Scanner apparatus and image forming apparatus
AssigneeBrother Kogyo Kabushiki Kaisha
InventorYasuo Tamaru
Life of this patent
Estimating the term…
Abstract
A polygon mirror is placed so that its rotation axis is positioned on a center line in a main scanning direction of an image forming area scanned by each light beam. Moreover, two light beam irradiating optical units are placed so that the light beams are incident on reflective surfaces of the polygon mirror from directions that cross the line and are point symmetrical to each other with respect to the rotation axis of the polygon mirror. Further, two fθ lenses are placed so that their lens center positions are displaced in mutually opposite directions from the center line in the main scanning direction of the image forming area.
Claims8
A scanner apparatus for scanning an image forming area with a light beam, comprising:
- a polygon mirror with a plurality of reflective surfaces for directing a light beam reflected thereby to the image forming area, and scanning the light beam in a scannable area wider than the image forming area in a main scanning direction by rotating on its rotation axis;
- a plurality of light beam emitting units for emitting light beams to the reflective surfaces from directions that cross a center line in the main scanning direction of the image forming area and are point symmetrical to each other with respect to the rotation axis of said polygon mirror;
- and
- a plurality of fθ lenses for scanning the light beams at equal speed in the image forming area, said fθ lenses being disposed so that their lens center positions through which the light beams directed to a center position in the main scanning direction of the scannable area pass are displaced in mutually opposite directions from the center line in the main scanning direction of the image forming area,
- wherein the image forming area is set so that the center line in the main scanning direction of the image forming area passes through the rotation axis of said polygon mirror.
An image forming apparatus comprising:
- a plurality of photoconductors;
- and
- a scanner apparatus for scanning an image forming area with a light beam,
- wherein said scanner apparatus comprises:
- a polygon mirror with a plurality of reflective surfaces for directing a light beam reflected thereby to the image forming area, and scanning the light beam in a scannable area wider than the image forming area in a main scanning direction by rotating on its rotation axis;
- a plurality of light beam emitting units for emitting light beams to the reflective surfaces from directions that cross a center line in the main scanning direction of the image forming area and are point symmetrical to each other with respect to the rotation axis of said polygon mirror;
- and
- a plurality of fθ lenses for scanning the light beams at equal speed in the image forming area, said fθ lenses being disposed so that their lens center positions through which the light beams directed to a center position in the main scanning direction of the scannable area pass are displaced in mutually opposite directions from the center line in the main scanning direction of the image forming area,
- wherein the image forming area is set so that the center line in the main scanning direction of the image forming area passes through the rotation axis of said polygon mirror.
Dependencies are inferred from the claim text.