PURPOSE: To stably granulate ink without lowering a frequency characteristic, by preventing the infiltration of bubbles from a nozzle by granulating the ink in the order of suction, injection and return.
CONSTITUTION: Drive pulses with negative-pole properties are applied to a piezo- electric element 6, ink is sucked into a pressure chamber 1 by curving an ekectric, machanical converting means 8 to the side reverse to the pressure chamber 1 at the rise portion and the means 8 is returned to a stationary condition by injecting ink from a nozzle 5 at the fall portion. Since the ink is sucked to the pressure chamber 1 side when the surface of the nozzle is under a stable condition, an equilibrium condition due to the surface tension of the surface is difficult to be broken, and the surface strongly resists the infiltration of bubbles. Thus, ink can stably be granulated without reducing a frequency characteristic because the penetration of the bubbles can be prevented even if the rise and fall of drive pulses applied to the piezo-electric element 6 are made steep.
YOSHIKAWA SHIGERU
MATSUDA TADASHI
