TWI843202B - Acoustic output device - Google Patents

Abstract

The present disclosure may disclose an acoustic device, including: a first vibration element, a second vibration element, and a piezoelectric element. The piezoelectric element drives the first vibration element and the second vibration element to vibrate in response to an electrical signal, wherein the first vibrating element is connected to the first position of the piezoelectric element, the second vibration element is connected to the second position of the piezoelectric element through a first elastic element, the second vibration element is connected to the third position of the piezoelectric element at a third position through a second elastic element. In the vibration direction of the second vibration element, the first elastic coefficient of the first elastic element is different from the second elastic coefficient of the second elastic element.

Description

Acoustic output device

This invention relates to the field of acoustic technology, and in particular to an acoustic output device.

This invention claims priority to the Chinese patent application No. 202210361236.2 filed on April 7, 2022, the entire contents of which are incorporated herein by reference.

Piezoelectric acoustic output devices use the reverse piezoelectric effect of piezoelectric materials to generate vibrations and radiate sound waves. Compared with transducer-electric speakers, they have the advantages of high electromechanical energy conversion efficiency, low energy consumption, small size, and high integration. With the current trend of device miniaturization and integration, piezoelectric acoustic output devices have extremely broad prospects and future. However, piezoelectric acoustic output devices have low sensitivity in the mid- and high-frequency bands (for example, the frequency range of 500Hz~10kHz) and more vibration modes in the audible range of the human ear (for example, 20Hz~20kHz), which leads to poor sound quality.

Therefore, it is hoped to provide a piezoelectric acoustic output device to improve its sensitivity in the mid- and high-frequency bands, while reducing its vibration mode in the audible range, thereby improving the sound quality of the acoustic output device.

The embodiment of this specification provides an acoustic output device, including: a first vibrating element; a second vibrating element; and a piezoelectric element, wherein the piezoelectric element drives the first vibrating element and the second vibrating element to vibrate in response to an electrical signal, wherein the first vibrating element is connected to the first position of the piezoelectric element, the second vibrating element is connected to the second position of the piezoelectric element at least through a first elastic element, and the second vibrating element is connected to the third position of the piezoelectric element at least through a second elastic element, and in the vibration direction of the second vibrating element, the first elastic coefficient of the first elastic element is different from the second elastic coefficient of the second elastic element.

Additional features will be partially described in the following description and will become apparent to those skilled in the art by reviewing the following content and accompanying drawings, or may be understood by the production or operation of the examples. Features of the present invention can be implemented and obtained by practicing or using various aspects of the methods, tools, and combinations described in the following detailed examples.

100:Acoustic output device

110: First vibration element

120: Second vibration element

130: Piezoelectric components

132: Piezoelectric film

134: Piezoelectric film

136: Substrate

140: First elastic element

142: First elastic rod

150: Second elastic element

152: Second elastic rod

160: Shell structure

170: Fixed structure

182: First connecting piece

184: Second connecting piece

190: Third connecting piece

200:Acoustic output device

400:Acoustic output device

600:Acoustic output device

700:Acoustic output device

The present invention will be further described in the form of exemplary embodiments, which will be described in detail through the accompanying drawings. These embodiments are not restrictive. In these embodiments, the same component symbols represent the same structure, wherein: [Figure 1] is a structural block diagram of an exemplary acoustic output device shown in some embodiments of this specification; [Figure 2] is a structural schematic diagram of an exemplary acoustic output device shown in some embodiments of this specification; [Figure 3] is a frequency response curve diagram of the vibration signal of the exemplary acoustic output device shown in some embodiments of this specification when it is output from the elastic mass end; [Figure 4] is a structural schematic diagram of an exemplary acoustic output device shown in some embodiments of this specification; [Figure 5] is a structural schematic diagram of an exemplary acoustic output device shown in some embodiments of this specification; [Figure 6] is a structural schematic diagram of an exemplary acoustic output device shown in some embodiments of this specification; [Figure 7] is a structural schematic diagram of an exemplary acoustic output device shown in some embodiments of this specification; [Figure 8] is a structural schematic diagram of an exemplary acoustic output device shown in some embodiments of this specification; [Figure 9] is a structural schematic diagram of an exemplary acoustic output device shown in some embodiments of this specification; [Figure 10] is a structural schematic diagram of an exemplary acoustic output device shown in some embodiments of this specification; [Figure 11] is a structural schematic diagram of an exemplary acoustic output device shown in some embodiments of this specification; [Figure 12] is a structural schematic diagram of an exemplary acoustic output device shown in some embodiments of this specification; [Figure 13] is a structural schematic diagram of an exemplary acoustic output device shown in some embodiments of this specification; [Figure 14] is a structural schematic diagram of an exemplary acoustic output device shown in some embodiments of this specification; [Figure 15] is a structural schematic diagram of an exemplary acoustic output device shown in some embodiments of this specification; [Figure 16] is a structural schematic diagram of an exemplary acoustic output device shown in some embodiments of this specification; [Figure 17] is a structural schematic diagram of an exemplary acoustic output device shown in some embodiments of this specification; [Figure 18] is a structural schematic diagram of an exemplary acoustic output device shown in some embodiments of this specification; [Figure 19] is a structural [Figure 5] is a simulation model diagram of an exemplary acoustic output device according to some embodiments of this specification; [Figure 6] is a structural schematic diagram of an exemplary acoustic output device according to some embodiments of this specification; [Figure 7] is a structural schematic diagram of another exemplary acoustic output device according to some embodiments of this specification; [Figure 8] is a frequency response curve diagram of the vibration signal of the exemplary acoustic output device according to some embodiments of this specification when it is output from the elastic mass end.

In order to more clearly explain the technical solutions of the embodiments of this specification, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings described below are only some examples or embodiments of this specification. For those with ordinary knowledge in the relevant technical field, this specification can also be applied to other similar scenarios based on these drawings without making any progressive efforts. Unless it is obvious from the language environment or otherwise explained, the same component symbols in the drawings represent the same structure or operation.

It should be understood that the "system", "device", "unit" and/or "module" used herein is a method for distinguishing different elements, components, parts, parts or assemblies at different levels. However, if other words can achieve the same purpose, the words can be replaced by other expressions.

As shown in this specification and patent application, unless the context clearly indicates an exception, the words "a", "an", "a kind" and/or "the" do not specifically refer to the singular, but may also include the plural. Generally speaking, the terms "include" and "comprise" only indicate the inclusion of clearly identified steps and elements, and these steps and elements do not constitute an exclusive list, and the method or apparatus may also include other steps or elements. The term "based on" means "based at least in part on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one other embodiment".

In the description of this specification, it should be understood that the terms "first", "second", "third", "fourth", etc. are used only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second", "third", "fourth" may explicitly or implicitly include at least one of the features. In the description of this specification, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

In this specification, unless otherwise clearly specified and limited, the terms "connection", "fixation" and the like should be understood in a broad sense. For example, the term "connection" can refer to fixed connection, detachable connection, or integration; it can be mechanical connection or electrical connection; it can be direct connection or indirect connection through an intermediate medium; it can be the internal connection of two components or the interaction relationship between two components, unless otherwise clearly limited. For those with ordinary knowledge in the relevant technical field, the specific meanings of the above terms in this specification can be understood according to the specific circumstances.

The embodiment of this specification provides an acoustic output device, which includes a first vibration element, a second vibration element and a piezoelectric element. The piezoelectric element can drive the first vibration element and the second vibration element to vibrate in response to an electrical signal. The first vibration element is connected to the first position of the piezoelectric element, the second vibration element is connected to the second position of the piezoelectric element at least through the first elastic element, and the second vibration element is connected to the third position of the piezoelectric element at least through the second elastic element. According to the embodiment of this specification, in the vibration direction of the second vibration element, by making the first elastic coefficient of the first elastic element different from the second elastic coefficient of the second elastic element, the sensitivity of the acoustic output device in the mid-high frequency band (for example, 1kHz~10kHz) can be improved, which is beneficial to the application of the acoustic output device in special scenarios.

