Patent ID: 7245862

Claim:
A method of adjusting rotational phase of a plurality of image carrying members in an image forming apparatus including an image transferring member and a plurality of detecting units adapted to each detect a corresponding one of a plurality of reference points, each reference point corresponding to a reference rotational position of a corresponding image carrying member, the method comprising: designating one image carrying member as a reference image carrying member; forming, after detection of the reference rotational position of the corresponding image carrying member, a toner image of a pattern on each image carrying member and transferring the toner images onto the image transferring member; detecting elapsed time differentials of each toner image transferred from the image carrying members other than the reference image carrying member based on the toner image transferred from the reference image carrying member, in a direction of movement at a fixed position on the image transferring member; calculating a sum of absolute values of the elapsed time differentials for each toner image and storing the sums as fluctuations in rotational speed of each image carrying member; adjusting rotational phases of the image carrying members, other than the reference image carrying member, with respect to a rotational phase of the reference image carrying member, and repeating the forming, the detecting, and the calculating at substantially the same position on the image transferring member, to thereby obtain fluctuations in the rotational speed of each image carrying member for a plurality of sets; and selecting the position where the fluctuation in the rotational speed is relatively lowest for each image carrying member.