Piezoelectric driving double diaphragm receiver and frequency response characteristic adjusting method thereof

Abstract

The application provides a piezoelectric driving double diaphragm receiver and a frequency response characteristic adjusting method thereof, comprising: a shell comprising a shell cover plate and a shell cover body; and a first diaphragm assembly comprising an upper tensioning diaphragm ring and a first elastic diaphragm fixed on the upper tensioning diaphragm ring. The application realizes three sound wave composite sound emission by a single driving element, effectively solves the inherent problem of narrow frequency response range (mainly concentrated in the medium frequency band) of the piezoelectric body, significantly widens the working frequency response range of the receiver under the premise of maintaining the advantages of low power consumption, small size and no magnetic interference of the piezoelectric driving, and fills the inherent sharp resonance peak of the single vibration mode by superimposing and complementing the frequency response curves of the three sound waves, so that the overall frequency response characteristic is smoother and the sound quality is more natural. Since the magnetic steel driving component is not included, the driving power consumption is significantly lower than that of the same level of magnetic steel receiver, and the application has good industrial practicability and energy saving and environmental protection benefits.

Description

Technical Field

[0001] This invention relates to a piezoelectrically driven dual-diaphragm receiver and a method for adjusting its frequency response characteristics. Background Technology

[0002] A receiver is an electroacoustic transducer that converts electrical signals into sound signals, widely used in hearing aids, headphones, communication equipment, and other fields. Traditional receivers mostly use electromagnetic drive, and their structure includes a permanent magnet (such as neodymium iron boron or ferrite), a voice coil, and a diaphragm. When an audio current passes through the voice coil, the voice coil experiences a force in the magnetic field, causing the diaphragm to vibrate and produce sound. However, this type of electromagnetic receiver has the following problems: First, the magnet and voice coil are relatively large, making further miniaturization difficult; second, the voice coil has resistive losses, resulting in high power consumption; third, its frequency response characteristics are inherently limited by the magnetic circuit and the vibration system, performing poorly in the high-frequency range.

[0003] In recent years, piezoelectric receivers have attracted attention due to their advantages such as simple structure, low power consumption, and ease of miniaturization. A piezoelectric element, driven by an audio voltage signal, exhibits the inverse piezoelectric effect, that is, it generates stretching and contracting vibrations along the electrode surface, thus directly producing sound. However, existing piezoelectric receivers mainly suffer from the following technical drawbacks: 1) Limited frequency response range. The vibration frequency response of the piezoelectric element itself is mainly concentrated in the mid-frequency range (approximately 500Hz to 5kHz), with significant attenuation of sound pressure levels in the low-frequency range (<200Hz) and high-frequency range (>10kHz), resulting in an overall unfulfilled sound quality in the receiver, insufficient low-frequency power, and a lack of high-frequency detail; 2) Unsmooth frequency response characteristics. A single piezoelectric element or a single diaphragm vibration system will exhibit a sharp resonance peak at its inherent resonant frequency, while the response in other frequency ranges will be insufficient, resulting in large fluctuations in the frequency response curve, sound distortion, and an unnatural listening experience; 3) Difficulty in achieving a wide-bandwidth response with a single vibration mode. In existing technologies, whether relying solely on piezoelectric element vibration or using a piezoelectric element to drive a single diaphragm, the sound production mode is singular, and the frequency response characteristics are determined by a single vibration system, making it difficult to achieve a flat response over a wide frequency band.

[0004] To address the aforementioned issues, existing technologies have proposed receivers with dual-diaphragm structures, such as those using two electromagnetic actuators to drive two diaphragms separately. However, these methods are complex, costly, and consume significant power. Other approaches have attempted to use piezoelectric elements to drive a single diaphragm, but the frequency response is still determined by the vibration of a single diaphragm, resulting in limited improvement at low and high frequencies. Furthermore, existing technologies lack effective methods for independently tuning the resonant frequencies of the dual diaphragms to broaden the frequency response range and smooth its characteristics.

[0005] Therefore, how to expand the frequency response range and smooth the frequency response characteristics of the receiver while maintaining the advantages of low power consumption and small size of piezoelectric drive is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] This invention provides a piezoelectrically driven dual-diaphragm receiver and a method for adjusting its frequency response characteristics, which can effectively solve the above-mentioned problems.

[0007] This invention is implemented as follows: A piezoelectrically driven dual-diaphragm receiver, comprising: The housing includes a housing cover plate and a housing body; The first diaphragm assembly includes an upper diaphragm ring and a first elastic diaphragm fixed on the upper diaphragm ring; The second diaphragm assembly includes a lower diaphragm ring and a second elastic diaphragm fixed on the lower diaphragm ring. The first diaphragm assembly and the second diaphragm assembly are disposed opposite to each other inside the housing. A piezoelectric element is disposed between the first diaphragm assembly and the second diaphragm assembly, and is drivenly connected to the first elastic diaphragm and the second elastic diaphragm respectively. The piezoelectric element is used to generate stretching vibration under the drive of an audio voltage signal. This stretching vibration directly generates a first sound wave and simultaneously drives the first elastic diaphragm and the second elastic diaphragm to generate membrane vibration, thereby generating a second sound wave and a third sound wave, respectively. Furthermore, the overall frequency response characteristics of the receiver are synthesized by the first sound wave, the second sound wave, and the third sound wave.

[0008] A piezoelectrically driven dual-diaphragm receiver and its frequency response characteristic adjustment method include the following steps; S1. Adjust the tension of the first elastic diaphragm to give it a first resonant frequency; S2. Adjust the tension of the second elastic diaphragm to give it a second resonant frequency that is different from the first resonant frequency; S3. The first diaphragm assembly and the second diaphragm assembly are arranged opposite to each other, and the piezoelectric element is driven to the first elastic diaphragm and the second elastic diaphragm, so that the overall frequency response characteristics of the receiver are synthesized by the direct vibration of the piezoelectric element, the vibration of the first elastic diaphragm and the vibration of the second elastic diaphragm.

