Patent attributes
An image forming apparatus carries out an image processing with respect to a sheet size and image information based on a print request to obtain a write image on a photoreceptor. On the basis of a printing ratio of the write image, the apparatus predicts occurrence of an image elongation. If the apparatus predicts that the image elongation occurs, the apparatus calculates a bending amount of a bended portion based on the difference between peripheral velocities of a photoreceptor and the idle roller, and the apparatus variably controls the peripheral velocity of an idle roller so that the bending amount is adjusted so as not to cause a slip phenomenon. It is possible to avoid the occurrence of a phenomenon of slipping of a sheet with respect to the photoreceptor without lowering image quality, and to surely secure a blank space formed at a rear edge portion of the sheet.