Patent ID: 7073892

Claim:
A printhead chip which comprises a substrate that defines ink supply conduits; drive circuitry positioned on the substrate; nozzle chamber assemblies positioned on the substrate, each nozzle chamber assembly defining a nozzle chamber in fluid communication with a respective ink supply conduit and having an upper portion that defines an ink ejection port in fluid communication with the nozzle chamber and a lower portion that extends from the substrate, the upper portion being reciprocally displaceable with respect to the lower portion so that ink is ejected from the ink ejection port; and actuators connected to the drive circuitry and to respective said upper portions to displace said upper portions to eject ink, wherein nozzle-clearing structures are mounted on the substrate in respective nozzle chambers, the nozzle-clearing structures being dimensioned to project through respective ink ejection ports at some stage during displacement of respective upper portions to clear any blockages in the ink ejection ports.