Bone Conduction Microphone

Abstract

The bone conduction microphone 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 in response to 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, and the resonant frequency of the bone conduction microphone is 2.5 kHz to 4.5 kHz.

Description

[Technical field]

[0001] (Incorporated by reference) This application claims priority to International Application PCT / CN2020 / 142533, filed December 31, 2020, the entire contents of which are incorporated herein by reference.

[0002] The present application relates to the technical field of hearing devices, and in particular to bone conduction microphones. [Background technology]

[0003] The microphone receives an external vibration signal, converts the vibration signal into an electrical signal using an acoustic conversion unit, and outputs the electrical signal after processing by a back-end circuit. The air conduction microphone receives an air conduction sound signal, which is a sound signal propagated by air, i.e., the air conduction microphone receives an air vibration signal. The bone conduction microphone receives a bone conduction sound signal, which is a sound signal propagated by human bone, i.e., the bone conduction microphone receives a bone vibration signal. Compared with the air conduction microphone, the bone conduction microphone has an advantage in noise resistance, and in a noisy environment, the bone conduction microphone is less interfered with by environmental noise, and can better collect human voices.

[0004] Traditional bone conduction microphones have a complicated structure and high manufacturing process requirements. Some devices have poor connection strength, which results in low reliability and affects the output signal. Therefore, it is necessary to provide a bone conduction microphone with a simple structure and high stability. Summary of the Invention [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 in response to 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 bone conduction microphone has a resonant frequency between 2.5 kHz and 4.5 kHz.

[0007] In some embodiments, the resonant frequency of the bone conduction microphone is between 2.5 kHz and 3.5 kHz.

[0008] 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 a hollow portion of the frame structure.

[0009] In some embodiments, the vibration unit includes at least one elastic layer, and the acoustic conversion 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 an upper surface of the first electrode layer or a lower surface of the second electrode layer.

[0010] In some embodiments, the acoustic transducer unit further includes a seed layer, the seed layer being located on a lower surface of the second electrode layer.

[0011] 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.

[0012] In some embodiments, the vibration unit includes at least one elastic layer, 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.

[0013] 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 or lower surface of the piezoelectric layer.

[0014] In some embodiments, the first comb-like structure and the second comb-like structure extend along a longitudinal direction of the laminated structure. In some embodiments, a resonance frequency of the bone conduction microphone and a stiffness of the vibration unit are positively correlated.

[0015] In some embodiments, the resonant frequency of the bone conduction microphone and the mass of the laminate structure are negatively correlated.

[0016] In some embodiments, the vibration unit includes a suspension membrane structure, 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.

[0017] In some embodiments, the suspension membrane structure includes a plurality of holes, the plurality of holes being distributed along an outer circumferential direction and / or an inner circumferential direction of the acoustic transducer unit.

[0018] In some embodiments, the plurality of holes are circular holes, and the radius of the circular holes is between 20 μm and 300 μm.

[0019] In some embodiments, the shape of the enclosed area of ​​the plurality of holes corresponds to the shape of the acoustic transducer unit.

[0020] In some embodiments, the shape of the holes corresponds to the shape of the acoustic transducer unit.

[0021] In some embodiments, the holes are distributed in a circular pattern along the outer and / or inner circumference of the acoustic transducer unit.

[0022] In some embodiments, the circle has a radius of 300 μm to 700 μm.

[0023] In some embodiments, the radial spacing from the edge of the effective acoustic transducer unit to the centre of the plurality of holes is between 50 μm and 400 μm.

[0024] In some embodiments, the effective acoustic transducer unit is a circular ring structure, and the inner diameter dimension of said acoustic transducer unit is between 100 μm and 700 μm.

[0025] In some embodiments, the effective acoustic transducer unit is a circular annular structure, and the outer diameter dimension of the effective acoustic transducer unit is between 110 μm and 710 μm.

[0026] In some embodiments, the radial spacing from the edge of the acoustic transducer unit to the center of the plurality of holes is between 100 μm and 400 μm.

[0027] In some embodiments, the acoustic transducer unit is an annular structure, and a thickness of the suspension membrane structure in an inner region of the annular structure is greater than a thickness of the suspension membrane structure in an outer region of the annular structure.

[0028] 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.

[0029] In some embodiments, the suspension membrane structure has a thickness of between 0.5 μm and 10 μm.

[0030] In some embodiments, the suspension membrane structure is circular, elliptical, polygonal or irregularly shaped.

[0031] In some embodiments, the suspension membrane structure is circular and the radius of said suspension membrane structure is between 500 μm and 1500 μm.

[0032] In some embodiments, the first electrode layer has a thickness between 80 nm and 250 nm.

[0033] In some embodiments, the piezoelectric layer has a thickness of between 0.8 μm and 5 μm.

[0034] In some embodiments, the second electrode layer has a thickness of 80 nm to 250 nm.

[0035] In some embodiments, the vibration unit further comprises a mass element, the mass element being located on a top or bottom surface of the suspension membrane structure.

[0036] In some embodiments, the acoustic transducer unit and the mass element are located on different sides of the suspension membrane structure.

[0037] 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 a circumferential direction of the mass element.

[0038] In some embodiments, the mass element is a cylinder, and the radius of a cross section perpendicular to a thickness direction of the mass element is between 100 μm and 700 μm.

[0039] In some embodiments, the mass element is a cylinder and the thickness of the mass element is between 20 μm and 400 μm.

[0040] In some embodiments, a lead structure is provided on the suspension membrane structure, and the first electrode layer and the second electrode layer are connected to the base structure by the lead structure, In some embodiments, the width of the lead structure is between 2 μm and 100 μm.

[0041] In some embodiments, the lead structure includes a first lead and a second lead, the first lead having one end connected to a first electrode layer and the other end connected to the base structure, and the second lead having one end connected to a second electrode layer and the other end connected to the base structure.

[0042] In some embodiments, the vibration unit further comprises a mass element, the mass element being located on the upper or lower surface of the suspension membrane structure, the suspension membrane structure comprising a plurality of holes, the plurality of holes being distributed along a circumferential direction of the acoustic transducer unit.

[0043] In some embodiments, the ratio of the intensity of the electrical signal of the bone conduction microphone to the intensity of the noise is 50% to 100% of the maximum value of the ratio of the intensity of the electrical signal to the intensity of the noise.

[0044] In some embodiments, the vibrating 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.

[0045] 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 within the at least one support arm.

[0046] 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.

[0047] In some embodiments, the mass element is located on a top or bottom surface of the first electrode layer or the second electrode layer.

[0048] 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 at least one support arm.

[0049] In some embodiments, an area of ​​the first electrode layer is less than or equal to an area of ​​the piezoelectric layer, and the entire area of ​​the first electrode layer is located on a surface of the piezoelectric layer.

[0050] In some embodiments, the first electrode layer, the piezoelectric layer and the second electrode layer of the acoustic transducer unit are adjacent to a connection point between the mass element and / or the support arm and the base structure.

[0051] In some embodiments, the at least one support arm includes at least one elastic layer, the at least one elastic layer being located on a top or bottom surface of the first electrode layer or the second electrode layer.

[0052] In some embodiments, the device further comprises a position limiting structure located in a hollow portion of the base structure, the position limiting structure being connected to the base structure and located above and / or below the mass element.

[0053] In some embodiments, the bone conduction acoustic transmission device according to any one of the preceding claims further comprises at least one damping layer covering the upper surface, the lower surface and / or the interior of the laminate structure.

[0054] The present application will now be further described by way of exemplary embodiments, which are described in detail with reference to the drawings, in which the exemplary embodiments are not limiting and in which like reference numerals indicate like structures. [Brief description of the drawings]

[0055] [Figure 1] 1 is a schematic diagram of a bone conduction acoustic transmission device according to some embodiments of the present application. [Diagram 2] 2 is a cross-sectional view of the bone conduction acoustic transmission device shown in FIG. 1 taken along line AA. [Diagram 3] FIG. 2 is a schematic diagram of another bone conduction acoustic transmission device shown in some embodiments of the present application. [Figure 4] FIG. 13 is a schematic diagram illustrating the configuration of a bone conduction acoustic transmission device according to another embodiment of the present application. [Diagram 5] 1 is a schematic diagram 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 of a bone conduction acoustic transmission device according to some embodiments of the present application. [Figure 8] 1 is a schematic diagram of a bone conduction acoustic transmission device according to some embodiments of the present application. [Figure 9] 9 is a cross-sectional view of the bone conduction acoustic transmission device shown in FIG. 8 taken along line CC. [Figure 10] 1 is a schematic diagram of a bone conduction acoustic transmission device according to some embodiments of the present application. [Figure 11] 1 is a schematic diagram of a bone conduction acoustic transmission device according to some embodiments of the present application. [Figure 12] 1 is a schematic diagram of a bone conduction acoustic transmission device according to some embodiments of the present application. [Figure 13] 1 is a schematic diagram of a bone conduction acoustic transmission device according to some embodiments of the present application. [Figure 14] 1 is a schematic diagram of a bone conduction acoustic transmission device according to some embodiments of the present application. [Figure 15]1 is a schematic diagram illustrating a bone conduction acoustic transmission device according to some embodiments of the present application. [Figure 16] 1 is a schematic diagram illustrating a bone conduction acoustic transmission device according to some embodiments of the present application. [Figure 17] 13 is a frequency response curve of a laminate structure with natural frequency forward shifted in accordance with some embodiments of the present application; [Figure 18] 1 is a frequency response curve diagram of a bone conduction acoustic transmission device having a damping structure layer and a bone conduction acoustic transmission device without a damping structure layer according to some embodiments of the present application. [Figure 19] 1 is a cross-sectional view of a bone conduction acoustic transmission device according to some embodiments of the present application. [Figure 20] 1 is a cross-sectional view of a bone conduction acoustic transmission device according to some embodiments of the present application. [Figure 21] 1 is a cross-sectional view of a bone conduction acoustic transmission device according to some embodiments of the present application. [Figure 22] 1 is a schematic diagram of a suspension membrane structure and holes of a bone conduction acoustic transmission device according to some embodiments of the present application. [Figure 23] 1 is a schematic diagram of a suspension membrane structure and holes of another bone conduction acoustic transmission device according to some embodiments of the present application. [Figure 24] 1 is a schematic diagram of a suspension membrane structure and holes of another bone conduction acoustic transmission device according to some embodiments of the present application. [Diagram 25] 1 is a schematic diagram of a suspension membrane structure and holes of another bone conduction acoustic transmission device according to some embodiments of the present application. [Figure 26] 1 is a schematic diagram of a suspension membrane structure and holes of another bone conduction acoustic transmission device according to some embodiments of the present application. [Figure 27] 1 is a schematic diagram of an acoustic transducer unit of a bone conduction acoustic transmission device according to some embodiments of the present application. [Figure 28] 1 is a schematic diagram of a lead structure of a bone conduction acoustic transmission device according to some embodiments of the present application. [Figure 29] 1 is a schematic diagram of a lead structure of another bone conduction acoustic transmission device according to some embodiments of the present application. [Diagram 30] 8 is a cross-sectional view of a partial structure of the bone conduction acoustic transmission device shown in FIG. 7. [Figure 31A] 1 is a schematic diagram of different mass elements of a bone conduction acoustic transmission device according to some embodiments of the present application. [Figure 31B] 1 is a schematic diagram of different mass elements of a bone conduction acoustic transmission device according to some embodiments of the present application. [Figure 31C] 1 is a schematic diagram of different mass elements of a bone conduction acoustic transmission device according to some embodiments of the present application. [Figure 32A] 1A-1C are schematic diagrams of different acoustic transducer units of a bone conduction acoustic transmission device according to some embodiments of the present application. [Figure 32B] 1A-1C are schematic diagrams of different acoustic transducer units of a bone conduction acoustic transmission device according to some embodiments of the present application. [Figure 32C] 1A-1C are schematic diagrams of different acoustic transducer units of a bone conduction acoustic transmission device according to some embodiments of the present application. [Fig. 32D] 1A-1C are schematic diagrams of different acoustic transducer units of a bone conduction acoustic transmission device according to some embodiments of the present application. [Figure 33A] 1A-1C are schematic diagrams of different lead structures of a bone conduction acoustic transmission device according to some embodiments of the present application. [Figure 33B] 1A-1C are schematic diagrams of different lead structures of a bone conduction acoustic transmission device according to some embodiments of the present application. [Diagram 34] 1 is a schematic diagram of a lead structure of another bone conduction acoustic transmission device according to some embodiments of the present application. [Diagram 35] 1 is a schematic diagram of a bone conduction acoustic transmission device according to some embodiments of the present application. [Diagram 36] 36 is a cross-sectional view of a partial structure of the bone conduction acoustic transmission device shown in FIG. 35. [Figure 37] 4 is a resonant frequency curve of a bone conduction acoustic transmission device according to some embodiments of the present application. [Figure 38] 13 is a resonant frequency curve of another bone conduction acoustic transmission device according to some embodiments of the present application. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0056] In order to more clearly describe 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 some examples or 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 creative efforts. Unless otherwise clear from the language environment or specified, the same symbols in the drawings indicate the same structures or operations. It should be understood that the drawings are only for illustration and description, and are not intended to limit the scope of the present application. It should be understood that the drawings are not drawn to scale.

[0057] It should be understood that for ease of explanation of the present application, the positional relationships indicated by terms such as "center," "upper," "lower," "top," "bottom," "inner," "outer," "axial," "radial," "periphery," "external," and the like are based on the positional relationships shown in the drawings, and are not intended to indicate that the devices, assemblies, or units referred to must have a particular positional relationship, and should not be understood as limiting the present application.

[0058] It should be understood that the terms "system," "apparatus," "unit," and / or "module" used herein are ways to distinguish between different levels of assemblies, parts, components, portions, or structures, however, other terms may be used in place of the above terms if they accomplish the same purpose.

[0059] As used herein and in the claims, unless otherwise clearly indicated through context, 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" are merely intended to indicate the inclusion of explicitly identified steps and elements, and these steps and elements are not intended to be an exclusive listing, and a method or apparatus may include other steps or elements.

[0060] In this application, flowcharts are used to describe the operations performed by the system according to the embodiments of this application. It should be understood that the preceding or subsequent operations are not necessarily performed in exact order. Instead, the steps may be processed in reverse order or simultaneously. Also, other operations may be added to these processes, or one or more operations may be removed from these processes.

[0061] When describing the bone conduction related technology in the present invention, the terms "bone conduction microphone", "bone conduction sound transmission device", "microphone device" or "bone conduction microphone" are used for description, and the description is merely one type of application form of bone conduction, and the bone conduction devices referred to in the above different descriptions are equivalent. For convenience of description, the use and application process of the sound generating unit will be described below by taking the bone conduction sound transmission device as an example. It should be noted that the above description is provided for the purpose of description only, and does not limit the scope of the present application.

[0062] 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, for example, 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 part of the structure of the laminated structure is physically connected to the base structure. Here, "connection" may be understood as a fixed connection between the laminated structure and the base structure after the laminated structure and the base structure are manufactured, respectively, by welding, riveting, fastening, bolts, or the like, or a physical deposition (e.g., physical vapor deposition) or chemical deposition (e.g., chemical vapor deposition) of the laminated structure on the base structure during manufacturing. In some embodiments, at least a part of the structure of the laminated structure may be fixed to the upper or lower surface of the base structure, or may be fixed to a side wall 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 a side wall of the base structure where the hollow portion is located, and the other end not connected to or in contact with the base structure, so that the other end is suspended in the hollow portion of the base structure. For example, the laminated structure may include a vibration membrane layer (also called a suspension membrane structure), which is fixedly connected to the base structure, and the laminated structure is installed 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, and the mass element is fixedly connected to the base structure by one or more support arms, one end of the support arm is connected to the base structure, and the other end of the support arm is connected to the mass element, so that the mass element and a part of the support arm are suspended in the hollow portion of the base structure.It should be understood that "located in the hollow portion of the base structure" or "suspended in the hollow portion of the base structure" referred to in this application may mean suspended in, 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 may be vibrated by 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. Here, it should be understood that the description of the vibration unit and the acoustic transducer unit is merely for the purpose of easily explaining the operation principle of the laminated structure, and does not limit the actual configuration and structure of the laminated structure. In fact, the vibration unit is not essential, and its function can be realized by the acoustic transducer unit at all. 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.

[0063] The vibration unit is a part of the laminated structure that is easily deformed by an external force or an inertial action, and the vibration unit can transmit the deformation due to the external force or the inertial action to the acoustic conversion unit. In some embodiments, the vibration unit and the acoustic conversion unit are laminated to form a laminated structure. The acoustic conversion 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 is a cantilever structure, the vibration unit may include at least one elastic layer, and the acoustic conversion unit may include a first electrode layer, a piezoelectric layer, and a second electrode layer installed in order from top to bottom, the elastic layer is located on the surface of the first electrode layer or the second electrode layer, the elastic layer deforms during vibration, the piezoelectric layer generates an electrical signal based on the deformation of the elastic layer, and the first electrode layer and the second electrode layer 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 deformed more easily by the action of an external force by changing the density of a specific area of ​​the suspension membrane structure, or by drilling holes in the suspension membrane structure, or by installing a counterweight (also called a mass element), etc., thereby driving the acoustic transducer unit to generate an electric signal. For example, the vibration unit may include at least one support arm and a mass element, and the mass element is suspended in the hollow part 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 is deformed to act on the acoustic transducer unit to generate an electric signal.

