Patent ID: 6873346

Claim:
An image forming apparatus, comprising: an optical element unit that generates a laser beam; a rotating deflector that deflects the laser beam while rotating; a photoconductor, an image of a color being formed on the photoconductor when the photoconductor is scanned by the deflected laser beam and processed by a developing agent, a spot of the laser beam on the photoconductor moving along a first direction when the laser beam is deflected by the rotating deflector; a turnable transfer member, a plurality of the images having different colors formed on the photoconductor being transferred to a predetermined position of the turnable transfer member in sequence each time the turnable transfer member turns one cycle; a displacement driving unit that moves the optical element unit, the spot of the laser beam on the photoconductor being displaced in a second direction when the optical element unit is moved by the displacement driving unit; first detection means for outputting a first signal each time the turnable transfer member turns one cycle; second detection means for outputting a second signal when the laser beam starts to scan the photoconductor in the first direction; and calculating means for calculating a time difference between the first signal and the second signal, wherein the displacement driving unit moves the optical element unit to displace the spot of the laser beam in the second direction by a distance to change a starting position of forming each of the plurality of images of different colors on the photoconductor, the distance being determined by the time difference.