Color image forming apparatus and process cartridge therefor

A color image forming apparatus configured to execute a sequence of steps of charging a surface of a photoconductive belt with a charger, exposing said surface with an exposing unit imagewise to electrostatically form a latent image on said surface and developing said latent image with a developing unit to form a corresponding toner image, repeat said sequence of steps a plurality of times to form toner images of different colors on said photo conductive belt one above the other and transfer a resulting composite color image to a recording medium with an image transferring unit, the color image forming apparatus comprising:

• a first-color developing unit configured to form a toner image on the photoconductive belt;
• and
• a second-color developing unit and successive developing units, at least said second-color and successive developing units each comprise an electrostatic developing unit including,
• an electrostatic toner conveying device comprising a plurality of electrodes arranged on an annulus of the electrostatic toner conveying device at preselected intervals in a direction of toner conveyance and each extending in a direction substantially perpendicular to said direction of toner conveyance, and
• a toner feeding device configured to feed the toner to said electrostatic toner conveying device,
• wherein voltages applied to said plurality of electrodes form a traveling-wave electric field for electrostatically transferring the toner, an electric field for causing said toner to electrostatically move toward the latent image formed on said photoconductive belt is formed, and toners not moved toward the latent image are directly conveyed to the toner feeding device by the electrostatic toner conveying device.