim 4
Dependent Claim
58 words
A phase-type diffusing plate according to claim 1 or 2, wherein said phase-type diffusing plate comprises a transmission type diffusing plate, and satisfies the following conditions: 0.7<(nd-1)d.sub.c /0.587<1.2 where d c is the height (in μm) of said plane portion C and nd is the refractive index for the spectral d-line (wavelength: 0.587 μm) of the phase portion.
Claim 5
Dependent Claim
41 words
A phase-type diffusing plate according to claim 1 or 2, wherein said phase-type diffusing plate comprises a reflection type diffusing plate, and satisfies the following condition: 0.7<2d.sub.c /0.587<5.1 where d c is the height (in μm) of said plane portion C.
Claim 6
Dependent Claim
139 words
A camera comprising: a photographic lens; and a focusing screen arranged at or near a plane on which said photographic lens forms an image, said focusing screen having three minute plane portions of different heights, the plane portion A, the plane portion B, and the plane portion C being arranged in the order from the lowest height, and, letting the height of said plane portion B relative to said plane portion A be denoted by d B , the height of said plane portion C relative to said plane portion A by d C , and the area ratios of said plane portions A, B and C to the entire area by S A , S B and S C (where S A +S B +S C =1) respectively, the following conditions are satisfied: 1.6<d.sub.C /d.sub.B <2.5 0.35<B.sub.S <0.5.
Claim 7
Dependent Claim
139 words
A camera comprising: a photographic lens; and a focusing screen arranged at or near a plane on which said photographic lens forms an image, said focusing screen having three minute plane portions of different heights, the plane portion A, the plane portion B, and the plane portion C being arranged in the order from the lowest height, and, letting the height of said plane portion B relative to said plane portion A be denoted by d B , the height of said plane portion C relative to said plane portion A by d C , and the area ratios of said plane portions A, B and C to the entire area by S A , S B and S C (where S A +S B +S C =1) respectively, the following conditions are satisfied: 1.6<d.sub.C /d.sub.B <2.5 0.35<B.sub.S <0.5.
Claim 8
Dependent Claim
20 words
A camera according to claim 5, wherein said focusing screen satisfies the following condition: 0.46<S.sub.A /S.sub.C <0.95 1.05<S.sub.A /S.sub.C <2.2.
Claim 9
Dependent Claim
54 words
A camera according to claim 5, wherein said focusing screen comprises a transmission type phase-type diffusing plate, and satisfies the following condition: 0.7<(nd-1)d.sub.c /0.587<1.2 where d c is the height (in μm) of said plane portion C and nd is the refractive index for the spectral d-line (wavelength: 0.587 μm) of the phase portion.
Claim 10
Dependent Claim
37 words
A camera according to claim 5, wherein said focusing screen comprises a reflection type phase-type diffusing plate, and satisfies the following condition: 0.7<2d.sub.c /0.587<5.1 where d c is the height (in μm) of said plane portion C.
Claim 11
Dependent Claim
39 words
A phase-type diffusing plate according to claim 1, wherein said plane portion A is of concave profile relative to said plane portion B, and wherein said plane portion C is of convex profile relative to said plane portion B.
Claim 12
Dependent Claim
36 words
A camera according to claim 5, wherein said plane portion A is of concave profile relative to said plane portion B, and said plane portion C is of convex profile relative to said plane portion B.
Claim 13
Dependent Claim
21 words
A phase-type diffusion plate according to claim 1, wherein at least one of said plane portions is of a circular shape.
Claim 14
Dependent Claim
19 words
A camera according to claim 5, wherein at least one of said plane portions is of a circular shape.
Claim 15
Dependent Claim
15 words
A phase-type diffusion plate according to claim 1, wherein said plane portions are arranged two-dimensionally.
Claim 16
Dependent Claim
18 words
A phase-type diffusion plate according to claim 13, wherein said plane portions are arranged in an island-like fashion.
Claim 17
Dependent Claim
13 words
A camera according to claim 5, wherein said plane portions are arranged two-dimensionally.
Claim 18
Dependent Claim
16 words
A camera according to claim 15, wherein said plane portions are arranged in an island-like fashion.
References Cited (Backward Citations)
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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) | 1995-02-17 | 1995-08-19 | 1996-02-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-02-17 | 1999-08-19 | 2000-02-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-02-17 | 2003-08-19 | 2004-02-18 | $7700.00 | Window Closed / Lapsed |