| 摘要 |
PURPOSE:To achieve lont-time stable ejection of an ink, by specifying the ratio of an applied voltage to the interval between adjacent electrodes, loading an ink limited in variation of an electric current after application of the voltage, and applying a potential difference between a control electrode and a common electrode while causing air to flow out from an air ejecting port, thereby jetting the ink. CONSTITUTION:An oil base ink having a viscosity of 2-10 cP, a resistivity of 1X106-1X10<8> OMEGA.cm, a surface tension of 20-40 dyn/cm and a specific gravity of not more than 1.3 is filled into an ink chamber 7 of an ink jet head. The interval of control electrodes 4 is not more than 1 mm, air is introduced through an air inlet port 6, and is permitted to flow out through each air-ejecting port 1, whereas a potential difference is applied between the control electrodes 4 and a common electrode 3, whereby a meniscus of the ink is extended in the direction of the air-ejecting port, and an ink droplet is ejected through the port 1 together with an air flow. Gold, platinum, rhodium or the like is vapor-deposited as electrodes so that the ratio of an applied voltage to the interval of the electrodes will be at least 100 V/mm. with the ink loaded on a cell having an electrode area of 0.2pi0.15 mm<2>, variations of an electric current with time under application of a voltage in the range of 100-500 V are measured, and the current value after 10-min voltage application is compared with an initial current value. When the variations in the current value are within 30%, a favorable result is obtained, and recording is stabilized. |
