Patent ID: 8369756

Claim:
An image forming apparatus comprising: a transfer-sheet conveying member that rotates to convey a transfer sheet; a first image forming unit that directly transfers a single-color image or images in a plurality of colors onto the transfer sheet that is in a process of being conveyed; an intermediate transfer member that rotates while an image, which is to be transferred onto the transfer sheet that is in the process of being conveyed, is being transferred thereon; a second image forming unit that transfers, onto the intermediate transfer member, images in a plurality of colors except for a color of the image directly transferred by the first image forming unit; a secondary transfer unit that transfers the images transferred onto the intermediate transfer member onto the transfer sheet that is in the process of being conveyed; a measuring unit that measures a surface velocity of each of the transfer-sheet conveying member and the intermediate transfer member for at least one cycle; and a control unit that performs phase matching control by accelerating or decelerating at least one of the transfer-sheet conveying member and the intermediate transfer member so as to match a phase of fluctuation of the measured surface velocity of the transfer-sheet conveying member and a phase of fluctuation of the measured surface velocity of the intermediate transfer member.