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JP2013059019

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DESCRIPTION JP2013059019
Abstract: A directional characteristic is improved without performing complicated processing on
a vibrator or an electrode. An electrostatic speaker 1 has a configuration in which a rectangular
second sound emitting unit 3, a rectangular frame-shaped insulating member 10, and a
rectangular first sound emitting unit 2 are overlapped when viewed from the upper surface side.
There is. The first sound emitting unit 2 sandwiches the vibrating body 210 with the electrodes
220U and 220L, and the second sound emitting unit 3 sandwiches the vibrating body 310 with
the electrodes 320U and 320L. The vibrating body 210 and the vibrating body 310 vibrate in the
same direction. The vibrating body 310 has a larger area than the vibrating body 210, and in a
region where the vibrating body 310 and the vibrating body 210 do not overlap when viewed
from the upper surface side, the sound pressure is lower than a region where the vibrating body
210 and the vibrating body 310 overlap. . In the electrostatic speaker 1, the sound pressure on
the edge side is low as viewed from the top side, and the side lobes become small. [Selected
figure] Figure 1
Electrostatic transducer
[0001]
The present invention relates to an electrostatic electroacoustic transducer.
[0002]
As inventions for controlling the directional characteristics of the electrostatic speaker, for
example, there are inventions disclosed in Patent Document 1 and Patent Document 2.
04-05-2019
1
The invention disclosed in Patent Document 1 is configured to include a vibrating membrane
between two flat plate electrodes, and the vibrating membrane is configured to increase the
surface density as it approaches the outer edge of the vibrating membrane. ing. According to this
configuration, in the region where the surface density is large in the vibrating film, the amplitude
decreases and the sound pressure of the generated sound decreases, so that the side lobe is
suppressed. The invention disclosed in Patent Document 2 also has a configuration in which a
vibrating film is provided between two electrodes. In the invention of Patent Document 2, a
plurality of regions having different intervals between the vibrating membrane and the
electrodes are provided. In the electrostatic loudspeaker, the electrostatic force acting on the
vibrating membrane is inversely proportional to the square of the distance between the vibrating
membrane and the electrode, so that the sound pressure of the sound generated from the
vibrating membrane will be different if the spacing is different. For this reason, if the distance
between the diaphragm and the electrode is increased in the area near the outer edge in the
electrostatic speaker, the sound pressure in the area near the outer edge is reduced, so that the
side lobe is suppressed.
[0003]
JP, 2007-274363, A JP, 2007-274362, A
[0004]
Now, in the invention of Patent Document 1, although it is necessary to increase the surface
density of the vibrating film toward the outer edge, it is necessary to configure the vibrating body
so that the surface density differs in a plurality of regions in one vibrating film. difficult.
Although a method using a plurality of diaphragms different in surface density instead of one
diaphragm may be considered, this configuration requires a wiring for supplying a bias voltage
for each diaphragm. Further, in the invention of Patent Document 2, although it is necessary to
make the distance between the electrode and the vibrating film different in a plurality of regions,
if the electrode is to be formed by one sheet, processing of the electrode becomes difficult. Also,
it is conceivable to use a plurality of electrodes instead of one electrode to make the distance
between each electrode and the vibrating film different. However, this configuration requires a
wiring for supplying a signal to each electrode. I will. In addition, a configuration in which a
vibrating film is sandwiched between a pair of electrodes can also be used as an electrostatic
microphone. If the surface density of the diaphragm and the distance between the electrodes and
04-05-2019
2
the diaphragm are as described above, the directivity characteristic can be controlled even in the
electrostatic microphone, but the above-mentioned problems are the same as in the electrostatic
speaker. It can occur.
[0005]
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 improving directivity characteristics without
performing complicated processing on a vibrator or an electrode.
[0006]
In order to solve the problems described above, the present invention is an electrostatic
electroacoustic transducer having a plurality of vibrators and a plurality of electrodes, wherein
the plurality of vibrators are directed in the normal direction of the vibrators. Overlapping, at
least a part of the outer edge side viewed from the normal direction of the vibrating body has a
region where the number of overlapping of the vibrating body is the smallest, the electrode faces
the vibrating body and a distance from the vibrating body To provide an electrostatic electroacoustic transducer characterized in that
[0007]
In the present invention, the other vibrator may be disposed inside the edge of the vibrator
having the largest area as viewed in the normal direction.
Further, in the present invention, the plurality of vibrators may have different areas, and the
vibrators having a narrow area may be disposed inside the edge of the vibrator having a large
area when viewed from the normal direction. Good.
Further, in the present invention, the number of overlapping of the vibrators as viewed from the
normal direction decreases in the first direction along the surface of the vibrators from the
center toward the outer edge, and on the surface of the vibrators. It is good also as composition
which is the same about the 2nd direction which intersects the above-mentioned 1st direction
along. Further, in the present invention, the number of overlapping of the vibrators as viewed
from the normal direction decreases in the first direction along the surface of the vibrators from
the center toward the outer edge, and on the surface of the vibrators. The second direction
crossing the first direction may be configured to decrease from the center toward the outer edge.
