Audio capture method, microphone, and electronic device

Abstract

The present application provides a sound capture method applied to a microphone. The microphone comprises a laser self-mixing device and a diaphragm device, the diaphragm device comprises a membrane configured to respond to sound vibration, and the laser self-mixing device and the diaphragm device are separately configured to detect the vibration of the membrane. In the method, a first voltage signal is obtained using the laser self-mixing device, and a second voltage signal is simultaneously obtained using the diaphragm device. If the first voltage signal is equal to or less than a preset threshold, the first voltage signal is converted into an audio signal, or if the first voltage signal is greater than a preset threshold, the second voltage signal is converted into an audio signal. According to the method of the present application, the audio signal may be collected in two different manners, so that the switching between the two signals is realized using a preset threshold, and the more consistent signal is selected and converted into an audio signal. This can ensure the quality of the audio signal. The present application further relates to a microphone and an electronic device.

Description

[Technical Field]

[0001] This application claims priority to Chinese Patent Application No. 202111276854.9, entitled "Audio Capture Method, Microphone, and Electronic Device," filed with the State Intellectual Property Office of China on October 29, 2021, which is incorporated herein by reference in its entirety.

[0002] The present application relates to the field of electronic devices, and in particular to sound capture methods, microphones, and electronic devices that use sound capture methods or that include microphones. [Background technology]

[0003] There are many scenarios in which electronic devices use microphones for sound collection, such as phone calls, video calls, voice assistants, remote meetings, large-scale live streaming, and online classes, all of which require microphones to extract audio signals. The signal-to-noise ratio of existing microphones typically does not exceed 70 dB. However, as usage requirements continue to increase, in some scenarios, the signal-to-noise ratio of microphones needs to be increased to 80 dB or more. As a result, it is difficult for existing microphones to meet the performance requirements. Summary of the Invention

[0004] The present application provides a sound capturing method for improving the pickup signal-to-noise ratio of a microphone. The present application further relates to a microphone and an electronic device. Specifically, the present application includes the following technical solutions: [Means for solving the problem]

[0005] According to a first aspect, the present application provides a sound capture method applied to a microphone, the microphone comprising a laser self-mixing device and a diaphragm device, the diaphragm device comprising a membrane, the membrane configured to respond to sound vibrations, the laser self-mixing device and the diaphragm device separately configured to detect vibrations of the membrane. The method comprises: simultaneously obtaining a first voltage signal using a laser self-mixing device and a second voltage signal using a diaphragm device; converting the first voltage signal into an audio signal if the first voltage signal is equal to or less than a preset threshold, or converting the second voltage signal into an audio signal if the first voltage signal is greater than the preset threshold. Includes:

[0006] The audio capture method in this application corresponds to a microphone including both a laser self-mixing device and a diaphragm device. A first voltage signal may be acquired using the laser self-mixing device, and a second voltage signal may be acquired using the diaphragm device. The first voltage signal and the second voltage signal are signals acquired by the laser self-mixing device and the diaphragm device, respectively, based on the membrane's response to external audio vibrations. The first voltage signal is then compared with a preset threshold to select whether to convert the first voltage signal or the second voltage signal into an audio signal.

[0007] The laser self-mixing device has a relatively high sensitivity for detecting sound vibrations and can respond to sound vibrations with low sound pressure. As a result, the response range and signal-to-noise ratio of the sound capture method in the present application are increased. In addition, the acoustic overload point of the diaphragm device is relatively high. When the diaphragm device is used in a scenario with vibrations of relatively high sound pressure, a better sound capture effect can be provided. Therefore, according to the sound capture method, a predetermined threshold is set, so that the laser self-mixing device and the diaphragm device can complement each other and collect audio signals in each of the relatively desirable operating scenarios to ensure the sound collection effect of the sound capture method in the present application.

[0008] In a possible embodiment, the laser self-mixing device comprises a transmitter and a receiver, and the step of obtaining the first voltage signal using the laser self-mixing device includes: controlling a transmitter to emit laser light toward the film; receiving the laser light from the membrane using a receiver and forming a first current signal; modulating the first current signal into a first voltage signal; Includes:

[0009] In this embodiment, the laser self-mixing device emits laser light toward the membrane to form a first current signal, and receives the laser light reflected by the membrane. The laser light reflected by the membrane may further form a self-mixing interference effect with a portion of the laser light in the back cavity to carry vibration information of the membrane, so that the first voltage signal converted from the first current signal can also carry vibration information.

[0010] In a possible embodiment, the laser self-mixing device further comprises a transimpedance amplifier and an operational amplifier, and the step of modulating the first current signal into the first voltage signal comprises: converting the first current signal into a first modulated voltage signal using a transimpedance amplifier; amplifying the first modulated voltage signal using an operational amplifier; filtering the amplified first modulated voltage signal to form a first voltage signal; Includes:

[0011] In this embodiment, after the first current signal is converted into the first modulated voltage signal, the first modulated voltage signal contains high-, medium-, and low-frequency vibration information. Therefore, the first modulated voltage signal is filtered to remove unnecessary high- and low-frequency vibration information. In addition, the first modulated voltage signal is amplified to increase the intensity of the first voltage signal. This facilitates subsequent conversion into an audio signal.

[0012] In a possible embodiment, the diaphragm device is provided with a diaphragm chip, and the step of obtaining the second voltage signal using the diaphragm device includes: using a diaphragm tip to collect strain signals formed by the displacement of the membrane; converting the distortion signal into a second voltage signal; Includes:

[0013] In this embodiment, the diaphragm device uses a diaphragm tip to sense the vibration of the membrane, then converts the displacement of the membrane into a strain signal, and forms a second voltage signal based on the strain signal.

[0014] In a possible embodiment, the step of converting the first voltage signal or the second voltage signal into an audio signal comprises: converting the first voltage signal or the second voltage signal into a digital signal format; performing algorithmic processing on the first voltage signal or the second voltage signal converted into a digital signal format to obtain an audio signal; Includes:

[0015] In this embodiment, the first voltage signal and the second voltage signal obtained by the processing unit are analog signals, respectively, and during processing of the first voltage signal or the second voltage signal into an audio signal, the analog signal needs to be first digitally converted to obtain a signal in digital format and perform algorithm processing on the signal in digital format.

[0016] In a possible embodiment, the method comprises: forming a control signal based on the first voltage signal and outputting the control signal to the transmitter, the control signal being used to adjust the wavelength of the laser light emitted toward the membrane; Further includes:

[0017] In this embodiment, when the external sound vibration changes and the laser self-mixing device collects the first voltage signal, the optimal operating point of the laser self-mixing device may change accordingly. The wavelength corresponding to the optimal operating point of the laser self-mixing device may be obtained by calculation. Therefore, the wavelength of the laser light emitted by the transmitter toward the membrane is correspondingly adjusted to ensure that the laser self-mixing device always collects the first voltage signal at the optimal operating point.

[0018] In a possible embodiment, the wavelength corresponding to the optimum operating point of the laser self-mixing device is obtained by calculation based on a phase-locked loop algorithm.

[0019] In a possible embodiment, the step of forming a control signal based on the first voltage signal and outputting the control signal to a transmitter to adjust the wavelength of the laser light emitted toward the film comprises: obtaining an optimum operating wavelength of the laser light by calculation based on the first voltage signal to form a control signal; controlling the magnitude of an operating current of the transmitter based on the control signal to control the wavelength of the laser light emitted toward the membrane; Includes:

[0020] In a possible embodiment, the step of obtaining an optimum operating wavelength of the laser light by calculation based on the first voltage signal to form the control signal comprises: converting the first voltage signal from an analog format to a digital format; obtaining an optimal operating wavelength of the laser light by calculation based on the first voltage signal in digital format to form a control signal; Includes:

[0021] In a possible embodiment, the step of controlling the magnitude of the operating current of the transmitter based on the control signal to control the wavelength of the laser light emitted toward the film comprises: converting the control signal from a digital format to an analog format; controlling the magnitude of an operating current of the transmitter based on the control signal in analog format to control the wavelength of the laser light emitted by the transmitter toward the membrane; Includes:

[0022] In this embodiment, the optimal operating point of the laser self-mixing device is calculated based on the first voltage signal in digital signal format. Therefore, the first voltage signal in analog format needs to be converted to digital before the calculation. Then, the optimal operating wavelength of the laser light of the laser self-mixing device at the optimal operating point may be obtained by calculation based on a phase-locked loop algorithm or the like. Next, the magnitude of the operating current of the transmitter is controlled to control the wavelength of the laser light, thereby adjusting the laser light emitted by the transmitter to the membrane.

