A loudspeaker includes two diaphragms arranged opposite each other, a drive unit for deflecting the two diaphragms in response to a control signal, the drive unit being coupled to the two diaphragms such that a first one of the two diaphragms is deflected in a first direction, and a second one of the two diaphragms is deflected in a second direction equal to the first direction.

A speaker array includes a first speaker device having a first membrane and a first acoustic channel, the first membrane being configured to oscillate and generate a first ultrasonic acoustic signal configured to be transmitted at least partially in the first acoustic channel, the first acoustic channel including at least one dimension comparable to a dimension of a viscous boundary layer of air. A second speaker device includes a second membrane and a second acoustic channel, the second membrane being configured to oscillate and generate a second ultrasonic acoustic signal configured to be transmitted at least partially in the second acoustic channel, the second acoustic channel including at least one dimension comparable to the dimension of the viscous boundary layer of air. An audio output of the speaker array is the combined output of at least the first speaker device and the second speaker device.

A speaker array includes a first speaker device having a first membrane and a first acoustic channel, the first membrane being configured to oscillate and generate a first ultrasonic acoustic signal configured to be transmitted at least partially in the first acoustic channel, the first acoustic channel including at least one dimension comparable to a dimension of a viscous boundary layer of air. A second speaker device includes a second membrane and a second acoustic channel, the second membrane being configured to oscillate and generate a second ultrasonic acoustic signal configured to be transmitted at least partially in the second acoustic channel, the second acoustic channel including at least one dimension comparable to the dimension of the viscous boundary layer of air. An audio output of the speaker array is the combined output of at least the first speaker device and the second speaker device.

The present disclosure discloses a MEMS chip including a capacitance system and a substrate with a back cavity. The capacitance system includes a back plate and a membrane; the substrate is located on one side of the membrane away from the back plate, including a first surface opposite to the membrane, a second surface opposite to the first surface, and an inner wall connecting the first surface and the second surface and enclosing the back cavity; the inner wall includes a first opening close to the membrane, having a first width along a first direction perpendicular with a vibration direction of the membrane, and a second opening away from the membrane, having a second width smaller than the first width along the first direction. The resonance frequency of the MEMS chip has been effectively improved and the SNR is simultaneously high.

The present disclosure discloses a MEMS chip which includes a substrate, a back plate fixed on the substrate, and a membrane fixed on the substrate and located above the back plate. A sealed space is formed between the membrane and the back plate. A support pillar is received in the sealed space. Two ends of the support pillar along a vibration direction of the membrane are separately fixed on the membrane and the back plate. As a result, when decreasing the volume of the back cavity, the resonance frequency of the MEMS chip has been effectively improved and the SNR is simultaneously high. Furthermore, the support pillar can effectively improve the reliability and crack resistance of the membrane.

Provided is an acoustic diaphragm with required properties for a vibrating part and an edge part thereof. The acoustic diaphragm comprises a vibrating part 11 and an edge part 12 located at an outer periphery of the vibrating part, wherein the vibrating part comprises a thermoplastic liquid crystal polymer (TLCP) having a certain composition; the edge part comprises a TLCP having a same composition as the TLCP of the vibrating part; and the vibrating part 11 and the edge part 12 have elastic moduli E.sub.d and E.sub.e measured by nanoindentation technique, respectively, which satisfy the following formula: E.sub.d>E.sub.e. For example, a ratio E.sub.d/E.sub.e of the elastic modulus E.sub.d of the vibrating part 11 to the elastic modulus E.sub.e of the edge part 12 may fall within a range of from 1.05 to 5.0.

A glass sheet composite includes a first glass sheet, a second sheet disposed opposite the first glass sheet, and a liquid layer formed by sealing up a liquid between the first glass sheet and the second sheet, in which the glass sheet composite has a plurality of vibration areas that are independent of each other in a plan view. The glass sheet composite is a diaphragm including at least one vibrator disposed on one side or both sides of the glass sheet composite. The glass sheet composite enables independent vibration at each of the vibration areas, and enables not only stereophonic or multiphonic reproduction but also local reproduction to be performed along with images. Since the diaphragm includes a vibrator, this diaphragm is excellent in sound reproduction.

A glass sheet composite includes a first glass sheet, a second sheet disposed opposite the first glass sheet, and a liquid layer formed by sealing up a liquid between the first glass sheet and the second sheet, in which the glass sheet composite has a plurality of vibration areas that are independent of each other in a plan view. The glass sheet composite is a diaphragm including at least one vibrator disposed on one side or both sides of the glass sheet composite. The glass sheet composite enables independent vibration at each of the vibration areas, and enables not only stereophonic or multiphonic reproduction but also local reproduction to be performed along with images. Since the diaphragm includes a vibrator, this diaphragm is excellent in sound reproduction.

A micro-electro-mechanical systems (MEMS) die includes a piston; an electrode facing the piston, wherein a capacitance between the piston and the electrode changes as the distance between the piston and the electrode changes; and a resilient structure (e.g., a gasket or a pleated wall) disposed between the piston and the electrode, wherein the resilient structure supports the piston and resists the movement of the piston with respect to the electrode. A back volume is bounded by the piston and the resilient structure and the resilient structure blocks air from leaving the back volume. The piston may be a rigid body made of a conductive material, such as metal or a doped semiconductor. The MEMS die may also include a second resilient structure, which provides further support to the piston and is disposed within the back volume.

A vibration device includes: a glass diaphragm; an exciter which is fixed to the glass diaphragm and vibrates the glass diaphragm; an enclosing member which defines an internal space by enclosing a portion, including a fixing position of the exciter, of the glass diaphragm, one end portion of the glass diaphragm being exposed to outside the internal space through an opening of the internal space; and a shielding member for acoustic shielding between the opening and the glass diaphragm, the shielding member dividing the glass diaphragm into an excitation region located inside the internal space and a vibration region located outside the internal space.