close

Вход

Забыли?

вход по аккаунту

?

DESCRIPTION JP2011228881

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 JP2011228881
The present invention provides a compact electroacoustic transducer suitable for mounting on an
electronic device at wide directivity and high sound pressure level. An electro-acoustic transducer
100 includes a plurality of piezoelectric film diaphragms 1 having electrodes formed on both
sides of a piezoelectric film that vibrates according to the state of an electric field, and the
plurality of piezoelectric film diaphragms 1 are arranged in a polyhedron shape. doing. Each
piezoelectric film diaphragm 1 is inserted into the opening formed on each surface of the
polyhedral frame 2. [Selected figure] Figure 1
Electro-acoustic transducer and electronic device
[0001]
The present invention relates to a compact electroacoustic transducer capable of being mounted
on an electronic device such as a portable telephone and having a wide directivity and high
sound pressure level, and an electronic device equipped with the electroacoustic transducer.
[0002]
As mobile phones have become more sophisticated, models that appeal to the AV (Audio / Visual)
function have been actively developed.
In addition, the miniaturization of mobile phones is in progress. Then, with the advancement of
AV functions, the demand for applications such as moving image reproduction has become high,
14-04-2019
1
and a small-sized electroacoustic transducer having a large volume and wide directivity is
required as an acoustic component.
[0003]
As a technology for increasing the volume of the electroacoustic transducer, as disclosed in
Patent Document 1, there is a technology for arranging a plurality of electrodynamic speakers.
However, in the technology disclosed in Patent Document 1, since the size of the electroacoustic
transducer is significantly increased because a plurality of electrodynamic speakers are disposed,
it is not suitable for mounting on an electronic device such as a cellular phone. . In Patent
Document 2, the main speaker and the microphone are disposed on the same plane, and the
microphone is used as a speaker when sound is not collected by the microphone, and the sound
is amplified by the interference between the sound emitted from the microphone and the sound
emitted from the main speaker Technology is disclosed. However, in the technology disclosed in
Patent Document 2, there is a problem that the reproduction of a large volume is insufficient
because the sound pressure emitted from the microphone is small compared to the sound
pressure generated from the main speaker.
[0004]
On the other hand, as a technology for achieving the wide directivity of the electroacoustic
transducer, as disclosed in Patent Document 3, there is a technology in which a plurality of
electrodynamic speakers are arranged in multiple planes. However, in the technique disclosed in
Patent Document 3, the size of the electroacoustic transducer is significantly increased because a
plurality of electrodynamic speakers are arranged in the same manner as the technique disclosed
in Patent Document 1, and therefore, the mobile phone etc. Not suitable for installation in
electronic devices. On the other hand, Patent Document 4 discloses a technique using a
piezoelectric film diaphragm having a curved surface. According to Patent Document 4, by using
a piezoelectric film diaphragm, it is possible to reproduce high sound pressure level and wide
band.
[0005]
JP, 2009-111836, A JP, 2002-281135, A JP, 10-341493, A JP, 2003-259489, A
[0006]
14-04-2019
2
As described above, in the technology of arranging a plurality of electrodynamic speakers
disclosed in Patent Document 1 and Patent Document 3, there is a problem that the size of the
electroacoustic transducer increases.
Further, the technology disclosed in Patent Document 2 has a problem that the sound pressure
level is insufficient. On the other hand, in the technique disclosed in Patent Document 4, since
the piezoelectric film diaphragm having a curved surface is used to obtain a high sound pressure
level, there is a problem that the size of the electroacoustic transducer increases. In particular, in
a small electronic device such as a portable telephone, there is a possibility that the piezoelectric
film diaphragm having a curved surface as disclosed in Patent Document 4 can not be mounted
because the size and thickness of the device are strictly limited.
[0007]
The present invention has been made to solve the above-mentioned problems, and it is an object
of the present invention to provide a small-sized electroacoustic transducer suitable for mounting
on an electronic device such as a cellular phone with wide directivity and high sound pressure
level. I assume.
[0008]
The electroacoustic transducer of the present invention is characterized by including a plurality
of piezoelectric film diaphragms in which electrodes are formed on both sides of a piezoelectric
film vibrating according to the state of an electric field, and the plurality of piezoelectric film
diaphragms are arranged in a polyhedron shape. It is said that.
