Patent ID: 7647004

Claim:
A developer cartridge, detachably mountable in an image-bearing member cartridge formed with two insertion portions, the developer cartridge comprising: a first developer wall defining a lower surface of the developer cartridge and being provided with: two convex parts protruding downward and that are arranged in a first direction, each of the two convex parts providing a first lowermost area of the developer cartridge; a guide portion located between the two convex parts with respect to the first direction, the guide portion being configured for guiding a recording medium when the recording medium moves between the two convex parts in a second direction perpendicular to the first direction; and a curved surface that protrudes downward and that provides a second lowermost area of the developer cartridge; and a second developer wall exclusively defining an upper surface of the developer cartridge; wherein: when the developer cartridge is put on a flat surface with the first developer wall facing downward, the two first lowermost areas and the second lowermost area contact the flat surface so as to support the developer cartridge; and the two convex parts are insertable into the two insertion portions when the developer cartridge is mounted on the image-bearing member cartridge.