| 摘要 |
PROBLEM TO BE SOLVED: To reduce the shift of the positions of beam spots on a face to be scanned in a short time during a job. SOLUTION: The light receiving face of photodetecting sensors 141A to 141D, which receive light beams scanned with a scanning optical system 100, has a shape that the width in a main scanning direction varies from the central part in a subscanning direction to the other parts. Thus, the time during which the light beams are made incident on the light receiving face for scanning the central part in the subscanning direction is different from the time for scanning the other parts, and the shift of the positions of the beam spots in the subscanning direction is detected from the difference in the time of scanning. Further, the detection of synchronization in a main scanning direction is also possible by the photodetecting sensors which can simultaneously serve as elements for detecting the shift of positions and as elements for detecting synchronization. COPYRIGHT: (C)2007,JPO&INPIT
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