Microphone diaphragm consistency test system and method

Abstract

The embodiment of the present disclosure discloses a microphone diaphragm consistency test system and method, which comprises a sound source device, a control element, a detection audio emitting device, a measurement microphone back plate, a vibration acquisition device and a calculation output device. The control element is used for controlling the sound source device to emit the detection audio. The measurement microphone back plate is combined with the diaphragm to be tested to form a capacitor body, and is used for forming feedback with the resonance audio of the diaphragm to be tested. The vibration acquisition device is connected with the calculation output device, and is used for receiving the feedback audio of the capacitor body and transmitting the feedback audio to the calculation output device in real time. The diaphragm to be tested is arranged opposite to the measurement microphone back plate, and a gap exists between the diaphragm to be tested and the measurement microphone back plate to form the capacitor body. The vibration acquisition device is arranged opposite to the capacitor body. The sound source device is arranged opposite to the capacitor body and the vibration acquisition device. Through the system, the diaphragm with obvious vibration is convenient and accurate, the detection method is convenient, and the accuracy and efficiency are high.

Description

Technical Field

[0001] This disclosure relates to the field of microphone diaphragm testing technology, specifically to a microphone diaphragm consistency testing system and method. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of this disclosure and is not necessarily an admission or implication in any way that such information constitutes related technology that is already known to those skilled in the art.

[0003] In related technologies, the testing of microphone diaphragms is mainly carried out through resonance equipment. However, resonance equipment can generally only test assembled microphones, that is, test the microphone itself. The testing process involves placing the microphone on a test platform, setting up a corresponding pickup element, and positioning it opposite the sound-generating unit. A resonance diaphragm is placed between the sound-generating unit and the test platform. After the sound is emitted by the sound-generating unit, it is transmitted to the microphone through the resonance diaphragm, and then the resonant frequency is detected to obtain the test result. This mechanism requires the diaphragm to be assembled into the microphone to achieve this, thus wasting a lot of assembly time. Furthermore, the use of a resonance diaphragm during the testing process makes it prone to interference, leading to inaccurate test results. Summary of the Invention

[0004] Therefore, this disclosure provides a microphone diaphragm consistency testing system and method to achieve the goal of accurately detecting the comprehensive performance of the microphone diaphragm.

[0005] To achieve the above objectives, the embodiments of this disclosure provide the following technical solutions: In a first aspect of the embodiments of this disclosure, a microphone diaphragm conformance testing system is provided, comprising: A sound source device, controlled by control elements, is used to emit detection audio. The measuring microphone's rear electrode plate, combined with the diaphragm under test, forms a capacitor body, which is used to generate feedback from the resonant audio of the diaphragm under test. A vibration acquisition device, connected to a computing output device, is used to receive feedback audio from the capacitor body and transmit it to the computing output device in real time. The diaphragm to be tested is positioned opposite to the rear electrode plate of the measuring microphone, with a gap between them forming a capacitor body. The vibration acquisition device is positioned opposite to the capacitor body, and the sound source device is positioned opposite to both the capacitor body and the vibration acquisition device.

[0006] In one disclosed embodiment, the vibration acquisition device is a condenser microphone, the sound source device is a coaxial speaker, and an open copper plate is provided on the rear electrode side of the measuring microphone, with the diaphragm to be tested disposed in the open hole.

[0007] In one disclosed embodiment, the diaphragm under test includes a metal ring with uniform surface stress, and a flexible film is adhesively bonded to the metal ring.

[0008] In a second aspect of the embodiments of this disclosure, a method for testing the consistency of a microphone diaphragm is provided, applicable to any of the above-mentioned systems, comprising the following steps: Step 1: Establish a microphone diaphragm consistency testing system, set the relative positional relationships, and select various diaphragms to be tested according to the application field; Step 2: Control the sound source device to emit a frequency sweep signal, and calculate the average value of the test results based on the data collected by the vibration acquisition device; Step 3: Calculate the relationship between the output fundamental frequency results of the diaphragm under different conditions based on the average data of the output device. The different states of the diaphragm include the diameter and structure of the diaphragm.

[0009] In one disclosed embodiment, the selection of the diaphragm includes determining different diameters and structures while keeping the material and thickness the same.

[0010] In one disclosed embodiment, the diaphragm is made of polyphenylene sulfide film or polyethylene terephthalate film with a thickness of 6 μm.

