JP3556726B2 - Diaphragm for soft dome speaker - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a diaphragm for a speaker used for a speaker, and more particularly to a diaphragm for a soft dome speaker.
[0002]
[Prior art]
Conventionally, speaker diaphragms have acoustically balanced physical properties, and paper diaphragms made from inexpensive pulp are widely used, but they are completed through a complex manufacturing process using natural cellulose fibers. Therefore, it lacks quality stability and has the disadvantage that heat resistance is high but moisture resistance is extremely poor. Even recently, there are still many paper diaphragms in all-band loudspeakers and the like, but various materials have been developed for, for example, dome speakers for exclusive use in the high-frequency band in order to obtain more stable quality and optimum performance than paper diaphragms.
[0003]
Broadly classified from the development direction, (1) a hard dome diaphragm that increases the high-band resonance frequency and expands the reproduction band with a focus on improving the elastic modulus; and (2) within the reproduction band with a focus on increasing internal loss There is a soft dome diaphragm designed to minimize unnecessary split resonance.
[0004]
Examples of (1) are metals and inorganic materials such as aluminum and titanium having a flexural modulus exceeding 50 GPa (gigapascal), polyester, polyetherimide, polyimide, paraphenylene terephthalate having a flexural modulus of about 2 to 20 GPa. Hard plastics such as amides are used. By adopting these materials, the heat resistance, moisture resistance and weather resistance are often improved together with the improvement of the flexural modulus, but the internal loss tends to be small.
[0005]
As an example of item (2), a method of applying a damping agent to a woven fabric such as cotton, polyester, silk, etc. by applying a sealing agent has been widely used. Lack of quality stability because it is a material.
[0006]
As a single material, a soft plastic such as a nylon resin having a flexural modulus of 0.1 to 1.0 GPa is used. By adopting this material, in addition to the improvement of the internal loss, the quality stability and the moisture resistance are improved, but the heat resistance and the weather resistance are often inferior. In other words, nylon resin is suitable as a basic resin for a soft dome speaker diaphragm because it is resistant to organic solvent adhesive applied at the time of assembling the diaphragm and has high fatigue strength and relatively large internal loss. Conventionally, a plasticizer is blended with the basic nylon resin in order to obtain a flexural modulus of 0.1 to 1.0 GPa and a large internal loss, which are not suitable for the soft dome speaker because of the lack of physical properties. I was The heat resistance and weather resistance are impaired by this plasticizer.
However, there are still many users who prefer the smooth reproduction sound quality obtained by the soft dome, and improvement of the quality stability, heat resistance, and weather resistance of the soft dome is desired.
[0007]
Further, when the bending elastic modulus of a single material is less than 0.1 GPa, sufficient rigidity cannot be obtained as a diaphragm, and the diaphragm is not generally used as a diaphragm that emits sound waves, and is mainly used as an elastic support portion of a speaker. Only the edge of the diaphragm will be used. For such uses, as a single material, an elastomer resin such as a vulcanized rubber, a polyurethane elastomer, an EPDM elastomer, an olefin elastomer, or a polyesteramide elastomer is used.
[0008]
[Problems to be solved by the invention]
However, a conventional diaphragm for a soft dome speaker formed of a woven fabric of cotton, polyester, silk or the like lacks quality stability because it is a composite material having a directional characteristic of a woven fabric and being easily deformed. In addition, the soft dome speaker diaphragm made of a soft plastic material such as nylon resin, which is a single material, not only improves internal loss, but also improves quality stability and moisture resistance, but has heat resistance and weather resistance. There is a problem of inferiority.
[0009]
The present invention has been made in view of such a point, and an object of the present invention is to provide a diaphragm for a soft dome speaker which is excellent in quality stability, heat resistance, and weather resistance and has a large internal loss.
