Printhead nozzle arrangement having variable volume nozzle chamber

1. A printhead having a plurality of nozzle arrangements, each arrangement comprising:

a substrate defining an ink inlet aperture with a wall portion bounding the ink inlet aperture and a crown portion defining a nozzle opening;

a skirt portion depending from the crown portion to form part of a peripheral wall of the nozzle arrangement, the crown and skirt portions being displaceable with respect to the wall portion towards the substrate to alter a volume of a nozzle chamber defined by the wall, crown and skirt portions; and

a thermal actuator interconnecting the crown and skirt portions with the substrate, the actuator for displacing the crown and skirt portions, wherein

the wall portion and skirt portions are configured to define a fluidic seal to inhibit the egress of ink during such displacement,

the substrate further includes a layer of micro-electromechanical drive circuitry for actuating the actuator, and

the actuator has a first active beam arranged above a second passive beam, the beams fabricated from a conductive ceramic material with an electrical connection between the active beam and the drive circuitry established via conductive pads.

2. The printhead of claim 1 , wherein the wall portion bounds the aperture and extends upwardly from the floor portion.

3. The printhead of claim 1 , wherein the skirt portion defines a first part of a peripheral wall of the nozzle chamber and the wall portion defines a second part of the peripheral wall of the nozzle chamber.

4. The printhead of claim 1 , wherein the actuator is connected to an anchor extending upwardly from the substrate, said anchor mounted on the conductive pads to form an electrical connection with the actuator.

5. The printhead of claim 1 , wherein the nozzle opening is arranged at an angle to the vertical so that ejection of ink deviates from the perpendicular.

6. The printhead of claim 1 , further comprising a nozzle guard having a planar cover member positioned on a support structure extending from the substrate, the planar cover member defining a plurality of passages, each passage being in register with a respective nozzle opening.

7. The printhead of claim 6 , wherein the support structure of the nozzle guard defines a number of openings that permit the ingress of air into a region between the printhead and the cover member, whereby air is permitted to pass through the passages.