| 摘要 |
PROBLEM TO BE SOLVED: To obtain stable image quality over a long period of time by sticking specific fine grain to an electrostatic latent image carrier, and containing specific toner in a developer. SOLUTION: Fine grain of 1×10<8> -1×10<12> Ωcm in volume resistivity and 20-100 mm in number average grain diameter is stuck to the surface of an electrostatic latent image carrier. A developer formed on the surface of a developer carrier contains toner with the above-mentioned fine grain additionally stuck to the outside of globular toner grain less than 120 in globularity. Titanium oxide, alumina, barium titanate or the like is used as the material of fine grain. Taking account of environmental stability, it is desirable that these fine grains have little hygroscopic property, and in case of inorganic powder with hygroscopic property such as titanium oxide, alumina or silica, material subjected to hydrophobic treatment is used. The toner consists of at least binder resin and a coloring agent. Polyester resin, polyurethane resin or the like is used as the binder resin, and carbon black, nigrosine or the like is used as the coloring agent. |
