CN116074708A

CN116074708A - Vibrating diaphragm of sound generating device and sound generating device

Info

Publication number: CN116074708A
Application number: CN202111275761.4A
Authority: CN
Inventors: 刘春发; 惠冰; 李春; 凌风光; 马长书; 付逊; 张成飞
Original assignee: Goertek Inc
Current assignee: Goertek Inc
Priority date: 2021-10-29
Filing date: 2021-10-29
Publication date: 2023-05-05

Abstract

The application discloses a vibrating diaphragm of a sound generating device and the sound generating device, wherein the vibrating diaphragm comprises at least one layer of modified ethylene-acrylic ester rubber film layer, and the modified ethylene-acrylic ester rubber film layer is prepared by mixing inorganic hollow microspheres, an additive and ethylene-acrylic ester polymer to form a rubber compound and then carrying out crosslinking reaction; wherein the particle size of the inorganic hollow microsphere is 1-60 mu m, and the distribution density of the inorganic hollow microsphere in the modified ethylene-acrylic ester rubber film layer is 0.15g/cm ³ ～0.9g/cm ³ The surface contact angle between the modified ethylene-acrylic ester rubber film layer and water is more than or equal to 70 degrees. The application is throughInorganic hollow microspheres, additives and ethylene-acrylic rubber are mixed to form a mixed rubber, and then a crosslinking reaction is carried out to prepare a modified ethylene-acrylic rubber film layer, and the modified ethylene-acrylic rubber film layer is used as a vibrating diaphragm material, so that the ageing resistance of the vibrating diaphragm is improved, the mucous membrane state of the rubber vibrating diaphragm material is slowed down, the density of the vibrating diaphragm is reduced, and the medium-frequency sensitivity of a sounding device is improved.

Description

Vibrating diaphragm of sound generating device and sound generating device

Technical Field

The present application relates to the field of electroacoustic technologies, and more particularly, to a diaphragm of a sound generating device and a sound generating device using the diaphragm.

Background

With the improvement of requirements for high power, waterproof performance, high sound quality and the like of a speaker, a rubber diaphragm has been widely used in the field of speakers. However, since the diaphragm density of the rubber material is large (. Gtoreq.1.2 g/cm) ³ ) The thickness is thicker, can lead to the vibrating diaphragm quality big for the vibrating diaphragm of rubber material is high in vibration system vibration quality, can lead to sound generating mechanism's intermediate frequency Fr (frequency response) low.

In addition, in the process of manufacturing the diaphragm by using the rubber material, the problem of mucous membrane is easy to occur. The mucous membrane can cause rubber dimensional stability poor, and the drawing of patterns degree of difficulty is big, causes corrosivity etc. to the mould, and the mucous membrane is serious can make extremely thin vibrating diaphragm appear tearing deformation and rupture of membranes to cause the shaping of vibrating diaphragm product poor, reduce the product yield.

Therefore, a new solution is needed to solve the above-mentioned problems.

Disclosure of Invention

An object of the present application is to provide a diaphragm of a sound generating device.

Another object of the present application is to provide a sound generating apparatus comprising the above-mentioned diaphragm.

In order to achieve the above object, the present application provides the following technical solutions.

According to the vibrating diaphragm of the sound generating device of the embodiment of the first aspect of the application, the vibrating diaphragm packThe modified ethylene-acrylic ester rubber film is prepared by mixing inorganic hollow microspheres, additives and ethylene-acrylic ester polymers to form a mixed rubber and then carrying out a crosslinking reaction; wherein the particle size of the inorganic hollow microspheres is 1-60 mu m, and the distribution density of the inorganic hollow microspheres in the modified ethylene-acrylic ester rubber film layer is 0.15g/cm ³ ～0.9g/cm ³ The surface contact angle between the modified ethylene-acrylic ester rubber film layer and water is more than or equal to 70 degrees.

According to some embodiments of the application, the inorganic cenospheres account for 5 to 48 weight percent of the total amount of the rubber compound.

According to some embodiments of the present application, the modified ethylene-acrylate rubber film layer has a tensile strength decrease of less than or equal to 46% and an elongation at break decrease of less than or equal to 71% after aging for 168 hours at 180 ℃ under hot air.

According to some embodiments of the present application, the compressive strength of the inorganic hollow microsphere is not less than 10MPa.

According to some embodiments of the present application, the tensile strength of the modified ethylene-acrylate rubber film layer is greater than or equal to 5MPa.

According to some embodiments of the present application, the modified ethylene-acrylate rubber film layer has a dissipation factor > 0.12 at room temperature.

According to some embodiments of the present application, the modified ethylene-acrylate rubber film layer has a density of 0.5g/cm ³ ～1.1g/cm ³ 。

According to some embodiments of the present application, the glass transition temperature of the modified ethylene-acrylate rubber film layer is less than or equal to-10 ℃.

According to some embodiments of the present application, the additive comprises a cross-linking agent, a reinforcing agent, and an anti-aging agent, wherein the cross-linking agent is at least one of a metal oxide, a metal peroxide, an organic oxide, an organic peroxide, and an amine-based curing system; the reinforcing agent is at least one of carbon black, silicon dioxide, calcium carbonate, barium sulfate, organic montmorillonite, unsaturated carboxylic acid metal salt, talcum powder, clay, mica powder, feldspar powder, sulfate, magnetic powder and diatomite; the antioxidant is at least one of an antioxidant N-445, an antioxidant 246, an antioxidant 4010, an antioxidant SP, an antioxidant RD, an antioxidant ODA, an antioxidant OD and an antioxidant WH-02.

According to some embodiments of the present application, the cross-linking agent comprises 0.5wt% to 4.6wt% of the rubber compound, the reinforcing agent comprises 5wt% to 71wt% of the rubber compound, and the anti-aging agent comprises 0.1wt% to 5.9wt% of the rubber compound.

According to some embodiments of the present application, the diaphragm is a single-layer structure, and the diaphragm is composed of one modified ethylene-acrylic ester rubber film layer.

According to some embodiments of the present application, the diaphragm is a composite layer structure, and the diaphragm further includes a film layer made of at least one of a thermoplastic elastomer, an engineering plastic, and a thermosetting elastomer.

