High-sound-pressure-level electroacoustic device structure

Abstract

The invention relates to the technical field of piezoelectric ceramic sounding structures, in particular to a high sound pressure level electroacoustic device structure, which comprises a shell and a piezoelectric vibrator, and is characterized in that the shell comprises an upper sounding cavity and a lower cover; the upper sounding cavity and the lower cover are assembled to form a shell, and the inner cavity of the shell is used for accommodating and installing the piezoelectric vibrator; a plurality of sound amplification holes penetrating to the inner cavity are formed in the surface of the upper sound production cavity, and the aperture ratio of the upper sound production cavity is at least 50%; the piezoelectric vibrator structurally comprises a piezoelectric ceramic piece and a metal vibrating diaphragm substrate, and the piezoelectric ceramic piece is adhered to one side or two sides of the metal vibrating diaphragm substrate; the sound pressure level of the electroacoustic device structure is high, the sound pressure level of the device can reach 100 db or above within the high frequency range of 15-50 kHz, and the sound pressure level of the device can reach 110 db under the frequency of 30 kHz.

Description

Technical Field

[0001] This invention relates to the field of piezoelectric ceramic sound-generating structure technology, specifically to a high sound pressure level electroacoustic device structure. Background Technology

[0002] Piezoelectric ceramic electroacoustic devices can effectively convert mechanical energy into electrical energy and are widely used in communication equipment, security systems, medical devices, instruments, industrial automation control, and home appliances. Piezoelectric materials are important functional materials that enable the conversion between mechanical and electrical energy. Lead zirconate titanate (PZT)-based piezoelectric ceramics, due to their superior dielectric and piezoelectric properties, are widely used in electronic components such as sensors, drivers, ultrasonic transducers, filters, buzzers, and loudspeakers.

[0003] A piezoelectric loudspeaker is a device that generates sound using the inverse piezoelectric effect. When a voltage signal is applied to the electrodes on a piezoelectric ceramic sheet, the ceramic sheet expands and contracts, and the ceramic sheet adheres to the diaphragm. The ceramic sheet drives the diaphragm to vibrate, which in turn vibrates the air to generate sound pressure and produce sound. Compared with traditional electroacoustic devices, piezoelectric loudspeakers are thinner and lighter, require a smaller acoustic cavity, and have advantages such as better heat dissipation, longer lifespan, and no magnetic field or electromagnetic radiation.

[0004] As applications extend towards higher frequencies and higher fidelity requirements, traditional single-sided piezoelectric ceramic electroacoustic devices are gradually revealing problems such as insufficient sound pressure level, narrow frequency response range, and low energy conversion efficiency. Summary of the Invention

[0005] To address the technical problem of low sound pressure level in existing piezoelectric electroacoustic structures, a high sound pressure level electroacoustic device structure is provided. The electroacoustic device structure of this invention has a high sound pressure level, reaching over 100 dB in the high-frequency range of 15-50 kHz, reaching 120 dB at around 18 kHz, and reaching 110 dB at 30 kHz.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0007] A high sound pressure level electroacoustic device structure includes a housing and a piezoelectric vibrator. The housing includes an upper sound-emitting cavity and a lower cover. The upper sound-emitting cavity and the lower cover are assembled to form the housing. The internal cavity of the housing is used to accommodate and install the piezoelectric vibrator. The surface of the upper sound-emitting cavity has a plurality of sound-amplifying holes that extend into the internal cavity. The opening ratio of the upper sound-emitting cavity is at least 50%, and the diameter of the sound-amplifying holes is 0.5-1.5 mm.

[0008] The piezoelectric oscillator comprises a piezoelectric ceramic sheet and a metal diaphragm substrate, wherein the piezoelectric ceramic sheet is bonded to one or both sides of the metal diaphragm substrate; the stoichiometric formula of the material of the piezoelectric ceramic sheet is: [Pb a Na 0.01 Sr 0.03-0.04 Ca 0.03-0.04 La 0.03-0.04 ][(Zr 0.55-0.6 Ti 0.4-0.45 ) b Mn 0.015-0.02 Sb 0.01 Nb 0.01 Sn 0.01 ]O3; where a takes values ​​in the range of 0.85-0.9, and b takes values ​​in the range of 0.95-0.99.