[0064] The acoustic transducer unit is a part of the laminated structure that converts the deformation of the vibration unit into an electric 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 on both ends thereof by the action of 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 by the action of 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., an AIN film material) manufactured by a deposition process (e.g., a magnetron sputtering deposition process). 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), and the like, or any combination thereof. Piezoelectric ceramic materials are piezoelectric polycrystals formed by random assembly of 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), and the like.

[0065] In some embodiments, the base structure and the laminated structure may be located in a housing of the bone conduction sound transmission device, the base structure is fixedly connected to the inner wall of the housing, and the laminated structure is placed on the base structure. When the housing of the bone conduction sound transmission device vibrates due to an external force (for example, the housing is vibrated due to the vibration of the face when a person speaks), the vibration of the housing vibrates the base structure. Furthermore, when the vibration unit is deformed, the piezoelectric layer of the acoustic conversion unit generates a potential difference (voltage) due to the deformation stress of the vibration unit, and at least two electrode layers (for example, a first electrode layer and a second electrode layer) located on the upper and lower surfaces of the piezoelectric layer in the acoustic conversion unit, respectively, may collect the potential difference and convert the external vibration signal into an electrical signal. For illustrative purposes only, the bone conduction sound 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., and the bone conduction sound transmission device may be placed on the head (e.g., face), neck, near the ears, and on the top of the head, etc., of the human body, and the bone conduction sound transmission device can collect sound by picking up the vibration signal of bones when a person speaks and converting it into an electrical signal. Note that the base structure is not limited to a structure independent of the housing of the bone conduction sound transmission device, and in some embodiments, the base structure may be a part of the housing of the bone conduction sound transmission device.

[0066] A bone conduction acoustic transmission device (also called a bone conduction microphone) receives an external vibration signal, converts the vibration signal into an electric signal by a laminated structure (including an acoustic conversion unit and a vibration unit), and outputs the electric signal after processing by a back-end circuit. When an external vibration signal acts on the bone conduction acoustic transmission device, and the external force acting frequency is the same as or very close to the system's natural oscillation frequency, the phenomenon of the amplitude increasing drastically is called resonance, and the frequency at which the resonance occurs is called the "resonance frequency". The bone conduction acoustic transmission device has a natural frequency, and when the frequency of the external vibration signal is close to the natural frequency, the laminated structure generates a large amplitude and outputs a large electric signal. Therefore, the response of the bone conduction acoustic transmission device to the external vibration is expressed as a resonance peak occurring near the natural frequency. Therefore, the resonance frequency of the bone conduction acoustic transmission device is basically equal to the natural frequency numerically. 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 4 kHz to 4.5 kHz. In some embodiments, since the bone conduction signal of the human body quickly decays from 1 kHz, it is desirable to adjust the resonance frequency of the bone conduction acoustic transmission device (or the natural frequency of the laminated structure) to a voice frequency band range of 1 kHz to 5 kHz. In some embodiments, the resonance frequency of the bone conduction acoustic transmission device may be adjusted to a voice frequency band range of 2 kHz to 5 kHz. In some embodiments, the resonance frequency of the bone conduction acoustic transmission device is 2.5 kHz to 4.5 kHz. In some embodiments, the resonance frequency of the bone conduction acoustic transmission device may be adjusted to a voice frequency band range of 3 kHz to 4.5 kHz. In some embodiments, the resonance frequency of the bone conduction acoustic transmission device may be adjusted to a voice frequency band range of 2.5 kHz to 3.5 kHz. By adjusting the resonance frequency range, the resonance peak of the bone conduction acoustic transmission device is set to a voice frequency band range of 2.5 kHz to 4.5 kHz, thereby improving the sensitivity of the bone conduction acoustic transmission device to respond to vibrations in the voice frequency band (for example, the frequency band range before the resonance peak, i.e., 20 Hz to 5 kHz).

[0067] Since the bone conduction sound transmission device can be equivalent to a mass-spring-damping system model, when the bone conduction sound transmission device operates, it can be equivalent to a mass-spring-damping system performing forced vibration under the action of an excitation force, and its vibration law conforms to the law of the mass-spring-damping system. Therefore, the resonance frequency of the bone conduction sound transmission device is related to the equivalent stiffness and equivalent mass of its internal assembly (e.g., a vibration unit or a laminated structure), that is, the resonance frequency of the bone conduction sound 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 sound transmission device equivalent to the mass-spring-damping system model, and the equivalent mass is the mass of the bone conduction sound transmission device equivalent to the mass-spring-damping system model. Therefore, in order to adjust the resonance frequency (or natural frequency) of the bone conduction sound transmission device, it is necessary to adjust the equivalent stiffness and equivalent mass of the vibration unit or the laminated structure.

[0068] During operation, the bone conduction acoustic transmission device can be equivalent to a mass-spring-damping system model performing forced vibration under the action of an external vibration force, and the vibration law conforms to the law of the mass-spring-damping system model, and the influence parameters of the resonance frequency f0 under the action of an external vibration 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) ζ. 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) ζ is negatively correlated with the system resonance frequency f0 of the bone conduction acoustic transmission device. In some embodiments,

[0069]

number

[0070] is positively correlated with the resonant frequency f0 of the bone conduction acoustic transmission device system. In some embodiments, the frequency response satisfies the following equation (1):

[0071]

number

[0072] 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 ζ is the equivalent relative damping coefficient (damping ratio) of the system.

[0073] Most bone conduction acoustic transmission devices, especially piezoelectric bone conduction acoustic transmission devices, generally have a small system equivalent relative damping coefficient ζ, and the resonance frequency f0 of the system is mainly affected by the equivalent stiffness and equivalent mass. Take the bone conduction acoustic transmission device shown in FIG. 5 as an example, its suspension membrane structure 530 provides spring, damping and mass action to the vibration system. Therefore, the suspension membrane structure 530 mainly affects the system equivalent stiffness k and also affects the system equivalent mass m. Take the bone conduction acoustic transmission device shown in FIG. 7 as an example, its suspension membrane structure 730 provides spring and damping action to the vibration system and provides mass action to the mass element 740. Therefore, the suspension membrane structure 730 mainly affects the system equivalent stiffness k and also affects the system equivalent mass m. The mass element 740 mainly affects the system equivalent mass m and also affects the system equivalent stiffness k. For a bone conduction acoustic transmission device with a complex structure, it is difficult to theoretically obtain its resonance frequency f0, and a finite element simulation tool can be used to establish a model of the corresponding structure and parameters to obtain 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 electrode layer and the second electrode layer), the piezoelectric layer, the elastic layer, the mass element, etc. described below, and the resonant frequency f0 of the bone conduction sound transmission device can be adjusted. In some embodiments, the resonant frequency f0 of the bone conduction sound transmission device can be adjusted by designing the structure of the bone conduction sound transmission device, for example, a structure in which a mass element is added to a support arm, a structure of a cantilever beam, a structure in which a hole is made in a suspension membrane, or a structure in which a mass element is added to a suspension membrane. In some embodiments, the resonant frequency f0 of the bone conduction sound transmission device can be adjusted by designing the dimensions of different members, for example, the length, width, thickness, etc. of the support arm, the mass element, the cantilever beam, the suspension membrane, etc.

[0074] 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, a hole can be provided in the vibration unit to adjust the equivalent stiffness of the vibration unit. For example, a mass element can be provided in the vibration unit to adjust the equivalent mass of the laminated unit. For example, a support arm can be provided in the vibration unit to adjust the equivalent stiffness of the laminated unit. For more details on adjusting the structural parameters of the vibration unit and the acoustic transducer unit, please refer to the following description, and the description will be omitted in this specification.

[0075] Signal-to-noise ratio (abbreviated as SNR) is the ratio of signal to noise in an electronic device or system. In a bone conduction acoustic transmission device, the higher the signal-to-noise ratio, the higher the electric signal strength of the bone conduction acoustic transmission device, the lower the noise, and the higher the effect of the bone conduction acoustic transmission device. Therefore, the signal-to-noise ratio is a very important parameter in the design process of a bone conduction acoustic transmission device, and in some embodiments, the signal-to-noise ratio SNR is a ratio of the sensitivity v of the bone conduction acoustic transmission device. s and the noise floor of the bone conduction acoustic transmission device v ntrms In some embodiments, the signal-to-noise ratio SNR is related to the sensitivity v s and the noise floor of the bone conduction acoustic transmission device v ntrms In some embodiments, the signal to noise ratio SNR is negatively correlated with

[0076]

number

[0077] In some embodiments, the signal-to-noise ratio (SNR) of the bone conduction acoustic transmission device can be calculated according to the following formula (2):

[0078]

number

[0079] In the formula, v s is the sensitivity of the bone conduction acoustic transmission device. s is related to the piezoelectric constant, the internal stress of the piezoelectric layer (e.g., the first piezoelectric layer), 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 transmission device and the external load. In some embodiments, after establishing the model, the sensitivity values ​​v of different bone conduction acoustic transmission device structures under corresponding external loads are calculated by the numerical method of finite element method. s It is possible to obtain ntrms is the noise floor of the bone conduction acoustic transmission device, and the noise floor of the bone conduction acoustic transmission device v ntrms is the noise floor value of the amplifier circuit (ASIC), v narms and the noise floor value v of the transducer (acoustic conversion unit) nsrms The noise floor of the bone conduction acoustic transmission device can be determined by parameters such as: ntrms is the noise floor value of the amplifier circuit (ASIC), v 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 dielectric loss tan δ of the piezoelectric layer (e.g., the first piezoelectric layer), and is the dielectric constant ε of the piezoelectric layer (e.g., the first piezoelectric layer). r , which can be related to parameters such as the thickness d of the piezoelectric layer (e.g., the first piezoelectric layer), the area S of the effective acoustic conversion unit of the bone conduction acoustic transmission device, the low-frequency cut-off frequency f0 of the noise floor of the bone conduction acoustic transmission device, and the high-frequency cut-off frequency f1 of the noise floor of the bone conduction acoustic transmission device.

[0080] In some embodiments, the noise floor of the bone conduction acoustic transmission device, v ntrms is the dielectric constant ε of a piezoelectric layer (e.g., the first piezoelectric layer) r, has a positive correlation with parameters such as the thickness d of the piezoelectric layer (e.g., the first piezoelectric layer) and the high frequency cutoff frequency f1 of the noise floor of the bone conduction acoustic transmission device. ntrms is negatively correlated with the area S of the effective acoustic transducer 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 dielectric loss tan δ of the piezoelectric layer (e.g., the first piezoelectric layer). In some embodiments, the noise floor v ntrms can be calculated using the following formula (3).

[0081] v ntrms =f(v nsrms ,v narms )=f(tan δ,ε r ,d,S,f1,f0,v narms ,ASIC gain) (3)

[0082] where ASIC gain is the gain of the amplifier circuit, which can be calculated during the amplifier circuit design process or obtained from the manufacturer; tan δ is the dielectric loss of the piezoelectric layer (e.g., the first piezoelectric layer); and ε r is the dielectric constant of the piezoelectric layer (e.g., the first piezoelectric layer), d is the thickness of the piezoelectric layer (e.g., the first piezoelectric layer), S is the area of ​​the effective acoustic conversion 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.

[0083] By substituting equation (3) into equation (2), we can obtain equation (4) which determines the signal-to-noise ratio SNR of the bone conduction acoustic transmission device.

[0084]

number

[0085] The meaning of each parameter in formula (4) is explained above. In formula (4), the dielectric loss tan δ of the piezoelectric material and the dielectric constant ε of the piezoelectric material are ris related to the material of the piezoelectric layer (e.g., the first piezoelectric layer). As can be seen from the above formula (4), 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), the material of the piezoelectric layer (e.g., the first piezoelectric layer), and sensitivity (sensitivity is affected by the material and structure of the bone conduction acoustic transmission device).

[0086] Based on the equation for solving the signal-to-noise ratio (SNR) of the bone conduction sound transmission device provided in this patent application, the materials of the electrode layer (first electrode layer and second electrode layer), the piezoelectric layer (first piezoelectric layer and second piezoelectric layer), the elastic layer, the mass element, etc. are designed, and the structure of the bone conduction sound transmission device is designed so that the design proposal meets the range requirement of the resonance frequency f0 and maximizes the signal-to-noise ratio (SNR) of the bone conduction sound transmission device. For example, a suspension membrane structure with holes, a structure with a mass element added to the suspension membrane structure, a cantilever structure, or a structure with a mass element added to the support arm is designed, and the dimensions of different members of the bone conduction sound transmission device, such as the dimensions of the suspension membrane structure, the number and dimensions of the holes in the suspension membrane structure, the dimensions and thickness of the mass element, and the area of ​​the effective sound conversion unit, are designed. As just one example, in a suspension membrane structure with holes, the stiffness and mass of the suspension membrane structure can be adjusted by designing the sound conversion unit, the materials and dimensions of each part of the suspension membrane structure, and the number and dimensions of the holes, etc., to concentrate stress on the sound conversion unit. The stress concentration in the acoustic transducer unit can increase the output electric 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. As a mere example, in a structure in which a mass element is added to a suspension membrane structure, the rigidity of the suspension membrane structure and the mass of the mass element can be adjusted by designing the materials, dimensions, etc. of the acoustic transducer unit, the suspension membrane structure, and each part of the mass element, so that the stress can be concentrated in the acoustic transducer unit. The stress concentration in the acoustic transducer unit can increase the output electric 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, in order to ensure that the designed bone conduction acoustic transmission device has high reliability, the signal-to-noise ratio SNR is adjusted to be smaller than the maximum value of SNR by adjusting the materials, structures, and dimensions of different members, for example, the SNR is designed to be 80% to 100% of the maximum value of SNR, the SNR is designed to be 50% to 100% of the maximum value of SNR, and the SNR is designed to be 20% to 100% of the maximum value of SNR.

[0087] Fig. 1 is a schematic diagram of a bone conduction acoustic transmission device according to some embodiments of the present application, Fig. 2 is a cross-sectional view of the bone conduction acoustic transmission device shown in Fig. 1 taken along line AA.

[0088] As shown in FIG. 1 and FIG. 2, the bone conduction acoustic transmission device 100 may include a base structure 110 and a laminate structure, and at least a part of the laminate structure is connected to the base structure 110. The base structure 110 may be a frame structure having a hollow interior, and a part of the structure of the laminate structure (for example, an end of the laminate structure away from the connection point between the base structure 110 and the laminate structure) may be located in the hollow part of the frame structure. Note that the frame structure is not limited to the rectangular parallelepiped shape shown in FIG. 1, and 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, 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 part of the frame structure by not connecting or contacting the frame structure. In some embodiments, the fixed end of the laminated structure may be connected to the upper surface, the lower surface, or the 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 of the base structure 110 is located may further be provided with a mounting groove that fits the fixed end of the laminated structure, so that the fixed end of the laminated structure is matingly connected to the base structure 110. To improve the 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 surface or the 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 in the side wall of the base structure 110 where the hollow portion is located, and the fixed end of the laminated structure and the base structure 110 are fitted and connected by the mounting groove.Here, "connection" may be understood as fixedly connecting the laminate structure and the base structure 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 connection base 140 may be a structure independent of the laminate structure, or may be integrally formed with the laminate structure.

[0089] In some embodiments, the laminated structure may include an acoustic transducer unit 120 and a vibration unit 130. The vibration unit 130 is a part of the laminated structure that is elastically deformable, and the acoustic transducer unit 120 is a part of the laminated structure that converts the deformation of the vibration unit 120 into an electrical signal. In some embodiments, the vibration unit 130 may be located on the upper or lower surface of the acoustic transducer unit 120. In some embodiments, the vibration unit 130 may include at least one elastic layer. For illustrative purposes only, the vibration unit 130 shown in FIG. 1 may include a first elastic layer 131 and a second elastic layer 132 that are installed in 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, which are arranged in order from top to bottom, and the 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) under the action of 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 derive 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., an AlN film material) manufactured by a deposition process (e.g., a magnetron sputtering deposition process). In 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 crystal material may include quartz, zinc blende, boron, tourmaline, zincite, GaAs, barium titanate and its derivative crystals, KH2PO4, NaKC4H4O6·4H2O (Rochelle salt), and the like, or any combination thereof. Piezoelectric ceramic material is a piezoelectric polycrystal with randomly assembled 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), and the like, or any combination thereof. In some embodiments, the material of the piezoelectric layer may be a piezoelectric polymer material, such as polyvinylidene fluoride (PVDF), and the like. In some embodiments, the first electrode layer 121 and the second electrode layer 123 are conductive material structures. Exemplary conductive materials may include metals, metal alloy materials, metal oxide materials, graphene, and the like, or any combination thereof. In some embodiments, metal and metal alloy materials may include nickel, iron, lead, platinum, titanium, copper, molybdenum, zinc, and any combination thereof. In some embodiments, metal alloy materials may include copper-zinc alloys, copper-tin alloys, copper-nickel-silicon alloys, copper-chromium alloys, copper-silver alloys, and the like, or any combination thereof. In some embodiments, metal oxide materials may include RuO2, MnO2, PbO2, NiO, and the like, or any combination thereof.

