Patent ID: 7549738

Claim:
A refill unit for a printer cartridge having an operatively, negatively pressurized ink reservoir, the refill unit comprising: a docking assembly for docking with the printer cartridge; an ink bag for storing ink housed in the docking assembly; a valve actuator shaped and configured to actuate an outlet valve of the ink reservoir into a closed position and thereafter to actuate an inlet valve of the ink reservoir into an open position when the docking assembly docks with the cartridge; an ink delivery outlet assembly arranged on the docking assembly in fluid communication with the ink bag and having a seal configured to allow ink to flow from the ink bag to the ink reservoir only when the refill unit engages the cartridge; and constrictor actuators engageable with the cartridge and configured to increase pressure in the ink bag during ink flow from the ink bag to the ink reservoir, and to permit a re-establishment of negative pressure in the ink reservoir upon disengagement from the cartridge.