CN113542986B

CN113542986B - Loudspeaker diaphragm and sound generating device

Info

Publication number: CN113542986B
Application number: CN202010307128.8A
Authority: CN
Inventors: 惠冰; 凌风光; 李春; 刘春发
Original assignee: Goertek Inc
Current assignee: Goertek Inc
Priority date: 2020-04-17
Filing date: 2020-04-17
Publication date: 2023-11-10
Anticipated expiration: 2040-04-17
Also published as: CN113542986A

Abstract

The invention discloses a loudspeaker diaphragm and a sound generating device. The loudspeaker diaphragm comprises a polystyrene-poly (ethylene-butylene) -polystyrene block copolymer foam film layer, wherein the polystyrene-poly (ethylene-butylene) -polystyrene block copolymer foam is a foam prepared by a foaming method from a copolymer consisting of a polystyrene block and a poly (ethylene-butylene) block, the mass percentage of the polystyrene block is 10% -70%, the glass transition temperature of the foam is less than or equal to-20 ℃, and the thermal plasticity temperature of the foam is 80-220 ℃. The foam film layer has foam cells uniformly distributed in the material, so that the overall density of the material is reduced, and the weight of the vibrating film with the same size is reduced. This makes the resilience performance of material better, and the amplitude is bigger, is difficult for leading to the speaker vibrating diaphragm to take place deformation because of self weight.

Description

Loudspeaker diaphragm and sound generating device

Technical Field

The invention relates to the technical field of electroacoustic conversion, in particular to a loudspeaker diaphragm and a sound generating device.

Background

Conventional loudspeaker diaphragms mostly adopt rubber film layers (such as NBR, IIR and the like) or soft polyurethane foam film layers. However, the above materials have poor comprehensive properties, such as high density, poor heat resistance, low elastic recovery, etc., which results in low loudness of the loudspeaker diaphragm and small margin of high and low temperature cycle reliability. Such a speaker diaphragm cannot meet the requirements of high power, water resistance, and high sound quality of a speaker.

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

Disclosure of Invention

An object of the present invention is to provide a new solution for a loudspeaker diaphragm.

According to a first aspect of the present invention, a loudspeaker diaphragm is provided. The loudspeaker diaphragm comprises a polystyrene-poly (ethylene-butylene) -polystyrene block copolymer foam film layer, wherein the polystyrene-poly (ethylene-butylene) -polystyrene block copolymer foam is a foam prepared by a foaming method from a copolymer consisting of a polystyrene block and a poly (ethylene-butylene) block, the mass percentage of the polystyrene block is 10% -70%, the glass transition temperature of the foam is less than or equal to-20 ℃, and the thermal plasticity temperature of the foam is 80-220 ℃.

Optionally, the foaming method adopts a foaming agent, wherein the foaming agent is at least one of nitrogen, carbon dioxide, butane, azo compounds, nitroso compounds, inorganic compounds and diamine compounds.

Optionally, the elongation at break of the foam is more than or equal to 100%.

Optionally, the tensile strength of the foam is 0.1MPa to 50MPa.

Alternatively, the foam has a density of 0.1g/cm ³ -1g/cm ³ The porosity is 10% -90%.

Optionally, the foam has a density of 0.2g/cm ³ -0.8g/cm ³ The porosity is 20% -80%.

Optionally, in the foam, the size of the cells is 10-200 μm.

Optionally, in the foam, the size of the cells is 30-150 μm.

Optionally, the elastic recovery rate of the foam film layer after 10% strain is more than or equal to 80%.

Optionally, the adhesive layer is further included, and the adhesive force between the foam film layer and the adhesive layer is greater than 50g/25mm under the 180 DEG peeling test.

Optionally, the thickness of the foam film layer is 100 μm to 1200 μm.

Optionally, the loudspeaker diaphragm is a single-layer diaphragm, and the single-layer diaphragm is formed by adopting a layer of foam film.

Or the vibrating diaphragm is a composite vibrating diaphragm, the composite vibrating diaphragm comprises two layers, three layers, four layers or five layers of film layers, and the composite vibrating diaphragm at least comprises one layer of foam film layer.

According to a second aspect of the present disclosure, a sound emitting device is provided. The sound generating device comprises a sound generating device main body and the loudspeaker vibrating diaphragm, wherein the loudspeaker vibrating diaphragm is arranged on the sound generating device main body.

According to one embodiment of the present disclosure, the foam film layer, because cells are uniformly distributed inside the material, results in a reduction in the overall density of the material and a reduction in the weight of the same size diaphragm. This makes the resilience performance of material better, and the amplitude is bigger, is difficult for leading to the speaker vibrating diaphragm to take place deformation because of self weight.

