Patent ID: 7761042

Claim:
A color image forming apparatus for forming a color image onto a transfer material by superimposing a plurality of unicolor toner images, comprising: a plurality of image bearing members to form the plurality of unicolor toner images on the plurality of image bearing members, respectively; a plurality of primary transferring sections that correspond to the plurality of image bearing members to transfer the plurality of unicolor toner images formed on the plurality of image bearing members onto an intermediate transfer member so as to superimpose the plurality of unicolor toner images with each other to form a full color toner image on the intermediate transfer member; a secondary transferring section to transfer the full color toner image, formed on the intermediate transfer member, onto the transfer material; and a discharge section disposed at such a position that is located between the plurality of primary transferring sections and the secondary transferring section and opposite to the intermediate transfer member, to apply a bias voltage onto the full color toner image formed on the intermediate transfer member; wherein the discharge section is constituted by a scorotron discharger including a discharging electrode, a grid electrode and a side plate, which are disposed in such a manner that the grid electrode is inserted into a gap formed between the discharging electrode, which is partially enclosed by the side plate, and the intermediate transfer member; and wherein a first voltage having a polarity opposite to that of the full color toner image is applied to the discharging electrode, a second voltage having a polarity same as that of the full color toner image is applied to the grid electrode, and a third voltage having a polarity opposite to that of the full color toner image is applied to the side plate.