[0009] Furthermore, the stoichiometric formula of the piezoelectric ceramic sheet is [Pb]. 0.89 Na 0.01 Sr 0.034 Ca 0.033 La 0.0 33 ][(Zr 0.55 Ti 0.45 ) 0.952 Mn 0.018 Sb 0.01 Nb 0.01 Sn 0.01 O3. The material and its preparation method are described in application number 2025107513942.

[0010] Furthermore, the piezoelectric ceramic sheet is a single-layer piezoelectric sheet or a multi-layer piezoelectric sheet; the thickness of the piezoelectric ceramic sheet is 0.1-0.3 mm and the diameter is 20-30 mm; the surface of the piezoelectric ceramic sheet has a silver conductive layer.

[0011] Furthermore, the piezoelectric ceramic sheet is bonded to both surfaces of the metal diaphragm substrate via an adhesive layer. The thickness of the adhesive layer is controlled to be 2-8 micrometers, and the adhesive layer material is polyimide adhesive. The metal diaphragm substrate material can be, for example, copper or stainless steel. High-frequency vibration of the device easily leads to aging of the adhesive layer, while polyimide adhesive has good fatigue resistance. Additionally, the single-layer piezoelectric sheet employs techniques known to those skilled in the art: after grinding and preparing the ceramic material into a slurry, a single-layer piezoelectric sheet of the corresponding thickness is directly obtained using a casting process. Conductive silver paste is printed on its surface, and then it is polarized. The polarized ceramic sheet is then bonded to the surface of the metal diaphragm substrate to obtain the piezoelectric oscillator. The multilayer piezoelectric sheet employs techniques known to those skilled in the art: ceramic material is ground and mixed into a paste, then cast into a thin sheet using a casting process. Multiple thin sheets are prepared, and an internal electrode paste (such as silver-palladium paste) is printed on their surfaces. After baking and curing, the sheets are stacked according to requirements and sintered at 900-1000℃ to obtain a multilayer piezoelectric ceramic sheet. Conductive silver paste is then printed on its surface, cured, and sintered again at 900-1000℃. After polarization, the polarized multilayer ceramic sheet is bonded to the surface of a metal diaphragm substrate to obtain a piezoelectric oscillator (the printing of the internal electrode and silver paste is referenced in the applicant's patent CN117762249A, and the preparation of the multilayer ceramic sheet can be referenced in the applicant's patent CN119930282A or other prior art).

[0012] Furthermore, the diameter of the metal diaphragm substrate is larger than the diameter of the piezoelectric ceramic sheet but smaller than the diameter of the internal cavity, and the thickness of the metal diaphragm substrate is 0.1-0.2 mm; the thickness of the overall high sound pressure level electroacoustic device structure is 4-6 mm.

[0013] Furthermore, the lower cover is snapped into the upper sound cavity, and the upper sound cavity has a mounting portion that is fixed after being snapped into the lower cover;

[0014] The piezoelectric vibrator has leads that connect to the positive and negative terminals of an external power source (the positive and negative leads are soldered onto the piezoelectric vibrator).

[0015] The upper sound cavity has a stepped surface extending outward with a thickness of 0.1-2 mm, and the diameter of the stepped surface is 60%-90% of the diameter of the upper sound cavity. The amplification hole is located on the stepped surface.

[0016] The side of the housing has a lead wire outlet.

