Patent ID: 8305637

Claim:
A multicolor image forming apparatus for forming a multicolor image on a sheet of recording media by superimposing different single-color images one on another, the multicolor image forming apparatus comprising: an exposure unit to direct optical beams for optically writing the different single-color images on respective image carriers; a pattern forming unit to form a positioning pattern on a transport member; a pattern detector disposed above the transport member on a scanning line, to detect the positioning pattern; a positional data detector to detect positional data in a sub-scanning direction of the optical beams; an adjustment unit to detect positional deviations among the different single-color images based on detection results generated by the pattern detector and the positional data detector, respectively, and to correct the positional deviations; and a storage unit to store as reference data the positional data in the sub-scanning direction of the optical beams that is detected when the positional deviations are corrected, wherein: the positional data detector detects current positional data in the sub-scanning direction of the optical beams at a predetermined timing before a subsequent positioning pattern is formed, the adjustment unit corrects the positional deviations based on the reference data and the current positional data in the sub-scanning direction of the optical beam, and when a scanning velocity of the optical beams is multiplied by α that is greater than 0, the reference data is divided by α.