Patent ID: 7188936

Claim:
A connection unit for an ink jet recording apparatus, adapted to connect an ink cartridge to a recording head, the ink cartridge comprising an ink storing chamber, an atmosphere communicating connection port in fluid communication with the ink storing chamber, and maintaining a closed condition in a first state in which the ink cartridge is not attached to the connection unit, and an ink supplying connection port communicated with the ink storing chamber, and maintaining a closed condition in the first state, the connection unit comprising: an ink reservoir having a height; a negative pressure generating system; an atmosphere communicating connection port located at a first part of the ink reservoir and to be connected to the atmosphere communicating connection port of the ink cartridge; an ink inflow connection port located at a second part of the ink reservoir and to be connected to the ink supplying connection port of the ink cartridge; and an ink flow port for supplying ink from the ink reservoir to the recording head; wherein the connection ports are respectively provided with valve members each of which is normally closed and which opens when the ink cartridge is attached to the connection unit, and wherein the connection unit is configured such that during a printing operation, the ink reservoir communicates with the atmosphere via the atmosphere communicating connection port of the connection unit connected to the atmosphere communicating connection port of the ink cartridge.