WO2021082248A1

WO2021082248A1 - Diaphragm for miniature sound generating device and miniature sound generating device

Info

Publication number: WO2021082248A1
Application number: PCT/CN2019/128166
Authority: WO
Inventors: 彭威锋; 凌风光; 李春; 刘春发
Original assignee: 歌尔股份有限公司
Priority date: 2019-10-31
Filing date: 2019-12-25
Publication date: 2021-05-06
Also published as: CN110708639A; CN110708639B

Abstract

Disclosed in the present invention are a diaphragm for a miniature sound generating device, and a miniature sound generating device. The diaphragm comprises at least one elastomer layer, the elastomer layer being made of chloroprene rubber; the molecular chain structure of the chloroprene rubber comprises isomers of butadiene chloride; and the molecular weight of the chloroprene rubber is from 10,000 to 500,000. The diaphragm provided by the present invention has excellent elasticity and fatigue resistance.

Description

Vibration diaphragm for miniature sounding device and miniature sounding device

Technical field

The present invention relates to the technical field of acoustic devices. Specifically, the present invention relates to a diaphragm for a miniature sounding device and a miniature sounding device.

Background technique

In recent years, with the rapid development of small electronic devices such as mobile phones and tablet computers, electronic devices need to be equipped with smaller and better performance micro-sounding devices. The diaphragm is one of the very important parts in the miniature sound device.

Most of the existing diaphragms for miniature sound emitting devices are made of high-modulus engineering plastic materials, such as PEEK, PAR, PEI, PI, etc. Although these engineering plastic materials have good temperature resistance, the material has poor resilience, and the product is prone to film folding and cannot play a role in waterproofing. In particular, the diaphragm made of these engineering plastic materials has poor fatigue resistance and resilience. The diaphragm cannot always maintain excellent elasticity during long-term vibration, which can easily cause poor listening and make the sound device acoustic Performance is not good. In addition, the existing diaphragm cannot be used normally under extreme conditions, and has many defects.

Therefore, it is necessary to provide a new technical solution to solve the above technical problems.

Summary of the invention

An object of the present invention is to provide a new technical solution for the diaphragm of the miniature sounding device and the miniature sounding device.

According to one aspect of the present invention, there is provided a diaphragm for a miniature sounding device, the diaphragm including at least one elastomer layer, wherein the elastomer layer is made of neoprene;

The chloroprene rubber molecular chain structure includes isomers of chlorinated butadiene;

The molecular weight of the chloroprene rubber is 10,000 to 500,000.

Optionally, the isomers of chlorinated butadiene include the following components:

Trans-1,4-structure, the content is 70%-95%;

Cis-1,4-structure, the content is 2%-25%;

1, 2 structure, the content is 0.1%-5%; and

3,4 structure, content is 0.1%-5%;

Wherein, the molecular structural formula of the trans-1,4-structure is as follows:

The molecular structural formula of the cis-1,4-structure is as follows:

The molecular structural formula of the 1, 2 structure is as follows:

The molecular structural formula of the 3, 4 structure is as follows:

Optionally, the chloroprene rubber is mixed with an inorganic filler reinforcing agent, and the inorganic filler reinforcing agent adopts at least one of carbon black, white carbon black, nano titanium dioxide, talc, precipitated calcium carbonate, and barium sulfate. The content of the inorganic filler reinforcing agent is 15%-90% of the total amount of the chloroprene rubber.

Optionally, the content of the inorganic filler reinforcing agent is 30%-70% of the total amount of the chloroprene rubber.

Optionally, the chloroprene rubber is mixed with an anti-aging agent, and the anti-aging agent adopts anti-aging agent N-445, anti-aging agent 246, anti-aging agent 4010, anti-aging agent SP, anti-aging agent RD, anti-aging agent ODA, anti-aging agent OD, At least one of the antioxidants WH-02, and the content of the antioxidants is 0.5%-10% of the total amount of the chloroprene rubber.

Optionally, the content of the antioxidant is 1% to 5% of the total amount of the chloroprene rubber.

Optionally, the chloroprene rubber is mixed with a plasticizer, and the plasticizer is an aliphatic dibasic acid ester plasticizer, a phthalate ester plasticizer, or a benzene polyester plasticizer. At least one of benzoate plasticizers, polyol ester plasticizers, chlorinated hydrocarbon plasticizers, epoxy plasticizers, citrate plasticizers, and polyester plasticizers The content of the plasticizer is 1%-10% of the total amount of the chloroprene rubber.

Optionally, the content of the plasticizer is 3%-7% of the total chloroprene rubber.

