US4620775A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Front-diaphragm wide angle lens
Assignee: Ricoh Co Ltd
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Filing: 1985-09-26
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Granted: 1986-11-04
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Expires: 2005-09-26
Abstract
Abstract In a triplet photographic lens wherein a diaphragm is arranged forwardly of a lens, an asymmetry of arrangement with respect to the diaphragm has been remarkable to make it difficult to provide a wide angle. According to the present invention, principally a second lens L 2 and a third lens L 3 are bended so as to come closer to a centripetal shape about the diaphragm to make small the full length and a spacing between lenses thereby providing compensation of aberrations and increasing relative illumination, thus providing a wide angle lens having an angle of view of 70°.
Inventors
- 👤 Yoshisato Fujioka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 08:50
CPC Classifications
G; G02; G02B; G02B9/00; G02B9/12; G02B9/14; G02B9/16
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
118 words
A front-diaphragm wide angle lens comprising, successively from a object side, a first lens L 1 comprising a double convex positive lens, a second lens L 2 comprising a double concave negative lens, and a third lens L 3 comprising a meniscus positive lens with a convex surface thereof directed toward an image side, the following conditions are met: 1.15<r4/|r3|< 2.5 0.7<|r5|/r4< 1.2 0.5<lr6|/r1< 0.7 0.2f<Σd<0.28f 0.03f<d.sub.2 +d.sub.4 <0.09f r i : radius of curvature of a refractive surface of the i th from the object side d i : thickness of lens or space of lens of the i th from the object side Σd: full length of lens f: focal length of the entire lens system.
Claim 2
Dependent Claim
118 words
A front-diaphragm wide angle lens comprising, successively from a object side, a first lens L 1 comprising a double convex positive lens, a second lens L 2 comprising a double concave negative lens, and a third lens L 3 comprising a meniscus positive lens with a convex surface thereof directed toward an image side, the following conditions are met: 1.15<r4/|r3|< 2.5 0.7<|r5|/r4< 1.2 0.5<lr6|/r1< 0.7 0.2f<Σd<0.28f 0.03f<d.sub.2 +d.sub.4 <0.09f r i : radius of curvature of a refractive surface of the i th from the object side d i : thickness of lens or space of lens of the i th from the object side Σd: full length of lens f: focal length of the entire lens system.
Claim 3
Dependent Claim
45 words
A wide angle lens of claim 1 having the following data ______________________________________
f = 100 1:8 Angle of view 65°
______________________________________
r1 = 48.645
d.sub.1 = 6.31
n.sub.1 = 1.83400
v.sub.1 = 37.3
Σd = 23.88
Diaphragm position forwardly of a first surface 6.43
______________________________________
Claim 4
Dependent Claim
84 words
A wide angle lens of claim 1 having the following data ______________________________________
f = 100 1:8 Angle of view 65°
______________________________________
r1 = 45.326
d.sub.1 = 6.80
n.sub.1 = 1.80450
ν.sub.1 = 39.6
r2 = -53.542
d.sub.2 = 0.77
r3 = -35.159
d.sub.3 = 2.85
n.sub.2 = 1.69895
ν.sub.2 = 30.1
r4 = 47.138
d.sub.4 = 2.91
r.sub.5 = -40.245
d.sub.5 = 8.47
n.sub.3 = 1.77250
ν.sub.3 = 49.6
r6 = -28.170
Σd = 21.8
Diaphragm position forwardly of a first surface 6.4.
______________________________________
Claim 5
Dependent Claim
84 words
A wide angle lens of claim 1 having the following data ______________________________________
f = 100 1:8 Angle of view 70°
______________________________________
r1 = 53.714
d.sub.1 = 6.15
n.sub.1 = 1.83400
ν.sub.1 = 37.3
r2 = -243.039
d.sub.2 = 3.79
r3 = -40.035
d.sub.3 = 3.16
n.sub.2 = 1.74077
ν.sub.2 = 27.8
r4 = 77.829
d.sub.4 = 2.53
r5 = -76.587
d.sub.5 = 8.84
n.sub.3 = 1.80420
ν.sub.3 = 46.5
r6 = -30.828
Σd = 24.47
Diaphragm position forwardly of a first surface 6.44.
______________________________________
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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) | 1989-11-03 | 1990-05-05 | 1990-11-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-11-03 | 1994-05-05 | 1994-11-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-11-03 | 1998-05-05 | 1998-11-04 | $7700.00 | Window Closed / Lapsed |