According to the sound production device of the second aspect of the embodiment of the application, the sound production device comprises a vibration system and a magnetic circuit system matched with the vibration system, the vibration system comprises a vibrating diaphragm and a voice coil combined with one side of the vibrating diaphragm, the magnetic circuit system drives the voice coil to vibrate so as to drive the vibrating diaphragm to produce sound, and the vibrating diaphragm is the vibrating diaphragm according to the embodiment of the application.

According to the sound production device of the third aspect embodiment of the application, the sound production device comprises a shell, and a magnetic circuit system and a vibration system which are arranged in the shell, wherein the vibration system comprises a voice coil, a first vibrating diaphragm and a second vibrating diaphragm, the top of the voice coil is connected with the first vibrating diaphragm, the magnetic circuit system drives the voice coil to vibrate so as to drive the first vibrating diaphragm to produce sound, two ends of the second vibrating diaphragm are respectively connected with the shell and the bottom of the voice coil, and the second vibrating diaphragm is the vibrating diaphragm according to the embodiment of the application.

According to the vibrating diaphragm of the sound production device, after the inorganic hollow microspheres, the additive and the ethylene-acrylic ester rubber are mixed to form the mixed rubber, the modified ethylene-acrylic ester rubber film layer prepared through the crosslinking reaction is a vibrating diaphragm material, so that the density of the vibrating diaphragm can be reduced while the vibrating diaphragm material has certain mechanical strength, and the medium-frequency sensitivity of the sound production device is improved. In addition, the inorganic hollow microsphere can form a compact oxide layer on the surface of the rubber, so that the ageing resistance of the vibrating diaphragm material is effectively improved, and the ageing resistance of the vibrating diaphragm is improved. In addition, through above-mentioned setting, can also slow down the mucous membrane state of rubber class vibrating diaphragm material effectively, reduce the drawing of patterns degree of difficulty, improve the product yield.

Other features of the present application and its advantages will become apparent from the following detailed description of exemplary embodiments of the present application, which proceeds with reference to the accompanying drawings.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description, serve to explain the principles of the application.

FIG. 1 is a graph showing test curves of vibration displacement of different portions of a diaphragm of a sound emitting device at different frequencies according to an embodiment of the present application;

FIG. 2 is a mid-frequency Fr plot of modified ethylene-acrylate rubber film layers of different densities for a diaphragm of a sound emitting device according to an embodiment of the present application;

FIG. 3 is a schematic diagram of the overall structure of a sound generating apparatus according to an embodiment of the present application;

FIG. 4 is a schematic view of a partial structure of a sound generating apparatus according to an embodiment of the present application;

FIG. 5 is a cross-sectional view of a sound emitting device according to an embodiment of the present application;

fig. 6 is an exploded view of a sound emitting device according to an embodiment of the present application.

Reference numerals

A sound generating device 100;

a housing 10; a voice coil 11; a first diaphragm 12; a second diaphragm 13; a magnetic circuit system 14;

a diaphragm 15; a folded ring portion 151; ball top 152.

Detailed Description

Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that: the relative arrangement of the components and steps, numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present application unless it is specifically stated otherwise.

The following description of at least one exemplary embodiment is merely exemplary in nature and is in no way intended to limit the application, its application, or uses.

Techniques, methods, and apparatus known to one of ordinary skill in the relevant art may not be discussed in detail, but are intended to be part of the specification where appropriate.

In all examples shown and discussed herein, any specific values should be construed as merely illustrative, and not a limitation. Thus, other examples of exemplary embodiments may have different values.

It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further discussion thereof is necessary in subsequent figures.

The diaphragm of the sound generating device according to the embodiment of the application is specifically described below with reference to the accompanying drawings.

According to the vibrating diaphragm of the sound production device, the vibrating diaphragm comprises at least one layer of modified ethylene-acrylic ester rubber film layer, and the modified ethylene-acrylic ester rubber film layer is prepared by mixing inorganic hollow microspheres, additives and ethylene-acrylic ester polymers to form a rubber compound and then carrying out crosslinking reaction. Wherein the particle size of the inorganic hollow microsphere is 1-60 mu m, and the distribution density of the inorganic hollow microsphere in the modified ethylene-acrylic ester rubber film layer is 0.15g/cm ³ ～0.9g/cm ³ The surface contact angle between the modified ethylene-acrylic ester rubber film layer and water is more than or equal to 70 degrees.

The vibrating diaphragm of the sound generating device according to the embodiment of the application can be formed by at least one modified ethylene-acrylic ester rubber film layer. Specifically, the diaphragm in the application may have a single-layer structure or a multi-layer composite structure. When the diaphragm is of a single-layer structure, i.e., the diaphragm is made of one modified ethylene-acrylate rubber film layer of the present application. When the vibrating diaphragm is of a multilayer composite structure, the vibrating diaphragm comprises at least one modified ethylene-acrylic ester rubber film layer, and the vibrating diaphragm is formed by compositing the modified ethylene-acrylic ester rubber film layer with film layers of other materials. Optionally, when the diaphragm contains multiple layers of modified ethylene-acrylic ester rubber film layers, two adjacent layers of modified ethylene-acrylic ester rubber film layers can be arranged at intervals, namely, film layers of other materials can be arranged between two adjacent layers of modified ethylene-acrylic ester rubber film layers, and the two adjacent layers of modified ethylene-acrylic ester rubber film layers can be bonded and arranged, so that the diaphragm can be selectively arranged according to actual use requirements.

Specifically, the ethylene-acrylate polymer may be a copolymer of ethylene and acrylate, and the chemical formula thereof may be at least one of the following chemical formulas:

wherein x, y and z in the formula (I) and the formula (II) are natural numbers; r, R' is alkyl.

Wherein the modified ethylene-acrylic ester rubber film layer is prepared by adding inorganic hollow microspheres into an ethylene-acrylic ester polymer. Specifically, the inorganic hollow microspheres, the additive and the ethylene-acrylic ester polymer are mixed to form a mixed rubber, and the mixed rubber is vulcanized to form the modified ethylene-acrylic ester rubber film. The ethylene-acrylic ester polymer can form ethylene-acrylic ester rubber, the ethylene-acrylic ester rubber is equivalent to a base material of a vibrating diaphragm material, and the inorganic hollow microspheres can be dispersed in the base material after the mixing process of the inorganic hollow microspheres and the ethylene-acrylic ester polymer. Because the distribution density of the inorganic hollow microspheres is smaller than that of the rubber, the density of the modified ethylene-acrylic ester rubber film layer can be reduced by adding the inorganic hollow microspheres into the rubber, and the low-density vibrating diaphragm is obtained.