Optionally, the chloroprene rubber is mixed with an internal mold release agent, and the internal mold release agent is stearic acid, stearate, stearylamine, alkyl phosphate, α-octadecyl -at least one of ω-hydroxypolyoxyethylene phosphate, the content of the internal release agent is 0.5% to 5% of the total amount of the chloroprene rubber.

Optionally, the content of the internal release agent is 1% to 3% of the total amount of the chloroprene rubber.

Optionally, the chloroprene rubber is mixed with a vulcanizing agent, and the vulcanizing agent includes a metal oxide system vulcanizing agent and a thiourea vulcanizing agent.

Optionally, the metal oxide system vulcanizing agent is magnesium oxide, zinc oxide or calcium oxide, and the content of the metal oxide system vulcanizing agent is 2%-10% of the total amount of the chloroprene rubber;

The content of the thiourea vulcanizing agent is 0.5% to 5% of the total amount of the chloroprene rubber.

Optionally, the diaphragm is a single-layer diaphragm, and the single-layer diaphragm is composed of a layer of neoprene; or,

The diaphragm is a composite diaphragm, and the composite diaphragm includes two, three, four or five diaphragm layers, and the composite diaphragm includes at least one neoprene diaphragm layer.

Optionally, the thickness of the chloroprene rubber film layer is 10 μm-200 μm.

Optionally, the thickness of the chloroprene rubber film layer is 30 μm-120 μm.

Optionally, the chloroprene rubber has a hardness in the range of 30-95A.

Optionally, the glass transition temperature of the chloroprene rubber ranges from -50 to 0°C.

Optionally, the loss factor of the chloroprene rubber at room temperature is greater than 0.06.

Optionally, the elongation at break of the chloroprene rubber is greater than 100%.

According to another aspect of the present invention, a miniature sound emitting device is provided. The miniature sounding device includes a sounding device main body and the above-mentioned diaphragm. The diaphragm is arranged on the sounding device main body, and the diaphragm is configured to vibrate and produce sound.

The inventor of the present invention found that in the prior art, the resilience and fatigue resistance of the diaphragm are relatively poor, which will affect the acoustic performance of the sound device. Therefore, the technical task to be achieved or the technical problem to be solved by the present invention has never been thought of or anticipated by those skilled in the art, so the present invention is a new technical solution.

The beneficial effects of the present invention are: the present invention discloses a diaphragm made of neoprene material. The diaphragm has good fatigue resistance and elasticity, can work for a long time under extreme conditions, and can maintain Good resilience and reliability. Therefore, the sound generating device can be used in extremely harsh environments while maintaining good acoustic performance.

Through the following detailed description of exemplary embodiments of the present invention with reference to the accompanying drawings, other features and advantages of the present invention will become clear.

Description of the drawings

The drawings incorporated in the specification and constituting a part of the specification illustrate the embodiments of the present invention, and together with the description are used to explain the principle of the present invention.

FIG. 1 is a comparison diagram of the total harmonic distortion test curve of the diaphragm provided by the present invention and the existing conventional diaphragm.

Fig. 2 is a test curve of the vibration displacement of different parts of the diaphragm of the sound generating device at different frequencies according to an embodiment of the present invention.

Fig. 3 is a test curve of the vibration displacement of different parts of the existing diaphragm at different frequencies.

Figure 4 shows the impedance curves of diaphragms with different hardnesses.

Fig. 5 is a comparison diagram of the test curves of loudness at different frequencies between the diaphragm provided by the present invention and the existing conventional diaphragm.

Detailed ways

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

The following description of at least one exemplary embodiment is actually only illustrative, and in no way serves as any limitation to the present invention and its application or use.

The technologies, methods, and equipment known to those of ordinary skill in the relevant fields may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be regarded as part of the specification.

In all examples shown and discussed herein, any specific value should be interpreted as merely exemplary, rather than as a limitation. Therefore, other examples of the exemplary embodiment may have different values.

It should be noted that similar reference numerals and letters indicate similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

According to an embodiment of the present invention, a diaphragm of a sound emitting device is provided. The diaphragm includes at least one elastomer layer, and the elastomer layer is made of neoprene. The diaphragm can be used in a sound emitting device such as a loudspeaker, especially in a miniature sound emitting device.

The molecular weight of the chloroprene rubber is relatively large, and can reach 10,000 to 500,000.

The molecular chain structure of the chloroprene rubber includes isomers of chlorinated butadiene with different contents. Specifically, the isomers of chlorinated butadiene specifically include:

Trans-1,4-structure, the content is 70%-95%;

Cis-1,4-structure, the content is 2%-25%;

1, 2 structure, the content is 0.1%-5%; and

3,4 structure, the content is 0.1%-5%.

