Audio output device

Abstract

An acoustic output device according to an embodiment of the present specification includes a vibration element having a beam structure extending along a longitudinal direction, a piezoelectric element that deforms in response to an electrical signal, the piezoelectric element driving the vibration element so that the deformation vibrates, the piezoelectric element being attached to a first position of the beam structure and the size of the attachment area along the longitudinal direction not exceeding 80% of the size of the beam structure along the longitudinal direction, and a mass element connected to a second position of the beam structure, the first position and the second position being distributed at an interval in the longitudinal direction, and the mass element driving the vibration of the vibration element so that the vibration of the vibration element vibrates in a direction perpendicular to the longitudinal direction.

Description

Technical Field

[0001] The present application relates to the technical field of acoustics, and particularly to an acoustic output device.

Background Art

[0002] A piezoelectric acoustic output device generates vibrations by utilizing the inverse piezoelectric effect of a piezoelectric material and emits sound waves to the outside. Compared with conventional electro-dynamic speakers, it has advantages such as high electro-mechanical energy conversion efficiency, low energy consumption, small volume, and high integration. With the current trend of miniaturization and integration of devices, the piezoelectric acoustic output device has extremely great potential. However, since the piezoelectric acoustic output device has problems such as low low-frequency response, it causes the problem of low sensitivity in the low-frequency range (for example, 50 Hz to 2000 Hz).

Summary of the Invention

Problems to be Solved by the Invention

[0003] Therefore, it is desirable to provide an acoustic output device that improves the low-frequency response and the sensitivity in the low-frequency range.

Means for Solving the Problems

[0004] The acoustic output device according to an embodiment of the present specification includes a vibration element having a beam structure extending along a longitudinal direction, and a piezoelectric element that deforms in response to an electrical signal, wherein the piezoelectric element drives the vibration element so that the deformation vibrates, the piezoelectric element is attached to a first position of the beam structure, and a size along the longitudinal direction of the attachment region does not exceed 80% of a size along the longitudinal direction of the beam structure, and a mass element connected to a second position of the beam structure, wherein the first position and the second position are distributed at intervals along the longitudinal direction, and the mass element drives the vibration of the vibration element to vibrate in a direction perpendicular to the longitudinal direction.

[0005] In some embodiments, the vibration element resonates with the mass element to generate a first resonance peak, and the frequency range of the first resonance peak is 50 Hz to 2000 Hz.

[0006] In some embodiments, the vibrations of the vibration element and the mass element have a second resonance peak, and the ratio of the frequency of the second resonance peak to the frequency of the first resonance peak is greater than 5.

[0007] In some embodiments, the vibrations of the vibration element and the mass element generate at least one resonance dip between the first resonance peak and the second resonance peak, and the amplitude difference between the first resonance peak or the second resonance peak and the at least one resonance dip is less than 80 dB.

[0008] In some embodiments, the length of the beam structure is less than 50 mm.

[0009] In some embodiments, the mass of the mass element is less than 10 g.

[0010] In some embodiments, the deformation direction of the piezoelectric element is perpendicular to the vibration direction of the vibration element.

[0011] In some embodiments, the length of the piezoelectric element is in the range of 3 mm to 30 mm.

[0012] In some embodiments, it further includes a second piezoelectric element attached to a third position of the beam structure, and the piezoelectric element and the second piezoelectric element are provided at intervals in the longitudinal direction of the vibration element.

[0013] In some embodiments, the distance between the piezoelectric element and the second piezoelectric element is less than 25 mm.

[0014] In some embodiments, the beam structure includes a fixed end, and the distance between the piezoelectric element or the second piezoelectric element and the fixed end is greater than 3 mm.

[0015] In some embodiments, in the vibration direction of the beam structure, the piezoelectric element and the second piezoelectric element are located on the same side of the beam structure.

[0016] In some embodiments, in the vibration direction of the beam structure, the piezoelectric element and the second piezoelectric element are located on both sides of the beam structure, respectively.

[0017] In some embodiments, it further includes a second mass element. In the longitudinal direction of the vibration element, the mass element and the second mass element are located on both sides of the piezoelectric element, respectively.

[0018] In some embodiments, the mass of the second mass element is greater than the mass of the mass element.

[0019] In some embodiments, the ratio of the mass of the second mass element to the mass of the mass element is in the range of 0 to 10.

[0020] In some embodiments, the deformation direction of the piezoelectric element is parallel to the vibration direction of the vibration element.

[0021] In some embodiments, one end of the piezoelectric element along the vibration direction is fixed, and the other end is connected to the beam structure at the first position.

[0022] In some embodiments, the beam structure includes a fixed end, and the ratio of the distance between the first position and the fixed end to the length of the beam structure is less than 0.6.

[0023] In some embodiments, it further includes a second vibration element, and the vibration element and the second vibration element are symmetrically provided on both sides of the mass element.

[0024] In some embodiments, it further includes a third piezoelectric element connected to the second vibration element, and the third piezoelectric element and the piezoelectric element are symmetrically provided on both sides of the mass element.

[0025] In some embodiments, one end of the vibration element and the second vibration element away from the mass element is fixedly provided.

[0026] In some embodiments, it further includes a third vibration element connected to the mass element.

[0027] In some embodiments, within a frequency range greater than 100 Hz, the third vibration element increases the vibration amplitude of the mass element.

[0028] In some embodiments, the ratio of the length of the third vibration element to the length of the vibration element is greater than 0.7.

[0029] In some embodiments, the vibration direction of the third vibration element is parallel to the vibration direction of the vibration element.

[0030] In some embodiments, it further includes a fourth piezoelectric element connected to the third vibration element.

[0031] In some embodiments, the deformation direction of the fourth piezoelectric element is perpendicular to the vibration direction of the third vibration element.

[0032] In some embodiments, the electrical signals received by the piezoelectric element and the fourth piezoelectric element have a phase difference less than 135°.

Brief Description of the Drawings

[0033]

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Mode for Carrying Out the Invention

[0034] To more clearly explain the technical means of the embodiments of this specification, the drawings necessary for the description of the embodiments will be briefly described below. Obviously, the drawings described below are only some examples or embodiments of this specification, and those skilled in the art can apply this specification to other similar scenarios based on these drawings without creative effort. Unless it is obvious from the language environment or not specified, the same numbers in the drawings indicate the same structure or operation.

[0035] The acoustic output device according to the embodiments of this specification can generate vibrations by a piezoelectric element using the inverse piezoelectric effect to output sound. Usually, the piezoelectric element may use two types of operation modes, d33 and d31. In the d33 operation mode, the deformation direction of the piezoelectric element (which may also be called the displacement output direction) is the same as the electrical direction (which may also be called the polarization direction), its resonance frequency is high, the output amplitude is small, and the low-frequency response is low. In the d31 operation mode, the deformation direction of the piezoelectric element is perpendicular to the electrical direction. In the d31 operation mode, by increasing the length of the piezoelectric element, a low-frequency peak with a sufficiently low frequency can be provided, and the output amplitude also increases significantly. However, in such a case, the piezoelectric element has many vibration modes within the audible range (for example, 20 Hz to 20 kHz), and it is expressed that many peaks and dips appear in the frequency response curve, so the sound quality of the acoustic output device (or piezoelectric speaker) is still low.

[0036] In order to solve the problems that the low-frequency response of a piezoelectric speaker is low and there are many modes within the audible range, the acoustic output device according to the embodiments of this specification may include a vibration element, a piezoelectric element, and a mass element. The vibration element has a beam structure extending along the longitudinal direction. The piezoelectric element can deform in response to an electrical signal, and the deformation can drive the vibration element to vibrate. The piezoelectric element is attached to a first position of the beam structure, and the size of the attachment region along the longitudinal direction of the beam structure does not exceed 80% of the size of the beam structure along the longitudinal direction. The mass element may be connected to a second position of the beam structure. The first position and the second position are distributed at intervals along the longitudinal direction of the beam structure, and the vibration of the piezoelectric element can drive the mass element to vibrate in a direction perpendicular to the longitudinal direction of the beam structure. Due to the resonance between the piezoelectric element and the mass element, the frequency response curve of the acoustic output device can have a first resonance peak within a low-frequency band (for example, 50 Hz to 2000 Hz), thereby improving the sensitivity of the acoustic output device within the low-frequency band. Also, due to the vibration of the piezoelectric element and the mass element, there is a second resonance peak within a high-frequency band (for example, 2000 Hz to 20000 Hz), and there is at least one resonance dip between the first resonance peak and the second resonance peak. Since the amplitude difference between the first resonance peak or the second resonance peak and the at least one resonance dip is less than 80 dB, a flat vibration response curve within the range from low frequency to high frequency is obtained, and furthermore, the sound quality of the acoustic output device is improved.

[0037] The acoustic output device according to the embodiments of the present specification is attached to a vibration element having a beam structure by a piezoelectric element, and outputs vibration by utilizing an elastic mass system composed of the elasticity provided by the beam structure having a certain length and the mass provided by the mass element. As a result, the frequency response curve of the acoustic output device has a resonance peak in the low-frequency band, thereby effectively improving the sensitivity of the acoustic output device in the low-frequency band. In some embodiments, the acoustic output device according to the embodiments of the present specification further reduces the vibration modes existing within the audible range of the human ear. For example, by having no or few resonance dips in the frequency response curve, or by reducing the amplitude difference between the resonance peak and the resonance dip, the frequency response curve within the audible range of the acoustic output device becomes flat, ensuring that the acoustic output device has high sound quality.

[0038] Hereinafter, the acoustic output device according to the embodiments of the present specification will be described in detail with reference to the drawings.

[0039] FIG. 1 is a configuration block diagram of an acoustic output device according to some embodiments of the present specification. In some embodiments, the acoustic output device 100 may be a bone conduction acoustic output device, an air conduction acoustic output device, or an acoustic output device that combines bone conduction and air conduction. In some embodiments, the acoustic output device 100 may include a sound box, headphones, glasses, a hearing aid, an Augmented Reality (AR) device, a Virtual Reality (VR) device, etc., or other devices having an audio playback function (for example, a mobile phone, a computer, etc.). In some embodiments, the acoustic output device 100 may include a vibration element 110, a piezoelectric element 120, and a mass element 130.

[0040] The vibration element 110 can vibrate based on the deformation of the piezoelectric element 120, so that the acoustic output device 100 can output vibration by the mass element 130. For example, the piezoelectric element 120 can deform in response to an electrical signal, and due to the deformation of the piezoelectric element 120, the vibration element 110 is driven to vibrate along the polarization direction of the piezoelectric element 120, and further the mass element 130 can be driven to vibrate along the polarization direction of the piezoelectric element 120. In some embodiments, the vibration direction of the mass element 130 is perpendicular to the longitudinal direction of the vibration element 110. In some embodiments, the vibration element 110 may have a beam structure extending along the longitudinal direction, the piezoelectric element 120 may be attached to the first position of the beam structure, and the mass element 130 may be connected to the second position of the beam structure. The first position and the second position are distributed at intervals along the longitudinal direction of the vibration element 110 (or called the beam structure). For example, the first position and the second position may be located at both ends of the longitudinal direction of the beam structure respectively. Also, for example, the first position may be located at the center of the longitudinal direction of the beam structure, and the second position may be located at any one end of the longitudinal direction of the beam structure. Further, for example, the first position and the second position may be located at any two positions of the longitudinal direction of the beam structure respectively, and there is a predetermined distance between the first position and the second position.

[0041] In some embodiments, the piezoelectric element 120 may be directly attached to the first position of the vibration element 110 in an adhesive manner. In some embodiments, the piezoelectric element 120 may be connected to the first position of the vibration element 110 in a manner such as fastening or tying. In some embodiments, the piezoelectric element 120 may be attached to the first position of the vibration element 110 in a physical deposition or chemical deposition manner. In some embodiments, the mass element 130 may be connected to the second position of the vibration element 110 in a manner such as adhesion, fastening, welding, screwing, etc.

[0042] In some embodiments, by adjusting the size along the longitudinal direction of the beam structure of the attachment region between the piezoelectric element 120 and the first position of the beam structure (i.e., the actual contact surface between the piezoelectric element 120 and the vibration element 110), the range of the flat curve in the frequency response curve of the acoustic output device 100 within the audible range of the human ear can be increased, and the sound quality of the acoustic output device 100 can be effectively improved. In some embodiments, in order to guarantee the sound quality of the acoustic output device 100, reduce the higher-order mode (or vibration mode) of the acoustic output device 100 within the audible range of the human ear, and increase the flat curve range in the frequency response curve of the acoustic output device 100, it can be achieved by reducing the size along the longitudinal direction of the beam structure of the attachment region between the piezoelectric element 120 and the first position of the beam structure. In some embodiments, the size along the longitudinal direction of the beam structure of the attachment region between the piezoelectric element 120 and the first position of the beam structure may be in the range of 1 mm to 50 mm. In some embodiments, the size along the longitudinal direction of the beam structure of the attachment region between the piezoelectric element 120 and the first position of the beam structure may be in the range of 1 mm to 45 mm. In some embodiments, the size along the longitudinal direction of the beam structure of the attachment region between the piezoelectric element 120 and the first position of the beam structure may be in the range of 2 mm to 40 mm. In some embodiments, the size along the longitudinal direction of the beam structure of the attachment region between the piezoelectric element 120 and the first position of the beam structure may be in the range of 3 mm to 30 mm. In some embodiments, the size along the longitudinal direction of the beam structure of the attachment region between the piezoelectric element 120 and the first position of the beam structure may be in the range of 5 mm to 20 mm.

[0043] In some embodiments, the size along the longitudinal direction of the beam structure in the attachment region between the piezoelectric element 120 and the first position of the beam structure may be 80% or less of the size along the longitudinal direction of the beam structure. In some embodiments, the size along the longitudinal direction of the beam structure in the attachment region between the piezoelectric element 120 and the first position of the beam structure may be 80% or less of the size along the longitudinal direction of the beam structure. In some embodiments, the size along the longitudinal direction of the beam structure in the attachment region between the piezoelectric element 120 and the first position of the beam structure may be 70% or less of the size along the longitudinal direction of the beam structure. In some embodiments, the size along the longitudinal direction of the beam structure in the attachment region between the piezoelectric element 120 and the first position of the beam structure may be 60% or less of the size along the longitudinal direction of the beam structure. In some embodiments, the size along the longitudinal direction of the beam structure in the attachment region between the piezoelectric element 120 and the first position of the beam structure may be 50% or less of the size along the longitudinal direction of the beam structure.