[0009] The beneficial effects of this invention are: (1) This invention connects a single piezoelectric element to two opposing elastic diaphragms simultaneously, utilizing the piezoelectric element to generate direct stretching vibration (first sound wave) and forced vibration of the double diaphragms (second and third sound waves) under the drive of an audio voltage signal. This allows the overall frequency response of the receiver to be synthesized from the three sound waves. Compared to the traditional piezoelectric receivers that rely solely on the vibration of the piezoelectric element itself or the single diaphragm vibration, this invention achieves three-wave composite sound generation with a single driving element. This effectively solves the inherent problem of the narrow frequency response range of the piezoelectric element (mainly concentrated in the mid-frequency band). While maintaining the advantages of low power consumption, small size, and no magnetic interference of piezoelectric drive, it significantly broadens the working frequency response range of the receiver. Furthermore, by superimposing and complementing the frequency response curves of the three sound waves, the inherent sharp resonance peaks of the single vibration mode are filled in, making the overall frequency response characteristics smoother and the sound quality fuller and more natural. At the same time, since it does not contain a magnet driving component, its driving power consumption is significantly lower than that of a magnet-type receiver of the same level, which has good industrial practicality and energy-saving and environmental protection benefits. Attached Figure Description

[0010] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0011] Figure 1 This is a cross-sectional view of the piezoelectrically driven dual-diaphragm receiver of the present invention.

[0012] Figure 2 This is a schematic diagram of the system for measuring the resonant frequency of a diaphragm using the resonant cavity method of the present invention.

[0013] Figure 3 This is a composite curve of the frequency response characteristics of this invention.

[0014] Figure 4 This is a separate frequency response curve of the diaphragm in this invention.

[0015] Figure 5 This is a separate frequency response curve of the diaphragm under this invention.

[0016] Figure 6 This is a schematic diagram of the complementary superposition of the frequency response of the dual diaphragms in this invention.

[0017] Figure 7 This is a frequency response comparison chart between the present invention and existing technologies. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention.

[0019] In the description of this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0020] Reference Figure 1-7 As shown, a piezoelectrically driven dual-diaphragm receiver includes... The housing includes a housing cover plate 10 and a housing cover body 20; a first diaphragm assembly includes an upper diaphragm ring 30 and a first elastic diaphragm fixed on the upper diaphragm ring 30; the electrodes of the piezoelectric element 100 are led out to the outside of the housing through a first electrode lead-out washer 60 and a second electrode lead-out washer 80 to ensure the reliability of the electrical connection; the housing cover plate 10 is provided with a fixing hole 70, and the housing cover plate 10 and the housing cover body 20 are fixedly connected through a connecting screw hole 90.

[0021] The outer casing 10 is typically located on the top or front of the receiver, used to close the upper part of the casing and protect the internal components; the outer casing 20 constitutes the main body of the casing, forming a container with an internal cavity. After the outer casing 10 and the outer casing 20 are interlocked, a basically closed acoustic cavity is formed inside, providing a stable acoustic environment for the normal operation of the internal vibration system.

[0022] Furthermore, the mounting holes 70 on the outer casing 10 are typically through holes, allowing the receiver to be securely fixed to the external device housing using screws, rivets, or other fasteners, preventing loosening or detachment due to vibration or impact during use. Simultaneously, to achieve reliable encapsulation and detachable connection between the outer casing 10 and the outer casing 20, they are fixedly connected via connecting screw holes 90. Specifically, threaded holes or smooth holes can be provided at corresponding positions on the outer casing 10 and the outer casing 20, allowing them to be fastened together using self-tapping screws or machine screws. This split-type housing structure with screw fixing offers significant advantages over traditional snap-fit ​​or ultrasonic welding methods, including reliable assembly, ease of disassembly and maintenance, and convenient adjustment of internal component positions.

[0023] In addition, to electrically connect the internal piezoelectric element 100 to the external audio signal source, a first electrode lead-out washer 60 and a second electrode lead-out washer 80 are provided on the housing. These two lead-out washers are typically made of conductive metal (such as copper, gold-plated copper, or stainless steel) and are fixed to the housing wall by compression fitting and sealing adhesive, or embedded in the housing material by integral injection molding. The inner end of the lead-out washer forms an electrical connection with the electrode of the piezoelectric element 100 inside the housing, while the outer end protrudes from the housing surface as a terminal. The electrode of the piezoelectric element 100 is led out to the outside of the housing through the first electrode lead-out washer 60 and the second electrode lead-out washer 80, thereby ensuring the long-term reliability of the electrical connection and preventing connection failure due to vibration, temperature changes, or humid environments. This structural design of the present invention ensures reliable installation of the receiver as a whole with external devices, reliable encapsulation of the housing itself, and stable electrical connection between the internal piezoelectric element and the external circuitry, providing a structural foundation for the industrial production and long-term use of the receiver.

[0024] Furthermore, the first diaphragm assembly in this case is not simply the diaphragm itself, but a composite structure. The upper diaphragm ring 30 is typically made of a rigid metal or plastic material, and its shape is ring-shaped or frame-shaped, used to support and fix the edge of the first elastic diaphragm. The first elastic diaphragm is a thin film material with elasticity (such as polyester film, polyimide film, polyetheretherketone film, or metal film), and its edge is fixed to the upper diaphragm ring 30 by adhesive, hot pressing, or mechanical clamping. This method of fixing the elastic diaphragm with a diaphragm ring is fundamentally different from the traditional method of using a piezoelectric element directly as the diaphragm or simply pasting the diaphragm. The core advantage of using the upper diaphragm ring 30 to fix the first elastic diaphragm is that the diaphragm ring can independently apply and maintain a precise and controllable initial tension on the diaphragm, and this tension remains stable throughout the entire service life of the receiver. The tension of the diaphragm is a key parameter that determines its vibration characteristics (especially its natural resonant frequency). The independent control of the tension through the diaphragm ring provides structural protection for subsequent adjustment of the diaphragm's resonant frequency. Meanwhile, the upper diaphragm ring 30 also serves as a mechanical interface for mounting the first diaphragm assembly onto other support structures inside the housing.

[0025] The second diaphragm assembly includes a lower diaphragm ring 50 and a second elastic diaphragm fixed on the lower diaphragm ring 50. The first diaphragm assembly and the second diaphragm assembly are disposed opposite each other in the housing.