The molecular structural formula of the trans-1,4-structure is as follows:

The molecular structural formula of the cis-1,4-structure is as follows:

The molecular structural formula of the 1, 2 structure is as follows:

The molecular structural formula of the 3, 4 structure is as follows:

In particular, chloroprene rubber has a unique molecular structure and is called special rubber. The molecular structure of chloroprene rubber is mostly composed of linear α-polymers, the molecular chain structure is regular, and there are chlorine atom polar groups on the molecular chain, which can increase the intermolecular force. Therefore, under the action of external force, the chloroprene rubber is easy to stretch and crystallize, making the molecules not easy to slip off. In addition, the molecular weight of chloroprene rubber is also relatively large, which can reach 10,000 to 500,000, and the molecular weight distribution is relatively uniform. Therefore, the physical and mechanical strength of chloroprene rubber is very high, which is not much different from natural rubber performance, and is better than butyl rubber. Benzene rubber and nitrile rubber.

Due to the presence of polar chlorine atoms in the neoprene molecule, neoprene emits hydrogen chloride gas that has a fire extinguishing effect at high temperatures. Therefore, chloroprene rubber also has excellent flame retardant properties compared to other rubbers. In addition, the chlorine atoms on the molecular chain of chloroprene rubber protect the carbon-carbon double bond, which makes the chloroprene rubber have good stability.

Chlorine atoms also bring great polarity to neoprene. Therefore, neoprene is a highly polymerized and highly cohesive polar rubber. Since the surface of the bonded material is usually polar, chloroprene rubber has a good affinity with the adhesive, which makes the diaphragm made of chloroprene rubber have higher reliability during bonding and molding.

The diaphragm provided by the present invention is made of chloroprene rubber material, so that the diaphragm has high elasticity and excellent fatigue resistance. Moreover, it can work for a long time under extreme conditions, and can maintain good resilience and reliability. Therefore, the sound generating device can be used in extremely harsh environments while maintaining good acoustic performance.

Optionally, the chloroprene rubber may be mixed with an inorganic filler reinforcing agent. The inorganic filler reinforcing agent includes at least one of carbon black, white carbon black, nano titanium dioxide, talc, precipitated calcium carbonate, and barium sulfate. And, when the mass fraction of the chloroprene rubber itself is 100 parts, the mass parts of the inorganic filler reinforcing agent itself is 15-90 parts, that is, the content of the inorganic filler reinforcing agent is the 15%-90% of the total amount of chloroprene rubber.

The surface of the inorganic filler reinforcing agent has groups such as hydrogen, carboxyl group, lactone group, free radical, quinone group, etc., which can undergo reactions such as substitution, reduction, and oxidation. After mixing the inorganic filler reinforcing agent into the neoprene rubber, due to the strong interaction between the inorganic filler reinforcing agent and the molecular interface of the neoprene rubber, when the material is stressed, the molecular chain is easier to be on the surface of the inorganic filler reinforcing agent particles. It slides up, but it is not easy to separate from the particles of the inorganic filler reinforcing agent. The chloroprene rubber and the inorganic filler reinforcing agent particles form a strong bond that can slide, and the mechanical strength is increased. In addition, the particle size of the inorganic filler reinforcing agent, the structure of the filler and the surface activity of the filler are the primary factors for investigating rubber fillers. These three factors generally depend on each other. The smaller the particle size of the inorganic filler reinforcing agent, the larger the specific surface area of the corresponding inorganic filler reinforcing agent; the larger the specific surface area of the inorganic filler reinforcing agent, the corresponding The surface activity is stronger.

Taking carbon black as an example, carbon black is mainly composed of carbon elements, and its proportion reaches 95%-99%, which belongs to the graphite crystal type. Carbon black is an amorphous structure, and particles form aggregates through physical and chemical bonding with each other. The primary structure of carbon black is composed of aggregates, and there are van der Waals forces or hydrogen bonds between the aggregates, which can aggregate into a spatial network structure, that is, the secondary structure of carbon black. The surface of carbon black has hydrogen, carboxyl, lactone, free radical, quinone and other groups that can undergo substitution, reduction, oxidation, etc. When it is added to neoprene, because the surface of carbon black and the molecular interface of neoprene The strong interaction between the material, the molecular chain is easier to slide on the surface of the carbon black when the material is stressed, but it is not easy to separate from the carbon black. Neoprene and carbon black form a strong bond that can slide, making the neoprene The mechanical strength of rubber increases.

