Acoustic transducer device and method of calibrating the same

Abstract

The application provides an acoustic transducing device and a calibration method thereof, comprising a transducer and an acoustic waveguide structure, the transducer has a sensing surface for receiving or emitting acoustic wave signals, the acoustic waveguide structure comprises two or more physical acoustic paths, each physical acoustic path forms acoustic communication with the sensing surface; at least one physical acoustic path is provided with an acoustic path switching unit correspondingly, the acoustic path switching unit has a first state and a second state, and the acoustic path switching unit can be switched from the first state to the second state through an irreversible switching mode. The acoustic transducing device is provided with the acoustic path switching unit with a state that cannot be reversibly changed in the acoustic waveguide structure, the state switching is triggered by external energy, the accurate reconstruction of the acoustic path of acoustic wave propagation is realized, and the repairable performance of the product is improved.

Description

Technical Field

[0001] This invention relates to the field of acoustic components technology, specifically to an acoustic transducer and its calibration method. Background Technology

[0002] Currently, in the mass production of microphones, i.e. miniature microphones and receivers, the acoustic performance of the final product fluctuates due to factors such as diaphragm tension fluctuations, packaging process tolerances, and overall assembly stress, which affects the final product yield.

[0003] Existing compensation methods aim to improve the precision of early-stage processes. However, in practice, since process-related equipment is generally fixed and processing technology is relatively mature, it is difficult to improve the yield of some components through process improvement. This is an inherent defect of manufacturing equipment. Generally, compensation methods rely on back-end circuit gain adjustment or digital signal processing (DSP). However, in actual operation, electrical compensation cannot completely correct sound parameters such as phase distortion and frequency fluctuation caused by the physical sound field, and it will increase system noise floor and power consumption. Therefore, how to achieve simple, reliable and low-cost performance compensation at the physical level is an urgent problem to be solved in the industry. Summary of the Invention

[0004] This invention provides an acoustic transducer that, by setting an acoustic path switching unit with irreversible state switching in the acoustic waveguide structure and using external energy to trigger state switching, achieves precise reconstruction of the acoustic path of sound wave propagation. In practical applications, the acoustic transducer can be manufactured according to standard procedures, and the acoustic parameters of the entire acoustic transducer can be adjusted by controlling the state of the acoustic path of sound wave propagation, thereby improving the repairability of the product to a certain extent and ensuring the production yield of the product.

[0005] Accordingly, the present invention discloses an acoustic transducer device, including a transducer and an acoustic waveguide structure. The transducer has a sensing surface for receiving or transmitting acoustic wave signals, and the acoustic waveguide structure includes two or more physical acoustic paths, each of which forms an acoustic connection with the sensing surface.

[0006] At least one of the physical acoustic paths is provided with an acoustic path switching unit, the acoustic path switching unit has a first state and a second state, and the acoustic path switching unit can switch from the first state to the second state in an irreversible switching manner;

[0007] When an acoustic path switching unit switches from the first state to the second state, the overall acoustic performance of the acoustic transducer changes directionally or quantitatively according to the physical acoustic path corresponding to the acoustic path switching unit.

[0008] In an optional implementation, in a physical acoustic path, when the acoustic path switching unit is in a first state, the corresponding physical acoustic path is cut off; when the acoustic path switching unit is in a second state, the corresponding physical acoustic path is partially or fully connected.

[0009] In an optional implementation, the acoustic path switching unit includes a removable structure disposed in the corresponding physical acoustic path, the removable structure being partially or completely removed using a non-contact removal method.

[0010] In an optional embodiment, the removable structure is made based on a corresponding removable material, and the removable material has a corresponding removal method;

[0011] Of all the physical acoustic paths, at least two of the physical acoustic paths use different removable materials for their removable structures.

[0012] In an optional embodiment, the transducer is fabricated on a circuit board substrate, and the acoustic waveguide structure is integrated on the circuit board substrate.

[0013] In an optional embodiment, the transducer has a protective housing, the sensing surface is located inside the protective housing, and the acoustic waveguide structure is integrated on the protective housing.

[0014] In an optional embodiment, the acoustic transducer further includes a housing, the transducer being located inside the housing, and the acoustic waveguide structure being integrated onto the housing.

