Developing device, and image forming apparatus and process cartridge using the developing device

Abstract

A developing device including a rotating developing roller bearing toner thereon, capable of developing an electrostatic latent image with the toner; a toner layer forming member configured to form a toner layer on the developing roller, and charge the toner of the toner layer at a nip between the developing roller and the toner layer forming member; and a toner supplying device configured to supply fresh toner to the developing device, wherein a charge quantity (q) of the toner on the developing roller varies according to the following equation q(t)=A·{1−exp(−t/tg)} wherein t represents a nip passing time of the toner on the developing roller, tg represents a time constant of charging the toner, and A represents a constant, and wherein the time constant tg is smaller than a rotation time of the developing roller per rotation; and an image forming apparatus and a process cartridge using the developing device.

Dependencies are inferred from the claim text.