Taking the selection of carbon black as an inorganic filler reinforcing agent as an example, when the mass fraction of carbon black is 10, the mechanical strength and elongation at break of the neoprene rubber material are relatively small. This is due to the small amount of carbon black. It is unevenly dispersed in the matrix, and it is difficult to achieve a reinforcing effect. With the increase of carbon black addition, the mechanical strength of the neoprene rubber material can be increased, while the elongation at break gradually decreases.

In one embodiment, when the mass parts of the chloroprene rubber itself is 100, preferably, the mass parts of the inorganic filler reinforcing agent itself is 30-70 parts, that is, the inorganic filler When the content of the filler reinforcing agent is 30%-70% of the total amount of the chloroprene rubber, it can better meet the requirements of the present invention for the performance of the diaphragm. Of course, those skilled in the art can flexibly adjust according to specific needs, and there is no limitation on this.

Optionally, an anti-aging agent may be mixed in the chloroprene rubber. The antioxidant can be, for example, at least one of antioxidant N-445, antioxidant 246, antioxidant 4010, antioxidant SP, antioxidant RD, antioxidant ODA, antioxidant OD, and antioxidant WH-02. And, when the mass fraction of the chloroprene rubber itself is 100 parts, the mass parts of the antioxidant itself is 0.5-10 parts, that is, the content of the antioxidant is the total amount of the chloroprene rubber 0.5%-10%.

During the use of chloroprene rubber, with the passage of time, due to the long-term influence of oxygen and ultraviolet light and other factors, the molecular chain of chloroprene rubber will gradually break, generating free radicals, and accelerating its own aging. The phenomenon is the natural aging of neoprene. In the present invention, by mixing the anti-aging agent in the chloroprene rubber, the autocatalytically active free radicals generated in the chloroprene rubber can be prevented or stopped or slowed down. It should be noted that if the amount of anti-aging agent added is too small, the effect of extending the service life of neoprene may not be achieved. However, if the amount of anti-aging agent added is too large, it is difficult for the anti-aging agent to be fully miscible with the neoprene, and it is difficult to uniformly disperse it. At this time, the mechanical properties of the neoprene may decrease. Therefore, when the mass parts of the chloroprene rubber is 100 parts, the mass parts of the antioxidant itself can be selected in the range of 0.5-10 parts. Preferably, the mass parts of the antioxidant itself is 1 to 5 parts, that is, the content of the antioxidant is 1% to 5% of the total amount of the chloroprene rubber. Of course, those skilled in the art can flexibly adjust according to specific needs, and there is no limitation on this.

Optionally, the chloroprene rubber may be mixed with a plasticizer. The plasticizer adopts aliphatic dibasic acid ester plasticizers, phthalate ester plasticizers (for example, including phthalate esters and terephthalate esters), and benzene polyacid esters plasticizers. Plasticizers, benzoate plasticizers, polyol ester plasticizers, chlorinated hydrocarbon plasticizers, epoxy plasticizers, citrate plasticizers, and polyester plasticizers At least one.

The molecule of the plasticizer is much smaller than the molecular chain of neoprene. Therefore, after the addition of the plasticizer molecule, it can move in the molecule of neoprene, that is, it can easily provide the space required for segment activity and reduce The glass transition temperature of the material increases the cold resistance of the material and improves the processing performance of the material. However, excessive plasticizer will precipitate from the inside of the material, which will reduce the mechanical properties of the material.

In one embodiment, when the mass parts of the chloroprene rubber itself is 100 parts, optionally, the mass parts of the plasticizer itself is 1-10 parts, that is, the plasticizer The content of the agent is 1%-10% of the total amount of the chloroprene rubber. In fact, as the amount of plasticizer increases, the glass transition temperature of the neoprene material decreases, but correspondingly, the tensile strength of the neoprene material will also decrease. In addition, excessive plasticizers will also precipitate from the inside of the neoprene rubber material, reducing the mechanical properties of the neoprene rubber material. When the mass parts of the plasticizer itself meets the above range, it can be ensured that the performance of the neoprene rubber can meet the performance requirements of the diaphragm. Preferably, the mass parts of the plasticizer itself is 3-7 parts, that is, the content of the plasticizer is 3%-7% of the total amount of the chloroprene rubber. Of course, those skilled in the art can flexibly adjust according to specific needs, and there is no limitation on this.