[0023] In a possible embodiment, the feedback strength C of the laser self-mixing device is less than one.

[0024] In this embodiment, the feedback strength C of the laser self-mixing device is controlled to be less than 1. This can avoid phase changes and noise fluctuations in the laser light received by the receiver, thereby ensuring the quality of the laser light received by the receiver.

[0025] In a possible embodiment, the preset threshold is 0.1V.

[0026] In a possible embodiment, the preset threshold is a voltage value of the audio signal corresponding to 94 dB to 100 dB.

[0027] In the above two embodiments, the preset threshold can be set to 0.1 V or to a voltage value of the audio signal corresponding to 94 dB to 100 dB. When the first voltage signal is equal to the preset threshold, the sensitivity of the laser self-mixing device's audio sensing capability is relatively high, allowing the laser self-mixing device to accurately capture distant audio vibrations with low sound pressure. When the first voltage signal is greater than the preset threshold, the laser self-mixing device's audio sensing capability is impaired by noise. In this case, the diaphragm device can more effectively complete the audio capture.

[0028] According to a second aspect, the present application provides an electronic device, the electronic device comprising a microphone, the microphone collecting sound using the sound capturing method according to the first aspect of the present application.

[0029] It will be appreciated that since the electronic device according to the second aspect of the present application collects sound using the audio capture method according to the first aspect of the present application, the electronic device also collects audio signals in two different ways and ensures the quality of the audio signals using a pre-set threshold.

[0030] According to a third aspect, the present application provides a microphone including a substrate, a protective cover, a laser self-mixing device, a diaphragm device, and a processing unit. The protective cover and the processing unit are both fixed to the substrate, and the protective cover and the substrate form an inner cavity via a housing. The laser self-mixing device and the diaphragm device are fixed within the inner cavity and are each communicatively connected to the processing unit. The diaphragm device includes a membrane and a back cavity, which is fixed to the substrate, and the membrane is located on the opposite side of the back cavity from the substrate, and the membrane and the back cavity form a sound pickup cavity via a housing on the substrate. The laser self-mixing device includes a transmitter and a receiver, which are both housed within the sound pickup cavity and fixed to the substrate, the transmitter configured to emit laser light toward the membrane, and the receiver configured to receive the laser light reflected by the membrane. The substrate is further provided with a plurality of sound pickup holes, and the sound pickup cavity is in communication with the outside via the plurality of sound pickup holes.

[0031] In a microphone according to a second aspect of the present application, the protective cover and the substrate house the laser self-mixing device and the diaphragm device, forming an inner cavity through the housing to protect the laser self-mixing device and the diaphragm device. The diaphragm device further forms a sound-pickup cavity within the inner cavity together with the substrate through the housing using the membrane and the back cavity. The substrate further has a sound-pickup hole. External sound vibrations may enter the sound-pickup cavity through the sound-pickup hole and vibrate the membrane. The diaphragm device may identify the vibration of the membrane and form a second voltage signal. The laser self-mixing device is then housed within the sound-pickup cavity. By emitting laser light toward the membrane, the laser self-mixing device may receive both the laser light reflected by the membrane and the back cavity and form a first voltage signal through detection.

[0032] It will be understood that the laser self-mixing device and the diaphragm device are both disposed in the microphone according to the third aspect of the present application, so that the audio capture method according to the first aspect can be applied to and realized in the microphone according to the third aspect of the present application. Specifically, the microphone in the present application may use the laser self-mixing device and the diaphragm device, respectively, to obtain a first voltage signal and a second voltage signal, and convert the audio signal using a preset threshold, so that the laser self-mixing device and the diaphragm device can complement each other and collect audio signals in each relatively desirable operating scenario to ensure the sound pickup effect of the microphone in the present application.

[0033] In a possible embodiment, the film comprises a reflecting portion, the reflecting portion being located on the surface of the film facing the substrate, and the laser light emitted by the transmitter is received by the receiver after being reflected by the reflecting portion.

[0034] In this embodiment, the reflector is located on the surface of the film facing the substrate, thereby allowing the laser light emitted by the transmitter to be better reflected to ensure that the receiver effectively receives the reflected laser light.

[0035] In a possible embodiment, the reflector is located at the geometric center of the film, and the transmitter and receiver on the substrate are located within the projection area of ​​the reflector on the substrate.

[0036] In this embodiment, the geometric center of the membrane is the region of the membrane where the amplitude is the largest. The reflector, transmitter, and receiver are all positioned corresponding to the geometric center of the membrane, which can improve the self-mixing efficiency of the reflected laser light, which is helpful for extracting vibration information.

[0037] In a possible embodiment, the distance H between the reflector and the transmitter satisfies the condition 20 um≦H≦100 um.

[0038] In this embodiment, the distance between the reflector and the transmitter is limited, so that the reflection path of the laser light is controlled and the self-mixing efficiency of the laser light can be guaranteed.

[0039] In a possible embodiment, the diaphragm device comprises a diaphragm chip configured to detect vibrations of the membrane, to form a second voltage signal, and to transmit the second voltage signal to a processing unit.

[0040] In this embodiment, the diaphragm chip may convert the displacement of the membrane into a strain signal, finally form a second voltage signal, and transmit the second voltage signal to a processing unit.

[0041] In a possible embodiment, the membrane is a piezoelectric or piezoresistive diaphragm and the diaphragm chip is a piezoelectric or piezoresistive diaphragm chip.

[0042] In this embodiment, the diaphragm device may be realized by a piezoresistive diaphragm device or a piezoelectric diaphragm device, and the diaphragm chip is correspondingly a piezoresistive diaphragm chip or a piezoelectric diaphragm chip, so that reliable collection of the second voltage signal is achieved.

[0043] In a possible embodiment, the thickness D of the film satisfies the condition 0.1 um≦D≦1 um.

[0044] In this embodiment, the thickness D of the membrane is controlled, so that the membrane's ability to respond to external sounds can be guaranteed.

[0045] In a possible embodiment, the membrane is provided with a barrier layer, which is located on the side of the membrane facing the substrate, and the back cavity is fixed to the membrane via the barrier layer.

[0046] In this embodiment, the barrier layer is connected between the back cavity and the main body of the membrane, so that insulation between the back cavity and the membrane can be realized, and the diaphragm chip can reliably sense the vibration of the membrane and form a second voltage signal.

[0047] In a possible embodiment, the diaphragm chip is a piezoresistive diaphragm chip, and the piezoresistive sensing part is disposed within the diaphragm, and the piezoresistive sensing part is configured to sense vibrations of the membrane and transmit a membrane displacement signal to the piezoresistive diaphragm chip.

[0048] In a possible embodiment, the diaphragm chip is a piezoelectric diaphragm chip, the membrane body is made of a piezoelectric material, and the metal layer is disposed on the membrane body, the body is configured to sense vibrations of the diaphragm and generate electric charges, the metal layer collects the electric charges and transmits the electric charge signal to the piezoelectric diaphragm chip using a transmission part.

[0049] In the above two embodiments, the working principles of the diaphragm device are different, and correspondingly, the diaphragm chip converts all the received different signals into a second voltage signal to realize the sensing of the vibration of the membrane.

[0050] In a possible embodiment, the residual stress of the film is 50 MPa or less.

[0051] In this embodiment, the residual stress of the film is monitored, and as a result, the sensitivity of the film can be controlled.

[0052] In a possible embodiment, the membrane is made from silicon or a silicon-containing compound.

[0053] In this embodiment, the membrane is made from silicon or a silicon-containing compound, which ensures the membrane's mechanical performance and makes it easy to manufacture.

[0054] In a possible embodiment, the membrane is provided with through-hole balancing holes.

[0055] In this embodiment, the balance holes on the membrane penetrate between the sound-collecting cavity and the inner cavity, so that the air in the inner cavity can communicate with the outside through the balance holes and the sound-collecting holes in turn, thereby ensuring pressure balance between the inner cavity and the sound-collecting cavity.

[0056] According to a fourth aspect, the present application provides an electronic device, the electronic device comprising a microphone according to the third aspect, the microphone configured to collect an audio signal.

