WO2021082252A1 - Diaphragm of sound production device, and sound production device - Google Patents

Abstract

Disclosed in the present invention are a diaphragm of a sound production device, and a sound production device. The material of the diaphragm is a butyl rubber membrane layer, and butyl rubber comprises a copolymer composed of isobutene monomers and isoprene monomers; the isoprene monomers are randomly distributed in molecular chains of the copolymer. One technical effect of the present disclosure is that the diaphragm made from butyl rubber can effectively inhibit excess vibration of a vibration system, and exert the effect of reducing distortion of an acoustic product. The diaphragm has excellent environmental adaptability and excellent acoustic performance.

Description

Diaphragm of sound device and sound device Technical field

The present invention relates to the technical field of acoustic-electric conversion, and more specifically, to a diaphragm of a sound-producing device and a sound-producing device.

Background technique

Micro speakers are very widely used sound emitting devices. Micro speakers vibrate the diaphragm through electromagnetic action, and the vibrating diaphragm can transmit sound. The diaphragm in the existing micro-speakers mostly adopts a high-modulus plastic film layer (PEEK, PAR, PEI, PI, etc.), or a composite structure of an engineering plastic diaphragm and a damping film (acrylic glue, silica gel, etc.).

When the micro-speaker using this kind of diaphragm works in a more complicated environment, the diaphragm is prone to problems. For example, in a low temperature environment, this type of diaphragm tends to become more brittle. In an environment with repeated high and low temperatures, it is easy to cause fatigue damage to the diaphragm. In an ozone environment, the diaphragm is more prone to aging problems. All kinds of problems that occur will cause the performance of the diaphragm to be reduced or destroyed.

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

Summary of the invention

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

According to the first aspect of the present invention, there is provided a diaphragm of a sound generating device, the material of the diaphragm includes a butyl rubber membrane layer, and the butyl rubber includes a copolymer composed of isobutylene monomer and isoprene monomer;

Wherein, the molar amount of the isoprene monomer accounts for 0.1% to 7% of the total molar amount of the copolymer.

Optionally, the butyl rubber further includes a vulcanizing agent; the vulcanizing agent includes at least one of sulfur, sulfur donating agent, quinone, and resin.

Optionally, the butyl rubber further includes a reinforcing agent; the reinforcing agent includes at least one of carbon black, silica, calcium carbonate, barium sulfate, organic montmorillonite, and unsaturated carboxylic acid metal salt .

Optionally, the butyl rubber further includes an antioxidant; the antioxidant includes antioxidant N-445, antioxidant 246, antioxidant 4010, antioxidant SP, antioxidant RD, antioxidant ODA, antioxidant OD, antioxidant At least one of WH-02.

Optionally, the butyl rubber further includes an internal mold release agent; the internal mold release agent includes stearic acid, stearate, stearylamine, alkyl phosphate, α-octadecyl- At least one of ω-hydroxypolyoxyethylene phosphates.

Optionally, the diaphragm is a single-layer diaphragm.

Optionally, the diaphragm is a composite diaphragm, and the composite diaphragm includes at least one butyl rubber membrane layer.

Optionally, the thickness of the diaphragm is 10um-200um.

Optionally, the diaphragm is prepared by one of compression molding, injection molding, and air pressure molding.

According to another aspect of the present invention, there is provided a sound emitting device, including any one of the above-mentioned diaphragms, and the diaphragm is configured to vibrate to make the sound emitting device sound.

A technical effect of the present disclosure is that the diaphragm made of the butyl rubber can effectively suppress the unnecessary vibration of the vibration system and achieve the effect of reducing the distortion of the acoustic product. Such a diaphragm has excellent environmental adaptability and excellent 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 cross-sectional view of a three-layer composite diaphragm according to an embodiment of the present invention.

Fig. 2 is a graph showing the relationship between the added amount of a reinforcing agent and the elongation at break in an embodiment of the present invention.

