TWI853238B - Vibration sensor - Google Patents

Abstract

The embodiments of the present disclosure may disclose a vibration sensor, including a shell structure and an acoustic transducer, and at least part of the shell structure and the acoustic transducer forms an acoustic cavity; a vibration unit, configured to divide the acoustic cavity into a plurality of acoustic cavities containing a first acoustic cavity, and the acoustic cavity may be acoustically connected to the acoustic transducer; the vibration unit may include at least one elastic element and quality element, and the at least one elastic element and the quality element may locate in the acoustic cavity. The at least one elastic element may be distributed on the opposite two sides of the quality element in a first direction so that in the range below the target frequency, the response sensitivity of the vibration unit to the shell structure in the first direction is higher than that of the vibration unit to the shell structure in the second direction, and the second direction is perpendicular to the first direction.

Description

Vibration sensor

This application relates to the field of sensors, and in particular to a vibration sensor.

This application claims priority to the Chinese patent application No. 202110677119.2 filed on June 18, 2021, and the Chinese patent application No. 202121366390.6 filed on June 18, 2021, the entire contents of which are incorporated herein by reference.

A vibration sensor is an energy conversion device that converts vibration signals into electrical signals. In some cases, a vibration sensor can be used as a bone conduction microphone. In a bone conduction microphone, the vibration sensor can detect the vibration signal transmitted through the skin when a person speaks, and convert the vibration signal transmitted from the human skin into an electrical signal, thereby achieving the effect of sound transmission. A bone conduction microphone can reduce the interference of noise transmitted through the air in the external environment on the target sound source, achieving a better sound transmission effect. In actual application scenarios, vibration sensors (e.g., bone conduction microphones) may receive vibration signals other than the target sound source (e.g., vibration signals from the vibrating speakers in headphones, vibration signals from the headphones, etc.), thereby affecting the sound transmission effect of the vibration sensor.

Based on the above problems, this specification provides a vibration sensor that can be used to reduce the impact of non-target vibration signals, thereby improving the sound transmission effect of the vibration sensor on the target vibration signal.

One aspect of an embodiment of the present specification provides a vibration sensor, comprising: a shell structure and an acoustic transducer, wherein the acoustic transducer is physically connected to the shell structure, wherein at least a portion of the shell structure and the acoustic transducer form an acoustic cavity; a vibration unit, which divides the acoustic cavity into a plurality of acoustic cavities including a first acoustic cavity, wherein the first acoustic cavity is acoustically connected to the acoustic transducer; the vibration unit comprises at least one elastic element and a mass element, wherein the at least one elastic element and the mass element are located in the acoustic cavity, and the mass element is connected to the shell structure or the acoustic transducer through the at least one elastic element. The housing structure is configured to generate vibration based on an external vibration signal, the vibration unit changes the volume of the first acoustic cavity in response to the vibration of the housing structure, and the acoustic transducer generates an electrical signal based on the change in the volume of the first acoustic cavity, wherein the at least one elastic element is distributed on opposite sides of the mass element in a first direction, so that within a target frequency range, the vibration unit has a higher response sensitivity to the vibration of the housing structure in the first direction than to the vibration of the housing structure in a second direction, and the second direction is perpendicular to the first direction.

In some embodiments, the ratio of the harmonic frequency of the vibration unit vibrating in the second direction to the harmonic frequency of the vibration unit vibrating in the first direction is greater than or equal to 2, and the difference between the response sensitivity of the vibration unit to the vibration of the shell structure in the second direction and the response sensitivity of the vibration unit to the vibration of the shell structure in the first direction is -20dB~-40dB.

In some embodiments, the first direction is the thickness direction of the mass element, the distance between the centroid of the at least one elastic element and the center of gravity of the mass element in the first direction is no more than 1/3 of the thickness of the mass element, and the distance between the centroid of the at least one elastic element and the center of gravity of the mass element in the second direction is no more than 1/3 of the side length or radius of the mass element.

In some embodiments, the at least one elastic element includes a first elastic element and a second elastic element, the first elastic element and the second elastic element are connected to the shell structure or the acoustic transducer corresponding to the acoustic cavity; the first elastic element and the second elastic element are approximately symmetrically distributed relative to the mass element in the first direction, wherein the first direction is the thickness direction of the mass element, the upper surface of the mass element is connected to the first elastic element, and the lower surface of the mass element is connected to the second elastic element.

In some embodiments, the first elastic element and the second elastic element are membrane-like structures, and the size of the upper surface or the lower surface of the mass element is smaller than the size of the first elastic element and the second elastic element.

In some embodiments, there is a gap between the first elastic element, the second elastic element, the mass element, and the shell structure or the acoustic transducer corresponding to the acoustic cavity, and the gap contains a filler for adjusting the quality factor of the vibration sensor.

In some embodiments, the first elastic element and the second elastic element are columnar structures, and the first elastic element and the second elastic element extend along the thickness direction of the mass element and are connected to the shell structure.

In some embodiments, there is a gap between the outer side of the first elastic element, the outer side of the second elastic element, the outer side of the mass element, and the shell structure or the acoustic transducer corresponding to the acoustic cavity, and the gap contains a filler for adjusting the quality factor of the vibration sensor.

In some embodiments, the first elastic element includes a first sub-elastic element and a second sub-elastic element, the first sub-elastic element is connected to the shell structure or acoustic transducer corresponding to the acoustic cavity through the second sub-elastic element, and the first sub-elastic element is connected to the upper surface of the mass element; the second elastic element includes a third sub-elastic element and a fourth sub-elastic element, the third sub-elastic element is connected to the shell structure or acoustic transducer corresponding to the acoustic cavity through the fourth sub-elastic element, and the third sub-elastic element is connected to the lower surface of the mass element.

The embodiment of the present specification provides another vibration sensor, which includes a housing structure and an acoustic transducer, wherein the acoustic transducer is physically connected to the housing structure, wherein at least a portion of the housing structure and the acoustic transducer form an acoustic cavity; a vibration unit, which divides the acoustic cavity into a plurality of acoustic cavities including a first acoustic cavity, wherein the first acoustic cavity is acoustically connected to the acoustic transducer; the vibration unit includes at least one elastic element and a mass element, wherein the at least one elastic element and the mass element are located in the acoustic cavity, and the mass element is connected to the housing structure or the acoustic transducer through the at least one elastic element. The housing structure is configured to generate vibration based on an external vibration signal, the vibration unit changes the volume of the first acoustic cavity in response to the vibration of the housing structure, and the acoustic transducer generates an electrical signal based on the change in the volume of the first acoustic cavity; wherein the at least one mass element is distributed on opposite sides of the elastic element in a first direction, so that within a target frequency range, the vibration unit has a higher response sensitivity to the vibration of the housing structure in the first direction than to the vibration of the housing structure in a second direction, and the second direction is perpendicular to the first direction.

100: Headphones

110: Vibration speaker

120: Vibration sensor

300: Vibration sensor

310: Shell structure

320: Vibration unit

330: Sound inlet

340: Substrate

360: The first acoustic cavity

370: Second acoustic cavity

400: Vibration sensor

410: Shell structure

420: Vibration unit

421:Mass element

422: Elastic element

430: Sound inlet

440: Substrate structure

460: The first acoustic cavity

470: Second acoustic cavity

500: Vibration sensor

510: Shell structure

520: Vibration unit

521:Mass element

522: Elastic element

530: Sound inlet

540: Substrate structure

560: The first acoustic cavity

600: Vibration sensor

620: Vibration unit

621:Mass element

622: Elastic element

800: Vibration sensor

810: Shell structure

811:Through hole

820:Acoustic transducer

830: Vibration unit

831:Mass element

832: Elastic element

840: The first acoustic cavity

850: Second acoustic cavity

900: Vibration sensor

910: Shell structure

920: Substrate structure

921:Through hole

930: Vibration unit

931:Mass element

932: Elastic element

940: The first acoustic cavity

950: Second acoustic cavity

960: Gap

1400: Vibration sensor

1410: Shell structure

1420: Substrate structure

1421:Through hole

1430: Vibration unit

1431:Mass element

1432: Elastic element

1440: The first acoustic cavity

1450: Second acoustic cavity

1460: Gap

1500: Vibration sensor

1510: Shell structure

1520: Substrate structure

1521:Through hole

1530: Vibration unit

1531:Mass element

1532: Elastic element

1540: The first acoustic cavity

1550: Second acoustic cavity

1560: Gap

1570:Fixed plate

1600: Vibration sensor

1610: Shell structure

1620: Substrate structure

1621:Through hole

1630: Vibration unit

1631:Mass element

1632: Elastic element

1640: The first acoustic cavity

1650: Second acoustic cavity

1700: Vibration sensor

1710: Shell structure

1720: Substrate structure

1721:Through hole

1730: Vibration unit

1731:Mass element

1732: Elastic element

1740: The first acoustic cavity

1750: Second acoustic cavity

1760: Gap

3201:Mass element

3202: Elastic element

4221: First elastic element

4222: Second elastic element

8321: First elastic element

8322: Second elastic element

9321: First elastic element

9322: Second elastic element

14321: First elastic element

14322: Second elastic element

15321: First elastic element

15322: Second elastic element

16311:First mass element

16312: Second mass element

17311:First mass element

17312: Second mass element

17321: First elastic element

17322: Second elastic element

17323: Third elastic element

153211: First sub-elastic element

153212: Second sub-elastic element

153221: The third elastic element

153222: The fourth elastic element

This specification will be further described in the form of exemplary embodiments, which will be described in detail through the accompanying drawings. These embodiments are not restrictive. In these embodiments, the same component symbols represent the same structure, where: [Figure 1] is an application scenario diagram of a vibration sensor according to some embodiments of this specification; [Figure 2] is a schematic diagram of a vibration signal of the vibration sensor shown in Figure 1; [Figure 3] is a structural schematic diagram of a vibration sensor according to some embodiments of this specification; [Figure 4] is a schematic diagram of a vibration sensor according to some embodiments of this specification. [Figure 5] is a schematic diagram of the structure of the vibration sensor shown in some embodiments of this specification; [Figure 6] is a vibration mode diagram of the vibration sensor in the first direction according to some embodiments of this specification; [Figure 7] is a vibration mode diagram of the vibration sensor in the second direction according to some embodiments of this specification; [Figure 8] is a schematic diagram of the structure of the vibration sensor shown in some embodiments of this specification; [ FIG. 9 is a schematic diagram of the structure of a vibration sensor according to some embodiments of the present specification; FIG. 10 is a frequency response curve diagram of a vibration sensor according to some embodiments of the present specification; FIG. 11 is a dynamic analog diagram of a vibration sensor according to some embodiments of the present specification; FIG. 12 is a dynamic analog diagram of a vibration sensor according to some embodiments of the present specification; FIG. 13 is a dynamic analog diagram of a vibration sensor according to some embodiments of the present specification. [Figure 14] is a schematic diagram of the structure of the vibration sensor shown in some embodiments of this specification; [Figure 15] is a schematic diagram of the structure of the vibration sensor shown in some embodiments of this specification; [Figure 16] is a schematic diagram of the structure of the vibration sensor shown in some embodiments of this specification; [Figure 17] is a schematic diagram of the structure of the vibration sensor shown in some embodiments of this specification.

In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the attached drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention and are not intended to limit the present invention.

On the contrary, the present invention covers any substitution, modification, equivalent method and scheme made on the essence and scope of the present invention as defined by the scope of the patent application. Furthermore, in order to enable the public to have a better understanding of the present invention, some specific details are described in detail in the detailed description of the present invention below. For those skilled in the art, the present invention can be fully understood without the description of these details.

Embodiments of the present invention relate to a vibration sensor. The vibration sensor may include a shell structure, a vibration unit and an acoustic transducer, the shell structure and the acoustic transducer are physically connected, at least a portion of the shell structure and the acoustic transducer form an acoustic cavity, and the vibration unit is located in the acoustic cavity formed by the shell structure and the acoustic transducer. In some embodiments, the vibration unit may include at least one elastic element and a mass element, and at least one elastic element and the mass element are located in the acoustic cavity. The shell structure is configured to generate vibration based on an external signal. When the shell structure generates vibration based on the external signal, the vibration unit vibrates simultaneously in response to the vibration of the shell structure, thereby changing the volume of the first acoustic cavity, and then the acoustic transducer generates an electrical signal. In some embodiments, at least one elastic element is distributed on opposite sides of the mass element in the first direction, or at least one mass element is distributed on opposite sides of the mass element in the first direction, so that within the target frequency range (for example, below 3000 Hz), the response sensitivity of the vibration unit to the vibration of the housing structure in the first direction is higher than the response sensitivity of the vibration unit to the vibration of the housing structure in the second direction, wherein the second direction is perpendicular to the first direction. For example, at least one elastic element includes a first elastic element and a second elastic element, the first elastic element and the second elastic element are respectively located on the upper surface and the lower surface of the mass element, wherein the first elastic element and the second elastic element can be approximately regarded as a whole, and the centroid of the whole approximately coincides with the center of gravity of the mass element. Taking the application of vibration sensors in headphones (e.g., bone conduction headphones) as an example, the vibration sensor can act as a bone conduction microphone to collect vibration signals generated by the user's facial muscles when speaking, and convert the vibration signals into electrical signals containing voice information. When the vibration sensor is integrated into the headphones, the vibration sensor will receive other vibration signals (e.g., vibration signals from speakers, vibration signals from the headphone housing, noise signals in the outside air, etc.) while receiving the vibration signals from the user's facial muscles when speaking. Different vibration signals have different vibration directions. In the embodiment of this specification, the centroid of the elastic element and the center of gravity of the mass element are approximately coincident, so that the response sensitivity of the vibration unit to the vibration of the housing structure in the first direction is higher than the response sensitivity of the vibration unit to the vibration of the housing structure in the second direction. In some application scenarios, the vibration sensor is used to collect the vibration signal of the user when speaking, the first direction corresponds to the facial muscle vibration signal of the user when speaking, and the second direction corresponds to the vibration direction of other vibration signals (for example, the vibration signal of the speaker). In other application scenarios, when the vibration sensor is used to collect noise signals from the external environment, the first direction corresponds to the vibration direction of the noise signal from the external environment, and the second direction corresponds to the vibration direction of other vibration signals (for example, the vibration signal of the speaker), thereby improving the directional selectivity of the vibration sensor and reducing the interference of other vibration signals on the target signal to be collected by the vibration sensor.

