Back to results
US 2003/0197912 A1Published application
Scanning optical system
AssigneePENTAX Corporation
InventorYutaka Takakubo
Life of this patent
Estimating the term…
Loading patent…
Loading patent…
AssigneePENTAX Corporation
InventorYutaka Takakubo
Estimating the term…
A scanning optical system is provided with alight source that emits at least one beam, an anamorphic optical element that converges the at least one beam in an auxiliary scanning direction, a polygonal mirror, and an imaging optical system. The imaging optical system has a scanning lens, and a compensation lens. One surface of the scanning lens has an anamorphic aspherical surface whose curvature in the auxiliary scanning direction is determined independently from a cross-sectional shape thereof along the main scanning direction. Further, one surface of the compensation lens has an aspherical surface in which a tilt angle of a cross-sectional shape in the auxiliary scanning direction changes with a position in the main scanning direction, the aspherical surface being asymmetrical with respect to a plane perpendicular to the auxiliary scanning direction and including a central point thereof.
A scanning optical system for emitting at least one beam scanning in a main scanning direction, comprising:
Dependencies are inferred from the claim text.
Drawings are temporarily unavailable. Open the PDF at USPTO
From the US filing history. Foreign family members aren’t listed.
Backward citations are indexed for grants only.
Using multifaceted mirrors: details of the optical system between the polygonal mirror and the image plane
Using multifaceted mirrors: multibeam scanners, e.g. using multiple light sources or beam splitters
Optical elements, systems or apparatus
Term end not estimated
The present invention relates to a scanning optical system employed in a scanning optical device such as a laser beam printer or the like.
In a scanning optical system for a laser beam printer, a laser beam emitted by a laser diode is deflected by a polygonal mirror to scan within a predetermined angular range. The scanning beam passes through an fθ lens, which converges the beam to form a scanning beam spot on a photoconductive surface. As the polygonal mirror rotates, the beam spot moves on the photoconductive surface. By ON/OFF modulating the beam spot as it moves, an electrostatic latent image is formed on the photoconductive surface. Hereinafter,a direction, on the photoconductive surface, in which the beam spot moves as the polygonal mirror rotates is referred to as a main scanning direction, while a direction perpendicular to the main scanning direction, on the photoconductive surface, is referred to as an auxiliary scanning direction.
Further, shape and direction of power of each optical element is described with reference to directions on the photoconductive surface. Further, a plane perpendicular to a rotation axis of the polygonal mirror and including an optical axis of a scanning lens is defined as a main scanning plane.
FIG. 1A shows a side view of a light source unit and a polygonal mirror of a scanning optical system to which the present invention is applicable;
FIG. 1B shows an arrangement of laser diodes provided in the light source unit of the scanning optical system viewed from the polygonal mirror;
FIG. 1C shows a side view of the scanning optical system on a photoconductive drum side thereof;
Hereinafter, an embodiment according to the invention are described with reference to the accompanying drawings.
FIG. 1A shows a side view of a light source unit 10 and a polygonal mirror 20 of a so-called tandem scanning optical system 100 to which the present invention is applicable. FIG. 1B shows an arrangement of laser diodes provided in the light source unit 10 viewed from the polygonal mirror. FIG. 1C shows a side view of the scanning optical system 100 on a photoconductive drum side thereof.
As shown in FIG. 1A, the light source unit 10 of the scanning optical system 100 includes eight laser diodes (11,11, . . . ), and eight collimator lenses (12,12, . . . ) which collimate divergent beams emitted by the laser diodes, respectively.