Patent ID: 7290863

Claim:
An ink jet printhead chip that comprises: a substrate that defines a plurality of ink inlet channels; drive circuitry positioned on the substrate; a plurality of nozzle arrangements positioned on the substrate, each nozzle arrangement defining a nozzle chamber in fluid communication with a respective ink inlet channel and a nozzle opening in fluid communication with the nozzle chamber; a plurality of ink ejecting mechanisms connected to the drive circuitry and arranged to eject drops of ink from respective nozzle openings on receipt of suitable signals from the drive circuitry; and a guard positioned on the substrate and spaced from the nozzle arrangements, the guard defining a plurality of passages in alignment with respective nozzle openings, the passages having a length dimension that exceeds a bore size of the respective nozzle openings such that misdirected drops of ink are inhibited from passing through the passages; wherein each nozzle arrangement has a wall portion that extends from the substrate and bounds its associated ink inlet channel and each ink ejecting mechanism includes a movable nozzle structure, the wall portion and the nozzle structure defining the nozzle chamber and the nozzle structure defining the nozzle opening, and an actuator connected to the nozzle structure to displace the nozzle structure with respect to the wall portion so that ink drops are ejected from the nozzle opening.