Patent ID: 9645521
Date: 2017-05-09
CPC Classifications: B41J,G02B,G03G,H04N

Claim:
1. An image forming apparatus, comprising: a light source configured to include a plurality of light emitting elements that are each configured to emit a light beam for exposing a photosensitive member; a deflection unit configured to deflect a plurality of light beams emitted from the plurality of light emitting elements such that the plurality of light beams scan the photosensitive member; a beam detection unit, provided at a position on which a light beam deflected by the deflection unit is incident, configured to generate, in response to the light beam being incident on the beam detection unit, a detection signal that indicates detection of the light beam deflected by the deflection unit; an image forming unit configured to form an image by developing an electrostatic latent image formed on the photosensitive member by exposure using the plurality of light beams; a correction unit configured to execute first correction to cause the image forming unit to form an image for correction and to correct, based on the formed image for correction, relative emission timings according to which the plurality of light emitting elements emit light beams based on image data, and second correction to measure a parameter corresponding to a state of the plurality of light beams scanning the photosensitive member and to correct, based on a value of the measured parameter, the relative emission timings for the plurality of light emitting elements; and a control unit configured to control the light source such that the plurality of light emitting elements emit light beams based on image data in accordance with the relative emission timings corrected by the correction unit, wherein when the first correction is to be executed, the correction unit executes the second correction before executing the first correction, and wherein in the second correction, the correction unit controls the light source such that first and second light emitting elements among the plurality of light emitting elements emit first and second light beams in sequence, and measures, as the parameter, a time interval between two detection signals that are generated by the beam detection unit and that correspond to the first and second light beams.