| 摘要 |
PURPOSE:To obtain an ink remaining amount detector with high durability and reliability, by suppressing the displacement of a diaphragm and using an electrode hardly forming an oxidized film thereon. CONSTITUTION:When an ink is discharged from a recording head to remain by a small amount, an ink pressure inside an ink supply tube 6 and a pressure detection chamber 14 is reduced to be negative. A diaphragm 13 is pulled down toward the pressure detection chamber 14 against the force of a spring 20, and a conductor 16 is separated from second conductors 21A and 21B. Then, an electrical conduction between the second conductors 21A and 21B is interrupted, whereby that an ink remaining amount has reached the limit is judged. The diaphragm 13 is pulled down under regulation that a projected part 17a of a stopper 17 is abutted against a case wall 11A and determined to extend within 1%. If a diaphragm of fluororesin etc. is used, it never generates fatigue or deterioration. For example, an alloy containing silver and copper is used for either the second conductors 21A and 21B or the conductor 16, and an alloy containing palladium and silver is used for the other one; in this manner, even if a silicon in an ink is turned into gas to leak from the pressure detection chamber 14 to an electrode side, the increase of an electric resistance due to an oxidized film is prevented. |
