Liquid supply system, fluid communicating structure, ink supply system, and inkjet recording head utilizing the fluid communicating structure

An ink tank comprising:

• an ink containing portion attachable to and detachable from a liquid chamber having a recording head for ejecting an ink,
• wherein the ink containing portion being attachable to and detachable from the liquid chamber via plural communication channels,
• wherein the liquid chamber forms a substantial closed space except said plural communication channels and said recording head in a state wherein said ink containing portion is attached to the liquid chamber,
• wherein the ink containing portion includes a movable section which forms at least a partial portion of the ink containing portion and which is displacable or deformable to change an internal volume of said ink containing portion, and urging means for urging the movable section in a direction for increasing the internal volume to thereby place the inside of the liquid chamber into a negative pressure state relative to an atmosphere pressure, and
• wherein said ink containing portion has means for introducing atmosphere directly into the ink containing portion in order to adjust the negative pressure state.