Air extraction momentum pump for inkjet printhead

1. An inkjet printhead including a printhead body and an ejector die, the printhead body comprising:

an ink chamber including an ink inlet port and an ink outlet that is fluidically connected to the ejector die;

an air accumulation chamber including a chamber axis, a length dimension along the chamber axis and an end that is proximate an air vent opening;

a mass that is movable along the chamber axis toward and away from the end that is proximate the air vent opening; and

a neck region connecting the ink chamber and the air accumulation chamber, wherein a dimension of the neck region that is parallel to the chamber axis is less than the length dimension of the air accumulation chamber.

2. The inkjet printhead of claim 1 , wherein a dimension of the mass is greater than a dimension of the neck region, thereby constraining the mass from entering the ink chamber.

3. The inkjet printhead of claim 1 , wherein a dimension of the mass along a direction perpendicular to the chamber axis is less than a corresponding dimension of the air accumulation chamber.

4. The inkjet printhead of claim 1 , wherein the air accumulation chamber includes a first wall located proximate the neck region and a second wall that is opposite the first wall, and wherein the air vent opening is disposed in or proximate the second wall.

5. The inkjet printhead of claim 4 , wherein a one-way valve covers the air vent opening.

6. The inkjet printhead of claim 5 , wherein the one-way valve is outside the air accumulation chamber.

7. The inkjet printhead of claim 6 , wherein the one-way valve includes a flapper valve having a free end located proximate the second wall of the air accumulation chamber.

8. The inkjet printhead of claim 1 , further comprising a breather membrane disposed outside the air accumulation chamber.

9. The inkjet printhead of claim 1 , further including a cap assembly comprising:

an inner cap including the air vent opening and a one-way valve covering the air vent opening, wherein the inner cap is affixed at an interface to the air accumulation chamber; and

a breather membrane, wherein the one-way valve is disposed between the breather membrane and the interface between the inner cap and the air accumulation chamber.

10. The inkjet printhead of claim 9 , wherein the cap assembly further comprises an outer cap including a tortuous vent path.

11. The inkjet printhead of claim 1 , wherein the mass includes a circular cross-section in a plane substantially perpendicular to the chamber axis.

12. The inkjet printhead of claim 1 , wherein the mass includes an average density of less than two grams per cubic centimeter.

13. The inkjet printhead of claim 1 , wherein the mass comprises a through hole.

14. The inkjet printhead of claim 13 , wherein the mass includes a face that is substantially perpendicular to the chamber axis, and a one way valve that covers one end of the through hole.

15. The inkjet printhead of claim 1 , wherein the ejector die comprises a nozzle face including an array of nozzles disposed along an array direction, wherein the chamber axis is substantially parallel to the nozzle face and substantially perpendicular to the array direction.

16. The inkjet printhead of claim 1 , the ink chamber being a first ink chamber for containing a first type of ink, the air accumulation chamber being a first air accumulation chamber including a first chamber axis, the mass being a first mass, and the neck region being a first neck region, wherein the printhead body further comprises:

a second ink chamber for a containing a second type of ink, the second ink chamber including an ink inlet port and an ink outlet that is fluidically connected to the ejector die;

a second air accumulation chamber including a second chamber axis, a length dimension along the chamber axis and an end that is proximate an air vent opening;

a second mass that is movable along the second chamber axis toward and away from the end that is proximate the air vent opening; and

a second neck region connecting the second ink chamber and the second air accumulation chamber, wherein a dimension of the second neck region that is parallel to the second chamber axis is less than the length dimension of the second air accumulation chamber.

17. The inkjet printhead of claim 16 , wherein the first chamber axis and the second chamber axis are not collinear.

18. An inkjet printing system comprising:

a carriage that is reciprocatably movable along a carriage scan direction; and

a printhead that is mounted on the carriage, the printhead including an ejector die and a printhead body, wherein the printhead body comprises:

an ink chamber including an ink inlet port and an ink outlet that is fluidically connected to the ejector die;

an air accumulation chamber including a length dimension along the carriage scan direction and an end that is proximate an air vent opening, wherein the air accumulation chamber is located above the ink chamber;

a mass that is movable along the carriage scan direction toward and away from the end that is proximate the air vent opening; and

a neck region connecting the ink chamber and the air accumulation chamber, wherein a dimension of the neck region that is parallel to the chamber axis is less than the length dimension of the air accumulation chamber.

19. The inkjet printing system according to claim 18 , further comprising a replaceable ink tank including an ink outlet port, wherein the ink outlet port of the replaceable ink tank is disposed to mate with the ink inlet port of the ink chamber when the ink tank is mounted on the printhead.

20. The inkjet printing system according to claim 19 , wherein a porous filter is disposed at the ink inlet port of the ink chamber, and wherein an ink path between the air accumulation chamber and the ink outlet of the ink chamber does not include a filter.

21. The inkjet printing system of claim 18 , the ink chamber containing an ink having a density d i grams/cm 3 , wherein the mass has an effective density d m grams/cm 3 , wherein 0.8d i <d m <1.2d i .