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JP2013146023

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DESCRIPTION JP2013146023
Abstract: A vibrator is easily displaced when an elastic member is provided between an electrode
and a vibrator. A non-woven elastic member (30) is provided with a plurality of linear cuts along
a Y-axis direction in a plurality of rows in the Y-axis direction and in a plurality of rows in the Xaxis direction. When a plurality of cuts are made in the elastic member 30, the fibers of the nonwoven fabric constituting the elastic member 30 are cut, and the number of restrictions on the
movement of the fibers in the Z-axis direction is reduced. You can get a big sound pressure.
[Selected figure] Figure 3
Electrostatic transducer
[0001]
The present invention relates to electrostatic transducers.
[0002]
In an electrostatic speaker, there is a speaker in which a member having elasticity is disposed
between a vibrating diaphragm that vibrates and an electrode facing the diaphragm.
For example, in the speaker disclosed in Patent Document 1, an elastic body formed of sponge,
foamed polyurethane or rubber is disposed between the vibrating membrane and the fixed
electrode. Further, in the speaker disclosed in Patent Document 2, a damping member formed of
ester wool, cotton or silk is disposed between a conductive diaphragm and a plane electrode.
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[0003]
JP-A-52-46812 JP-A-2008-54154
[0004]
In the speaker of Patent Document 1, the elastic body is formed of sponge, foamed polyurethane
or rubber.
In this configuration, since the elasticity is large as compared with the damping member of
Patent Document 2 formed of fibers, the vibrating membrane is less likely to vibrate, and the
sound pressure of the sound generated from the speaker becomes low. Moreover, in the speaker
of Patent Document 2, the damping member is formed of ester wool, cotton or silk. In this
configuration, since there is a gap between the fibers forming the damping member, the damping
member is easily compressed in the direction in which the diaphragm is displaced as compared
to the elastic member of Patent Document 1, and the diaphragm is easily displaced.
[0005]
By the way, the damping member of the speaker of Patent Document 2 has a configuration in
which continuous fibers are entangled. In this configuration, when receiving force from the
diaphragm, each fiber is supported at a plurality of locations by the entangled other fibers, and
the displacement of the fibers is suppressed. The present invention has been made under the
above-described background, and it is an object of the present invention to provide a technique
for facilitating displacement of a vibrating body when an elastic member is provided between an
electrode and the vibrating body.
[0006]
In order to achieve the above object, the present invention has an electrode, a vibrator opposite
to the electrode, to which a bias voltage is applied, and elasticity, which is disposed between the
electrode and the vibrator, the vibrator And an elastic member having a cut in a region in contact
with
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[0007]
In the present invention, the elastic member may be a non-woven fabric.
Further, in the present invention, the length of the break per unit area in the first region whose
area is smaller than the vibrating body inside the edge of the vibrating body when viewed from
the normal direction of the vibrating body is the first It is good also as composition longer than
the length of the above-mentioned break per unit area in the 2nd field outside a field.
[0008]
According to the present invention, when the elastic member is provided between the electrode
and the vibrator, the vibrator can be easily displaced.
[0009]
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.
The figure which showed the cut 31 of the elastic member 30. FIG. FIG. 2 shows a configuration
of a drive circuit 100. The figure which showed the cut | notch and hole which concern on a
modification. The figure which showed the area | region in which a cut is provided in the elastic
member 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.
The figure which showed the cut | interruption which concerns on a modification.
[0010]
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 X-
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axis 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. Moreover, in FIG.2, 3,
illustration of the cut 31 mentioned later is abbreviate | omitted.
[0011]
As shown in the figure, the electrostatic loudspeaker 1 has a vibrator 10, electrodes 20U and
20L, elastic members 30U and 30L, and protection members 60U and 60L. 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 configurations of the protective member 60U and the protective
member 60L are the same. For this reason, also in these members, when it is not particularly
necessary to distinguish between a member whose code end is "U" and a member whose code
end is "L", the descriptions such as "L" and "U" are omitted. Do. 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.
