WO2020108252A1 - Activated carbon sound absorption particle and sound production apparatus - Google Patents

Abstract

Disclosed are an activated carbon sound absorption particle and a sound production apparatus. The activated carbon sound absorption particle is prepared by mixing an amorphous activated carbon particle with a high-molecular polymer adhesive; an activated carbon sound absorption material comprises three elements, i.e., carbon, hydrogen, and oxygen; the amorphous activated carbon particle comprises a turbostratic structure formed by irregularly accumulating the molecular fragments of a two-dimensional graphite layer structure and/or three-dimensional graphite microcrystalline; the amorphous activated carbon particle comprises a loose pore structure; the pore structure comprises nanoscale micropores and nanoscale mesopores; the particle size range of the activated carbon sound absorption particle is 50-1,000μm; the particle size range of the amorphous activated carbon particle is 0.1-100μm. The present invention has a technical effect that the activated carbon sound absorption particle may be used for reducing the resonance frequency of the sound production apparatus.

Description

Activated carbon sound-absorbing particles and sound-generating device Technical field

The present invention relates to the technical field of acoustics, in particular, the present invention relates to an activated carbon sound-absorbing particle and sound-generating device.

Background technique

Consumer electronics products have developed rapidly this year, and electronic products such as mobile phones, tablet computers, and headphones are widely used by consumers in various fields. With the gradual development of related technologies, consumers have increasingly higher performance requirements for electronic products. Technicians improve the various components of electronic products to meet the needs of performance development.

The sound-generating device is an important acoustic device in electronic products, which is used to convert electrical signals into sound signals. The resonance frequency of the sound-generating device is an important acoustic performance index, and reducing the resonance frequency of the sound-generating device helps to improve the acoustic effect of the sound-generating device.

Resonance frequency means that the sound-generating device gradually increases the vibration frequency from the low range, when the vibration intensity reaches the strongest vibration, or, the impedance characteristic of the sound-generating device is measured. When the impedance value reaches the maximum for the first time, the corresponding vibration frequency is called the speaker The resonant frequency or resonant frequency of the unit, namely f ₀ .

How to reduce the resonance frequency of the sound-generating device to improve the acoustic performance has become a major research direction for those skilled in the art.

Summary of the invention

An object of the present invention is to provide a new technical solution for reducing the resonance frequency of a sound-generating device.

According to the first aspect of the present invention, there is provided activated carbon sound absorbing particles. The activated carbon sound absorbing particles are made by mixing amorphous activated carbon particles with a polymer binder. The activated carbon sound absorbing materials include carbon, hydrogen and oxygen. Element, the amorphous activated carbon particles contain a chaotic layer structure formed by the random accumulation of molecular fragments of a two-dimensional graphite layer structure and/or three-dimensional graphite crystallites. The amorphous activated carbon particles have a loose pore structure. The pore structure includes nano-scale micropores and mesopores, the particle size of the activated carbon sound absorbing particles is in the range of 50-1000 microns, and the particle size of the amorphous activated carbon particles is in the range of 0.1-100 microns.

Optionally, the mass ratio of carbon elements in the amorphous activated carbon particles is greater than or equal to 60 wt%, and the mass ratio of carbon to oxygen in the amorphous activated carbon particles is greater than or equal to 3.

Optionally, the mass ratio of carbon elements in the amorphous activated carbon particles is greater than or equal to 60 wt%, and the mass ratio of hydrocarbons in the amorphous activated carbon particles is greater than or equal to 11.

Optionally, the particle size range of the activated carbon sound absorbing particles is 100-450 microns, and the particle size range of the amorphous activated carbon particles is 0.2-20 microns.

Optionally, the pore structure has micropores and mesopores, the pore size of the micropores ranges from 0.5-2 nm, and the pore size of the mesopores ranges from 2-3.5 nm.

Optionally, the cumulative pore volume of the amorphous activated carbon particles ranges from 0.6 to ⁵ cm ³ /g.