The acoustic output device provided in the embodiment of this specification will be described in detail below with reference to the attached figures.

FIG1 is a block diagram of an exemplary acoustic output device according to some embodiments of this specification. In some embodiments, the acoustic output device 100 may be a bone conduction acoustic output device, an air conduction acoustic output device, or a bone-air conduction combined acoustic output device. In some embodiments, the acoustic output device 100 may include audio, headphones, glasses, hearing aids, augmented reality (AR) equipment, virtual reality (VR) equipment, etc., or other devices with audio playback functions (such as mobile phones, computers, etc.). In some embodiments, the acoustic output device 100 may be an open acoustic output device. As shown in FIG1 , the acoustic output device 100 may include a first vibration element 110, a second vibration element 120, a piezoelectric element 130, a first elastic element 140, and a second elastic element 150.

The first vibration element 110 and the second vibration element 120 can both be mass blocks with a certain mass. In some embodiments, the first vibration element 110 and/or the second vibration element 120 can include a vibration plate, a diaphragm, etc., so that the acoustic output device 100 outputs vibration through the first vibration element 110 and/or the second vibration element 120. In some embodiments, the material of the mass block can include but is not limited to metals (e.g., copper, iron, magnesium, aluminum, tungsten, etc.), alloys (aluminum alloys, titanium alloys, tungsten alloys, etc.), polymer materials (e.g., polytetrafluoroethylene, silicone rubber, etc.), and other materials. In some embodiments, the material of the first vibration element 110 and the material of the second vibration element 120 can be the same or different.

The piezoelectric element 130 may be an electric energy conversion device that can convert electric energy into mechanical energy using the reverse piezoelectric effect. In some embodiments, the piezoelectric element 130 may be composed of materials having a piezoelectric effect, such as piezoelectric ceramics, piezoelectric quartz, piezoelectric crystals, and piezoelectric polymers. In some embodiments, the piezoelectric element 130 may be in the shape of a sheet, a ring, a diamond, a rectangular parallelepiped, a column, a sphere, or any combination thereof, or may be other irregular shapes. In some embodiments, the piezoelectric element 130 may include a beam structure (e.g., a strip structure having a certain width) (as shown in FIGS. 2 and 4). As an example, the beam structure may include two layers of piezoelectric sheets and a substrate, and the two layers of piezoelectric sheets are attached to opposite sides of the substrate, respectively. The substrate can generate vibrations (for example, vibrate in a direction perpendicular to the substrate surface) according to the expansion and contraction of the two layers of piezoelectric sheets along the length extension direction of the piezoelectric beam structure. In this specification, the length extension direction of the beam structure of the piezoelectric element 130 may refer to a direction in which the characteristic dimension of the beam structure in the extension direction is more than 1 times the characteristic dimension of the beam structure in any other direction. In some embodiments, the beam structure may include a straight beam structure, a curved beam structure, etc. In this specification, a straight beam structure will be used as an example for explanation, which is not intended to limit the scope of this specification. For more descriptions of the beam structure, please refer to Figure 2 and its description.

The first vibration element 110 can be physically connected (e.g., glued, clamped, screwed, welded, etc.) to the first position of the piezoelectric element 130. The second vibration element 120 can be connected to the second position of the piezoelectric element 130 at least through the first elastic element 140, and connected to the third position of the piezoelectric element 130 at least through the second elastic element 150. In other words, one end of the first elastic element 140 can be connected to the second position of the piezoelectric element 130, one end of the second elastic element 150 can be connected to the third position of the piezoelectric element 130, and the other ends of the first elastic element 140 and the second elastic element 150 are simultaneously connected to the second vibration element 120. The piezoelectric element 130 can be deformed under the action of a driving voltage (or an excitation signal), thereby generating vibration. The first vibration element 110 and the second vibration element 120 can generate vibrations in response to the vibrations of the piezoelectric element 130, respectively. Specifically, the piezoelectric element 130 can directly transmit the vibrations to the first vibration element 110, and the vibrations of the piezoelectric element 130 can be transmitted to the second vibration element 120 through the first elastic element 140 and the second elastic element 150. In other words, the second vibration element 120 can simultaneously receive the vibrations transmitted by the first elastic element 140 and the second elastic element 150. In the embodiment of this specification, the first vibration element 110 directly connected to the piezoelectric element 130 can be referred to as a mass end, and the second vibration element 120 connected to the piezoelectric element 130 through the first elastic element 140 and the second elastic element 150 can be referred to as an elastic mass end.

In some embodiments, the first elastic element 140 and the second elastic element 150 may be connected to the same or different positions of the second vibration element 120. For example, as shown in FIG5 , the first elastic element 140 and the second elastic element 150 may be simultaneously connected to the middle position A of the second vibration element 120. For another example, as shown in FIG5 , the first elastic element 140 may be connected to the position A' of the second vibration element 120, and the second elastic element 150 may be connected to the position A" of the second vibration element 120.

In some embodiments, when the piezoelectric element 130 includes a beam-shaped structure, the first position may be located at the center of the length extension direction of the beam-shaped structure. The second position and the third position may be located at two ends of the length extension direction of the beam-shaped structure, respectively. In some embodiments, the second position and the third position may be located at any two positions symmetrical or asymmetrical about the center of the beam-shaped structure, respectively, in the length extension direction of the beam-shaped structure. In some embodiments, the piezoelectric element 130 may also include regular shapes such as circles, triangles, pentagons, hexagons, or other irregular shapes. For example, when the shape of the piezoelectric element 130 is a circle, the first position may be the center of the circle, and the second position and the third position may be located at two radial ends of the circle, respectively. For another example, when the shape of the piezoelectric element 130 is an irregular shape, the first position may be the center of mass of the irregular shape, and the second position and the third position may be two positions on the irregular shape (e.g., the edge) that are symmetrical or asymmetrical about the center of mass. In this specification, for ease of description, a piezoelectric element with a beam structure is used as an example of the piezoelectric element 130.

In some embodiments, the first elastic element 140 and the second elastic element 150 can be directly connected to the second position and the third position of the piezoelectric element 130 (by gluing, welding, clamping, etc.). In some embodiments, the acoustic output device 100 may further include a first connector and a second connector (not shown). The second vibration element 120 and the first elastic element 140 can be connected to the second position of the piezoelectric element 130 through the first connector, and the second vibration element 120 and the second elastic element 150 can be connected to the third position of the piezoelectric element 130 through the second connector. For example, as shown in FIG. 4 , the second vibration element 120 and the first elastic element 140 can be connected to the end of the piezoelectric element 130 (i.e., the second position) through the first connector 182, and the second vibration element 120 and the second elastic element 150 can be connected to the other end of the piezoelectric element 130 (i.e., the third position) through the second connector 184.

In the vibration direction of the second vibration element 120, the first elastic coefficient of the first elastic element 140 and the second elastic coefficient of the second elastic element 150 may be different. In some embodiments, the material of the first elastic element 140 and/or the second elastic element 150 may be any material capable of transmitting vibration. For example, the material of the first elastic element 140 and/or the second elastic element 150 may be silicone, foam, plastic, rubber, metal, etc., or any combination thereof. In some embodiments, the first elastic element 140 and/or the second elastic element 150 may be a component with good elasticity (i.e., prone to elastic deformation). For example, the first elastic element 140 and/or the second elastic element 150 may include a spring (e.g., an air spring, a mechanical spring, an electromagnetic spring, etc.), a vibration transmitting sheet, a spring sheet, a substrate, etc., or any combination thereof. In some embodiments, the first elastic element 140 and/or the second elastic element 150 may include one or more elastic rods (e.g., the first elastic rod 142 and/or the second elastic rod 152 shown in FIG. 4 ). The second vibration element 120 may be connected to one or more elastic rods to achieve connection with the second position and/or the third position of the piezoelectric element 130. In some embodiments, the length, material, or number, length, material, angle, etc. of the first elastic element 140 and/or the second elastic element 150 or any combination thereof can be adjusted to make the first elastic coefficient of the first elastic element 140 and the second elastic coefficient of the second elastic element 150 different. For more descriptions of the first elastic element 140 and/or the second elastic element 150, please refer to other places in this specification (for example, Figure 2, Figure 4 and their descriptions), which will not be repeated here.

