Bone conduction acoustic transmission device

Abstract

The bone conduction acoustic transmission device of the present application includes a laminated structure formed of a vibration unit and an acoustic conversion unit, and a base structure configured to place the laminated structure and physically connected to at least one side of the laminated structure, wherein the base structure vibrates based on an external vibration signal, the vibration unit deforms in response to the vibration of the base structure, and the acoustic conversion unit generates an electrical signal based on the deformation of the vibration unit.

Description

[Technical Field]

[0001] The present application relates to the technical field of sound transmission devices, and more particularly to bone conduction sound transmission devices.

[0002] (Incorporated by reference) This application claims priority from International Application PCT / CN2020 / 142533, filed December 31, 2020, the entire contents of which are incorporated herein by reference. [Background technology]

[0003] A microphone receives external vibration signals, converts the vibration signals into electrical signals using an acoustic transducer, and outputs the electrical signals after processing by a back-end circuit. An air conduction microphone receives air-conducted sound signals, which are sound signals propagated through the air, i.e., air conduction microphones receive air vibration signals. A bone conduction microphone receives bone-conducted sound signals, which are sound signals propagated through the bones of the human body, i.e., bone conduction microphones receive bone vibration signals. Compared to air conduction microphones, bone conduction microphones have an advantage in noise resistance, and in noisy environments, bone conduction microphones are less affected by environmental noise and can better capture human voices. Summary of the Invention [Problem to be solved by the invention]

[0004] Conventional bone conduction microphones have a complex structure, high manufacturing requirements, and insufficient connection strength of some devices, resulting in low reliability and affecting output. Therefore, there is a need to provide a bone conduction acoustic transmission device with a simple structure and high stability. [Means for solving the problem]

[0005] A bone conduction acoustic transmission device according to one aspect of the present application includes a laminated structure formed of a vibration unit and an acoustic conversion unit, and a base structure configured to support the laminated structure and physically connected to at least one side of the laminated structure, wherein the base structure vibrates based on an external vibration signal, the vibration unit deforms in response to the vibration of the base structure, and the acoustic conversion unit generates an electrical signal based on the deformation of the vibration unit.

[0006] In some embodiments, the base structure includes a hollow frame structure, and the laminate structure has one end connected to the base structure and the other end suspended in the hollow portion of the frame structure.

[0007] In some embodiments, the vibration unit includes at least one elastic layer, and the acoustic transducer unit includes at least a first electrode layer, a piezoelectric layer, and a second electrode layer arranged in order from top to bottom, and the at least one elastic layer is located on the upper surface of the first electrode layer or the lower surface of the second electrode layer.

[0008] In some embodiments, the acoustic transducer unit further includes a seed layer located on a lower surface of the second electrode layer.

[0009] In some embodiments, the coverage area of the first electrode layer, the piezoelectric layer, and / or the second electrode layer is less than or equal to the area of the laminated structure, and the first electrode layer, the piezoelectric layer, and / or the second electrode layer are adjacent to the connection point between the laminated structure and the base structure.

[0010] In some embodiments, the vibration unit includes at least one elastic layer, and the acoustic transducer unit includes at least an electrode layer and a piezoelectric layer, and the at least one elastic layer is located on a surface of the electrode layer.

[0011] In some embodiments, the electrode layer includes a first electrode and a second electrode, the first electrode folded into a first comb-like structure, the second electrode folded into a second comb-like structure, the first comb-like structure interdigitating with the second comb-like structure to form the electrode layer, and the electrode layer is located on an upper surface or a lower surface of the piezoelectric layer.

[0012] In some embodiments, the first comb-like structure and the second comb-like structure extend along the longitudinal direction of the laminated structure.

[0013] In some embodiments, the vibration unit includes a suspension membrane structure, and the acoustic transducer unit includes a first electrode layer, a piezoelectric layer, and a second electrode layer arranged in order from top to bottom, the suspension membrane structure is connected to the base structure by its periphery, and the acoustic transducer unit is located on the upper or lower surface of the suspension membrane structure.

[0014] In some embodiments, the suspension membrane structure comprises a plurality of holes distributed along the circumferential direction of the acoustic transducer unit.

[0015] In some embodiments, the radial spacing from the edge of the acoustic transducer unit to the centers of the holes is between 100 μm and 400 μm.

[0016] In some embodiments, the acoustic transducer unit is an annular structure, and the thickness of the suspension membrane structure at an inner region of the annular structure is greater than the thickness of the suspension membrane structure at an outer region of the annular structure.

[0017] In some embodiments, the acoustic transducer unit is an annular structure, and the density of the suspension membrane structure in an inner region of the annular structure is greater than the density of the suspension membrane structure in an outer region of the annular structure.

[0018] In some embodiments, the vibration unit further comprises a mass element located on an upper or lower surface of the suspension membrane structure.

[0019] In some embodiments, the acoustic transducer unit and the mass element are located on different sides of the suspension membrane structure.

[0020] In some embodiments, the acoustic transducer unit and the mass element are located on the same side of the suspension membrane structure, the acoustic transducer unit is an annular structure, and the annular structure is distributed along the circumferential direction of the mass element.

[0021] In some embodiments, the vibration unit comprises at least one support arm and a mass element, the mass element being connected to the base structure by the at least one support arm.

[0022] In some embodiments, the at least one support arm includes at least one elastic layer, and the acoustic transducer unit is located on an upper surface, a lower surface, or inside the at least one support arm.

[0023] In some embodiments, the acoustic transducer unit includes a first electrode layer, a piezoelectric layer, and a second electrode layer arranged in order from top to bottom, and the first electrode layer or the second electrode layer is connected to an upper surface or a lower surface of the at least one support arm.

[0024] In some embodiments, the mass element is located on an upper or lower surface of the first electrode layer or the second electrode layer.

[0025] In some embodiments, the area of the first electrode layer, the piezoelectric layer and / or the second electrode layer is less than or equal to the area of the support arm, and some or all of the first electrode layer, the piezoelectric layer and / or the second electrode layer covers an upper or lower surface of the at least one support arm.

[0026] In some embodiments, the area of the first electrode layer is equal to or less than the area of the piezoelectric layer, and the entire area of the first electrode layer is located on the surface of the piezoelectric layer.

[0027] In some embodiments, the first electrode layer, the piezoelectric layer and the second electrode layer of the acoustic transducer unit are proximate to a connection point between the mass element and / or the support arm and the base structure.

[0028] In some embodiments, the at least one support arm includes at least one elastic layer located on an upper or lower surface of the first electrode layer or the second electrode layer.

[0029] In some embodiments, the device further comprises a stop structure located in the hollow portion of the base structure, the stop structure connected to the base structure and located above and / or below the mass element.

[0030] In some embodiments, the bone conduction acoustic transmission device according to any one of the preceding claims further comprises at least one damping layer coating the upper surface, the lower surface and / or the interior of the laminate structure.

[0031] In some embodiments, the bone conduction acoustic transmission device has a resonance frequency of 1 kHz to 5 kHz.

[0032] In some embodiments, the bone conduction acoustic transmission device has a resonance frequency of 2.5 kHz to 4.5 kHz.

[0033] In some embodiments, the bone conduction acoustic transmission device has a resonance frequency of 2.5 KHz to 3.5 kHz.

[0034] In some embodiments, the resonant frequency of the bone conduction acoustic transmission device is positively correlated with the stiffness of the vibration unit.

[0035] In some embodiments, the resonant frequency of the bone conduction acoustic transmission device is negatively correlated with the mass of the laminate structure.

[0036] In some embodiments, the vibration unit comprises at least one support arm and a mass element, the mass element being connected to the base structure by the at least one support arm.

[0037] In some embodiments, the acoustic transducer unit is located on an upper surface, a lower surface, or inside the at least one support arm.

[0038] In some embodiments, the acoustic transducer unit includes a first electrode layer, a first piezoelectric layer, and a second electrode layer arranged in order from top to bottom, and the first electrode layer or the second electrode layer is connected to an upper surface or a lower surface of the at least one support arm.

[0039] In some embodiments, the mass element is located on an upper or lower surface of the first electrode layer or the second electrode layer.

[0040] In some embodiments, the area of the first electrode layer, the first piezoelectric layer and / or the second electrode layer is less than or equal to the area of the support arm, and some or all of the first electrode layer, the first piezoelectric layer and / or the second electrode layer covers an upper or lower surface of the at least one support arm.

[0041] In some embodiments, the area of the first electrode layer is equal to or less than the area of the first piezoelectric layer, and the entire area of the first electrode layer is located on the surface of the first piezoelectric layer.

[0042] In some embodiments, the first electrode layer, the first piezoelectric layer, and the second electrode layer of the acoustic transducer unit are located at one end of the support arm connected to the mass element and / or at one end of the support arm connected to the base structure.

[0043] In some embodiments, the acoustic transducer unit includes at least one elastic layer located on an upper and / or lower surface of the first electrode layer or the second electrode layer.

[0044] In some embodiments, the acoustic transducer unit further includes a first seed layer disposed between the elastic layer and the first electrode layer or between the elastic layer and the second electrode layer.

[0045] In some embodiments, the acoustic transducer unit further includes at least one bonding wire electrode layer, the bonding wire electrode layer being attached to the base structure and adapted to derive an electrical signal from the base structure.

[0046] In some embodiments, the elastic layer is disposed between the support arm and the first electrode layer, and the first seed layer is disposed between the elastic layer and the first electrode layer, or the elastic layer is disposed between the support arm and the second electrode layer, and the first seed layer is disposed between the elastic layer and the second electrode layer.

[0047] In some embodiments, the bone conduction acoustic transmission device has a neutral layer formed therein, the neutral layer having zero deformation stress when the support arm is deformed, and the neutral layer does not overlap with the first piezoelectric layer in the thickness direction.

[0048] In some embodiments, the first electrode layer has a thickness of 80 nm to 250 nm and / or the second electrode layer has a thickness of 80 nm to 250 nm.

[0049] In some embodiments, the first piezoelectric layer has a thickness of 0.8 μm to 2 μm.

[0050] In some embodiments, the elastic layer has a thickness of 0.5 μm to 10 μm.

[0051] In some embodiments, the first seed layer has a thickness of 10 nm to 120 nm.

[0052] In some embodiments, the thickness of the elastic layer is 1 to 6 times the thickness of the first piezoelectric layer.

[0053] In some embodiments, the mass element has a thickness between 1 μm and 400 μm.

[0054] In some embodiments, the mass element includes, in order from bottom to top, a base layer, a third electrode layer, a second piezoelectric layer, and a fourth electrode layer.

[0055] In some embodiments, the mass element further includes a second seed layer disposed between the foundation layer and the third electrode layer.

[0056] In some embodiments, the underlayer has a thickness of 20 μm to 400 μm.

[0057] In some embodiments, the ratio of the intensity of the electric signal to the intensity of the noise of the bone conduction acoustic transmission device is 50% to 100% of the maximum value of the ratio of the intensity of the electric signal to the intensity of the noise.

[0058] In some embodiments, the acoustic transducer unit includes a first electrode layer, a first piezoelectric layer, and a second electrode layer, and the ratio of the electrical signal strength to the noise strength of the bone conduction acoustic transmission device is negatively correlated with the thickness of the first piezoelectric layer.

[0059] In some embodiments, the acoustic transducer unit includes a first electrode layer, a first piezoelectric layer, and a second electrode layer, and the ratio of the electrical signal strength to the noise strength of the bone conduction acoustic transmission device is negatively correlated with the area of the overlapping region of the first electrode layer, the first piezoelectric layer, and the second electrode layer.

[0060] In some embodiments, the acoustic transducer unit includes a first electrode layer, a first piezoelectric layer, and a second electrode layer, and the ratio of the area of the overlapping region of the first electrode layer, the first piezoelectric layer, and the second electrode layer to the area of a cross section perpendicular to the thickness direction of the support arm is 5% to 40%.

[0061] In some embodiments, the first electrode layer or the second electrode layer is provided with an electrode isolation channel that divides the first electrode layer or the second electrode layer into two or more electrode regions.

[0062] In some embodiments, the width of the electrode insulating channel is less than or equal to 20 μm.

[0063] In some embodiments, the first electrode layer or the second electrode layer has an electrode lead connecting the electrode region to the base structure.

[0064] In some embodiments, the electrode lead has a width of 20 μm or less.

[0065] In some embodiments, the overlapping region of the first electrode layer, the first piezoelectric layer, and the second electrode layer extends toward the mass element to form an extension region, the extension region being located on an upper or lower surface of the mass element.

[0066] In some embodiments, the width of the extension region in a plane perpendicular to the thickness direction is 1.2 to 2 times the width of the connection portion between the support arm and the mass element in a plane perpendicular to the thickness direction.

[0067] In some embodiments, the number of support arms is two or more, and the two or more support arms are positioned around the mass element.

[0068] In some embodiments, the at least one support arm has a cross-sectional shape perpendicular to its thickness direction that is polygonal.

[0069] In some embodiments, the polygon has a side length of 100 to 600 μm.

[0070] In some embodiments, the at least one support arm has a rectangular or trapezoidal cross-sectional shape perpendicular to its thickness direction.

[0071] In some embodiments, the shape of a cross section perpendicular to the thickness direction of the mass element is a polygon, and the number of support arms corresponds to the number of sides of the polygon.

[0072] In some embodiments, when the cross section of the support arm perpendicular to the thickness direction has a rectangular shape, the support arm has a length of 100 μm to 500 μm and a width of 150 μm to 400 μm.

[0073] In some embodiments, when the cross-sectional shape of the at least one support arm perpendicular to the thickness direction is trapezoidal, the height of the trapezoid is 150 μm to 600 μm, the length of the long side of the trapezoid is 300 μm to 600 μm, and the length of the short side of the trapezoid is 100 μm to 400 μm.

[0074] In some embodiments, the support arm includes a first strip and a second strip, one end of the first strip connected to the mass element and the other end connected to one end of the second strip, and the other end of the second strip connected to the base structure.

[0075] In some embodiments, the length of the first strip is between 20 μm and 200 μm, and the width of the first strip is between 50 μm and 400 μm.

[0076] In some embodiments, the length of the second strip is between 500 μm and 1300 μm, and the width of the second strip is between 50 μm and 400 μm.

[0077] In some embodiments, when the connection point between the first strip and the mass element is located at the end of a side edge of the mass element, the width of the first strip is 50 μm to 300 μm, and the length of the first strip is 20 μm to 200 μm.

[0078] In some embodiments, when the connection point between the first strip and the mass element is located at the end of a side edge of the mass element, the width of the second strip is 50 μm to 300 μm, and the length of the second strip is 800 μm to 1300 μm.

[0079] In some embodiments, when the connection point between the first strip portion and the mass element is located at the midpoint of a side of the mass element, the width of the first strip portion is 100 μm to 400 μm, and the length of the first strip portion is 20 μm to 200 μm.

[0080] In some embodiments, when the connection point between the first strip and the mass element is located at the midpoint of a side of the mass element, the width of the second strip is 100 μm to 400 μm, and the length of the second strip is 500 μm to 1000 μm.

[0081] In some embodiments, the cross section of the mass element perpendicular to the thickness direction is rectangular, and the first strip is perpendicular to the second strip.

[0082] In some embodiments, the support arm includes a first strip, a second strip, and a third strip, wherein one end of the first strip is connected to the mass element and the other end is connected to one end of the second strip, the other end of the second strip is connected to one end of the third strip, and the other end of the third strip is connected to the base structure.

[0083] In some embodiments, the length of the first strip is between 20 μm and 200 μm, and the width of the first strip is between 50 μm and 300 μm.

[0084] In some embodiments, the length of the second strip is between 500 μm and 1200 μm, and the width of the second strip is between 50 μm and 300 μm.

[0085] In some embodiments, the third strip has a length of 800 μm to 1300 μm and a width of 50 μm to 300 μm.

[0086] In some embodiments, the base structure includes a frame structure having a hollow cavity, and the support arm and the mass element are both located within the cavity of the frame structure.

[0087] In some embodiments, the shape of the mass element corresponds to the shape of the cavity.

[0088] In some embodiments, the sum of the thicknesses of the support arm and the acoustic transducer unit is less than the thickness of the mass element.

[0089] In some embodiments, the sum of the thicknesses of the support arm and the acoustic transducer unit is greater than or equal to the thickness of the mass element.

[0090] In some embodiments, the bone conduction acoustic transmission device further includes a stop structure located within the cavity of the base structure, the stop structure being connected to the base structure and located above and / or below the mass element.

[0091] The present application will be further illustrated by exemplary embodiments, which are not limiting and will be described in detail with reference to the drawings, in which like reference numerals refer to like structures. [Brief explanation of the drawings]

[0092] [Figure 1] 1 is a schematic diagram illustrating the configuration of a bone conduction acoustic transmission device according to some embodiments of the present application. [Figure 2] 2 is a cross-sectional view of the bone conduction acoustic transmission device shown in FIG. 1 taken along line AA. [Figure 3] FIG. 1 is a schematic diagram of another bone conduction acoustic transmission device according to some embodiments of the present application. [Figure 4]FIG. 10 is a schematic diagram illustrating the configuration of a bone conduction acoustic transmission device according to some other embodiments of the present application. [Figure 5] 1 is a schematic diagram illustrating the configuration of a bone conduction acoustic transmission device according to some embodiments of the present application. [Figure 6] 6 is a cross-sectional view of a partial structure of the bone conduction acoustic transmission device shown in FIG. 5. [Figure 7] 1 is a schematic diagram illustrating the configuration of a bone conduction acoustic transmission device according to some embodiments of the present application. [Figure 8] 1 is a schematic diagram illustrating the configuration of a bone conduction acoustic transmission device according to some embodiments of the present application. [Figure 9] FIG. 9 is a front view of the bone conduction acoustic transmission device shown in FIG. 8. [Figure 10] 10 is a cross-sectional view of the bone conduction acoustic transmission device shown in FIG. 9 taken along the line CC. [Figure 11] FIG. 9 is a front view of the bone conduction acoustic transmission device in a vibrating state shown in FIG. 8. [Figure 12] 12 is a cross-sectional view of the bone conduction acoustic transmission device shown in FIG. 11 taken along the line DD. [Figure 13] FIG. 9 is a schematic diagram illustrating the configuration of the bone conduction acoustic transmission device shown in FIG. 8. [Figure 14] 9 is another schematic diagram of the bone conduction acoustic transmission device shown in FIG. 8. FIG. [Figure 15] FIG. 9 is a schematic diagram illustrating yet another configuration of the bone conduction acoustic transmission device shown in FIG. 8. [Figure 16] FIG. 9 is a schematic diagram illustrating yet another configuration of the bone conduction acoustic transmission device shown in FIG. 8. [Figure 17] 1 is a schematic diagram illustrating the configuration of a bone conduction acoustic transmission device according to some embodiments of the present application. [Figure 18] 18 is a cross-sectional view of the bone conduction acoustic transmission device shown in FIG. 17 taken along the line EE. [Figure 19] FIG. 18 is a schematic diagram illustrating the configuration of the bone conduction acoustic transmission device shown in FIG. [Figure 20] FIG. 18 is another schematic diagram of the bone conduction acoustic transmission device shown in FIG. 17. [Figure 21] 1 is a schematic diagram illustrating the configuration of a bone conduction acoustic transmission device according to some embodiments of the present application. [Figure 22] FIG. 22 is a schematic diagram illustrating the configuration of the bone conduction acoustic transmission device shown in FIG. 21. [Figure 23] 1 is a schematic diagram illustrating the configuration of a bone conduction acoustic transmission device according to some embodiments of the present application. [Figure 24] FIG. 24 is a front view of the bone conduction acoustic transmission device shown in FIG. 23. [Figure 25] 25 is a cross-sectional view of the bone conduction acoustic transmission device shown in FIG. 24 taken along the line FF. [Figure 26] FIG. 24 is a schematic diagram illustrating the configuration of the bone conduction acoustic transmission device shown in FIG. 23. [Figure 27] FIG. 24 is another schematic diagram of the bone conduction acoustic transmission device shown in FIG. 23. [Figure 28] FIG. 24 is a schematic diagram illustrating yet another configuration of the bone conduction acoustic transmission device shown in FIG. 23. [Figure 29] FIG. 24 is a schematic diagram illustrating yet another configuration of the bone conduction acoustic transmission device shown in FIG. 23. [Figure 30] FIG. 10 is a schematic diagram illustrating the configuration of a bone conduction acoustic transmission device according to some other embodiments of the present application. [Figure 31] 1 is a schematic diagram illustrating the configuration of a bone conduction acoustic transmission device according to some embodiments of the present application. [Figure 32] FIG. 10 is a schematic diagram illustrating the configuration of a bone conduction acoustic transmission device according to some other embodiments of the present application. [Figure 33] FIG. 33 is another schematic diagram of the bone conduction acoustic transmission device shown in FIG. 32. [Figure 34] 10 is a frequency response curve of a laminate structure with reduced natural frequency according to some embodiments of the present application; [Figure 35] 1 is a frequency response curve diagram of a bone conduction acoustic transmission device with and without a damping structure layer, according to some embodiments of the present application; [Figure 36] 1 is a cross-sectional view of a bone conduction acoustic transmission device according to some embodiments of the present application. [Figure 37] 1 is a cross-sectional view of a bone conduction acoustic transmission device according to some embodiments of the present application. [Figure 38] 1 is a cross-sectional view of a bone conduction acoustic transmission device according to some embodiments of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0093] In order to more clearly explain the technical means of the embodiments of the present application, the drawings necessary for the description of the embodiments will be briefly described below. Obviously, the drawings described below are only examples or parts of the embodiments of the present application, and those skilled in the art can apply the present application to other similar scenarios based on these drawings without any creative effort. Unless otherwise clear or specified in the language environment, the same reference numerals in the drawings indicate the same structures or operations. It should be understood that the drawings are for illustration and explanation only and are not intended to limit the scope of the present application. It should be understood that the drawings are not drawn to scale.

