Patent ID: 8471436

Claim:
A piezoelectric element drive circuit for outputting a signal that drives a piezoelectric element, the drive circuit comprising: a frequency signal generation unit that outputs a frequency signal whose frequency is altered discretely; a voltage-controlled oscillator that alters the frequency of an output signal based on an inputted voltage; a phase comparator that compares the phase of the output signal from the frequency signal generation unit and the phase of the output signal of the voltage-controlled oscillator; a resistance that is connected between the voltage-controlled oscillator and the phase comparator; and a capacitor that is connected between the end of the resistance that is not connected to the phase comparator and a ground portion of the circuit, wherein degree of alteration of the frequency signal is determined in accordance with a time constant based on values from the resistance and the capacitor, wherein the output signal of the voltage-controlled oscillator is input into the phase comparator directly, wherein the voltage-controlled oscillator outputs a frequency signal whose frequency is altered continuously, and wherein the output signal of the voltage-controlled oscillator is the signal that is directly utilized for a driving frequency signal of the piezoelectric element.