[0044] In some embodiments, further, attenuation is added to one or more elements of the acoustic output device 100 to increase the attenuation coefficient of the acoustic output device 100, and by making the frequency response curve of the acoustic output device 100 smoother within the audible range of the human ear (for example, the curve L63 shown in FIG. 6), the sound quality of the acoustic output device 100 can be improved. For example, the vibrating element 110 may be manufactured using a material having an attenuation effect (for example, silica gel, rubber, sponge, etc.). Further, for example, an attenuation material may be applied to the piezoelectric element 120. Furthermore, for example, the vibrating element 110 and / or the mass element 130 may be filled with an attenuation material or electromagnetic attenuation.

[0045] In some embodiments, the vibration element 110 may further be in a sheet shape, rod shape, or the like. In some embodiments, the material of the vibration element 110 may be a material having vibration transmission ability. For example, the material of the vibration element 110 may be silica gel, sponge, plastic, rubber, metal, etc. or any combination thereof. In some embodiments, the vibration element 110 may be a component having high elasticity (i.e., prone to elastic deformation). For example, the vibration element 110 may include a spring (e.g., an air spring, a mechanical spring, an electromagnetic spring, etc.), a vibration transmission sheet, a spring plate, a substrate, etc., or any combination thereof.

[0046] The piezoelectric element 120 may be an electric energy conversion device that can convert electric energy into mechanical energy by utilizing the inverse piezoelectric effect. In some embodiments, the piezoelectric element 120 may be composed of a material having a piezoelectric effect (inverse piezoelectric effect), such as piezoelectric ceramics, piezoelectric quartz, piezoelectric crystals, piezoelectric polymers, etc. In some embodiments, the piezoelectric element 120 may have a shape such as a sheet shape, a ring shape, a rhombus shape, a rectangular parallelepiped shape, a columnar shape, a spherical shape, or any combination thereof, or other irregular shapes. In some embodiments, the piezoelectric element 120 may have a beam structure or a sheet structure and a block structure along its longitudinal direction. In some embodiments, the piezoelectric element 120 and the vibration element 110 may have a beam structure with the same width. In some embodiments, the piezoelectric element 120 may have an integral structure, and the piezoelectric element 120 is located on one side of the vibration element 110. When the piezoelectric element 120 deforms along the polarization direction of the piezoelectric element 120, the vibration element 110 can be driven to vibrate in the same direction, that is, the piezoelectric element 120 may be in the d33 operation mode. In some embodiments, the piezoelectric element 120 may include two layers of piezoelectric sheets respectively attached to opposite sides of the vibration element. When the piezoelectric element 120 deforms along a direction perpendicular to the polarization direction of the piezoelectric element 120, the vibration element 110 can generate vibrations along the polarization direction of the piezoelectric element 120 based on the deformation of the two layers of piezoelectric sheets, that is, the piezoelectric element 120 may be in the d31 operation mode. For more descriptions regarding the piezoelectric element 120, reference can be made to FIGS. 2A, 2B and their descriptions.

[0047] The mass element 130 may be a mass block having a certain mass. In some embodiments, the mass element 130 may include a diaphragm, a vibrating membrane, etc., so that the acoustic output device 100 can output vibrations by the mass element 130. In some embodiments, the material of the mass element 130 includes, but is not limited to, materials such as 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.).

[0048] The piezoelectric element 120 can be deformed by the action of a driving voltage (or an electrical signal). Due to this deformation, the vibration element 110 can be driven to vibrate, and thus the mass element 130 can be driven to vibrate. In some embodiments, the vibration element 110 and the mass element 130 can resonate to generate a first resonance peak (e.g., the first resonance peak 621 shown in FIG. 6).

[0049] In some embodiments, the resonance frequency corresponding to the first resonance peak generated by the resonance between the vibration element 110 and the mass element 130 can be determined based on Equation (1).

[0050]

Equation

[0051] Here, f0 represents the resonance frequency, k represents the elastic coefficient of the vibration element 110, and m represents the mass of the mass element 130.

[0052] In some embodiments, as can be seen from Equation (1), by adjusting the mass of the mass element 130 and / or the elastic coefficient of the vibration element 110, the frequency range of the resonance frequency corresponding to the first resonance peak can be adjusted. In some embodiments, the frequency range of the first resonance peak may be 50 Hz to 2000 Hz. In some embodiments, the frequency range of the first resonance peak may be 50 Hz to 1500 Hz. In some embodiments, the frequency range of the first resonance peak may be 100 Hz to 1000 Hz. In some embodiments, the frequency range of the first resonance peak may be 150 Hz to 500 Hz. In some embodiments, the frequency range of the first resonance peak may be 150 Hz to 200 Hz.

[0053] In some embodiments, the vibrations of the vibrating element 110 and the mass element 130 can have a second resonance peak (e.g., the second resonance peak 622 shown in FIG. 6). In some embodiments, the second resonance peak can be generated by the resonance between the vibrating element 110 and the mass element 130 (e.g., a resonance of a higher order than the resonance that generates the first resonance peak). In some embodiments, the ratio of the frequency of the second resonance peak to the frequency of the first resonance peak may be greater than 5. For example, the frequency of the first resonance peak may be between 50 Hz and 200 Hz, and the frequency of the second resonance peak may be between 500 Hz and 2000 Hz. Further, for example, the frequency of the first resonance peak may be between 100 Hz and 500 Hz, and the frequency of the second resonance peak may be between 500 Hz and 5000 Hz. Further, for example, the frequency of the first resonance peak may be between 100 Hz and 1000 Hz, and the frequency of the second resonance peak may be between 600 Hz and 20000 Hz. Further, for example, the frequency of the first resonance peak may be between 100 Hz and 2000 Hz, and the frequency of the second resonance peak may be between 800 Hz and 20000 Hz. In some embodiments, between the first resonance peak and the second resonance peak, the vibrations of the vibrating element 110 and the mass element 130 can generate at least one resonance dip. In some embodiments, the amplitude difference between the first resonance peak or the second resonance peak and the at least one resonance dip may be smaller than a predetermined threshold value. For example, the amplitude difference between the first resonance peak or the second resonance peak and the at least one resonance dip may be smaller than 200 dB. Further, for example, the amplitude difference between the first resonance peak or the second resonance peak and the at least one resonance dip may be smaller than 150 dB. Further, for example, the amplitude difference between the first resonance peak or the second resonance peak and the at least one resonance dip may be smaller than 80 dB. Further, for example, the amplitude difference between the first resonance peak or the second resonance peak and the at least one resonance dip may be smaller than 50 dB. Further, for example, the amplitude difference between the first resonance peak or the second resonance peak and the at least one resonance dip may be smaller than 30 dB.In some embodiments, since the amplitude difference between the first resonance peak or the second resonance peak and the at least one resonance dip is smaller than a predetermined threshold value, by obtaining a flat frequency response curve between the first resonance peak or the second resonance peak and the at least one resonance dip, the sound quality of the acoustic output device 100 can be improved.

[0054] In some embodiments, by adjusting the length of the vibration element 110 (beam structure), the elastic coefficient of the vibration element 110 can be adjusted to realize the adjustment of the frequency range of the resonance frequency corresponding to the first resonance peak. For example, the larger the length of the beam structure, the smaller its elastic coefficient. When the mass of the mass element 130 is constant, the resonance frequency corresponding to the first resonance peak becomes lower. However, if the length of the beam structure is too large, it is disadvantageous for the miniaturized design of the acoustic output device 100. In order to ensure that the acoustic output device 100 can generate a first resonance peak within the low-frequency band, improve the sensitivity within the frequency band, and realize the miniaturization of the device, in some embodiments, the length of the beam structure may be smaller than 20 mm. In some embodiments, the length of the beam structure may be smaller than 30 mm. In some embodiments, the length of the beam structure may be smaller than 40 mm. In some embodiments, the length of the beam structure may be smaller than 50 mm. In some embodiments, the length of the beam structure may be smaller than 60 mm.

[0055] In some embodiments, by adjusting the mass of the mass element 130, the frequency range of the resonance frequency corresponding to the first resonance peak can be adjusted. For example, when the length of the beam structure is constant, the larger the mass of the mass element 130, the smaller the resonance frequency corresponding to the first resonance peak. However, if the mass of the mass element 130 is too large, it is disadvantageous for the miniaturized design of the acoustic output device 100. In order to ensure that the acoustic output device 100 can generate the first resonance peak within the low frequency band, improve the sensitivity within the frequency band, and realize the miniaturization of the device, in some embodiments, the mass of the mass element 130 may be less than 5 g. In some embodiments, the mass of the mass element 130 may be less than 6 g. In some embodiments, the mass of the mass element 130 may be less than 8 g. In some embodiments, the mass of the mass element 130 may be less than 10 g.

[0056] In some embodiments, the vibration of the vibration element 110 (acoustic output device 100) can be transmitted to the user in a bone conduction manner by the mass element 130. As an exemplary explanation, the vibration of the vibration element 110 is transmitted to the user's facial skeleton and / or muscles by the mass element 130 and finally transmitted to the user's ear. Also, for example, the mass element 130 may not be in direct contact with the human body, and the vibration of the vibration element 110 may be transmitted to the housing of the acoustic output device by the mass element 130 and then transmitted to the user's facial skeleton and / or muscles by the housing and finally transmitted to the user's ear. In some embodiments, the vibration of the vibration element 110 may be transmitted to the user in an air conduction manner by the mass element 130. Exemplarily, the mass element 130 can drive the air around it to vibrate directly, thereby transmitting the vibration to the user's ear through the air. Also, for example, the mass element 130 may be further connected to the vibrating membrane, and the vibration of the mass element 130 may be transmitted to the vibrating membrane and then drive the air to vibrate by the vibrating membrane, so that the vibration is transmitted to the user's ear by the air.

[0057] In some embodiments, the acoustic output device 100 may further include a second piezoelectric element 140. The second piezoelectric element 140 may have a structure, material, etc. similar to those of the piezoelectric element 120 (or referred to as the first piezoelectric element 120). The second piezoelectric element 140 is attached to the third position of the beam structure, and the piezoelectric element 120 and the second piezoelectric element 140 may be provided at intervals in the longitudinal direction of the vibrating element, and the electrical signals input by the piezoelectric element 120 and the second piezoelectric element 140 are the same. Thus, it can be regarded that the piezoelectric element 120 and the second piezoelectric element 140 are connected in series. In some embodiments, the piezoelectric element 120 and the second piezoelectric element 140 may be in the d31 operation mode, and the deformation directions of the piezoelectric element 120 and the second piezoelectric element 140 may be perpendicular to the vibration direction of the vibrating element 110. For example, the piezoelectric element 120 and the second piezoelectric element 140 reciprocally deform along a direction perpendicular to the polarization direction and drive the vibrating element 110 to vibrate along the polarization direction. In some embodiments, the beam structure may include a fixed end and a free end (i.e., the vibrating element 110 is a cantilever beam structure), the fixed end may be fixed to other components of the acoustic output device 100 (e.g., the inner wall of the housing), and the free end may be connected to the mass element 130. In some embodiments, by adjusting the distance in the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140, the higher-order modes generated when the vibrating element 110 and the mass element 130 vibrate can be reduced or eliminated. For example, the resonance peak (or resonance dip) generated by the vibration of the vibrating element 110 and the mass element 130 driven by the piezoelectric element 120 in the medium and high frequency band (e.g., 500 Hz to 2000 Hz) and the resonance dip (or resonance peak) generated by the vibration of the vibrating element 110 and the mass element 130 driven by the second piezoelectric element 140 in the medium and high frequency band (e.g., 500 Hz to 2000 Hz) can overlap. Therefore, since the higher-order modes in the medium and high frequency band of the acoustic output device 100 can be removed, it is guaranteed that the frequency response curve becomes smoother and the sound quality of the acoustic output device 100 can be improved. In some embodiments, the resonance dip and resonance peak that can overlap may refer to resonance dips and resonance peaks having close or the same frequencies.For more explanations about the second piezoelectric element 140 of the acoustic output device 100, reference can be made to FIG. 9 and its related descriptions, which are omitted here.

[0058] In some embodiments, the acoustic output device 100 may further include a second mass element 150. In the longitudinal direction of the vibration element 110, the mass element 130 (also referred to as the first mass element 130) and the second mass element 150 may be located on both sides of the piezoelectric element 120, respectively. In some embodiments, by making the mass of the second mass element 150 larger than that of the mass element 130, the beam structure is fixed toward one side of the second mass element 150 (i.e., corresponding to the fixed end), thereby solving the problem that it is difficult to find a fixed boundary and difficult to fix the fixed end of the beam structure within the acoustic output device 100 (e.g., the housing). In some embodiments, by adjusting the ratio of the mass of the second mass element 150 to the mass of the mass element 130, the adjustment of the resonance frequency corresponding to the first resonance peak can be realized. For more explanations about the acoustic output device 100 further including the second mass element 150, reference can be made to FIG. 7 and its related descriptions, which are omitted here.

[0059] In some embodiments, the piezoelectric element 120 may be in the d33 operating mode, and the deformation direction of the piezoelectric element 120 may be parallel to the vibration direction of the vibration element 110. For example, when the piezoelectric element 120 deforms along the polarization direction of the piezoelectric element 120, the vibration element 110 can also be driven to vibrate along the polarization direction. In some embodiments, one end of the piezoelectric element 120 along the vibration direction is fixed (e.g., fixed to other components of the acoustic output device 100, such as the housing), and the other end is connected to the beam structure at the first position (e.g., attached to the beam structure). In some embodiments, by adjusting the position of the piezoelectric element 120 in the beam structure, for example, by adjusting the ratio of the distance from the first position to the fixed end of the beam structure to the length of the beam structure, the resonant frequency corresponding to the resonant peak in the low-frequency band of the acoustic output device 100 can be adjusted. Therefore, the sensitivity in different frequency bands of the acoustic output device 100 is improved, and it can be applied to more usage scenarios. For more explanations regarding the parallelism between the deformation direction of the piezoelectric element 120 and the vibration direction of the vibration element 110 in the acoustic output device 100, reference can be made to FIG. 4 and its related descriptions, which are omitted here.

[0060] In some embodiments, the acoustic output device 100 may further include a second vibration element 160, and the vibration element 110 (also referred to as the first vibration element 110) and the second vibration element 160 are symmetrically provided on both sides of the mass element 130. One end of the vibration element 110 and the second vibration element 160 away from the mass element 130 is fixedly provided respectively. In some embodiments, the acoustic output device 100 may further include a third piezoelectric element 170 connected to the second vibration element 160, and the third piezoelectric element 170 and the piezoelectric element 120 are symmetrically provided on both sides of the mass element 130. Thus, it can be regarded that the third piezoelectric element 170 is connected in parallel with the piezoelectric element 120. With this setting, the resonance dip within the audible range of the human ear in the frequency response curve of the acoustic output device 100 is reduced or eliminated, the frequency response curve of the acoustic output device 100 becomes smooth, and it is guaranteed to have high sound quality. For more descriptions regarding that the acoustic output device further includes the second vibration element 160 and the third piezoelectric element 170, reference can be made to FIG. 17 and its related descriptions, which are omitted here.

