Patent ID: 7826775

Claim:
A developing device comprising: a developer carrying body comprising an agent carrying member configured to carry, on its moving surface, a developer comprising toner and magnetic carriers, and a magnetic field generating member comprising plural magnetic poles immovably provided inside the agent carrying member and arranged along a surface movement direction of the agent carrying member, wherein the developer carrying body is configured to convey the developer, along with the movement of the moving surface of the agent carrying member, to a developing position facing a latent image carrier of an image forming apparatus to develop a latent image on the latent image carrier; a supplying member configured to supply the developer to the agent carrying member by conveying the developer in a rotational axial direction of the supplying member; and a regulating member configured to regulate a layer thickness of the developer being carried on a surface region of the agent carrying member after the developer has passed a supplying position where the developer is supplied from the supplying member to the agent carrying member, and before the developer reaches the developing position, while the regulating member is facing said surface region with a predetermined gap therebetween, wherein: the magnetic field generating member further comprises a regulating magnetic pole facing the regulating member via the agent carrying member, and a pump-up magnetic pole disposed adjacent to the regulating magnetic pole on an upstream side of the regulating magnetic pole in the surface movement direction of the agent carrying member, wherein the pump-up magnetic pole is configured to pump up the developer being conveyed by the supplying member to the moving surface of the agent carrying member by attracting this developer with a pump-up magnetic force of the pump-up magnetic pole; and in the magnetic field generating member, the regulating magnetic pole and the pump-up magnetic pole have different polarities from each other, and a maximum pump-up magnetic force position, where the pump-up magnetic force on the moving surface of the agent carrying member is maximum, faces an upstream position with respect to the supplying position.