| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to perform appropriate exposure according to the process line speed to a photoreceptor drum.SOLUTION: An optical scanner includes a driving unit that drives a light source outputting a plurality of light beams, and scans a scanning target surface moving in a sub-scanning direction at a predetermined line speed, in a main scanning direction by deflecting the light beams using a polygon mirror rotating at a constant speed. The optical scanner first controls the driving unit to change the number of light beams according to the line speed, and changes the speed of scanning in the main scanning direction by the polygon mirror according to a difference between a predetermined exposure amount and an exposure amount per unit length in the main scanning direction when the number of light beams is changed. When the rotation speed of the polygon mirror is changed, the optical scanner also changes the light intensity of the light source and a writing clock frequency. |