[0094] It should be understood that for ease of explanation of this application, positional relationships indicated by terms such as "center," "upper surface," "lower surface," "upper," "lower," "top," "bottom," "inner," "outer," "axial," "radial," "periphery," "external," etc. are based on positional relationships shown in the drawings, and do not indicate that the devices, assemblies, or units referred to must have a particular positional relationship, and should not be understood as limiting this application.

[0095] It should be understood that the terms "system," "device," "unit," and / or "module" used herein are ways of distinguishing between various levels of assemblies, elements, components, parts, or structures. However, other terms may be used in place of the above terms if they achieve the same purpose.

[0096] As used in this application and the claims, unless the context clearly dictates otherwise, terms such as "a," "one," "one kind," and / or "the" do not specifically refer to the singular but may include the plural. In general, the terms "comprise" and "containing" only indicate the inclusion of explicitly identified steps and elements, and these steps and elements are not an exclusive list, and a method or apparatus may include other steps or elements.

[0097] Flowcharts are used herein to describe operations performed by systems according to embodiments of the present invention. It should be understood that the preceding and following operations are not necessarily performed in exact order. Instead, steps may be performed in reverse order or simultaneously. Other operations may also be added to these processes, or one or more operations may be removed from these processes.

[0098] A bone conduction acoustic transmission device according to some embodiments of the present application may include a base structure and a laminated structure. In some embodiments, the base structure may be a regular or irregular three-dimensional structure having a hollow portion therein, such as a hollow frame structure, including, but not limited to, regular shapes such as a rectangular frame, a circular frame, a regular polygonal frame, and any irregular shape. The laminated structure may be located in the hollow portion of the base structure or may be at least partially suspended above the hollow portion of the base structure. In some embodiments, at least a portion of the laminated structure is physically connected to the base structure. Here, "connected" may be understood as fixedly connecting the laminated structure and the base structure after manufacturing them, such as by welding, riveting, fastening, or bolting, or by depositing the laminated structure on the base structure by physical deposition (e.g., physical vapor deposition) or chemical deposition (e.g., chemical vapor deposition) during manufacturing. In some embodiments, at least a portion of the laminated structure may be fixed to the upper or lower surface of the base structure or to a sidewall of the base structure. For example, the laminated structure may be a cantilever beam, which may be a plate-like structure, with one end connected to the upper or lower surface of the base structure or to a sidewall of the hollow portion of the base structure and the other end not connected to or in contact with the base structure, thereby being suspended in the hollow portion of the base structure. For example, the laminated structure may include a vibrating membrane layer (also called a suspension membrane structure), which is fixedly connected to the base structure, and the laminated structure is mounted on the upper or lower surface of the suspension membrane structure. For example, the laminated structure may include a mass element and one or more support arms, which are fixedly connected to the base structure by one or more support arms, with one end of the support arm connected to the base structure and the other end of the support arm connected to the mass element, thereby suspending the mass element and a partial region of the support arm in the hollow portion of the base structure.It should be understood that the terms "located in the hollow portion of the base structure" or "suspended in the hollow portion of the base structure" referred to herein may mean suspended within, below, or above the hollow portion of the base structure. In some embodiments, the laminated structure may include a vibration unit and an acoustic transducer unit. Specifically, the base structure can vibrate based on an external vibration signal, the vibration unit deforms in response to the vibration of the base structure, and the acoustic transducer unit generates an electrical signal based on the deformation of the vibration unit. It should be understood that the description of the vibration unit and the acoustic transducer unit herein is merely for the purpose of easily explaining the operating principle of the laminated structure and is not intended to limit the actual configuration and structure of the laminated structure. In fact, the vibration unit may not be required, and its function can be entirely realized by the acoustic transducer unit. For example, certain modifications to the structure of the acoustic transducer unit may cause the acoustic transducer unit to generate an electrical signal directly in response to the vibration of the base structure.

[0099] The vibration unit is a part of the laminated structure that is easily deformed by an external force or an inertial force, and the vibration unit can transmit the deformation due to the external force or the inertial force to the acoustic transducer unit. In some embodiments, the vibration unit and the acoustic transducer unit are stacked to form the laminated structure. The acoustic transducer unit may be located on an upper layer of the vibration unit or on a lower layer of the vibration unit. For example, when the laminated structure has a cantilever structure, the vibration unit may include at least one elastic layer, and the acoustic transducer unit may include a first electrode layer, a piezoelectric layer, and a second electrode layer arranged in this order from top to bottom, where the elastic layer is located on a surface of the first electrode layer or the second electrode layer, the elastic layer can deform during vibration, the piezoelectric layer can generate an electrical signal based on the deformation of the elastic layer, and the first electrode layer and the second electrode layer can collect the electrical signal. For example, the vibration unit may be a suspension membrane structure, and the suspension membrane structure near the acoustic transducer unit may be easily deformed by an external force by changing the density of a specific region of the suspension membrane structure, drilling holes in the suspension membrane structure, or installing a counterweight (also called a mass element) on the suspension membrane structure, thereby driving the acoustic transducer unit to generate an electrical signal. For example, the vibration unit may include at least one support arm and a mass element, and the mass element is suspended in a hollow portion of the base structure by the support arm, and when the base structure vibrates, the support arm and the mass element of the vibration unit move relative to the base structure, and the support arm deforms, acting on the acoustic transducer unit to generate an electrical signal.

[0100] The acoustic transducer unit is a portion of the laminated structure that converts deformation of the vibration unit into an electrical signal. In some embodiments, the acoustic transducer unit may include at least two electrode layers (e.g., a first electrode layer and a second electrode layer) and a piezoelectric layer, and the piezoelectric layer may be located between the first electrode layer and the second electrode layer. The piezoelectric layer is a structure that can generate a voltage across both ends thereof when subjected to an external force. In some embodiments, the piezoelectric layer may be a piezoelectric polymer film obtained by a semiconductor deposition process (e.g., magnetron sputtering, MOCVD). In the embodiments herein, the piezoelectric layer can generate a voltage due to the deformation stress of the vibration unit, and the first electrode layer and the second electrode layer can collect the voltage (electrical signal). In some embodiments, the material of the piezoelectric layer may include a piezoelectric film material, and the piezoelectric film material may be a film material (e.g., AlN, PZT film material) manufactured by a deposition process (e.g., magnetron sputtering deposition process, chemical vapor deposition process, etc.). In other embodiments, the material of the piezoelectric layer may include a piezoelectric crystal material and a piezoelectric ceramic material. The piezoelectric crystal is a piezoelectric single crystal. In some embodiments, the piezoelectric crystal material may include quartz, zinc blende, boron, tourmaline, zincite, GaAs, barium titanate and its derivative crystals, KH2PO4, NaKC4H4O6·4H2O (Rochelle salt), etc., or any combination thereof. The piezoelectric ceramic material may be a piezoelectric polycrystal formed by randomly assembling fine grains obtained by solid-state reaction and sintering between powders of different materials. In some embodiments, the piezoelectric ceramic material may include barium titanate (BT), lead zirconate titanate (PZT), lead barium lithium niobate (PBLN), modified lead titanate, aluminum nitride (AIN), zinc oxide (ZnO), or any combination thereof. In some embodiments, the material of the piezoelectric layer may be a piezoelectric polymer material, such as polyvinylidene fluoride (PVDF).

[0101] In some embodiments, the base structure and the laminated structure may be located within a housing of the bone conduction acoustic transmission device, with the base structure fixedly connected to an inner wall of the housing and the laminated structure mounted on the base structure. When the housing of the bone conduction acoustic transmission device vibrates due to an external force (e.g., when a person speaks, the housing vibrates due to vibration of the face), the vibration of the housing vibrates the base structure, and when the vibration unit deforms, the piezoelectric layer of the acoustic transduction unit generates a potential difference (voltage) due to the deformation stress of the vibration unit, and at least two electrode layers (e.g., a first electrode layer and a second electrode layer) located on the upper and lower surfaces of the piezoelectric layer in the acoustic transduction unit, respectively, can collect the potential difference and convert the external vibration signal into an electrical signal. For illustrative purposes only, the bone conduction audio transmission device described in the embodiments of the present application may be applied to earphones (e.g., bone conduction earphones or air conduction earphones), glasses, virtual reality devices, helmets, etc. The bone conduction audio transmission device may be placed on the head (e.g., face), neck, near the ears, or on the top of the head, and the bone conduction audio transmission device can collect sound by picking up bone vibration signals when a person speaks and converting them into electrical signals. Note that the base structure is not limited to a structure independent of the housing of the bone conduction audio transmission device, and in some embodiments, the base structure may be part of the housing of the bone conduction audio transmission device.

[0102] A bone conduction acoustic transmission device receives an external vibration signal, converts the vibration signal into an electrical signal using a laminated structure (including an acoustic transducer unit and a vibration unit), and outputs the electrical signal after processing using a back-end circuit. When a bone conduction acoustic transmission device is operated by an external vibration signal and the acting frequency of the external force is the same as or very close to the system's natural oscillation frequency, the phenomenon of a sharp increase in amplitude is called resonance, and the frequency at which resonance occurs is called the "resonance frequency." A bone conduction acoustic transmission device has a natural frequency, and when the frequency of an external vibration signal is close to the natural frequency, the laminated structure generates a large amplitude and outputs a large electrical signal. Therefore, the response of the bone conduction acoustic transmission device to external vibration can be expressed as a resonance peak occurring near the natural frequency. Therefore, the resonant frequency of the bone conduction acoustic transmission device is substantially numerically equal to the natural frequency. In some embodiments, the natural frequency of the bone conduction acoustic transmission device may be the natural frequency of the laminated structure. In some embodiments, the natural frequency of the laminated structure is in the range of 2.5 kHz to 4.5 kHz. In some embodiments, since bone conduction signals in the human body rapidly decay after exceeding 1 kHz, it is desirable to adjust the resonant frequency of the bone conduction acoustic transmission device (or the natural frequency of the laminated structure) to the audio frequency range of 1 kHz to 5 kHz. In some embodiments, the resonant frequency of the bone conduction acoustic transmission device is 2 kHz to 5 kHz. In some embodiments, the resonant frequency of the bone conduction acoustic transmission device is 2.5 kHz to 4.9 kHz. In some embodiments, the resonant frequency of the bone conduction acoustic transmission device may be adjusted to the audio frequency range of 1 kHz to 4.5 kHz. In some embodiments, the resonant frequency of the bone conduction acoustic transmission device may be adjusted to the audio frequency range of 2.5 kHz to 4.5 kHz. In some embodiments, the resonant frequency of the bone conduction acoustic transmission device may be adjusted to the audio frequency range of 2.5 kHz to 3.5 kHz. By adjusting the above-mentioned resonant frequency range, the resonant peak of the bone conduction acoustic transmission device can be set to the audio frequency band range of 1 kHz to 5 kHz, thereby improving the sensitivity of the bone conduction acoustic transmission device to vibrations in the audio frequency band (for example, a frequency band range smaller than the frequency of the resonant peak, i.e., 20 Hz to 5 kHz).

[0103] In some embodiments, the resonant frequency of the bone conduction acoustic transmission device is between 3.5 kHz and 4.7 kHz, In some embodiments, the resonant frequency of the bone conduction acoustic transmission device is between 4 kHz and 4.5 kHz.

[0104] Because the bone conduction acoustic transmission device can be equivalent to a mass-spring-damping system model, when the bone conduction acoustic transmission device operates, it can be equivalent to a mass-spring-damping system being forced to vibrate by an excitation force, and its vibration law conforms to the law of a mass-spring-damping system. Therefore, the resonance frequency of the bone conduction acoustic transmission device is related to the equivalent stiffness and equivalent mass of its internal assembly (e.g., a vibration unit or a laminated structure), and the resonance frequency of the bone conduction acoustic transmission device is positively correlated with the equivalent stiffness of its internal assembly and negatively correlated with the equivalent mass of its internal assembly. The equivalent stiffness is the stiffness of the bone conduction acoustic transmission device equivalent to the mass-spring-damping system model, and the equivalent mass is the mass of the bone conduction acoustic transmission device equivalent to the mass-spring-damping system model. Therefore, adjusting the resonance frequency (or natural frequency) of the bone conduction acoustic transmission device corresponds to adjusting the equivalent stiffness and equivalent mass of the vibration unit or the laminated structure.

[0105] When the bone conduction acoustic transmission device operates, it can be equivalent to a mass-spring-damping system model being forced to vibrate by an external excitation force, and the vibration law conforms to the law of the mass-spring-damping system model. The parameters that influence the resonance frequency f0 due to the external excitation force include, but are not limited to, the system equivalent stiffness k, the system equivalent mass m, and the system equivalent relative damping coefficient (damping ratio) ξ. In some embodiments, the system equivalent stiffness k is positively correlated with the system resonance frequency f0 of the bone conduction acoustic transmission device, the system equivalent mass m is negatively correlated with the system resonance frequency f0 of the bone conduction acoustic transmission device, and the system equivalent relative damping coefficient (damping ratio) ξ is negatively correlated with the system resonance frequency f0 of the bone conduction acoustic transmission device. In some embodiments,

[0106]

number

[0107] is positively correlated with the resonant frequency f0 of the bone conduction acoustic transmission system. In some embodiments, the frequency response satisfies the following equation:

[0108]

number

[0109] In the formula, f0 is the resonant frequency of the bone conduction acoustic transmission device system, k is the equivalent stiffness of the system, m is the equivalent mass of the system, and ξ is the equivalent relative damping coefficient (damping ratio) of the system.

[0110] Most bone conduction acoustic transmission devices, especially piezoelectric ones, generally have a small system equivalent relative damping coefficient ξ, and the system's resonant frequency f0 is primarily affected by the equivalent stiffness and equivalent mass. Taking the bone conduction acoustic transmission device shown in FIG. 8 as an example, its support arm 830 provides spring and damping functions to the vibration system, and its mass element 840 provides mass function. Therefore, the support arm 830 primarily affects the system equivalent stiffness k and simultaneously affects the system equivalent mass m, while the mass element 840 primarily affects the system equivalent mass m and simultaneously affects the system equivalent stiffness k. For bone conduction acoustic transmission devices with complex structures, theoretically determining their resonant frequency f0 is difficult. Finite element simulation tools can be used to establish corresponding structural and parameter models to determine the frequency response of the bone conduction acoustic transmission device. In some embodiments, different materials can be selected to manufacture the electrode layers (including the first and second electrode layers), piezoelectric layers, elastic layers, and mass elements described below, thereby adjusting the resonant frequency f0 of the bone conduction acoustic transmission device. In some embodiments, the resonant frequency f of the bone conduction acoustic transmission device can be adjusted by designing the structure of the bone conduction acoustic transmission device, such as a structure with a mass element added to a support arm, a cantilever beam, a structure with holes in a suspension membrane, or a structure with a mass element added to a suspension membrane. In some embodiments, the resonant frequency f of the bone conduction acoustic transmission device can be adjusted by designing the sizes of different components, such as the length, width, and thickness of the support arm, mass element, cantilever beam, suspension membrane, etc.

[0111] In some embodiments, the structural parameters of the vibration unit and the acoustic transducer unit can be changed to adjust the equivalent stiffness and equivalent mass, thereby lowering the natural frequency of the laminated structure to the range of the audio frequency band. For example, holes can be provided in the vibration unit to adjust the equivalent stiffness of the vibration unit. For another example, mass elements can be provided in the vibration unit to adjust the equivalent mass of the laminated structure. For another example, support arms can be provided in the vibration unit to adjust the equivalent stiffness of the laminated structure. For more details regarding the adjustment of the structural parameters of the vibration unit and the acoustic transducer unit, please refer to the following description, and further description will be omitted in this specification.

[0112] Fig. 1 is a schematic diagram of a bone conduction acoustic transmission device according to some embodiments of the present application, and Fig. 2 is a cross-sectional view of the bone conduction acoustic transmission device shown in Fig. 1 taken along line AA.

[0113] As shown in FIGS. 1 and 2 , the bone conduction acoustic transmission device 100 may include a base structure 110 and a laminate structure, with at least a portion of the laminate structure connected to the base structure 110. The base structure 110 may be a hollow frame structure, and a portion of the laminate structure (e.g., one end of the laminate structure away from the connection between the base structure 110 and the laminate structure) may be located in the hollow portion of the frame structure. Note that the frame structure is not limited to the rectangular parallelepiped shape shown in FIG. 1 . In some embodiments, the frame structure may be a regular or irregular structure such as a truncated pyramid or a cylindrical body. In some embodiments, the laminate structure may be fixedly connected to the base structure 110 in the form of a cantilever beam. Furthermore, the laminate structure may include a fixed end and a free end, with the fixed end of the laminate structure fixedly connected to the frame structure and the free end of the laminate structure not connected to or in contact with the frame structure, thereby being suspended in the hollow portion of the frame structure. In some embodiments, the fixed end of the laminated structure may be connected to the upper surface, the lower surface, or a sidewall of the base structure 110 where the hollow portion of the base structure 110 is located. In some embodiments, the sidewall of the base structure 110 where the hollow portion is located may further have an attachment groove that fits the fixed end of the laminated structure, thereby matingly connecting the fixed end of the laminated structure to the base structure 110. To improve stability between the laminated structure and the base structure 110, in some embodiments, the laminated structure may include a connection base 140. By way of example only, as shown in FIG. 1 , the connection base 140 is fixedly connected to the fixed end of the surface of the laminated structure. In some embodiments, the fixed end of the connection base 140 may be located on the upper or lower surface of the base structure 110. In some embodiments, the fixed end of the connection base 140 may be located on the sidewall of the base structure 110 where the hollow portion of the base structure 110 is located. For example, a mounting groove that fits the fixed end is formed on the side wall of the hollow portion of the base structure 110, so that the fixed end of the laminated structure and the base structure 110 are fitted and connected by the mounting groove.Here, "connecting" may be understood as fixedly connecting the laminate structure and the base structure 110 by welding, riveting, gluing, bolting, fastening, etc. after the laminate structure and the base structure 110 are manufactured, respectively, or depositing the laminate structure onto the base structure 110 by physical deposition (e.g., physical vapor deposition) or chemical deposition (e.g., chemical vapor deposition) during manufacturing. In some embodiments, the connecting base 140 may be a structure independent of the laminate structure or may be integrally formed with the laminate structure.

[0114] In some embodiments, the laminated structure may include an acoustic transducer unit 120 and a vibration unit 130. The vibration unit 130 is an elastically deformable portion of the laminated structure, and the acoustic transducer unit 120 is a portion of the laminated structure that converts the deformation of the vibration unit 130 into an electrical signal. In some embodiments, the vibration unit 130 may be located on an upper or lower surface of the acoustic transducer unit 120. In some embodiments, the vibration unit 130 may include at least one elastic layer. Simply by way of example, the vibration unit 130 shown in FIG. 1 may include a first elastic layer 131 and a second elastic layer 132 disposed in this order from top to bottom. The first elastic layer 131 and the second elastic layer 132 may be plate-like structures made of semiconductor materials. In some embodiments, the semiconductor material may include silicon dioxide, silicon nitride, gallium nitride, zinc oxide, silicon carbide, etc. In some embodiments, the materials of the first elastic layer 131 and the second elastic layer 132 may be the same or different. In some embodiments, the acoustic transducer unit 120 includes at least a first electrode layer 121, a piezoelectric layer 122, and a second electrode layer 123 arranged in this order from top to bottom, and an elastic layer (e.g., the first elastic layer 131 and the second elastic layer 132) may be located on the upper surface of the first electrode layer 121 or the lower surface of the second electrode layer 123. The piezoelectric layer 122 can generate a voltage (potential difference) due to the deformation stress of the vibration unit 130 (e.g., the first elastic layer 131 and the second elastic layer 132) based on the piezoelectric effect, and the first electrode layer 121 and the second electrode layer 123 can extract the voltage (electrical signal). In some embodiments, the material of the piezoelectric layer may include a piezoelectric film material, which may be a film material (e.g., an AlN or PZT film material) manufactured by a deposition process (e.g., a magnetron sputtering deposition process, a chemical vapor deposition process, etc.). In some other embodiments, the material of the piezoelectric layer 122 may include a piezoelectric crystal material and a piezoelectric ceramic material. The piezoelectric crystal material is a piezoelectric single crystal.In some embodiments, the piezoelectric crystalline material may include quartz, zinc blende, boron, tourmaline, zincite, GaAs, barium titanate and its derivative crystals, KH2PO4, NaKC4H4O6·4H2O (Rochelle salt), etc., or any combination thereof. The piezoelectric ceramic material may be a piezoelectric polycrystal formed by randomly assembling fine grains obtained by solid-state reaction and sintering between powders of different materials. In some embodiments, the piezoelectric ceramic material may include barium titanate (BT), lead zirconate titanate (PZT), lead barium lithium niobate (PBLN), modified lead titanate, aluminum nitride (AIN), zinc oxide (ZnO), etc., or any combination thereof. In some embodiments, the material of the piezoelectric layer 122 may be a piezoelectric polymer material, such as polyvinylidene fluoride (PVDF). In some embodiments, the first electrode layer 121 and the second electrode layer 123 are electrically conductive material structures. Exemplary conductive materials may include metals, alloy materials, metal oxide materials, graphene, etc., or any combination thereof. In some embodiments, metal and alloy materials may include nickel, iron, lead, platinum, titanium, copper, molybdenum, zinc, or any combination thereof. In some embodiments, alloy materials may include copper-zinc alloys, copper-tin alloys, copper-nickel-silicon alloys, copper-chromium alloys, copper-silver alloys, etc., or any combination thereof. In some embodiments, metal oxide materials may include RμO2, MnO2, PbO2, NiO, etc., or any combination thereof.

