The present invention relates to a color image forming device for forming toner
images of a plurality of colors on a medium, and is for improving second transfer
efficiency from an intermediate transfer body to the medium. The device has image
forming units (12-1 to 12-4) for forming the toner
images of the plurality of colors on at least one image bearing body (14-1
to 14-4) by a plurality of developing units (22-1 to
22-4) respectively accommodating toner of different colors; an intermediate
transfer body (24); primary transfer means (38-1 to 38-4)
for primary transferring the toner images of the plurality of colors onto the intermediate
transfer body sequentially for the respective colors; and secondary transfer means
(45) for secondary transferring the toner images of the plurality of colors
on the intermediate transfer body onto the medium. The image forming units form
the toner images of the plurality of colors so that the potentials of toner layers
transferred onto the intermediate transfer body (24) are progressively lower
in the order in which the plurality of colors are transferred. Since the potential
of the toner layer directly adhered to the intermediate transfer body is higher,
the directly adhered toner layer becomes easier to be secondary-transferred, and
thereby, the secondary transfer efficiency is improved and the reproducibility
of the secondary color is improved.