[0026] Specifically, the second diaphragm assembly is also a composite structure. The lower diaphragm ring 50 is similar in material, shape, and function to the upper diaphragm ring 30, serving to support and fix the edge of the second elastic diaphragm and provide it with independently adjustable initial tension. The first and second elastic diaphragms can be made of the same material, or different materials can be used depending on their required resonant frequencies (for example, a softer material can be used for a diaphragm requiring a low-frequency response, while a harder material can be used for a diaphragm requiring a high-frequency response). In the assembled state, the first and second diaphragm assemblies are arranged opposite each other within the housing. "Relative arrangement" means that the two diaphragm assemblies are arranged vertically parallel in space, with the first and second elastic diaphragms facing each other and forming an air gap of a certain thickness between them. This relatively arranged dual-diaphragm layout is the basic structure for frequency response synthesis in this invention. When the two diaphragms vibrate under the drive of the piezoelectric element, they radiate sound waves to the front and rear of the housing, respectively, or simultaneously to the same side of the housing (depending on the acoustic path design), thereby achieving the superposition effect of two sound sources.

[0027] A porous insulating gasket 40 is provided between the first diaphragm assembly and the second diaphragm assembly; the outer shell is also provided with a first electrode lead-out washer 60 and a second electrode lead-out washer 80 for fixing and electrical connection.

[0028] Specifically, the thickness of the insulating gasket 40 determines the spacing of the air gap between the first and second elastic diaphragms, typically ranging from 0.1 mm to 2 mm. The choice of material for the insulating gasket 40 is a crucial technical consideration: it must possess both insulation and porosity. Regarding insulation, the gasket material should be an electrical insulator (such as foam plastic, porous rubber, non-woven fabric, sponge, microporous ceramic, or polytetrafluoroethylene porous membrane), its function being to electrically isolate the upper diaphragm ring 30 and the lower diaphragm ring 50 from each other. This is because the metal plating (if any) on the two diaphragm assemblies or the diaphragm rings themselves may carry different potentials. Direct contact or connection through a conductive medium could lead to a short circuit, damaging the piezoelectric element or external drive circuit. Regarding porosity, the gasket material contains numerous interconnected micropores that allow air to flow freely in the air gap between the upper and lower diaphragms. Without these pores, the air gap between the upper and lower diaphragms would be a completely closed space. When the diaphragm vibrates, the internal air is repeatedly compressed and stretched, generating additional aeroelastic force. This "air cushion effect" significantly increases the equivalent stiffness and equivalent mass of the vibration system, leading to a reduction in diaphragm amplitude, decreased sound production efficiency, worse transient response, and even nonlinear distortion at large amplitudes. Furthermore, as mentioned earlier, the lead-out gasket, besides leading out the electrodes of the piezoelectric element 100, also serves to fix the position of internal components. This design of the present invention simultaneously achieves electrical isolation between the two diaphragms, airflow regulation, and reliable signal extraction, making it one of the key structures ensuring the normal operation of the receiver.

[0029] In one embodiment, the porosity ε of the porous insulating gasket 40 is preferably 30% to 70%, the thickness d is preferably 0.1 mm to 0.5 mm, and the ratio of its acoustic impedance Zs to the characteristic impedance ρc of air satisfies:

[0030] Where ρ is air density, c is sound speed, ω is angular frequency, and j is the imaginary unit. Experiments conducted by the inventors have verified that when ε=50% and d=0.2mm, the average acoustic impedance of this insulating gasket in the frequency range of 200Hz to 8kHz is reduced by approximately 60% compared to the non-porous gasket, while maintaining electrical insulation performance above 10¹²Ω.

[0031] A piezoelectric element 100 is disposed between the first diaphragm assembly and the second diaphragm assembly, and is drivenly connected to the first elastic diaphragm and the second elastic diaphragm respectively. The first elastic diaphragm has a first resonant frequency, and the second elastic diaphragm has a second resonant frequency different from the first resonant frequency, so that the effective operating frequency bands of the first diaphragm assembly and the second diaphragm assembly are staggered and complementary to each other, thereby widening the overall frequency response range of the receiver and smoothing its frequency response characteristics. The first resonant frequency and the second resonant frequency are set by adjusting the tension of the first elastic diaphragm and / or the second elastic diaphragm.

[0032] The piezoelectric element (100) is typically made of a ceramic material with excellent piezoelectric properties (such as lead zirconate titanate piezoelectric ceramic PZT). Its shape can be circular, square, or rectangular, and its thickness is typically 0.1 mm to 1 mm. Metal electrode layers (e.g., silver or nickel electrodes formed by screen printing and high-temperature sintering) are disposed on two opposing main surfaces of the piezoelectric element 100. During assembly, the two main surfaces of the piezoelectric element 100 form a driving connection with the first and second elastic diaphragms, respectively. The term "driving connection" refers to the piezoelectric element 100 being in contact with or fixed to the two elastic diaphragms in a manner that effectively transmits mechanical vibration. This connection can be achieved in several ways: for example, a thin layer of conductive adhesive (such as silver paste or carbon paste) can be coated between the two surfaces of the piezoelectric element 100 and the two elastic diaphragms, forming an electrical connection while bonding and fixing; alternatively, a non-conductive structural adhesive can be used for bonding, with the electrodes led out separately; or an elastic contact method can be used, allowing the surface of the piezoelectric element 100 to maintain mechanical contact with the diaphragms without fixing them. Regardless of the specific method used, the core requirement is that the expansion and contraction vibration of the piezoelectric element 100 can be effectively transmitted to the two elastic diaphragms, driving them to generate membrane vibration. This invention uses a single piezoelectric element 100 to simultaneously drive the first and second elastic diaphragms, which is fundamentally different from the traditional approach where one driver drives only one diaphragm. It achieves the effect of generating dual-diaphragm vibration with a single driving element, creating conditions for subsequent frequency response synthesis while maintaining a compact structure and low power consumption.

[0033] In one embodiment, in order to ensure that the stretching vibration of the piezoelectric body 100 can be transmitted to the two elastic diaphragms efficiently and faithfully, the drive connection should meet the following conditions: the thickness of the connection layer should be controlled between 0.01 mm and 0.1 mm, and the elastic modulus of the connection layer should be between that of the piezoelectric material and the diaphragm material, so as to avoid significant vibration reflection or energy loss. In one specific embodiment of the present invention, an epoxy resin-based conductive adhesive is used for bonding. The thickness of the conductive adhesive layer is controlled between 0.02 mm and 0.05 mm, and the curing condition is heating at 80°C for 30 minutes. The Young's modulus of the conductive adhesive after curing is approximately 2 GPa, which is between that of PZT piezoelectric ceramics (approximately 70 GPa) and polyester diaphragms (approximately 3 GPa), enabling good mechanical impedance matching and achieving a vibration energy transfer efficiency of over 90%. In another specific embodiment, the piezoelectric body 100 and the two elastic diaphragms are connected by a non-contact driving method. That is, a small gap (e.g., 0.01 mm to 0.05 mm) is maintained between the surface of the piezoelectric body 100 and the diaphragms. The diaphragms are driven to vibrate through near-field acoustic pressure coupling. This non-contact method can eliminate the additional damping introduced by the adhesive layer, but requires precise control of the gap size. In the preferred embodiment of the present invention, conductive adhesive bonding is used because it has a simple structure, mature technology, high reliability, and can simultaneously achieve mechanical drive and electrical connection.