[0061] In some embodiments, the acoustic output device 100 may include a third vibrating element 180 connected to the mass element 130. In some embodiments, the ratio of the length of the third vibrating element 180 to the length of the vibrating element 110 may be greater than 0.7, and the vibration direction of the third vibrating element 180 is parallel to the vibration direction of the vibrating element 110. In some embodiments, the acoustic output device 100 may further include a fourth piezoelectric element 190 connected to the third vibrating element 180. When the fourth piezoelectric element 190 is in the d31 operation mode, the deformation direction of the fourth piezoelectric element 190 is perpendicular to the vibration direction of the third vibrating element 180. Thereby, the resonance peak in the low frequency band due to the vibration of the third vibrating element 180 and the mass element 130 compensates for the resonance dip due to the vibration of the vibrating element 110 and the mass element 110, so that the frequency response curve of the acoustic output device 100 becomes smoother and the sound quality can be higher. Also, the third vibrating element 180 can improve the sensitivity of the acoustic output device 100 in the low frequency band by increasing the vibration amplitude of the mass element 130 in the low frequency band. For more explanations regarding the acoustic output device including the third vibrating element 180 and the fourth piezoelectric element 190, reference may be made to FIG. 19 and its related description, which will be omitted here.

[0062] In some embodiments, the acoustic output device 100 may further include a housing structure 210. The housing structure 210 may be configured to mount other components of the acoustic output device 100 (e.g., the vibration element 110, the second vibration element 160, the third vibration element 180, the piezoelectric element 120, the second piezoelectric element 140, the third piezoelectric element 170, the fourth piezoelectric element 190, the mass element 130, the second mass element 150, etc., or combinations thereof). In some embodiments, the housing structure 210 may be a sealed or semi-sealed structure with a hollow interior, and other components of the acoustic output device 100 are located within or on the housing structure. In some embodiments, the shape of the housing structure may be a regular shape such as a cuboid, a cylinder, a frustum of a cone, or an irregular three-dimensional structure. When the user wears the acoustic output device 100, the housing structure may be located near the user's ear. For example, the housing structure may be located on the peripheral side (e.g., the front side or the rear side) of the user's auricle. Also, for example, the housing structure may be located on the user's ear so as not to 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 may contact the user's skin. The acoustic driver assembly (e.g., a combination of the piezoelectric element 120, the vibration element 110, and the mass element 130) within the bone conduction earphone converts an audio signal into a mechanical vibration, and the mechanical vibration can be transmitted to the user's auditory nerve through the housing structure and the user's skeleton. In some embodiments, the acoustic output device 100 may be an air conduction earphone, and at least one side of the housing structure may or may not contact the user's skin. The side wall of the housing structure includes at least one sound conduction hole, and the acoustic driver assembly within the air conduction earphone converts an audio signal into an air conduction sound, and the air conduction sound can be emitted in the direction of the user's ear through the sound conduction hole.

[0063] In some embodiments, the acoustic output device 100 may include a fixing structure 220. The fixing structure 220 may be configured to hang the acoustic output device 100 near the user's ear. In some embodiments, the fixing structure 220 may be physically connected (e.g., adhered, fastened, screwed, etc.) to the housing structure 210 of the acoustic output device 100. In some embodiments, the housing structure 210 of the acoustic output device 100 may be a part of the fixing structure 220. In some embodiments, the fixing structure 220 may include an earhook, a headband, an elastic band, a glasses temple, etc., so as to stably hang the acoustic output device 100 at a position near the user's ear and prevent it from falling during the user's use. For example, the fixing structure 220 may be an earhook, and the earhook may be configured to be worn around the ear region. In some embodiments, the earhook may be a continuous hook-shaped object, may be elastically stretched and worn on the user's ear, and at the same time apply pressure to the user's auricle to firmly fix the acoustic output device 100 at a specific position on the user's ear or head. In some embodiments, the earhook may be a discontinuous strip. For example, the earhook may include a rigid part and a flexible part. The rigid part may be made of a rigid material (e.g., plastic or metal) and may be fixed to the housing structure 210 of the acoustic output device 100 in a physical connection (e.g., fastening, screwing, etc.) manner. The flexible part may be made of an elastic material (e.g., fabric, composite material or / and chloroprene rubber). Also, for example, the fixing structure 220 may be a neckband configured to be worn around the neck / shoulder region. Further, for example, the fixing structure 220 may be a glasses temple that is hung on the user's ear as a part of the glasses.

[0064] The above description regarding FIG. 1 is for illustrative purposes only and is not intended to limit the scope of the present application. Those skilled in the art can make various changes and modifications based on the description of the present application. For example, in some embodiments, the acoustic output device 100 may further include one or more components (such as a signal transceiver, an interaction module, a battery, etc.). In some embodiments, one or more components of the acoustic output device 100 may be replaced by other elements that can achieve similar functions. For example, the acoustic output device 100 may not include the fixed structure 220, and the housing structure 210 or a part thereof may have a shape adapted to the human ear (such as an annular shape, an elliptical shape, (regular or irregular) polygonal shape, a U shape, a V shape, a semi-circular shape) so that the housing structure can be hung near the user's ear. These changes and modifications do not depart from the scope of this specification.

[0065] FIG. 2A is a schematic configuration diagram of an acoustic output device according to some embodiments of this specification.

[0066] As shown in FIG. 2A, the acoustic output device 200 may include a vibration element 110, a piezoelectric element 120, and a mass element 130. The vibration element 110 has a beam structure along the longitudinal direction (i.e., the X direction). The piezoelectric element 120 may be attached to a first position of the beam structure, and the mass element 130 may be connected to the free end 112 (i.e., the second position) of the beam structure. The first position and the second position are distributed at intervals along the longitudinal direction of the beam structure. In some embodiments, the first position may be located at any position in the longitudinal direction of the beam structure. For example, the first position may be located at the center in the longitudinal direction of the beam structure. Also, for example, the piezoelectric element 120 may cover the beam structure along the longitudinal direction of the beam structure, i.e., the first position may cover the beam structure. In some embodiments, the actual contact surface between the piezoelectric element 120 and the beam structure may be referred to as the attachment region of the piezoelectric element 120. In some embodiments, by adjusting the size of the attachment region of the piezoelectric element 120 along the longitudinal direction of the beam structure, the resonance frequency and amplitude corresponding to the resonance peak generated in the low-frequency band of the acoustic output device 200 can be adjusted, making it more suitable for more scenes and helping to improve the sensitivity within the low-frequency band of the acoustic output device 200. For more descriptions regarding adjusting the size of the attachment region of the piezoelectric element 120, reference can be made to FIGS. 3A, 3B and their related descriptions, which are omitted here.

[0067] In some embodiments, the vibration element 110 may have a cantilever beam structure having a fixed end 111 and a free end 112. The fixed end 111 may be fixed to other components of the acoustic output device 100 (e.g., the inner wall of the housing), and the free end 112 may be connected to the mass element 130 to output vibrations. By driving the vibration element 110 and the mass element 130 so that the piezoelectric element 120 vibrates along the polarization direction (i.e., the Z direction) of the piezoelectric element 120, the vibration element 110 and the mass element 130 generate a first resonance peak (which may also be called a low-frequency peak) within a low-frequency band (e.g., 50 Hz to 2000 Hz), so that the sensitivity within the low-frequency band of the acoustic output device 200 can be improved.

[0068] In some embodiments, as shown in FIG. 2A, the beam structure (or cantilever beam) may be a cuboid structure. The cuboid structure may have a length along the X direction, a width along the Y direction, and a thickness along the Z direction. It should be noted that the cuboid beam structure shown in FIG. 2A is only for illustrative purposes and is not intended to limit the protection scope of this specification. Those skilled in the art can make various changes and modifications based on the description of this application. In some embodiments, the beam structure or at least some of its structural, size, and material parameters can be adjusted. For example, the beam structure in this specification is not limited to the cuboid structure and may have other shapes. For example, the cross-sectional shape along the longitudinal direction (i.e., the X direction) of the beam structure may be a regular or irregular shape such as a triangle, semi-circle, rhombus, pentagon, hexagon, etc. Also, for example, the widths and / or thicknesses at different positions in the beam structure may be the same or different. Also, for example, the shapes at different positions in the beam structure may be the same or different.

[0069] FIG. 2B is a cross-sectional view of the acoustic output device along the direction perpendicular to the longitudinal direction (i.e., the Y direction) of the vibration element shown in FIG. 2A.

[0070] In some embodiments, the deformation direction of the piezoelectric element 120 in the acoustic output device 200 may be parallel to the longitudinal direction of the vibration element 110. Thus, the vibration element 110 is driven to generate vibrations along the polarization direction of the piezoelectric element 120, that is, the vibration direction of the vibration element 110 may be parallel to the polarization direction of the piezoelectric element 120. Specifically, as shown in FIG. 2B, the piezoelectric element 120 may include two piezoelectric sheets (i.e., piezoelectric sheet 121 and piezoelectric sheet 122). The piezoelectric sheet 121 and the piezoelectric sheet 122 may be respectively attached to both opposite sides of the vibration element 110 (at the first position), and the polarization directions of the piezoelectric sheet 121 and the piezoelectric sheet 122 are perpendicular to the attachment surface. The vibration element 110 can generate vibrations perpendicular to the attachment surface in response to the deformation of the piezoelectric sheet 121 and the piezoelectric sheet 122.

[0071] In some embodiments, the piezoelectric sheet 121 and the piezoelectric sheet 122 may be an assembly configured to provide a piezoelectric effect and / or a reverse piezoelectric effect. In some embodiments, the piezoelectric sheet covers one or more surfaces of the vibration element 110, deforms under the action of a driving voltage, and drives the vibration element 110 to generate a warp, thereby enabling the piezoelectric element 120 to output vibrations. For example, along the polarization direction of the piezoelectric element 120 (as shown by the arrow BB' in the figure), the piezoelectric sheet 121 and the piezoelectric sheet 122 are respectively attached to opposite sides of the vibration element 110, and the vibration element 110 can generate vibrations based on the expansion and contraction along the longitudinal direction (as shown by the arrow AA' in the figure) of the piezoelectric element 120 of the piezoelectric sheet 121 and the piezoelectric sheet 122. Specifically, the piezoelectric sheet (for example, the piezoelectric sheet 121) located on one side of the vibration element 110 can contract along its longitudinal direction, and the piezoelectric sheet (for example, the piezoelectric sheet 122) located on one side of the vibration element 110 can elongate along its longitudinal direction, thereby driving the vibration element 110 to generate a warp along the direction perpendicular to its surface (that is, the thickness direction BB') to generate vibrations. In some embodiments, the material of the piezoelectric sheet 121 and / or the piezoelectric sheet 122 may include piezoelectric ceramics, piezoelectric quartz, piezoelectric crystals, piezoelectric polymers, etc., or any combination thereof.

[0072] It should be noted that the piezoelectric element 120 shown in FIG. 2B is only for illustrative purposes and is not intended to limit the protection scope of this specification. In some embodiments, the number of piezoelectric sheets in the piezoelectric element 120 may not be limited to two as shown in FIG. 2B. For example, the piezoelectric element 120 may include one piezoelectric sheet, and the piezoelectric sheet is attached to one side of the vibration element 110 (at the first position), can deform under the action of a driving voltage, thereby driving the vibration element 110 to generate a warp and enabling the piezoelectric element 120 to output vibrations.

[0073] In some embodiments, by adjusting the size along the longitudinal direction of the beam structure in the attachment region of the piezoelectric element 120, the resonance frequency and amplitude corresponding to the resonance peak generated in the low-frequency band of the acoustic output device can be adjusted, making it more suitable for more scenes and helping to improve the sensitivity within the low-frequency band of the acoustic output device. As a mere example, FIG. 3A is a schematic configuration diagram of an acoustic output device according to some embodiments of the present specification. As shown in FIG. 3A, in the acoustic output device 300, the piezoelectric element 120 covers (attaches to) at least a part of the beam structure (i.e., the vibration element 110) along the longitudinal direction of the beam structure from the fixed end 111. In some embodiments, the ratio of the size along the longitudinal direction of the beam structure in the attachment region of the piezoelectric element 120 to the length of the beam structure can affect the elasticity of the beam structure. For example, when the height of the cross-section along the longitudinal direction (i.e., the X direction) of the portion of the beam structure where the piezoelectric element 120 is attached (abbreviated as the covered portion) is larger than the height of the cross-section along the longitudinal direction of the portion where the piezoelectric element 120 is not attached (abbreviated as the non-covered portion), the bending elastic modulus of the covered portion is shown to be larger than that of the non-covered portion, that is, the covered portion has a higher elastic coefficient than the non-covered portion and is more difficult to bend. In some embodiments, as the ratio of the size along the longitudinal direction of the beam structure in the attachment region of the piezoelectric element 120 to the length of the beam structure increases, the elastic coefficient of the entire beam structure increases, and thus the resonance frequency corresponding to the low-frequency peak in the frequency response curve of the acoustic output device 300 also increases.

[0074] FIG. 3B is a frequency response curve diagram of the acoustic output device according to some embodiments of the present specification. As shown in FIG. 3B, curve L31 is the frequency response curve when the ratio (indicated by per in FIG. 3B) of the size along the longitudinal direction of the beam structure to the length of the beam structure in the attachment region of the piezoelectric element 120 of the acoustic output device 300 is 0.2. Curve L32 is the frequency response curve when the ratio of the size along the longitudinal direction of the beam structure to the length of the beam structure in the attachment region of the piezoelectric element 120 of the acoustic output device 300 is 0.4. Curve L33 is the frequency response curve when the ratio of the size along the longitudinal direction of the beam structure to the length of the beam structure in the attachment region of the piezoelectric element 120 of the acoustic output device 300 is 0.6. Curve L34 is the frequency response curve when the ratio of the size along the longitudinal direction of the beam structure to the length of the beam structure in the attachment region of the piezoelectric element 120 of the acoustic output device 300 is 0.8. Curve L35 is the frequency response curve when the ratio of the size along the longitudinal direction of the beam structure to the length of the beam structure in the attachment region of the piezoelectric element 120 of the acoustic output device 300 is 0.9. Curve L36 is the frequency response curve when the ratio of the size along the longitudinal direction of the beam structure to the length of the beam structure in the attachment region of the piezoelectric element 120 of the acoustic output device 300 is 1. The resonance peak within the dashed circle C is the first resonance peak generated by the acoustic output device 300 in the low frequency band when the ratio of the size along the longitudinal direction of the beam structure to the length of the beam structure in the attachment region of the piezoelectric element 120 is different.