[0057] It will be appreciated that since the electronic device according to the fourth aspect of the present application comprises a microphone according to the third aspect of the present application for sound collection, the electronic device also collects audio signals in two different ways and uses a pre-set threshold to ensure the quality of the audio signals. [Brief explanation of the drawings]

[0058] [Figure 1] 1 is a schematic diagram of the internal framework of an electronic device according to the present application; [Figure 2] 1 is a schematic diagram of the structure of an electronic device according to the present application; [Figure 3] 1 is a schematic diagram of a microphone structure according to the present application; [Figure 4] 1 is a schematic exploded view of the structure of a microphone according to the present application; [Figure 5] 1 is a schematic exploded view of the structure of a diaphragm device in a microphone according to the present application; [Figure 6] 1 is a schematic cross-sectional view of the structure of an inner cavity in a microphone according to the present application; [Figure 7] 1 is a schematic plan view of the structure of a sound-collecting cavity in a microphone according to the present application. [Figure 8] 1 is a schematic cross-sectional view of a partial structure of a diaphragm device in a microphone according to the present application. [Figure 9] 2A-2C are schematic diagrams of steps in a method for making a diaphragm device in a microphone according to the present application. [Figure 10a] 1A-1C are schematic diagrams of structures for each step of a method for making a diaphragm device in a microphone according to the present application. [Figure 10b]1A-1C are schematic diagrams of structures for each step of a method for making a diaphragm device in a microphone according to the present application. [Figure 10c] 1A-1C are schematic diagrams of structures for each step of a method for making a diaphragm device in a microphone according to the present application. [Figure 10d] 1A-1C are schematic diagrams of structures for each step of a method for making a diaphragm device in a microphone according to the present application. [Figure 10e] 3A to 3C are schematic diagrams of structures for each step of a method for manufacturing a diaphragm device in a microphone according to the present application. [Figure 10f] 1A-1C are schematic diagrams of structures for each step of a method for making a diaphragm device in a microphone according to the present application. [Figure 10g] 1A-1C are schematic diagrams of structures for each step of a method for making a diaphragm device in a microphone according to the present application. [Figure 10h] 1A-1C are schematic diagrams of structures for each step of a method for making a diaphragm device in a microphone according to the present application. [Figure 11] 10 is a schematic cross-sectional view of another embodiment of a partial structure of a diaphragm device in a microphone according to the present application; [Figure 12] 1 is a flowchart of an audio capture method according to the present application. [Figure 13] FIG. 1 is a circuit diagram of signal processing in a microphone according to the present application. [Figure 14] 4 is a flowchart of another embodiment of an audio capture method according to the present application. [Figure 15] 4 is a flowchart of yet another embodiment of an audio capture method according to the present application. [Figure 16] FIG. 10 is a circuit diagram of another embodiment of signal processing in a microphone according to the present application. DETAILED DESCRIPTION OF THE INVENTION

[0059] The following describes the technical solutions in the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application. It is clear that the described embodiments are only a part, not all, of the embodiments of the present application. All other embodiments obtained by those skilled in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0060] FIG. 1 is a schematic diagram of the internal framework of an electronic device 200 according to the present application.

[0061] As shown in FIG. 1 , the electronic device 200 includes a control chip 201 and a microphone 100 provided in the present application. The microphone 100 is electrically connected to the control chip 201 and configured to sense external sound vibrations, form an audio signal, and transmit the audio signal to the control chip 201. After receiving the audio signal sensed by the microphone 100, the control chip 201 may transmit the audio signal to the outside to realize the remote call function of the electronic device 200. It should be understood that the audio signal in this specification may also be understood as an audio code, and that the audio code may be transmitted to the outside in the form of a communication signal. The electronic device 200 according to the present application may be a terminal product such as a mobile phone, a tablet, a notebook computer, a desktop computer, or a television. In some other embodiments, after receiving the audio signal sensed by the microphone 100, the control chip 201 may further analyze information such as instructions contained in the audio signal (code) to respond to a user's voice control operation. Alternatively, the electronic device 200 according to the present application may be the aforementioned terminal product, smart home appliance, etc.

[0062] As shown in FIG. 1 , the electronic device 200 may further include an audio decoding unit 202, an audio amplifier unit 203, and a speaker 204. The control chip 201 is located at the back end of the microphone 100 and is further electrically connected to the audio decoding unit 202, the audio amplifier unit 203, and the speaker 204, in sequence. After receiving external audio vibrations sensed by the microphone 100, the control chip 201 may send an audio signal to the speaker 204. The audio signal is sequentially decoded and amplified, and then played back through the speaker 204. In this way, the electronic device 200 can realize the function of voice interaction with a user through voice capture by the microphone 100. FIG. 2 is a schematic diagram of the structure of the electronic device 200 according to the present application.

[0063] As shown in FIG. 2 , eight microphones 100 are disposed on the electronic device 200. The microphones 100 are distributed in different directions on the outer edge of the electronic device 200 and configured to capture audio vibrations from different orientations of the electronic device 200. Each microphone 100 is electrically connected to the control chip 201 and configured to transmit an audio signal. In some embodiments, the eight microphones 100 may be further numbered one by one. To realize an orientation identification function, the control chip 201 may determine the position of the microphone 100 in the electronic device 200 that is currently sensing the audio signal, i.e., the orientation of the sound source relative to the electronic device 200 that is currently emitting the audio vibration, based on the audio signals received from the microphones 100 with different numbers.

[0064] In the subsequent audio signal processing process, the electronic device 200 may selectively receive audio signals captured by the microphones 100 within the determined direction of the sound source relative to the electronic device 200 to achieve directional audio signal collection. In addition, when multiple microphones 100 respectively collect audio signals and transmit the audio signals to the control chip 201, the control chip 201 may further integrate the multiple audio signals into one signal, and then transmit the signal to the outside or perform operations such as voice interaction or command recognition, to improve the accuracy of audio vibration capture by the electronic device 200. In some other embodiments, the distribution and number of microphones 100 in the electronic device 200 may be alternatively specified as needed based on actual usage scenarios. This is not particularly limited in the present application.

[0065] FIG. 3 is a schematic diagram of the structure of a microphone 100 according to the present application.

[0066] The microphone 100 provided in the present application includes a substrate 10 and a protective cover 20. The protective cover 20 includes a protective plate 21 and a protective wall 22. The protective wall 22 is disposed around the edge of the protective plate 21, and the protective wall 22 is further fixed to the substrate 10, so that the entire protective cover 20 is fixed to the substrate 10. The protective cover 20 and the substrate 10 form an inner cavity 23 (see FIG. 6 ) through the housing.

[0067] FIG. 4 is a schematic exploded view of the structure of microphone 100.

[0068] The microphone 100 further includes a diaphragm device 30. The diaphragm device 30 is housed in an inner cavity 23 formed by the protective cover 20 and the substrate 10 through the housing, and the diaphragm device 30 is fixed to the substrate 10. As shown in FIG. 4 , the microphone 100 further includes a processing unit 40, which may be an application specific integrated circuit (ASIC). The processing unit 40 is also fixed to the substrate 10 and housed in the inner cavity 23. The processing unit 40 is fixed to the substrate 10, and the processing unit 40 is further electrically connected to the diaphragm device 30. In some other embodiments, the processing unit 40 may alternatively be located outside the protective cover 20. In other words, the processing unit 40 may be located outside the inner cavity 23. In this case, the processing unit is still fixed to the substrate 10 and is electrically connected to the diaphragm device 30.

[0069] FIG. 5 is a schematic exploded view of the structure of the diaphragm device 30. As shown in FIG.

[0070] The diaphragm device 30 may be a micro-electrical mechanical system (MEMS) and includes a membrane 31 and a back cavity 32. The membrane 31 is in the form of a thin film and may be made of silicon or a silicon-containing compound, or in some embodiments, a piezoelectric material. The back cavity 32 is in the form of a hollow ring and is provided with a through-hole 321. As shown in FIG. 5 , the back cavity 32 is circular, and the through-hole 321 is correspondingly specified to be circular, resulting in the back cavity 32 having a hollow circular ring shape. In some other embodiments, the back cavity 32 may alternatively be rectangular, elliptical, or the like, and the through-hole 321 is correspondingly specified to have a shape that matches the shape of the back cavity 32, resulting in the back cavity 32 having a rectangular ring or elliptical ring shape.