[0034] Furthermore, diaphragm tension refers to the tensile stress experienced by the diaphragm within its plane, measured in Newtons per meter (N / m). According to thin-film vibration theory, for a circular elastic diaphragm fixed at all four sides, the relationship between its fundamental resonant frequency and tension is given by the formula f = (2.405 / 2πR)·√(T / m), where f is the resonant frequency (Hz), R is the diaphragm radius (m), T is the tension (N / m), and m is the areal density of the diaphragm (kg / m²). This formula clearly shows that the resonant frequency f is directly proportional to the square root of the tension T. That is, the greater the tension, the tighter the diaphragm, and the higher the resonant frequency; the smaller the tension, the looser the diaphragm, and the lower the resonant frequency. Therefore, by adjusting the tension of the diaphragm ring on the elastic diaphragm—specifically, a dedicated diaphragm tensioning device can be used to apply and adjust the tension—the inherent resonant frequency of the diaphragm can be precisely controlled. For example, if the first elastic diaphragm needs to be set to low-frequency resonance (e.g., 150Hz), its tension is adjusted to be smaller; if the second elastic diaphragm needs to be set to mid-to-high frequency resonance (e.g., 2kHz), its tension is adjusted to be larger. The tension of the two diaphragms can be adjusted independently without interference, thus allowing for the free selection of the target resonant frequency for each diaphragm. This invention establishes a complete technical chain of "adjusting tension → changing resonant frequency → setting operating frequency band," enabling the frequency response characteristics of the dual diaphragms to be customized according to product requirements. For example, the target frequency response curves for different brands of hearing aids and the sound quality style requirements for different headphone products can all be achieved by adjusting the tension.

[0035] In a preferred embodiment of the present invention, the tensions of the first elastic diaphragm and the second elastic diaphragm are determined according to the following formula: f = (k / 2πR)·√(T / m), where f is the target resonant frequency, R is the diaphragm radius, m is the diaphragm surface density, and k is the diaphragm shape factor (k = 2.405 for circular diaphragms, k = π for square diaphragms, and k = π·√(1+(a / b)²)) for rectangular diaphragms). The tension T1 of the first elastic diaphragm and the tension T2 of the second elastic diaphragm satisfy: T2 / T1 ≥ 9, to ensure that the two resonant frequencies differ by more than three times, thereby achieving a significant widening of the frequency response range (at least extending by two octaves). Experiments conducted by the inventors have verified that when T2 / T1 = 9, f2 / f1 = 3; when T2 / T1 = 25, f2 / f1 = 5; and when T2 / T1 = 100, f2 / f1 = 10. Preferably, the value range of T2 / T1 is 9–100, and the corresponding value range of f2 / f1 is 3–10.

[0036] The piezoelectric element 100 is used to generate stretching vibration under the drive of an audio voltage signal. This stretching vibration directly generates a first sound wave and simultaneously drives a first elastic diaphragm and a second elastic diaphragm to generate membrane vibration, thereby generating a second sound wave and a third sound wave, respectively. Furthermore, the overall frequency response characteristics of the receiver are synthesized by the first sound wave, the second sound wave, and the third sound wave.

[0037] Specifically, when an external audio signal source (such as the amplifier output of a hearing aid) applies an AC audio voltage to the two electrodes of the piezoelectric body 100, the piezoelectric body 100 deforms using the inverse piezoelectric effect. The characteristics of the inverse piezoelectric effect are: under the influence of an electric field, the piezoelectric body undergoes mechanical deformation along or perpendicular to the direction of the electric field, and the magnitude of the deformation is proportional to the electric field strength. The direction of the deformation changes with the polarity of the electric field. When an AC audio voltage is applied, the piezoelectric body alternately stretches and shortens with the voltage change, generating stretching and contracting vibrations. This stretching and contracting vibration itself directly radiates sound waves into the surrounding air, generating the first sound wave. Simultaneously, the stretching and contracting vibration of the piezoelectric body 100 also drives the first and second elastic diaphragms through the aforementioned driving connection (adhesion or contact), causing these two diaphragms to undergo forced diaphragm vibration. Forced diaphragm vibration refers to the vibration of the diaphragm under the action of an external driving force, with its vibration frequency matching the frequency of the driving force (i.e., the frequency of the audio voltage signal in this case). The vibration of the first elastic diaphragm generates a second sound wave, and the vibration of the second elastic diaphragm generates a third sound wave. Thus, the entire receiver radiates sound waves simultaneously from three sources: the piezoelectric element itself, the first elastic diaphragm, and the second elastic diaphragm. The overall frequency response characteristics of the receiver are not determined by any single sound source, but are synthesized from the first, second, and third sound waves. This "three-wave synthesis" composite sound generation mode is one of the core technical principles of this invention. In the frequency domain, the frequency response of the first sound wave is mainly characterized by a peak in the mid-frequency range (an inherent characteristic of piezoelectric materials). The frequency response of the second sound wave forms a resonance peak (e.g., a low-frequency peak) centered on the first resonant frequency, and the frequency response of the third sound wave forms another resonance peak (e.g., a mid-to-high frequency peak) centered on the second resonant frequency. When these three sound waves are superimposed in the air and / or within the acoustic cavity of the casing, their frequency response curves complement and flatten each other, resulting in an overall frequency response curve that has both a wide bandwidth and a flat shape. Thus, by using a "single piezoelectric material driving dual diaphragms" structure, the frequency response synthesis of three sound waves is achieved with the fewest possible driving components. While maintaining low power consumption and small size, this solves the technical defects of traditional piezoelectric receivers, such as narrow frequency response range and uneven curves.

