Patent ID: 7761028

Claim:
A developing apparatus for an image forming apparatus comprising: a developing roller for carrying a magnetic developer; a developing device frame, having an opening for exposing a part of said developing roller, for rotatably supporting said developing roller; a magnetic sealing member, mounted to said developing device frame at a longitudinal end portion, for sealing a gap between said developing device frame and said developing roller against leakage of the magnetic developer, wherein said magnetic sealing member includes an arcuate surface which has a magnetic property and which is opposed to an outer surface of said developing roller with a gap therebetween and a projected surface which has a magnetic property and which is projected from an upstream end of said arcuate surface toward upstream with respect to a peripheral moving direction of said developing roller and which is more remote from an outer surface of said developing roller than said arcuate surface; and a sheet for preventing the magnetic developer from leaking through between said developing device frame and said developing roller, said sheet being mounted to an upstream end of said developing device frame with respect to the moving direction and contacted to said developing roller so as to cover at least a part of said projected surface.