OPTICALLY SCANNING OPTICAL DEVICE

摘要

PROBLEM TO BE SOLVED: To prevent timing to write an image on a photoreceptor from becoming incomplete be to of staining of polygon mirror. SOLUTION: In this optically scanning optical device where a laser beam is deflected by the polygon mirror 5 so as to perform scanning and expose the photoreceptor 8, a reflecting mirror for a sensor 9 and a photosensor 10 are arranged corresponding to the back within a deflecting scanning range. The timing for writing image on the photoreceptor 8 is decided, based on a counted value set by each deflectingly reflecting surface of the mirror 5 by counting a reference clock from the time of the laser beam reflected by the front deflecting reflection surface of the mirror 5 being detected.