[0038] The receiver also includes a structure for reducing the air acoustic resistance between the first elastic diaphragm and the second elastic diaphragm; the structure consists of several through holes provided on the first elastic diaphragm and / or the second elastic diaphragm, and / or several vent holes provided on the housing corresponding to the air gap region between the two diaphragms.

[0039] Since the first and second elastic diaphragms are positioned opposite each other inside the housing, there is an air gap with a finite thickness between them (typically determined by the thickness of the porous insulating gasket 40). When the two diaphragms move towards or away from each other under the drive of the piezoelectric element 100 (i.e., one moves upward and the other downward, or both move in the same direction but at different speeds), the air in this air gap is compressed or stretched, thus generating air resistance. If the air gap is completely closed (i.e., the insulating gasket 40 is not breathable and there are no openings on the housing), air cannot freely enter or exit, and the diaphragms need to overcome additional air elastic forces during movement. This leads to a series of adverse consequences: increased equivalent stiffness and equivalent mass of the vibration system, reduced diaphragm amplitude, decreased sound production efficiency, worsened transient response, and potential nonlinear distortion at large amplitudes. Therefore, this invention provides a structure for reducing the air resistance between the first and second elastic diaphragms: The structure can be implemented using one of the following three methods or a combination thereof: The first method involves setting several through holes on the first and / or second elastic diaphragms. These through holes can be formed by laser drilling or mechanical punching, with a diameter typically between 0.05mm and 1mm. The total area of ​​the through holes is generally controlled to be 1% to 5% of the total diaphragm area. These through holes allow air to circulate freely between the upper and lower diaphragms, thereby balancing the air pressure on both sides and eliminating the "air cushion effect." The second method involves setting several vent holes on the wall of the outer shell corresponding to the air gap area between the two diaphragms. For example, several tiny vent holes can be opened on the side wall of the outer shell 20 to connect the closed air gap with the outside atmosphere. When the diaphragm moves, air can enter and exit the air gap through these vent holes, similarly eliminating the air cushion effect. The third method combines the above two methods, i.e., drilling holes on the diaphragm and opening vent holes on the outer shell.

[0040] It is important to note that the size, number, and distribution of the through holes and vent holes require careful design: if the holes are too small or too few, the reduction in acoustic impedance will be insignificant; if the holes are too large or too many, it may affect the mechanical strength and resonant characteristics of the diaphragm itself, or lead to excessive low-frequency sound wave leakage, thus reducing the low-frequency response. This invention, by setting through holes and / or vent holes, effectively reduces the air acoustic impedance between the two diaphragms, improves the sensitivity and transient response of the vibration system, and enhances linearity at large amplitudes. It is an important auxiliary structure to ensure that the two diaphragms can vibrate freely and achieve the expected acoustic performance.

[0041] Alternatively, when using a diaphragm through-hole design, the number of through-holes N is determined by the following formula based on the diaphragm area S and the area of ​​a single through-hole A: N = (S×α) / A, where α is the proportion of the total area of ​​the through-holes to the total area of ​​the diaphragm, and the value of α ranges from 1% to 5%. The diameter of a single through-hole is preferably 0.1mm to 0.5mm. The through-holes should be evenly distributed on the diaphragm surface, avoiding concentration at the center or edge of the diaphragm to prevent local stress concentration that could lead to diaphragm breakage. When using a housing vent design, the number and total cross-sectional area of ​​the vents should ensure that the time constant τ of the air pressure change in the air gap is less than 1 / 10 of the sound wave period. Specifically, the relationship between the total cross-sectional area S_hole of the vents and the air gap volume V_gap satisfies: S_hole ≥ (V_gap × 2πf_min) / (c × 0.1), where f_min is the minimum operating frequency of the receiver (e.g., 100Hz), and c is the speed of sound (approximately 340m / s). According to this relationship, for a receiver with a typical air gap volume of 50 mm³, the total cross-sectional area of ​​the vent should be no less than about 0.09 mm², that is, at least one circular hole with a diameter of 0.34 mm.

[0042] In one specific embodiment of the present invention, the diaphragm has a diameter of 8 mm and an area of ​​50.3 mm². Twelve through holes with a diameter of 0.2 mm are uniformly opened on its surface, with a total area of ​​approximately 0.38 mm², accounting for 0.75% of the total diaphragm area. Tests have shown that this configuration effectively reduces air resistance without having a noticeable impact on the mechanical strength and resonant frequency of the diaphragm.

[0043] The piezoelectric driven dual-diaphragm receiver does not contain a magnet drive component, and its drive power consumption is lower than that of a magnet-type receiver of the same level.

[0044] Specifically, piezoelectrically driven dual-diaphragm receivers do not include a magnet drive component. Traditional receivers typically use electromagnetic drive, with core components including a permanent magnet (such as a neodymium iron boron magnet or a ferrite magnet) and a voice coil. The permanent magnet provides a constant magnetic field, and the voice coil is a coil suspended in the magnetic field. When an audio current passes through the voice coil, the current-carrying voice coil moves under the influence of the Lorentz force in the magnetic field, causing the diaphragm to vibrate and produce sound. This electromagnetic drive method has inherent drawbacks: the magnet and voice coil are relatively large and heavy; the voice coil has DC resistance, which generates Joule heat loss; the magnetic circuit system suffers from hysteresis loss and eddy current loss; and the permanent magnet may demagnetize in a strong magnetic field environment. In contrast, the present invention uses a piezoelectric element 100 as the sole driving element for the magnet and voice coil. The piezoelectric element is essentially a capacitive device; under AC voltage drive, its active power consumption is mainly determined by the dielectric loss tangent (tanδ), typically only 0.01–0.02, far lower than the resistive loss of the voice coil (the efficiency of the voice coil is usually between a few percent and tens of percent). Therefore, the piezoelectrically driven dual-diaphragm receiver of the present invention has lower driving power consumption than a magnet-type receiver of the same level (i.e., capable of producing the same maximum output sound pressure level).

[0045] Specifically, under the same input voltage, the power consumption of a piezoelectric driven receiver is typically only 20% to 50% of that of an electromagnetically driven receiver. This has significant practical implications for applications that are extremely sensitive to power consumption, such as hearing aids, true wireless stereo headphones, and implantable medical devices. Lower power consumption means longer battery life or allows for the use of smaller capacity batteries, thus enabling device miniaturization. At the same time, since it does not contain magnets, the receiver of this invention is not affected by strong external magnetic field environments (e.g., it will not experience performance degradation or failure when used near MRI equipment) and will not interfere with other magnetically sensitive devices (such as magnetic compasses, magnetic stripe cards, etc.), thus exhibiting better electromagnetic compatibility.

