Provided are a polymer-based piezoelectric composite material and a piezoelectric film having piezoelectric conversion characteristics stabilized by suppressing a change in piezoelectric conversion efficiency in various humidity environments. 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 a pore volume per unit area is in a range of 0.01 μL/mm.sup.2 to 1.7 μL/mm.sup.2, which is acquired in a manner that a mercury penetration amount of a sample obtained by cutting a polymer-based piezoelectric composite material in a thickness direction and cutting out the polymer-based piezoelectric particle into a size of 12.5 mm×25 mm is measured by a mercury penetration method, and the penetration amount is divided by an area of a cross-section of the sample.

Systems and techniques are provided for a piezoelectric transducer. A base plate includes a first electrical contact and a second electrical contact. A transduction element is mounted directly on the base plate and electrically connected to the first electrical contact. A spacer includes a via. The via includes electrically conductive material. The spacer is mounted on the base plate around the transduction element and the electrically conductive material of the via is electrically connected to the second electrical contact. A diaphragm is mounted on the spacer and on the transduction element.

The present invention provides a polymer-based piezoelectric composite material from which a piezoelectric film capable of outputting a higher sound pressure and exhibiting excellent flexibility even in a low-temperature environment 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).sub.n—CN  Formula (1)

In Formula (1), L.sup.1 represents a divalent linking group excluding a urethane group. R.sup.1 and R.sup.2 each independently represent a hydrogen atom, an alkyl group, or an aryl group. n represents an integer of 3 or greater. * represents a bonding position with respect to the main chain of a polymer.

A crossover circuit, disposed within a sound producing device including a first sound producing cell driven by a first driving signal and a second sound producing cell driven by a second driving signal, includes a first filter receiving an input signal at an input terminal of the first filter, a first subtraction circuit, and a second filter coupled between the output terminal of the first filter and the second input terminal of the first subtraction circuit. A first input terminal of the first subtraction circuit is coupled to the input terminal of the first filter; a second input terminal of the first subtraction circuit is coupled to an output terminal of the first filter. The crossover circuit produces the first driving signal and the second driving signal according to a first output signal of the first subtraction circuit and a second output signal of the first filter respectively.

A panel bottom member structure includes a panel bottom member including a light absorbing member, a top bonding layer disposed on the light absorbing member, an acoustic vibration element disposed beneath the light absorbing member and generating a vibration in response to an acoustic signal, and a buffer member disposed beneath the light absorbing member and non-overlapping the acoustic vibration element, and an element circuit board connected to the acoustic vibration element and provided with an acoustic element driving chip for generating the acoustic signal.

Provided are an electroacoustic conversion film and an electroacoustic converter which are capable of suppressing a decrease in piezoelectric conversion efficiency in a case of use in a high-temperature environment. The electroacoustic conversion film is an electroacoustic conversion film including a polymer-based piezoelectric composite material which contains piezoelectric particles in a matrix containing a polymer material, and electrode layers which are formed on both surfaces of the polymer-based piezoelectric composite material, in which the electroacoustic conversion film has a thermal expansion coefficient of 12 ppm/° C. to 100 ppm/° C.

A display apparatus includes: a display module including a display panel configured to display an image, a vibration plate on a rear surface of the display module, a connection member between the rear surface of the display module and the vibration plate, at least one vibration module on the vibration plate, and an enclosure between the display module and the vibration plate, the enclosure being spaced apart from the vibration module, the enclosure surrounding the vibration module.

An apparatus includes a display panel displaying an image and a vibration apparatus disposed at a rear surface of the display panel to vibrate the display panel. The vibration apparatus may include a plurality of vibration generators overlapping one another. Accordingly, a sound may be generated based on a vibration of the display panel, and a sound having an enhanced sound pressure level characteristic may be output in a forward direction of the display panel.

Display panel and display apparatus including the same. A display panel includes a first substrate including a display portion configured to display an image, a second substrate attached to the first substrate by an adhesive member, and a vibration generating module within the adhesive member to overlap the display portion. The vibration generating module is surrounded by the second substrate and the adhesive member.

The present disclosure relates to a vibration generation device, a display apparatus including the vibration generation device, and a vehicle including the vibration generation device. A vibration generation device includes a piezoelectric ceramic part having a certain interval, a piezoelectric material layer between the piezoelectric ceramic parts, and an electrode part configured to provide electric field to one or more of the piezoelectric ceramic part and the piezoelectric material layer.