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JP2013146020

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DESCRIPTION JP2013146020
Abstract: When a member having elasticity is provided between an electrode and a vibrating
body, sound waves generated by the vibrating body are efficiently radiated. SOLUTION: A
vibrating body 10 to which a bias voltage is applied is positioned between electrodes 20U and
20L to which an acoustic signal is supplied, and an elastic member 30U having elasticity between
the vibrating body 10 and the electrodes 20U and 20L. , 30 L are located. The electrodes 20U
and 20L are provided with a plurality of holes 21 penetrating from the upper surface side to the
lower surface side, and the elastic members 30U and 30L are provided with a plurality of holes
31 penetrating from the upper surface side to the lower surface side. One hole 31 is located
below one hole 21 on the upper surface side, and one hole 31 is located above one hole 21 on
the lower surface side, and the holes 21 and 31 overlap. In the part, the vibrator 10 is exposed to
the outside. [Selected figure] Figure 2
Electrostatic transducer
[0001]
The present invention relates to electrostatic transducers.
[0002]
Some electrostatic loudspeakers, which are transducers that convert electrical signals into sound,
include a cushioning material having elasticity between a vibrating diaphragm that vibrates and
an electrode provided with a plurality of holes.
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1
Further, in the electrostatic speaker of this configuration, as disclosed in, for example, Patent
Document 1, there is a configuration in which a hole is provided in a cushion material. According
to the speaker of Patent Document 1, the stiffness of the cushioning material is low and the
minimum resonance frequency is low, as compared with the configuration in which no hole is
provided in the cushioning material. Further, according to the invention of Patent Document 1,
since the stiffness of the cushioning material is lowered, the vibrating film is more easily vibrated
as compared with the configuration in which no hole is provided in the cushioning material.
[0003]
JP 2007-274341 A
[0004]
By the way, even if the vibrating membrane is easily vibrated by the configuration of Patent
Document 1, if the sound that has passed through the hole of the cushion material is blocked by
the electrode, the emission of the sound from the speaker is suppressed.
[0005]
The present invention has been made under the above-described background, and provides a
technique for efficiently emitting sound waves generated by a vibrating body when a member
having elasticity is provided between an electrode and the vibrating body. With the goal.
[0006]
In order to achieve the above object, the present invention provides a first electrode, a vibrator to
which a bias voltage is applied, and a first elastic member having elasticity and disposed between
the electrode and the vibrator. And the first elastic member is provided with a plurality of holes
penetrating from the vibrator side to the first electrode side, and the first electrode is provided
with the first elastic member from the first elastic member side. A plurality of through holes are
provided on the side opposite to the side, and an electrostatic transducer is provided in which the
hole of the first electrode and the hole of the first elastic member are connected.
[0007]
In the present invention, the second elastic member having elasticity is located on the opposite
side to the first elastic member as viewed from the vibrating body, and on the opposite side to
the vibrating body as viewed from the second elastic member. And the second elastic member
has a plurality of holes penetrating from the vibrator side to the second electrode side, and the
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2
second electrode is arranged from the second elastic member side. A plurality of holes
penetrating to the side opposite to the second elastic member side, the hole of the second
electrode and the hole of the second elastic member are connected, and the hole of the first
electrode, the hole of the first elastic member, The hole of the second elastic member and the
hole of the second electrode may overlap as viewed from the first electrode side.
[0008]
The present invention also includes an electrode, a vibrator to which a bias voltage is applied,
and a plurality of elastic members having elasticity and being spaced apart from each other
between the electrode and the vibrator. The electrode has a plurality of holes penetrating from
the vibrator side to the opposite side to the vibrator side, and the elastic member is arranged at a
position not overlapping with the holes when viewed from the electrode side I will provide a.
[0009]
According to the present invention, when an elastic member is provided between the electrode
and the vibrator, the sound wave generated by the vibrator is efficiently emitted.
[0010]
FIG. 1 is an external view of an electrostatic speaker 1 according to an embodiment of the
present invention.
1. AA sectional view taken on the line of FIG.
The exploded view of electrostatic type speaker 1.
FIG. 2 shows a configuration of a drive circuit 100.
Sectional drawing of the electrostatic-type speaker 1 which concerns on a modification.
Sectional drawing of the electrostatic-type speaker 1 which concerns on a modification.
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Sectional drawing of the electrostatic-type speaker 1 which concerns on a modification.
