Patent ID: 8145100

Claim:
A process cartridge for use in an image forming apparatus, the process cartridge comprising: an image bearing member to bear an image on a surface thereof; and a developing unit to develop the image formed on the image bearing member and integrally incorporated together with the image bearing member in the process cartridge, wherein the developing unit comprises: a developer bearing member used for image developing and to bear developer including toner particles and carrier particles; a casing to form a developer container containing the developer to supply to the developer bearing member; a conveyance screw having a shaft with a spiral screw blade fixedly mounted thereon and which rotates around the shaft to agitate the developer in the casing and convey the developer in an axial direction of the shaft; a toner density sensor to detect a density of the toner particles on a detection surface formed by a part of an inner wall of the casing disposed parallel to the shaft of the conveyance screw; and a detection surface agitating member fixedly mounted on the shaft of the screw at a position facing the detection surface to scrape away the developer accumulated on the detection surface according to a rotation of the screw, the detection surface agitating member including an elastic sheet disposed at a substantially same angle to the axial direction of the shaft of the conveyance screw as the spiral screw blade and elastically deformable to scrape away the developer accumulated on the detection surface.