[0015] Accordingly, the present invention also discloses a calibration method for an acoustic transducer, used to calibrate the overall acoustic performance of the acoustic transducer, comprising:

[0016] Obtain the original acoustic performance of the acoustic transducer to be calibrated, and compare the original acoustic performance with the preset standard acoustic performance to determine the calibration content;

[0017] In the acoustic transducer, the physical acoustic path in the first state is selected as the candidate acoustic path, and the directional and / or quantitative changes in the total acoustic performance of each candidate acoustic path when it switches from the first state to the second state are obtained.

[0018] With the goal of achieving the calibration content, the optimal acoustic path is selected from the candidate acoustic paths according to the changed content;

[0019] The acoustic path switching unit in the optimal candidate acoustic path is switched from the first state to the second state.

[0020] Optional implementation methods, set of acoustic performance parameters , For the first One sound parameter, ;

[0021] The standard acoustic performance includes reference values ​​for the parameters and error ranges for the parameters, wherein the reference values ​​for the parameters are expressed as follows: The error range of the parameter is expressed as follows: , , For parameters The upper limit of the allowable error, For parameters The lower limit of the allowable error;

[0022] The original acoustic performance of the acoustic transducer is expressed as follows: ;

[0023] The performance difference between the standard acoustic performance and the original acoustic performance is defined as follows: ,in, ;

[0024] Define calibration content , For the error normalization value, in In parameters Error range At that time, ,exist In parameters Error range When outside, .

[0025] In summary, this invention provides an acoustic transducer and its calibration method. Based on the concept of programmable post-processing, it achieves irreversible switching of the physical acoustic path state by pre-setting corresponding physical compensation structures in multiple physical acoustic paths and utilizing non-contact energy processing methods such as laser ablation and electrothermal melting. This fundamentally solves the consistency problem caused by manufacturing equipment and processes in the mass production of micro acoustic transducers. This technical solution bypasses complex and unstable mechanical adjustment mechanisms and has advantages such as zero delay, zero noise, and phase fidelity compared to back-end circuit compensation methods. It can achieve high-precision and high-reliability performance alignment of acoustic devices of different production batches or even different types at extremely low additional costs, and has good practical implementation value. Attached Figure Description

[0026] Figure 1 This is a simplified structural diagram of the acoustic transducer device according to an embodiment of the present invention.

[0027] Figure 2This is a schematic diagram of an omnidirectional MEMS microphone structure.

[0028] Figure 3 This is a schematic diagram of a MEMS microphone structure that does not pick up sound from all directions.

[0029] Figure 4 This is a partial cross-sectional structural diagram of the circuit board substrate according to an embodiment of the present invention. Detailed Implementation

[0030] To further illustrate the technical means and effects adopted by this application to achieve its intended purpose, the specific implementation methods, structures, features, and effects according to this application are described in detail below with reference to the accompanying drawings and preferred embodiments. In the following description, different "an embodiment" or "an embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0031] Figure 1 This is a simplified structural diagram of the acoustic transducer device according to an embodiment of the present invention.

[0032] Specifically, the present invention discloses an acoustic transducer device, including a transducer and an acoustic waveguide structure.

[0033] Specifically, the transducer has at least one sensing surface 1 for receiving or transmitting acoustic signals. As the core component for converting acoustic signals into electrical signals, when acting as a receiver (such as a microphone), the sensing surface 1 receives acoustic vibrations and converts them into electrical signals; when acting as a transmitter (such as a receiver), the sensing surface 1 converts electrical signals into acoustic vibrations and radiates them outwards. In practice, the sensing surface 1 is generally located on one side of the diaphragm structure. Depending on specific requirements, both sides of the diaphragm structure can simultaneously serve as sensing surfaces 1. Due to the reversibility of the transducer (the receiver and transmitter are based on reversible technical principles), to avoid unnecessary complexity, the following description mainly focuses on the situation where the transducer acts as a receiver.

[0034] Specifically, the acoustic waveguide structure includes two or more physical acoustic paths 3, each of which has one end open to form an acoustic connection with the sensing surface 1. Each physical acoustic path 3 provides a specific acoustic path for sound wave propagation, extending from the transducer's sensing surface 1 to the external sound field environment or internal acoustic cavity of the device. In actual structural design, the acoustic waveguide structure is fabricated on a physical carrier, which typically has a relatively sealed connecting cavity 2 between the sensing surfaces 1. In practical implementation, one physical acoustic path 3 is considered as a channel for sound to travel from the outside to the sensing surface 1 (sound will not travel to the sensing surface 1 through other paths). By designing multiple parallel or branched physical acoustic paths 3, different physical options are provided for sound wave propagation.

