Ink refill unit having printer ink storage actuators

1. An ink refill unit for replenishing an ink storage compartment of an inkjet printer, the ink refill unit comprising:

a body containing a quantity of refilling ink configured to engage an interface of the storage compartment; and

a plurality of actuators defined in the body for actuating a constrictor mechanism of the storage compartment as the ink refill unit engages the interface and deactivating the constrictor mechanism as the ink refill unit disengages the interface, the constrictor mechanism for constricting a flexible tubular wall of the storage compartment by a predetermined amount.

2. An ink refill unit according to claim 1 wherein the actuators are positioned in the body such that they are at the corners of a regular sided geometric shape.

3. An ink refill unit according to claim 2 wherein the actuators are generally flat pegs extending from the body such that the plane of each peg crosses the corresponding diagonal of said shape at right angles.

4. An ink refill unit according to claim 3 wherein the pegs are slightly arcuate with their respective centres of curvature proximate the centre of said shape.

5. An ink refill unit according to claim 4 wherein each of the pegs have a buttress reinforcement extending along the corresponding diagonal and towards the centre of said shape.

6. An ink refill unit according to claim 1 , comprising:

engagement formations on the body for releasably engaging the interface of the storage compartment; and

an inlet valve actuator for opening an inlet valve of the interface as the refill unit engages the interface so that the ink in the body is in fluid communication with the storage compartment.

7. An ink refill unit according to claim 1 , wherein:

the storage compartment is negatively pressurized and supplies ink to a printhead assembly;

the interface has a normally closed inlet valve and a normally open outlet valve, both in fluid communication with the storage compartment; and

the refill unit has valve actuator formations on the body, wherein during use, the body releasably engages the interface to actuate the inlet and the outlet valves so the storage compartment fills with ink from the body because of the negative pressure in the storage compartment.

8. An ink refill unit according to claim 1 , wherein:

the storage compartment is negatively pressurized ink storage and supplies ink to a printhead assembly via a normally open outlet valve; and

the refill unit has engagement formations for releasably engaging the storage compartment and an outlet valve actuator for closing the outlet valve as the refill unit engages the storage compartment.

9. An ink refill unit according to claim 1 , wherein:

the storage compartment supplies a printhead assembly with an array of nozzles, wherein during use, the storage compartment is maintained at a negative pressure to avoid inadvertent ink leakage from the nozzles;

the refill unit has an ink outlet and a repressurizing arrangement in the body;

upon engagement of the refill unit with the storage compartment, the repressurizing arrangement causes part of the unit to be inwardly depressed as the ink from the body is drawn into the storage compartment through the ink outlet by the negative pressure until pressure equalization; and

upon subsequent disengagement of the refill unit from the storage compartment, the repressurizing arrangement releases the inwardly depressed part of the storage compartment to re-establish the negative pressure.

10. An ink refill unit according to claim 1 , wherein:

the interface releasably engages with the refill unit and has valves for controlling ink flows into, and out of, the storage compartment; and

the refill unit has an ink outlet and valve actuators on the body for actuating the valves when the refill unit engages the interface, such that the valve actuators actuate the valves in a predetermined sequence.

11. An ink refill unit according to claim 1 , wherein:

the storage compartment forms part of the inkjet printer which has a printhead, control circuitry and the interface for releasably engaging the refill unit;

the refill unit has an ink outlet and a memory circuit for storing information relating to at least one characteristic of the refilling ink; and

during use, the memory circuit allows to the control circuit to interrogate it to verify that the ink in the refill unit is suitable for the printer.

12. An ink refill unit according to claim 1 , further comprising:

an ink outlet for engaging a complementary ink inlet of the interface; and

a spigot extending from the body for insertion in an aperture in the interface,

wherein the lateral cross section of the spigot is keyed to the shape defined by the aperture to ensure the ink refill unit is correctly matched to the storage compartment.

13. An ink refill unit according to claim 1 , further comprising:

an ink outlet for engaging a complementary ink inlet of the storage compartment; and

a visual indicator to provide a visual indication when a predetermined quantity of the refilling ink has flowed from the refill unit into the storage compartment.