close

Вход

Забыли?

вход по аккаунту

?

DESCRIPTION JPH11164396

код для вставкиСкачать
Patent Translate
Powered by EPO and Google
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
financial decisions, should not be based on machine-translation output.
DESCRIPTION JPH11164396
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
piezoelectric speaker used for acoustic equipment and the like and a method of manufacturing
the same.
[0002]
2. Description of the Related Art Since a piezoelectric speaker is a planar body, plane resonance
occurs at a specific frequency, and a strong and weak peak dip appears in the sound pressurefrequency characteristic. Due to the inferior characteristics of the flatness, it is considered
unsuitable for reproducing high-fidelity audio. Therefore, in practice, damping holes and the like
are provided on the front and back surfaces of the diaphragm, and a new resonance system is
added by the acoustic circuit to disperse the peak dip of the intensity, thereby reducing the
unusual peak.
[0003]
In addition, as a support material (edge material) between the diaphragm and the frame, a foam
made of silicon foam resin or the like is cut into a frame shape, and the diaphragm and the edge
material, or different ones are adhered The diaphragm is sandwiched by two edge members and
further crimped by the frame.
13-04-2019
1
[0004]
SUMMARY OF THE INVENTION As described above, in the piezoelectric speaker having a planar
shape, resonance causes a sharp peak dip in the sound pressure frequency characteristic.
Although measures are taken to reduce this resonance with an acoustic circuit, it is necessary to
provide a circuit-necessary volume before and after the diaphragm, which becomes an obstacle
in achieving a thinner unit. Moreover, it is unsuitable from the surface of mass productivity to
incorporate what was produced with another piece, although support materials, such as a
damper material and an edge material, are used. In order to solve the above-mentioned
conventional problems, the present invention provides a piezoelectric speaker using a diaphragm
which prevents resonance, is low in distortion, excellent in flatness and low range reproduction,
and has good assembly operation efficiency, and a method of manufacturing the same. The
purpose is
[0005]
In order to achieve the above object, according to the first piezoelectric speaker of the present
invention, vulcanized rubber is formed in a thin film state on any part of the piezoelectric
element. It is characterized by
[0006]
In the piezoelectric speaker according to the present invention, at least the vulcanized rubber is
selected from a heat-vulcanizable diene rubber, a vulcanizable non-diene rubber, a copolymer
rubber thereof, and a silicone liquid rubber. It is preferable that it is one rubber.
In the piezoelectric speaker of the present invention, preferably, the vulcanized rubber thin film
is at least one selected from a foam and a non-foam.
[0007]
In the piezoelectric speaker according to the present invention, the thickness of the vulcanized
rubber thin film is preferably in the range of 50 to 500 μm. Further, in the piezoelectric speaker
13-04-2019
2
of the present invention, it is preferable that the foaming ratio of the foam is more than 0% and
not more than 300% (that is, 3 times foaming).
[0008]
Next, a second piezoelectric speaker according to the present invention includes at least one
rubber selected from a thermally vulcanizable diene rubber, a vulcanizable non-diene rubber, and
a copolymer thereof at an edge portion of the piezoelectric speaker. Are characterized by being
vulcanized and foamed and bonded to the unit as an edge material.
[0009]
Next, according to the first method of manufacturing a piezoelectric speaker of the present
invention, a predetermined amount is applied to any part of the piezoelectric element of the
piezoelectric speaker using a coating solution containing a vulcanizable rubber, and then heating
is performed. Crosslinking is performed to form a thin film.
[0010]
In the above method, the vulcanizable rubber is at least one rubber selected from a thermally
vulcanizable diene rubber, a vulcanizable non-diene rubber and copolymer thereof, and silicone
liquid rubber. Is preferred.
In the above method, the vulcanizing agent is preferably sulfur.
In the above-mentioned method, it is preferable to add a foaming agent to the coating solution,
and to foam at the time of heat crosslinking to form a thin film.
[0011]
Next, a second method of manufacturing a piezoelectric speaker according to the present
invention is selected from diene rubbers which are thermally crosslinked by addition of a
vulcanizing agent, non-diene rubber materials which can be vulcanized, and copolymers of these.
After applying a predetermined amount to a predetermined position using a solution containing
at least one material, the foamed portion obtained by heating is bonded to the unit as an edge
13-04-2019
3
material. In the above method, it is preferable to apply a predetermined amount of rubber
material to the edge portion of the piezoelectric speaker, and fix it in the unit by placing it on a
frame and performing heat foaming and thermal crosslinking.