[0011] In one disclosed embodiment, the analysis process of the computing output device involves using acoustic excitation modes to pick up sound signals through both acoustic sensors and optical sensors.

[0012] According to the embodiments of this disclosure, the system has the following advantages: it includes a sound source device controlled by a control element to emit detection audio; a measuring microphone rear electrode plate, which is combined with the diaphragm under test to form a capacitor body, used to generate feedback from the resonant audio of the diaphragm under test; a vibration acquisition device connected to a computing output device, used to receive the feedback audio from the capacitor body and transmit it to the computing output device in real time; the diaphragm under test and the measuring microphone rear electrode plate are arranged opposite each other, with a gap between them forming the capacitor body; the vibration acquisition device is arranged opposite to the capacitor body; the sound source device is arranged opposite to the capacitor body and the vibration acquisition device. Through this system setup, during the detection process, the fundamental frequency of the diaphragm can be determined based on the relationship between the diaphragm and the vibration acquisition device when the diaphragm vibrates and the vibration frequency result. This method is convenient and accurate for diaphragms with significant vibration, and the detection method is convenient, accurate, and efficient.

[0013] This method offers significant engineering practical value for low-cost, high-volume, and rapid screening of medium-to-large microphone diaphragms. Testing can be performed without assembling the diaphragm into a complete microphone, simplifying the testing process and facilitating rapid screening during production. The system structure is simple, mainly consisting of a sound source, a backplate, and a data acquisition device. Compared to complex laser vibration measurement systems, it is lower in cost and easier to implement. It offers advantages in terms of low cost and ease of operation. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments or related technologies of this disclosure, the accompanying drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0015] The structures, proportions, sizes, etc. illustrated in this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the conditions under which this disclosure can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effectiveness and purpose that this disclosure can achieve, should still fall within the scope of the technical content disclosed herein.

[0016] Figure 1 This is a schematic diagram of a microphone diaphragm conformance testing system according to an exemplary embodiment. Figure 2 An analytical model for a microphone diaphragm conformance testing method illustrated according to an exemplary embodiment; Figure 3 An electro-acoustic analog model of a photoacoustic microphone head shown according to an exemplary embodiment.

[0017] In the diagram: 1. Sound source device; 2. Measuring microphone back plate; 3. Vibration acquisition device; 4. Calculation output device; 5. Diaphragm to be tested. Detailed Implementation

[0018] The following specific embodiments illustrate the implementation of this disclosure. Those skilled in the art can easily understand other advantages and effects of this disclosure from the content disclosed in this specification. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0019] The terms “upper,” “lower,” “left,” “right,” and “middle” used in this specification are merely for clarity of description and are not intended to limit the scope of this disclosure. Any changes or adjustments to their relative relationships, without substantially altering the technical content, shall also be considered within the scope of this disclosure.

[0020] like Figure 1 The diagram shows a schematic representation of a microphone diaphragm conformance testing system according to an embodiment. The system includes... A sound source device, controlled by control elements, is used to emit detection audio. The measuring microphone's rear electrode plate, combined with the diaphragm under test, forms a capacitor body, which is used to generate feedback from the resonant audio of the diaphragm under test. A vibration acquisition device, connected to a computing output device, is used to receive feedback audio from the capacitor body and transmit it to the computing output device in real time. The diaphragm under test and the rear electrode plate of the measuring microphone are positioned opposite each other, with a gap between them forming a capacitor body. The vibration acquisition device is positioned opposite the capacitor body, and the sound source device is positioned opposite the capacitor body and the vibration acquisition device.

[0021] By setting up this system, the fundamental frequency of the diaphragm can be determined during the detection process based on the relationship between the diaphragm and the vibration acquisition device when the diaphragm vibrates, as well as the vibration frequency result. This method is convenient and accurate for diaphragms with obvious vibrations, and the detection method is convenient, accurate and efficient.

[0022] The system has a simple structure and low cost: The system mainly consists of a sound source device, a measuring microphone back plate, a vibration acquisition device, and a calculation output device. All of these are general-purpose components, and the hardware cost is lower than that of non-contact solutions such as laser vibration measurement. Moreover, it does not require supporting facilities such as a precision vibration isolation platform, making it easy to deploy in a production environment.