[0009]
According to the present invention, by arranging a plurality of piezoelectric film diaphragms in a
polyhedron shape and emitting sound waves from a plurality of surfaces, it is possible to realize a
compact electroacoustic transducer with wide directivity and a large sound pressure level. .
In the piezoelectric film diaphragm arranged in a polyhedron shape, the radiation surface
vibrates by applying a voltage to the electrodes.
14-04-2019
3
In the present invention, since the piezoelectric film diaphragm is used, the mechanical quality
factor (Qm) of the converter is reduced, and the sound pressure frequency characteristics can be
flattened. In the electro-acoustic transducer according to the present invention, since a
piezoelectric film diaphragm is used, parts such as magnets are unnecessary and miniaturization
can be promoted compared to a conventional electrodynamic speaker. Further, in the present
invention, it is not necessary to use a piezoelectric film diaphragm having a curved surface as in
the conventional electroacoustic transducer, and the housing of a polyhedron-shaped electronic
device is used as a frame and plate-shaped piezoelectric on each surface of the frame. Since a
film diaphragm may be disposed, it is suitable for mounting on a small electronic device such as
a cellular phone. Further, the electroacoustic transducer according to the present invention is
excellent in manufacturability and high in impact stability at the time of dropping, and hence is
suitable for mounting on a small electronic device such as a cellular phone.
[0010]
It is an outline view of an electroacoustic transducer concerning a 1st embodiment of the present
invention. FIG. 1 is a cross-sectional view showing a structure of a piezoelectric film diaphragm
according to a first embodiment of the present invention. It is sectional drawing which shows the
polarization direction of the piezoelectric film which concerns on the 1st Embodiment of this
invention. It is a figure which shows the solid crystal ion arrangement | positioning of the
piezoelectric material concerning the 1st Embodiment of this invention. It is sectional drawing
which shows the structure of the flame | frame which concerns on the 1st Embodiment of this
invention. It is a top view which shows the evaluation method of the electroacoustic transducer
based on the 1st Embodiment of this invention.
[0011]
First Embodiment Hereinafter, an embodiment of the present invention will be described with
reference to the drawings. FIG. 1 is an external view of an electroacoustic transducer according
to a first embodiment of the present invention. As shown in FIG. 1, the electro-acoustic
transducer 100 of the present embodiment includes a plurality of piezoelectric film diaphragms
1 vibrating by application of voltage, a frame 2 for fixing the piezoelectric film diaphragms 1, and
a piezoelectric film diaphragm 1, and wires 3a and 3b for supplying a voltage, and terminals 4a
and 4b.
14-04-2019
4
[0012]
FIG. 2 is a cross-sectional view showing the structure of the piezoelectric film diaphragm 1. The
piezoelectric film diaphragm 1 is obtained by forming the upper electrode layer 11 and the lower
electrode layer 12 on each of the main surfaces of the piezoelectric film 10 as shown in FIG. The
piezoelectric film 10 is made of a polymer material having piezoelectric characteristics. When an
electrical signal is applied to the piezoelectric film 10, vibration is generated by the piezoelectric
effect, and a sound wave can be generated. The material of the piezoelectric film 10 is not
particularly limited as long as it is a polymer material having a piezoelectric effect, and examples
thereof include polyvinylidene fluoride (PVDF).
[0013]
As a material of the upper electrode layer 11 and the lower electrode layer 12, a conductive
material such as metal can be used, but preferably silver paste (silver, silver-palladium) can be
used. The thickness of the upper electrode layer 11 and the lower electrode layer 12 is optimally
5 μm to 300 μm. If the thickness of the upper electrode layer 11 and the lower electrode layer
12 is less than 5 μm, the film thickness is thin, so that the film thickness varies in the
manufacturing process, and a sufficient function as an electrode material can not be obtained. On
the other hand, when the thickness of the upper electrode layer 11 and the lower electrode layer
12 exceeds 300 μm, the upper electrode layer 11 and the lower electrode layer 12 restrain the
movement of the piezoelectric film 10, so the amplitude of the piezoelectric film 10 is attenuated.