[0012]
Next, according to a third method of manufacturing a piezoelectric speaker of the present
invention, a diene rubber which is made heat-crosslinkable by adding a vulcanizing agent to a
rubbery polymer, a vulcanizable non-diene rubber material, and a co-polymer thereof After
screen printing a predetermined amount and shape on a piezoelectric element of a mixed
solution of at least one rubber material selected from polymers and a nonpolar solvent, or a
solution containing the above rubber material with a foaming agent added And a composite
material type diaphragm obtained by drying and crosslinking in an atmosphere of 200 ° C. or
less.
[0013]
Next, according to a fourth method of manufacturing a piezoelectric speaker of the present
invention, a diene rubber which is made heat-crosslinkable by adding a vulcanizing agent to a
rubbery polymer, a vulcanizable non-diene rubber material, and a co-polymer thereof A mixed
solution of at least one rubber material selected from polymers and a nonpolar solvent, or one
obtained by adding a foaming agent to the above resin solution is coated on a piezoelectric
element in a predetermined amount and shape, and the resin is specified What is formed into the
thickness and shape of the is fixed to the diaphragm and the frame.
[0014]
In the above method, at least one rubber material selected from a diene rubber, a vulcanizable
non-diene rubber material, and a copolymer thereof can be made into a heat-crosslinkable
rubber-like polymer by the addition of a vulcanizing agent. Direct heat transfer to the
piezoelectric body is prevented by punching out the unheated sheet to which the foaming agent
has been added into a predetermined shape, stacking the piezoelectric element and the sheet and
frame, thermally compressing it, and thermally foaming it locally. At the same time, it is
preferable to perform adhesion between the frame-edge and the edge-piezoelectric element.
[0015]
Further, in the above method, it is preferable to change the elastic modulus of the edge material
by adjusting the amount of the foaming agent to be added, and to perform acoustic design
13-04-2019
4
suitable for the shape of the frame and the diaphragm.
In the above method, the nonpolar solvent is preferably at least one solvent selected from
toluene, xylene, hexane, ethyl acetate, dimethylformamide (DMF) and dimethylsulfoxide (DMSO).
[0016]
The piezoelectric speaker of the present invention is typified by butadiene-styrene copolymer
(SBR), butadiene-acrylonitrile copolymer (NBR), and chloroprene polymer (CR), which are
thermally crosslinked by addition of sulfur component. Of non-diene rubber or vulcanizable nondiene rubber materials such as ethylene-propylene copolymer (EPM) and ethylene-propylenesmall amount non-conjugated diene copolymer (EPDM) The cross-linked product is dissolved in a
nonpolar solvent such as toluene to use the one adjusted to a predetermined viscosity.
[0017]
By applying the above solution to a piezoelectric speaker piezoelectric plate and using a
composite material in which a thin film stabilized by thermal crosslinking is formed, unnecessary
peak dips and distortions derived from surface resonance are effectively reduced. Sound quality
can be improved.
[0018]
At this time, in addition to the damping effect of the rubber itself, it is also possible to impart a
damping effect due to the thickness to the piezoelectric plate, and partially change the thickness
of the thin film or apply it locally in an effective shape It is possible to give the function of
Due to this damping effect, the unique resonance is dispersed in the surface shape of the
piezoelectric plate, and the peak is reduced.
[0019]
Since the rubber material is adjusted to a solution having a suitable viscosity, it can be applied
using screen printing technology, and can be easily re-applied to change the thickness, so it is
suitable for the speaker's frequency characteristics. Any design can be done.
13-04-2019
5
[0020]
Furthermore, a foaming agent is added to these polymer rubbers, and after application, they are
heated and foamed to form a foam having a plurality of cells inside, thereby giving a damping
effect and imparting rigidity by thickness for braking The effect can be enhanced.
[0021]
The formation of the edge can also be performed by screen printing, and rubber is applied
around the piezoelectric plate with a predetermined width and thickness, and a foaming process
is performed under predetermined conditions.
By adjusting the foaming agent, the expansion ratio can be arbitrarily controlled, and the acoustic
design can be facilitated.
Further, the expansion ratio can be varied by increasing or decreasing the amount of the foaming
additive, and the elastic modulus of the edge material can be arbitrarily adjusted.
