A method of operating electro-acoustical transducers such as PMUTs involves applying to the transducer an excitation signal over an excitation interval, acquiring at the transducer a ring-down signal indicative of the ring-down behavior of the transducer after the end of the excitation interval, and calculating, as a function of said ring-down signal, a resonance frequency of the electro-acoustical transducer. A bias voltage of the electro-acoustical transducer can be controlled as a function of the resonance frequency. An acoustical signal received can be transduced into an electrical reception signal and a damping parameter of the electro-acoustical transducer can be calculated as a function of the ring-down signal so that a cross-correlation reference signal can be synthesized as a function of the resonance frequency and the damping ratio of the electro-acoustical transducer. Such a cross-correlation reference signal can be used for cross-correlation with the electrical reception signal to improve the reception quality.

An imaging device includes a two dimensional array of piezoelectric elements. Each piezoelectric element includes: a piezoelectric layer; a bottom electrode disposed on a bottom side of the piezoelectric layer and configured to receive a transmit signal during a transmit mode and develop an electrical charge during a receive mode; and a first top electrode disposed on a top side of the piezoelectric layer; and a first conductor, wherein the first top electrodes of a portion of the piezoelectric elements in a first column of the two dimensional array are electrically coupled to the first conductor.

An ultrasonic induction circuit is provided, a first electrode of an ultrasonic sensor is electrically connected with a first terminal of the ultrasonic sensing circuit, a second electrode is electrically connected with a second terminal of a first potential supply sub-circuit, and the first terminal of the first potential supply sub-circuit is electrically connected with a first potential supply end. A gate of M1 is electrically connected with the second electrode and the second terminal of the compensation sub-circuit. The second electrode is electrically connected with the first terminal of the compensation sub-circuit. The first electrode is coupled to the second potential supply end. The first terminal of the signal output sub-circuit is electrically connected to the second electrode of the first transistor, and the second terminal is electrically connected to the second terminal of the ultrasonic induction circuit.

A vibration device includes a piezoelectric element, a vibration member to which the piezoelectric element is bonded, and a wiring member connected with the piezoelectric element. A method for vibrating the vibration device includes inputting a signal including a fundamental frequency component to the piezoelectric element through the wiring member, and vibrating the vibration device in a vibration mode that includes the fundamental frequency component and does not approximately include a high order frequency component that is n times (n represents an integer of 2 or more) the fundamental frequency component. The fundamental frequency component is lower than the resonance frequency component of the vibration device.

Provided is a driving apparatus that sets a signal wave in a low-frequency region having a frequency of 10 Hz or more and 250 Hz or less as a modulating wave and outputs to a piezoelectric actuator a driving signal having a waveform obtained by modulating an amplitude of a sine wave in a high-frequency region having a frequency of 20 kHz or more and 40 kHz or less with the modulating wave.

A power module for producing structure-borne sound. The power module includes: a control unit and a first substrate, the control unit being situated on the first substrate; at least one first power semiconductor and at least one second power semiconductor, the first substrate being situated on the at least one first power semiconductor and on the at least one second power semiconductor; a first metal connection, a second substrate, and a second metal connection, the first metal connection electrically connecting the first substrate and the second substrate, and the second metal connection being situated below the second substrate, wherein the second substrate has a piezoelectric material and the control unit is set up to excite the piezoelectric material of the second substrate so that a structure-borne sound signal is produced.

A vibratory actuator control apparatus includes a vibrating member, having an electro-mechanical energy conversion element, and a contact member that contacts the vibrating member. In a second case where the vibrating member and the contact member are brought from a stationary state to a stopped state, an operation sequentially passes through a third stage and a fourth stage. The third stage is for decelerating a relative movement driving speed by applying a driving voltage to the electro-mechanical energy conversion element while maintaining a control parameter of the driving voltage constant and increasing a driving frequency. The fourth stage is for decelerating the driving speed by applying the driving voltage to the electro-mechanical energy conversion element while maintaining the driving frequency constant and decreasing the control parameter of the driving voltage. A start frequency is set based on the driving frequency corresponding to a predetermined driving speed in the third stage.

A vibrating piezoelectric atomizer comprising: a piezoelectric tube having a length, a first end defining an opening and a second end, the second end of the piezoelectric transducer tubular body is connected to a horn; the horn is dimensioned to be half wavelength resonator; the horn is folded and located alongside the piezoelectric tube; a metallic disk is connected to the horn near the first end of the piezoelectric tube, whereby by applying an alternating voltage across electrodes of the piezoelectric tube, the piezoelectric tube is excited into a resonant vibration when frequency of excitation equals to half wavelength resonant frequency of the piezoelectric tube's length and vibrates in synchronism and is communicated to the metallic disk to atomize a liquid.

A method of operating electro-acoustical transducers such as PMUTs involves applying to the transducer an excitation signal over an excitation interval, acquiring at the transducer a ring-down signal indicative of the ring-down behavior of the transducer after the end of the excitation interval, and calculating, as a function of said ring-down signal, a resonance frequency of the electro-acoustical transducer. A bias voltage of the electro-acoustical transducer can be controlled as a function of the resonance frequency. An acoustical signal received can be transduced into an electrical reception signal and a damping parameter of the electro-acoustical transducer can be calculated as a function of the ring-down signal so that a cross-correlation reference signal can be synthesized as a function of the resonance frequency and the damping ratio of the electro-acoustical transducer. Such a cross-correlation reference signal can be used for cross-correlation with the electrical reception signal to improve the reception quality.

A control device for reducing and homogenizing welding residual stress by acoustic waves, comprising: a fixing tool having two rows of through holes; a plurality of ultrasonic transducers each having a body and a conical horn transmitting portion at a lower end of the body, wherein lower ends of the horn transmitting portions are fixedly connected with flanges, the horn transmitting portions of the ultrasonic transducers extend into respective through holes of the fixing tool to be in contact with welded parts below the fixing tool, the flanges are fixed to the fixing tool by bolts, and the two rows of through holes are arranged both sides of a welding seam of the welded parts; and a driving device for driving the ultrasonic transducers to operate. A corresponding control method is also provided. The control device can be used to control residual stress at the welding seam of steels.