PURPOSE: To prevent the leakage of ink by making the pressure in an ink tank equal to atmospheric pressure by closing both ends of a pipe element opened at both ends thereof by hydrophobic films and sealing a liquid in the pipe element to constitute a valve unit.
CONSTITUTION: In an ink jet cartridge having such a structure that both ends of a pipe element opened at both ends thereof are closed by hydrophobic films 6 and a liquid 7 is sealed in the pipe element to constitute a valve unit 5 and the ink supply pipe 4 to an ink jet head unit 3 having an ink emitting means is extended to the lower end of an ink tank 1 to generate negative pressure at the time of printing, the valve unit 5 is utilized as an atmosphere communication means. By utilizing the hydrophobia membranes 6 different in air permeability, ink 2 can be held in the ink tank 1 without using a porous element and negative pressure is effectively generated in the ink tank 1 at the time of printing and ink can be stably supplied to an ink emitting orifice.
MASUDA KAZUAKI
KAWAI JUN
SATO YOHEI
OSADA TORACHIKA
HIKUMA MASAHIKO
TANETANI YOICHI
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