In some embodiments, the vibration sensor in the embodiments of this specification can be applied to mobile devices, wearable devices, virtual reality devices, augmented reality devices, etc., or any combination thereof. In some embodiments, the mobile device can include a smart phone, a tablet computer, a personal digital assistant (PDA), a game device, a navigation device, etc., or any combination thereof. In some embodiments, the wearable device can include a smart bracelet, an earphone, a hearing aid, a smart helmet, a smart watch, a smart clothing, a smart backpack, a smart accessory, etc., or any combination thereof. In some embodiments, the virtual reality device and/or augmented reality device may include a virtual reality helmet, virtual reality glasses, virtual reality goggles, augmented reality helmets, augmented reality glasses, augmented reality goggles, etc. or any combination thereof. For example, the virtual reality device and/or augmented reality device may include Google Glass, Oculus Rift, Hololens, Gear VR, etc.

FIG1 is an application scenario diagram of a vibration sensor according to some embodiments of the present specification. Taking the application of the vibration sensor to an earphone (e.g., a bone conduction earphone) as an example, as shown in FIG1 , the earphone 100 may include a vibration speaker 110 and a vibration sensor 120. When a user wears the earphone 100 shown in FIG1 , the earphone 100 contacts the skin area of the user's head. When the earphone 100 is in operation, on the one hand, the vibration speaker 110 generates a vibration signal based on an audio signal, and the vibration signal is transmitted to the user's head skin through the housing of the earphone 100 or other structures (e.g., a vibration plate), and the vibration signal is transmitted to the user's auditory nerve through the bones or muscles of the head. On the other hand, when the user is on a call or recording, the sound emitted by the vocal cords when the user is speaking is transmitted to the skin surface through the bones, and drives the housing of the headset 100 to generate a vibration signal. The vibration sensor 120 can collect the vibration signal and convert it into an electrical signal containing voice information. In some application scenarios, for example, when the user is using the headset 100 to make a call or input voice information, the vibration signal to be collected by the vibration sensor 120 is the vibration signal generated by the facial muscles when the user is speaking. The vibration signal here can be regarded as a target signal (the vibration direction of the target vibration signal is the bidirectional arrow E shown in FIG. 1), and the target signal is the vibration signal to be collected by the vibration sensor 120. The vibration speaker 110 of the earphone 100 will also generate a vibration signal when in operation, and the external air vibration will also act on the earphone 100 to generate a vibration signal, and these vibration signals can be regarded as noise signals. In order to prevent the noise signal from affecting the target signal noise, the vibration speaker 110 and the vibration sensor 120 in the earphone 100 can be arranged vertically or approximately vertically, where the vibration speaker 110 and the vibration sensor 120 are arranged vertically or approximately vertically means that the vibration direction of the vibration speaker 110 (the bidirectional arrow N shown in FIG. 1) is vertically or approximately vertically to the vibration direction of the vibration sensor 120 (the first direction shown in FIG. 1). The approximately vertical here may mean that the normal of the vibration speaker 110 and the normal of the vibration sensor 120 have an angle within a certain range. In some embodiments, the angle may be in the range of 75°-115°. Preferably, the angle may be in the range of 80°-100°. More preferably, the angle may be in the range of 85°-95°. In some embodiments, in order to reduce the impact of the vibration generated by the contact between the earphone 100 and the user's facial skin on the target signal, the vibration direction of the vibration speaker 110 may be set at a certain angle θ (for example, less than 90°) with the plane where the user's skin contact area is located.

FIG2 is a schematic diagram of an exemplary vibration signal according to the vibration sensor shown in FIG1. In combination with FIG1 and FIG2, the vibration direction of the vibration unit in the vibration sensor 120 is the first direction; the vibration signal generated by the vibration speaker 110 is SN, wherein, when the vibration direction of the vibration speaker 110 is not perpendicular to the user's skin contact area, the vibration signal SN generated by the vibration speaker 110 has a signal component Se in the first direction, and the signal component Se can also be regarded as a noise signal; the vibration signal (target signal) generated by the facial muscles of the user when speaking is SE, wherein Se is the signal component of the target signal SE in the first direction, and the signal component can be picked up by the vibration sensor 120. In the vibration unit of the vibration sensor 120 provided in the embodiment of the present specification, the centroid or center of gravity of the elastic element is approximately coincident with the center of gravity of the mass element, so that the response sensitivity of the vibration unit to the vibration of the shell structure in the first direction is higher than the response sensitivity of the vibration unit to the vibration of the shell structure in the second direction, so that the vibration sensor 120 can better receive the effective component Se of the vibration signal (target signal SE) in the first direction generated by the facial muscles of the user when speaking, and at the same time, the vibration signal Sn of the vibration speaker 110 in the second direction has less influence on the vibration sensor 120, thereby improving the directional selectivity of the vibration sensor and reducing the interference of non-target vibration signals on the target signal to be collected by the vibration sensor. It should be noted that the centroid of the elastic element and the center of gravity of the mass element here approximately coincide with each other. It can be understood that the centroid of the elastic element is a regular geometric structure with uniform density (for example, a cylindrical structure, a ring structure, a rectangular parallelepiped structure, etc.) and the center of gravity of the mass element approximately coincide with each other. At this time, the centroid of the elastic element can be regarded as the center of gravity of the elastic element. In some embodiments, when the elastic element is an irregular structure or has uneven density, the actual center of gravity of the elastic element can be regarded as approximately coinciding with the center of gravity of the mass element.

FIG3 is a schematic diagram of a vibration sensor according to some embodiments of the present specification. As shown in FIG3 , the vibration sensor 300 may include a housing structure 310, an acoustic transducer, and a vibration unit 320. In some embodiments, the shape of the vibration sensor 300 may be a cuboid, a cylinder, or other irregular structures. In some embodiments, the housing structure 310 may be made of a material having a certain hardness, so that the housing structure 310 protects the vibration sensor 300 and its internal components (e.g., the vibration unit 320). In some embodiments, the material of the housing structure 310 may include but is not limited to one or more of metal, alloy material, polymer material (e.g., acrylonitrile-butadiene-styrene copolymer, polyvinyl chloride, polycarbonate, polypropylene, etc.), etc. In some embodiments, the shell structure 310 is connected to the acoustic transducer, and the connection methods here may include but are not limited to welding, clamping, bonding or integral molding. In some embodiments, the shell structure 310 and the acoustic transducer can form an acoustic cavity, wherein the vibration unit 320 can be located in the acoustic cavity. The vibration unit 320 can separate the acoustic cavity into a first acoustic cavity 360 and a second acoustic cavity 370. The acoustic transducer can convert the vibration signal of the acoustic cavity inside the shell structure 310 into an electrical signal. Specifically, when the vibration sensor 300 is working, the external vibration signal can be transmitted to the vibration unit 320 through the shell structure 310, and the vibration unit 330 vibrates in response to the vibration of the shell structure 310. Since the vibration phase of the vibration unit 320 is different from the vibration phase of the housing structure 310 and the acoustic transducer, the vibration of the vibration unit 320 can cause the volume of the first acoustic cavity 360 in the housing structure 310 to change, thereby causing the sound pressure of the first acoustic cavity 360 to change, and the acoustic transducer can detect the sound pressure change of the first acoustic cavity 360 and convert it into an electrical signal. In some embodiments, the acoustic transducer may include a substrate 340, and the housing structure 310 may be connected to the acoustic transducer through the substrate 340. In some embodiments, the substrate 340 may be a rigid circuit board (e.g., PCB) and/or a flexible circuit board (e.g., FPC). In some embodiments, the substrate 340 may include at least one sound inlet hole 330, and the first acoustic cavity 360 may be connected to the acoustic transducer through the sound inlet hole 330. In some embodiments, the acoustic transducer may also include at least one diaphragm (not shown in FIG. 3 ), and the diaphragm may be disposed at the sound inlet hole 330. When an external vibration signal acts on the shell structure 310, the sound pressure of the first acoustic cavity 360 changes, and the diaphragm mechanically vibrates in response to the change in the sound pressure of the first acoustic cavity 360. The magnetic circuit system of the acoustic transducer generates an electrical signal based on the mechanical vibration of the diaphragm.

In some embodiments, the vibration unit 320 may include an elastic element 3202 and a mass element 3201, the mass element 3201 and the elastic element 3202 are located in the acoustic cavity, and the mass element 3201 is connected to the shell structure 310 through the elastic element 3202. Specifically, the periphery of the elastic element 3202 is connected to the inner wall of the shell structure 310, and the mass element 3201 may be located on the upper surface or the lower surface of the elastic element 3202. The mass element 3201 can increase the vibration amplitude of the elastic element 3202 relative to the shell structure 310, so that the volume change value of the first acoustic cavity 360 can change significantly under the action of external vibration signals of different sound pressure levels and frequencies, thereby improving the sensitivity of the vibration sensor 300. In some embodiments, the structure of the elastic element 3202 can be a membrane structure. In some embodiments, the mass element 3201 can be a regular structure such as a cuboid, a cylinder, or an irregular structure. In some embodiments, the material of the mass element 3201 can be a metal material or a non-metal material. Metal materials may include but are not limited to steel (e.g., stainless steel, carbon steel, etc.), light alloys (e.g., aluminum alloys, palladium copper, magnesium alloys, titanium alloys, etc.), etc., or any combination thereof. Non-metal materials may include but are not limited to polyurethane foam materials, glass fibers, carbon fibers, graphite fibers, silicon carbide fibers, etc. In some embodiments, the material of the elastic element 3202 may include but is not limited to sponge, rubber, silicone, plastic, foam, polydimethylsiloxane (PDMS), polyimide (PI), etc., or any combination thereof. In some embodiments, the thickness of the elastic element 3202 may be 0.1um~500um. Preferably, the thickness of the elastic element 3202 may be 0.5um~300um. More preferably, the thickness of the elastic element 3202 may be 1um~50um. In some embodiments, the thickness of the mass element 3201 may be 10um~1000um. Preferably, the thickness of the mass element 3201 may be 20um~800um. Further preferably, the thickness of the mass element 3201 may be 50um~500um. In some embodiments, the mass element 3201 may be located at the center of the elastic element 3202. In some embodiments, the size (e.g., length and width) of the mass element 3201 may be smaller than the size of the elastic element 3202, wherein the periphery of the mass element 3201 has a spacing with the inner wall of the shell structure 310, and the spacing may prevent the mass element 3201 from colliding with the shell structure 310 when vibrating. In some embodiments, the distance between the periphery of the mass element 3201 and the inner wall of the shell structure 310 can be 1um~1000um. Preferably, the distance between the periphery of the mass element 3201 and the inner wall of the shell structure 310 is 20um~800um. More preferably, the distance between the periphery of the mass element 3201 and the inner wall of the shell structure 310 is 50um~500um. In some embodiments, the ratio of the resonant frequency of the vibration sensor in the second direction to the resonant frequency in the first direction (also referred to as relative lateral sensitivity) can be changed by adjusting the size (e.g., length, width) of the mass element 3201, so that the sensitivity of the vibration sensor 300 in the second direction is reduced within the target frequency range while ensuring that the sensitivity of the vibration sensor 300 in the first direction does not change significantly. In some embodiments, the ratio of the vibration frequency of the vibration sensor in the second direction to the vibration frequency in the first direction can be greater than 1. Preferably, the ratio of the vibration frequency of the vibration sensor in the second direction to the vibration frequency in the first direction can also be greater than 1.5. Further preferably, the ratio of the vibration frequency of the vibration sensor in the second direction to the vibration frequency in the first direction may also be greater than 2. In some embodiments, the ratio of the size of the mass element 3201 (e.g., length or width) to the size of the elastic element 3202 may be 0.2~0.9. Preferably, the ratio of the size of the mass element 3201 to the size of the elastic element 3202 may be 0.3~0.7. Further preferably, the ratio of the size of the mass element 3201 to the size of the elastic element 3202 may be 0.5-0.7. Just as a specific example, for example, the size of the mass element 3201 (e.g., length or width) may be 1/2 of the size of the elastic element 3202. For another example, the size (e.g., length or width) of the mass element 3201 may be 3/4 of the size of the elastic element 3202. In some embodiments, the first direction may refer to the thickness direction of the mass element 3201, and the second direction is perpendicular to the first direction. In this embodiment, the elastic element 3202 is more likely to undergo elastic deformation than the shell structure 310, so that the vibration unit 320 can move relative to the shell structure 310. When external vibration acts on the shell structure 310, the shell structure 310, the acoustic transducer, the vibration unit 320 and other components vibrate at the same time. Since the vibration phase of the vibration unit 320 is different from the shell structure 310 and the acoustic transducer, the volume of the acoustic cavity changes, resulting in a change in the sound pressure of the acoustic cavity, which is converted into an electrical signal by the acoustic transducer to achieve sound pickup.

It should be noted that the shape of the elastic element 3202 is not limited to the membrane structure shown in FIG. 3 , but can also be other structures that can undergo elastic deformation, such as a spring structure, a metal ring, a membrane structure, a columnar structure, etc.

