Developing device for suppressing variations in bulk density of developer, and an image forming apparatus including the developing device

摘要

A developing device (20M, 20C, 20Y, 20BK) includes a developer (28M, 28C, 28Y, 28BK) including toner including a coloring agent dispersed in a binder resin, and carrier including a core material, and a coating layer covering the core material and containing a binder resin and a powder, a toner denisty detecting device (26M, 26C, 26Y, 26BK) that detects a toner density of the developer (28M, 28C, 28Y, 28BK) by use of a bulk density sensor, and a control device (30M, 30C, 30Y, 30BK) that controls the toner density based on a detection result of the toner density detecting device (26M, 26C, 26Y, 26BK). A ratio (D/h) of an average particle diameter (D) of the powder in the coating layer to a thickness of the coating layer is greater than 1 and less than 10.