Patent Number: 8,818,244

Title: Developing device and image forming apparatus

Abstract: A developing device for developing an electrostatic latent image on an image bearing member including a developer bearing member opposed to the image bearing member to bear thereon a developer including a toner and a magnetic carrier; a developer containing part to contain the developer to supply the developer to the developer bearing member; an agitating or feeding member to agitate or feed the developer in the developer containing part; a magnetic permeability sensor to measure magnetic permeability of the developer to determine toner concentration of the developer; a developer feeder; a feeding member to feed the developer to the developer containing part through the developer feeder; and a driver to drive the feeding member independently of the agitating or feeding member. The magnetic permeability sensor is arranged on the developer feeder.

Inventors: Hirayama; Yushi (Kanagawa, JP), Ishibashi; Hitoshi (Kanagawa, JP), Hirai; Shuji (Tokyo, JP), Kaneko; Satoshi (Kanagawa, JP), Muroi; Hideo (Kanagawa, JP)

Assignee: Ricoh Company, Ltd.

International Classification: G03G 15/08 (20060101)

Expiration Date: 8/26/12018