If the amount of the foaming agent added is reduced, the elastic modulus is increased, but the
rigidity due to the thickness effect is reduced.
The elastic modulus is lowered by increasing the foaming agent, but the apparent rigidity is
improved by the thickness effect.
Both are opposite physical properties, and it is possible to adjust the amount of amplitude of the
speaker piezoelectric plate by the addition of a suitable foaming agent, and to control it to an
arbitrary sound pressure particularly in the low range.
[0022]
Further, a predetermined amount of rubber is applied to the edge portion of the piezoelectric
plate and installed in the frame, and heat is applied from the outside to foam inside the frame
and the piezoelectric plate is fixed in the frame. In addition, a high viscosity rubber sheeted into a
13-04-2019
6
sheet and punched into a predetermined shape is attached in a state where a gap is provided
between the piezoelectric plate and the frame, and the two are further sandwiched to perform
heat compression bonding. The rubber present alone in the gap serves as a damper, and the
stress applied to the piezoelectric plate is relieved, making it easy to oscillate up and down, not
only to improve the sound quality and flatness but also to reproduce the lower range. It becomes
possible.
[0023]
In the specification of the present invention, the term "piezoelectric substance" means a
piezoelectric substance itself such as PZT (lead zirconate titanate sintered body), for example. It
is called "metal diaphragm" or "diaphragm", and one obtained by bonding the "piezoelectric" and
"metal diaphragm" or "diaphragm" is called "piezoelectric element".
[0024]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method of manufacturing a
piezoelectric speaker according to the present invention will be described with reference to the
drawings.
(Embodiment 1) A thermally crosslinked SBR rubber and toluene are mixed at a weight ratio of 1:
1 and stirred to obtain a polymer rubber solution.
[0025]
The rubber solution was applied to the back surface of a metal diaphragm of a piezoelectric
element of 20 mm in vertical width and 25 mm in horizontal width made of a composite plate of
aluminum and ceramic material so that the thickness after drying was about 100 μm. The
application was performed by screen printing. The screen printing pattern at this time is shown
in FIG. The cross-sectional view of the piezoelectric element after application is as shown in FIG.
After the solution containing the rubber 1 was applied to the entire back surface of the metal
diaphragm 8, it was dried at room temperature for 24 hours and heat cured at 170 ° C. for 15
seconds. The obtained piezoelectric elements were placed on the edge and the frame, and the
acoustic characteristics of the unit were measured. FIG. 1 illustrates a cross section of a unit on
which the piezoelectric plate is mounted. In FIG. 1, 1 is an SBR rubber thin film applied to a metal
diaphragm 8, 2 is a PZT piezoelectric bonded to the back surface of the metal diaphragm 8, 3 is
13-04-2019
7
an edge material for holding the end face of the metal diaphragm 8, 4 Is a frame to follow the
edge material 3. The edge material 3 used was a conventional one obtained by cutting foamed
silicone rubber into a frame shape.
[0026]
Here, SBR rubber is used as rubber 1, but a diene rubber represented by SBR, NBR, CR, or a
nondiene rubber material that can be vulcanized such as EPM, EPDM, or a copolymer thereof is
used. It is also good. Further, although aluminum is used as the metal diaphragm 8, brass or a
stainless alloy represented by 42 alloy may be used other than aluminum. Also, SBR rubber was
applied to the piezoelectric element for which the step of bonding the metal diaphragm 8 and the
piezoelectric body 2 was completed and heat treatment was carried out, but after heat treatment
was applied to the metal diaphragm with SBR rubber May be adhered to the metal diaphragm 8.
[0027]
2 and 3 show the sound pressure-frequency characteristics of the piezoelectric speaker obtained
by the above method. FIG. 2 shows the sound pressure-frequency characteristics of the
conventional piezoelectric speaker diaphragm, and FIG. 3 uses the diaphragm according to the
present embodiment in which polymer rubber is applied to the front of the back surface as the
piezoelectric speaker diaphragm. The sound pressure-frequency characteristic of the case is
shown. Each of the three waveform lines shows the sound pressure-frequency characteristic 5,
the second-order distortion characteristic 6, and the third-order distortion characteristic 7.