[0071] The membrane 31 is fixed to the back cavity 32 side and shields the through-hole 321. The opposite side of the back cavity 32 from the membrane 31 is fixed to the substrate 10, so that the diaphragm device 30 and the substrate 10 form a sound pickup cavity 33 (see the cross-sectional view of the structure of the inner cavity 23 of the microphone 100 shown in FIG. 6) via the housing. It will be understood that the sound pickup cavity 33 is housed within the inner cavity 23. At least one sound pickup hole 11 is provided in the area of ​​the substrate 10 corresponding to the sound pickup cavity 33. Specifically, as shown in FIG. 7, the protruding portion of the through-hole 321 of the back cavity 32 on the substrate 10 forms a housing area 322, and all of the multiple sound pickup holes 11 are located within the housing area 322. At least one sound pickup hole 11 penetrates the substrate 10, so that the sound pickup cavity 33 is connected to the outside. External sound vibrations may enter the sound pickup cavity 33 through each sound pickup hole 11 and vibrate the membrane 31. The diaphragm device 30 may convert the displacement strain of the membrane 31 into an electrical signal, collect and capture the external sound vibrations, form an audio signal, and transmit the audio signal to the processing unit 40.

[0072] The shape, size, and number of the sound pickup holes 11 of the microphone 100 according to the present application are not particularly limited. As shown in FIG. 7 , there may be four sound pickup holes 11. In other embodiments, the number of sound pickup holes 11 may alternatively be another number. In addition, the shape and size of the sound pickup holes 11 may be specified as needed. If the sound pickup holes 11 can communicate with the sound pickup cavity 33 and the external space, external sound vibrations can enter the sound pickup cavity 33 through the sound pickup holes 11.

[0073] FIG. 8 shows an embodiment of the interior of the diaphragm device 30. In this embodiment, the membrane 31 is realized by a piezoresistive diaphragm. Specifically, the membrane 31 includes a body 311, a reflecting portion 312, a barrier layer 313, a piezoresistive sensing portion 314, a transmitting portion 315, and a protective layer 316. The body 311 is made of silicon or a silicon-containing compound. The body 311 is in the form of a thin film and has a first surface 311a and a second surface 311b facing opposite to each other. The first surface 311a is the outer surface of the body 311 facing the substrate 10. The second surface 311b is the outer surface of the body 311 opposite to the substrate 10. The direction from the first surface 311a to the second surface 311b is the thickness direction of the body 311. The direction parallel to the first surface 311a and the second surface 311b is the surface direction of the main body 311.

[0074] The barrier layer 313 is connected between the main body 311 and the back cavity 32. That is, the barrier layer 313 is located on the first surface 311a. The barrier layer 313 is configured to fix the membrane 31 to the back cavity 32 and completely insulate the membrane 31 from the back cavity 32. The reflective portion 312 is also located on the first surface. As shown in FIG. 8, the reflective portion 312 is further disposed at the geometric center of the main body 311. The reflective portion 312 faces the inside of the sound-collecting cavity 33. The protective layer 316 is located on the second surface 311b side, and the protective layer 316 faces the outside of the sound-collecting cavity 33. The protective layer 316 is configured to protect other components of the main body 311 and the membrane 31.

[0075] The piezoresistive sensing portion 314 and the transmitting portion 315 are located between the reflecting portion 312 and the protective layer 316 in the thickness direction of the main body 311. The piezoresistive sensing portion 314 is further distributed in the surface direction of the main body 311. The piezoresistive sensing portion 314 is configured to sense vibration displacement caused by the main body 311. After external sound vibration is transmitted to the sound pickup cavity 33 through the sound pickup hole 11, the main body 311 is excited by the external sound vibration, causing vibration displacement. The piezoresistive sensing portion 314 generates a strain signal in response to the vibration displacement of the main body 311 and transmits the strain signal in the opposite direction via the transmitting portion 315 connected to the piezoresistive sensing portion 314. Furthermore, the membrane 31 is provided with a piezoresistive diaphragm chip 341 corresponding to the piezoresistive sensing portion 314. The piezoresistive diaphragm chip 341 may be disposed on the diaphragm device 30 or may be integrated into the processing portion 40. The piezoresistive diaphragm chip 341 is electrically connected to the piezoresistive sensing part 314 and is configured to convert the strain signal sensed by the piezoresistive sensing part 314 into a voltage signal (specifically, a second voltage signal V2) and transmit the voltage signal to the processing part 40.

[0076] It will be appreciated that when the piezoresistive diaphragm chip 341 is disposed on the diaphragm device 30, specifically on the second surface 311b of the membrane 31, the piezoresistive diaphragm chip 341 may be directly electrically connected to the piezoresistive sensing part 314 via the transmission part 315 to collect strain signals. When the piezoresistive diaphragm chip 341 is incorporated into the processing part 40, the piezoresistive diaphragm chip 341 needs to be connected to the piezoresistive sensing part 314 by joining the transmission part 315 and the transmission line 319. The above two methods of disposing the piezoresistive diaphragm chip 341 both establish a connection between the piezoresistive diaphragm chip 341 and the piezoresistive sensing part 314, allowing the piezoresistive diaphragm chip 341 to collect strain signals.

[0077] The total thickness of the membrane 31 in this embodiment may be in the range of 0.1 um to 1 um, for example, 0.9 um, so as to ensure the ability of the membrane 31 to respond to the sound pressure of external sound vibrations and the displacement sensitivity of the membrane 31. The area of ​​the membrane 31 may be, for example, 0.3 mm 2to 4mm 2 For example, 1 mm 2 In this case, a shorter side length of the film 31 indicates a wider high frequency range covered by the film 31, and a longer side length indicates a relatively higher sensitivity of the film 31. This may be specifically adjusted based on the actual application scenario. The residual stress of the film 31 does not exceed 50 MPa, so the sensitivity of the film 31 is guaranteed.

[0078] The shape of the reflective portion 312 may be circular, and the radius of the reflective portion 312 may be in the range of 10 μm to 1000 μm, e.g., 60 μm, resulting in a relatively large reflective area. The thickness of the reflective portion 312 may be in the range of 10 nm to 200 nm, resulting in a guaranteed light reflection ability. Furthermore, the distance between the geometric center of the reflective portion 312 and the geometric center of the main body 311 must be controlled to within 10 μm.

[0079] The thickness of the piezoresistive sensitive portion 314 may be in the range of 100 nm to 500 nm, for example 180 nm, to reach a preset resistance value, so that a strain signal is collected.

[0080] The thickness of the protective layer 316 is in the range of 50 nm to 1000 nm, for example, 200 nm, to ensure the protective effect.

[0081] In one embodiment, the membrane 31 is further provided with a balancing hole 317. The balancing hole 317 penetrates the membrane 31 in the thickness direction of the membrane 31 and communicates with the sound-pickup cavity 33 and the inner cavity 23. After external sound vibrations enter the sound-pickup cavity 33 through the sound-pickup hole 11, the air pressure in the sound-pickup cavity 33 may change. As a result, the membrane 31 creates a pressure difference between the sound-pickup cavity 33 and the inner cavity 23, which may hinder the vibration of the membrane 31. The balancing hole 317 is provided to balance the pressure in the sound-pickup cavity 33 and the inner cavity 23 to ensure the vibration effect of the membrane 31. The diameter of the balancing hole 317 may be in the range of 0.5 μm to 5 μm, for example, 1.5 μm.

[0082] In an embodiment in which the piezoresistive diaphragm chip 341 is disposed on the membrane 31, the structure of the piezoresistive diaphragm chip 341 needs to be further restricted to prevent the piezoresistive diaphragm chip 341 from affecting the vibration effect of the membrane 31. In one embodiment, the shape of the piezoresistive diaphragm chip 341 is rectangular, and the combination of the side lengths of the piezoresistive diaphragm chip 341 may be in the range of 0.5 mm x 0.5 mm to 5 mm x 5 mm, for example, 1.4 mm x 1.4 mm. The thickness of the piezoresistive diaphragm chip 341 may be in the range of 150 μm to 500 μm, for example, 220 μm.

[0083] 9 and 10a to 10h show steps of a method for making the diaphragm device 30 according to the present application. The diaphragm device 30 according to the present application may be expanded and obtained through the following steps:

[0084] S101: Prepare a silicon substrate, and form two thermal oxide layers 313a and 313b on the silicon substrate by a thermal oxidation process (see FIG. 10a).

[0085] One thermal oxide layer 313a is located on the outer surface of one side of the silicon substrate, and the other thermal oxide layer 313b is located inside the silicon substrate and is spaced apart from the thermal oxide layer 313a on the outer surface.

[0086] S102: Fabricate the piezoresistive sensing portion 314 in the silicon substrate by a light boron doping process (see FIG. 10b).