The figure which expanded the cross section of the electrostatic speaker 1 which concerns on a
modification. The schematic diagram of the upper surface side of electrode 20L which concerns
on a modification. The figure which showed the structure of the microphone 2 and the acoustic
signal generation circuit 200 which concern on a modification.
[0011]
Embodiment FIG. 1 is an external view of an electrostatic speaker 1 (electrostatic transducer)
according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of the
electrostatic speaker 1 taken along line A-A. FIG. 3 is an exploded view of the electrostatic
speaker 1. In the figure, the directions are indicated by the orthogonal X-axis, Y-axis, and Z-axis,
and the horizontal direction when the electrostatic speaker 1 is viewed from the front is the Xaxis direction, and the depth direction is the Y-axis direction. The height (up and down) direction
is the direction of the Z axis. In the following description, for convenience of description, the
positive direction side of the Z axis may be referred to as the upper surface side, and the negative
direction side of the Z axis may be referred to as the lower surface side.
[0012]
As shown in the figure, the electrostatic loudspeaker 1 has a vibrator 10, electrodes 20U and
20L, and elastic members 30U and 30L. In the present embodiment, the configurations of the
electrode 20U and the electrode 20L are the same, and the configurations of the elastic member
30U and the elastic member 30L are the same. For this reason, in these members, when it is not
particularly necessary to distinguish between a member having a suffix “U” and a member
having a suffix “L”, the descriptions such as “L” and “U” are omitted. . Further, the
dimensions of the respective members in the figure are different from the actual dimensions so
that the shapes and positional relationships of the respective members can be easily understood.
[0013]
(Configuration of Each Part of Electrostatic Speaker 1) First, each part of the electrostatic speaker
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1 will be described. When viewed from the top side, the rectangular vibrator 10 is electrically
conductive on one side of a film (insulating layer) of an insulating and flexible synthetic resin
such as PET (polyethylene terephthalate) or PP (polypropylene). It has a sheet-like structure in
which a conductive metal is deposited to form a conductive film (conductive layer). In the present
embodiment, the conductive film is formed on one side of the film, but may be formed on both
sides of the film. The vibrating body 10 may have a configuration in which a conductive metal is
rolled to form a film.
[0014]
The electrode (fixed electrode) 20 uses a film (insulating layer) of insulating synthetic resin such
as PET or PP as a base material, and a conductive metal is deposited on one surface of the film to
form a conductive film (conductive layer) ) Is formed. The electrode 20 is rectangular when
viewed from the top surface side. The electrode 20 has a plurality of holes 21 penetrating from
the upper surface side to the lower surface side, so that air and sound can pass therethrough.
Although illustration of the holes 21 is omitted in FIG. 1 and FIG. 3, in the electrode 20, the holes
21 are provided in a plurality of rows in the Y axis direction and a plurality of columns in the X
axis direction. Further, in the present embodiment, the holes 21 are circular as viewed from the
upper surface side, but the shape of the holes 21 is not limited to a circular shape, and may be
another shape such as a polygon or an oval. It is also good. In the present embodiment, the
length in the X-axis direction and the length in the Y-axis direction of the electrode 20 are longer
than those of the vibrating body 10. Similar to the vibrator 10, the electrode 20 may be formed
into a film by rolling a conductive metal. The electrode 20 may not have flexibility as long as it
has conductivity, and may be, for example, punching metal.
[0015]
The elastic member 30 is a non-woven fabric in the present embodiment and can pass air and
sound without passing electricity, and its shape is rectangular when viewed from the top side.
The elastic member 30 has elasticity, and deforms when an external force is applied, and returns
to its original shape when an external force is removed. In the present embodiment, the length in
the X-axis direction and the length in the Y-axis direction of the elastic member 30 are the same
as those of the electrode 20. Moreover, although illustration is abbreviate | omitted in FIG.1 and
FIG.3, elastic member 30 which concerns on this embodiment is provided with two or more holes
31 which penetrate from the upper surface side to the lower surface side. In the present
embodiment, the holes 31 are circular when viewed from the upper surface side, but the shape of
the holes 31 is not limited to a circle, and may be another shape such as a polygon or an oval.
