An object is to provide a piezoelectric film that has excellent flexibility in a high temperature environment at higher than 50° C. and exhibits good flexibility even at room temperature, a laminated piezoelectric element in which the piezoelectric films are laminated, and an electroacoustic transducer using the piezoelectric film or the laminated piezoelectric element. The object is solved by the piezoelectric film including: a polymer-based piezoelectric composite material in which piezoelectric particles are dispersed in a matrix including a polymer material; and electrode layers provided on both surfaces of the polymer-based piezoelectric composite material, in which a loss tangent at a frequency of 1 Hz according to dynamic viscoelasticity measurement has a maximal value of greater than or equal to 0.1 existing in a temperature range of higher than 50° C. and lower than or equal to 150° C., and has a value of greater than or equal to 0.08 at 50° C.

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.

Microphones, microphone systems, and methods for capturing and processing sound are described. The microphones and microphone systems may adaptively change the direction from which sound is captured. The microphones and microphone systems avoid the need to provide arrays of microphones, while providing adaptive beamforming without a time delay between each channel of information, and multi-directional sound capture. A dependency between the frequency response and system size is also avoided.

A microelectromechanical electroacoustic transducer includes a supporting frame of semiconductor material, a membrane of semiconductor material, connected to the supporting frame along a perimeter and having central symmetry, and a piezoelectric actuator on a peripheral portion of the membrane. The membrane has through slits of elongated shape arranged around a center of the membrane.

An apparatus includes a test circuit to receive signals from a piezoelectric horn and a control circuit to determine whether to operate the apparatus in a silent test mode or a normal mode. The apparatus includes a control circuit to, based on a determination to operate in the normal mode, enable a driver circuit to drive the piezoelectric horn so as to output sound when activated by the driver circuit. The test circuit is to, based on a determination to operate in the silent test mode, cause the piezoelectric horn to generate a piezoelectric response, wherein the piezoelectric horn is silent while generating the piezoelectric response during the silent test mode, and cause evaluation of whether or not the piezoelectric horn is working correctly based upon the received signals from the piezoelectric horn.

An ultra-wide bandwidth acoustic transducer may include multiple layers, including an inner piezoelectric layer, a polymer coupling layer and an outer piezoelectric layer. The polymer layer may be located between, and may be bonded to, the inner and outer piezoelectric layers. The transducer may have multiple eigenfrequencies of vibration. These eigenfrequencies may include primary resonant frequencies of the inner and outer piezoelectric layers respectively and may also include resonant frequencies that arise due to coupling between the layers. An acoustic backscatter system may employ such a transducer in backscatter nodes as well as in a transmitter. The multiple eigenfrequencies may enable the system to perform spread-spectrum communication at a high throughput. These multiple eigenfrequencies may also enable each backscatter node to shift frequency of an uplink signal, which in turn may enable the system to mitigate self-interference and to decode concurrent signals from multiple backscatter nodes.

An object is to provide a piezoelectric film that has excellent flexibility in a sub-zero environment and exhibits the required flexibility even at room temperature, a laminated piezoelectric element in which the piezoelectric films are laminated, and an electroacoustic transducer using the piezoelectric film or the laminated piezoelectric element. The object is solved by the piezoelectric film including: a polymer-based piezoelectric composite material in which piezoelectric particles are dispersed in a matrix including a polymer material; and electrode layers formed on both surfaces of the polymer-based piezoelectric composite material, in which a loss tangent at a frequency of 1 Hz according to dynamic viscoelasticity measurement has a maximal value of greater than or equal to 0.1 existing in a temperature range of higher than or equal to −80° C. and lower than 0° C., and has a value of greater than or equal to 0.05 at 0° C.

A display apparatus includes a display panel including configured to display an image and a sound generating device on a rear surface of the display panel, the sound generating device being configured to vibrate the display panel to generate sound. The sound generating device includes a first structure and a second structure over or under the first structure, the second structure including a first part having a piezoelectric characteristic and a second part between adjacent first parts to have flexibility.

A flexible electronic device includes: a sensor; a flexible display; a piezoelectric speaker including N piezoelectric films attached to the flexible display; and a processor configured to: detect a change of a state of the flexible display through the sensor; based on the change of the state of the flexible display, determine locations of a number of piezoelectric films through which sound is to be output, among the N piezoelectric films; and output sound through the number of piezoelectric films by controlling the piezoelectric films to be activated, based on the determined locations of the number of piezoelectric films.

An ultrasonic generator includes a substrate, a lower electrode on the substrate, an upper electrode on the lower electrode, and an ultrasonic generation unit between the lower electrode and the upper electrode. The ultrasonic generation unit includes a vibration chamber and an ultrasonic generation layer on the vibration chamber. The ultrasonic generation layer is configured to propel a surrounding medium to vibrate to generate ultrasonic waves in response to a voltage difference between the upper electrode and the lower electrode.