JP2010109979

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DESCRIPTION JP2010109979
The present invention provides an electret electroacoustic transducer which can widen a
utilization space inside an electronic device in place of a dynamic speaker which has a large
resonance chamber and prevents thinning. An electronic device 100 is provided. The electronic
device 100 includes a housing 110 and an electroacoustic transducer 180 provided on the inner
wall surface of the housing 110. The electroacoustic transducer 180 includes an electret
diaphragm 120, a conductive plate 140, and at least one spacer 150. The electret diaphragm
120 is disposed on the inner wall surface of the housing 110 and has a film main body 122 and
an electrode layer 124. The membrane body 122 is electrostatically charged, and the electrode
layer 124 is formed on the lower surface of the membrane body 122. The conductive plate 140
has a plurality of openings 114 and is provided on the top surface of the film body 122 in an
overlapping manner. The spacer 150 is disposed between the electret diaphragm 120 and the
conductive plate 140 to keep them at a predetermined distance. [Selected figure] Figure 2a
Electronic device equipped with electret electroacoustic transducer
[0001]
Cross-Reference to Related Applications: This application claims priority based on Taiwan Patent
Application 097141921, filed October 31, 2008, the entire disclosure of which is incorporated
herein by reference. Be incorporated.
[0002]
The present invention relates to an electroacoustic transducer, in particular to an electronic
device provided with an electret electroacoustic transducer.
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[0003]
A speaker is one of the means of producing sound.
The principle that a speaker emits a sound is to move the diaphragm of the speaker by an
electrical signal to push air.
Currently, speakers are widely used in electronic devices with sound output functions, such as
mobile phones, personal digital assistants (PDAs), laptop computers and the like.
[0004]
One common speaker is a so-called dynamic speaker. The principle that a dynamic speaker emits
sound is that a current is supplied to a voice coil to generate a magnetic field. When a magnetic
field is generated, the voice coil becomes responsive to the magnetic field from a permanent
magnet fixed to the frame of the speaker, which causes the diaphragm attached to the voice coil
to vibrate. Although such a dynamic speaker can output very good quality sound, it has a
considerable thickness because of the large resonance chamber. Therefore, when the dynamic
type speaker is used for the portable electronic device as described above, the electronic device
can not be thinned.
[0005]
The present invention provides an electronic device provided with an electret electroacoustic
transducer. The electret electroacoustic transducer of the electronic device of the present
invention is significantly thinner than conventional dynamic speakers. Therefore, the available
space inside the electronic device can be expanded.
[0006]
In the first embodiment, the electronic device provided with the electret electroacoustic
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transducer of the present invention comprises a housing, and the housing has a plurality of
openings penetrating from the inner wall surface to the outer wall surface. An electroacoustic
transducer is provided on the inner wall surface of the housing. The electro-acoustic transducer
includes a first electret diaphragm disposed on an inner wall surface of the housing. The first
electret diaphragm has a first film body and a first electrode layer formed on the lower surface of
the first film body. The first film body is formed of a dielectric and is electrostatically charged. A
first conductive plate having a plurality of openings is provided as an electrode on top of the first
film body. Furthermore, at least one first spacer is provided between the first electret diaphragm
and the first conductive plate to keep them at a predetermined distance.
[0007]
In the second embodiment, the electronic device provided with the electroacoustic transducer
further includes a second conductive plate which functions as an electrode when compared with
the electronic device of the first embodiment. The second conductive plate is provided to overlap
the first conductive plate and has a plurality of openings. An insulating layer formed of a porous
porous thin film is provided between the first conductive plate and the second conductive plate.
Furthermore, a second electret diaphragm is provided to overlap on the second conductive plate.
The second electret diaphragm has a second film body and a second electrode layer formed on
the top surface of the second film body. The second film body is formed of a dielectric and is
electrostatically charged. A muffling layer is attached to the second electrode layer. Furthermore,
at least one second spacer is provided between the second electret diaphragm and the second
conductive plate to keep them at a predetermined distance.
