Abstract: An ink discharging device includes arrayed nozzle holes and corresponding ink flow paths leading thereto. An electrode is provided between the adjacent ink flow paths in such a manner as to be exposed to both of the adjacent ink flow paths so that each electrode works as a common electrode for both of the adjacent ink flow paths. By energizing a conductive ink between the electrodes within the corresponding ink flow path, a portion of the conductive ink is discharged through the corresponding nozzle hole.

Abstract: In an ink-jet printer of the type wherein a current is passed through a conductive ink contained between a pair of electrodes to cause the ink to become vaporized and cause trapped gasses or bubbles to expand suddenly, exerting a sufficient pressure upon the ink to force droplets of ink from a nozzle, a current value flowing between the electrodes is detected to determine the amount of wear of the electrodes, and when the detected current value is lower than a predetermined value, an alarm indicative of the replacement of the currently used ink-jet head is given and, at the same time, ejection of the ink from the nozzle is stopped. Thus, printing operation is always achieved with stable ejection of ink, guaranteeing high printing qualities.