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BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
acoustic vibration system member molded of a resin film and a method of manufacturing the
same, and in particular, to improve the material of a diaphragm for a speaker and a microphone,
a speaker center cap and a speaker suspension. And a method of manufacturing the improved
component. [Prior Art] A vibrating plate, a voice coil bobbin, a center cap, a suspension (edge,
damper, etc.) is referred to as a vibration system member for sound, but in the case of a vibrating
plate, mass production in the case of a valve is difficult as is known. Recently, in order to
compensate for defects on the properties and materials, molded resin films are used, and films
such as polyester, polypropylene, polyether sulfone, and polyimide are thermoformed into a
predetermined shape. . On the other hand, looking at the conventional general thermoforming
processing methods for films, there are a vacuum forming method and a mold forming method,
and the vacuum forming method is adopted as a means for forming a thermoplastic film. When
the film is softened by heating the film to the vicinity of the melting point, suction is performed
by a vacuum force, and the softened film is closely adhered to a mold and molded. However,
these resin films conventionally used have the following disadvantages. That is, the abovementioned conventional film has few characteristics with high speed of sound propagation
(hereinafter referred to as "sound velocity") and has less internal loss C and less r tan δ)) and
easily resonates in the used frequency band. Many things get worse. In addition, although a
polypropylene film or the like having a large tan δ is often used, a film having a large tan δ has
a low sound velocity and a low high-frequency reproduction limit frequency. Incidentally, the
velocity of sound and tan δ of a polyimide film (hereinafter referred to as “PI film”) referred
to as a so-called high-performance film in the conventional example, a polyphenylene sulfide film
(hereinafter referred to as rpps film), etc. are as follows. PI film A velocity of sound 2200 m / see
tan δ 0.015 PI film B velocity of sound 17001 II / sec tan δ 0.018 PPS film velocity of sound
1900 m / see tan δ 0.010 So we first have a tensile modulus of substantially 600 kg / mm or
more A rose-oriented aromatic polyamide film has been proposed (JP-B-57-17886, JP-A-6237124, JP-A-6'2-174129, etc.).
However, a film generally referred to as a high performance (heat resistant) film (for example,
the above PI film and the like) and the substantially rose-oriented aromatic polyamide film
proposed earlier by us have a melting point of 550 ° C. It is said that the heating method for
heating these films is extremely inefficient because the heating temperature of these films is
much higher than the decomposition point of the film. Is extremely difficult. Therefore, as
another molding method, molding by a mold molding method in which press deformation of a
molding material (film) can be expected is tried, and a PI film etc. has a glass transition
temperature of 180 ° C. to 350 ° C. Because it is a temperature range that can be heated
relatively easily. When the mold temperature is set appropriately, the resistance to material
deformation is significantly reduced to facilitate molding, and PI films and the like are
commercialized by this molding method. In addition, although the material such as a sheet or
film made of an aromatic polyamide polymer and the properties thereof have a wide range, as a
conventional example in mold molding and the like, it is shown in the embodiment of Japanese
Utility Model Laid-Open Publication No. 57-119986. As described above, an aromatic polyamide
sheet (branded as Nomex, a sheet obtained by forming fibers made of a meta-oriented aromatic
polyamide into a chip and processed into a non-woven fabric), etc. in hot water at 100 ° C. for 6
minutes After the above-mentioned immersion, there is an example which is press-molded in the
shape of a cone with the metallic mold kept heating at about 200 ° C. However, the abovementioned PPTA film does not have a glass transition point, and as described above, the melting
point is a decomposition point of 550 ° C. or more, and a non-woven fabric composed of a metaoriented aromatic polyamide (the trade name Nomex), a film, etc. Extremely high in strength and
elastic ratio and low in elongation as compared with the above, so that it has extremely high
rigidity, is less susceptible to press deformation, and 1 has the property of being easily broken
when forcedly extending the material, Molding is considered to be extremely difficult, and none
has been commercialized practically. In fact, even if press molding is performed using a mold
(male mold or female mold) heated to about 200 ° C., deformation during mold removal,
insufficient molding state, or the film being molded Fracture or deformation after molding
occurs, the yield rate is extremely low, and there are points to be solved for practical use. In
order to cope with this drawback, as described in JP-A-63-278491, as a method of forming a
diaphragm from a substantially para-identical aromatic polyamide sheet as described in JP-A-63278491, a method other than thermoforming is used. Although a molding means was proposed,
in Example 1.2 of this method, the film was cut into a predetermined shape, and the superposed
portion was bonded with an epoxy resin.
