Method of driving ink-jet head

Abstract

In a method for driving an ink jet head in which at least a portion of a wall surface of an ink chamber is deformed by a piezoelectric actuator to eject ink, the voltage applied to the piezoelectric actuator is lowered from a voltage value in an initial condition, thereby causing the volume of the ink chamber to increase and thus causing ink to be drawn into the ink chamber, and then the applied voltage is rapidly raised up to a prescribed voltage value higher than the initial condition voltage value, thereby causing the volume of the ink chamber to decrease and thus causing ink to be ejected from the ink chamber. Next, after holding the prescribed voltage value for a prescribed length of time, the applied voltage is caused to drop from the prescribed voltage value down to the initial condition voltage value, thereby causing the volume of the ink chamber to increase. The time over which the applied voltage is dropped is set equal to one half the cycle of meniscus surface tension oscillations caused by the ink ejection, and the voltage drop value is set at such a value at to generate, in the ink chamber, oscillations corresponding to the amplitude of the meniscus surface tension oscillations.