[0012]
(Configuration of Each Part of Electrostatic Speaker 1) First, each part of the electrostatic speaker
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.
[0013]
The elastic member 30 is a non-woven fabric in the present embodiment and can pass air and
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sound without passing electricity, and its shape is rectangular when viewed from the top side. An
example of the non-woven fabric is, for example, one obtained by bonding fibers formed by a
spun bonding method by a chemical bonding method or a thermal bonding method. 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.
[0014]
In the elastic member 30 according to the present embodiment, a plurality of cuts are provided,
which penetrate from the upper surface side to the lower surface side and cut the fibers
constituting the non-woven fabric. FIG. 4 is a top view of the elastic member 30U. As shown in
FIG. 4, in the elastic member 30, a plurality of linear cuts 31 extending in the Y-axis direction are
provided in a plurality of rows in the Y-axis direction and a plurality of columns in the X-axis
direction. The length of the cut 31 is not limited to a specific length, and may be determined
according to the material and thickness of the fibers forming the non-woven fabric, the thickness
of the elastic member 30 in the Z-axis direction, and the like. The line spacing and line spacing of
the cuts 31 are not limited to a specific spacing, and are determined according to the material
and thickness of the fibers forming the non-woven fabric, the thickness of the elastic member 30
in the Z-axis direction, etc. You may Also, the direction in which the cut 31 is arranged is not
limited to the X-axis direction or the Y-axis direction, and may be arranged obliquely with respect
to the X-axis direction, for example. The elastic member 30 may have insulation, be transparent
to sound, and be made of a plurality of fibers, and may be a material obtained by applying heat to
the batt and compressed, a woven cloth, or the like. In the present embodiment, the length of the
elastic member 30 in the X-axis direction is longer than the length of the vibrating body 10 in
the X-axis direction, and the length of the elastic member 30 in the Y-axis direction is greater
than the length of the vibrating body 10 in the Y-axis direction Although it is longer, it is not
limited to this configuration.
[0015]
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 penetrating from the
front surface to the back surface to allow air and sound to pass therethrough, but in the
drawings, the illustration of the holes is omitted. In the present embodiment, the length in the Xaxis direction and the length in the Y-axis direction of the electrode 20 are the same as the elastic
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member 30. 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.
[0016]
The protective member 60 is a cloth having an insulating property. The protection member 60 is
rectangular when viewed from the top surface side, and allows passage of air and sound. In the
present embodiment, the length in the X axis direction of the protective member 60 and the
length in the Y axis direction are the same as those of the elastic member 30. In addition, the
protective member 60 should just have insulation, for example, may be a sheet of synthetic resin.
[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 disposed between the lower surface
side of the elastic member 30U and the upper surface side of the elastic member 30L. The
vibrating body 10 is coated with an adhesive with a width of several mm from the edge and
adhered to the elastic member 30U and the elastic member 30L, and the elastic member 30U
and the elastic member 30R inside the portion to which the adhesive is applied It is in a state of
not being fixed to the member 30L. 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 bonded to the upper surface side of the elastic member 30U. The electrode
20L is bonded to the lower surface side of the elastic member 30L. The electrode 20U is coated
with an adhesive with a width of several mm from the edge and adhered to the elastic member
30U, and the electrode 20L is coated with an adhesive with a width of several mm from the edge
with an elastic member 30L Glued to. The electrode 20 is in a state where it is not fixed to the
elastic member 30 inside the portion to which the adhesive is applied. The electrode 20U is in
contact with the elastic member 30U at the side with the conductive film, and the electrode 20L
is in contact with the elastic member 30L at the side with the conductive film. That is, the
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conductive film of the electrode 20 and the vibrator 10 face each other with the elastic member
30 interposed therebetween.
