Multi-beam pitch adjusting apparatus and image forming apparatus

An image forming apparatus, comprising:

• a photoconductive device configured to bear a latent image formed by an optical scanning device;
• a developing device configured to visualize the latent image with toner;
• and
• a transferring device configured to transfer a toner image visualized by the developing device on a transfer sheet,
• wherein the photoconductive device includes:
• 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 state, 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 C1 and C2 by automatically rotating the holding member, wherein
• C1 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,
• C2 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.

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 state, the at least two light source modules including a pair of means for emitting light;
• at least one pair of means for changing a sub scanning direction component of a light beam direction, wherein a sensitivity of at least one of said pair of means for changing is different from another;
• means for holding the at least two light source modules and for rotating each of the at least two light source modules together;
• means for approximating a pair of light beams irradiated from the pair of means for emitting light;
• means for respectively detecting a beam pitch between beam spots formed by the pair of light beams irradiated from the pair of means for emitting light on the scan receiving surface;
• and
• means for initially correcting the beam pitch by automatically rotating at least one of the two light source modules around an optical axis and for secondly adjusting a distance between points C1 and C2 by automatically rotating the holding means, wherein
• C1 is a virtual middle position between beam spots created by the pair of light beams irradiated from the pair of means for emitting light in a first of the at least two light source modules,
• C2 is a virtual middle position between beam spots created by the pair of light beams irradiated from the pair of means for emitting light 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.