FIG4 is a schematic diagram of a vibration sensor according to some embodiments of the present specification. The vibration sensor 400 shown in FIG4 may include a housing structure 410, an acoustic transducer, and a vibration unit 420. The vibration sensor 400 in FIG4 may be the same as or similar to the vibration sensor 300 in FIG3. For example, the housing structure 410 of the vibration sensor 400 may be the same as or similar to the housing structure 310 of the vibration sensor 300. For another example, the substrate structure 440 of the vibration sensor 400 may be the same as or similar to the substrate structure 340 of the vibration sensor 300. For another example, the first acoustic cavity 460 of the vibration sensor 400 may be the same as or similar to the first acoustic cavity 360 of the vibration sensor 300. For more information about the vibration sensor 400 (e.g., the second acoustic cavity 470, the sound inlet 430, the mass element 421, etc.), please refer to FIG. 4 and related descriptions.

In some embodiments, the vibration unit may include a mass element 421 and an elastic element 422, wherein the elastic element 422 is located on one side of the mass element 421 in the first direction, for example, the mass element 421 may be located on the upper surface of the elastic element 422. In other embodiments, the mass element 421 may also be located on the lower surface of the elastic element 422.

In some embodiments, the main difference between the vibration sensor 400 in FIG. 4 and the vibration sensor 300 in FIG. 3 is that the elastic element 422 may include a first elastic element 4221 and a second elastic element 4222, and the first elastic element 4221 and the second elastic element 4222 are located on the same side of the mass element 421. As shown in FIG. 4, the mass element 421 is connected to the first elastic element 4221 through the second elastic element 4222, and the first elastic element 4221 is connected to the substrate structure 440 of the acoustic transducer. Specifically, the mass element 421, the second elastic element 4222, and the first elastic element 4221 are connected in sequence from top to bottom, wherein the lower surface of the first elastic element 4221 is connected to the substrate structure 440 of the acoustic transducer, the upper surface of the first elastic element 4221 is connected to the upper surface of the second elastic element 4222, and the mass element 421 is located on the upper surface of the second elastic element.

In some embodiments, the first elastic element 4221 may be a membrane structure, and the second elastic element 4222 may be a ring structure. The inner side of the first elastic element 4221, the lower surface of the second elastic element 4222, and the substrate structure 440 of the acoustic transducer form a first acoustic cavity 460, and the first acoustic cavity 460 is connected to the sound inlet hole 430 at the substrate structure 440. The first elastic element 4221 and the second elastic element 4222 may be made of the same or different materials. The materials of the first elastic element 4221 and/or the second elastic element 4222 may refer to the description of the elastic element 3202 in FIG. 3, which will not be repeated here. In some embodiments, the first elastic element 4221 and the second elastic element 4222 may be an integrated structure or independent structures. In some embodiments, the ratio of the resonant frequency of the vibration sensor in the second direction to the resonant frequency in the first direction (also referred to as relative lateral sensitivity) can be changed by adjusting the size (e.g., length, width) of the mass element 421, so that the sensitivity of the vibration sensor 400 in the second direction is reduced within the target frequency range while ensuring that the sensitivity of the vibration sensor 400 in the first direction does not change significantly. For the specific contents of the size of the mass element 421 and the elastic element 422, please refer to the description elsewhere in this specification, for example, Figure 3 and its related description.

FIG5 is a schematic diagram of the structure of a vibration sensor according to some embodiments of the present specification. As shown in FIG5, the vibration sensor 500 may include a housing structure 510, an acoustic transducer, and a vibration unit 520. The vibration sensor shown in FIG5 is the same as or similar to the vibration sensor 400 shown in FIG4. For example, the housing structure 510 of the vibration sensor 500 is the same as or similar to the housing structure 410 of the vibration sensor 400. For another example, the first acoustic cavity 560 of the vibration sensor 500 is the same as or similar to the first acoustic cavity 460 of the vibration sensor 400. For another example, the substrate structure 540 and the sound inlet 530 of the vibration sensor 500 are the same as or similar to the substrate structure 440 and the sound inlet 430 of the vibration sensor 400.

In some embodiments, as shown in FIG. 5 , the main difference between the vibration sensor 500 and the vibration sensor 400 is that the vibration unit includes a mass element 521 and an elastic element 522, the mass element 521 is connected to a substrate structure 540 through the elastic element 522, and the elastic element 522 is connected to the substrate structure 540 of the acoustic transducer. Specifically, the mass element 521, the elastic element 522 and the substrate structure 540 are connected in sequence from top to bottom, wherein the lower surface of the mass element 521 is connected to the upper surface of the elastic element 522, and the lower surface of the elastic element 522 is connected to the substrate structure 540 of the acoustic transducer.

In some embodiments, the elastic element 522 is a ring-shaped structure, and the inner side of the elastic element 522, the lower surface of the mass element 521 and the substrate structure 540 form a first acoustic cavity 560, and the first acoustic cavity 560 is connected to the sound inlet hole 530 at the substrate structure 540. The material of the elastic element 522 can refer to the description of the elastic element 3202 in Figure 3, which will not be repeated here. In some embodiments, the elastic element 522 and the mass element 521 can be used as an integrated structure or independent structures. In some embodiments, the ratio of the resonant frequency of the vibration sensor in the second direction to the resonant frequency in the first direction (also referred to as relative lateral sensitivity) can be changed by adjusting the size of the mass element 521 (e.g., length, width), so that the sensitivity of the vibration sensor 500 in the second direction is reduced within the target frequency range while ensuring that the sensitivity of the vibration sensor 500 in the first direction does not change significantly. For the specific contents of the size of the mass element 521 and the elastic element 522, please refer to the description elsewhere in this specification, for example, Figure 3 and its related description.

FIG. 6 is a vibration mode diagram of a vibration sensor in a first direction according to some embodiments of the present specification; FIG. 7 is a vibration mode diagram of a vibration sensor in a second direction according to some embodiments of the present specification. As shown in FIG. 6 and FIG. 7, when the vibration sensor 600 receives vibration signals of different vibration directions, the vibration conditions of the vibration unit 620 are also different. As shown in FIG. 6, in some embodiments, when the vibration sensor 600 receives a vibration signal from a first direction, the mass element 621 of the vibration unit 620 vibrates along the first direction, and at the same time, the elastic element 622 generates elastic deformation in the first direction under the action of the mass element 621, where the displacement of the left and right sides of the mass element 621 in the first direction is the same, and the elastic deformation of the left and right sides of the elastic element 622 in the first direction is also the same. As shown in FIG. 7 , when the vibration sensor 600 receives the vibration signal from the second direction, the mass element 621 and the elastic element 622 generate wave-like motion, for example, the vibration amplitudes of the left side and the right side of the mass element 621 and the elastic element 622 are different. It can be seen that when the vibration sensor 600 receives the target signal, other vibration signals (for example, signals with different vibration directions from the target signal) will interfere with the target signal. In some embodiments, in order to reduce the interference of other signals as much as possible when the vibration sensor receives the target signal, the vibration unit 620 (for example, the elastic element 622 and the mass element 621) can be adjusted. For example, by providing at least one elastic element in the vibration sensor that is approximately symmetrically distributed relative to the mass element in the first direction, or providing at least one mass element in the vibration sensor that is approximately symmetrically distributed relative to the elastic element in the first direction, so that the distance between the center of gravity of the mass element and the centroid of at least one elastic element is limited to a specific range (for example, the distance between the centroid of at least one elastic element and the center of gravity of the mass element in the first direction is not greater than 1/3 of the thickness of the mass element), the sensitivity of the vibration sensor in the second direction can be reduced, thereby improving the directional selectivity of the vibration sensor and enhancing the anti-noise interference capability of the vibration sensor. For the content of further improving the sensitivity of the vibration sensor in the first direction while reducing the sensitivity in the second direction, please refer to Figures 8 to 17 and their related descriptions.

FIG8 is a schematic diagram of a structure of a vibration sensor according to some embodiments of the present specification. As shown in FIG8 , the vibration sensor 800 may include a housing structure 810, an acoustic transducer 820, and a vibration unit 830. In some embodiments, the shape of the housing structure 810 may be a cuboid, a cylinder, or other regular structures or irregular structures. In some embodiments, the housing structure 810 may be made of a material having a certain hardness, so that the housing structure 810 protects the vibration sensor 800 and its internal components (e.g., the vibration unit 830). In some embodiments, the material of the housing structure 810 may include but is not limited to one or more of metals, alloy materials, polymer materials (e.g., acrylonitrile-butadiene-styrene copolymer, polyvinyl chloride, polycarbonate, polypropylene, etc.), etc. In some embodiments, the shell structure 810 and the acoustic transducer 820 are connected in a physical manner, and the physical connection here may include but is not limited to connection methods such as welding, clamping, bonding or integral molding. In some embodiments, at least part of the shell structure 810 and the acoustic transducer 820 can form an acoustic cavity. In some embodiments, the shell structure 810 can independently form a packaging structure with an acoustic cavity, wherein the acoustic transducer 820 can be located in the acoustic cavity of the packaging structure. In some embodiments, the shell structure 810 can be a structure with a hollow interior and an open opening at one end, and the acoustic transducer 820 is physically connected to the open end of the shell structure 810 to achieve packaging, thereby forming an acoustic cavity. In some embodiments, the vibration unit 830 may be located in the acoustic cavity, and the vibration unit 830 may separate the acoustic cavity into a first acoustic cavity 840 and a second acoustic cavity 850. In some embodiments, the first acoustic cavity 840 is acoustically connected to the acoustic transducer 820, and the second acoustic cavity 850 may be an acoustically sealed cavity structure. It should be noted that the multiple acoustic cavities into which the vibration unit 830 separates the acoustic cavity are not limited to the first acoustic cavity 840 and the second acoustic cavity 850, and may also include more acoustic cavities, for example, a third acoustic cavity, a fourth acoustic cavity, etc.

The vibration sensor 800 can convert the external vibration signal into an electrical signal. In some embodiments, the external vibration signal may include a vibration signal when a person speaks, a vibration signal generated by the skin following the movement of the human body or the operation of a speaker close to the skin, a vibration signal generated by an object or air in contact with the vibration sensor, or any combination thereof. Further, the electrical signal generated by the vibration sensor can be input into an external electronic device. In some embodiments, the external electronic device may include a mobile device, a wearable device, a virtual reality device, an augmented reality device, or the like, or any combination thereof. In some embodiments, the mobile device may include a smart phone, a tablet computer, a personal digital assistant (PDA), a gaming device, a navigation device, or the like, or any combination thereof. In some embodiments, the wearable device may include a smart bracelet, earphones, hearing aids, a smart helmet, a smart watch, smart clothing, a smart backpack, a smart accessory, or any combination thereof. In some embodiments, the virtual reality device and/or the augmented reality device may include a virtual reality helmet, a virtual reality glasses, a virtual reality goggles, an augmented reality helmet, an augmented reality glasses, an augmented reality goggles, or any combination thereof. For example, the virtual reality device and/or the augmented reality device may include Google Glass, Oculus Rift, Hololens, Gear VR, or the like. Specifically, when the vibration sensor 800 is working, the external vibration signal can be transmitted to the vibration unit 830 through the housing structure 810, and the vibration unit 830 vibrates in response to the vibration of the housing structure 810. Since the vibration phase of the vibration unit 830 is different from the vibration phase of the housing structure 810 and the acoustic transducer 820, the vibration of the vibration unit 830 can cause the volume of the first acoustic cavity 840 to change, thereby causing the sound pressure of the first acoustic cavity 840 to change. The acoustic transducer 820 can detect the sound pressure change of the first acoustic cavity 840 and convert it into an electrical signal, which is transmitted to the external electronic device through the solder joint (not shown in FIG. 8). The solder joints here can be electrically connected to internal components (e.g., processors) of devices such as headphones, hearing aids, hearing aids, augmented reality glasses, augmented reality helmets, virtual reality glasses, etc. through data lines, and the electrical signals obtained by the internal components can be transmitted to external electronic devices via wired or wireless means. In some embodiments, the acoustic transducer 820 may include at least one through hole 811, which is connected to the first cavity 840. A diaphragm (not shown in FIG. 8 ) is provided at the position of the through hole 811. When the sound pressure of the first acoustic cavity 840 changes, the air inside the first acoustic cavity 840 vibrates and acts on the diaphragm through the through hole 811, causing the diaphragm to deform. The acoustic transducer 820 converts the vibration signal of the diaphragm into an electrical signal.

