Optical scanning unit, image forming apparatus, and method of correcting positional misalignment

摘要

An optical scanning unit includes an optical deflector, a plurality of scanning optical systems, and a pixel-clock generating unit. A photodetector is arranged in at least two locations on a writing-start side and a writing-end side outside the writing area. The optical scanning unit measures a scanning time, and corrects respective dot positions of image data in the writing area to arbitrary positions based on an amount of fluctuation of the scanning time measured.