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US RE34,156 EGranted
Scanning optical system for use in a laser beam printer
AssigneeAsahi Kogaku Kogyo Kabushiki Kaisha
InventorAkira Morimoto
Life of this patent
Estimating the term…
Abstract
An optical system particularly for a laser beam printer comprising a semiconductor laser, a collimating lens, a cylindrical lens having curvature in the sub-scanning cross section, a deflector and anamorphic scanning lens system concentrating the light on a scanning plane. The anamorphic scanning lens system may have one to four lenses but has one lens with a convex toric surface facing the scanning plane. The anamorphic scanning lens system has stronger power in the sub-scanning cross section than in the main scanning cross section.
Claims25
An optical system comprising:
- a semiconductor laser;
- a collimating lens that produces a beam of generally parallel rays from laser light emitted from said semiconductor laser;
- a cylindrical lens that has a curvature in a first cross section and which once performs a focusing of the laser light to form an image in said first cross section;
- a deflector that is disposed behind a point at which said image has been formed in the first cross section as a result of focusing by said cylindrical lens;
- and
- an anamorphic scanning lens system by which the deflected beam from said deflector is concentrated on a scanning plane[, said anamorphic optical system satisfying the following condition:
- 0.03f<l<0.25f (1)
- where l is the distance between a plane of deflection of said deflector and a point at which said image has been formed in said first cross section as a result of focusing with said cylindrical lens, and f is the focal length of the scanning lens system in a second cross section, substantially perpendicular to said first cross section].
5 more elements
An optical system comprising:
- a semiconductor laser;
- a collimating lens that produces a beam of generally parallel rays of beam from laser light emitted from said semiconductor laser;
- a cylindrical lens that has a curvature in a first cross section and which once performs a focusing of the laser light to form an image in said first cross section;
- a deflector that is disposed behind a point at which said image has been formed in the first cross section as a result of focusing by said cylindrical lens;
- and
- an anamorphic scanning lens system by which the deflected beam from said deflector is concentrated on a scanning plane, said anamorphic lens system being composed, in order from a side of said deflector, of a first, a second and a third lens group;
- a lens of said first lens group being a negative lens that has a concave cylindrical surface with a curvature being present in the first cross section;
- a lens of said second lens group being a convex meniscus lens that has a concave surface directed toward the side of said deflector;
- and
- a lens of said third group having a planar surface on the side of said deflector and a convex toric surface on the side of the scanning plane which has a stronger curvature in the first cross section than in a second cross section perpendicular thereto.
7 more elements
An optical system comprising:
- a semiconductor laser;
- a collimating lens that produces a beam of generally parallel rays from laser light emitted from said semiconductor laser;
- a cylindrical lens that has a curvature in a first cross section and which once performs a focusing of the laser light to form an image in said first cross section;
- a deflector that is disposed behind a point at which said image has been formed in the first cross section as a result of focusing by said cylindrical lens;
- and
- an anamorphic scanning lens system by which the deflected beam from said deflector is concentrated on a scanning plane, said scanning lens system being composed, in order from a side of said deflector, of a first and a second lens group;
- a lens in said first lens group being a negative lens that has a concave cylindrical surface with a curvature being present in said first cross section;
- and
- a lens in said second lens group having a planar surface on a side of said deflector and a convex toric surface on a side of the scanning plane which has a stronger curvature in the first cross section than in a second cross section perpendicular thereto.
6 more elements
An optical system comprising:
- a semiconductor laser;
- a collimating lens that produces a beam of generally parallel rays from laser light emitted from said semiconductor laser;
- a cylindrical lens that has a curvature in a first cross section and which once performs a focusing of the laser light to form an image in said first cross section;
- a deflector that is disposed behind a point at which said image has been formed in the first cross section as a result of focusing by said cylindrical lens;
- and
- an anamorphic scanning lens system by which a deflected beam from said deflector is concentrated on a scanning plane, said anamorphic scanning lens system being composed, in order from a side of said deflector side, of four lens groups;
- a first-group lens being a negative lens that has a concave cylindrical surface with a curvature being present in the first cross section;
- a second-group lens being a convex meniscus lens that has its concave surface directed toward the deflector side;
- a third-group lens having a planar surface on the deflector side and a convex toric surface on the side of the scanning plane which has a stronger curvature in the first cross section than in a second cross section perpendicular thereto;
- and
- a fourth-group lens having convex cylindrical surface which has a curvature in the first cross section.
8 more elements
An optical system comprising:
- a semiconductor laser;
- a collimating lens that produces a beam of generally parallel rays from laser light emitted from said semiconductor laser;
- a cylindrical lens that has a curvature in a first cross section and which once performs a focusing of the laser light to form an image in said first cross section;
- a deflector that is disposed behind a point at which an image has been formed in the first cross section as a result of focusing by said cylindrical lens;
- and
- an anamorphic scanning lens system by which the deflected beam from said deflector is concentrated on a scanning plane, said anamorphic scanning lens system consisting of a single lens group that has a convex toric surface on the side of the scanning plane which has a stronger curvature in the first cross section than in a second cross section perpendicular thereto.
3 more elements
Dependencies are inferred from the claim text.