Patent ID: 7525324

Claim:
An inspection method for a piezoelectric element for determining whether or not the piezoelectric element is anomalous, the method comprising at least: first-inspection-signal application step of applying to the piezoelectric element a first inspection signal having a first predetermined voltage waveform, the first predetermined voltage waveform is a voltage waveform composed of a first number of successive basic waveforms each increasing from zero to a predetermined voltage value and then decreasing from the predetermined voltage value to zero; first-characteristic-value measurement step of measuring, as a first characteristic value, an electrical characteristic value of the piezoelectric element after application of the first inspection signal; second-inspection-signal application step of applying to the piezoelectric element a second inspection signal having a second predetermined voltage waveform and an electrical power greater than that of the first inspection signal, the second predetermined voltage waveform is a voltage waveform composed of a second number of the successive basic waveforms or successive second waveforms each including the basic waveform, the second number being larger than the first number; second-characteristic-value measurement step of measuring, as a second characteristic value, the electrical characteristic value of the piezoelectric element after application of the second inspection signal; and anomaly determination step of determining whether or not the piezoelectric element is anomalous on the basis of a value corresponding to the difference between the measured second characteristic value and the measured first characteristic value, wherein the basic waveform is a voltage waveform in which at least one of an increasing time, which is a time required to increase from zero to the predetermined voltage value, and a decreasing time, which is a time required to decrease from the predetermined voltage value to zero, substantially coincides with the resonance period of the piezoelectric element.