US4571035A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Two-element fθ lens group capable of correcting leaning of deflecting plane
Assignee: Ricoh Co Ltd
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Filing: 1982-11-22
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Granted: 1986-02-18
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Expires: 2002-11-22
Abstract
Abstract An fθ lens is provided for use in an optical scanner including a deflection unit for deflecting a beam of light at substantially uniform angular rate, first optics for causing the inciddence of a beam which is elliptical in cross section and has a principal axis substantially parallel to a deflecting plane defined by the deflection unit and adapted to be focused in a direction orthogonal to the principal axis, a surface being scanned, and second optics having an fθ characteristic for focusing the beam onto the surface and causing it to scan the surface substantially at uniform rate as the beam is deflected by the deflection unit. The two-element lens group includes a meniscus single lens having an fθ characteristic and having a positive power and having its concave surface directed toward the deflection unit. Also included is a cylindrical lens having a positive power in a plane perpendicular to the deflecting plane.
Inventors
- 👤 Nobuo Sakuma
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 16:24
CPC Classifications
G; G02; G02B; G02B13/00; G02B13/0005; G02B26/00; G02B26/08; G02B26/10; G02B26/12; G02B26/125; G02B27/00; G02B27/0025; G02B27/0031
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
187 words
For use in an optical scanner in which a beam which is elliptical in section and having a principal axis substantially parallel to a deflecting plane and adapted to be focused in a direction orthogonal to the principal axis is caused to be incident on a deflection unit so as to be focused adjacent to a deflecting point in one direction and in which the beam is deflected by the deflection unit at a substantially uniform angular rate to scan a surface; a two-element lens group capable of correcting leaning of a deflecting plane and for focusing a beam onto a surface being scanned as it is deflected by the deflection unit so as to scan the surface substantially at a uniform rate, comprising: a meniscus single lens disposed alongside the deflection unit, the meniscus single lens having an fθ characteristic, having a positive power and having a concave surface thereof directed toward the deflecting point, and a cylindrical lens disposed alongside the surface being scanned and having a positive power in a plane which is perpendicular to the deflecting plane wherein the following criteria is satisfied:
Claim 2
Dependent Claim
187 words
For use in an optical scanner in which a beam which is elliptical in section and having a principal axis substantially parallel to a deflecting plane and adapted to be focused in a direction orthogonal to the principal axis is caused to be incident on a deflection unit so as to be focused adjacent to a deflecting point in one direction and in which the beam is deflected by the deflection unit at a substantially uniform angular rate to scan a surface; a two-element lens group capable of correcting leaning of a deflecting plane and for focusing a beam onto a surface being scanned as it is deflected by the deflection unit so as to scan the surface substantially at a uniform rate, comprising: a meniscus single lens disposed alongside the deflection unit, the meniscus single lens having an fθ characteristic, having a positive power and having a concave surface thereof directed toward the deflecting point, and a cylindrical lens disposed alongside the surface being scanned and having a positive power in a plane which is perpendicular to the deflecting plane wherein the following criteria is satisfied:
Claim 3
Dependent Claim
73 words
6≦n 1 ≦2.0 (i) -15≦R.sub.1 /f.sub.1 ≦-1.7 (ii) f.sub.2 /f.sub.1 ≦0.3 (iii) where f 1 represents the focal length of the meniscus single lens, n 1 the refractive index of the meniscus single lens, R 1 the radius of curvature of a surface of the meniscus single lens which is directed toward the deflection unit and f 2 the focal length of a surface of the cylindrical lens which has a refracting power.
Claim 4
Dependent Claim
73 words
6≦n 1 ≦2.0 (i) -15≦R.sub.1 /f.sub.1 ≦-1.7 (ii) f.sub.2 /f.sub.1 ≦0.3 (iii) where f 1 represents the focal length of the meniscus single lens, n 1 the refractive index of the meniscus single lens, R 1 the radius of curvature of a surface of the meniscus single lens which is directed toward the deflection unit and f 2 the focal length of a surface of the cylindrical lens which has a refracting power.