[0017] Beneficial technical effects: This invention utilizes an improved piezoelectric material. Due to the high piezoelectric coefficient of this improved piezoelectric material, a piezoelectric oscillator is made and combined with a special upper cavity structure. The sound pressure level of the device can reach over 100 dB in the high-frequency range of 15-50 kHz, over 120 dB at around 18 kHz, and over 110 dB at 30 kHz, thus realizing high-frequency vibration sound generation of high sound pressure level electroacoustic devices. Attached Figure Description

[0018] Figure 1 A schematic diagram of the piezoelectric vibrator structure of the high sound pressure level electroacoustic device of the present invention; wherein 2-piezoelectric vibrator, 21-piezoelectric ceramic sheet, 22-metal diaphragm substrate, 23-lead wire;

[0019] Figure 2 This is a schematic diagram of the housing structure of the high sound pressure level electroacoustic device of the present invention;

[0020] 1-Upper sound chamber, 11-Mounting part, 12-Amplification hole, 3-Lower cover;

[0021] Figure 3 The sound pressure test results are for the high sound pressure level electroacoustic device structure in Example 1. Detailed Implementation

[0022] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0023] Unless otherwise specifically stated, the numerical values ​​set forth in these embodiments do not limit the scope of the invention. Techniques and methods known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques and methods should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that values ​​expressed, for example, as "within the range of ab" or "between the range of ab," do not include the endpoint values ​​a and b; values ​​expressed as "for ab," "is ab," or "ab" include the endpoint values ​​a and b.

[0024] Experimental methods not specified in the following examples are generally performed according to national standards; if there is no corresponding national standard, they are performed according to general standard requirements or general methods.

[0025] Example 1

[0026] A high sound pressure level electroacoustic device structure includes a housing and a piezoelectric vibrator 2, as shown in the schematic diagram of the piezoelectric vibrator 2. Figure 1 As shown in the schematic diagram of the shell structure, Figure 2 As shown;

[0027] The housing includes an upper sound-emitting cavity 1 and a lower cover 3; the upper sound-emitting cavity 1 and the lower cover 3 are assembled to form a housing, and the internal cavity of the housing is used to accommodate and install the piezoelectric vibrator 2;

[0028] The upper sound cavity 1 has a plurality of sound-amplifying holes 13 extending into the inner cavity on its surface. The upper sound cavity 1 has a stepped surface extending outward with a thickness of 0.5 mm. The diameter of the stepped surface is 80% of the diameter of the upper sound cavity. The sound-amplifying holes 13 are located on the stepped surface. The opening ratio of the stepped surface is 70%. The diameter of the sound-amplifying holes is 1.0 mm.

[0029] The structure of the piezoelectric vibrator 2 includes a piezoelectric ceramic sheet 21 and a metal diaphragm substrate 22, wherein the piezoelectric ceramic sheet 21 is bonded to both sides of the metal diaphragm substrate 22. Figure 1 (Only one side is shown in the image).

[0030] The piezoelectric ceramic sheet 21 is a multilayer piezoelectric sheet with a thickness of 0.2 mm ± 0.05 mm and a diameter of 25 mm ± 0.2 mm; the stoichiometric formula of the material of the piezoelectric ceramic sheet 21 is [Pb]. 0.89 Na 0.01 Sr 0.034 Ca 0.033 La 0.033 ][(Zr 0.55 Ti 0.45 ) 0.952 Mn 0.018 Sb 0.01 Nb 0.01 Sn 0.01 O3, whose surface has a silver conductive layer;

[0031] The piezoelectric ceramic sheet 21 is bonded to the two surfaces of the metal diaphragm substrate 22 by an adhesive layer, the thickness of the adhesive layer is controlled to be 2-8 micrometers, and the adhesive layer material is polyimide adhesive.

[0032] The metal diaphragm substrate 22 is made of stainless steel, with a diameter of 29mm ± 0.1mm and a thickness of 0.15mm ± 0.01mm;

[0033] The lower cover 3 is snapped into the upper sound cavity 1 to form a shell, and the overall thickness of the shell is 4-5mm; the upper sound cavity 1 has a mounting part 11 that is fixed after being snapped into the lower cover;

[0034] The piezoelectric vibrator 2 has leads 23 that are connected to the positive and negative poles of an external power source (the positive lead and the negative lead are welded to the piezoelectric vibrator).

