Patent ID: 7744182

Claim:
A capacitive load driving circuit supplying driving voltage to a capacitive load, the circuit comprising: a driving voltage waveform generating unit which, at times of charging or discharging of the capacitive load, generates a driving voltage waveform in which potential applied to the capacitive load varies stepwise from a first potential to a second potential during a predetermined time period; wherein the driving voltage waveform generating unit has a plurality of power sources providing a plurality of potentials from the first potential to the second potential, and a plurality of switching elements switching supply to the capacitive load of the potentials provided by the plurality of power sources, the plurality of switching elements carrying out switching operation such that the potential applied to the capacitive load varies stepwise from the first potential to the second potential, wherein one end of the capacitive load is connected to a reference potential and the other end of the capacitive load is connected to the plurality of power sources providing different potentials respectively via the plurality of switching elements, and wherein the plurality of power sources includes a first power source that provides the first potential with respect to the reference potential, a second power source that provides the second potential with respect to the reference potential, and at least a third power source that provides an intermediate potential between the first potential and the second potential with respect to the reference potential, and the plurality of power sources are constant power sources that provide constant potentials, wherein a driving voltage waveform in which potential applied to the capacitive load varies stepwise at least three steps during charging and during discharging, and the differences in potentials for each adjacent steps are even.