Fig. 3 is a diagram showing the relationship between the same thickness and different hardness of the diaphragm and F0 according to an embodiment of the present invention.

Fig. 4 is a comparison diagram of total harmonic distortion test curves between a diaphragm and a conventional diaphragm according to an embodiment of the present invention.

Fig. 5 is a comparison diagram of stress-strain curves between a diaphragm and a conventional diaphragm according to an embodiment of the present invention.

Fig. 6 is a test curve (SPL curve) of loudness at different frequencies of a diaphragm and a conventional diaphragm according to an embodiment of the present invention.

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 disclosure, there is provided a diaphragm of a sound generating device. The material of the diaphragm includes a butyl rubber film layer, and the butyl rubber is a copolymer including isobutylene monomer and isoprene monomer.

Wherein, the molar amount of the isoprene monomer accounts for 0.1% to 7% of the total molar amount of the copolymer.

The structure of the copolymer is as follows:

The copolymer is composed of isobutylene monomer and isoprene monomer. Wherein, n is the molar amount of isobutylene monomer; m is the molar amount of isoprene monomer; the isoprene monomer is randomly distributed in the molecular chain of the copolymer.

In this embodiment, the copolymer contains a small amount of isoprene, and the degree of unsaturation of the molecular chain of the copolymer is relatively low. The degree of unsaturation of the molecular chain is 0.2%-6%. This degree of unsaturation is only 1/50 of that of natural rubber. Therefore, the butyl rubber has excellent weathering resistance and ozone resistance.

The butyl rubber in this embodiment has a relatively low glass transition temperature, which can reach -60°C at the lowest. In this way, the rubber diaphragm can be used for a long time in a low temperature environment.

The regular structure of the butyl rubber enables the butyl rubber to have the ability to crystallize and is a crystalline rubber. In the main chain of the butyl rubber, there are two methyl groups in a spiral arrangement around the main chain for every other methyl group. Its molecular weight has a higher steric hindrance, which is reflected in physical properties, that is, butyl rubber has higher damping. In this way, after the butyl rubber is made into the diaphragm, the acoustic products applied to the diaphragm can have a lower Q value, which can effectively suppress the unnecessary vibration of the vibration system and achieve the effect of reducing the distortion of the speaker. In this way, the diaphragm made of the butyl rubber has excellent environmental adaptability and excellent acoustic performance.

The main monomers of the copolymer of isobutylene and isoprene are isobutylene and isoprene. Among them, the proportion of isoprene in the copolymer will affect the copolymer. The higher the proportion of isoprene in the total amount, the lower the molecular saturation. The degree of molecular saturation will affect the ozone resistance and heat resistance of butyl rubber. The lower the molecular saturation, the better the oxidation resistance of rubber. But too low saturation will affect the fluidization speed of rubber.

The molar amount of isoprene monomer accounts for 0.1% to 7% of the total molar amount of the copolymer. The copolymer does not affect the fluidization speed of the rubber, so that the rubber has excellent ozone resistance and heat resistance.

Preferably, the molar amount of the isoprene monomer accounts for 0.2% to 5% of the total molar amount of the copolymer. In this proportion, butyl rubber has more excellent ozone resistance and heat resistance.

Butyl rubber has excellent resilience and oil resistance. The use of butyl rubber to make the diaphragm of the micro speaker can meet the material performance requirements of the diaphragm of the micro speaker.

In one embodiment, the diaphragm is a single-layer diaphragm.

When the diaphragm is a single-layer diaphragm, the diaphragm is made of the above-mentioned butyl rubber.

In one embodiment, the diaphragm is a composite diaphragm.

When the diaphragm is a composite diaphragm, the composite diaphragm includes at least one butyl rubber diaphragm layer, and each diaphragm layer is fixed by composite bonding with a glue layer.

For example, the butyl rubber can be made into a single-layer diaphragm or a composite diaphragm. The composite diaphragm includes two, three, four or five layers. Those skilled in the art can choose a better number of layers according to actual needs.

