Patent ID: 8107124

Claim:
An image forming apparatus comprising: an image forming portion having a rotator and being configured to form an image on at least one of said rotator and a recording medium traveling with rotation of said rotator; a storage portion configured to store change characteristics information relevant to correction parameters corresponding to phase points of said rotator; a first designating portion configured to determine a first estimated phase point as an estimation of a current phase of said rotator based on a base time point, and designate, as a designated parameter, the correction parameter corresponding to said first estimated phase point based on said change characteristics information; a correcting portion configured to correct an image forming position on said at least one of said rotator and said recording medium based on said designated parameter; a detecting portion configured to detect that said rotator has reached a detecting phase point; and a changing portion configured to change a value of said designated parameter into an adjusted value intermediate between said designated parameter and a reference parameter so that said correcting portion corrects the image forming position based on said adjusted value, said reference parameter being a correction parameter designated from said correction parameters based on a time when said detecting portion detects said detecting phase point.