Patent ID: 7011397

Claim:
An ink cartridge comprising: an ink storage chamber; an ink supply port that is in fluid communication with the ink storage chamber through an ink flow path; and a negative pressure generating mechanism which selectively blocks the ink flow path and opens as a consequance of consumption of ink, the negative pressure generating mechanism including; an ink supply flow path forming member disposed between the ink storage region and the ink supply port, and forming a part of the ink flow path communicatable with the ink supply port; and an elastic member disposed in the ink supply flow path forming member so as to define a communicating portion between a part of the ink supply flow path forming member and a first surface of the elastic member, the communicating portion including an inlet formed in the ink supply flow path forming member through which ink enters into the communicating portion and an outlet formed in the ink supply flow path forming member through which ink leaves the communicating portion, the inlet and outlet both being located on a same side with respect to the elastic member, the first surface receiving a first pressure from the ink storage chamber via the inlet and a second surface receiving a second pressure from the ink supply port via the outlet, so that the first surface of the elastic member contacts with and separates from an opening portion of the ink flow path in response to an applied elastic force, the applied elastic force depending, at least in part, upon a difference between the first pressure and the second pressure; wherein the elastic member is moved to open the opening portion of the ink flow path when the pressure from the ink supply port decreases to not more than a predetermined value, to thereby open the ink flow path and allow the supply of ink to the ink supply port; and wherein the opening portion of the ink flow path serves as the outlet.