Method of priming a printhead with ink bubbles present in a printhead assembly

1. A method of priming one or more printhead integrated circuits, said method comprising the steps of:

(i) providing a printhead assembly comprising:

an ink distribution manifold having an ink inlet and an ink outlet;

one or more printhead integrated circuits mounted on said manifold, each printhead integrated circuit comprising a plurality of nozzles;

an upstream ink line connected to said ink inlet; and

a downstream ink line connected to said ink outlet, wherein at least part of said printhead assembly contains ink bubbles;

(ii) providing an ink chamber in fluid communication with said ink inlet via said upstream ink line;

(iii) priming said printhead integrated circuits by drawing ink from said ink chamber, through said manifold and into said downstream ink line using a pump;

(iv) bursting ink bubbles in said downstream ink line;

(v) sensing for ink downstream of a bubble-bursting point in said downstream ink line; and

(v) shutting off said pump when said ink is sensed.

2. The method of claim 1 , wherein said printhead is a pagewidth inkjet printhead.

3. The method of claim 1 , wherein said priming is performed by positively pressurizing a headspace above ink in said ink chamber.

4. The method of claim 3 , wherein a pump outlet of said pump communicates with said headspace.

5. The method of claim 4 , wherein a pump inlet communicates with said ink outlet so as to apply negative pressure simultaneously at said ink outlet.

6. The method of claim 1 , wherein a loop in said downstream ink conduit prevents ink from flowing back into said ink chamber when said pump is shut off, said loop passing below a level of ink in said ink chamber.

7. The method of claim 1 , wherein a valve in said downstream ink conduit prevents ink from flowing back into said ink chamber when said pump is shut off.

8. The method of claim 1 , wherein said bubbles are burst by expansion of said bubbles.

9. The method of claim 8 , wherein said bubbles are burst using a bubble-bursting box provided in said downstream ink line, said bubble-bursting box comprising:

a bubble-bursting chamber having a respective chamber inlet defined in a base thereof, said chamber inlet being connected to a downstream ink conduit; and

an air outlet in fluid communication said chamber.

10. The method of claim 9 , wherein an optical sensor is positioned above a bubble-bursting point in said bubble-bursting chamber.

11. The method of claim 9 , wherein said bubble-bursting chamber is dimensioned to promote expansion and bursting of ink bubbles entering said chamber via said chamber inlet.

12. The method of claim 11 , wherein each bubble-bursting chamber has curved sidewalls, wherein a curvature of said sidewalls is greater than a curvature of said downstream ink conduit.

13. The method of claim 12 , wherein each bubble-bursting chamber is generally crescent-shaped, thereby maximizing said curvature in a minimal volume.

14. The method of claim 9 , wherein said bubble-bursting box comprises an air chamber in fluid communication with said bubble-bursting chamber, said air outlet being positioned in said air chamber.

15. The method of claim 14 , wherein each bubble-bursting chamber communicates with said air chamber via a respective air channel defined in a roof of said box.

16. The method of claim 15 , wherein each air channel is a hydrophobic serpentine channel for minimizing transfer of ink to said air chamber when said box is tipped.

17. The method of claim 16 , wherein each air channel comprises at least one ink-trapping stomach.

18. The method of claim 16 , wherein each air channel terminates at a channel outlet defined in a roof of said box, each channel outlet being positioned to deposit ink into said air chamber.

19. The method of claim 18 , wherein said air outlet is defined in a base of said air chamber, and each channel outlet is offset from said air outlet.