Optionally, the polymer adhesive includes at least one of polyacrylics, polyvinyl alcohols, polystyrenes, polyurethanes, polyvinyl acetates, and polybutadiene rubbers. The mass proportion of the polymer adhesive in the activated carbon sound absorbing particles is 1-10wt%.

Optionally, the amorphous activated carbon particles include hydrophobic amorphous activated carbon particles.

Optionally, the bulk density of the amorphous activated carbon particles is 0.05-0.8 g/cm ³ .

The invention also provides a sound generating device, including:

A housing with a containing cavity formed in the housing;

A vibration component, the vibration component is disposed in the housing;

The above-mentioned activated carbon sound-absorbing particles are arranged in the accommodating cavity.

According to one embodiment of the present disclosure, activated carbon sound absorbing particles may be used to reduce the resonance frequency of the sound-generating device.

Other features and advantages of the present invention will become clear by the following detailed description of exemplary embodiments of the present invention with reference to the drawings.

BRIEF DESCRIPTION

The drawings incorporated in and forming a part of the specification illustrate embodiments of the invention, and together with the description serve to explain the principles of the invention.

1 is a comparison table of carbon-oxygen ratio, structural characteristics and resonance frequency reduction effect of the activated carbon sound absorbing material provided by the present invention;

2 is a graph of vibration frequency and electrical impedance of activated carbon sound-absorbing materials with different carbon-oxygen ratios provided by the present invention;

3 is a graph of the cumulative pore volume when the carbon-to-oxygen ratio of the activated carbon sound absorbing material provided by the present invention is 9;

4 is a comparison table of the particle size of amorphous activated carbon particles provided by the present invention and the resonance frequency reduction effect;

5 is a graph of vibration frequency and electrical impedance of amorphous activated carbon carbon particles of different particle sizes provided by the present invention.

detailed description

Various exemplary embodiments of the present invention will now be described in detail with reference to the drawings. It should be noted that 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 unless specifically stated otherwise.

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

Techniques, methods and equipment known to those of ordinary skill in the related art may not be discussed in detail, but where appropriate, the techniques, methods and equipment should be considered as part of the specification.

In all examples shown and discussed herein, any specific values should be interpreted as merely exemplary and not limiting. 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, so once an item is defined in one drawing, there is no need to discuss it further in subsequent drawings.

The invention provides an activated carbon sound absorbing material, the activated carbon sound absorbing material contains a two-dimensional graphite layer and/or three-dimensional graphite crystallites, and the activated carbon sound absorbing material formed by stacking graphite layers and crystallites has a loose pore structure inside. The pore structure includes nano-scale micropores and mesopores. The pore size of the mesopores is larger than that of the micropores. The pore structure in the activated carbon sound-absorbing material can enable the activated carbon sound-absorbing material to rapidly absorb and release air. The carbon element is used to provide support, thereby forming a frame and a channel structure.

After the verification of the present invention, the activated carbon sound-absorbing material is put into the box of the sound-generating device, which can be equivalent to expanding the volume of the box by absorbing and releasing the air, and the volume of the chamber is expanded by a times, a is greater than 1 .

The resonance frequency f _{0 of the} sounding device unit can be expressed by the following formula:

In the above equation, M _ms is the mass of the sounding device unit, and C _ms is the equivalent acoustic compliance of the sounding device unit.

After assembling the sound-generating device unit in the box of the sound-generating device, the resonance frequency f _{01 of the} sound-generating device can be expressed by the following formula:

In the above equation, C _ms is the air acoustic compliance of the volume of the box of the sounding device.

After putting the activated carbon sound-absorbing particles into the box of the sound-generating device, the resonance frequency f _{02 of the} sound-generating device at this time is expressed by the following formula:

As mentioned above, the volume of the cabinet is equivalently enlarged by a times (a>1) by the activated carbon sound-absorbing material, and it can be seen that f _{02 is} less than f ₀₁ .

In the box of the sound-generating device, the forced vibration of the particles consumes the energy of the sound wave. This effect is equivalent to the increase in the air acoustic compliance in the volume of the box, thereby reducing the resonance frequency f ₀₂ .