[0035] The lower cover 3 has a lead wire outlet on its side after it is snapped into the upper sound cavity 1.

[0036] In this case, the piezoelectric ceramic sheet 21 is a multilayer piezoelectric sheet, and the preparation process includes the following steps:

[0037] S1. Prepare the following raw materials according to stoichiometric ratios: 0.089 mol PbCO3, 0.05236 mol ZrO2, 0.04284 mol TiO2, 0.0005 mol Na2O, 0.0034 mol SrCO3, 0.0033 mol CaCO3, 0.00165 mol La2O3, 0.0009 mol Mn2O3, 0.0005 mol Nb2O3, 0.0005 mol Sb2O3, and 0.001 mol SnO2. The purity of each raw material should be ≥98%.

[0038] The first wet ball milling was performed: the above materials were added to a planetary ball mill, along with anhydrous ethanol and zirconium beads, wherein the mass ratio of materials to anhydrous ethanol to zirconium beads was 1:1.5:1. 3mm zirconium beads were used in combination with 0.8mm zirconium beads (the mass ratio of large beads to small beads was 6:4). The ball milling speed was 500 rpm, and the milling time was 12 hours. During the ball milling process, the liquid nitrogen temperature was controlled at 20℃. After the ball milling was completed, the materials were dried, and the zirconium beads were recovered by sieving.

[0039] S2. The material after the first ball milling is pre-sintered at 900℃ for 1 hour;

[0040] S3. The pre-calcined material is fed back into the planetary ball mill, along with anhydrous ethanol and zirconium beads. The mass ratio of material to anhydrous ethanol to zirconium beads is 1:4:1. 0.3mm zirconium beads are used in combination with 0.05mm zirconium beads (the mass ratio of large beads to small beads is 3:7). The ball milling speed is 300 rpm, and the milling time is 6 hours. During the ball milling process, the liquid nitrogen temperature is controlled at 20℃. After the ball milling is completed, the material is dried, and the zirconium beads are recovered by sieving.

[0041] The median particle size of the material obtained from the second wet ball milling was less than 0.5 micrometers;

[0042] S4. Preparation of casting slurry: The slurry consists of the following materials in 100% by mass: 53% ceramic powder obtained in S3, 20.5% polyvinyl butyral, 1.5% dioctyl phthalate, 6% xylene, 4% ethyl acetate, 3% n-propanol, and the balance being anhydrous ethanol. After mechanical grinding and stirring until uniform, the mixture is defoamed under vacuum to obtain the casting slurry.

[0043] S5. Casting process: The casting slurry is fed into the slurry tank of the casting machine and flows out from the casting outlet of the casting machine. The distance between the doctor blade and the carrier film is controlled to be 0.1 mm. Under the uniform linear motion of the carrier film at a speed of 1 cm / s, the casting slurry forms a casting strip on the carrier film. Then it enters the drying zone of the casting machine and is dried in hot air at 40°C for 3 hours. A single-layer preform film with no cracks or holes and good overall consistency can be obtained by peeling. The thickness is about 46.5 micrometers. Prepare 5 single-layer preform films.

[0044] S6. Screen print the inner electrode paste (silver-palladium paste) on one surface of the multiple single-layer blank films. After the inner electrode paste dries and cures, stack the films with the inner electrode paste facing up, arrange them in plastic, and sinter them in the range of 900-1000℃ to obtain multilayer parts.

[0045] The de-plasticizing process involves hot-pressing pre-forming followed by pre-sintering in a muffle furnace. The hot-pressing pre-forming process involves heating to 250°C at a heating rate of 1°C / min, then applying pressure after reaching the temperature. During the pressure-pressing process, venting is performed until the pressure reaches 2MPa for hot pressing for 0.5 hours, which causes adhesion between the multilayer ceramic sheets. The pre-sintering process involves heating to 350°C at a heating rate of 3°C / min for 2 hours, followed by heating to 750°C for 3 hours.