Under the condition that the ethylene-acrylic ester rubber vibrating diaphragm material added with the inorganic hollow microspheres has the same hardness as the ethylene-acrylic ester rubber vibrating diaphragm material without the inorganic hollow microspheres in the prior art, the vibrating diaphragm has lower vibrating diaphragm density and can reduce the vibration quality of a vibrating diaphragm system. That is, the diaphragm of the present application can promote the intermediate frequency response of the sound generating device, so that the sound generating device has higher intermediate frequency sensitivity.

Inorganic hollow microsphere is a hollow, thin-walled, hard, lightweight sphere with a high strength to density ratio. The utility model provides a sound generating mechanism's vibrating diaphragm adds there is inorganic hollow microsphere, can reduce density and weight of rubber effectively to make the whole weight of vibrating diaphragm alleviate, reduce vibration system's vibration quality, promoted sound generating mechanism's sensitivity. The inorganic hollow micro beads can be hollow glass micro beads, hollow ceramic micro beads and the like. The main component of the hollow glass bead is borosilicate, and the borosilicate has high temperature resistance.

Inorganic hollow microspheres are added into AEM (ethylene-acrylic ester) rubber, a compact oxide layer is formed on the surface of the rubber, permeation of oxygen molecules is prevented, and ageing resistance of the AEM rubber is effectively improved. In addition, the inorganic hollow microsphere has higher compressive strength, and can ensure that the inorganic hollow microsphere is not extruded and crushed in the mixing process.

Further, the particle size of the inorganic hollow microspheres is selected in the range of 1 μm to 60 μm, preferably 5 μm to 30 μm, and for example, the particle size of the inorganic hollow microspheres may be 1 μm, 5 μm, 10 μm, 20 μm, 30, 40 μm, 50 μm or 60 μm. That is, the inorganic hollow microspheres with different particle diameters can be selected according to the thickness of the vibrating diaphragm, so as to ensure that the inorganic hollow microspheres are uniformly dispersed in the base material.

In addition, as the size of the inorganic hollow microsphere is reduced, the distribution density of the inorganic hollow microsphere tends to increase, and the distribution density of the inorganic hollow microsphere can be controlled to be 0.15g/cm ³ ～0.9g/cm ³ Within the range, for example, the distribution density of the inorganic hollow microspheres may be 0.15g/cm ³ 、0.2g/cm ³ 、0.35g/cm ³ 、0.5g/cm ³ 、0.6g/cm ³ 、0.7g/cm ³ 、0.8g/cm ³ Or 0.9g/cm ³ . To ensure that the inorganic hollow micro-beads can effectively reduce the density of the vibrating diaphragmThe distribution density of the inorganic hollow microspheres is preferably 0.35g/cm ³ ～0.8g/cm ³ 。

It should be noted that, the small molecule complexing agent in the rubber can migrate to the rubber surface in the high temperature processing and forming process, and the accumulation of the small molecule complexing agent on the mold is increased due to multiple times of forming, and the small molecule complexing agent on the rubber surface and the small molecule complexing agent on the mold form physical adsorption effect, so that mucous membrane is formed.

Since the mucous membrane is related to the surface polar groups of the membrane layer, the mucous membrane degree of the diaphragm can be characterized by measuring the surface contact angle, and the smaller the surface contact angle is, the higher the mucous membrane property of the diaphragm is. The first table shows the effect of the diaphragm material formed by AEM rubber added with different contents of inorganic hollow microspheres on the surface contact angle of the diaphragm material. The inorganic hollow bead is selected as a hollow glass bead, and the hollow glass bead is one of the inorganic hollow beads, and the hollow glass bead or other inorganic hollow beads can also reflect the effect of the inorganic hollow bead in the material.

The influence of the content of the inorganic hollow microspheres in the vibrating diaphragm material on the mucous membrane property of the vibrating diaphragm is as follows:

the testing method comprises the following steps: the test was performed according to the GGS1616 drop angle standard, with ten point measurements taken for each sample.

List one

Hollow glass bead addition (wt%)	0	5	10	40	48
						Surface contact angle (°)	68	73	78	91	95

As shown in table one, as the content of the hollow glass beads increases, the surface contact angle of the diaphragm material gradually increases. Specifically, when the adding amount of the hollow glass beads is 0, the surface contact angle of the diaphragm material is only 68 degrees. With the increase of the addition amount of the hollow glass beads, the surface contact angle component of the vibrating diaphragm material is increased. Because the inorganic hollow microsphere has high rigidity, a compact protective layer can be formed on the surface of the rubber, the migration of the micromolecular complexing agent can be effectively prevented, and the mucous membrane state of the rubber vibrating diaphragm is greatly slowed down. The inorganic hollow microspheres are added into the ethylene-acrylic ester polymer, so that the surface contact angle between the modified ethylene-acrylic ester rubber film layer and water is more than or equal to 70 degrees, the problem of the mucous membrane of the vibrating membrane can be effectively solved, and the demolding difficulty of the vibrating membrane is reduced.

Therefore, according to the vibrating diaphragm of the sound production device, after the inorganic hollow microspheres, the additive and the ethylene-acrylic acid ester polymer are adopted to form the rubber compound, the modified ethylene-acrylic acid ester rubber film layer prepared through the crosslinking reaction is a vibrating diaphragm material, so that the density of the vibrating diaphragm can be reduced while the vibrating diaphragm material has certain mechanical strength, and the medium frequency response of the sound production device is improved. In addition, the inorganic hollow microsphere can form a compact oxide layer on the surface of the rubber, so that the ageing resistance of the vibrating diaphragm material can be effectively improved. In addition, through above-mentioned setting, can also effectively slow down the mucous membrane state of rubber class vibrating diaphragm material, effectively reduce the drawing of patterns degree of difficulty of vibrating diaphragm.

According to one embodiment of the application, the compressive strength of the inorganic hollow microsphere is more than or equal to 10MPa.

That is, the inorganic hollow microsphere has higher compressive strength, not only can ensure that the inorganic hollow microsphere is not extruded and crushed in the mixing process, but also can effectively improve the tensile strength of the modified ethylene-acrylic ester rubber film layer by adding the inorganic hollow microsphere into the ethylene-acrylic ester polymer. When the vibrating diaphragm has higher mechanical strength, the phenomenon that the vibrating diaphragm is excessively stretched due to overlarge driving force in a limiting environment can be avoided, and the using effect of the vibrating diaphragm is further guaranteed.