The activated carbon sound-absorbing material provided by the present invention can be used in sound-generating devices such as earphones, earpieces, speakers, and sound boxes. For example, the activated carbon sound-absorbing material is put into the rear sound cavity of the sound-generating device to virtually expand the volume of the rear sound cavity, thereby reducing the resonance frequency of the sound-generating device. Furthermore, the effect of improving the acoustic performance of the sound generating device is achieved.

In an optional embodiment, the mass ratio of carbon element in the activated carbon sound-absorbing material is greater than or equal to 60 wt%. The mass ratio of carbon to oxygen in the activated carbon sound absorbing material is greater than or equal to 3. The carbon element plays a role in forming a frame and constructing a pore structure in the activated carbon sound-absorbing material. After the inventor of the present invention has developed, it is preferable to configure the carbon-oxygen mass ratio to be greater than 3. If the carbon-to-oxygen mass ratio is too low, the pore structure formed in the activated carbon sound-absorbing material will be too sparse, and the pore diameter of the pore structure will become larger. As the pore size of the channel structure becomes larger, the cumulative pore volume of the activated carbon sound-absorbing material becomes smaller, and the ability to absorb and reduce air is reduced. This phenomenon will cause the expansion magnification of the activated carbon sound-absorbing material to the equivalent volume of the box of the sound-generating device to be reduced, which in turn causes the effect of reducing the resonance frequency f ₀ to be weakened. Therefore, the preferred mass ratio of carbon to oxygen is greater than 3.

The carbon-oxygen mass ratio is preferably greater than 5. When the mass ratio of carbon to oxygen is within the above range, the effect of reducing the resonance frequency is the best. At this time, the diameter of the pore structure of the pore structure is smaller, which is more conducive to the rapid absorption and release of air. In a specific embodiment of the present invention, the carbon-to-oxygen mass ratio may be 3, 5, 15, 20.

In another optional embodiment, the mass ratio of carbon element in the activated carbon sound absorbing material is greater than or equal to 60wt%. The mass ratio of hydrocarbons in the activated carbon sound-absorbing material is greater than or equal to 11. Optionally, the activated carbon sound-absorbing material is formed by carbonizing mineral materials, plant materials, synthetic materials, etc. at a high temperature. Depending on the carbonization process, the proportion of raw materials remaining inside the activated carbon sound-absorbing material is different. The smaller the mass ratio of hydrocarbons, the smaller the percentage of other impurities in the remaining raw materials. Correspondingly, the more perfect the pore structure inside the material, the greater the cumulative pore volume of the pore structure, and the better the adsorption capacity for air.

Preferably, the carbon-hydrogen ratio is greater than 13. Within the above range, the activated carbon sound-absorbing material exhibits the best effect of reducing the resonance frequency. For example, the activated carbon sound-absorbing material with a carbon-hydrogen mass ratio of 10, 11, 13, and 20 has cumulative pore volumes of 0.37g/cm ³ , 0.45g/cm ³ , 0.62g/cm ^3, and 0.81g/cm ³ , respectively. Among the activated carbon sound absorbing materials with the same quality, the effect of reducing the resonance frequency f _{0 is} the best.

For the pore structure, the micropores are mainly used to absorb and contain air molecules, while the mesopores can not only contain air molecules, but also play a role in allowing air molecules to quickly enter and exit the micropores, so that the activated carbon sound-absorbing material has a good The ability to respond to changes in air pressure. Figures 1 and 2 use different carbon-to-oxygen mass ratios as variable factors to show the changes in the reduction effect of micropores, mesopores, cumulative pore volume, and resonance frequency f ₀ . It can be seen from Fig. 2 that as the vibration frequency increases, the impedance first increases and then decreases. The frequency at which the impedance reaches the maximum value is the resonance frequency (f ₀ ). As the carbon-to-oxygen mass ratio increases, its resonance frequency f ₀ gradually decreases, indicating that the higher the carbon-to-oxygen mass ratio, the activated carbon sound-absorbing material has a better effect of reducing the resonance frequency. Fig. 3 is a graph of cumulative pore volume when the carbon-to-oxygen mass ratio is 15. As shown by the solid line in FIG. 3, the pore diameter of the micropores is mainly distributed in the range of 0.7-1.3nm, and the cumulative pore volume of the pores whose pore diameter is below 2nm is 0.53ml/g, and the mesopore pore diameter is mainly distributed Between 2-3.5nm, and its total cumulative pore volume is 0.83ml/g.

