Patent ID: 7055921

Claim:
A method for driving a liquid-jet head comprising a passage-forming substrate in which pressure generating chambers communicating with nozzle orifices are formed; and a piezoelectric element provided on one surface of said passage-forming substrate via a vibration plate, said piezoelectric element consisting of a lower electrode, a piezoelectric layer, and an upper electrode, wherein said piezoelectric layer consists of a relaxor ferroelectric, a voltage between a potential V 1 , at which a capacitance of said piezoelectric element is maximal in a capacitance-potential curve of said piezoelectric element, and a potential V 2 , which has a larger absolute value than an absolute value of said potential V 1 and at which an inflection point in said capacitance-potential curve is reached, is set as a drive start potential V 0 , and said piezoelectric element is driven using a drive waveform having an ejection step for changing a potential from said drive start potential V 0 to a potential V 3 , at which a driving electric field having an electric field strength of 100 to 500 kV/cm is generated in said piezoelectric layer, to contract said pressure generating chamber, thereby ejecting liquid droplets through said nozzle orifice.