An object of the present invention is to provide a piezoelectric film capable of realizing an electroacoustic conversion film or the like in which the durability is high and a sufficient sound pressure with respect to an input operating voltage is obtained. The object is achieved by providing a piezoelectric film including a polymer-based piezoelectric composite material which contains piezoelectric particles in a matrix containing a polymer material, and electrode layers which are provided on both surfaces of the polymer-based piezoelectric composite material, in which in a case where a cross section of the film in a thickness direction is observed with a scanning electron microscope, the polymer-based piezoelectric composite material is divided into ten equal regions in the thickness direction, area ratios of the piezoelectric particles in two most distant regions are measured, and the area ratio of the piezoelectric particles in the region with a lower area ratio is set as 1, the area ratio of the piezoelectric particles in the region with a higher area ratio is 1.2 or greater.

An acoustic wave device includes a functional electrode provided on a first main surface of an element substrate, extended wiring lines that are electrically connected to the functional electrode and that are adjacent to each other on a second main surface facing away from the first main surface, external terminals that are connected to the extended wiring lines, respectively, and that are provided on the second main surface, a first resin portion that seals the acoustic wave device, and a second resin portion that is provided at a position which is between the element substrate and the first resin portion and which is on the second main surface.

Piezoelectric devices are described fabricated in packaging buildup layers. In one example, a package has a plurality of conductive routing layers and a plurality of organic dielectric layers between the conductive routing layers. A die attach area has a plurality of vias to connect to a microelectronic die, the vias connecting to respective conductive routing layers. A piezoelectric device is formed on an organic dielectric layer, the piezoelectric device having at least one electrode coupled to a conductive routing layer.

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.

A piezoelectric component that has a piezoelectric element including a piezoelectric ceramic layer and a sintered metal layer on at least a first main surface of the piezoelectric ceramic layer and containing a non-precious metal, and a protective layer containing an elastic body covering first and second opposed main surfaces of the piezoelectric element. The piezoelectric ceramic layer contains 90 mol % or more of a perovskite compound that contains niobium, an alkali metal, and oxygen. A thickness of the piezoelectric element is 100 μm or less.

An active acoustic system includes a thin-film sheet having an array of piezoelectric microstructures embossed in the film. Each piezoelectric microstructure may act as a speaker and/or a microphone. A control circuit is configured to individually address the piezoelectric microstructures to provide a separate voltage signal to, or receive a separate voltage signal from, each piezoelectric microstructure.

In an ultrasonic sensor that is attached to a body component, a negative electrode line connected to a negative terminal is isolated from a shielding portion. The shielding portion is connected to a ground potential point without being connected to the negative electrode line.

Bulk acoustic wave (BAW) resonators, and particularly top electrodes with step arrangements for BAW resonators are disclosed. Top electrodes on piezoelectric layers are disclosed that include a border (BO) region with a dual-step arrangement where an inner step and an outer step are formed with increasing heights toward peripheral edges of the top electrode. Dielectric spacer layers may be provided between the outer steps and the piezoelectric layer. Passivation layers are disclosed that extend over the top electrode either to peripheral edges of the piezoelectric layer or that are inset from peripheral edges of the piezoelectric layer. Piezoelectric layers may be arranged with reduced thickness portions in areas that are uncovered by top electrodes. BAW resonators as disclosed herein are provided with high quality factors and suppression of spurious modes while also providing weakened BO modes that are shifted farther away from passbands of such BAW resonators.

A piezoelectric transformer comprises at least a laminate of a first member, a first piezoelectric element, a second piezoelectric element and a second member sequentially stacked one on the other in the above-listed order and a pressurizing mechanism for squeezing the first member and the second member together in the stacking direction. The ratio of the electromechanical coupling coefficient k.sub.33 relative to the electromechanical coupling coefficient k.sub.31 (k.sub.33/k.sub.31) of the first piezoelectric element and the second piezoelectric element is not less than 2.0.

A structure includes an oriented piezoelectric polymer arranged in a circular tubular or circular columnar shape, wherein the orientation angle of the piezoelectric polymer with respect to the central axis of the structure is 15° to 75°, the piezoelectric polymer includes a crystalline polymer having an absolute value of 0.1 to 1000 pC/N for the piezoelectric constant d14 when the orientation axis is the third axis, and the piezoelectric polymer includes a P-body containing a crystalline polymer with a positive piezoelectric constant d14 value and an N-body containing a crystalline polymer with a negative value, wherein for the portion of the central axis of the structure having a length of 1 cm, the value of T1/T2 is 0 to 0.8, T1 being the smaller and T2 being the larger of (ZP+SN) and (SP+ZN), where ZP, SP, ZN, and SN are particularly defined masses.