[0075] As can be seen from FIG. 3B, as the ratio of the size along the longitudinal direction of the beam structure in the attachment region of the piezoelectric element 120 to the length of the beam structure increases, the resonance frequency corresponding to the first resonance peak in the low frequency band of the acoustic output device (for example, the acoustic output device 300) gradually increases (for example, the resonance frequencies corresponding to the first resonance peaks in curves L31 to L36 gradually increase). When the ratio of the size along the longitudinal direction of the beam structure in the attachment region of the piezoelectric element 120 to the length of the beam structure reaches 90%, the resonance frequency corresponding to the first resonance peak in curve L35 is almost the same as the resonance frequency corresponding to the first resonance peak in curve L36. When the ratio of the size along the longitudinal direction of the beam structure in the attachment region of the piezoelectric element 120 to the length of the beam structure is 80% or less, the resonance frequencies corresponding to the first resonance peaks in curves L34, L33, L32, and L31 decrease as the ratio decreases. In order to ensure that the acoustic output device (for example, the acoustic output device 300) can generate a resonance peak (that is, the first resonance peak) in a low frequency band, thereby achieving the purpose of improving the sensitivity of the acoustic output device in the low frequency band, in some embodiments, the size along the longitudinal direction of the beam structure in the attachment region of the piezoelectric element 120 may be 80% or less of the size along the longitudinal direction of the beam structure. In some embodiments, the size along the longitudinal direction of the beam structure in the attachment region of the piezoelectric element 120 may be 60% or less of the size along the longitudinal direction of the beam structure. In some embodiments, the size along the longitudinal direction of the beam structure in the attachment region of the piezoelectric element 120 may be 50% or less of the size along the longitudinal direction of the beam structure. In some embodiments, the size along the longitudinal direction of the beam structure in the attachment region of the piezoelectric element 120 may be 40% or less of the size along the longitudinal direction of the beam structure.

[0076] Also, as can be seen from FIG. 3B, as the ratio of the size along the longitudinal direction of the beam structure in the attachment region of the piezoelectric element 120 to the length of the beam structure decreases, the peak value corresponding to the first resonance peak in the curves L36 to L31 decreases. This is because the size along the longitudinal direction of the beam structure of the piezoelectric element 120 decreases, and accordingly its output force also decreases, resulting in a decrease in the peak value of the resonance peak. In order to ensure that the resonance peak in the low frequency band of the acoustic output device can have a high peak value, thereby improving the sensitivity in that frequency band, in some embodiments, the size along the longitudinal direction of the beam structure in the attachment region of the piezoelectric element 120 may be greater than 5% of the size along the longitudinal direction of the beam structure. In some embodiments, the size along the longitudinal direction of the beam structure in the attachment region of the piezoelectric element 120 may be greater than 10% of the size along the longitudinal direction of the beam structure. In some embodiments, the size along the longitudinal direction of the beam structure in the attachment region of the piezoelectric element 120 may be greater than 20% of the size along the longitudinal direction of the beam structure. In some embodiments, the size along the longitudinal direction of the beam structure in the attachment region of the piezoelectric element 120 may be greater than 30% of the size along the longitudinal direction of the beam structure.

[0077] FIG. 4 is a schematic configuration diagram of an acoustic output device according to some embodiments of the present specification.

[0078] As shown in FIG. 4, the acoustic output device 400 and the acoustic output device 200 have similar structures except that the setting method and operation mode of the piezoelectric element 120 in the acoustic output device 400 and the piezoelectric element 120 in the acoustic output device 200 are different. In the acoustic output device 400, when the piezoelectric element 120 is in the d33 operation mode, the deformation direction of the piezoelectric element 120 may be parallel to the vibration direction of the vibration element 110. Specifically, in the acoustic output device 400, the piezoelectric element 120 is attached to one side of the vibration element 110 along the vibration direction of the vibration element 110. Further, one end of the piezoelectric element 120 along the polarization direction is fixed, and the other end is connected (attached) to the beam structure at the first position. By setting it in this way, when the piezoelectric element 120 deforms along its polarization direction, the vibration element 110 can be driven to vibrate in the same direction. In some embodiments, the piezoelectric element 120 may have a laminated structure. As an exemplary description, the piezoelectric element 120 may include a multilayer piezoelectric sheet, and the multilayer piezoelectric sheet may be laminated along the polarization direction of the piezoelectric sheet to form the piezoelectric element 120.

[0079] In some embodiments, along the longitudinal direction of the beam structure, the distance between the fixed end 111 and the piezoelectric element 120 (or the first position) is different, and the resonance frequencies corresponding to the resonance peaks in the low-frequency band of the frequency response curve of the acoustic output device 400 are different. Here, the first position may refer to the position where the edge of the piezoelectric element 120 close to the fixed end 111 is located. Therefore, by adjusting the distance in the longitudinal direction of the beam structure between the fixed end 111 and the piezoelectric element 120 to change the resonance frequency corresponding to the resonance peak in the low-frequency band of the frequency response curve of the acoustic output device 400, it is helpful to improve the sensitivity in different frequency bands of the acoustic output device and can be applied to more scenes. Hereinafter, it will be described in detail with reference to the frequency response curve of the acoustic output device.

[0080] FIG. 5 is a frequency response curve diagram of an acoustic output device according to some embodiments of the present specification.

[0081] In FIG. 5, curve L51 is a frequency response curve when the ratio (denoted as p in FIG. 5) of the distance between the fixed end 111 of the acoustic output device 400 and the piezoelectric element 120 to the length of the beam structure is 0.2. Curve L52 is a frequency response curve when the ratio of the distance between the fixed end 111 of the acoustic output device 400 and the piezoelectric element 120 to the length of the beam structure is 0.4. Curve L53 is a frequency response curve when the ratio of the distance between the fixed end 111 of the acoustic output device 400 and the piezoelectric element 120 to the length of the beam structure is 0.6. Curve L54 is a frequency response curve when the ratio of the distance between the fixed end 111 of the acoustic output device 400 and the piezoelectric element 120 to the length of the beam structure is 0.8. The resonance peak within the dashed circle Y is the first resonance peak generated by the acoustic output device 400 within the low frequency band.

[0082] As can be seen from FIG. 5, when the distance between the piezoelectric element and the fixed end in the acoustic output device (for example, the acoustic output device 400) increases, the resonance frequency corresponding to the resonance peak within the low frequency band of the acoustic output device also increases (for example, the resonance frequencies corresponding to the resonance peaks in curves L51, L52, L53, and L54 gradually increase). In order to ensure that the acoustic output device (for example, the acoustic output device 400) can generate the first resonance peak within the low frequency band and improve the sensitivity within this frequency band, in some embodiments, the ratio of the distance between the first position and the fixed end to the length of the beam structure may be less than 0.8. In some embodiments, the ratio of the distance between the first position and the fixed end to the length of the beam structure may be less than 0.6. In some embodiments, the ratio of the distance between the first position and the fixed end to the length of the beam structure may be less than 0.4.

[0083] FIG. 6 is a frequency response curve diagram of an acoustic output device according to some embodiments of the present specification.

[0084] As shown in FIG. 6, curve L61 is the frequency response curve of the acoustic output device (e.g., acoustic output device 400) when the attenuation coefficient (denoted as eta in FIG. 6) is 0, the ratio of the distance between the fixed end of the acoustic output device (e.g., fixed end 111) and the piezoelectric element 120 to the length of the beam structure (denoted as p in FIG. 6) is 0.2, and the piezoelectric element 120 is in the d33 operation mode. Curve L62 is the frequency response curve of the acoustic output device (e.g., acoustic output device 200) when the attenuation coefficient of the acoustic output device is 0, the ratio of the distance between the fixed end of the acoustic output device and the piezoelectric element 120 to the length of the beam structure is 0.2, the piezoelectric element 120 is in the d31 operation mode, and the width of the piezoelectric element 120 is 2 mm. Curve L63 is the frequency response curve of the acoustic output device (e.g., acoustic output device 200) when the attenuation coefficient of the acoustic output device is 1, the ratio of the distance between the fixed end of the acoustic output device and the piezoelectric element 120 to the length of the beam structure is 0.2, the piezoelectric element 120 is in the d31 operation mode, and the width of the piezoelectric element 120 is 2 mm. In some embodiments, the width of the piezoelectric element 120 may be the same as the width of the beam structure. The first resonance peak (or the low-frequency peak) at the dashed circle X may be generated by the resonance of the vibration element 110 and the mass element 130. The first resonance peak is helpful for improving the sensitivity in the low-frequency band of the acoustic output device 200.

[0085] As shown in FIG. 6, in some embodiments, the vibration element 110 and the mass element 130 can generate a first resonance peak in the range of 50 Hz to 2000 Hz. In some embodiments, the vibration element 110 and the mass element 130 can generate a first resonance peak in the range of 100 Hz to 2000 Hz. In some embodiments, the vibration element 110 and the mass element 130 can generate a first resonance peak in the range of 200 Hz to 2000 Hz. In some embodiments, the vibration element 110 and the mass element 130 can generate a first resonance peak in the range of 500 Hz to 1500 Hz. In some embodiments, the vibration element 110 and the mass element 130 can generate a first resonance peak in the range of 500 Hz to 1000 Hz.

[0086] As can be seen with reference to curve L61 and curve L62, when the piezoelectric element 120 is in the d31 operation mode, the acoustic output device can generate a first resonance peak with a high peak value in the low frequency band, compared to the case where the piezoelectric element 120 is in the d33 operation mode. Thereby, in some embodiments, by setting the piezoelectric element 120 to the d31 operation mode, the sensitivity of the acoustic output device in the low frequency band can be improved.

[0087] In some embodiments, by adding an attenuation structure to the acoustic output device to increase the attenuation coefficient of the acoustic output device and making the vibration response curve of the acoustic output device relatively smooth, the sound quality of the acoustic output device can be further improved. For example, a vibration element 110 can be manufactured using a damping material (e.g., butyronitrile). Also, for example, a damping material can be added to the vibration element 110, and for example, a damping paint can be applied to the surface of the vibration element 110 or penetrated into the inside of the vibration element 110. As can be seen with reference to curve L62 and curve L63, L63 is smoother than L62, but the peak value of the first resonance peak of curve L61 is significantly smaller than the peak value of the first resonance peak of L63. Thereby, in some embodiments, by appropriately increasing the attenuation coefficient of the acoustic output device, its frequency response curve becomes flat and it can have high sound quality. However, if the attenuation coefficient of the acoustic output device is too large, the peak value of the first resonance peak in the low frequency band of the acoustic output device becomes small, reducing the sensitivity in the low frequency band of the acoustic output device. To ensure that the acoustic output device has high sound quality and high sensitivity in the low frequency band, in some embodiments, the attenuation coefficient of the acoustic output device may be between 0 and 1. In some embodiments, the attenuation coefficient of the acoustic output device may be between 0 and 0.8. In some embodiments, the attenuation coefficient of the acoustic output device may be between 0.1 and 0.7. In some embodiments, the attenuation coefficient of the acoustic output device may be between 0.2 and 0.5.

[0088] FIG. 7 is a schematic configuration diagram of an acoustic output device according to some embodiments of the present specification.

[0089] As shown in FIG. 7, the structure of the acoustic output device 700 can be regarded as a structure that changes based on the structure of the acoustic output device 200. Specifically, the acoustic output device 700 and the acoustic output device 200 differ in that the fixed end 111 in the acoustic output device 200 is provided as a free end 111' in the acoustic output device 700, and the acoustic output device 700 may further include a second mass element 150. In the longitudinal direction of the vibration element 110, the mass element 130 and the second mass element 150 may be located on both sides of the piezoelectric element 120, respectively. As an exemplary explanation, the mass element 130 and the second mass element 150 may be connected to both ends in the longitudinal direction of the beam structure, respectively. For example, the second mass element 150 is connected to the free end 111', and the mass element 130 is connected to the free end 112.

[0090] In some embodiments, the masses of the mass element 130 and the second mass element 150 may be the same or different. As shown in FIG. 1, by adjusting the mass of the mass element 130, the frequency range of the resonance frequency corresponding to the first resonance peak can be adjusted. When the length of the beam structure is constant, the larger the mass of the mass element 130, the smaller the resonance frequency corresponding to the first resonance peak. In some embodiments, the mass of the mass element 130 may be less than 5 g. In some embodiments, the mass of the mass element 130 may be less than 6 g. In some embodiments, the mass of the mass element 130 may be less than 8 g. In some embodiments, the mass of the mass element 130 may be less than 10 g.

[0091] FIG. 8 is a frequency response curve diagram of an acoustic output device according to some embodiments of the present specification.

[0092] In FIG. 8, curve L81 is the frequency response curve when the mass of the second mass element 150 of the acoustic output device 700 is much smaller than the mass of the mass element 130 (approximately, the ratio of the mass of the second mass element 150 to the mass of the mass element 130 (denoted by np in FIG. 8) can be regarded as 0). Curve L82 is the frequency response curve when the ratio of the mass of the second mass element 150 to the mass of the mass element 130 of the acoustic output device 700 is 2. Curve L83 is the frequency response curve when the ratio of the mass of the second mass element 150 to the mass of the mass element 130 of the acoustic output device 700 is 100.

[0093] As can be seen from FIG. 8, as the ratio of the mass of the second mass element 150 to the mass of the mass element 130 increases, the resonance frequencies corresponding to the first resonance peak 811 in the curve L81, the first resonance peak 821 in the curve L82, and the first resonance peak 831 in the curve L83 gradually decrease. As an illustrative explanation, as shown in FIG. 8, the resonance frequency corresponding to the first resonance peak 811 is approximately 350 Hz, the resonance frequency corresponding to the first resonance peak 821 is approximately 250 Hz, and the resonance frequency corresponding to the first resonance peak 831 is approximately 75 Hz. Thus, in some embodiments, in order to ensure that the acoustic output device 700 generates a first resonance peak within a lower frequency band, the mass of the second mass element 150 may be greater than the mass of the mass element 130. Further, by adjusting the ratio of the mass of the second mass element 150 to the mass of the mass element 130, the resonance frequency corresponding to the resonance peak of the acoustic output device 700 can be changed. Specifically, the greater the ratio of the mass of the second mass element 150 to the mass of the mass element 130, the smaller the resonance frequency corresponding to the resonance peak of the acoustic output device 700. In some embodiments, the ratio of the mass of the second mass element 150 to the mass of the mass element 130 may be in the range of 0 to 5. In some embodiments, the ratio of the mass of the second mass element 150 to the mass of the mass element 130 may be in the range of 0 to 10. In some embodiments, the ratio of the mass of the second mass element 150 to the mass of the mass element 130 may be in the range of 0 to 20. In some embodiments, the ratio of the mass of the second mass element 150 to the mass of the mass element 130 may be in the range of 0 to 50. In some embodiments, the ratio of the mass of the second mass element 150 to the mass of the mass element 130 may be in the range of 0 to 100.