[0087] The piezoresistive sensing portion 314 is located between the two thermal oxide layers 313 a and 313 b and is patterned in synchronization with the process of fabricating the piezoresistive sensing portion 314 .

[0088] S103: Fabricate a portion of the transmitting portion 315a in the silicon substrate by a heavy boron doping process (see FIG. 10c).

[0089] The depth of a portion of the transmitting portion 315a in the silicon substrate is equal to the depth of the piezoresistive sensing portion 314 in the silicon substrate, so that a portion of the transmitting portion 315a communicates with each of the patterned piezoresistive sensing portions 314.

[0090] S104: Etch the thermal oxide layer 313a located on the outer surface of the silicon substrate to expose the structure of the transmission part 315a fabricated in step S103 (see FIG. 10d).

[0091] The thermal oxide layer 313a is etched to form a protective layer 316 of the membrane 31, the protective layer 316 having vias 315b formed therein by etching.

[0092] S105: Fill the via 315b and the outer surface of the protective layer 316 with metal by a deposition process to form another part of the transmitting portion 315c (see FIG. 10e).

[0093] The metal on protective layer 316 forms a conductive structure layer outside protective layer 316. The metal filled in via 315b is connected to a part of transmission section 315a fabricated in step S103, and as a result, a part of transmission section 315c fabricated in step S105 and another part of transmission section 315a fabricated in step S103 form transmission section 315. This allows the strain signal in piezoresistive sensing section 314 to be guided outside protective layer 316. Thereafter, transmission section 315 may be directly connected to piezoresistive diaphragm chip 341 or may be connected to diaphragm chip 341 via transmission path 319.

[0094] In some embodiments, the creation of balance holes 317 may also be completed at this step.

[0095] S106: Etch the outer surface of the other side of the silicon substrate by a deep reactive ion etching process to remove material of the silicon substrate until the other thermal oxide layer 313b is exposed (see FIG. 10f).

[0096] The etching of this portion of the silicon substrate is a center etch, and the surrounding material of the silicon substrate is retained to form the back cavity 32 of the diaphragm device 30. The material of the silicon substrate between the other thermal oxide layer 313b and the protective layer 316 forms the main body 311 of the membrane 31.

[0097] S107: A rinse process is performed to remove the part of the thermal oxide layer 313b exposed in step S106 (see FIG. 10g).

[0098] The thermal oxide layer 313b remaining after the rinsing process forms the barrier layer 313 of the film 31, and the barrier layer 313 is connected between the body 311 and the back cavity 32. In addition, after partially removing the thermal oxide layer 313b, the first surface 311a of the body 311 is also exposed. The rinsing process may be performed by using a hydrofluoric acid (HF) reagent.

[0099] S108: The reflector 312 is fabricated on the first surface 311a by a deposition process (see FIG. 10h).

[0100] The reflector 312 may be made from aluminum or an aluminum alloy.

[0101] In this way, the diaphragm device 30 provided in this embodiment of the present application can be fabricated, and the position of each component and each layer structure and the realization of the function of each component and each layer structure are guaranteed.

[0102] FIG. 11 shows another embodiment of the structure of the diaphragm device 30. In the embodiment of FIG. 11, the membrane 31 is realized by a piezoelectric membrane. Specifically, the membrane 31 also includes a main body 311, a reflective portion 312, a barrier layer 313, a transmitting portion 315, and a protective layer 316. The main body 311 is made of a piezoelectric material. The entire main body 311 is also in the form of a thin film, and has a first surface 311a and a second surface 311b facing opposite to each other. The first surface 311a is the outer surface of the main body 311 facing the substrate 10. The second surface 311b is the outer surface of the main body 311 opposite to the substrate 10. The barrier layer 313 is connected between the main body 311 and the back cavity 32. The reflective portion 312 is also located on the first surface 311a. The protective layer 316 is located on the second surface 311 b side and is configured to protect the main body 311 and other constituent structures of the membrane 31 .

[0103] In this embodiment, the metal layer 318 and the transmitting portion 315 are disposed in the thickness direction of the main body 311 and are located between the first surface 311a and the second surface 311b of the main body 311. One or more metal layers 318 may be present. FIG. 11 shows two metal layers 318. The transmitting portions 315 are electrically connected to the metal layers 318, respectively, and the transmitting portions 315 extend partially from the second surface 311b. In this embodiment, the protective layer 316 is further located on one side of the transmitting portion 315, opposite the reflective portion 312, and is configured to cover and protect the transmitting portion 315 extending from the second surface 311b.

[0104] After the external sound vibration is transmitted to the sound-receiving cavity 33 through the sound-receiving hole 11, the body 311 is excited by the external sound vibration, resulting in vibration displacement. The body 311, made of a piezoelectric material, may generate electric charges. A metal layer 318 disposed within the body 311 collects the electric charges, generates a charge signal, and transmits the charge signal in the opposite direction via a transmission unit 315 connected to the metal layer 318. Furthermore, the membrane 31 is correspondingly provided with a piezoelectric diaphragm chip 342. The piezoelectric diaphragm chip 342 may be disposed on the diaphragm device 30 or may be integrated into the processing unit 40. The piezoelectric diaphragm chip 342 is electrically connected to the transmission unit 315 and configured to convert the charge signal collected by the metal layer 318 into a second voltage signal V2 and transmit the second voltage signal V2 to the processing unit 40.

[0105] 11 , the dimensions of the internal body 311, the reflecting portion 312, the protective layer 316, the piezoelectric diaphragm chip 342, etc. of the diaphragm device 30 realized by the piezoelectric diaphragm shown in FIG. 11 , the embodiment of the balancing hole 317, etc. may all be specified with reference to the above-mentioned piezoresistive diaphragm device 30 in order to improve the sensitivity of the diaphragm device 30. Therefore, the embodiment in which the diaphragm device 30 according to the present application is realized by a piezoresistive film or a piezoelectric film can also realize reliable capture of external sound vibrations.

[0106] See Figures 5, 6, and 7. The microphone 100 according to the present application further includes a laser self-mixing device 60. The laser self-mixing device 60 is housed in the sound-collecting cavity 33 and includes a transmitter 61 and a receiver 62. Both the transmitter 61 and the receiver 62 are fixed to the substrate 10. The transmitter 61 may be a vertical cavity surface-emitting laser (VCSEL) and is configured to emit laser light toward the reflector 312. The receiver 62 is configured to receive the laser light reflected by the reflector 312. The laser light emitted by the transmitter 61 and the laser light reflected by the reflector 312 may both be diffracted within the sound-collecting cavity 33. The diffracted laser light further hits the first surface 311a of the film 31 and the inner wall of the back cavity 32, and after being reflected, a portion of the laser light is received by the receiver 62. Furthermore, the vibration of the membrane 31 also causes a portion of the laser light to be reflected by the inner wall of the back cavity 32. When external sound vibrations vibrate the membrane 31, the aforementioned laser light reflected by the reflecting portion 312 may carry vibration information of the membrane 31. The laser light may be mixed with the laser light reflected by the inner wall of the back cavity 32 to form a self-mixing effect in the sound-collecting cavity 33. The intensity and frequency of the self-mixing laser light beam may be changed, and the changed intensity and changed frequency also carry vibration information of the membrane 31. After receiving the laser signal obtained by mixing, the receiver 62 may compare the laser light emitted by the transmitter 61 with the laser light obtained by mixing, extract a current signal (specifically, a first current signal A1), convert the current signal into a voltage signal (specifically, a first voltage signal V1), and transmit the voltage signal to the processing unit 40.

[0107] As shown in FIGS. 6 and 7 , the transmitter 61 and the receiver 62 are further arranged one on top of the other, with the transmitter 61 fixed to the substrate 10 and the receiver 62 located on the opposite side of the transmitter 61 from the substrate 10. Furthermore, the film 31 is arranged parallel to the substrate 10, and the first surface 311a of the film 31 is perpendicular to both the transmitter 61 and the receiver 62. Therefore, the reflecting portion 312 is also arranged perpendicular to the transmitter 61 and the receiver 62. In addition, the transmitter 61 and the receiver 62 on the substrate 10 are located within the projection range of the reflecting portion 312 on the substrate 10. In this case, the transmitter 61 emits laser light toward the film 31 in a direction perpendicular to the substrate 10, and the laser light is vertically reflected by the reflecting portion 312 and then received by the receiver 62. As a result, the flight distance of the laser light within the sound pickup cavity 33 can be shortened.

