| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which is capable of accurately put images one over the other during image formation and is capable of easily aligning images in the case of a change in driving speed of a belt. <P>SOLUTION: A pitch measuring part 111 measures pitches being intervals of marks added at fixed intervals in a moving direction, and an expansion/contraction amount calculating part 112 calculates an expansion/contraction amount of the belt rotating at a prescribed speed, on the basis of measured pitches, and an average expansion/contraction amount calculating part 114 calculates a first average expansion/contraction amount being an average value of a plurality of expansion/contraction amounts in accordance with movement at a first speed of the belt and calculates a second average expansion/contraction amount being an average value of a plurality of expansion/contraction amounts in accordance with movement at a second speed of the belt, and a position correction amount calculating part 117 calculates a position correction amount for correcting an image write position for image formation at the second speed on the basis of a difference value between the first expansion/contraction amount and the second average expansion/contraction amount, and a control part 118 controls the write position on the basis of the calculated position correction amount. <P>COPYRIGHT: (C)2007,JPO&INPIT |