[0035] Compared with the prior art, in the embodiments of the present invention, at least one of the physical acoustic paths 3 is provided with an acoustic path switching unit 4, the acoustic path switching unit 4 has a first state and a second state, and the acoustic path switching unit 4 can switch from the first state to the second state through an irreversible switching method.

[0036] When an acoustic path switching unit 4 switches from the first state to the second state, the overall acoustic performance of the acoustic transducer changes directionally or quantitatively according to the physical acoustic path 3 corresponding to the acoustic path switching unit 4.

[0037] Specifically, from the inherent structure of the acoustic transducer, the acoustic transducer of this embodiment is characterized by having multiple physical acoustic paths 3, each of which has an acoustic path switching unit 4. The state of the switching unit includes a first state and an irreversibly changing second state. Accordingly, the overall acoustic performance of the acoustic transducer is affected not only by the performance of the transducer itself but also by the combined influence of all physical acoustic paths 3. Therefore, according to the state combination of the multiple physical acoustic paths 3, for a specific acoustic transducer, by adjusting the state of the acoustic path switching unit 4, the acoustic transducer has a variety of selectable total acoustic performance.

[0038] From the perspective of the manufacturing process of the acoustic transducer, during the production process, all physical acoustic paths 3 and their corresponding acoustic path switching units 4 need to be manufactured. The state switching of the acoustic path switching units 4 can be adjusted as needed. In actual manufacturing, due to the inability to achieve complete consistency in the manufacturing process, all individual acoustic transducers manufactured have differences in overall acoustic performance. After identifying these differences through detection and other technical means, the state of the acoustic path switching units 4 is switched as needed, so that the individual acoustic transducers composed of different sets of physical acoustic paths 3 have similar (meeting performance requirements) overall acoustic performance. From this perspective, the structural feature of the acoustic transducer in this embodiment of the invention is a structure that maintains the consistency of the overall acoustic performance of the acoustic transducer under different sets of physical acoustic paths 3.

[0039] It should be noted that the irreversible operation described in the embodiments of the present invention means that once the acoustic path switching unit 4 switches from the first state to the second state, it cannot be automatically restored to the first state by conventional physical means or changes in environmental conditions. Therefore, in actual processing, the activation of the acoustic path switching unit 4 is actually a post-processing method. During the testing process after the acoustic transducer is produced, when parameters are mismatched, the acoustic performance of the acoustic transducer can be fine-tuned by activating the acoustic path switching unit 4. Finally, the structure of the acoustic transducer is such that some acoustic path switching units 4 are in the first state and some are in the second state.

[0040] From a basic implementation perspective, when the acoustic path switching unit 4 is in the first state, it cuts off the corresponding physical acoustic path 3, making the acoustic path completely closed or non-conductive. In this state, sound waves cannot propagate through the acoustic path, meaning the physical acoustic path 3 does not affect the acoustic performance of the acoustic transducer. When the acoustic path switching unit 4 is in the second state, it partially or fully conducts the corresponding physical acoustic path 3, restoring the acoustic path's sound wave propagation capability. In other words, the physical acoustic path 3 participates in influencing the acoustic performance of the acoustic transducer. In this basic implementation, the impact of opening the physical acoustic path 3 on the acoustic performance of the acoustic transducer is predictable (through testing or empirical methods). For example, opening a physical acoustic path 3 can enhance the relative amplitude of low-frequency sound waves. Therefore, in practice, the acoustic performance of the acoustic transducer can be selectively altered, allowing for the reconstruction of the acoustic waveguide network of the acoustic transducer by selectively activating specific physical acoustic paths 3. According to this embodiment, in the final product of the acoustic transducer, even if the physical acoustic path 3 is in the first state and does not affect the overall acoustic performance of the acoustic transducer, its structure will still exist in the acoustic transducer, thereby forming a redundant structure existing in the physical acoustic transducer. This structural feature can be clearly distinguished from other products under the prior art.

[0041] Furthermore, considering this perspective (physical acoustic path 3 is blocked in the initial state), at least one of the physical acoustic paths 3 is in the second state. This physical acoustic path 3 can be considered as the main acoustic path, used to ensure the basic acoustic performance of the acoustic transducer and ensure that the basic acoustic function of the transducer is realized. Only when the basic acoustic performance of the acoustic transducer does not meet the requirements is it necessary to activate other physical acoustic paths 3.

