Patent ID: 7949289

Claim:
An image forming apparatus equipped with multiple image carriers on which images with different color components are formed respectively, and a driving section for rotating said image carriers, wherein multiple adjustment images are formed at a predetermined interval in an image forming region corresponding to the cycle length of one rotation of each image carrier, reference phases for the rotation of the respective image carriers are determined on the basis of maximum portions of divergences between the predetermined interval and a detected interval of each adjustment image, and said driving section is controlled so that the respective reference phases determined are aligned, comprising: a calculating section for dividing the image forming region into a plurality of even-numbered divided regions, the divided regions being a multiple of four, and calculating the divergence amount of each divided region; and a determining section for determining the maximum portions on the basis of the divided regions in which the difference, between the divergence amounts of a first plurality of the divided regions being away from each other by a half cycle length and the absolute value of the difference between the divergence amounts of a second plurality of the divided regions being away from the first plurality of the divided regions by a quarter cycle length and being away from each other by a half cycle, is maximum.