In some embodiments, the vibration of the first vibration element 110 and the second vibration element 120 can generate two resonance peaks within the frequency range audible to the human ear (e.g., 20 Hz to 20 kHz). Specifically, the resonance of the second vibration element 120 and the first elastic element 140 and the second elastic element 150 can generate a first resonance peak with a lower frequency (e.g., 50 Hz to 2000 Hz) among the two resonance peaks (e.g., the resonance peak in the dotted line M in FIG. 3 ), and the resonance of the piezoelectric element 130 and the first vibration element 110 can generate a second resonance peak with a higher frequency (e.g., 1 kHz to 10 kHz) among the two resonance peaks (e.g., the resonance peak in the dotted line N in FIG. 3 ). The frequency corresponding to the second harmonic peak (also called the second harmonic frequency) may be higher than the frequency corresponding to the first harmonic peak (also called the first harmonic frequency).

In some embodiments, the frequency range of the first harmonic frequency corresponding to the first harmonic peak and/or the second harmonic frequency corresponding to the second harmonic peak can be adjusted by adjusting the mass of the second vibration element 120, the elastic coefficient of the first elastic element 140 and/or the second elastic element 150 (for example, the first elastic coefficient and/or the second elastic coefficient). In some embodiments, the frequency range of the first harmonic frequency can be 50Hz~1500Hz. In some embodiments, the frequency range of the first harmonic frequency can be 100Hz~1000Hz. In some embodiments, the frequency range of the first harmonic frequency can be 150Hz~500Hz.

In some embodiments, the frequency range of the second resonant frequency corresponding to the second resonant peak can be adjusted by adjusting the performance parameters of the piezoelectric element 130. In some embodiments, the performance parameters of the piezoelectric element 130 may include geometric parameters, material parameters, etc. Exemplary geometric parameters may include thickness, length, etc. Exemplary material parameters may include elastic modulus, density, etc. In some embodiments, the second resonant frequency may be the natural frequency of the piezoelectric element 130. In some embodiments, the frequency range of the second resonant frequency may be 1kHz~10kHz. In some embodiments, the frequency range of the second resonant frequency may be 1kHz~8kHz. In some embodiments, the frequency range of the second resonant frequency may be 2kHz~5kHz. In some embodiments, the frequency range of the second resonant frequency can be 3kHz~4kHz.

In some embodiments, damping may be added to one or more elements in the acoustic output device 100, thereby making the resonance peak of the acoustic output device 100 smoother. For example, a material with a large damping effect (e.g., silicone, rubber, foam, etc.) may be used to prepare the first elastic element 140 and/or the second elastic element 150. For another example, a damping material may be coated on the piezoelectric element 130. For another example, a damping material or electromagnetic damping may be coated on the first vibration element 110 and/or the second vibration element 120.

In some embodiments, the vibration of the piezoelectric element 130 (or the acoustic output device 100) can be transmitted to the user by bone conduction through the first vibration element 110 and/or the second vibration element 120. For example, the second vibration element 120 can be directly in contact with the skin of the user's head, and the vibration of the piezoelectric element 130 is transmitted to the bones and/or muscles of the user's face through the second vibration element 120, and finally transmitted to the user's ears. For another example, the second vibration element 120 may not be in direct contact with the human body, and the vibration of the piezoelectric element 130 can be transmitted to the outer shell of the acoustic output device through the second vibration element 120, and then transmitted from the outer shell to the bones and/or muscles of the user's face, and finally transmitted to the user's ears. In some embodiments, the vibration of the piezoelectric element 130 can also be transmitted to the user through the first vibration element 110 and/or the second vibration element 120 in an air conduction manner. For example, the second vibration element 120 can directly drive the air around it to vibrate, thereby transmitting it to the user's ear through the air. For another example, the second vibration element 120 can be further connected to the diaphragm, and the vibration of the second vibration element 120 can be transmitted to the diaphragm, and then the diaphragm drives the air to vibrate, thereby transmitting it to the user's ear through the air.

In some embodiments, the acoustic output device 100 may further include a housing structure 160. The housing structure 160 may be configured to carry other components of the acoustic output device 100 (e.g., the first vibration element 110, the second vibration element 120, the piezoelectric element 130, the first elastic element 140, or the second elastic element 150, etc.). In some embodiments, the housing structure 160 may be a closed or semi-closed structure with a hollow interior, and other components of the acoustic output device 100 are located inside or on the housing structure. In some embodiments, the housing structure 160 may be a three-dimensional structure of a regular or irregular shape such as a cuboid, a cylinder, or a frustum. When a user wears the acoustic output device 100, the housing structure 160 may be located near the user's ear. For example, the housing structure 160 may be located around the user's auricle (e.g., the front side or the back side). For another example, the housing structure 160 may be located on the user's ear but does not block or cover the user's ear canal. In some embodiments, the acoustic output device 100 may be a bone conduction earphone, and at least one side of the housing structure 160 may be in contact with the user's skin. The acoustic driver element in the bone conduction earphone (e.g., a combination of the piezoelectric element 130, the first vibration element 110, the first elastic element 140, the second elastic element 150, and the second vibration element 120) converts the audio signal into mechanical vibration, which can be transmitted to the user's auditory nerve through the housing structure 160 and the user's bones. In some embodiments, the acoustic output device 100 may be an air conduction earphone, and at least one side of the housing structure 160 may or may not be in contact with the user's skin. The side wall of the housing structure 160 includes at least one sound-conducting hole, and the acoustic driver element in the air conduction earphone converts the audio signal into air-conducted sound, which can be radiated toward the user's ear through the sound-conducting hole.

In some embodiments, the acoustic output device 100 may include a fixing structure 170. The fixing structure 170 may be configured to fix the acoustic output device 100 near the user's ear. In some embodiments, the fixing structure 170 may be physically connected to the housing structure 160 of the acoustic output device 100 (e.g., glued, snapped, screwed, etc.). In some embodiments, the housing structure 160 of the acoustic output device 100 may be a part of the fixing structure 170. In some embodiments, the fixing structure 170 may include an ear hook, a back hook, an elastic band, a temple of glasses, etc., so that the acoustic output device 100 can be better fixed near the user's ear to prevent the user from falling off during use. For example, the fixing structure 170 may be an ear hook, and the ear hook may be configured to be worn around the ear area. In some embodiments, the ear hook may be a continuous hook and may be elastically stretched to be worn on the user's ear. The ear hook may also apply pressure to the user's auricle so that the acoustic output device 100 is firmly fixed to a specific position of the user's ear or head. In some embodiments, the ear hook may be a discontinuous strip. For example, the ear hook may include a rigid portion and a flexible portion. The rigid portion may be made of a rigid material (e.g., plastic or metal), and the rigid portion may be fixed to the housing structure 160 of the acoustic output device 100 by physical connection (e.g., snap connection, thread connection, etc.). The flexible portion may be made of an elastic material (e.g., cloth, composite material, or/and neoprene). For another example, the fixing structure 170 can be a neck strap configured to be worn around the neck/shoulder area. For another example, the fixing structure 170 can be a glasses leg, which is a part of the glasses and is mounted on the user's ears.

