Optical scanner and image formation apparatus

An optical scanner comprising:

• a plurality of light source units spaced, from each other along a first direction, each having an optical axis along which a light beam from the light source unit is emitted;
• a deflection unit that deflects the light beams together in a single plane at an angle with respect to the light beams and scans the light beams along a second direction perpendicular to the first direction;
• a plurality of imaging units that form an image with each of the light beams on a corresponding surface to be scanned;
• a housing unit that holds the light source units, the deflection units, and the imaging units, the housing unit including a beam merging unit located on the axes between the light source units and the deflection unit, configured to direct the light beams to the deflection unit such that distances between the light beams along the second direction are decreased in a sequence in which the light beams are arranged,
• a beam turning unit that turns the light beams scanned by the deflection unit in a sequence corresponding to the sequence, and
• a plurality of pre-deflection imaging units each located on one of the optical axes between the beam merging unit and the light source unit corresponding to the optical axis, and that converges the light beam from the light source unit in the first direction on a deflection plane of the deflection unit,
• wherein convergences of the pre-deflection imaging units differ from each other relatively to a sequence in which the light source units are aligned in the first direction.

An optical scanner comprising:

• a plurality of light source units spaced from each other along a first direction and configured to emit light beams;
• a deflection unit that deflects the light beams together in a single plane at an angle with respect to the light beams and scans the light beams along a second direction perpendicular to the first direction;
• a plurality of imaging units that form an image with each of the light beams on a corresponding surface to be scanned, and include a lens shared by the light beams and having no defractive power in the first direction;
• and
• a beam merging unit configured to turn at least one of the light beams at a different position, wherein a distance from a turning point on the beam merging unit to a deflection point on the deflection unit decreases for each consecutive light beam along the first direction,
• wherein the beam merging unit includes a plurality of separate mirrors each located on one of the optical axes between the light source units and the deflection unit, each of the plurality of separate mirrors is disposed on a separate bracket that is staggered with respect to other brackets,
• wherein the plurality of imaging units include a plurality of toroidal lenses having an optical face tangle error correction function of the deflection unit, and
• each of the plural toroidal lenses images the respective light beams deflected by the deflection unit in a spot on the corresponding surface to be scanned.

An image formation apparatus comprising:

• an optical write unit that forms latent images on image carriers, a development unit that develops the latent images as toner images;
• and
• a transfer unit that transfers the toner images onto a sheet of paper,
• wherein the optical write unit includes an optical scanner having:
• a plurality of light source units spaced from each other along a first direction and configured to emit light beams;
• a deflection unit that deflects the light beams together and scans the light beams along a second direction perpendicular to the first direction;
• a plurality of imaging units that form an image with each of the light beams on a corresponding surface to be scanned, and include a lens shared by the light beams and having no refractive power in the first direction;
• and
• a beam merging unit configured to turn at least one of the light beams at a different position, wherein a distance from a turning point on the beam merging unit to a deflection point on the deflection unit decreases for each consecutive light beam along the first direction,
• wherein the beam merging unit includes a plurality of separate mirrors each located on one of the optical axes between the light source units and the deflection unit, each of the plurality of separate mirrors is disposed on a separate bracket that is staggered with respect to other brackets,
• wherein the plurality of imaging units include a plurality of toroidal lenses having an optical face tangle error correction function of the deflection unit, and
• each of the plural toroidal lenses images the respective light beams deflected by the deflection unit in a spot on the corresponding surface to be scanned.