Patent ID: 8155565

Claim:
A developing device for developing an electrostatic latent image formed on an image bearer with a developer that has been triboelectrically-charged by mixing and agitation of two components, toner and magnetic carrier, comprising: a developing hopper for storing the developer; an agitation and conveying member that is rotationally driven inside the developing hopper for conveying the developer while agitating; a developer support which supports the developer that has been mixed and agitated inside the developing hopper and supplies the developer whilst being rotationally driven to a developing area located opposing the image bearer; a layer thickness-regulating member for regulating the layer thickness of the developer being conveyed by the developer support; a flow-guide plate member for flowing down the surplus developer that was rejected by the layer thickness-regulating member to a place located away from the layer thickness-regulating member; a plurality of diffusing elements arranged upright on the flow-guide plate member for flowing down the surplus developer in a predetermined direction whilst diffusing the developer with respect to the longitudinal direction of the developer support; and a downflow direction control mechanism for controlling the downflow direction of the surplus developer by the diffusing elements, in accordance with the coverage ratio of black solid area in print documents with respect to the longitudinal direction of the developing hopper, wherein the downflow direction control mechanism is controlled such that the angle of the downflow direction that is regulated by the diffusing elements is made greater in accordance with the rotational speed of the developer support.