It should be noted that the above description of FIG. 1 is provided for illustrative purposes only and is not intended to limit the scope of the present invention. For those skilled in the art, various changes and modifications can be made according to the teachings of the present invention. For example, in some embodiments, the acoustic output device 100 may further include one or more components (e.g., a signal transceiver, an interactive module, a battery, etc.). In some embodiments, one or more components in the acoustic output device 100 may be replaced by other components that can achieve similar functions. For example, the acoustic output device 100 may not include the fixing structure 170, and the housing structure 160 or a portion thereof may be a housing structure having a shape that fits the human ear (e.g., a ring shape, an ellipse shape, a polygon (regular or irregular), a U shape, a V shape, a semicircle shape), so that the housing structure can be hung near the user's ear. These changes and modifications will not deviate from the scope of the present invention.

FIG2 is a schematic diagram of the structure of an exemplary acoustic output device according to some embodiments of this specification. As shown in FIG2, the acoustic output device 200 may include a first vibration element 110, a second vibration element 120, a piezoelectric element 130, a first elastic element 140, and a second elastic element 150. The piezoelectric element 130 may include a beam structure. In some embodiments, the length of the piezoelectric element 130 (i.e., the dimension along the direction in which the length of the beam structure extends) may be in the range of 3 mm to 30 mm.

In some embodiments, as shown in FIG. 2 , the piezoelectric element 130 may include two piezoelectric sheets (i.e., piezoelectric sheet 132 and piezoelectric sheet 134) and a substrate 136. The substrate 136 may be configured as a carrier for carrying components and an element that deforms in response to vibration. In some embodiments, the material of the substrate 136 may include one or more combinations of metals (such as copper foil, steel, etc.), phenolic resin, cross-linked polystyrene, etc. In some embodiments, the shape of the substrate 136 may be determined according to the shape of the piezoelectric element 130. For example, if the piezoelectric element 130 is a piezoelectric cantilever beam, the substrate 136 may be correspondingly set to a long strip shape. For another example, if the piezoelectric element 130 is a piezoelectric film, the substrate 136 may be correspondingly set to a plate or sheet shape.

The piezoelectric sheet 132 and the piezoelectric sheet 134 may be elements that provide piezoelectric effect and/or inverse piezoelectric effect. In some embodiments, the piezoelectric sheet may cover one or more surfaces of the substrate 136, and deform under the action of the driving voltage to drive the substrate 136 to deform, thereby realizing the output vibration of the piezoelectric element 130. For example, along the thickness direction of the piezoelectric element 130 (as shown by the arrow ZZ' in the figure), the piezoelectric sheet 132 and the piezoelectric sheet 134 are respectively attached to the opposite sides of the substrate 136, and the substrate 136 may generate vibration according to the expansion and contraction of the piezoelectric sheet 132 and the piezoelectric sheet 134 along the length extension direction of the piezoelectric element 130 (as shown by the arrow XX' in the figure). Specifically, when power is applied along the thickness direction ZZ' of the piezoelectric element 130, the piezoelectric sheet on one side of the substrate 136 can shrink along its length extension direction, and the piezoelectric sheet on the other side of the substrate 136 can stretch along its length extension direction, thereby driving the substrate 136 to bend and vibrate in a direction perpendicular to the surface of the substrate 136 (i.e., the thickness direction ZZ').

In some embodiments, the material of the piezoelectric sheet 132 and/or 134 may include piezoelectric ceramics, piezoelectric quartz, piezoelectric crystals, piezoelectric polymers, etc., or any combination thereof. Exemplary piezoelectric crystals may include crystal, pyrophyllite, borate, pyrotechnics, ruthenium, GaAs, barium titanate and its derivative structure crystals, KH ₂ PO ₄ , NaKC ₄ H ₄ O ₆ . 4H ₂ O (sodium potassium tartrate), etc. Exemplary piezoelectric ceramic materials may include barium titanate (BT), lead zirconate titanate (PZT), barium lithium lead niobate (PBLN), modified lead titanate (PT), aluminum nitride (AIN), zinc oxide (ZnO), etc., or any combination thereof. Exemplary piezoelectric polymer materials may include polyvinylidene fluoride (PVDF), among others.

The first vibration element 110 can be connected to the first position of the piezoelectric element 130. The second vibration element 120 can be connected to the second position of the piezoelectric element 130 through the first elastic element 140, and connected to the third position of the piezoelectric element 130 through the second elastic element 150. It should be noted that when the piezoelectric element 130 with a beam-like structure vibrates, the amplitude of the end thereof is larger, so when the first position, the second position and/or the third position are located at the end of the beam-like structure, the output response sensitivity of the corresponding vibration element end is higher and the sound quality is better.

In some embodiments, the first position may be located at the center of the length extension direction of the beam structure, the second position may be located at one end of the length extension direction of the beam structure, and the third position may be located at the other end of the length extension direction of the beam structure, thereby realizing a symmetrical structure of the piezoelectric element 130 with the surface passing through the first position and perpendicular to the length extension direction of the beam structure as the symmetrical surface. For example, as shown in FIG2 , the first vibration element 110 may be attached to the middle position (i.e., the first position) of the first surface of the piezoelectric element 130 in the length extension direction, the first elastic element 140 may be attached to one end of the second surface opposite to the first surface in the length extension direction of the piezoelectric element 130 (i.e., the second position), and the second elastic element 150 may be attached to the other end of the second surface opposite to the first surface in the length extension direction of the piezoelectric element 130 (i.e., the third position). In some embodiments, the piezoelectric element 130 may include two sub-piezoelectric elements. One end of each sub-piezoelectric element may be connected to the first vibration element 110. The other end of each sub-piezoelectric element may be connected to the second vibration element 120 through the first elastic element 140 and the second elastic element 150, respectively. In some embodiments, the two sub-piezoelectric elements may be on a straight line. The two sub-piezoelectric elements may be arranged symmetrically with respect to a plane passing through the center of the first vibration element 110 and perpendicular to the length extension direction of the beam structure. In this case, the center of the first vibration element 110 may be regarded as the center position of the piezoelectric element composed of the two sub-piezoelectric elements. The first vibration element 110 is connected at the center position of the piezoelectric element, i.e., the first position.

In some embodiments, the acoustic output device 200 may further include one or more connectors (not shown), and two components of the acoustic output device 200 may be connected via the connector. For example, the second vibration element 120 and the first elastic element 140 may be connected to the second position of the piezoelectric element 130 via the connector. For another example, the second vibration element 120 and the second elastic element 150 may be connected to the third position of the piezoelectric element 130 via the connector. The connector may be disposed at the second position (or the third position) of the piezoelectric element 130, one end of the first elastic element 140 (or the second elastic element 150) may be connected to the connector, and the other end of the first elastic element 140 (or the second elastic element 150) may be connected to the second vibration element 120. The arrangement of the connector can make the vibration of the piezoelectric element 130 at the second position or the third position be transmitted to the first elastic element 140 or the second elastic element 150 and the second vibration element 120, and also make the structure of the first elastic element 140 and/or the second elastic element 150 more flexible. For example, as shown in FIG2 , the second vibration element 120 can be a vibration plate having the same shape as the piezoelectric element 130. The vibration plate and the piezoelectric element 130 can be arranged opposite to each other. The first elastic element 140 and/or the second elastic element 150 can be a spring (e.g., a mechanical spring, an electromagnetic spring, etc.), or a rod-shaped object made of other materials with a smaller elastic coefficient. The first elastic element 140 and/or the second elastic element 150 may be arranged vertically between the second vibration element 120 and the piezoelectric element 130. In this case, the first elastic element 140 may have a first elastic coefficient in the vibration direction of the second vibration element 120, and the second elastic element 150 may have a second elastic coefficient in the vibration direction of the second vibration element 120. For another example, as shown in FIG. 4 , the first elastic element 140 and/or the second elastic element 150 may include a plurality of elastic rods (e.g., the first elastic rod 142 or the second elastic rod 152). The elastic rod may be connected to the piezoelectric element 130 via a first connector 182 and a second connector 184. The elastic rod may be connected between the piezoelectric element 130 and the second vibration element 120 in a manner that is inclined or parallel to the piezoelectric element 130. In this case, the first elastic rod may have a first elastic coefficient in the vibration direction of the second vibration element 120, and the first elastic rod may also have a third elastic coefficient in the vibration direction perpendicular to the second vibration element 120, the second elastic rod may have a second elastic coefficient in the vibration direction of the second vibration element 120, and the second elastic rod may also have a fourth elastic coefficient in the vibration direction perpendicular to the second vibration element 120. For more descriptions of the elastic rod, please refer to FIG. 4 and its description, which will not be repeated here.