In some embodiments, the vibration unit 830 may include a mass element 831 and at least one elastic element 832, and the mass element 831 and the at least one elastic element 832 are located in an acoustic cavity formed by the shell structure 810 and the acoustic transducer 820. In some embodiments, the at least one elastic element 832 may be distributed on opposite sides of the mass element 831 in a first direction. The first direction may refer to the thickness direction of the mass element 831. For example, the first direction may be the “first direction” indicated by the arrow in FIG. 8 . In some embodiments, the mass element 831 may be connected to the shell structure 810 and/or the acoustic transducer 820 through at least one elastic element 832. For example, at least one elastic element 832 may include a first elastic element 8321 and a second elastic element 8322, and the first elastic element 8321 is located on a side of the mass element 831 away from the acoustic transducer 820. It can also be understood that the first elastic element 8321 is located on the upper surface of the mass element 831, wherein one end of the first elastic element 8321 is connected to the shell structure 810, and the other end of the first elastic element 8321 is connected to the mass element 831. The second elastic element 8322 may be located on a side of the mass element 831 close to the acoustic transducer 820, and it may also be understood that the second elastic element 8322 is located on the lower surface of the mass element 831, wherein one end of the second elastic element 8322 is connected to the acoustic transducer 820, and the other end of the second elastic element 8322 is connected to the mass element 831. In other embodiments, at least one elastic element 832 may also be located around the mass element 831, wherein the inner side of at least one elastic element 832 is connected to the outer side of the mass element 831, and the outer side of at least one elastic element 832 is connected to the shell structure 810 and/or the acoustic transducer 820. The side of the mass element 831 mentioned here is relative to the vibration direction of the mass element 831 (for example, the first direction). For convenience, the direction of the mass element 831 relative to the vibration of the shell structure 810 can be considered as the axial direction. At this time, the side of the mass element 831 means a side of the mass element 831 arranged around the axis. In some embodiments, the mass element 831 can be a regular structure or an irregular structure such as a cuboid or a cylinder. In some embodiments, the material of the mass element 831 can be a metal material or a non-metal material. The metal material can include but is not limited to steel (for example, stainless steel, carbon steel, etc.), light alloy (for example, aluminum alloy, cobalt, magnesium alloy, titanium alloy, etc.), etc., or any combination thereof. Non-metallic materials may include but are not limited to polyurethane foam, glass fiber, carbon fiber, graphite fiber, silicon carbide fiber, etc. In some embodiments, the elastic element 832 may be in the shape of a round tube, a square tube, a special-shaped tube, a ring, a flat plate, etc. In some embodiments, at least one elastic element 832 may have a structure that is more prone to elastic deformation (e.g., a spring structure, a metal ring, a membrane structure, a columnar structure, etc.), and its material may be a material that is prone to elastic deformation, such as silicone, rubber, etc. In the embodiments of the present specification, at least one elastic element 832 is more likely to undergo elastic deformation than the shell structure 810, so that the vibration element 830 can move relative to the shell structure 810. It should be noted that in some embodiments, the mass element 831 and any one of the at least one elastic element 832 can be composed of the same or different materials, and then assembled together to form the vibration unit 830. In some embodiments, the mass element 831 and any one of the at least one elastic element 832 can also be composed of the same material, and then formed into a single piece to form the vibration unit 830. At least one elastic element 832 and the mass element 831, the acoustic transducer 820, and the housing structure 810 may be bonded by an adhesive, or other connection methods known to those skilled in the art (e.g., welding, clamping, etc.) may be used, without limitation.

In some embodiments, the first elastic element 8321 and the second elastic element 8322 may be approximately symmetrically distributed relative to the mass element 831 in the first direction. In some embodiments, the first elastic element 8321 and the second elastic element 8322 may be connected to the housing structure 810 or the acoustic transducer 820. For example, the first elastic element 8321 may be located on a side of the mass element 831 away from the acoustic transducer 820, one end of the first elastic element 8321 is connected to the housing structure 810, and the other end of the first elastic element 8321 is connected to the upper surface of the mass element 831. The second elastic element 8322 can be located on a side of the mass element 831 facing the acoustic transducer 820 , one end of the second elastic element 8322 is connected to the acoustic transducer 820 , and the other end of the second elastic element 8322 is connected to the lower surface of the mass element 831 . In some embodiments, by providing the first elastic element 8321 and the second elastic element 8322 in the vibration sensor 800 and being approximately symmetrically distributed with respect to the mass element 831 in the first direction, the center of gravity of the mass element 831 and the centroid of at least one elastic element 832 are approximately coincident, so that when the vibration unit 830 vibrates in response to the vibration of the housing structure 810, the vibration of the mass element 831 in the second direction can be reduced, thereby reducing the response sensitivity of the vibration unit 830 to the vibration of the housing structure 810 in the second direction, thereby improving the directional selectivity of the vibration sensor 800. The second direction here is perpendicular to the first direction. In some embodiments, the centroid of at least one elastic element 832 can refer to the geometric center of the elastic element 832. The centroid of the elastic element 832 is related to the shape and size of the elastic element 832. For example, when at least one elastic element 832 is a rectangular plate structure, the centroid of at least one elastic element 832 can be located at the intersection of two diagonal lines of the rectangular plate structure. In some embodiments, the elastic element 832 can be approximately regarded as a structure with uniform density, and the centroid of the elastic element 832 can be approximately regarded as the center of gravity of the elastic element 832.

In some embodiments, the size, shape, material, or thickness of the first elastic element 8321 and the second elastic element 8322 may be the same. In some embodiments, the structure of the first elastic element 8321 and the structure of the second elastic element 8322 may be a membrane structure, a columnar structure, a tubular structure, or any combination thereof. In some embodiments, the material of the first elastic element 8321 and the second elastic element 8322 may include but is not limited to sponge, rubber, silicone, plastic, foam, polydimethylsiloxane (PDMS), polyimide (PI), or any combination thereof. In some embodiments, plastic may include but is not limited to polytetrafluoroethylene (PTFE), high molecular polyethylene, blown nylon, engineering plastics, or any combination thereof. Rubber may refer to other single or composite materials that can achieve the same performance, and may include but not limited to general-purpose rubber and special-purpose rubber. In some embodiments, general-purpose rubber may include but not limited to natural rubber, isoprene rubber, styrene-butadiene rubber, cis-butadiene rubber, chloroprene rubber, etc. or any combination thereof. In some embodiments, special-purpose rubber may include but not limited to nitrile rubber, silicone rubber, fluororubber, polysulfide rubber, polyurethane rubber, epichlorohydrin rubber, acrylate rubber, propylene oxide rubber, etc. or any combination thereof. Among them, styrene-butadiene rubber may include but not limited to emulsion-polymerized styrene-butadiene rubber and solution-polymerized styrene-butadiene rubber. In some embodiments, the composite material may include but is not limited to reinforcing materials such as glass fiber, carbon fiber, boron fiber, graphite fiber, fiber, graphene fiber, silicon carbide fiber or aramid fiber.

For example, when the first elastic element 8321 and the second elastic element 8322 are both membrane structures, made of the same material (e.g., polytetrafluoroethylene), and have the same size and thickness, the first elastic element 8321 and the second elastic element 8322 are approximately symmetrically distributed relative to the mass element 831 in the first direction, so that the centroid of at least one elastic element 832 can coincide or approximately coincide with the center of gravity of the mass element 831, and thus when the vibration unit 830 vibrates in response to the vibration of the housing structure 810, the vibration of the mass element 831 in the second direction can be reduced, thereby reducing the response sensitivity of the vibration unit 830 to the vibration of the housing structure 810 in the second direction, and thus improving the direction selectivity of the vibration sensor 800 when receiving the vibration signal.

In some embodiments, the first elastic element 8321 and the second elastic element 8322 are distributed on opposite sides of the mass element 831 in the first direction, where the first elastic element 8321 and the second elastic element 8322 can be approximately regarded as one elastic element, the centroid of the elastic element approximately coincides with the center of gravity of the mass element, so that within the target frequency range (for example, below 3000 Hz), the response sensitivity of the vibration unit 830 to the vibration of the shell structure 810 in the first direction is higher than the response sensitivity of the vibration unit 830 to the vibration of the shell structure 810 in the second direction. In some embodiments, the difference between the response sensitivity of the vibration unit 830 to the vibration of the shell structure 810 in the second direction and the response sensitivity of the vibration unit 830 to the vibration of the shell structure 810 in the first direction may be -20dB~-60dB. In some embodiments, the difference between the response sensitivity of the vibration unit 830 to the vibration of the shell structure 810 in the second direction and the response sensitivity of the vibration unit 830 to the vibration of the shell structure 810 in the first direction may be -25dB~-50dB. In some embodiments, the difference between the response sensitivity of the vibration unit 830 to the vibration of the shell structure 810 in the second direction and the response sensitivity of the vibration unit 830 to the vibration of the shell structure 810 in the first direction may be -30dB~-40dB. In some embodiments, the target frequency range may refer to a frequency range less than or equal to 3000 Hz.

In some embodiments, the vibration unit 830 generates vibration in a first direction in response to the vibration of the housing structure 810. The vibration in the first direction can be regarded as the sound signal that the vibration sensor 800 expects to pick up, and the vibration in the second direction can be regarded as a noise signal. Therefore, during the operation of the vibration sensor 800, the vibration generated by the vibration unit 830 in the second direction can be reduced, thereby reducing the response sensitivity of the vibration unit 830 to the vibration of the housing structure 810 in the second direction, thereby improving the directional selectivity of the vibration sensor 800 and reducing the interference of the noise signal on the sound signal.

In some embodiments, the centroid of at least one elastic element 832 may coincide with or approximately coincide with the center of gravity of the mass element 831. In some embodiments, when the vibration unit 830 vibrates in response to the vibration of the housing structure 810, the centroid of at least one elastic element 832 coincides with or approximately coincides with the center of gravity of the mass element 831, which can reduce the vibration of the mass element 831 in the second direction while keeping the response sensitivity of the vibration unit 830 to the vibration of the housing structure 810 in the first direction substantially unchanged, thereby reducing the response sensitivity of the vibration unit 830 to the vibration of the housing structure 810 in the second direction, thereby improving the directional selectivity of the vibration sensor 800. In some embodiments, the response sensitivity of the vibration unit 830 to the vibration of the shell structure 810 in the first direction can be changed (for example, improved) by adjusting the thickness, elastic coefficient of the elastic element 832, the mass and size of the mass element 831, etc.

The fact that the centroid of at least one elastic element 832 and the center of gravity of the mass element 831 can coincide or approximately coincide can be understood as the centroid of the elastic element 832 and the center of gravity of the mass element 831 satisfying specific conditions in the first direction and the second direction. In some embodiments, the specific condition can be that the distance between the centroid of at least one elastic element 832 and the center of gravity of the mass element 831 in the first direction can be no greater than 1/4 of the thickness of the mass element 831, and the distance between the centroid of at least one elastic element 832 and the center of gravity of the mass element 831 in the second direction is no greater than 1/4 of the side length or radius of the mass element 831. In some embodiments, the specific condition may be that the distance between the centroid of at least one elastic element 832 and the center of gravity of the mass element 831 in the first direction may be no greater than 1/3 of the thickness of the mass element 831, and the distance between the centroid of at least one elastic element 832 and the center of gravity of the mass element 831 in the second direction may be no greater than 1/3 of the side length or radius of the mass element 831. In some embodiments, the distance between the centroid of at least one elastic element 832 and the center of gravity of the mass element 831 in the first direction may be no greater than 1/2 of the thickness of the mass element 831, and the distance between the centroid of at least one elastic element 832 and the center of gravity of the mass element 831 in the second direction may be no greater than 1/2 of the side length or radius of the mass element 831. For example, when the mass element 831 is a cube, the distance between the centroid of at least one elastic element 832 and the center of gravity of the mass element 831 in the first direction is no more than 1/3 of the thickness (side length) of the mass element 831, and the distance between the centroid of at least one elastic element 832 and the center of gravity of the mass element 831 in the second direction is no more than 1/3 of the side length of the mass element 831. For another example, when the mass element 831 is a cylinder, the distance between the centroid of at least one elastic element 832 and the center of gravity of the mass element 831 in the first direction is no more than 1/4 of the thickness (height) of the mass element 831, and the distance between the centroid of at least one elastic element 832 and the center of gravity of the mass element 831 in the second direction is no more than 1/4 of the circular radius of the upper surface (or lower surface) of the mass element 831.

In some embodiments, when the centroid of at least one elastic element 832 coincides or approximately coincides with the center of gravity of the mass element 831, the harmonic frequency of the vibration unit 830 vibrating in the second direction can be shifted to a high frequency without changing the harmonic frequency of the vibration unit 830 vibrating in the first direction. In some embodiments, when the centroid of at least one elastic element 832 coincides or approximately coincides with the center of gravity of the mass element 831, the harmonic frequency of the vibration unit 830 vibrating in the first direction can remain substantially unchanged, for example, the harmonic frequency of the vibration unit 830 vibrating in the first direction can be a frequency within a relatively strong frequency range perceived by the human ear (for example, 20 Hz-2000 Hz, 2000 Hz-3000 Hz, etc.). The harmonic frequency of the vibration unit 830 vibrating in the second direction may be shifted to a high frequency and located in a frequency range (e.g., 5000 Hz-9000 Hz, 1 kHz-14 kHz, etc.) where human ear perception is relatively weak. Based on the shift of the harmonic frequency of the vibration unit 830 vibrating in the second direction to a high frequency, the harmonic frequency of the vibration unit 830 vibrating in the first direction remains substantially unchanged, so that the ratio of the harmonic frequency of the vibration unit 830 vibrating in the second direction to the harmonic frequency of the vibration unit 830 vibrating in the first direction may be greater than or equal to 2. In some embodiments, the ratio of the harmonic frequency of the vibration unit 830 vibrating in the second direction to the harmonic frequency of the vibration unit 830 vibrating in the first direction may also be greater than or equal to other values. For example, the ratio of the harmonic frequency of the vibration unit 830 vibrating in the second direction to the harmonic frequency of the vibration unit 830 vibrating in the first direction may also be greater than or equal to 1.5.

In some embodiments, the ratio of the harmonic frequency of the vibration unit 830 vibrating in the second direction to the harmonic frequency of the vibration unit 830 vibrating in the first direction can reflect the influence of the noise signal picked up by the vibration sensor 800 on the sound signal. For example, the larger the ratio of the harmonic frequency of the vibration unit 830 vibrating in the second direction to the harmonic frequency of the vibration unit 830 vibrating in the first direction, the higher the harmonic frequency of the vibration unit 830 vibrating in the second direction. At this time, the vibration unit 830 is more sensitive to sounds in the lower frequency band (for example, below 2000 Hz) in the first direction, and the vibration unit 830 is more sensitive to sounds in the higher frequency band in the second direction. The sensitivity of high-frequency sounds (for example, above 2000Hz) is higher, while the human ear is insensitive to sound signals in the higher-frequency band (for example, greater than 2000Hz), but sensitive to sound signals in the lower-frequency band (for example, below 2000Hz). The noise signal in the higher-frequency band range in the second direction picked up by the vibration unit 830 has less interference with the target sound signal picked up in the first direction.

