Patent ID: 8649705

Claim:
A developing apparatus for use in an electrophotographic image forming apparatus, comprising: a plurality of developing units configured to form corresponding developer images; a frame configured to hold the plurality of developing units therein in position, the developing units being movable independently by a distance relative to the frame; and an elastic sealing member secured to the frame and disposed between a side plate of each developing unit and the frame to seal a gap between the side plate and the frame after the developing unit has been attached to the frame, wherein when the developing unit moves over the distance relative to the frame, the elastic sealing member is deformable so that a surface of the elastic sealing member in contact with the side plate follows movement of the developing unit without slipping; wherein each of the developing units includes a first transporting path configured to transport developer, and the frame includes a second transporting path configured to communicate with the first transporting path and to transport the developer further when a corresponding developing unit has been attached to the frame; the elastic sealing member seals a gap between the first transporting path and the second transporting path when the corresponding developing unit is attached to the frame; and the sealing member is compressed so that the sealing member, the gap, and the distance are related by T≧L 1 +L 2 , where T is the thickness of the sealing member when it is not compressed, L 1 is the distance, and L 2 is the gap.