Patent ID: 8385760

Claim:
An image forming apparatus comprising: an image information reception device configured to receive image information; at least one latent image bearer configured to rotate and bear a latent image; a latent image writing device configured to write the latent image at a prescribed latent image writing position on the surface of the at least one latent image bearer in accordance with the image information; a developing device configured to developing the latent image and obtain a toner image on the surface; a transfer device configured to transfer the toner image from the at least one latent image bearer onto a transfer receiving member at a prescribed transfer position; a conveyance device configured to convey the transfer receiving member in the same direction as the at least one latent image bearer moves at the prescribed transfer position; an image detector configured to detect expansion and contraction on a pattern image formed and transferred from the at least one latent image bearer onto the transfer receiving member at a pattern image detection position; a driving source configured to provide a driving force; a common drive force transmission system configured to transmit the driving force to the at least one latent image bearer and the conveyance device, said common drive transmission system including at least one transmission member; a rotational position detector configured to detect a rotational position of the at least one transmission member, said at least one transmission member causing fluctuation of a velocity of one of the at least one latent image bearer and the transfer receiving member in a cycle per rotation of the at least one transmission member; and a control device configured to control formation of the pattern image while driving the common drive source at a prescribed velocity, wherein said control device recognizes expansion and contraction of the pattern image based on an output of the image detector, said control device calculating a driving motor velocity cancellation fluctuation pattern for driving the common drive source, said driving motor velocity cancellation pattern creating a latent image expansion and contraction cancellation pattern configured to cancel, at the prescribed latent image writing position, the expansion and contraction of the pattern image detected by the image detecting device, wherein a process of calculating said cancellation patterns is executed except when a print job for forming the toner image is executed in accordance with the image information, wherein said control device controls the common drive source in accordance with the driving motor velocity cancellation pattern, and wherein said latent image expansion and contraction cancellation pattern includes the same amplitude and an opposite phase to the expansion and contraction of the pattern image detected by the image detector.