As shown in Figure 1, it is a three-layer composite diaphragm. The middle layer 12 is a butyl rubber film layer, and the engineering plastic film layer 11 is respectively compounded on the upper and lower surfaces of the butyl rubber film layer.

In one embodiment, the copolymer further includes a vulcanizing agent.

Adding a vulcanizing agent to vulcanize the rubber can cause the rubber to undergo a cross-linking reaction and increase the rubber's elasticity, hardness, tensile strength, and tensile strength.

Wherein, the vulcanizing agent includes at least one of sulfur, sulfur donating agent, quinone and resin.

The above-mentioned vulcanizing agent can better improve the elasticity, strength, tensile strength and tensile strength of rubber.

In one embodiment, the copolymer further includes an anti-aging agent.

As the rubber's use time increases, the molecular chains in the rubber will be broken and free radicals will be generated, which will accelerate the aging rate of the rubber. Adding antioxidants to rubber can stop the autocatalytically active free radicals generated in rubber products. In order to achieve the effect of increasing the service life of the rubber.

For example, the added antioxidant includes at least one of antioxidant N-445, antioxidant 246, antioxidant 4010, antioxidant SP, antioxidant RD, antioxidant ODA, antioxidant OD, and antioxidant WH-02.

When the amount of antioxidant added is too small, the effect of prolonging the service life of the rubber cannot be achieved. When the anti-aging agent is added too much, the anti-aging agent cannot be better miscible with the elastomer, and it is difficult to uniformly disperse, which will cause the mechanical properties of the rubber to decrease.

For example, when the total mass parts of isobutylene monomer and isoprene monomer are selected to be 100 parts, the addition amount of antioxidant is 0.5-10 parts. This addition amount can simultaneously extend the service life of the rubber and prevent the deterioration of the mechanical properties of the rubber. Two needs.

Preferably, the amount of antioxidant added is 1 part to 5 parts. Within this addition amount range, the service life of the rubber can be effectively increased without reducing the mechanical properties of the rubber.

In one embodiment, the copolymer further includes an internal mold release agent.

After the internal mold release agent is mixed with the copolymer, it can help the molded rubber to fall out of the mold in the process of making the product. The rubber added with the internal release agent is molded in the mold many times, and a smooth film is formed in the mold, making the rubber product release easier.

For example, the added internal mold release agent includes at least one of stearic acid, stearate, stearylamine, alkyl phosphate, and α-octadecyl-ω-hydroxypolyoxyethylene phosphate.

These internal release agents can make the rubber easier to release from the mold. Avoid the influence of the demolding process on the product.

Optionally, when the total mass parts of isobutylene monomer and isoprene monomer are 100 parts, the mass parts of the internal release agent is 0.5 to 5 parts. If the internal release agent is added to mix with the copolymer within this range, the formed rubber will be more easily released during the release process without affecting product molding.

In one embodiment, the copolymer further includes a reinforcing agent.

In this embodiment, the reinforcing agent added to the butyl rubber is an inorganic filler.

Preferably, the reinforcing agent includes at least one of carbon black, silica, calcium carbonate, barium sulfate, organic montmorillonite, and unsaturated carboxylic acid metal salt.

Butyl rubber has a low modulus, and the hardness of butyl rubber can be adjusted by adding a reinforcing agent.

As shown in Figure 2, when the content of the reinforcing agent is increased too high, the elongation at break of butyl rubber will drop sharply, which will cause the diaphragm to break easily.

In an example, when the total mass parts of isobutylene monomer and isoprene monomer are 100 parts, the mass parts of the reinforcing agent is 5 parts to 90 parts.

Within the above-mentioned mass fraction range, the risk of diaphragm rupture can be effectively reduced.

Preferably, the mass parts of the reinforcing agent is 5 parts to 70 parts.

In this range, the diaphragm can better avoid membrane rupture.

