Patent ID: 8755086

Claim:
A control method of an image forming apparatus which has photoconductors, an intermediate transfer belt to which developers attached to the photoconductors are transferred, and drive rollers to drive the intermediate transfer belt, the control method comprising: printing test patterns on the intermediate transfer belt by adjusting a printing time interval of the test patterns according to a spatial period of the photoconductors and a spatial period of the drive rollers, if conditions to execute auto color registration (ACR) are satisfied; and executing ACR according to a signal reflected by the test patterns, wherein the printing of the test patterns on the intermediate transfer belt by adjusting the printing time interval of the test patterns according to the spatial period of the photoconductors and the spatial period of the drive rollers includes printing the test patterns by an interval of a value obtained by dividing a spatial period corresponding to the least common multiple of the spatial period of the photoconductors and the spatial period of the drive rollers by K, K being a natural number other than 1.