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The holes 31 are provided corresponding to each of the holes 21 of the electrode 20, and in the
elastic member 30, a plurality of rows in the Y axis direction and a plurality of columns in the X
axis direction are provided. Specifically, as shown in an enlarged manner in FIG. 2, in the
electrode 20U and the elastic member 30U, one hole 31 is located below one hole 21, and the
hole 21 and the hole 31 are connected. It is continuous. For this reason, the vibrating body 10 is
exposed to the outside in the portion where the hole 21 and the hole 31 overlap when viewed
from the upper surface side. Further, in the electrode 20L and the elastic member 30L, one hole
31 is positioned above one hole 21 and the vibrating body 10 is exposed to the outside in a
portion where the hole 21 and the hole 31 overlap when viewed from the lower surface side. It
will be done.
[0016]
In the present embodiment, in the case where the electrode 20 and the elastic member 30 are
provided with holes, first, the elastic member 30 is overlapped on the electrode 20 and adhered.
Then, after bonding the electrode 20 and the elastic member 30, the needles arranged in a
plurality of rows and columns are pressed from the electrode 20 side or the elastic member 30
side so as to penetrate the overlapped electrode 20 and the elastic member 30. . When the
penetrated needle is pulled out of the electrode 20 and the elastic member 30, the holes 21 and
31 overlap with each other as viewed from the upper surface side. Here, the diameter and the
number of needles, and the distance between the needles for making holes in the electrode 20
and the elastic member 30 are not limited to specific values, and the thickness and the area of
the electrode 20 and the elastic member 30 It may be changed according to the situation. In
addition, the needle may be heated to provide a hole. Moreover, the method of providing a hole
in the electrode 20 and the elastic member 30 is not limited to the above-mentioned method. For
example, the electrode 20 and the elastic member 30 may be bonded after the holes are
separately provided without bonding the electrode 20 and the elastic member 30. Further, the
holes may be provided by die cutting by press processing, or the holes may be provided by laser
processing.
[0017]
(Structure of Electrostatic Speaker 1) Next, the structure of the electrostatic speaker 1 will be
described. In the electrostatic speaker 1, the vibrator 10 is bonded to the electrode 20U and the
lower surface side of the elastic member 30U provided with the hole 31 and the upper surface of
the elastic member 30L bonded to the electrode 20L and provided with the hole 31. Placed
between the sides. The adhesive is applied to the elastic member 30U and the elastic member
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30L with a width of several mm from the edge to the inner side of the vibrator 10, and the elastic
member 30U and the elastic member 30L are inside the portion to which the adhesive is applied.
It is in the state of not being fixed to In addition, the adhesive is applied to the elastic member
30U and the elastic member 30L with a width of several mm from the edge to the inside, and
they are fixed to each other.
[0018]
The electrode 20U is located on the upper surface side of the elastic member 30U, and the
electrode 20L is located on the lower surface side of the elastic member 30L. In the electrode
20U, the side with the conductive film is in contact with the elastic member 30U, and the side
with the conductive film is in contact with the elastic member 30L. That is, the conductive film of
the electrode 20 and the vibrator 10 face each other with the elastic member 30 interposed
therebetween.
[0019]
Electrical Configuration of Electrostatic Speaker 1 Next, an electrical configuration of the
electrostatic speaker 1 will be described. FIG. 4 is a diagram showing the configuration of a drive
circuit 100 for driving the electrostatic speaker 1. As shown in FIG. 4, the drive circuit 100 for
driving the electrostatic speaker 1 includes an amplification unit 130, a transformer 110, a DC
power supply 111, resistors R11 to R13, and a female first connector 140. There is.
[0020]
The amplification unit 130 is an amplification unit that amplifies and outputs an input acoustic
signal. The amplification unit 130 is connected to the terminal T14 and the terminal T15 of the
primary side coil of the transformer 110 via the resistor R11 and the resistor R12. The AC
acoustic signal amplified by the amplification unit 130 is supplied to the transformer 110. The
transformer 110 boosts the acoustic signal supplied from the amplification unit 130. One
terminal T11 of the secondary coil of the transformer 110 is connected to the first terminal of
the first connector 140, and the other terminal T12 of the secondary coil of the transformer 110
is the third terminal of the first connector 140. It is connected to the. Further, the center tap T13
of the secondary coil of the transformer 110 is connected to the ground GND which is the
reference potential of the drive circuit 100.
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[0021]
The direct current power supply 111 is a power supply for applying a direct current voltage (bias
voltage) to the vibrating body 10. The DC power supply 111 is connected to the fifth terminal of
the first connector 140 via the resistor R13. The second terminal, the fourth terminal, and the
sixth terminal of the first connector 140 are connected to the ground GND of the drive circuit
100.
