US4627685A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Post-objective type scanning device
Assignee: Ricoh Co Ltd
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Filing: 1984-12-20
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Granted: 1986-12-09
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Expires: 2004-12-20
Abstract
Abstract A post-objective type scanning device which effects scanning after a beam has been formed into a condenser light flux by an optical deflector used for laser printers or the like includes a focusing cylindrical lens in the vicinity of the scanning surface. The cylindrical lens and scanning surface are arranged to provide a geometric optically conjugate perpendicular to the scanning line so as to correct irregularities in the scanning line and to reduce the curvature of the resulting image surface.
Inventors
- 👤 Nobuo Sakuma
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 11:22
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/04; H04N1/113; H04N1/1135; G; G02; G02B; G02B26/00; G02B26/08; G02B26/10; G02B27/00; G02B27/0025; G02B27/0031; G02B5/00; G02B5/08; G02B5/09
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
125 words
A post-objective type scanning device having reduced image surface curvature comprising a deflector whose reflection surface is a convex spherical surface having a radius R or a cylindrical mirror, a photosensitive surface in which a light beam deflected by said deflector scans and a cylindrical optical element installed in the neighbourhood of said photosensitive surface, characterized in that if the radius of said deflector is R and the relation of L o =L.sub.θ is present, where L o is the length from the deflecting point to the scanning surface when the rotational angle of the deflector is O and L.sub.θ is the length from the deflecting point to the scanning surface at said rotational angle θ, the following relation is established: R={(1/cos θ)+cos θ/(1+cos θ)-1}L.sub.o.
Claim 2
Dependent Claim
125 words
A post-objective type scanning device having reduced image surface curvature comprising a deflector whose reflection surface is a convex spherical surface having a radius R or a cylindrical mirror, a photosensitive surface in which a light beam deflected by said deflector scans and a cylindrical optical element installed in the neighbourhood of said photosensitive surface, characterized in that if the radius of said deflector is R and the relation of L o =L.sub.θ is present, where L o is the length from the deflecting point to the scanning surface when the rotational angle of the deflector is O and L.sub.θ is the length from the deflecting point to the scanning surface at said rotational angle θ, the following relation is established: R={(1/cos θ)+cos θ/(1+cos θ)-1}L.sub.o.
Claim 3
Dependent Claim
97 words
A post-objective type scanning device according to claim 1 wherein the radius of curvature of a reflection surface of the deflector is R=153.480 mm, the focal length of the cylindrical optical elements, which is a lens installed in the neighbourhood of the photosensitive surface, is fc=27 mm, the length from the photosensitive surface to the cylindrical lens is s o =30 mm, the length from the deflecting point to the photosensitive surface is L o =300 mm, and the deflection angle in which the length L.sub.θ to the scanning surface is equal to L o is 20°.
Claim 4
Dependent Claim
98 words
A post-objective type scanning device according to claim 1 wherein the radius of curvature of a reflection surface of the deflector is R=301.720 mm; the focal length of the cylindrical optical element, which is a lens installed in the neighbourhood of the photosensitive surface, is fc=28.5 mm, the length from the photosensitive surface to the cylindrical lens is s o =30 mm, the length from the deflecting point to the photosensitive surface is L o =600 mm, and the deflection angle in which the the length L.sub.θ to the scanning surface is equal to L o is 10°.
Claim 5
Dependent Claim
42 words
A post-objective type scanning device according to claim 1 wherein the cylindrical optical element is a focusing lens placed a length s o from the scanning surface, where s o =(1-l o )L o , and s o is approximately 30 mm.
References Cited (Backward Citations)
US3320255A
Cited
US4318583A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-12-08 | 1990-06-09 | 1990-12-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-12-08 | 1994-06-09 | 1994-12-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-12-08 | 1998-06-09 | 1998-12-09 | $7700.00 | Window Closed / Lapsed |