The first elastic coefficient of the first elastic element 140 and the second elastic coefficient of the second elastic element 150 may be different. In some embodiments, the difference between the first elastic coefficient of the first elastic element 140 and the second elastic coefficient of the second elastic element 150 may affect the frequency response curve of the acoustic output device 200 (as shown in FIG. 3 ). In some embodiments, the second elastic coefficient may be greater than the first elastic coefficient. The ratio of the second elastic coefficient to the first elastic coefficient may be greater than 10. In some embodiments, in order to ensure that the acoustic output device 200 has a high sensitivity in the range of 1.5kHz to 3kHz and has a flat frequency response curve, the ratio of the second elastic coefficient to the first elastic coefficient may be in the range of 10 to 50. In some embodiments, in order to ensure that the acoustic output device 200 has a high sensitivity in the range of 2.5kHz to 4kHz and has a flat frequency response curve, the ratio of the second elastic coefficient to the first elastic coefficient may be in the range of 50 to 100. In some embodiments, in order to ensure that the acoustic output device 200 has a high sensitivity in the range of 3kHz to 5kHz and has a flat frequency response curve, the ratio of the second elastic coefficient to the first elastic coefficient may be in the range of 100 to 1000. In some embodiments, the second elastic coefficient may be much larger than the first elastic coefficient. For example, the first elastic element 140 arranged as shown in FIG2 may be a spring, and the second elastic element 150 may be a rod made of a material with a large elastic modulus (e.g., metal). In other words, the second vibration element 120 may be rigidly connected to the piezoelectric element 130 through the rod, rather than being elastically connected to the piezoelectric element 130 through a spring.

FIG3 is a frequency response curve diagram of a vibration signal of an exemplary acoustic output device according to some embodiments of the present specification when the vibration signal is output from the elastic mass end. As shown in FIG3, curve L31 represents the frequency response curve of the acoustic output device (e.g., acoustic output device 200) when the first elastic coefficient ks1 of the first elastic element and the second elastic coefficient ks2 of the second elastic element are the same. Curve L32 represents the frequency response curve of the acoustic output device when the ratio of the second elastic coefficient ks2 of the second elastic element to the first elastic coefficient ks1 of the first elastic element is 10, and the vibration signal is output from the elastic mass end. Curve L33 represents the frequency response curve of the acoustic output device output by the elastic mass end when the ratio of the second elastic coefficient ks2 of the second elastic element to the first elastic coefficient ks1 of the first elastic element is 100. Curve L34 represents the frequency response curve of the acoustic output device output by the elastic mass end when the ratio of the second elastic coefficient ks2 of the second elastic element to the first elastic coefficient ks1 of the first elastic element is 1000. Curve L35 represents the frequency response curve of the acoustic output device output by the elastic mass end when the ratio of the second elastic coefficient ks2 of the second elastic element to the first elastic coefficient ks1 of the first elastic element is 10000. As an example, as shown in Figure 3, the first elastic coefficient ks1 of the first elastic element corresponding to each frequency response curve is the same and is 666.2N/m.

As shown in FIG3 , curves L31, L32, L33, L34 and L35 all have two resonance peaks in the range of 100 Hz to 5000 Hz (which is within the audible range of the human ear). The first resonance peak in the virtual loop M can be generated by the resonance of the second vibration element 120, the first elastic element 140 and the second elastic element 150. The second resonance peak in the virtual loop N can be generated by the resonance of the first vibration element 110 and the piezoelectric element 130. As can be seen from FIG3 , when the first elastic coefficient ks1 of the first elastic element 140 is equal to the second elastic coefficient ks2 of the second elastic element 150 (corresponding to curve L31), the curve between the first resonance peak and the second resonance peak is flat and has no peaks and valleys, but its sensitivity is relatively low. Keep the first elastic coefficient ks1 unchanged and increase the second elastic coefficient ks2. In other words, the acoustic output device 200 changes from an elastically symmetric acoustic output device (corresponding to curve L31) to an elastically asymmetric acoustic output device (e.g., corresponding to curve L32). The first resonant frequency corresponding to the first resonant peak of the acoustic output device 200 (the resonant peak in the dotted loop M) increases slightly, and then a resonant valley (i.e., the resonant valley in the dotted loop O) is generated after the first resonant peak.

As the second elastic coefficient ks2 further increases (corresponding to curves L32 to L35), the position of the first resonance peak remains almost unchanged, and the frequency corresponding to the resonance valley after the first resonance peak hardly changes with the increase of the second elastic coefficient ks2. Therefore, the position of the resonance valley is determined by the elastic element with a smaller elastic coefficient. As the second elastic coefficient ks2 increases, the second resonance peak (i.e., the resonance peak in the virtual coil N) gradually moves to high frequencies, and the frequency response amplitude after the second resonance peak is significantly improved. In other words, the acoustic output device 200 has a higher sensitivity in the mid-high frequency band (e.g., 1kHz~10kHz). When the second elastic coefficient ks2 increases to 1000 times the first elastic coefficient ks1, the frequency response curve of the acoustic output device 200 remains basically unchanged as the second elastic coefficient ks2 continues to increase (for example, as shown by curves L34 and L35).

In summary, when the second elastic coefficient ks2 is different from the first elastic coefficient ks1, the acoustic output device 200 has a higher sensitivity in the mid-high frequency band. As the difference between the second elastic coefficient ks2 and the first elastic coefficient ks1 increases, the sensitivity of the acoustic output device 200 in the mid-high frequency band increases. In some embodiments, when the difference between the second elastic coefficient ks2 and the first elastic coefficient ks1 exceeds a certain value (for example, the ratio between the second elastic coefficient ks2 and the first elastic coefficient ks1 is greater than 1000 times), the frequency response of the acoustic output device 200 in the mid-high frequency band is basically unchanged, that is, the sensitivity of the acoustic output device 200 in the mid-high frequency band no longer continues to increase.

FIG. 4 is a schematic diagram of the structure of an exemplary acoustic output device according to some embodiments of the present specification. FIG. 5 is a simulation model diagram of an exemplary acoustic output device according to some embodiments of the present specification. As shown in FIG. 4 , the acoustic output device 400 may have a structure similar to that of the acoustic output device 200. For example, the acoustic output device 400 may include a first vibration element 110, a second vibration element 120, a piezoelectric element 130, a first elastic element 140, and a second elastic element 150. For another example, the piezoelectric element 130 may include a beam structure. The first vibration element 110 may be connected to the center position (i.e., the first position) of the length extension direction of the beam structure. The second vibration element 120 may be connected to the two ends (i.e., the second position and the third position) of the length extension direction of the beam structure through the first elastic element 140 and the second elastic element 150. In this specification, for the convenience of description, the first position is taken as the center position of the beam structure, and the second position and the third position are taken as the two ends of the length extension direction of the beam structure as examples.

