Patent ID: 7432943

Claim:
An image forming apparatus which comprises a plurality of image forming stations arranged in parallel, each of image forming stations having a photosensitive drum, and which forms a desired image by combining toner images formed on the photosensitive drums, said image forming apparatus comprising: a scanning optical system for deflecting and scanning a plurality of laser beams concurrently with a single deflector to irradiate the photosensitive drums, wherein: at least one of the photosensitive drums is controlled to change its rotation speed with a change in print mode; and in a case wherein the print mode is changed and accordingly the rotation speed of the at least one of the photosensitive drums is changed, synchronization of writing in a main scanning direction is performed by using one of the laser beams irradiating the photosensitive drums which are not used for image formation in the newly set print mode.