[0094] In some embodiments, in the acoustic output device 700, when the mass of the second mass element 150 is much larger than the mass of the mass element 130 (for example, the ratio of the mass of the second mass element 150 to the mass of the mass element 130 is 100 or more), the vibration element 110 (beam structure) may tend to be fixed to one end of the second mass element 150. One end of the beam structure connected to the second mass element 150 can be regarded as a fixed end. In this case, the acoustic output device 700 may be equivalent to the acoustic output device 200. By setting it in this way, by using the second mass element 150 as the fixed boundary (fixed end) of the beam structure, the problem that it is difficult to find a fixed boundary and it is difficult to be fixed for the fixed end of the beam structure in the acoustic output device (for example, within the housing structure) can be solved.

[0095] In some embodiments, in the acoustic output device 700, when the mass of the second mass element 150 is much larger than the mass of the mass element 130, the acoustic output device 700 may be equivalent to the acoustic output device 200. Therefore, in order to ensure that the acoustic output device 700 can generate a first resonance peak within the low frequency band, as can be understood from the related description of the acoustic output device 200, the ratio of the distance between the second mass element 150 and the piezoelectric element 120 to the length of the beam structure may be less than 0.8. In some embodiments, the ratio of the distance between the second mass element 150 and the piezoelectric element 120 to the length of the beam structure may be less than 0.6. In some embodiments, the ratio of the distance between the second mass element 150 and the piezoelectric element 120 to the length of the beam structure may be less than 0.4.

[0096] FIG. 9 is a schematic configuration diagram of an acoustic output device according to some embodiments of the present specification.

[0097] As shown in FIG. 9, the structure of the acoustic output device 900 can be regarded as a structure that changes based on the structure of the acoustic output device 200. Specifically, the acoustic output device 900 and the acoustic output device 200 differ in that the acoustic output device 900 may further include a second piezoelectric element 140. The second piezoelectric element 140 may be attached to the third position of the beam structure, and the piezoelectric element 120 and the second piezoelectric element 140 may be provided at intervals in the longitudinal direction of the vibration element 110 (or the beam structure).

[0098] In some embodiments, the second piezoelectric element 140 and the piezoelectric element 120 may have the same or similar structures, materials, etc. In some embodiments, the piezoelectric element 120 and the second piezoelectric element 140 are provided at intervals in the longitudinal direction of the vibration element 110 (or the beam structure), and the electrical signals input by the piezoelectric element 120 and the second piezoelectric element 140 may be the same. In this way, it can be regarded that the piezoelectric element 120 and the second piezoelectric element 140 are connected in series. In some embodiments, the second piezoelectric element 140 and the piezoelectric element 120 may be in the d31 operation mode, and the deformation directions of the piezoelectric element 120 and the second piezoelectric element 140 may be perpendicular to the vibration direction of the vibration element 110.

[0099] In some embodiments, in the vibration direction of the vibration element 110, the piezoelectric element 120 and the second piezoelectric element 140 may be located on the same side of the beam structure. For example, as shown in FIG. 9, the piezoelectric element 120 and the second piezoelectric element 140 may be attached to the first position and the third position of the beam structure respectively, and may be located on the same side of the beam structure. In some embodiments, in the vibration direction of the vibration element 110, the piezoelectric element 120 and the second piezoelectric element 140 may be located on opposite sides of the beam structure. For example, the piezoelectric element 120 and the second piezoelectric element 140 may be attached to the first position and the third position of the beam structure respectively, and may be located on opposite sides of the beam structure.

[0100] Note that the number of piezoelectric elements shown in FIG. 9 is merely for illustrative purposes and is not intended to limit the scope of protection of this specification. In some embodiments, the acoustic output device 900 may further include two or more piezoelectric elements, such as three, four, five, etc. The two or more piezoelectric elements may be provided at intervals in the longitudinal direction of the beam structure. In some embodiments, the distances in the longitudinal direction of the beam structures of two adjacent piezoelectric elements among the two or more piezoelectric elements may be the same or different. In some embodiments, as shown in FIG. 9, the piezoelectric element 120 and the second piezoelectric element 140 may be located on the same side of the mass element 130. In some embodiments, the piezoelectric element 120 and the second piezoelectric element 140 may be located on both sides of the mass element 130, respectively. For example, in the longitudinal direction of the beam structure, the piezoelectric element 120, the mass element 130, and the second piezoelectric element 140 are arranged in sequence.

[0101] Hereinafter, the acoustic output device 900 will be described in detail with reference to the frequency curve diagram of the acoustic output device 900.

[0102] FIG. 10 is a frequency response curve diagram of an acoustic output device according to some embodiments of this specification.

[0103] FIG. 10 shows the different frequency response curves of the acoustic output device 900 when the length of the beam structure of the acoustic output device 900 is 50 mm, the lengths of the piezoelectric element 120 and the second piezoelectric element 140 (i.e., the size along the longitudinal direction of the beam structure in the attachment region between the piezoelectric element 120 and the beam structure) are both 5 mm, the piezoelectric element 120 or the second piezoelectric element 140 is 4 mm away from the fixed end (denoted as p1 in the figure), and there are different distances (denoted as p12 in the figure) along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140. The distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 may refer to the distance between the center point (e.g., the centroid) of the piezoelectric element 120 and the center point of the second piezoelectric element 140. The curve L101, the curve L102, and the curve L103 are the frequency response curves of the acoustic output device 900 when the distances along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 are 14 mm, 18 mm, and 22 mm, respectively. The dashed circle Z indicates the first resonance peak generated by the vibration element 110 and the mass element 130 within the low frequency band (e.g., 50 Hz to 2000 Hz). In some embodiments, the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 may refer to the length of the interval region in the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140.

[0104] As can be seen from FIG. 10, the length of the beam structure of the acoustic output device 900 is 50 mm, the lengths of the piezoelectric element 120 and the second piezoelectric element 140 are both 5 mm, the piezoelectric element 120 or the second piezoelectric element 140 is 4 mm away from the fixed end, and when the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 is 18 mm, the curve within the mid-high frequency band (for example, 200 Hz to 2000 Hz) of the frequency response curve of the acoustic output device 900 (that is, curve L102) becomes relatively smooth. Specifically, in curve L102, there are no or small resonance peaks and / or resonance dips within the mid-high frequency band. When the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 is 14 mm or 22 mm, it is shown that the frequency response curve of the acoustic output device 900 (that is, curve L101 or L103) has resonance peaks and / or resonance dips within the mid-high frequency band. As an illustrative explanation, as shown in FIG. 10, curve L101 has a resonance peak 1011 and a resonance dip 1012 within 200 Hz to 2000 Hz, and curve L103 has a resonance dip 1031 and a resonance peak 1032 within 200 Hz to 2000 Hz. Thereby, by reasonably designing the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 (for example, 18 mm), the resonance dips and resonance peaks (for example, resonance peak 1011 and resonance dip 1012, resonance dip 1031 and resonance peak 1032) generated within the mid-high frequency band of the acoustic output device 900 can overlap (or be called cancellation). Therefore, the frequency response curve of the acoustic output device 900 (for example, curve L102) becomes relatively flat, ensuring that the acoustic output device 900 has high sound quality.

[0105] FIG. 11 is a frequency response curve diagram of an acoustic output device according to some embodiments of the present specification.

[0106] FIG. 11 shows the different frequency response curves of the acoustic output device 900 when the length of the beam structure of the acoustic output device 900 is 50 mm, the lengths of the piezoelectric element 120 and the second piezoelectric element 140 are both 5 mm, the piezoelectric element 120 or the second piezoelectric element 140 is 5 mm away from the fixed end, and the piezoelectric element 120 and the second piezoelectric element 140 have different distances along the longitudinal direction of the beam structure. Curves L111, L112, and L113 are the frequency response curves of the acoustic output device 900 when the distances along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 are 12 mm, 14 mm, and 18 mm, respectively. The dashed circle M indicates the first resonance peak generated by the vibration element 110 and the mass element 130 within the low frequency band (for example, 50 Hz to 2000 Hz).

[0107] As can be seen from FIG. 11, when the length of the beam structure of the acoustic output device 900 is 50 mm, the lengths of the piezoelectric element 120 and the second piezoelectric element 140 are 5 mm, the piezoelectric element 120 or the second piezoelectric element 140 is 5 mm away from the fixed end, and the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 is 14 mm, the curve within the mid-high frequency band (for example, 200 Hz to 2000 Hz) of the frequency response curve of the acoustic output device 900 (that is, curve L112) becomes relatively smooth. Specifically, in curve L112, there are no or small resonance peaks and / or resonance dips within the mid-high frequency band. When the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 is 10 mm or 18 mm, it is shown that the frequency response curve of the acoustic output device 900 (that is, curve L111 or L113) has resonance peaks and / or resonance dips within the mid-high frequency band. As an exemplary explanation, as shown in FIG. 11, curve L111 has a resonance dip 1111 and a resonance peak 1112 within 200 Hz to 2000 Hz, and curve L113 has a resonance dip 1131 and a resonance peak 1132 within 200 Hz to 2000 Hz. As can be understood from this, by reasonably designing the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 (for example, 14 mm), the resonance dips and resonance peaks (for example, resonance dip 1111 and resonance peak 1112, resonance dip 1131 and resonance peak 1132) generated within the mid-high frequency band of the acoustic output device 900 can overlap (or be called cancellation). Therefore, the frequency response curve of the acoustic output device 900 (for example, curve L112) becomes relatively flat, ensuring that the acoustic output device 900 has high sound quality.

[0108] FIG. 12 is a frequency response curve diagram of an acoustic output device according to some embodiments of the present specification.

[0109] FIG. 12 shows different frequency response curves of the acoustic output device 900 corresponding to the case where the length of the beam structure of the acoustic output device 900 is 50 mm, the lengths of the piezoelectric element 120 and the second piezoelectric element 140 are both 5 mm, the piezoelectric element 120 or the second piezoelectric element 140 is 6 mm away from the fixed end, and the piezoelectric element 120 and the second piezoelectric element 140 have different distances along the longitudinal direction of the beam structure. Curves L121, L122, and L123 are the frequency response curves of the acoustic output device 900 when the distances along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 are 10 mm, 12 mm, and 14 mm, respectively. The dashed circle N indicates the first resonance peak generated by the vibration element 110 and the mass element 130 within the low frequency band (for example, 50 Hz to 2000 Hz).

[0110] As can be seen from FIG. 12, when the length of the beam structure of the acoustic output device 900 is 50 mm, the lengths of the piezoelectric element 120 and the second piezoelectric element 140 are 5 mm, the piezoelectric element 120 or the second piezoelectric element 140 is 6 mm away from the fixed end, and the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 is 12 mm, the curve within the mid-high frequency band (for example, 200 Hz to 2000 Hz) of the frequency response curve of the acoustic output device 900 (that is, curve L122) becomes relatively smooth. Specifically, in curve L122, there are no or small resonance peaks and / or resonance dips within the mid-high frequency band. When the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 is 10 mm or 14 mm, it is shown that the frequency response curve of the acoustic output device 900 (that is, curve L121 or L123) has resonance peaks and / or resonance dips within the mid-high frequency band. As an illustrative explanation, as shown in FIG. 12, curve L121 has a resonance dip 1211 and a resonance peak 1212 within 200 Hz to 2000 Hz, and curve L123 has a resonance dip 1231 and a resonance peak 1232 within 200 Hz to 2000 Hz. As can be understood from this, by reasonably designing the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 (for example, 12 mm), the resonance dips and resonance peaks (for example, resonance dip 1211 and resonance peak 1212, resonance dip 1231 and resonance peak 1232) generated within the mid-high frequency band of the acoustic output device 900 can overlap (or be called cancellation). Therefore, the frequency response curve of the acoustic output device 900 (for example, curve L122) becomes relatively flat, ensuring that the acoustic output device 900 has high sound quality.

[0111] As shown in FIGS. 10 to 12, when the lengths of the beam structure, the piezoelectric element 120, and the second piezoelectric element 140 do not change, as the distance between the piezoelectric element 120 or the second piezoelectric element 140 and the fixed end 111 increases (for example, 4 mm, 5 mm, and 6 mm in FIGS. 10 to 12 in order), the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 corresponding to the overlapping resonance peak and resonance dip gradually decreases (for example, 18 mm, 14 mm, and 12 mm in FIGS. 10 to 12 in order). Thus, in some embodiments, based on the different distances between the piezoelectric element 120 or the second piezoelectric element 140 and the fixed end 111, the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 can be adjusted. As a mere example, when the distance between the piezoelectric element 120 or the second piezoelectric element 140 and the fixed end 111 increases, by appropriately decreasing the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140, the resonance peak and the resonance dip can overlap, so that the frequency response curve of the acoustic output device 900 becomes relatively flat and the sound quality of the acoustic output device 900 is improved. For example, the ratio of the distance between the piezoelectric element 120 or the second piezoelectric element 140 and the fixed end 111 to the length of the beam structure may be greater than 0.05, and the ratio of the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 to the length of the beam structure may be less than 0.5. Also, for example, the ratio of the distance between the piezoelectric element 120 or the second piezoelectric element 140 and the fixed end 111 to the length of the beam structure may be greater than 0.08, and the ratio of the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 to the length of the beam structure may be less than 0.4. Also, for example, the ratio of the distance between the piezoelectric element 120 or the second piezoelectric element 140 and the fixed end 111 to the length of the beam structure may be greater than 0.1, and the ratio of the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 to the length of the beam structure may be less than 0.3. Also, for example, the ratio of the distance between the piezoelectric element 120 or the second piezoelectric element 140 and the fixed end 111 to the length of the beam structure may be greater than 0.12, and the ratio of the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 to the length of the beam structure may be less than 0.25.

[0112] FIG. 13 is a frequency response curve diagram of an acoustic output device according to some embodiments of the present specification.

[0113] In FIG. 13, the length of the beam structure of the acoustic output device 900 (denoted as lb in the figure) is 37.5 mm, the lengths of the piezoelectric element 120 and the second piezoelectric element 140 are both 5 mm, the piezoelectric element 120 or the second piezoelectric element 140 is 4 mm away from the fixed end, and different frequency response curves of the acoustic output device 900 corresponding to the case where there are different distances along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 are shown. Curves L131, L132, and L133 are the frequency response curves of the acoustic output device 900 when the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 is 8 mm, respectively. Inside the dashed circle O, the vibration element 110 and the mass element 130 are the first resonance peaks generated in the low frequency band (for example, 50 Hz to 2000 Hz).