[0010]
[Means for Solving the Problems]
In order to solve the above problems, a diaphragm for a soft dome speaker according to the present invention is an olefin-based diaphragm having a flexural modulus of 0.1 to 1.0 GPa (absolute dry at 23 ° C., ASTM (American Society for Testing and Materials) D790). It is characterized by being composed of an elastomer-modified nylon resin film,
Further, it is characterized by being constituted by an alloy resin film of an olefin-based elastomer resin having a bending elastic modulus of 0.1 to 1.0 GPa (absolutely dried at 23 ° C., ASTM D790) and a nylon resin,
Further, the nylon resin is characterized in that it is 6 nylon or 66 nylon.
[0011]
[Action]
In the present invention, the main nylon resin is modified with an olefin elastomer resin having flexibility and large internal loss to obtain an appropriate flexural modulus and internal loss. While maintaining the high heat resistance of the nylon resin, weather resistance and stability can be dramatically improved.
[0012]
【Example】
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
1 to 3 show an embodiment of the present invention. FIG. 1 is a sectional view of a soft dome speaker diaphragm 1 in which a dome portion 2 and an edge portion 3 are integrally formed. FIG. 2 is a balance drive in which a dome-shaped diaphragm portion 6 and a cone-shaped diaphragm portion 7 are combined. FIG. 3 is a cross-sectional view of the center speaker 9.
[0013]
Next, an embodiment will be described by taking a diaphragm for a soft dome speaker as an example. As a material for the diaphragm, pellets prepared by mixing 3% of a master batch of carbon pigment with olefin-based elastomer-modified 6 nylon resin manufactured by DuPont and trade name of ZYTEL FN727 are formed by a film forming machine to have a thickness of 0%. A .13 mm film was obtained. This film has a flexural modulus of 0.7 GPa (absolute dry at 23 ° C., ASTM D790), a specific gravity of 1.0 (ASTM D-792), a melting point of 220 ° C. (ASTM D-3418), and an internal loss of 0.1 (by vibrating reed method). In-house measurement).
Further, after heating an iron-made metal mold accurately processed into the shape of a diaphragm for a soft dome speaker to a temperature of 180 ° C., the above-mentioned 0.13 mm film was sandwiched and pressed with a force of about 5 kN for 10 seconds. The temperature was lowered to 110 ° C., the mold was opened, the molded product was taken out, and a diaphragm for a soft dome speaker having a voice coil diameter of φ25 was obtained.
[0014]
At the same time, as a comparative example, a conventionally used nylon resin Supronyl manufactured by Hoechst was formed into a 0.13 mm film under the same conditions. However, since Supronyl has a lower heat deformation temperature than the film of the example, the mold temperature at the time of pressing was 130 ° C., and the mold temperature at the time of removal was 70 ° C.
The diaphragm may be formed by molding a film or by molding a molten resin into a dome-shaped mold using an injection molding machine.
[0015]
These two types of soft dome speaker diaphragms are incorporated into a speaker, and the frequency characteristics are measured. Then, after taking out a heat resistance test in a high temperature bath at a temperature of 85 ° C. for 96 hours, take out the sample, return it to room temperature, and measure the frequency characteristics again. did.
That is, FIG. 4 is a diagram showing frequency characteristics before and after a heat resistance test of the speaker using the soft dome speaker diaphragm according to the embodiment, and FIG. 5 is a heat resistance test of the speaker using the soft dome speaker diaphragm in the conventional example. It is a figure showing the frequency characteristic before and behind.
[0016]
In the figure, the solid line A is the frequency characteristic before the heat resistance test according to the example, and the broken line B is the frequency characteristic after the heat resistance test. The solid line C shows the frequency characteristics before the heat resistance test according to the conventional example, and the broken line D shows the frequency characteristics after the heat resistance test.
When comparing the frequency characteristics of the two types of soft dome speaker diaphragms before the heat resistance test, that is, the solid line A and the solid line C, there is no significant difference. It turns out that it has initial performance equivalent to a board.
[0017]
Next, comparing the frequency characteristics after each heat resistance test, the broken line D of the conventional soft dome speaker diaphragm of FIG. 5 is 10 kHz to 15 kHz with respect to the broken line B of the soft dome speaker diaphragm of the embodiment of FIG. It fluctuated greatly in the band, and it was confirmed that the soft dome speaker diaphragm according to the example had excellent heat resistance. Further, as a result of observing the speaker after the heat resistance test, it was found that the shape of the dome portion of the conventional diaphragm for a soft dome speaker caused thermal deformation and the resin was cured.
