Patent ID: 7586511

Claim:
An image forming apparatus comprising: a light source; an image bearing member; a segment device for dividing a main scan line on the image bearing member scanned by a laser beam emitted from the light source, into a plurality of segments each constituted by a plurality of pixels; an image clock generating device for generating image clocks for the respective segments; an image forming unit for forming a reference image based on the image clocks generated by the image clock generating device; a reading unit for reading the reference image formed by the image forming unit; a detecting device for detecting a shift between an ideal laser irradiation location and an actual laser irradiation location based on the reference image read by the reading unit; and a correcting device for correcting the shift of the laser irradiation location in accordance with the detection results obtained by the detecting device, wherein the detecting device separates the plurality of segments in units of blocks of continuous segments, and detects a shift between a predesignated ideal laser irradiation position and an actual laser irradiation position, in units of blocks, based on the reference image formed by the image forming unit, and wherein, in accordance with the detection results obtained by the detecting device, the correcting device controls the image clocks for a part of the plurality of segments constituting each block to correct the shift of the laser irradiation position in units of blocks.