Method of depriming a printhead with concomitant isolation of ink supply chamber

1. A method of depriming a printhead, said method comprising the steps of:

(i) providing a printhead having a plurality of nozzles for ejection of ink, an ink inlet and an ink outlet;

(ii) providing an ink chamber having an outlet port connected to said ink inlet via an upstream ink line, said ink chamber having an inlet port controlled by a float valve positioned in said ink chamber;

(iii) depriming said printhead by pumping ink from a downstream ink line connected to said ink outlet, through said printhead and into said ink chamber; and

(iv) closing said float valve when a level of ink in said chamber reaches a predetermined first level, thereby isolating said ink chamber from an ink reservoir in fluid communication with said inlet port,

wherein said float valve comprises:

an arm pivotally mounted about a pivot;

a float mounted at one end of said arm; and

a valve stem attached to said arm, said valve stem having a valve head for closure of a valve seat when the float reaches said predetermined first level, wherein said valve seat is partitioned at the inlet port of said chamber.

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

3. The method of claim 1 , wherein said chamber comprises an air vent open to atmosphere, said air vent communicating with a headspace above said ink.

4. The method of claim 1 , wherein said pumping is by means of an inline ink pump.

5. The method of claim 4 , wherein said ink pump is positioned in said downstream ink line.

6. The method of claim 4 , wherein said ink pump is a peristaltic pump.

7. The method of claim 4 , wherein said pump is reversible.

8. The method of claim 1 , wherein said chamber comprises a return port connected to said downstream ink line, and a snorkel extending from said return port to above the ink in said chamber.

9. The method of claim 4 , wherein said downstream ink line comprises inline filters positioned on either side of said pump.

10. The method of claim 1 , wherein said ink chamber functions as a pressure-regulating chamber during normal printing, said chamber controlling a hydrostatic pressure of ink supplied to said printhead.

11. The method of claim 1 , wherein said valve is configured to be closed for at least the duration of said depriming.

12. The method of claim 1 , further comprising the steps of:

(v) removing said deprimed printhead; and

(vi) replacing said deprimed printhead with a replacement printhead.

13. The method of claim 12 , further comprising the step of:

(vii) priming said replacement printhead by pumping ink from said ink chamber, through said printhead and into said downstream ink line.