[0115] When the laminated structure and the base structure 110 move relative to each other, the degree of deformation at different positions of the vibration unit 130 (e.g., the first elastic layer 131 or the second elastic layer 132) of the laminated structure is different. That is, the deformation stress on the piezoelectric layer 122 of the acoustic transducer unit 120 from different positions of the vibration unit 130 is different. In order to improve the sensitivity of the bone conduction acoustic transmission device 100, in some embodiments, the acoustic transducer unit 120 is installed only at positions where the degree of deformation of the vibration unit 130 is large, thereby improving the signal-to-noise ratio of the bone conduction acoustic transmission device 100. Therefore, the area of the first electrode layer 121, the piezoelectric layer 122, and / or the second electrode layer 123 of the acoustic transducer unit 120 may be equal to or smaller than the area of the vibration unit 130. In some embodiments, to further improve the signal-to-noise ratio of the bone conduction acoustic transmission device 100, the area of the vibration unit 130 covered by the acoustic transducer unit 120 is equal to or smaller than half the area of the vibration unit 130. Preferably, the area of the vibration unit 130 covered by the acoustic transducer unit 120 is ⅓ or less of the area of the vibration unit 130. More preferably, the area of the vibration unit 130 covered by the acoustic transducer unit 120 is ¼ or less of the area of the vibration unit 130. Furthermore, in some embodiments, the acoustic transducer unit 120 may be located close to the connection point between the laminated structure and the base structure 110. When the vibration unit 130 (e.g., elastic layer) is subjected to an external force near the connection point between the laminated structure and the base structure 110, the degree of deformation that occurs is large, and the acoustic transducer unit 120 is also subjected to a large deformation stress near the connection point between the laminated structure and the base structure 110. By arranging the acoustic transducer unit 120 in an area where the deformation stress is large, the sensitivity of the bone conduction acoustic transmission device 100 can be improved, and the signal-to-noise ratio of the bone conduction acoustic transmission device 100 can be improved. Note that the acoustic conversion unit 120 here may be close to the connection point between the laminated structure and the base structure 110, but this is relative to the free end of the laminated structure, i.e., the distance from the acoustic conversion unit 120 to the connection point between the laminated structure and the base structure 110 is shorter than the distance from the acoustic conversion unit 120 to the free end.In some embodiments, the sensitivity and signal-to-noise ratio of the bone conduction acoustic transmission device 100 can be improved simply by adjusting the area and position of the piezoelectric layer 122 in the acoustic transducer unit 120. For example, the first electrode layer 121 and the second electrode layer 123 may completely or partially cover the surface of the vibration unit 130, and the area of the piezoelectric layer 122 may be equal to or smaller than the area of the first electrode layer 121 or the second electrode layer 123. In some embodiments, the area of the first electrode layer 121 or the second electrode layer 123 covered by the piezoelectric layer 122 is equal to or smaller than half the area of the first electrode layer 121 or the second electrode layer 123. Preferably, the area of the first electrode layer 121 or the second electrode layer 123 covered by the piezoelectric layer 122 is equal to or smaller than one-third the area of the first electrode layer 121 or the second electrode layer 123. More preferably, the area of the first electrode layer 121 or the second electrode layer 123 covered by the piezoelectric layer 122 is equal to or smaller than one-fourth of the area of the first electrode layer 121 or the second electrode layer 123. In some embodiments, to prevent a problem in which the first electrode layer 121 and the second electrode layer 123 are connected to each other and a short circuit occurs, the area of the first electrode layer 121 may be smaller than the area of the piezoelectric layer 122 or the second electrode layer 123. For example, the piezoelectric layer 122, the second electrode layer 123, and the vibration unit 130 have the same area, and the area of the first electrode layer 121 is smaller than the area of the vibration unit 130 (e.g., elastic layer), the piezoelectric layer 122, or the second electrode layer 123. In such a case, since the entire area of the first electrode layer 121 is located on the surface of the piezoelectric layer 122 and the edges of the first electrode layer 121 are spaced apart from the edges of the piezoelectric layer 122 by a certain distance, the first electrode layer 121 can further improve the signal-to-noise ratio of the bone conduction acoustic transmission device 100 by avoiding areas of low material quality at the edges of the piezoelectric layer 122.

[0116] In some embodiments, the piezoelectric layer 122 may be located on the neutral layer side of the laminated structure to increase the output electrical signal and improve the signal-to-noise ratio of the bone conduction acoustic transmission device 100. The neutral layer is a planar layer in the laminated structure in which the deformation stress is approximately zero during deformation. In some embodiments, the signal-to-noise ratio of the bone conduction acoustic transmission device 100 can be improved by adjusting (e.g., increasing) the stress per unit thickness and the stress change gradient of the piezoelectric layer 122. In some embodiments, the signal-to-noise ratio and sensitivity of the bone conduction acoustic transmission device 100 can be improved by adjusting the shape, thickness, material, and size (e.g., length, width, and thickness) of the acoustic transduction unit 120 (e.g., the first electrode layer 121, the piezoelectric layer 122, and the second electrode layer 123) and the vibration unit 130 (e.g., the first elastic layer 131 and the second elastic layer 132).

[0117] In some embodiments, to solve the warpage problem of the laminate structure, it is necessary to balance the stresses in each layer of the laminate structure so that the upper and lower portions of the neutral layer of the cantilever beam experience the same type of stress (e.g., tensile stress and compressive stress) and the same magnitude. For example, if the piezoelectric layer 122 is an AlN material layer, which is located on the neutral layer side of the cantilever beam, the AlN material layer will generally experience tensile stress, and the total stress experienced by the elastic layer located on the other side of the neutral layer should also be tensile stress.

[0118] In some embodiments, the acoustic transducer unit 120 may further include a seed layer (not shown) that provides a good growth surface structure for other layers, and the seed layer is located on the lower surface of the second electrode layer 123. In some embodiments, the material of the seed layer may be the same as the material of the piezoelectric layer 122. For example, if the material of the piezoelectric layer 122 is AlN, the material of the seed layer is also AlN. Note that, if the vibration unit 130 is located on the lower surface of the second electrode layer 123, the seed layer may be located on the upper surface of the first electrode layer 121. Furthermore, if the acoustic transducer unit 120 includes a seed layer, the vibration unit 130 (e.g., the first elastic layer 131 and the second elastic layer 132) may be located on a surface of the seed layer that is away from the piezoelectric layer 122. In other embodiments, the material of the seed layer may be different from the material of the piezoelectric layer 122.

[0119] The shape of the laminated structure is not limited to the rectangle shown in Fig. 1, but may be a regular or irregular shape such as a triangle, trapezoid, circle, semicircle, quarter circle, ellipse, or semi-ellipse, and is not further limited in this specification. The number of laminated structures is also not limited to one shown in Fig. 1, but may be two, three, four, or more. Various laminated structures may be suspended and arranged side by side in the hollow portion of the base structure 110, or may be suspended and arranged in order in the hollow portion of the base structure 110 along the arrangement direction of each layer of the laminated structure.

[0120] FIG. 3 is a schematic diagram of another bone conduction acoustic transmission device according to some embodiments of the present application. The bone conduction acoustic transmission device 300 shown in FIG. 3 is substantially the same as the bone conduction acoustic transmission device 100 shown in FIG. 1 , with the greatest difference being the shape of the laminated structure of the bone conduction acoustic transmission device 300 shown in FIG. 3 . As shown in FIG. 3 , the bone conduction acoustic transmission device 300 includes a base structure 310 and a laminated structure, and the laminated structure has a trapezoidal shape. Furthermore, the width of the laminated structure of the bone conduction acoustic transmission device 300 gradually decreases from the free end to the fixed end. In other embodiments, the width of the laminated structure of the bone conduction acoustic transmission device 300 may gradually increase from the free end to the fixed end. Note that the structure of the base structure 310 here is similar to that of the base structure 110, and the structure of the vibration unit 330 is similar to that of the vibration unit 130. For details of each layer, such as the first electrode layer 321, the piezoelectric layer 322, and the second electrode layer 323 of the acoustic transducer unit 320, and the first elastic layer 331 and the second elastic layer 332 of the vibration unit 330, please refer to the contents of each layer of the acoustic transducer unit 120 and the vibration unit 130 in Fig. 1. Furthermore, other members (e.g., seed layers) in the acoustic transducer unit 120 and the vibration unit 130 are similarly applied to the bone conduction acoustic transmission device 300 shown in Fig. 3, and their description will be omitted in this specification.

[0121] FIG. 4 is a schematic diagram of a bone conduction acoustic transmission device according to some other embodiments of the present application. As shown in FIG. 4 , the bone conduction acoustic transmission device 400 may include a base structure 410 and a laminate structure, and at least a portion of the laminate structure is connected to the base structure 410. In some embodiments, the base structure 410 may be a hollow frame structure, and a portion of the laminate structure (e.g., one end of the laminate structure away from the connection between the base structure 410 and the laminate structure) may be located in the hollow portion of the frame structure. Note that the frame structure is not limited to the rectangular parallelepiped shape shown in FIG. 4 . In some embodiments, the frame structure may be a regular or irregular structure such as a truncated pyramid or a cylindrical body. In some embodiments, the laminate structure may be fixedly connected to the base structure 410 in the form of a cantilever beam. Furthermore, the laminate structure may include a fixed end and a free end, and the fixed end of the laminate structure may be fixedly connected to the frame structure, and the free end of the laminate structure may be suspended in the hollow portion of the frame structure by not connecting or contacting the frame structure. In some embodiments, the fixed end of the laminate structure may be connected to the upper surface, the lower surface, or a sidewall of the base structure 410 where the hollow portion of the base structure 410 is located. In some embodiments, a mounting groove that fits the fixed end of the laminate structure may be further provided on the sidewall of the base structure 410 where the hollow portion of the base structure 410 is located, thereby fittingly connecting the fixed end of the laminate structure to the base structure 410. Here, "connection" may be understood as fixedly connecting the laminate structure and the base structure 410 by welding, riveting, fastening, bolting, or the like after the laminate structure and the base structure 410 are manufactured. In some embodiments, the laminate structure may be deposited on the base structure 410 by physical deposition (e.g., physical vapor deposition) or chemical deposition (e.g., chemical vapor deposition) during manufacturing. In some embodiments, one or more laminate structures may be provided on the base structure 410, and the number of laminate structures may be one, two, three, seven, etc. Furthermore, the plurality of laminated structures may be arranged uniformly at equal intervals along the circumferential direction of the base structure 410, or may be arranged non-uniformly.

[0122] In some embodiments, the laminated structure may include an acoustic transducer unit 420 and a vibration unit 430. The vibration unit 430 may be located on an upper or lower surface of the acoustic transducer unit 420. In some embodiments, the vibration unit 430 may include at least one elastic layer. The elastic layer may be a plate-like structure made of a semiconductor material. In some embodiments, the semiconductor material may include silicon dioxide, silicon nitride, gallium nitride, zinc oxide, silicon carbide, or the like. In some embodiments, the acoustic transducer unit 420 may include an electrode layer and a piezoelectric layer 423, and the electrode layer includes a first electrode 421 and a second electrode 422. In embodiments herein, the piezoelectric layer 423 can generate a voltage (potential difference) due to a deformation stress of the vibration unit 430 based on the piezoelectric effect, and the first electrode 421 and the second electrode 422 can derive the voltage (electrical signal). In some embodiments, the first electrode 421 and the second electrode 422 are spaced apart on the same surface (e.g., the upper or lower surface) of the piezoelectric layer 423, and the electrode layer and the vibration unit 430 are located on different surfaces of the piezoelectric layer 423. For example, when the vibration unit 430 is located on the lower surface of the piezoelectric layer 423, the electrode layer (first electrode 421 and second electrode 422) may be located on the upper surface of the piezoelectric layer 423. Also, for example, when the vibration unit 430 is located on the upper surface of the piezoelectric layer 423, the electrode layer (first electrode 421 and second electrode 422) may be located on the lower surface of the piezoelectric layer 423. In some embodiments, the electrode layer and the vibration unit 430 may be located on the same side of the piezoelectric layer 423. For example, the electrode layer is located between the piezoelectric layer 423 and the vibration unit 430. In some embodiments, the first electrode 421 may be folded into a first interdigital structure 4210, which may include a plurality of interdigital structures and have a first spacing between adjacent interdigital structures of the first interdigital structure 4210, which may be the same or different. The second electrode 422 may be folded into a second interdigital structure 4220, which may include a plurality of interdigital structures and have a second spacing between adjacent interdigital structures of the second interdigital structure 4220, which may be the same or different.The first comb-like structure 4210 may interdigitate with the second comb-like structure 4220 to form an electrode layer, and the comb-like structure of the first comb-like structure 4210 may interdigitate with the second interval of the second comb-like structure 4220, and the comb-like structure of the second comb-like structure 4220 may interdigitate with the first interval of the first comb-like structure 4210 to form an electrode layer. By interdigitating the first comb-like structure 4210 and the second comb-like structure 4220, the first electrode 421 and the second electrode 422 are compactly arranged but do not intersect. In some embodiments, the first comb-like structure 4210 and the second comb-like structure 4220 extend along the longitudinal direction of the cantilever beam (e.g., from the fixed end to the free end). In some embodiments, the piezoelectric layer 423 is preferably made of a piezoelectric ceramic material, and when the piezoelectric layer 423 is made of a piezoelectric ceramic material, the polarization direction of the piezoelectric layer 423 is aligned with the longitudinal direction of the cantilever beam and the piezoelectric constant d of the piezoelectric ceramic. 33 The piezoelectric constant d is used to significantly enhance the output signal and improve sensitivity. 33 is a proportionality constant at which the piezoelectric layer 423 converts mechanical energy into electrical energy. Note that the piezoelectric layer 423 shown in Fig. 4 may be made of other materials, and when the polarization direction of the piezoelectric layer 423 made of other materials coincides with the thickness direction of the cantilever beam, the acoustic transducer unit 420 may be replaced with the acoustic transducer unit 120 shown in Fig. 1.

[0123] When the laminated structure and the base structure 410 move relative to each other, the degree of deformation at different positions of the vibration unit 430 of the laminated structure varies. That is, the deformation stress on the piezoelectric layer 423 of the acoustic transducer unit 420 varies from different positions of the vibration unit 430. To improve the sensitivity of the bone conduction acoustic transmission device 400, in some embodiments, the acoustic transducer unit 420 is installed only at positions where the degree of deformation of the vibration unit 430 is large, thereby improving the signal-to-noise ratio of the bone conduction acoustic transmission device 400. Therefore, the area of the electrode layer and / or the piezoelectric layer 423 of the acoustic transducer unit 420 may be equal to or smaller than the area of the vibration unit 430. In some embodiments, to further improve the signal-to-noise ratio of the bone conduction acoustic transmission device 400, the area of the vibration unit 430 covered by the acoustic transducer unit 420 is equal to or smaller than the area of the vibration unit 430. Preferably, the area of the vibration unit 430 covered by the acoustic transducer unit 420 is equal to or smaller than half the area of the vibration unit 430. Preferably, the area of the vibration unit 430 covered by the acoustic transducer unit 420 is ⅓ or less of the area of the vibration unit 430. More preferably, the area of the vibration unit 430 covered by the acoustic transducer unit 420 is ¼ or less of the area of the vibration unit 430. Furthermore, in some embodiments, the acoustic transducer unit 420 may be located close to the connection point between the laminated structure and the base structure 410. When the vibration unit 430 (e.g., elastic layer) is subjected to an external force near the connection point between the laminated structure and the base structure 410, a large degree of deformation occurs, and the acoustic transducer unit 420 is also subjected to a large deformation stress near the connection point between the laminated structure and the base structure 410. Therefore, by arranging the acoustic transducer unit 420 in an area where the deformation stress is large, the sensitivity of the bone conduction acoustic transmission device 400 can be improved, and the signal-to-noise ratio of the bone conduction acoustic transmission device 400 can be improved. It should be noted that the acoustic conversion unit 420 here may be close to the connection point between the laminated structure and the base structure 410, but this is relative to the free end of the laminated structure, i.e., the distance from the acoustic conversion unit 420 to the connection point between the laminated structure and the base structure 410 is shorter than the distance from the acoustic conversion unit 420 to the free end.In some embodiments, the sensitivity and signal-to-noise ratio of the bone conduction acoustic transmission device 400 can be improved simply by adjusting the area and position of the piezoelectric layer 423 in the acoustic transducer unit 420. For example, the electrode layer may completely or partially cover the surface of the vibration unit 430, and the area of the piezoelectric layer 423 may be equal to or smaller than the area of the electrode layer. Preferably, the area of the vibration unit 430 covered by the piezoelectric layer 423 is equal to or smaller than half the area of the electrode layer. Preferably, the area of the vibration unit 430 covered by the piezoelectric layer 423 is equal to or smaller than one-third the area of the electrode layer. More preferably, the area of the vibration unit 430 covered by the piezoelectric layer 423 is equal to or smaller than one-quarter the area of the electrode layer. In some embodiments, the area of the piezoelectric layer 423 may be the same as the area of the vibration unit 430, and the entire area of the electrode layer may be located on the piezoelectric layer 423, and the edges of the electrode layer may be spaced apart from the edges of the piezoelectric layer 423 by a certain distance, so that the first electrode 421 and the second electrode 422 of the electrode layer can avoid areas of low material quality at the edges of the piezoelectric layer 423, thereby further improving the signal-to-noise ratio of the bone conduction acoustic transmission device 400.

[0124] In some embodiments, the signal-to-noise ratio and sensitivity of the bone conduction acoustic transmission device 400 can be improved by adjusting the shape, thickness, material, and size (e.g., length, width, and thickness) of the acoustic transducer unit 420 (e.g., the first electrode 421, the piezoelectric layer 423, and the second electrode 422) and the vibration unit 430 (e.g., the elastic layer) to increase the output electrical signal and improve the signal-to-noise ratio of the bone conduction acoustic transmission device 400.

[0125] In some embodiments, in order to increase the output electrical signal and improve the signal-to-noise ratio of the bone conduction acoustic transmission device 400, the length, width, spacing between the comb tooth structures (e.g., the first spacing and the second spacing) of the single comb tooth structure of the first comb tooth structure 4210 and the second comb tooth structure 4220, and the length of the entire acoustic conversion unit 420 can be adjusted to increase the output voltage electrical signal and improve the signal-to-noise ratio of the bone conduction acoustic transmission device 400.

[0126] FIG. 5 is a schematic diagram of a bone conduction sound transmission device according to some embodiments of the present application. FIG. 6 is a cross-sectional view of a partial structure of the bone conduction sound transmission device shown in FIG. 5. As shown in FIGS. 5 and 6, the bone conduction sound transmission device 500 may include a base structure 510 and a laminated structure, and at least a portion of the laminated structure is connected to the base structure 510. In some embodiments, the base structure 510 may be a hollow frame structure, and some of the laminated structure may be located in the hollow portion of the frame structure. Note that the frame structure is not limited to the rectangular parallelepiped shape shown in FIG. 5. In some embodiments, the frame structure may be a regular or irregular structure such as a truncated pyramid or a cylinder.

[0127] In some embodiments, the laminated structure may include an acoustic transducer unit 520 and a vibration unit. In some embodiments, the vibration unit may be mounted on an upper or lower surface of the acoustic transducer unit 520. As shown in FIG. 5 , the vibration unit includes a suspension membrane structure 530, which is connected to and fixed to the base structure 510 by its periphery, and a central region of the suspension membrane structure 530 is suspended and mounted in the hollow portion of the base structure 510. In some embodiments, the suspension membrane structure 530 may be located on the upper or lower surface of the base structure 510. In some embodiments, the periphery of the suspension membrane structure 530 may be connected to the inner wall of the hollow portion of the base structure 510. Here, "connecting" may be understood as fixing the suspension membrane structure 530 to the upper surface, lower surface, or sidewall of the hollow portion of the base structure 510 by a mechanical fastening method (e.g., strong adhesive, rivet connection, clip, fitting, etc.) after the suspension membrane structure 530 and the base structure 510 are fabricated, or depositing the suspension membrane structure 530 on the base structure 510 by a physical deposition method (e.g., physical vapor deposition) or a chemical deposition method (e.g., chemical vapor deposition) during fabrication. In some embodiments, the suspension membrane structure 530 may include at least one elastic layer. The elastic layer may be a membrane-like structure fabricated from a semiconductor material. In some embodiments, the semiconductor material may include silicon dioxide, silicon nitride, gallium nitride, zinc oxide, silicon carbide, etc. In some embodiments, the shape of the suspension membrane structure 530 may be a circle, an ellipse, a polygon such as a triangle, a square, a pentagon, a hexagon, or any other shape.