[0046] In Example 2, in order to objectively compare the power consumption of the piezoelectrically driven dual-diaphragm receiver of the present invention with that of a conventional magnet receiver, the following test method was used: 1) Select two receiver samples: Sample A is the piezoelectric driven dual-diaphragm receiver prepared in the embodiment of the present invention, and Sample B is a commercially available balanced armature (magnetic) receiver of the same size. Both can produce the same maximum output sound pressure level (e.g., 110dB SPL) at a frequency of 1kHz. 2) Under the same input voltage (e.g., 1Vrms) and the same load conditions, measure the active power drawn by the two receivers from the drive circuit respectively; 3) Test results show that at an input of 1kHz and 1Vrms, the active power of sample A (the present invention) is 2.5mW, and the active power of sample B (magnetic type) is 8.2mW. The power consumption of the present invention is approximately 30.5% of that of the magnetic type. In the comparison of average power consumption across the entire frequency band (200Hz to 8kHz), the power consumption of the present invention is approximately 25% to 45% of that of the magnetic type.

[0047] To further demonstrate the test methods and data for comparing the power consumption of non-magnetic steel drives, please refer to the table below:

[0048] It should be noted that the above comparative data were obtained under specific test conditions. The specific power consumption ratio may vary depending on the specific design parameters of the receiver, the test frequency, the test environment, and other factors. However, the present invention has lower drive power consumption than magnet receivers of the same level. This technical effect is clear and repeatable under the same test conditions.

[0049] A piezoelectrically driven dual-diaphragm receiver and its frequency response characteristic adjustment method include the following steps; S1. Adjust the tension of the first elastic diaphragm to give it a first resonant frequency; S2. Adjust the tension of the second elastic diaphragm so that it has a second resonant frequency different from the first resonant frequency; S3. The first diaphragm assembly and the second diaphragm assembly are positioned opposite each other, and the piezoelectric element 100 is driven to connect to the first elastic diaphragm and the second elastic diaphragm, so that the overall frequency response characteristics of the receiver are synthesized by the direct vibration of the piezoelectric element 100, the vibration of the first elastic diaphragm, and the vibration of the second elastic diaphragm.

[0050] In step S1, the first elastic diaphragm, along with its upper tension ring 30, is placed on a dedicated tension adjustment device. This device applies a controllable tensile force to the diaphragm and maintains a stable applied tension. The tensile stress on the diaphragm is gradually increased or decreased mechanically (e.g., by rotating the adjusting screw or adjusting the locking force of the clamping ring), while the current resonant frequency is monitored in real time using a resonant frequency measuring device (e.g., the resonant cavity method described below) until the frequency reaches a preset target value (e.g., 150Hz). If the diaphragm is required to compensate for low frequencies, the target resonant frequency is set to a lower value (e.g., 100Hz to 300Hz); if it is required to compensate for mid-to-high frequencies, it is set to a higher value (e.g., 1.5kHz to 3kHz). After the tension is adjusted to the correct position, the upper tension ring (30) is locked in place by a locking mechanism, keeping the tension of the diaphragm stable. Thus, the first resonant frequency of the first elastic diaphragm is precisely set.

[0051] In step S2, the operating principle is exactly the same as in S1, but the target frequency setting must be different from the first resonant frequency. Typically, to ensure the frequency response ranges of the two diaphragms are staggered and complementary, the resonant frequency of one diaphragm can be set in the low-frequency range, and the resonant frequency of the other diaphragm in the mid-to-high-frequency range. The ratio between the two resonant frequencies is usually recommended to be more than three times (e.g., 150Hz and 2kHz, a ratio of approximately 13 times), to ensure that the resonance peaks are sufficiently separated on the frequency axis, avoiding mutual interference, while also forming a smooth transition region. The second resonant frequency is set by independently adjusting and locking the tension of the second elastic diaphragm using the lower tension ring 50.

[0052] It should be noted that the "tension adjustment" operation described in steps S1 and S2 above relies on the upper diaphragm ring 30 and the lower diaphragm ring 50 in the device of the present invention. In traditional receivers, the diaphragm is either directly glued to the outer shell (tension cannot be adjusted) or integrally formed with the piezoelectric element (tension is fixed), making independent tension adjustment impossible. The present invention, by setting an independent diaphragm ring structure, allows the diaphragm to be pre-fixed to the diaphragm ring before assembly, and the diaphragm tension can be precisely set by mechanically adjusting the diaphragm ring (e.g., changing the tightness of the diaphragm ring) or replacing it with a diaphragm ring of different specifications. Therefore, the frequency response characteristic adjustment method and the device structure of the present invention are interdependent and inseparable: the device provides an operable structural basis for the method, while the method provides technological assurance for the device to achieve optimal performance.

[0053] It should be noted that the method provided by this invention makes the frequency response characteristics of the receiver no longer fixed and unadjustable, but can be flexibly customized by changing the tension of the two diaphragms, thereby adapting to the needs of different application scenarios.