In some embodiments, the acoustic output device 400 may further include a first connector 182 and a second connector 184. The second vibration element 120 and the first elastic element 140 may be connected to the second position of the piezoelectric element 130 via the first connector 182. The first connector 182 may be disposed at the second position of the piezoelectric element 130, one end of the first elastic element 140 may be connected to the first connector 182, and the other end of the first elastic element 140 may be connected to the second vibration element 120. Similarly, the second vibration element 120 and the second elastic element 150 may be connected to the third position of the piezoelectric element 130 via the second connector 184. The second connecting member 184 can be disposed at the third position of the piezoelectric element 130, one end of the second elastic element 150 can be connected to the second connecting member 184, and the other end of the second elastic element 150 can be connected to the second vibration element 120.

In some embodiments, at least one of the first elastic element 140 and the second elastic element 150 may be arranged in a manner inclined or parallel to the piezoelectric element 130. For example, as shown in FIG4 , the planes where the first elastic element 140 and the second elastic element 150 are located may be parallel to the surface of the piezoelectric element 130 by using the first connector 182 and the second connector 184. In this case, the elastic element arranged in a manner inclined or parallel to the piezoelectric element 130 may have elastic coefficient components in the vibration direction of the second vibration element 120 and perpendicular to the vibration direction of the second vibration element 120. Specifically, as shown in FIG5 , the first elastic element 140 (not shown) has a first elastic coefficient along the direction ZZ’ perpendicular to the piezoelectric element 130 (or along the vibration direction of the second vibration element 120), and the first elastic element 140 has a third elastic coefficient along the direction XX’ parallel to the length of the piezoelectric element 130. The second elastic element 150 (not shown) has a second elastic coefficient along the direction ZZ’ perpendicular to the piezoelectric element 130 (or along the vibration direction of the second vibration element 120), and the second elastic element 150 has a fourth elastic coefficient along the direction XX’ parallel to the length of the piezoelectric element 130.

In some embodiments, when the first elastic element 140 transmits vibration, the first elastic coefficient may affect the displacement output of the first elastic element 140 in the ZZ' direction, and the third elastic coefficient may affect the displacement output of the first elastic element 140 in the XX' direction. Since the displacement output of the first elastic element 140 in the XX' direction may cause the two ends of the first elastic element 140 (e.g., elastic rod) to be squeezed and deformed, the elastic deformation along the direction XX' parallel to the length of the piezoelectric element 130 can generate a displacement output in the direction ZZ' perpendicular to the piezoelectric element 130. In other words, the third elastic coefficient can affect the deformation ability of the first elastic element 140 in the ZZ’ direction, thereby affecting the vibration output of the second vibration element 120 connected to the first elastic element 140. Similarly, when the second elastic element 150 transmits vibration, the displacement output of the second elastic element 150 in the XX’ direction may cause the two ends of the second elastic element 150 to be squeezed and deformed, so that the elastic deformation along the direction XX’ parallel to the length of the piezoelectric element 130 can generate a displacement output in the direction ZZ’ perpendicular to the piezoelectric element 130. In other words, the fourth elastic coefficient can affect the deformation ability of the second elastic element 150 in the ZZ' direction, thereby affecting the vibration output of the second vibration element 120 connected to the second elastic element 150. In some embodiments, the smaller the third elastic coefficient (or the fourth elastic coefficient), the greater the contribution of the third elastic coefficient (or the fourth elastic coefficient) to the vibration transmission in the ZZ' direction.

In order to ensure that the acoustic output device 400 has good sensitivity in the middle and high frequency band (for example, 1kHz~10kHz) (as shown in FIG8), in the vibration direction of the second vibration element 120 (or the piezoelectric element 130), the first elastic coefficient of the first elastic element 140 may be different from the second elastic coefficient of the second elastic element 150. For example, the second elastic coefficient may be greater than or less than the first elastic coefficient. In this specification, for the convenience of description, the second elastic coefficient is greater than the first elastic coefficient as an example. It should be noted that when the acoustic output device 400 vibrates, since the second elastic coefficient is greater than the first elastic coefficient, the second vibration element 120 will vibrate in a direction perpendicular to the surface of the piezoelectric element 130 while tilting and swinging toward the first elastic element 140 or the second elastic element 150.

In some embodiments, the influence of the third elastic coefficient of the first elastic element 140 on the vibration output of the second vibration element 120 in the direction ZZ' perpendicular to the piezoelectric element 130 and the influence of the fourth elastic coefficient of the second elastic element 150 on the vibration output of the second vibration element 120 in the direction ZZ' perpendicular to the piezoelectric element 130 can be further adjusted to change the frequency response performance of the acoustic output device 400. In some embodiments, the third elastic coefficient of the first elastic element 140 and the fourth elastic coefficient of the second elastic element 150 can be equal or different. In some embodiments, the ratio between the third elastic coefficient and the first elastic coefficient of the first elastic element 140, and/or the ratio between the fourth elastic coefficient and the second elastic coefficient of the second elastic element 150 may be greater than 1×10 ⁴ . In some embodiments, the ratio between the third elastic coefficient and the first elastic coefficient of the first elastic element 140, and/or the ratio between the fourth elastic coefficient and the second elastic coefficient of the second elastic element 150 may be greater than 1×10 ⁵ . In some embodiments, the ratio between the third elastic coefficient and the first elastic coefficient of the first elastic element 140, and/or the ratio between the fourth elastic coefficient and the second elastic coefficient of the second elastic element 150 may be greater than 1×10 ⁶ . In some embodiments, a ratio between the third elastic coefficient and the first elastic coefficient of the first elastic element 140 and/or a ratio between the fourth elastic coefficient and the second elastic coefficient of the second elastic element 150 may be greater than 1×10 ⁷ .

In some embodiments, the first elastic element 140 may include one or more first elastic rods 142, and the second elastic element 150 may include one or more second elastic rods 152. In some embodiments, the first elastic rod 142 and/or the second elastic rod 152 may have a cylindrical, rectangular, or any other suitable structure (for example, a concave-convex structure as shown in FIG. 4). In some embodiments, the first elastic coefficient of the first elastic element 140 and the second elastic coefficient of the second elastic element 150 may be different by adjusting the number, length, material, structure, layout pattern, etc. of the first elastic rod 142 and/or the second elastic rod 152 or any combination thereof.

In some embodiments, the number of the first elastic rods 142 and the number of the second elastic rods 152 may be the same or different. For example, when each first elastic rod 142 is the same as each second elastic rod 152 (for example, the material, length, structure, etc. are the same), the number of the first elastic rods 142 and the number of the second elastic rods 152 may be different. At this time, since the number of elastic rods included in the first elastic element 140 and the second elastic element 150 is different, the elastic coefficients of the two in the vibration direction of the second vibration element 120 (i.e., the first elastic coefficient and the second elastic coefficient) are different. For another example, the number of the first elastic rods 142 and the number of the second elastic rods 152 may be the same (for example, 2, 3, 4, etc.), and the first elastic coefficient of the first elastic element 140 and the second elastic coefficient of the second elastic element 150 may be different by making other characteristics (for example, length, material, etc.) of each first elastic rod 142 different from other corresponding characteristics (for example, length, material, etc.) of each second elastic rod 152. As an example, the material of each of the one or more first elastic rods 142 and the material of each of the one or more second elastic rods 152 can be different, so that the first elastic coefficient of the first elastic element 140 and the second elastic coefficient of the second elastic element 150 are different. For example, the material of the first elastic rod 142 can be a material with a smaller elastic modulus (e.g., silicone, foam, plastic, rubber, etc.), and the material of the second elastic rod 152 can be a material with a larger elastic modulus (e.g., metal, alloy, etc.).

