Provided is a piezoelectric actuator, a linear driving device, and an electronic device that achieve displacement of a drive shaft of a given magnitude even in a case where a low voltage is applied. A piezoelectric actuator includes a piezoelectric material composed of a stack of plate-shaped piezoelectric elements, the piezoelectric material being expandable and contractable in a direction of a plate surface thereof; an elastic plate having the piezoelectric material formed on a plate surface of the elastic plate, and a drive shaft having one end fixed to either the piezoelectric material or the elastic plate in a direction perpendicular to the plate surface of the piezoelectric material.

An acoustic wave transmitting structure and a display device are provided. The acoustic wave transmitting structure includes a first layer, a second layer, and an intermediate layer. The first layer has a first acoustic impedance Z1. The second layer has a second acoustic impedance Z2. The intermediate layer is disposed between the first layer and the second layer, and has a third acoustic impedance Z3. Z1, Z2, and Z3 satisfy a relation: (Z1+Z2)/6.8Z3(Z1+Z2)/0.6. The display device includes a display panel and an acoustic wave generator. The display panel has a substrate. A plurality of display elements are disposed on one side of the substrate. The acoustic wave generator is disposed on the other side of the substrate of the display panel through the acoustic wave transmitting structure. The other side of the substrate is opposite to the one side of the substrate.

A device comprising a lid layer; an acoustic layer coupled to the lid layer, wherein the acoustic layer comprises: a piezoelectric layer; a dielectric layer; at least one material layer located in the dielectric layer; and a plurality of interconnects coupled to the piezoelectric layer; a cavity located between the lid layer and the piezoelectric layer; a substrate coupled to the dielectric layer of the acoustic layer; and at least one via interconnect coupled to the piezoelectric layer through the plurality of interconnects, wherein the at least one via interconnect extends through the dielectric layer and the substrate.

An apparatus may include a vibration member and a vibration device configured to vibrate the vibration member. The vibration device may be configured to comprise a first vibration portion and a second vibration portion which is different from the first vibration portion.

A converting element for converting between mechanical vibrations and electric signals comprises piezoelectric elements arranged in a stack and a connector, for example a wire. At the outside of the stack are grooves between adjacent piezoelectric elements. The connector is disposed within the grooves which are filled with an electrically conductive filling material. The connector is connected to the stack via a sintering process. The connector comprises inner segments arranged within the grooves and outer segments arranged outside of the grooves. The outer segments are arranged at the outside of the stack. A vibronic sensor may contain the converting unit.