CN110951172A

CN110951172A - Sound generating device's vibrating diaphragm and sound generating device

Info

Publication number: CN110951172A
Application number: CN201911063397.8A
Authority: CN
Inventors: 王述强; 凌风光; 李春; 刘春发
Original assignee: Goertek Inc
Current assignee: Goertek Inc
Priority date: 2019-10-31
Filing date: 2019-10-31
Publication date: 2020-04-03
Also published as: WO2021082252A1

Abstract

The invention discloses a vibrating diaphragm of a sound generating device and the sound generating device, wherein the vibrating diaphragm is made of a butyl rubber film layer, and the butyl rubber comprises a copolymer consisting of an isobutylene monomer and an isoprene monomer; wherein the isoprene monomer is randomly distributed in the molecular chain of the copolymer. The vibrating diaphragm made of the butyl rubber can effectively inhibit redundant vibration of a vibrating system, and achieves the effect of reducing distortion of acoustic products. Such a diaphragm has excellent environmental adaptability and excellent acoustic properties.

Description

Sound generating device's vibrating diaphragm and sound generating device

Technical Field

The invention relates to the technical field of sound-electricity conversion, in particular to a vibrating diaphragm of a sound generating device and the sound generating device.

Background

The micro-speaker is a sound producing device which is widely applied. The micro loudspeaker makes the vibrating diaphragm vibrate through the electromagnetic action, and the vibrating diaphragm of vibration can transmit sound. The diaphragm in the existing micro-speaker mostly adopts a high-modulus plastic film layer (PEEK, PAR, PEI, PI, etc.), or a structure of compounding an engineering plastic diaphragm and a damping film (acrylic glue, silica gel, etc.).

When the micro loudspeaker applying the vibrating diaphragm works in a complex environment, the vibrating diaphragm is easy to cause problems. For example, such diaphragms tend to become more brittle in low temperature environments. In the repeated environment of high and low temperature, the diaphragm is easy to be damaged by fatigue. Under the ozone environment, the vibrating diaphragm is more prone to aging problems and the like. Various problems occur that result in the performance of the diaphragm being degraded or destroyed.

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

Disclosure of Invention

The invention aims to provide a vibrating diaphragm of a sound generating device and a new technical scheme of the sound generating device.

According to a first aspect of the present invention, a diaphragm of a sound generating apparatus is provided, where the diaphragm is made of a butyl rubber film layer, and the butyl rubber includes a copolymer composed of an isobutylene monomer and an isoprene monomer;

wherein the molar weight of the isoprene monomer accounts for 0.1-7% of the total molar weight of the copolymer.

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

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

Optionally, the butyl rubber further comprises an antioxidant; the anti-aging agent comprises at least one of 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 and anti-aging agent WH-02.

Optionally, the butyl rubber further comprises an internal release agent, wherein the internal release agent comprises at least one of stearic acid, stearate, octadecyl amine, alkyl phosphate, α -octadecyl-omega-hydroxypolyoxyethylene phosphate.

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 film layer.

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

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 generating device, including the diaphragm of any one of the above, the diaphragm being configured to generate sound by vibrating.

The vibrating diaphragm made of the butyl rubber can effectively inhibit redundant vibration of a vibrating system, and achieves the effect of reducing distortion of acoustic products. Such diaphragms have excellent environmental adaptability and excellent acoustic properties.

Other features and advantages of the present invention will become apparent from the following detailed description of exemplary embodiments thereof, 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 invention and together with the description, serve to explain the principles of the invention.

FIG. 1 is a cross-sectional view of a three-layer composite diaphragm according to one embodiment of the present invention.

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

FIG. 3 is a graph of different stiffness versus F0 for equal diaphragm thickness for one embodiment of the invention.

FIG. 4 is a graph comparing the total harmonic distortion test curves for a diaphragm of one embodiment of the present invention and a conventional diaphragm.

FIG. 5 is a graph comparing the stress-strain curves of a diaphragm of one embodiment of the present invention with a conventional diaphragm.

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

Detailed Description

Various exemplary embodiments of the present invention 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, the numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise.

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

Techniques, methods, and apparatus known to those 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 particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be discussed further in subsequent figures.

According to an embodiment of the present disclosure, a diaphragm of a sound generating apparatus is provided, where a material of the diaphragm includes a butyl rubber film layer, and the butyl rubber is a copolymer including an isobutylene monomer and an isoprene monomer.

