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JPH06181598

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DESCRIPTION JPH06181598
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
speaker diaphragm which is one of the main components constituting a speaker used in various
audio equipment and a method of manufacturing the same.
[0002]
2. Description of the Related Art As a material used for a speaker diaphragm, paper, metal, resin
or the like is generally used in the mainstream, and in particular, among the speaker diaphragms
using resin, high reliability and low A speaker diaphragm using a polyethylene naphthalate film
(hereinafter referred to as a PEN film) obtained by highly stretching a material composed of
naphthalenedicarboxylic acid and ethylene glycol has been used for the purpose of achieving a
strain ratio.
[0003]
However, since the speaker diaphragm made of the above PEN film is a polymer film, it is easy to
mold in a dome shape, has good productivity, and is inexpensive and can be supplied in large
quantities. However, it has a problem that hardness is lower than that of a speaker diaphragm
using a metal material such as aluminum or titanium, and lack of rigidity makes it easy to
reproduce a low range but to narrow a reproduction range.
[0004]
In order to solve this, there is a method to reduce the film thickness of PEN film, but if this
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method is used, distortion occurs and it not only appears as flicker on the input-proof surface of
the speaker, but also it is high because it lacks rigidity. There was a problem that range playback
was not possible.
[0005]
As another method, there is also a method of solving the above-mentioned problems by coating a
metal such as diamond or alumina on the surface of a speaker diaphragm molded into a desired
shape using a PEN film, but the cost becomes expensive. It had the subject that use was limited.
[0006]
An object of the present invention is to solve the above-described conventional problems, and to
provide a speaker diaphragm with excellent mass productivity, low cost, and high performance,
and a method of manufacturing the same.
[0007]
SUMMARY OF THE INVENTION In order to solve the above problems, the speaker diaphragm
according to the present invention comprises a network-like or turtle-like alumina film having a
thickness of 5 Å to 300 Å on one side or both sides of a PEN film. It is set as the diaphragm for
speakers of the formed structure.
[0008]
[Function] With this configuration, a metal consisting of an alumina film is formed on the surface
of a PEN film in the form of a mesh or a turtle shell, and the formed alumina film is not a uniform
film but a mesh having cracks or gaps. Since the film is an eye-like or turtle-like film, the internal
loss increases due to the effect of the above-mentioned gap.
When forming into a dome-shaped speaker diaphragm, it is possible to easily form the speaker
diaphragm without breaking the hard alumina film, so the rigidity is further increased while the
internal loss is increased, and the distortion is reduced. Thus, it is possible to provide a speaker
diaphragm capable of performing reproduction with higher sound quality.
[0009]
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A loudspeaker diaphragm
according to an embodiment of the present invention will be described below with reference to
the drawings.
FIG. 1 is a cross-sectional view showing the configuration of a speaker diaphragm according to
the present invention. In FIG. 1, 1 is a polyethylene naphthalate film obtained by highly
stretching a material consisting of naphthalene dicarboxylic acid and ethylene glycol with PEN
film. An alumina film 2 having a thickness of about 50 Å is formed on one side of the film by
reactive sputtering in an oxygen atmosphere.
[0010]
The physical property values of the speaker diaphragm of the present invention having the
alumina film 2 formed thereon and the speaker diaphragm made of a PEN film coated with a
uniform and dense alumina film on the surface as a conventional example were compared.
[0012]
As apparent from this (Table 1), it can be seen that the speaker diaphragm according to the
present invention is superior to the conventional product in both the sound velocity and the
internal loss.
[0013]
The alumina film 2 is formed by the reactive sputtering method in an oxygen atmosphere, but
when this method is used, the string-like alumina film 2 starts to be formed from about 5 Å in
film thickness, and this film thickness becomes The alumina film 2 grows into a net-like or turtlelike structure as it increases, and when the film thickness reaches about 300 Å, the alumina film
2 is uniformly and densely formed on the entire surface, and practically It is estimated that the
most effective and effective film thickness is around 50 to 100 Å.
[0014]
Incidentally, FIG. 2 shows an enlarged view of the alumina film when the film thickness of the
alumina film is 50 Å, and FIG. 3 shows the case of 300 Å.
[0015]
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Next, using the material of the speaker diaphragm according to the present invention, a speaker
diaphragm having a desired shape was molded under the conditions of a molding temperature of
210 ° C. and a molding time of 15 seconds, and the speaker was assembled using this.
The output sound pressure frequency characteristic of this speaker is shown in FIG.
[0016]
Also, the third-order distortion characteristics of this speaker and the conventional speaker
assembled similarly using the conventional speaker diaphragm are compared and shown in FIG.
[0017]
Furthermore, the sound quality evaluation results of the present invention and the conventional
speaker are compared and shown in FIG.
[0018]
Thus, in the speaker diaphragm according to the present invention, since the alumina film 2
formed on the surface of the PEN film has a mesh-like or turtle-like structure, it is possible to use
the PEN film for a speaker having a desired shape. The elongation of the alumina film 2 when
formed into a diaphragm is relaxed in the mesh-like or turtle-like gaps of the hard alumina film 2
and does not greatly affect the formability.
Further, it is considered that the hard alumina film 2 has a large number of gaps, and the effect
of the gaps causes a large internal loss.
For this reason, the speaker diaphragm according to the present invention has a high internal
loss due to the alumina film 2 formed on the surface, in addition to the rigid height of the PEN
film 1 of the base material.
Therefore, the speaker using the speaker diaphragm of the present invention can realize clear
sound quality with a delicate high tone range.
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[0019]
In the above embodiment, the formation of the alumina film 2 is performed in the state of a PEN
film, and the case of forming the speaker diaphragm into a desired shape has been described
using this, but the formation of the alumina film 2 is performed by forming the PEN film
Needless to say, the same effect can be obtained even after the speaker diaphragm is made.
[0020]
As described above, the speaker diaphragm according to the present invention can realize clear
and delicate high-quality sound reproduction, and further, by coating an alumina film on the
surface, the heat resistance and the weather resistance can be realized. Because it is possible to
reduce the rate of change in physical properties due to special environments such as, it can be
used not only for indoor use, but also for outdoor use, automotive use, etc. It is of great value.
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