DEVELOPING APPARATUS AND ELECTRONIC PHOTOGRAPH IMAGE FORMING APPARATUS

摘要

Disclosed is a developing apparatus that, even in a discontinuous printing mode having a rest period, can suppress a fluctuation in image density. The developing apparatus comprises at least a developing agent for developing an electrostatic latent image formed on a photoconductor drum, a developing agent carrier for supporting and transporting the developing agent, and a developing agent layer thickness control means disposed near the developing agent carrier for controlling the amount of the developing agent supported and transported on the developing agent carrier. The developing agent is a negatively chargeable monocomponent magnetic toner that comprises magnetic toner particles containing at least a binder resin and magnetic iron oxide particles and having specific saturation magnetization, weight average particle diameter, and composition. The developing agent carrier has a surface layer comprising a binder resin, a quaternary ammonium salt, graphitized particles, and electroconductive spherical resin particles and has a specific surface shape.