Laser beam scanner

DETAILED DESCRIPTION The invention addresses the forgoing problems and provides a laser beam scanner capable of reducing the width of a beam detector in the sub-scanning direction required for receiving a plurality of laser beams emitted from a plurality of laser light sources.
According to one aspect of the invention, a laser beam scanner for scanning a plurality of laser beams in a main scanning direction includes a plurality of laser light sources, each of which emits a laser beam; a deflector that deflects the laser beam emitted from each of the plurality of laser light sources; a first converging unit that converges, in the main scanning direction and in a sub-scanning direction perpendicular to the main scanning direction, the laser beam deflected by the deflector; a photosensitive member across which the laser beam converged at least in the sub-scanning direction by the first converging unit is scanned; a detector that receives and detects the laser beam converged at least in the main scanning direction by the first converging unit to provide scan start timing of the laser beam, a second converging unit that converges the laser beam emitted from each of the plurality of laser light sources on the deflector; and a third converging unit that converges, in the sub-scanning direction, the laser beam converged at least in the main scanning direction by the first converging unit, on the detector.
A lateral magnification in the sub-scanning direction in an optical path from the deflector to the detector is less than the lateral magnification in the sub-scanning direction in an optical path from the deflector to the photosensitive member.
Each of the laser beams emitted from a plurality of laser light sources is deflected by the deflector.
Then the deflected laser beam, which is converged at least in the sub-scanning direction by the first converging unit, on the photosensitive member.
Meanwhile, the detector detects the laser beam deflected by the deflector and converged at least in the main scanning direction by the first converging unit and converged by the third converging unit in order to provide the scan start timing of the laser beam