| 摘要 |
PURPOSE:To form an optical system being free from a picture drawing distortion by using an inexpensive single lens by providing a frequency modulator and modulating a fundamental clock for taking a timing of switching of a light beam at the time of drawing a picture. CONSTITUTION:When a data processing part 11 reads in picture data to be brought to picture drawing from a recording medium of the outside, the data processing part 11 sends successively the data which is read in, to a converter 12. The converter 12 converts the sent data to raster data and outputs it to an optical modulator 15, and the optical modulator 15 takes a timing of ON and OFF by using a frequency which has been modulated by a frequency modulator 14 as a fundamental clock. The frequency modulator 14 synchronizes a rotation of a rotary polygon mirror 17 and the frequency modulation by receiving a signal from a photodetector 19. In such a way, since the fundamental clock is fluctuated in the same ratio as a fluctuation of a scanning speed, a picture drawing distortion can be corrected, and an optical system being free from the picture drawing distortion can be obtained at a low cost. |
