Piezoelectric actuator, drive control method of piezoelectric actuator, and electronic device

A drive control method of a piezoelectric actuator, the piezoelectric actuator including:

• a ring-shaped piezoelectric element;
• a first vibration area and a second vibration area provided on both sides of a bisector bisecting the piezoelectric element along a diameter of the piezoelectric element, the first vibration area and the second vibration area being respectively provided with at least one drive electrode to which a drive signal is supplied at a position substantially axisymmetric with respect to the bisector;
• and a detection electrode that detects vibrating condition of the piezoelectric element to output a vibration signal, the detection electrode being provided on at least one of the first vibration area and the second vibration area, the method comprising:
• providing the drive signal with a phase-advance drive signal and a phase-delay drive signal having a predetermined phase difference, the phase-advance drive signal that is phase-advanced relative to the phase-delay drive signal being supplied to one of the first vibration area and the second vibration area and the phase-delay drive signal that is phase-delayed relative to the phase-advance drive signal being supplied to the other of the first vibration area and the second vibration area;
• and
• variably controlling the frequency of the drive signal based on a detected phase difference between one of the phase-advance drive signal and the phase-delay drive signal and the vibration signal.

An electronic device, comprising a piezoelectric actuator, the piezoelectric actuator including:

• a ring-shaped piezoelectric element, vibration of the piezoelectric element being transmitted to an object;
• a first vibration area and a second vibration area provided on both sides of a bisector bisecting the piezoelectric element along a diameter of the piezoelectric element, the first vibration area and the second vibration area being respectively provided with at least one drive electrode to which a drive signal is supplied, the drive electrode being arranged substantially axisymmetrically with respect to the bisector,
• the drive signal including a phase-advance drive signal and a phase-delay drive signal having a predetermined phase difference, the phase-advance drive signal that is phase-advanced relative to the phase-delay drive signal being supplied to one of the first vibration area and the second vibration area and the phase-delay drive signal that is phase-delayed relative to the phase-advance drive signal being supplied to the other of the first vibration area and the second vibration area;
• and
• a detection electrode that detects vibrating condition of the piezoelectric element to output a vibration signal, the detection electrode being provided on at least one of the first vibration area and the second vibration area to which the phase-delay drive signal is supplied,
• the drive of the piezoelectric actuator being controlled based on a detected phase difference between one of the phase-advance drive signal and the phase-delay drive signal and the vibration signal.