[0114] As can be seen from FIG. 13, when the length of the beam structure of the acoustic output device 900 is 37.5 mm, the lengths of the piezoelectric element 120 and the second piezoelectric element 140 are 5 mm, the piezoelectric element 120 or the second piezoelectric element 140 is 4 mm away from the fixed end, and the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 is 9 mm, the curve within the mid-high frequency band (for example, 200 Hz to 2000 Hz) of the frequency response curve of the acoustic output device 900 (that is, curve L132) becomes relatively smooth. Specifically, in curve L132, there are no or small resonance peaks and / or resonance dips within the mid-high frequency band. When the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 is 8 mm or 10 mm, it is shown that the frequency response curve of the acoustic output device 900 (that is, curve L131 or L133) has resonance peaks and / or resonance dips within the mid-high frequency band. As an illustrative explanation, as shown in FIG. 13, curve L131 has a resonance dip 1311 and a resonance peak 1312 within 200 Hz to 2000 Hz, and curve L133 has a resonance dip 1331 and a resonance peak 1332 within 200 Hz to 2000 Hz. As can be understood from this, by reasonably designing the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 (for example, 9 mm), the resonance dips and resonance peaks (for example, resonance dip 1311 and resonance peak 1312, resonance dip 1331 and resonance peak 1332) generated within the mid-high frequency band of the acoustic output device 900 can overlap (or be called cancellation), so that the frequency response curve of the acoustic output device 900 becomes relatively flat, ensuring that the acoustic output device 900 has high sound quality.

[0115] FIG. 14 is a frequency response curve diagram of an acoustic output device according to some embodiments of the present specification.

[0116] FIG. 14 shows the different frequency response curves of the acoustic output device 900 when the length of the beam structure of the acoustic output device 900 is 37.5 mm, the lengths of the piezoelectric element 120 and the second piezoelectric element 140 are both 5 mm, the piezoelectric element 120 or the second piezoelectric element 140 is 5 mm away from the fixed end, and the piezoelectric element 120 and the second piezoelectric element 140 have different distances along the longitudinal direction of the beam structure. Curves L141, L142, and L143 are the frequency response curves of the acoustic output device 900 when the distances along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 are 5.6 mm, 6.2 mm, and 6.8 mm, respectively. Inside the dashed circle P, the vibration element 110 and the mass element 130 are the first resonance peaks generated in the low frequency band (for example, 50 Hz to 2000 Hz).

[0117] As can be seen from FIG. 14, when the length of the beam structure of the acoustic output device 900 is 37.5 mm, the lengths of the piezoelectric element 120 and the second piezoelectric element 140 are 5 mm, the piezoelectric element 120 or the second piezoelectric element 140 is 5 mm away from the fixed end, and the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 is 6.2 mm, the curve within the mid-high frequency band (for example, 200 Hz to 2000 Hz) of the frequency response curve of the acoustic output device 900 (that is, curve L142) becomes relatively smooth. Specifically, in curve L142, there are no or small resonance peaks and / or resonance dips within the mid-high frequency band. When the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 is 5.6 mm or 6.8 mm, it is shown that the frequency response curve of the acoustic output device 900 (that is, curve L141 or L143) has resonance peaks and / or resonance dips within the mid-high frequency band. As an exemplary explanation, as shown in FIG. 14, curve L141 has a resonance dip 1411 and a resonance peak 1412 within 200 Hz to 2000 Hz, and curve L143 has a resonance dip 1431 and a resonance peak 1432 within 200 Hz to 2000 Hz. As can be understood from this, by reasonably designing the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 (for example, 6.2 mm), the resonance dips and resonance peaks (for example, resonance dip 1411 and resonance peak 1412, resonance dip 1431 and resonance peak 1432) generated within the mid-high frequency band of the acoustic output device 900 can overlap (or be called cancellation), so that the frequency response curve of the acoustic output device 900 becomes relatively flat, ensuring that the acoustic output device 900 has high sound quality.

[0118] As shown in FIGS. 13 and 14, when the lengths of the beam structure, the piezoelectric element 120, and the second piezoelectric element 140 do not change, as the distance between the piezoelectric element 120 or the second piezoelectric element 140 and the fixed end 111 increases (for example, 4 mm and 5 mm in FIGS. 13 and 14 in sequence), the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 corresponding to the overlapping resonance peak and resonance dip gradually decreases (for example, 9 mm and 6.2 mm in FIGS. 13 and 14 in sequence). Thereby, in some embodiments, based on the different distances between the piezoelectric element 120 or the second piezoelectric element 140 and the fixed end 111, the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 can be adjusted. As a mere example, when the distance between the piezoelectric element 120 or the second piezoelectric element 140 and the fixed end 111 increases, by appropriately decreasing the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140, the resonance peak and the resonance dip can overlap, so that the frequency response curve of the acoustic output device 900 becomes relatively flat and the sound quality of the acoustic output device 900 is improved. For example, the ratio of the distance between the piezoelectric element 120 or the second piezoelectric element 140 and the fixed end 111 to the length of the beam structure may be greater than 0.1, and the ratio of the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 to the length of the beam structure may be less than 0.25. Also, for example, the ratio of the distance between the piezoelectric element 120 or the second piezoelectric element 140 and the fixed end 111 to the length of the beam structure may be greater than 0.13, and the ratio of the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 to the length of the beam structure may be less than 0.2.

[0119] FIG. 15 is a frequency response curve diagram of an acoustic output device according to some embodiments of the present specification.

[0120] FIG. 15 shows different frequency response curves of the acoustic output device 900 corresponding to the case where the length of the beam structure of the acoustic output device 900 is 25 mm, the lengths of the piezoelectric element 120 and the second piezoelectric element 140 are both 5 mm, the piezoelectric element 120 or the second piezoelectric element 140 is 4 mm away from the fixed end, and the piezoelectric element 120 and the second piezoelectric element 140 have different distances along the longitudinal direction of the beam structure. Curves L151, L152, and L153 are the frequency response curves of the acoustic output device 900 when the distances along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 are 0.5 mm, 1.5 mm, and 2.5 mm, respectively. Inside the dashed circle Q, the vibration element 110 and the mass element 130 are the first resonance peaks generated in the low frequency band (for example, 50 Hz to 2000 Hz).

[0121] As can be seen from FIG. 15, when the length of the beam structure of the acoustic output device 900 is 25 mm, the lengths of the piezoelectric element 120 and the second piezoelectric element 140 are 5 mm, the piezoelectric element 120 or the second piezoelectric element 140 is 4 mm away from the fixed end, and the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 is 1.5 mm, the curve within the mid- to high-frequency band (for example, 300 Hz to 3000 Hz) of the frequency response curve of the acoustic output device 900 (that is, curve L152) becomes relatively smooth. Specifically, in curve L152, there are few or no resonance peaks and / or resonance dips within the mid- to high-frequency band. When the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 is 0.5 mm or 2.5 mm, it is shown that the frequency response curve of the acoustic output device 900 (that is, curve L151 or L153) has resonance peaks and / or resonance dips within the mid- to high-frequency band. As an illustrative explanation, as shown in FIG. 15, curve L151 has a resonance dip 1511 and a resonance peak 1512 within 300 Hz to 3000 Hz, and curve L153 has a resonance dip 1531 and a resonance peak 1532 within 300 Hz to 3000 Hz. As can be understood from this, by reasonably designing the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 (for example, 1.5 mm), the resonance dips and resonance peaks (for example, resonance dip 1511 and resonance peak 1512, resonance dip 1531 and resonance peak 1532) generated within the mid- to high-frequency band of the acoustic output device 900 can overlap (or be called cancellation). Therefore, the frequency response curve of the acoustic output device 900 becomes relatively flat, ensuring that the acoustic output device 900 has high sound quality.

[0122] As shown in FIGS. 10, 13, and 15, when the lengths of the piezoelectric element 120 and the second piezoelectric element 140 and the distance between the piezoelectric element 120 or the second piezoelectric element 140 and the fixed end 111 do not change, as the length of the beam structure decreases (for example, 50 mm, 37.5 mm, and 25 mm in FIGS. 10, 13, and 15 in sequence), the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 corresponding to the overlapping resonance peak and resonance dip gradually decreases (for example, 18 mm, 9 mm, and 1.5 mm in FIGS. 10, 13, and 15 in sequence). Thereby, in some embodiments, based on different beam structure lengths, the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 can be adjusted. As a mere example, when the length of the beam structure decreases, by appropriately reducing the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140, the resonance peak and the resonance dip can overlap, so that the frequency response curve of the acoustic output device 900 becomes relatively flat and the sound quality of the acoustic output device 900 is improved. For example, the ratio of the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 to the length of the beam structure may be less than 0.6. Also, for example, the ratio of the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 to the length of the beam structure may be less than 0.4. Also, for example, the ratio of the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 to the length of the beam structure may be less than 0.2. Also, for example, the ratio of the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 to the length of the beam structure may be less than 0.1.

[0123] FIG. 16 is a frequency response curve diagram of an acoustic output device according to some embodiments of the present specification.

[0124] FIG. 16 shows the different frequency response curves of the acoustic output device 900 corresponding to the case where the length of the beam structure of the acoustic output device 900 is 50 mm, the lengths of the piezoelectric element 120 and the second piezoelectric element 140 (denoted as lp in the figure) are both 25 mm, the piezoelectric element 120 or the second piezoelectric element 140 is 4 mm away from the fixed end, and there are different distances along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140. Curves L161, L162, and L163 are the frequency response curves of the acoustic output device 900 when the distances along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 are -4 mm, -2.5 mm, and -1 mm, respectively. Inside the dashed circle R, the vibration element 110 and the mass element 130 are the first resonance peaks generated in the low frequency band (for example, 50 Hz to 2000 Hz). The distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 may refer to the distance between the center point (for example, the center of gravity) of the piezoelectric element 120 and the center point of the second piezoelectric element 140. Note that when the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 is 0, it may be understood that the projections of the center points of the piezoelectric element 120 and the second piezoelectric element 140 along the vibration direction of the beam structure overlap. When the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 is a positive number, it may be understood as the distance between the center points of the piezoelectric element 120 and the second piezoelectric element 140 when the position of one piezoelectric element (for example, the second piezoelectric element 140) does not change and the other piezoelectric element (for example, the piezoelectric element 120) shifts along the longitudinal direction of the beam structure towards the mass element 130. When the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 is a negative number, it may be understood as the distance between the center points of the piezoelectric element 120 and the second piezoelectric element 140 when the position of one piezoelectric element (for example, the second piezoelectric element 140) does not change and the other piezoelectric element (for example, the piezoelectric element 120) shifts along the longitudinal direction of the beam structure towards the fixed end 111.

[0125] As can be seen from FIG. 16, when the length of the beam structure of the acoustic output device 900 is 50 mm, the lengths of the piezoelectric element 120 and the second piezoelectric element 140 are 25 mm, the piezoelectric element 120 or the second piezoelectric element 140 is 4 mm away from the fixed end, and the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 is -2.5 mm, the curve within the mid-high frequency band (for example, 300 Hz to 3000 Hz) of the frequency response curve of the acoustic output device 900 (that is, curve L162) becomes relatively smooth. Specifically, in curve L162, there are no or small resonance peaks and / or resonance dips within the mid-high frequency band. When the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 is -4 mm or -1 mm, it is shown that the frequency response curve of the acoustic output device 900 (that is, curve L161 or L163) has resonance peaks and / or resonance dips within the mid-high frequency band. As an illustrative explanation, as shown in FIG. 16, curve L161 has a resonance dip 1611 and a resonance peak 1612 within 300 Hz to 3000 Hz, and curve L163 has a resonance dip 1631 and a resonance peak 1632 within 300 Hz to 3000 Hz. As can be understood from this, by reasonably designing the distance (for example, -2.5 mm) between the piezoelectric element 120 and the second piezoelectric element 140 along the longitudinal direction of the beam structure, the resonance dips and resonance peaks (for example, resonance dip 1611 and resonance peak 1612, resonance dip 1631 and resonance peak 1632) generated within the mid-high frequency band of the acoustic output device 900 can overlap (or be called cancellation), so that the frequency response curve of the acoustic output device 900 becomes relatively flat, ensuring that the acoustic output device 900 has high sound quality.

[0126] As shown in FIGS. 10 and 16, when the length of the beam structure, the distance between the piezoelectric element 120 or the second piezoelectric element 140 and the fixed end 111 do not change, as the lengths of the piezoelectric element 120 and the second piezoelectric element 140 increase (for example, 5 mm and 25 mm in FIGS. 10 and 16 in sequence), the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 corresponding to the overlapping resonance peaks and resonance dips gradually decreases (for example, 18 mm and -2.5 mm in FIGS. 10 and 16 in sequence). Thereby, in some embodiments, based on the different lengths of the piezoelectric element 120 and the second piezoelectric element 140, the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 can be adjusted. As a mere example, when the lengths of the piezoelectric element 120 and the second piezoelectric element 140 increase, by appropriately reducing the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140, the resonance peak and the resonance dip can overlap, so that the frequency response curve of the acoustic output device 900 becomes relatively flat and the sound quality of the acoustic output device 900 is improved. For example, the ratio of the lengths of the piezoelectric element 120 and the second piezoelectric element 140 to the length of the beam structure may be greater than 0.05, and the ratio of the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 to the length of the beam structure may be less than 0.4. Also, for example, the ratio of the lengths of the piezoelectric element 120 and the second piezoelectric element 140 to the length of the beam structure may be greater than 0.1, and the ratio of the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 to the length of the beam structure may be less than 0.3. Also, for example, the ratio of the lengths of the piezoelectric element 120 and the second piezoelectric element 140 to the length of the beam structure may be greater than 0.2, and the ratio of the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 to the length of the beam structure may be less than 0.1. Also, for example, the ratio of the lengths of the piezoelectric element 120 and the second piezoelectric element 140 to the length of the beam structure may be greater than 0.4, and the ratio of the distance along the longitudinal direction of the beam structure between the piezoelectric element 120 and the second piezoelectric element 140 to the length of the beam structure may be less than 0.