However, since the material is discontinuous in the surface direction of the diaphragm in the
method of combining the overlapping portions in this manner, the excellent acoustic
characteristics of the material are once interrupted at that portion, and the epoxy-based resin is
inferior in acoustic characteristics. Due to the sound transmission and the complicated shape of
the joint, it is necessary to apply a reinforcing adhesive such as anti-blip other than pure
adhesion, and as a result, the coating amount of the epoxy resin The physical properties of this
diaphragm are governed by the physical properties (sound velocity of 2000 to 2500 m / sec) of
the epoxy resin as a binder, and there is a possibility that the excellent properties inherent to the
PPTA film may be reduced. In addition, there are drawbacks such as lack of mass productivity
since the joining method requires many man-hours. In Example 3 shown in the above-mentioned
JP-A-63-278491, a resin material is cast on the surface of a conical mold frame, a conical sheet is
obtained through a predetermined process, and the top is cut. It is advantageous in terms of
performance to obtain a cone-shaped diaphragm, but it is difficult to control the thickness of the
sheet, and it is difficult to obtain strength as a diaphragm. The SUMMARY OF THE INVENTION
The first object of the present invention is to solve the above-mentioned drawbacks of the
conventional acoustic vibration system member, and by using a PPTA film, the sound velocity is
extremely fast, and the internal loss tends to occur. An object of the present invention is to
provide a large acoustic vibration system member. A second object of the present invention is to
provide a method of manufacturing an acoustic vibration system member which is excellent in
mass productivity without deteriorating the excellent acoustic characteristics of the PPTA film.
[Means for Solving the Problems] In order to solve the problems, in the present invention, a film
composed of a substantially para-identical aromatic polyamide having a tensile modulus of 600
Kg / mm or more (the above PPTA film) Is press molded with a mold heated to at least 250 ° C.,
and the mold is cooled to an appropriate temperature in the pressed state, and then the vibration
system member for a speaker or a microphone is molded by removing the mold. . As a vibration
system member, it is possible to form a single member such as a diaphragm, a center cap, an
edge member or the like, for example, a voice coil bobbin and a diaphragm, a diaphragm and a
center cap, a diaphragm and an edge, etc. In addition, two or more parts to be adjacent to each
other can be integrally molded. Also, a vibration-based member having a laminated structure can
be obtained by bonding a PPTA film in advance with an adhesive and thermoforming it. It is
possible to efficiently produce a uniform product with PTTA film which has acoustically excellent
properties but is closed for use as a vibration system member because there is no suitable
molding method, which is obtained by this The vibration system member can have excellent
characteristics such as an acoustic velocity of at least 2500 m / sec or more, actually 3000 m /
sec or more, and a tan δ of 0.03.
[Examples] The resin film used in the present invention is substantially composed of
parapolyaromatic polyamide. The para-identical aromatic polyamide refers to a polymer having a
repeating structure in which the para position of the aromatic ring or a position similar thereto is
connected by an amide group. In general, PPTA is most often used, but for the purpose of further
improving moldability etc., for example, 4,4'-diphenylene, 1.4'-naphthalene, 1.5-naphthalene, 2.6-
naphthalene, 414 ' Substitution of the p-phenylene group with substituted substances such as
diphenylene ether, 3.4′-diphenylene ether or their halogens, alkyls and nitros, introduction of
the above-mentioned substituents into the p-phenylene group, etc. It may be Also, poly (pbenzamide) can be used. The film used in the present invention has a Young's modulus of 600 Kg
/ mm "or more, and has an elongation of 20% or more from the viewpoint of fracture or molding
stability in press molding, and further has a density of 1.44. Since it is g / cm3 or less, it is
advantageous to acoustic characteristics. In addition, fillers such as glass fibers, carbon fibers,
carbon particles, carbon whiskers, talc, silica, etc. may be added to adjust the surface property,
moldability, and properties, or voids may be obtained by employing a foaming method or the like.
May be contained. The resin film used in the present invention can be produced, for example, by
the method disclosed in JP-A-57-17886, JP-A-62-37124, JP-A-62-174129, etc. . The embodiment
of the present invention will be described based on FIGS. 1 to 4. FIG. 1 is a cross-sectional view of
the main part of the speaker, in which l is a diaphragm, 2 is a voice coil bobbin, 3 is an edge 3a.
The suspension 3 such as the damper 3b and the like, 4 indicates a center cap, and these are
vibration system members to which the present invention is applied. [Examples] Example 1
Example 1 is an example of molding a cone-shaped diaphragm 1, and as shown in FIG. 2, a male
mold 5 and a female mold provided with cooling medium passages 5a and 6a, respectively. 6.
Heat the female die 6 to 380 ° C. or higher and the male die 5 to 280 ° C. or higher using a
press die consisting of 6 and have a thickness of about 60 μm, Young's modulus of 1020 Kg /
mn + ′ ′, elongation of 34% PPTA film 7 having a density of 1, 402 g / cm 3, an acoustic
velocity of 3400 m / sec, and tan δ of 0.03 g was press-formed at a press speed of about 15 ff 1
m / sec to 20 n + m / see. The choice of press speed is important because the PPTA film used in
this example has a 50% increase in elongation at break but an 80% decrease in break strength
under the above-mentioned heating condition, and the choice of press speed is also important.
Since the molding state immediately after is extremely fragile, the cooling water is passed
through the cooling medium passages 5a and 6a in the as-pressed state, and the molds 5 and 6
are cooled to about 80 ° C. Restore film strength.
