Piezoelectric head inspection device and droplet jetting device

An inspection device for a piezoelectric head that includes

• a pressure chamber filled with liquid,
• a liquid supply channel that supplies the liquid to the pressure chamber,
• a nozzle at which droplets are jetted from the pressure chamber, and
• a piezoelectric element that applies pressure to the pressure chamber,
• the inspection device comprising:
• a detection component comprising:
• a bridge circuit including
• the piezoelectric element,
• a switching element connected in series with the piezoelectric element,
• a first resistor connected in series with the piezoelectric element and the switching element,
• a capacitor with an electrostatic capacitance corresponding to a damping capacitance of the piezoelectric element,
• a second resistor corresponding to an on-resistance of the switching element and connected in series with the capacitor, and
• a third resistor, connected in series with the capacitor and the second resistor, with a value the same as the first resistor,
• the piezoelectric element, the switching element and the first resistor being connected in parallel with the capacitor, the second resistor and the third resistor;
• and
• a differential amplifier that amplifies a differential voltage of the bridge circuit between a voltage between the piezoelectric element and the first resistor and a voltage between the capacitor and the third resistor,
• wherein, when voltage is applied to the switching element and the second resistor of the bridge circuit on the basis of the predetermined detection signal and the piezoelectric element is driven, the detection component outputs an output voltage of the differential amplifier to serve as the signal corresponding to behavior of the acoustic vibration system;
• and
• a judgment component that, on the basis of the detection signal and the signal outputted by the detection component, judges for a cause of defective ejections at the piezoelectric head.