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JPH04287498

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Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
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DESCRIPTION JPH04287498
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
diaphragm for audio equipment used in audio equipment such as speakers and microphones.
[0002]
2. Description of the Related Art A diaphragm used for an audio device such as a speaker is
preferably one capable of reproducing as high a sound as possible in order to reproduce a timbre
faithfully. Conventionally, aluminum alloy, titanium, beryllium, etc. are used as a material of such
a diaphragm for acoustic devices. The diaphragm made of aluminum alloy and titanium has a
sound velocity of about 5200 m / s and about 4900 m / s, respectively. On the other hand, the
diaphragm made of beryllium has a sound velocity of about 11500 m / sec. Therefore, when a
diaphragm is formed using beryllium, it is possible to obtain a speaker excellent in high-pitched
sound reproduction capability.
[0003]
Conventionally, there are two main ways to form a beryllium diaphragm. The first method is the
"powder metallurgy type". In the case of this “powder metallurgy type”, as shown in the
process chart of FIG. 4, first, Be (beryllium) flakes are formed and melted in vacuum to obtain a
Be ingot material. Next, the Be ingot material is chipped and crushed and then sieved to obtain Be
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powder. Next, the Be powder is vacuum hot pressed to form a Be hot press block. Next, this hot
press block is hot-rolled by cross rolling to obtain a cross-rolled plate. Then, the cross-rolled
sheet is subjected to high temperature processing such as hot press forming to obtain a
beryllium diaphragm by forming into a predetermined shape. On the other hand, the second
method is the "vapor deposition type". In the case of this "vapor deposition type", beryllium is
vapor deposited to a predetermined thickness on a substrate such as copper molded in
accordance with the shape of the diaphragm, and then the substrate is etched away to obtain a
beryllium diaphragm of a desired shape.
[0004]
Further, the diaphragm for an acoustic device of this type is composed of a dome-shaped
vibrating portion and an edge portion for supporting the vibrating portion. Generally, these
vibration parts and edge parts are molded separately, and then joined and integrated with each
other by an adhesive or the like. Further, in the case of forming a diaphragm using, for example,
aluminum, it is also performed to integrally form the vibrating portion and the edge portion at
the time of pressing. In order to improve the high-pitched sound reproduction characteristics of
the diaphragm, the strength of the edge portion is an important factor. However, in the
diaphragm in which the vibrating portion and the edge portion are separately formed, the
adhesive layer or the like intervenes between the vibrating portion and the edge portion even if
the characteristics of the edge material are excellent. It is difficult to hold Therefore, in order to
obtain a diaphragm having excellent high-pitched sound reproduction characteristics, it is
desirable to use a material having excellent characteristics such as beryllium and to integrally
form the vibration portion and the edge portion.
[0005]
By the way, among the conventional beryllium diaphragms, the "powder metallurgy type"
beryllium diaphragm has a very high material cost, so it is necessary to use a material different
from beryllium at the edge portion, There is only separately formed one by this. On the other
hand, integral molding has also been attempted in order to take advantage of the ability to form a
"vapor deposition type" beryllium diaphragm into a desired shape according to the shape of the
substrate.
[0006]
SUMMARY OF THE INVENTION However, the above-described conventional acoustic device
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diaphragm has the following problems.
[0007]
First of all, the "powder metallurgy type" beryllium diaphragm is high in material cost of
beryllium material and requires a process such as edge bonding, so its manufacturing cost is
extremely high.
In addition, high sound reproduction characteristics are insufficient because the separately
formed edge portions are joined.
[0008]
On the other hand, although the "vapor deposition" beryllium diaphragm in which the vibrating
portion and the edge portion are integrally molded has a relatively low manufacturing cost and
can obtain excellent high-sound reproduction characteristics, the crystal grains of beryllium by
deposition are used. Are arranged in a column perpendicular to the surface of the deposition
substrate, so the mechanical strength is low. Therefore, cracking due to metal fatigue is likely to
occur, and the resistance to input voltage is poor. In addition, if the thickness of the diaphragm is
increased to improve the mechanical strength, acoustic characteristics such as sound quality are
degraded.