The structure of the copolymer is as follows:

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

In this example, the copolymer contained a small amount of isoprene, and the degree of unsaturation of the copolymer molecular chain was low. The unsaturation degree of the molecular chain is 0.2-6%. Thus, the unsaturation is only 1/50 for natural rubber. Therefore, the butyl rubber has excellent weather resistance and ozone resistance.

The butyl rubber in this example has a relatively low glass transition temperature, which can be as low as-60 ℃. Thus, the diaphragm made of the rubber can be used for a long time in a low-temperature environment.

The butyl rubber has a regular structure, so that the butyl rubber has crystallization capacity and belongs to crystalline rubber. On the main chain of the butyl rubber, every other two methyl groups are arranged spirally around the main chain. The molecular weight of the rubber has higher steric hindrance, and the rubber shows higher damping on physical properties. Therefore, after the vibrating diaphragm is made of the butyl rubber, an acoustic product applied to the vibrating diaphragm can have a lower Q value, redundant vibration of a vibration system can be effectively inhibited, and the effect of reducing loudspeaker distortion is achieved. Therefore, the diaphragm made of the butyl rubber has excellent environment 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 affects the copolymer. The higher the proportion of isoprene in the total amount, the lower the molecular saturation. The molecular saturation affects the ozone resistance and heat resistance of the butyl rubber. The lower the molecular saturation, the better the oxidation resistance of the rubber. Too low a saturation affects the fluidization velocity of the rubber.

The molar amount of the isoprene monomer accounts for 0.1 to 7% of the total molar amount of the copolymer. The copolymer can make rubber have excellent ozone resistance and heat resistance without affecting the fluidization speed of the rubber.

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

The butyl rubber has excellent rebound resilience and oil resistance, and when the vibrating diaphragm of the micro-speaker is made of the butyl rubber, the vibrating diaphragm of the micro-speaker can meet the requirements of material performance.

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

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

In one embodiment, the diaphragm is a composite diaphragm.

When the vibrating diaphragm is a composite vibrating diaphragm, the composite vibrating diaphragm comprises at least one butyl rubber film layer, and the film layers are bonded and fixed in a composite mode through glue layers.

For example, the butyl rubber may be used to form a single-layer diaphragm or a composite diaphragm, where the composite film includes two, three, four, or five layers. The skilled person can select a more optimal number of layers according to actual needs.

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

In one embodiment, a vulcanizing agent is also included in the copolymer.

The rubber is vulcanized by adding the vulcanizing agent, so that the rubber can generate a crosslinking reaction, and the performances of the rubber, such as elasticity, hardness, tensile strength, stretching strength and the like, are improved.

Wherein the vulcanizing agent comprises at least one of sulfur, a sulfur donor, quinone and resin.

The vulcanizing agent can better improve the performances of the rubber such as elasticity, strength, tensile strength, constant tensile strength and the like.

In one embodiment, the copolymer further comprises an antioxidant.

As the service life of the rubber is increased, molecular chains in the rubber are broken to generate free radicals, so that the aging speed of the rubber is accelerated. The addition of an antioxidant to rubber can terminate autocatalytically active radicals generated in rubber products. So as to achieve the effect of prolonging the service life of the rubber.

For example, the antioxidant to be added 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 the antioxidant added is too small, the effect of prolonging the service life of rubber is not achieved. When the anti-aging agent is added too much, the anti-aging agent cannot be well dissolved with the elastomer, and is difficult to disperse uniformly, so that the mechanical property of the rubber is reduced.

For example, when the total of 100 parts by mass of the isobutylene monomer and the isoprene monomer is selected, the addition amount of the anti-aging agent is 0.5 to 10 parts, and the addition amount can simultaneously meet the two requirements of prolonging the service life of the rubber and preventing the mechanical property of the rubber from being reduced.

Preferably, the antioxidant is added in an amount of 1 part to 5 parts. Within the addition amount range, the service life of the rubber can be effectively prolonged, and the mechanical property of the rubber is not reduced.

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

After the internal release agent is mixed with the copolymer, the rubber after molding can be helped to fall off from the mold in the process of manufacturing products. The rubber added with the internal release agent is molded in the mold for many times, and a smooth film is formed in the mold, so that the rubber product is easy to release.

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

These internal mold release agents enable the rubber to be more easily released from the mold. The influence of the demoulding process on the product is avoided.