It will end up. In the present embodiment, as shown in FIG. 3, the upper electrode layer 11 on the
acoustic emission surface (upper surface in FIG. 3) is a positive electrode (+) and the lower
electrode layer 12 on the opposite side is a negative electrode (-). Is formed from the negative
electrode toward the positive electrode.
[0014]
The mechanism of vibration generation of the piezoelectric film diaphragm 1 will be described
below. In the piezoelectric film diaphragm 1 of the present embodiment, vibration is generated in
the piezoelectric film 10 by inputting an electrical signal to the pair of upper electrode layer 11
and lower electrode layer 12. Piezoelectric materials have an effect that a voltage is generated by
strain generated by applying pressure, that is, a piezoelectric effect. Since the piezoelectric effect
is a reversible phenomenon, distortion occurs when a voltage is applied to the piezoelectric
material. The piezoelectric effect is due to the solid crystal ion arrangement of the piezoelectric
14-04-2019
5
material shown in FIG. 4, and the positional deviation of the ions arranged in the lattice-like
crystal on the atom is increased by applying pressure, and one of the crystals is A phenomenon
in which the end is positive and the other end of the crystal is negative, that is, an electric
polarization occurs to generate a voltage. In FIG. 4, 40 is an ion such as Ba <2+>, Pb <2+>, La
<3+>, 41 is an ion such as Ti <4+>, Zr <4+>, and 42 is an oxygen ion. In addition, since the
piezoelectric effect is generated reversibly as described above, when a voltage is applied to the
piezoelectric material, an expansion and contraction movement occurs, which has an effect of
generating vibration. The electroacoustic transducer 100 of the present embodiment generates
vibration in the piezoelectric film 10 using this piezoelectric effect to generate a sound wave.
[0015]
In the present embodiment, the piezoelectric film diaphragm 1 is fixed to the frame 2. The frame
2 has a shape of a polyhedron having a plurality of faces, for example, a shape of a regular
dodecahedron in which 12 regular pentagons are arranged. The piezoelectric film diaphragm 1 is
disposed on each surface of the regular dodecahedron. An opening 20 is formed on each surface
of the frame 2 as shown in FIG. 5A, and a recess 21 for attaching the piezoelectric film
diaphragm 1 is provided around the opening 20 of the frame 2. It is formed. The piezoelectric
film diaphragm 1 is inserted into the opening 20 of the frame 2 as shown in FIG. 5B, and the
edge of the piezoelectric film diaphragm 1 is bonded to the recess 21 of the frame 2. Thereby,
the edge of the piezoelectric film diaphragm 1 is fixed to the frame 2 so as not to cause positional
deviation.
[0016]
When the diaphragm is made of the conventional piezoelectric ceramic, since the piezoelectric
ceramic is a brittle material, breakage is likely to occur in affixing operation and the like, and
assembly is difficult. Since the piezoelectric ceramic is easily broken, the manufacturing cost is
also increased. Furthermore, since the piezoelectric ceramic is easily broken, there is a problem
that the place of use is also limited. On the other hand, since the piezoelectric film 10 is made of
a resin material, it can absorb the impact when it is dropped, and the drop strength of the
electroacoustic transducer 100 can also be improved. Moreover, since the piezoelectric film 10 is
a resin material, it has good processability and can be processed into any shape.
[0017]
14-04-2019
6
The material of the frame 2 used in the electroacoustic transducer 100 of the present
embodiment is not particularly limited, such as metal or resin material, but it is preferable to use
aluminum or stainless steel. By using the metal material of stainless steel or aluminum having
high rigidity for the frame 2, the strength of the frame 2 is increased, so that the portability of
the electroacoustic transducer 100 can be improved. Furthermore, by affixing the piezoelectric
film diaphragm 1 to the highly rigid frame 2, the vibration of the frame 2 generated in driving
the piezoelectric film can be attenuated. That is, the loss of vibrational energy can be suppressed,
and the conversion efficiency from electrical energy to vibrational energy can be improved.
[0018]
The thickness of the frame 2 is preferably 30 μm to 1000 μm. When the thickness of the frame
2 is less than 30 μm, the rigidity of the frame 2 is weakened, and the bonding area of the
piezoelectric film diaphragm 1 is reduced, which is not preferable in manufacturing. In addition,
if the thickness of the frame 2 exceeds 1000 μm, the size of the electroacoustic transducer is
increased, which is not suitable for mounting on an electronic device such as a mobile phone.
