Image forming apparatus

A double-sided image forming apparatus, which forms images on both surfaces of a sheet-shaped medium, comprising:

• a first image bearing element to bear a toner image;
• a second image bearing element, mounted opposite said first image bearing element, to bear a toner image;
• a first transfer means for transferring said toner image to a first surface of said sheet-shaped medium from said first image bearing element;
• a second transfer means for transferring said toner image to a second surface of said sheet-shaped medium from said second image bearing element;
• a fixing means for fixing said toner images transferred to said sheet-shaped medium, wherein said sheet-shaped medium is conveyed to said fixing means by said second image bearing element, after said first transfer means transfers said toner image to the first surface of said sheet-shaped medium, and said second image bearing element includes a separating section with a curved shape, located at an end portion of it toward said fixing means, to separate said sheet-shaped medium from said second image bearing element by means of a curvature of said separating section;
• a discharger, disposed opposite to said second image bearing element, to discharge electric charges residing on said sheet-shaped medium, after said toner image is transferred onto said second surface of said sheet-shaped medium;
• a detector to detect thickness and/or stiffness data of said sheet-shaped medium;
• and
• a controller to control a first image forming mode, which enables to form images on both surfaces of said sheet-shaped medium by means of both said first image bearing element and said second image bearing element, and to control a second image forming mode, which enables to form an image on only a single surface of said sheet-shaped medium by means of said first image bearing element, wherein said controller controls said discharging operation of said discharger, said first image forming mode and said second image forming mode, on the basis of the data detected by said detector.