04-05-2019
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[0008]
According to the present invention, directivity characteristics can be improved without
performing complicated processing on a vibrator or an electrode.
[0009]
The figure which showed the plane, the side, and the front of electrostatic loudspeaker 1
concerning a 1st embodiment of the present invention.
The exploded view of electrostatic type speaker 1. 1. AA sectional view taken on the line of FIG.
FIG. 2 shows a configuration of a drive circuit 100. The figure which showed the plane, the side,
and the front of electrostatic-type speaker 1A which concerns on 2nd Embodiment. FIG. 2 shows
a configuration of a drive circuit 100A. The figure which showed the plane, the side, and the
front of electrostatic loudspeaker 1B concerning 3rd Embodiment. FIG. 2 shows a configuration
of a drive circuit 100B. The figure which showed the plane, the side, and the front of electrostatic
speaker 1C concerning a modification. The figure which showed the plane, the side, and the front
of electrostatic-type speaker 1D which concerns on a modification. The figure which showed the
plane, the side, and the front of electrostatic-type speaker 1E concerning a modification. The
figure which showed the plane, the side, and the front of electrostatic-type speaker 1F
concerning a modification. The figure which showed the plane, the side, and the front of
electrostatic speaker 1G concerning a modification. FIG. 2 is a diagram showing an electrical
configuration according to an electrostatic microphone 5;
[0010]
First Embodiment FIG. 1 (a) is a plan view of an electrostatic speaker 1 (electrostatic
electroacoustic transducer) according to an embodiment of the present invention, and FIG. 1 (b)
is a side view of the electrostatic speaker 1. FIG. 1C is a front view of the electrostatic speaker 1.
FIG. 2 is an exploded view of the electrostatic speaker 1. As shown in the figure, the electrostatic
loudspeaker 1 has a configuration in which a first sound emitting unit 2, an insulating member
10, and a second sound emitting unit 3 are stacked. 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-axis direction, and the depth direction is the Y-axis
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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. Further, in the drawings, those in which “•” is described
in “o” means an arrow directed from the back to the front of the drawing. Further, in the
drawings, those in which “x” is described in “o” means an arrow directed from the front to
the back of the drawing. 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.
[0011]
First, the structure of the electrostatic speaker 1 will be described. FIG. 3 is a cross-sectional view
of the electrostatic speaker 1 taken along line AA. The electrostatic speaker 1 includes a first
sound emitting unit 2 and a second sound emitting unit 3. The electrostatic speaker 1 has a
configuration in which the insulating member 10 is stacked on the second sound emitting unit 3
and the first sound emitting unit 2 is stacked on the insulating member 10. The first sound
emitting unit 2 and the second sound emitting unit 3 have a rectangular shape when viewed
from the upper surface side, and the shape when the first sound emitting unit 2 is viewed from
the upper surface side and the second sound emitting unit 3 from the upper surface side The
shapes seen are similar. Each of the first sound emitting unit 2 and the second sound emitting
unit 3 is a push-pull electrostatic speaker. Therefore, the electrostatic loudspeaker 1 according to
the present embodiment has a configuration in which two sets of electrostatic loudspeakers
having different areas and similar in shape are overlapped with the insulating member 10
interposed therebetween.
[0012]
In the present embodiment, the insulating member 10 is a synthetic resin having an insulating
property, and its shape is a rectangular frame when viewed from the upper surface side. In the
present embodiment, the length of the insulating member 10 in the X-axis direction is the same
as the length of the first sound emitting portion 2 in the X-axis direction. Further, the length of
the insulating member 10 in the Y-axis direction is the same as the length of the first sound
emitting portion 2 in the Y-axis direction. That is, when viewed from the upper surface side, the
shape of the outer periphery of the insulating member 10 is the same as the shape of the outer
periphery of the first sound emitting portion 2.
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[0013]
The first sound emitting unit 2 includes a vibrator 210, electrodes 220U and 220L, and elastic
members 230U and 230L. In the present embodiment, the configurations of the electrode 220U
and the electrode 220L are the same, and the configurations of the elastic member 230U and the
elastic member 230L 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. .
[0014]
The rectangular vibrating body 210 viewed from the top side is made of a film (insulating layer)
of an insulating and flexible synthetic resin such as PET (polyethylene terephthalate) or PP
(polypropylene), as a film. A conductive metal is vapor-deposited on one surface of the sheet 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. In addition, the
vibrating body 210 may have a configuration in which a conductive metal is rolled to form a film.
