A piezoelectric actuator includes a vibrating section configured to flexurally vibrate in an in-plane direction, a connecting section connected to the vibrating section in the vibrating direction of the vibrating section, a supporting section configured to support the vibrating section via the connecting section, and a reinforcing section provided on an opposite side of the vibrating section in the supporting section in a direction parallel to a direction in which the vibrating section and the connecting section are arranged.

An array of piezoelectric micromachined ultrasonic transducers (PMUTs) includes a first piezoelectric layer and a second piezoelectric layer, a dielectric layer positioned between the first piezoelectric layer and the second piezoelectric layer, and a plurality of conductive layers positioned on opposing surfaces of the first piezoelectric layer and opposing surfaces of the second piezoelectric layer. A plurality of isolation trenches extend through the dielectric layer and at least a portion of conductive layers of the plurality of conductive layers, where the plurality of isolation trenches are positioned between neighboring PMUTs of the array of PMUTs such that the neighboring PMUTs are electrically isolated, and wherein the plurality of isolation trenches relieve stress in the dielectric layer.

An ultrasonic tonometer, which measures an intraocular pressure of a subject eye using an ultrasonic wave, has an ultrasonic actuator including an ultrasonic element that generates an ultrasonic wave and a sonotrode that propagates the ultrasonic wave generated from the ultrasonic element, and irradiating the subject eye with the ultrasonic wave. The sonotrode includes an uneven portion in which a thickness of the sonotrode varies in a sound axis direction of the ultrasonic wave.

A method for producing an ultrasonic transducer including an arrangement determination step of determining an arrangement of piezoelectric elements in a stack on the basis of mechanical quality factors of the respective piezoelectric elements; and an assembly step of assembling the stack in which the piezoelectric elements are arranged according to the arrangement determined in the arrangement determination step, a horn, and a back mass. In the arrangement determination step, the arrangement of the piezoelectric elements is determined so that the difference in mechanical quality factor between the piezoelectric elements adjacent in the longitudinal direction is within 5% of a mean value of the mechanical quality factors of the piezoelectric elements.

An electroacoustic transducer includes: a polygonal-shaped laminated piezoelectric element including alternately stacked piezoelectric layers and electrode layers, with the piezoelectric layers placed between at least one pair of electrode layers having different polarities; and a circular vibration plate on which the laminated piezoelectric element is placed. Of the piezoelectric layers sandwiched between the at least one pair of electrode layers, the total volume (V) of those effective layers that overlap the at least one pair of electrode layers as viewed from the stacking direction satisfies the condition below:

0.2πR.sup.2×ts≦V≦2.0πR.sup.2×ts

wherein π represents the ratio of the circumference of a circle to its diameter, R represents the radius of the vibration plate, and ts represents the thickness of the vibration plate.

A haptic information presentation system uses a human sensory characteristic or illusion to suitably control a physical quantity, and causes a person to feel a force which cannot exist physically, or a haptic sensory physical characteristic.

A vibration presentation device includes: an electrostatic or piezoelectric actuator; a first elastic body laminated on the actuator; a second elastic body laminated on the actuator on the opposite side to the first elastic body; an electrostatic or piezoelectric sensor disposed around the actuator; a cover that holds the first elastic body and the second elastic body such that the first elastic body and the second elastic body are compressed more than the actuator, the cover transmitting, when a pressing force in the laminate direction is applied to the cover from the outside, the pressing force to a sensor, and vibrating by vibration generated by the actuator; and a control device that drives the actuator when the sensor detects the pressing force.

A sensor system for use in a wellbore is provided that can include a piezoelectric transducer for transmitting an acoustic wave into a fluid medium positioned in the wellbore by repeatedly bending between two positions in response to an actuation signal. The piezoelectric transducer can include at least four piezoelectric layers stacked on top of one another. Each of the four piezoelectric layers can be coupled to an adjacent layer via a bonding material. Each of the four piezoelectric layers can include a piezoelectric material, a top electrode coupled to a top surface of the piezoelectric material, and a bottom electrode coupled to a bottom surface of the piezoelectric material. The sensor system can also include a hydrophone for detecting a reflection or a refraction of the acoustic wave off an object in the wellbore and transmitting an associated signal to a processing device.

An underwater acoustic projector system that includes a linear array of acoustic projectors in close proximity such that the acoustic projectors interact with one another when they produce acoustic pressures, wherein each acoustic projector in the linear array is spaced apart from an adjacent acoustic projector by a respective distance, and wherein the respective distance between two acoustic projectors proximate the center of the linear array is greater than the respective distance between two acoustic projectors proximate the end of the linear array.

A transducer, a method of manufacturing a transducer, and a transducing device are provided. The transducer includes a receiving unit and a transmitting unit. The receiving unit includes a first receiving electrode, a first piezoelectric film, and a second receiving electrode which are sequentially stacked, and the receiving unit is configured to convert a first acoustic wave signal into an electrical signal by using a piezoelectric effect of the first piezoelectric film. The transmitting unit is configured to receive a control signal, which is based on the electrical signal, to transmit a second acoustic wave signal.