| 摘要 |
PROBLEM TO BE SOLVED: To precisely correct a deviation less than one dot in the sub-scan direction by adjusting rotary phases of polygon mirrors of respective laser units. SOLUTION: Large-sized recording is performed by serially continuing scan lines recorded by laser beams deflected by respective polygon mirrors 73a, 73b of first, second laser units. At this time, by adjusting a rotary phase difference between polygon mirrors 73a, 73b of both laser units, the positional deviation of respective scan lines in the sub-scan direction are adjusted. For this purpose, by minutely changing a rotary reference frequency of one side polygon mirror for the other side within the range that rotary phase synchronism doesn't come off, the phase difference between both polygon mirrors is changed, and when it becomes a prescribed phase difference, the rotary reference frequency is returned to the origin, and respective polygon mirrors are rotated at the same speed and at an adjusted and fixed phase. |