[0090] 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, i.e., 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, in some embodiments, the acoustic transducer unit 120 is installed only at a position 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. Thus, 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, in order 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 1 / 2 of the area of ​​the vibration unit 130. Preferably, the area of ​​the vibration unit 130 covered by the acoustic transducer unit 120 is 1 / 3 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 1 / 4 or less of the area of ​​the vibration unit 130. Furthermore, in some embodiments, the position of the acoustic transducer unit 120 may be close to the connection point between the laminated structure and the base structure 110. When the vibration unit 130 (e.g., elastic layer) receives 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 receives a large deformation stress near the connection point between the laminated structure and the base structure 110. By disposing 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 with respect 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 microphone 100 can be improved by simply 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 covered by the piezoelectric layer 122 of the first electrode layer 121 or the second electrode layer 123 is equal to or smaller than ½ of the area of ​​the first electrode layer 121 or the second electrode layer 123. Preferably, the area covered by the piezoelectric layer 122 of the first electrode layer 121 or the second electrode layer 123 is equal to or smaller than ⅓ of 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 less than ¼ of 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 may be smaller than the area of ​​the piezoelectric layer 122 or the second electrode layer 123 to prevent the problem that the first electrode layer 121 and the second electrode layer 123 are connected to each other and a short circuit occurs. For example, the areas of the piezoelectric layer 122, the second electrode layer 123 and the vibration unit 130 are the same, and the area of ​​the first electrode layer 121 is smaller than the areas of the vibration unit 130 (e.g., elastic layer), the piezoelectric layer 122 or the second electrode layer 123. In this 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 the areas of low material quality at the edges of the piezoelectric layer 122.

[0091] In some embodiments, the piezoelectric layer 122 may be located on one side of a neutral layer of the laminate structure to increase the output electrical signal and improve the signal-to-noise ratio of the bone conduction acoustic transmission device. The neutral layer is a planar layer in the laminate structure that has a deformation stress of approximately zero when deformed. In some embodiments, the signal-to-noise ratio of the bone conduction acoustic transmission device 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 dimensions (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).

[0092] In some embodiments, to solve the warpage problem of the laminate structure, the stresses of each layer in the laminate structure should be balanced so that the upper and lower parts 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 AIN material layer, the piezoelectric layer 122 is located on one side of the neutral layer of the cantilever beam, the AIN material layer is generally under 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.

[0093] 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. It should be noted that, if the acoustic transducer unit 120 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 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.

[0094] 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, a trapezoid, a circle, a semicircle, a quarter circle, an ellipse, or a 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 in parallel in the hollow part of the base structure, or may be suspended in sequence in the hollow part of the base structure along the arrangement direction of each layer of the laminated structures.

[0095] FIG. 3 is a schematic diagram of another bone conduction sound transmission device shown in some embodiments of the present application. The bone conduction sound transmission device 300 shown in FIG. 3 is almost the same as the bone conduction sound transmission device 100 shown in FIG. 1, and the biggest difference between them is that the shape of the laminated structure of the bone conduction sound transmission device 300 shown in FIG. 3 is different from that of the bone conduction sound transmission device 100 shown in FIG. 3. As shown in FIG. 3, the bone conduction sound transmission device 300 includes a base structure 310 and a laminated structure, and the shape of the laminated structure is trapezoidal. Furthermore, the width of the laminated structure of the bone conduction sound 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 sound 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 the structure of the base structure 110, and the structure of the vibration unit 330 is similar to the structure of the vibration unit 130. For details of each layer, such as the first electrode 321, the piezoelectric layer 322, and the second electrode 323 of the acoustic conversion unit 320, and the first elastic layer 331 and the second elastic layer 332 of the vibration unit 330, refer to the contents of each layer of the acoustic conversion unit 120 and the vibration unit 130 in Fig. 1. In addition, other members (e.g., seed layers) in the acoustic conversion unit 120 and the vibration unit 130 are similarly applied to the bone conduction acoustic transmission device 300 shown in Fig. 3, and description thereof will be omitted in this specification.

[0096] FIG. 4 is a schematic diagram of a bone conduction sound transmission device according to another embodiment of the present application. As shown in FIG. 4, the bone conduction sound transmission device 400 may include a base structure 410 and a laminated structure, and at least a part of the laminated structure is connected to the base structure 410. In some embodiments, the base structure 410 may be a frame structure with a hollow interior, and a part of the structure of the laminated structure (for example, an end of the laminated structure away from a connection point between the base structure 410 and the laminated structure) may be located in the hollow part of the frame structure. Note that the frame structure is not limited to the rectangular parallelepiped shape shown in FIG. 4, and 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 laminated structure may be fixedly connected to the base structure 410 in the form of a cantilever beam. Furthermore, the laminated structure may include a fixed end and a free end, and the fixed end of the laminated structure may be fixedly connected to the frame structure, and the free end of the laminated structure may be suspended in the hollow part of the frame structure by not connecting or contacting the frame structure. In some embodiments, the fixed end of the laminated structure may be connected to the upper surface, the lower surface, or the side wall of the base structure 410 where the hollow portion of the base structure 410 is located. In some embodiments, the side wall of the base structure 410 where the hollow portion of the base structure 410 is located may further be provided with a mounting groove that fits the fixed end of the laminated structure, so that the fixed end of the laminated structure may be matingly connected to the base structure 410. Here, "connection" may be understood as a fixed connection between the laminated structure and the base structure 410 by welding, riveting, fastening, bolting, or the like after the laminated structure and the base structure are manufactured, respectively. In some embodiments, the laminated structure may be deposited on the base structure 410 by a physical deposition (e.g., physical vapor deposition) or chemical deposition (e.g., chemical vapor deposition) method during manufacturing. In some embodiments, one or more laminated structures may be installed on the base structure 410, for example, the number of laminated structures may be one, two, three, seven, etc. Furthermore, the multiple laminated structures may be arranged uniformly at equal intervals along the circumferential direction of the base structure 410, or may be arranged non-uniformly.

[0097] 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 the upper surface or the 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, etc. 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 the embodiments herein, the piezoelectric layer 423 can generate a voltage (potential difference) under the action of the 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 from each other on the same surface (e.g., the top or bottom) 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 bottom surface of the piezoelectric layer 423, the electrode layer (the first electrode 421 and the second electrode 422) may be located on the top surface of the piezoelectric layer 423. Also, for example, when the vibration unit 430 is located on the top surface of the piezoelectric layer 423, the electrode layer (the first electrode 421 and the second electrode 422) may be located on the bottom 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 comb-like structure 4210, which may include a plurality of comb structures and have a first spacing between adjacent comb structures of the first comb-like structure 4210, which may be the same or different. The second electrode 422 may be folded into a second comb-like structure 4220, which may include a plurality of comb structures and have a second spacing between adjacent comb structures of the second comb-like structure 4220, which may be the same or different.The first comb-like structure 4210 may be meshed 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 enter the second interval of the second comb-like structure 4220, and the comb-like structure of the second comb-like structure 4220 may enter the first interval of the first comb-like structure 4210, thereby meshing with each other to form an electrode layer. By the meshing of the first comb-like structure 4210 and the second comb-like structure 4220 with each other, the first electrode 421 and the second electrode 422 are arranged compactly but do not cross. 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 fabricated from a piezoelectric ceramic material, and when the piezoelectric layer 423 is a piezoelectric ceramic material, the polarization direction of the piezoelectric layer 423 coincides 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 greatly enhance the output signal and improve the sensitivity. 33 is a proportional constant of the piezoelectric layer converting 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, the acoustic transducer unit 420 may be replaced by the acoustic transducer unit 120 shown in Fig. 1.

[0098] 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 is different, i.e., the deformation stress on the piezoelectric layer 423 of the acoustic transducer unit 420 from different positions of the vibration unit 430 is different. In order to improve the sensitivity of the bone conduction acoustic transmission device, in some embodiments, the acoustic transducer unit 420 is installed only at a position 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, in order 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 1 / 2 of the area of ​​the vibration unit 430. Preferably, the area of ​​the vibration unit 430 covered by the acoustic transducer unit 420 is 1 / 3 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 1 / 4 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) receives an external force near the connection point between the laminated structure and the base structure 410, the degree of deformation that occurs is large, and the acoustic transducer unit 420 receives a large deformation stress near the connection point between the laminated structure and the base structure 410. Therefore, by disposing 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. Note 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 with respect 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 microphone 100 can be improved by simply 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 ½ of 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 ⅓ of the area of ​​the piezoelectric layer. More preferably, the area of ​​the vibration unit 430 covered by the piezoelectric layer 423 is equal to or smaller than ¼ of 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 at 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.

[0099] 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 dimensions (e.g., length, width, and thickness) of the acoustic conversion 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.

[0100] 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, the length, width, spacing between the comb tooth structures (e.g., the first spacing and the second spacing) of the single comb tooth structures of the first comb tooth structure 4210 and the second comb tooth structure 4220, and the entire length of the acoustic conversion unit 420 can be adjusted to increase the output electrical signal and improve the signal-to-noise ratio of the bone conduction acoustic transmission device.

[0101] 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 local 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 part 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 a part of the structure of the laminated structure may be located in the hollow part of the frame structure. Note that the frame structure is not limited to the rectangular parallelepiped shape shown in FIG. 5, and in some embodiments, the frame structure may be a regular or irregular structure such as a pyramid truncated pyramid or a cylinder.

[0102] In some embodiments, the laminate structure may include an acoustic transducer unit 520 and a vibration unit.

[0103] In some embodiments, the resonant frequency of the bone conduction acoustic transmission device (also called a bone conduction microphone) and the stiffness of the vibration unit are positively correlated. When other parameters (e.g., the mass of the laminated structure) are not changed, the stiffness of the vibration unit is larger, the resonant frequency of the bone conduction acoustic transmission device is higher, and the stiffness of the vibration unit is smaller, the resonant frequency of the bone conduction acoustic transmission device is lower.

[0104] In some embodiments, the resonance frequency of the bone conduction acoustic transmission device and the mass of the laminated structure are negatively correlated: when other parameters (e.g., the stiffness of the vibration unit) are unchanged, the larger the mass of the laminated structure, the lower the resonance frequency of the bone conduction acoustic transmission device, and the smaller the mass of the laminated structure, the higher the resonance frequency of the bone conduction acoustic transmission device.

[0105] In some embodiments, the vibration unit may be installed on the 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 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. "Connecting" here may be understood as fixing the suspension membrane structure 530 to the upper surface, lower surface or side wall of the hollow portion of the base structure 510 by a mechanical fixing method (e.g., strong adhesion, rivet connection, clip, fitting, etc.) after the suspension membrane structure 530 and the base structure 510 are manufactured, respectively, or depositing the suspension membrane structure 530 onto the base structure 510 by a physical deposition method (e.g., physical vapor deposition) or chemical deposition method (e.g., chemical vapor deposition) during manufacturing.

[0106] In some embodiments, the stiffness of the vibration unit may be the stiffness of the suspension membrane structure 530 .

[0107] In some embodiments, the suspension membrane structure 530 may include at least one elastic layer. The elastic layer may be a membrane-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, single crystal silicon, polycrystalline silicon, etc. In some embodiments, the suspension membrane structure 530 may be made of one of the above semiconductor materials, or may be made of two or more of the above semiconductor materials stacked along the thickness direction. For example, the suspension membrane structure 530 may be a single crystal silicon (or polycrystalline silicon)-silicon dioxide composite layer, a single crystal silicon (or polycrystalline silicon)-silicon nitride composite layer, or a silicon nitride-single crystal silicon (or polycrystalline silicon)-silicon dioxide composite layer.

[0108] In some embodiments, the shape of the suspension membrane structure 530 may be a circle, an ellipse, a triangle, a square, a pentagon, a hexagon, or any other shape. For example, as shown in FIG. 22, the suspension membrane structure 530 may be a square. In some embodiments, as shown in FIG. 23, the suspension membrane structure 530 is a circle. In some embodiments, the suspension membrane structure 530 may be a circle, and the radius of the suspension membrane structure 530 is between 500 μm and 1500 μm. In some embodiments, the radius of the suspension membrane structure 530 is between 520 μm and 1400 μm. In some embodiments, the radius of the suspension membrane structure 530 is between 550 μm and 1300 μm. In some embodiments, the radius of the suspension membrane structure 530 is between 570 μm and 1200 μm. In some embodiments, the radius of the suspension membrane structure 530 is between 600 μm and 1100 μm. In some embodiments, the radius of the suspension membrane structure 530 is between 630 μm and 1000 μm. In some embodiments, the radius of the suspension membrane structure 530 is between 650 μm and 900 μm. In some embodiments, the radius of the suspension membrane structure 530 is between 670 μm and 850 μm. Note that the shape and dimensions (e.g., radius) of the suspension membrane structure 530 in this application refer to the shape and dimensions of a cross section perpendicular to the thickness direction (the direction indicated by the arrow in FIG. 6).

[0109] In some embodiments, the acoustic transducer unit 520 may be located on the upper or lower surface of the suspension membrane structure 530 .

[0110] In some embodiments, the suspension membrane structure 530 may include one hole 5300, which is located on the outside or inside of the acoustic transducer unit 520. In some embodiments, the suspension membrane structure 530 may include multiple holes 5300, which are distributed along the circumferential direction (e.g., the outer circumferential direction and / or the inner circumferential direction) of the acoustic transducer unit 520 around the center of the acoustic transducer unit 520. By providing the plurality of holes 5300 in the suspension membrane structure 530, the rigidity of different positions of the suspension membrane structure 530 can be adjusted to reduce the rigidity of the suspension membrane structure 530 in the area close to the plurality of holes 5300 and relatively increase the rigidity of the suspension membrane structure 530 away from the plurality of holes 5300. When the suspension membrane structure 530 and the base structure 510 move relatively, the degree of deformation of the suspension membrane structure 530 in the area close to the plurality of holes 5300 is large and the degree of deformation of the suspension membrane structure 530 in the area away from the plurality of holes 5300 is small. At this time, it can be understood that arranging the acoustic conversion unit 520 in the area close to the plurality of holes 5300 of the suspension membrane structure 530 helps the acoustic conversion unit 520 to collect vibration signals, thereby effectively improving the sensitivity of the bone conduction acoustic transmission device 500. In addition, since the structure of each component of the bone conduction acoustic transmission device 500 is simple, it can be easily manufactured or assembled.

[0111] In some embodiments, the holes 5300 of the suspension membrane structure 530 may be any shape, such as circular holes, elliptical holes, square holes, other polygonal holes, etc. For example, as shown in FIG. 22 and FIG. 23, the holes 5300 are square holes. For example, as shown in FIG. 24, the holes 5300 are irregularly shaped holes. Preferably, as shown in FIG. 25 and FIG. 26, the holes 5300 are circular holes, which can reduce local stress concentrations and improve the sensitivity of the bone conduction acoustic transmission device. In some embodiments, the holes 5300 are circular, and the radius of the holes 5300 is 20 μm to 300 μm. In some embodiments, the radius of the holes 5300 is 25 μm to 250 μm. In some embodiments, the holes 5300 may be non-through holes (e.g., grooves in the suspension membrane). In some embodiments, the holes 5300 may be through holes. In some embodiments, the number of the holes 5300 may be one or more. For example, the number of holes 5300 may be 2, 4, 6, 8, 10, 12, 14, 16, or 18.

[0112] In some embodiments, the holes 5300 may be distributed in the outer circumferential direction of the acoustic transducer unit 520, as shown in Figs. 22-24. In some embodiments, the holes 5300 may be distributed in the inner circumferential direction of the acoustic transducer unit 520, as shown in Fig. 25. In some embodiments, the holes 5300 may be uniformly or non-uniformly distributed in the outer circumferential direction and / or the inner circumferential direction of the acoustic transducer unit 520. Preferably, the holes 5300 are uniformly distributed at equal intervals in the outer circumferential direction and / or the inner circumferential direction of the acoustic transducer unit 520, as shown in Figs. 23-25. In some embodiments, the holes 5300 may be surrounded by one, two or multiple circumferences. For example, as shown in Figs. 23-25, the holes 5300 are surrounded by one circumference. Also, for example, as shown in Fig. 26, the holes 5300 are surrounded by two circumferences. Preferably, the holes 5300 are surrounded by one circumference. In some embodiments, the shape surrounded by the hole 5300 may be a circle, an ellipse, a rectangle, a polygon, or other regular or irregular shape. In the present application, the shape surrounded by the hole 5300 is the shape surrounded by the center of the hole 5300 (also called the center), and the dimension of the shape surrounded by the center of the hole 5300 is the distance value between the two farthest points of the shape surrounded by the center of the hole 5300. For example, the shape surrounded by the center of the hole 5300 may be a circle, and the dimension of the shape surrounded by the center of the hole 5300 may be the diameter of the circle. For example, the shape surrounded by the center of the hole 5300 may be a square, and the dimension of the shape surrounded by the center of the hole 5300 may be the length of the diagonal of the square. For example, the shape enclosed by the center of hole 5300 may be an irregular shape, and the dimension of the shape enclosed by the center of hole 5300 may be the distance between the two most distant apexes of the irregular shape.

[0113] In some embodiments, the shape of the acoustic transducer unit 520 may include a square, a circle, an ellipse, a curved ring, a polygon, or other regular or irregular shape. For example, as shown in FIG. 22, the shape of the acoustic transducer unit 520 is a square. Also, for example, as shown in FIGS. 23 to 27, the shape of the acoustic transducer unit 520 is a circular ring. In some embodiments, the shape of the acoustic transducer unit 520 may be a ring with one or more openings. For example, as shown in FIG. 27, the shape of the acoustic transducer unit 520 is a circular ring with two openings. In some embodiments, the acoustic transducer unit 520 is a closed circular ring.

