Patent ID: 8644736

Claim:
A developing apparatus comprising: a developer container configured to contain a developer including a non-magnetic toner and a magnetic carrier, the developer container including a first chamber configured to contain the developer, a second chamber communicating with the first chamber at both ends of the first chamber to form a circulation path, and a partition wall between the first and second chambers; a developer carrier configured to carry the developer contained in the developer container and convey the developer to a development area opposed to an image carrier, a density sensor configured to detect information on a permeability of the developer in the developer container; and a carrying member, including a rotational shaft provided at a position opposed to the density sensor and a spiral screw formed around the rotational shaft, configured to carry the developer in the developer container, wherein the carrying member includes a first upstream area adjacent to a position opposed to a detection surface of the density sensor on an upstream side in a developer carrying direction and a second upstream area adjacent to the first upstream area on the upstream side in the developer carrying direction, and wherein a stirring force in a rotational direction of the carrying member per unit pitch interval of the screw of the carrying member is smaller in the first upstream area than in the second upstream area so that the carrying member has a higher carrying ability per unit pitch interval in a direction of the rotational shaft in the first upstream area than in the second upstream area.