Patent attributes
An image forming apparatus is provided which can form an image without defective transfer even if a resistance value of a transfer device is so high that defective transfer tends to occur. Before starting operation of printing an image on a sheet, a transfer current is passed to a transfer roller so as to detect a voltage value V of a transfer voltage. When it is determined that the detected voltage value V does not exceed a reference voltage value Vr (resistance value of the transfer roller does not exceed a reference limiting value), an operation mode of the printing operation is set to a first printing mode. When it is determined that the detected voltage value V exceeds a reference voltage value Vr (resistance value of the transfer roller exceeds a reference limiting value), the operation mode of the printing operation is set to a second printing mode.
