| 摘要 |
PURPOSE: To reduce the weight of a polygon mirror and to improve high-speed stable rotating performance by forming a mirror part and a bearing part to hollows. CONSTITUTION: This polygon mirror consists of a synthetic resin, such as polycarbonate, and a fixing hole 32 to be fitted with a revolving shaft is formed in its central part. Namely, the section where this fixing hole 32 is formed constitutes the bearing part 31a. The polygon mirror is formed to a hexagonal shape and has six mirror surfaces 33 in side face parts constituting the mirror parts. Further, the polygon mirror has internally the hollow part 34 and this hollow part 34 is formed at the time of injection molding of the polygon mirror by a synthetic resin, such as polycarbonate. In such a case, the mechanical strength is increased by making the thickness of the fixing hole 32 larger by >=1.2 times than the thickness of the mirror surfaces 33, by which the safety is improved. Such polygon mirror is made of the hollow resin, by which the drastic reduction in the weight is made possible. |