That is, after the mold in the as-pressed state is cooled, when the mold is released, the film is
molded into the shape of a predetermined diaphragm, and after removal from the mold, trimming
is performed to cut off the excess portion. The diaphragm 1 was obtained. Although the
embodiment shown in FIG. 2 is an example of manufacturing a cone type diaphragm, it goes
without saying that it is also possible to manufacture a dome type diaphragm and, as shown in
FIG. 3, the diaphragm It is also possible to integrally form at least two or more of the voice coil
bobbin 2, the edge 3a, the damper 3b, and the center cap 4 by the above-described press
molding means. Example 2 Forming is also possible by laminating two or more layers of PPTA
film. In Example 2, two PPTA films having a Young's modulus of 1230 g / mm ′ ′, an
elongation of 23%, and a density of 1.405 g / cI113. Were bonded with an adhesive and
laminated. The application of the adhesive used a well-known coating machine, but this makes it
possible to coat the adhesive very thinly and uniformly, and does not depend on the physical
properties of the adhesive as in the prior art, and Performance could be improved by considering
the material. The physical properties of this laminated film are as follows: sound velocity 3550 m
/ sec. The tan δ was 0.045, and the tan δ could be increased without slowing the sound
velocity. After the diaphragm was molded with this laminate, a part thereof was cut off and the
physical properties were measured. As a result, no significant change was observed as compared
with the physical properties of the laminate before molding. Embodiment 3 As another example
of the laminating method, after molding into a predetermined diaphragm shape, this molded
product may be laminated, and as one embodiment, Young's modulus 1200 kg / mm ",
elongation 24%, A rubber adhesive is applied by spray on one side of two molded articles molded
into a diaphragm shape using a PPTA film with a density of 1.400 g / c- to volatilize the solvent,
and then a hot press is applied. It stuck together by the heat reactivation method. When a part of
the laminated diaphragm was cut off and the physical properties were measured, the sound
velocity was 3000 m / see and tan δ was 0.075, and the sound velocity was slightly reduced,
but it was possible to increase tan δ. As is well known, when metal or the like is deposited on the
front surface or the back surface of the film, the physical properties are improved. Therefore, the
film may be molded with this treatment, or it may be vapor-deposited after molding. Although
the diaphragm is formed in the first embodiment as described above, it is needless to say that
only the suspension of the center cap 4, the edge 3a, the damper 3b, etc. may be formed.
By the way, it is a common means to change the molding temperature condition and the like
depending on the molding shape, but if the thickness of the film is about 25μ, molding is
possible even if the male mold 5 is set around 250 ° C. FIG. 4 is a frequency comparison
characteristic diagram of the speaker A using the diaphragm obtained according to Example 1
and the 3-inch aperture speaker B using the diaphragm made of a conventional PI resin film, and
the vibration according to the present invention It can be seen that the loudspeaker A of the
board is significantly improved in the high region. According to the vibration-based vibration
member of the present invention, the film of para-oriented aromatic polyamide has an acoustic
velocity of 3000 II l / sec or more, tan δ 0, 03 or more, and is extremely excellent in acoustic
characteristics. In terms of the diaphragm, it has extremely high performance compared to the
diaphragm formed by conventional resin film molding, and in particular, one having a sufficiently
larger tan δ than the conventional resin film can be obtained. The stiffness of the portion usually
referred to as the neck portion In can be increased. Therefore, it becomes difficult to generate a
peak in the high frequency reproduction frequency on the characteristic, and the sound velocity
is faster than the conventional resin film diaphragm, that is, the flexural vibration in the high
frequency band is reduced because the elastic modulus is high. The split vibration can be
prevented, and the flatness of this zone can be easily obtained, and the characteristics can be
remarkably improved as apparent from the comparison characteristic diagram of FIG. In addition,
it is possible to adjust the sound quality by molding only the center cap and installing it on a
conventional speaker diaphragm etc. Furthermore, since the creep resistance is extremely good
as a suspension, the speaker suspension for high power It is possible to use it. The manufacturing
method is basically simple and convenient because it can be molded in a wide range of
conventionally used resin film molding, so it is possible to mass-produce very easily, and
therefore, it has higher performance than members such as a conventional diaphragm.
Components can be easily manufactured.
Brief description of the drawings
FIG. 1 is a cross-sectional view of an essential part for explaining a vibration system member of a
speaker, FIG. 2 is a process diagram showing an embodiment of a manufacturing method
according to the present invention, and FIG. FIG. 4 is a frequency comparison characteristic view
of the speaker using the diaphragm obtained in Example 1 and the speaker using the
conventional diaphragm made of resin film, showing various forms of members. .
Diaphragm, 2: voice coil bobbin 3: suspension, 3a: edge 3b, damper, 4: center cap: male,: female,
5a. 6a: Cooling medium passage 7: PPTA film patent applicant Kenwood Co., Ltd. Doha Asahi
Kasei Kogyo Co., Ltd.
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