In some embodiments of the present application, the inorganic cenospheres comprise 5 to 48 weight percent of the total amount of the rubber compound.

That is, inorganic cenospheres may be added to the ethylene-acrylate polymer in an amount of 5 to 48% by weight based on the total amount of the rubber compound. Along with the increase of the addition amount of the inorganic hollow microspheres, the density of the modified ethylene-acrylic ester rubber film layer is reduced, and the diaphragm material with the required performance can be obtained by controlling the addition amount of the inorganic hollow microspheres. The content of the inorganic hollow microsphere may be any value between 5wt% and 48wt%, for example, the content of the inorganic hollow microsphere may be 5wt%, 10wt%, 15wt%, 20wt%, 30wt%, 40wt% or 48wt%.

It should be noted that, since the density of the inorganic hollow microsphere is far smaller than that of the rubber, the density of the rubber material is significantly reduced with the increase of the addition amount of the inorganic hollow microsphere. In particular, when the content of the inorganic hollow microspheres is low (less than 5wt percent), the influence on the density of the vibrating diaphragm material is small, and the vibrating diaphragm still has a large density.

When the content of the inorganic hollow microsphere is too high (more than 48wt percent), the maximum amplitude of the prepared vibrating diaphragm is reduced under the same driving force due to the too high mechanical strength, so that the low-frequency Fr of the sound generating device is reduced. In addition, the density of the modified ethylene-acrylic ester rubber film layer is greatly reduced by excessively adding the inorganic hollow microspheres, and the prepared vibrating diaphragm has low elongation at break and strength and is easy to collapse, rupture and other reliability problems.

Therefore, the modified ethylene-acrylic ester rubber film layer prepared by adding the inorganic hollow microspheres accounting for 5-48 wt% of the total amount of the rubber compound is taken as the vibrating diaphragm material, so that the density and the strength of the vibrating diaphragm can be simultaneously considered, and the excellent medium-frequency performance and the excellent low-frequency performance of the vibrating diaphragm are effectively ensured.

According to one embodiment of the application, after the modified ethylene-acrylic ester rubber film layer is aged for 168 hours under the hot air at 180 ℃, the tensile strength of the modified ethylene-acrylic ester rubber film layer is reduced by less than or equal to 46 percent, and the elongation at break is reduced by less than or equal to 71 percent.

Specifically, the chemical component of the hollow glass microsphere is borosilicate, the borosilicate has higher temperature resistance, and when the borosilicate is added into AEM rubber, a compact oxide layer is formed on the surface of the AEM rubber, so that the permeation of oxygen molecules can be prevented, and the ageing resistance of the AEM rubber is effectively improved. Table two shows the effect of adding different amounts of inorganic hollow microspheres on the decrease in tensile strength and elongation at break of AEM rubber under the condition of aging for 168 hours in air at 180 ℃.

The content of the inorganic hollow microspheres in the vibrating diaphragm material has the following influence on the ageing resistance of the vibrating diaphragm:

test methods tensile strength and elongation at break were determined according to ASTM D412-2016, the test specimens were dumbbell-shaped and the tensile rate was 500mm/min, and each group of samples was measured 5 times for average.

Watch II

Hollow glass bead addition (wt%)	0	5	15	20	30	40
							Percent decrease in tensile strength (%)	51.7	45	39.4	38.1	35.8	32.6
Percent reduction in elongation at break (%)	75.6	69.7	65.1	53.8	47.2	42.1

As shown in Table II, when the addition amount of the hollow glass beads was 0, the percent decrease in tensile strength and the percent decrease in elongation at break after aging of the diaphragm material were greater than the percent decrease in tensile strength and the percent decrease in elongation at break after aging of the diaphragm material to which the hollow glass beads were added in a certain amount. With the increase of the addition amount of the inorganic hollow microspheres, the tensile strength decline percentage and the elongation at break of the vibrating diaphragm material are gradually decreased after aging, and the ageing resistance of the vibrating diaphragm material is improved. Namely, under extreme environment, the modified ethylene-acrylic ester rubber film layer can also have good physical and chemical properties.

In some embodiments of the present application, the tensile strength of the modified ethylene-acrylate rubber film layer is greater than or equal to 5MPa.

That is, the low-density rubber diaphragm material is formed by adding a certain content of inorganic hollow microspheres into the ethylene-acrylic ester polymer, so that the tensile strength of the modified ethylene-acrylic ester rubber diaphragm layer is more than or equal to 5MPa. Preferably, the tensile strength of the modified ethylene-acrylic ester rubber film layer is more than or equal to 7MPa.

Because the inorganic hollow microspheres have higher compressive strength, the tensile strength of AEM rubber can be effectively improved by adding the inorganic hollow microspheres into AEM rubber, and the vibrating diaphragm made of the AEM rubber has higher mechanical strength, so that the phenomenon that the vibrating diaphragm is excessively stretched due to overlarge driving force in a limiting environment can be avoided. Table three shows the effect of the content of inorganic cenospheres on the tensile strength of the diaphragm material.

The influence of the content of the inorganic hollow microspheres in the vibrating diaphragm material on the tensile strength of the vibrating diaphragm is as follows:

watch III

Hollow glass bead addition (wt%)	0	5	15	20	30	40
							Tensile Strength (MPa)	4.3	5.6	7.1	10.2	12.4	15.9

As shown in table three, the tensile strength of the modified ethylene-acrylate rubber film layer increased significantly with increasing hollow glass bead content. That is, by adding the inorganic hollow microspheres into the ethylene-acrylic ester rubber, the tensile strength of the modified ethylene-acrylic ester rubber film layer can be improved, and the use effect of the vibrating diaphragm is ensured. Further, the diaphragm with required tensile strength can be obtained by adjusting the addition amount of the inorganic hollow microspheres.

