Weight-balanced polygonal mirror, light scanning unit using the polygonal mirror, and image forming apparatus
First Claim
Patent Images
1. A polygonal mirror formed of a plastic, the polygonal mirror comprising:
- a plurality of reflection surfaces that are formed on an outer portion of the polygonal mirror and rotate around a rotational axis; and
an internal mirror surface that defines a hole, a ratio of an internal diameter d of the hole to an outer diameter D of the polygonal mirror satisfies 0.1≦
d/D≦
0.3;
grooves formed in the internal mirror surface toward the respective corners of the reflection surfaces, the grooves being dimensioned and configured to balance a mass of the polygonal mirror whereby deformation of the polygonal mirror is reduced during rotation.
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Abstract
A polygonal mirror, a light scanning unit using the polygonal mirror, and an image forming apparatus. The polygonal mirror is formed of a plastic and includes a plurality of reflection surfaces that are formed in an outer portion of the polygonal mirror and rotate around a rotational axis, and an internal mirror surface that defines a hole, wherein a ratio of an internal diameter d to an outer diameter D satisfies 0.1≦d/D≦0.3.
10 Citations
20 Claims
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1. A polygonal mirror formed of a plastic, the polygonal mirror comprising:
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a plurality of reflection surfaces that are formed on an outer portion of the polygonal mirror and rotate around a rotational axis; and an internal mirror surface that defines a hole, a ratio of an internal diameter d of the hole to an outer diameter D of the polygonal mirror satisfies 0.1≦
d/D≦
0.3;grooves formed in the internal mirror surface toward the respective corners of the reflection surfaces, the grooves being dimensioned and configured to balance a mass of the polygonal mirror whereby deformation of the polygonal mirror is reduced during rotation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A light scanning unit comprising:
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a light source to emit a light beam; a polygonal mirror to deflect the light beam emitted from the light source, in a main scanning direction; and an imaging optical system to image the light beam deflected by the polygonal mirror, onto a scanning surface, wherein the polygonal mirror is formed of a plastic and comprises a plurality of reflection surfaces that are formed in an outer portion of the polygonal mirror and rotate around a rotational axis; an internal mirror surface that defines a hole, a ratio of an internal diameter d of the hole to an outer diameter D of the polygonal mirror satisfies 0.1≦
d/D≦
0.3; andgrooves formed in the internal mirror surface toward the respective corners of the reflection surfaces, the grooves being dimensioned and configured to balance a mass of the polygonal mirror whereby deformation of the polygonal mirror is reduced during rotation. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. An image forming apparatus comprising:
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a light scanning unit comprising a light source to emit a light beam;
a polygonal mirror to deflect the light beam emitted from the light source, in a main scanning direction; and
an imaging optical system to image the light beam deflected by the polygonal mirror, onto a scanning surface;a developing unit comprising a photoconductor that is disposed at an imaging point of the light beam emitted from the light scanning unit, wherein an electrostatic latent image is formed on the photoconductor, and a developing roller that develops the electrostatic latent image formed on the photoconductor; and a transfer unit onto which an image developed by the developing unit is transferred, wherein the polygonal mirror is formed of a plastic and comprises a plurality of reflection surfaces that are formed in an outer portion of the polygonal mirror and rotate around a rotational axis; an internal mirror surface that defines a hole, a ratio of an of an internal diameter d of the hole to an outer diameter D of the polygonal mirror satisfies 0.1≦
d/D≦
0.3; andgrooves formed in the internal mirror surface toward the respective corners of the reflection surfaces, the grooves being dimensioned and configured to balance a mass of the polygonal mirror whereby deformation of the polygonal mirror is reduced during rotation.
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Specification