In some embodiments, adjusting the size of the mass element 831 can also reduce the response sensitivity of the vibration unit 830 to the vibration of the housing structure 810 in the second direction. For example, without changing the mass of the mass element 831, the thickness of the mass element 831 can be reduced (or the area of the upper surface and/or lower surface of the mass element 831 is increased) so that the resonant frequency of the vibration unit 830 in the second direction is in the high frequency range (for example, greater than 3000 Hz), thereby reducing the response sensitivity of the vibration unit 830 to the vibration in the second direction within the target frequency range (for example, less than 3000 Hz).

FIG. 9 is a schematic diagram of a structure of a vibration sensor according to some embodiments of the present specification. A vibration sensor 900 as shown in FIG. 9 may include a housing structure 910, an acoustic transducer, and a vibration unit 930. In some embodiments, the housing structure 910 may be in the shape of a cuboid, a cylinder, or other regular structures or irregular structures. In some embodiments, the housing structure 910 may be made of a material having a certain hardness, so that the housing structure 910 protects the vibration sensor 900 and its internal components (e.g., the vibration unit 930). In some embodiments, the material of the housing structure 910 may include but is not limited to one or more of metals, alloy materials, polymer materials, etc. In some embodiments, the shell structure 910 can be connected to the substrate structure 920 on the upper surface of the acoustic transducer, and the connection method here can include but is not limited to welding, clamping, bonding or integral molding. In some embodiments, the substrate structure 920 can be a rigid circuit board (e.g., PCB) and/or a flexible circuit board (e.g., FPC). In some embodiments, at least part of the shell structure 910 and the substrate structure 920 on the upper surface of the acoustic transducer can form an acoustic cavity. In some embodiments, the shell structure 910 can independently form a packaging structure with an acoustic cavity, wherein the acoustic transducer can be located in the acoustic cavity of the packaging structure. In some embodiments, the shell structure 910 may be a structure that is hollow inside and has an open opening at one end, and the substrate structure 920 on the upper surface of the acoustic transducer is physically connected to the open end of the shell structure 910 to achieve packaging, thereby forming an acoustic cavity. In some embodiments, the vibration unit 930 may be located in the acoustic cavity. The vibration unit 930 may separate the acoustic cavity into a first acoustic cavity 940 and a second acoustic cavity 950. In some embodiments, the first acoustic cavity 940 may be acoustically connected to the acoustic transducer through a through hole 921 located on the substrate structure 920, and the second acoustic cavity 950 may be an acoustically sealed cavity structure. It should be noted that the multiple acoustic cavities into which the vibration unit 930 divides the acoustic cavity are not limited to the first acoustic cavity 940 and the second acoustic cavity 950, but may also include more acoustic cavities, for example, the third acoustic cavity, the fourth acoustic cavity, etc.

In some embodiments, the vibration unit 930 may include a mass element 931 and an elastic element 932, wherein the elastic element 932 may include a first elastic element 9321 and a second elastic element 9322. In some embodiments, the first elastic element 9321 and the second elastic element 9322 may be a membrane structure. In some embodiments, the first elastic element 9321 and the second elastic element 9322 may be approximately symmetrically distributed relative to the mass element 931 in the first direction. The first elastic element 9321 and the second elastic element 9322 may be connected to the shell structure 910. For example, the first elastic element 9321 may be located on a side of the mass element 931 facing away from the substrate structure 920, the lower surface of the first elastic element 9321 may be connected to the upper surface of the mass element 931, and the periphery of the first elastic element 9321 may be connected to the inner wall of the shell structure 910. The second elastic element 9322 may be located on a side of the mass element 931 facing the substrate structure 920, the upper surface of the second elastic element 9322 may be connected to the lower surface of the mass element 931, and the periphery of the second elastic element 9322 may be connected to the inner wall of the shell structure 910. It should be noted that the membrane structure of the first elastic element 9321 and the second elastic element 9322 can be a regular and/or irregular structure such as a rectangle or a circle, and the shapes of the first elastic element 9321 and the second elastic element 9322 can be adaptively adjusted according to the cross-sectional shape of the shell structure 910.

In some embodiments, when the first elastic element 9321 and the second elastic element 9322 are membrane structures, the size of the upper surface or the lower surface of the mass element 931 is smaller than the size of the first elastic element 9321 and the second elastic element 9322, and the side surface of the mass element 931 and the inner wall of the shell structure 910 form a ring or rectangle with equal spacing. In some embodiments, the thickness of the mass element 931 can be 10um~1000um. In some embodiments, the thickness of the mass element 931 can be 6um~500um. In some embodiments, the thickness of the mass element 931 can be 800um~1400um. In some embodiments, the thickness of the first elastic element 9321 and the second elastic element 9322 can be 0.1um~500um. In some embodiments, the thickness of the first elastic element 9321 and the second elastic element 9322 may be 0.05um~200um. In some embodiments, the thickness of the first elastic element 9321 and the second elastic element 9322 may be 300um~800um. In some embodiments, the thickness ratio of each elastic element (e.g., the first elastic element 9321 or the second elastic element 9322) to the mass element 931 may be 2~100. In some embodiments, the thickness ratio of each elastic element to the mass element 931 may be 10~50. In some embodiments, the thickness ratio of each elastic element to the mass element 931 may be 20~40. In some embodiments, the thickness difference between the mass element 931 and each elastic element (e.g., the first elastic element 9321 or the second elastic element 9322) may be 9um~500um. In some embodiments, the thickness difference between the mass element 931 and each elastic element may be 50um~400um. In some embodiments, the thickness difference between the mass element 931 and each elastic element may be 100um~300um.

In some embodiments, a gap 960 may be formed between the first elastic element 9321, the second elastic element 9322, the mass element 931 and the housing structure 910 or the acoustic transducer corresponding to the acoustic cavity. As shown in FIG9 , in some embodiments, the gap 960 may be located around the mass element 931. When the mass element 931 responds to an external vibration signal, the mass element 931 vibrates relative to the housing structure 910. The gap 960 may prevent the mass element 931 from colliding with the housing structure 910 when vibrating. In some embodiments, the gap 960 may include a filler. By providing the filler in the gap 960, the quality factor of the vibration sensor 900 may be adjusted. Preferably, the filler is provided in the gap 960 so that the quality factor of the vibration sensor 900 is 0.7 to 10. More preferably, the filler is provided in the gap 960 so that the quality factor of the vibration sensor 900 is 1 to 5. In some embodiments, the filler may be one or more of a gas, a liquid (e.g., silicone oil), an elastic material, etc. Exemplary gases may include but are not limited to one or more of air, argon, nitrogen, carbon dioxide, etc. Exemplary elastic materials may include but are not limited to silicone gel, silicone rubber, etc.

In some embodiments, the volume of the acoustic cavity (for example, the second acoustic cavity 950) formed between the first elastic element 9321 and the shell structure 910 corresponding to the acoustic cavity can be greater than or equal to the volume of the first acoustic cavity 940 formed between the second elastic element 9322 and the shell structure 910 and the substrate structure 920 corresponding to the acoustic cavity, so that the volume of the first acoustic cavity 940 is equal to or approximately equal to the volume of the second acoustic cavity 950, thereby improving the symmetry of the vibration sensor 900. Specifically, there is air inside the first acoustic cavity 940 and the second acoustic cavity 950. When the vibration unit 930 vibrates relative to the shell, the vibration unit 930 compresses the air inside the two acoustic cavities. The first acoustic cavity 940 and the second acoustic cavity 950 can be approximately regarded as two air springs. The volume of the second acoustic cavity 950 is greater than or equal to the volume of the first acoustic cavity 940, so that the coefficients of the air springs brought by the compression of the air by the vibration unit 930 during vibration are approximately equal, thereby further improving the symmetry of the elastic elements (including air springs) on the upper and lower sides of the mass element 931. In some embodiments, the volume of the first acoustic cavity 940 and the volume of the second acoustic cavity 950 may be 10um3~1000um3. Preferably, the volume of the first acoustic cavity 940 and the volume of the second acoustic cavity 950 may be 50um3~500um3.

FIG10 is a frequency response curve diagram of a vibration sensor according to some embodiments of the present specification. As shown in FIG10 , the horizontal axis represents frequency in Hz, and the vertical axis represents the sensitivity of the vibration sensor in dB. Curve 1010 represents the sensitivity of a vibration sensor including one elastic element (e.g., the vibration sensor 300 of FIG3 ) in a first direction. Curve 1020 represents the sensitivity of a vibration sensor including two approximately symmetrical elastic elements (e.g., the first elastic element 9321 and the second elastic element 9322 shown in FIG9 ) in a first direction. Curve 1030 represents the sensitivity of a vibration sensor including one elastic element (e.g., the vibration sensor 300 of FIG3 ) in a second direction. Curve 1040 represents the sensitivity of a vibration sensor including two approximately symmetrical elastic elements (e.g., the first elastic element 9321 and the second elastic element 9322 shown in FIG. 9 ) in the second direction. The elastic element of the vibration sensor corresponding to curve 1010 (or curve 1030) is the same in material and shape as the two elastic elements of the vibration sensor corresponding to curve 1020 (or curve 1040), and the difference is that the thickness of the elastic element of the vibration sensor corresponding to curve 1010 (or curve 1030) is approximately equal to the total thickness of the two elastic elements of the vibration sensor corresponding to curve 1020 (or curve 1040). It should be noted that the error of the approximate equality here does not exceed 50%.

By comparing curve 1010 and curve 1020, it can be seen that within a specific frequency range (e.g., below 3000 Hz), the sensitivity of the vibration sensor with one elastic element in the first direction (curve 1010 in FIG. 10 ) is approximately equal to the sensitivity of the vibration sensor with two approximately symmetrical elastic elements in the first direction (curve 1020 in FIG. 10 ). It can also be understood that within a specific frequency range (e.g., below 3000 Hz), the number and distribution of elastic elements included in the vibration sensor have little effect on the sensitivity of the vibration sensor in the first direction. In addition, in curves 1010 and 1020, f1 is the resonance frequency of the resonance peak in the first direction of the vibration sensor having one elastic element, and f2 is the resonance frequency of the resonance peak in the first direction of the vibration sensor having two approximately symmetrical elastic elements, wherein the resonance frequency f1 of the resonance peak in the first direction of the vibration sensor having one elastic element is approximately equal to the resonance frequency f2 of the resonance peak in the first direction of the vibration sensor having two approximately symmetrical elastic elements. That is, within a specific frequency range, the sensitivity of the vibration sensor having one elastic element in the first direction is approximately equal to the sensitivity of the vibration sensor having two approximately symmetrical elastic elements in the first direction. Considering that the vibration sensor is a non-ideal device, the resonant frequency in the first direction of the vibration sensor has a mapping (also called a component) in the second direction. Accordingly, in curve 1030, f3 is used to characterize the mapping of the resonant frequency in the first direction of the vibration sensor having an elastic element in the frequency response curve of the second direction (it can also be understood as the resonant frequency in the first direction in the second direction). In the curve 1040, f4 is used to characterize the mapping of the resonant frequency in the first direction of the vibration sensor including two elastic elements in the frequency response curve in the second direction, and f6 is the resonant frequency in the second direction of the vibration sensor having two approximately symmetrical elastic elements. Due to the existence of the mapping relationship, the resonant frequency f3 in the third curve 1030 is approximately equal to the resonant frequency f1 in the first curve 1010, and the resonant frequency f4 in the fourth curve 1040 is approximately equal to the resonant frequency f2 in the second curve 1020. By comparing curve 1030 and curve 1040, it can be seen that within a specific frequency range (for example, below 3000 Hz), the sensitivity of the vibration sensor including one elastic element in the second direction (curve 1030 in FIG. 10 ) is greater than the sensitivity of the vibration sensor including two approximately symmetrical elastic elements in the second direction (curve 1040 in FIG. 10 ). It can also be understood that within a specific frequency range (for example, below 3000 Hz), the number and distribution of elastic elements included in the vibration sensor have a greater impact on the sensitivity of the vibration sensor in the second direction. In addition, it can be seen from the combination of curve 1030 and curve 1040 that when f1 and f2 are approximately equal (or f3 and f4 are approximately equal), within a specific frequency range (for example, below 3000 Hz), the resonance frequency f5 corresponding to the resonance peak in the second direction of the vibration sensor having one elastic element is significantly smaller than the resonance frequency f6 corresponding to the resonance peak in the second direction of the vibration sensor including two approximately symmetrical elastic elements. In some embodiments, by providing two approximately symmetrical elastic elements in the vibration sensor, the resonance frequency of the resonance peak in the second direction of the vibration sensor can be located in a higher frequency range, thereby reducing the sensitivity of the vibration sensor in the medium and low frequency range far from the resonance frequency. Furthermore, within a specific frequency range (3000 Hz), the sensitivity of the vibration sensor including two approximately symmetrical elastic elements in the second direction (curve 1040 in FIG. 10 ) is flatter than the sensitivity of the vibration sensor including one elastic element in the second direction (curve 1030 in FIG. 10 ).