Other features of the present invention and its advantages will become apparent from the following detailed description of exemplary embodiments of the invention, 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 plot of loudness (i.e., SPL plot) of a loudspeaker diaphragm at different frequencies than a conventional rubber diaphragm in accordance with one embodiment of the present disclosure.

Fig. 2 is a graph of harmonic distortion testing of a loudspeaker diaphragm and a conventional foam diaphragm in accordance with one embodiment of the present disclosure.

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

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

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

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

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

According to one embodiment of the present disclosure, a loudspeaker diaphragm is provided. The loudspeaker diaphragm comprises a polystyrene-poly (ethylene-butylene) -polystyrene block copolymer foam film layer, wherein the polystyrene-poly (ethylene-butylene) -polystyrene block copolymer foam is a foam prepared by a foaming method from a copolymer consisting of a polystyrene block and a poly (ethylene-butylene) block, the mass percentage of the polystyrene block is 10% -70%, the glass transition temperature of the foam is less than or equal to-20 ℃, and the thermal plasticity temperature of the foam is 80-220 ℃.

In the embodiment of the invention, the mass percentage of the polystyrene block is 10-70%. In the range, the foaming body film layer has excellent glass transition temperature, low temperature resistance and mechanical property.

The higher the glass transition temperature, the greater the mass content of the polystyrene block, the greater the mechanical strength of the material and the poorer the elastic recovery. In this case, the glass transition temperature of the foam is not more than-20 ℃. The glass transition temperature enables the loudspeaker diaphragm to keep a high-elasticity state at normal temperature, and the rebound resilience is good.

Preferably, the glass transition temperature of the foam film layer is from-80 ℃ to-40 ℃. This makes it possible to keep the loudspeaker diaphragm in operation with a good elasticity at a temperature lower than-20 c, so that the sound-producing device exhibits a high sound quality. Meanwhile, the risk of damage to the loudspeaker diaphragm in a low-temperature environment is reduced, and the reliability of the loudspeaker diaphragm is higher.

The foam film layer has bubbles uniformly distributed in the material, so that the overall density of the material is reduced, and the weight of the vibrating film with the same size is reduced. This makes the resilience performance of material better, and the amplitude is bigger, is difficult for leading to the speaker vibrating diaphragm to take place deformation because of self weight.

The foaming method includes a chemical foaming method or a physical foaming method. The chemical foaming method is a method of foaming an elastomer material (e.g., plastic) by generating a gas by a chemical method. The chemical foaming agent added into the elastomer material is decomposed after being heated, so that gas is released, and bubbles are formed in the elastomer forming process; the foaming may also be carried out during the formation of the elastomeric material by means of gases released by chemical reactions between the different components of the elastomeric material.

The physical foaming method is a method of forming bubbles in a material during the molding of the material by physical change of a foaming agent added to the material. The physical foaming method does not affect the chemical properties and molecular structure of the elastomer material, and can form uniform bubbles inside the material.

The foaming method and the foaming agent can be selected by those skilled in the art according to actual needs.

The number of layers of the diaphragm can be set by a person skilled in the art according to actual needs.

In one example, the foaming agent of the foam is at least one of nitrogen, carbon dioxide, butane, an azo compound, a nitroso compound, an inorganic compound, and a diamine compound. The foaming agents described above are all capable of forming uniform bubbles within the elastomeric material.

For example, a foam is formed by supercritical foaming. In the preparation process, firstly, a foaming agent such as supercritical carbon dioxide or nitrogen is injected into a closed container, and the foaming agent and a molten copolymer are fully and uniformly mixed and diffused to form single-phase mixed sol; then, the sol is introduced into a mold cavity or an extrusion die, and a large pressure drop is generated in the sol, so that gas is separated out, and a large number of bubble nuclei are formed. In the subsequent cooling forming process, the bubble nuclei in the sol are continuously grown and formed, and finally the foam is obtained.

For example, the size of the bubble holes is 10 μm to 200. Mu.m. Within this range, the cells are effective in reducing the density of the elastomeric material and maintaining good structural strength, resiliency and temperature resistance. Where cell size refers to the distance between two points of maximum cell size.

Further, the size of the bubble holes is 30 μm to 150 μm. Within this range, the physical properties of the elastomeric material are more favorable.

The size of the cells has a positive correlation with the content of blowing agent. When the content of the foaming agent is low, the arrangement of the cells is loose, the cell wall is thicker, and the change of the size of the cells is small; when the content of the foaming agent is high, cells are closely arranged, cell walls are thinned, and fusion between cells occurs, resulting in an increase in size and a decrease in density of the cells.

In one example, the foam has an elongation at break of 100% or more.

The higher the elongation at break, the higher the polystyrene block content in the elastomer material, the lower the glass transition temperature of the elastomer material, the better the flexibility, the better the low temperature resistance, and the higher the reliability margin of the loudspeaker diaphragm at low temperature.