[0023] In this system, the microphone diaphragm under test and the fixed measuring microphone rear plate form a parallel capacitor. When a sweep signal (frequency range 100Hz-20kHz) emitted from the speaker acts on the diaphragm, the gap H between the diaphragm and the rear plate changes, causing a change in the microphone capacitance. Therefore, when the frequency of the sweep signal is the same as the diaphragm's fundamental frequency, the diaphragm resonates. At this point, the diaphragm's vibration displacement is at its maximum, meaning the distance between the diaphragm and the rear plate is at its minimum, and the variable capacitance is at its maximum. Consequently, the amplitude of the output voltage signal is at its maximum. Analyzing the test results, the diaphragm's fundamental frequency can be obtained.

[0024] The equipment for acquiring diaphragm vibrations is a custom-designed condenser microphone, where the diaphragm under test replaces the original nickel diaphragm. The sound source is a coaxial speaker. To facilitate the measurement of the diaphragm's fundamental frequency, a perforated copper plate is added to hold the diaphragm under test. The fundamental frequency of the diaphragm measured by the testing system will be slightly affected by the perforated copper plate.

[0025] In a second aspect of the embodiments of this disclosure, a method for testing the consistency of a microphone diaphragm is provided, applicable to any of the above-mentioned systems, comprising the following steps: Step 1: Establish a microphone diaphragm consistency testing system, set the relative positional relationships, and select various diaphragms to be tested according to the application field; Step 2: Control the sound source device to send out a frequency sweep signal, and calculate the average value of the test results based on the data collected by the vibration acquisition device; Step 3: Calculate the relationship between the output fundamental frequency results of the diaphragm under different conditions based on the average data of the output device. Among them, the different states of the diaphragm include the diameter and structure of the diaphragm.

[0026] Easy to operate and highly efficient in screening: It adopts a non-assembly direct test mode, so the diaphragm under test does not need to be pre-assembled into a complete microphone to perform fundamental frequency testing, which greatly simplifies the testing process and saves assembly time. It is especially suitable for rapid screening of large batches of diaphragms.

[0027] Specifically, diaphragm selection involves choosing different diameters and structures while keeping the material and thickness the same.

[0028] Selection of diaphragms to be tested: 1. Diaphragms with a front cavity in the metal ring and an outer diameter of 20 mm; 2. Diaphragms without a front cavity in the metal ring, wherein the outer diameters of the diaphragms are 14 mm, two types of 16 mm (one type has an embossed pattern on the surface of the diaphragm, and the other type has a normal surface), 20 mm, and 34 mm.

[0029] This vibration measurement method yields the fundamental frequency of the diaphragm. At this frequency, the diaphragm's displacement amplitude is at its maximum, meaning the distance between the diaphragm and the rear electrode is minimum, resulting in the highest output voltage and sensitivity. This method is convenient and accurate for diaphragms exhibiting significant vibration, but it is difficult to measure some lightweight diaphragms with small diameters.

[0030] During testing, from left to right are the excitation end → sensing end → analysis end.

[0031] The sound source device 1 is placed coaxially with the diaphragm 5 under test, and the vertical distance between the sound-emitting end face of the sound source device 1 and the plane where the diaphragm 5 under test is located is fixed, forming the excitation end. The speaker emits sound waves that change continuously from low frequency to high frequency, applying acoustic excitation to the diaphragm under test. The diaphragm under test is placed coaxially with the rear electrode plate of the measuring microphone, with a fixed gap in the middle, forming the main body of the capacitor, which constitutes the sensing end. The vibration acquisition device and the calculation output device constitute the analysis end, which acquires the electrical signal output by the microphone, calculates and outputs the resonant frequency of the diaphragm.

[0032] Repeated measurement: For the same diaphragm under test, repeat the above steps N times (e.g., N=10 times) to obtain N fundamental frequency measurements: f 0,1 ,f 0,2 ,...,f 0,N To eliminate random errors, the average value of the measurement results is calculated: the arithmetic mean of these N fundamental frequency values ​​is taken to obtain the final characterization value of the diaphragm's fundamental frequency. The unit is Hz: (1) Where N represents the total number of times the same diaphragm under test is measured. In this embodiment, N=10, meaning that each diaphragm under test is measured 10 times.

[0033] i: The sequence number of the measurement, i = 1, 2, 3, ..., N. For example, i = 1 represents the 1st measurement, and i = 10 represents the 10th measurement.

[0034] f 0,i The fundamental frequency value obtained from the first measurement, in Hz. For example, f 0,1 f represents the fundamental frequency value obtained from the first measurement. 0,10 This represents the fundamental frequency value obtained from the 10th measurement.