[0108] In the microphone 100 according to the present application, the sound-collecting cavity 33 may be defined as the front cavity of the microphone 100, and the distance between the membrane 31 and the substrate 10 is defined as the height of the front cavity. The space of the inner cavity 23 excluding the space of the sound-collecting cavity 33 is defined as the rear cavity of the microphone 100. The height of the membrane 31 relative to the inner surface of the protective plate 21 is defined as the height of the rear cavity. In one embodiment, the distance H between the reflector 312 and the transmitter 61 is limited to satisfy the condition 20 μm≦H≦100 μm. This restriction controls the distance between the transmitter 61 and the membrane 31. In addition, since the distance between the transmitter 61 and the membrane 31 is limited, the flight distance of the laser light within the sound-collecting cavity 33 is controlled, which results in a reduced signal-to-noise ratio (SNR) of the laser signal obtained by the receiver 62.

[0109] Since the transmitter 61 is fixed to the substrate 10, the distance between the transmitter 61 and the reflector 312 is controlled, and the distance between the substrate 10 and the membrane 31 is also controlled. That is, the height of the front cavity of the microphone 100 is controlled by the aforementioned constraint. Assuming that the space and height of the inner cavity 23 are fixed, controlling the height of the front cavity of the microphone 100 means increasing the height of the rear cavity of the microphone 100. Increasing the height of the rear cavity also helps to increase the signal-to-noise ratio of the diaphragm device 30. Furthermore, in the aforementioned embodiments of the membrane 31, the body 311 has a simple single-layer or two-layer structure, but the microphone 100 can reach a relatively good operating state. Compared to the prior art membranes with multi-layer structures, the membrane 31 in the present application is thinner, and the resulting space of the rear cavity is correspondingly larger. This helps to improve the signal-to-noise ratio of the diaphragm device 30.

[0110] Therefore, in addition to capturing external audio vibrations using the diaphragm device 30, the microphone 100 according to the present application may also capture external audio vibrations using the laser self-mixing device 60. To ensure that the microphone 100 can achieve a better audio capture effect, the two audio vibration capture methods may complement each other, or a method such as a fusion algorithm may be used. In addition, because the microphone 100 according to the present application has a better audio capture effect, the audio capture capability of the electronic device 200 using the microphone 100 is also improved.

[0111] 12 shows a method for capturing audio according to the present application. The method includes the following steps:

[0112] S100: The laser self-mixing device 60 is used to obtain a first voltage signal V1, and the diaphragm device 30 is used to obtain a second voltage signal V2 at the same time.

[0113] S200: If the first voltage signal V1 is less than or equal to a preset threshold V0, convert the first voltage signal V1 into an audio signal; or if the first voltage signal V1 is greater than the preset threshold V0, convert the second voltage signal V2 into an audio signal.

[0114] It should be understood that the sound capturing method according to the present application is based on the aforementioned microphone 100, which includes both the laser self-mixing device 60 and the diaphragm device 30. Specifically, in step S100, when external sound vibration occurs, sound waves are transmitted to the sound pickup cavity 33 through the sound pickup hole 11, causing the membrane 31 to vibrate. In this case, the diaphragm device 30 may sense the vibration of the membrane 31, sense the displacement of the membrane 31 in a piezoelectric or piezo-resistive manner, form a second voltage signal V2, and transmit the second voltage signal V2 to the processing unit 40. At the same time, the laser self-mixing device 60 monitors the vibration of the membrane 31, forms a first voltage signal V1, and transmits the first voltage signal V1 to the processing unit 40. In this case, the two voltage signals acquired by the processing unit 40 are formed based on the same external sound vibration. Specifically, the audio vibrations captured by the laser self-mixing device 60 and the audio vibrations captured by the diaphragm device 30 are audio vibrations in the same environment, and the first voltage signal V1 and the second voltage signal V2 are both used to represent the audio vibrations in the same environment.

[0115] The processing unit 40 separately acquires the first voltage signal V1 and the second voltage signal V2, and then determines the magnitude of the first voltage signal V1 based on a preset threshold V0. Specifically, the processing unit 40 may compare the first voltage signal V1 with the preset threshold V0 and process the first voltage signal V1 or the second voltage signal V2 based on the comparison result. Specifically, if the first voltage signal V1 is equal to or less than the preset threshold V0, the processing unit 40 selects to process the first voltage signal V1 and converts the first voltage signal V1 into an audio signal that is output in the reverse direction. Alternatively, if the first voltage signal V1 is greater than the preset threshold V0, the processing unit 40 selects to process the second voltage signal V2 and converts the second voltage signal V2 into an audio signal that is output in the reverse direction.

[0116] Because the laser self-mixing device 60 and the diaphragm device 30 use different sound capture principles, the two devices have different advantages when it comes to sound capture. The laser self-mixing device 60 is more sensitive and can be configured to collect sound vibration signals with relatively low sound vibration energy and relatively low sound pressure. However, in scenarios with relatively high sound vibration energy and high sound pressure, the laser self-mixing device 60's noise increases, the signal-to-noise ratio decreases, and the acoustic overload point (AOP) of the laser self-mixing device 60 is relatively low. As a result, the overall sound recognition ability is impaired. In contrast, the diaphragm device 30 has better recognition ability in scenarios with relatively high sound pressure, can control the signal-to-noise ratio of the signal, and has a higher AOP.

[0117] The energy of external sound vibrations may be identified based on the magnitude of the sound pressure. In the microphone 100 of the present application, the identification and differentiation may be performed based on the magnitude of the collected first voltage signal V1 or the magnitude of the collected second voltage signal V2. In the sound capture method of the present application, a preset threshold V0 may be set to control the microphone 100 to capture sound vibrations in relatively low sound pressure scenarios using the laser self-mixing device 60, thereby improving the sensitivity of the microphone 100 and extending the operating range of the microphone 100. In relatively high sound pressure scenarios, the microphone 100 of the present application captures sound vibrations using the diaphragm device 30 to ensure the signal-to-noise ratio of the signal and improve the acoustic overload point of the microphone 100.

[0118] Furthermore, because the first voltage signal V1 and the second voltage signal V2 are both used to represent the same environmental sound vibrations, the first voltage signal V1 and the second voltage signal V2 may be considered to be synchronized in time. When the processing unit 40 switches from processing the first voltage signal V1 to processing the second voltage signal V2, or from processing the second voltage signal V2 to processing the first voltage signal V1, signal desynchronization or frame loss will not occur due to the time-synchronization characteristics of the two signals. This ensures that the microphone 100 can continuously capture the external sound vibrations and convert the external sound vibrations to obtain a continuous audio signal.

[0119] Additionally, due to different structures of the membrane 31 and back cavity 32 in the diaphragm device 30 and different selections of the transmitter 61 and receiver 62 in the laser self-mixing device 60, the preset threshold V0 in the audio capture method of the present application is not specified to be a unique value. In some embodiments, the preset threshold V0 may be set to 0.1 V. Specifically, if the magnitude of the first voltage signal V1 collected by the laser self-mixing device 60 is equal to or less than 0.1 V, the processing unit 40 processes the first voltage signal V1 into an audio signal; or, if the magnitude of the first voltage signal V1 is greater than 0.1 V, the processing unit 40 processes the second voltage signal V2 into an audio signal. However, in some other embodiments, the preset threshold may alternatively be defined as a voltage value formed when the laser self-mixing device 60 collects an audio signal corresponding to 94 dB to 100 dB. This may also ensure that the laser self-mixing device 60 and the diaphragm device 30 capture audio vibrations in their respective more desirable operating (i.e., sound pressure) scenarios.

[0120] It should be understood that in the above-described embodiment, the preset threshold V0 may be a specific value or a range of values. There is some overlap between the desired operating scenarios of the diaphragm device 30 and the laser self-mixing device 60. In other words, when there is an overlap (i.e., a range of sound pressure), the diaphragm device 30 and the laser self-mixing device 60 can both achieve a relatively good sound vibration capturing effect.

[0121] In some embodiments, after the preset threshold V0 is set to a value range, a specific setting may be further made to the signal switching method of the processing unit 40. For example, when the processing unit 40 converts the first voltage signal V1 into an audio signal, the processing unit 40 may be controlled to continuously convert the first voltage signal V1 into an audio signal as long as the first voltage signal V1 does not exceed the upper limit of the preset threshold V0. This ensures the continuity of the audio signal. Alternatively, when the processing unit 40 converts the second voltage signal V2 into an audio signal, the processing unit 40 may be controlled to continuously convert the second voltage signal V2 into an audio signal as long as the first voltage signal V1 is equal to or greater than the lower limit of the preset threshold V0. This also ensures the continuity of the audio signal. In addition, the method of this embodiment also avoids signal synchronization loss or frame loss that may occur due to the processing unit 40 frequently switching the signal processing line of the processing unit 40.