Preferably, mesopores with pore diameters in the range of 2-3.5 nm account for 60-65% of the total mesopore content. When the pore diameters of a large number of mesopores are concentrated in a narrow range, the higher the degree of perfection of the mesopores, the cumulative pore volume shows an upward trend, and the adsorption-desorption effect on air is better. Thus, the activated carbon sound-absorbing material can exhibit a better equivalent capacity expansion effect. In a preferred embodiment, the mesopores with a pore diameter of 2-3.5 nm are 60-65% of the total mesopores, thereby achieving the above-mentioned effect of improving the adsorption and desorption performance. If the pore diameters of a large number of mesopores are concentrated in a pore size range larger than 5 nm, the difference between the pore diameters of the mesopores and the micropores is large, resulting in uneven communication between the mesopores and the micropores. As a result, the resistance of the air molecules into and out of the micropores and rapid flow in the mesopores increases, which affects the acoustic performance of the activated carbon sound-absorbing material.

Preferably, the activated carbon sound-absorbing material is configured to have an adsorption amount of nitrogen greater than or equal to 0.05 mmol/g. This ensures that the activated carbon sound-absorbing material has sufficient air absorption and desorption performance to meet the needs of equivalent expansion cavity space.

For the two-dimensional graphite layer and/or three-dimensional graphite crystallite structure contained in the activated carbon material, it mainly affects the pore structure formed in the material. The more the content of the above two structures in the material, the more uniform the pore structure formed by the material after the carbonization process and the smaller the pore diameter of the pore structure, so that the activated carbon sound-absorbing material can produce a good effect of reducing the resonance frequency.

Alternatively, the activated carbon sound-absorbing material may be made of amorphous activated carbon particles. The amorphous activated carbon particles contain a chaotic layer structure formed by the accumulation of molecular fragments of two-dimensional graphite layers and/or three-dimensional graphite crystallites in an irregular form. There are a large number of irregular bonds on the edges of the two-dimensional graphite layer structure and three-dimensional graphite crystallites. Irregular bonds can form a tight connection between the two-dimensional graphite layer structure and the three-dimensional graphite crystallites, and interweave to form a pore structure. The valence electrons of carbon have sp ² hybrid orbitals and sp ³ hybrid orbitals, thereby forming a hexagonal carbon network plane. Activated carbon particles stacked and formed in this irregular form can form a fine and rich pore structure to meet the structural requirements of the activated carbon sound-absorbing material for the pore structure.

Preferably, the particle size of the two-dimensional graphite layer and the three-dimensional graphite crystallites is less than 30 nanometers. If the particle diameters of the two-dimensional graphite layer and the three-dimensional graphite crystallites are within the above range, a uniform and fine pore structure can be better formed after random accumulation. On the one hand, it is more conducive to the performance of activated carbon sound-absorbing materials to absorb and release air. On the other hand, it can improve the structural uniformity and stability of amorphous activated carbon particles, and improve the structural strength of products made of activated carbon sound-absorbing materials.

Optionally, the amorphous activated carbon particles themselves may be one or more of spherical, quasi-spherical, flake-shaped, or rod-shaped structures. For example, after spherical carbon particles are used to form activated carbon sound-absorbing particles, a more uniform and fine pore structure can be formed between the carbon particles, thereby improving the acoustic performance of the activated carbon sound-absorbing particles. The use of flake-shaped carbon particles can improve the structural stability of activated carbon sound-absorbing particles and reduce the risk of powdering and damage. At the same time, since the carbonization process of the sheet-shaped amorphous activated carbon particles is simple and the cost is low, the sheet-shaped amorphous activated carbon particles are preferred from an industrial application perspective.

