Patent ID: 8287069

Claim:
A head drive apparatus of a liquid jet apparatus having: a nozzle for jetting liquid drops; an actuator provided in correspondence to the nozzle; and a drive unit that applies a drive signal to the actuator, wherein the drive unit comprises: a drive waveform generator that generates a drive waveform signal being an input for generating the drive signal; a modulator that modulates a pulse of the drive waveform signal generated by the drive waveform generator; a digital power amplifier for amplifying power of a modulated signal subjected to the pulse modulation by the modulator; and a low pass filter for smoothing an amplified digital signal subjected to the power amplification by the digital power amplifier and supplying the signal as the drive signal to the actuator, wherein the modulator comprises a pulse modulation method selection unit that selects a pulse modulation method depending on an input signal level of the drive waveform signal or a type of drive waveform signal, a first pulse modulation method having a constant pulse frequency regardless of the input signal level of the drive waveform signal, and a second pulse modulation method for changing a pulse frequency in accordance with the input signal level of the drive waveform signal, and wherein the pulse modulation method selection unit selects any one of the first pulse modulation method and the second pulse modulation method, by referring to the input signal level of the drive waveform signal.