Patent US4129581A successfully refreshed from Google Patents.
Patent US5086350A successfully refreshed from Google Patents.
US5086350A
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US
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Fθ lens
Assignee: Fujifilm Holdings Corp
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Filing: 1990-08-28
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Granted: 1992-02-04
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Expires: 2010-08-28
Abstract
Abstract An fθ lens comprises a first lens set having a positive or negative refracting power and a second lens set having a positive refracting power, which are located in that order from the side of a light deflector. The first lens set is composed of two lenses cemented together, and the second lens set is composed of a single lens. They satisfy the conditions 0.2≦ΨG2/Ψ≦1.5 r1, r2<0 0.3≦r3/r1≦1.7 vdl>vd2 where Ψ denotes the reciprocal of the focal length of the whole fθ lens; ΨG2 denotes the reciprocal of the focal length of the second lens set; r1, r2, and r3 denote the radii of curvature of the first, second, and third lens-surfaces, each radius taking a positive value when the lens surface is convex as viewed from the side of the light deflector; vd1 denotes the Abbe's dispersion number of the first lens of the first lens set; and vd2 denotes the Abbe's dispersion number of the second lens of the first lens set.
Inventors
- 👤 Sumihiro Nishihata
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 15:58
CPC Classifications
G; G02; G02B; G02B13/00; G02B13/0005
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
137 words
An fθ lens located between a light deflector, which deflects a light beam approximately at uniform angular velocity, and a surface, which is to be scanned, the fθ lens converges the light beam onto the surface and causes the converged light beam to scan the surface approximately at uniform velocity, the fθ lens comprising: a first lens set having a positive or negative refracting power and a second lens set having a positive refracting power, said first lens set and second lens set being located in that order from the side of said light deflector, wherein said first lens set is composed of a first lens and a second lens, which are cemented together, said second lens set is composed of a single lens, and said first lens set and said second lens set satisfy the conditions
Claim 2
Dependent Claim
137 words
An fθ lens located between a light deflector, which deflects a light beam approximately at uniform angular velocity, and a surface, which is to be scanned, the fθ lens converges the light beam onto the surface and causes the converged light beam to scan the surface approximately at uniform velocity, the fθ lens comprising: a first lens set having a positive or negative refracting power and a second lens set having a positive refracting power, said first lens set and second lens set being located in that order from the side of said light deflector, wherein said first lens set is composed of a first lens and a second lens, which are cemented together, said second lens set is composed of a single lens, and said first lens set and said second lens set satisfy the conditions
Claim 3
Dependent Claim
105 words
2≦ΨG2/Ψ≦1.5 r1, r2<0 0.3≦r3/r1≦1.7 vd1>vd2 where Ψ denotes the reciprocal of the focal length of the whole fθ lens; ΩG2 denotes the reciprocal of the focal length of the second lens set; r1, r2 and r3 denote radii of curvature of first, second, and third surfaces of said first and second lenses, each radius taking a positive value when the corresponding lens surface is convex as viewed from the side of the light deflector; vd1 denotes the Abbe's dispersion number of said first lens of said first lens set; and vd2 denotes the Abbe's dispersion number of said second lens of said first lens set.
Claim 4
Dependent Claim
105 words
2≦ΨG2/Ψ≦1.5 r1, r2<0 0.3≦r3/r1≦1.7 vd1>vd2 where Ψ denotes the reciprocal of the focal length of the whole fθ lens; ΩG2 denotes the reciprocal of the focal length of the second lens set; r1, r2 and r3 denote radii of curvature of first, second, and third surfaces of said first and second lenses, each radius taking a positive value when the corresponding lens surface is convex as viewed from the side of the light deflector; vd1 denotes the Abbe's dispersion number of said first lens of said first lens set; and vd2 denotes the Abbe's dispersion number of said second lens of said first lens set.
Claim 5
Dependent Claim
16 words
An fθ lens as defined in claim 1 wherein said light beam is a laser beam.
References Cited (Backward Citations)
JPS53137631A
Cited
US4401362A
Cited
JPS5821711A
Cited
US4674825A
Cited
US4787723A
Cited
JPS62254110A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-02-03 | 1995-08-05 | 1996-02-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-02-03 | 1999-08-05 | 2000-02-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-02-03 | 2003-08-05 | 2004-02-04 | $7700.00 | Window Closed / Lapsed |