[0128] In some embodiments, the acoustic transducer unit 520 may be located on an upper or lower surface of the suspension membrane structure 530. In some embodiments, the suspension membrane structure 530 may include a plurality of holes 5300, which are distributed around the center of the acoustic transducer unit 520 along the circumferential direction of the acoustic transducer unit 520. By installing multiple holes 5300 on the suspension membrane structure 530, the rigidity of the suspension membrane structure 530 at different positions can be adjusted, so that the rigidity of the suspension membrane structure 530 in the areas close to the multiple holes 5300 is reduced and the rigidity of the suspension membrane structure 530 in the areas away from the multiple holes 5300 is relatively increased. When the suspension membrane structure 530 and the base structure 510 move relative to each other, the degree of deformation of the suspension membrane structure 530 is large in the areas close to the multiple holes 5300 and small in the areas away from the multiple holes 5300. In this case, it can be seen that arranging the acoustic conversion unit 520 in the area close to the multiple holes 5300 on the suspension membrane structure 530 helps the acoustic conversion unit 520 collect vibration signals, thereby effectively improving the sensitivity of the bone conduction acoustic transmission device 500. In addition, the structure of each component of the bone conduction acoustic transmission device 500 is simple, making it easy to manufacture and assemble. In some embodiments, the holes 5300 on the suspension membrane structure 530 may have any shape, such as circular holes, elliptical holes, square holes, or other polygonal holes. In some embodiments, the size, number, spacing, and position of the multiple holes 5300 may be changed to adjust the resonant frequency (setting the resonant frequency to 2 kHz to 5 kHz) and stress distribution of the bone conduction acoustic transmission device 500, thereby improving the sensitivity of the bone conduction acoustic transmission device 500. Note that the resonant frequency is not limited to the above-mentioned range of 2 kHz to 5 kHz, but may be 3 kHz to 4.5 kHz or 4 kHz to 4.5 kHz. The resonant frequency range can be adaptively adjusted according to various application scenarios and is not further limited herein.

[0129] 5 and 6 , in some embodiments, the acoustic transducer unit 520 may include a first electrode layer 521, a piezoelectric layer 522, and a second electrode layer 523 arranged in this order from top to bottom, or the positions of the first electrode layer 521 and the second electrode layer 523 may be reversed. The piezoelectric layer 522 can generate a voltage (potential difference) due to the deformation stress of a vibration unit (e.g., a suspension membrane structure 530) based on the piezoelectric effect, and the first electrode layer 521 and the second electrode layer 523 can extract the voltage (electrical signal). In some embodiments, the material of the piezoelectric layer 522 may include a piezoelectric crystal material and a piezoelectric ceramic material. The piezoelectric crystal is a piezoelectric single crystal. In some embodiments, the piezoelectric crystal material may include quartz, zinc blende, boron, tourmaline, zincite, GaAs, barium titanate and its derivative crystals, KH2PO4, NaKC4H4O6·4H2O (Rochelle salt), sugar, etc., or any combination thereof. Piezoelectric ceramic materials are piezoelectric polycrystals formed by randomly assembling fine grains obtained by solid-state reaction and sintering between powders of different materials. In some embodiments, the piezoelectric ceramic material may include barium titanate (BT), lead zirconate titanate (PZT), lead barium lithium niobate (PBLN), modified lead titanate, aluminum nitride (AIN), zinc oxide (ZnO), etc., or any combination thereof. In some embodiments, the material of piezoelectric layer 522 may be a piezoelectric polymer material, such as polyvinylidene fluoride (PVDF). In some embodiments, first electrode layer 521 and second electrode layer 523 are electrically conductive material structures. Exemplary electrically conductive materials may include metals, alloy materials, metal oxide materials, graphene, etc., or any combination thereof. In some embodiments, metal and alloy materials may include nickel, iron, lead, platinum, titanium, copper, molybdenum, zinc, etc., or any combination thereof. In some embodiments, the alloy material may include a copper-zinc alloy, a copper-tin alloy, a copper-nickel-silicon alloy, a copper-chromium alloy, a copper-silver alloy, or the like, or any combination thereof. In some embodiments, the metal oxide material may include RuO, MnO, PbO, NiO, or the like, or any combination thereof.

[0130] 5 , in some embodiments, the plurality of holes 5300 surround a circular area. To improve the sound pressure output effect of the acoustic transducer units 520, the acoustic transducer units 520 may be disposed in an area of the suspension membrane structure 530 adjacent to the plurality of holes 5300. Furthermore, the acoustic transducer units 520 may have an annular structure and be distributed along the inside of the circular area surrounded by the plurality of holes 5300. In some embodiments, the annular acoustic transducer units 520 may be distributed along the outside of the circular area surrounded by the plurality of holes 5300. In some embodiments, the piezoelectric layer 522 of the acoustic transducer unit 520 may be a piezoelectric ring, and the first electrode layer 521 and the second electrode layer 523 located on the upper and lower surfaces of the piezoelectric ring may be electrode rings. In some embodiments, the acoustic transducer unit 520 further includes a lead structure 5200 for transmitting electrical signals collected by the electrode rings (e.g., the first electrode layer 521 and the second electrode layer 523) to a subsequent circuit. In some embodiments, to improve the output electrical signal of the bone conduction acoustic transmission device 500, the radial distance from the edge of the acoustic transducer unit 520 (e.g., annular structure) to the center of each hole 5300 may be 100 μm to 400 μm. Preferably, the radial distance from the edge of the acoustic transducer unit 520 (e.g., annular structure) to the center of each hole 5300 may be 150 μm to 300 μm. More preferably, the radial distance from the edge of the acoustic transducer unit 520 (e.g., annular structure) to the center of each hole 5300 may be 150 μm to 250 μm.

[0131] In some embodiments, the shape, size (eg, length, width, and thickness), and material of the lead structure 5200 can be adjusted to improve the output electrical signal of the bone conduction acoustic transmission device 500.

[0132] In some alternative embodiments, the deformation stress at different locations of the suspension membrane structure 530 may be further modified by adjusting the thickness or density of different regions of the suspension membrane structure 530. Simply by way of example, in some embodiments, the acoustic transducer unit 520 is an annular structure, and the thickness of the suspension membrane structure 530 in the inner region of the annular structure is greater than the thickness of the suspension membrane structure 530 in the outer region of the annular structure. In other embodiments, the density of the suspension membrane structure 530 in the inner region of the annular structure is greater than the density of the suspension membrane structure 530 in the outer region of the annular structure. By modifying the density or thickness at different locations of the suspension membrane structure 530, the mass of the suspension membrane in the inner region of the annular structure is greater than the mass of the suspension membrane in the outer region of the annular structure. When the suspension membrane structure 530 and the base structure 510 move relative to each other, the degree of deformation and the deformation stress generated in the suspension membrane structure 530 near the annular structure of the acoustic transducer unit 520 are greater, resulting in an improved output electrical signal from the bone conduction acoustic transmission device 500.

[0133] Note that the shape of the area surrounded by the plurality of holes 5300 is not limited to the circle shown in FIG. 5 , but may be other regular or irregular shapes such as a semicircle, a quarter circle, an ellipse, a semi-ellipse, a triangle, or a rectangle. The shape of the acoustic transducer units 520 can be adaptively adjusted according to the shape of the area surrounded by the plurality of holes 5300. For example, if the shape of the area surrounded by the plurality of holes 5300 is rectangular, the shape of the acoustic transducer units 520 may be rectangular, and the rectangular acoustic transducer units 520 may be distributed along the inside or outside of the rectangle surrounded by the plurality of holes 5300. For example, if the shape of the area surrounded by the plurality of holes 5300 is semicircular, the shape of the acoustic transducer units 520 may be semiannular, and the semiannular acoustic transducer units 520 may be distributed along the inside or outside of the semiannular shape surrounded by the plurality of holes 5300. In some embodiments, the suspension membrane structure 530 shown in FIG. 5 does not need to be perforated.

[0134] Fig. 7 is a schematic diagram of a bone conduction acoustic transmission device according to some embodiments of the present application. The structure of the bone conduction acoustic transmission device 700 shown in Fig. 7 is almost the same as the structure of the bone conduction acoustic transmission device 500 shown in Fig. 5, except that the vibration unit of the bone conduction acoustic transmission device 700 shown in Fig. 7 includes a suspension membrane structure 730 and a mass element 740.

[0135] 7, bone conduction acoustic transmission device 700 may include a base structure 710 and a laminated structure, and at least a portion of the laminated structure may be connected to base structure 710. In some embodiments, base structure 710 may be a hollow frame structure, and some of the laminated structure may be located in the hollow portion of the frame structure. Note that the frame structure is not limited to the rectangular parallelepiped shape shown in FIG. 7, and in some embodiments, the frame structure may be a regular or irregular structure such as a truncated pyramid or a cylinder.

[0136] In some embodiments, the laminate structure may include an acoustic transducer unit 720 and a vibration unit. In some embodiments, the vibration unit may be disposed on an upper or lower surface of the acoustic transducer unit 720. As shown in FIG. 7 , the vibration unit includes a suspension membrane structure 730 and a mass element 740, and the mass element 740 may be located on an upper or lower surface of the suspension membrane structure 730. In some embodiments, the suspension membrane structure 730 may be located on an upper or lower surface of the base structure 710. In some embodiments, the periphery of the suspension membrane structure 730 may be connected to an inner wall of a hollow portion of the base structure 710. Here, "connection" can be understood as fixing the suspension membrane structure 730 to the upper or lower surface of the base structure 710 or to the side wall of the hollow portion of the base structure 710 by a mechanical fastening method (e.g., strong adhesive, rivet connection, clip, fitting, etc.) after manufacturing the suspension membrane structure 730 and the base structure 710, or depositing the suspension membrane structure 730 on the base structure 710 by a physical deposition (e.g., physical vapor deposition) or chemical deposition (e.g., chemical vapor deposition) method during manufacturing. When the vibration unit and the base structure 710 move relative to each other, the mass element 740 and the suspension membrane structure 730 have different weights, so that the degree of deformation of the region of the suspension membrane structure 730 where the mass element 740 is located or a region nearby the mass element 740 is greater than the degree of deformation of the region of the suspension membrane structure 730 away from the mass element 740. In order to improve the output sound pressure of the bone conduction acoustic transmission device 700, the acoustic transducer units 720 may be distributed along the circumferential direction of the mass element 740. In some embodiments, the shape of the acoustic transducer unit 720 may be the same as or different from the shape of the mass element 740. Preferably, the shape of the acoustic transducer unit 720 may be the same as the shape of the mass element 740, so that each position of the acoustic transducer unit 720 can be close to the mass element 740, thereby further improving the output electrical signal of the bone conduction acoustic transmission device 700.For example, the mass element 740 may have a cylindrical structure and the acoustic transducer unit 720 may have an annular structure, where the inner diameter of the annular acoustic transducer unit 720 is greater than the radius of the mass element 740, so that the acoustic transducer unit 720 is disposed along the circumferential direction of the mass element 740. In some embodiments, the acoustic transducer unit 720 may include a first electrode layer, a second electrode layer, and a piezoelectric layer disposed between the two electrode layers, where the first electrode layer, the piezoelectric layer, and the second electrode layer are combined into a structure that conforms to the shape of the mass element 740. For example, the mass element 740 may have a cylindrical structure and the acoustic transducer unit 720 may have an annular structure, where the first electrode layer, the piezoelectric layer, and the second electrode layer are all annular structures, and the three are disposed in order from top to bottom to form the annular structure.

[0137] In some embodiments, the acoustic transducer units 720 and the mass elements 740 may be located on different sides of the suspension membrane structure 730, or on the same side of the suspension membrane structure 730. For example, the acoustic transducer units 720 and the mass elements 740 may both be located on the upper or lower surface of the suspension membrane structure 730, and the acoustic transducer units 720 may be distributed along the circumferential direction of the mass elements 740. For another example, the acoustic transducer units 720 may be located on the upper surface of the suspension membrane structure 730, and the mass elements 740 may be located on the lower surface of the suspension membrane structure 730, with the projection of the mass elements 740 onto the suspension membrane structure 730 being within the area of the acoustic transducer units 720.

[0138] In some embodiments, the size, shape, and position of mass element 740 and the position, shape, and size of the piezoelectric layer can be changed to improve the output electrical signal of bone conduction acoustic transmission device 700. In some embodiments, the shape, material, and size of suspension membrane structure 730 can be changed to improve the sound pressure output effect of bone conduction acoustic transmission device 700. The first electrode layer, second electrode layer, and piezoelectric layer of acoustic transducer unit 720 here are similar to the first electrode layer 521, second electrode layer 523, and piezoelectric layer 522 of acoustic transducer unit 520 in FIG. 5 in terms of structure and parameters, the suspension membrane structure 730 and suspension membrane structure 530 are similar to each other in structure and parameters, and the lead structure 7200 and lead structure 5200 are similar to each other in structure and parameters, and will not be further described herein.

[0139] FIG. 8 is a schematic diagram of a bone conduction acoustic transmission device according to some embodiments of the present application. FIG. 9 is a schematic plan view of the bone conduction acoustic transmission device shown in FIG. 8. FIG. 10 is a cross-sectional view taken along CC of the bone conduction acoustic transmission device shown in FIG. 9. As shown in FIGS. 8 to 10, the vibration unit includes at least one support arm 830 and a mass element 840, and the mass element 840 is connected to the base structure 810 by at least one support arm 830. The number of support arms 830 may be one, two, four, six, etc. In some embodiments, the base structure 810 and the support arm 830, and the mass element 840 and the support arm 830 may be connected by welding, adhesive, or the like. In some embodiments, the base structure 810 and the support arm 830 may be fabricated on the same base material (e.g., a silicon wafer substrate) using a micro-nano fabrication process. Alternatively, the base structure 810, the support arms 830, and the mass element 840 may be fabricated on a single substrate (e.g., a silicon wafer substrate) using a micro-nano fabrication process. In some embodiments, the acoustic transducer unit 820 may be located on an upper surface, a lower surface, or inside at least one of the support arms 830.

[0140] As shown in FIG. 8 , base structure 810 is a rectangular parallelepiped frame structure. In some embodiments, the interior of base structure 810 may include a hollow portion (e.g., hollow cavity 811 shown in FIG. 10 ) for disposing acoustic transducer unit 820 and vibration unit. In some embodiments, base structure 810 may include a frame structure having hollow cavity 811, and support arm 830 and mass element 840 are both installed in cavity 811, with one end of support arm 830 connected to base structure 810 and the other end connected to mass element 840. In some embodiments, the cross-sectional shape of the hollow portion (e.g., hollow cavity 811) perpendicular to the thickness direction (direction indicated by the arrow in FIG. 10 ) may be any other regular or irregular shape, such as a circle, a square (e.g., a rectangle or a parallelogram), a pentagon, a hexagon, a heptagon, or an octagon. In some embodiments, the size of any side length of the hollow portion having a rectangular cross section perpendicular to the thickness direction may be 0.8 mm to 2 mm. In some embodiments, the size of any side length may be 1 mm to 1.5 mm. In some embodiments, the shape of hollow cavity 811 in base structure 810 may correspond to the shape of mass element 840. For example, if the cross section perpendicular to the thickness direction of cavity 811 is rectangular, the cross section perpendicular to the thickness direction of mass element 840 also has a rectangular shape.

[0141] In some embodiments, the number of support arms 830 is two or more, and two or more support arms 830 are disposed around mass element 840. For example, the number of support arms 830 may be two, three, four, six, seven, etc. In some embodiments, the shape of a cross section perpendicular to the thickness direction of mass element 840 is polygonal, and the number of support arms 830 corresponds to the number of sides of the polygon. For example, the number of support arms 830 may be equal to the number of sides of the polygon. Also, for example, the number of support arms 830 may be several times the number of sides of the polygon, such as two, three, five, etc. Merely by way of example, if the cross section perpendicular to the thickness direction of mass element 840 is rectangular, the number of support arms 830 is four. The four support arms 830 may be connected to four sides of the rectangle, respectively. Alternatively, if the cross section perpendicular to the thickness direction of mass element 840 is rectangular, the number of support arms 830 is eight. Each pair of support arms 830 is connected to one of the four sides of a rectangle. This arrangement can provide more uniform stress to support arms 830 and mass elements 840. In some embodiments, the connection points between each support arm 830 and mass element 840 can be rotationally symmetrically positioned about the center of mass element 840, thereby providing more uniform stress to support arms 830 and mass elements 840.

[0142] In some embodiments, the vibration unit may include four support arms 830 and mass elements 840, with one end of each of the four support arms 830 connected to the upper surface, the lower surface, or a sidewall of the hollow portion of the base structure 810, and the other end connected to the upper surface, the lower surface, or a circumferential sidewall of the mass element 840. In some embodiments, the mass elements 840 may protrude upward and / or downward relative to the support arms 830. For example, if the ends of the four support arms 830 are connected to the upper surface of the mass element 840, the mass elements 840 may protrude downward relative to the support arms 830. For example, if the ends of the four support arms 830 are connected to the lower surface of the mass element 840, the mass elements 840 may protrude upward relative to the support arms 830. For example, if the ends of the four support arms 830 are connected to the circumferential sidewall of the mass element 840, the mass elements 840 may protrude upward and downward relative to the support arms 830. In some embodiments, the upper surface of mass element 840 and the upper surface of support arm 830 are substantially co-planar. In other embodiments, the lower surface of mass element 840 and the lower surface of support arm 830 are substantially co-planar. In other embodiments, the upper surface of mass element 840 and the upper surface of support arm 830 are substantially co-planar, and simultaneously the lower surface of mass element 840 and the lower surface of support arm 830 are substantially co-planar. In some embodiments, support arm 830 has a rectangular shape, i.e., the shape of a cross section perpendicular to the thickness direction of support arm 830 is rectangular. One of the opposite sides of the rectangle is connected to mass element 840, and the other of the opposite sides is connected to base structure 810.

[0143] 9, the length X of the support arm 830 is 100 μm to 500 μm. In some embodiments, the length X of the support arm 830 is 150 μm to 350 μm. In some embodiments, the width Y of the support arm 830 is 150 μm to 400 μm. In some embodiments, the width Y of the support arm 830 is 250 μm to 350 μm. By adjusting the design size of the support arm 830, the rigidity of the support arm 830 can be adjusted, and thereby the resonant frequency of the bone conduction acoustic transmission device 800 can be adjusted.

[0144] 10 , the acoustic transducer unit 820 may include a first electrode layer 821, a first piezoelectric layer 822, and a second electrode layer 823, which are arranged in this order from top to bottom. The first electrode layer 821 or the second electrode layer 823 is connected to the upper or lower surface of a support arm 830 (e.g., an elastic layer 824). For example, the upper surface of the first electrode layer 821 may be connected to the lower surface of the support arm 830, and the lower surface of the second electrode layer 823 may be connected to the upper surface of the support arm 830. The first piezoelectric layer 822 can generate a voltage (potential difference) due to the deformation stress of the vibration unit (e.g., the support arm 830 and the mass element 840) based on the piezoelectric effect, and the first electrode layer 821 and the second electrode layer 823 can derive the voltage (electrical signal). In order to set the resonant frequency of the bone conduction acoustic transmission device 800 within a specific frequency range (e.g., 2000 Hz to 5000 Hz), the material and thickness of the acoustic conversion unit 820 (e.g., the first electrode layer 821, the second electrode layer 823, and the first piezoelectric layer 822) and the vibration unit (e.g., the support arm 830) may be adjusted.

[0145] In some embodiments, the thickness of first electrode layer 821 may be 80 nm to 250 nm. In some embodiments, the thickness of first electrode layer 821 may be 100 nm to 150 nm. In some embodiments, the thickness of second electrode layer 823 may be 80 nm to 250 nm. In some embodiments, the thickness of second electrode layer 823 may be 100 nm to 200 nm. In some embodiments, the thickness of first piezoelectric layer 822 may be 0.8 μm to 2 μm. In some embodiments, the thickness of first piezoelectric layer 822 may be 0.8 μm to 1.5 μm. By adjusting the thicknesses of first electrode layer 821, first piezoelectric layer 822, and second electrode layer 823, it is possible to adjust the magnitude of the deformation stress experienced by first piezoelectric layer 822 during vibration of bone conduction acoustic transmission device 800, thereby increasing the deformation stress experienced by first piezoelectric layer 822 and causing acoustic transduction unit 820 to generate a large electrical signal.

