Patent ID: 7653332

Claim:
An image forming apparatus comprising: latent image carriers; a transfer member to receive sequentially developed images from the image carriers while moving in a given direction there past; image detectors to detect conditions of images, respectively, formed on the transfer member; sensors to detect rotational displacements of the image carriers, respectively; and a controller to do at least the following, perform image-to-image displacement control by doing at least the following, forming a detection image on the transfer member, the detection image including images transferred from the image carriers, and detecting a condition of the detection image via the image detectors, and adjusting image forming timing on the image carriers, respectively; perform speed-variation detection control by doing at least the following, forming a speed-variation detection image on the transfer member, the speed-variation detection image including an image transferred from each of image carriers, detecting a condition of the speed-variation detection image via the image detectors, and determining speed variation of the image carriers, respectively, per one revolution based upon outputs of the image detectors and the sensors; perform phase adjustment control by at least determining phase adjustments for the image carriers, respectively, based on the corresponding speed-variations; and the controller further being operable to perform at least the phase adjustment control and the image-to-image displacement control before performing image forming operations on the image carriers, respectively.