| 摘要 |
PROBLEM TO BE SOLVED: To easily control the surface phases of plural polygon mirrors without obtaining the phase control data through an experiment and an evaluation by providing a rotational phase control means. SOLUTION: A polygon mirror 11 is rotated by a polygon motor 12. The laser beams from a laser light source LD are deflected by the outer surfaces of the mirror 11 and scan an LD scanning range D. A rotational position detecting Hall element 13 is provided in the motor 12 and the element 13 outputs signals having the frequency corresponding to the rotation of the motor 12. The phase control of the motor 12 is conducted by inputting the frequency from the element 13 and the rotational frequency from the external to a PLL control section and the mirror 11 rotates at a constant speed. Thus, the direction of the mirror surface of a polygon mirror is easily controlled using a conventional motor rotation controlling circuit and a motor driving circuit as they are. |