As shown in Figure 2, the elongation at break of butyl rubber gradually decreases as the amount of carbon black added increases. When the part of carbon black is 100 parts, the elongation at break of butyl rubber is 90%. When the diaphragm made of butyl rubber is subjected to greater stress, there is a risk of the diaphragm breaking.

As shown in Figure 3, it is a graph of the relationship between butyl rubber hardness and F0 (resonant frequency).

Compared with engineering plastics, butyl rubber materials have a lower modulus. The hardness of butyl rubber can be adjusted by adding a reinforcing agent. It has a large hardness adjustment range. The hardness adjustment range can be 25A-90A, preferably 30-85A. With the increase of the hard segment, the material strength increases. The adjustable range of 100% constant elongation modulus is 0.5-50MPa, preferably 1-30MPa. The 100% constant elongation modulus of butyl rubber is positively related to the hardness. The higher the hardness, the higher the 100% constant elongation modulus, and the higher the F0 of the diaphragm material. However, when the F0 is too high, the loudness of the loudspeaker's low frequency will be reduced. The following figure shows the F0 of the diaphragm with the same thickness and different hardness. It can be seen from the figure that as the hardness increases, the F0 increases proportionally.

For example, the sound emitting device is a micro speaker, and the F0 of the speaker is proportional to the Young's modulus and thickness of the diaphragm. F0 can be adjusted by adjusting the Young's modulus and thickness of the diaphragm.

The specific adjustment principle is as follows:

Among them, Mms is the equivalent vibration quality of the speaker, and Cms is the equivalent compliance of the speaker.

Among them, Cms1 is elastic wave compliance, and Cms2 is diaphragm compliance. When designing without bouncing waves, the equivalent compliance of the speaker 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 F0 of the speaker is proportional to the modulus and thickness, and the modulus of the rubber is proportional to its hardness. Therefore, the F0 can be adjusted by the way of hardness adjustment. In order to obtain full bass and comfortable listening, while the speaker has a lower F0, the diaphragm should have sufficient stiffness and damping. Those skilled in the art can adjust the size of F0 by adjusting the hardness and thickness of the diaphragm. Optionally, the hardness is 25-90A. The thickness of the diaphragm is 30-120μm. This enables the F0 of the speaker to reach 150-1500Hz. The low frequency performance of the speaker is excellent.

The butyl rubber has a regular structure and crystallizing ability. It is a crystalline rubber. In the main chain of the butyl rubber, there are two methyl groups arranged spirally around the main chain for every other methine group. Therefore, its molecular weight has higher steric hindrance, which is reflected in physical properties, that is, butyl rubber has higher damping, and the loss factor at room temperature is greater than 0.06, preferably greater than 0.1. Excellent damping performance, so that the diaphragm has a lower impedance curve. The damping of the diaphragm is improved, and when used in a speaker, the vibration system has a strong ability to suppress the polarization phenomenon during the vibration process, and the vibration consistency is good. The existing engineering plastic film layer has low damping, and its loss factor is generally less than 0.01, and the damping property is small. As shown in Figure 4, after the diaphragm is made of butyl rubber, its acoustic products can have a lower Q value, which can effectively suppress the unnecessary vibration of the vibration system and the polarization of the vibration system, and achieve the effect of reducing speaker distortion.

As shown in Figure 5, butyl rubber has excellent toughness, with an elongation at break greater than 100%, preferably greater than 150%. Within the above-mentioned range of elongation at break, reliability problems such as membrane rupture are unlikely to occur during use of the diaphragm module.

The engineering plastic diaphragm has an obvious yield point, which is about 1 to 5% strain. However, the diaphragm provided by the present disclosure does not have a yield point, which indicates that the diaphragm has a wider elastic area and has excellent resilience performance.

Butyl rubber diaphragm has good flexibility, for example, elongation at break ≥100%. This makes the vibration displacement of the diaphragm larger and louder. And the reliability and durability are good. The better the flexibility of the 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 material produces a large strain, which easily exceeds the strain range of the engineering plastics yielding, causing the diaphragm to appear abnormally such as membrane fold, membrane crack or membrane rupture. The diaphragm made of butyl rubber as the base material has flexibility in a larger strain range, reducing the risk of diaphragm damage.