[0022]
Next, in the electrostatic speaker 1, the first terminal of the male second connector 141 is
connected to the electrode 20U by a cable, and the third terminal of the second connector 141 is
connected to the electrode 20L by a cable. The fifth terminal of the second connector 141 is
connected to the vibrating body 10 by a cable. In the first connector 140 and the second
connector 141, the terminals are insulated.
[0023]
(Operation of Embodiment) Next, the operation of this embodiment will be described. When
driving the electrostatic speaker 1, first, the male second connector 141 is fitted to the female
first connector 140. When the second connector 141 is fitted in the first connector 140, the
terminals of the same number of each connector are connected, the terminal T11 and the
electrode 20U are electrically connected, and the terminal T12 and the electrode 20L are
electrically connected. . Since the center tap T13 of the transformer 110 is connected to the
ground GND, the voltages of the terminals T11 and T12 are 0 V when the amplitude of the
acoustic signal input to the amplification unit 130 is 0 V.
[0024]
Further, when the second connector 141 is fitted in the first connector 140, the DC power supply
111 is electrically connected to the vibrating body 10 via the resistor R13, and a DC voltage (bias
voltage) is applied to the vibrating body 10 Be done.
04-05-2019
8
[0025]
Next, the case where the amplitude of the acoustic signal changes from 0 V will be described.
When an AC acoustic signal is input to the amplification unit 130, the input acoustic signal is
amplified and supplied to the primary side of the transformer 110. The acoustic signal boosted
by the transformer 110 as boosting means and output from the terminal T12 is boosted by the
transformer 110 and has the same amplitude as that of the acoustic signal output from the
terminal T11 and the polarity of the signal is reverse.
[0026]
Since the positive acoustic signal is input to the amplification unit 130, the polarity of the
acoustic signal output from the terminal T11 on the secondary side of the transformer 110
becomes positive, and the polarity of the audio signal output from the terminal T12 is negative.
In this case, while the electrostatic attractive force between the vibrator 10 and the electrode
20U is weakened, the electrostatic attractive force between the vibrator 10 and the electrode 20L
is strengthened. Then, the vibrator 10 is displaced toward the electrode 20L (in the negative
direction of the Z axis) according to the difference between the electrostatic attraction acting on
the electrode 20U side and the electrostatic attraction acting on the electrode 20L side.
[0027]
In addition, since the negative acoustic signal is input to the amplification unit 130, the polarity
of the acoustic signal output from the terminal T11 on the secondary side of the transformer 110
becomes negative, and the polarity of the acoustic signal output from the terminal T12 is When it
becomes positive, the electrostatic attractive force between the vibrator 10 and the electrode 20L
is weakened, while the electrostatic attractive force between the vibrator 10 and the electrode
20U is stronger. Then, the vibrating body 10 is displaced to the electrode 20U side (the positive
direction of the Z axis) according to the difference between the electrostatic attractive force
acting on the electrode 20U side and the electrostatic attractive force acting on the electrode 20L
side.
[0028]
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9
Thus, the vibrating body 10 is displaced in the positive direction of the Z-axis and the negative
direction of the Z-axis in accordance with the acoustic signal, and becomes a vibration by
sequentially changing its displacement direction (vibration frequency, amplitude, Sound waves
corresponding to the phase) are generated from the vibrator 10. The generated sound wave
passes through the elastic member 30 having sound permeability and the electrode 20 and is
emitted as sound to the outside of the electrostatic speaker 1.
[0029]
When the vibrating body 10 is displaced to the electrode 20U side, the air in the hole 31 of the
elastic member 30U and the hole 21 of the electrode 20U is pushed by the vibrating body 10 on
the upper surface side of the electrostatic speaker 1 and the electrostatic type Move to the
outside of the speaker 1. Further, on the lower surface side of the electrostatic speaker 1, when
the vibrating body 10 is displaced to the electrode 20U side, the air in the hole 31 of the elastic
member 30L and the hole 21 of the electrode 20L along the displacement of the vibrating body
10 is the upper surface side The air in the vicinity of the electrode 20L is drawn into the hole 21
of the electrode 20L. In addition, when the vibrating body 10 is displaced to the electrode 20L
side, the air in the hole 31 of the elastic member 30L and the hole 21 of the electrode 20L is
pushed by the vibrating body 10 on the lower surface side of the electrostatic speaker 1 Move to
the outside of the speaker 1. Further, on the upper surface side of the electrostatic speaker 1,
when the vibrating body 10 is displaced to the electrode 20L side, the air in the hole 31 of the
elastic member 30U and the hole 21 of the electrode 20U is moved to the lower surface side
along with the displacement of the vibrating body 10. And air in the vicinity of the electrode 20U
is drawn into the holes 21 of the electrode 20U.
