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US 4,084,881 AGranted
Light beam scanning device
AssigneeCanon Kabushiki Kaisha
InventorsYoichi Hirabayashi, Setsuo Minami, Takeshi Goshima
Life of this patent
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Abstract
A prism anamorphic optical system is disposed in the path of deflected beam from a rotatable polygonal mirror or a galvano-mirror. This prism anamorphic optical system includes at least two prisms, so that different amounts of displacement of the deflected beam at each angle of deflection and in a direction perpendicular to the direction of deflection caused by the first of the prisms are corrected by the second and subsequent prisms, as viewed from the incidence side. Thus, a straight scanning line may be obtained.
Claims3
A light beam scanning device comprising:
- a source of light;
- a deflecting mirror for causing a light beam from said source to be deflected about an axis toward which said light beam is directed;
- a prism anamorphic afocal optical system for the correction of tilt disposed in the path of the deflected beam from said deflecting mirror, said prism anamorphic afocal optical system comprising a plurality of prisms so that different displacements of the deflected beam at each angle of deflection and in a direction perpendicular to the direction of deflection caused by the first of said prisms are corrected by the second and subsequent prisms, as viewed from the incidence side;
- and
- a condensing optical system disposed between said prism anamorphic afocal system and a surface to be scanned, to thereby cause the deflected beam from said prism anamorphic afocal optical system to be condensed on said surface to be scanned.
2 more elements
Dependencies are inferred from the claim text.