Optical scanner and image forming apparatus including same

An optical scanner to scan a plurality of objects respectively with optical beams emitted from an optical beam emitter,

• the optical scanner comprising:
• a deflector assembly including at least one deflecting unit configured to respectively deflect 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
• an even number of curvature adjustment units each including a holder structure configured to forcibly curve one of the plurality of reflection mirrors in a direction opposite the main scanning direction and a pressure unit configured to push the reflection mirror in a direction opposite the direction of the forcible curve,
• wherein the curvature adjustment unit adjusts a direction and an amount of curvature of a main scanning line on the object by adjusting an amount that the pressure unit deforms the reflection mirror, and
• in each of the reflection optical systems, a first half of the curvature adjustment units and a second half thereof curve the main scanning line in directions opposite to each other by respectively curving the reflection mirrors forcibly with the holder structures.

An image forming apparatus comprising:

• a plurality of image carriers;
• an optical scanner configured to form electrostatic latent images on the plurality of image carriers through optical scanning, respectively, comprising a deflector assembly including at least one deflecting unit configured to respectively deflect the optical beams in a main scanning direction and a plurality of reflection optical systems;
• a plurality of developing units each configured to develop the electrostatic latent image formed on one of the image carriers;
• and
• a plurality of transferers each configured to transfer the developed image on one of the image carriers to a transfer member,
• wherein each of the reflection optical systems includes a plurality of reflection mirrors to reflect one of the optical beams and an even number of curvature adjustment units each including a holder structure configured to forcibly curve one of the plurality of reflection mirrors in a direction opposite the main scanning direction and a pressure unit configured to push the reflection mirror in a direction opposite the direction of the forcible curve,
• each of the curvature adjustment units adjusts a direction and an amount of curvature of a main scanning line on the image carrier by adjusting an amount that the pressure unit deforms the reflection mirror, and
• in each of the reflection optical systems, a first half of the even number of curvature adjustment units and a second half of the curvature adjustment units curve the main scanning line in directions opposite to each other by respectively curving the reflection mirrors forcibly with the holder structures.