| 摘要 |
PROBLEM TO BE SOLVED: To simplify the structure of an fθlens and lower the cost, and facilitate the assembling operation. SOLUTION: To maintain fθproperties, the time interval of the emission of a light beam is long at a position close to the center of a horizontal scan and short at positions close to the ends of the horizontal scan and then control needs to be performed so that image formation positions of the light beam should be positioned at equal intervals. For the purpose, a projection pattern (arrow S3) with which the beam is emitted at every 9th clock is provided in addition to standard projection patterns (arrows S1, S2, and S4) with which the light beam is emitted at, for example, every 8th clock so as to make the time interval of the projection long at the position close to the center of the horizontal scan. |