Optionally, the particle size of the amorphous activated carbon particles ranges from 0.1 to 100 microns. The particle size of the amorphous activated carbon particles will affect its own bulk density, and the size of the bulk density will affect the performance of air absorption.

If the particle size of amorphous activated carbon particles is too small, it will cause a significant increase in bulk density. Under a certain volume, the mass of amorphous activated carbon particles that can be filled is relatively reduced, resulting in a weakening of the performance of reducing the resonance frequency. If the particle size of the amorphous activated carbon particles is too large, the bulk density will be significantly reduced. Under certain volume, bulk density is too large will lead to the energy consumed when the forced vibration acoustic space the particles is reduced, the air acoustic compliance (C _ma) is equivalent to the volume of the sound box apparatus is reduced, but also Will reduce the performance of reducing the resonance frequency.

Preferably, the particle size of the amorphous activated carbon particles ranges from 0.2 to 20 microns, and within this range, the prepared activated carbon sound-absorbing particles can exhibit a good effect of reducing the resonance frequency f ₀ .

Correspondingly, the selectable range of the bulk density of the amorphous activated carbon particles is 0.15-0.8 g/cm ³ , preferably, the bulk density is 0.25-0.55 g/cm ³ . The size of the bulk density can also be adjusted by factors such as the shape and carbon content of the amorphous activated carbon particles.

4 and 5 show the degree of decrease in bulk density and resonance frequency f ₀ when the particle diameters of the amorphous activated carbon particles are 0.05, 1, 15, and 30 microns, respectively. As shown in Fig. 4, when the particle size of the amorphous activated carbon particles is 1 and 15 microns, the bulk density is 0.51 g/cm ³ and 0.33 g/cm ³ , and the degree of decrease of the resonance frequency f ₀ is 169Hz and 175Hz. As shown in Figure 5, as the vibration frequency increases, the impedance first increases and then decreases. As the particle size increases, its effect on reducing f ₀ tends to increase first and then decrease. It can be seen that when the particle size is too large or too small, the degree to which the resonance frequency f ₀ decreases decreases accordingly.

In particular, for the pore structure of amorphous activated carbon particles including micropores and mesopores, the pore size of the micropores is in the range of 0.5-2 nanometers, and the pore diameter of most micropores is between 0.7-1.3 nanometers. The pore size of the mesopores is in the range of 2-20 nm, preferably, most of the mesopores are between 2-3.5 nm.

In amorphous activated carbon particles, the pore size of the micropores is limited to a small size, so that the particles can contain sufficient and large number of micropores, on the one hand, increase the total cumulative pore volume of the particles, on the other hand, they can improve the air molecules Adsorption capacity. A large number of micropores with small pore diameters can adsorb a large number of air molecules and improve the acoustic performance of the activated carbon sound-absorbing particles. The limitation of the pore size of the mesopores to the above range is to provide sufficient flow space for the air molecules so that the air molecules can move quickly when the air molecules need to be quickly sucked into or released from the micropores. Reduces air blockage and micropores. On the other hand, if the pore size of the mesopores is too large, the cumulative pore volume of the amorphous activated carbon particles will be reduced, resulting in a decrease in the air absorption performance of the entire particles.

Preferably, the cumulative pore volume of the amorphous activated carbon particles ranges from 0.6 to ⁵ cm ³ /g. The cumulative pore volume of amorphous activated carbon particles significantly affects the effect of sound-absorbing particles on reducing the resonance frequency. When the cumulative pore volume is less than 0.4 cm ³ /g, the absorption and desorption ability of air-absorbing particles to air molecules is significantly reduced. The lower pore volume prevents air molecules from smoothly entering and exiting the amorphous activated carbon particles, and the particles cannot absorb air molecules in large quantities. However, when the cumulative pore volume increases to 0.7 cm ³ /g, the content of mesopores rises, making the particles satisfy the need for rapid entry and exit of air molecules. The response speed for adsorption and desorption of air molecules has increased significantly, and the equivalent expansion ratio for the enclosure of the sounding device has increased significantly. After the cumulative pore volume continues to increase, the content of micropores also increases accordingly, and the amount of air molecules adsorbed by the particles also increases significantly. This can better play a role in reducing the resonance frequency.

