Patent ID: 9454103
Filing Date: 2016-09-27
CPC Classification: G03G

Claim Text:
1. A developing device configured to develop an electrostatic image formed on an image bearing member by using 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 being disposed rotatably to contact with the image bearing member at the developing position and bearing the developer from a supplied position where developer is supplied to a collected position where magnetic carrier particles are collected and bearing toner particles from the collected position to the developing position; and a carrier collecting member configured to collect the magnetic carrier particles from the developing member at the collected position, the carrier collecting 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 the rotational 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 each protrusion portion has a first face formed at one side in a circumferential direction of the developing member of an apex of each protrusion portion and a second face formed at the other side in the circumferential direction of the developing member of the apex of each protrusion portion, and an inclination angle of the first face is less than an inclination angle of the second face, and wherein in the circumferential direction of the developing member, when a downward direction of the first face is set to be positive, a relative velocity of a surface velocity of the developing member to a surface velocity of the image bearing member is set to be positive at the developing position.