Back to results
US 8,711,457 B2Granted
Optical scanner and image-forming device
AssigneeBrother Kogyo Kabushiki Kaisha
InventorsRyota Kato, Shogo Mori
Life of this patent
Estimating the term…
Abstract
An scanning unit scanner includes a light source and a polygon mirror unit. A front-to-rear rib is disposed between the light source and the polygon mirror unit and near the polygon mirror unit. An input side opening having a slit shape is formed as a cutout in the top edge of the front-to-rear rib. When laser light from the light source passes through the input side opening, the input side opening restricts the width of the light in a main scanning direction.
Claims9
An optical scanner comprising:
- a light source that emits a light;
- a deflecting unit that deflects and scans the light in a main scanning direction;
- a shielding rib disposed near the deflecting unit and between the light source and the deflecting unit, the shielding rib being formed with a first aperture that allows the passage of the light from the light source while restricting a width of the light;
- and
- a scanning optical system that forms images on a photosensitive surface of a photosensitive member with the light deflected and scanned by the deflecting unit;
- wherein:
- the deflecting unit includes a polygon mirror having a plurality of reflecting surfaces that reflect the light from the light source, the polygon mirror rotating around a rotational axis;
- and
- the light source, the scanning optical system, and the polygon mirror are arranged such that the light from the light source that is incident on the polygon minor is reflected from a first one of the reflecting surfaces of the polygon mirror other than a second one of the reflecting surfaces that is oriented orthogonal to an optical path of the incident light, and that the reflected light forms an image on the photosensitive surface;
- the scanning optical system includes an fθ lens that converts the light deflected and scanned by the deflecting unit into a light scanned at a constant speed over the photosensitive surface;
- and
- the light source, the scanning optical system, and the polygon mirror are arranged to satisfy the equation:
- α/2+W/(2*f)−2π/N>0
- wherein:
- α is an angle formed by an optical path of the light from the light source to a point of reflection on the reflecting surface of the polygon mirror and a straight line connecting the point of reflection with a center point in the main scanning direction of an effective scanning region in which the light is scanned over the photosensitive surface;
- W is ½ the width of the effective scanning region in the main scanning direction;
- f is a focal length of the fθ lens;
- and
- N is the number of reflecting surfaces.
16 more elements
An image-forming device comprising:
- a light source emitting a light;
- a deflecting unit that deflects and scans the light in the main scanning direction;
- a shielding rib disposed near the deflecting unit and between the light source and the deflecting unit, the shielding rib being formed with a first aperture that allows the passage of the light from the light source while restricting a width of the light;
- a photosensitive member having a photosensitive surface;
- and
- a scanning optical system that forms images on the photosensitive surface with the light deflected and scanned by the deflecting unit;
- wherein:
- the deflecting unit includes a polygon mirror having a plurality of reflecting surfaces that reflect the light from the light source, the polygon mirror rotating around a rotational axis;
- and
- the light source, the scanning optical system, and the polygon mirror are arranged such that the light from the light source that is incident on the polygon mirror is reflected from a first one of the reflecting surfaces of the polygon mirror other than a second one of the reflecting surfaces that is oriented orthogonal to an optical path of the incident light, and that the reflected light forms an image on the photosensitive surface;
- the scanning optical system includes an fθ lens that converts the light deflected and scanned by the deflecting unit into a light scanned at a constant speed over the photosensitive surface;
- and
- the light source, the scanning optical system, and the polygon mirror are arranged to satisfy the equation:
- α/2+W/(2*f)−2π/N>0
- wherein:
- α is an angle formed by an optical path of the light from the light source to a point of reflection on the reflecting surface of the polygon mirror and a straight line connecting the point of reflection with a center point in the main scanning direction of an effective scanning region in which the light is scanned over the photosensitive surface;
- W is ½ the width of the effective scanning region in the main scanning direction;
- f is a focal length of the fθ lens;
- and
- N is the number of reflecting surfaces.
17 more elements
Dependencies are inferred from the claim text.