Patent ID: 9366988
Filing Date: 2016-06-14
CPC Classification: G03G

Claim Text:
1. A developing device configured to develop an electrostatic image formed on an image bearing member by a developer containing non-magnetic toner particles and magnetic carrier particles, comprising: a developing member configured to develop the electrostatic image formed on the image bearing member at a developing position, the developing member carrying developer from a supplying position for supplying developer to a collecting position for collecting the magnetic carrier particles to carry the toner particles to the developing position from the collecting position; and a carrier recovering member configured to recover the magnetic carrier particles from the developing member at the collecting position, the carrier recovering member having a magnet to form a magnetic field between the magnet and the developing member for collecting the magnetic carrier particles from the developing member; wherein an outer surface of the developing member includes a plurality of protrusion portions which extend along the outer surface of the developing member in a direction intersecting a toner particle carrying direction of the developing member and are aligned with a regular interval between adjacent protrusion portions, wherein the regular interval is equal to or larger than a particle diameter of a toner particle having an average particle diameter from among the particle diameters of the toner particles and smaller than a carrier particle diameter of a magnetic carrier particle having an average particle diameter from among the particle diameters of the magnetic carrier particles, and wherein the protrusion portions protrude from the outer surface of the developing member with a height that is smaller than the average particle diameter of the toner particles, and wherein the developing member contacts with the image bearing member at a developing portion, and the developing member and the image bearing member rotate so as to have a relative velocity difference at the developing portion.