Polygon mirror, light guide device, and optical scanning device

A polygon mirror rotating around a rotational axis, comprising:

• a plurality of sides,
• wherein each of at least two sides of the sides includes:
• a first reflection surface formed in a plane inclined to a plane perpendicular to the rotational axis;
• and
• a second reflection surface formed in a plane inclined to a plane perpendicular to the rotational axis,
• wherein after light which enters into the polygon mirror is reflected by the first reflection surface, the light is reflected by the second reflection surface, and
• wherein at least one of a direction in which the first reflection surface is inclined with respect to a plane perpendicular to the rotational axis and a distance in the direction of the rotational axis between the first reflection surface and the second reflection surface is different among the sides.

A light guide device, comprising:

• a polygon mirror rotating around a rotational axis, the polygon mirror including a plurality of sides,
• wherein each of at least two sides of the sides includes a first reflection surface formed in a plane inclined to a plane perpendicular to the rotational axis and a second reflection surface formed in a plane inclined to a plane perpendicular to the rotational axis,
• wherein after light which enters into the polygon mirror is reflected by the first reflection surface, the light is reflected by the second reflection surface, and
• wherein at least one of a direction in which the first reflection surface is inclined with respect to a plane perpendicular to the rotational axis and a distance in the direction of the rotational axis between the first reflection surface and the second reflection surface is different among the sides;
• a first light reflection unit guiding light deflected by a first side of the sides of the polygon mirror to a first scanning area;
• and
• a second light reflection unit guiding light deflected by a second side to a second scanning area different from the first scanning area.

An optical scanning device, comprising:

• a light guide device including:
• a polygon mirror rotating around a rotational axis, the polygon mirror including a plurality of sides, wherein each of at least two sides of the sides includes a first reflection surface formed in a plane inclined to a plane perpendicular to the rotational axis and a second reflection surface formed in a plane inclined to a plane perpendicular to the rotational axis;
• wherein after light which enters into the polygon mirror is reflected by the first reflection surface, the light is reflected by the second reflection surface;
• and wherein at least one of a direction in which the first reflection surface is inclined with respect to a plane perpendicular to the rotational axis and a distance in the direction of the rotational axis between the first reflection surface and the second reflection surface is different among the sides;
• a first light reflection unit guiding light deflected by a first side of the sides of the polygon mirror to a first scanning area;
• and
• a second light reflection unit guiding light deflected by a second side to a second scanning area different from the first scanning area,
• wherein each of the first light reflection unit and the second light reflection unit includes a plurality of reflection surfaces that reflect the light,
• wherein each of the first light reflection unit and the second light reflection unit reflects the light emitted from the rotating polygon mirror two or more times, and guides the light to an arbitrary irradiated point included in a scanning line that is straight,
• wherein a light path length from an incident position of the light to the polygon mirror to the irradiated point is substantially constant over all the irradiated points in the scanning line, and
• wherein on the scanning line, the scanning speed of the light guided from the polygon mirror by the first light reflection unit and the second light reflection unit is substantially constant.