Patent attributes
An image forming apparatus that forms an image on a front side of a sheet then reverses the sheet front and back sides and forms an image on the back side, including: a sheet conveying path; a sheet edge portion detection sensor; a sheet reference mark detection sensor; a first determination section for determination of a position of an image to be formed on the back side, referring to a detected edge of the sheet; a second determination section for determination of a position of an image to be formed on the back side, referring to a detected reference mark; and switching section for switching whether to use the first determination section or the second determination section for determination of the position of the image to be formed on the back side of the sheet, based on setting information on double-sided printing to be performed by the image forming apparatus.