Patent ID: 7643771

Claim:
A developer cartridge comprising: a casing that accommodates developer and is formed with an opening for communicating inside of the casing with outside thereof; a developing roller that is disposed on the opening and is rotatably supported on the casing; a sheet member that is disposed between the casing and the developing roller; a plurality of seal members that is attached to the sheet member in order to prevent the developer from leaking through the opening; and a thickness-regulating member that has a first part attached to the casing and a second part that regulates thickness of the developer provided on the developing roller, wherein the developing roller has a rotational shaft defining an axial direction and a peripheral surface, the peripheral surface including a center zone and end zones at both end portions in the axial direction; the casing has opposing surfaces opposed to the end zones; the sheet member comprises two first sheet portions and a second sheet portion integrally provided with the first sheet portions, each of the first sheet portions being disposed between each of the end zones and each of the opposing surfaces, the second sheet portion being disposed between the casing and the first part; and the plurality of seal members comprises two first seal members and a second seal member, each of the first seal members being attached to each of the first sheet portions in order to prevent developer from leaking through a space formed between each of the end zones and each of the opposing surfaces, the second seal member being attached to the second sheet portion in order to prevent the developer from leaking through a space formed between the casing and the first part.