Patent ID: 8437064

Claim:
An optical scanning apparatus comprising: a light source which emits an optical beam; a deflection unit including a rotating polygonal mirror which, having a plurality of reflecting surfaces, deflects the optical beam emitted from the light source so that the optical beam scans an object to be scanned, and a drive unit configured to drive the rotating polygonal mirror; an output unit configured to output a specific surface signal indicative of a specific one of the plurality of reflecting surfaces of the rotating polygonal mirror while the rotating polygonal mirror is rotating; a speed detection unit configured to detect rotational speed of the rotating polygonal mirror; a control unit configured to control the drive unit to perform acceleration or deceleration of the rotating polygonal mirror at a timing associated with the specific surface signal outputted by the output unit, based on a detection result of the speed detection unit, wherein the timing corresponds to a timing when the specific surface is deflecting the optical beam, and the specific surface is a surface such that deviation of length of a scanning line corresponding to the specific surface is relatively smaller as compared to that of others of the plurality of reflecting surfaces.