[0042] Furthermore, in this embodiment of the invention, since the acoustic performance adjustment of the acoustic transducer is mainly achieved by changing the path of sound waves from the outside to the sensing surface 1, common influencing factors include: among all the physical acoustic paths 3, two of the physical acoustic paths 3 have different cross-sectional shapes, and / or two of the physical acoustic paths 3 have different cross-sectional areas, and / or two of the physical acoustic paths 3 have different acoustic path lengths, and / or two of the physical acoustic paths 3 have different acoustic path trajectories. Through differentiated geometric parameter design, different acoustic paths possess different acoustic characteristics.

[0043] Specifically, differences in cross-sectional shape (circular, rectangular, elliptical, or irregular) can produce different acoustic impedance characteristics and resonant modes; differences in cross-sectional area directly affect acoustic impedance matching and sound wave transmission efficiency; differences in acoustic path length between different lengths can produce different phase delays and frequency selectivity characteristics; differences in acoustic path trajectories such as straight, curved, spiral, or bifurcated trajectories can achieve different sound wave directivity (the position of the sound wave pointing to the sensing surface 1) or filtering characteristics. It is important to note that in most application scenarios, due to the complexity of the sound wave sources received by the sensing surface 1, the impact of a single physical acoustic path 3 switching from the first state to the second state on the overall acoustic performance of the entire acoustic transducer is directional. Quantitative adjustment can only be achieved in laboratory environments and acoustic transducers with simple structures.

[0044] In order for the acoustic path switching unit 4 to effectively realize the functions required by the embodiments of the present invention, based on the consideration of manufacturability, the acoustic path switching unit 4 includes a removable structure disposed in the corresponding physical acoustic path 3. The removable structure can be partially or completely removed by a non-contact removal method.

[0045] Specifically, a non-contact removal method is used to remove the removable structure, primarily to avoid introducing additional factors that could affect the overall acoustic performance of the acoustic transducer. Specifically, the removable structure is made of a corresponding removable material, and the removable material has a corresponding removal method.

[0046] Specifically, the removable material generally employs energy-sensitive ablation materials. These energy-sensitive ablation materials can be selected from thermosensitive materials, photosensitive materials, electrolytic materials, laser ablation materials, etc., and can be ablated under specific forms of energy excitation, thereby achieving partial or complete removal of the material.

[0047] Specifically, during the irreversible transition of the acoustic path switching unit 4 from the first state to the second state, the removable structure is partially or completely removed based on the corresponding type of energy activation. In practical applications, the energy activation method, corresponding to the material used in the removable structure, includes, but is not limited to, applying a current pulse, laser irradiation, microwave heating, resistance wire heating, etc. In specific implementations, the removal process of the removable structure is fast and controllable, the acoustic path after switching is smooth inside, and the acoustic performance is stable.

[0048] It should be noted that the acoustic transducer in this embodiment of the invention does not specify a specific size. For acoustic transducers of different sizes, the corresponding size of the removable structure also varies. Regarding the ablation method of the removable structure, in most cases, the energy input needs to be focused on the ablation component to ensure accurate removal. Different energy activation methods have different levels of focus; for example, microwave heating is a spatial energy activation method, resistance wire heating is a range-based energy activation method, and laser irradiation is a precise point activation method. Processing removable structures of different sizes requires consideration of both the fabrication feasibility and the removal feasibility of the removable structure.

[0049] In all the described physical acoustic paths 3, the removable structures in two of these paths are made of different materials. Generally, for some very small-scale acoustic transducers, it is difficult to meet the accurate focusing performance requirements during material removal in practical implementation. By using materials sensitive to different energy types or energy levels, the purpose of selectively activating specific acoustic paths can be achieved. For example, the ablative component in the first acoustic path is sensitive to laser wavelength λ1, and the component in the second acoustic path is sensitive to laser wavelength λ2. By selecting different wavelengths of laser irradiation, the switching state of each acoustic path can be independently controlled; alternatively, the removable structure of one acoustic path can be made of a photosensitive material, and the removable structure of the other acoustic path can be made of a thermosensitive material, with different types of removal methods used for removal.

[0050] In terms of the removal principle of the removable structure, the lower-cost implementation method is laser removal. Accordingly, the removable structure can be processed on the physical acoustic path 3 and located at the outer opening (the opening on the other side of the sensing surface 1), and can be directly removed by laser focusing. This requires the acoustic transducer itself to have a surface structure that can be directly laser processed (without other structures blocking the outer opening of the physical acoustic path 3).