Alternatively, the mass part of the internal mold release agent is 0.5 to 5 parts when the mass parts of the isobutylene monomer and the isoprene monomer are 100 parts in total. The internal release agent is added in the range to be mixed with the copolymer, so that the formed rubber can be easily released in the release process, and the product forming cannot be influenced.

In one embodiment, a strengthening agent is also included in the copolymer.

In this example, 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 metal salt of unsaturated carboxylic acid.

The butyl rubber has lower modulus, and the hardness of the butyl rubber can be adjusted by adding the reinforcing agent.

As shown in fig. 2, when the content of the reinforcing agent is increased too high, the elongation at break of the butyl rubber is sharply reduced, which may cause the diaphragm to be easily broken.

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

Within the mass fraction range, the membrane breaking risk of the vibrating membrane can be effectively reduced.

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

Within the range, the diaphragm can better avoid the occurrence of membrane rupture.

As shown in fig. 2, the elongation at break of the butyl rubber gradually decreased as the added fraction of carbon black increased. When the part of the carbon black is 100 parts, the elongation at break of the butyl rubber is 90 percent. When the vibrating diaphragm made of the butyl rubber is subjected to large stress, the risk of membrane rupture of the vibrating diaphragm exists.

FIG. 3 is a graph showing the relationship between the hardness of butyl rubber and F0 (resonance frequency).

Butyl rubber materials have a lower modulus relative to engineering plastics. The hardness of the butyl rubber can be adjusted by adding the reinforcing agent, the hardness adjustment range is larger, the hardness adjustment range can be from 25A to 90A, preferably from 30A to 85A, the material strength is increased along with the increase of hard segments, and the adjustable range of 100 percent tensile modulus at room temperature is 0.5-50MPa, preferably from 1-30 MPa. The 100% modulus of butyl rubber is positively correlated with the stiffness, and the higher the stiffness, the higher the 100% modulus, the higher the F0 of the diaphragm material, but when F0 is too high, the loudness of the low frequency of the loudspeaker is reduced. FIG. 3 shows F0 for diaphragms of the same thickness but different hardnesses, and it can be seen that F0 increases proportionally with increasing stiffness.

For example, the sound generating device is a micro-speaker, and the F0 of the speaker is proportional to the young's modulus and thickness of the diaphragm. The adjustment of F0 can be achieved by adjusting the young's modulus and thickness of the diaphragm.

The specific adjustment principle is as follows:

wherein Mms is the equivalent vibration mass of the loudspeaker, and Cms is the equivalent compliance of the loudspeaker.

Wherein Cms1 is the elasto-compliance and Cms2 is the diaphragm compliance. When there is no elastic wave design, the equivalent compliance of the loudspeaker is the compliance of the diaphragm.

Wherein W is the total width of the bending ring part of the diaphragm, and t is the thickness of the diaphragm; dvc is the joint outer diameter of the vibrating diaphragm and the voice coil; e is the Young modulus of the vibrating diaphragm material; u is the Poisson's ratio of the vibrating diaphragm material.

It can be seen that the F0 of a speaker is proportional to the modulus and thickness, while the modulus of rubber is proportional to its stiffness, and therefore, F0 can be tuned by way of stiffness tuning. For a full bass and comfortable listening, the diaphragm should be sufficiently stiff and damped while the loudspeaker has a low F0. The size of F0 can be adjusted by one skilled in the art by adjusting the stiffness and thickness of the diaphragm. Optionally, the hardness is 25-90A. The thickness of the diaphragm is 30-120 μm. This enables the F0 of the speaker to reach 150-1500 Hz. The low frequency performance of the speaker is excellent.

The butyl rubber has a regular structure, has crystallization capacity and is crystalline rubber. On the main chain of the butyl rubber, every other methine group has two methyl groups arranged in a helix around the main chain. Therefore, the molecular weight of the rubber has higher steric hindrance, which is reflected in physical properties, namely, the butyl rubber has higher damping, and the loss factor at room temperature is more than 0.06, preferably more than 0.1. The excellent damping performance makes the diaphragm have lower resistance to bending. The damping of the vibrating diaphragm is improved, and when the vibrating diaphragm is applied to a loudspeaker, the vibrating system has strong capability of inhibiting the polarization phenomenon in the vibrating process, and the vibration consistency is good. The existing engineering plastic film layer has low damping, the loss factor of the existing engineering plastic film layer is generally less than 0.01, and the damping performance is small. As shown in fig. 4, after the butyl rubber is made into the diaphragm, the acoustic product can have a lower Q value, so that the unnecessary vibration of the vibration system and the polarization of the vibration system can be effectively suppressed, and the effect of reducing the distortion of the speaker can be achieved.

