Abstract: An ink ejection head including a nozzle holding member having an ink ejection nozzle threadably connected to a forward end portion of a liquid chamber structure. The ink ejection heads further includes a sealing member, such as a packing or an O-ring, located inwardly of a threaded connection as viewed from a liquid chamber in the liquid chamber structure. Introduction of dust or grit through the threaded connection into the liquid chamber can be effectively avoided by this arrangement, to thereby prevent obturation of the ink ejection nozzle.

Abstract: An ink-jet printer for forming desired characters on a recording medium by ink droplets is provided. In accordance with the present ink-jet printer, the third harmonic vibration as well as the fundamental harmonic vibration is imparted to the ink inside the ink nozzle so that ink droplets regularly spaced from each other without ink satellites therebetween may be produced. One embodiment of the present invention proposes to provide a vibrator having a resonant frequency three times higher than the exciting frequency. Another embodiment of the present invention proposes to mount the vibrator on the nozzle at a specific location with respect to the mouth of the nozzle.