Optionally, the chloroprene rubber may be mixed with an internal mold release agent. The internal mold release agent uses at least one of stearic acid, stearate, stearylamine, alkyl phosphate, and α-octadecyl-ω-hydroxypolyoxyethylene phosphate. In the injection molding process of neoprene, there may be process problems such as sticking rollers and sticking molds. The invention improves the processing performance of the chloroprene rubber by adding an internal release agent to the rubber compound.

The release ability of chloroprene rubber is related to the mixing amount of the internal release agent. Specifically: If the mixing amount of the internal release agent is small, the molding state of the neoprene is good, but the release ability is poor, and it is difficult to improve the mucosal problem. If the mixing amount of the internal release agent is too large, although the release performance of the chloroprene rubber is significantly improved, the formed chloroprene rubber is prone to the problem of the internal release agent being deposited and accumulated on the surface of the mold, contaminating the mold. In the embodiment of the present invention, in the case where the mass parts of the chloroprene rubber is 100 parts, the mass parts of the internal mold release agent itself can be selected to be 0.5-5 parts, that is, the internal mold release The content of the agent is 0.5% to 5% of the total amount of the chloroprene rubber. Preferably, the mass parts of the internal mold release agent itself is 1-3 parts, that is, the content of the internal mold release agent is 1% to 3% of the total amount of the chloroprene rubber, and the chlorine formed at this time Butadiene rubber is in good molding state, and there is little residue after molding. Of course, those skilled in the art can flexibly adjust according to specific needs, and there is no limitation on this.

Optionally, the chloroprene rubber may be mixed with a vulcanizing agent. The vulcanizing agent includes a metal oxide system vulcanizing agent and a thiourea vulcanizing agent.

The metal oxide system vulcanizing agent can be magnesium oxide, zinc oxide or calcium oxide. In addition, the content of the metal oxide system vulcanizing agent is 2%-10% of the total amount of the chloroprene rubber. It should be noted that in addition to the metal oxide system vulcanizing agent that needs to be mixed into the neoprene rubber, a certain amount of thiourea vulcanizing agent needs to be mixed. The content of the thiourea vulcanizing agent is 0.5% to 5% of the total amount of the chloroprene rubber.

Optionally, the glass transition temperature of the diaphragm is in the range of -50°C to 0°C. Chloroprene rubber itself has a higher molecular weight, and its molecular chain is more flexible, and has better low temperature resistance. When the diaphragm satisfies the above glass transition temperature range, the diaphragm of the sound device can maintain a high elastic state at room temperature and has good resilience. In a certain range, the lower the glass transition temperature, the diaphragm can work normally at a lower temperature. When the thickness of the diaphragm is constant, the lower the glass transition temperature, the lower the resonance frequency F0 of the assembled sound device.

In one embodiment, the glass transition temperature of the diaphragm provided by the present invention is -50°C to 0°C, preferably -30°C to 0°C. The diaphragm can not only maintain a high elastic state at room temperature, but also has good resilience. More importantly, even when the temperature is below 0°C, the diaphragm can still maintain good rubber elasticity when working, so that the sound device exhibits a higher sound quality. At the same time, the risk of diaphragm damage in a low temperature environment is reduced, and the reliability is higher.

The molecular chain of neoprene is relatively soft, which gives neoprene excellent toughness. The diaphragm made of neoprene has a breaking elongation greater than 100%. Preferably, the elongation at break of the diaphragm is greater than 150%. The diaphragm of the present invention has a relatively high elongation at break, which makes the diaphragm less likely to have reliability problems such as membrane rupture when used in a sound generating device.

Under the same stress, the strain of the diaphragm provided by the embodiment of the present invention is significantly greater than that of the PEEK diaphragm in the prior art. This indicates that the Young's modulus of the diaphragm provided by the embodiment of the present invention is significantly smaller than that of the PEEK diaphragm in the prior art.

In addition, the PEEK diaphragm of the prior art has an obvious yield point, which is about 0.4-0.5% strain. However, the speaker diaphragm provided by the present invention does not have a yield point. This shows that the diaphragm provided by the present invention has a wider elastic area and has excellent resilience performance.

The diaphragm made of neoprene material has good flexibility. For example, its elongation at break is ≥100%. Among them, the molecular chain of chloroprene rubber has a very important influence on the elongation at break, and those skilled in the art can choose according to actual needs. This makes the vibration displacement of the diaphragm of the sound device larger and louder. And the reliability and durability are good. The better the flexibility of the neoprene material and the greater the elongation at break, the stronger the ability of the diaphragm to resist damage. When the diaphragm is vibrating in a state of large amplitude, the neoprene material produces a relatively large strain, and there is a risk of membrane folding, membrane cracking or membrane rupture when vibrating for a long time. The diaphragm of the present invention using neoprene as the base material has good flexibility and reduces the risk of damage to the diaphragm. The higher the elongation at break, the lower the breakage rate of the diaphragm in long-term use.

