Patent US4925279A successfully refreshed from Google Patents.
US4925279A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Telecentric f-θ lens system
Assignee: Dainippon Screen Manufacturing Co Ltd
•
Filing: 1989-09-19
•
Granted: 1990-05-15
•
Expires: 2009-09-19
Abstract
Abstract The present invention is directed to a telecentric f-θ lens system which includes first and second lens groups. The first lens group includes: first lens set having an entrance pupil and a positive power first lens in the form of meniscus, a negative power second lens, and positive power third and fourth lenses in the form of meniscus. The second lens group includes a fifth lens having a positive power. The telecentric f-θ lens system therefore has a flat image surface.
Inventors
- 👤 Hiroyuki Shirota
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 17:00
CPC Classifications
G; G02; G02B; G02B13/00; G02B13/22; G02B13/0005
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
97 words
A telecentric f-θ lens system, comprising: (a) a first lens group having an entrance pupil, which includes (a-1) a first lens in the form of meniscus having a positive power, said first lens having a concave surface which is directed to said entrance pupil, (a-2) a second lens having a negative power, and (a-3) third and fourth lenses in the form of meniscus having a positive power, respectively; and (b) a second lens group including a fifth lens having a positive power, said first through fifth lenses being successively disposed in order from said entrance pupil side.
Claim 2
Dependent Claim
97 words
A telecentric f-θ lens system, comprising: (a) a first lens group having an entrance pupil, which includes (a-1) a first lens in the form of meniscus having a positive power, said first lens having a concave surface which is directed to said entrance pupil, (a-2) a second lens having a negative power, and (a-3) third and fourth lenses in the form of meniscus having a positive power, respectively; and (b) a second lens group including a fifth lens having a positive power, said first through fifth lenses being successively disposed in order from said entrance pupil side.
Claim 3
Dependent Claim
67 words
A telecentric f-θ lens system of claim 1 wherein said telecentric f-θ lens system satisfies: -0.65<(r.sub.1 /f)<-0.25 0.4<(d.sub.8 /f)<1.16 1.61<(f.sub.5 /f)<3.5 where r 1 is a radius of curvature of said concave surface of said first lens; f is a focal length of the system; d 8 is a distance between said fourth and fifth lenses; and f 5 is a focal length of said fifth lens.
Claim 4
Dependent Claim
153 words
A scanning system for scanning an optical beam on a recording surface, said scanning system comprising: a light source for generating an optical beam; a deflector for deflecting the optical beam going out from said light source; and a telecentric f-θ lens system for imaging the optical beam deflected by said deflector on said recording surface, said telecetric f-θ lens system comprising: (a) a first lens group having an entrance pupil, which includes (a-1) a first lens in the form of meniscus having a positive power, said first lens having a concave surface which is directed to said entrance pupil, (a-2) a second lens having a negative power, and (a-3) third and fourth lenses in the form of meniscus having a positive power, respectively; and (b) a second lens group including a fifth lens having a positive power, said first through fifth lenses being successively disposed in order from said entrance pupil side.
Claim 5
Dependent Claim
153 words
A scanning system for scanning an optical beam on a recording surface, said scanning system comprising: a light source for generating an optical beam; a deflector for deflecting the optical beam going out from said light source; and a telecentric f-θ lens system for imaging the optical beam deflected by said deflector on said recording surface, said telecetric f-θ lens system comprising: (a) a first lens group having an entrance pupil, which includes (a-1) a first lens in the form of meniscus having a positive power, said first lens having a concave surface which is directed to said entrance pupil, (a-2) a second lens having a negative power, and (a-3) third and fourth lenses in the form of meniscus having a positive power, respectively; and (b) a second lens group including a fifth lens having a positive power, said first through fifth lenses being successively disposed in order from said entrance pupil side.
Claim 6
Dependent Claim
65 words
A scanning system of claim 3 wherein said telecentric f-θ lens system satisfies: -0.65<(r.sub.1 /f)<-0.25 0.4<(d.sub.8 /f)<1.16 1.61<(f.sub.5 /f)<3.5 where r 1 is a radius of curvature of said concave surface of said first lens; f is a focal length of the system; d 8 is a distance between said fourth and fifth lenses; and f 5 is a focal length of said fifth lens.
References Cited (Backward Citations)
US1945977A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-05-14 | 1993-11-13 | 1994-05-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-05-14 | 1997-11-13 | 1998-05-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-05-14 | 2001-11-13 | 2002-05-15 | $7700.00 | Window Closed / Lapsed |