Patent ID: 8103180

Claim:
An image forming device, comprising: a medium carrying path configured with to carry a recording medium, an image forming unit configured with at least a plurality of photoreceptor bodies, the photoreceptor bodies being arranged along the medium carrying path, the image forming unit configured to form an image, based on image data, onto the recording medium carried on the medium carrying path; a fixing unit configured to fix the image formed by the image forming unit onto the recording medium; a medium inversion path configured to invert the recording medium where the image has been fixed onto the first surface by the fixing unit to the second surface, and to carry the recording medium to the image forming unit; a first measuring unit placed within the medium carrying path and configured to measure a size of the recording medium when the image is formed on the first surface by the image forming unit; a second measuring unit configured to measure the size of the recording medium prior to another image being formed on the second surface of the recording medium by the image forming unit; and a control unit configured to change the size of printing range based upon the image data that is used to form the image on the second surface of the recording medium in accordance with a ratio of the size of the recording medium measured by the first measuring unit to the size of the recording medium measured by the second measuring unit, wherein the second measuring unit is arranged at a measurement position in the medium inversion path where the second measuring unit begins to measure the size of the recording medium, one of the photoreceptor bodies is arranged at a transfer position where the image on the photoreceptor body at the transfer position is transferred to the recording medium, a first distance from the measurement position to the transfer position is greater than a length of the recording medium, and the photoreceptor body at the transfer position is arranged upstream relative to all other photoreceptor bodies.