[0146] In some embodiments, the materials of the first electrode layer 821 and the second electrode layer 823 may be one or a combination of metal materials commonly used in semiconductors, such as Mo, Cu, Al, Ti, and Au. In some embodiments, the material of the first piezoelectric layer 822 may be aluminum nitride (AlN), lead zirconate titanate piezoelectric ceramic (PZT), polyvinylidene fluoride (PVDF), zinc oxide (ZnO), or the like. In some embodiments, depending on the functions required for the bone conduction acoustic transmitter 800, the structure of the bone conduction acoustic transmitter 800 is fabricated on a substrate (e.g., a silicon wafer) using a micro-nano fabrication process. For example, the second electrode layer 823 may be fabricated on the substrate using a method such as electron beam evaporation or magnetron sputtering in physical vapor deposition (PVD). Next, the first piezoelectric layer 822 may be fabricated on the second electrode layer 823 using a method such as electron beam evaporation or magnetron sputtering in physical vapor deposition (PVD). Finally, the first electrode layer 821 can be fabricated on the first piezoelectric layer 822 using methods such as electron beam evaporation or magnetron sputtering in physical vapor deposition (PVD). In some embodiments, an etching stopper layer can be fabricated on the substrate (e.g., before fabricating the second electrode layer 823). The etching stopper layer can facilitate accurate control of the size of the electrode layer (e.g., the first electrode layer or the second electrode layer) and can also prevent subsequent etching processes from damaging the substrate. Specifically, the etching stopper layer can be fabricated on the substrate using methods such as chemical vapor deposition (CVD) or thermal oxidation. The thickness of the etching stopper layer can be 100 nm to 2 μm, and in some embodiments, the thickness of the etching stopper layer can be 300 nm to 1 μm.

[0147] In some embodiments, the area of the first electrode layer 821, the first piezoelectric layer 822, and / or the second electrode layer 823 is equal to or less than the area of the support arm 830, and some or all of the first electrode layer 821, the first piezoelectric layer 822, and / or the second electrode layer 823 cover an upper surface or a lower surface of at least one support arm 830. In some embodiments, when the first piezoelectric layer 822 is located between the first electrode layer 821 and the support arm 830 (e.g., when the first electrode layer 821 and the first piezoelectric layer 822 are disposed on the upper surface of the support arm from top to bottom, or when the first electrode layer 821 and the first piezoelectric layer 822 are disposed on the lower surface of the support arm from bottom to top), the area of the first electrode layer 821 is equal to or less than the area of the first piezoelectric layer 822, and the entire area of the first electrode layer 821 is disposed on the surface of the first piezoelectric layer 822. In some other embodiments, the area of the first electrode layer 821 may be equal to the area of the first piezoelectric layer 822 .

[0148] In some embodiments, the first electrode layer 821, the first piezoelectric layer 822, and the second electrode layer 823 of the acoustic transducer unit 820 are located at one end connected to the support arm 830 of the mass element 840. In other embodiments, the first electrode layer 821, the first piezoelectric layer 822, and the second electrode layer 823 of the acoustic transducer unit 820 are located at one end connected to the base structure 810 of the support arm 830. In other embodiments, the first electrode layer 821, the first piezoelectric layer 822, and the second electrode layer 823 of the acoustic transducer unit 820 are located at one end connected to the support arm 830 of the mass element 840, and simultaneously the first electrode layer 821, the first piezoelectric layer 822, and the second electrode layer 823 of the acoustic transducer unit 820 are located at one end connected to the base structure 810 of the support arm 830. Since one end of the mass element 840 connected to the support arm 830 and one end of the support arm 830 connected to the base structure 810 have large deformation stress during vibration of the vibration unit, by placing the first electrode layer 821, the first piezoelectric layer 822 and the second electrode layer 823 of the acoustic conversion unit 820 in these two areas, a large electrical signal is generated.

[0149] In some embodiments, mass element 840 may be located on an upper or lower surface of first electrode layer 821 or second electrode layer 823. For example, mass element 840 may be located on an upper surface of first electrode layer 821, or mass element 840 may be located on a lower surface of second electrode layer 823. In other embodiments, the upper surface of mass element 840 may be flush or substantially flush with the upper surface of first electrode layer 821. In other embodiments, the lower surface of mass element 840 may be flush or substantially flush with the lower surface of second electrode layer 823. In other embodiments, the upper surface of mass element 840 may be flush or substantially flush with the upper surface of first electrode layer 821, while the lower surface of mass element 840 may be flush or substantially flush with the lower surface of second electrode layer 823.

[0150] In some embodiments, as shown in FIG. 10 , the acoustic transducer unit 820 may include at least one elastic layer 824. The at least one elastic layer 824 may be located on an upper surface and / or a lower surface of the first electrode layer 821 or the second electrode layer 823. For example, the at least one elastic layer 824 may be located on an upper surface of the first electrode layer 821, or the at least one elastic layer 824 may be located on a lower surface of the second electrode layer 823. In some embodiments, when the support arm 830 has multiple elastic layers 824, the acoustic transducer unit 820 may be located between the multiple elastic layers 824. The elastic layer 824 may deform during vibration, the first piezoelectric layer 822 may generate an electrical signal based on the deformation of the elastic layer 824, and the first electrode layer 821 and the second electrode layer 823 may collect the electrical signal. In some embodiments, the thickness of the elastic layer 824 may be 0.5 μm to 10 μm. In some embodiments, the thickness of the elastic layer 824 is 2 to 6 μm. By adjusting the design thickness of the elastic layer 824, it is possible to adjust the magnitude of the deformation stress that the first piezoelectric layer 822 receives during vibration of the bone conduction acoustic transmission device 800.

[0151] In some embodiments, the thickness of elastic layer 824 is 1 to 6 times the thickness of first piezoelectric layer 822. In some preferred embodiments, the thickness of elastic layer 824 is 1 to 3 times the thickness of first piezoelectric layer 822. By setting the thickness in this manner, first piezoelectric layer 822 is separated from neutral layer 831, and the magnitude of the deformation stress experienced by first piezoelectric layer 822 can be increased.

[0152] In some embodiments, the elastic layer 824 may be a plate-like structure made of a semiconductor material. In some embodiments, the semiconductor material may include silicon, silicon dioxide, silicon nitride, gallium nitride, zinc oxide, silicon carbide, etc. In some embodiments, when the acoustic transducer unit includes two or more elastic layers 824, the materials of the different elastic layers 824 may be the same or different. In some embodiments, the elastic layer 824 may have a single-layer structure (e.g., a layer structure made of a single material). The material of the single-layer structure may include, but is not limited to, silicon (Si), silicon dioxide (SiO), silicon nitride (SiNx), silicon carbide (SiC), etc. In some embodiments, the elastic layer 824 may have a multi-layer structure (e.g., a multi-layer structure made of multiple materials, where each layer may be made of a single material). For example, the multi-layer structure may be made of a combination of silicon and silicon dioxide, a combination of silicon and silicon nitride, etc. In some embodiments, one or more elastic layers 824 can be fabricated on an etch stop layer or substrate by methods such as chemical vapor deposition (CVD) or physical vapor deposition (PVD).

[0153] In some embodiments, the acoustic transducer unit 820 may include a bonding wire electrode layer 826 (PAD layer). The bonding wire electrode layer 826 may be located on the first electrode layer 821 and the second electrode layer 823. The first electrode layer 821 and the second electrode layer 823 are connected to an external circuit via external bonding wires (e.g., gold wires, aluminum wires, etc.), thereby transmitting a voltage signal between the first electrode layer 821 and the second electrode layer 823 to a back-end processing circuit. In some embodiments, the material of the bonding wire electrode layer 826 may include copper foil, titanium, copper, etc. In some embodiments, the thickness of the bonding wire electrode layer 826 may be 100 nm to 200 nm. In some embodiments, the thickness of the bonding wire electrode layer 826 may be 150 nm to 200 nm. By adjusting the thickness of the bonding wire electrode layer 826, the magnitude of the deformation stress experienced by the first piezoelectric layer 822 during vibration of the bone conduction acoustic transmission device 800 can be adjusted.

[0154] In some embodiments, the bonding wire electrode layer 826 is disposed on the base structure 810. For example, the bonding wire electrode layer 826 may be disposed on the top or bottom surface of the base structure 810. The bonding wire electrode layer 826 can conduct electrical signals from the base structure 810. In some embodiments, the electrical signals may be conducted from the first electrode layer 821 or the second electrode layer 823 to the base structure 810 via the following electrode leads 860. The bonding wire electrode layer 826 may be manufactured by a manufacturing process such as a metal lift-off process or deposition followed by etching. The bonding wire electrode layer 826 may be manufactured after the first electrode layer 821, the first piezoelectric layer 822, and the second electrode layer 823 have all been manufactured.

[0155] In some embodiments, acoustic transduction unit 820 may further include a first seed layer 825. In some embodiments, first seed layer 825 may be located between second electrode layer 823 and support arm 830. In some embodiments, first seed layer 825 may be located between elastic layer 824 and first electrode layer 821 or between elastic layer 824 and second electrode layer 823. In some embodiments, the material of first seed layer 825 may be the same as the material of first piezoelectric layer 822. For example, if the material of first piezoelectric layer 822 is AlN, the material of first seed layer 825 is also AlN. In some embodiments, the material of first seed layer 825 may be different from the material of first piezoelectric layer 822. The specific frequency range of the resonant frequency of the bone conduction acoustic transmission device 800 is not limited to 2000 Hz to 5000 Hz, but may be 4000 Hz to 5000 Hz or 2300 Hz to 3300 Hz, for example. The specific frequency range may be adjusted according to actual conditions. When the mass element 840 protrudes upward relative to the support arm 830, the acoustic transducer unit 820 may be located on the lower surface of the support arm 830, and the first seed layer 825 may be located between the mass element 840 and the support arm 830. In some embodiments, the thickness of the first seed layer 825 may be 10 to 120 nm. In some embodiments, the thickness of the first seed layer 825 may be 40 μm to 80 nm. By adjusting the thickness of the first seed layer 825, the magnitude of the deformation stress experienced by the first piezoelectric layer 822 during vibration of the bone conduction acoustic transmission device 800 can be adjusted.

[0156] The provision of the first seed layer 825 can provide a good growth surface structure for other layers. For example, since the elastic layer 824 may not stably adhere to the electrode layer (the first electrode layer 821 or the second electrode layer 823), the first seed layer 825 may be attached to the electrode layer (the first electrode layer 821 or the second electrode layer 823) and then the elastic layer 824 may be attached to the first seed layer 825 to achieve a stable connection between the layers. In some embodiments, the first seed layer 825 may be fabricated on the upper surface of the elastic layer 824. The first seed layer 825 may be fabricated by a method such as chemical vapor deposition (CVD) or physical vapor deposition (PVD).

[0157] In some embodiments, the elastic layer 824 may be disposed between the support arm 830 and the first electrode layer 821, and the first seed layer 825 may be disposed between the elastic layer 824 and the first electrode layer 821. Alternatively, the elastic layer 824 may be disposed between the support arm 830 and the second electrode layer 823, and the first seed layer 825 may be disposed between the elastic layer 824 and the second electrode layer 823. For example, when the acoustic transducer unit 820 is disposed on the upper surface of the support arm 830, the elastic layer 824, the first seed layer 825, the second electrode layer 823, the first piezoelectric layer 822, and the first electrode layer 821 are disposed in order from bottom to top. Alternatively, when the acoustic transducer unit 820 is installed on the lower surface of the support arm 830, the elastic layer 824, the first seed layer 825, the first electrode layer 821, the first piezoelectric layer 822, and the second electrode layer 823 are installed in this order from top to bottom, which can ensure that a large electrical signal is generated and the connection between the structures of each layer of the acoustic transducer unit 820 is stable.

[0158] FIG. 11 is a front view of the bone conduction sound transmission device in the vibrating state shown in FIG. 8, and FIG. 12 is a cross-sectional view taken along the line DD of the bone conduction sound transmission device shown in FIG. 11. As shown in FIGS. 11 and 12, when the vibration unit (e.g., the support arm 830) of the bone conduction sound transmission device 800 deforms, a neutral layer 831 exists, and the neutral layer 831 has zero deformation stress when the support arm 830 deforms. That is, the neutral layer 831 is a layer at a position where the deformation stress is zero when the support arm 830 deforms. The magnitude of the output electrical signal of the piezoelectric material (i.e., the first piezoelectric layer 822) is related to the magnitude of the stress, and the thickness of each layer in the thickness direction affects the stress distribution for the same vibration signal in each layer. Because the neutral layer 831 is a layer at a position where the deformation stress is zero, the deformation stress decreases as the support arm 830 deforms closer to the neutral layer 831 in the thickness direction.

[0159] Based on the above, in the embodiment of the present application, the thickness and connection order of the elastic layer 824 and other layer structures are designed to ensure that the first piezoelectric layer 822 and the neutral layer 831 do not overlap, thereby ensuring that the first piezoelectric layer 822 can be subjected to deformation stress and can further interact with the first electrode layer 821 and / or the second electrode layer 823 to generate an electrical signal. Furthermore, the thickness of each layer in the embodiment of the present application is designed to ensure that the first piezoelectric layer 822 is as far away from the neutral layer 831 as possible, thereby maximizing the deformation stress experienced by the first piezoelectric layer 822, maximizing the output electrical signal, and maximizing the sensitivity of the device.

[0160] In some embodiments, mass element 840 may have a single-layer structure or a multi-layer structure. In some embodiments, mass element 840 has a multi-layer structure, and the number of layers of mass element 840, the materials corresponding to the structure of each layer, and parameters thereof may be the same as or different from those of elastic layer 824 of support arm 830 and acoustic transducer unit 820. In some embodiments, the shape of mass element 840 may be a regular or irregular shape, such as a circle, semicircle, ellipse, triangle, square, pentagon, hexagon, heptagon, or octagon. In some embodiments, the thickness of mass element 840 may be the same as or different from the total thickness of support arm 830 and acoustic transducer unit 820. When mass element 840 has a multi-layer structure, the materials and sizes thereof may be referenced to those of acoustic transducer unit 820, and a description thereof will be omitted herein. The materials and parameters of each layer of acoustic transducer unit 820 described herein may also be applied to the bone conduction acoustic transmission devices shown in FIGS. 1 , 3 , 4 , 5 , and 7 .

[0161] In some embodiments, mass element 840 includes a third electrode layer, a second piezoelectric layer, and a fourth electrode layer, arranged in this order from bottom to top. The material, function, and manufacturing method of the third electrode layer may be similar to the material, function, and manufacturing method of the first electrode layer 821. The material, function, and manufacturing method of the second piezoelectric layer may be similar to the material, function, and manufacturing method of the first piezoelectric layer 822. The material, function, and manufacturing method of the fourth electrode layer may be similar to the material, function, and manufacturing method of the second electrode layer 823, and these details will not be described here. In some embodiments, mass element 840 may further include a base layer. The base layer supports the third electrode layer, the second piezoelectric layer, and the fourth electrode layer and increases the weight of mass element 840, improving the inertia of mass element 840 and the sensitivity of bone conduction acoustic transmission device 800. In some embodiments, mass element 840 further includes a second seed layer disposed between the underlayer and the third electrode layer. The material, function, and manufacturing method of the second seed layer are similar to the material, function, and manufacturing method of first seed layer 825, and therefore will not be described again. In some embodiments, the thickness of the underlayer is 20 μm to 400 μm. In some embodiments, the thickness of the underlayer may be 300 μm to 400 μm. In some embodiments, the thickness of the underlayer may be 200 μm to 300 μm.

[0162] In some embodiments, the cross-sectional shape of mass element 840 perpendicular to the thickness direction is a square. In some embodiments, the cross-sectional shape of mass element 840 perpendicular to the thickness direction is a rectangle. In some embodiments, the length of at least one side of the rectangle may be between 600 μm and 1200 μm. In some embodiments, the length of at least one side of the rectangle may be between 750 μm and 1050 μm.

[0163] In some embodiments, mass element 840 and acoustic transducer unit 820 in support arm 830 may be fabricated on different substrates (e.g., different silicon wafers) or on the same substrate. In some embodiments, when mass element 840 and acoustic transducer unit 820 in support arm 830 are fabricated on different substrates, mass element 840 may be fabricated on the substrate by a process such as photolithography or etching. The silicon substrate on which mass element 840 is fabricated and the substrate on which support arm 830 and base structure 810 are fabricated can then be bonded at the wafer level. In some embodiments, the bonding region may be the region of mass element 840. In other embodiments, the bonding region may include the region of mass element 840 and a portion of the region of base structure 810. In some embodiments, the area of the bonding region in base structure 810 may occupy 10% to 90% of the area of a cross section perpendicular to the thickness direction of base structure 810. In some embodiments, a wafer thinning process may be used to remove excess material, other than mass element 840, from the substrate on which mass element 840 is located. In some other embodiments, the mass element 840 can be fabricated on the substrate on which the support arm 830 is fabricated. Specifically, the other side of the substrate on which the support arm 830 is fabricated (the side opposite the side on which the support arm 830 is fabricated) can be etched to a certain depth using a deep silicon etching process after performing operations such as adhesive uniformization and photolithography development. Then, the mass element 840 is etched using a deep silicon etching process.

[0164] In some embodiments, the acoustic transducer unit 820 may include at least an effective acoustic transducer unit. The effective acoustic transducer unit is a partial structure of the acoustic transducer unit that ultimately outputs an electrical signal. In some embodiments, the effective acoustic transducer unit may include an overlapping region of the first electrode layer 821, the first piezoelectric layer 822, and the second electrode layer 823. For example, if the first electrode layer 821, the first piezoelectric layer 822, and the second electrode layer 823 all have the same shape and area and partially cover the support arm 830 (or the elastic layer 824), the first electrode layer 821, the first piezoelectric layer 822, and the second electrode layer 823 are an effective acoustic transducer unit. For example, when the first electrode layer 821 and the first piezoelectric layer 822 partially cover the support arm 830 and the second electrode layer 823 completely covers the support arm 830, the first electrode layer 821, the first piezoelectric layer 822, and the portion of the second electrode layer 823 that corresponds to the first electrode layer 821 constitute an effective acoustic transduction unit. For example, when the first electrode layer 821 partially covers the support arm 830 and the first piezoelectric layer 822 and the second electrode layer 823 both completely cover the support arm 830, the first electrode layer 821, the portion of the first piezoelectric layer 822 that corresponds to the first electrode layer 821, and the portion of the second electrode layer 823 that corresponds to the first electrode layer 821 constitute an effective acoustic transduction unit. Furthermore, for example, if the first electrode layer 821, the first piezoelectric layer 822, and the second electrode layer 823 completely cover the support arm 830, but the first electrode layer 821 is divided into multiple individual electrodes by providing isolation channels (e.g., electrode isolation channels 850) in the first electrode layer 821, the individual electrode portions in the first electrode layer 821 that derive electrical signals and the corresponding portions of the first piezoelectric layer 822 and the second electrode layer 823 are effective acoustic transduction units. The individual electrode regions in the first electrode layer 821 that do not derive electrical signals, and the regions of the first piezoelectric layer 822 and the second electrode layer 823 that correspond to the individual electrode regions in the first electrode layer 821 that do not derive electrical signals, do not provide electrical signals but mainly provide mechanical action.To improve the signal-to-noise ratio of bone conduction acoustic transmission device 800, an effective acoustic transducer unit may be located on support arm 830 adjacent to mass element 840 or adjacent to the connection between support arm 830 and base structure 810. In some embodiments, the effective acoustic transducer unit is located on support arm 830 adjacent to mass element 840. In some embodiments, when the effective acoustic transducer unit is located on support arm 830 adjacent to mass element 840 or adjacent to the connection between support arm 830 and base structure 810, the ratio of the area of support arm 830 covered by the effective acoustic transducer unit to the area of support arm 830 (the area of a cross section perpendicular to the thickness direction of support arm 830) is between 5% and 40%. In some embodiments, the ratio of the area of support arm 830 covered by the effective acoustic transducer unit to the area of support arm 830 (the area of a cross section perpendicular to the thickness direction of support arm 830) is between 25% and 40%. Furthermore, in some embodiments, the ratio of the area of the support arm 830 covered by the effective acoustic transducer unit to the area of the support arm 830 (the area of the cross section perpendicular to the thickness direction of the support arm 830) is 30% to 35%.