[0030]
The elastic member 30 of the present embodiment is a non-woven fabric in which continuous
fibers are bonded. Therefore, when the hole 31 is not provided in the elastic member 30, the air
between the fibers of the non-woven fabric moves along with the displacement of the vibrating
body 10 when the vibrating body 10 is displaced. In the meantime, the fibers of the non-woven
fabric resist the movement of air.
[0031]
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10
On the other hand, in the present embodiment, the holes 31 are provided corresponding to the
holes 21. In the part where the holes 31 are present, the fibers of the non-woven fabric do not
prevent movement and there is little resistance to the radiation of the sound, so the vibrator 10
easily vibrates and is compared with the case where the holes 31 are not provided. Then, the
sound wave generated by the vibrator 10 is efficiently emitted. Further, as compared with the
configuration in which the hole 21 and the hole 31 are not connected, the sound wave that has
passed through the hole 31 is emitted without being blocked by the electrode 20, so that a large
sound pressure can be obtained.
[0032]
[Modifications] Although the embodiment of the present invention has been described above, the
present invention is not limited to the above-described embodiment, and can be practiced in
various other forms. For example, the above-described embodiment may be modified as follows
to implement the present invention. The above-described embodiment and the following
modifications may be combined with each other.
[0033]
(Modification 1) In the electrostatic loudspeaker 1, the diameters of the holes 21 and 31 may be
different. FIG. 5 is an enlarged view of a cross section of the electrostatic loudspeaker 1
according to the present modification. As shown in FIG. 5, the diameter of the hole 21 may be
made larger than the diameter of the hole 31, and the hole 21 and the hole 31 may be connected
in series. Further, the diameter of the hole 31 may be larger than the diameter of the hole 21.
According to the configuration in which the diameter of the hole 31 is made larger than the
diameter of the hole 21, since the hole 21 and the hole 31 are connected in series, sound is
emitted more efficiently than in the configuration in which the hole 31 is closed by the electrode
20. Be done. Further, in the configuration in which the diameter of the hole 31 is larger than the
diameter of the hole 21, the area of the electrode 20 is larger as compared with the configuration
in which the diameter of the hole 21 is larger than the diameter of the hole 31. The sound
pressure can be increased.
[0034]
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11
(Modification 2) FIG. 6 is an enlarged view of a cross section of the electrostatic loudspeaker 1
according to this modification. In the electrostatic speaker 1, if the vibrating body 10 is exposed
through the hole 31 and the hole 21, as shown in FIG. 6, the positions of the center of the hole
21 and the center of the hole 31 are shifted. It may be connected to In addition, even when the
diameter of the hole 21 is larger than the diameter of the hole 31, the positions of the center of
the hole 21 and the center of the hole 31 may be shifted so as to be continuous.
[0035]
(Modification 3) FIG. 7 is an enlarged view of a cross section of the electrostatic loudspeaker 1
according to the present modification. In the electrostatic speaker 1, the number of the holes 31
may be larger than that of the holes 21, and the holes 31 may be provided at positions other
than the holes 21 as shown in FIG. 7.
[0036]
(Modification 4) Further, in the electrostatic speaker 1, the holes 31 and the holes 21 are
provided in a plurality of rows and a plurality of columns in the X axis direction and the Y axis
direction, but the holes 31 and 21 may be electrodes, for example, It may be provided
concentrically from the center of 20.
[0037]
(Modification 5) When providing a hole in the electrode 20 and the elastic member 30, the
electrode 20U to which the elastic member 30U is bonded and the electrode 20L to which the
elastic member 30L is bonded are overlapped, and the overlapped members are penetrated In
order to do so, the needles arranged in a plurality of rows and columns may be pressed.
After opening the hole, the elastic member 30U and the elastic member 30L are opened, and the
vibrator 10 is disposed between the elastic member 30U and the elastic member 30L, and then
the edges of the elastic member 30L and the elastic member 30U It may be adhered.
