Cartridge unit incorporating printhead and ink feed system

1. A cartridge unit for an inkjet printer, the cartridge unit comprising:

a printhead having an array of ink ejection nozzles;

a plurality of ink storage compartments, each ink storage compartment having a variable storage volume and a displaceable wall section biased to expand the variable storage volume to generate a sustained negative pressure;

an ink feed system for connecting the ink storage compartment to the printhead, the ink feed system including a plurality of channels extending parallel to a length of the printhead, each channel corresponding respectively to an ink storage compartment; and

a printhead maintenance assembly, the printhead maintenance assembly having a capper spring biased against the array of ink ejection nozzles for covering the array of ink ejection nozzles, wherein,

the printhead maintenance assembly includes a catch element engaged with an actuator, the catch element being movable by the actuator in a direction to counteract the biasing of the capper against the array of ink ejection nozzles,

each ink storage compartment has an interface for receiving a refill unit for refilling the ink storage compartment, the interface having an inlet valve biased to a closed position for receiving ink into a respective ink storage compartment, and an open outlet valve biased to an open position for communicating ink from a respective ink storage compartment to the printhead, and

the cartridge unit further comprises a pair of valve actuator pins provided in the interface of each ink storage compartment, the pair of valve actuator pins adapted to engage with a refill unit received by the interface to substantially simultaneously actuate the inlet valve to an opened position and actuate the outlet valve to a closed position.

2. A cartridge unit according to claim 1 , wherein the printhead assembly is fixed to the cartridge unit for removal and replacement therewith.

3. A cartridge unit according to claim 1 , wherein the printhead assembly is a pagewidth printhead assembly.

4. A cartridge unit according to claim 1 , wherein the ink storage compartment has an interface for releasably engaging with a refill unit for refilling the ink storage compartment, the interface having valves for controlling ink flows into, and out of, the storage compartment.

5. A cartridge unit according to claim 1 , wherein the maintenance assembly is movable between a capped position where the assembly covers the array of nozzles, and an uncapped position spaced from the array of nozzles.

6. A cartridge unit according to claim 1 , wherein an upper surface of the printhead maintenance assembly presents a print media guide facilitating the guiding of print media past the array of ink ejection nozzles.

7. A cartridge unit according to claim 6 , wherein the print media guide is presented when the catch element is moved by the actuator to counteract the biasing of the capper against the array of ink ejection nozzles.