[0008]
In the third embodiment, the electronic device provided with the electret electroacoustic
transducer of the present invention comprises a housing, and the housing has a plurality of
openings penetrating from the inner wall surface to the outer wall surface. The electroacoustic
transducer is provided on the inner wall surface of the housing. In the electro-acoustic
transducer, a conductive plate as an electrode is disposed on an inner wall surface of the housing,
and the conductive plate has a plurality of openings. The electret diaphragm is provided so as to
overlap the conductive plate, and has a film main body and an electrode layer formed on the
upper surface of the film main body. The membrane body is formed of a dielectric and is
electrostatically charged. Furthermore, at least one spacer is provided between the electret
diaphragm and the conductive plate to keep them at a predetermined distance. A muffling layer
is attached to the electrode layer.
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[0009]
In the fourth embodiment, the electronic device provided with the electroacoustic transducer is
substantially the same as the electronic device of the third embodiment. The difference from the
third embodiment is that, in the electroacoustic transducer of the electronic device of the fourth
embodiment, a conductive layer is formed as a film on the inner wall surface of the housing
instead of the conductive plate of the third embodiment. .
[0010]
The above and other objects, features and features of the present invention will be readily
apparent from the detailed description given below with reference to the accompanying
drawings.
[0011]
It is a perspective view which shows the electronic device of this invention.
FIG. 2 is a cross-sectional view showing an electronic device provided with the electro-acoustic
transducer according to the first embodiment of the present invention, showing a state in which
the back cover is removed from the electronic device main body. FIG. 2 is a cross-sectional view
of an electronic device including the electro-acoustic transducer according to the first
embodiment of the present invention, showing a state in which a back cover is attached to the
electronic device body. FIG. 6 is a cross-sectional view showing an electronic device provided
with the electro-acoustic transducer according to a second embodiment of the present invention,
showing a state in which the back cover is removed from the electronic device main body. FIG. 6
is a cross-sectional view of an electronic device including the electro-acoustic transducer
according to a second embodiment of the present invention, showing a state in which a back
cover is attached to the electronic device body. It is a sectional view showing electronic
equipment provided with an electroacoustic transducer by a 3rd example of the present
invention, and shows a state where a back cover was removed from an electronic equipment
main part. It is a sectional view showing the electronic equipment provided with the electronic
sound transducer by a 3rd example of the present invention, and shows the state where the back
cover was attached to the electronic equipment main part. It is a sectional view showing the
electronic equipment provided with the electronic sound transducer by a 4th example of the
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present invention, and shows the state where the back cover was removed from the electronic
equipment main part. It is a sectional view showing the electronic equipment provided with the
electronic sound transducer by a 4th example of the present invention, and shows the state
where the back cover was attached to the electronic equipment main part.
[0012]
As shown in FIGS. 1, 2a and 2b, an electronic device 100 equipped with an electroacoustic
transducer according to a first embodiment of the present invention has a housing 110, and the
housing 110 is exposed from its inner wall surface 112. It has a large number of openings 114
penetrating to the wall surface 118. An electroacoustic transducer 180 is provided on the inner
wall surface 112 of the housing 110. The electroacoustic transducer 180 includes an electret
diaphragm 120, and the electret diaphragm 120 is disposed on the inner wall surface 112 of the
housing 110. In addition, the electret diaphragm 120 includes a film main body 122 and an
electrode layer 124 formed on the lower surface of the film main body 122. The film body 122 is
made of a dielectric and is electrostatically charged. The film body 122 has a thickness of 7 μm
to 25 μm, and the electrode layer 124 has a thickness of 0.05 μm to 1 μm. A conductive plate
140 functioning as an electrode is provided on the top surface of the film body 122 in an
overlapping manner. The conductive plate 140 has a plurality of openings 142 corresponding to
the openings 114 of the housing 110. The thickness of the conductive plate 140 is 0.1 mm to 1
mm, and the aperture ratio of the opening 142 in the conductive plate 140 is greater than 20%.
