Patent US4789230A successfully refreshed from Google Patents.
US4789230A
Expired / Lapsed
US
⏱️ 0.0 years remaining
f-θ Lens for use in a light beam scanning device
Assignee: Fujifilm Business Innovation Corp
•
Filing: 1988-02-17
•
Granted: 1988-12-06
•
Expires: 2008-02-17
Abstract
Abstract An fθ lens for use in a light beam scanning device is constituted by a meniscus lens having a small power and located on the side of a deflection point, and a planoconvex lens having a large power and disposed with its convex surface on the side of a surface to be scanned. The lenses are constructed to satisfy the following conditions: -0.3≦f/f1≦0.2 (a) -0.6/f1+0.85/f≦1/f2 1/f2≦-0.6/f1+0.95/f (b) where f represents a focal length of a lens system constituted by the two lenses, and f 1 and f 2 respectively represent focal lengths of the meniscus lens and the plano-convex lens.
Inventors
- 👤 Akira Ohta
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 18:56
CPC Classifications
G; G02; G02B; G02B13/00; G02B13/0005
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
124 words
An fθ lens for use in a light beam scanning device for focusing on a surface to be scanned a light beam which is deflected by deflecting means, said fθ lens comprising: a meniscus lens having a small power and located on the side of a deflection point which the light beam is deflected, and a plano-convex lens having a large power and disposed with its convex surface on the side of said surface to be scanned, said lenses being constructed to satisfy the following conditions: -0.3≦f/f1≦0.2 (a) -0.6/f1+0.85/f≦1/f2 1/f2≦-0.6/f1+0.95/f (b) where f represent a focal length of a lens system constituted by said two lenses, and f 1 and f 2 respectively represent focal lengths of the meniscus lens and the plano-convex lens.
Claim 2
Dependent Claim
124 words
An fθ lens for use in a light beam scanning device for focusing on a surface to be scanned a light beam which is deflected by deflecting means, said fθ lens comprising: a meniscus lens having a small power and located on the side of a deflection point which the light beam is deflected, and a plano-convex lens having a large power and disposed with its convex surface on the side of said surface to be scanned, said lenses being constructed to satisfy the following conditions: -0.3≦f/f1≦0.2 (a) -0.6/f1+0.85/f≦1/f2 1/f2≦-0.6/f1+0.95/f (b) where f represent a focal length of a lens system constituted by said two lenses, and f 1 and f 2 respectively represent focal lengths of the meniscus lens and the plano-convex lens.
References Cited (Backward Citations)
US3973833A
Cited
JPS53137631A
Cited
US4179183A
Cited
US4277128A
Cited
US4343531A
Cited
JPS55127514A
Cited
JPS55149916A
Cited
US4571035A
Cited
US4645311A
Cited
US4512625A
Cited
JPS6148684A
Cited
JPS61172109A
Cited
US4707085A
Cited
US4712884A
Cited
JPS61175607A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-12-06 | 1992-06-06 | 1992-12-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-12-06 | 1996-06-06 | 1996-12-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-12-06 | 2000-06-06 | 2000-12-06 | $7700.00 | Window Closed / Lapsed |