摘要 |
A color copying machine has 4 color image forming units arranged at equal spaces along a first direction above a conveyor belt endlessly running in the first direction. Images formed by the image forming units are superimposed and a color images is formed on a paper that is conveyed by the conveyor belt. When correcting misregistration of colors, wedge shaped marks formed on the conveyor belt are detected by sensors and correction amounts based on the detection result are set up. Then, the correction control is executed based on the correction amounts. Further, a straight line mark extending in the second direction orthogonal to the first direction is formed and color misregistration caused by secular speed change of the conveyor belt by the effect of radiant heat is corrected. In this case, a correction amount is changed based on the straight mark detection result.
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