[0054] Example 1: To achieve the operation of "adjusting the diaphragm to the target resonant frequency" in the aforementioned frequency response adjustment method, a fundamental technical problem needs to be solved first: how to accurately measure the correspondence between the diaphragm tension and its resonant frequency? Because diaphragm tension is a mechanical parameter, it is difficult to measure directly on the production line; while the resonant frequency is an acoustic parameter, it is relatively easy to measure. Therefore, this invention proposes to use the resonant cavity method to solve this problem. The complete implementation process of this method is as follows: The relationship between the tension and resonant frequency of a first or second elastic diaphragm is measured and calibrated using a resonant cavity method: The diaphragm to be tested is placed in a resonant cavity, excited by a continuously variable frequency sound pressure generator, and its resonant frequency is measured using a laser or microphone. The tension value is then determined according to a preset formula relating the diaphragm resonant frequency and tension. Specifically, the steps include: A1. Install the diaphragm to be tested (which can be the first elastic diaphragm or the second elastic diaphragm, together with its fixed diaphragm ring) onto the opening of a resonant cavity with standard acoustic characteristics. The resonant cavity is a closed cavity with a known volume, smooth inner walls, and defined acoustic boundary conditions (usually cylindrical or cubic, with a volume between a few cubic centimeters and a few liters, depending on the size of the diaphragm). A2. Use a sound pressure generator with continuously variable frequency (e.g., a high-fidelity loudspeaker driven by a function signal generator) to apply a sweep frequency sound pressure excitation to the diaphragm under test in the resonant cavity. The sweep frequency range should cover the possible target resonant frequencies of the diaphragm under test (e.g., from 20Hz to 20kHz), and the sweep frequency speed should be slow enough (e.g., one logarithmic cycle per minute) to ensure that the diaphragm can achieve steady-state vibration at each frequency point. A3. During the frequency sweep process, the actual resonant frequency of the diaphragm is determined by using a laser vibrometer (non-contact optical vibration measurement, which directly measures the vibration velocity or displacement of the diaphragm surface) or a microphone (which measures the sound pressure change inside the resonant cavity). When the excitation frequency matches the natural frequency of the diaphragm, the amplitude of the diaphragm will reach its maximum value (represented as a peak value in the laser vibrometer signal), and the sound pressure inside the resonant cavity will also reach an extreme value (represented as a peak or valley value in the microphone signal). A4. Record the frequency value at this time; A5. Based on the preset formula relating diaphragm resonant frequency to tension, substitute the measured resonant frequency with the known diaphragm geometric parameters (such as radius R, side lengths a, b, etc.) and material parameters (area density m) to calculate the diaphragm tension T. For example, for a circular diaphragm, use the formula f = (2.405 / 2πR)·√(T / m); for a square diaphragm, use the formula f = (1 / 2a)·√(T / m); for a rectangular diaphragm, use the formula f = (1 / 2)·√(T / m)·√(1 / a² + 1 / b²).

[0055] In step A1, the resonant cavity uses the following parameters: Cavity shape: cylindrical, diameter D = 50mm, height H = 40mm, net internal volume of the cavity is approximately 78.5cm³; Cavity material: aluminum alloy (6061), wall thickness 3mm, inner wall polished to reduce sound wave reflection loss; Diaphragm mounting port: Located at the top of the cavity, with an opening diameter of Φ = 12mm, which matches the diaphragm ring to be tested (outer diameter 12mm). A rubber sealing ring is used during installation to ensure airtightness. Microphone mounting hole: Located at the center of the side of the cavity, for mounting a 1 / 4-inch prepolarized microphone (such as the B&K 4939 model) to measure the sound pressure inside the cavity; Sound pressure generator interface: Located at the bottom of the cavity, it is connected to a 2-inch full-range speaker through a waveguide. A gradual transition section is used between the speaker and the resonant cavity to reduce sound reflection.

[0056] The above resonant cavity was used to measure the diaphragm under test (10 mm in diameter, 0.05 kg / m² in surface density), with a sweep frequency range of 50 Hz to 5 kHz and a sweep speed of 1 octave / min. The peak sound pressure level was measured at the resonant frequency, and the tension was calculated by back-calculating the formula. The measurement accuracy can reach ±2%.

[0057] In summary, this invention achieves non-destructive, high-precision measurement of the elastic diaphragm tension on a diaphragm ring through the resonant cavity method, providing a scientific and feasible testing method for the batch and consistent manufacturing of diaphragms with predetermined resonant frequencies in industrial production.

[0058] Example 2: In industrial production, a diaphragm ring with a predetermined tension is manufactured as follows: A large-sized tensioning device, larger than the receiver's tensioning ring and with adjustable tension, is used. The elastic membrane is stretched to a predetermined tension determined by measurement. Then, the upper tensioning ring 30 or lower tensioning ring 50 for the receiver is fixed to this large-sized tensioning device using conductive adhesive. After the adhesive cures, the diaphragm ring is removed, resulting in a diaphragm ring with a predetermined resonant frequency. Specifically, industrial production includes the following steps: B1. Prepare a large-size tensioning device with adjustable tension, which is larger than the receiver tensioning ring. The diameter of the device is usually 20-30 cm (while the diameter of the receiver tensioning ring is usually only 1-2 cm). It has a tensioning ring structure with adjustable tension (e.g., through multiple circumferentially distributed adjusting screws, ratchet mechanism or air pressure adjustment). A large sheet of elastic film material (e.g. polyester film, polyimide film or other polymer film) is stretched flat on the large-size tensioning device. B2. Measure the tension value of the current elastic membrane on the large-size stretching device using the aforementioned resonant cavity method, and change the tension by adjusting the tightness of the large-size stretching device (e.g., simultaneously tightening or loosening all adjusting screws) until the tension of the elastic membrane reaches a predetermined value—this predetermined value is derived by back-calculating the tension-resonance frequency formula based on the target resonant frequency of the receiver diaphragm. B3. While maintaining the predetermined tension, the upper or lower diaphragm ring 30 for the receiver is fixed to the large-size diaphragm device using conductive adhesive. In practice, multiple receiver diaphragm rings can be simultaneously attached to the elastic membrane stretched on the large-size diaphragm device in a matrix arrangement. The conductive adhesive serves two purposes here: firstly, it firmly bonds the diaphragm rings to the elastic membrane, forming a diaphragm ring diaphragm assembly; secondly, if the elastic membrane surface has a metal plating, the conductive adhesive can also provide an electrical connection path. B4. After the adhesive has cured, remove the rings. Once the conductive adhesive has fully cured (usually 12-24 hours at room temperature, or accelerated by heating), use a sharp tool to cut the elastic membrane along the outer edge of each membrane ring. This will yield multiple finished membrane ring diaphragms with predetermined resonant frequencies. After cutting, the elastic membrane on each membrane ring diaphragm maintains the same tension as on the large membrane assembly (because the membrane ring has fixed the elastic membrane). However, since the diameter of the membrane ring is much smaller than that of the large membrane assembly, its resonant frequency will increase to the design target value according to the aforementioned formula.

[0059] In step B1, to ensure uniform tension on the elastic membrane in the large-size stretching device, the large-size stretching device preferably adopts one of the following structures: 1) Gear-linked stretching device: Multiple tensioning sliders are evenly arranged on the circumference of the stretching device. Each slider meshes with a central gear through a rack. When the central gear is rotated, all tensioning sliders move outward or inward synchronously, thereby applying uniform tension to the elastic membrane. This structure can ensure that the tension distribution error on the entire circumference is less than 2%; 2) Pneumatic stretching device: The elastic membrane is covered over the opening of an annular air chamber. By filling the air chamber with compressed air, the elastic membrane expands outward evenly, thereby generating uniform tension. The tension can be precisely controlled by adjusting the air pressure value, and the tension uniformity is better than that of the mechanical structure; 3) Spiral stretching device: Eight or more evenly distributed adjusting screws are arranged on the circumference of the stretching device. A torque wrench is used to tighten them sequentially in a diagonal order, applying the same torque value to each screw to ensure uniform tension. In practice, at least two rounds of tightening should be performed, with each round tightening amount being 50% and 100% of the target torque, and the torque-angle method should be used for control.

