Patent ID: 7744200

Claim:
An inkjet printer comprising: a print head having a plurality of nozzles; a plurality of ink cartridges storing inks of different colors, respectively, to be supplied to said print head; and a pressure applying section for applying pressure in an ejecting direction to the inks in the nozzles of said print head by supplying compressed air to said ink cartridges; wherein said pressure applying section comprises: a pump for supplying compressed air to said ink cartridges through an air channel extending between said ink cartridges and said pump; and a charge tank provided in said air channel, for temporarily keeping the compressed air; and wherein, after increasing pressure in said plurality of ink cartridges, said charge tank, and said air channel simultaneously by the supply of compressed air from said pump, the compressed air is released to said print head and the pressure is applied to the inks in the nozzles of said print head; wherein said pressure applying section further comprises an atmospheric air release valve provided for said charge tank or said air channel, a pressure applying valve provided in an ink channel between said print head and each of said ink cartridge, and a controller for controlling said pump, said atmospheric air release valve, and said pressure applying valve; and wherein said controller performs control so that, after increasing pressure in said ink cartridges, charge tank, and air channel by driving said pump for a certain time, said pressure applying valve is opened to apply the pressure to the inks in the nozzles of said print head, said atmospheric air release valve is opened after elapse of a certain time, and the compressed air in said charge tank is released to atmosphere.