Inkjet printer with float valve pressure regulator

1. An inkjet printer comprising:

an ink reservoir;

a printhead having an ink inlet and an ink outlet;

an upstream ink conduit connected to the ink inlet of said printhead;

a downstream ink conduit connected to the ink outlet of said printhead;

a pressure-regulating chamber including:

an inlet port connected to the ink reservoir via a supply conduit;

an outlet port connected to the upstream ink conduit;

a vent open to atmosphere; and

a float valve for maintaining a set level of ink in said pressure-regulating chamber, said float valve comprising:

an arm pivotally mounted about a pivot;

a float mounted at one end of said arm; and

a valve head connected to said arm for sealing engagement with a valve seat at said inlet port.

2. The printer of claim 1 , wherein said downstream ink conduit comprises a loop section passing below said set level of ink.

3. The printer of claim 2 , further comprising a printhead priming system.

4. The printer of claim 3 comprising:

an air pump communicating with a headspace of said pressure-regulating chamber; and

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

wherein, in a priming configuration, said valve is configured to be shut and said pump is configured to positively pressurize said headspace thereby forcing ink from said chamber through said printhead and into said downstream ink conduit.

5. The printer of claim 4 , wherein a sensor is positioned for sensing ink towards in said downstream ink conduit, said sensor cooperating with said pump such that said pump is shut off when said sensor senses any ink.

6. The printer of claim 5 , wherein said loop section controls an amount of ink flowing from said downstream ink conduit back into said pressure-regulating chamber so as to restore a printing configuration after priming.

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

8. The printer of claim 7 , wherein, in a de-priming configuration, said pump is reversed and ink is pulled from said printhead towards said pressure-regulating chamber.

9. The printer of claim 1 , wherein said printhead is replaceable, said ink inlet being releasably connected to said upstream ink conduit and said ink outlet being releasably connected to said downstream ink conduit.