Patent ID: 7248820

Claim:
An image forming apparatus comprising: a plurality of image carriers; a plurality of transfer units, each of which is provided corresponding to each of said plurality of image carriers, each of said plurality of transfer units being contacted under pressure with each of said plurality of image carriers through an intermediate transfer body or recording material by the application of pressure when each of said plurality of transfer units is operating and not contacting each of said plurality of image carriers when each of said plurality of transfer units is not operating; a plurality of driving units for driving said plurality of image carriers to rotate at a rotary speed; and a control unit for controlling said plurality of driving units to drive said plurality of image carriers under a feed-forward control and a feed-back control, the control unit controlling said plurality of driving units according to correction information, wherein the correction information used for the feed-forward control is different depending upon a kind of image, wherein said control unit makes said plurality of transfer units to be selectively operated according to the kind of image and said control unit changes a speed control method for said plurality of driving units according to the kind of image, wherein the kind of image includes a full-color image, a mono-chrome image, or a uni-color image.