Ink cartridge and ink jet printer

An ink jet printer, comprising:

• a print head;
• and
• an ink cartridge that supplies ink to the print head, comprising,
• a casing body including a first chamber allowing atmospheric air to enter therein, and a second chamber storing ink therein,
• a lid member, disposed within the second chamber movably in a vertical direction, the lid member partitioning the second chamber into a first space above the lid member and a second space below the lid member for storing ink, wherein a gap is formed between an outer periphery of the lid member and an inner periphery of the second chamber such that a meniscus of ink is formed therebetween,
• a partition member that partitions the first chamber from the second chamber, the partition member provided at an upper end of the second chamber, and having a through hole formed at a portion which is away from the inner periphery of the second chamber, the through hole allowing the atmospheric air to enter the second chamber, and
• an elastic member disposed in the second chamber, to urge the lid member upward, and maintain the second space of the second chamber at a negative pressure,
• wherein the ink cartridge supplies the ink from the second chamber to the print head.