In particular, the cumulative pore volume of amorphous activated carbon particles is not likely to be too high. If the pore volume is too high, it may cause problems such as difficulty in adhesion and a decrease in the structural reliability of the activated carbon sound-absorbing particles. The increase in the amount of adhesive caused by this problem will cause the content of amorphous activated carbon particles in the activated carbon sound-absorbing particles to decrease, which will affect the acoustic performance of the particles.

Preferably, the cumulative pore volume of the amorphous activated carbon particles ranges from 0.8 to ² cm ³ /g. Within this range, activated carbon sound-absorbing particles can play a good acoustic performance, and there will be no problems such as reduced structural reliability and reduced content of amorphous activated carbon particles.

Further, the ratio of the cumulative pore volume of the micropores to the cumulative pore volume of the mesopores is in the range of 0.05-20. Preferably, the ratio between the two ranges from 0.1 to 5, for example, the above ratio can be selected as 1 or 2. For different activated carbon sound-absorbing particles with the same mass, the higher the ratio of the cumulative pore volume of micropores to the cumulative pore volume of mesopores, the stronger the adsorption and desorption performance of air molecules. This performance characteristic is mainly reflected in that the micropores can provide a larger volume for absorbing air molecules, so that the larger the equivalent expansion magnification of the cabinet of the sound generating device. The better the effect of reducing the resonance frequency. However, in the technical solution of the present invention, the ratio of the above two does not exceed 20. After the ratio exceeds 20, the effect of the activated carbon sound-absorbing particles to reduce the resonance frequency drops sharply. The reason for this is that the above-mentioned ratio is too large to indicate that the content of micropores is too high, and the size of most of the pore structure of the activated carbon sound absorbing particles is too small, thereby hindering the convection of air and preventing the air molecules from entering and exiting the activated carbon sound absorbing particles. In turn, it affects the propagation of sound waves, and its reducing effect on f ₀ is sharply reduced.

Optionally, the specific surface area of the amorphous activated carbon particles is in the range of 1000-3000 m ² /g. Preferably, the specific surface area of the amorphous activated carbon particles is in the range of 1500-2800 m ² /g. Within a certain range, the specific surface area of amorphous activated carbon particles has a positive correlation with its cumulative pore volume. The larger the specific surface area, the larger the cumulative pore volume. Within an appropriate range, the larger the cumulative pore volume, the greater the adsorption capacity of the amorphous activated carbon particles to air, and the better the effect of reducing f ₀ .

Preferably, the amorphous activated carbon particles include hydrophobic amorphous activated carbon particles. The surface of the hydrophobic activated carbon particles does not contain hydrophilic groups such as carboxyl groups, hydroxyl groups, and amino groups. The use of hydrophobic amorphous activated carbon particles can reduce the content of impurities in the activated carbon sound-absorbing particles. On the one hand, the hydrophobicity of the particles can prevent the pore structure of the particles from adsorbing and bonding during the processing of bonding and granulation. Agent. In addition, for the finished activated carbon sound-absorbing particles, the hydrophobicity of the particles can reduce the absorption of moisture in the air by the particles, and avoid problems such as clogging of the pore structure of the activated carbon sound-absorbing particles by the liquid. Reduced the risk of activated carbon sound-absorbing particles in the process of long-term use, due to the absorption of water, adhesives and failure.

The invention also provides an activated carbon sound-absorbing particle, which is formed by mixing and granulating amorphous carbon particles and a polymer adhesive. The high-molecular polymer adhesive binds powdery amorphous activated carbon particles into activated carbon sound-absorbing particles that are convenient for filling and application. In particular, micron-sized pores can also be formed between the amorphous activated carbon particles bound together, which further improves the air absorption and release capacity of the activated carbon sound absorbing particles.

