Patent ID: 7639974

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, respectively; an intermediate transfer member onto which the plurality of unicolor toner images are successively transferred one by one in such a manner that the plurality of unicolor toner images are superimposed on each other, so as to form a full color toner image on a toner-image bearing surface of the intermediate transfer member; a secondary transferring section to transfer the full color toner image, formed on the toner-image bearing surface of the intermediate transfer member, onto the transfer material; and a pre-secondary transfer charge eliminating section disposed between the plurality of primary transferring sections and the secondary transferring section, including a plurality of discharge devices aligned along the toner-image bearing surface of the intermediate transfer member and an opposing electrode aligned along another surface of the intermediate transfer member opposing to the plurality of discharge devices; wherein each of the plurality of discharge devices includes a discharging electrode and a grid electrode; and wherein an electric potential difference between the grid electrode disposed at an upstream side in a rotating direction of the intermediate transfer member and the opposing electrode, is greater than that between the grid electrode disposed at a downstream side in a rotating direction of the intermediate transfer member and the opposing electrode.