Patent attributes
A developing apparatus develops an electrostatic latent image formed on a photoconductive drum with toner into a toner image. A developing roller has a surface on which a thin layer of toner is formed. The developing roller has a ten-point height of irregularities Rz such that 1 μm<Rz<DV and in pressure contact with the photoconductive drum to supply the toner to the electrostatic latent image. DV is a volume mean particle diameter. A developing blade is pressed against the surface of the developing roller to form a thin toner layer on the developing roller. The toner has parameters (1) 1 μm<DV<7 μm, (2) 0.9<roundness<0.97, (3) small-diameter particles (not larger than DV×0.5 μm) of not more than 20% by number percentage, (4) large-diameter particles (not smaller than DV×2.0 μm) of not more than 1% by volume percentage.
