Ink cartridge and ink jet record apparatus using ink cartridge

An ink cartridge for supplying ink to a record head through an ink supply port wherein space of a container is divided into a plurality of ink storage chambers by a dividing partition wall, the ink storage chambers are connected by a communication hole, and a most upstream one of the ink storage chambers is opened to the atmosphere, the ink cartridge comprising:

• a liquid level sensor comprising a piezoelectric element, which is disposed at an ink level detection position in a downstream one of the ink storage chambers;
• and
• a liquid level sensor accommodation area for accommodating the liquid level sensor therein, the accommodation area being defined by a partition wall that is at least partly inclined with respect to liquid surface of ink, and that forms upper and lower communication gaps,
• wherein the upper gap is narrower than the size of an air bubble occurring in the ink, whereby blocking entry of the bubble into the accommodation area, and
• wherein the upper gap has a size adapted to destroy the bubble when the bubble is squeezed into the accommodation area via the upper gap.

An ink cartridge comprising:

• a container having at least one ink chamber storing ink therein;
• a partition wall disposed in the container, and defining a sensor chamber in a part of the ink chamber, the partition wall further defining an upper gap and a lower gap through which the sensor chamber is in fluid communication with another part of the ink chamber;
• a liquid level sensor comprising a piezoelectric element, which is disposed in the sensor chamber,
• wherein air bubbles accumulate in front of the upper gap and wherein one of the bubbles is enlarged as it is pushed into the accommodation area via the upper gap, and the enlarged bubble is destroyed by the upper gap, the upper gap is in a range of 0.5 mm to 1 mm.