Optionally, the particle size range of the activated carbon sound absorbing particles is 50-1000 microns. The particle size of the activated carbon sound-absorbing particles has an influence on the packing density of the particles, the content of the binder and other factors, which in turn affects the effect of reducing the resonance frequency f ₀ .

If the particle size of the activated carbon sound-absorbing particles is less than 50 microns, the strength of the activated carbon sound-absorbing particles itself relatively decreases. After it is applied to the box of the sound-generating device, the vibration of the air and the change of air pressure become more likely to cause the activated carbon sound-absorbing particles to powder and break. This kind of problem will seriously affect the effect of particles to reduce the resonance frequency, and may affect the reliability of the sounding device.

If the particle size of the activated carbon sound-absorbing particles is greater than 1000 microns, the volume of the particles is relatively large, and the gap between the particles increases significantly. When such activated carbon sound-absorbing particles are placed in the box of the sound-generating device, the packing density of the particles is significantly reduced. Correspondingly, within the unit volume of the box, the amount of activated carbon sound absorbing particles that can be filled is relatively decreased. Therefore, the amount of substances that can produce a virtual capacity expansion effect is reduced, and the effect of reducing the resonance frequency f ₀ is weakened.

Therefore, the particle size range of the activated carbon sound absorbing particles is kept in the range of 50-1000 microns, which can basically meet the performance requirements of reducing the resonance frequency f ₀ . Preferably, the particle size of the activated carbon sound absorbing particles is between 100-450 microns. For example, the particle size is 200, 250 microns. Within the above preferred range, the performance of reducing the resonance frequency f ₀ reaches an optimal level. The particle size range of the activated carbon sound-absorbing particles and the particle size range of the amorphous activated carbon particles can be designed in coordination. For example, optionally, the particle size range of the activated carbon sound absorbing particles is 50-1000 microns, and the particle size range of the amorphous activated carbon particles is 0.1-100 microns. Preferably, the particle size range of the activated carbon sound absorbing particles is 100-450 microns, and the particle size range of the amorphous activated carbon particles is 0.2-20 microns. Through the control of the particle size, the best packing density and the effect of reducing the resonance frequency can be achieved.

The present invention also provides an optional type of the high-molecular polymer adhesive, the high-molecular polymer adhesive is configured to ensure that the shape and structural stability of the activated carbon sound-absorbing particles are as low as possible Destroy and block the pore structure in amorphous activated carbon particles.

Optionally, the polymer adhesive includes at least one of polyacrylic acid esters, polyvinyl alcohols, polystyrenes, polyvinyl acetates, latexes, and polyolefin adhesives . The above polymer adhesive can also be made into activated carbon sound-absorbing particles afterwards and then taken out from the sound-absorbing particles through a degreasing process, thereby leaving a richer pore structure. Preferably, the mass proportion of the polymer adhesive in the activated carbon sound absorbing particles is in the range of 1-10 wt%. If the content of the polymer binder is too high and the amount of amorphous activated carbon particles is reduced accordingly, the performance of absorbing air will be affected. If the content of the polymer adhesive is too low, the manufactured activated carbon sound-absorbing particles are prone to problems such as powdering and crushing, resulting in reduced structural reliability.

In the sound-generating device, under an environment of approximately one atmospheric pressure, the activated carbon sound absorbing particles of the present invention have a high absorption capacity and absorption coefficient for nitrogen molecules and other air molecules. Putting the activated carbon sound-absorbing particles provided by the present invention into the rear acoustic cavity of the micro-speaker can effectively achieve the mid-low frequency resonance frequency f ₀ of the micro-speaker, and its reducing effect is in the range of 0.5-4.5 Hz/mg. The activated carbon sound absorbing particles can change the acoustic compliance of the gas contained in the substantially closed rear acoustic cavity.