In some embodiments, the first elastic coefficient of the first elastic element 140 and the second elastic coefficient of the second elastic element 150 can be made different by changing the layout pattern of the first elastic rods 142 and/or the second elastic rods 152. For example, when each first elastic rod 142 is the same as each second elastic rod 152 (for example, material, length, etc.), and the number of the first elastic rods 142 and the number of the second elastic rods 152 are the same, the first elastic coefficient of the first elastic element 140 and the second elastic coefficient of the second elastic element 150 can be made different by setting the angle between every two adjacent first elastic rods 142 or the angle between every two adjacent second elastic rods 152. For example, in order to make the second elastic coefficient greater than the first elastic coefficient, the angle between every two adjacent second elastic rods 152 can be made smaller than the angle between every two adjacent first elastic rods 142. In some embodiments, in order to minimize unnecessary shaking and offset caused by the asymmetric structure and avoid adverse effects on the output sound quality of the acoustic output device 400, the first elastic rod 142 can be arranged symmetrically with respect to a plane that is perpendicular to the surface of the piezoelectric element 130 and the center of the piezoelectric element 130, and the second elastic rod 152 can also be arranged symmetrically with respect to a plane that is perpendicular to the surface of the piezoelectric element 130 and the center of the piezoelectric element 130.

In some embodiments, the first elastic coefficient of the first elastic element 140 and the second elastic coefficient of the second elastic element 150 may be different by making the lengths of each first elastic rod 142 and each second elastic rod 152 different. It should be noted that in this specification, the length of the first elastic rod 142 may refer to the length of the first elastic rod 142 when it is not affected by external forces (i.e., in a natural state), and the length of the second elastic rod 152 may refer to the length of the second elastic rod 152 when it is not affected by external forces. In some embodiments, the first elastic coefficient of the first elastic element 140 and the second elastic coefficient of the second elastic element 150 may be different by making each first elastic rod 142 and each second elastic rod 152 have different structures. For example, each first elastic rod 142 may have a concave-convex structure, and each second elastic rod 152 may have a cylindrical long rod structure.

FIG6 is a schematic diagram of the structure of an exemplary acoustic output device according to some embodiments of the present specification. FIG7 is a schematic diagram of the structure of another exemplary acoustic output device according to some embodiments of the present specification. As shown in FIG6, the acoustic output device 600 has a similar structure to the acoustic output device 400. The difference between the acoustic output device 600 and the acoustic output device 400 is that in the acoustic output device 600, in addition to the second elastic rod 152, the second elastic element 150 also includes a third connector 190. The second vibration element 120 can be further connected to the third position of the piezoelectric element 130 through the third connector 190.

In some embodiments, the third connecting member 190 may be a component made of any material. The third connecting member 190 and the second elastic rod 152 may together constitute the second elastic element 150. In other words, the elastic coefficient of the second elastic element 150 (e.g., the second elastic coefficient in the vibration direction of the second vibration element 120) is provided by the third connecting member 190 and the second elastic rod 152. In some embodiments, when the second elastic rod 152 has the same configuration as the first elastic rod 142 (e.g., the same structure, length, quantity, material, etc.), the second elastic coefficient of the second elastic element 150 can be made different from the first elastic coefficient of the first elastic element 140 by providing a third connector 190 (which can provide an additional elastic coefficient for the second elastic element 150).

In some embodiments, the difference between the second elastic coefficient of the second elastic element 150 and the first elastic coefficient of the first elastic element 140 can be adjusted by changing the structure and material of the third connector 190, so that the sensitivity of the acoustic output device 600 in different frequency bands can be improved to adapt to more usage scenarios. In some embodiments, the third connector 190 can be in the shape of a sheet, ring, diamond, rectangular, column, sphere, or any combination thereof, or other irregular shapes. In some embodiments, the material of the third connector 190 can be silicone, foam, plastic, rubber, metal, or any combination thereof.

In some embodiments, when the third connector 190 is made of a material with a relatively large elastic modulus (e.g., metal, alloy, etc.), it is equivalent to that the second vibration element 120 and the piezoelectric element 130 are rigidly connected through the third connector 190. In this case, the second elastic rod 152 can be removed. As shown in the acoustic output device 700 in FIG. 7 , the second vibration element 120 can be directly connected to the third position of the piezoelectric element 130 through the third connector 190. At this time, the third connector 190 is the second elastic element 150. In some embodiments, in order to make the second vibration element 120 and the second connector 184 form a rigid connection, the second elastic coefficient of the second elastic element 150 can be greater than 1×10 ⁴ N/m. In some embodiments, in order to form a rigid connection between the second vibration element 120 and the second connector 184, the second elastic coefficient may be greater than 1×10 ⁵ N/m. In some embodiments, in order to form a rigid connection between the second vibration element 120 and the second connector 184, the second elastic coefficient may be greater than 1×10 ⁶ N/m. In some embodiments, in order to form a rigid connection between the second vibration element 120 and the second connector 184, the second elastic coefficient may be greater than 1×10 ⁷ N/m.

In some embodiments, the first elastic element 140 may include a fourth connector (not shown in the figure), and the second vibration element 120 may be further connected to the second position of the piezoelectric element 130 through the fourth connector. In this case, the first elastic coefficient of the first elastic element 140 and the second elastic coefficient of the second elastic element 150 may be different by making the third connector 190 and the fourth connector different (for example, different in structure, material, etc.).

FIG8 is a frequency response curve diagram of a vibration signal of an exemplary acoustic output device according to some embodiments of the present specification when the vibration signal is output from the elastic mass end. As shown in FIG8, curve L81 represents the frequency response curve of the acoustic output device when the first elastic coefficient ks1 of the first elastic element and the second elastic coefficient ks2 of the second elastic element are the same, both being 666.2 N/m, and the third elastic coefficient kh1 of the first elastic element and the fourth elastic coefficient kh2 of the second elastic element are the same, both being 666.2 N/m. Curves L82, L83, and L84 represent the frequency response curves of the acoustic output device (e.g., acoustic output device 400) outputting the vibration signal from the elastic mass end when the first elastic coefficient of the first elastic element is 666.2 N/m, the ratio of the first elastic coefficient ks1 of the first elastic element to the second elastic coefficient ks2 of the second elastic element is 100, the ratio of the third elastic coefficient kh1 of the first elastic element to the first elastic coefficient ks1 is 100, 1000, and 2000, respectively, and the ratio of the fourth elastic coefficient kh2 of the second elastic element to the second elastic coefficient ks2 is 100, 1000, and 2000, respectively.

As shown in FIG8 , curves L81, L82, L83, and L84 all have two resonance peaks in the range of 100 Hz to 5000 Hz (which is within the audible range of human ears). The first resonance peak in the virtual coil Q may be generated by the resonance of the second vibration element 120, the first elastic element 140, and the second elastic element 150. The second resonance peak in the virtual coil P may be generated by the resonance of the first vibration element 110 and the piezoelectric element 130. As can be seen from Figure 8, when the first elastic coefficient ks1 of the first elastic element 140 is equal to the second elastic coefficient ks2 of the second elastic element 150, and the third elastic coefficient kh1 of the first elastic element and the fourth elastic coefficient kh2 of the second elastic element are equal (corresponding curve L81), the curve between the first resonant peak and the second resonant peak is flat and has no peaks and valleys, but its sensitivity is relatively low. Keep the first elastic coefficient ks1 unchanged, increase the second elastic coefficient ks2 to 100 times of ks1, in other words, the acoustic output device 400 changes from an elastically symmetric acoustic output device (corresponding to curve L81) to an elastically asymmetric acoustic output device (for example, corresponding to curves L82, L83, and L84), and the first resonant peak (the resonant peak in the dotted loop Q) of the acoustic output device 400 corresponds to the first resonant frequency increases, and then a resonant valley (i.e., the resonant valley in the dotted loop P) is generated after the first resonant peak.