[0046] Then, conductive silver paste is printed on the surface of the multilayer component as required. After curing, it is sintered at 950℃ for 3 hours to form a silver conductive layer (as an external electrode) on the surface of the multilayer component. Then, it is polarized at 180℃ and an electric field of 2000V / mm for 30 minutes to form positive and negative electrodes. After marking, the material [Pb] is obtained. 0.89 Na 0.01 Sr 0.034 Ca 0.033 La 0.033 ][(Zr 0.55 Ti 0.45 ) 0.952 Mn 0.018 Sb 0.01 Nb 0.01 Sn 0.01 O3 and multi-layered piezoelectric ceramic sheets;

[0047] Then, the two aforementioned multilayer piezoelectric ceramic sheets are bonded to the two surfaces of the metal diaphragm substrate using polyimide adhesive, forming the piezoelectric oscillator in this case (a structure in which a single-layer piezoelectric sheet is bonded to both sides of a metal diaphragm substrate). The capacitance C = 1.6 μf (test standard GB / T15750-2008, 120 Hz), planar electromechanical coupling coefficient Kp = 82% (calculated after resonance method test), and longitudinal piezoelectric strain constant d 33 =800 pC / N (GB / T 11309-1989), dielectric loss δ=0.03 (test standard GB / T5594.4-2015), mechanical quality factor Q m =50.

[0048] A sound pressure level test was conducted on the product structure in this case (test method: the product was placed on the test platform of the CRY6125 electroacoustic tester, and a microphone was placed 30cm above it for reception). The results are as follows: Figure 2 As shown, by Figure 2 It can be seen that the device's sound pressure level can reach over 100 dB in the high-frequency range of 15-50 kHz, 120 dB at around 18 kHz, and 110 dB at 30 kHz.

[0049] Example 2

[0050] The high sound pressure level electroacoustic device in this case has the same structure as that in Example 1, except that:

[0051] The upper sound cavity has a stepped surface extending outward with a thickness of 0.8 mm. The diameter of the stepped surface is 70% of the diameter of the upper sound cavity. The amplification hole is located on the stepped surface. The opening ratio of the stepped surface is 80%. The diameter of the amplification hole is 1.5 mm.

[0052] The piezoelectric ceramic sheet in the piezoelectric oscillator is a multilayer piezoelectric sheet, and the preparation process includes the following steps:

[0053] Steps S1-S4 are the same as in Example 1;

[0054] S5. Casting process: The casting slurry is fed into the slurry tank of the casting machine and flows out from the casting outlet of the casting machine. The distance between the doctor blade and the carrier film is controlled to be 50 micrometers. Under the uniform linear motion of the carrier film at a speed of 1 cm / s, the casting slurry forms a casting strip on the carrier film. Then it enters the drying zone of the casting machine and is dried in hot air at 40°C for 3 hours. A single-layer preform film with no cracks or holes and good overall consistency can be obtained by peeling. The thickness is about 22.5 micrometers. 10 single-layer preform films are prepared.

[0055] S6. Same as in Example 1, the material obtained is

[0056] [Pb0.89 Na 0.01 Sr 0.034 Ca 0.033 La 0.033 ][(Zr 0.55 Ti 0.45 ) 0.952 Mn 0.018 Sb 0.01 Nb 0.01 Sn 0.01 O3 and multi-layered piezoelectric ceramic sheets.

[0057] Then, two multilayer piezoelectric ceramic sheets are bonded to the two surfaces of the metal diaphragm substrate using polyimide adhesive, forming the piezoelectric oscillator in this case (a structure in which multilayer piezoelectric sheets are bonded to both sides of the metal diaphragm substrate). The capacitance C = 6.6 μf (test standard GB / T15750-2008, 120Hz), planar electromechanical coupling coefficient Kp = 82% (calculated after resonance method test), and longitudinal piezoelectric strain constant d 33 =802 pC / N (GB / T 11309-1989), dielectric loss δ=0.03 (test standard GB / T5594.4-2015), mechanical quality factor Q m =50;

[0058] The sound pressure level of the product in this case was tested (test method: the product was placed on the test platform of the CRY6125 electroacoustic tester, and a microphone was placed 30cm above it for reception). The results showed that the sound pressure level of the device could reach more than 100dB in the high frequency range of 20-50kHz, and the sound pressure level reached 110dB at 30kHz.

