Patent ID: 7280786

Claim:
A developing unit utilized in an image-forming apparatus with a photoconductive drum on a circumferential surface of which a photoconductive film is formed, an electrostatic latent image being formed on the photoconductive film, the developing unit comprising: a non-magnetic developing roller for charging and supplying an electrostatic developing toner to the electrostatic latent image formed on the photoconductive film while contacting with the photoconductive film on the photoconductive drum to develop the electrostatic latent image; wherein the electrostatic developing toner comprises iron oxide particles in resin particles, the iron oxide particles functioning as a colorant the amount of the iron oxide particles relative to the toner is 4-7vol %, and the ratio (d/D) between the average particle diameter D of the electrostatic developing toner and the average particle diameter d of the iron oxide particles, is within the range of 0.01-0.03.