| 摘要 |
PURPOSE:To obtain a polygon mirror of low cost and high accuracy by specifying the form of a surrounding member, the number of rotations, position of a light reflection surface, and angle of both ends of the light reflection surface in rotational direction. CONSTITUTION:A thickness size in rotational direction of a surrounding member 12 comprising a plastic material of which inner periphery is fixed to an outer surface of a center supporting member 11 and around the outer periphery of which multiple light reflection surfaces 14 are formed in made larger than a thickness size in rotational direction of the center supporting member 11. The number of rotations of a polygon mirror, a distance from the center of the light reflection surface to the center of rotation, and an angle surrounded by two lines from the rotational center to both ends of the light reflection surface in rotational direction are defined by the equation I. In the equation I, h is the levelness (mum) of the light reflection surface 14, omega is the number of rotations (rpm), r is a distance (mm) between the center of the light reflection angle 14 and the center of rotation, x is the cos (theta/2), ..., and thetais an angle surrounded by two lines from the rotational center to both ends of the light reflection surface, E is Young's modulus (kg/mm<2>), rho is density (kg/mm<3>), and lambda is an wave length of laser beam to be used. |