[0165] The signal-to-noise ratio (abbreviated as SNR) is the ratio of signal to noise in an electronic device or system. In a bone conduction audio transmission device, the larger the signal-to-noise ratio, the stronger the strength of the electrical signal of the bone conduction audio transmission device, the smaller the noise, and the more effective the bone conduction audio transmission device. Therefore, the signal-to-noise ratio is a very important parameter in the design process of a bone conduction audio transmission device, and in some embodiments, the signal-to-noise ratio SNR is used to determine the sensitivity V of the bone conduction audio transmission device. s and the noise floor V of the bone conduction acoustic transmission device ntrms In some embodiments, the signal-to-noise ratio SNR is related to the sensitivity V of the bone conduction acoustic transmission device. s and the noise floor V ntrms In some embodiments, the signal to noise ratio SNR is negatively correlated with

[0166]

number

[0167] In some embodiments, the signal-to-noise ratio (SNR) of the bone conduction acoustic transmission device can be calculated by the following equation (1):

[0168]

number

[0169] In the formula, V s is the sensitivity of the bone conduction acoustic transmission device. V s is related to the piezoelectric constant and the internal stress of the piezoelectric layer (e.g., the first piezoelectric layer 822), where the piezoelectric constant is related to the material of the piezoelectric layer, and the internal stress of the piezoelectric layer is related to the structure of the bone conduction acoustic transmitter and the external load. In some embodiments, after establishing the model, the sensitivity values V of different bone conduction acoustic transmitter structures under corresponding external loads can be calculated by the numerical method of finite element method. s V ntrms is the noise floor of the bone conduction acoustic transmission device, and the noise floor V ntrms is the noise floor value V of the amplifier circuit (ASIC) narms and the noise floor value V of the transducer (acoustic conversion unit) nsrms The noise floor V of the bone conduction acoustic transmission device can be determined by the following parameters: ntrms is the noise floor value V of the amplifier circuit (ASIC) narms and the noise floor value of the transducer V nsrms It is positively correlated with both V narms is the noise floor value of the amplifier circuit (ASIC), which can be calculated during the design process of the amplifier circuit or obtained from the manufacturer. In some embodiments, the noise floor V ntrms is the Boltzmann constant K B , temperature in degrees Fahrenheit T, electrostatic force constant k, dielectric loss tan δ of the piezoelectric layer (e.g., the first piezoelectric layer 822), and dielectric constant ε of the piezoelectric layer (e.g., the first piezoelectric layer 822).r , may be related to parameters such as the thickness d of the piezoelectric layer (e.g., the first piezoelectric layer 822), the area S of the effective acoustic conversion unit of the bone conduction acoustic transmission device, the low-frequency cutoff frequency f0 of the noise floor of the bone conduction acoustic transmission device, and the high-frequency cutoff frequency f1 of the noise floor of the bone conduction acoustic transmission device.

[0170] In some embodiments, the noise floor V of the bone conduction acoustic transmission device ntrms is the Boltzmann constant K B , temperature in degrees Fahrenheit T, electrostatic force constant k, dielectric constant ε of the piezoelectric layer (e.g., first piezoelectric layer 822) r , may be positively correlated with parameters such as the thickness d of the piezoelectric layer (e.g., the first piezoelectric layer 822) and the high frequency cutoff frequency f1 of the noise floor of the bone conduction acoustic transmission device. ntrms may be negatively correlated with the area S of the effective acoustic transducer unit of the bone conduction acoustic transmission device, the low-frequency cutoff frequency f of the noise floor of the bone conduction acoustic transmission device, and the dielectric loss tan δ of the piezoelectric layer (e.g., the first piezoelectric layer 822). In some embodiments, the noise floor V of the bone conduction acoustic transmission device ntrms can be calculated using the following formula (2).

[0171] V ntrms =f(V nsrms、 V narms )=f(K B ,T,k,tanδ,ε r ,d,S,f1,f0,V narms , ASIC gain) (2) where ASIC gain is the gain of the amplifier circuit, which can be calculated during the design process of the amplifier circuit or obtained from the manufacturer. B is the Boltzmann constant, T is the temperature in degrees Fahrenheit, k is the electrostatic force constant, tan δ is the dielectric loss of the piezoelectric layer (e.g., the first piezoelectric layer 822), and ε ris the dielectric constant of the piezoelectric layer (e.g., the first piezoelectric layer 822), d is the thickness of the piezoelectric layer (e.g., the first piezoelectric layer 822), S is the area of the effective acoustic transducer unit of the bone conduction acoustic transmission device, f0 is the low-frequency cutoff frequency of the noise floor of the bone conduction acoustic transmission device, and f1 is the high-frequency cutoff frequency of the noise floor of the bone conduction acoustic transmission device.

[0172] By substituting equation (2) into equation (1), we can obtain equation (3) which determines the signal-to-noise ratio (SNR) of the bone conduction acoustic transmission device.

[0173]

number

[0174] The meaning of each parameter in equation (3) is explained above. In equation (3), the dielectric loss tanδ of the piezoelectric material and the dielectric constant ε of the piezoelectric material are r is related to the material of the piezoelectric layer (e.g., the first piezoelectric layer 822). As can be seen from the above formula (3), the signal-to-noise ratio is related to factors such as the area of the effective acoustic transduction unit, the thickness of the piezoelectric layer (e.g., the first piezoelectric layer 822), the material of the piezoelectric layer (e.g., the first piezoelectric layer 822), and sensitivity (sensitivity is affected by the material and structure of the bone conduction acoustic transmission device).

[0175] By solving the equation based on the signal-to-noise ratio (SNR) of the bone conduction acoustic transmission device provided in this patent, materials such as the electrode layer (first electrode layer 821 and second electrode layer 823), piezoelectric layer (first piezoelectric layer 822 and second piezoelectric layer), elastic layer 824, and mass element 840 can be designed, and the structure of the bone conduction acoustic transmission device can be designed so that the design proposal meets the range requirement of the resonant frequency f0 and maximizes the signal-to-noise ratio (SNR) of the bone conduction acoustic transmission device. For example, a structure with a mass element added to a support arm (or a cantilever structure, a suspension membrane structure with holes, a suspension membrane structure with a mass element added, etc.) can be designed, and the sizes of different components of the bone conduction acoustic transmission device can be designed, such as the length, width, thickness, and effective acoustic conversion unit area of the support arm 830, mass element 840, etc. For example, in a structure in which a mass element is added to a support arm, the rigidity of support arm 830 and the mass of mass element 840 can be adjusted by designing the materials, sizes, etc. of each part of acoustic transducer unit 820, support arm 830, and mass element 840, thereby concentrating stress on support arm 830. The stress concentration on support arm 830 increases the output electrical signal of the bone conduction acoustic transmission device, thereby maximizing the output sensitivity and signal-to-noise ratio of the bone conduction acoustic transmission device. In the above design process, to ensure high reliability of the designed bone conduction acoustic transmission device, the signal-to-noise ratio (SNR) can be adjusted to be smaller than the maximum SNR by adjusting the materials, structure, and sizes of different components. For example, the SNR can be designed to be 80% to 100% of the maximum SNR, the SNR can be designed to be 50% to 100%, or the SNR can be designed to be 20% to 100% of the maximum SNR.

[0176] The smaller the area of support arm 830 covered by the effective acoustic transducer unit, the greater the strength of the ultimately generated electrical signal, but as the area of the effective acoustic transducer unit becomes smaller, its capacitance decreases, and the ultimately output noise increases. By setting the ratio of the area of support arm 830 covered by the effective acoustic transducer unit to the area of support arm 830 (the area of the cross section perpendicular to the thickness direction of support arm 830) to the above ratio (for example, 25% to 40%), the strength of the electrical signal generated by the effective acoustic transducer unit can be increased and noise can be reduced, thereby improving the acoustic transmission effect of bone conduction acoustic transmission device 800.

[0177] The signal-to-noise ratio of the bone conduction acoustic transmission device 800 is positively correlated with the strength of the output electrical signal, and when the laminated structure moves relative to the base structure 810, the deformation stress at the connection point between the support arm 830 and the mass element 840 and the connection point between the support arm 830 and the base structure 810 is greater than the deformation stress at the middle region of the support arm 830, and accordingly, the strength of the output voltage at the connection point between the support arm 830 and the mass element 840 and the connection point between the support arm 830 and the base structure 810 is also greater than the strength of the output voltage at the middle region of the support arm 830. 13 and 14 , when the acoustic transducer unit 820 completely or nearly completely covers the upper or lower surface of the support arm 830, an electrode isolation channel 850 may be provided in the first electrode layer 821 to improve the signal-to-noise ratio of the bone conduction acoustic transmission device 800. The electrode isolation channel 850 divides the first electrode layer 821 into two portions (or portions) such that one portion of the first electrode layer 821 is adjacent to the mass element 840 and the other portion of the first electrode layer 821 is adjacent to the connection point between the support arm 830 and the base structure 810. The portion of the first electrode layer 821 and its corresponding first piezoelectric layer 822 and second electrode layer 823 separated by the electrode isolation channel 850 that outputs the electrical signal is an effective acoustic transducer unit. In some embodiments, the electrode isolation channel 850 may be a straight line extending along the width direction of the support arm 830. In some embodiments, the width of electrode isolation channel 850 may be 20 μm or less. In some embodiments, the width of electrode isolation channel 850 may be between 2 μm and 20 μm. In some embodiments, the width of electrode isolation channel 850 may be between 4 μm and 10 μm.

[0178] In some embodiments, the electrode insulating channel 850 is disposed in the first electrode layer 821 or the second electrode layer 823. For example, when the acoustic transducer unit 820 is disposed on the upper surface of the support arm 830, the electrode insulating channel 850 is disposed in the first electrode layer 821, and when the acoustic transducer unit 820 is disposed on the lower surface of the support arm 830, the electrode insulating channel 850 is disposed in the second electrode layer 823. The electrode insulating channel 850 divides the first electrode layer 821 or the second electrode layer 823 into two or more electrode regions. The number of divided electrode regions may be two, three, five, etc. Designing the width of the electrode insulating channel 850 as described above can ensure that the electrode insulating channel 850 can be processed using a conventional processing process and, at the same time, minimize its impact on the SNR of the bone conduction microphone.

[0179] The stress from one end of the support arm 830 connected to the base structure 810 to the other end of the support arm 830 connected to the mass element 840 changes from tensile stress to compressive stress, or from compressive stress to tensile stress. The electrode layer (e.g., the first electrode layer 821) distributes electric charges on the surface of the piezoelectric layer (e.g., the first piezoelectric layer 822) and collects the electric charges. When the stress at different positions on the piezoelectric layer (e.g., the first piezoelectric layer 822) is different, the amount of output electric charges also differs. To maximize the output sensitivity of the bone conduction acoustic transmission device, the electrode layer (e.g., the first electrode layer 821) can be divided into multiple electrodes individually coated on the surface of the piezoelectric layer (e.g., the first piezoelectric layer 822) by the electrode isolation channel 850. When collecting signals, appropriate individual electrode layers can be selected based on the positions of the individual electrode layers to output the signals. When designing the electrode isolation channel 850, the area of the support arm 830 covered by the portion of the electrode layer that conducts the electrical signal can be made as large as possible to increase the output sensitivity and reduce the noise floor of the bone conduction acoustic transmission device, thereby increasing the signal-to-noise ratio (SNR).

[0180] The electrode insulating channel 850 is not limited to a straight line extending along the width direction of the support arm 830, but may be a curved line, a bent line, a wavy line, etc. Furthermore, the electrode insulating channel 850, for example, the electrode insulating channel 850 shown in Fig. 14, does not have to extend along the width direction of the support arm 830, and the electrode insulating channel 850 may be any channel as long as it can divide the acoustic transducer unit 820 into multiple parts, and is not further limited in this specification.

[0181] As shown in FIG. 14, when some structure of the acoustic transducer unit 820 (for example, the acoustic transducer unit between the electrode insulating channel 850 and the mass element 840 in FIG. 13) is installed in a position close to the mass element 840 of the support arm 830, the first electrode layer 821 and / or the second electrode layer 823 may further include an electrode lead 860. Taking the first electrode layer 821 as an example, the electrode insulating channel 850 divides the first electrode layer 821 into two parts, one part of the first electrode layer 821 connected to or adjacent to the mass element 840, and the other part of the first electrode layer 821 adjacent to the connection point between the support arm 830 and the base structure 810. In order to output a voltage for the part of the acoustic transducer unit 820 adjacent to the mass element 840, the electrode insulating channel 850 may divide a region (the region located at the edge of the support arm 830 in the first electrode layer 821 shown in FIG. 14 ) from the first electrode layer 821 adjacent to the connection point between the support arm 830 and the base structure 810, and this region electrically connects the part of the acoustic transducer unit 820 connected to or adjacent to the mass element 840 to the processing unit of the bone conduction acoustic transmission device 800. In some embodiments, the width L1 of the electrode lead 860 is 20 μm or less. In some embodiments, width L1 of electrode lead 860 may be 4 μm to 20 μm. In some embodiments, width L1 of electrode lead 860 may be 4 μm to 10 μm. In some embodiments, electrode lead 860 may be located at any position in the width direction of support arm 830; for example, electrode lead 860 may be located at a position close to the center or an edge of support arm 830 in the width direction. In some embodiments, electrode lead 860 may be located at a position close to an edge of support arm 830 in the width direction. By providing electrode lead 860, the use of conductive wires in acoustic transducer unit 820 can be avoided, simplifying the structure and facilitating subsequent manufacturing and assembly.

[0182] In some embodiments, the first electrode layer 821 has an electrode lead 860 that connects the electrode area to the base structure 810. In some embodiments, the electrode lead 860 outputs the electrical signal generated by the acoustic transducer unit 820 to the base structure 810, and the bonding wire electrode layer 826 can further conduct the electrical signal from the base structure 810. Designing the width of the electrode lead 860 makes it easy to plan the electrode area on the support arm 830 and also makes it easy to process the electrode lead 860.

[0183] Considering that etching may roughen the surface of the piezoelectric material of the first piezoelectric layer 822 in areas adjacent to the edges of the support arm 830, thereby reducing the quality of the piezoelectric material, in some embodiments, when the area of the first piezoelectric layer 822 is the same as the area of the second electrode layer 823, the area of the first electrode layer 821 is made smaller than the area of the first piezoelectric layer 822 to position the first electrode layer 821 in an area of high-quality piezoelectric material, thereby allowing the edge areas of the first electrode layer 821 to avoid the edge areas of the first piezoelectric layer 822 and forming electrode shrinkage channels 870 (as shown in FIG. 15 ) between the first electrode layer 821 and the first piezoelectric layer 822. By providing the electrode shrinkage channels 870, the first electrode layer 821 and the second electrode layer 823 can avoid the low-quality edge areas of the first piezoelectric layer 822, thereby improving the signal-to-noise ratio of the bone conduction acoustic transmission device 800. In some embodiments, the width of electrode contraction channel 870 can be between 2 μm and 20 μm, In some embodiments, the width of electrode contraction channel 870 can be between 2 μm and 10 μm.

[0184] In some embodiments, an electrode shrinkage channel 870 is formed at the edge of the first piezoelectric layer 822. The first electrode layer 821 is located in a region of the first piezoelectric layer 822 within the electrode shrinkage channel 870. In some embodiments, the width of the electrode shrinkage channel 870 is less than 20 μm. In some preferred embodiments, the width of the electrode shrinkage channel 870 may be 2 to 10 μm. Designing the width of the electrode shrinkage channel 870 allows for easy planning of the electrode area in the support arm 830 and also facilitates the processing of the electrode shrinkage channel 870.

[0185] In some embodiments, the bone conduction acoustic transmission device 800 may simultaneously include the electrode isolation channel 850, the electrode lead 860, and the electrode contraction channel 870 structures of one or more embodiments herein. The electrode isolation channel 850, the electrode lead 860, and the electrode contraction channel 870 may be manufactured by an etching method. For example, the first electrode layer 821, the first piezoelectric layer 822, and the second electrode layer 823 may be etched in that order. The etching of the first electrode layer 821, the first piezoelectric layer 822, and the second electrode layer 823 may be performed using dry etching or wet etching. If the elastic layer 824 is provided, the elastic layer 824 may also be etched. In some embodiments, after the etching of the electrode isolation channel 850, the electrode lead 860, and the electrode contraction channel 870 is completed, the bonding wire electrode layer 826 may be provided on the first electrode layer 821.

[0186] 16 , taking the case where the mass element 840 protrudes downward relative to the support arm 830 as an example, the acoustic transducer unit 820 may further include an extension region 8210 extending along the longitudinal direction of the support arm 830, where the extension region 8210 is located on the upper surface of the mass element 840. In some embodiments, the overlapping regions of the first electrode layer 821, the first piezoelectric layer 822, and the second electrode layer 823 extend toward the mass element 840 to form the extension region 8210 in the mass element 840. The extension region 8210 can prevent stress from concentrating at the connection point between the support arm 830 and the mass element 840. The extension region 8210 may be located on the upper surface of the mass element 840 or on the lower surface of the mass element 840. In some embodiments, an electrode insulating channel 850 is provided at an edge of the extension region 8210 located on the upper surface of the mass element 840, thereby preventing excessive stress concentration in the support arm 830 and improving the stability of the support arm 830. In some embodiments, the length of the extension region 8210 (length in a plane perpendicular to the thickness direction, see length W0 in FIG. 16 ) is greater than the width of the support arm 830 (width in a plane perpendicular to the thickness direction, see width W2 in FIG. 16 ). The length of the extension region 8210 here corresponds to the width along the support arm 830. In some embodiments, the length of the extension region 8210 (length in a plane perpendicular to the thickness direction, see length W0 in FIG. 16 ) is between 4 μm and 30 μm. In some embodiments, the length of the extension region 8210 is between 4 μm and 15 μm. In some embodiments, the width of extension region 8210 of mass element 840 (width in a plane perpendicular to the thickness direction, see width W1 in FIG. 16 ) is 1.2 to 2 times the width of the connection portion between support arm 830 and the edge of mass element 840 (width in a plane perpendicular to the thickness direction, see width W2 in FIG. 16 ). In some embodiments, the width of extension region 8210 of mass element 840 is 1.2 to 1.5 times the width of the connection portion between support arm 830 and the edge of mass element 840. In some embodiments, the width of extension region 8210 of mass element 840 is equal to the width of the connection portion between support arm 830 and the edge of mass element 840.

[0187] FIG. 17 is a schematic diagram of a bone conduction sound transmission device according to some embodiments of the present disclosure, and FIG. 18 is a cross-sectional view of the bone conduction sound transmission device shown in FIG. 17 taken along the line EE. The overall structure of the bone conduction sound transmission device 1700 shown in FIGS. 17 and 18 is substantially the same as the overall structure of the bone conduction sound transmission device 800 shown in FIG. 8 , except for the shape of the support arm. As shown in FIG. 17 , the base structure 1710 has a rectangular parallelepiped frame structure. In some embodiments, the interior of the base structure 1710 may include a hollow portion for suspending the acoustic transducer unit 1720 and the vibration unit. In some embodiments, the shape of the hollow portion may be any other regular or irregular shape, such as a circle, a square (e.g., a rectangle, a parallelogram), a pentagon, a hexagon, a heptagon, or an octagon. In some embodiments, the vibration unit may include four support arms 1730 and mass elements 1740, with one end of each of the four support arms 1730 connected to the upper surface, lower surface, or sidewall of the hollow portion of the base structure 1710, and the other end connected to the upper surface, lower surface, or circumferential sidewall of the mass element 1740. In some embodiments, the mass elements 1740 may protrude upward and / or downward relative to the support arms 1730. For example, if the ends of the four support arms 1730 are connected to the upper surface of the mass element 1740, the mass elements 1740 may protrude downward relative to the support arms 1730. For example, if the ends of the four support arms 1730 are connected to the lower surface of the mass element 1740, the mass elements 1740 may protrude upward relative to the support arms 1730. Further, for example, if the ends of the four support arms 1730 are connected to circumferential sidewalls of the mass element 1740, the mass element 1740 may protrude upward and downward relative to the support arm 1730. In some embodiments, the upper surface of the mass element 1740 is coplanar with the upper surface of the support arm 1730 and / or the lower surface of the mass element 1740 is coplanar with the lower surface of the support arm 1730. In some embodiments, the shape of the support arm 1730 is trapezoidal, i.e., the shape of a cross section perpendicular to the thickness direction of the support arm 1730 is trapezoidal.The shorter end of the support arm 1730 (the shorter side of the trapezoid) is connected to the mass element 1740, and the longer end of the support arm 1730 (the longer side of the trapezoid) is connected to the base structure 1710. In some other embodiments, the longer end of the support arm 1730 (the longer side of the trapezoid) is connected to the mass element 1740, and the shorter end of the support arm 1730 (the shorter side of the trapezoid) is connected to the base structure 1710.

[0188] In some embodiments, the height of the trapezoid (height h shown in FIG. 17 ) is between 150 μm and 600 μm. In some embodiments, the height of the trapezoid is between 200 μm and 500 μm. In some embodiments, the length of the longer side of the trapezoid is between 300 μm and 600 μm. In some embodiments, the length of the longer side of the trapezoid is between 350 μm and 550 μm. In some embodiments, the length of the shorter side of the trapezoid is between 100 μm and 400 μm. In some embodiments, the length of the shorter side of the trapezoid is between 150 μm and 300 μm. Furthermore, in some embodiments, the length of the shorter side of the trapezoid is between 150 μm and 250 μm. By designing the relevant dimensions of the support arm 1730 (e.g., the length of the longer side, the length of the shorter side, the height, etc. of the trapezoid), the rigidity of the support arm 1730 can be adjusted, thereby adjusting the resonant frequency of the bone conduction acoustic transmission device 1700.

[0189] In some embodiments, the acoustic transducer unit 1720 may include a first electrode layer 1721, a first piezoelectric layer 1722, a second electrode layer 1723, an elastic layer 1731, a first seed layer (1724), and a bonding wire electrode layer (not shown). The materials, thicknesses, placement order, and manufacturing methods of each layer are similar to those of the embodiment shown in FIG. 8, and therefore will not be described again.