Based on the above curve analysis, it can be known that by setting the first elastic element and the second elastic element which are approximately symmetrical in the vibration sensor, it is possible to achieve in a specific frequency band (for example, below 3000 Hz), under the premise of substantially not changing the sensitivity of the vibration sensor in the first direction while reducing the sensitivity of the vibration sensor in the second direction, thereby increasing the difference between the sensitivity of the vibration sensor in the second direction and the sensitivity of the vibration sensor in the first direction, improving the directional selectivity of the vibration sensor, and enhancing the anti-noise interference capability of the vibration sensor. In some embodiments, in order to further reduce the sensitivity in the second direction, within a specific frequency range (for example, below 3000 Hz), the ratio of the resonance frequency f6 corresponding to the resonance peak in the second direction in the vibration sensor having two approximately symmetrical elastic elements to the resonance frequency f5 corresponding to the resonance peak in the second direction in the vibration sensor having one elastic element may be greater than 2. In some embodiments, within a specific frequency range (for example, below 3000 Hz), the ratio of the resonance frequency f6 corresponding to the resonance peak in the second direction in the vibration sensor having two approximately symmetrical elastic elements to the resonance frequency f5 corresponding to the resonance peak in the second direction in the vibration sensor having one elastic element may be greater than 3.5. In some embodiments, within a specific frequency range (for example, below 3000 Hz), a ratio of a resonance frequency f6 corresponding to a resonance peak in the second direction of a vibration sensor having two approximately symmetrical elastic elements to a resonance frequency f5 corresponding to a resonance peak in the second direction of the vibration sensor having two approximately symmetrical elastic elements may be greater than 5. In some embodiments, a ratio of a resonance frequency f6 corresponding to a resonance peak in the second direction of a vibration sensor having two approximately symmetrical elastic elements to a resonance frequency f2 corresponding to a resonance peak in the first direction of the vibration sensor having two approximately symmetrical elastic elements may be greater than 1. Preferably, the resonance frequency f6 corresponding to the resonance peak in the second direction of the vibration sensor having two approximately symmetrical elastic elements and the resonance frequency f2 corresponding to the resonance peak in the first direction can be greater than 1.5. Further preferably, the resonance frequency f6 corresponding to the resonance peak in the second direction of the vibration sensor having two approximately symmetrical elastic elements and the resonance frequency f2 corresponding to the resonance peak in the first direction can be greater than 2.

FIG. 11 is a dynamic analog diagram of a vibration sensor according to some embodiments of the present specification; FIG. 12 is a dynamic analog diagram of a vibration sensor according to some embodiments of the present specification. FIG. 11 (a) shows the displacement of a mass element vibrating in a first direction in a vibration sensor including an elastic element, wherein the resonant frequency of the vibration sensor in the first direction is 1678.3 Hz. FIG. 11 (b) shows the displacement of a mass element vibrating in a second direction in a vibration sensor including an elastic element, wherein the resonant frequency of the vibration sensor in the second direction is 2372.2 Hz. FIG. 12 (a) shows the displacement of a mass element vibrating in a first direction in a vibration sensor including two approximately symmetrical elastic elements, wherein the resonant frequency of the vibration sensor in the first direction is 1678 Hz. (b) in Figure 12 shows the displacement of the mass element vibrating in the second direction in a vibration sensor including two approximately symmetrical elastic elements, wherein the resonant frequency of the vibration sensor in the second direction is 14795 Hz. It should be noted that in Figures 11 and 12, except for the different thicknesses of the elastic elements, the length, width, and thickness of the elastic elements and the length, width, and thickness of the mass element are the same.

Referring to Fig. 11, the resonant frequency (1678.3 Hz) of the vibration sensor including an elastic element in the first direction and the resonant frequency (2372.2 Hz) of the vibration sensor including an elastic element in the second direction are both within the target frequency range (e.g., 0 Hz-3000 Hz). Therefore, the vibration signal of the mass element in the second direction has a greater impact on the electrical signal finally output by the vibration sensor. Referring to Figure 12, the resonant frequency (1678 Hz) of the vibration sensor including two approximately symmetrical elastic elements in the first direction is within the target frequency range (e.g., 0 Hz-3000 Hz), and the resonant frequency (14795 Hz) of the vibration sensor including two approximately symmetrical elastic elements in the second direction is much higher than the target frequency. Therefore, the vibration signal of the mass element in the second direction has less influence on the electrical signal finally output by the vibration sensor.

In some embodiments, the displacement of the mass element is related to the resonant frequency of the vibration sensor in the first direction and/or the second direction. Specifically, the displacement of the mass element is inversely proportional to the square of the resonant frequency of the vibration sensor in the first direction and/or the second direction. In other words, the higher the resonant frequency of the vibration sensor in the first direction and/or the second direction, the smaller the displacement of the mass element in the first direction and/or the second direction. In some embodiments, the smaller the displacement of the mass element in the first direction and/or the second direction, the smaller the impact on the output electrical signal of the vibration sensor. Therefore, in order to reduce the impact of the vibration signal of the mass element in the second direction on the output electrical signal of the vibration sensor, the displacement of the mass element in the second direction can be reduced, that is, the resonant frequency of the vibration sensor in the second direction can be increased. Comparing Figure 11 and Figure 12, the displacement of the mass element of the vibration sensor in Figure 12 in the second direction is smaller than the displacement of the mass element of the vibration sensor in Figure 11 in the second direction. Therefore, the sensitivity of the vibration sensor in Figure 12 in the second direction is lower than the sensitivity of the vibration sensor in Figure 11 in the second direction, that is, by setting two approximately symmetrical elastic elements in the vibration sensor, the sensitivity of the vibration sensor in the second direction can be reduced, thereby improving the directional selectivity of the vibration sensor and enhancing the anti-noise interference capability of the vibration sensor.

In some embodiments, the resonant frequency of the vibration sensor in the first direction and the second direction can be adjusted by adjusting the size (e.g., length, width) of the mass element. In some embodiments, the ratio of the resonant frequency of the vibration sensor in the second direction to the resonant frequency of the first direction can be changed by adjusting the size (e.g., length, width) of the mass element. In some embodiments, the ratio of the vibration frequency of the vibration sensor in the second direction to the vibration frequency in the first direction can be 1-2.5. Preferably, the ratio of the vibration frequency of the vibration sensor in the second direction to the vibration frequency in the first direction can also be 1.3-2.2. Further preferably, the ratio of the vibration frequency of the vibration sensor in the second direction to the vibration frequency in the first direction can also be 1.5-2. For details on adjusting the resonant frequency and ratio of the vibration sensor in the first direction and the second direction by adjusting the size of the mass element, please refer to Figure 13 and its related description.

FIG13 is a harmonic frequency diagram of a vibration unit according to some embodiments of the present specification. As shown in FIG13 , the horizontal axis represents the length of the mass element, in mm, and the vertical axis represents the frequency corresponding to mass elements of different lengths, in Hz. The vibration sensor 300 in FIG3 is used as an example for illustration. Here, the mass element 3201 in the vibration unit 320 has a width of 1.5 mm and a thickness of 0.3 mm, and the elastic element 3202 of the vibration unit 320 has a length of 3 mm, a width of 2 mm, and a thickness of 0.01 mm. Curve 1310 represents the harmonic frequency of the vibration sensor 300 in the first direction, and curve 1320 represents the harmonic frequency of the vibration sensor 300 in the second direction. Referring to curve 1310 in FIG. 13 , when the length of mass element 3201 is in the range of 0.6 mm to 0.8 mm, the resonant frequency of vibration sensor 300 in the first direction decreases as the length of mass element 3201 increases. Referring to curve 1320 in FIG. 13 , when the length of mass element 3201 is in the range of 0.6 mm to 1.2 mm, the resonant frequency of vibration sensor 300 in the second direction decreases as the length of mass element 931 increases. When the length of mass element 3201 is in the range of 1.2 mm to 2.4 mm, the resonant frequency of vibration sensor 300 in the first direction increases as the length of mass element 3201 increases. When the length of the mass element 3201 is in the range of 1.4 mm to 2.4 mm, the resonant frequency of the vibration sensor 300 in the second direction increases with the increase in the length of the mass element 3201. In some embodiments, the ratio of the resonant frequency of the vibration sensor 300 in the second direction to the resonant frequency in the first direction can be changed with the length of the mass element 3201, that is, by adjusting the size (e.g., length, width) of the mass element 3201, the ratio of the resonant frequency of the vibration sensor 300 in the second direction to the resonant frequency in the first direction (also referred to as relative lateral sensitivity) can be changed. In some embodiments, the ratio of the resonant frequency of the vibration sensor in the second direction to the resonant frequency in the first direction may be 1-2.5. Preferably, the ratio of the resonant frequency of the vibration sensor in the second direction to the resonant frequency in the first direction may be 1.5-2.5. Further preferably, the ratio of the resonant frequency of the vibration sensor in the second direction to the resonant frequency in the first direction may be greater than 2. For example, in FIG13 , when the length of the mass element 3201 is about 0.2 mm, the resonant frequency of the vibration sensor 300 in the second direction is about 2200 Hz, the resonant frequency of the vibration sensor 300 in the first direction is about 1000 Hz, and the ratio of the resonant frequency of the vibration sensor 300 in the second direction to the resonant frequency in the first direction is about 2.2. Further, when the length of the mass element 3201 is about 0.8 mm, the resonant frequency of the vibration sensor 300 in the second direction is about 2000 Hz, the resonant frequency of the vibration sensor 300 in the first direction is about 800 Hz, and the ratio of the resonant frequency of the vibration sensor 300 in the second direction to the resonant frequency in the first direction is about 2.

By changing the size (length or width) of the mass element, the ratio of the resonant frequency of the vibration sensor in the second direction to the resonant frequency in the first direction changes. Here, the mass of the mass element and the rigidity of the elastic element will also change at the same time, thereby affecting the resonant frequency of the vibration sensor in the second direction and the resonant frequency in the first direction. In some embodiments, in order to reduce the sensitivity of the vibration sensor in the second direction within the target frequency range while ensuring that the sensitivity of the vibration sensor in the first direction does not change significantly, the ratio of the size of the mass element (for example, length or width) to the size of the elastic element can be 0.2~0.9. Preferably, the ratio of the size of the mass element to the size of the elastic element can be 0.3~0.7. Further preferably, the ratio of the size of the mass element to the size of the elastic element may be 0.5-0.7. As a specific example only, for example, the size (e.g., length or width) of the mass element may be 1/2 of the size of the elastic element. For another example, the size (e.g., length or width) of the mass element may be 3/4 of the size of the elastic element.

FIG. 14 is a schematic diagram of a structure of a vibration sensor according to some embodiments of the present specification. As shown in FIG. 14 , a vibration sensor 1400 may include a housing structure 1410, an acoustic transducer, and a vibration unit 1430. The vibration sensor 1400 shown in FIG. 14 may be the same as or similar to the vibration sensor 900 shown in FIG. 9 . For example, the housing structure 1410 of the vibration sensor 1400 may be the same as or similar to the housing structure 910 of the vibration sensor 900. For another example, the first acoustic cavity 1440 of the vibration sensor 1400 may be the same as or similar to the first acoustic cavity 940 of the vibration sensor 900. For another example, the substrate structure 1420 of the vibration sensor 1400 may be the same as or similar to the substrate structure 920 of the vibration sensor 900. For more information about the vibration sensor 1400 (e.g., the second acoustic cavity 1450, the through hole 1421, the mass element 1431, etc.), please refer to FIG. 9 and its related description.

In some embodiments, the main difference between the vibration sensor shown in FIG. 14 and the vibration sensor 900 shown in FIG. 9 is that the first elastic element 14321 and the second elastic element 14322 of the vibration sensor 1400 may be a columnar structure, and the first elastic element 14321 and the second elastic element 14322 may extend along the thickness direction of the mass element 1431 and be connected to the housing structure 1410 or the substrate structure 1420 on the upper surface of the acoustic transducer. In some embodiments, the first elastic element 14321 and the second elastic element 14322 may be approximately symmetrically distributed relative to the mass element 1431 in the first direction. In some embodiments, the first elastic element 14321 may be located on a side of the mass element 1431 facing away from the substrate structure 1420, the lower surface of the first elastic element 14321 may be connected to the upper surface of the mass element 1431, and the upper surface of the first elastic element 9321 may be connected to the inner wall of the housing structure 1410. In some embodiments, the second elastic element 14322 may be located on a side of the mass element 1431 facing the substrate structure 1420, the upper surface of the second elastic element 14322 may be connected to the lower surface of the mass element 1431, and the lower surface of the second elastic element 14322 may be connected to the substrate structure 1420 on the upper surface of the acoustic transducer. It should be noted that the columnar structure of the first elastic element 14321 and the second elastic element 14322 can be a regular and/or irregular structure such as a cylindrical shape or a square column shape, and the shapes of the first elastic element 14321 and the second elastic element 14322 can be adaptively adjusted according to the cross-sectional shape of the shell structure 1410.

In some embodiments, when the first elastic element 14321 and the second elastic element 14322 are columnar structures, the thickness of the mass element 1431 may be 10um~1000um. In some embodiments, the thickness of the mass element 1431 may be 4um~500um. In some embodiments, the thickness of the mass element 1431 may be 600um~1400um. In some embodiments, the thickness of the first elastic element 14321 and the second elastic element 14322 may be 10um~1000um. In some embodiments, the thickness of the first elastic element 14321 and the second elastic element 14322 may be 4um~500um. In some embodiments, the thickness of the first elastic element 14321 and the second elastic element 14322 may be 600um~1400um. In some embodiments, the difference between the thickness of each elastic element in the elastic element 1432 (for example, the first elastic element 14321 and the second elastic element 14322) and the thickness of the mass element 1431 may be 0um~500um. In some embodiments, the difference between the thickness of each elastic element in the elastic element 1432 and the thickness of the mass element 1431 may be 20um~400um. In some embodiments, the difference between the thickness of each elastic element in the elastic element 1432 and the thickness of the mass element 1431 may be 50um~200um. In some embodiments, the ratio of the thickness of each elastic element in the elastic element 1432 to the thickness of the mass element 1431 may be 0.01~100. In some embodiments, the ratio of the thickness of each elastic element in the elastic element 1432 to the thickness of the mass element 1431 may be 0.5 to 80. In some embodiments, the ratio of the thickness of each elastic element in the elastic element 1432 to the thickness of the mass element 1431 may be 1 to 40. In some embodiments, a gap 1460 may be provided between the outer side of the first elastic element 14321, the outer side of the second elastic element 14322, the outer side of the mass element 1431, and the housing structure 1410 or the acoustic transducer corresponding to the acoustic cavity. As shown in FIG. 14 , in some embodiments, the gap 1460 may be located around the mass element 1431. When the mass element 1431 vibrates in response to the vibration of the housing structure 1410, the gap 1460 may prevent the mass element 1431 from colliding with the housing structure 1410 during vibration. In some embodiments, the gap 1460 may include a filler. For more description of the filler, please refer to FIG. 9 and its related description, which will not be elaborated here.