[0122] In one embodiment, step S100 "obtain a first voltage signal V1 using the laser self-mixing device 60" may include the following substeps.

[0123] S110: The transmitter 61 is controlled to emit laser light toward the film 31.

[0124] S120: Receive the laser light reflected by the film 31 using the receiver 62 to form a first current signal A1.

[0125] S130: The first current signal A1 is modulated into a first voltage signal V1.

[0126] As described above, after the receiver 62 of the laser self-mixing device 60 receives the reflected laser light, the signal generated by sensing is a current signal (i.e., the first current signal A1). However, the preset threshold V0 in the method according to the present application is a voltage signal. Therefore, the first current signal A1 needs to be first modulated and converted into a first voltage signal V1, and then the processing unit 40 can compare the first voltage signal V1 with the preset threshold V0 for determination. In some embodiments, the laser signal received by the receiver 62 may be a laser light beam formed by self-mixing in the sound-collecting cavity 33.

[0127] Furthermore, in one embodiment, the step S130 "Modulate the first current signal A1 into the first voltage signal V1" further includes the following substeps.

[0128] S131: Convert the first current signal A1 into a first modulated voltage signal VT1 using a transimpedance amplifier.

[0129] S132: Amplify the first modulated voltage signal VT1 using an operational amplifier.

[0130] S133: Filter the amplified first modulated voltage signal VT1 to form a first voltage signal V1.

[0131] For details, please refer to FIG. 13. FIG. 13 is a circuit diagram of the signal processing in the microphone 100 according to the present application. In this embodiment, the laser self-mixing device 60 further includes a transimpedance amplifier 63, and an operational amplifier 64, a low-pass filter 65, and a high-pass filter 66 are further disposed in the laser self-mixing device 60. The transimpedance amplifier 63 is electrically connected to the receiver 62 and configured to convert the first current signal A1 into a first modulation voltage signal VT1. The operational amplifier 64 is electrically connected to the transimpedance amplifier 63 and configured to amplify the first modulation voltage signal VT1 to increase the strength of the first modulation voltage signal VT1, so that the amplified first modulation voltage signal VT1 can meet the data processing requirements of the processing unit 40. A low-pass filter 65 and a high-pass filter 66 are connected in series to the operational amplifier 64 and are configured to perform low-pass filtering and high-pass filtering, respectively, on the amplified first modulated voltage signal VT1 to form a first voltage signal V1.

[0132] Because the range of audio frequencies that the human ear can receive is limited, after conversion to an audio signal, part of the vibration information carried in the first modulated voltage signal VT1 exceeds the range of audio frequencies that the human ear can receive. Therefore, after filtering is performed on the amplified first modulated voltage signal VT1, part of the vibration information that exceeds the range of audio frequencies that the human ear can receive can be removed. The first voltage signal V1 formed after filtering is performed on the amplified first modulated voltage signal VT1 retains only vibration information within the range of audio frequencies that the human ear can receive. This reduces the load on the processing unit 40.

[0133] In the case of the diaphragm device 30, in one embodiment, step S100 "obtain a second voltage signal V2 using the diaphragm device 30" may include the following substeps.

[0134] S140: The diaphragm tip is used to collect the strain signal formed by the displacement of the membrane 31.

[0135] S150: Convert the distortion signal into a second voltage signal V2.

[0136] Based on the above description of the solution for the diaphragm device 30, the diaphragm device 30 of the present application needs to use a diaphragm chip to sense the vibration of the membrane 31, convert the displacement of the membrane 31 into a strain signal, and generate a second voltage signal V2 based on the strain signal. The diaphragm chip may be a piezoresistive diaphragm chip 341 or a piezoelectric diaphragm chip 342. When the diaphragm chip is a piezoelectric diaphragm chip 342, the strain signal of the piezoelectric diaphragm chip 342 is specifically a charge signal, i.e., a collected charge, generated by the deformation of the body 311 made of a piezoelectric material when it vibrates. In this case, the charge signal is converted into the second voltage signal V2.

[0137] It should be noted that the operation process of the laser self-mixing device 60 to form the first voltage signal V1 in substeps S110 to S130 and the operation process of the diaphragm device 30 to form the second voltage signal V2 in substeps S140 and S150 are operations completed by two different processing circuits that operate separately and synchronously. The sequence of sequence numbers above does not represent a specific sequence of the operation process of the microphone 100, and the two operation processes are actually in a parallel relationship. For details, please refer to FIG. 14. FIG. 14 is another schematic flowchart of the audio capture method according to the present application.

[0138] In one embodiment, based on the examples of Figures 13 and 14, in the present application, step S200 of "converting the first voltage signal V1 or the second voltage signal V2 into an audio signal" may further include the following substeps:

[0139] S210: Convert the first voltage signal V1 or the second voltage signal V2 into a digital signal format.

[0140] S220: Perform algorithm processing on the first voltage signal V1 or the second voltage signal V2 converted into a digital signal format to obtain an audio signal.

[0141] Specifically, in this embodiment, the processing unit 40 includes a conversion module 41 and a processing module 42. The first voltage signal V1 input from the laser self-mixing device 60 is in an analog signal format, and the second voltage signal V2 input from the diaphragm device 30 is also in an analog signal format. When the processing module 42 processes the first voltage signal V1 or the second voltage signal V2, the conversion module 41 must first perform digital conversion on the first voltage signal V1 and the second voltage signal V2. After the first voltage signal V1 and the second voltage signal V2 are converted from analog signals to digital signals, the conversion module 41 transmits the first voltage signal V1 and the second voltage signal V2 in the digital signal format to the processing module 42, and the processing module 42 processes the first voltage signal V1 and the second voltage signal V2 in the digital signal format into audio signals.

[0142] Please refer to Fig. 15, which is a flowchart of yet another embodiment of the audio capturing method according to the present application. Please also refer to Fig. 16, which is a circuit diagram corresponding to the flowchart. After step S100 "obtain a first voltage signal V1 using the laser self-mixing device 60", the method may further include:

[0143] S300: A control signal is formed based on the first voltage signal V1, and is output to the transmitter 61 to adjust the wavelength of the laser light emitted toward the film 31.

[0144] Specifically, as the external audio vibration changes and the laser self-mixing device 60 collects the first voltage signal V1, the optimal operating point (or the optimal operating intensity and frequency of the laser light) of the laser self-mixing device 60 may change accordingly. Based on the different magnitudes of the first voltage signal V1, the processing unit 40 may obtain the current optimal operating point of the laser self-mixing device 60 through calculations based on a phase-locked loop algorithm or the like. In this case, the processing unit 40 may synchronously analyze the wavelength of the laser light emitted by the laser self-mixing device 60 when the laser self-mixing device 60 operates at the optimal operating point. The processing unit 40 controls the operating current of the transmitter 61, thereby controlling the wavelength of the laser light emitted by the laser self-mixing device 60. This ensures that the laser self-mixing device 60 always collects the first voltage signal V1 at the optimal operating point.

[0145] In one embodiment, step S300 "adjusting the wavelength of the laser light emitted by the transmitter 61 toward the membrane 31 based on the first voltage signal V1 and a phase-locked loop algorithm" may further include the following substeps:

[0146] S310: Obtain the optimum operating wavelength of the laser light by calculation based on the first voltage signal V1 to form a control signal.

[0147] S320: In order to control the wavelength of the laser light emitted toward the film 31, the magnitude of the operating current of the transmitter 61 is controlled based on the control signal.

[0148] Specifically, step S310 may further include the following substeps.

[0149] S311: Convert the first voltage signal V1 from analog format to digital format.

[0150] S312: Obtain the optimum operating wavelength of the laser light by calculation based on the first voltage signal V1 in digital format to form a control signal.

[0151] Step S320 may include the following sub-steps.

[0152] S321: Convert the control signal from digital format to analog format.

[0153] S322: Control the magnitude of the operating current of the transmitter 61 based on the control signal in analog format to control the wavelength of the laser light emitted by the transmitter 61 toward the film 31.

