| 摘要 |
PURPOSE:To realize the minute expression of gradation in the case of printing. CONSTITUTION:This scanner is provided with a polygonal mirror 12 where a 1st reflection surface 12a parallel with a rotary shaft 11 and a 2nd reflection surface 12b inclined against the rotary shaft by an angle theta are alternately arranged, and by which the scanning by a laser beam made incident on the respective reflection surfaces by rotation is performed, a 1st laser diode 13 irradiating the 1st reflection surface of the mirror 12 with the laser beam b1, and a 2nd laser diode 14 irradiating the 2nd reflection surface of the polygonal mirror with the laser beam b2 whose power is smaller than the laser beam b1 from the 1st laser diode 13; and the respective laser diodes 13 and 14 are selectively operated so that the scanning lines by the laser beams b1 and b2 from the laser diodes 13 and 14 on the photosensitive surface of a photosensitive drum 15 may be aligned. |
