An object of the present invention is to provide an electroacoustic transducer and an image display device, each of which can be rolled up and does not need a mechanical mechanism and a driving source. The object is accomplished by providing a vibration plate or display element which can be rolled up, and a convex leaf spring having an arc-shaped cross section in the lateral direction and having a concave side disposed facing one surface of the vibration plate or a non-image-displaying surface of the display element.

A piezoelectric device includes a substrate on which a plurality of recesses are arranged in a first direction, a vibration plate, and a piezoelectric actuator having a first electrode, a second electrode and a third electrode, a fourth electrode, and a piezoelectric layer, in which a plurality of active portions are provided, the second electrode and the third electrode are provided from an edge of a region facing a recess to an outside of the recess, the first electrode is formed between the second electrode and the third electrode, and the fourth electrode configures a common electrode for the plurality of active portions.

A piezoelectric device includes a substrate on which a plurality of recesses are arranged in a first direction, a vibration plate, and a piezoelectric actuator having a first electrode, a second electrode and a third electrode, a fourth electrode, and a piezoelectric layer, in which a plurality of active portions are provided, the second electrode and the third electrode are provided from an edge of a region facing a recess to an outside of the recess, the first electrode is formed between the second electrode and the third electrode, the second electrode, the third electrode, and the fourth electrode configure common electrodes for the plurality of active portions, and the first electrode configures an individual electrode provided independently for each of the active portions.

A waveform improvement method includes providing a piezoelectric material coupled to a matching material, generating a plurality of first grooves in a matching layer of at least one matching layer, packaging an isolation material into the plurality of first grooves, and providing two input voltages to the piezoelectric material for generating an ultrasonic signal by the piezoelectric material. The piezoelectric material includes at least one piezoelectric layer. The matching material includes at least one matching layer. The matching material is used to match acoustic impedance of the piezoelectric material. The plurality of first grooves in the matching layer are used to optimize the acoustic impedance and a vibration isolation effect.

A waveform improvement method includes providing a piezoelectric material coupled to a matching material, generating a plurality of first grooves in a matching layer of at least one matching layer, packaging an isolation material into the plurality of first grooves, and providing two input voltages to the piezoelectric material for generating an ultrasonic signal by the piezoelectric material. The piezoelectric material includes at least one piezoelectric layer. The matching material includes at least one matching layer. The matching material is used to match acoustic impedance of the piezoelectric material. The plurality of first grooves in the matching layer are used to optimize the acoustic impedance and a vibration isolation effect.

A control device that controls an electronic device including a top panel having an operation surface, a position detector that detects a position of operational input performed on the operation surface, and a first vibrating element that generates vibration in the top panel, the control device includes a first processor that outputs a first drive signal to the first vibrating element to drive the first vibrating element; a first capacitor inserted in series between the first vibrating element and the first processor; and a first differential amplifier that detects a first voltage of the first capacitor or the first vibrating element, wherein the first processor is configured to determine whether pressing operation to the top panel has been performed based on the first voltage detected by the first differential amplifier.

A thermal excitation acoustic-wave-generating device includes a first heating element, a substrate that includes a main surface along which the first heating element is disposed, and a facing body that faces the substrate with the first heating element interposed therebetween. The substrate and the facing body define a path for an acoustic wave. A length of the path is close to a whole number multiple of ¼ of a wavelength of the acoustic wave.

A haptic actuator is disclosed. The haptic actuator includes a polygonal piezoelectric element configured to generate a displacement thereof while expanding and contracting in accordance with polarities of a voltage applied thereto, and a jig member coupled to the piezoelectric element at upper and lower sides of the piezoelectric element in a thickness direction of the piezoelectric element in a state of contacting only corners of the piezoelectric element and configured to amplify the displacement generated at the piezoelectric element, thereby vibrating. The jig member amplifies the displacement generated at the piezoelectric element and, as such, vibrates. Accordingly, it is possible to provide excellent haptic effects with high resolution to the user, using even a small voltage.

A piezoelectric device includes a piezoelectric single crystal body with a homogeneous polarization state and of which at least a portion flexurally vibrates, an upper electrode on an upper surface of the piezoelectric single crystal body, a lower electrode on a lower surface of the piezoelectric single crystal body, and a supporting substrate below the piezoelectric single crystal body. A recess extends from a lower surface of the supporting substrate toward the lower surface of the piezoelectric single crystal body.

A piezoelectric device includes a piezoelectric single crystal body with a homogeneous polarization state and of which at least a portion flexurally vibrates, an upper electrode on an upper surface of the piezoelectric single crystal body, a lower electrode on a lower surface of the piezoelectric single crystal body, and a supporting substrate below the piezoelectric single crystal body. A recess extends from a lower surface of the supporting substrate toward the lower surface of the piezoelectric single crystal body.