[0019]
In the electro-acoustic transducer 100 of the present embodiment, in order to apply an electrical
signal to the piezoelectric film 10, a pair of wires 3a, 3b and a pair of terminals 4a, 4b are used.
One end of the wiring 3a is connected to the upper electrode layer 11 of each piezoelectric film
diaphragm 1 via solder, and the other end of the wiring 3a is connected to the terminal 4a. One
end of the wiring 3b is connected to the lower electrode layer 12 of each piezoelectric film
diaphragm 1 via solder, and the other end of the wiring 3b is connected to the terminal 4b. The
material of the wires 3a and 3b is not particularly limited as long as it is a conductive material
having electrical conductivity, but it is preferable to use a polyurethane-coated copper wire as
the wires 3a and 3b. The material of the terminals 4a and 4b is not particularly limited as long as
it is a conductive material having electrical conductivity, but it is preferable that the terminals 4a
and 4b be covered with an insulating material except for the connection portion with the outside.
As the terminals 4a and 4b, for example, it is desirable to use a flexible substrate.
[0020]
14-04-2019
7
The operation of the electroacoustic transducer 100 of the present embodiment will be described
below. By inputting an electrical signal to the upper electrode layer 11 and the lower electrode
layer 12 of each piezoelectric film diaphragm 1 through the terminals 4a and 4b, the
piezoelectric film 10 of each piezoelectric film diaphragm 1 vibrates to generate sound waves. .
In the electroacoustic transducer 100 according to the present embodiment, the piezoelectric
film diaphragms 1 are arranged in multiple planes, so sound waves are generated from a
plurality of radiation planes, and the sound pressure level is increased. Usually, the sound
pressure level is determined by the pressure change to the air medium and thus depends on the
radiation area and the vibration amplitude. That is, in the present embodiment, the apparent
radiation area can be increased by arranging a plurality of radiation planes three-dimensionally,
which is useful for improving the sound pressure level.
[0021]
Further, in the electro-acoustic transducer 100 of the present embodiment, the sound pressure
level can be increased, and at the same time, flattening of the sound pressure frequency
characteristics can be realized. That is, in the present embodiment, since the diaphragm is
formed of the piezoelectric film 10 having a large mechanical loss, the mechanical quality factor
(Qm) is small compared to the conventional ceramic material, and the sound pressure peak
generated near the resonance point is Since it attenuates, flatter acoustic characteristics can be
realized.
[0022]
Further, in the electroacoustic transducer 100 of the present embodiment, the frequency band to
be reproduced can be expanded. In a normal acoustic element, the sound pressure level rises
from the fundamental resonance frequency or higher, so in order to realize bass reproduction, it
is necessary to reduce the fundamental resonance frequency of the acoustic element. For
example, in a portable telephone, the reproduction band of sound is 100 Hz to 20 kHz, and in
order to realize good reproduction of sound in this band, the fundamental resonance frequency
of the acoustic element needs to be 800 Hz or less. However, since the fundamental resonance
frequency f0 is determined by the load weight m, the rigidity c of the diaphragm, and the length l
of the diaphragm as shown in the equation (1), it is desirable in the conventional highly rigid
ceramic material. It is difficult to adjust to the fundamental resonance frequency f0 of
[0023]
14-04-2019
8
[0024]
In this embodiment, since the piezoelectric film 10 is used as the diaphragm, the rigidity of the
diaphragm is low, the basic resonance frequency f0 can be reduced, and it is optimal for lowrange reproduction.
Further, since the flexible piezoelectric film 10 is used, the impact of the drop is absorbed by the
resin material, which is suitable for mounting on a small electronic device such as a portable
telephone.
[0025]
Moreover, in the electroacoustic transducer 100 of this Embodiment, since a sound wave is
radiate | emitted in many directions, wide directivity can be implement | achieved. In the
conventional acoustic component, the directivity changes largely depending on the frequency to
be reproduced because the radiation direction is one direction. For example, in the low frequency
band, a wide directivity can be obtained because the sound waves wrap around, but the
directivity becomes narrow in a high frequency band where the straightness of the sound wave is
strong. On the other hand, in the present embodiment, broad directivity can be obtained at any
frequency without being affected by the directivity characteristic of the sound wave in multiple
directions.