[0059] This invention utilizes an improved piezoelectric material with a high piezoelectric coefficient to create a piezoelectric oscillator. This oscillator is then combined with a special upper cavity structure, which vibrates and generates sound when energized. The sound is transmitted through compression in the upper cavity, thus achieving high-frequency vibration and sound generation of a high sound pressure level electroacoustic device.

[0060] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A structure for a high sound pressure level electroacoustic device, characterized in that, The device includes a housing and a piezoelectric vibrator. The housing includes an upper sound-producing cavity and a lower cover. The upper sound-producing cavity and the lower cover are assembled to form the housing. The internal cavity of the housing is used to accommodate and install the piezoelectric vibrator. The surface of the upper sound-producing cavity has a plurality of sound-amplifying holes that extend into the internal cavity. The opening ratio of the upper sound-producing cavity is at least 50%, and the diameter of the sound-amplifying holes is 0.5-1.5 mm. The piezoelectric oscillator comprises a piezoelectric ceramic sheet and a metal diaphragm substrate, wherein the piezoelectric ceramic sheet is bonded to one or both sides of the metal diaphragm substrate; the stoichiometric formula of the material of the piezoelectric ceramic sheet is: [Pb a Na 0.01 Sr 0.03- 0.04 Ca 0.03-0.04 La 0.03-0.04 ][(Zr 0.55-0.6 Ti 0.4-0.45 ) b Mn 0.015-0.02 Sb 0.01 Nb 0.01 Sn 0.01 O3; Where a takes values ​​in the range of 0.85-0.9, and b takes values ​​in the range of 0.95-0.

99.

2. The high sound pressure level electroacoustic device structure according to claim 1, characterized in that, The stoichiometric formula of the material of the piezoelectric ceramic sheet is: [Pb 0.89 Na 0.01 Sr 0.034 Ca 0.033 La 0.033 [(Zr 0.55 Ti 0.45 ) 0.952 Mn 0.018 Sb 0.01 Nb 0.01 Sn 0.01 ]O3。 3. The high sound pressure level electroacoustic device structure according to claim 2, characterized in that, The piezoelectric ceramic sheet is a single-layer piezoelectric sheet or a multi-layer piezoelectric sheet; the thickness of the piezoelectric ceramic sheet is 0.1-0.3 mm and the diameter is 20-30 mm; the surface of the piezoelectric ceramic sheet has a silver conductive layer.

4. The high sound pressure level electroacoustic device structure according to claim 3, characterized in that, The piezoelectric ceramic sheet is bonded to the two surfaces of the metal diaphragm substrate by an adhesive layer. The thickness of the adhesive layer is controlled to be 2-8 micrometers. The adhesive layer material is polyimide adhesive. The metal diaphragm substrate material can be, for example, copper or stainless steel.

5. A high sound pressure level electroacoustic device structure according to any one of claims 1-4, characterized in that, The diameter of the metal diaphragm substrate is larger than the diameter of the piezoelectric ceramic sheet but smaller than the diameter of the internal cavity, and the thickness of the metal diaphragm substrate is 0.1-0.2 mm; the thickness of the overall high sound pressure level electroacoustic device structure is 4-6 mm.

6. The structure of a high sound pressure level electroacoustic device according to any one of claims 1-4, characterized in that, The lower cover is snapped into the upper sound cavity, and the upper sound cavity has a mounting part that is fixed after being snapped into the lower cover; The piezoelectric vibrator has leads that connect to the positive and negative terminals of an external power source; The upper sound cavity has a stepped surface extending outward with a thickness of 0.1-2 mm, and the diameter of the stepped surface is 60%-90% of the diameter of the upper sound cavity. The amplification hole is located on the stepped surface. The side of the housing has a lead wire outlet.

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