[0154] Specifically, as described above, the processing unit 40 includes a processing module 42. The optimal operating point of the laser self-mixing device 60 is calculated by the processing module 42 based on the first voltage signal V1 in digital signal format. Therefore, before calculating the optimal operating wavelength of the laser light, the conversion module 41 must further convert the first voltage signal V1 in analog format into digital format. After the calculation is completed, the processing module 42 must further return the calculation result to the conversion module 41, which then converts the calculation result from digital format into an analog control signal in analog signal format. The transmitter 61 then receives the analog control signal and controls the magnitude of the operating current to control the wavelength of the laser light emitted by the transmitter 61.

[0155] In FIG. 15, step S310 "convert the first voltage signal V1 from analog format to digital format" may be realized by step S210 "convert the first voltage signal V1 or the second voltage signal V2 to digital signal format."

[0156] In one embodiment, the method according to the present application comprises: setting the feedback strength C of the laser self-mixing device 60 to less than 1; It may further include:

[0157] Specifically, in this embodiment, the feedback strength of the laser self-mixing device 60 can be understood as the change in the intensity and frequency of the laser light obtained when the laser light transmitted by the transmitter 61 self-mixes in the sound-collecting cavity, combines propagation medium gain and optical loss, and undergoes phase superposition, relative to the intensity and frequency of the initially emitted laser light. The feedback strength is related to the height of the front cavity of the microphone 100, the reflectivity of the reflecting portion 312, the laser linewidth, the frequency of the laser light, and the height of the resonant cavity of the laser self-mixing device 60. When the feedback strength C>1, the optical signal received by the receiver 62 may undergo a phase change and may be accompanied by high phase noise. When the feedback strength C=1, the phase jump and phase noise of the distortion signal are correspondingly reduced. When the feedback strength C<1, no phase jump occurs in the optical signal received by the receiver 62, and the phase noise is relatively low. Therefore, in this embodiment, the feedback strength of the laser self-mixing device 60 is controlled, and as a result, the quality of the laser signal received by the receiver 62 can be guaranteed.

[0158] The above description is merely a specific embodiment of the present application and is not intended to limit the scope of protection of the present application. Any modifications or substitutions that are easily conceivable by those skilled in the art within the technical scope disclosed in the present application, such as removing or adding structural members and changing the shape of structural members, shall fall within the scope of protection of the present application. The embodiments and features of the embodiments of the present application may be combined with each other unless a contradiction occurs. Therefore, the scope of protection of the present application shall be subject to the scope of protection of the claims. [Explanation of symbols]

[0159] 10 Substrate 11 Sound pickup hole 20 Protective cover 21 Protective Plate 22 Protective wall 23 Inner cavity 30 Diaphragm device 31 Membrane 32 Back cavity 33 Sound pickup cavity 40 Processing section 41 Conversion Module 42 Processing Module 60 Laser self-mixing device 61 Transmitter 62 Receiver 63 Transimpedance Amplifier 64 operational amplifiers 65 Low-pass filter 66 High-pass filter 100 microphones 200 Electronic Devices 201 Control Chip 202 Audio Decoding Unit 203 Audio amplifier 204 Speaker 311 Main Unit 311a First Side 311b Second Side 312 Reflector 313 Barrier Layer 313a, 313b thermal oxidation layer 314 Piezoresistive sensing part 315 Transmission Unit 315b via 316 Protective layer 317 Balance hole 318 Metal layer 319 Transmission Line 321 Through hole 322 Containment Area 341 Piezoresistive Diaphragm Chip 342 Piezoelectric diaphragm chip A1 First current signal V0 Pre-set threshold V1 First voltage signal V2 Second voltage signal VT1 First modulated voltage signal C Feedback Strength H distance

Claims

1. 1. A method of sound capture applied to a microphone, the microphone comprising a laser self-mixing device and a diaphragm device, the diaphragm device comprising a membrane, the membrane configured to respond to sound vibrations, the laser self-mixing device and the diaphragm device separately configured to detect vibrations of the membrane; The method comprises: obtaining a first voltage signal using the laser self-mixing device and simultaneously obtaining a second voltage signal using the diaphragm device; converting the first voltage signal into an audio signal if the first voltage signal is equal to or less than a lower limit of a preset threshold, or converting the second voltage signal into an audio signal if the first voltage signal is greater than an upper limit of the preset threshold; when converting the first voltage signal into an audio signal, continuously converting the first voltage signal into an audio signal if the first voltage signal does not exceed an upper limit of the preset threshold; or when converting the second voltage signal into an audio signal, continuously converting the second voltage signal into an audio signal if the first voltage signal is equal to or greater than a lower limit of the preset threshold.

1. A method for capturing audio, comprising:

2. The laser self-mixing device includes a transmitter and a receiver, and the step of obtaining a first voltage signal using the laser self-mixing device includes: controlling the transmitter to emit laser light toward the film; receiving the laser light reflected by the film using the receiver to form a first current signal; modulating the first current signal into the first voltage signal; 2. The audio capture method of claim 1, comprising:

3. the laser self-mixing device further comprises a transimpedance amplifier and an operational amplifier; The step of modulating the first current signal into the first voltage signal includes: converting the first current signal to a first modulated voltage signal using the transimpedance amplifier; amplifying the first modulated voltage signal using the operational amplifier; filtering the amplified first modulated voltage signal to form the first voltage signal; 3. The audio capture method of claim 2, comprising:

4. The diaphragm device includes a diaphragm chip, and the step of obtaining a second voltage signal using the diaphragm device includes: using the diaphragm tip to collect strain signals generated by the displacement of the membrane; converting the distortion signal into the second voltage signal; 2. The audio capture method of claim 1, comprising:

5. forming a control signal based on the first voltage signal and outputting the control signal to the transmitter to adjust the wavelength of the laser light emitted toward the film; The audio capture method of claim 2 further comprising:

6. forming a control signal based on the first voltage signal and outputting the control signal to the transmitter to adjust the wavelength of the laser light emitted toward the film, obtaining an optimum operating wavelength of the laser light by calculation based on the first voltage signal to form the control signal; controlling a magnitude of an operating current of the transmitter based on the control signal to control the wavelength of the laser light emitted toward the membrane; 6. The audio capture method of claim 5, comprising:

7. 2. The method of claim 1, wherein the feedback coefficient C of the laser self-mixing device is less than 1.

8. 8. An electronic device comprising a microphone, the microphone collecting sound using the sound capture method according to any one of claims 1 to 7.

9. A microphone for capturing sound using the sound capture method of claim 1, comprising: The laser beam splitter includes a substrate, a protective cover, a laser self-mixing device, a vibration plate device, and a processing section; the protective cover and the processing section are both fixed to the substrate, the protective cover and the substrate form an internal cavity via a housing, the laser self-mixing device and the diaphragm device are fixed in the internal cavity and are each communicatively connected to the processing section; the diaphragm device includes a membrane and a back cavity, the back cavity is fixed to the substrate, the membrane is located on the opposite side of the back cavity from the substrate, and the membrane and the back cavity form a sound-collecting cavity via a housing on the substrate; the laser self-mixing device includes a transmitter and a receiver, both of which are housed in the sound pickup cavity and fixed to the substrate, the transmitter being configured to emit laser light toward the film, and the receiver being configured to receive the laser light reflected by the film; The substrate is further provided with a plurality of sound pickup holes, and the sound pickup cavity is in communication with the outside via the plurality of sound pickup holes. microphone.

10. 10. The microphone of claim 9, wherein the film comprises a reflective portion located on a surface of the film facing the substrate, and the laser light emitted from the transmitter is received by the receiver after being reflected by the reflective portion.

11. The microphone of claim 10, wherein the reflector is located at the geometric center of the film, and the transmitter and receiver on the substrate are located within a projection area of ​​the reflector on the substrate.

12. 10. The microphone of claim 9, wherein the diaphragm device comprises a diaphragm chip configured to detect vibrations of the membrane, form a second voltage signal, and transmit the second voltage signal to the processing unit.

13. 13. A microphone according to claim 12, wherein the membrane is a piezoelectric membrane or a piezoresistive membrane and the diaphragm tip is a piezoelectric diaphragm tip or a piezoresistive diaphragm tip, respectively.

14. 10. The microphone according to claim 9, wherein the thickness D of the film satisfies the condition 0.1 μm≦D≦1 μm.

15. 11. The microphone according to claim 10, wherein a distance H between the reflecting portion and the transmitter satisfies the condition 20 μm≦H≦100 μm.

16. 15. An electronic device comprising a microphone according to any one of claims 9 to 14, the microphone being configured to collect an audio signal.

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