US Patent 7535612 Optical scanner and image forming apparatus including same

An optical scanner scans a plurality of objects respectively with optical beams and includes a deflector assembly including at least one deflecting unit that deflects the optical beams in a main scanning direction and a plurality of reflection optical systems each including a plurality of reflection mirrors to reflect one of the optical beams and a curvature adjustment unit. The curvature adjustment unit forcibly curves one of the reflection mirrors in a direction opposite the main scanning direction with a holder structure, pushes the reflection mirror in a direction opposite the direction of the forcible curve with a pressure unit, and adjusts a direction and an amount of curvature of a main scanning line by adjusting an amount that the pressure unit deforms the reflection mirror. The main scanning lines on the plurality of objects are curved in a similar direction due to the forcible curve of the reflection mirror.