According to some embodiments of the present application, the modified ethylene-acrylate rubber film layer has a density of 0.5g/cm ³ ～1.1g/cm ³ Therefore, the ethylene-acrylic ester rubber film layer can have a good weight reduction effect, and the sounding sensitivity of the vibrating diaphragm can be improved. Optionally, the density of the modified ethylene-acrylic ester rubber film layer is 0.5g/cm ³ 、0.6g/cm ³ 、0.7g/cm ³ 、0.8g/cm ³ 、0.9g/cm ³ 、1g/cm ³ Or 1.1g/cm ³ . Therefore, through the arrangement, the modified ethylene-acrylic ester rubber film layer can reduce the weight by 30% -50%, a good weight reduction effect is achieved, and the sounding sensitivity of the vibrating diaphragm is greatly improved.

According to one embodiment of the application, the tensile strength of the modified ethylene-acrylic ester rubber film layer when the film layer is broken is 2 MPa-45 MPa, and the tearing strength is 15N/mm-100N/mm.

That is, the low-density rubber diaphragm material is formed by adding inorganic cenospheres to an ethylene-acrylic acid ester polymer, and when the diaphragm material is broken, the tensile strength thereof can be controlled in the range of 2MPa to 45MPa, and the tear strength can be controlled in the range of 15N/mm to 100N/mm. For example, the tensile strength of the modified ethylene-acrylate rubber may be 2MPa, 6MPa, 10MPa, 16MPa, 20MPa, 25MPa, 30MPa, 40MPa, or 45MPa. The tear strength of the modified ethylene-acrylate rubber may be 15N/mm, 30N/mm, 45N/mm, 50N/mm, 70N/mm, 90N/mm or 100N/mm. Namely, the modified ethylene-acrylic ester rubber film layer can have proper mechanical properties, and the diaphragm prepared from the modified ethylene-acrylic ester rubber film layer is not easy to break in the use process of the sound production device, so that the use reliability of the diaphragm is effectively ensured.

According to one embodiment of the present application, the room temperature storage modulus of the modified ethylene-acrylate rubber film layer is from 0.5MPa to 35MPa. The low-density rubber diaphragm material is formed by adding inorganic hollow microspheres into the ethylene-acrylic ester polymer, the room temperature storage modulus of the modified ethylene-acrylic ester rubber film layer can be in the range of 0.5-35 MPa, and the diaphragm can be ensured to have good rebound resilience.

That is, the vibrating diaphragm prepared by adopting the modified ethylene-acrylic ester rubber film layer as a raw material has excellent damping performance and rebound resilience, the vibration system can effectively inhibit polarization phenomenon in the vibration sounding process, and the consistency of the vibration system is better. The vibration uniformity of each part of vibrating diaphragm of this application is better, has effectively reduced sound generating mechanism's distortion.

In some embodiments of the present application, the modified ethylene-acrylate rubber film layer has a hardness of 35A to 80A.

It should be noted that the sound generating device may be a speaker. The loudspeaker comprises a vibration system and a magnetic circuit system matched with the vibration system, wherein the vibration system comprises a vibrating diaphragm provided by the application, and the vibrating diaphragm can be a folded ring vibrating diaphragm or a flat vibrating diaphragm. The loudspeaker adopting the vibrating diaphragm has the advantages of good sounding effect, good durability and the like.

In some embodiments of the present application, when the hardness of the diaphragm material is controlled within a range of 35A to 80A, and the room temperature storage modulus is within a range of 0.5MPa to 35MPa, the F0 of the speaker can reach 500Hz to 1500Hz, thereby enabling the speaker to have excellent low frequency performance.

In some embodiments of the present application, the modified ethylene-acrylate rubber film layer has a dissipation factor > 0.12 at room temperature.

Specifically, the inorganic hollow microsphere has higher strength, the density of the modified ethylene-acrylic ester rubber film layer is reduced after the inorganic hollow microsphere is filled into rubber, and the hardness is properly improved. The content of the reinforcing agent of the low-density rubber is far less than that of the common rubber under the same hardness. The modified ethylene-acrylic ester rubber film layer has higher gel content, increased intermolecular entanglement and high internal friction resistance, so that the modified ethylene-acrylic ester rubber film layer has excellent damping performance. The loss factor of the vibrating diaphragm at room temperature is more than 0.12. Preferably, the modified ethylene-acrylate rubber film has a loss factor of > 0.13. Therefore, the vibrating diaphragm prepared from the vibrating diaphragm material with a higher damping value can have a lower impedance curve, the damping property of the vibrating diaphragm is improved, the polarization phenomenon can be effectively restrained by the vibration system in the vibration sounding process, and the consistency of the vibration system is better.

In addition, the loss factor can be matched with the thickness of the vibrating diaphragm, and the performance of the vibrating diaphragm can be further optimized. Generally, the higher the loss factor is, the better the damping performance of the material is, the damping performance of the vibrating diaphragm material is improved, the polarization in the vibration process is reduced, the product distortion is reduced, and the listening yield is improved. For example, the loss factor may be 0.12, 0.13, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, or 0.25, etc.

It should be noted that, the loss factor test method may be a conventional test method, for example: is obtained by dynamic mechanical test DMA measurement, measured according to ASTM D5026-15 standard, stretching the clamp, the test temperature range is-50 ℃ to 100 ℃, and the heating rate is 3 ℃/min

Further, the diaphragm of the present application has excellent damping performance, as shown in fig. 1, wherein the diaphragm may be a rectangular folded ring diaphragm. The abscissa is frequency (Hz) and the ordinate is loudness displacement (mm). And testing the edge position and the center position of the central part of the vibrating diaphragm respectively to obtain test curves of vibration displacement of different parts of the vibrating diaphragm under different frequencies.

The damping effect of the vibrating diaphragm material added with the inorganic hollow microspheres on the vibrating diaphragm is as follows:

the inorganic hollow bead is selected as a hollow glass bead, and the hollow glass bead is one of the inorganic hollow beads, and the hollow glass bead or other inorganic hollow beads can also reflect the effect of the inorganic hollow bead in the material.

As shown in fig. 1, the curves in fig. 1 are intensively distributed, which indicates that the vibration consistency of each part of the vibrating diaphragm of the sound generating device is better, the vibrating diaphragm swings less during the vibration process, and the sound quality and the listening stability are better.