Claim 5
Dependent Claim
81 words
A two-element lens group acording to claim 1 wherein f 1 =300, maximum deflecting angle w=±21°, F/100, the location of entrance pupil of -81.0 wherein individual lens surfaces assume values given in the Table below as the surfaces are sequentially numbered in a direction from the deflection unit toward the surface being scanned: ______________________________________
Surface Radius of Separation be-
Refractive
number curvature tween surfaces
index
______________________________________
1 -510.000 10.00 1.60000
2 -134.022 247.60 1.00000
3 24.750 7.00 1.52000
4 ∞
______________________________________
Claim 6
Dependent Claim
82 words
A two-element lens group according to claim 1 wherein f 1 =300, maximum deflecting angle w=±21°, F/100 and the location of entrance pupil of -94.0 and in which individual lens surfaces assume values given in the Table below as they are numbered in a direction from the deflection unit toward the surface being scanned. ______________________________________
Surface Radius of Separation be-
Refractive
number curvature tween surfaces
index
______________________________________
1 -1500.000 10.00 1.60000
2 -161.116 246.14 1.00000
3 24.960 7.00 1.52000
4 ∞
______________________________________
Claim 7
Dependent Claim
82 words
A two-element lens group according to claim 1 wherein f 1 =300, maximum deflecting angle w=±21°, F/100 and the location of entrance puil of -99.3 and in which individual lens surfaces assume values given in the Table below as they are numbered in a direction from the deflection unit toward the surface being scanned. ______________________________________
Surface Radius of Sepration be-
Refractive
number curvature tween surfaces
index
______________________________________
1 -4500.000 10.00 1.60000
2 -173.221 245.64 1.00000
3 25.050 7.00 1.52000
4 ∞
______________________________________
Claim 8
Dependent Claim
82 words
A two-element lens group according to claim 1 wherein f 1 =300, maximum deflecting angle w=±21°, F/100 and the location of entrance pupil of -94.0 and in which individual lens surfaces assume values given in the Table below as they are numbered in a direction from the deflection unit toward the surface being scanned: ______________________________________
Surface Radius of Separation be-
Refractive
number curvature tween surfaces
index
______________________________________
1 -510.000 10.00 1.80000
2 -164.622 248.01 1.00000
3 24.970 7.00 1.52000
4 ∞
______________________________________
Claim 9
Dependent Claim
82 words
A two-element lens group according to claim 1 wherein f 1 =300, maximum deflecting angle w=±21°, F/100 and the location of entrance pupil of -111.0 and in which individual lens surfaces assume values given in the Table below as they are numbered in a direction from the deflection unit toward the surface being scanned: ______________________________________
Surface Radius of Separation be-
Refractive
number curvature tween surfaces
index
______________________________________
1 -1500.000 10.00 1.80000
2 -207.510 246.28 1.00000
3 25.240 7.00 1.52000
4 ∞
______________________________________
Claim 10
Dependent Claim
81 words
An lens group according to claim 1 wherein f 1 =300, maximum deflecting angle w=±21°, F/100 and the location of entrance pupil of -118.2 and in which individual lens surfaces assume values given in the Table below as they are numbered in a direction from the deflection unit toward the surface being scanned: ______________________________________
Surface Radius of Separation be-
Refractive
number curvature tween surfaces
index
______________________________________
1 -4500.000 10.00 1.80000
2 -228.073 245.69 1.00000
3 25.360 7.00 1.52000
4 ∞
______________________________________
References Cited (Backward Citations)
US4294506A
Cited
JPS54119239A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-02-17 | 1989-08-19 | 1990-02-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-02-17 | 1993-08-19 | 1994-02-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-02-17 | 1997-08-19 | 1998-02-18 | $7700.00 | Window Closed / Lapsed |