[0038]
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12
FIG. 8 is an enlarged view of a cross section of the electrostatic loudspeaker 1 according to the
present modification. As shown in FIG. 8, according to the present modification, the holes 21 of
the electrodes 20U and 20L and the holes 31 of the elastic members 30U and 30L overlap when
viewed from the upper surface side. In this configuration, for example, when the vibrating body
10 is displaced toward the electrode 20U, the air in the holes 31 and 21 on the upper surface
side is pushed by the vibrating body 10 and moves to the outside of the electrostatic speaker 1.
Further, below the holes 31 on the upper surface side, the holes 31 and the holes 21 are present,
so the fibers of the non-woven fabric do not prevent the movement of the air, and the air is
drawn into the holes 21 of the electrode 20U. That is, in the portion where the holes 21 of the
electrodes 20U and 20L and the holes 31 of the elastic members 30U and 30L overlap as viewed
from the upper surface side, the vibrating body 10 is less resistant to the radiation of sound. It is
easy to vibrate and a large sound pressure can be obtained.
[0039]
(Modification 6) In embodiment mentioned above, although the elastic member 30 becomes a
sheet form, the shape of the elastic member 30 is not limited to a sheet form. FIG. 9 is a
schematic view of the upper surface side of the electrode 20L according to the present
modification. In FIG. 9, a part of the upper surface side of the electrode 20L is shown enlarged.
As shown in FIG. 9, in the present modification, a rectangular parallelepiped elastic member 30A
having elasticity is discretely arranged in a plurality of rows and a plurality of columns on the
upper surface side of the electrode 20L. In the electrode 20L, the holes 21 are provided between
the adjacent elastic members 30A. Also in the electrode 20U, as in the electrode 20L, the elastic
members 30A are discretely arranged in a plurality of rows and a plurality of columns at
intervals, and the holes 21 of the electrode 20U are provided between adjacent elastic members
30A. It is done. Also in this modification, the vibrating body 10 is easily vibrated because there is
nothing to prevent the movement of air in the portion where the hole 21 is provided as viewed
from the upper surface side.
[0040]
The shape of the elastic member 30A is not limited to a rectangular parallelepiped, and may be,
for example, a pyramid (a triangular pyramid, a square pyramid, etc.) or a cone. When the shape
of the elastic member 30A is a cone, the bottom surface is adhered to the electrode 20, and the
top of the head is in contact with the vibrating body 10.
04-05-2019
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[0041]
(Modification 7) In the embodiment described above, the elastic member 30 is a non-woven
fabric, but the elastic member 30 may have insulation, transmit sound, and be formed of a
plurality of fibers. It may be heat-packed or woven cloth. Further, the elastic member 30 may be
a sponge-like synthetic resin having an insulating property. Further, the elastic member 30 may
have a configuration in which air does not pass as long as sound passes, and for example, a
sponge of elastic discontinuous bubbles may be formed into a sheet, and the holes 31 may be
provided.
[0042]
(Modification 8) In the embodiment described above, the electrostatic speaker 1 is a push-pull
type, but the electrostatic speaker 1 is a single type that does not include one of the electrode
20U or the electrode 20L. It is also good. In the case of the push-pull type, a pair of signals
having the same amplitude but different polarities is supplied to the electrostatic speaker 1, but
when the electrostatic speaker 1 is a single type, it is outputted from the terminal T11 or the
terminal T12. Signal is supplied to the electrode 20.
[0043]
(Modification 9) In the embodiment described above, although the configuration in which the
electrode 20, the vibrating body 10, and the elastic member 30 are stacked is used as a speaker
for converting an acoustic signal into a sound, this configuration converts a sound into an
acoustic signal. It is also possible to use an electrostatic microphone (electrostatic transducer).
FIG. 10 is a diagram showing a configuration of a microphone 2 according to the present
modification and an acoustic signal generation circuit 200 that generates an acoustic signal
representing a sound collected by the microphone 2. In this modification, since the microphone 2
has the same configuration as the above-described electrostatic speaker 1, the members
constituting the microphone 2 have the same reference numerals as the electrostatic speaker 1,
and the explanation of each member will be described. I omit it. Further, since the configuration
of the acoustic signal generation circuit 200 is the same as that of the drive circuit 100 except
that the direction in which the signal flows is different from that of the drive circuit 100,
components included in the acoustic signal generation circuit 200 are components included in
the drive circuit 100 The same reference numerals are given and the description of each part is
04-05-2019
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omitted. The transformation ratio of the transformer 110 and the resistance values of the
resistors R11 to R13 are appropriately adjusted.