In the example, the elongation at break of the elastomer material is more than or equal to 100 percent, so that the reliability problems such as membrane rupture and the like are not easy to occur in the use of the loudspeaker diaphragm.

In addition, the elongation at break of the elastomer material is more than or equal to 100%, so that the vibration displacement of the loudspeaker diaphragm is larger, and the loudness is larger. And the reliability and durability are good, and the better the flexibility of the material is. The greater the elongation at break, the greater the ability of the loudspeaker diaphragm to resist failure.

Further, the elongation at break of the foam body is more than or equal to 150%, so that the vibration displacement of the loudspeaker diaphragm is larger, and the loudness is larger.

In one example, the tensile strength of the foam is from 0.1MPa to 50MPa.

The higher the content of polystyrene, the more steric hindrance between molecular chains increases, the rigidity of molecular chains increases, the higher the glass transition point of the elastomer material becomes, the lower the low temperature resistance of the elastomer material becomes, the strength of the elastomer material increases, and the elongation at break decreases. The higher the foaming ratio of the elastomer material, the lower the density, the higher the porosity, the lower the strength and the lower the elongation at break of the elastomer material.

In one example, the foam has a density of 0.1g/cm ³ -1g/cm ³ The porosity is 10% -90%.

The porosity is inversely related to the density of the elastomeric material, the higher the porosity, the lower the density of the elastomeric material.

In the foam, the higher the content of the foaming agent, the higher the expansion ratio, and the lower the density of the elastomer material. While too low a density may result in a decrease in the mechanical strength of the material. In the use, the speaker vibrating diaphragm easily ftractures, is difficult to satisfy the user demand. In the range, the loudspeaker diaphragm has moderate density, high mechanical property and difficult cracking.

Further, the density was 0.2g/cm ³ -0.8g/cm ³ The porosity is 20% -80%. Within this range, the foam has good rebound resilience, a small density, and the resulting loudspeaker diaphragm has a large amplitude and a small polarization.

Preferably, the film layer has a density of 0.1g/cm ³ -0.8g/cm ³ . At this density, compared withIn the rubber ring-folded diaphragm, the ring-folded diaphragm prepared by the foaming body has smaller mass, so that the sound generating device shows higher loudness.

Fig. 1 is a test plot (i.e., SPL plot) of loudness at different frequencies of a loudspeaker diaphragm in accordance with one embodiment of the present disclosure than a conventional rubber diaphragm. Wherein, the abscissa is frequency, unit: hz; the ordinate is loudness, unit: dB (dB). The solid line (curve a in fig. 1) is a test curve of a loudspeaker diaphragm provided by an embodiment of the present disclosure. The dashed line (curve B in fig. 1) is a test curve of a conventional rubber diaphragm. The two diaphragms are both folded ring diaphragms, and the sizes are the same.

As can be seen from the SPL curves, the low frequency performance of the two loudspeaker diaphragms is similar, as shown in fig. 1. The F0 of the sound generating device of the vibrating diaphragm adopting the embodiment of the disclosure and the conventional rubber vibrating diaphragm is 191Hz, but the frequency sensitivity of the sound generating device of the loudspeaker vibrating diaphragm adopting the embodiment of the disclosure is about 1.5dB higher than that of the conventional rubber vibrating diaphragm. It can be seen that the sound generating apparatus employing the loudspeaker diaphragm of the embodiments of the present disclosure has higher loudness and comfort.

Table 1 shows the relationship between the polystyrene block content and the glass transition temperature and tensile strength of the materials.

As can be seen from Table 1, as the content of the polystyrene block increases, the glass transition temperature of the material increases, the low temperature resistance decreases, the mechanical strength increases, and when the content of the polystyrene block is 80%, the mechanical strength of the material increases greatly, but the toughness decreases significantly. In the above range, the performance of the material satisfies the use requirement of the loudspeaker diaphragm.

Polystyrene Block content (wt%)	5	10	40	70	80
						Glass transition temperature (. Degree. C.)	-80	-75	-69	-61	-50
Tensile Strength (MPa)	4.3	5.9	8.5	10.8	17.7

TABLE 1

In one example, the foam film layer has an elastic recovery of greater than or equal to 80% after 10% strain. The loudspeaker has better transient response and lower distortion due to the good rebound resilience of the loudspeaker diaphragm.

Compared with a polyurethane foam vibrating diaphragm, the vibrating diaphragm prepared from the foaming thermoplastic nylon elastomer has a wider elastic area, and the strain generated in the area, after external force is removed, the material has excellent resilience, so that the vibrating diaphragm of the loudspeaker has less swinging vibration in the vibration process, and the tone quality and the listening stability of a sound generating device are better.