FIG. 15 is a schematic diagram of a structure of a vibration sensor according to some embodiments of the present specification. As shown in FIG. 15 , a vibration sensor 1500 may include a housing structure 1510, an acoustic transducer, and a vibration unit 1530. The vibration sensor 1500 shown in FIG. 15 may be the same as or similar to the vibration sensor 900 shown in FIG. 9 . For example, the housing structure 1510 of the vibration sensor 1500 may be the same as or similar to the housing structure 910 of the vibration sensor 900. For another example, the first acoustic cavity 1540 of the vibration sensor 1500 may be the same as or similar to the first acoustic cavity 940 of the vibration sensor 900. For another example, the substrate structure 1520 of the vibration sensor 1500 may be the same as or similar to the substrate structure 920 of the vibration sensor 900. For more information about the vibration sensor 1500 (e.g., the second acoustic cavity 1550, the through hole 1521, the mass element 1531, etc.), please refer to FIG. 9 and its related description.

In some embodiments, unlike the vibration sensor 900, the first elastic element 15321 of the vibration sensor 1500 may include a first sub-elastic element 153211 and a second sub-elastic element 153212. The first sub-elastic element 153211 and the shell structure 1510 corresponding to the acoustic cavity are connected through the second sub-elastic element 153212, and the first sub-elastic element 153211 is connected to the upper surface of the mass element 1531. As shown in FIG15 , the upper surface of the mass element 1531 is connected to the lower surface of the first sub-elastic element 153211, the upper surface of the first sub-elastic element 153211 is connected to the lower surface of the second sub-elastic element 153212, and the upper surface of the second sub-elastic element 153212 is connected to the inner wall of the shell structure 1510. In some embodiments, the periphery of the first sub-elastic element 153211 and the periphery of the second sub-elastic element 153212 may overlap or approximately overlap. In some embodiments, the second elastic element 15322 of the vibration sensor 1500 may include a third sub-elastic element 153221 and a fourth sub-elastic element 153222. The third sub-elastic element 153221 and the acoustic transducer corresponding to the acoustic cavity are connected through the fourth sub-elastic element 153222, and the third sub-elastic element 153221 is connected to the lower surface of the mass element 1531. As shown in FIG15, the lower surface of the mass element 1531 is connected to the upper surface of the third sub-elastic element 153221, the lower surface of the third sub-elastic element 153221 is connected to the upper surface of the fourth sub-elastic element 153222, and the lower surface of the fourth sub-elastic element 153222 is connected to the acoustic transducer through the substrate structure 1520 on the upper surface of the acoustic transducer. In some embodiments, the periphery of the third sub-elastic element 153221 and the periphery of the fourth sub-elastic element 153222 may overlap or approximately overlap.

In some embodiments, the periphery of the first sub-elastic element 153211 and the periphery of the second sub-elastic element 153212 (or the periphery of the third sub-elastic element 153221 and the periphery of the fourth sub-elastic element 153222) may not overlap. For example, when the first sub-elastic element 153211 is a membrane structure and the second sub-elastic element 153212 is a columnar structure, the periphery of the first sub-elastic element 153211 may be connected to the inner wall of the shell structure 1510, and there may be a gap between the periphery of the second sub-elastic element 153212 and the inner wall of the shell structure 1510.

In some embodiments, the first sub-elastic element 153211 and the third sub-elastic element 153221 may be approximately symmetrically distributed with respect to the mass element 1531 in the first direction. The size, shape, material, or thickness of the first sub-elastic element 153211 and the third sub-elastic element 153221 may be the same. In some embodiments, the second sub-elastic element 153212 and the fourth sub-elastic element 153222 may be approximately symmetrically distributed with respect to the mass element 1531 in the first direction. The size, shape, material, or thickness of the second sub-elastic element 153212 and the fourth sub-elastic element 153222 may be the same. In some embodiments, the size, shape, material, or thickness of the first sub-elastic element 153211 and the second sub-elastic element 153212 (or the third sub-elastic element 153221 and the fourth sub-elastic element 153222) may be the same. For example, the material of the first sub-elastic element 153211 and the second sub-elastic element 153212 is polytetrafluoroethylene. In some embodiments, the size, shape, material, or thickness of the first sub-elastic element 153211 and the second sub-elastic element 153212 (or the third sub-elastic element 153221 and the fourth sub-elastic element 153222) may be different. For example, the first sub-elastic element 153211 is a membrane structure, and the second sub-elastic element 153212 is a columnar structure.

In some embodiments, the vibration sensor 1500 may further include a fixing plate 1570. The fixing plate 1570 may be distributed along the periphery of the mass element 1531, the fixing plate 1570 may be located between the first sub-elastic element 153211 and the third sub-elastic element 153221, and the upper surface and the lower surface of the fixing plate 1570 may be connected to the first sub-elastic element 153211 and the third sub-elastic element 153221, respectively. In some embodiments, the fixing plate 1570 may be an independent structure. For example, the fixing plate 1570 may be a columnar structure having a thickness approximately the same as that of the mass element 1531, the upper surface of the fixing plate 1570 may be connected to the lower surface of the first sub-elastic element 153211, and the lower surface of the fixing plate 1570 may be connected to the upper surface of the third sub-elastic element 153221. In some embodiments, the fixing piece 1570 may also be a structure integrally formed with other structures. For example, the fixing piece 1570 may be a columnar structure integrally formed with the first sub-elastic element 153211 and/or the third sub-elastic element 153221. In some embodiments, the fixing piece 1570 may also be a columnar structure penetrating the first sub-elastic element 153211 and/or the third sub-elastic element 153221. For example, the fixing piece 1570 may penetrate the first sub-elastic element 153211 and be connected to the second sub-elastic element 153212. In some embodiments, the structure of the fixing piece 1570 may be other types of structures in addition to the columnar structure, for example, a ring structure, etc. In some embodiments, when the fixing piece 1570 is a ring-shaped structure, the fixing piece 1570 is evenly distributed around the mass element 1531, the upper surface of the fixing piece 1570 is connected to the lower surface of the first sub-elastic element 153211, and the lower surface of the fixing piece 1570 is connected to the upper surface of the third sub-elastic element 153221.

In some embodiments, the thickness of the fixing plate 1570 may be the same as the thickness of the mass element 1531. In some embodiments, the thickness of the fixing plate 1570 may be different from the thickness of the mass element 1531. For example, the thickness of the fixing plate 1570 may be greater than the thickness of the mass element 1531. In some embodiments, the material of the fixing plate 1570 may be an elastic material, such as foam, plastic, rubber, silicone, etc. In some embodiments, the material of the fixing plate 1570 may also be a rigid material, such as metal, metal alloy, etc. Preferably, the material of the fixing plate 1570 may be the same as the material of the mass element 1531. In some embodiments, the fixing plate 1570 can realize the fixing effect of the gap 1560, and the fixing plate 1570 can also serve as an additional mass element to adjust the resonant frequency of the vibration sensor, thereby adjusting (for example, reducing) the difference between the sensitivity of the vibration sensor in the second direction and the sensitivity of the vibration sensor in the first direction.

In some embodiments, there may be a gap 1560 between the fixing plate 1570, the mass element 1531, the first sub-elastic element 153211, and the second sub-elastic element 153212. In some embodiments, there may also be a gap 1560 between the side of the elastic element 1532, the side of the fixing plate 1570, the inner wall of the shell structure 1510, and the acoustic transducer. In some embodiments, when the mass element 1531 vibrates in response to the vibration of the shell structure 1510, the gap 1560 can prevent the mass element 1531 from colliding with the shell structure 1510 when vibrating. In some embodiments, the gap 1560 may include a filler, and more descriptions of the filler can refer to FIG. 9 and its related descriptions, which are not repeated here.

FIG. 16 is a schematic diagram of a structure of a vibration sensor according to some embodiments of the present specification. As shown in FIG. 16 , a vibration sensor 1600 may include a housing structure 1610, an acoustic transducer, and a vibration unit 1630. The vibration sensor 1600 shown in FIG. 16 may be the same or similar to the vibration sensor 900 shown in FIG. 9 . For example, the housing structure 1610 of the vibration sensor 1600 may be the same or similar to the housing structure 910 of the vibration sensor 900. For another example, the first acoustic cavity 1640 of the vibration sensor 1600 may be the same or similar to the first acoustic cavity 940 of the vibration sensor 900. For another example, the substrate structure 1620 of the vibration sensor 1600 may be the same or similar to the substrate structure 920 of the vibration sensor 900. For more information about the vibration sensor 1600 (e.g., the second acoustic cavity 1650, the through hole 1621, the acoustic transducer, etc.), please refer to FIG. 9 and its related description.

In some embodiments, the vibration sensor 1600 is different from the vibration sensor 900 in that the structure of the vibration unit is different. The vibration unit 1630 of the vibration sensor 1600 may include at least one elastic element 1632 and two mass elements (e.g., a first mass element 16311 and a second mass element 16312). In some embodiments, the mass element 1631 may include a first mass element 16311 and a second mass element 16312. The first mass element 16311 and the second mass element 16312 are symmetrically arranged relative to the at least one elastic element 1632 in the first direction. In some embodiments, the first mass element 16311 may be located on a side of at least one elastic element 1632 facing away from the substrate structure 1620, and the lower surface of the first mass element 16311 is connected to the upper surface of at least one elastic element 1632. The second mass element 16312 may be located on a side of at least one elastic element 1632 facing the substrate structure 1620, and the upper surface of the second mass element 16312 is connected to the lower surface of at least one elastic element 1632. In some embodiments, the size, shape, material, or thickness of the first mass element 16311 and the second mass element 16312 may be the same. In some embodiments, the first mass element 16311 and the second mass element 16312 are symmetrically arranged relative to at least one elastic element 1632 in the first direction, so that the center of gravity of the mass element 1631 and the centroid of at least one elastic element 1632 can be approximately coincident, so that when the vibration unit 1630 vibrates in response to the vibration of the housing structure 1610, the vibration of the mass element 1631 in the second direction can be reduced, thereby reducing the response sensitivity of the vibration unit 1630 to the vibration of the housing structure 1610 in the second direction, thereby improving the directional selectivity of the vibration sensor 1600.

In some embodiments, the first mass element 16311 and the second mass element 16312 are distributed on opposite sides of at least one elastic element 1632 in a first direction. Here, the first mass element 16311 and the second mass element 16312 can be approximately regarded as an integral mass element, and the center of gravity of the integral mass element approximately coincides with the centroid of at least one elastic element 1632, so that within the target frequency range (for example, below 3000 Hz), the response sensitivity of the vibration unit 1630 to the vibration of the shell structure 1610 in the first direction is higher than the response sensitivity of the vibration unit 1630 to the vibration of the shell structure 1610 in the second direction. In some embodiments, the difference between the response sensitivity of the vibration unit 1630 to the vibration of the shell structure 1610 in the second direction and the response sensitivity of the vibration unit 1630 to the vibration of the shell structure 1610 in the first direction may be -20dB~-60dB. In some embodiments, the difference between the response sensitivity of the vibration unit 1630 to the vibration of the shell structure 1610 in the second direction and the response sensitivity of the vibration unit 1630 to the vibration of the shell structure 1610 in the first direction may be -25dB~-50dB. In some embodiments, the difference between the response sensitivity of the vibration unit 1630 to the vibration of the shell structure 1610 in the second direction and the response sensitivity of the vibration unit 1630 to the vibration of the shell structure 1610 in the first direction can be -30dB~-40dB.

In some embodiments, during the operation of the vibration sensor 1600, the vibration generated by the vibration unit 1630 in the second direction can be reduced, thereby reducing the response sensitivity of the vibration unit 1630 to the vibration of the housing structure 1610 in the second direction, thereby improving the directional selectivity of the vibration sensor 1600 and reducing the interference of noise signals on sound signals.

In some embodiments, the centroid of at least one elastic element 1632 may coincide with or approximately coincide with the center of gravity of the mass element 1631. In some embodiments, when the vibration unit 1630 vibrates in response to the vibration of the housing structure 1610, the centroid of at least one elastic element 1632 coincides with or approximately coincides with the center of gravity of the mass element 1631, and the vibration of the mass element 1631 in the second direction may be reduced while the response sensitivity of the vibration unit 1630 to the vibration of the housing structure 1610 in the first direction remains substantially unchanged, thereby reducing the response sensitivity of the vibration unit 1630 to the vibration of the housing structure 1610 in the second direction, thereby improving the directional selectivity of the vibration sensor 1600. In some embodiments, the response sensitivity of the vibration unit 1630 to the vibration of the shell structure 1610 in the first direction can be changed (for example, improved) by adjusting the thickness, elastic coefficient of the elastic element 1632, the mass and size of the mass element 1631, etc.

