Patent ID: 7411597

Claim:
An image forming apparatus comprising: an image carrier; a polygonal mirror drive motor configured to drive a polygonal mirror to scan the image carrier with a laser beam emitted from a light source; an intermediate transfer member configured to transfer thereto a toner image formed on the image carrier; a drive roller configured to drive the intermediate transfer member, wherein a perimeter of the intermediate transfer member is substantially an integral multiple of a perimeter of each of the image carrier and the drive roller; an intermediate transfer member position detection unit configured to detect a position of the intermediate transfer member to output an image forming operation start signal; a pattern detection unit configured to detect a registration correction pattern formed on the intermediate transfer member based on the image forming operation start signal; a misregistration variation detection unit configured to read the registration correction pattern detected by the pattern detection unit based on the image forming operation start signal and to generate a reference clock signal based on the read registration correction pattern; and a polygonal mirror drive motor control unit configured to adjust a rotation speed of the polygonal mirror drive motor based on the reference clock signal generated by the misregistration variation detection unit.