Patent ID: 7237884

Claim:
An ink cartridge, comprising: a first at least one wall; an ink chamber capable of storing ink, the ink chamber being bounded, at least in part, by the first at least one wall; an ink supply opening configured to permit communication between the ink chamber and an area outside of the ink chamber; and a detection portion; wherein: the detection portion extends away from the ink chamber relative to portions of the ink cartridge adjacent to the detection portion, at least when the ink cartridge is installed in an image forming apparatus; at least one part of the detection portion is capable of obstructing a light beam directed through the detection portion in a direction perpendicular to a direction that the detection portion extends away from the ink channel; and the at least one part of the detection portion has a fixed location on the ink cartridge, regardless of an amount of ink in the ink cartridge, at least when the ink cartridge is installed in the image forming apparatus and in operation.