Ink supply for printhead ink chambers

1. An inkjet printhead comprising:

a wafer substrate defining a planar support surface;

a plurality of ink chambers adjacent the planar support surface of the wafer substrate, the ink chambers being defined by sidewalls extending between a nozzle plate and the wafer substrate, one of the sidewalls of each chamber having an opening to allow ink to refill the chamber, each ink chamber having a nozzle opening and an actuator for ejecting ink through the nozzle opening upon activation;

an ink conduit between the nozzle plate and the wafer substrate, the ink conduit being in fluid communication with the openings of the plurality of the ink chambers; and

a plurality of ink inlets defined in the wafer substrate, each of the ink conduits receiving ink to supply to the ink chambers from at least one of the ink inlets, each of the ink inlets having an ink permeable trap and a vent sized so that the surface tension of an ink meniscus across the vent prevents ink leakage; wherein during use, the ink permeable trap directs gas bubbles to the vent where the gas bubbles vent to atmosphere.

2. An inkjet printhead according to claim 1 wherein each of the ink conduits is in fluid communication with two of the ink inlets.

3. An inkjet printhead according to claim 1 further comprising at least one priming feature extending through each of the ink inlets; such that,

surface tension of an ink meniscus at the ink inlet acts to draw the ink out of the inlet and partially along the flow path toward the ink chambers.

4. An inkjet printhead according to claim 1 wherein the nozzle openings are arranged in rows such that centres of the nozzle openings are collinear and nozzle pitch along each row is greater than 1000 nozzles per inch.

5. An inkjet printhead according to claim 4 , wherein the nozzle pitch is 1600 nozzles per inch.

6. An inkjet printhead according to claim 1 wherein the nozzle openings are elliptical and the minor axes of each nozzle opening in the row are aligned.

7. An inkjet printhead according to claim 1 wherein each ink chamber has a plurality of nozzle openings, and activation of the actuator ejects ink simultaneously through all the nozzle openings of the ink chamber.

8. An inkjet printhead according to claim 1 further comprising drive circuitry formed on the planar support surface for providing the actuators with electrical pulses for actuation.

9. An inkjet printhead according to claim 8 wherein the drive circuitry has a drive field effect transistor (FET) for each of the actuators, the drive voltage of the drive FET being less than 5 Volts.

10. An inkjet printhead according to claim 9 wherein the drive voltage of the drive FET is 2.5 Volts.

11. An inkjet printhead according to claim 1 wherein the ink chambers have an elongate shape such that two of the sidewalls are long relative to the others, and the opening for allowing ink to refill the chamber is in one of the long sidewalls.

12. An inkjet printhead according to claim 1 further comprising a filter structure at the opening of each ink chamber, the filter structure having rows of obstructions extending transverse to the flow direction through the opening, the obstructions in each row being spaced such that the obstructions are out of registration with the obstructions in an adjacent row with respect to the flow direction.

13. An inkjet printhead according to claim 1 wherein the nozzle plate has an exterior surface with formations for reducing its co-efficient of static friction.