Patent ID: 8036589

Claim:
An image forming apparatus comprising: an image forming mechanism configured to form an image on a first side of a recording medium; a fixing unit configured to fix an image on the recording medium; a reversing unit located downstream of the fixing unit, the reversing unit including a curved path having a large curvature configured to convey the recording medium, reverse the recording medium, and convey the recording medium again to the image forming mechanism for forming an image on a second side of the recording medium; a stopping unit configured to temporarily stop the recording medium between the fixing unit and the image forming mechanism; a sheet position calculating unit configured to calculate positions of a plurality of recording mediums in a sheet conveyance path based on information obtained from a plurality of sheet sensors and a clock; a sheet-to-sheet distance calculating unit configured to calculate distances between the plurality of recording mediums based on the positions calculated by the sheet position calculating unit, the sheet-to-sheet distance calculating unit further configured to calculate a delay time for a sheet in the sheet conveyance path, the delay time based on allowable maximum sheet-to-sheet distances obtained from an allowable maximum sheet-to-sheet distance table; and a sheet conveying controller configured to interface with the sheet-to-sheet distance calculating unit to control a group of driving motors based on the delay time.