[0028]
According to the results, it is confirmed in FIG. 3 that the strong peak at 8.0 kHz is reduced and
the flatness is improved from 35 dB to 20 dB, in particular, the flatness from 6.0 kHz to 20 kHz
is significantly improved. It was done. Moreover, distortion is reduced at 600 Hz and 9.5 kHz.
[0029]
From these results, it has been confirmed that the use of the diaphragm according to the present
embodiment in which the polymer rubber is coated on the front surface of the back is superior to
that of the conventional product.
13-04-2019
8
[0030]
(Embodiment 2) A piezoelectric element made of a composite plate of aluminum and a ceramic
material was prepared.
What added the foaming agent to the heat-crosslinking type SBR rubber was mixed and stirred at
a weight ratio of 1: 1 with toluene to obtain a polymer rubber solution. The rubber solution was
screen-printed on the back surface of the metal diaphragm so that the thickness after drying was
100 μm. The mask pattern at this time is as shown in FIG. This is called screen printing step 1.
In this state, it was dried at room temperature for 1 hour.
[0031]
Next, a polymer rubber solution is prepared by mixing and stirring toluene at a weight ratio of 1:
1 to an SBR rubber which has been adjusted to have a foaming ratio of 2 (100%) by increasing
the addition amount of the foaming agent, and drying it. It adjusted so that thickness might be
set to 250 micrometers and screen-printed by width of 1 mm on the circumference of diaphragm
both sides. The mask pattern at this time is shown in FIG. This process is referred to as screen
printing process 2, and a cross-sectional view of the piezoelectric element obtained in processes
1 and 2 is shown in FIG. The metal diaphragm 8, the PZT piezoelectric body 2, and the SBR
rubber thin film 1 applied to the metal diaphragm are shown. After applying the rubber solution,
the SBR rubber thin film 1 was dried at room temperature for 24 hours and placed in the unit.
[0032]
Next, while the diaphragm coated with rubber was placed in the unit, it was heated at 170 ° C.
for 30 seconds to simultaneously perform foaming and crosslinking. The cross section at this
time is shown in FIG. According to FIG. 4, the composite material diaphragm 8 coated and
foamed with rubber is a foam formed in the metal frame 4 up and down and having a foaming
ratio twice as high as that of the rubber coated on the diaphragm. At 9, it was found that the
sandwich was sandwiched and supported. It was confirmed that this foam functions as an edge
when driven as a piezoelectric speaker unit.
13-04-2019
9
[0033]
Although SBR rubber is used here, diene rubber represented by SBR, NBR, CR, or non-diene
rubber material which can be vulcanized, such as EPM, EPDM, or copolymer thereof may be
used. Further, although aluminum is used as the metal diaphragm 8, brass or a stainless alloy
represented by 42 alloy may be used other than aluminum. Also, SBR rubber was applied to the
piezoelectric element for which the step of bonding the metal diaphragm 8 and the piezoelectric
body 2 was completed and heat treatment was carried out, but after heat treatment was applied
to the metal diaphragm with SBR rubber May be adhered to the metal diaphragm 8.
[0034]
(Embodiment 3) A piezoelectric element made of a composite plate of aluminum and a ceramic
material was prepared. The thermally crosslinked SBR rubber was mixed and stirred with toluene
at a weight ratio of 1: 1 to prepare a rubber solution as a polymer rubber solution. The rubber
solution was adjusted to a thickness of 100 μm on the back surface of the metal diaphragm to
perform screen printing.
[0035]
Furthermore on the back of the diaphragm. A thermally cross-linked SBR rubber to which a
foaming agent was added was formed into a sheet, which was punched into a shape as shown in
FIG. 9 and had a thickness of 50 μm. The obtained sheet was attached to a diaphragm and
further fixed to a frame. At this time, the gap provided between the frame and the diaphragm was
1 mm. A cross-sectional view at this time is shown in FIG.
[0036]
Further, heat compression is locally applied at 200 ° C. for 15 seconds by using a forming jig
10 as shown in FIG. 11 to complete the crosslinking completely, and the diaphragm-edge
material, frame -Glued the edge material. By applying heat locally, destruction and depolarization
of the piezoelectric element can be prevented. A cross-sectional view after molding is shown in
FIG. As in Examples 1 and 2, the SBR rubber was used, but a diene rubber represented by SBR,
13-04-2019
10
NBR, CR, or a non-diene rubber material which can be vulcanized such as EPM, EPDM, or the like.
