| 摘要 |
PURPOSE:To prevent a vapor-deposited film from spreading around to nonreflecting surfaces and to protect the metal vapor-deposited film end part of reflecting surfaces and prevent the film from peeling by forming steps which are low on the sides of the reflecting surfaces on the borders between the reflecting surfaces and nonreflecting surfaces. CONSTITUTION:One or plural reflecting surfaces 21 are formed by metal vapor deposition on the peripheral surface of a fast rotary body formed of resin and nonreflecting surfaces 22 are provided adjacently to both ends of the reflecting surfaces 21 to constitute the rotary polygon mirror 20, which is provided with the steps 23 which are low on the reflecting surface sides on the borders between the reflecting surfaces 21 and nonreflecting surfaces 22. Therefore, the vapor-deposited film is prevented from spreading around from the mirror surface part of the polygon mirror 20 to the non-mirror surface part and the metallic film at the mirror surface part is prevented from peeling. Further, sags which are easily generated before are not generated on the border between the reflecting surface 21 and nonreflecting surface 22 even as to the molding of the polygon mirror 20, the picture accuracy of the reflecting surface 21 becomes stable, and an excellent image which has no ghost is obtained. |