In some embodiments, the distance between the centroid of at least one elastic element 1632 and the center of gravity of the mass element 1631 in the first direction may be no greater than 1/3 of the thickness of the mass element 1631. In some embodiments, the distance between the centroid of at least one elastic element 1632 and the center of gravity of the mass element 1631 in the first direction may be no greater than 1/2 of the thickness of the mass element 1631. In some embodiments, the distance between the centroid of at least one elastic element 1632 and the center of gravity of the mass element 1631 in the first direction may be no greater than 1/4 of the thickness of the mass element 1631. In some embodiments, the distance between the centroid of at least one elastic element 1632 and the center of gravity of the mass element 1631 in the second direction may be no greater than 1/3 of the side length or radius of the mass element 1631. In some embodiments, the distance between the centroid of at least one elastic element 1632 and the center of gravity of the mass element 1631 in the second direction is not greater than 1/2 of the side length or radius of the mass element 1631. In some embodiments, the distance between the centroid of at least one elastic element 1632 and the center of gravity of the mass element 1631 in the second direction is not greater than 1/4 of the side length or radius of the mass element 1631. For example, when the mass element 1631 is a cube, the distance between the centroid of at least one elastic element 1632 and the center of gravity of the mass element 1631 in the second direction is not greater than 1/3 of the side length of the mass element 1631. For another example, when the mass element 1631 is a cylinder, the distance between the centroid of at least one elastic element 1632 and the center of gravity of the mass element 1631 in the second direction is no more than 1/3 of the circular radius of the upper surface (or lower surface) of the mass element 1631.

In some embodiments, when the centroid of at least one elastic element 1632 coincides or approximately coincides with the center of gravity of the mass element 1631, the harmonic frequency of the vibration unit 1630 vibrating in the second direction can be shifted to a high frequency without changing the harmonic frequency of the vibration unit 1630 vibrating in the first direction. In some embodiments, when the centroid of at least one elastic element 1632 coincides or approximately coincides with the center of gravity of the mass element 1631, the harmonic frequency of the vibration unit 1630 vibrating in the first direction can remain substantially unchanged, for example, the harmonic frequency of the vibration unit 1630 vibrating in the first direction can be a frequency within a relatively strong frequency range perceived by the human ear (for example, 20 Hz-2000 Hz, 2000 Hz-3000 Hz, etc.). The harmonic frequency of the vibration unit 1630 vibrating in the second direction may be shifted toward high frequencies and located in a frequency range (e.g., 5000 Hz-9000 Hz, 1 kHz-14 kHz, etc.) where human ear perception is relatively weak. Based on the shift of the harmonic frequency of the vibration unit 1630 vibrating in the second direction toward high frequencies, the harmonic frequency of the vibration unit 1630 vibrating in the first direction remains substantially unchanged, and the ratio of the harmonic frequency of the vibration unit 1630 vibrating in the second direction to the harmonic frequency of the vibration unit 1630 vibrating in the first direction may be greater than or equal to 2. In some embodiments, the ratio of the harmonic frequency of the vibration unit 1630 vibrating in the second direction to the harmonic frequency of the vibration unit 1630 vibrating in the first direction may also be greater than or equal to other values. For example, the ratio of the harmonic frequency of the vibration unit 1630 vibrating in the second direction to the harmonic frequency of the vibration unit 1630 vibrating in the first direction may also be greater than or equal to 1.5.

FIG. 17 is a schematic diagram of a structure of a vibration sensor according to some embodiments of the present specification. As shown in FIG. 17 , a vibration sensor 1700 may include a housing structure 1710, an acoustic transducer, and a vibration unit 1730. The vibration sensor 1700 shown in FIG. 17 may be the same or similar to the vibration sensor 1600 shown in FIG. 16 . For example, the housing structure 1710 of the vibration sensor 1700 may be the same or similar to the housing structure 1610 of the vibration sensor 1600. For another example, the first acoustic cavity 1740 of the vibration sensor 1700 may be the same or similar to the first acoustic cavity 1640 of the vibration sensor 1600. For another example, the acoustic transducer of the vibration sensor 1700 may be the same or similar to the acoustic transducer of the vibration sensor 1600. For more structures of the vibration sensor 1700 (e.g., the second acoustic cavity 1750, the through hole 1721, the mass element 1731, the first mass element 17311, the second mass element 17312, etc.), please refer to FIG. 16 and its related description.

Unlike the vibration sensor 1600, the elastic element 1732 of the vibration sensor 1700 may further include a second elastic element 17322 and a third elastic element 17323. In some embodiments, the first elastic element 17321 may be connected to the housing structure 1710 and/or the acoustic transducer through the second elastic element 17322 and the third elastic element 17323, respectively. As shown in FIG. 17 , the first elastic element 17321 is a membrane structure, and the second elastic element 17322 and the third elastic element 17323 are columnar structures. The upper surface of the first elastic element 17321 is connected to the lower surface of the second elastic element 17322, and the upper surface of the second elastic element 17322 is connected to the inner wall of the housing structure 1710. The lower surface of the first elastic element 17321 is connected to the upper surface of the third elastic element 17323, and the lower surface of the third elastic element 17323 is connected to the acoustic transducer through the substrate structure 1720 on the upper surface of the acoustic transducer. In some embodiments, the peripheries of the first elastic element 17321, the second elastic element 17322, and the third elastic element 17323 may overlap or approximately overlap. In some embodiments, the peripheries of the first elastic element 17321, the second elastic element 17322, and the third elastic element 17323 may not overlap. For example, when the first elastic element 17321 is a membrane structure, and the second elastic element 17322 and the third elastic element 17323 are columnar structures, the periphery of the first elastic element 17321 can be connected to the inner wall of the shell structure 1710, and there is a gap between the periphery of the second elastic element 17322 and the third elastic element 17323 and the inner wall of the shell structure 1710.

In some embodiments, the structures of the first elastic element 17321, the second elastic element 17322 and the third elastic element 17323 may also be the same. For example, the first elastic element 17321, the second elastic element 17322 and the third elastic element 17323 are all membrane structures. In some embodiments, the materials of the first elastic element 17321, the second elastic element 17322 and the third elastic element 17323 may be the same. In some embodiments, the materials of the first elastic element 17321, the second elastic element 17322 and the third elastic element 17323 may be different.

In some embodiments, there may be a gap 1760 between the outer side of the first elastic element 17321, the outer side of the second elastic element 17322, the outer side of the third elastic element 17323 and the shell structure 1710 or the acoustic transducer corresponding to the acoustic cavity. In some embodiments, when the mass element 1731 vibrates in response to the vibration of the shell structure 1710, the gap 1760 can prevent the mass element 1731 from colliding with the shell structure 1710. In some embodiments, the gap 1760 may include a filler, and the specific description of the filler can refer to Figure 9 and its related content, which will not be repeated here.

It should be noted that the vibration unit of the vibration sensor shown in the embodiments of this specification (for example, the vibration unit 830 shown in Figure 8, the vibration unit 930 shown in Figure 9, the vibration unit 1430 shown in Figure 14, etc.) is set in a horizontal direction. In some embodiments, the setting direction of the vibration unit can also be set in other directions (for example, longitudinally or obliquely). Correspondingly, the first direction and the second direction change with the change of the mass element (for example, the mass element 831 shown in Figure 8, the mass element 931 shown in Figure 9, the mass element 1431 shown in Figure 14, etc.). For example, when the vibration unit 830 (mass element 831) of the vibration sensor 800 is disposed longitudinally, it can be approximately regarded as the vibration unit 830 shown in FIG8 being rotated 90° in the clockwise (or counterclockwise) direction as a whole. Correspondingly, the first direction and the second direction also change with the rotation of the vibration unit 830. The working principle of the vibration sensor when the vibration unit is disposed longitudinally is similar to the working principle of the vibration sensor when the vibration unit is disposed transversely, and will not be elaborated here.

The beneficial effects that may be brought about by the embodiments of this specification include but are not limited to: (1) by providing at least one elastic element in the vibration sensor that is approximately symmetrically distributed with respect to the mass element in the first direction, or providing at least one mass element in the vibration sensor that is approximately symmetrically distributed with respect to the elastic element in the first direction, the distance between the center of gravity of the mass element and the centroid of the at least one elastic element is limited to a specific range (for example, the distance between the centroid of the at least one elastic element and the center of gravity of the mass element in the first direction is not greater than the distance between the centroid of the at least one elastic element and the mass element); (1/3 of the thickness of the mass element), thereby reducing the sensitivity of the vibration sensor in the second direction, thereby improving the directional selectivity of the vibration sensor and enhancing the anti-noise interference capability of the vibration sensor; (2) by providing at least one elastic element in the vibration sensor that is approximately symmetrically distributed relative to the mass element in the first direction, the force exerted on the mass element by at least one elastic element can be approximately symmetrical, thereby improving the stability and reliability of the vibration sensor, thereby improving the anti-shock capability of the vibration sensor. It should be noted that different embodiments may produce different beneficial effects. In different embodiments, the beneficial effects that may be produced may be any one or a combination of the above, or any other beneficial effects that may be obtained.

The above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

800: Vibration sensor

810: Shell structure

811:Acoustic transducer

820:Acoustic transducer

830: Vibration unit

831:Mass element

832: Elastic element

840: The first acoustic cavity

850: Second acoustic cavity

8321: First elastic element

8322: Second elastic element

Claims (10)

A vibration sensor, the vibration sensor comprising: a shell structure and an acoustic transducer, the acoustic transducer being physically connected to the shell structure, wherein at least a portion of the shell structure and the acoustic transducer form an acoustic cavity; a vibration unit, which divides the acoustic cavity into a plurality of acoustic cavities including a first acoustic cavity, the first acoustic cavity being acoustically connected to the acoustic transducer, the vibration unit comprising at least one elastic element and a mass element, the at least one elastic element and the mass element being located in the acoustic cavity, the mass element being connected to the shell structure or the acoustic transducer via the at least one elastic element; the shell structure being configured to generate vibration based on an external vibration signal, the vibration unit In response to the vibration of the housing structure, the volume of the first acoustic cavity changes, and the acoustic transducer generates an electrical signal based on the change in the volume of the first acoustic cavity, wherein the at least one elastic element is distributed on opposite sides of the mass element in a first direction, so that within a target frequency range, the response sensitivity of the vibration unit to the vibration of the housing structure in the first direction is higher than the response sensitivity of the vibration unit to the vibration of the housing structure in a second direction, and the second direction is perpendicular to the first direction; the ratio of the harmonic frequency of the vibration unit vibrating in the second direction to the harmonic frequency of the vibration unit vibrating in the first direction is greater than or equal to 2. As in claim 1, the vibration sensor, wherein the difference between the response sensitivity of the vibration unit to the vibration of the shell structure in the second direction and the response sensitivity of the vibration unit to the vibration of the shell structure in the first direction is -20dB~-40dB. The vibration sensor of claim 1, wherein the first direction is the thickness direction of the mass element, the distance between the centroid of the at least one elastic element and the center of gravity of the mass element in the first direction is no more than 1/3 of the thickness of the mass element, and the distance between the centroid of the at least one elastic element and the center of gravity of the mass element in the second direction is no more than 1/3 of the side length or radius of the mass element. As in the vibration sensor of claim 1, the at least one elastic element includes a first elastic element and a second elastic element, the first elastic element and the second elastic element are connected to the shell structure or the acoustic transducer corresponding to the acoustic cavity; the first elastic element and the second elastic element are approximately symmetrically distributed relative to the mass element in the first direction, wherein the first direction is the thickness direction of the mass element, the upper surface of the mass element is connected to the first elastic element, and the lower surface of the mass element is connected to the second elastic element. As in the vibration sensor of claim 4, the first elastic element and the second elastic element are membrane structures, and the size of the upper surface or the lower surface of the mass element is smaller than the size of the first elastic element and the second elastic element. As in claim 5, the vibration sensor has a gap between the first elastic element, the second elastic element, the mass element and the shell structure or the acoustic transducer corresponding to the acoustic cavity, and the gap has a filler for adjusting the quality factor of the vibration sensor. As in claim 4, the first elastic element and the second elastic element are columnar structures, and the first elastic element and the second elastic element extend along the thickness direction of the mass element and are connected to the shell structure. As in claim 7, the vibration sensor has a gap between the outer side of the first elastic element, the outer side of the second elastic element, the outer side of the mass element, and the shell structure or the acoustic transducer corresponding to the acoustic cavity, and the gap has a filler for adjusting the quality factor of the vibration sensor. The vibration sensor of claim 4, wherein the first elastic element includes a first sub-elastic element and a second sub-elastic element, the first sub-elastic element is connected to the shell structure corresponding to the acoustic cavity or the acoustic transducer through the second sub-elastic element, and the first sub-elastic element is connected to the upper surface of the mass element; the second elastic element includes a third sub-elastic element and a fourth sub-elastic element, the third sub-elastic element is connected to the shell structure corresponding to the acoustic cavity or the acoustic transducer through the fourth sub-elastic element, and the third sub-elastic element is connected to the lower surface of the mass element. A vibration sensor, the vibration sensor comprising: a shell structure and an acoustic transducer, the acoustic transducer being physically connected to the shell structure, wherein at least a portion of the shell structure and the acoustic transducer form an acoustic cavity; a vibration unit, which divides the acoustic cavity into a plurality of acoustic cavities including a first acoustic cavity, the first acoustic cavity being acoustically connected to the acoustic transducer, the vibration unit comprising at least one elastic element and a mass element, the at least one elastic element and the mass element being located in the acoustic cavity, the mass element being connected to the shell structure or the acoustic transducer via the at least one elastic element; the shell structure being configured to generate vibration based on an external vibration signal, the vibration unit In response to the vibration of the shell structure, the volume of the first acoustic cavity changes, and the acoustic transducer generates an electrical signal based on the change in the volume of the first acoustic cavity; wherein the at least one mass element is distributed on opposite sides of the elastic element in a first direction, so that within a target frequency range, the response sensitivity of the vibration unit to the vibration of the shell structure in the first direction is higher than the response sensitivity of the vibration unit to the vibration of the shell structure in a second direction, and the second direction is perpendicular to the first direction; the ratio of the harmonic frequency of the vibration unit vibrating in the second direction to the harmonic frequency of the vibration unit vibrating in the first direction is greater than or equal to 2.

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