Ink cartridge for ink jet printer

An ink tank unit for an ink jet recording apparatus, comprising:

• a container having a first ink accumulating chamber, a second ink accumulating chamber and a third ink accumulating chamber, a partition wall disposed within said container and defining said first ink accumulating chamber and separating said first accumulating chamber from said second ink accumulating chamber, said partition wall having a first ink passage therethrough located at a first position;
• an elastically deformable first valve part mounted within said second ink accumulating chamber and having a second ink passage therethrough located at a second position, said first valve part and said partition wall defining said third ink accumulating chamber, said third ink accumulating chamber being disposed between said first and second ink accumulating chambers, said third ink accumulating chamber in fluid communication with said first ink accumulating chamber through said first ink passage and selectively communicating with said second ink accumulating chamber through said second ink passage;
• and
• a rigid second valve part formed on said partition wall and aligned with said second position;
• and
• a biasing mechanism constructed to urge said first and second valve parts together and permit selective separation of said first and second valve parts.

A negative pressure generating mechanism for selectively communicating a container of an ink tank with a recording head through an ink supply chamber having an ink supply passage in response to pressure changes caused by ejection of ink from said recording head, said negative pressure mechanism, comprising:

• a valve body mounted within said negative pressure generating mechanism;
• an elastically deformable valve seat mounted within said negative pressure generating mechanism and defining a side of said ink supply chamber, said valve seat having a through hole therein;
• and
• a biasing spring positioned to urge said valve body towards said valve seat for selectively maintaining said valve body and said valve seat in contact with said through hole to close said through hole, said valve seat separating from said valve body to open said through hole in response to variations in pressure within said ink supply chamber, said container communicating with said ink supply passage when said through hole is open.

A negative pressure generating mechanism for selectively supplying ink to a recording head through an ink flow passage of a container having a first ink accumulating chamber, a second ink accumulating chamber, and a third ink accumulating chamber, said container having a partition wall disposed within said container and defining said first ink accumulating chamber and separating said first ink accumulating chamber from said second ink accumulating chamber, said partition wall having a first ink passage therethrough located at a first position, said negative pressure generating mechanism, comprising:

• an elastically deformable first valve part mounted within said second ink accumulating chamber and having a second ink passage therethrough, said first valve part and said partition wall defining said third ink accumulating chamber, said third ink accumulating chamber being disposed between said first and second ink accumulating chambers, said third ink accumulating chamber in fluid communication with said first ink accumulating chamber through said first ink passage and selectively communicating with said second ink accumulating chamber through said second ink passage;
• and
• a rigid second valve part formed on said partition wall and aligned with said first valve part and
• a biasing mechanism constructed to urge said first and second valve parts together and permit selective separation of said first and second valve parts.