Compared with engineering plastics, the chloroprene rubber provided by the present invention has a wider elastic area. When the strain of the diaphragm occurs in this area, after the external force is removed, the diaphragm has excellent resilience. Correspondingly, during the vibration process of the diaphragm, there is less rocking vibration, and the sound quality and listening stability are better.

As shown in Fig. 1, the diaphragm provided by the present invention has a lower THD (total harmonic distortion) compared to the PEEK diaphragm of the prior art. This shows that the diaphragm provided by the present invention has more excellent anti-polarization ability and better sound quality.

The diaphragm provided by the invention is in a highly elastic state at room temperature, the molecular chain is easy to move, the friction between the molecules is large, and the damping performance is better. Optionally, at room temperature, the loss factor of the diaphragm is greater than 0.06. Excellent damping performance enables the diaphragm to have lower impedance. The damping of the diaphragm is improved, the ability of the vibration system of the sound device to suppress the polarization phenomenon during the vibration process is enhanced, and the vibration consistency is good. However, the damping of the existing diaphragm made of engineering plastics is low, the loss factor is usually less than 0.01, and the damping is small.

Preferably, the loss factor of the diaphragm provided by the present invention is greater than 0.1.

Fig. 2 is a test curve of the vibration displacement of different parts of the diaphragm of the sound generating device at different frequencies according to an embodiment of the present invention. Fig. 3 is a test curve of the vibration displacement of different parts of the existing diaphragm at different frequencies.

Wherein, the diaphragm is a rectangular folded ring diaphragm. The abscissa is the frequency (Hz), and the ordinate is the loudness displacement (mm). Take points at the edge position and the center position of the center of the diaphragm for testing.

It can be seen that the curves in Fig. 2 are more concentrated, while the curves in Fig. 3 are more scattered. This indicates that the vibration consistency of the various parts of the diaphragm provided by the embodiment of the present invention is better, during the vibration process, the vibration of the diaphragm is less, and the sound quality and listening stability are more excellent.

Optionally, the vibration diaphragm provided by the present invention has a Shore hardness range of 30-95A. The resonance frequency F0 of the sound generating device is proportional to the modulus, hardness, and thickness of the diaphragm, while for neoprene materials, the modulus is proportional to the hardness. Therefore, hardness can be used to reflect the modulus of the diaphragm.

The strength and hardness of the neoprene rubber material can be adjusted by the inorganic filler reinforcing agent. In general, the higher the strength and hardness of the neoprene material, the higher the F0 of the prepared diaphragm. Correspondingly, the loudness of the sounding device will be reduced and the bass performance will be worse. Figure 4 shows the impedance curves of the diaphragm with the same thickness and different hardness. It can be seen from Fig. 4 that as the hardness increases, the resonance frequency F0 of the sound emitting device increases sharply.

The diaphragm of the sound emitting device provided by the present invention may be, for example, a folded ring diaphragm or a flat diaphragm. The resonance frequency F0 of the sounding device is proportional to the Young's modulus and thickness of the diaphragm. The change of F0 can be achieved by changing the thickness and Young's modulus of the diaphragm of the sounding device. The specific adjustment principle is as follows:

Among them, Mms is the equivalent vibration mass of the sounding device, and Cms is the equivalent compliance of the sounding device:

Among them, C _m1 is the elastic wave compliance, and C _m2 is the diaphragm compliance. When designing without elastic waves, the equivalent compliance of the sounding device is the diaphragm compliance:

Among them, W is the total width of the folded ring of the diaphragm, t is the thickness of the diaphragm; dvc is the outer diameter of the diaphragm and voice coil; E is the Young's modulus of the diaphragm material; u is the Poisson of the diaphragm material ratio.

It can be seen that the resonance frequency F0 of the sound emitting device is proportional to the modulus and thickness of the diaphragm. The modulus of the diaphragm is directly proportional to its hardness. Therefore, hardness can be used instead of its modulus. In order to obtain full bass and comfortable hearing, while the sound device has a lower resonance frequency F0, the diaphragm should have sufficient rigidity and damping. Those skilled in the art can adjust the size of F0 by adjusting the hardness and thickness of the speaker diaphragm.

The Shore hardness of the diaphragm is preferably 30-80A, and the thickness of the diaphragm is 30-120 μm. Within the above-mentioned preferred range, the resonance frequency F0 of the sound generating device can reach 150-1500 Hz. The low frequency performance of the sound device is excellent.

