US Patent 7486919 Transfer apparatus and image forming apparatus

A transfer unit transfers an image formed on an image bearing body (a photoconductive drum or an intermediate transfer belt) onto a medium by an electrostatic force. The transfer unit includes a transfer belt and a transfer roller. The transfer roller extends parallel to the image bearing body and transfers a toner image onto a medium. The transfer roller is pressed toward the image bearing body under a pressing force in a range of 28-112 gf/cm. The transfer belt is held between the transfer roller and the image bearing body in a sandwiched relation to define a transfer point between the transfer belt and the image bearing body. The transfer belt transports the medium through the transfer point.