[0035] : represents all f from i to N 0,i The values ​​are summed up.

[0036] Calculate the standard deviation: Calculate the standard deviation S of these N measurements to evaluate the stability and data quality of this test.

[0037] (2) Where S stands for Standard Deviation, measured in Hz. It quantifies the dispersion of N measurement results and is an important indicator for evaluating the stability and data quality of a testing system. The smaller the S value, the closer the multiple measurement results are to each other, the better the repeatability of the testing system, and the more stable and reliable the measurement results.

[0038] N: The total number of repeated measurements on the same diaphragm under test.

[0039] f 0,i The fundamental frequency value obtained from the first measurement.

[0040] : Average fundamental frequency.

[0041] The test results of the fundamental frequency of the test diaphragm are given separately. The diaphragm thickness is 6 μm and the material is a flexible polymer film (PET), mainly polyphenylene sulfide film or polyethylene terephthalate film. There are 5 test diaphragms in each group, and each measurement is performed 10 times. The mean (AVE) and standard deviation (STD) of the fundamental frequency are shown in Tables 1 to 6.

[0042] In engineering, experimental analysis is a common method to obtain the modal parameters of a microphone. This method is called Experimental Modal Analysis (EMA), also known as traditional modal analysis or classical modal analysis. It refers to a test and analysis method that uses an excitation device to excite the structure and measures the structural response at the same time. Figure 2 This is a modal experimental method for diaphragms. It uses a sound source as the excitation source, where the signal acts on the diaphragm to cause vibration. Sound signals are picked up using both acoustic and optical sensors, and the transfer function characteristics are analyzed to obtain the modal parameters of the diaphragm vibration.

[0043] When constructing the equivalent analysis model of the acoustic trigger, the lumped parameter model analytical method is selected as the electro-mechanical-acoustic analogy circuit diagram. The electro-mechanical-acoustic analogy circuit diagram method is applicable when the size of the acoustic element is much smaller than the wavelength of the sound wave. For example... Figure 3 As shown, it is an electro-mechanical-acoustic analog model of the microphone head of a photoacoustic microphone.

[0044] The effective sound pressure on the diaphragm (or the equivalent sound pressure of diaphragm vibration) is the sound pressure component that actually drives the diaphragm to vibrate after being divided by the acoustic path impedance. The sound pressure applied to the diaphragm of a photoacoustic microphone refers to the acoustic pressure exerted on the diaphragm. Acoustic elements consist of a diaphragm and an air gap cavity. The analog impedance of each acoustic element is expressed as the acoustic quality of the diaphragm. Radiated acoustic impedance Tone order and the acoustic compliance of the air gap cavity and thin-layer damping For ease of analysis, the circuit impedance is divided into three parts: , , ,in The effective sound pressure acting on the diaphragm is expressed as follows:

[0045] The transfer function of the attack can be expressed as:

[0046] Substituting equation (3) into equation (4), we can obtain the resonant frequency of the photoacoustic microphone's microphone head as follows:

[0047]

[0048] Table 1. Fundamental frequency (Hz) of a 14mm diameter diaphragm

[0049] Table 2. Fundamental frequency (Hz) of 16mm diameter embossed film

[0050] Table 3. Fundamental frequency (Hz) of a 16mm diameter diaphragm

[0051] Table 4. Fundamental frequency (Hz) of a 20mm diameter diaphragm without anterior cavity

[0052] Table 5. Fundamental frequency (Hz) of a 20mm diameter diaphragm with an anterior cavity