Fig. 2 is a harmonic distortion test plot of a loudspeaker diaphragm and a conventional foam diaphragm according to one embodiment of the present disclosure. I.e. THD (Total Harmonic Distortion) curve. Wherein, the abscissa is frequency, unit: hz; the ordinate is THD. The dashed line (curve a in fig. 2) is a test curve of a loudspeaker diaphragm provided by an embodiment of the present disclosure. The solid line (curve C in FIG. 2) is a test curve of the polyurethane foam diaphragm. The two diaphragms are both folded ring diaphragms, and the sizes are the same.

As can be seen from the figures, the speaker diaphragm of the embodiment of the present disclosure has lower THD, and no peak or the like, relative to the polyurethane foam diaphragm. This shows that the loudspeaker diaphragm of the embodiment of the disclosure has better polarization resistance and better sound quality.

In one example, the loudspeaker diaphragm further comprises a glue layer, the adhesion between the foam film layer and the glue layer being greater than 50g/25mm under a 180 ° peel test. Within this range, the strength and durability of the entire loudspeaker diaphragm are significantly improved.

Preferably, the adhesion between the film layer and the glue layer is greater than 100g/25mm (180 ° peel). When the loudspeaker diaphragm is applied to a loudspeaker device, the high cohesive force ensures that the coordination consistency between the loudspeaker diaphragm and the cone basin in the vibration process is good, the sound quality is pure, and the loudspeaker diaphragm still keeps an initial state after long-time vibration, so that the performance stability is high.

In one example, the film layer has a thickness of 50 μm to 2000 μm. The greater the thickness, the higher the structural strength of the loudspeaker diaphragm, but the lower the sound sensitivity; the smaller the thickness, the higher the sensitivity of the loudspeaker diaphragm, but the lower the structural strength. The thickness range of the loudspeaker diaphragm has good sounding sensitivity and high structural strength.

Further, the thickness of the film layer is 100 μm to 1200 μm. In this enclosure, the overall performance of the loudspeaker diaphragm is more excellent.

According to another embodiment of the present disclosure, a sound emitting device is provided. The sound generating device comprises a sound generating device main body and the loudspeaker vibrating diaphragm, wherein the loudspeaker vibrating diaphragm is arranged on the sound generating device main body. The sound generating device is a loudspeaker device.

The sounding device has the characteristics of high loudness, high sensitivity, small distortion and good durability.

In the embodiments of the present disclosure, the key descriptions are different between the embodiments, so long as the different optimization features between the embodiments are not contradictory, the different optimization features may be combined to form a better embodiment, and in consideration of brevity of line text, the description is omitted here.

While certain specific embodiments of the invention have been described in detail by way of example, it will be appreciated by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the 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. The loudspeaker diaphragm is characterized by comprising a polystyrene-poly (ethylene-butylene) -polystyrene block copolymer foam film layer, wherein the polystyrene-poly (ethylene-butylene) -polystyrene block copolymer foam is a foam prepared by a foaming method from a copolymer consisting of a polystyrene block and a poly (ethylene-butylene) block, the mass percentage of the polystyrene block is 10% -70%, the glass transition temperature of the foam is less than or equal to-20 ℃, and the thermal plasticity temperature of the foam is 80-220 ℃; the elongation at break of the foam body is more than or equal to 100%; the tensile strength of the foam is 0.1MPa-50MPa; the density of the foam was 0.1g/cm ³ -1g/cm ³ The porosity is 10% -90%.

2. The loudspeaker diaphragm of claim 1 where: the foaming method adopts a foaming agent, wherein the foaming agent is at least one of nitrogen, carbon dioxide, butane, azo compounds, nitroso compounds, inorganic compounds and diamine compounds.

3. The loudspeaker diaphragm of claim 1 where the foam has a density of 0.2g/cm ³ -0.8g/cm ³ The porosity is 20% -80%.

4. The loudspeaker diaphragm of claim 1 where in the foam has a cell size of 10 μm to 200 μm.

5. The loudspeaker diaphragm of claim 4 where the foam has a pore size of 30 μm to 150 μm.

6. The loudspeaker diaphragm of claim 1 where the foam film has an elastic recovery of greater than or equal to 80% after 10% strain.

7. The loudspeaker diaphragm of claim 1 further comprising a glue layer, the bond between the foam film layer and the glue layer being greater than 50g/25mm under a 180 ° peel test.

8. The loudspeaker diaphragm of claim 1 where the foam film layer has a thickness of 100 μm to 1200 μm.

9. The loudspeaker diaphragm of claim 1 or 8, wherein the loudspeaker diaphragm is a single-layer diaphragm, and the single-layer diaphragm is formed by a foam film layer;

10. A sound generating device comprising a sound generating device body and the loudspeaker diaphragm of any one of claims 1-9, the loudspeaker diaphragm being disposed on the sound generating device body.