[0127] As shown in FIGS. 10 to 16, by reasonably designing the distance between the piezoelectric element 120 and the second piezoelectric element 140, the frequency response curves (for example, curves L102, L112, L122, L132, L142, L152, and L162) of the acoustic output device 900 become smooth within the mid- to high-frequency band, and the acoustic output device 900 can have high sound quality. In some embodiments, the length of the beam structure may be less than 50 mm, and the distance between the piezoelectric element 120 and the second piezoelectric element 140 may be less than 25 mm. In some embodiments, the length of the beam structure may be less than 50 mm, and the distance between the piezoelectric element 120 and the second piezoelectric element 140 may be less than 22 mm. In some embodiments, the length of the beam structure may be less than 50 mm, and the distance between the piezoelectric element 120 and the second piezoelectric element 140 may be less than 18 mm. In some embodiments, the length of the beam structure may be less than 50 mm, and the distance between the piezoelectric element 120 and the second piezoelectric element 140 may be less than 14 mm. In some embodiments, the length of the beam structure may be less than 40 mm, and the distance between the piezoelectric element 120 and the second piezoelectric element 140 may be less than 10 mm. In some embodiments, the length of the beam structure may be less than 40 mm, and the distance between the piezoelectric element 120 and the second piezoelectric element 140 may be less than 7 mm. In some embodiments, the length of the beam structure may be less than 40 mm, and the distance between the piezoelectric element 120 and the second piezoelectric element 140 may be less than 2.5 mm. In some embodiments, the length of the beam structure may be less than 30 mm, and the distance between the piezoelectric element 120 and the second piezoelectric element 140 may be less than -1 mm.

[0128] As can be seen from curve L101, curve L112, and curve L123, when the length of the beam structure, the length of the piezoelectric element 120, and the distance between the piezoelectric element 120 and the second piezoelectric element 140 are constant, as the distance between the piezoelectric element 120 or the second piezoelectric element 140 and the fixed end (for example, the distance between the second piezoelectric element 140 and the fixed end shown in FIG. 9) increases, the peak value of the first resonance peak generated by the acoustic output device 900 within the low-frequency band increases. As an illustrative explanation, the peak value of the first resonance peak within the broken-line circle Z of curve L101 is approximately 170 dB, the peak value of the first resonance peak within the broken-line circle M of curve 112 is approximately 175 dB, and the peak value of the first resonance peak within the broken-line circle N of curve L123 is approximately 180 dB. In some embodiments, by increasing the distance between the piezoelectric element 120 or the second piezoelectric element 140 and the fixed end to improve the peak value of the first resonance peak within the low-frequency band of the acoustic output device 900, the sensitivity within the low-frequency band of the acoustic output device 900 can be improved. In some embodiments, the distance between the piezoelectric element 120 or the second piezoelectric element 140 and the fixed end may be greater than 3 mm. In some embodiments, the distance between the piezoelectric element 120 or the second piezoelectric element 140 and the fixed end may be greater than 4 mm. In some embodiments, the distance between the piezoelectric element 120 or the second piezoelectric element 140 and the fixed end may be greater than 5 mm. In some embodiments, the distance between the piezoelectric element 120 or the second piezoelectric element 140 and the fixed end may be greater than 6 mm. In some embodiments, the distance between the piezoelectric element 120 or the second piezoelectric element 140 and the fixed end may be greater than 7 mm.

[0129] FIG. 17 is a schematic configuration diagram of an acoustic output device according to some embodiments of the present specification.

[0130] As shown in FIG. 17, the structure of the acoustic output device 1700 can be regarded as a structure that changes based on the structure of the acoustic output device 200. Specifically, the acoustic output device 1700 and the acoustic output device 200 differ in that the acoustic output device 1700 further includes a second vibration element 160, and the vibration element 110 and the second vibration element 160 are symmetrically provided on both sides of the mass element 130. The acoustic output device 1700 may include a third piezoelectric element 170 connected to (or attached to) the second vibration element 160, and the third piezoelectric element 170 and the piezoelectric element 120 are symmetrically provided on both sides of the mass element 130. In some embodiments, the piezoelectric element 120 and the third piezoelectric element 170 are respectively provided on two piezoelectric beams located on both sides of the mass element 130, and the electrical signals input by the piezoelectric element 120 and the third piezoelectric element 170 may be the same. In this way, it can be regarded that the piezoelectric element 120 is connected in parallel to the third piezoelectric element 170. In some embodiments, the vibration directions of the second vibration element 160 and the vibration element 110 are the same. In some embodiments, the piezoelectric element 120 and the third piezoelectric element 170 may be in the d31 operation mode, and the deformation directions of the piezoelectric element 120 and the third piezoelectric element 170 may be perpendicular to the vibration directions of the vibration element 110 and the second vibration element 160. In some embodiments, the piezoelectric element 120 and the third piezoelectric element 170 may be in the d33 operation mode, and the deformation directions of the piezoelectric element 120 and the third piezoelectric element 170 may be parallel to the vibration direction of the vibration element 110. In some embodiments, one end of the vibration element 110 and the second vibration element 160 away from the mass element 130 is fixedly provided (i.e., a fixed end). For example, one end of the vibration element 110 and the second vibration element 160 away from the mass element 130 may be fixed to other components (e.g., a housing) of the acoustic output device 1700. Also, for example, the piezoelectric element 120 and the third piezoelectric element 170 may be in the d33 operation mode, and one end of the piezoelectric element 120 and the third piezoelectric element 170 along the vibration direction of the vibration element 110 and the second vibration element 160 is fixed, and the other ends are respectively attached to one end of the vibration element 110 and the second vibration element 160 away from the mass element 130, so that one end of the vibration element 110 and the second vibration element 160 away from the mass element 130 may be fixedly provided with respect to the mass element 130.For more explanations about the second vibration element 160 and the third piezoelectric element 170, reference can be made to the related explanations of the vibration element 110 and the piezoelectric element 120 respectively, and the explanations are omitted here.

[0131] FIG. 18 is a frequency response curve diagram of an acoustic output device according to some embodiments of the present specification.

[0132] In FIG. 18, the curve L181 is a frequency response curve when no mass element is connected between the vibration element 110 and the second vibration element 160 (or it is called the no-load of the vibration element 110 and the second vibration element 160). The curve L182 is a frequency response curve when a mass element is connected between the vibration element 110 and the second vibration element 160 (or it is called the load of the vibration element 110 and the second vibration element 160).

[0133] As shown in FIG. 18, the curve between adjacent resonance peaks in the curve L181 and the curve L182 is smooth and there is no resonance dip. As can be seen from this, by providing a structure in which piezoelectric sheets are connected in parallel, no resonance dip occurs in the frequency response curve of the acoustic output device 1700, the frequency response curve becomes smoother, and it can help improve the sound quality of the acoustic output device 1700. In addition, when comparing the resonance peak 1811 of the curve L181 and the resonance peak 1821 of the curve L182, it can be seen that when the mass element 130 is connected between the vibration element 110 and the second vibration element 160, the resonance frequency corresponding to the resonance peak becomes smaller. Therefore, by changing the mass of the mass element 130, the resonance frequency corresponding to the resonance peak generated by the acoustic output device 1700 in the low frequency band (for example, 100 Hz to 1000 Hz) can be changed.

[0134] FIG. 19 is a schematic configuration diagram of an acoustic output device according to some embodiments of the present specification.

[0135] As shown in FIG. 19, the structure of the acoustic output device 1900 can be regarded as a structure that changes based on the structure of the acoustic output device 200. Specifically, the acoustic output device 1900 and the acoustic output device 200 differ in that the acoustic output device 1900 may further include a third vibration element 180 connected to the mass element 130. Note that the vibration direction of the third vibration element 180 is parallel to the vibration direction of the vibration element 110. Further, the acoustic output device 1900 may further include a fourth piezoelectric element 190 that may be connected to the third vibration element 180. In some embodiments, when the fourth piezoelectric element 190 is in the d31 operation mode, the deformation direction of the fourth piezoelectric element 190 is perpendicular to the vibration direction of the third vibration element 180. In some embodiments, the third vibration element 180 and the vibration element 110 may have the same or different structures, materials, etc. In some embodiments, the fourth piezoelectric element 190 and the piezoelectric element 120 may have the same or different structures, materials, etc. In some embodiments, as shown in FIG. 19, the beam structures located on both sides of the mass element 130 of the third vibration element 180 may be provided symmetrically. In some embodiments, the fourth piezoelectric element 190 may include two piezoelectric sheets located on both sides of the mass element 130. In some embodiments, the fourth piezoelectric element 190 may include one piezoelectric sheet that may completely cover the third vibration element 180 or may partially cover the third vibration element 180. For more explanations regarding the third vibration element 180 and the fourth piezoelectric element 190, reference can be made to the related explanations of the vibration element 110 and the piezoelectric element 120 respectively, and the explanations are omitted here.

[0136] Note that the acoustic output device 1900 shown in FIG. 19 is only for illustrative purposes and is not intended to limit the protection scope of this specification. Those skilled in the art can make various changes and modifications based on the description of this application. For example, the fourth piezoelectric element 190 may include one piezoelectric sheet that may completely cover the third vibration element 180 or may partially cover the third vibration element 180. Also, for example, the piezoelectric element 120 may include one piezoelectric sheet that may completely cover the vibration element 110.

[0137] In some embodiments, the vibration element 110 may have a cantilever beam structure. The cantilever beam has a fixed end 111 and a free end 112. The mass element 130 is connected to the vibration element 110 at the free end 112. In some embodiments, the third vibration element 180 may have a beam structure. For example, the third vibration element 180 may be a free beam in which at least a part (e.g., the longitudinal central region) is connected to the mass element 130 and both ends are free ends. In some embodiments, in the projection plane along the vibration direction of the third vibration element 180 or the vibration element 110, the included angle between the longitudinal direction of the third vibration element 180 (i.e., the major axis direction of the free beam) and the longitudinal direction of the vibration element 110 may be 90°. In some embodiments, the connection position between the mass element 130 and the third vibration element 180 may be located at the center in the longitudinal direction of the third vibration element 180, that is, the vibration element 110 and the third vibration element 180 may form a "T" - shaped structure (or a structure called a T - shaped beam). In some embodiments, the included angle between the longitudinal direction of the third vibration element 180 and the longitudinal direction of the vibration element 110 may be less than 90° or greater than 90°. In some embodiments, the connection position between the mass element 130 and the third vibration element 180 may be located at any position in the longitudinal direction of the third vibration element 180.

[0138] In some embodiments, the vibration element 110 and the third vibration element 180 may be an integrally formed "T" - shaped structure or a structure with other configurations. Other configurations include that in the longitudinal direction of the vibration element 110 (i.e., the x - direction in the figure), the widths (i.e., the y - direction in the figure) at different positions of the vibration element 110 are different. For example, the width increases as it approaches the free end or the width decreases as it approaches the free end.

[0139] FIG. 20 is a frequency response curve diagram of an acoustic output device according to some embodiments of the present specification.

[0140] In FIG. 20, curve L201 is the frequency response curve generated when the piezoelectric element 120 is independently excited (i.e., the frequency response curve generated when the mass element 130 is driven so that the vibrating element 110 (or a cantilever beam) vibrates). Curve L202 is the frequency response curve generated when the fourth piezoelectric element 190 is independently excited (i.e., the frequency response curve generated when the third vibrating element 180 (or a free beam) and the mass element 130 vibrate). Curve L203 is the frequency response curve when the piezoelectric element 120 and the fourth piezoelectric element 190 in the acoustic output device 1900 are simultaneously excited (i.e., the frequency response curve generated when the vibrating element 110, the third vibrating element 180, and the mass element 130 vibrate simultaneously (or a T-shaped beam)).

[0141] As shown in FIG. 20, at least two resonance peaks (e.g., the first resonance peak 2011 and the second resonance peak 2012) exist within the audible range of the human ear (e.g., 20 Hz to 20,000 Hz) in curve L201. A resonance dip 2013 exists between the first resonance peak 2011 and the second resonance peak 2012. In some embodiments, the frequency of the first resonance peak 2011 may be within the range of 50 Hz to 2000 Hz. The frequency of the resonance dip 2013 is approximately 1330 Hz. At least one resonance peak (e.g., resonance peak 2021) exists within the audible range of the human ear (e.g., 20 Hz to 20,000 Hz) in curve L202. The frequency of the resonance peak 2021 is approximately 1330 Hz. At least two resonance peaks (e.g., the first resonance peak 2031 and the second resonance peak 2032) exist within the audible range of the human ear (e.g., 20 Hz to 20,000 Hz) in curve L203. As can be seen from FIG. 20, no resonance dip appears between the first resonance peak 2031 and the second resonance peak 2032 in curve L203. This is because the resonance peak 2021 compensates for the resonance dip 2013 with the same frequency, so no resonance dip appears between the first resonance peak 2031 and the second resonance peak 2032 in curve L203. Also, within the frequency range greater than 100 Hz, the amplitude of curve L203 is improved compared to curve L201.

[0142] Accordingly, in some embodiments, the third vibration element 180 and the mass element 130 vibrate, and due to the resonance peak generated in the low frequency band (for example, 50 Hz to 2000 Hz) (hereinafter, for convenience of explanation, referred to as the resonance peak corresponding to the third vibration element 180), the resonance dip between the first resonance peak and the second resonance peak generated by the vibration of the vibration element 110 and the mass element 130 (hereinafter, for convenience of explanation, referred to as the resonance dip corresponding to the vibration element 110) is compensated. As a result, the frequency response curve of the acoustic output device 1900 has no resonance dip between the first resonance peak and the second resonance peak, the curve between the first resonance peak and the second resonance peak becomes smoother, and it can contribute to improving the sound quality of the acoustic output device.

[0143] In some embodiments, the ratio of the frequency f0 of the first resonance peak corresponding to the vibration element 110 to the frequency f1 of the second resonance peak may be within the range of 5 to 30. In some embodiments, the ratio of the frequency f0 of the first resonance peak corresponding to the vibration element 110 to the frequency f1 of the second resonance peak may be within the range of 6 to 25. In some embodiments, the ratio of the frequency f0 of the first resonance peak corresponding to the vibration element 110 to the frequency f1 of the second resonance peak may be within the range of 8 to 20. In some embodiments, the ratio of the frequency f0 of the first resonance peak corresponding to the vibration element 110 to the frequency f1 of the second resonance peak may be within the range of 10 to 18.

[0144] In some embodiments, the resonance frequency of the beam structure (for example, the cantilever beam corresponding to the vibration element 110 or the free beam corresponding to the third vibration element 180) can be determined based on Equation (2).

[0145]

Equation

[0146] Here, l represents the length of the beam structure, EI represents the bending rigidity of the beam structure, ρ l represents the unit length density of the beam structure, and β il represents the coefficient related to the i-th resonance eigenvalue. As can be seen from Equation (2), when the bending rigidity EI and ρl of the beam structure do not change, the resonance frequency of the beam structure is β i changes with l.

[0147] In some embodiments, the frequency equation of the vibration element 110 (cantilever beam) connected to the mass element 130 can be expressed as follows.

[0148]

Equation

[0149] Here, α represents the ratio of the mass of the mass element 130 to the mass of the vibration element 110, and β i l1 represents the coefficient related to the i-th resonance eigenvalue corresponding to the cantilever beam. The value of β i l1 obtained by solving Equation (3) is shown in Table 1 below.

