Patent ID: 7783233

Claim:
A developing device for an image forming apparatus using developing agent supplied from a supplying device, said developing device comprising: a developing roller configured to bear the developing agent thereon and develop a toner image on an image bearing member of the image forming apparatus; and a supply and circulation system configured to receive developing agent from the supplying device, said system being configured to supply the developing agent to said developing roller and circulate the developing agent within said developing device, said system including: an agitate conveying member, and a circulation route having at least a portion that extends upward, wherein said agitate conveying member is provided within said upwardly extending portion of said circulation route, wherein said agitate conveying member is configured to convey the developing agent upward through said upwardly extending portion of said circulation route, wherein said upwardly extending portion includes a space configured to allow some of the developing agent being conveyed through said upwardly extending portion to fall, wherein said upwardly extending portion includes a wall enclosing said agitate conveying member, the space includes a gap between an inner surface of said wall and a periphery of said agitate conveying member, and the gap is in a range of 0.5 to 1.5 mm.