A control method of a piezoelectric driving device which includes a vibrator including a piezoelectric element and vibrating by application of a drive signal to the piezoelectric element, a driven unit moving by the vibration of the vibrator, a drive signal generation unit generating the drive signal based on a pulse signal, the control method including: stopping the application of the drive signal to the piezoelectric element at the time when a driving speed of the driven unit is a reference speed, in a case of stopping driving of the driven unit.

A piezoelectric element includes: a first electrode and a second electrode; and a piezoelectric layer provided between the first electrode and the second electrode and having a perovskite structure, in which 0<P1/P2≤0.5 and 0<P1 where, when a positive predetermined voltage is applied to the piezoelectric layer, then a voltage applied to the piezoelectric layer is set to 0 V for 0.1 seconds, and then a triangular wave voltage waveform having a maximum voltage of the predetermined voltage is applied to the piezoelectric layer to obtain a hysteresis curve drawn counterclockwise, P1 is a residual polarization amount at a start point of the hysteresis curve and P2 is a residual polarization amount at an end point of the hysteresis curve.

The present invention is a piezoelectric actuator drive method, a piezoelectric actuator drive circuit, and a piezoelectric actuator drive system capable of causing a piezoelectric element to vibrate in a maximum amplitude state. The piezoelectric actuator drive circuit includes: an obtainment unit that obtains operation information pertaining to operation of the piezoelectric element in a period that is a part of one cycle of a drive cycle in which the piezoelectric element is driven; and a control unit that performs feedback control of a drive parameter for driving the piezoelectric element based on the operation information.

An ultrasonic fingerprint recognition sensor and a manufacturing method thereof, and a display device are disclosed. The ultrasonic fingerprint recognition sensor includes a resonant cavity, a receiver electrode, a drive electrode, and a piezoelectric thin film layer between the receiver electrode and the drive electrode, the resonant cavity is on a side, closer to the piezoelectric thin film layer, of the receiver electrode, and is configured to increase vibration amplitude of the piezoelectric thin film layer.

In some embodiments, a piezoelectric device is provided. The piezoelectric device includes a semiconductor substrate. A first electrode is disposed over the semiconductor substrate. A piezoelectric structure is disposed on the first electrode. A second electrode is disposed on the piezoelectric structure. A heating element is disposed over the semiconductor substrate. The heating element is configured to heat the piezoelectric structure to a recovery temperature for a period of time, where heating the piezoelectric structure to the recovery temperature for the period of time improves a degraded electrical property of the piezoelectric device.

A piezoelectric element drive circuit includes a piezoelectric element driven at a predetermined frequency and having a resonant frequency of (2n+1) times the predetermined frequency (n is a predetermined natural number), and a drive voltage generator that has a first output terminal connected to a first terminal of the piezoelectric element and a second output terminal connected to a second terminal of the piezoelectric element. When the piezoelectric element is driven, a waveform of potential difference between the first output terminal and the second output terminal is a step wave which transitions while taking an intermediate potential. A time length for which the potential difference is the intermediate potential is around (t2−t1)/(2n+1) in a period of time from time t.sub.1 at which the potential difference falls to the intermediate potential to time t.sub.2 at which the potential difference falls to the intermediate potential subsequently.

In piezoelectric sensors, conventional amplification factor adjustment methods involving the cutting of a wiring pattern or use of a laser trimmable resistor are unable to adjust the amplification factor when the sensor is in a completed state. As a result, the production process becomes complex and production costs increase. Further, because the amplification factor adjustment is carried out in a different state from that of the finished product, the problem that the amplification factor is not set correctly in the finished product also occurs. A non-volatile memory is incorporated in an integrated circuit in which there are integrated piezoelectric sensor circuit elements. The amplification factor is adjusted by writing data from a writing terminal to change an amplification resistor a.

An ultrasonic sensor includes a vibration plate that includes a vibration portion and is formed of a resin; a wall portion that is provided on the vibration plate, surrounds the vibration portion and is formed of a resin; and a piezoelectric element that is provided in the vibration portion of the vibration plate. Accordingly, the wall portion surrounding the vibration portion can suppress a frequency variation of an ultrasonic wave output from the ultrasonic sensor and can deform the ultrasonic sensor into a shape corresponding to a surface of an object having various shapes.

Examples include a device including a nanovoided polymer element having a first surface and a second surface, a first plurality of electrodes disposed on the first surface, a second plurality of electrodes disposed on the second surface, and a control circuit configured to apply an electrical potential between one or more of the first plurality of electrodes and one or more of the second plurality of electrodes to induce a physical deformation of the nanovoided polymer element.

An ultrasound system, probe and method are provided. The ultrasound system includes a transducer with piezoelectric transducer elements polarized in a poling direction. A bipolar transmit circuit is configured to generate a transmit signal having first and second polarity segments. The first and second polarity segments have corresponding first and second peak amplitudes. A bias generator is configured to generate a bias signal in a direction of the poling direction. The bias signal is combined with the transmit signal to form a biased transmit signal that is shifted in the direction of the poling direction and still includes both of positive and negative voltages over a transmit cycle.