Image forming apparatus with electrophotographic system

摘要

An image forming apparatus that is capable of simplifying controls for light sources. A polygon mirror with four reflective surfaces deflects light beams emitted from first and second light sources. A housing in which the light sources and the polygon mirror are arranged is configured so that optical paths of the light beams toward the polygon mirror are parallel to a virtual plane containing a rotating axis of the polygon mirror, and so that the light beams are incident on adjoining reflective surfaces of the polygon mirror. First and second driver ICs drive the first and second light sources in one of operation modes. A control unit outputs the same operation mode signal to the first and second driver ICs at the same timing so that the first and second light sources operate in the same operation mode.

主权项

1. An image forming apparatus comprising:
a first light source; a second light source; a rotation polygon mirror configured to have four reflective surfaces and to deflect a light beam emitted from said first light source and a light beam emitted from said second light source with the four reflective surfaces so that the light beam emitted from said first light source scans a first photoconductor and the light beam emitted from said second light source scans a second photoconductor, said rotation polygon mirror being shaped in substantially a square when viewed along a rotation axis of said rotation polygon mirror, and the four reflective surfaces are disposed at sides of said substantially square rotation polygon mirror and arranged in parallel with the rotation axis, respectively; a housing in which said first light source, said second light source, and said rotation polygon mirror are arranged so that an optical path of the light beam emitted from said first light source toward said rotation polygon mirror and an optical path of the light beam emitted from said second light source toward said rotation polygon mirror are parallel to a virtual plane that is parallel to a rotating axis of said rotation polygon mirror and contains the rotating axis, and so that the light beam emitted from said second light source is incident on a reflective surface among the four reflective surfaces that adjoins to the reflective surface on which the light beam emitted from said first light source is incident at an upstream side in a rotating direction of said rotation polygon mirror; a first driver IC configured to drive said first light source in one operation mode among a plurality of operation modes; a second driver IC configured to drive said second light source in one operation mode among the plurality of operation modes; a control unit configured to output a same operation mode signal to both said first driver IC and said second driver IC at a same timing so that the operation mode of said first light source is identical to the operation mode of said second light source; and a first light receiving unit configured to receive a light beam emitted from said first light source, and a second light receiving unit configured to receive a light beam emitted from said second light source, wherein the plurality of operation modes include a light amount control mode, said first driver IC controls a value of a current to said first light source based on a reception result of said first light receiving unit in the light amount control mode, wherein said second driver IC controls a value of a current to said second light source based on a reception result of said second light receiving unit in the light amount control mode, and wherein the control unit outputs the same operation mode signal for changing another operation mode into the light amount control mode to both said first driver IC and said second driver IC at a same timing.