[0114] The shape of the acoustic conversion unit 520 in one or more embodiments of the present application may be the shape of a cross section perpendicular to the thickness direction (the direction indicated by the arrow in FIG. 6) of the acoustic conversion unit.

[0115] In some embodiments, the relevant dimensions of the acoustic transducer unit 520 (e.g., inner or outer diameter dimensions of the acoustic transducer unit) affect the resonant frequency of the vibration system. In some embodiments, the dimensions of the acoustic transducer unit may include an outer diameter dimension and / or an inner diameter dimension of a cross section perpendicular to a thickness direction of the acoustic transducer unit. In some embodiments, the outer diameter dimension of the acoustic transducer unit 520 may be an outer diameter dimension of a cross section perpendicular to a thickness direction of the acoustic transducer unit 520. In some embodiments, the inner diameter dimension of the acoustic transducer unit 520 may be an inner diameter dimension of a cross section perpendicular to a thickness direction of the acoustic transducer unit 520. The outer diameter dimension of the cross section may be the distance between two farthest points of the outer edge of the cross section. For example, if the cross section is circular, the outer diameter dimension of the cross section may be the diameter of the circle. Also, for example, if the cross section is elliptical, the outer diameter dimension of the cross section may be the major axis of the ellipse. Also, for example, if the cross section is rectangular, the outer diameter dimension of the cross section may be the length of a diagonal of the rectangle. For example, if the cross section is an irregular rectangle, the outer diameter of the cross section may be the distance between the two most distant apex angles of the rectangle. The inner diameter of the cross section may be the distance between the two closest points of the inner edge of the cross section, and a straight line passing through these two points passes through the geometric center of the inner edge. For example, if the inner edge shape of the cross section is a circle, the inner diameter of the cross section may be the diameter of the circle. For example, if the inner edge shape of the cross section is an ellipse, the inner diameter of the cross section may be the minor axis of the ellipse. For example, if the inner edge shape of the cross section is a rectangle, the inner diameter of the cross section may be the side length of the minor side of the rectangle.

[0116] In some embodiments, the acoustic transducer unit 520 may include at least an effective acoustic transducer unit. The effective acoustic transducer unit is a part of the structure of the acoustic transducer unit that finally outputs an electrical signal. In some embodiments, the effective acoustic transducer unit 520 may have an inner diameter dimension of 100 μm to 700 μm. In some embodiments, the effective acoustic transducer unit 520 may have an inner diameter dimension of 130 μm to 600 μm. In some embodiments, the effective acoustic transducer unit 520 may have an inner diameter dimension of 150 μm to 500 μm. In some embodiments, the effective acoustic transducer unit 520 may have an inner diameter dimension of 200 μm to 400 μm. In some embodiments, the effective acoustic transducer unit 520 may have an outer diameter dimension of 110 μm to 710 μm. In some embodiments, the effective acoustic transducer unit 520 may have an outer diameter dimension of 150 μm to 650 μm. In some embodiments, the effective acoustic transducer unit 520 may have an outer diameter dimension of 200 μm to 620 μm. In some embodiments, the outer diameter of the effective acoustic transducer unit 520 may be between 250 μm and 600 μm.

[0117] In some embodiments, the shape surrounded by the plurality of holes 5300 is consistent with the shape of the acoustic transducer unit 520. For example, as shown in FIG. 22, the shape of the acoustic transducer unit 520 is a square, and the shape surrounded by the plurality of holes 5300 is a square. Also, for example, as shown in FIG. 23, the shape surrounded by the plurality of holes 5300 is a circle, and the shape of the acoustic transducer unit 520 is a circle. In some embodiments, the shape of the plurality of holes 5300 is consistent with the shape of the acoustic transducer unit 520. For example, as shown in FIG. 22, the shape of the plurality of holes 5300 is a square, and the shape of the acoustic transducer unit 520 is a square. Preferably, the plurality of holes 5300 are distributed in a circular shape along the circumferential direction of the acoustic transducer unit 520. In some embodiments, the shapes of the plurality of holes 5300 may be consistent or not consistent. For example, the shape of the plurality of holes 5300 may be one of a circle, an ellipse, a square, a polygon, and an irregular shape. For example, the shape of the plurality of holes 5300 may include a combination of two or more of the following shapes: circular, elliptical, rectangular, polygonal, and irregular. In some embodiments, the radius of the circle surrounded by the plurality of holes 5300 may be between 300 μm and 700 μm. In some embodiments, the radius of the circle surrounded by the plurality of holes 5300 is between 350 μm and 650 μm.

[0118] In some embodiments, the outer diameter of the effective acoustic transducer unit 520 may be smaller than, equal to, or larger than the dimension of the shape surrounded by the center of each hole of the plurality of holes 5300. In some embodiments, the inner diameter of the effective acoustic transducer unit 520 may be smaller than, equal to, or larger than the dimension of the shape surrounded by the center of each hole of the plurality of holes 5300. Preferably, the shape of the acoustic transducer unit 520 is annular (i.e., both the inside and outside of the cross section perpendicular to the thickness direction of the acoustic transducer unit 520 are circular), the shape surrounded by the plurality of holes 5300 is circular, and the radius of the inner edge of the effective acoustic transducer unit 520 (i.e., the inner radius of the cross section perpendicular to the thickness direction of the effective acoustic transducer unit 520) is smaller than the radius of the circle surrounded by the plurality of holes 5300. In some embodiments, the radius of the inner edge of the effective acoustic transducer unit 520 is smaller than the radius of the circle surrounded by the plurality of holes 5300, and the difference between the radius of the inner edge of the effective acoustic transducer unit 520 and the radius of the circle surrounded by the plurality of holes 5300 may be 50 μm to 300 μm. In some embodiments, the difference between the radius of the inner edge of the effective acoustic transducer unit 520 and the radius of the circle surrounded by the plurality of holes 5300 may be 70 μm to 250 μm. In some embodiments, the difference between the radius of the inner edge of the effective acoustic transducer unit 520 and the radius of the circle surrounded by the plurality of holes 5300 may be 90 μm to 230 μm.

[0119] In some embodiments, the outer diameter of the effective acoustic transducer unit 520 may be smaller than, equal to, or larger than the dimension of the hollow cavity of the base structure 510. In some embodiments, the inner diameter of the effective acoustic transducer unit 520 may be smaller than, equal to, or larger than the dimension of the hollow cavity of the base structure 510. The dimension of the hollow cavity of the base structure 510 is the distance value between the two farthest points of the inner edge of the cross section perpendicular to the thickness direction of the base structure 510. The shape and dimensions of the inner edge of the cross section perpendicular to the thickness direction of the base structure 510 are similar to the shape and dimensions of the circle surrounded by the centers of the holes 5300, and will not be described in this specification. Preferably, the outer diameter of the effective acoustic transducer unit 520 is smaller than the dimension of the hollow cavity of the base structure 510. In some embodiments, the outer diameter of the effective acoustic transducer unit 520 is smaller than the dimension of the hollow cavity of the base structure 510, and the difference between the dimension of the hollow cavity of the base structure 510 and the outer diameter of the effective acoustic transducer unit 520 is in the range of 5 μm to 400 μm. In some embodiments, the shapes of the hollow cavities of the acoustic transducer unit 520 and the base structure 510 may be the same or different. In some embodiments, when the shapes of the hollow cavities of the acoustic transducer unit 520 and the base structure 510 are the same, the difference between the dimension of the hollow cavity of the base structure 510 and the outer diameter of the effective acoustic transducer unit 520 may be in the range of 5 μm to 400 μm. For example, the shape of the acoustic transducer unit 520 is annular, the shape of the hollow cavity of the base structure 510 is circular, and the difference between the outer diameter of the effective acoustic transducer unit 520 and the dimension of the hollow cavity of the base structure 510 may be in the range of 5 μm to 400 μm. In some embodiments, the difference between the maximum dimensions of both may be in the range of 20 μm to 380 μm. In some embodiments, the difference between the maximum dimensions of both may be in the range of 50 μm to 350 μm. In some embodiments, the difference between the maximum dimensions of both may be in the range of 80 μm to 320 μm.

[0120] In some embodiments, the sensitivity of the bone conduction acoustic transmission device 500 can be improved by adjusting the resonance frequency (setting the resonance frequency to 2 kHz to 5 kHz) and stress distribution of the bone conduction acoustic transmission device 500 by changing the size, number, spacing, and position of the multiple holes 5300. Note that the resonance frequency is not limited to the above 2 kHz to 5 kHz, but may be 3 kHz to 4.5 kHz or 4 kHz to 4.5 kHz, and the range of the resonance frequency can be adaptively adjusted according to various application scenes, and is not further limited in this specification.

[0121] 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 that are arranged in 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) under the action of the deformation stress of the vibration unit (e.g., the suspension membrane structure 530) based on the piezoelectric effect, and the first electrode layer 521 and the second electrode layer 523 can derive 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., an AlN film material) manufactured by a deposition process (e.g., a magnetron sputtering deposition process). 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), sugar, and the like, or any combination thereof. Piezoelectric ceramic material is a piezoelectric polycrystal with randomly assembled 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), and the like, or any combination thereof. In some embodiments, the piezoelectric layer 522 may be a piezoelectric polymer material, such as polyvinylidene fluoride (PVDF). In some embodiments, the first electrode layer 521 and the second electrode layer 523 are conductive material structures. Exemplary conductive materials may include metals, metal alloy materials, metal oxide materials, graphene, etc., or any combination thereof. In some embodiments, metal and metal 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 copper zinc alloy, copper tin alloy, copper nickel silicon alloy, copper chromium alloy, copper silver alloy, etc., or any combination thereof. In some embodiments, the metal oxide material may include RuO2, MnO2, PbO2, NiO, etc., or any combination thereof.

[0122] In some embodiments, the effective acoustic transducer unit may include an overlapping region of the first electrode layer 521, the piezoelectric layer 522, and the second electrode layer 523. For example, when the first electrode layer 521, the piezoelectric layer 522, and the second electrode layer 523 have the same shape and area and partially cover the suspension membrane structure 530, the first electrode layer 521, the piezoelectric layer 522, and the second electrode layer 523 are effective acoustic transducer units. For example, when the first electrode layer 521 and the piezoelectric layer 522 partially cover the suspension membrane structure 530 and the second electrode layer 523 covers the entire suspension membrane structure 530, the portions of the first electrode layer 521, the piezoelectric layer 522, and the second electrode layer 523 that correspond one-to-one along the thickness direction constitute an effective acoustic transducer unit. In addition, the dimensions (e.g., inner diameter, outer diameter) and corresponding parameters (e.g., the difference between the radius of the inner edge of the acoustic conversion unit 520 and the radius of the circle surrounded by multiple holes 5300, the range of the difference between the dimension of the hollow cavity of the base structure 510 and the outer diameter dimension of the acoustic conversion unit 520, and the radial spacing from the edge of the acoustic conversion unit 520 to the center of each hole 5300) of the acoustic conversion unit described in this specification are all valid dimensions and corresponding parameters of the acoustic conversion unit.

[0123] In some embodiments, the acoustic transducer unit 520 may further include a seed layer. The seed layer may optimize the lattice structure of the first electrode layer 521, the second electrode layer 523, and the piezoelectric layer 522 deposited thereon, ensure the quality of the acoustic transducer unit 520, and improve the adhesion of the film layer. In some embodiments, the seed layer may be manufactured on the silicon substrate by a physical vapor deposition (PVD) method or a chemical vapor deposition (CVD) method. In some embodiments, the seed layer may have a thickness of 5 nm to 200 nm. In some embodiments, the seed layer may have a thickness of 8 nm to 150 nm. Note that the acoustic transducer unit 520 may not have a seed layer. In some embodiments, the second electrode layer 523 may be manufactured on the upper surface of the seed layer or the upper surface of the silicon substrate by a PVD method or a CVD method. In some embodiments, the second electrode layer 523 may have a thickness of 80 nm to 250 nm. In some embodiments, the second electrode layer 523 has a thickness of 100 nm to 200 nm. In some embodiments, the piezoelectric layer 522 can be manufactured on the upper surface of the second electrode layer 523 by a PVD method or a CVD method. In some embodiments, the piezoelectric layer 522 can have a thickness of 0.8 μm to 5 μm. In some embodiments, the piezoelectric layer 522 has a thickness of 0.8 μm to 4 μm. In some embodiments, the first electrode layer 521 can be manufactured on the upper surface of the piezoelectric layer 522 by a PVD method or a CVD method. In some embodiments, the first electrode layer 521 can have a thickness of 80 nm to 250 nm. In some embodiments, the first electrode layer 521 has a thickness of 90 nm to 230 nm. In some embodiments, the first electrode layer 521, the piezoelectric layer 522, and the second electrode layer 523 can be etched in order. In some embodiments, the first electrode layer 521, the piezoelectric layer 522, and the second electrode layer 523 can be etched by dry etching or wet etching.

[0124] As shown in FIG. 5, in some embodiments, the plurality of holes 5300 surround a circular region, and in order to improve the sound pressure output effect of the acoustic transducer unit 520, the acoustic transducer unit 520 may be installed in a region close to the plurality of holes 5300 in the suspension membrane structure 530, and further, the acoustic transducer unit 520 may be annular and distributed along the inside of the circular region surrounded by the plurality of holes 5300. As shown in FIG. 23-FIG. 24, the acoustic transducer unit 520 is distributed along the inside of the circular region surrounded by the plurality of holes 5300. In some embodiments, the annular acoustic transducer unit 520 may be distributed along the outside of the circular region surrounded by the plurality of holes 5300. As shown in FIG. 25, the acoustic transducer unit 520 is distributed along the outside of the circular region surrounded by the plurality of holes 5300. Preferably, the annular acoustic transducer unit 520 may be distributed along the inside of the circular region surrounded by the plurality of holes 5300, and the circular region surrounded by the plurality of holes 5300 is distributed inside the base structure 510. 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.

[0125] In some embodiments, the size, number, and distribution positions of the plurality of holes 5300 in the suspension membrane structure 530 and the shape, dimensions, and positions of the acoustic transducer unit 520 can be adjusted to adjust the equivalent stiffness and equivalent mass of the bone conduction acoustic transmission device 500, adjust the resonance frequency and stress distribution of the bone conduction acoustic transmission device 500, and further adjust the output electrical signal of the bone conduction acoustic transmission device 500, thereby improving the sensitivity of the bone conduction acoustic transmission device 500. In some embodiments, the holes 5300 in the suspension membrane structure 530 can be manufactured by an etching process. In some embodiments, the etching process can include a dry etching process or a wet etching process.

[0126] In some embodiments, the acoustic transducer unit 520 further includes a lead structure 5200, which transmits the 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, the first electrode layer 521 and the second electrode layer 523 are connected to the base structure 510 by the lead structure 5200. In some embodiments, the lead structure 5200 includes a first lead and a second lead. The first lead has one end connected to the first electrode layer 521 and the other end connected to the base structure 510, and the second lead has one end connected to the second electrode layer 521 and the other end connected to the base structure 510.

[0127] In some embodiments, adjusting the shape, dimensions (e.g., length, width, and thickness), and material of the lead structure 5200 can lower the resonant frequency and improve the output electrical signal of the bone conduction acoustic transmission device 500, thereby improving the sensitivity of the bone conduction acoustic transmission device 500.

[0128] In some embodiments, the lead structure 5200 may include straight lines, broken lines, and curved lines. Preferably, the lead structure 5200 is straight, as shown in FIGS. 22-27. Alternatively, for example, the lead structure 5200 is curved, as shown in FIG. 28. In some embodiments, the width of the lead structure 5200 (width d shown in FIGS. 27-28) may be between 2 μm and 100 μm. In some embodiments, the width is between 10 μm and 100 μm. In some embodiments, the width is between 15 μm and 90 μm. In some embodiments, the width is between 20 μm and 80 μm.

[0129] FIG. 29 is a schematic diagram of a lead structure of another bone conduction acoustic transmission device according to some embodiments of the present application. In some embodiments, the first electrode layer 521 is connected to the upper surface, lower surface, or side surface of the base structure 510 by the lead structure 5200. In some embodiments, as shown in FIG. 29, the first electrode layer 521 is connected to the pad 5210 by the lead structure 5200. The pad 5210 may be located on the upper surface, lower surface, or side surface of the base structure 510, and as shown in FIG. 29, the pad 5210 may be located on the upper surface of the base structure 510, and guides an electrical signal between the acoustic transduction unit 520 and the housing, the lead structure 5200, etc. By connecting the first electrode layer 521 to the pad 5210 by the lead structure 5200, the electrical signal between the acoustic transduction unit 520 and the housing and the lead structure 5200 can be reduced, the parasitic capacitance can be reduced, and the sensitivity of the bone conduction acoustic transmission device 500 can be improved. In some embodiments, the pad 5210 may be circular, elliptical, triangular, polygonal, or irregularly shaped. In some embodiments, the maximum dimension range of the pad 5210 is 80 μm to 500 μm. The maximum dimension range may be a side length or a diameter. For example, if the pad 5210 is rectangular, the maximum side length of the pad 5210 may be 80 μm to 500 μm. Also, for example, if the pad 5210 is circular, the maximum diameter of the pad 5210 may be 80 μm to 500 μm. In some embodiments, the maximum dimension range of the pad 5210 is 85 μm to 450 μm. In some embodiments, the maximum dimension range of the pad 5210 is 90 μm to 400 μm. Note that the shape and dimensions of the pad 5210 in this application are the shape and dimensions of a cross section perpendicular to the thickness direction. In some embodiments, the pad 5210 can be fabricated by depositing a single or multi-layer metal (e.g., Pt, Au, Ti, Cr, Ti / Au, etc.) to which the wire is easily welded. Preferably, the metal deposited on the pad 5210 can be Ti / Au or Gr / Au. In some embodiments, the pad 5210 can be fabricated by a metal lift-off process (Metal Lift-Off Technology, LIFT-OFF). In some embodiments, the deposition thickness of the pad 5210 is between 100 nm and 300 nm.Preferably, the deposition thickness is 150 nm to 250 nm. In some embodiments, the back side of the silicon substrate is subjected to adhesive uniformization, photolithography development process to obtain a patterned deep silicon emission window, and a deep silicon etching process is used to etch the silicon into the oxide layer of the silicon substrate, and then the oxide layer of the silicon substrate is removed to obtain the bone conduction acoustic transmission device 3100.

