Priming system for pagewidth print cartridge

1. An ink priming system for a cartridge unit having a pagewidth printhead assembly in fluid communication with one or more ink storage compartments, the system comprising:

a priming inlet provided on the pagewidth printhead assembly, the priming inlet including a valve incorporating an elastomeric seal;

an ink flow passage providing fluid connection between the pagewidth printhead assembly and each of the ink storage compartments, the ink flow passage terminating at each of the ink storage compartments to form an ink outlet;

an ink filter provided across the ink outlet;

a vent hole defined through a surface of each ink storage compartment, the vent hole being defined through a surface opposite the ink outlet; and

an ink retaining member provided within each ink storage compartment for receiving and storing ink, the ink retaining member being interposed between the ink outlet and the vent hole, wherein

ink is supplied to the priming inlet of the pagewidth printhead assembly to flow from the pagewidth printhead assembly into the ink storage compartment via the ink flow passage and across the ink filter, and

the ink received via the ink flow passage primes both the printhead assembly and the ink retaining member of each ink storage compartment with ink substantially simultaneously the amount of priming ink being controlled so that the ink retaining member is not completely saturated and remains dry nearest the vent hole.

2. The ink priming system according to claim 1 , wherein ink is drawn into the ink retaining member with assistance from a capillary force facilitated by the vent hole.

3. The ink priming system according to claim 1 , wherein the ink retaining member is a porous body adapted to absorb the ink supplied to the ink storage compartment through capillary action.

4. The ink priming system according to claim 3 , wherein the ink retaining member is a foam material.

5. The ink priming system according to claim 1 , wherein the ink filter is a mesh material.

6. The ink priming system according to claim 1 , wherein the ink filter restricts air bubbles formed in the ink from passing therethrough.

7. The ink priming system according to claim 1 , wherein the ink filter is placed on a raised portion located adjacent the ink outlet, thereby providing a gap between the ink outlet and the ink filter.

8. The ink priming system according to claim 5 , wherein each ink retaining member is supported upon the ink filter within the ink storage compartment.

9. The ink priming system according to claim 1 , wherein each ink retaining member includes an absorbent layer including a plurality of channels forming a micro-capillary array, and an ink trapping layer provided between the ink flow passage and the absorbent layer, the absorbent layer for absorbing the supplied ink in multiple directions.

10. The ink priming system according to claim 9 , wherein walls of the channels are rigid.

11. The ink priming system according to claim 9 , wherein the ink trapping layer is made of one of: foam; and sponge.

12. The ink priming system according to claim 1 , wherein the pagewidth printhead assembly comprises one or more ink delivery channels arranged along its length and ink supplied to said priming inlet passes into one of the channels.

13. The ink priming system according to claim 12 , wherein the pagewidth printhead assembly has a plurality of groups of nozzles provided thereon, each group of nozzle is in fluid communication with one of the ink delivery channels to receive ink therefrom for priming said nozzles.

14. An ink priming system according to claim 1 , wherein the vent hole exposes the ink retaining member to atmospheric pressure, whereby generation of the capillary force is assisted.

15. An ink priming system according to claim 1 , wherein the vent hole assists in keeping a surface of the ink retaining member nearest thereto dry relative to a surface of the ink retaining member in the vicinity of the entry point, whereby generation of the capillary force is assisted.

16. An ink priming system according to claim 1 , further comprising a bypass fluid path connected at one end to the ink storage compartment, and connected at another end at the ink flow passage, wherein the bypass fluid path provides an additional fluid path for priming ink into the ink storage compartment, and bypasses the ink filter.