[0051] In addition, based on the differences in the physical structure of the acoustic transducer, the following state switching methods can also be selected:

[0052] Electrically driven switching, similar to eFuse technology in semiconductor chips, eliminates the need for optical windows in practical applications, as the switching is entirely completed within the acoustic transducer. Specifically, a miniature bridging conductor (made of low-melting-point metal alloys such as tin-bismuth alloys, doped polycrystalline silicon, or extremely thin aluminum films) is placed at the cut-off point of physical acoustic path 3. The two ends of this conductor are connected to the control circuit of the acoustic transducer or independently led-out test pads. During state switching, a momentary high-current pulse is input to the corresponding test pad. The Joule heating generated by the current causes the conductor to sublimate or melt rapidly, thereby opening the corresponding physical acoustic path 3.

[0053] The thermally driven switching method utilizes the phase change characteristics of materials at specific temperatures to change their physical state. Specifically, the desired removable structure is made of medical-grade paraffin, low-molecular-weight polymers, or shape memory polymers (SMP) with heat-shrink properties. The removable structure is heated by local infrared induction heating or by micro resistance wires integrated into the inner wall of the channel. After being heated, the material changes from solid to liquid and flows to the preset storage tank or the opening of the channel due to capillary action, thereby releasing the acoustic path. This switching method does not produce splashing metal vapor or smoke and can protect the sensing surface 1 from contamination.

[0054] Photochemical-driven, this state-switching method utilizes high-energy photons to directly break the chemical bonds of materials, rather than relying on heat. Specifically, it employs photodegradable polymers (such as polymethyl methacrylate containing specific photosensitive groups) and photoresist to create a removable structure. This removable structure can be fabricated as an ultra-thin transparent or semi-transparent film covering the outer opening of the physical acoustic channel. When the removable structure is irradiated with ultraviolet light of a specific wavelength, the ultraviolet light causes the long polymer chains to break into tiny volatile molecules or brittle residues. These are then removed by blowing with clean compressed air. This state-switching method does not generate thermal stress, protecting the high-precision diaphragm tension from being affected.

[0055] In practical implementation, based on current market acoustic transducer products, the acoustic transducer of this invention actually includes three main types of acoustic transducers, in ascending order of size: MEMS microphone, microphone device, and microphone equipment. Correspondingly, depending on the size and structural differences of the acoustic transducer, the acoustic waveguide structure can be fabricated on the corresponding physical carrier. This invention uses a MEMS microphone as an example for illustration. Microphone devices and microphone equipment are larger in size, and the relevant processing methods of MEMS microphones can be easily converted and applied to microphone devices and microphone equipment; therefore, this invention will not provide further explanation in this embodiment.

[0056] Specifically, Figure 2This is a schematic diagram of an omnidirectional MEMS microphone structure. Figure 3 This is a schematic diagram of a MEMS microphone structure that does not pick up sound from all directions.

[0057] Specifically, when the acoustic transducer is a MEMS microphone, the transducer is fabricated on a circuit board substrate 101, and the acoustic waveguide structure is integrated on the circuit board substrate 101.

[0058] Specifically, for a conventional omnidirectional MEMS microphone, its basic structure includes a circuit board substrate 101, a micro-support fabricated on the circuit board substrate 101, a micro-diaphragm 103 fabricated on the micro-support, an integrated chip fabricated on the circuit board substrate 101, and a protective cover 104. The periphery of the protective cover 104 is fixed on the circuit board substrate 101, and a relatively sealed cavity is formed inside it, which encloses the other components.

[0059] In the existing technology, a first pickup hole 102 is opened on the circuit board substrate 101 to allow external sound to enter the cavity and trigger the micro diaphragm from the bottom side of the micro diaphragm 103; for a non-omnidirectional MEMS microphone, a second pickup hole 105 is opened on the protective cover 104 to allow external sound to enter the cavity and trigger the micro diaphragm from the top side of the micro diaphragm.

[0060] For a specific type of MEMS acoustic transducer, its acoustic performance is the result of multiple factors, some of which are uncontrollable factors arising from the manufacturing process. This can lead to fluctuations in the acoustic performance of the final product, potentially resulting in a large number of defective products when high consistency is required in the acceptance criteria. The fluctuations in acoustic performance are largely due to errors in the processing equipment. The most direct solution is to replace the equipment with higher precision equipment, but this is costly. Furthermore, even products manufactured with higher precision equipment may encounter similar problems. The fundamental solution lies in further improving the consistency of the acoustic performance of the produced acoustic transducers within the same equipment system. Based on this objective, the solution provided by this invention is to adjust the relevant implementation methods of the pickup hole.