According to one embodiment of the present application, the diaphragm has a density of 0.5g/cm ³ ～1g/cm ³ 。

That is, the density of the diaphragm can be controlled at 0.5g/cm by adding inorganic hollow microspheres to an ethylene-acrylic acid ester polymer to form a low density rubber diaphragm material and adjusting the addition amount of the inorganic hollow microspheres ³ ～1g/cm ³ . For example, the density of the diaphragm may be 0.5g/cm ³ 、0.7g/cm ³ 、0.8g/cm ³ 、0.9g/cm ³ Or 1g/cm ³ 。

The influence of the content of the inorganic hollow microspheres in the vibrating diaphragm material on the intermediate frequency Fr of the vibrating diaphragm is as follows:

as shown in fig. 2, by testing the mid frequency Fr of the sound emitting devices of the diaphragms with different densities, the mid frequency performance of the sound emitting device with the diaphragm gradually decreases as the density of the diaphragm increases. That is, the density of the vibrating diaphragm can be reduced and the medium frequency performance of the sound generating device can be improved by adding the vibrating diaphragm material formed by the inorganic hollow microspheres into the ethylene-acrylic ester rubber.

Wherein, it is also noted that when the low-density rubber density is low (< 0.5 g/cm) ³ ) The inorganic hollow microsphere has high content, and the prepared vibrating diaphragm has low elongation at break and strength and is easy to collapse, rupture membrane and other reliability problems. When the inorganic hollow microsphere content is low and the diaphragm density is high (> 1 g/cm) ³ ) Compared with the conventional ethylene-acrylic ester rubber diaphragm, the diaphragm prepared by the method has the advantage that the intermediate frequency Fr of the sound generating device is not obviously improved under the condition of the same thickness.

In some embodiments of the present application, the glass transition temperature of the diaphragm is less than or equal to-10 ℃.

That is, the glass transition temperature of the diaphragm can be controlled at less than or equal to-10 ℃ by adding inorganic hollow microspheres to the ethylene-acrylic acid ester polymer to form a low-density rubber diaphragm material and adjusting the addition amount of the inorganic hollow microspheres. For example, -10 ℃, -15 ℃, -20 ℃ and the like. Preferably, the glass transition temperature of the modified ethylene-acrylic ester rubber film layer can be less than or equal to-20 ℃.

Therefore, the glass transition temperature of the vibrating diaphragm is controlled to be less than or equal to minus 10 ℃, so that the vibrating diaphragm can keep a high-elasticity state at normal temperature, and the vibrating diaphragm has good rebound resilience. When the use temperature of the vibrating diaphragm is lower than 0 ℃, the vibrating diaphragm of the loudspeaker can keep good rubber elasticity all the time when in operation, so that the loudspeaker shows high tone quality. Meanwhile, the risk of damage to the loudspeaker diaphragm in a low-temperature environment is reduced, and the reliability is higher. In addition, the diaphragm with lower glass transition temperature can ensure that the diaphragm material has high modulus consistency when working higher than the glass transition temperature, and F0 of the diaphragm prepared by the diaphragm material has better stability in a full temperature range.

According to one embodiment of the present application, the additives include a cross-linking agent, a reinforcing agent, and an anti-aging agent.

Wherein the cross-linking agent is at least one of metal oxide, metal peroxide, organic oxide, organic peroxide and amine vulcanization system; the reinforcing agent is at least one of carbon black, silicon dioxide, calcium carbonate, barium sulfate, organic montmorillonite, unsaturated carboxylic acid metal salt, talcum powder, clay, mica powder, feldspar powder, sulfate, magnetic powder and diatomite; the antioxidant is at least one of antioxidant N-445, antioxidant 246, antioxidant 4010, antioxidant SP, antioxidant RD, antioxidant ODA, antioxidant OD and antioxidant WH-02.

In some embodiments of the present application, the cross-linking agent comprises 0.5wt% to 4.6wt% of the mix, the reinforcing agent comprises 5wt% to 71wt% of the mix, and the anti-aging agent comprises 0.1wt% to 5.9wt% of the mix.

Wherein the content of the cross-linking agent is 0.5 to 4.6wt percent of the rubber compound, preferably 1 to 3wt percent. The amount of the cross-linking agent directly determines the cross-linking degree, when the content of the cross-linking agent in the system is lower than 0.5wt%, the cross-linking degree of the rubber is lower, the mechanical strength is low, and the mechanical property of the material is difficult to meet the product requirement. When the content of the cross-linking agent is more than 4.6wt%, the cross-linking degree of the rubber is higher, the elongation at break of the material is lower, the toughness of the material is insufficient, and the material is easy to embrittle and break in the long-term use process.

The content of the anti-aging agent is 0.1-5.9 wt% of the rubber compound, the molecular chain is broken to generate free radicals with the extension of time in the use process of the rubber, the self aging is accelerated, and the addition of the anti-aging agent can stop the self-catalytic active free radicals generated in the rubber product. Too small addition amount cannot achieve the effect of prolonging the service life of the product, while too large addition amount is difficult to uniformly disperse because the addition amount cannot be well mutually dissolved with the elastomer, so that the mechanical property of the material is reduced, and the material is easy to separate out to the surface along with the time extension.

The content of the reinforcing agent is 5-71 wt% of the rubber compound, the reinforcing agent forms an interface with a rubber molecular chain through mutual interference, van der Waals force or hydrogen bond, when the material is stressed, the molecular chain slides on the surface of the reinforcing agent easily, but is not easy to separate from the reinforcing agent, the rubber molecule and the reinforcing agent form a strong bond capable of sliding, and the mechanical strength is increased. And the excessive reinforcing agent leads to remarkable increase of the tensile strength of the material, and the elongation at break is rapidly reduced, so that the product requirement cannot be met.

According to one embodiment of the application, the diaphragm is of a single-layer structure and is composed of a modified ethylene-acrylic ester rubber film layer.

In some embodiments of the present application, the diaphragm is a composite layer structure, and the diaphragm includes at least one modified ethylene-acrylate rubber film layer. Namely, when the vibrating diaphragm is a composite vibrating diaphragm, the composite vibrating diaphragm can comprise a layer of modified ethylene-acrylic ester rubber film layer, also can comprise a plurality of layers of modified ethylene-acrylic ester rubber film layers, wherein the layers of modified ethylene-acrylic ester rubber film layers can be adjacently arranged or can be arranged at intervals, and the specific arrangement method can be selected according to the specific design requirement of the sound generating device.

According to one embodiment of the present application, the diaphragm further comprises a film layer made of at least one of a thermoplastic elastomer, an engineering plastic, and a thermosetting elastomer.

