Patent ID: 7460145

Claim:
An optical scanning apparatus comprising: a light source including at least two light source modules configured to irradiate and scan a scan receiving surface with a pair of light beams in a spot states the at least two light source modules including a pair of semi-conductor laser diodes; at least one pair of beam direction changing devices configured to change a sub scanning direction component of a light beam direction, wherein a sensitivity of at least one of said pair of beam direction changing devices is different from another; a holding member configured to hold the at least two light source modules and to rotate each of the at least two light source modules together; a light beam-approximating device configured to approximate a pair of light beams irradiated from the pair of semi-conductor laser diodes; a beam pitch detecting device configured to respectively detect a beam pitch between beam spots formed by the pair of light beams irradiated from the pair of semi-conductor laser diodes on the scan receiving surface; and a beam pitch correcting device configured to initially correct the beam pitch by automatically rotating at least one of the two light source modules around an optical axis and to secondly adjust a distance between points C 1 and C 2 by automatically rotating the holding member, wherein C 1 is a virtual middle position between beam spots created by the pair of light beams irradiated from the pair of semi-conductor laser diodes in a first of the at least two light source modules, C 2 is a virtual middle position between beam spots created by the pair of light beams irradiated from the pair of semi-conductor laser diodes in a second of the at least two light source modules, a distance between beams spots included in a same pair of beam spots in a main-scanning direction is shorter than a distance between corresponding beam spots in different pairs of beam spots in the main-scanning direction, and the at least two light source modules are arranged in the main-scanning direction and the pair of semiconductor laser diodes are arranged in a sub-scanning direction.