Patent ID: 8162453

Claim:
An inkjet recording apparatus comprising: print heads each of which has ejection ports through which ink is ejected; main tanks each of which stores the ink; ink supply channels which respectively connect the main tanks with the print heads; subsidiary tanks which are arranged in the ink supply channels and each of which includes an external case and an ink accommodating member that is flexible and arranged in the external case, the ink being supplied from the main tanks to the print heads through the ink supply channels and the ink accommodating members in the subsidiary tanks; a pressure buffer which is connected to spaces in the subsidiary tanks between the external cases and the ink accommodating members; a common pressure reducing pump which reduces a pressure Pb inside the pressure buffer and is shared by the subsidiary tanks; differential pressure valves which are respectively attached to the subsidiary tanks so as to connect the spaces in the subsidiary tanks with an atmosphere such that each of pressures Ps inside the spaces in the subsidiary tanks is set to a uniform pressure; a first pressure gage which measures the pressure Pb inside the pressure buffer; and a second pressure gage which measures the pressures Ps inside the spaces in the subsidiary tanks, wherein an operation of the common pressure reducing pump to reduce the pressure Pb inside the pressure buffer is performed and the differential pressure valves adjust the pressures Ps inside the spaces in the subsidiary tanks so that each of the pressures Ps inside the spaces in the subsidiary tanks is set to the uniform pressure, the pressure Pb inside the pressure buffer and each of the pressures Ps inside the spaces in the subsidiary tanks have a relationship of Pb<Ps, and each of back pressures of the print heads is thereby set to a uniform back pressure, at least while the ink is being ejected from the print heads.