[0130] In some embodiments, in order to improve the output electrical signal of the bone conduction acoustic transmission device 500, the radial distance from the edge of the effective acoustic transducer unit 520 (e.g., annular structure) to the center of each hole 5300 may be 50 μm to 400 μm. The edge of the effective acoustic transducer unit 520 (e.g., annular structure) may be an inner edge or an outer edge. In some embodiments, the radial distance from the edge of the effective acoustic transducer unit 520 (e.g., annular structure) to the center of each hole 5300 may be 100 μm to 350 μm. Preferably, the radial distance from the edge of the effective 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 effective 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 thickness or density of different regions of the suspension membrane structure 530 is the same. In some embodiments, the thickness of the suspension membrane structure 530 is between 0.5 μm and 10 μm. Preferably, the thickness is between 0.5 μm and 5 μm. In some alternative embodiments, the deformation stress at different positions of the suspension membrane structure 530 may be further adjusted by adjusting the thickness or density of different regions of the suspension membrane structure 530. For illustrative purposes only, in some embodiments, the acoustic transducer unit 520 is set in an annular structure, and the thickness of the suspension membrane structure 530 at the inner region of the annular structure is greater than the thickness of the suspension membrane structure 530 at the outer region of the annular structure. The thickness of the suspension membrane structure at the inner region of the annular structure or the thickness of the suspension membrane structure at the outer region is the dimension in the thickness direction in FIG. 6. In some other embodiments, the density of the suspension membrane structure 530 at the inner region of the annular structure is greater than the density of the suspension membrane structure 530 at the outer region of the annular structure. By changing the density or thickness at different positions 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, or the stiffness of the suspension membrane in the inner region of the annular structure is less than the stiffness of the suspension membrane in the outer region of the annular structure, so that when the suspension membrane structure 530 and the base structure 510 move relative to each other, the degree of deformation generated in the suspension membrane structure 530 near the annular structure of the acoustic conversion unit 520 (i.e., the inner region of the suspension membrane structure 530) is greater, and the generated deformation stress is also greater, resulting in a larger electrical signal output from the bone conduction acoustic transmission device 500 and a higher sensitivity of the bone conduction acoustic transmission device 500.

[0132] In addition, the shape of the area surrounded by the multiple 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 (a sector with a central angle of 90°), an ellipse, a semi-ellipse, a triangle, a rectangle, etc., and the shape of the acoustic transducer unit 520 can be adaptively adjusted according to the shape of the area surrounded by the multiple holes 5300. For example, when the shape of the area surrounded by the multiple holes 5300 is a rectangle, the shape of the acoustic transducer unit 520 may be a rectangle, and the rectangular acoustic transducer units 520 may be distributed along the inside or outside of the rectangle surrounded by the multiple holes 5300. Also, for example, when the shape of the area surrounded by the multiple holes 5300 is a semicircle, the shape of the acoustic transducer unit 520 may be a semi-ring, and the semi-ring acoustic transducer units 520 may be distributed along the inside or outside of the semi-ring shape surrounded by the multiple holes 5300. In some embodiments, the suspension membrane structure 530 shown in FIG. 5 may not have holes.

[0133] Fig. 7 is a schematic diagram of a bone conduction acoustic transmission device according to some embodiments of the present application, and Fig. 30 is a cross-sectional view of a local structure of the bone conduction acoustic transmission device shown in Fig. 7.

[0134] The structure of the bone conduction acoustic transmission device 700 shown in FIG. 7 is roughly 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 and 30, the 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 is connected to the base structure 710. In some embodiments, the base structure 710 may be a hollow frame structure, and a portion of the structure 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 laminated structure may include an acoustic transducer unit 720 and a vibration unit. In some embodiments, the vibration unit may be installed on the upper or lower surface of the acoustic transducer unit 720. As shown in FIG. 7, the vibration unit may include a suspension membrane structure 730 and a mass element 740, and the mass element 740 may be located on the upper or lower surface of the suspension membrane structure 730. In some embodiments, the suspension membrane structure 730 may be located on the upper or lower surface of the base structure 710. In some embodiments, the periphery of the suspension membrane structure 730 may be connected to the inner wall of the hollow portion of the base structure 710. "Connecting" here may be understood as fixing the suspension membrane structure 730 to the upper surface, lower surface or side wall of the hollow portion of the base structure 710 in a mechanical fixing manner (e.g., strong adhesion, rivet connection, clip, fitting, etc.) after the suspension membrane structure 730 and the base structure 710 are manufactured, respectively, or depositing the suspension membrane structure 730 onto the base structure 710 in a physical deposition manner (e.g., physical vapor deposition) or chemical deposition manner (e.g., chemical vapor deposition) during manufacturing.

[0137] In some embodiments, the shape of the suspension membrane structure 730 may be a circle, an ellipse, a triangle, a rectangle, a pentagon, a hexagon, or any other shape. Preferably, the suspension membrane structure 730 is a circle, as shown in Figures 31A-31C. For more details about the suspension membrane structure 730, please refer to the description of the suspension membrane structure 530 in Figure 5, and the description will be omitted in this specification.

[0138] In some embodiments, the mass of the laminated structure may include the mass of the mass element 740. 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, and the degree of deformation of the suspension membrane structure 730 in the area where the mass element 740 is located or in the vicinity thereof is greater than the degree of deformation of the suspension membrane structure 730 in the area away from the mass element 740. In order to improve the output sound pressure of the bone conduction sound 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 units 720 may be the same as or different from the shape of the mass element 740. Preferably, the shape of the acoustic transducer units 720 may be the same as the shape of the mass element 740, so that each position of the acoustic transducer units 720 can be close to the mass element 740, thereby further improving the output electric signal of the bone conduction sound output device 700. For example, the mass element 740 may have a cylindrical structure, and the acoustic transducer unit 720 may have an annular structure, in which 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. Note that the shapes and dimensions of the acoustic transducer unit 720 and the mass element 740 in this application are the shapes and dimensions of the cross sections perpendicular to the thickness direction.

[0139] In some embodiments, the acoustic transducer unit 720 may include a first electrode layer 721, a second electrode layer 723, and a piezoelectric layer 722 located between the two electrode layers, and the first electrode layer 721, the piezoelectric layer 722, and the second electrode layer 723 are combined into a structure that matches the shape of the mass element 740. For example, the mass element 740 may be a cylindrical structure, and the acoustic transducer unit 720 may be an annular structure, in which the first electrode layer 721, the piezoelectric layer 722, and the second electrode layer 723 are all annular structures, and the three are sequentially arranged from top to bottom to be combined into the annular structure.

[0140] In some embodiments, the shape of the acoustic conversion unit 720 may be a circular ring, a polygonal ring, or a curved ring. For example, as shown in FIG. 31A to FIG. 31C, the shape of the acoustic conversion unit 720 is a circular ring. For example, as shown in FIG. 32A, the shape of the acoustic conversion unit 720 is a regular hexagonal ring. For example, as shown in FIG. 32C to FIG. 32D, the shape of the acoustic conversion unit 720 is a regular square ring. In some embodiments, the shape of the acoustic conversion unit 720 may be a closed ring, an open ring, or a multi-stage ring. For example, as shown in FIG. 32A, the shape of the acoustic conversion unit 720 is a closed ring. For example, as shown in FIG. 32B, the shape of the acoustic conversion unit 720 is a circular two-stage ring. Preferably, as shown in FIG. 31A to FIG. 31C, the shape of the acoustic conversion unit 720 is a circular closed ring.

[0141] In some embodiments, the inner diameter and the outer diameter of the acoustic transducer unit 720 affect the resonant frequency of the vibration system. In some embodiments, the inner diameter of the acoustic transducer unit 720 may be 100 μm to 700 μm. In some embodiments, the outer diameter of the acoustic transducer unit 720 may be 110 μm to 710 μm. The inner diameter and the outer diameter of the acoustic transducer unit 720 are similar to the inner diameter and the outer diameter of the acoustic transducer unit 520, and specifically, reference may be made to the relevant contents of FIG. 5, which will not be further described in this specification.

[0142] In some embodiments, the outer diameter of the acoustic transducer unit 720 may be smaller than, equal to, or larger than the dimension of a cross section perpendicular to the thickness direction of the mass element 740. In some embodiments, the inner diameter of the acoustic transducer unit 720 may be smaller than, equal to, or larger than the dimension of a cross section perpendicular to the thickness direction of the mass element 740. Preferably, the cross section perpendicular to the thickness direction of the mass element 740 is circular, and the inner diameter of the acoustic transducer unit 720 is slightly larger than the diameter of the cross section perpendicular to the thickness direction of the mass element 740. In some embodiments, the inner diameter of the acoustic transducer unit 720 is larger than the diameter of the cross section perpendicular to the thickness direction of the mass element 740, and the difference between the inner diameter of the acoustic transducer unit 720 and the diameter of the cross section perpendicular to the thickness direction of the mass element 740 may be between 5 μm and 200 μm. In some embodiments, the inner diameter of the acoustic transducer unit 720 is larger than the diameter of the mass element by 10 μm to 180 μm. In some embodiments, the inner diameter of the acoustic transducer unit 720 is between 20 μm and 160 μm larger than the diameter of the mass element. In some embodiments, the inner diameter of the acoustic transducer unit 720 is between 30 μm and 140 μm larger than the diameter of the mass element. In some embodiments, the inner diameter of the acoustic transducer unit 720 is between 40 μm and 120 μm larger than the diameter of the mass element.

[0143] In some embodiments, the outer diameter dimension of the acoustic transducer unit 720 may be smaller than, equal to, or larger than the dimension of the hollow cavity of the base structure. In some embodiments, the inner diameter dimension of the acoustic transducer unit 720 may be smaller than, equal to, or larger than the dimension of the hollow cavity of the base structure. The hollow cavity of the base structure is similar to the hollow cavity of the base structure 510, and can be specifically referred to the relevant contents of FIG. 5, and will not be further described herein. Preferably, the outer diameter dimension of the acoustic transducer unit 720 is smaller than the dimension of the hollow cavity of the base structure. In some embodiments, the outer diameter dimension of the acoustic transducer unit 720 is smaller than the dimension of the hollow cavity of the base structure, and the difference between the dimension of the hollow cavity of the base structure and the outer diameter dimension of the acoustic transducer unit 720 may be in the range of 5 μm to 400 μm. For the dimensions of the acoustic transducer unit 720 and the hollow cavity of the base structure, reference can be made to the description of FIG. 5, and the description will be omitted in this specification.

[0144] In some embodiments, the mass element 740 may be one or more. In some embodiments, the multiple mass elements 740 may be uniformly disposed along the inside of the acoustic transducer unit 720. In some embodiments, the mass element 740 may be cylindrical, polygonal prism-shaped, spherical, or irregular. For example, as shown in FIG. 32A, the mass element 740 is a regular hexagonal prism. For example, as shown in FIG. 32B, the mass element 740 is a cylindrical shape. For example, as shown in FIGS. 32C to 32D, the mass element 740 is a quadrangular prism. Note that the description of the shape of each assembly of the bone conduction acoustic transmission device in this specification may refer to the outer shape of each assembly, or may refer to the shape of a cross section perpendicular to the thickness direction of each assembly.

[0145] In some embodiments, mass element 740 is cylindrical and the radius of a cross section perpendicular to the thickness direction of mass element 740 may be between 100 μm and 700 μm. In some embodiments, the radius of a cross section perpendicular to the thickness direction of mass element 740 may be between 120 μm and 600 μm. In some embodiments, the radius of a cross section perpendicular to the thickness direction of mass element 740 may be between 140 μm and 500 μm. In some embodiments, the radius of a cross section perpendicular to the thickness direction of mass element 740 may be between 160 μm and 400 μm. In some embodiments, the radius of a cross section perpendicular to the thickness direction of mass element 740 may be between 200 μm and 350 μm. In some embodiments, the axial thickness (also referred to as the thickness along the thickness direction) of mass element 740 may be between 20 μm and 400 μm. In some embodiments, the axial thickness may be between 25 μm and 300 μm. In some embodiments, the axial thickness may be between 30 μm and 200 μm. In some embodiments, the axial thickness may be between 35 μm and 150 μm.

[0146] In some embodiments, mass element 740 may be a single layer structure or a multi-layer structure. In some embodiments, when mass element 740 is a single layer structure, mass element 740 may be made of a single material. In some embodiments, the single material may include, but is not limited to, any one of silicon-based materials such as single crystal silicon, polycrystalline silicon, silicon dioxide, silicon nitride, silicon carbide, etc. Preferably, mass element 740 may be single crystal silicon or polycrystalline silicon. In some embodiments, when mass element 740 is a multi-layer structure, mass element 740 may be made of multiple materials. In some embodiments, the multiple materials may include, but are not limited to, two or more of silicon-based materials such as single crystal silicon, polycrystalline silicon, silicon dioxide, silicon nitride, silicon carbide, etc.

[0147] In some embodiments, the acoustic transducer unit 720 and the mass element 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 unit 720 and the mass element 740 are both located on the upper surface or the lower surface of the suspension membrane structure 730, and the acoustic transducer unit 720 is distributed along the circumferential direction of the mass element 740. For example, the acoustic transducer unit 720 is located on the upper surface of the suspension membrane structure 730, and the mass element 740 is located on the lower surface of the suspension membrane structure 730, and the projection of the mass element 740 onto the suspension membrane structure 730 is within the area of ​​the acoustic transducer unit 720. For example, the acoustic transducer unit 720 is located on the lower surface of the suspension membrane structure 730, and the mass element 740 is located on the upper surface of the suspension membrane structure 730, and the projection of the mass element 740 onto the suspension membrane structure 730 is within the area of ​​the acoustic transducer unit 720.

[0148] In some embodiments, the mass element 740 and the hollow cavity of the acoustic transducer unit 720 or base structure 710 are disposed coaxially. For example, as shown in FIG. 31A-31B, the mass element 740 and the acoustic transducer unit 720 are disposed coaxially. In some embodiments, the mass element 740 and the hollow cavity of the acoustic transducer unit 720 or base structure 710 are disposed on different axes. For example, as shown in FIG. 31C, the mass element 740 and the acoustic transducer unit 720 are disposed on different axes. In some embodiments, the misalignment between the mass element 740 and the acoustic transducer unit 720 may be between 0 μm and 50 μm. In some embodiments, the misalignment between the mass element 740 and the acoustic transducer unit 720 may be between 5 μm and 45 μm. In some embodiments, the misalignment between the mass element 740 and the acoustic transducer unit 720 may be between 10 μm and 40 μm. In some embodiments, the misalignment between the mass element 740 and the acoustic transducer unit 720 may be between 15 μm and 35 μm. In some embodiments, the misalignment between the mass element 740 and the acoustic transducer unit 720 may be between 20 μm and 30 μm. When the mass element 740 and the acoustic transducer unit 720 are on different axes, the output voltage decreases and the output electrical signal decreases, and preferably, the axial misalignment between the mass element 740 and the acoustic transducer unit 720 is 0 μm, that is, the mass element 740 and the acoustic transducer unit 720 are installed coaxially.

[0149] In some embodiments, the mass element 740 can be manufactured on a substrate (the same material as the base structure 710) by a process such as photolithography, etching, etc. Furthermore, the substrate on which the mass element 740 is manufactured and the substrate on which the suspension membrane structure 730 and the base structure 710 are manufactured can be bonded at the wafer level. In some embodiments, the bonding area can be the area of ​​the mass element 740. In other embodiments, the bonding area can include the area of ​​the mass element 740 and a part of the area of ​​the base structure 710 while ensuring leak holes in the acoustic transducer unit and pad areas of the base structure 710. In some embodiments, the area of ​​the bonding area of ​​the base structure 710 can occupy 10% to 90% of the area of ​​a cross section perpendicular to the thickness direction of the base structure 710. In some embodiments, a wafer thinning process can be used to remove excess material other than the mass element 740 from the substrate on which the mass element 740 is located. In other embodiments, the mass element 740 can be further manufactured on the substrate on which the acoustic transducer unit 720 is manufactured. Specifically, the other side of the base material for manufacturing the acoustic transducer unit 720 (the opposite side for manufacturing the acoustic transducer unit 720) can be etched to a certain depth using a deep silicon etching process after performing operations such as uniformizing the adhesive and photolithography development processing. Then, the mass element 740 is further etched using a deep silicon etching process.

