Patent ID: 7509068

Claim:
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 of the sheet, comprising: a conveying path which conveys the sheet; an edge portion detection sensor which detects an edge of the sheet being conveyed, the sensor provided on the conveying path; a mark detection sensor which detects a reference mark formed on the sheet being conveyed, the sensor provided on the conveying path; a first determination section which determines a position of an image to be formed on the back side of the sheet, referring to the edge of the sheet detected by the edge portion detection sensor; a second determination section which determines a position of an image to be formed on the back side of the sheet, referring to the reference mark detected by the mark detection sensor; and a 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.