[0018]
FIG. 6 compares the changes in tensile elasticity (in-house measured by the vibration lead method) of the resin film used for the soft dome speaker diaphragm according to the example and the conventional soft dome speaker diaphragm in the ultraviolet irradiation acceleration test. FIG. To confirm the weather resistance of both diaphragms, a 0.13 mm film before molding was subjected to an ultraviolet irradiation acceleration test using a single-arc carbon sunshine weather meter (black panel temperature: 83 ° C.), and the elastic modulus of the film before the test was set to 1 Where the degree of increase in the elastic modulus after the test is expressed as a cure rate by a magnification.
In the figure, the solid line E represents the cure rate with respect to the accelerated test time in the examples, and ○ represents the spot. Dashed line F represents the cure rate with respect to the accelerated test time in the conventional example, and Δ is the spot. Whereas the conventional example hardened up to three times the tensile modulus before the test, and the performance of the loudspeaker changed drastically, in the example, it was only 1.4 times and was greatly improved.
[0019]
In this way, it is possible to obtain quality stability with a single material instead of a composite material in which a woven fabric is formed and a damping agent that serves as a sealant is applied. This makes it possible to greatly improve the reliability of the diaphragm for a soft dome speaker, thereby making it possible to make use of the inherent sound quality.
In particular, the present invention can be applied to an in-vehicle speaker, an outdoor speaker, and the like, which cannot be used with a conventional nylon-based resin diaphragm.
Note that the present invention is not limited to a dome-shaped diaphragm, and can be applied to a cone-shaped or balance-drive-type diaphragm.
[0020]
【The invention's effect】
As described above, the diaphragm for a soft dome speaker according to the present invention has a bending elastic modulus of 0.1 to 1.0 GPa, and is made of an olefin-based elastomer-modified nylon resin film.
A single material can provide quality stability, while at the same time maintaining the high heat resistance inherent in nylon resin, dramatically improving weather resistance and stability. It can be applied to speakers and the like.
[Brief description of the drawings]
FIG. 1 is a sectional view of a soft dome speaker diaphragm in which a dome portion and an edge portion are integrally formed in an embodiment of the present invention.
FIG. 2 is a cross-sectional view of a balance drive type speaker diaphragm in which a dome-shaped diaphragm and a cone-shaped diaphragm are combined in an embodiment of the present invention.
FIG. 3 is a sectional view of a center cap according to an embodiment of the present invention.
FIG. 4 is a diagram illustrating frequency characteristics of a speaker using a diaphragm for a soft dome speaker according to the present invention before and after a heat resistance test.
FIG. 5 is a diagram showing frequency characteristics before and after a heat resistance test of a speaker using a soft dome speaker diaphragm in a conventional example.
FIG. 6 is a diagram comparing changes in the tensile elasticity of a resin film used for a diaphragm for a soft dome speaker according to the present invention and a resin film used for a diaphragm for a soft dome speaker in a conventional example in an ultraviolet irradiation acceleration test.
[Explanation of symbols]
Reference Signs List 1 diaphragm for soft dome speaker 2 dome part 3 edge part 5 diaphragm diaphragm for balance drive type 6 dome diaphragm part 7 cone-type diaphragm part 9 center cap

Claims (3)

A diaphragm for a soft dome speaker, comprising a olefin-based elastomer-modified nylon resin film having a flexural modulus of 0.1 to 1.0 GPa (23 ° C., absolutely dry, ASTM D790). A diaphragm for a soft dome speaker, comprising an alloy resin film of an olefin-based elastomer resin and a nylon resin having a flexural modulus of 0.1 to 1.0 GPa (23 ° C., absolutely dry, ASTM D790). The nylon resin is claimed in claim 1 or 2 soft dome loudspeaker diaphragm, wherein it is 6 nylon or 66 nylon.

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