Patent ID: 7187397
Filing Date: 2007-03-06
Classification: B41J,G02B,H04N

Abstract:
1. A light beam scanning apparatus comprising: emitting devices which emit a plurality of light beams; a beam scanner which reflects the plurality of light beams emitted from said emitting devices towards a to-be-scanned surface to scan the to-be-scanned surface by use of the plurality of light beams; a first detector which detects the light beam scanned on the to-be-scanned surface by said beam scanner and generates an output which is continuously changed with a variation in the passage position of the light beam in a sub-scanning direction perpendicular to a main scanning direction of the light beam; a second detector disposed separately from said first detector in the main scanning direction and having a width in the main scanning direction which is equal to a traveling distance of the light beam on said first detector passed when the light beam scans the first passage position; a third detector disposed separately from said first detector in the main scanning direction and having a width in the main scanning direction which is equal to a traveling distance of the light beam on said first detector passed when the light beam scans the second passage position, the second passage position being separated from the first passage position in the sub-scanning direction by a distance corresponding to preset resolution; a position changing unit configured to change the passage position of at least one of the plurality of light beams; and a controller which controls the passage positions of the plurality of light beams to preset positions by use of said position changing unit based on the outputs of said second and third detectors respectively obtained when the light beam has passed through said second and third detectors.