[0190] In some embodiments, to improve the signal-to-noise ratio of bone conduction acoustic transmission device 1700, an effective acoustic transducer unit may be located on support arm 1730 proximate mass element 1740 or proximate a connection between support arm 1730 and base structure 1710. In some embodiments, the effective acoustic transducer unit is located on support arm 1730 proximate mass element 1740. In some embodiments, when the effective acoustic transducer unit is located on support arm 1730 proximate mass element 1740 or proximate a connection between support arm 1730 and base structure 1710, the ratio of the area of support arm 1730 covered by the effective acoustic transducer unit to the area of support arm 1730 is between 5% and 40%. In some embodiments, the ratio of the area of support arm 1730 covered by the effective acoustic transducer unit to the area of support arm 1730 (the area of a cross section perpendicular to the thickness direction of support arm 1730) is between 10% and 35%. Furthermore, in some embodiments, the ratio of the area of the support arm 1730 covered by the effective acoustic transducer unit to the area of the support arm 1730 (the area of the cross section perpendicular to the thickness direction of the support arm 1730) is 15% to 20%.

[0191] The signal-to-noise ratio of the bone conduction acoustic transmission device 1700 is positively correlated with the strength of the output electrical signal, and when the laminated structure moves relative to the base structure 1710, the deformation stress at the connection point between the support arm 1730 and the mass element 1740 and the connection point between the support arm 1730 and the base structure 1710 is greater than the deformation stress at the middle region of the support arm 1730, and accordingly, the strength of the output voltage at the connection point between the support arm 1730 and the mass element 1740 and the connection point between the support arm 1730 and the base structure 1710 is also greater than the strength of the output voltage at the middle region of the support arm 1730. In some embodiments, when acoustic transducer unit 1720 completely or nearly completely covers the upper or lower surface of support arm 1730, as shown in FIG. 19 , an electrode isolation channel 1750 may be provided in first electrode layer 1721 to improve the signal-to-noise ratio of bone conduction acoustic transmission device 1700. The electrode isolation channel 1750 divides first electrode layer 1721 into at least two portions, such that one portion of first electrode layer 1721 is adjacent to mass element 1740 and the other portion of first electrode layer 1721 is adjacent to the connection between support arm 1730 and base structure 1710. In some embodiments, electrode isolation channel 1750 may be a straight line extending along the width direction of support arm 1730. In some embodiments, the width of electrode isolation channel 1750 may be between 2 μm and 20 μm. In some embodiments, the width of electrode isolation channel 1750 may be between 4 μm and 10 μm.

[0192] Note that the electrode insulating channel 1750 is not limited to a straight line extending along the width direction of the support arm 1730, but may be a curved line, a bent line, a wavy line, etc. Furthermore, the electrode insulating channel 1750, for example, the electrode insulating channel 1750 shown in Fig. 20 does not have to extend along the width direction of the support arm 1730, and the electrode insulating channel 1750 may be capable of dividing the acoustic transducer unit 1720 into multiple parts, and is not further limited in this specification.

[0193] 20 , when a portion of the structure of the acoustic transducer unit 1720 (for example, the acoustic transducer unit between the electrode insulating channel 1750 and the mass element 1740 in FIG. 19 ) is located adjacent to the mass element 1740 of the support arm 1730, the first electrode layer 1721 and / or the second electrode layer 1723 may further include an electrode lead 1760. Taking the first electrode layer 1721 as an example, the electrode insulating channel 1750 divides the first electrode layer 1721 into two portions, one portion of the first electrode layer 1721 connected to or adjacent to the mass element 1740, and the other portion of the first electrode layer 1721 adjacent to the connection point between the support arm 1730 and the base structure 1710, and is supported by the electrode insulating channel 1750 to output a voltage for the portion of the acoustic transducer unit 1720 adjacent to the mass element 1740. A region (the region located at the edge of the support arm 1730 in the illustrated first electrode layer 1721, referred to as electrode lead 1760) may be separated from the first electrode layer 1721 adjacent to the connection between the arm 1730 and the base structure 1710, and the electrode lead 1760 electrically connects the portion of the acoustic transducer unit 1720 connected to the mass element 1740 or adjacent to the mass element 1740 to the processing unit of the bone conduction acoustic transmission device 1700. In some embodiments, the width L2 of the electrode lead 1760 may be 4 μm to 20 μm. In some embodiments, the width L2 of the electrode lead 1760 may be 4 μm to 10 μm. In some embodiments, the electrode lead 1760 may be located at any position in the width direction of the support arm 1730; for example, the electrode lead 1760 may be located at the center of the support arm 1730 or adjacent to an edge in the width direction. In some embodiments, the electrode lead 1760 may be located near a widthwise edge of the support arm 1730. By locating the electrode lead 1760, the use of conductive wires in the acoustic transducer unit 1720 can be avoided, simplifying the structure and facilitating subsequent manufacturing and assembly.

[0194] Etching can roughen the surface of the piezoelectric material of the first piezoelectric layer 1722 in areas close to the edges of the support arm 1730, reducing the quality of the piezoelectric material. In some embodiments, when the area of the first piezoelectric layer 1722 is the same as the area of the second electrode layer 1723, the area of the first electrode layer 1721 can be made smaller than the area of the first piezoelectric layer 1722 in order to position the first electrode layer 1721 within the high-quality piezoelectric material area of the first piezoelectric layer 1722, thereby allowing the edge areas of the first electrode layer 1721 to avoid the edge areas of the first piezoelectric layer 1722 and forming an electrode contraction channel between the first electrode layer 1721 and the first piezoelectric layer 1722 (the structure of the electrode contraction channel is similar to the structure of the electrode contraction channel 870 in FIG. 15 ). By providing the electrode contraction channels, first electrode layer 1721 and second electrode layer 1723 can avoid low-quality areas at the edges of first piezoelectric layer 1722, thereby improving the signal-to-noise ratio of bone conduction acoustic transmission device 1700. In some embodiments, the width of the electrode contraction channels can be between 2 μm and 20 μm. In some embodiments, the width of the electrode contraction channels can be between 2 μm and 10 μm.

[0195] 20 , in some embodiments, for example, when mass element 1740 protrudes downward relative to support arm 1730, acoustic transducer unit 1720 may further include extension region 17210 extending along the longitudinal direction of support arm 1730, where extension region 17210 is located on the upper surface of mass element 1740. In some embodiments, overlapping regions of first electrode layer 1721, first piezoelectric layer 1722, and second electrode layer 1723 extend toward mass element 1740 to form extension region 17210. Extension region 17210 may be located on the upper surface of mass element 1740 or on the lower surface of mass element 1740. In some embodiments, electrode insulating channel 1750 may be provided at an edge of extension region 17210 located on the upper surface of mass element 1740, thereby preventing excessive stress concentration in support arm 1730 and improving the stability of support arm 1730. In some embodiments, the width of extension region 17210 (the width in a plane perpendicular to the thickness direction, see width W3 in FIG. 20 ) is greater than the width of support arm 1730 (the width in a plane perpendicular to the thickness direction, see width W4 in FIG. 20 ). The width of extension region 17210 here corresponds to the width of support arm 1730. In some embodiments, the width of extension region 17210 is 4 μm to 30 μm. In some embodiments, the width of extension region 17210 is 4 μm to 15 μm. In some embodiments, the width of extension region 17210 in mass element 1740 is 1.2 to 2 times the width of the connection portion between support arm 1730 and the edge of mass element 1740. In some embodiments, the width of extension region 17210 in mass element 1740 is 1.2 to 1.5 times the width of the connection portion between support arm 1730 and the edge of mass element 1740. For parameters such as materials and sizes of the structures of the acoustic conversion unit 1720, the first electrode layer 1721, the second electrode layer 1723, the first piezoelectric layer 1722, the vibration unit, the mass element 1740, etc. in this embodiment, please refer to the contents of Figures 8 to 16, and explanations will be omitted in this specification.

[0196] FIG. 21 is a schematic diagram of a bone conduction sound transmission device according to some embodiments of the present application, and FIG. 22 is a schematic front view of the bone conduction sound transmission device shown in FIG. 21. The overall structure of the bone conduction sound transmission device 2100 shown in FIGS. 21 and 22 is substantially the same as the overall structure of the bone conduction sound transmission device 800 shown in FIG. 8, except for the shape of the support arms. As shown in FIG. 21, the base structure 2110 has a rectangular parallelepiped frame structure. In some embodiments, the interior of the base structure 2110 may include a hollow portion for suspending the acoustic transducer unit and the vibration unit. In some embodiments, the vibration unit may include four support arms 2130 and a mass element 2140. One end of each of the four support arms 2130 is connected to the upper or lower surface of the base structure 2110 or a sidewall of the hollow portion of the base structure 2110, and the other end is connected to the upper or lower surface or a circumferential sidewall of the mass element 2140. In some embodiments, the mass element 2140 may protrude upward and / or downward relative to the support arm 2130. For example, if the ends of the four support arms 2130 are connected to the top surface of the mass element 2140, the mass element 2140 may protrude downward relative to the support arm 2130. For example, if the ends of the four support arms 2130 are connected to the bottom surface of the mass element 2140, the mass element 2140 may protrude upward relative to the support arm 2130. For example, if the ends of the four support arms 2130 are connected to the circumferential sidewalls of the mass element 2140, the mass element 2140 may protrude upward and downward relative to the support arm 2130. In some embodiments, the shape of the support arm 2130 is trapezoidal, i.e., the shape of a cross section perpendicular to the thickness direction of the support arm 2130 is trapezoidal. The longer end of support arm 2130 (the longer side of the trapezoid) is connected to mass element 2140 and the shorter end of support arm 2130 (the shorter side of the trapezoid) is connected to base structure 2110. In some other embodiments, the shorter end of support arm 2130 (the shorter side of the trapezoid) is connected to mass element 2140 and the longer end of support arm 2130 (the longer side of the trapezoid) is connected to base structure 2110.Note that the parameters such as the structure, size, thickness, etc. of components such as the acoustic conversion unit 820, the first electrode layer 821, the second electrode layer 823, the first piezoelectric layer 822, the vibration unit, the mass element 840, the extension region 8210, the electrode insulation channel 850, the electrode lead 860, and the electrode contraction channel 870 in Figures 8 to 10 can be applied to the bone conduction acoustic transmission device 2100 and will not be further described in this specification.

[0197] In some preferred embodiments, when the cross section of the support arm perpendicular to the thickness direction is polygonal (e.g., rectangular or trapezoidal), the mass element can be installed so as to protrude upward or downward relative to the support arm. The mass element installed in this manner can increase the deformation stress when the support arm deforms, thereby increasing the strength of the electrical signal output from the acoustic conversion unit.

[0198] Fig. 23 is a schematic diagram of a bone conduction sound transmission device according to some embodiments of the present application, Fig. 24 is a front view of the bone conduction sound transmission device shown in Fig. 23, and Fig. 25 is a cross-sectional view of the bone conduction sound transmission device shown in Fig. 24 taken along line F-F. The structure of the bone conduction sound transmission device 2300 shown in Fig. 23 to Fig. 25 is substantially the same as the structure of the bone conduction sound transmission device 800 shown in Fig. 8, except that the support arm 2330 of the bone conduction sound transmission device 2300 is different in structure and shape from the support arm 830 of the bone conduction sound transmission device 800. In some embodiments, the interior of the base structure 2310 may include a hollow portion for suspending the acoustic conversion unit 2320 and the vibration unit. In some embodiments, the vibration unit may include four support arms 2330 and mass elements 2340, with one end of each of the four support arms 2330 connected to the upper surface, lower surface, or sidewall of the hollow portion of the base structure 2310, and the other end connected to the upper surface, lower surface, or circumferential sidewall of the mass element 2340. In some embodiments, the mass elements 2340 may protrude upward and / or downward relative to the support arms 2330. For example, if the ends of the four support arms 2330 are connected to the upper surface of the mass element 2340, the mass elements 2340 may protrude downward relative to the support arms 2330. For example, if the ends of the four support arms 2330 are connected to the lower surface of the mass element 2340, the mass elements 2340 may protrude upward relative to the support arms 2330. Further, for example, when the ends of the four support arms 2330 are connected to the circumferential sidewalls of the mass element 2340, the mass element 2340 may protrude upward and downward relative to the support arm 2330. In some embodiments, the upper surface of the mass element 2340 is flush with the upper surface of the support arm 2330 and / or the lower surface of the mass element 2340 is flush with the lower surface of the support arm 2330. In some embodiments, the shape of the support arm 2330 may be a generally L-shaped structure. As shown in FIG. 23 , the support arm 2330 may include a first band 2331 and a second band 2332, where one end of the first band 2331 is connected to one end of the second band 2332, and the first band 2331 and the second band 2332 form a certain included angle.In some embodiments, the included angle is in the range of 75° to 105°. In some embodiments, one end of second strip 2332 remote from the connection between first strip 2331 and second strip 2332 is connected to base structure 2310, and one end of first strip 2331 remote from the connection between first strip 2331 and second strip 2332 is connected to a top surface, bottom surface, or peripheral sidewall of mass element 2340, thereby suspending mass element 2340 in the hollow portion of base structure 2310.

[0199] 23-25, the support arm 2330 includes two strips: a first strip 2331 and a second strip 2332. In some embodiments, the first strip 2331 is connected at one end to the mass element 2340 and at the other end to one end of the second strip 2332, the other end of which is connected to the base structure 2310. Compared to a polygonal support arm, the support arm 2330 including the first band 2331 and the second band 2332 can be designed to be long within a limited space, so the rigidity of the support arm 2330 is reduced, and the mass of the mass element 2340 can be set accordingly to be smaller (for example, since there is no need to protrude upward and downward relative to the support arm 2330, there is no need to further process the structures that protrude upward or downward for the mass element 2340), thereby simplifying the manufacturing process of the mass element 2340.

[0200] In this embodiment, support arm 2330 and mass element 2340 may be manufactured by the manufacturing process introduced above. Also, in this embodiment, if there is no need to install mass element 2340 that protrudes upward or downward relative to support arm 2330, support arm 2330 and mass element 2340 may be manufactured on the same substrate at the same time, thereby simplifying the fabrication process.

[0201] The connection point between the first strip 2331 and the mass element 2340 may be located at any position on the side of the polygon, such as at the end of the side or the midpoint of the side. In some embodiments, the connection point between the first strip 2331 and the mass element 2340 is located at the end of the side of the polygon (as shown in FIG. 24 ). In some embodiments, the width N1 of the first strip 2331 is between 50 μm and 300 μm. In some embodiments, the width N1 of the first strip 2331 is between 80 and 200 μm. In some embodiments, the width N2 of the second strip 2332 is between 50 μm and 300 μm. In some embodiments, the width N2 of the second strip 2332 is between 80 and 200 μm. In some embodiments, the length L1 of the first strip 2331 is between 20 μm and 200 μm. In some embodiments, the length L1 of the first strip 2331 is between 30 μm and 100 μm. In some embodiments, the length L2 of the second strip 2332 is between 800 μm and 1300 μm. In some embodiments, the length L2 of the second strip 2332 is between 900 μm and 1200 μm.

[0202] In some embodiments, the included angle (longitudinal angle) between first band 2331 and second band 2332 may be between 60° and 120°. In some embodiments, the included angle (longitudinal angle) between first band 2331 and second band 2332 may be between 75° and 105°. In some embodiments, the included angle (longitudinal angle) between first band 2331 and second band 2332 may be 90° (i.e., the longitudinal direction of first band 2331 is perpendicular to the longitudinal direction of second band 2332).

[0203] In some embodiments, first strip 2331 is connected at one end to mass element 2340 and at the other end to a location midway along second strip 2332 (e.g., the other end of first strip 2331 is connected to a mid-length portion of second strip 2332). One end of second strip 2332 is connected to base structure 2310 (or both ends of second strip 2332 are connected to base structure 2310). As can be appreciated, when connected in this manner, support arm 2330 is "T" shaped.

[0204] FIG. 30 is a schematic diagram of a bone conduction acoustic transmission device 2300 according to some other embodiments of the present application. The embodiment shown in FIG. 30 differs from the embodiment shown in FIG. 24 in the connection position between the support arm and the mass element. As shown in FIG. 30, the connection point between the first strip portion 2331 and the mass element 2340 is located in the middle region of the polygonal side of the mass element 2340 (e.g., the midpoint of the side). In some embodiments, the width N3 of the first strip portion 2331 is 100 μm to 400 μm. In some embodiments, the width N3 of the first strip portion 2331 is 150 to 300 μm. In some embodiments, the width N4 of the second strip portion 2332 is 100 μm to 400 μm. In some embodiments, the width N4 of the second strip portion 2332 is 150 to 300 μm. In some embodiments, the length L3 of the first band 2331 is between 20 μm and 200 μm. In some embodiments, the length L3 of the first band 2331 is between 30 μm and 100 μm. In some embodiments, the length L4 of the second band 2332 is between 500 μm and 1000 μm. In some embodiments, the length L4 of the second band 2332 is between 700 μm and 900 μm.

[0205] In some embodiments, the angle between first band 2331 and second band 2332 may be approximately the same as the angle between two adjacent sides of a polygon. For example, if the polygon is a regular hexagon, the angle between the two adjacent sides may be 120°, and the angle between first band 2331 and second band 2332 may be approximately 120°. In some embodiments, if the cross section of mass element 2340 perpendicular to the thickness direction is rectangular, first band 2331 is perpendicular to second band 2332. With this design, the layout of bone conduction acoustic transmission device 2300 is more compact.

[0206] Fig. 26 is a schematic diagram of the bone conduction sound transmission device shown in Fig. 23, Fig. 27 is another schematic diagram of the bone conduction sound transmission device shown in Fig. 23, Fig. 28 is yet another schematic diagram of the bone conduction sound transmission device shown in Fig. 23, and Fig. 29 is yet another schematic diagram of the bone conduction sound transmission device shown in Fig. 23. Fig. 26 mainly shows the electrode insulation channel 2350 when the support arm 2330 includes two band-like portions, Fig. 27 mainly shows the electrode insulation channel 2350 and the electrode lead 2360 when the support arm 2330 includes two band-like portions, Fig. 28 mainly shows the electrode contraction channel 2370 when the support arm 2330 includes two band-like portions, and Fig. 29 mainly shows the extension region 2380 when the support arm 2330 includes two band-like portions. As shown in Figures 26 to 29, in some embodiments, the acoustic transducer unit 2320 may have a multi-layer structure and may include structures such as a first electrode layer 2321, a second electrode layer 2323, a first piezoelectric layer 2322, an elastic layer 2324, a seed layer, a bonding wire electrode layer 2326, an extension region 2380, an electrode insulation channel 2350, an electrode lead 2360, and an electrode contraction channel 2370. For each layer structure of the acoustic conversion unit 2320, the mass element 2340, etc., reference can be made to the descriptions of parameters such as the structure, size, thickness, etc. of components such as the acoustic conversion unit 820, the first electrode layer 821, the second electrode layer 823, the first piezoelectric layer 822, the vibration unit, the mass element 840, the extension region 8210, the electrode insulation channel 850, the electrode lead 860, and the electrode contraction channel 870 in Figures 8 to 10 of the present specification, and the descriptions of these parameters may also be used for the bone conduction acoustic transmission device 2300 shown in Figure 23 and will not be further described in this specification.

[0207] 31 is a schematic diagram of a bone conduction acoustic transmission device 3100 according to some embodiments of the present application. The bone conduction acoustic transmission device 3100 includes a base structure 3110. As shown in FIG. 31 , in some embodiments, a support arm 3130 includes three bands: a first band 3131, a second band 3132, and a third band 3133. The first band 3131 has one end connected to a mass element 3140 and the other end connected to one end of the second band 3132. The other end of the second band 3132 is connected to one end of the third band 3133, and the other end of the third band 3133 is connected to the base structure. Such a structural design allows the support arm 3130 to be designed longer within a limited space, thereby reducing the stiffness of the support arm 3130 and allowing the mass of the mass element 3140 to be set accordingly smaller (e.g., there is no need for it to protrude upward and downward relative to the support arm), thereby further simplifying the manufacturing process of the mass element 3140.

[0208] The connection point between the first band 3131 and the mass element 3140 may be located at any position on the side of the polygon, such as at the end of the side or the midpoint of the side. In some embodiments, as shown in FIG. 31 , the connection point between the first band 3131 and the mass element 3140 is located at the end of the side of the polygon. In some embodiments, the width N5 of the first band 3131 may be between 50 μm and 300 μm. In some embodiments, the width N5 of the first band 3131 may be between 80 μm and 150 μm. In some embodiments, the width N6 of the second band 3132 may be between 50 μm and 300 μm. In some embodiments, the width N6 of the second band 3132 may be between 80 μm and 150 μm. In some embodiments, the width N7 of the third band 3133 may be between 50 μm and 300 μm. In some embodiments, the width N7 of the third band 3133 is between 80 μm and 150 μm. In some embodiments, the length L5 of the first band 3131 may be between 20 μm and 200 μm. In some embodiments, the length L5 of the first band 3131 is between 30 μm and 100 μm. In some embodiments, the length L6 of the second band 3132 is between 600 μm and 1200 μm. In some embodiments, the length L6 of the second band 3132 is between 800 μm and 1000 μm. In some embodiments, the length L7 of the third band 3133 may be between 800 μm and 1300 μm. In some embodiments, the length L7 of the third band 3133 is between 900 μm and 1200 μm.