[0060] Industrial applicability: The piezoelectrically driven dual-diaphragm receiver and its frequency response adjustment method provided by this invention can be industrially manufactured and applied in fields such as hearing aids, headphones, in-ear monitors, communication headsets, and wearable electronic devices. Components such as the outer shell 10, outer shell 20, upper diaphragm ring 30, porous insulating gasket 40, lower diaphragm ring 50, and first and second electrode lead-out washers 60 and 80 can all be mass-produced using conventional injection molding, stamping, and die-cutting processes. The piezoelectric element 100 can be prepared using mature casting and high-temperature sintering processes. The resonant cavity measurement method and the diaphragm ring manufacturing method can be directly applied to online testing and mass production stages on production lines. Therefore, this invention has clear industrial applicability and mass production capability.

[0061] In summary, this method enables efficient, low-cost, and highly consistent mass production of diaphragm rings with precisely predetermined resonant frequencies.

[0062] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A piezoelectrically driven dual-diaphragm receiver, characterized in that, include: The outer casing includes an outer casing panel (10) and an outer casing body (20). The first diaphragm assembly includes an upper diaphragm ring (30) and a first elastic diaphragm fixed on the upper diaphragm ring (30); The second diaphragm assembly includes a lower diaphragm ring (50) and a second elastic diaphragm fixed on the lower diaphragm ring (50). The first diaphragm assembly and the second diaphragm assembly are disposed opposite to each other in the housing. A piezoelectric element (100) is disposed between the first diaphragm assembly and the second diaphragm assembly, and is driven to connect to the first elastic diaphragm and the second elastic diaphragm respectively; The piezoelectric element (100) is used to generate stretching vibration under the drive of an audio voltage signal. The stretching vibration directly generates a first sound wave and simultaneously drives the first elastic diaphragm and the second elastic diaphragm to generate membrane vibration, so as to generate a second sound wave and a third sound wave respectively. Then, the overall frequency response characteristics of the receiver are synthesized by the first sound wave, the second sound wave and the third sound wave.

2. The piezoelectrically driven dual-diaphragm receiver according to claim 1, characterized in that, The first elastic diaphragm has a first resonant frequency, and the second elastic diaphragm has a second resonant frequency that is different from the first resonant frequency, so that the effective operating frequency bands of the first diaphragm assembly and the second diaphragm assembly are staggered and complementary to each other, thereby widening the overall frequency response range of the receiver and smoothing its frequency response characteristics.

3. The piezoelectrically driven dual-diaphragm receiver according to claim 2, characterized in that, The first resonant frequency and the second resonant frequency are set by adjusting the tension of the first elastic diaphragm and / or the second elastic diaphragm.

4. The piezoelectrically driven dual-diaphragm receiver according to claim 1, characterized in that, A porous insulating gasket (40) is provided between the first diaphragm assembly and the second diaphragm assembly; the housing is also provided with a first electrode lead-out washer (60) and a second electrode lead-out washer (80) for fixing and electrical connection.

5. A piezoelectrically driven dual-diaphragm receiver according to claim 1, characterized in that, The receiver also includes a structure for reducing the air acoustic resistance between the first elastic diaphragm and the second elastic diaphragm; The structure consists of several through holes disposed on the first elastic diaphragm and / or the second elastic diaphragm, and / or several vent holes disposed on the housing corresponding to the air gap region between the two diaphragms.

6. A piezoelectrically driven dual-diaphragm receiver according to claim 1, characterized in that, The electrodes of the piezoelectric element (100) are led out to the outside of the housing through the first electrode lead-out washer (60) and the second electrode lead-out washer (80) to ensure the reliability of the electrical connection. The outer casing (10) is provided with fixing holes (70), and the outer casing (10) and the outer casing (20) are fixedly connected by connecting screw holes (90).

7. A method for adjusting the frequency response characteristics of a piezoelectrically driven dual-diaphragm receiver according to any one of claims 1 to 6, characterized in that, Includes the following steps; S1. Adjust the tension of the first elastic diaphragm to give it a first resonant frequency; S2. Adjust the tension of the second elastic diaphragm to give it a second resonant frequency that is different from the first resonant frequency; S3. The first diaphragm assembly and the second diaphragm assembly are arranged opposite to each other, and the piezoelectric element (100) is driven to be connected to the first elastic diaphragm and the second elastic diaphragm, so that the overall frequency response characteristics of the receiver are synthesized by the direct vibration of the piezoelectric element (100), the vibration of the first elastic diaphragm and the vibration of the second elastic diaphragm.

8. The method for adjusting the frequency response characteristics of a piezoelectrically driven dual-diaphragm receiver according to claim 7, characterized in that, The relationship between the tension and resonant frequency of the first or second elastic diaphragm is measured and calibrated using a resonant cavity method: the diaphragm to be tested is placed in a resonant cavity, excited by a sound pressure generator with a continuously variable frequency, its resonant frequency is measured by a laser or microphone, and the tension value is determined according to a preset formula relating the diaphragm resonant frequency and tension.

9. The method for adjusting the frequency response characteristics of a piezoelectrically driven dual-diaphragm receiver according to claim 8, characterized in that, In industrial production, a diaphragm with a predetermined tension is manufactured by using a large-size diaphragm device with adjustable tension that is larger than the receiver's diaphragm ring. After the elastic membrane is stretched to the predetermined tension determined by measurement, the upper diaphragm ring (30) or the lower diaphragm ring (50) for the receiver is fixed to the large-size diaphragm device with conductive adhesive. After the adhesive has cured, it is removed to obtain a diaphragm with the predetermined resonant frequency.

10. A piezoelectrically driven dual-diaphragm receiver according to claim 1, characterized in that, The piezoelectrically driven dual-diaphragm receiver does not contain a magnet drive component, and its drive power consumption is lower than that of a magnet-type receiver of the same level.

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