[0026]
As described above, in summary, according to the present embodiment, it is possible to realize a
small-sized electroacoustic transducer 100 with wide directivity and large volume. In this
embodiment, it is not necessary to use a piezoelectric film diaphragm having a curved surface as
in the electroacoustic transducer disclosed in Patent Document 4, and the housing of the
polyhedron-shaped electronic device is used as the frame 2. Since the flat piezoelectric film
diaphragm 1 may be disposed on each surface, it is suitable for mounting on a small electronic
device such as a portable telephone. In addition, since the electroacoustic transducer 100 of the
present embodiment is excellent in manufacturability and has high impact stability at the time of
dropping, it is suitable for mounting on a small electronic device such as a mobile phone.
14-04-2019
9
[0027]
Next, the result of having evaluated the acoustic characteristic and directional characteristic of
the electroacoustic transducer 100 of this Embodiment is shown below. As a result of measuring
the sound pressure level of 1 kHz with a microphone 10 cm away from the electroacoustic
transducer 100, the sound pressure level of 1 kHz of the electroacoustic transducer 100 was 93
dB. The directional characteristics were measured by arranging the electroacoustic transducer
100 and the microphones 101-1, 101-2, 101-3 and 101-4 as shown in FIG. The distance
between the electroacoustic transducer 100 and the microphones 101-1, 101-2, 101-3, and 1014 is 10 cm. The measurement frequency was set to three types of 1 kHz, 3 kHz, and 5 kHz, and
three types of frequencies were measured in each direction, and data acquisition of a total of 12
points was performed. The measurement results of the directivity characteristics are shown in
Table 1.
[0028]
[0029]
The wide directivity judgment criterion is to set the difference between the maximum value and
the minimum value of all the measurement results within 3 dB.
According to the measurement results in Table 1, it was determined that wide directivity was
obtained because the difference between the maximum value 93 dB and the minimum value 91
dB in each measurement result was within 3 dB.
[0030]
Second Embodiment In the second embodiment, the thickness of the piezoelectric film 10 of the
first embodiment is set to 30 μm, and an electroacoustic transducer is manufactured. As a result
of measuring the characteristics of this electroacoustic transducer, the sound pressure level at 1
kHz was 93 dB, and good broad directivity similar to that of the first embodiment was obtained.
14-04-2019
10
[0031]
Third Embodiment In the third embodiment, the thickness of the piezoelectric film 10 of the first
embodiment is set to 100 μm, and an electroacoustic transducer is manufactured. As a result of
measuring the characteristics of this electroacoustic transducer, the sound pressure level at 1
kHz was 90 dB, and good broad directivity similar to that of the first embodiment was obtained.
[0032]
Fourth Embodiment In the fourth embodiment, the shape of the frame 2 of the first embodiment
is changed to a cubic shape to produce an electroacoustic transducer. As a result of measuring
the characteristics of this electroacoustic transducer, the sound pressure level at 1 kHz was 93
dB, and good broad directivity similar to that of the first embodiment was obtained.
[0033]
Fifth Embodiment In the fifth embodiment, the shape of the frame 2 of the first embodiment is
changed to a triangular pyramid to produce an electroacoustic transducer. As a result of
measuring the characteristics of this electroacoustic transducer, the sound pressure level at 1
kHz was 93 dB, and good broad directivity similar to that of the first embodiment was obtained.
[0034]
Sixth Embodiment In the sixth embodiment, the electro-acoustic transducer is manufactured with
the thickness of the upper electrode layer 11 and the lower electrode layer 12 of the first
embodiment set to 100 μm. As a result of measuring the characteristics of this electroacoustic
transducer, the sound pressure level at 1 kHz was 93 dB, and good broad directivity similar to
that of the first embodiment was obtained.
[0035]
14-04-2019
11
Seventh Embodiment In the seventh embodiment, an electroacoustic transducer is manufactured
by setting the thicknesses of the upper electrode layer 11 and the lower electrode layer 12 of the
first embodiment to 50 μm. As a result of measuring the characteristics of this electroacoustic
transducer, the sound pressure level at 1 kHz was 93 dB, and good broad directivity similar to
that of the first embodiment was obtained.
