Oblon, Spivak, McClelland, Maier & Neustadt, P.C.
Developing device with improved developer circulation and toner density control
 A developing device for an image forming apparatus includes a developer carrier such as a developing sleeve having a magnetic field generating device therein which carries and conveys a developer containing toner and magnetic carrier particles. The developing device also includes a first regulating member such as a blade which regulates the developer being carried and conveyed by the developer carrier, and a developer storing section stores developer scraped off the developer carrier by the first regulating member. The developer storing section includes a second regulating member arranged upstream of the first regulating member with respect to a direction in which the developer carrier conveys the developer. The developing device further includes a toner storing section provided adjacent to the developer storing section to supply toner to the developer carrier. A contact condition of the developer carried on the developer carrier with the toner supplied to the developer carrier from the toner storing section is varied in accordance with variation of a toner density in the developer carried on the developer carrier to thereby vary a condition of the developer on the developer carrier to attract the toner. The second regulating member is spaced from the developer carrier such that when a thickness of a layer of the developer on the developer carrier increases due to an increase of the toner density in the developer on the developer carrier, the second regulating member regulates an increased amount of the developer being carried and conveyed by the developer carrier. The magnetic fields, toner speeds, and distances of the regulating members to the developer carrier satisfy predetermined conditions in different embodiments. 
Ricoh Company, Ltd.
G
G03G
inventional
Tsuyoshi Hideo Masayuki Shinji Shunji Kiyonori
Imamura Yoshizawa Yamane Tamaki Katoh Tsuda