[0150] In some embodiments, an etching stopper layer can be fabricated on the substrate, and the etching stopper layer can easily accurately control the dimensions of the electrode layer (e.g., the first electrode layer or the second electrode layer), and the etching stopper layer can further prevent the subsequent etching process from damaging the substrate. Specifically, the etching stopper layer can be fabricated on the substrate by a method such as chemical vapor deposition (CVD) or thermal oxidation. In some embodiments, 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. In some embodiments, the etching stopper layer can be removed by photolithography and etching processes to obtain a bone conduction acoustic transmission device.

[0151] In some embodiments, the size, shape, and position of the mass element 740 and the position, shape, and size of the piezoelectric layer can be changed to improve the output electrical signal of the bone conduction acoustic transmission device 700. In some embodiments, the shape, material, and size of the suspension membrane structure 730 can be changed to improve the sound pressure output effect of the bone conduction acoustic transmission device 700. Here, the first electrode layer 721, the second electrode layer 723, and the piezoelectric layer 722 of the acoustic transducer unit 720 and the first electrode layer 521, the second electrode layer 523, and the piezoelectric layer 522 of the acoustic transducer unit 520 in FIG. 5 are similar in structure and parameters, the suspension membrane structure 730 and the suspension membrane structure 530 are similar in structure and parameters, and the lead structure 7200 and the lead structure 5200 are similar in structure.

[0152] In some embodiments, the acoustic transducer unit 720 further includes a lead structure 7200, which transmits the electrical signals collected by the electrode rings (e.g., the first electrode layer 721 and the second electrode layer 723) to a subsequent circuit. In some embodiments, the first electrode layer 721 and the second electrode layer 723 are connected to the base structure 710 by the lead structure 7200. Specifically, the lead structure 7200 includes a first lead and a second lead, the first lead having one end connected to the first electrode layer 721 and the other end connected to the base structure, and the second lead having one end connected to the second electrode layer 721 and the other end connected to the base structure.

[0153] In some embodiments, by adjusting the shape, dimensions (e.g., length, width, and thickness), and material of the lead structure 7200, the equivalent stiffness and equivalent quality of the bone conduction acoustic transmission device 700 can be adjusted, the output electrical signal of the bone conduction acoustic transmission device 700 can be improved, and the sensitivity of the bone conduction acoustic transmission device 500 can be improved.

[0154] In some embodiments, the lead structure 7200 may include straight lines, broken lines, and curved lines. For example, as shown in FIGS. 31A-31C, the lead structure 7200 is straight. For example, as shown in FIG. 33A, the lead structure 7200 is curved. For example, as shown in FIG. 33B, the lead structure 7200 is broken lines. In some embodiments, the width of the lead structure 7200 may be between 10 μm and 100 μm. In some embodiments, the width is between 15 μm and 90 μm. In some embodiments, the width is between 20 μm and 80 μm.

[0155] FIG. 34 is a schematic diagram of a lead structure of another bone conduction acoustic transmission device according to some embodiments of the present application. In some embodiments, as shown in FIG. 34, the first electrode layer 721 is connected to a pad 7210 by a lead structure 7200. The pad 7210 may be located on the upper surface, lower surface, or side surface of the base structure 710, and as shown in FIG. 34, the pad 7210 may be located on the upper surface of the base structure 710, and guides an electrical signal between the acoustic transducer unit 720 and the housing, the lead structure 7200, etc. By connecting the first electrode layer 721 to the pad 7210 by the lead structure 7200, the electrical signal between the acoustic transducer unit 720 and the housing and the lead structure 7200 can be reduced, the parasitic capacitance can be reduced, and the sensitivity of the bone conduction acoustic transmission device 700 can be improved. In some embodiments, the pad 7210 can be circular, elliptical, triangular, polygonal, irregular, or the like. For a more detailed description of the pad 7210, please refer to the description of the pad 5210 in FIG. 5, and the description will be omitted here.

[0156] The first electrode layer 721, the second electrode layer 723, and the piezoelectric layer 722 of the acoustic transducer unit 720 in Figure 7 are similar in structure and parameters to the first electrode layer 521, the second electrode layer 523, and the piezoelectric layer 522 of the acoustic transducer unit 520 in Figure 5, the suspension membrane structure 730 and the suspension membrane structure 530 are similar in structure and parameters, etc., and the lead structure 7200 and the lead structure 5200 are similar in structure, for specific details, please refer to the related explanation in Figure 5, and will not be further described in this specification.

[0157] The structures in one or more of the above-mentioned embodiments may be combined with each other. For example, the vibration unit may include a suspension membrane structure and a mass unit, and the suspension membrane structure includes at least one hole. Specifically, as shown in FIG. 35 and FIG. 36.

[0158] FIG. 35 is a schematic diagram of a bone conduction sound transmission device according to some embodiments of the present application. FIG. 36 is a cross-sectional view of a partial structure of the bone conduction sound transmission device shown in FIG. 35. As shown in FIGS. 35 and 36, the bone conduction sound transmission device 3500 may include a base structure 3510 and a laminated structure, and at least a part of the laminated structure is connected to the base structure 3510. In some embodiments, the base structure 3510 may be a hollow frame structure, and a part of the laminated structure may be located in the hollow part of the frame structure. Note that the frame structure is not limited to the rectangular parallelepiped shape shown in FIG. 35, and in some embodiments, the frame structure may be a regular or irregular structure such as a pyramid truncated pyramid or a cylinder.

[0159] In some embodiments, the laminated structure may include an acoustic transducer unit 3520 and a vibration unit. As shown in FIG. 35, the vibration unit includes a suspension membrane structure 3530, which is connected to and fixed to the base structure 3510 by its periphery, and a central region of the suspension membrane structure 3530 is suspended in the hollow portion of the base structure 3510. In some embodiments, the suspension membrane structure 3530 may be located on the upper or lower surface of the base structure 3510. In some embodiments, the periphery of the suspension membrane structure 3530 may be connected to the inner wall of the hollow portion of the base structure 3510.

[0160] In some embodiments, the suspension membrane structure 3530 may include at least one elastic layer. The elastic layer may be a membrane-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, monocrystalline silicon, polycrystalline silicon, and the like. In some embodiments, the suspension membrane structure 3530 may include a plurality of holes 35300, and the plurality of holes 35300 are distributed along the circumferential direction (e.g., the outer circumferential direction and / or the inner circumferential direction) of the acoustic transducer unit 3520 centered on the center of the acoustic transducer unit 3520. The suspension membrane structure 3530 and the suspension membrane structure 530 have similar structures and parameters, and the relevant contents of FIG. 5 may be referred to in detail, and will not be further described in this specification.

[0161] In some embodiments, the acoustic transducer unit 3520 may be located on the upper or lower surface of the suspension membrane structure 3530. For example, as shown in FIG. 35 to FIG. 36, the acoustic transducer unit 3520 may be located on the upper surface of the suspension membrane structure 3530. With reference to FIG. 35 and FIG. 36, in some embodiments, the acoustic transducer unit 3520 may include a first electrode layer 3521, a piezoelectric layer 3522, and a second electrode layer 3523 that are installed in order from top to bottom, and the positions of the first electrode layer 3521 and the second electrode layer 3523 may be reversed. The similarities in structure and parameters between the acoustic transducer unit 3520 and the acoustic transducer unit 520 or the acoustic transducer unit 720 may be referred to in particular in the relevant contents of FIG. 5 or FIG. 7, and will not be further described in this specification.

[0162] In some embodiments, the vibration unit may further include a mass element 3540 (not shown in FIG. 35), which may be located on the upper or lower surface of the suspension membrane structure 3530. For example, as shown in FIG. 36, the mass element 3540 may be located on the lower surface of the suspension membrane structure 3530. For the similarity of the structures and parameters of the mass element 3540 and the mass element 740, please refer to the relevant contents of FIG. 7 in particular, and will not be further described in this specification.

[0163] Based on one or more of the above-mentioned embodiments, the resonance frequency curves of a bone conduction sound transmission device in which multiple circular holes are provided in the suspension membrane structure and a bone conduction sound transmission device in which a mass element is provided below the suspension membrane structure are described below with reference to Figures 37 and 38. Note that the structural configuration of the bone conduction sound transmission device corresponding to Figures 37 and 38 is only for illustrating that the resonance frequency of the bone conduction sound transmission device can be adjusted by providing holes and a mass element in the suspension membrane structure, and does not limit the scope of protection of the present application.

[0164] FIG. 37 is a resonance frequency curve of a bone conduction sound transmission device according to some embodiments of the present application. FIG. 38 is a resonance frequency curve of another bone conduction sound transmission device according to some embodiments of the present application. The resonance frequency curve is a frequency response curve. The bone conduction sound transmission device corresponding to the resonance frequency curve in FIG. 37 is a circular structure surrounded by a circular suspension membrane structure and a plurality of circular through-holes in FIG. 28. The number of holes is 2 to 18, and the holes are distributed in a circle surrounded by one or two circles, the radius of the holes is 20 μm to 300 μm, and the radius of the circle surrounded by the holes is 300 μm to 700 μm. The suspension membrane structure has a thickness of 0.5 μm to 10 μm, a circular shape, and a radius of 500 μm to 1500 μm. The acoustic conversion unit is a circular closed ring, with an inner diameter of 100 μm to 700 μm and an outer diameter of 110 μm to 710 μm. The bone conduction acoustic transmission device corresponding to the resonant frequency curve in Figure 38 has a structure of a circular suspension membrane structure and a circular mass element in Figure 31A, the mass elements are 1 to 3 in number, are cylindrical in shape, have a thickness of 20 μm to 400 μm, and the radial dimension of the cross section perpendicular to the thickness direction of the mass element is 100 μm to 700 μm, the mass element and the acoustic conversion unit are installed coaxially, the suspension membrane structure has a thickness of 0.5 μm to 10 μm, is circular in shape, and has a radial dimension of 500 μm to 1500 μm, and the acoustic conversion unit is a circular closed ring with an inner diameter dimension of 100 μm to 700 μm and an outer diameter dimension of 110 μm to 710 μm.

[0165] As can be seen from Fig. 37, the resonant frequency ranges from 2 kHz to 5 kHz (with a peak at 3.8 kHz), and as can be seen from Fig. 38, the resonant frequency ranges from 3 kHz to 5.5 kHz (with a peak at 4.5 kHz). By adjusting the number, size, and distribution position of the holes, and the size, shape, position, and weight of the mass element, the resonant frequency of the bone conduction acoustic transmission device is adjusted to within 3 kHz to 4.5 kHz, and further the output electrical signal of the bone conduction acoustic transmission device is adjusted to improve the sensitivity of the bone conduction acoustic transmission device.

[0166] FIG. 8 is a schematic diagram of a bone conduction sound transmission device according to some embodiments of the present application. FIG. 9 is a cross-sectional view of the bone conduction sound transmission device shown in FIG. 8 along CC. As shown in FIG. 8, the base structure 810 is a rectangular parallelepiped frame structure. In some embodiments, the inside of the base structure 810 may include a hollow portion for disposing the sound conversion unit 820 and the vibration unit. In some embodiments, the shape of the hollow portion may be other regular or irregular shapes such as a circle, a square (e.g., a rectangle, a parallelogram), a pentagon, a hexagon, a heptagon, an octagon, etc. In some embodiments, the dimension of one side of the rectangular cavity may be 0.8 mm to 2 mm. Preferably, the dimension of one side of the rectangular cavity may be 1 mm to 1.5 mm. In some embodiments, the vibration unit may include four support arms 830 and a mass element 840, and one end of each of the four support arms 830 is connected to the top surface, bottom surface, or a sidewall of the hollow portion of the base structure 810, and the other end is connected to the top surface, bottom surface, or a circumferential sidewall of the mass element 840. In some embodiments, the mass element 840 may protrude upward and / or downward relative to the support arms 830. For example, when the ends of the four support arms 830 are connected to the top surface of the mass element 840, the mass element 840 may protrude downward relative to the support arms 830. For example, when the ends of the four support arms 830 are connected to the bottom surface of the mass element 840, the mass element 840 may protrude upward relative to the support arms 830. For example, when the ends of the four support arms 830 are connected to the circumferential sidewall of the mass element 840, the mass element 840 may protrude upward and downward relative to the support arms 830. In some embodiments, support arm 830 is trapezoidal in shape, with a narrower end of support arm 830 connected to mass element 840 and a wider end of support arm 830 connected to base structure 810 .

[0167] In some embodiments, the support arm 830 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, silicon dioxide, silicon nitride, gallium nitride, zinc oxide, silicon carbide, etc. In some embodiments, the materials of different elastic layers of the support arm 830 may be the same or different. Furthermore, the bone conduction acoustic transmission device 800 may include an acoustic transducer unit 820. The acoustic transducer unit 820 may include a first electrode layer 821, a piezoelectric layer 822, and a second electrode layer 823 arranged in order from top to bottom, and the first electrode layer 821 or the second electrode layer 823 is connected to the upper surface or the lower surface of the support arm 830 (e.g., the elastic layer). In some embodiments, when the support arm 830 is a plurality of elastic layers, the acoustic transducer unit 820 may be located between the plurality of elastic layers. The piezoelectric layer 822 can generate a voltage (potential difference) due to the action of 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 resonance 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 piezoelectric layer 822) and the vibration unit (e.g., the support arm 830) may be adjusted. In some embodiments, the acoustic transducer unit 820 may include a bonding wire electrode layer (PAD layer), which may be located on the first electrode layer 821 and the second electrode layer 823, and connects the first electrode layer 821 and the second electrode layer 823 to an external circuit in the manner of an external bonding wire (e.g., gold wire, aluminum wire, etc.), thereby outputting 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 may include copper foil, titanium, copper, etc. In some embodiments, the thickness of the bonding wire electrode layer may be 100 nm to 200 nm. Preferably, the thickness of the bonding wire electrode layer may be 150 nm to 200 nm.In some embodiments, the acoustic transducer unit 820 may further include a seed layer, and the seed layer may be located between the second electrode layer 823 and the support arm 830. In some embodiments, the material of the seed layer may be the same as the material of the piezoelectric layer 822. For example, if the material of the piezoelectric layer 822 is AlN, the material of the seed layer is also AlN. In some embodiments, the material of the seed layer may be different from the material of the piezoelectric layer 822. Note that 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, and may be 4000 Hz to 5000 Hz or 2300 Hz to 3300 Hz, etc., and the specific frequency range may be adjusted according to the actual situation. In addition, 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 seed layer may be located between the mass element 840 and the support arm 830.

[0168] In some embodiments, the mass element 840 may have a single layer structure or a multi-layer structure. In some embodiments, the mass element 840 has a multi-layer structure, and the number of layers of the mass element 840, the material corresponding to the structure of each layer, and the parameters may be the same as or different from those of the elastic layer and the acoustic transducer unit 820 of the support arm 830. In some embodiments, the shape of the mass element 840 may be a regular or irregular shape, such as a circle, a semicircle, an ellipse, a triangle, a square, a pentagon, a hexagon, a heptagon, an octagon, and the like. In some embodiments, the thickness of the mass element 840 may be the same as or different from the total thickness of the support arm 830 and the acoustic transducer unit 820. For the material and dimensions when the mass element 840 has a multi-layer structure, reference may be made to the elastic layer and the acoustic transducer unit 820 of the support arm 830, and the description thereof will be omitted in this specification. In addition, the material and parameters of each layer structure of the elastic layer and the acoustic transducer unit 820 may be applied to the bone conduction acoustic transmission device shown in FIG. 1, FIG. 3, FIG. 4, FIG. 5, and FIG. 7.

[0169] In some embodiments, the acoustic transducer unit 820 may include at least an effective acoustic transducer unit. The effective acoustic transducer unit is a part of the structure of the acoustic transducer unit that finally outputs an electric signal. For example, if the first electrode layer 821, the piezoelectric layer 822, and the second electrode layer 823 have the same shape and area and partially cover the support arm 830 (elastic layer), the first electrode layer 821, the piezoelectric layer 822, and the second electrode layer 823 are effective acoustic transducer units. Also, for example, if the first electrode layer 821 and the 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 piezoelectric layer 822, and the part of the second electrode layer 823 corresponding to the first electrode layer 821 constitute an effective acoustic transducer unit. Further, for example, when the first electrode layer 821 partially covers the support arm 830, and the 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 piezoelectric layer 822 corresponding to the first electrode layer 821, and the portion of the second electrode layer 823 corresponding to the first electrode layer 821 constitute an effective acoustic transduction unit. Further, for example, when the first electrode layer 821, the piezoelectric layer 822, and the second electrode layer 823 completely cover the support arm 830, but the first electrode layer 821 is divided into a plurality of individual electrodes by providing an insulating channel (e.g., electrode insulating channel 8200) in the first electrode layer 821, the individual electrode portions that output electrical signals in the first electrode layer 821 and the corresponding piezoelectric layer 822 and second electrode layer 823 portions are effective acoustic transduction units. The individual electrode regions in the first electrode layer 821 that do not output an electrical signal, the piezoelectric layer 822 corresponding to the individual electrodes and insulating channels in the first electrode layer 821 that do not output an electrical signal, and the regions in the second electrode layer 823 do not provide electrical signals and mainly provide mechanical action. To improve the signal-to-noise ratio of the bone conduction acoustic transmission device 800, an effective acoustic conversion unit may be located in the vicinity of the mass element 840 of the support arm 830 or in the vicinity of the connection between the support arm 830 and the base structure 810. Preferably, the effective acoustic conversion unit is located in the vicinity of the mass element 840 of the support arm 830.In some embodiments, when the effective acoustic transducer unit is located at a location of the support arm 830 adjacent to the mass element 840 or adjacent to the connection of the support arm 830 with the base structure 810, 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 is between 5% and 40%. Preferably, 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 is between 10% and 35%. More preferably, 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 is between 15% and 20%.

