Printhead priming system with feedback control of priming pump

1. A priming system for priming an inkjet printhead having an ink inlet, an ink outlet and a plurality of nozzles, said priming system comprising:

pressure-regulating ink chamber having an inlet port and an outlet port connected to said ink inlet via an upstream ink line;

an ink reservoir in fluid communication with said inlet port, said ink reservoir being positioned above a level of ink in said chamber;

a valve positioned between said ink reservoir and said inlet port,

an air pump having a pump outlet communicating with a headspace above said ink in said ink chamber;

a sensor positioned for sensing ink in a downstream ink line connected to said ink outlet, said sensor cooperating with said pump such that said pump is shut off when said sensor senses any ink; and

means for minimizing phantom sensing of ink caused by ink bubbles in said downstream ink line,

wherein, in a priming configuration, said valve is configured to be shut and said pump is configured to positively pressurize said headspace until said sensor senses ink.

2. The priming system of claim 1 , wherein said pump is reversible for effecting de-priming operations.

3. The priming system of claim 2 , wherein, in a de-priming configuration, said pump is reversed and ink is pulled from said printhead towards said ink chamber.

4. The priming system of claim 1 , wherein said ink outlet is in fluid communication with a pump inlet, thereby enabling both pushing and pulling of ink during a priming and/or a de-priming operation.

5. The priming system of claim 1 , further comprising means for controlling, after priming, an amount of ink flowing from said downstream ink line back into said pressure-regulating chamber.

6. The priming system of claim 5 , wherein said means is selected from the group comprising:

an electronically-controlled valve;

a check-valve; and

a loop section passing below a level of ink in said chamber.

7. The priming system of claim 1 , wherein said sensor comprises an optical sensor.

8. The priming system of claim 1 , wherein said means for minimizing phantom sensing of ink comprises a bubble-bursting box, said box comprising:

one or more bubble-bursting chambers having a respective chamber inlet; and

an air outlet.

9. The priming system of claim 8 , wherein said sensor is positioned to sense ink above a bubble-bursting point in at least one of said bubble-bursting chambers.

10. The priming system of claim 9 , wherein said at least one bubble-bursting chamber is transparent.

11. The priming system of claim 8 , wherein said air outlet is:

open to atmosphere; or

in fluid communication with a pump inlet of said pump, thereby enabling both pushing and pulling of ink through said printhead during a priming or a de-priming operation.

12. The priming system of claim 8 , wherein said bubble-bursting box comprises a plurality of bubble-bursting chambers, each chamber corresponding to a respective ink channel of said ink supply system.

13. The priming system of claim 8 , wherein each bubble-bursting chamber is dimensioned to promote expansion and bursting of ink bubbles entering said chamber via said chamber inlet.

14. The priming system of claim 13 , wherein each bubble-bursting chamber has curved sidewalls, wherein a curvature of said sidewalls is greater than a curvature of said conduit.

15. The priming system of claim 14 , wherein each bubble-bursting chamber is generally crescent-shaped, thereby maximizing said curvature in a minimal volume.

16. The priming system of claim 15 , wherein said bubble-bursting box comprises an air chamber in fluid communication with said bubble-bursting chambers via an air channel defined in a roof of said box, said air outlet being defined in said air chamber.

17. The priming system of claim 16 , wherein said air channel is a hydrophobic serpentine channel comprising at least one ink-trapping stomach, said air channel minimizing transfer of ink to said air chamber when said box is tipped.

18. The priming system of claim 1 , wherein said printhead is replaceable.

19. The priming system of claim 18 , wherein said printhead comprises one or more printhead integrated circuits mounted on an ink distribution manifold, each printhead integrated circuit comprising a plurality of nozzles, and said manifold having said ink inlet and said ink outlet.