The activated carbon sound absorbing particles provided by the present invention are suitable for adjusting the resonance frequency of a substantially closed cavity. Activated carbon sound-absorbing particles filled into the box of the sound-generating device can be equivalent to increasing the damping of the sound-generating device, thereby reducing the resonance intensity. In turn, the peak value of the electrical impedance of the sound emitting device is reduced.

On the other hand, the adsorption and desorption of air molecules by the activated carbon sound-absorbing material provided by the present invention can be performed repeatedly, and the phenomenon of performance degradation due to repeated adsorption and desorption of air molecules will not occur. The activated carbon sound-absorbing material can be used repeatedly for a long time.

The invention also provides a sound generating device. The sound-generating device includes a housing, a vibrating component and the above-mentioned activated carbon sound-absorbing particles. An accommodating cavity is formed in the housing, and the vibration component is disposed in the housing. The activated carbon sound absorbing particles are arranged in the accommodating cavity.

The vibration assembly divides the accommodating cavity into a front acoustic cavity and a rear acoustic cavity. The front acoustic cavity communicates with a sound hole on the housing, and the rear acoustic cavity is basically a closed space. The activated carbon sound-absorbing particles may be disposed in the rear acoustic cavity. Of course, the present invention does not limit the placement of activated carbon sound absorbing particles in the front acoustic cavity to adjust the sound and air flow of the front acoustic cavity.

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, 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)

An activated carbon sound absorbing particle, characterized in that the activated carbon sound absorbing particle is made by mixing amorphous activated carbon particles with a polymer adhesive, and the activated carbon sound absorbing material includes three elements of carbon, hydrogen, and oxygen. The shaped activated carbon particles contain a chaotic layer structure formed by the random accumulation of molecular fragments of two-dimensional graphite layer structure and/or three-dimensional graphite crystallites. The amorphous activated carbon particles have a loose pore structure in which the pore structure includes nanoscale The micropores and mesopores of the activated carbon sound absorbing particles have a particle size range of 50-1000 microns, and the amorphous activated carbon particles have a particle size range of 0.1-100 microns. The sound absorbing particles according to claim 1, wherein the mass ratio of carbon elements in the amorphous activated carbon particles is greater than or equal to 60 wt%, and the mass ratio of carbon to oxygen in the amorphous activated carbon particles is greater than or equal to 3. The sound absorbing particles according to claim 1, wherein the mass ratio of carbon elements in the amorphous activated carbon particles is greater than or equal to 60 wt%, and the mass ratio of hydrocarbons in the amorphous activated carbon particles is greater than or equal to 11. The sound absorbing particles according to claim 1, wherein the particle size range of the activated carbon sound absorbing particles is 100-450 microns, and the particle size range of the amorphous activated carbon particles is 0.2-20 microns. The activated carbon sound absorbing particles according to claim 1, wherein the pore structure has micropores and mesopores, the pore size of the micropores ranges from 0.5-2 nm, and the pore size of the mesopores ranges from 2-3.5 nm . The activated carbon sound-absorbing particles according to claim 1, wherein the cumulative pore volume of the amorphous activated carbon particles is in the range of 0.6-5 cm ³ /g. The activated carbon sound absorbing particles according to claim 1, characterized in that the polymer adhesive includes polyacrylic acid, polyvinyl alcohol, polystyrene, polyurethane, polyvinyl acetate, polybutylene At least one of the two rubber adhesives, the mass ratio of the polymer adhesive in the activated carbon sound absorbing particles is in the range of 1-10 wt%. The activated carbon sound absorbing particles according to claim 1, wherein the amorphous activated carbon particles include hydrophobic amorphous activated carbon particles. The activated carbon sound absorbing particles according to claim 1, wherein the bulk density of the amorphous activated carbon particles is 0.05-0.8 g/cm ³ . A sounding device, characterized in that it includes: A housing with a containing cavity formed in the housing; A vibration component, the vibration component is disposed in the housing; The accommodating cavity is provided with the activated carbon sound absorbing particles according to any one of claims 1-9.

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