Patent ID: 7591548

Claim:
An ink cartridge, comprising: a cartridge case enclosing an ink chamber; a path extending from the ink chamber to an exterior of the ink cartridge; a valve member having a first state in which communication between the ink chamber and the exterior of the ink cartridge along the path is permitted and a second state in which communication between the ink chamber and the exterior of the ink cartridge along the path is prevented; an urging member enclosing a portion of the path on an ink chamber-side of the valve member, the urging member being capable of urging the valve member toward the exterior of the cartridge and comprising a hollow portion forming the portion of the path; wherein: the path varies in diameter at different locations along the path; a first diameter of the path in one or more narrow sections is smaller than diameters in all other sections of the path; at least one of the narrow sections of the path has a polygonal cross sectional shape in a plane perpendicular to a direction in which ink flows through the at least one of the narrow sections; the hollow portion has a substantially tapered shape, such that a first diameter at a first end of the hollow portion is greater than a second diameter at a second end of the hollow portion; and the hollow portion has a polygonal cross sectional shape at least at the second end.