| 摘要 |
PURPOSE:To simplify a memory circuit and a delay circuit greatly by adjusting the speed of each rotary polygon mirror driving means individually according to the phase difference of each light beam which is scanned by the rotary polygon mirror. CONSTITUTION:When a 1st beam detection pulse signal 75 and a 2nd beam detection pulse signal 76 are sent out of 1st and 2nd laser beam detectors 69 and 70 while having a phase difference T1, a timer means such as an internal counter circuit measures the phase difference of a rotary phase synchronism controller 2. Then one reference signal PSELECT obtained by selecting one of reference signals P1 - Pn with a selection switch 3 is sent out to a 2nd phase synchronism control part 5 as a reference signal for generating a phase close to the obtained phase difference T1. Consequently, 1st and 2nd motors 63 and 65 are brought under phase synchronism control of 1st and 2nd phase synchronism control parts 4 and 5 with the signal PSELECT for generating the phase difference, 1st and 2nd subsequent signals 75 and 76 are put almost in phase, and the beam reflecting surfaces of 1st and 2nd rotary polygon mirrors 64 and 66 are put in phase. |