Furthermore, at least one spacer 150 is provided between the electret diaphragm 120 and the
conductive plate 140, and the distance between the electret diaphragm 120 and the conductive
plate 140 is kept constant. The spacers 150 are disposed at a distance of 5 mm to 20 mm from
each other, and the height thereof is 100 μm to 400 μm.
[0013]
In order to charge the film body 122, it is necessary to polarize the film body 122 which is not
originally charged with static charge. For example, after the electrode layer 124 is formed on the
film body 122, electrostatic charge can be generated inside and on the surface of the film body
122 by using the corona charging process to polarize the film body 122. Materials suitable for
the membrane body 122 include fluorinated ethylene propylene (FEP), polytetrafluoroethylene
(PTFE), polyvinylidene fluoride (PVDF), silicon dioxide (SiO2), or other fluoride polymers .
Furthermore, the electret diaphragm 120 needs to fix its edge so as not to move. In order to
operate the electroacoustic transducer 180 of this embodiment, the electric signal in the same
phase as the original sound signal and the electric signal in the reverse phase, that is, the
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differential signal, are respectively transmitted to the conductive plate 140 and the electrode
layer 124. It must be added. As a result, the coulomb force acts on the electret diaphragm 120
from the conductive plate 140 and the electrode layer 124 to provide a push-pull effect. The
push-pull effect causes the electret diaphragm 120 to vibrate in response to the electrical signal.
When the electret diaphragm 120 vibrates, air is pushed to make a sound. The generated sound
exits the housing 110 through the opening 114 and reaches the user's ear.
[0014]
In addition, since the sound generated by the electret diaphragm 120 passes through the
opening 142 of the conductive plate 140 and is reflected by the components provided on the
upper portion of the conductive plate 140, the performance of the electroacoustic transducer
180 is deteriorated due to the echo. In order to prevent this, the upper surface of the conductive
plate 140 is separated from the components above the conductive plate 140 by a predetermined
distance, more specifically, 1 mm. Instead of this, a sound absorbing layer 160 made of, for
example, glass fiber, sponge, non-woven fabric or the like may be attached to the upper surface
of the conductive plate 140 to absorb the sound passing through the opening 142. The muffling
layer 160 has a thickness of 1 mm to 5 mm. Furthermore, at least one spacer 170 having a
thickness of 30 μm to 50 μm is disposed between the electrode layer 124 and the inner wall
surface 112 of the housing 110 corresponding to the spacer 150, and the electrode layer 124 is
mounted on the housing 110. I keep it so that I do not touch. Alternatively, the spacer 150 may
be formed of an adhesive such as double-sided tape to fix the conductive plate 140 and the film
body 122.
[0015]
In FIGS. 1, 3a and 3b, an electronic device 200 equipped with an electroacoustic transducer
according to a second embodiment of the present invention has all of the components of the
electronic device 100. That is, it has the housing 110, the electret diaphragm 120 of the
electroacoustic transducer 180, the conductive plate 140, the spacers 150 and 170, and the
muffling layer 160. In addition to the above components, the electroacoustic transducer 280 of
the electronic device 200 of the present embodiment further includes a conductive plate 240
functioning as an electrode. The conductive plate 240 is stacked on the conductive plate 140 and
has a plurality of openings 242 corresponding to the openings 142 of the conductive plate 140.
The thickness of the conductive plate 240 is 0.1 mm to 1 mm. An insulating layer 290 made of a
breathable porous thin film having a thickness of 20 μm to 200 μm is provided between the
conductive plate 140 and the conductive plate 240. In addition, an electret diaphragm 220 is
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disposed on the conductive plate 240, and the electret diaphragm 220 includes a film main body
222 and an electrode layer 224 formed on the upper surface of the film main body 222. Are
attached to the electrode layer 224. The film body 222 is made of a dielectric and is
electrostatically charged. The thickness of the film body 222 is 7 μm to 25 μm, and the
thickness of the electrode layer 224 is 0.05 μm to 1 μm. Furthermore, between the electret
diaphragm 220 and the conductive plate 240, at least one spacer 250 made of, for example, an
adhesive material is provided corresponding to the spacer 150, and the electret diaphragm 220
and the conductive plate 240 Interval is kept constant. The height of the spacer 250 is 100 μm
to 400 μm.
