Patent ID: 8454137

Claim:
An ink tank comprising: a reservoir for holding ink, the reservoir including a flexible wall for adjusting an internal volume of the reservoir; a biasing element for applying a force to the flexible wall that tends to increase the internal volume of the reservoir; an ink supply port for delivering ink from the reservoir to a printhead; a breather element, at least a portion of which is disposed inside the reservoir so that a first end is open to air and a second end is in contact with the ink, including a capillary material in contact with the ink in the reservoir, wherein the breather element permits air to enter the reservoir in response to an internal pressure of the reservoir being less than atmospheric pressure outside the ink tank by an amount that is related to a property of the biasing element and a capillary pressure of the breather element; and a housing; wherein the breather element comprises a pipe having the first end that opens to air outside the housing of the ink tank and the second end that is inside the reservoir that holds the ink; and a capillary element affixed to the second end of the pipe.