| 摘要 |
PROBLEM TO BE SOLVED: To accurately maintain beam deflecting function. SOLUTION: This polygon scanner is constituted by forming a cylindrical projecting part 25 projecting in the axial direction on a metallic outer periphery member 21 shrink-fit or press-fit in a ceramic rotating sleeve 7 which is supported by a dynamic pressure bearing 10, forming a boss-like projecting part 28 projecting in the axial direction more to the inside in the radial direction than the reflection surface 22a of a polygon mirror 22, whose coefficient of thermal expansion is substantially matches with that of the member 21 on a mirror 22, and fixedly fitting the outer peripheral surface of the projecting part 28 to the inner peripheral surface of the projecting part 25, whereby the effects of distortion acting on the reflection surface 22a of the mirror 22 is reduced to such as extent that it can be neglected, even if the distortion is caused in a fitting part between the sleeve 7 and the member 21, whose coefficients of thermal expansion are different when temperature rises, so that the beam deflecting function is accurately maintained. |