[0016]
As described above, the film body 222 which is not originally charged with electrostatic charge
needs to be polarized to generate electrostatic charge internally and on the surface. Suitable
materials for membrane body 222 include FEP, PTFE, PVDF, silicon dioxide, or other fluoride
polymers. Furthermore, the electret diaphragm 220 needs to fix its edge so that it does not move.
In order to operate the electroacoustic transducer 280 of this embodiment, a first electrical
signal in phase with the original sound signal is applied to the conductive plate 140 and the
electrode layer 224, and a second electrical signal in antiphase with the original signal is applied.
A signal must be applied to the electrode layer 124 and the conductive plate 240. As a result, the
electret diaphragm 120 and the electret diaphragm 220 are exposed to the Coulomb force from
the conductive plates 140 and 240 and the electrode layers 124 and 224 and vibrate to generate
sounds according to the first and second electrical signals. The sound generated by the electret
diaphragm 220 passes through the insulating layer 290 and the opening 114 to the outside of
the housing 110. The electroacoustic transducer 280 having two electret diaphragms can output
twice the volume (3 dB) as compared to the electroacoustic transducer 180 having only one
electret diaphragm.
[0017]
In FIGS. 1, 4a and 4b, an electronic apparatus 300 equipped with an electroacoustic transducer
according to a third embodiment of the present invention includes an enclosure 110 and an
electroacoustic transducer 380 installed on the inner wall surface 112 of the enclosure 110. And.
The electroacoustic transducer 380 includes a conductive plate 340 that functions as an
electrode, and the conductive plate 340 is disposed on the inner wall surface 112 of the housing
110. The conductive plate 340 has a plurality of openings 342 corresponding to the openings
114. An electret diaphragm 320 is stacked on the conductive plate 340, and the electret
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diaphragm 320 includes a film main body 322 and an electrode layer 324 formed on the upper
surface of the film main body 322. The membrane body 322 is made of a dielectric and is
electrostatically charged. The thickness of the film body 322 is 7 μm to 25 μm, and the
thickness of the electrode layer 324 is 0.05 μm to 1 μm. Furthermore, at least one spacer 350
made of, for example, an adhesive is provided between the electret diaphragm 320 and the
conductive plate 340, and the distance between the electret diaphragm 320 and the conductive
plate 340 is kept constant. The spacers 350 are spaced from each other by 5 mm to 20 mm, and
the height thereof is 100 μm to 400 μm. Furthermore, at least one spacer 370 made of, for
example, an adhesive material is disposed between the conductive plate 340 and the inner wall
surface 112 of the housing 110 corresponding to the spacer 350, and the conductive plate 340
does not contact the housing 110. Keep it like that. The spacer 370 has a thickness of 30 μm to
50 μm. Furthermore, a muffling layer 360 is attached to the electrode layer 324 to prevent
performance degradation of the electro-acoustic transducer 380 due to echo.
[0018]
As in the above embodiment, the film body 322 which is not originally charged with electrostatic
charge needs to be polarized to generate the electrostatic charge internally and on the surface.
Suitable materials for the membrane body 322 include fluoride polymers such as FEP, PTFE,
PVDF, silicon dioxide and the like. Furthermore, the electret diaphragm 320 needs to fix its edge
so that it does not move. To operate the electro-acoustic transducer 380 of this embodiment, an
electrical signal must be applied to the conductive plate 340 and the electrode layer 324.
Thereby, the electret diaphragm 320 vibrates and outputs a sound according to the applied
electric signal.
