| 摘要 |
PURPOSE:To provide an optical deflector which prevents the deformation of a rotary polygonal mirror due to thermal expansion and suppresses the degradation of quality of images formed by deflection scanning. CONSTITUTION:A rotary polygonal mirror 1 is fixed rotatably to the upper part of a rotor 2 with an annular spring member 3, and a resin spacer 6 pressed into between the rotary polygonal mirror 1 and the rotor 2. The resin spacer 6 consists of such a material having a higher thermal expansion coefft. and a smaller Young's modulus than the rotary polygonal mirror 1 and the rotor 2. Thereby, even when the rotary polygonal mirror 1 or the rotor 2 is deformed by head, the resin spacer 6 absorbs deformation so that no deformation is caused in the mirror surface of the rotary polygonal mirror 1. Thus, the deterioration of rotating performance of the rotary polygonal mirror 1 or the degradation of the image quality due to thermal expansion of the rotary polygonal mirror 1 can be prevented. |