[0009]
The present invention has been made in view of the above problems, and is for an acoustic device
having high mechanical strength, excellent durability to an input voltage, and excellent acoustic
characteristics and capable of reducing the manufacturing cost thereof. It aims at providing a
diaphragm.
[0010]
The diaphragm for an audio device according to the present invention is formed by rolling a
vapor deposited beryllium plate obtained by vapor deposition and pressing the vapor deposited
rolled beryllium plate to form the beryllium. It is characterized in that a vibrating portion in
which the direction of the vapor deposition crystal grain is aligned with the rolling direction, and
an edge portion supporting the vibrating portion are integrally formed.
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[0011]
In the present invention, since the deposited beryllium plate obtained by vapor deposition is
subjected to rolling, its metallographic structure changes, and the crystal direction of the
deposited beryllium plate is aligned with the rolling direction.
For this reason, the deposition-rolled beryllium plate after rolling is excellent in mechanical
strength and ductility.
For example, a vapor-deposited and rolled beryllium sheet has a tensile strength approximately
doubled and an elongation approximately 10 times greater than that of a vapor-deposited
beryllium sheet prior to rolling. Therefore, since the diaphragm for acoustic equipment in which
the deposition-rolled beryllium plate is formed has high mechanical strength, cracking due to
metal fatigue hardly occurs, and the durability to the input voltage is excellent.
[0012]
In addition, since the deposition-rolled beryllium plate has good strength and ductility, it can be
formed such that the vibrating portion and the edge portion are integrally formed by press
processing or the like, and the edge strength is high. A diaphragm for acoustic equipment having
excellent acoustic characteristics such as sound quality can be manufactured.
[0013]
Furthermore, since the number of manufacturing steps can be reduced by integral molding of the
edge portion, and the above-mentioned deposition-rolled beryllium plate is less expensive than
the beryllium plate obtained by powder metallurgy, the diaphragm for acoustic equipment is
manufactured. The cost can be significantly reduced as compared to the prior art.
[0014]
Embodiments of the present invention will now be described with reference to the attached
drawings.
[0015]
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FIG. 1 is a cross-sectional view of a loudspeaker according to an embodiment of the present
invention.
[0016]
The cylindrical center portion of the center pole 1 made of a magnetic material is disposed
substantially at the center of the speaker, and the lower end portion is extended in a collar shape
to have a large diameter.
A ring-shaped magnet 2 is disposed on the lower end of the center pole 1 so as to surround the
center of the center pole 1.
A ring-shaped outer pole 3 made of a magnetic substance is disposed on the magnet 2 so as to
surround the central portion of the center pole 1.
In this case, a magnetic field is formed between the center pole 1 and the outer pole 3 by
appropriately spacing the center pole 1 and the outer pole 3 from each other.
Further, a frame 4 is attached on the outer pole 3, and a beryllium diaphragm 5 is fixed to the
frame 4.
[0017]
The beryllium diaphragm 5 is provided with an edge 5b at the periphery of a dome-shaped
vibrating portion 5a, and the edge 5b is fixed to the frame 4 with the recess of the vibrating
portion 5a facing the center pole 1 side. ing. In addition, a voice coil 6 is provided downward at
the peripheral portion of the vibrating portion 5 a, and the voice coil 6 is disposed between the
center pole 1 and the outer pole 3. An input voltage is supplied to the voice coil 6 from the
outside, and the vibrating portion 5a vibrates in response to the input voltage and the magnetic
field between the center pole 1 and the outer pole 3.
[0018]
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Next, a method of manufacturing the beryllium diaphragm 5 will be described with reference to
the process chart shown in FIG. First, a flat substrate to be deposited with beryllium (Be) is
prepared. Then, beryllium is vapor-deposited on the surface of the substrate to form a beryllium
film. Thereafter, the beryllium film is separated by removing the substrate by etching or the like
to obtain a beryllium plate. Then, the beryllium plate is subjected to rolling processing and then
formed by pressing processing. Thereby, the beryllium diaphragm 5 of a predetermined shape is
completed. In this case, the vibrating portion 5a and the edge portion 5b are formed integrally.