Furthermore, as shown in curves L82 to L84, since the third elastic coefficient kh1 of the first elastic element and the fourth elastic coefficient kh2 of the second elastic element can affect the vibration output of the second vibration element 120, when the third elastic coefficient kh1 of the first elastic element 140 and the fourth elastic coefficient kh2 of the second elastic element 150 are gradually increased (corresponding to curves L82 to L84), the first harmonic frequency corresponding to the first harmonic peak and the frequency corresponding to the subsequent harmonic valley gradually move toward high frequencies at the same time, the frequency response amplitude before the first harmonic peak increases slightly, and the frequency response amplitude after the second harmonic peak is significantly improved. In other words, the acoustic output device 400 has a higher sensitivity in the mid-high frequency band (e.g., 1kHz~10kHz). When the third elastic coefficient kh1 of the first elastic element 140 increases to 2000 times the first elastic coefficient ks1, and the fourth elastic coefficient kh2 of the second elastic element 150 increases to 2000 times the second elastic coefficient ks2, the first resonance valley after the first resonance peak and the second resonance peak produce a significant canceling effect (corresponding to curve L84), thereby making the frequency response of the corresponding acoustic output device flatter. As the difference between the second elastic coefficient ks2 and the first elastic coefficient ks1 increases, the sensitivity of the acoustic output device 200 in the mid-high frequency band increases. In some embodiments, when the difference between the second elastic coefficient ks2 and the first elastic coefficient ks1 exceeds a certain value (for example, the ratio between the second elastic coefficient ks2 and the first elastic coefficient ks1 is greater than 1000 times), the frequency response of the acoustic output device 200 in the mid-high frequency band is basically unchanged, that is, the sensitivity of the acoustic output device 200 in the mid-high frequency band no longer continues to increase.

In summary, when the second elastic coefficient ks2 is different from the first elastic coefficient ks1, the acoustic output device 400 has a higher sensitivity in the mid-high frequency band. When the first elastic coefficient ks1 and the second elastic coefficient ks2 are kept unchanged, as the third elastic coefficient kh1 and the fourth elastic coefficient kh2 increase, the sensitivity of the acoustic output device 400 in the mid-high frequency band is improved, and the frequency response curve in the mid-high frequency band is flatter. In some embodiments, in order to improve the sensitivity of the acoustic output device 400 in the frequency band of 500 Hz to 3000 Hz, the difference between the second elastic coefficient ks2 and the first elastic coefficient ks1 can be set in the range of 10 ³ N/m to 10 ⁴ N/m, and the third elastic coefficient kh1 can be set in the range of 10 ³ N/m to 10 ⁴ N/m, and the fourth elastic coefficient kh2 can be set in the range of 105 N/m to 106 N/m. In some embodiments, in order to improve the sensitivity of the acoustic output device 400 in the frequency band of 1500 Hz to 7000 Hz and the flatness of the frequency response in this frequency band, the difference between the second elastic coefficient ks2 and the first elastic coefficient ks1 can be set in the range of 10 ³ to 10 ⁴ N/m, and the third elastic coefficient kh1 can be set in the range of 10 ⁵ N/m to 10 ⁷ N/m, and the fourth elastic coefficient kh2 can be set in the range of 10 ⁵ N/m to 10 ⁹ N/m.

The beneficial effects that may be brought about by the embodiments of the present invention include but are not limited to: (1) in an acoustic output device, by directly connecting the first vibration element to the piezoelectric element and simultaneously connecting the second vibration element to the piezoelectric element using elastic elements (first elastic element and second elastic element), the acoustic output device can generate two resonance peaks, and the frequency response curve between the two resonance peaks is relatively straight, thereby improving the sound quality of the acoustic output device; (2) in the vibration direction of the second vibration element, using elastic elements with different elasticities to generate two resonance peaks. The first elastic element and the second elastic element with a coefficient connect the second vibration element to the piezoelectric element, which can improve the sensitivity of the acoustic output device, especially the sensitivity in the mid-high frequency band (for example, 1kHz~10kHz); (3) by adjusting the elastic coefficients of the first elastic element and the second elastic element in the vibration direction perpendicular to the second vibration element, the sensitivity of the acoustic output device in a specific frequency band can be higher and the frequency response curve can be flatter, so that the acoustic output device has better sound quality. It should be noted that different embodiments may produce different beneficial effects. In different embodiments, the beneficial effects that may be produced may be any one or a combination of the above, or any other beneficial effects that may be obtained.

The basic concepts have been described above. Obviously, for those skilled in the art, the above detailed disclosure is only for example and does not constitute a limitation of this specification. Although not explicitly stated here, those skilled in the art may make various modifications, improvements and amendments to this specification. Such modifications, improvements and amendments are suggested in this specification, so such modifications, improvements and amendments still belong to the spirit and scope of the exemplary embodiments of this specification.

600:Acoustic output device

110: First vibration element

120: Second vibration element

130: Piezoelectric components

140: First elastic element

142: First elastic rod

150: Second elastic element

152: Second elastic rod

182: First connecting piece

184: Second connecting piece

190: Third connecting piece

Claims (10)

An acoustic output device includes: a first vibrating element; a second vibrating element; and a piezoelectric element, wherein the piezoelectric element drives the first vibrating element and the second vibrating element to vibrate in response to an electrical signal, wherein the first vibrating element is connected to a first position of the piezoelectric element, the second vibrating element is connected to a second position of the piezoelectric element at least through a first elastic element, and the second vibrating element is connected to a third position of the piezoelectric element at least through a second elastic element, and in the vibration direction of the second vibrating element, the first elastic coefficient of the first elastic element is different from the second elastic coefficient of the second elastic element; the vibration of the piezoelectric element is transmitted to the user through the second vibrating element in a bone conduction manner. As in claim 1, the acoustic output device, wherein the first elastic element includes one or more first elastic rods, the second elastic element includes one or more second elastic rods, and the length or material of at least one of the one or more first elastic rods is different from the length or material of at least one of the one or more second elastic rods. An acoustic output device as claimed in claim 1, wherein the first elastic element includes one or more first elastic rods, the second elastic element includes one or more second elastic rods, and the angle between every two adjacent first elastic rods in the one or more first elastic rods is different from the angle between every two adjacent second elastic rods in the one or more second elastic rods. An acoustic output device as claimed in claim 1, wherein the first elastic element comprises one or more first elastic rods, the second elastic element comprises one or more second elastic rods, each of the one or more first elastic rods is the same as each of the one or more second elastic rods, and the number of the first elastic rods is different from the number of the second elastic rods. As in claim 1, the acoustic output device, wherein the first elastic element includes one or more first elastic rods, the second elastic element includes one or more second elastic rods and a third connecting member, and the second vibration element is further connected to the third position of the piezoelectric element at least through the third connecting member. As in claim 1, the acoustic output device, wherein the first elastic element includes one or more first elastic rods, the second elastic element includes a third connecting member, and the second vibration element is connected to the third position of the piezoelectric element through the third connecting member. An acoustic output device as claimed in claim 1, wherein the first elastic coefficient of the first elastic element is smaller than the second elastic coefficient of the second elastic element, and the second elastic coefficient of the second elastic element is greater than 1×10 ⁴ N/m. An acoustic output device as described in any one of claims 1 to 7, wherein the ratio between the second elastic coefficient of the second elastic element and the first elastic coefficient of the first elastic element is greater than 10. An acoustic output device as claimed in claim 1, wherein, in the vibration direction perpendicular to the second vibration element, the first elastic element has a third elastic coefficient, and the ratio of the third elastic coefficient to the first elastic coefficient is greater than 1×10 ⁴ ; or in the vibration direction perpendicular to the second vibration element, the second elastic element has a fourth elastic coefficient, and the ratio of the fourth elastic coefficient to the second elastic coefficient is greater than 1×10 ⁴ . As in claim 1, the piezoelectric element comprises a beam-shaped structure, the first position is located at the center of the length extension direction of the beam-shaped structure, and the second position and the third position are respectively located at two ends of the length extension direction of the beam-shaped structure.

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