[0061] Specifically, on the one hand, due to limitations in the manufacturing process, the internal structures of MEMS microphones, such as micro-supports and micro-diaphragms, are difficult to adjust after processing. On the other hand, since the micro-supports and micro-diaphragms are located internally, even if they can be adjusted, it is necessary to disassemble the housing and other structures, and then reassemble them after adjustment. Since the housing and other structures themselves and their fixing structures also affect the acoustic performance of the acoustic transducer, adjusting the internal structures such as micro-supports and micro-diaphragms would introduce more influencing variables and is not practically feasible. Therefore, the acoustic transducer of this invention mainly improves the implementation methods related to the pickup hole.

[0062] Figure 4 This is a partial cross-sectional structural diagram of the circuit board substrate 101 according to an embodiment of the present invention. The corresponding position in this diagram is actually the location of the first pickup hole 102.

[0063] Specifically, for an omnidirectional MEMS microphone, the bottom surface of the micro-diaphragm is the sensing surface 1. Correspondingly, the circuit board substrate 101 is the structural carrier of the acoustic waveguide structure. The circuit board substrate 101 includes multiple circuit layers 106 combined to form the acoustic path 3, which is essentially a channel structure processed on the circuit board. The embodiment of the present invention is illustrated in the schematic diagram. Figure 4 The diagram illustrates five physical acoustic paths 3, numbered A to E. Specifically, the methods for forming the required physical acoustic paths 3 on the circuit board substrate 101 include drilling, etching, laser penetration, and layer processing. After the required physical acoustic paths 3 are obtained, the acoustic path switching unit 4 is then processed.

[0064] Specifically, the acoustic path switching unit 4 is a physical structure set in the physical acoustic path 3. First, regarding the specific structural form of the acoustic path switching unit 4, in the first state, the acoustic path switching unit 4 can completely fill the corresponding physical acoustic path 3, or it can be a local structure within the physical acoustic path 3, or it can be a local result at one or both ends of the physical acoustic path 3. In actual implementation, the specific structural form of the acoustic path switching unit 4 is related to the materials and processing methods used, and this related content has been fully explained and introduced in the foregoing description.

[0065] For removing removable components, laser removal is a cost-effective and efficient method. Laser removal offers excellent focusing performance, effectively targeting even small removable components. Correspondingly, when using laser removal, the ablable component is typically positioned at the outer opening of the physical acoustic path 3. Figure 4 The bottom position of the circuit board substrate 101 structure shown ensures that the laser can effectively remove removable components.

[0066] It should be noted that in actual implementation, if laser removal is used, it is currently difficult to completely and precisely control the removal of removable components during ablation. However, the parameter adjustment orientation resulting from the removal of removable components is consistent. For example, the function of a physical acoustic path 3 is to improve the low frequency of the sound signal. The removal ratio of removable components affects the magnitude of low frequency improvement, without resulting in completely different adjustment effects. In practice, removable components may introduce some undesirable sound parameter adjustment results under certain extreme structural changes. Since the structural improvement features of the acoustic transducer in this embodiment are essentially a compensation method, acoustic transducers with unsatisfactory compensation results can be abandoned.

[0067] Based on the MEMS microphones described above, the physical structure of the acoustic transducer changes as the microphone size increases.

[0068] For example, the transducer has a protective housing (similar to the protective cover 104 described above), and the acoustic waveguide structure is integrated into the protective housing. The protective housing is typically made of metal or rigid plastic, and the acoustic waveguide structure can be directly formed into the inner wall of the housing using insert molding, 3D printing, or micromachining techniques, resulting in a compact structure that does not compromise the protective performance of the transducer itself.

[0069] As a further improvement of the present invention, the acoustic transducer also includes a housing that encloses the transducer, and the acoustic waveguide structure is integrated onto the housing. This design is suitable for modular product design, where the transducer and acoustic waveguide structure are assembled as independent modules within the housing of the final product, facilitating maintenance, replacement, and customization of acoustic performance.

[0070] Furthermore, the transducer can be one of the following types: a MEMS microphone, an electret microphone, a miniature receiver, or an ultrasonic sensor. The technical solution of this invention has good versatility and can be applied to various miniature acoustic transducer products. Among them, MEMS microphones benefit from the compatibility of semiconductor processes, making it easiest to implement the high-integration design of this invention; electret microphones can achieve performance upgrades through this invention; miniature receivers can switch between earpiece mode and hands-free mode through acoustic path switching; and ultrasonic sensors can achieve optimization of different detection distances and accuracies through acoustic path reconstruction.

