| 摘要 |
PURPOSE: To enhance the flatness and the inclination angle of each outer peripheral flat surface by providing a flat plate in contact with the inner peripheral wall provided perpendicularly to the axial center of a prism at the position of equal distance from both the ends of the prism in the prism, and so disposing the centers of respective mirror surfaces at the equal distance from the axial center. CONSTITUTION: The rotary polygon mirror comprises a cylindrical hexagonal prism 1, mirror surfaces formed on the outer peripheral flat surfaces 1a to 1f of the prism 1, and flat plates 2 provided at a right angle to the axial center CL of the prism 1 at the position of equal distance from both the ends of the prism in the prism 1 and connected integrally to the inner peripheral wall of the prism 1. The mirror surfaces have different inclination angles C to F with respect to the flat surface perpendicular to the axial center CL so that the distances between the centers O of the mirror surfaces and the center CL are equal. Melted resin is filled in a space for molding the plates 2 and the prism 1 from the center of a disc gate 14 in the mold having a space for integrally molding the prism 1 and the plates 2 and a space corresponding to the disc to temporarily block the through hole 3 of the plate 2. |