The thermoplastic elastomer is at least one of thermoplastic polyester elastomer, thermoplastic polyurethane elastomer, thermoplastic polyamide elastomer and organic silicon elastomer, and the engineering plastic is at least one of polyether ether ketone, polyarylate, polyetherimide, polyimide, polyphenylene sulfide, polyethylene naphthalate, polyethylene terephthalate and polybutylene terephthalate; the thermosetting elasticity is at least one of natural rubber, styrene-butadiene rubber, isoprene rubber, chloroprene rubber, butyl rubber, nitrile rubber, chlorinated nitrile rubber, ethylene propylene rubber, silicone rubber, fluorosilicone rubber, fluororubber, polyurethane rubber, acrylic rubber, ethylene-vinyl acetate rubber, chlorosulfonated polyethylene rubber, epichlorohydrin rubber and polysulfide rubber.

That is, when the diaphragm is a composite diaphragm, the composite diaphragm is composed of a film layer made of at least one of a thermoplastic polyester elastomer, a thermoplastic polyurethane elastomer, a thermoplastic polyamide elastomer, and a silicone elastomer, and a modified ethylene-acrylate rubber film layer. The raw materials of the plastic polyurethane elastomer, the thermoplastic polyamide elastomer and the organosilicon elastomer can be various, and can be selected according to specific requirements. The composite diaphragm composed of the film layer made of the plastic polyurethane elastomer, the thermoplastic polyamide elastomer and the organic silicon elastomer and the modified ethylene-acrylic ester rubber film layer has excellent mechanical properties, and has higher damping value while ensuring certain mechanical strength.

In summary, according to the vibrating diaphragm of the sounding device disclosed by the embodiment of the application, the vibrating diaphragm prepared by taking the modified ethylene-acrylic ester rubber film layer as the raw material has excellent damping performance and rebound resilience, the vibration system can effectively inhibit polarization phenomenon in the vibrating sounding process, the consistency of the vibration system is better, the distortion of the sounding device is effectively reduced, and the density of the vibrating diaphragm is reduced by controlling the addition amount of the inorganic hollow microspheres, so that the vibrating diaphragm has excellent ageing resistance and mucosa resistance, and the intermediate frequency performance and the service performance of the sounding device are improved.

It should be noted that, the diaphragm provided in the present application may be formed into any sound generating device, for example, the following typical sound generating devices: the vibration system comprises a vibrating diaphragm and a voice coil combined on one side of the vibrating diaphragm. When the sounding device works, the voice coil can vibrate up and down under the action of the magnetic field force of the magnetic circuit system after the voice coil is electrified so as to drive the vibrating diaphragm to vibrate, and sounding can be carried out when the vibrating diaphragm vibrates.

According to the sound production device of the second aspect of the embodiment of the application, the sound production device comprises a vibration system and a magnetic circuit system matched with the vibration system, the vibration system comprises a vibrating diaphragm and a voice coil combined on one side of the vibrating diaphragm, the magnetic circuit system drives the voice coil to vibrate so as to drive the vibrating diaphragm to produce sound, and the vibrating diaphragm is the vibrating diaphragm of the embodiment. Specifically, when sound generating mechanism during operation, the voice coil is under the effect of magnetic field force of magnetic circuit after the voice coil loudspeaker voice coil is circular telegram, and the voice coil loudspeaker voice coil can vibrate in order to drive the vibrating diaphragm vibration from top to bottom, can carry out the sound production when the vibrating diaphragm vibrates.

As shown in fig. 3 and 4, the sound generating device includes a diaphragm 15 made by the embodiments described above, the diaphragm 15 may be composed of a folded ring portion 151 and a spherical top portion 152, and the modified ethylene-acrylic ester rubber film layer may be applied to the folded ring portion of the diaphragm. Those skilled in the art can make corresponding adjustments according to the actual product requirements, for example, the folded ring portion 151 protrudes toward the voice coil 11, the top portion 152 is located on the lower surface of the folded ring portion 151, and a centering support plate is added in the vibration system.

As shown in fig. 5 and 6, the sound generating device 100 according to the third aspect of the present application includes a housing 10, and a magnetic circuit 14 and a vibration system disposed in the housing 10, where the vibration system includes a voice coil 11, a first diaphragm 12 and a second diaphragm 13, the top of the voice coil 11 is connected to the first diaphragm 12, the magnetic circuit 14 drives the voice coil 11 to vibrate to drive the first diaphragm 12 to generate sound, two ends of the second diaphragm 13 are respectively connected to the housing 10 and the bottom of the voice coil 11, and the second diaphragm 13 is a diaphragm of the above embodiment.

That is, the sound generating apparatus 100 according to the embodiment of the present application may further include two diaphragms prepared by the above embodiment of the present application, namely, the first diaphragm 12 and the second diaphragm 13, the first diaphragm 12 may be used for vibration sound generation, and the second diaphragm 13 may be used for balancing the vibration of the voice coil 11. Specifically, when the sound generating device 100 works, the voice coil 11 can vibrate up and down under the action of the magnetic field force of the magnetic circuit system 14 after the voice coil 11 is electrified to drive the first diaphragm 12 to vibrate, and sound can be generated when the first diaphragm 12 vibrates. The second vibrating diaphragm 13 can also vibrate up and down along with the voice coil 11, and as the two ends of the second vibrating diaphragm 13 are respectively connected with the bottom of the shell 10 and the bottom of the voice coil 11, the second vibrating diaphragm 13 can balance the vibration of the voice coil 11, and can prevent the voice coil 11 from generating polarization, thereby improving the sounding effect of the sounding device 100.

It should be noted that, the diaphragms of the embodiments described herein may be used for the first diaphragm 12 and the second diaphragm 13 at the same time, or one of the first diaphragm 12 and the second diaphragm 13 may be used for the diaphragms of the embodiments described herein, which is not particularly limited in this application.

The diaphragm of the sound generating device of the present application will be specifically described with reference to specific embodiments.

Comparative example one

The formula is as follows according to the parts by mass: 100 parts of ethylene-acrylic ester polymer (AEM); 30 parts of a reinforcing agent; 2 parts of chemical inhibitor; 2 parts of vulcanizing agent; 2 parts of vulcanization accelerator. And (3) mixing and then carrying out a crosslinking reaction to form a vibrating diaphragm material, and assembling the vibrating diaphragm material into a product.