[0071] Accordingly, this invention also discloses a calibration method for an acoustic transducer, used to calibrate the overall acoustic performance of the acoustic transducer. Specifically, in conjunction with the preceding description of the acoustic transducer, after production, the main acoustic path of the acoustic transducer is activated, possessing its original acoustic performance. During the inspection of the acoustic transducer, if the original acoustic performance does not meet the performance requirements, the overall acoustic performance of the acoustic transducer can be adjusted by switching the state of the physical acoustic path 3. This process is ultimately a compensation and repair method, and in terms of implementation, it is a calibration method. It should be noted that the overall acoustic performance of the acoustic transducer after final calibration may not necessarily meet the requirements for a good product, but it provides a feasible technical means for repairing defective products.

[0072] In practice, acoustic transducers are manufactured using various processing equipment. Due to limitations of the equipment or processes, the defect rate of some high-requirement products may exceed 30%. Through the structural design of the acoustic transducer and the corresponding calibration method in this invention, a large number of defective products can be repaired. This can be understood as breaking through the processing quality limits of existing equipment or processes.

[0073] Specifically, the acoustic transducer calibration method disclosed in this embodiment of the invention includes:

[0074] S101: Obtain the original acoustic performance of the acoustic transducer to be calibrated, and compare the original acoustic performance with the preset standard acoustic performance to determine the calibration content;

[0075] Acoustic performance is actually a set of multiple acoustic parameter data. For microphones, the most important parameter is their ability to pick up and reproduce sound at various frequencies. In practice, multiple frequency parameters can be identified by frequency segmentation, with the average value used as the standard value for each frequency parameter and a corresponding allowable error range set. Other acoustic parameters can be set according to requirements.

[0076] Specifically, assuming a set of parameters for acoustic performance , For the first One sound parameter, ;

[0077] The standard acoustic performance includes reference values ​​for the parameters and error ranges for the parameters, wherein the reference values ​​for the parameters are expressed as follows: The error range of the parameter is expressed as follows: , , For parameters The upper limit of the allowable error, For parameters The lower limit of the allowable error;

[0078] Accordingly, the original acoustic performance of the acoustic transducer is expressed as follows: ;

[0079] Correspondingly, the performance difference between the standard acoustic performance and the original acoustic performance is defined as... ,in, ;

[0080] Accordingly, define the calibration content. , For the error normalization value, in In parameters Error range At that time, ,exist In parameters Error range When outside, .

[0081] In this embodiment of the invention, in addition to the calibration content itself, the calibration method also adds a weighting characteristic (based on normalized data) to the calibration content according to actual needs. Specifically, this weighting characteristic is mainly used to reflect the adjustment priority of parameters of greater interest.

[0082] Ultimately, through calibration, a clear evaluation value, similar to a score, can be obtained for each sound parameter within a unified evaluation system. Sound parameters with relatively higher evaluation values ​​have priority in calibration.

[0083] From another practical perspective, since this calibration method can be repeated multiple times, the parameter with the largest deviation range should be adjusted first to avoid other adjustment methods from further increasing the deviation value of the parameter with the largest deviation range, thus making calibration impossible.

[0084] S102: Select the physical acoustic path in the first state as the candidate acoustic path in the acoustic transducer, and obtain the directional and / or quantitative changes in the total acoustic performance when each candidate acoustic path switches from the first state to the second state.

[0085] S103: With the goal of achieving the calibration content, select the optimal acoustic path from the candidate acoustic paths according to the changed content;

[0086] Correspondingly, for a specific type of acoustic transducer, in the evaluation system constructed in step S101, the contribution of the state switching of each physical acoustic path to the evaluation value of the parameter is directionally quantifiable (this quantification is generally a range value). According to the requirements of the calibration content, the optimal candidate acoustic path is selected.

[0087] S104: Switch the acoustic path switching unit in the optimal candidate acoustic path from the first state to the second state.

[0088] Correspondingly, according to the aforementioned description of the acoustic path switching unit, the removable structure is processed using corresponding technical means, and the acoustic path switching unit switches from the first state to the second state, giving the acoustic transducer a new physical structure and new overall sound performance. At this point, the overall sound performance of the calibrated acoustic transducer can be tested, and the calibration method of this embodiment can be repeated until all acoustic path switching units switch from the first state to the second state. If switching all acoustic path switching units from the first state to the second state still fails to meet the performance requirements of the acoustic transducer, then the acoustic transducer can only be classified as a defective product for further processing.

