| 摘要 |
A developing device includes a toner bearing member holding a toner on its surface for conveyance of the toner to a development region where the toner bearing member opposes an image bearing member via a predetermined gap therebetween; a regulating member pressed against the surface of the toner bearing member for regulation of the amount of toner conveyed to the development region; and a developing bias source for applying an alternating electric field between the toner bearing member and the image bearing member. The developing device features the use of the toner bearing member including a conductive substrate formed with an elastic layer, an intermediate layer and a surface layer on the surface thereof, respective volume resistances rho1, rho2 and rho3 of which layers satisfy a condition rho2<=RHO1&LE;RHO3, the toner bearing member having an arithmetic average surface roughness in the range of 0.8 to 2.5 mum, and the use of the toner having a volume-average particle size of 3 to 8 mum.
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