Example 1

The formula is as follows according to the parts by mass: 100 parts of ethylene-acrylic ester polymer (AEM); 30 parts of a reinforcing agent; 30 parts of hollow glass beads; 2 parts of chemical inhibitor; 2 parts of vulcanizing agent; 2 parts of vulcanization accelerator. And (3) mixing and then carrying out a crosslinking reaction to form a vibrating diaphragm material, and assembling the vibrating diaphragm material into a product.

Table four

The test indexes are as follows: tensile strength, elongation at break, loss factor, density and surface contact angle

As shown in table four, the performance test results of the diaphragms of comparative example one and example one are shown in table four, and show the influence of the addition of the inorganic hollow microspheres on tensile strength, elongation at break, loss factor, density and surface contact angle.

As can be seen from Table IV, the tensile strength and the loss factor of the modified ethylene-acrylic ester rubber film layer are obviously increased due to the addition of the hollow glass beads. That is, by adding the inorganic hollow microspheres, the vibrating diaphragm has excellent damping performance and rebound resilience, the vibration system can effectively inhibit polarization phenomenon in the vibration sounding process, the consistency of the vibration system is better, and the distortion of the sounding device is effectively reduced.

Further, as the hollow glass beads have lower density, the density of the added modified ethylene-acrylic ester rubber film layer is obviously reduced to 0.923g/cm ³ . Moreover, the surface contact angle between the rubber film layer and water in the embodiment of the present application is 83 °, and the surface contact angle between the rubber film layer and water in the comparative example one is 68 °, so that the rubber film layer in the embodiment is easier to release from the mold than the rubber film layer without adding the inorganic hollow microspheres.

Although specific embodiments of the present application have been described in detail by way of example, it will be appreciated by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present application. It will be appreciated by those skilled in the art that modifications may be made to the above embodiments without departing from the scope and spirit of the present application. The scope of the application is defined by the appended claims.

Claims

1. The vibrating diaphragm of the sound production device is characterized by comprising at least one modified ethylene-acrylic ester rubber film layer, wherein the modified ethylene-acrylic ester rubber film layer is prepared by mixing inorganic hollow microspheres, an additive and an ethylene-acrylic ester polymer to form a rubber compound and then carrying out a crosslinking reaction;

wherein the particle size of the inorganic hollow microspheres is 1-60 mu m, and the distribution density of the inorganic hollow microspheres in the modified ethylene-acrylic ester rubber film layer is 0.15g/cm ³ ～0.9g/cm ³ The surface contact angle between the modified ethylene-acrylic ester rubber film layer and water is more than or equal to 70 degrees.

2. The diaphragm of the sound generating device according to claim 1, wherein the content of the inorganic hollow microspheres is 5-48 wt% of the total amount of the rubber compound.

3. The diaphragm of the sound generating device according to claim 1, wherein the tensile strength of the modified ethylene-acrylic ester rubber film layer is reduced by less than or equal to 46% and the elongation at break is reduced by less than or equal to 71% after the modified ethylene-acrylic ester rubber film layer is aged for 168 hours under 180 ℃ hot air.

4. The diaphragm of the sound generating apparatus according to claim 1, wherein the compressive strength of the inorganic hollow microsphere is not less than 10MPa.

5. The diaphragm of the sound generating device according to claim 1, wherein the tensile strength of the modified ethylene-acrylic ester rubber film layer is not less than 5MPa.

6. The sound emitting device diaphragm of claim 1, wherein the modified ethylene-acrylate rubber film layer has a dissipation factor > 0.12 at room temperature.

7. The sound emitting device diaphragm of claim 1, wherein the modified ethylene-acrylate rubber layer has a density of 0.5g/cm ³ ～1.1g/cm ³ 。

8. The diaphragm of the sound generating apparatus of claim 1, wherein the glass transition temperature of the modified ethylene-acrylate rubber film layer is less than or equal to-10 ℃.

9. The diaphragm of the sound generating apparatus of claim 1, wherein the additive comprises a cross-linking agent, a reinforcing agent and an anti-aging agent,

wherein the cross-linking agent is at least one of metal oxide, metal peroxide, organic oxide, organic peroxide and amine vulcanization system; the reinforcing agent is at least one of carbon black, silicon dioxide, calcium carbonate, barium sulfate, organic montmorillonite, unsaturated carboxylic acid metal salt, talcum powder, clay, mica powder, feldspar powder, sulfate, magnetic powder and diatomite; the antioxidant is at least one of an antioxidant N-445, an antioxidant 246, an antioxidant 4010, an antioxidant SP, an antioxidant RD, an antioxidant ODA, an antioxidant OD and an antioxidant WH-02.

10. The sound emitting device diaphragm of claim 9, wherein the cross-linking agent is present in an amount of 0.5wt% to 4.6wt% of the rubber compound, the reinforcing agent is present in an amount of 5wt% to 71wt% of the rubber compound, and the anti-aging agent is present in an amount of 0.1wt% to 5.9wt% of the rubber compound.

11. The diaphragm of the sound generating apparatus according to claim 1, wherein the diaphragm has a single-layer structure, and the diaphragm is composed of one layer of the modified ethylene-acrylic ester rubber film.

12. The sound generating apparatus diaphragm of claim 1, wherein the diaphragm is a composite layer structure, and the diaphragm further comprises a film layer made of at least one of a thermoplastic elastomer, an engineering plastic, and a thermosetting elastomer.

13. The utility model provides a sound generating device, its characterized in that includes vibration system and with vibration system matched with magnetic circuit system, vibration system includes the vibrating diaphragm and combines the voice coil loudspeaker voice coil in vibrating diaphragm one side, magnetic circuit system drives the voice coil loudspeaker voice coil vibrates in order to drive the vibrating diaphragm sound production, the vibrating diaphragm is the vibrating diaphragm of any one of claims 1-12.

14. The utility model provides a sound generating device, its characterized in that includes the casing and establishes magnetic circuit and vibration system in the casing, vibration system includes voice coil loudspeaker voice coil, first vibrating diaphragm and second vibrating diaphragm, the top of voice coil loudspeaker voice coil with first vibrating diaphragm links to each other, magnetic circuit drives the voice coil loudspeaker voice coil vibrates in order to drive first vibrating diaphragm sound production, the both ends of second vibrating diaphragm respectively with the casing with the bottom of voice coil loudspeaker voice coil links to each other, the second vibrating diaphragm is the vibrating diaphragm of any one of claims 1-12.