[0036]
Eighth Embodiment In the eighth embodiment, stainless steel is adopted as a material of the
frame 2 of the first embodiment, and an electroacoustic transducer is manufactured. As a result
of measuring the characteristics of this electroacoustic transducer, the sound pressure level at 1
kHz was 93 dB, and good broad directivity similar to that of the first embodiment was obtained.
[0037]
Ninth Embodiment In the ninth embodiment, aluminum is adopted as a material of the frame 2 of
the first embodiment to produce an electroacoustic transducer. As a result of measuring the
characteristics of this electroacoustic transducer, the sound pressure level at 1 kHz was 93 dB,
and good broad directivity similar to that of the first embodiment was obtained.
[0038]
Tenth Embodiment In the tenth embodiment, the piezoelectric film diaphragm 1 of the first
embodiment is doubled in number to fabricate an electroacoustic transducer. As a result of
measuring the characteristics of this electroacoustic transducer, the sound pressure level at 1
kHz was 110 dB, and good broad directivity similar to that of the first embodiment was obtained.
[0039]
In the first to tenth embodiments, a common electric signal is applied to all the piezoelectric film
diaphragms 1 of the electroacoustic transducer, but the present invention is not limited to this,
and a part of piezoelectric Another electrical signal may be applied to the upper electrode layer
14-04-2019
12
11 and the lower electrode layer 12 of the film diaphragm 1. Thereby, multiple types of sound
waves can be emitted from one electro-acoustic transducer. In order to emit a plurality of types
of sound waves from one electro-acoustic transducer, the wirings 3a and 3b and the terminals 4a
and 4b may be provided for each group of the piezoelectric film diaphragm 1. If electric signals
different for each group are input to the terminals 4a and 4b of the group, the piezoelectric film
diaphragm 1 of each group will emit different sound waves for each group. In order to secure the
sound pressure level, it is preferable to provide a plurality of piezoelectric film diaphragms 1 for
each group.
[0040]
Also, in the first to tenth embodiments, a mobile phone is described as an example of an
electronic device equipped with an electroacoustic transducer, but the present invention is not
limited to this, and other electronic devices may be used. Needless to say, it is possible to mount
an electroacoustic transducer.
[0041]
Although a part or all of the above-mentioned embodiment may be described as the following
supplementary notes, it is not limited to the following.
[0042]
(Supplementary Note 1) A plurality of piezoelectric film diaphragms in which electrodes are
formed on both sides of a piezoelectric film vibrating according to the state of an electric field,
and the plurality of piezoelectric film diaphragms are arranged in a polyhedron shape vessel.
[0043]
(Supplementary Note 2) The electro-acoustic transducer according to supplementary note 1,
wherein the piezoelectric film is made of a piezoelectric polymer material.
[0044]
(Supplementary Note 3) The electro-acoustic transducer according to supplementary note 1 or 2,
wherein each piezoelectric film diaphragm is inserted into an opening formed in each surface of
a polyhedral frame. .
[0045]
(Supplementary Note 4) In the electro-acoustic transducer according to any one of
14-04-2019
13
supplementary notes 1 to 3, each piezoelectric film diaphragm is divided into a plurality of
groups, and different electrical signals can be input to the electrodes for each group. An
electroacoustic transducer characterized by
[0046]
(Supplementary Note 5) An electronic apparatus comprising the electro-acoustic transducer
according to any one of supplementary notes 1 to 4.
[0047]
The present invention can be applied to a small-sized electroacoustic transducer.
[0048]
DESCRIPTION OF SYMBOLS 1 ... Piezoelectric film diaphragm, 2 ... Frame, 3a, 3b ... Wiring, 4a, 4b
... Terminal, 10 ... Piezoelectric film, 11 ... Upper electrode layer, 12 ... Lower electrode layer, 20 ...
Opening part, 21 ... Concave, 100 ... electroacoustic transducers.
14-04-2019
14
Документ
Категория
Без категории
Просмотров
0
Размер файла
25 Кб
Теги
jp2011228881, description
1/--страниц
Пожаловаться на содержимое документа