[0019]
The protective member 60U is adhered to the upper surface side of the electrode 20U. The
protective member 60L is bonded to the lower surface side of the electrode 20L. The protective
member 60U is coated with an adhesive with a width of several mm from the edge to be adhered
to the electrode 20U, and the protective member 60L is coated with an adhesive with a width of
several mm from the edge with an electrode 20L. Glued to. The protective member 60 is in a
state where it is not fixed to the electrode 20 inside the portion to which the adhesive is applied.
[0020]
Electrical Configuration of Electrostatic Speaker 1 Next, an electrical configuration of the
electrostatic speaker 1 will be described. FIG. 5 is a diagram showing the configuration of a drive
circuit 100 for driving the electrostatic speaker 1. As shown in FIG. 5, the drive circuit 100 for
driving the electrostatic speaker 1 includes the amplification unit 130, the transformer 110, the
DC power supply 111, the resistors R11 to R13, and the female first connector 140. There is.
[0021]
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.
[0022]
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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.
[0023]
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.
[0024]
(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.
[0025]
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.
[0026]
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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.
[0027]
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, the electrostatic attractive force between the vibrating body 10 and the electrode
20U is weakened, while the electrostatic attractive force between the vibrating body 10 and the
electrode 20L is intensified. 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.
[0028]
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.
[0029]
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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 waves
pass through the elastic member 30 having sound permeability, the electrode 20 and the
protection member 60 and are emitted as sound to the outside of the electrostatic speaker 1.
[0030]
When the vibrating body 10 is displaced, the elastic member 30 in contact with the vibrating
body 10 on the side where the vibrating body 10 is displaced receives the force from the
vibrating body 10. When the cut 31 is not provided in the elastic member 30, the elastic member
30 is a non-woven fabric in which continuous fibers are bonded, and the edge is adhered and
fixed. Therefore, for example, when the cut 31 is not provided in the elastic member 30 in the
cross section taken along the line A-A in FIG. 1, the surface of the elastic member 30 in contact
with the vibrator 10 has both ends in the Y axis direction. And is considered to function as a
beam receiving a force from the vibrating body 10. On the other hand, when a plurality of cuts
are made in the elastic member 30, when each fiber of the non-woven fabric constituting the
elastic member 30 is cut, it is considered that the end of the cut fiber behaves as a free end. For
this reason, in FIG. 4, between the cuts 31 adjacent to each other in the direction of the Y axis, in
the Y axis direction, the beam is not a beam fixed at both ends, and a structure including cut free
end fibers is obtained. Fewer things limit the movement of each fiber. That is, when the cut is
provided, the stiffness in the direction in which the elastic member 30 is compressed is lowered
as compared with the case where the cut is not provided.
[0031]
Here, in comparison with the elastic member 30 in the case where the cut 31 is provided and the
case where the cut 31 is not provided, the number of the cut 31 is plural because the number of
restricting the movement of the fiber is small. The arrangement provided in a row is more likely
to be displaced in the positive and negative directions of the Z axis. The ease of displacement
means that even if the same electrostatic attractive force works, the displacement amount of the
vibrating body 10, that is, the amplitude of the vibrating body 10 becomes larger in the case
where the cut 31 is provided, and a large sound pressure is obtained. be able to. In particular,
with respect to sound at frequencies lower than the lowest resonance frequency, a larger sound
pressure can be obtained as compared with the case where the cut 31 is not provided.
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[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 embodiment described above, although a plurality of linear cuts 31 are
provided in the elastic member 30, the pattern of the cuts is not limited to that shown in FIG. For
example, as shown to (a) of FIG. 6, it may be a pattern in which the cuts 31 having different
longitudinal directions are alternately arranged in a predetermined direction. Further, as shown
in (b) to (e) of FIG. 6, a pattern in which two linear cuts 31 intersect with each other may be
alternately arranged in a predetermined direction. When cutting the fibers of the non-woven
fabric which is the elastic member 30, for example, the fibers of the non-woven fabric may be cut
by providing a plurality of holes penetrating from the upper surface side to the lower surface
side of the elastic member 30. . In this case, the holes provided in the elastic member 30 may
have a circular shape as viewed from the upper surface side like the holes 32a shown in (f) of
FIG. 6, and the holes shown in (g) of FIG. The shape seen from the upper surface side like 32 b
may be rectangular. Further, the cut 31 may not be straight, and may be, for example, a cut 31 of
a curve as shown in (h) of FIG.