[0150]

Table 1

[0151] In some embodiments, the frequency equation of the third vibration element 180 (free beam) can be expressed as follows.

[0152]

Equation

[0153] Here, β i l2 represents the coefficient related to the i-th resonance eigenvalue corresponding to the free beam. The value of β i l2 obtained by solving Equation (4) is 4.730, 7.853… (i = 1, 2…).

[0154] To ensure that the resonance peak corresponding to the third vibration element 180 can compensate for the resonance dip corresponding to the vibration element 110, in some embodiments, the frequency of the resonance peak corresponding to the third vibration element 180

[0155]

Number

[0156] The ratio to the frequency f1 corresponding to the second resonance peak corresponding to the vibration element 110 may be less than 2. In some embodiments, the frequency of the resonance peak corresponding to the third vibration element 180

[0157]

Number

[0158] The ratio to the frequency f1 of the second resonance peak corresponding to the vibration element 110 may be less than 1.5. In some embodiments, the frequency of the resonance peak corresponding to the third vibration element 180

[0159]

Number

[0160] The ratio to the frequency f1 of the second resonance peak corresponding to the vibration element 110 may be less than 1. In some embodiments, the frequency of the resonance peak corresponding to the third vibration element 180

[0161]

Number

[0162] The ratio to the frequency f1 of the second resonance peak corresponding to the vibration element 110 may be less than 0.5. In some embodiments, to ensure that the resonance peak corresponding to the third vibration element 180 can compensate for the resonance dip corresponding to the vibration element 110, the frequency of the resonance peak corresponding to the third vibration element 180

[0163]

Number

[0164] may be located near the frequency of the resonance dip corresponding to the vibration element 110 (for example, the resonance frequencies corresponding to the resonance dip 2013 and the resonance peak 2021 are both about 1330 Hz), whereby the frequency of the resonance peak corresponding to the third vibration element 180

[0165]

Number

[0166] may be smaller than the resonance frequency f1 corresponding to the second resonance peak corresponding to the vibration element 110, that is

[0167]

Number

[0168] Here, the value of β1l2 is 4.730, and Equation (5) can be expressed as follows.

[0169]

Number

[0170] Based on Equation (6) and Table 1, in some embodiments, the ratio of the length of the third vibration element 180 to the length of the vibration element 110 may be greater than 0.7. In some embodiments, the ratio of the length of the third vibration element 180 to the length of the vibration element 110 may be greater than 1. In some embodiments, the ratio of the length of the third vibration element 180 to the length of the vibration element 110 may be greater than 1.2.

[0171] Also, as can be seen from curve L201 and curve L203, within the medium and high frequency band (200 Hz to 20000 Hz), the amplitude of curve L203 is greater than that of curve L201 in all cases. Thus, in some embodiments, within a range greater than 100 Hz, the third vibration element 180 can increase the vibration amplitude of the mass element 130. Therefore, by using the same or a similar structure as the acoustic output device 1900, the acoustic output device can have high sensitivity within the medium and high frequency band.

[0172] FIG. 21 is a frequency response curve diagram of an acoustic output device according to some embodiments of the present specification.

[0173] In FIG. 21, curve L211 is the frequency response curve when the piezoelectric element 120 is independently excited (i.e., the frequency response curve generated when driving the mass element 130 so that the vibration element 110 (or called a cantilever beam) vibrates). Curve L212 is the frequency response curve when the fourth piezoelectric element 190 is independently excited (i.e., the frequency response curve generated when the third vibration element 180 (or called a free beam) and the mass element 130 vibrate). Curves L213, L214, L215, and L216 are the frequency response curves when the piezoelectric element 120 and the fourth piezoelectric element 190 in the acoustic output device 1900 are simultaneously excited, and the phase difference (denoted as theta in the figure) of the excitation signal is 0°, 45°, 135°, and 180°, respectively.

[0174] As can be seen from curve L213, curve L214, curve L215, and curve L216, when the phase difference of the excitation signals between the piezoelectric element 120 and the fourth piezoelectric element 190 in the acoustic output device 1900 exceeds 135°, a resonance dip (for example, resonance dip 2161 in curve L216) appears between the first resonance peak and the second resonance peak in the frequency response curve of the acoustic output device 1900. This is caused by the vibrations of the vibration element 110 and the third vibration element 180 being in antiphase and canceling each other out. Therefore, in order for the frequency response curve of the acoustic output device 1900 to have a large flat curve range without a resonance dip appearing between the first resonance peak and the second resonance peak and thus have high sound quality, in some embodiments, the phase difference of the excitation signals between the piezoelectric element 120 and the fourth piezoelectric element 190 may be 135° or less. In some embodiments, the phase difference of the excitation signals between the piezoelectric element 120 and the fourth piezoelectric element 190 may be 90° or less. In some embodiments, the phase difference of the excitation signals between the piezoelectric element 120 and the fourth piezoelectric element 190 may be 60° or less. In some embodiments, the phase difference of the excitation signals between the piezoelectric element 120 and the fourth piezoelectric element 190 may be 45° or less. In some embodiments, the phase difference of the excitation signals between the piezoelectric element 120 and the fourth piezoelectric element 190 may be 30° or less. In some embodiments, the phase difference of the excitation signals between the piezoelectric element 120 and the fourth piezoelectric element 190 may be 0°.

[0175] FIG. 22 is a frequency response curve diagram of an acoustic output device according to some embodiments of the present specification.

[0176] In FIG. 22, curves L221, L222, L223, L224, and L225 are the frequency response curves when the length of the third vibration element 180 of the acoustic output device 1900 (denoted as lp_d2 in the figure) is 0 mm (i.e., the acoustic output device 1900 does not include the third vibration element 180 and can be regarded as corresponding to the acoustic output device 200), 20 mm, 22 mm, 24 mm, and 30 mm, respectively. The length of the vibration element 110 (denoted as lp_d in the figure) is 20 mm in all cases. As can be seen from curves L221, L222, L223, L224, and L225, when the length of the third vibration element 180 is less than 24 mm, curves L221, L222, and L223 all have resonance dips near 2250 Hz, and with the increase in the length of the third vibration element 180, only the amplitude in the mid-high frequency band (e.g., 2000 Hz to 20000 Hz) of the frequency response curve of the acoustic output device 1900 increases, that is, the sensitivity in the mid-high frequency band of the acoustic output device 1900 can be increased. When the length of the third vibration element 180 exceeds 24 mm, since there is no resonance dip between the first resonance peak and the second resonance peak in curves L224 and L225, the frequency response curve of the acoustic output device 1900 becomes flatter, which is helpful for improving the sound quality. Also, as can be seen from curves L224 and L225, as the length of the third vibration element 180 increases, the amplitude of the frequency response curve also increases, which is helpful for improving the sensitivity of the acoustic output device 1900. Also, as the length of the third vibration element 180 increases, the resonance peak in the mid-high frequency band (e.g., 2000 Hz to 20000 Hz) of the frequency response curve of the acoustic output device 1900 shifts to the left (i.e., shifts to lower frequencies). Thus, by adjusting the length of the third vibration element 180, the requirements for the vibration performance of the acoustic output device 1900 can be met.

[0177] As can be understood from the above, in the acoustic output device 1900, by increasing the length of the third vibrating element 180, the sensitivity and sound quality of the acoustic output device 1900 can be improved. In some embodiments, the length of the vibrating element 110 may be 20 mm, and the length of the third vibrating element 180 may be greater than 24 mm. In some embodiments, the length of the third vibrating element 180 may be greater than 26 mm. In some embodiments, the length of the third vibrating element 180 may be greater than 28 mm. In some embodiments, the length of the third vibrating element 180 may be greater than 30 mm.

[0178] Although the basic concept has been described above, it is obvious to those skilled in the art that the above detailed disclosure is merely presented as an example and does not limit this specification. Although not explicitly described in this specification, those skilled in the art can make various changes, improvements, and modifications to this specification. Since these changes, improvements, and modifications are intended to be suggested by this specification, they are within the spirit and scope of the exemplary embodiments of this specification.

[0179] Furthermore, specific terms are used in this specification to describe the embodiments herein. For example, "one embodiment", "an embodiment", and / or "some embodiments" mean specific features, structures, or characteristics related to at least one embodiment of this specification. Therefore, it should be emphasized and understood that two or more references to "an embodiment" or "one embodiment" or "one alternative embodiment" in various parts of this specification do not necessarily all refer to the same embodiment. Also, the specific features, structures, or characteristics in one or more embodiments of this specification may be appropriately combined.

[0180] Also, unless expressly recited in the claims, the recited order of process elements or sequences, the use of alphanumerics, or the use of other names in this specification do not limit the order of the procedures and methods in this specification. In the above disclosure, various useful embodiments of the invention, which are currently considered, are described through various examples. However, such details are for illustrative purposes only. The appended claims are not limited to the disclosed embodiments, but rather are intended to cover all modifications and equivalent combinations within the spirit and scope of the embodiments in this specification. For example, the system assembly described above may be implemented by a hardware device, but may also be implemented by a software-only solution, for example, by installing the system described on an existing server or mobile device.

[0181] Similarly, in the foregoing description of the embodiments in this specification, it should be understood that for the purpose of simplifying this specification and facilitating the understanding of one or more embodiments of the invention, various features may be grouped in one embodiment, drawing, or its description. However, such a disclosure method should not be construed as reflecting an intention that the claimed subject matter requires more features than those recited in each claim. In fact, the features of an embodiment may be fewer than all the features of the single embodiment disclosed above.

[0182] In some embodiments, numbers are used to describe the number of components and attributes, and it should be understood that the numbers for describing such embodiments are modified by the modifier "about", "substantially" or "generally" in some examples. Unless otherwise specified, "about", "substantially" or "generally" indicates that the above numbers are allowed a variation of ±20%. Therefore, in some embodiments, the numerical parameters used in the specification and claims are all approximate values that can vary according to the characteristics required by individual embodiments. In some embodiments, for numerical parameters, the defined number of significant digits should be considered and the normal rounding method should be applied. In some embodiments of this specification, the numerical ranges and parameters for determining the range are approximate values, but in specific embodiments, such numbers are set as accurately as possible.

[0183] Finally, it should be understood that the embodiments described in this specification are merely for explaining the principles of the embodiments of this specification. Other variations may also be within the scope of this specification. Therefore, without limitation, by way of example, alternative configurations of the embodiments of this specification may be considered to be in accordance with the teachings of this specification. Thus, the embodiments of this specification are not limited to the embodiments clearly introduced and described in this specification.

Description of Reference Numerals

[0184] 100 Acoustic output device 110 Vibration element 111 Fixed end 112 Free end 120 Piezoelectric element 130 Mass element 140 Second piezoelectric element 150 Second mass element 160 Second vibration element 170 Third piezoelectric element 180 Third vibration element 190 Fourth piezoelectric element 200 Acoustic output device 210 Housing structure 220 Fixing structure 300 Audio output device 400 Audio output device 621 First resonance peak 622 Second resonance peak 700 Audio output device 900 Audio output device 1700 Audio output device

Claims

1. A vibration element having a beam structure extending along a longitudinal direction, A piezoelectric element that deforms in response to an electrical signal, drives the vibration element so that the deformation vibrates, the piezoelectric element is attached to a first position of the beam structure, and a size along the longitudinal direction of the attachment region does not exceed 60% of the size along the longitudinal direction of the beam structure, a piezoelectric element, A mass element connected to a second position of the beam structure, wherein the first position and the second position are distributed at intervals along the longitudinal direction, and drives the mass element so that the vibration of the vibration element vibrates in a direction perpendicular to the longitudinal direction, a mass element, an acoustic output device including, The deformation direction of the piezoelectric element is perpendicular to the vibration direction of the vibration element, the acoustic output device further includes a second piezoelectric element attached to a third position of the beam structure, and the piezoelectric element and the second piezoelectric element are provided at intervals along the longitudinal direction of the vibration element, an acoustic output device characterized by this.

2. The vibration element resonates with the mass element to generate a first resonance peak, and a frequency range of the first resonance peak is 50 Hz to 2000 Hz, the acoustic output device according to claim 1, characterized by this.

3. The vibrations of the vibration element and the mass element have a second resonance peak, and a ratio of a frequency of the second resonance peak to a frequency of the first resonance peak is greater than 5, the acoustic output device according to claim 2, characterized by this.

4. The vibrations of the vibration element and the mass element generate at least one resonance dip between the first resonance peak and the second resonance peak, and an amplitude difference between the first resonance peak or the second resonance peak and the at least one resonance dip is less than 80 dB, the acoustic output device according to claim 3, characterized by this.

5. A vibration element having a beam structure extending along a longitudinal direction, A piezoelectric element that deforms in response to an electrical signal, drives the vibration element so that the deformation vibrates, the piezoelectric element is attached to a first position of the beam structure, and a size along the longitudinal direction of the attachment region does not exceed 60% of the size along the longitudinal direction of the beam structure, a piezoelectric element, A mass element connected to the second position of the beam structure, wherein the first position and the second position are distributed at intervals in the longitudinal direction, and the mass element is driven such that the vibration of the vibration element vibrates in a direction perpendicular to the longitudinal direction, a mass element; A second vibration element, wherein the vibration element and the second vibration element are symmetrically provided on both sides of the mass element, and an acoustic output device characterized by this. **Claim 6** The acoustic output device according to claim 5, further comprising a third piezoelectric element connected to the second vibration element, wherein the third piezoelectric element and the piezoelectric element are symmetrically provided on both sides of the mass element. **Claim 7** The acoustic output device according to claim 6, wherein one end of the vibration element and the second vibration element away from the mass element is fixedly provided. **Claim 8** A vibration element having a beam structure extending along a longitudinal direction, A piezoelectric element that deforms in response to an electrical signal, wherein the vibration element is driven such that the deformation vibrates, the piezoelectric element is attached to the first position of the beam structure, and the size along the longitudinal direction of the attachment region does not exceed 60% of the size along the longitudinal direction of the beam structure, a piezoelectric element; A mass element connected to the second position of the beam structure, wherein the first position and the second position are distributed at intervals in the longitudinal direction, and the mass element is driven such that the vibration of the vibration element vibrates in a direction perpendicular to the longitudinal direction, a mass element; An acoustic output device including a third vibration element connected to the mass element and having a vibration direction parallel to the vibration direction of the vibration element. **Claim 9** The acoustic output device according to claim 8, further comprising a fourth piezoelectric element connected to the third vibration element. **Claim 10** The acoustic output device according to claim 9, wherein the deformation direction of the fourth piezoelectric element is perpendicular to the vibration direction of the third vibration element. **Claim 11** The acoustic output device according to claim 9, wherein the electrical signals received by the piezoelectric element and the fourth piezoelectric element have a phase difference smaller than 135°.

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