[0019]
The electronic device 400 provided with the electro-acoustic transducer according to the fourth
embodiment of the present invention shown in FIGS. 1, 5a and 5b is substantially the same as the
electronic device 300 shown in FIG. Substantially the same components are denoted by the same
reference numerals, and the description of these components is omitted here. The difference
from the third embodiment is that, in the electroacoustic transducer 480 of the electronic device
400 of the fourth embodiment, a conductive layer 440 is formed on the inner wall surface 112 of
the housing 110 instead of the conductive plate 340. The spacer 370 is not provided. As
described above, to operate the electroacoustic transducer 480 of this embodiment, an electrical
signal must be applied to the conductive layer 440 and the electrode layer 324. Thereby, the
electret diaphragm 320 vibrates and outputs a sound according to the applied electric signal.
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[0020]
The electroacoustic transducers 180, 280, 380, 480 of the electronic devices 100, 200, 300, 400
are installed on a housing 110, and the housing 110 is a part of the electronic devices 100, 200,
300, 400. It can be a cover covering the front, side or back. It will be appreciated that the
electroacoustical transducers 180, 280, 380, 480 operate by connecting electrically to other
components, such as the circuit board of the electronic device 100, 200, 300, 400. Referring
back to FIGS. 2a, 2b, 3a, 3b, 4a, 4b, 5a, 5b, the electroacoustic transducers 180, 280, 380, 480
can be assembled to the removable back cover 110. Sometimes, the inner wall surface 112 of the
back cover 110 is provided with an electrical terminal 116 a and electrically connected to the
conductive plates 140 and 340 and the conductive layer 440. An electrical terminal 116 b is also
provided on the inner wall surface 112 of the back cover 110, and is electrically connected to the
electrode layers 124 and 324. Furthermore, electric terminals 119a and 119b are provided on
the inner wall surface 112 of the back cover 110 of the electronic device 200, and are
electrically connected to the conductive plate 240 and the electrode layer 224 of the
electroacoustic transducer 280, respectively. As shown in FIGS. 2b, 3b, 4b and 5b, when the back
cover 110 is attached to the electronic device 100, 200, 300 and 400, the electrical terminals
116a and 116b are respectively the electronic device 100, 200 and 300. , 400 are electrically
connected in contact with the electric terminals 197a and 197b on the circuit board 195,
respectively. The electrical terminals 119a and 119b (shown in FIG. 3b) are electrically
connected to the electrical terminals 198a and 198b on the circuit board 195 of the electronic
device 200, respectively. This makes it possible to apply electrical signals to the conductive
plates 140, 240, 340, the conductive layer 440, and the electrode layers 124, 224, 324, and the
electret diaphragms 120, 220, 320 vibrate in response to the applied electrical signals. To make
a sound.
[0021]
According to the invention, the spacer of the electroacoustic transducer may be a separate
member. However, it will be understood that instead of the individual spacers described above, a
sheet having a plurality of openings may be used.
[0022]
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The electronic device of the present invention can be implemented as a portable electronic device
such as a mobile phone, a personal digital assistant (PDA), a laptop computer and the like. Since
the electroacoustic transducer of the electronic device of the present invention is very thin
compared to the conventional dynamic speaker, the available space in the electronic device is
expanded. Furthermore, the electroacoustic transducer of the electronic device of the present
invention can be attached to the back cover. Therefore, the thickness of the electronic device can
be further reduced, and the available space in the electronic device can be further expanded.
Furthermore, in the electro-acoustic transducer of the electronic device according to the first and
second embodiments of the present invention, the electret surface is polluted by dust or moisture
because the electret surface of the electret diaphragm faces the inside of the electronic device. It
is possible to avoid the failure of the electret diaphragm.
[0023]
While the preferred embodiments have been described for the purpose of illustrating the
invention, it is understood that various modifications, additions, and substitutions may be made
without departing from the scope and spirit of the invention as disclosed in the appended claims.
It will be easily understood by the trader.
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