Patent ID: 7703901

Claim:
A printhead ink supply system comprising: (a) an inkjet printhead; (b) an ink reservoir; (c) an ink pressure regulator for regulating a hydrostatic pressure of ink supplied to said printhead, said regulator comprising: an ink chamber having an ink outlet; an air inlet open to atmosphere; an air channel connected to the air inlet, said air channel having a constriction defining a bubble outlet, said bubble outlet being configured as a slot having a length dimension which is longer than a width dimension, said bubble outlet being positioned for bubbling air bubbles into the chamber, each air bubble comprising an air cavity trapped inside a film or a body of ink; and (d) a first ink line providing fluid communication between said ink outlet and an inlet channel of said printhead, wherein said width dimension of said slot is dimensioned to control a Laplace pressure of air bubbles drawn into said ink as result of supplying ink to the printhead, thereby regulating a hydrostatic pressure of the ink.