[0170] 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, 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 in 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 in the middle region of the support arm 830. In some embodiments, when the acoustic transducer unit 820 completely or almost completely covers the upper or lower surface of the support arm 830, an electrode insulating channel 8200 may be provided in the first electrode layer 821 to improve the signal-to-noise ratio of the bone conduction acoustic transmission device 800, and the electrode insulating channel 8200 divides the first electrode layer 821 into two parts, so that one part of the first electrode layer 821 is close to the mass element 840 and the other part of the first electrode layer 821 is close to the connection point between the support arm 830 and the base structure 810. The part of the first electrode layer 821 that outputs an electric signal, the corresponding piezoelectric layer 822, and the second electrode layer 823 are an effective acoustic transducer unit. In some embodiments, the electrode insulating channel 8200 may be a straight line extending along the width direction of the support arm 830. In some embodiments, the width of the electrode insulating channel 8200 may be 2 μm to 20 μm. Preferably, the width of the electrode insulating channel 8200 may be between 4 μm and 10 μm.

[0171] The electrode insulating channel 8200 is not limited to a straight line extending along the width direction of the support arm 830, and may be a curved line, a bent line, a wavy line, etc. Also, the electrode insulating channel 8200, for example, the electrode insulating channel 8201 shown in Fig. 10, does not have to extend along the width direction of the support arm 830, and the electrode insulating channel 8200 may be capable of dividing the acoustic conversion unit 820 into a plurality of parts, and is not further limited in this specification.

[0172] As shown in FIG. 10, when some structure of the acoustic transducer unit 820 (e.g., the acoustic transducer unit between the electrode insulation channel 8201 and the mass element 840 in FIG. 10) 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. Taking the first electrode layer 821 as an example, the electrode insulating channel 8201 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 adjacent to the mass element 840 of the acoustic transducer unit 820, the electrode insulating channel 8201 may divide a part of the first electrode layer 821 adjacent to the connection point between the support arm 830 and the base structure 810 (a part located at the edge of the support arm 830 in the first electrode layer 821 shown in the figure), and the part of the part of the part connected to or adjacent to the mass element 840 of the acoustic transducer unit 820 is electrically connected to the processing unit of the bone conduction acoustic transmission device 800. In some embodiments, the width of the electrode lead may be 4 μm to 20 μm. Preferably, the width of the electrode lead may be 4 μm to 10 μm. In some embodiments, the electrode lead may be located at any position in the width direction of the support arm 830, for example, the electrode lead may be located at a position close to the center or edge of the support arm 830 in the width direction. Preferably, the electrode lead may be located at a position close to the edge of the support arm 830 in the width direction. By providing the electrode lead 8211, the use of a conductive wire in the acoustic transducer unit 820 can be avoided, simplifying the structure and facilitating subsequent manufacturing and assembly.

[0173] Considering that the surface of the piezoelectric material of the piezoelectric layer 822 may be roughened by etching in the area close to the edge of the support arm 830, which may reduce the quality of the piezoelectric material, in some embodiments, when the area of ​​the piezoelectric layer 822 is the same as the area of ​​the second electrode layer 823, the area of ​​the piezoelectric layer 822 is made smaller than the area of ​​the first electrode layer 821 so that the first electrode layer 821 is located in the high quality piezoelectric material area, and the edge area of ​​the first electrode layer 821 avoids the edge area of ​​the piezoelectric layer 822, and an electrode shrinkage channel (not shown) is formed between the first electrode layer 821 and the piezoelectric layer 822. By setting the electrode shrinkage channel, the first electrode layer 821 and the second electrode layer 823 avoid the low quality area of ​​the edge of the piezoelectric layer 822, and as a result, the signal-to-noise ratio of the bone conduction acoustic transmission device can be improved. In some embodiments, the width of the electrode shrinkage channel may be 2 μm to 20 μm. Preferably, the width of the electrode shrinkage channel may be 2 μm to 10 μm.

[0174] As shown in FIG. 10, for example, in the case where the mass element 840 protrudes downward relative to the support arm 830, the acoustic transducer unit 820 may further include an extension region 8210 extending along the longitudinal direction of the support arm 830, and the extension region 8210 is located on the upper surface of the mass element 840. In some embodiments, an electrode insulating channel 8201 is provided at the edge position of the extension region 8210 located on the upper surface of the mass element 840, thereby preventing the occurrence of a problem of excessive stress concentration on the support arm 830 and improving the stability of the support arm 830. In some embodiments, the length of the extension region 8210 is greater than the width of the support arm 830. Here, the length of the extension region 8210 corresponds to the width along the support arm 830. In some embodiments, the length of the extension region 8210 is 4 μm to 30 μm. Preferably, the length of the extension region 8210 is 4 μm to 15 μm. In some embodiments, the length of extension region 8210 in mass element 840 is 1.2 to 2 times the width of the connection between support arm 830 and an edge of mass element 840. Preferably, the length of extension region 8210 in mass element 840 is 1.2 to 1.5 times the width of the connection between support arm 830 and an edge of mass element 840.

[0175] FIG. 11 is a schematic diagram of a bone conduction sound transmission device according to some embodiments of the present application. The overall structure of the bone conduction sound transmission device 1000 shown in FIG. 11 is almost the same as the overall structure of the bone conduction sound transmission device 800 shown in FIG. 8, but differs in that the shape of the support arm is different. As shown in FIG. 11, the base structure 1010 is a rectangular parallelepiped frame structure. In some embodiments, the inside of the base structure 1010 may include a hollow portion for suspending the acoustic conversion unit and the vibration unit. In some embodiments, the shape of the hollow portion may be other regular or irregular shapes such as a circle, a square (e.g., a rectangle, a parallelogram), a pentagon, a hexagon, a heptagon, an octagon, etc. In some embodiments, the vibration unit may include four support arms 1030 and a mass element 1040, with one end of each of the four support arms 1030 connected to the top, bottom, or sidewall of the hollow portion of the base structure 1010, and the other end connected to the top, bottom, or circumferential sidewall of the mass element 1040. In some embodiments, the mass element 1040 may protrude upward and / or downward relative to the support arms 1030. For example, if the ends of the four support arms 1030 are connected to the top surface of the mass element 1040, the mass element 1040 may protrude downward relative to the support arms 1030. Also, for example, if the ends of the four support arms 1030 are connected to the bottom surface of the mass element 1040, the mass element 1040 may protrude upward relative to the support arms 1030. Further for example, if the ends of the four support arms 1030 are connected to the circumferential sidewalls of the mass element 1040, the mass element 1040 may protrude upwards and downwards relative to the support arms 1030. In some embodiments, the support arms 1030 are rectangular in shape and have one end connected to the mass element 1040 and the other end connected to the base structure 1010.

[0176] In some embodiments, in order to improve the signal-to-noise ratio of the bone conduction acoustic transmission device 1000, the effective acoustic transducer unit may be located in the vicinity of the mass element 1040 of the support arm 1030 or in the vicinity of the connection between the support arm 1030 and the base structure 1010. Preferably, the effective acoustic transducer unit is located in the vicinity of the mass element 1040 of the support arm 1030. In some embodiments, when the effective acoustic transducer unit is located in the vicinity of the mass element 1040 of the support arm 1030 or in the vicinity of the connection between the support arm 1030 and the base structure 1010, the ratio of the area of ​​the support arm 1030 covered by the effective acoustic transducer unit to the area of ​​the support arm 1030 is between 5% and 40%. Preferably, the ratio of the area of ​​the support arm 1030 covered by the effective acoustic transducer unit to the area of ​​the support arm 1030 is between 10% and 35%. More preferably, the ratio of the area of ​​the support arm 1030 covered by the effective acoustic transducer units 1020 to the area of ​​the support arm 1030 is 15% to 20%.

[0177] The signal-to-noise ratio of the bone conduction acoustic transmission device 1000 is positively correlated with the strength of the output electrical signal, and when the laminated structure moves relative to the base structure, the deformation stress at the connection point between the support arm 1030 and the mass element 1040 and the connection point between the support arm 1030 and the base structure 1010 is greater than the deformation stress in the middle region of the support arm 1030, and accordingly, the strength of the output voltage at the connection point between the support arm 1030 and the mass element 1040 and the connection point between the support arm 1030 and the base structure 1010 is also greater than the strength of the output voltage in the middle region of the support arm 1030. In some embodiments, when the acoustic transducer unit completely or almost completely covers the upper or lower surface of the support arm 1030, an electrode insulating channel 1050 may be provided in the first electrode layer to improve the signal-to-noise ratio of the bone conduction acoustic transmission device 1000, and the electrode insulating channel 1050 divides the first electrode layer into two parts, such that one part of the first electrode layer is close to the mass element 1040 and the other part of the first electrode layer is close to the connection point between the support arm 1030 and the base structure 1010. In some embodiments, the electrode insulating channel 1050 may be a straight line extending along the width direction of the support arm 1030. In some embodiments, the width of the electrode insulating channel 1050 may be 2 μm to 20 μm. Preferably, the width of the electrode insulating channel 1050 may be 4 μm to 10 μm.

[0178] The electrode insulating channel 1050 is not limited to a straight line extending along the width direction of the support arm 1030, and may be a curved line, a bent line, a wavy line, etc. Also, the electrode insulating channel 1050, for example, the electrode insulating channel 11200 shown in Fig. 12, does not have to extend along the width direction of the support arm 1030, and the electrode insulating channel may be any channel capable of dividing the acoustic transducer unit into a plurality of parts, and is not further limited in this specification.

[0179] As shown in FIG. 12, when some structure of the acoustic conversion unit (e.g., the acoustic conversion unit between the electrode insulation channel 11200 and the mass element 1140 in FIG. 12) is installed in a position close to the mass element 1140 of the support arm 1130, the first electrode layer 1121 and / or the second electrode layer may further include an electrode lead. Taking the first electrode layer 1121 as an example, the electrode insulation channel 11200 divides the first electrode layer 1121 into two parts, a part of the first electrode layer 1121 connected to or close to the mass element 1140, and another part of the first electrode layer 1121 close to the connection point between the support arm 1130 and the base structure 1110, and in order to output a voltage close to the mass element 1140 of the acoustic conversion unit, the electrode insulation channel 11200 may divide a portion of the first electrode layer 1121 close to the connection point between the support arm 1130 and the base structure 1110 (a portion located at the edge of the support arm 1130 in the first electrode layer 1121 shown in the figure), and the portion of the region electrically connects the portion connected to or close to the mass element 1140 in the acoustic conversion unit to the processing unit of the bone conduction acoustic transmission device. In some embodiments, the width of the electrode lead may be 4 μm to 20 μm. Preferably, the width of the electrode lead may be 4 μm to 10 μm. In some embodiments, the electrode lead may be located at any position in the width direction of the support arm 1130, for example, the electrode lead may be located at a position close to the center or edge of the support arm 1130 in the width direction. Preferably, the electrode lead may be located at a position close to the edge of the support arm 1130 in the width direction. By providing the electrode lead, the use of a conductive wire in the acoustic transducer unit can be avoided, simplifying the structure and facilitating subsequent manufacturing and assembly.

[0180] As shown in FIG. 13, the surface of the piezoelectric material of the piezoelectric layer is roughened by etching in the area close to the edge of the support arm, reducing the quality of the piezoelectric material. In some embodiments, when the area of ​​the piezoelectric layer is the same as the area of ​​the second electrode layer, the area of ​​the piezoelectric layer is made smaller than the area of ​​the first electrode layer 1121 in order to position the first electrode layer 1121 in the piezoelectric material area where the quality of the piezoelectric layer is high, so that the edge area of ​​the first electrode layer 1121 avoids the edge area of ​​the piezoelectric layer, and an electrode shrinkage channel 11212 is formed between the first electrode layer 1121 and the piezoelectric layer. By providing the electrode shrinkage channel 11212, the first electrode layer and the second electrode layer avoid the area of ​​the edge of the piezoelectric layer where the quality is low, and as a result, the signal-to-noise ratio of the bone conduction acoustic transmission device can be improved. In some embodiments, the width of the electrode shrinkage channel 11212 may be 2 μm to 20 μm. Preferably, the width of the electrode shrinkage channel 11212 may be 2 μm to 10 μm.

[0181] As shown in FIG. 14, in some embodiments, the acoustic transducer unit may further include an extension region 11210 extending along the longitudinal direction of the support arm 1130, for example, when the mass element 1140 protrudes downward relative to the support arm 1130, and the extension region 11210 is located on the upper surface of the mass element 1140. In some embodiments, an electrode insulating channel 11200 is provided at the edge position of the extension region 11210 located on the upper surface of the mass element 1140, thereby preventing the occurrence of a problem of excessive stress concentration on the support arm 1130 and improving the stability of the support arm 1130. In some embodiments, the length of the extension region 11210 is greater than the width of the support arm 1130. Here, the length of the extension region 11210 corresponds to the width of the support arm 1130. In some embodiments, the length of the extension region 11210 is 4 μm to 30 μm. Preferably, the length of the extension region 11210 is 4 μm to 15 μm. In some embodiments, the length of the extension region 11210 in the mass element 1140 is 1.2 to 2 times the width of the connection portion between the support arm 1130 and the edge of the mass element 1140. Preferably, the length of the extension region 11210 in the mass element 1140 is 1.2 to 1.5 times the width of the connection portion between the support arm 1130 and the edge of the mass element 1140. For parameters such as materials and dimensions of the structures of the acoustic conversion unit, the first electrode layer, the second electrode layer, the piezoelectric layer, the vibration unit, the mass element 1140, etc. in this embodiment, the contents of Figures 8 to 10 can be referred to, and description thereof will be omitted in this specification.

[0182] FIG. 15 is a schematic diagram of another bone conduction sound transmission device according to some embodiments of the present application. The structure of the bone conduction sound transmission device 1500 shown in FIG. 15 is almost the same as the structure of the bone conduction sound transmission device 800 shown in FIG. 8, but differs in that the connection method between the support arm and the base structure is different. As shown in FIG. 15, the base structure 1510 is a rectangular parallelepiped frame structure. In some embodiments, the inside of the base structure 1510 may include a hollow portion for suspending the acoustic conversion unit and the vibration unit. In some embodiments, the vibration unit may include four support arms 1530 and a mass element 1540, and one end of each of the four support arms 1530 is connected to the upper surface, lower surface, or a side wall of the base structure 1510 where the hollow portion is located, and the other end is connected to the upper surface, lower surface, or a side wall in the circumferential direction of the mass element 1540. In some embodiments, the mass element 1540 may protrude upward and / or downward with respect to the support arm 1530. For example, if the ends of the four support arms 1530 are connected to a top surface of the mass element 1540, the mass element 1540 may project downward relative to the support arm 1530. For example, if the ends of the four support arms 1530 are connected to a bottom surface of the mass element 1540, the mass element 1540 may project upward relative to the support arm 1530. For example, if the ends of the four support arms 1530 are connected to a circumferential sidewall of the mass element 1540, the mass element 1540 may project upward and downward relative to the support arm 1530. In some embodiments, the support arm 1530 is trapezoidal in shape, with the wider end of the support arm 1530 connected to the mass element 1540 and the narrower end of the support arm 1530 connected to the base structure 1510. In addition, the parameters such as the structure, dimensions, thickness, etc. of components such as the acoustic conversion unit 820, the first electrode layer 821, the second electrode layer 823, the piezoelectric layer 822, the vibration unit, the mass element 840, the extension area 8210, the electrode insulating channel 8201, the electrode contraction channel, and the electrode insulating channel 8200 in Figures 8 to 10 can be applied to the bone conduction acoustic transmission device 1500, and will not be further described in this specification.

[0183] FIG. 16 is a schematic diagram of a bone conduction sound transmission device according to some embodiments of the present application. The structure of the bone conduction sound transmission device 1600 shown in FIG. 16 is almost the same as the structure of the bone conduction sound transmission device 800 shown in FIG. 8, but differs in that the structure of the support arm 1630 of the bone conduction sound transmission device 1600 is different from the structure of the support arm 830 of the bone conduction sound transmission device 800. In some embodiments, the inside of the base structure 1610 may include a hollow portion for suspending the acoustic conversion unit and the vibration unit. In some embodiments, the vibration unit may include four support arms 1630 and a mass element 1640, and one end of each of the four support arms 1630 is connected to the upper surface, lower surface, or a side wall of the base structure 1610 where the hollow portion is located, and the other end is connected to the upper surface, lower surface, or a side wall in the circumferential direction of the mass element 1640. In some embodiments, the mass element 1640 may protrude upward and / or downward with respect to the support arm 1630. For example, if the ends of the four support arms 1630 are connected to an upper surface of the mass element 1640, the mass element 1640 may project downward relative to the support arm 1630. For example, if the ends of the four support arms 1630 are connected to a lower surface of the mass element 1640, the mass element 1640 may project upward relative to the support arm 1630. For example, if the ends of the four support arms 1630 are connected to a circumferential sidewall of the mass element 1640, the mass element 1640 may project upward and downward relative to the support arm 1630. In some embodiments, the upper surface of the mass element 1640 is coplanar with the upper surface of the support arm 1630 and / or the lower surface of the mass element 1640 is coplanar with the lower surface of the support arm 1630. In some embodiments, the shape of the support arm 1630 may be a generally L-shaped structure. 16, the support arm 1630 may include a first support arm 1631 and a second support arm 1632, where one end of the first support arm 1631 is connected to one end of the second support arm 1632, and the first support arm 1631 and the second support arm 1632 have an included angle. In some embodiments, the included angle ranges from 75° to 105°.In some embodiments, the end of the first support arm 1631 away from the connection point between the first support arm 1631 and the second support arm 1632 is connected to the base structure 1610, and the end of the second support arm 1632 away from the connection point between the first support arm 1631 and the second support arm 1632 is connected to the upper surface, lower surface or peripheral side wall of the mass element 1640, thereby suspending the mass element 1640 in the hollow portion of the base structure 1610.