As shown in fig. 5, butyl rubber has excellent toughness with an elongation at break of greater than 100%, preferably greater than 150%. In the range of the elongation at break, the diaphragm module is not easy to break and the like.

The engineering plastic diaphragm forms an obvious yield point, and the strain is about 1-5%. While the diaphragm provided by the present disclosure does not have a yield point, this indicates that the diaphragm has a wider elastic region and the resilience performance is excellent.

The butyl rubber diaphragm has good flexibility, for example, the elongation at break is more than or equal to 100%. This results in a greater vibration displacement and loudness of the diaphragm. And has good reliability and durability. The better the flexibility of the material, the greater the elongation at break, the greater the ability of the diaphragm to resist damage. When the vibrating diaphragm vibrates in a large-amplitude state, the material generates large strain and easily exceeds the strain range of engineering plastic yielding, so that the vibrating diaphragm is abnormal in membrane folding, membrane cracking or membrane breaking. The vibrating diaphragm made of the butyl rubber serving as the base material has flexibility in a large strain interval, and the risk of damage of the vibrating diaphragm is reduced.

For example, fig. 6 is a test curve (SPL curve) of loudness at different frequencies for a diaphragm of one embodiment of the present disclosure and a conventional diaphragm.

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

In fig. 6, as can be seen from the SPL curve, the two diaphragms F0 are identical, but the diaphragm sensitivity in this embodiment is higher than that of the conventional diaphragm. That is, a speaker using the diaphragm of the embodiment of the present invention has a higher loudness.

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

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

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

The vibrating diaphragm prepared by the preparation method can not influence the acoustic performance of the vibrating diaphragm.

According to an embodiment of the present disclosure, there is provided a sound-generating device including the diaphragm of any one of the above, the diaphragm being configured to cause the sound-generating device to generate sound by vibrating.

In the sound production device, the sound production device further comprises a vibration system and a magnetic circuit system, and the vibrating diaphragm is arranged in the vibration system. Through the action between the magnetic circuit system and the vibration system, the vibration diaphragm is vibrated to produce sound. For example, the sound generating device is a micro speaker, and the vibration of the diaphragm makes the micro speaker generate sound. The micro-speaker using the diaphragm described above has the advantages of the diaphragms in all the examples described above.

Although some specific embodiments of the present invention have been described in detail by way of examples, it should be understood by those skilled in the art that the above examples are for illustrative purposes only and are not intended to limit the scope of the present invention. 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 invention. The scope of the invention is defined by the appended claims.

Claims

1. A vibrating diaphragm of a sound production device is characterized in that the vibrating diaphragm is made of a butyl rubber film layer, and butyl rubber comprises a copolymer composed of an isobutylene monomer and an isoprene monomer;

2. The diaphragm of claim 1, wherein the butyl rubber further comprises a vulcanizing agent; the vulcanizing agent comprises sulfur, a sulfur donor and at least one of quinone and resin.

3. The diaphragm of claim 1, wherein the butyl rubber further comprises a reinforcing agent; the reinforcing agent comprises at least one of carbon black, silicon dioxide, calcium carbonate, barium sulfate, organic montmorillonite and unsaturated carboxylic acid metal salt.

4. The diaphragm of claim 1, wherein the butyl rubber further comprises an anti-aging agent; the anti-aging agent comprises at least one of 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 and anti-aging agent WH-02.

5. The diaphragm of claim 1, wherein the butyl rubber further comprises an internal mold release agent, wherein the internal mold release agent comprises at least one of stearic acid, a stearate, octadecyl amine, alkyl phosphate, and α -octadecyl- ω -hydroxypolyoxyethylene phosphate.

6. The diaphragm of claim 1, wherein the diaphragm is a single-layer diaphragm.

7. The diaphragm of claim 1, wherein the diaphragm is a composite diaphragm, and the composite diaphragm includes at least one butyl rubber film layer.

8. The diaphragm of claim 1, wherein the thickness of the diaphragm is 10um to 200 um.

9. The diaphragm of claim 1, wherein the diaphragm is fabricated by one of compression molding, injection molding, and pneumatic molding.

10. A sound-generating device comprising the diaphragm of any one of claims 1 to 9, the diaphragm being configured to generate sound by vibrating.