| 摘要 |
PROBLEM TO BE SOLVED: To prevent color shift from occurring when speed of a drive source of an image carrier is changed. SOLUTION: The image forming apparatus includes: a plurality of photoreceptors 1M to 1K; developing devices 5M to 5K which form visible images on the photoreceptors; a primary transfer bias roller which superposes and transfers the visible images carried on the photoreceptors onto a surface of an intermediate transfer belt 8; an optical sensor unit which detects the visible images on the intermediate transfer belt; and a controller which controls to form predetermined visible images on the respective photoreceptors and transfer them to the surface of the intermediate transfer belt, so as to obtain an image for detecting displacement formed of the visible images, and then corrects image forming start timing for each of the photoreceptors based on detection timing of the visible images, thereby performing timing correction processing for reducing displacement of the superposed visible images, and drive speed control of the photoreceptor. The photoreceptors and the developing devices are driven by different drive sources independently, and the controller changes the speed of the developing device so that a speed ratio of the developing device to the opposite photoreceptor may be always constant. COPYRIGHT: (C)2010,JPO&INPIT |