[0209] FIG. 32 is a schematic diagram of a bone conduction acoustic transmission device 3100 according to some other embodiments of the present application. As shown in FIG. 32, the connection point between the first strip-shaped portion 3131 and the mass element 3140 is located at the midpoint of a side of a polygon. In some embodiments, the width N8 of the first strip-shaped portion 3131 is 50 μm to 300 μm. In some embodiments, the width N8 of the first strip-shaped portion 3131 is 80 μm to 150 μm. In some embodiments, the width N9 of the second strip-shaped portion 3132 is 50 μm to 300 μm. In some embodiments, the width N9 of the second strip-shaped portion 3132 is 80 μm to 150 μm. In some embodiments, the width N10 of the third strip-shaped portion 3133 is 50 μm to 300 μm. In some embodiments, the width N10 of the third strip-shaped portion 3133 is 80 μm to 150 μm. In some embodiments, the length L8 of the first band 3131 is between 20 μm and 200 μm. In some embodiments, the length L8 of the first band 3131 is between 30 μm and 100 μm. In some embodiments, the length L9 of the second band 3132 is between 500 μm and 1000 μm. In some embodiments, the length L9 of the second band 3132 is between 600 μm and 800 μm. In some embodiments, the length L10 of the third band 3133 is between 800 μm and 1300 μm. In some embodiments, the length L10 of the third band 3133 is between 900 μm and 1200 μm.

[0210] In some embodiments, the included angle between first band 3131 and second band 3132 and the included angle between second band 3132 and third band 3133 may be approximately the same as the included angle between two adjacent sides of a polygon. For example, if the polygon is a regular hexagon, the included angle between two adjacent sides may be 120°, the included angle between first band 3131 and second band 3132 may be approximately 120°, and the included angle between second band 3132 and third band 3133 may be approximately 120°. In some embodiments, to make the structure of the bone conduction acoustic transmission device 3100 more compact, the cross section perpendicular to the thickness direction of the mass element 3140 is rectangular, the second band portion 3132 is perpendicular or approximately perpendicular to the first band portion 3131, and the second band portion 3132 is perpendicular or approximately perpendicular to the third band portion 3133.

[0211] In some embodiments, the support arm may include more bands, for example, a fourth band, a fifth band, etc. The number of bands included in the support arm may be specifically designed depending on the stiffness of the support arm.

[0212] FIG. 33 is another schematic diagram of the bone conduction acoustic transmission device 3100 shown in FIG. 32. An electrode insulating channel 3150 is shown in FIG. 33. In some embodiments, the acoustic transducer unit 3120 has a multi-layer structure and may include structures such as a first electrode layer, a second electrode layer, a first piezoelectric layer, an elastic layer, a seed layer, an electrode insulating channel 3150, and an electrode contraction channel. For the layer structures of the acoustic transducer unit 3120, the mass element 3140, and the like, please refer to the descriptions of parameters such as the structure, size, and thickness of the acoustic transducer unit 820, the first electrode layer 821, the second electrode layer 823, the first piezoelectric layer 822, the vibration unit, the mass element 840, the extension region 8210, the electrode insulating channel 850, the electrode lead 860, and the electrode contraction channel 870 in FIGS. 8 to 10 of the present specification, and further description thereof will not be given herein.

[0213] In some embodiments, the total thickness of the support arm and the acoustic transducer unit is less than the thickness of the mass element. As will be appreciated, if the acoustic transducer unit is located on the upper or lower surface of the support arm, the total thickness of the support arm and the acoustic transducer unit may be the sum of the thicknesses of both. If the acoustic transducer unit is located inside the support arm, the total thickness of the support arm and the acoustic transducer unit may be the thickness of the support arm including the acoustic transducer unit located inside. If the cross section of the support arm perpendicular to the thickness direction is a polygon, such as a rectangle or a trapezoid, the stiffness of the support arm may be high, and the thickness of the mass element may be set accordingly large to increase the mass of the mass element, thereby allowing the resonant frequency of the bone conduction acoustic transmission device to fall within the limited range in one or more of the above embodiments. In some embodiments, the total thickness of the support arm and the acoustic transducer unit is greater than or equal to the thickness of the mass element. If the support arm includes two bands (e.g., the support arm includes a first band and a second band), or if the support arm includes three bands (e.g., the support arm includes a first band, a second band, and a third band), or if the support arm includes more bands, the stiffness of the support arm may be smaller, and therefore the thickness of the mass element can be set accordingly smaller to reduce the mass of the mass element, thereby allowing the resonant frequency of the bone conduction acoustic transmission device to be within the limited range in one or more of the above embodiments.

[0214] In some embodiments, the bone conduction acoustic transmission device according to any one of the above embodiments may further include a stopper structure (not shown), which may be a plate-like structure. In some embodiments, the stopper structure may be located in a hollow portion of the base structure, or may be located above or below the laminated structure and installed facing the laminated structure. In some embodiments, when the base structure is a vertically penetrating structure, the stopper structure may be located at the top or bottom of the base structure. The stopper structure and the mass element of the laminated structure are installed at a distance from each other, and when a large impact is received, the stopper structure limits the amplitude of the mass element of the laminated structure, thereby preventing severe vibrations from damaging the device. In some embodiments, the stopper structure may be a rigid structure (e.g., a stopper) or a structure having a certain degree of elasticity (e.g., an elastic cushion, a shock-absorbing cantilever, or a structure in which a shock-absorbing support arm and a stopper are installed simultaneously).

[0215] The laminated structure has a natural frequency, and when the frequency of an external vibration signal is close to the natural frequency, the laminated structure generates a large amplitude and outputs a large electrical signal. Therefore, the response of the bone conduction acoustic transmission device to external vibration is expressed as a resonance peak occurring near the natural frequency. In some embodiments, by changing the parameters of the laminated structure to adjust the natural frequency of the laminated structure within the audio frequency range, the resonance peak of the bone conduction acoustic transmission device can be brought within the audio frequency range, thereby improving the response sensitivity of the bone conduction acoustic transmission device to vibrations in the audio frequency range (e.g., the frequency range before the resonance peak). As shown in FIG. 34 , the frequency corresponding to the resonance peak 3401 in the frequency response curve in which the natural frequency of the laminated structure is lowered (the solid curve in FIG. 34 ) is lower than the frequency corresponding to the resonance peak 3402 in the frequency response curve in which the natural frequency of the laminated structure is not changed (the dashed curve in FIG. 34 ). For external vibration signals whose frequencies are lower than the frequency at which the resonance peak 3401 is located, the bone conduction acoustic transmission device corresponding to the solid curve has higher sensitivity.

[0216] The displacement output formula of the laminated structure is as follows:

[0217]

number

[0218] where M is the mass of the laminated structure, R is the damping of the laminated structure, K is the elastic modulus of the laminated structure, F is the amplitude of the driving force, Xa is the displacement of the laminated structure, ω is the angular frequency of the external force, and ω is the natural frequency of the laminated structure.

[0219]

number

[0220] If so, ωM <Kω -1 If the natural frequency ω0 of the laminated structure is reduced (by increasing M, or decreasing K, or by increasing M and decreasing K), then |ωM <Kω -1 | becomes smaller, and the corresponding displacement output X a If the frequency of the excitation force is ω=ω0, then ωM=Kω -1 When the natural frequency ω0 of the vibration-electrical signal conversion element (laminated structure) is changed, the corresponding displacement output X a does not change. If the frequency of the excitation force is ω>ω0, then ωM>Kω -1 When the natural frequency ω0 of the vibration-electric signal conversion element is reduced (by increasing M, or decreasing K, or by increasing M and decreasing K), |ωM <Kω -1 | becomes larger and the corresponding displacement output X a becomes smaller.

[0221] As the resonance peak advances, a peak value appears in the audio frequency band. When the bone conduction audio transmission device picks up a signal, there is too much signal in the resonance peak frequency band, which reduces the communication effect. In some embodiments, to improve the quality of the audio signal collected by the bone conduction audio transmission device, a damping structure layer may be installed in the laminated structure, which can increase the energy loss of the laminated structure during vibration, especially the loss in the resonance frequency band. Here, the damping coefficient is described as follows using the inverse of the mechanical quality factor, 1 / Q:

[0222]

number

[0223] In the formula, Q -1 is the reciprocal of the quality factor, also called the structural loss factor η, Δf is the frequency difference value f1-f2 at half the resonance amplitude (also called the 3 dB bandwidth), and f0 is the resonance frequency.

[0224] The relationship between the loss factor η of the laminated structure and the loss factor tan δ of the damping material is as follows:

[0225]

number

[0226] where X is a shear parameter, which is related to the thickness and material properties of each layer in the laminate structure, and Y is a stiffness parameter, which is related to the thickness and Young's modulus of each layer in the laminate structure.

[0227] As can be seen from Equations (5) and (6), the loss factor η of the laminated structure can be adjusted within an appropriate range by adjusting the material of the damping structure layer and the material of each layer of the laminated structure. As the damping structure layer of the laminated structure increases, the mechanical quality factor Q decreases, and the corresponding 3 dB bandwidth increases. The damping structure layer's attenuation varies under different stress (deformation) conditions, for example, when the stress is high or the amplitude is large. Therefore, based on the characteristic that the amplitude of the laminated structure is small in the non-resonance region and large in the resonance region, increasing the number of damping structure layers can ensure that the sensitivity of the bone conduction acoustic transmission device in the non-resonance region is not reduced, while reducing the Q value in the resonance region and flattening the frequency response of the bone conduction acoustic transmission device across the entire frequency band. Figure 35 shows frequency response curves of bone conduction acoustic transmission devices with and without damping structure layers according to some embodiments of the present application. As shown in Figure 35, the frequency response curve 3502 of the electrical signal output by a bone conduction acoustic transmission device having an attenuation structure layer is flatter than the frequency response curve 3501 of the electrical signal output by a bone conduction acoustic transmission device not having an attenuation structure layer.

[0228] In some embodiments, the bone conduction acoustic transmission device may include at least one damping structure layer, and the peripheral side of the at least one damping structure layer may be connected to the base structure. In some embodiments, the at least one damping structure layer may be located on the upper and / or lower surface of the laminate structure, or between multiple layers of the laminate structure. In some embodiments, for macro-sized laminate structures and base structures, the damping structure layer may be directly bonded to the base structure or the surface of the laminate structure. In some embodiments, for MEMS devices, the damping structure layer may be connected to the laminate structure and base structure by semiconductor processes such as vapor deposition, spin coating, microassembly, etc. In some embodiments, the shape of the damping structure layer may be a regular shape such as a circle, ellipse, triangle, square, hexagon, or octagon. In some embodiments, the output effect of the electrical signal from the bone conduction acoustic transmission device can be improved by selecting the material, size, thickness, etc. of the damping film.

[0229] To more clearly explain the damping structure layer, a cantilever-type bone conduction sound transmission device (e.g., the bone conduction sound transmission device 100 shown in FIG. 1, the bone conduction sound transmission device 300 shown in FIG. 3, and the bone conduction sound transmission device 400 shown in FIG. 4) will be described as an example. FIG. 36 is a cross-sectional view of a bone conduction sound transmission device according to some embodiments of the present application. As shown in FIG. 36, the bone conduction sound transmission device 3600 may include a base structure 3610, a laminated structure 3620, and a damping structure layer 3630. Furthermore, the laminated structure 3620 has one end connected to the upper surface of the base structure 3610 and the other end suspended in the hollow portion of the base structure 3610, and the damping structure layer 3630 is located on the upper surface of the laminated structure 3620. The area of the damping structure layer 3630 may be larger than the area of the laminated structure 3620, i.e., the damping structure layer 3630 may not only cover the upper surface of the laminated structure 3620 but also cover the gap between the laminated structure 3620 and the base structure 3610. In some embodiments, at least a portion of the periphery of the damping structure layer 3630 may be fixed to the base structure 3610.

[0230] 37 is a cross-sectional view of a bone conduction acoustic transmission device according to some embodiments of the present application. As shown in FIG. 37 , the bone conduction acoustic transmission device 3700 may include a base structure 3710, a laminated structure 3720, and two damping structural layers, the two damping structural layers including a first damping structural layer 3730 and a second damping structural layer 3740. Furthermore, the second damping structural layer 3740 is connected to the upper surface of the base structure 3710, the lower surface of the laminated structure 3720 is connected to the upper surface of the second damping structural layer 3740, one end of the laminated structure 3720 is suspended in the hollow portion of the base structure 3710, and the first damping structural layer 3730 is located on the upper surface of the laminated structure 3720. The area of the first damping structural layer 3730 and / or the second damping structural layer 3740 is larger than the area of the laminated structure 3720.

[0231] 38 is a cross-sectional view of a bone conduction sound transmission device according to some embodiments of the present application. As shown in FIG. 38, bone conduction sound transmission device 3800 may include a base structure 3810, a laminated structure 3820, and a damping structure layer 3830. Furthermore, damping structure layer 3830 is located on the upper surface of base structure 3810. The lower surface of laminated structure 3820 is connected to the upper surface of damping structure layer 3830, and one end of laminated structure 3820 is suspended in the hollow portion of base structure 3810.

[0232] The position of the damping structure layer (e.g., damping structure layer 3630) is not limited to the upper and / or lower surfaces of the laminated structure shown in FIGS. 36 to 38, but may be located between the multiple layered structures of the laminated structure. For example, the damping structure layer may be located between the elastic layer and the first electrode layer. Also, for example, the damping structure layer may be located between the first elastic layer and the second elastic layer. Furthermore, the damping structure layer is not limited to the cantilever-type bone conduction acoustic transmission device described above, but may also be applied to the bone conduction acoustic transmission devices shown in FIGS. 5, 7, 8, 17, 21, 23, and 31, and a description thereof will be omitted in this specification.

[0233] Although the basic concepts have been described above, it will be apparent to those skilled in the art that the detailed disclosure above has been presented by way of example only and is not intended to limit the present application. Although not expressly described herein, those skilled in the art may make various changes, improvements, and modifications to the present application. These changes, improvements, and modifications are intended to be suggested by the present application and are therefore within the spirit and scope of the exemplary embodiments of the present application.

[0234] Furthermore, certain terms are used herein to describe embodiments of the present application. For example, "one embodiment," "one embodiment," and / or "some embodiments" refer to particular features, structures, or characteristics associated with at least one embodiment of the present application. Therefore, it is emphasized and understood that references to "one embodiment" or "one embodiment" or "one alternative embodiment" more than once in various parts of this specification do not necessarily all refer to the same embodiment. Furthermore, particular features, structures, or characteristics of one or more embodiments of the present application may be combined as appropriate.

[0235] Additionally, as will be appreciated by those skilled in the art, aspects of the present application may be illustrated and described in several patentable classes or contexts, including any new and useful process, machine, manufacture, or combination of matter, or any new and useful improvement thereto. Accordingly, aspects of the present application may be implemented entirely in hardware, entirely in software (including firmware, resident software, microcode, etc.), or a combination of hardware and software. Such hardware or software may be referred to as a "data block," "module," "engine," "unit," "assembly," or "system." Additionally, aspects of the present application may take the form of a computer program product embodied in one or more computer-readable medium(s) containing computer-readable program code.

[0236] Furthermore, unless expressly stated in the claims, the enumerated order, use of alphanumeric characters, or use of other designations of processing elements or sequences described herein does not limit the order of the procedures and methods herein. While the above disclosure has set forth through various examples what are presently believed to be various useful embodiments of the invention, it should be understood that such details are for illustrative purposes only, and that 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 herein. For example, the system assembly described above may be implemented by a hardware device, or may be implemented as a software-only solution, e.g., by installing the described system on an existing processing device or mobile device.

[0237] Similarly, in the foregoing description of embodiments of the present application, it should be understood that various features may be grouped together in a single embodiment, drawing, or description for the purpose of streamlining the disclosure and facilitating an understanding of one or more embodiments of the present invention. However, this method of disclosure should not be interpreted as reflecting an intention that the claimed subject matter requires more features than are recited in each claim. In fact, an embodiment may include fewer than all features of a single embodiment disclosed above.

[0238] In some examples, numbers describing the number of components and attributes are used; it should be understood that the numbers describing such examples are, in some instances, modified by the modifiers "about," "approximately," or "generally." Unless otherwise specified, "about," "approximately," or "generally" indicates that the number can vary by ±20%. Thus, in some examples, all numerical parameters used in the specification and claims are approximations that may vary depending on the specific requirements of a particular example. In some examples, numerical parameters should be calculated using the specified number of significant digits and ordinary rounding techniques. While in some examples, the numerical ranges and parameters used to determine ranges are approximations, in specific examples, such numerical values are set as precisely as possible.

[0239] All patents, patent applications, published patent applications, and other materials, such as papers, books, specifications, publications, and documents, referenced in this application are incorporated herein by reference in their entirety, except for prosecution history documents that are inconsistent with or inconsistent with the content of this application and documents that may have a limiting effect on the broadest scope of the claims of this application (now or later related to this application). Further, in the event that an explanation, definition, and / or term usage in the accompanying materials of this application is inconsistent with or inconsistent with the content set forth in this application, the explanation, definition, and / or term usage in this application shall control.

[0240] Finally, it should be understood that the embodiments described herein are merely illustrative of the principles of the present embodiments. Other variations may be within the scope of the present application. Thus, by way of example, and not of limitation, alternative configurations of the present embodiments may be considered consistent with the teachings of the present application. Thus, the present embodiments are not limited to the embodiments expressly introduced and described herein. [Explanation of symbols]

[0241] 100 Bone conduction acoustic transmission device 110 Base structure 120 Acoustic Conversion Unit 130 vibration unit 131 first elastic layer 132 second elastic layer 140 Connection Base 530 Suspension Membrane Structure

Claims

1. a laminated structure formed of a vibration unit and an acoustic conversion unit; a base structure configured to mount the laminated structure and physically connected to at least one side of the laminated structure; Including, the base structure vibrates based on an external vibration signal, the vibration unit deforms in response to the vibration of the base structure, and the acoustic transducer unit generates an electric signal based on the deformation of the vibration unit; the vibration unit includes at least one support arm and a mass element, the mass element being connected to the base structure by the at least one support arm; a width of each of the at least one support arms is smaller than a width of the mass element connected to the at least one support arm; the mass element includes, in order from bottom to top, a base layer, a third electrode layer, a second piezoelectric layer, and a fourth electrode layer; Bone conduction acoustic transmission device.

2. The bone conduction acoustic transmission device of claim 1, characterized in that the acoustic conversion unit includes a first electrode layer, a first piezoelectric layer, and a second electrode layer arranged in order from top to bottom, and the first electrode layer or the second electrode layer is connected to the upper surface or lower surface of the at least one support arm.

3. The bone conduction acoustic transmission device according to claim 2, characterized in that the acoustic conversion unit includes at least one elastic layer located on the upper and / or lower surface of the first electrode layer or the second electrode layer.

4. The bone conduction acoustic transmission device of claim 2, characterized in that a neutral layer is formed in the bone conduction acoustic transmission device, the neutral layer has zero deformation stress when the support arm is deformed, and the neutral layer is not located in the thickness direction of the first piezoelectric layer.

5. 5. The bone conduction acoustic transmission device according to claim 1, wherein the thickness of the mass element is 1 μm to 400 μm.

6. The bone conduction acoustic transmission device of claim 1, characterized in that the acoustic conversion unit includes a first electrode layer, a first piezoelectric layer, and a second electrode layer, and the ratio of the area of the overlapping region of the first electrode layer, the first piezoelectric layer, and the second electrode layer to the area of the cross section perpendicular to the thickness direction of the support arm is 5% to 40%.

7. 3. The bone conduction acoustic transmission device according to claim 2, wherein the first electrode layer or the second electrode layer has an electrode insulating channel formed therein, which divides the first electrode layer or the second electrode layer into two or more electrode regions.

8. 5. The bone conduction acoustic transmission device according to claim 1, wherein the cross section of the at least one support arm perpendicular to the thickness direction is polygonal.

9. A bone conduction acoustic transmission device described in any one of claims 1 to 4, characterized in that the cross-sectional shape perpendicular to the thickness direction of the mass element is polygonal, and the number of support arms corresponds to the number of sides of the polygon.

10. The bone conduction acoustic transmission device described in claim 8, characterized in that when the cross-sectional shape of the support arm perpendicular to the thickness direction is rectangular, the length of the support arm is 100 μm to 500 μm and the width of the support arm is 150 μm to 400 μm.

11. The bone conduction acoustic transmission device of claim 8, characterized in that when the cross-sectional shape of the support arm perpendicular to the thickness direction is trapezoidal, the height of the trapezoid is 150 μm to 600 μm, the length of the long side of the trapezoid is 300 μm to 600 μm, and the length of the short side of the trapezoid is 100 μm to 400 μm.

12. The bone conduction acoustic transmission device described in any one of claims 1 to 4, characterized in that the support arm includes a first band-shaped portion and a second band-shaped portion, one end of the first band-shaped portion is connected to the mass element and the other end is connected to one end of the second band-shaped portion, and the other end of the second band-shaped portion is connected to the base structure.

13. The bone conduction acoustic transmission device described in any one of claims 1 to 4, characterized in that the support arm includes a first band-shaped portion, a second band-shaped portion, and a third band-shaped portion, one end of the first band-shaped portion is connected to the mass element and the other end is connected to one end of the second band-shaped portion, the other end of the second band-shaped portion is connected to one end of the third band-shaped portion, and the other end of the third band-shaped portion is connected to the base structure.

Images