[0019]
In this embodiment, since the beryllium plate obtained by vapor deposition is rolled, the crystal
direction of the beryllium plate is the rolling direction. For this reason, the mechanical strength
and ductility of a beryllium board can be improved. Accordingly, since the beryllium diaphragm 5
formed by vapor deposition rolling beryllium plate after rolling processing has high mechanical
strength, cracking due to metal fatigue hardly occurs, and the durability to the input voltage is
excellent. In addition, since the deposition-rolled beryllium plate has good strength and ductility,
the thickness of the beryllium diaphragm 5 can be reduced, and the edge strength is high, so that
acoustic characteristics such as sound quality can be improved. Furthermore, since the vibrating
portion 5a and the edge portion 5b are integrally formed, both bonding steps are not necessary,
and the deposition-rolled beryllium plate is less expensive than the beryllium plate obtained by
the powder metallurgy method, so the beryllium vibration is The manufacturing cost of the plate
5 can be reduced.
[0020]
Next, the beryllium diaphragm according to this example was actually manufactured, and its
performance was tested. As a result, the beryllium diaphragm according to the present
embodiment has a mechanical strength higher than that of the beryllium diaphragm
manufactured by the conventional vapor deposition method, so that the thickness can be reduced
with the same level of input-resistant design. did it.
[0021]
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FIG. 3 is a graph showing the frequency characteristics of the beryllium diaphragm according to
this embodiment and the conventional example. The horizontal axis shows frequency (Hz) and
the vertical axis shows output sound pressure (dB). The thickness of the beryllium diaphragm
according to the present embodiment is 50 μm, and the thickness of the beryllium diaphragm
according to the conventional example is 75 μm. Moreover, the conditions of a measurement
unit set input voltage to 4V, and used the compression driver (diameter; 100 mm) provided with
the plain tube (diameter; 50 mm, length; 2.5 m).
[0022]
As apparent from FIG. 3, since the beryllium diaphragm according to the present embodiment
can be thinner than the beryllium diaphragm according to the conventional example, the output
sound pressure is 1 to 2 dB in the high sound area. It's getting higher.
[0023]
When a speaker is constructed using these beryllium diaphragms, although some noise is
generated in the case using the beryllium diaphragm according to the conventional example, the
beryllium diaphragm according to the present embodiment is used. The noise was reduced and
the clear sound quality was obtained.
[0024]
As described above, the beryllium diaphragm according to the present embodiment is extremely
excellent in performance as a diaphragm for acoustic equipment.
[0025]
As described above, the diaphragm for audio equipment according to the present invention is
formed by rolling the vapor deposited beryllium plate obtained by vapor deposition and then
pressing the vapor deposited rolled beryllium plate. Since the vibrating portion and the edge
portion are formed to be integrated, their mechanical strength is high.
Therefore, cracking due to metal fatigue is unlikely to occur, and the durability to input voltage is
excellent.
In addition, since the strength of the edge portion is high, it is possible to produce a diaphragm
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for acoustic equipment having excellent acoustic characteristics such as sound quality.
Furthermore, since the number of manufacturing processes can be reduced by integral molding
of the edge portion, and since the deposition-rolled beryllium plate is less expensive than the
beryllium plate obtained by the powder metallurgy method, the manufacturing cost of the
diaphragm for acoustic equipment is compared Can be significantly reduced.
[0026]
Brief description of the drawings
[0027]
FIG. 1 is a cross-sectional view showing a speaker according to an embodiment of the present
invention.
[0028]
FIG. 2 is a process diagram showing a method of manufacturing a beryllium diaphragm
according to an embodiment of the present invention.
[0029]
FIG. 3 is a graph showing frequency characteristics of beryllium diaphragms according to the
present embodiment and the prior art.
[0030]
[FIG. 4] It is process drawing which shows the manufacturing method of the conventional
beryllium diaphragm.
[0031]
Explanation of sign
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