| 摘要 |
PROBLEM TO BE SOLVED: To properly detect the consumption state of the ink in an ink cartridge over a plurality of stages. SOLUTION: A plurality of sensors 41-44 are arranged to an ink cartridge. These liquid sensors 41-44 are piezolectric devices converting vibration energy to an electric signal and form detection signals showing ink consumption states. The liquid sensors 41-44 are arranged on the cartridge at different positions to detect liquid consumption states of a plurality of stages. Preferably, the liquid sensors are arranged along the direction wherein a liquid surface moves accompanied by the consumption of a liquid. The intervals between the sensors are set so as to be different along the liquid surface moving direction. |