[0184] In some embodiments, the acoustic transducer unit may have a multi-layer structure and include structures such as a first electrode layer, a second electrode layer, a piezoelectric layer, an elastic layer, a seed layer, an electrode contraction channel, an electrode insulating channel, etc. For each layer structure of the acoustic transducer unit, mass element 1640, etc., reference may be made to the description of the acoustic transducer unit 820, the first electrode layer 821, the second electrode layer 823, the piezoelectric layer 822, the vibration unit, the mass element 840, the extension region 8210, the electrode insulating channel 8201, the electrode contraction channel, and the electrode insulating channel 8200 in Figures 8 to 10 of the specification of this application, and further description will not be made in this specification.

[0185] In some embodiments, the bone conduction acoustic transmission device according to any one of the embodiments above may further include a position limiting structure (not shown), and the position limiting structure is a plate-like structure. In some embodiments, the position limiting structure may be located in a hollow portion of the base structure, and the position limiting structure may be located above or below the laminated structure and installed facing the laminated structure. In some embodiments, when the base structure is a structure that penetrates vertically, the position limiting structure may be located at the top or bottom of the base structure. When the position limiting structure and the mass unit of the laminated structure are installed at a distance from each other and a large impact is received, the position limiting structure limits the amplitude of the mass unit of the laminated structure, thereby preventing the device from being damaged by strong vibration. In some embodiments, the position limiting structure may be a rigid structure (e.g., a position limiting block) or a structure having a certain elasticity (e.g., an elastic cushion, a shock-absorbing cantilever, or a structure in which a shock-absorbing support arm and a position limiting block are installed simultaneously, etc.).

[0186] The laminated structure has a natural frequency, and when the frequency of the external vibration signal is close to the natural frequency, the laminated structure generates a large amplitude and outputs a large electric signal. Therefore, the response of the bone conduction sound transmission device to the external vibration is expressed as a resonance peak occurring near the natural frequency. In some embodiments, the parameters of the laminated structure are changed to move the natural frequency of the laminated structure within the voice band range, thereby bringing the resonance peak of the bone conduction sound transmission device into the voice band range, and improving the response sensitivity of the bone conduction sound transmission device to vibration in the voice band (for example, the frequency range before the resonance peak). As shown in FIG. 17, the frequency corresponding to the resonance peak 1701 in the frequency response curve (solid curve in FIG. 17) in which the natural frequency of the laminated structure is advanced is lower than the frequency corresponding to the resonance peak 1702 in the frequency response curve (dashed curve in FIG. 17) in which the natural frequency of the laminated structure is not changed. For an external vibration signal whose frequency is lower than the frequency at which the resonance peak 1701 is located, the bone conduction sound transmission device corresponding to the solid curve has a higher sensitivity.

[0187] The displacement output equation of the laminated structure is as follows:

[0188]

number

[0189] where M is the mass of the laminate structure, R is the damping of the laminate structure, K is the elastic modulus of the laminate structure, F is the amplitude of the actuation force, and x a is the displacement of the laminated structure, w is the angular frequency of the external force, and w0 is the natural frequency of the laminated structure.

[0190]

number

[0191] If so, wM <Kw -1If the natural frequency w0 of the laminated structure is reduced (by increasing M, or decreasing K, or by increasing M and decreasing K), then |wM <Kw -1 | becomes smaller, and the corresponding displacement output x a If the frequency of the excitation force w=w0, then wM=Kw -1 When the natural frequency w0 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 w>w0, then wM>Kw -1 If the natural frequency w0 of the vibration-electrical signal conversion element is reduced (by increasing M, decreasing K, or increasing M and decreasing K), then |wM-Kw -1 | becomes larger and the corresponding displacement output x a becomes smaller.

[0192] As the resonance peak advances, a peak value appears in the voice band. When the bone conduction sound transmission device picks up the signal, there is too much signal in the resonance peak band, which reduces the call effect. In some embodiments, in order to improve the quality of the voice signal collected by the bone conduction sound transmission device, a damping structure layer may be installed on 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 1 / Q of the mechanical quality factor:

[0193]

number

[0194] In the formula, Q -1 is the inverse of the quality factor, also called the structural loss factor η, Δf is the frequency difference value f1-f2 at half the resonant amplitude (also called the 3 dB bandwidth), and f0 is the resonant frequency.

[0195] The relationship between the loss factor η of the laminated structure and the loss factor tan δ of the damping material is as follows:

[0196]

number

[0197] where X is a shear parameter, which is related to the thickness and material properties of each layer of the laminate structure, and Y is a stiffness parameter, which is related to the thickness and Young's modulus of each layer of the laminate structure.

[0198] As can be seen from Equation (6) and Equation (7), the loss factor η of the laminated structure can be adjusted to a suitable range by adjusting the material of the damping structure layer and the material of each layer of the laminated structure. As the damping of the damping structure layer of the laminated structure increases, the mechanical quality factor Q decreases and the corresponding 3 dB bandwidth increases. The damping of the damping structure layer is different in different stress (deformation) states, for example, the damping is large when the stress is high or the amplitude is large. Therefore, based on the feature that the amplitude of the laminated structure is small in the non-resonance region and the amplitude of the laminated structure is large in the resonance region, the damping structure layer can be increased to ensure that the sensitivity of the bone conduction microphone in the non-resonance region is not reduced, and the Q value of the resonance region can be reduced, and the frequency response of the bone conduction sound transmission device can be flattened in the entire frequency band. FIG. 18 is a frequency response curve diagram of a bone conduction sound transmission device having a damping structure layer and a bone conduction sound transmission device without a damping structure layer according to some embodiments of the present application. As shown in Figure 18, a frequency response curve 1802 of an electrical signal output by a bone conduction acoustic transmission device having an attenuation structure layer is flatter than a frequency response curve 1801 of an electrical signal output by a bone conduction acoustic transmission device not having an attenuation structure layer.

[0199] 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 surface and / or the lower surface of the laminated structure, or between the multi-layered structure of the laminated structure. In some embodiments, for macro-sized laminated structures and base structures, the damping structure layer may be directly bonded to the base structure or the surface of the laminated structure. In some embodiments, for MEMS devices, the damping structure layer may be connected to the laminated structure and base structure by a semiconductor process, such as deposition, spin coating, microassembly, etc. In some embodiments, the shape of the damping structure layer may be a regular shape, such as a circle, an ellipse, a triangle, a square, a hexagon, an octagon, etc. In some embodiments, the output effect of the electrical signal of the bone conduction acoustic transmission device may be improved by selecting the material, dimensions, thickness, etc. of the damping film.

[0200] In order to more clearly explain the damping structure layer, a cantilever type bone conduction sound transmission device (for example, 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. 19 is a cross-sectional view of a bone conduction sound transmission device according to some embodiments of the present application. As shown in FIG. 19, the bone conduction sound transmission device 1900 may include a base structure 1910, a laminated structure 1920, and a damping structure layer 1930. Furthermore, the laminated structure 1920 has one end connected to the upper surface of the base structure 1910 and the other end suspended in the hollow portion of the base structure 1910, and the damping structure layer 1930 is located on the upper surface of the laminated structure 1920. The area of ​​the damping structure layer 1930 may be larger than the area of ​​the laminated structure 1920, i.e., the damping structure layer 1930 may not only cover the top surface of the laminated structure 1920, but also cover the gap between the laminated structure 1920 and the base structure 1910. In some embodiments, at least a portion of the periphery of the damping structure layer 1930 may be fixed to the base structure 1910.

[0201] Fig. 20 is a cross-sectional view of a bone conduction sound transmission device according to some embodiments of the present application. As shown in Fig. 20, the bone conduction sound transmission device 2000 may include a base structure 2010, a laminated structure 2020, and two damping structure layers, the two damping structure layers including a first damping structure layer 2030 and a second damping structure layer 2040. Furthermore, the second damping structure layer 2040 is connected to the upper surface of the base structure 2010, the lower surface of the laminated structure 2020 is connected to the upper surface of the second damping structure layer 2030, one end of the laminated structure 2020 is suspended in the hollow part of the base structure 2010, and the first damping structure layer 2030 is connected to the upper surface of the laminated structure 2020. The area of ​​the first damping structure layer 2030 and / or the second damping structure layer 2040 is larger than the area of ​​the laminated structure 2020.

[0202] Fig. 21 is a cross-sectional view of a bone conduction sound transmission device according to some embodiments of the present application. As shown in Fig. 21, the bone conduction sound transmission device 2100 may include a base structure 2110, a laminated structure 2120, and a damping structure layer 2130. Furthermore, the damping structure layer 2130 is located on the lower surface of the base structure 2110. The laminated structure 2120 has a lower surface connected to an upper surface of the damping structure layer 2130, and one end is suspended in the hollow portion of the base structure 2110.

[0203] The position of the attenuation structure layer (for example, the attenuation structure layer 1930) is not limited to the upper surface and / or the lower surface of the laminated structure shown in the above-mentioned Figs. 19 to 21, and may be located between the multi-layered structure of the laminated structure. For example, the attenuation structure layer may be located between the elastic layer and the first electrode layer. Also, for example, the attenuation structure layer may be located between the first elastic layer and the second elastic layer. Furthermore, the attenuation structure layer is not limited to the above-mentioned cantilever type bone conduction acoustic transmission device, and may be applied to the bone conduction acoustic transmission devices shown in Figs. 5, 7, 8, 11, 15, and 16, and a description thereof will be omitted in this specification.

[0204] Although the basic concept has been described above, it is clear to those skilled in the art that the detailed disclosure above is merely provided as an example 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 therefore are within the spirit and scope of the exemplary embodiments of the present application.

[0205] Also, certain terms are used herein to describe embodiments of the present application. For example, "one embodiment," "an embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic associated with at least one embodiment of the present application. Thus, it is emphasized and understood that references to "one embodiment," "one embodiment," or "one alternative embodiment" more than once in various parts of this specification do not necessarily all refer to the same embodiment. Also, certain features, structures, or characteristics of one or more embodiments of the present application may be combined as appropriate.

[0206] Also, 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. Thus, 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. Any of the above hardware or software may be referred to as a "data block," "module," "engine," "unit," "assembly," or "system." Furthermore, 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.

[0207] Furthermore, unless expressly stated in the claims, the recitation order of the processing elements or sequences described herein, the use of alphanumeric characters, or the use of other designations, do not limit the order of the procedures and methods of the present application. While the above disclosure describes through various examples what are presently believed to be various useful embodiments of the invention, it will be understood that such details are merely illustrative and that the appended claims are not limited to the disclosed embodiments, but on the contrary are intended to cover all modifications and equivalent combinations within the spirit and scope of the embodiments of the present application. For example, the system assembly described above may be implemented by a hardware device, but may also be implemented as a software-only solution, for example, by installing the described system on an existing processing device or mobile device.

[0208] Similarly, in the foregoing description of embodiments of the present application, it will be appreciated that various features may be grouped together in a single embodiment, drawing, or description for the purpose of streamlining the present disclosure and facilitating an understanding of one or more embodiments of the present invention. This method of disclosure, however, should not be interpreted as reflecting an intention that the claimed subject matter requires more features than are recited in each claim. Indeed, an embodiment may include fewer than all features of a single embodiment disclosed above.

[0209] In some embodiments, numbers are used to describe the number of components and attributes, and the numbers describing such embodiments should be understood to be modified in some embodiments by the modifiers "about," "approximately," or "substantially." Unless otherwise specified, "about," "approximately," or "substantially" indicate that the value described by the number is allowed to vary by ±20%. Thus, in some embodiments, all numerical parameters used in the specification and claims are approximations that may vary depending on the characteristics required for a particular embodiment. In some embodiments, the numerical parameters should be calculated taking into account the number of significant digits stated and ordinary rounding techniques should be employed. In some embodiments, the numerical ranges and parameters used to determine the ranges are approximations; however, in specific embodiments, such numerical values ​​are set as precisely as possible.

[0210] All patents, patent applications, published patent applications, and other materials such as articles, books, specifications, publications, documents, etc. referenced in this application are incorporated herein by reference in their entirety, except for prosecution history documents that are inconsistent 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). In addition, if the explanations, definitions, and / or use of terms in the accompanying documents of this application are inconsistent or inconsistent with the content set forth in this application, the explanations, definitions, and / or use of terms in this application shall control.

[0211] Finally, it should be understood that the embodiments described herein are merely illustrative of the principles of the embodiments of the present application. Other variations are possible within the scope of the present application. Thus, by way of example, and not of limitation, alternative configurations of the embodiments of the present application may be considered consistent with the teachings of the present application. Thus, the embodiments of the present application are not limited to the embodiments expressly introduced and described herein. [Explanation of symbols]

[0212] 100, 300, 400, 500, 700, 3500, 800 Bone conduction acoustic transmission device 110, 310, 410, 510, 710, 3510, 810 base structure 140 Connection Base 120, 320, 420, 520, 720, 3520, 820 Acoustic conversion unit 130, 330, 430 vibration unit 131, 331 First elastic layer 132, 332 second elastic layer 121, 521, 721, 3521 First electrode layer 122, 322, 423, 522, 722, 3522 Piezoelectric layer 123, 523, 723, 3523 Second electrode layer 530, 730, 530, 730, 3530 Suspension membrane structure 740, 3540, 840 mass elements 321, 421 First electrode 323, 422 Second electrode 4210 First comb-shaped structure 4220 Second comb-like structure 5300, 35300 holes 5200, 7200 lead structure 5210, 7210 Pads 830 Support Arm 8200, 8201 Electrode isolation channel 8210 Extended area 11212 Electrode Contraction Channel 1930 Damping Structure Layer

Claims

1. A laminated structure formed of a vibration unit and an acoustic conversion unit; a base structure configured to support the laminated structure and physically connected to at least one side of the laminated structure; Including, The base structure is vibrated by an external vibration signal, the vibration unit is deformed in response to the vibration of the base structure, the acoustic conversion unit generates an electric signal based on the deformation of the vibration unit, and the bone conduction microphone has a resonance frequency of 2.5 kHz to 4.5 kHz; The vibration unit includes a suspension membrane structure, the suspension membrane structure is connected to the base structure by its periphery, and the acoustic transducer unit is located on the upper surface or the lower surface of the suspension membrane structure; The suspension membrane structure includes a plurality of holes, the plurality of holes being distributed along an outer circumferential direction and / or an inner circumferential direction of the acoustic transducer unit; The acoustic transducer unit includes at least an effective acoustic transducer unit, and a radial distance from an edge of the effective acoustic transducer unit to a center of the plurality of holes is 50 μm to 400 μm; A bone conduction microphone, wherein the acoustic transducer unit has an annular structure, and the effective inner diameter dimension of the acoustic transducer unit is 100 μm to 700 μm, or the effective outer diameter dimension of the acoustic transducer unit is 110 μm to 710 μm.

2. The bone conduction microphone of claim 1 , wherein the resonant frequency of the bone conduction microphone and the rigidity of the vibration unit are positively correlated, or the resonant frequency of the bone conduction microphone and the mass of the laminated structure are negatively correlated.

3. The bone conduction microphone according to claim 1 , wherein the acoustic transducer unit includes a first electrode layer, a piezoelectric layer and a second electrode layer arranged in order from top to bottom.

4. The bone conduction microphone according to claim 1 , wherein the plurality of holes are circular holes, and the radius of the circular holes is between 20 μm and 300 μm.

5. The bone conduction microphone according to claim 4 , wherein a shape surrounded by the plurality of holes coincides with a shape of the acoustic transducer unit.

6. 5. The bone conduction microphone according to claim 4, wherein the holes are distributed in a circle along the outer circumferential direction and / or the inner circumferential direction of the acoustic conversion unit, and the circle has a radius of 300 μm to 700 μm.

7. 5. The bone conduction microphone of claim 3, wherein the acoustic transducer unit is an annular structure, and the thickness of the suspension membrane structure in an inner region of the annular structure is greater than the thickness of the suspension membrane structure in an outer region of the annular structure.

8. 5. The bone conduction microphone according to claim 3, wherein the suspension membrane structure has a thickness of 0.5 μm to 10 μm.

9. A bone conduction microphone as described in claim 3, wherein the thickness of the first electrode layer is 80 nm to 250 nm, the thickness of the second electrode layer is 80 nm to 250 nm, or the thickness of the piezoelectric layer is 0.8 μm to 5 μm.

10. The bone conduction microphone of claim 3 or 4, wherein the vibration unit further includes a mass element, the mass element being a cylinder, the radius of a cross section perpendicular to the thickness direction of the mass element being 100 μm to 700 μm, or the thickness of the mass element being 20 μm to 400 μm.

11. The bone conduction microphone of claim 1 , wherein 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.

12. The bone conduction microphone of claim 1 , further comprising at least one damping layer covering an upper surface, a lower surface and / or an interior of the laminate structure.

Images