Optionally, the diaphragm provided by the present invention may be a single-layer structure or a multi-layer composite diaphragm. Wherein, the single-layer diaphragm is a diaphragm composed of a layer of neoprene rubber film. The composite diaphragm is a diaphragm formed by successively stacking multiple neoprene rubber membrane layers. Alternatively, the composite diaphragm may include at least one layer of chloroprene rubber diaphragm, and the chloroprene rubber diaphragm is bonded and compounded with a diaphragm made of other materials to form a composite diaphragm made of multiple materials. In addition, the multiple membrane layers can be combined by hot pressing or the like to form the above-mentioned composite diaphragm. The composite diaphragm may be a two-layer, three-layer, four-layer or five-layer composite diaphragm, which is not limited in the present invention. At least one membrane layer in the composite diaphragm is a neoprene membrane layer made of neoprene provided by the present invention.

For the neoprene film layer, the thickness may be 10-200 μm, preferably 30-120 μm. When the thickness of the neoprene film layer is within this range, it can better meet the performance requirements and assembly space requirements of the sound generating device.

The thickness of the diaphragm will affect its acoustic performance. In general, a lower thickness will affect the reliability of the diaphragm, and a larger thickness will affect the sensitivity of the diaphragm. Therefore, the thickness of the diaphragm provided by the present invention can be controlled between 30 μm and 120 μm, for example. When the thickness of the single-layer neoprene diaphragm is 30μm-120μm, the thickness range can make the sensitivity of the sound device diaphragm higher, and the elasticity and rigidity of the diaphragm can meet the production requirements of the sound device . In particular, it can be used in miniature sound generating devices. In addition, as the weakest element of the sound generating device, the diaphragm can ensure long-term normal use during repeated vibrations, thereby prolonging the service life of the sound generating device.

The present invention also provides a comparison curve diagram between a specific implementation of the diaphragm provided by the present invention and the existing conventional diaphragm, as shown in FIG. 5. Figure 5 shows the test curves (SPL curves) of the loudness of the two diaphragms at different frequencies. Among them, the diaphragm is a folded ring diaphragm. The abscissa is frequency (Hz), and the ordinate is loudness.

In Fig. 5, the solid line is the test curve of the diaphragm provided by the present invention. The dotted line is the test curve of the conventional diaphragm. It can be seen from the SPL curve that the intermediate frequency performance of the two diaphragms is similar. The F0 of the sound device using the diaphragm provided by the present invention is 835 Hz. The F0 of the sound device using the conventional diaphragm is 915 Hz. This shows that the low-frequency sensitivity of the diaphragm provided by the present invention is higher than that of the existing PEEK diaphragm. That is to say, the use of the diaphragm provided by the present invention can make the sound generating device have higher loudness and comfort.

The diaphragm provided by the present invention is prepared by mixing neoprene rubber material and auxiliary agent, and then integrally molding. The preparation method of the diaphragm provided by the present invention is simple, and the prepared diaphragm can be used in small electronic devices such as earphones and smart watches. The diaphragm provided by the present invention has excellent resilience. Compared with traditional diaphragm materials, it can not only maintain excellent elasticity during long-term vibration, but also has excellent fatigue resistance and reliability. Moreover, it can be used normally for a long time under extreme conditions.

On the other hand, the present invention also provides a miniature sound generating device.

The miniature sounding device includes a main body of the sounding device and the above-mentioned diaphragm made of neoprene. The chloroprene rubber molecular chain structure includes isomers of chlorinated butadiene. The vibrating membrane is arranged on the main body of the sound generating device, and the vibrating membrane is configured to be driven to vibrate and generate sound through vibration. The main body of the sound generating device may be equipped with components such as a coil, a magnetic circuit system, etc., and the diaphragm is driven to vibrate through electromagnetic induction. The miniature sound emitting device provided by the present invention has excellent acoustic performance.

Although some specific embodiments of the present invention have been described in detail through examples, those skilled in the art should understand that the above examples are only for illustration and not for limiting the scope of the present invention. Those skilled in the art should understand that the above embodiments can be modified without departing from the scope and spirit of the present invention. The scope of the invention is defined by the appended claims.