[0034]
(Modification 2) In the above-described embodiment, the cut 31 is provided in a plurality of rows
and a plurality of columns over substantially the entire surface of the elastic member 30, but the
cut 31 may be provided in a specific region of the elastic member 30. Good. FIG. 7 is a view of
the elastic member 30 according to the present modification viewed from the top side, and is a
view for explaining the arrangement position of the cut 31. In FIG. 7, the vibrating body 10 is
indicated by a broken line. As shown in FIG. 7, in the area A1 (the first area shown by hatching)
inside the edge of the vibrating body 10 as viewed from the upper surface side (the normal
direction of the vibrating body 10), the cut 31 is provided The cut 31 may not be provided in the
second region outside A1. In this modification, the distance a1 from the edge in the Y-axis
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positive direction of the area A1 to the edge in the Y-axis positive direction of the vibrating body
10 and the Y-axis of the vibrating body 10 from the edge in the Y-axis negative direction of the
area A1 Distance a2 to the edge in the negative direction is equal, distance a3 from the edge in
the positive direction of the X axis of region A1 to the edge in the positive direction of X axis of
vibrating body 10, and from the edge in the negative direction of X axis of region A1 to vibrating
body 10 It is preferable that the distances a4 to the edge in the negative direction of the X axis
be equal. Further, in the elastic member 30, it is more preferable that the distances a1 to a4 be
equal.
[0035]
According to this modification, comparing the outside and the inside of the area A1, since the cut
31 is not provided outside the area A1, the displacement amount of the vibrating body 10
becomes smaller than the area A1 outside the area A1. . As a result, in the electrostatic speaker 1,
the sound pressure of the sound emitted from the region near the edge is lower than the sound
pressure of the sound emitted from the region A1, so that the side lobe of the directivity
characteristic can be suppressed. it can. In the case where the cut 31 is provided also outside the
area A1, the interval of the cut 31 may be made wider than the area A1 in the area outside the
area A1. That is, in the area outside the area A1, the number of cuts 31 per unit area is made
smaller than that in the area A1, and the length of the break in the area A1 per unit area is longer
than the area outside the area A1. Good. Also in this configuration, since the displacement
amount of the vibrating body 10 is smaller than the area A1 outside the area A1, the side lobe of
the directivity characteristic of the electrostatic speaker 1 can be suppressed as described above.
[0036]
Moreover, in order to make the sound pressure of the sound emitted from the second area
outside the area A1 lower than the sound pressure of the sound emitted from the area A, the cut
is made between the area A1 and the area outside the area A1. The pattern of may be made
different. For example, the cut 31 shown in (b) and (d) of FIG. 6 may be provided in the area A1,
and the linear cut 31 shown in FIG. 4 may be provided in the area outside the area A1. . In the
case of this configuration, it is preferable to make the pitch of the cuts the same in the area A1
and outside the area A1. According to this configuration, the cut 31 shown in FIG. 4 has a shorter
length for cutting the elastic member 30 than the cut 31 shown in (b) and (d) of FIG. 6 and the
area outside the area A1 is the area The amount of displacement of the vibrating body 10 is
smaller than the area A1 outside the area A1 because it is cut less than A1. As a result, in the
electrostatic speaker 1, the sound pressure of the sound emitted from the region near the edge is
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lower than the sound pressure of the sound emitted from the region A1, so that the side lobe of
the directivity characteristic is suppressed. Can. When the elastic member 30 is divided into a
plurality of regions, the number of regions is not limited to two, and may be three or more. In
addition, the pitch of the cuts may be gradually increased from the inside to the outside of the
elastic member 30 instead of clearly dividing the area.
