Patent ID: 7722170

Claim:
An ink pressure regulator for regulating a hydrostatic pressure of ink supplied to an inkjet printhead, said regulator comprising: an ink chamber having an ink outlet for fluid communication with the printhead via an ink line; an air inlet open to atmosphere; a bubble outlet positioned in a headspace of the ink chamber at all operative ink levels, said bubble outlet being positioned for bubbling air bubbles directly into said headspace at all operative ink levels, each air bubble comprising an air cavity trapped inside a film of ink; a capillary channel in fluid communication with ink contained in the ink chamber, said capillary channel supplying ink from the chamber to the bubble outlet by capillary action; and an air channel connecting the air inlet and the bubble outlet, wherein said bubble outlet is dimensioned to control a Laplace pressure of air bubbles drawn into said chamber as result of supplying ink to the printhead, thereby regulating a hydrostatic pressure of the ink.