Claims

A diaphragm for a miniature sounding device, characterized in that: the diaphragm includes at least one elastomer layer, wherein the elastomer layer is made of neoprene;

The chloroprene rubber molecular chain structure includes isomers of chlorinated butadiene;

The molecular weight of the chloroprene rubber is 10,000 to 500,000.
The diaphragm according to claim 1, wherein the isomers of chlorinated butadiene comprise the following components:

Trans-1,4-structure, the content is 70%-95%;

Cis-1,4-structure, the content is 2%-25%;

1, 2 structure, the content is 0.1%-5%; and

3,4 structure, content is 0.1%-5%;

Wherein, the molecular structural formula of the trans-1,4-structure is as follows:

The molecular structural formula of the cis-1,4-structure is as follows:

The molecular structural formula of the 1, 2 structure is as follows:

The molecular structural formula of the 3, 4 structure is as follows:
The diaphragm according to claim 1, wherein the chloroprene rubber is mixed with an inorganic filler reinforcing agent, and the inorganic filler reinforcing agent is carbon black, white carbon black, nano titanium dioxide, talc, At least one of precipitated calcium carbonate and barium sulfate, and the content of the inorganic filler reinforcing agent is 15%-90% of the total amount of the chloroprene rubber.
The diaphragm according to claim 3, wherein the content of the inorganic filler reinforcing agent is 30%-70% of the total amount of the neoprene rubber.
The diaphragm according to claim 1, wherein the chloroprene rubber is mixed with an anti-aging agent, and the anti-aging agent adopts anti-aging agent N-445, anti-aging agent 246, anti-aging agent 4010, anti-aging agent SP, anti-aging agent At least one of RD, antioxidant ODA, antioxidant OD, and antioxidant WH-02, and the content of the antioxidant is 0.5%-10% of the total amount of the chloroprene rubber.
The diaphragm according to claim 5, wherein the content of the anti-aging agent is 1%-5% of the total amount of the neoprene rubber.
The diaphragm according to claim 1, wherein a plasticizer is mixed in the neoprene rubber, and the plasticizer is an aliphatic dibasic acid ester plasticizer or a phthalate ester plasticizer. Agents, benzoic acid ester plasticizers, benzoic acid ester plasticizers, polyol ester plasticizers, chlorinated hydrocarbon plasticizers, epoxy plasticizers, citrate ester plasticizers, At least one of the polyester plasticizers, and the content of the plasticizer is 1%-10% of the total amount of the chloroprene rubber.
The diaphragm according to claim 7, wherein the content of the plasticizer is 3%-7% of the total amount of the neoprene rubber.
The diaphragm according to claim 1, characterized in that: the chloroprene rubber is mixed with an internal mold release agent, and the internal mold release agent is stearic acid, stearate, stearylamine, phosphoric acid At least one of alkyl ester and α-octadecyl-ω-hydroxy polyoxyethylene phosphate, and the content of the internal release agent is 0.5% to 5% of the total amount of the chloroprene rubber.
The diaphragm according to claim 9, wherein the content of the internal release agent is 1%-3% of the total amount of the neoprene.
The diaphragm according to claim 1, wherein the chloroprene rubber is mixed with a vulcanizing agent, and the vulcanizing agent includes a metal oxide system vulcanizing agent and a thiourea vulcanizing agent.
The diaphragm according to claim 11, wherein the metal oxide system vulcanizing agent is magnesium oxide, zinc oxide or calcium oxide, and the content of the metal oxide system vulcanizing agent is the total amount of the neoprene rubber 2%-10% of

The content of the thiourea vulcanizing agent is 0.5% to 5% of the total amount of the chloroprene rubber.
The diaphragm according to claim 1, wherein the diaphragm is a single-layer diaphragm, and the single-layer diaphragm is composed of a layer of neoprene rubber; or,

The diaphragm is a composite diaphragm, and the composite diaphragm includes two, three, four or five diaphragm layers, and the composite diaphragm includes at least one neoprene diaphragm layer.
The diaphragm according to claim 13, wherein the thickness of the neoprene film layer is 10 μm-200 μm.
The diaphragm according to claim 14, wherein the thickness of the neoprene membrane layer is 30 μm-120 μm.
The diaphragm according to claim 1, wherein the hardness of the neoprene rubber is in the range of 30-95A.
The diaphragm according to claim 1, wherein the glass transition temperature of the neoprene rubber is in the range of -50-0°C.
The diaphragm according to claim 1, wherein the loss factor of the chloroprene rubber at room temperature is greater than 0.06.
The diaphragm according to claim 1, wherein the elongation at break of the neoprene rubber is greater than 100%.
A miniature sounding device, characterized by comprising a sounding device main body and the diaphragm according to any one of claims 1-19, the diaphragm being arranged on the sounding device main body, and the diaphragm being configured to be capable of Vibration sounds.