[0037]
(Modification 3) In the embodiment described above, when viewed from the upper surface side,
the shapes of the vibrator 10, the electrode 20, the elastic member 30, and the protective
member 60 are rectangular, but each shape is limited to rectangular It is not something to be
done. For example, the shape of each member may be circular or elliptical, or may be polygonal
other than rectangular. Moreover, the shape of each member viewed from the upper surface side
may be a shape surrounded by a free curve.
[0038]
(Modification 4) In the embodiment described above, when providing the cut 31 in the elastic
member 30, the elastic member 30 is adhered to the electrode 20 before adhering the vibrating
body 10 to the elastic member 30, and from the upper surface side of the electrode 20 A cut may
be provided on the lower surface side of the elastic member 30. In addition, even when the holes
32a and the holes 32b are provided in the elastic member 30, the elastic member 30 is adhered
to the electrode 20 before adhering the vibrating body 10 to the elastic member 30, and the
lower surface of the elastic member 30 from the upper surface side of the electrode 20 A
through hole may be provided on the side.
[0039]
(Modification 5) In the embodiment described above, although the elastic member 30 is provided
with the cut 31 in the rectangular non-woven fabric, the elastic member 30 may be formed by
arranging a plurality of strip non-woven fabrics. Alternatively, the elastic member 30 may be
formed by arranging rectangular non-woven fabrics in a plurality of rows and a plurality of
columns. In this configuration, the fibers of the non-woven fabric are shorter as compared to the
configuration in which a single non-woven fabric without the cut 31 is used as the elastic
member 30, and the vibrating body 10 is in the positive direction of the Z axis as in the above
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embodiment. And it becomes easy to displace in the negative direction.
[0040]
(Modification 6) 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.
[0041]
(Modification 7) In the embodiment mentioned above, although elastic member 30 was a
nonwoven fabric, if it has cut 31 or holes 32a and 32b, it is what made synthetic resin which has
insulation sponged, etc. May be Also, the elastic member 30 may be configured so that air does
not pass as long as sound passes, and for example, a sponge of elastic discontinuous bubbles is
formed into a sheet, and the cut 31 or the holes 32a and 32b are provided. The elastic member
30 may be used. The holes 32 a and the holes 32 b are provided by cutting the elastic member
30, and thus can be considered as an example of a cut.
[0042]
(Modification 8) In the embodiment mentioned above, although cut 31 penetrates from the upper
surface side of elastic member 30 to the undersurface side, it is not limited to penetration
composition. As long as the fibers forming the elastic member 30 are cut, the cut 31 may be
provided so as not to penetrate the elastic member 30 in the Z-axis direction. In the case of this
modification, the electrostatic speaker 1 is configured such that the side of the elastic member
30 where the cut 31 is provided contacts the vibrating body 10.
[0043]
(Modification 9) In the embodiment described above, although the configuration in which the
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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. 8 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, parts
included in the acoustic signal generation circuit 200 The same reference numerals are given
and the description of each part is 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.
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[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
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, since the cut 31 is provided in the elastic member 30, the vibrator 10 is
easily displaced as compared with the configuration in which the cut 31 is not provided, and
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]
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16
(Modification 10) The embodiment described above is not limited to the configuration in which a
plurality of cuts 31 are provided. For example, as shown in (a) of FIG. 9, one cut 31 of ninety-nine
fold may be provided in the elastic member 30, and as shown in (b) of FIG. One cut 31 may be
provided in the elastic member 30.
[0050]
DESCRIPTION OF SYMBOLS 1 ... Electrostatic type speaker, 2 ... Microphone, 10 ... Vibrator, 20,
20 U, 20 L ... Electrode, 30, 30 U, 30 L ... Elastic member, 60, 60 U, 60 L ... Protective member,
100 ... Drive circuit, 110 ... Transformation , 111: DC power supply, 130: amplification unit, 140:
first connector, 141: second connector, 200: acoustic signal generation circuit, R11 to R13:
resistor
11-05-2019
17
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