A display apparatus includes a display module having a display panel configured to display an image; a sound generating device on a rear surface of the display panel and including a first side and a second side perpendicular to the first side and an adhesive member in a partial region of the sound generating device, the adhesive member having a size smaller than one of the first side and the second side of the sound generating device.

The present disclosure relates to an electronic device. The electronic device includes: a display panel assembly; a piezoelectric sound-generating unit bonded to the display panel assembly along a thickness direction of the electronic device; and a structural member connected to the display panel assembly or connected to the piezoelectric sound-generating unit to close a cavity. The cavity is away from a side of the piezoelectric sound-generating unit bonded to the display panel assembly.

A sound producing package structure configured to produce sound includes a substrate, a sound producing component and a conductive adhesive layer. The sound producing component is disposed on the substrate, and the sound producing component is configured to generate an acoustic wave corresponding to an input audio signal. The conductive adhesive layer is disposed between the substrate and the sound producing component by a surface mount technology.

A display device includes a display panel including a display layer including light-emitting elements disposed on a substrate, and a sensor electrode layer disposed on the display layer. The sensor electrode layer includes a first sound electrode and a second sound electrode; a vibration layer electrically contacting the first sound electrode and the second sound electrode and being deformed in response to a first sound driving voltage applied to the first sound electrode and a second sound driving voltage applied to the second sound electrode; and sensor electrodes disposed on the vibration layer. The sensor electrodes sense an input.

Provided is 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 piezoelectric film is 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 piezoelectric film in a thickness direction is observed with a scanning electron microscope, the polymer-based piezoelectric composite material is divided into two equal regions in the thickness direction, and void volumes of the two regions are measured, a ratio of the void volume obtained by dividing the void volume of the region with a larger void volume by the void volume of the region with a smaller void volume is 1.2 or greater.

Provided is a piezoelectric film capable of realizing a piezoelectric speaker in which a high sound pressure is obtained, a sufficient sound pressure characteristic is obtained in a wide frequency band, and generation of a chattering sound particularly in a low sound can be suppressed. The piezoelectric film is 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 laminated on both surfaces of the polymer-based piezoelectric composite material, in which a variation coefficient of a destructive force of a laminate having the polymer-based piezoelectric composite material and the electrode layers in a plane direction is 0.25 or less.

[Object] To provide an ultrasonic apparatus having a high transmission strength, high reception sensitivity, reliability, and excellent mass productivity.

[Solving Means] An ultrasonic apparatus according to the present technology includes an ultrasonic wave transmitting element and an ultrasonic wave receiving element. The ultrasonic wave transmitting element is arranged on a first surface side of the ultrasonic apparatus and has a structure in which a piezoelectric material layer is sandwiched by an upper electrode and a lower electrode. The ultrasonic wave receiving element is arranged between a second surface opposite to the first surface side of the ultrasonic apparatus and the ultrasonic wave transmitting element and has a MEMS structure.

The present invention provides a polymer-based piezoelectric composite material from which a piezoelectric film capable of outputting a higher sound pressure is obtained in a case of using a piezoelectric speaker, a piezoelectric film formed of the polymer-based piezoelectric composite material, and a piezoelectric speaker and a flexible display which are formed of the piezoelectric film. The polymer-based piezoelectric composite material of the present invention is a polymer-based piezoelectric composite material including a polymer matrix which contains a polymer having a unit represented by Formula (1), and at least one unit selected from the group consisting of, a unit represented by Formula (2-1), a unit represented by Formula (2-2), and a unit represented by Formula (2-3), and piezoelectric particles.

(MO.sub.x/2)  Formula (1)

(R.sup.1SiO.sub.3/2)  Formula (2-1)

(R.sup.2.sub.2SiO.sub.2/2)  Formula (2-2)

(R.sup.3.sub.3SiO.sub.1/2)  Formula (2-3)

Provided are a polymer-based piezoelectric composite material and a piezoelectric film which have high productivity and are capable of suppressing degradation of piezoelectric conversion efficiency in an environment where the temperature and the humidity are severe. The polymer-based piezoelectric composite material is a polymer-based piezoelectric composite material including piezoelectric particles in a matrix containing a polymer material, in which the polymer-based piezoelectric composite material contains greater than 500 ppm and 10000 ppm or less of a substance on a mass basis which has an SP value of less than 12.5 (cal/cm.sup.3).sup.1/2 and is in a liquid state at room temperature, voids are formed in the polymer-based piezoelectric composite material, and an area ratio of the voids in a cross section of the polymer-based piezoelectric composite material is 0.1% or greater and 20% or less.

The present invention provides a polymer-based piezoelectric composite material from which a piezoelectric film capable of outputting a higher sound pressure is obtained in a case of using a piezoelectric speaker, a piezoelectric film formed of the polymer-based piezoelectric composite material, and a piezoelectric speaker and a flexible display which are formed of the piezoelectric film. The polymer-based piezoelectric composite material of the present invention is a polymer-based piezoelectric composite material including a polymer matrix which contains a polymer containing a group represented by Formula (1), and piezoelectric particles.

*-L.sup.1-CR.sup.1R.sup.2—CN  Formula (1) In Formula (1), L.sup.1 represents a divalent linking group excluding a divalent aliphatic hydrocarbon group. R.sup.1 and R.sup.2 each independently represent a hydrogen atom, an alkyl group, or an aryl group.