[0044]
When the sound reaches the microphone 2, the vibrator 10 vibrates by the reached sound. When
the vibrating body 10 vibrates, the distance between the vibrating body 10 and the electrodes
20U and 20L changes, so that the capacitance between the vibrating body 10 and the electrode
20 changes.
[0045]
For example, when the vibrating body 10 is displaced toward the electrode 20U, the distance
between the electrode 20U and the vibrating body 10 is shortened, and the capacitance between
the electrode 20U and the vibrating body 10 is increased. Further, the distance between the
electrode 20L and the vibrating body 10 becomes longer, and the capacitance between the
electrode 20L and the vibrating body 10 becomes smaller. Since the electrodes 20U and 20L are
connected to the ground GND via the center tap T13 of the transformer 110, the potential of the
electrode 20U changes so that the potential difference between the electrode 20U and the
vibrating body 10 is reduced. The potential of the electrode 20L changes so that the potential
difference with the vibrator 10 increases. Here, since a potential difference occurs between the
electrode 20U and the electrode 20L, a signal flows in the secondary coil of the transformer 110.
[0046]
Further, when the vibrating body 10 is displaced to the electrode 20L side, the distance between
the electrode 20L and the vibrating body 10 becomes short, and the capacitance between the
electrode 20L and the vibrating body 10 becomes large. Further, the distance between the
electrode 20U and the vibrating body 10 becomes longer, and the capacitance between the
electrode 20U and the vibrating body 10 becomes smaller. Then, the potential of the electrode
20L changes so that the potential difference between the electrode 20L and the vibrating body
10 becomes smaller, and the potential of the electrode 20U changes so that the potential
difference between the electrode 20U and the vibrating body 10 becomes larger. Here, a
potential difference is generated between the electrode 20U and the electrode 20L, and a signal
04-05-2019
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flows in the secondary coil of the transformer 110 in the direction opposite to that when the
vibrating body 10 is displaced in the direction of the electrode 20U.
[0047]
When a signal flows through the secondary coil of the transformer 110, the signal also flows
through the primary coil of the transformer 110 in response to this signal. The signal that has
flowed to the primary coil is amplified by the amplifier 130 and the amplified signal is output
from the amplifier 130 as an acoustic signal representing the sound collected by the microphone
2. In this modification, the hole 21 is provided in the electrode 20, and the hole 31 is provided in
the elastic member 30, so the vibrating body 10 is easily vibrated as compared with a
configuration in which the hole 21 and the hole 31 are not provided. Sound can be efficiently
converted into an acoustic signal.
[0048]
In the present modification, when the impedance of the transformer 110 is low, the frequency
characteristic at a low frequency may be degraded due to the influence of the load capacity of
the microphone 2. In this case, in place of the transformer 110, an amplifier with high impedance
may be connected to the electrodes 20U and 20L to suppress a decrease in frequency
characteristics.
[0049]
In the embodiment described above, the holes 21 and the holes 31 have the same shape when
viewed from the upper surface side, and the holes 21 and the holes 31 are connected to be
continuous, but the shape of the holes 21 when viewed from the upper surface The shape of the
holes 31 may be different. In this case, it is preferable that the hole 31 be located in the region of
the hole 21 when viewed from the upper surface side, and the hole 21 and the hole 31 be
connected in series. In addition, it is preferable that a hole having a larger area as viewed from
the upper surface side be provided in the electrode 20 and a hole having a narrow area be
provided in the elastic member 30. According to these configurations, the hole located on the
outer side as viewed from the vibrating body 10 is wider, so that the sound wave can be emitted
efficiently.
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[0050]
DESCRIPTION OF SYMBOLS 1 ... Electrostatic type speaker, 2 ... Microphone, 10 ... Vibrator, 20,
20 U, 20 L ... Electrode, 30, 30 A, 30 U, 30 L ... Elastic member, 100 ... Drive circuit, 110 ...
Transformer, 111 ... DC power supply, 130 amplification part, 140 first connector, 141 second
connector 200 acoustic signal generation circuit R11 to R13 resistor
04-05-2019
17
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