A copolymer may be used. Furthermore, although aluminum is used as the metal diaphragm 8,
brass or stainless alloy represented by 42 alloy may be used other than aluminum.
[0037]
12 and 13 show the sound pressure-frequency characteristics of the piezoelectric speaker
obtained by the above method. FIG. 12 shows sound pressure-frequency characteristics of a
piezoelectric speaker in which the "edge" of the diaphragm is directly bonded to the frame. 13 is
a piezoelectric speaker diaphragm in which the polymer rubber is applied to the entire back
surface, and the frame and the diaphragm are heat treated by applying a polymer rubber sheet,
thereby simultaneously performing an edge forming and bonding process. The sound pressurefrequency characteristic at the time of using the diaphragm which concerns on is shown. The
three waveform lines show the sound pressure-frequency characteristic 5, the second-order
distortion characteristic 6, and the third-order distortion characteristic 7.
[0038]
According to the results, it is confirmed that the lowest resonance frequency f0 is 1200 Hz in
FIG. 12, while it is reduced to 450 Hz in FIG. The distortion at f0 is also improved to -34 dB in
FIG. 13 but to -34 dB in FIG. Furthermore, the fine peak dip seen in FIG. 12 was not seen in the
characteristics of FIG.
[0039]
From these results, the piezoelectric speaker according to the embodiment of the present
invention is superior in distortion, flatness, and low-range reproduction as compared with the
conventional product by applying the polymer rubber to the front surface of the back surface of
the metal diaphragm. That was confirmed.
[0040]
As described above, in the present invention, a thermally crosslinked rubber polymer rubber
solution in an uncrosslinked state is applied to a metal diaphragm of a piezoelectric element in an
arbitrary shape and thickness. A damping effect is imparted to the diaphragm itself by forming a
thin film vulcanized and stabilized by heat treatment, thereby reducing peak dips on acoustic
characteristics characteristic of a planar piezoelectric speaker, and comparing with the prior art.
13-04-2019
11
Thus, a diaphragm with low distortion and excellent flatness can be obtained.
[0041]
In addition, it can be used as a support material by adding a foaming agent to the rubber polymer
rubber used there and applying it to the edge part of the diaphragm and foaming it, and mass
productivity is improved compared to the conventional punching die support system. , It was
possible to save the waste of material.
[0042]
Brief description of the drawings
[0043]
1 is a cross-sectional view of a piezoelectric speaker unit according to an embodiment of the
present invention.
[0044]
FIG. 2 is a diagram showing sound pressure-frequency characteristics of a piezoelectric speaker
using a conventional diaphragm.
[0045]
FIG. 3 is a diagram showing sound pressure-frequency characteristics of a piezoelectric speaker
using a diaphragm coated with rubber according to an embodiment of the present invention.
[0046]
4 is a cross-sectional view of the piezoelectric speaker unit.
[0047]
5 is a view showing a mask pattern for screen printing.
[0048]
6 is a view showing a screen printing mask pattern.
13-04-2019
12
[0049]
7 is a cross-sectional view after the screen printing step 1 of the same.
[0050]
8 is a cross-sectional view after the screen printing step 2 of the same.
[0051]
Fig. 9 Same shape with punched edge material
[0052]
FIG. 10 A state in which the edge material of FIG. 9 is fixed to a frame and a diaphragm (cross
section along line I-II of FIG. 9)
[0053]
FIG. 11 In the same manner, the edge material is thermally compression molded with a jig (cross
section along line I-II in FIG. 9).
[0054]
Figure 12 Sound pressure-frequency characteristics of a piezoelectric speaker in which the
diaphragm is directly attached to the frame.
[0055]
Fig. 13 Same, sound pressure-frequency characteristics of a piezoelectric speaker in which a
diaphragm is bonded to a frame via rubber.
[0056]
Explanation of sign
[0057]
Reference Signs List 1 SBR rubber thin film 2 coated on a diaphragm 2 PZT piezoelectric 3 edge
material 4 metal frame 5 sound pressure-frequency characteristic 6 secondary distortion
characteristic 7 third distortion characteristic 8 metal diaphragm 9 SBR rubber foam 10 molding
jig
13-04-2019
13
13-04-2019
14
Документ
Категория
Без категории
Просмотров
0
Размер файла
24 Кб
Теги
description, jph11164396
1/--страниц
Пожаловаться на содержимое документа