To reduce lowering of image quality and deterioration of ejection characteristics by suppressing evaporation of ink from an opening communicating with the atmosphere.
A cover member 105 is fixed to the upper surface 102d of a liquid storage chamber 102 so as to further cover a communication section 102b covering a gas/liquid separating member 104. The length Ln of each passage from the gas/liquid separating member 104 to an opening 106 communicating with the atmosphere and the cross-sectional area Sn of each passage in an ink jet cartridge 100 are set to satisfy a relation K/V<R<2000, assuming the diffusion resistance is R=Σ(Ln/Sn), K=10000 [mg mm/mm2] is a coefficient, and the total weight of liquid to be filled into the liquid storage chamber 102 is V.
UJITA TOSHIHIKO
TANIGUCHI TAKU
Katsuhiro Ito
Ishibashi Masayuki
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