Patent ID: 7697184

Claim:
An optical scanning device that is configured to be installed in an image forming apparatus, the optical scanning device comprising: a light emitting unit that emits a light beam; a deflector that deflects and scans the light beam in a main scanning direction on a surface of an image carrier; a plurality of folding mirrors that reflect light from the light emitting unit; a beam detector, that is a spot detector, arranged between a folding mirror closest to the image carrier and the image carrier, the beam reflector being configured to detect a beam position of the light beam deflected by the deflector in a sub-scanning direction; a correcting unit that calculates a correction amount of out-of-color registration based on the beam position, and shifts the beam position to a specified position on the surface of the image carrier based on the correction amount to correct out-of-color registration in the sub-scanning direction prior to irradiation of the image carrier; and a controller that controls, while the beam detector detects the beam position for correction of out-of-color registration, a deflection speed of the deflector to be less than a writing deflection speed for writing a latent image on the surface of the image carrier, wherein the correcting unit corrects out-of-color registration in a period after the deflector is activated and before the deflection speed reaches the writing deflection speed to write a latent image on the surface of the image carrier.