For example, FIG. 6 is a test curve (SPL curve) of loudness at different frequencies of a diaphragm and a conventional diaphragm according to an embodiment of the disclosure.

The diaphragm is a folded ring diaphragm. The abscissa is frequency (Hz), and the ordinate is loudness. The solid line is the test curve of the diaphragm provided by the embodiment of the present invention. The dotted line is the test curve of the conventional diaphragm.

In Fig. 6, it can be seen from the SPL curve that the two diaphragms F0 are the same, but the sensitivity of the diaphragm in this embodiment is higher than that of the conventional diaphragm. In other words, the speaker using the diaphragm of the embodiment of the present invention has a higher loudness.

In one embodiment, the thickness of the diaphragm is 10um-200um. Within this range, the diaphragm can have an appropriate F0, and a good low-frequency response can be achieved.

Preferably, the thickness of the diaphragm is 30um-120um. Within this range, the diaphragm has better performance.

In one embodiment, when the butyl rubber is made into the diaphragm, it is made by one of compression molding, injection molding, and air pressure molding.

Using the above-mentioned preparation method to prepare the diaphragm will not affect the acoustic performance of the diaphragm.

According to an embodiment of the present disclosure, there is provided a sound emitting device including any one of the above-mentioned diaphragms, the diaphragm being configured to vibrate the sound emitting device to produce sound.

The sound device also includes a vibration system and a magnetic circuit system, and the diaphragm is arranged in the vibration system. Through the interaction between the magnetic circuit system and the vibration system, the diaphragm is vibrated and sounded. For example, the sound device is a micro speaker, and the vibration of the diaphragm makes the micro speaker sound. The micro-speaker using the above-mentioned diaphragm has the advantages of the above-mentioned diaphragm in all the examples.

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 (10)

1. A diaphragm of a sound device, characterized in that the material of the diaphragm includes a butyl rubber membrane layer, and the butyl rubber includes a copolymer composed of isobutylene monomer and isoprene monomer;

   Wherein, the molar amount of the isoprene monomer accounts for 0.1% to 7% of the total molar amount of the copolymer.
2. The diaphragm of claim 1, wherein the butyl rubber further includes a vulcanizing agent; the vulcanizing agent includes at least one of sulfur, a sulfur donating agent, and quinone and resin.
3. The diaphragm according to claim 1, wherein the butyl rubber further includes a reinforcing agent; the reinforcing agent includes carbon black, silica, calcium carbonate, barium sulfate, organic montmorillonite, and At least one of saturated carboxylic acid metal salts.
4. The diaphragm of claim 1, wherein the butyl rubber further includes an antioxidant; the antioxidant includes antioxidant N-445, antioxidant 246, antioxidant 4010, antioxidant SP, and antioxidant RD , At least one of anti-aging agent ODA, anti-aging agent OD and anti-aging agent WH-02.
5. The diaphragm according to claim 1, wherein the butyl rubber further includes an internal mold release agent; the internal mold release agent includes stearic acid, stearate, stearylamine, and alkyl phosphate. At least one of base ester and α-octadecyl-ω-hydroxypolyoxyethylene phosphate.
6. The diaphragm according to claim 1, wherein the diaphragm is a single-layer diaphragm.
7. The diaphragm according to claim 1, wherein the diaphragm is a composite diaphragm, and the composite diaphragm includes at least one butyl rubber membrane layer.
8. The diaphragm according to claim 1, wherein the thickness of the diaphragm is 10um-200um.
9. The diaphragm according to claim 1, wherein the diaphragm is prepared by one of compression molding, injection molding, and air pressure molding.
10. A sounding device, comprising the diaphragm of any one of claims 1-9, the diaphragm being configured to vibrate the sounding device to produce sound.

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