PURPOSE: To enhance the reliability of an ink storager without causing maloperration of a sensor by a method in which the sensor set portion is formed vertically to the liquid level of ink in such as way as to prevent the staying of ink droplets on the inside of the sensor set position even when the liquid level of ink is lowered.
CONSTITUTION: The first tank with a liquid level sensor is provided with recessions 36 and projections 37 uprisen from the recessions 36. A pair of sensors. e.g., electrode plates 38 facing each other, are set on the outside walls of the projections, and the electrostatic capacity between the electrode plates 38 is detected to measure the height of ink liquid levels or the presence of the ink in the first tank 30. As the sensor, a photo coupler may be used if the discharge portion 37 is made of a transparent material. The projected inner wall 37A, or the partition wall 37A of the sensor 38, is extended downwards from the set position of the sensor 38. No staying of ink droplets in the sensor set position of the projected inner wall 37A takes place, and exact detection of the reduction of ink liquid level can be attained.
TAKAOKA MAKOTO
HITOTSUBASHI HIROO
NAKAMURA TAKU
UZAWA SHIYUNICHI
YOSHIMURA SHIGERU
