Patent ID: 7583927

Claim:
An image forming apparatus comprising: an image forming section for forming images on both sides of a transfer sheet; a reversing section for reversing the transfer sheet on which an image has been formed on one side thereof; a first detecting section to detect the transfer sheet being conveyed; a second detecting section to detect the transfer sheet being conveyed, wherein the second detecting section is arranged to have a predetermined distance from the first detecting section in a direction perpendicular to a conveyance direction; a calculating section for obtaining: a skew amount of a leading edge of the transfer sheet based on a moment when the first detecting section starts detecting the transfer sheet and a moment when the second detecting section starts detecting the transfer sheet; a first length of the transfer sheet at a position where the first detecting section is arranged before reversing the transfer sheet, wherein the first length is obtained based on a result output by the first detecting section; a second length of the transfer sheet at a position where the second detecting section is arranged before reversing the transfer sheet; a skew amount of a trailing edge of the transfer sheet based on a difference between the first length of the transfer sheet and the second length of the transfer sheet; a first correction amount for correcting a skew of the leading edge; and a second correction amount for correcting a skew of the trailing edge; and a correcting section that changes a relative position between the transfer sheet and the image on the one side of the transfer sheet in accordance with the first correction amount obtained by the calculating section, and that further changes a relative position between the transfer sheet and an image on the other side of the transfer sheet in accordance with the second correction amount obtained by the calculating section.