[0089] It should be noted that for acoustic transducers obtained from the same equipment cluster and the same processing flow, the defects of the final defective products are mostly the same. Correspondingly, when designing the physical acoustic path in the acoustic transducer, it is still necessary to target the defects in the equipment to make it more targeted and improve the success rate of repairing defective products.

[0090] In summary, this invention provides an acoustic transducer and its calibration method. Based on the concept of programmable post-processing, it achieves irreversible switching of the physical acoustic path state by pre-setting corresponding physical compensation structures in multiple physical acoustic paths and utilizing non-contact energy processing methods such as laser ablation and electrothermal melting. This fundamentally solves the consistency problem caused by manufacturing equipment and processes in the mass production of micro acoustic transducers. This technical solution bypasses complex and unstable mechanical adjustment mechanisms and has advantages such as zero delay, zero noise, and phase fidelity compared to back-end circuit compensation methods. It can achieve high-precision and high-reliability performance alignment of acoustic devices of different production batches or even different types at extremely low additional costs, and has good practical implementation value.

[0091] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An acoustic transducer device, comprising a transducer and an acoustic waveguide structure, wherein the transducer has a sensing surface for receiving or transmitting acoustic wave signals, and the acoustic waveguide structure comprises two or more physical acoustic paths, each of the physical acoustic paths forming an acoustic connection with the sensing surface. Its features are, At least one of the physical acoustic paths is provided with an acoustic path switching unit, the acoustic path switching unit has a first state and a second state, and the acoustic path switching unit can switch from the first state to the second state in an irreversible switching manner; When an acoustic path switching unit switches from the first state to the second state, the total acoustic performance of the acoustic transducer changes directionally or quantitatively according to the physical acoustic path corresponding to the acoustic path switching unit. The acoustic path switching unit includes a removable structure disposed in the corresponding physical acoustic path, and the removable structure can be partially or completely removed using a non-contact removal method. In a physical acoustic path, when the acoustic path switching unit is in the first state, the corresponding physical acoustic path is cut off; when the acoustic path switching unit is in the second state, the corresponding physical acoustic path is partially or fully connected.

2. The acoustic transducer as described in claim 1, characterized in that, The removable structure is made based on a corresponding removable material, and the removable material has a corresponding removal method; Of all the physical acoustic paths, at least two of the physical acoustic paths use different removable materials for their removable structures.

3. The acoustic transducer as described in claim 1, characterized in that, The transducer is fabricated on a circuit board substrate, and the acoustic waveguide structure is integrated on the circuit board substrate.

4. The acoustic transducer as described in claim 1, characterized in that, The transducer has a protective housing, the sensing surface is located inside the protective housing, and the acoustic waveguide structure is integrated on the protective housing.

5. The acoustic transducer as described in claim 1, characterized in that, The acoustic transducer also includes a housing, the transducer is located inside the housing, and the acoustic waveguide structure is integrated on the housing.

6. A calibration method for an acoustic transducer, characterized in that, For calibrating the overall acoustic performance of the acoustic transducer according to any one of claims 1 to 5, including: Obtain the original acoustic performance of the acoustic transducer to be calibrated, and compare the original acoustic performance with the preset standard acoustic performance to determine the calibration content; In the acoustic transducer, the physical acoustic path in the first state is selected as the candidate acoustic path, and the directional and / or quantitative changes in the total acoustic performance of each candidate acoustic path when it switches from the first state to the second state are obtained. With the goal of achieving the calibration content, the optimal acoustic path is selected from the candidate acoustic paths according to the changed content; The acoustic path switching unit in the optimal candidate acoustic path is switched from the first state to the second state.

7. The acoustic transducer calibration method as described in claim 6, characterized in that, Set of parameters for acoustic performance , For the first One sound parameter, ; The standard acoustic performance includes reference values ​​for the parameters and error ranges for the parameters, wherein the reference values ​​for the parameters are expressed as follows: The error range of the parameter is expressed as follows: , , For parameters The upper limit of the allowable error, For parameters The lower limit of the allowable error; The original acoustic performance of the acoustic transducer is expressed as follows: ; The performance difference between the standard acoustic performance and the original acoustic performance is defined as follows: ,in, ; Define calibration content , For the error normalization value, in In parameters Error range At that time, ,exist In parameters Error range When outside, .

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