[0053] Table 6. Fundamental frequency (Hz) of the 34mm experimental diaphragm. According to Tables 1-6: Comparative analysis of measurement results for the same diaphragm revealed that the standard deviation of the fundamental frequency for a 34mm diameter diaphragm was less than 18Hz, while that for a 14mm diameter diaphragm was greater than 25Hz. The measurement results for the 14mm diameter diaphragm were more unstable, with greater uniformity in the fundamental frequency. This is related to the diaphragm diameter. The capacitive method for measuring the fundamental frequency of a diaphragm is easily affected by the external environment. Diaphragms with high fundamental frequencies show little displacement when resonating, making it more difficult to detect diaphragms with smaller diameters, such as those less than 9.7mm. Comparative analysis of measurement results for different diaphragms revealed significant differences in fundamental frequency across the five diaphragms, regardless of diameter (14mm or 34mm). This discrepancy was attributed to relatively poor consistency in controlling the standard tension T0 during each diaphragm stretching process, which affected the diaphragm's fundamental frequency. In actual production, the acceptable control range for the diaphragm's fundamental frequency is ±150Hz relative to the standard diaphragm frequency. Comparative analysis of the measurement results of two types of diaphragms with a diameter of 16mm revealed that the standard deviation of the fundamental frequency of the embossed diaphragm was less than 55Hz, while the standard deviation of the fundamental frequency of the ordinary diaphragm was mostly around 100Hz. The non-uniformity of the ordinary diaphragm was greater than that of the embossed diaphragm. This test result is consistent with the patent of Audio-Technica's embossed diaphragm. Comparing Tables 3.7, 3.8, and 3.9, it can be seen that the fundamental frequency of the 16mm diameter diaphragm is greater than that of the 14mm diameter diaphragm. This is because, when the diaphragm material and thickness remain unchanged, in addition to the diaphragm diameter affecting the fundamental frequency, the diaphragm tension also plays a role. In this case, the tension of the 14mm diameter diaphragm is less than that of the 16mm diameter diaphragm. Comparing Tables 3.10 and 3.11, it can be seen that when the microphone diaphragm diameter is 20mm and the diaphragm material, thickness, and tension remain unchanged, the presence or absence of a front cavity has a significant impact on the fundamental frequency. The fundamental frequency of the diaphragm without a front cavity is greater than that of the diaphragm with a front cavity.

[0054] This vibration measurement method is used to test and control the fundamental frequency of a microphone diaphragm, which reflects a comprehensive performance test index.

[0055] The implementation of this system method yields stable and reliable results: by performing multiple measurements on the same diaphragm and calculating the average value and standard deviation, random errors are effectively eliminated, ensuring the repeatability and reliability of the test results.

[0056] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0057] Although the present disclosure has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, such modifications or improvements made without departing from the spirit of the present disclosure are all within the scope of protection claimed by the present disclosure.

Claims

1. A microphone diaphragm conformity testing system, characterized in that, include A sound source device, controlled by control elements, is used to emit detection audio. The measuring microphone's rear electrode plate, combined with the diaphragm under test, forms a capacitor body, which is used to generate feedback from the resonant audio of the diaphragm under test. A vibration acquisition device, connected to a computing output device, is used to receive feedback audio from the capacitor body and transmit it to the computing output device in real time. The diaphragm to be tested is positioned opposite to the rear electrode plate of the measuring microphone, with a gap between them forming a capacitor body. The vibration acquisition device is positioned opposite to the capacitor body, and the sound source device is positioned opposite to both the capacitor body and the vibration acquisition device.

2. The microphone diaphragm consistency testing system according to claim 1, characterized in that, The vibration acquisition device is a condenser microphone, the sound source device is a coaxial speaker, and a perforated copper plate is provided on the rear electrode side of the measuring microphone, with the diaphragm to be tested placed inside the perforation.

3. The microphone diaphragm consistency testing system according to claim 2, characterized in that, The diaphragm under test includes a metal ring with uniform surface stress, and a flexible film is glued to the metal ring.

4. A method for testing the consistency of a microphone diaphragm, applied to a system as described in any one of claims 1-3, characterized in that, Includes the following steps Step 1: Establish a microphone diaphragm consistency testing system, set the relative positional relationships, and select various diaphragms to be tested according to the application field; Step 2: Control the sound source device to emit a frequency sweep signal, and calculate the average value of the test results based on the data collected by the vibration acquisition device; Step 3: Calculate the relationship between the output fundamental frequency results of the diaphragm under different conditions based on the average data of the output device. The different states of the diaphragm include the diameter and structure of the diaphragm.

5. The microphone diaphragm consistency test method according to claim 4, characterized in that, The selection of the diaphragm includes confirming the choice of different diameters and structures while keeping the material and thickness the same.

6. The microphone diaphragm consistency test method according to claim 5, characterized in that, The diaphragm is made of polyphenylene sulfide film or polyethylene terephthalate film, with a thickness of 6 μm.

7. The microphone diaphragm consistency test method according to claim 4, characterized in that, The analysis process of the computing output device is to use acoustic excitation mode to pick up sound signals through both acoustic sensors and optical sensors.

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