[0015]
The elastic member 230 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. In
the present embodiment, the length of the elastic member 230 in the X-axis direction is the same
as the length of the vibrating body 210 in the X-axis direction, and the length of the elastic
member 230 in the Y-axis direction is also the length of the vibrating body 210 in the Y-axis
direction. It has become the same. In addition, the elastic member 230 has elasticity, and is
deformed when an external force is applied, and returns to the original shape when an externally
applied force is removed. The elastic member 230 may be a member having insulation, sound
transmission, and elasticity, and it is formed by applying heat to the batt and compressing it, a
woven cloth, and a synthetic resin having insulation to be spongy Or the like. Further, the elastic
member 230 may have a configuration in which air does not pass as long as sound passes
therethrough. For example, a sponge of an elastic and discontinuous bubble may be formed into
a sheet to be the elastic member 230.
04-05-2019
6
[0016]
The electrode (fixed electrode) 220 uses a film (insulating layer) of insulating synthetic resin
such as PET or PP as a base material, and conductive metal is deposited on one surface of the
film to form a conductive film (conductive layer) ) Is formed. The electrode 220 has a rectangular
shape when viewed from the upper surface side, and includes a plurality of holes penetrating
from the front surface to the back surface to allow air and sound to pass therethrough. In the
drawings, the illustration of the holes is omitted. In the present embodiment, the length of the
electrode 220 in the X-axis direction is the same as the length of the elastic member 230 in the
X-axis direction, and the length of the electrode 220 in the Y-axis direction is also the length of
the elastic member 230 in the Y-axis direction. It is the same. Similar to the vibrator 210, the
electrode 220 may be formed into a film by rolling a conductive metal. The electrode 220 may
not have flexibility as long as it has conductivity, and may be, for example, a punching metal.
[0017]
In the first sound emitting portion 2, the vibrating body 210 is disposed between the lower
surface of the elastic member 230U and the upper surface of the elastic member 230L. The
vibrating member 210 is coated with an adhesive with a width of several mm from the edge on
the positive direction side and the negative direction side of the X axis and the edge on the
positive direction side and the negative direction side of the Y axis. The adhesive is applied to the
elastic member 230L, and the inner side of the portion to which the adhesive is applied is not
adhered to the elastic member 230U and the elastic member 230L.
[0018]
The electrode 220U is bonded to the upper surface side of the elastic member 230U. The
electrode 220L is bonded to the lower surface side of the elastic member 230L. The electrode
220U is applied with an adhesive having a width of several mm inward from the positive
direction side and the negative direction side edge of the X axis and the positive direction side
and the negative direction edge of the Y axis and is adhered to the elastic member 230U The
electrode 220L is coated with an adhesive having a width of several mm from the edges on the
positive direction side and the negative direction side of the X axis and the edges on the positive
direction side and the negative direction side of the Y axis. Glued to. The electrode 220 is not
fixed to the elastic member 230 inside the portion to which the adhesive is applied. The electrode
04-05-2019
7
220U is in contact with the elastic member 230U at the side with the conductive film, and the
side with the conductive film is in contact with the elastic member 230L. That is, the conductive
film of the electrode 220 and the vibrator 210 face each other with the elastic member 230
interposed therebetween.
[0019]
Next, the second sound emitting unit 3 includes a vibrating body 310, electrodes 320U and
320L, and elastic members 330U and 330L. The configurations of the electrode 320U and the
electrode 320L are the same, and the configurations of the elastic member 330U and the elastic
member 330L 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. .
[0020]
The vibrating body 310 differs from the vibrating body 210 only in the dimensions in the X-axis
direction and the Y-axis direction, and the other configuration is the same as that of the vibrating
body 210. The length in the X-axis direction of the vibrating body 310 is shorter than that of the
vibrating body 210, and the length in the Y-axis direction is shorter than that of the vibrating
body 210. Therefore, the vibrating body 310 is similar in shape to the vibrating body 210 and
has a different area. The electrodes 320 U and 320 L also differ from the electrode 220 only in
the dimensions in the X-axis direction and the Y-axis direction, and the other configurations are
the same as the electrode 220. In the present embodiment, the dimensions in the X-axis direction
and the Y-axis direction of the electrode 320 are the same as those of the vibrating body 310.
The elastic members 330U and 330L also differ from the elastic member 230 only in the
dimensions in the X-axis direction and the Y-axis direction, and the other configurations are the
same as the elastic member 230. In the present embodiment, the dimensions of the elastic
member 330 in the X-axis direction and the Y-axis direction are the same as those of the
vibrating body 310.
[0021]
Also in the second sound emitting unit 3, an adhesive is applied to each member with a width of
several mm from the edge, and the electrode 320L, the elastic member 330L, the vibrator 310,
04-05-2019
8
the elastic member 330U, and the electrode 320U are overlapped in this order And glued
together. Note that the side with the conductive film is in contact with the elastic member 330U
in the electrode 320U, and the side with the conductive film is in contact with the elastic member
330L in the electrode 320L. That is, the conductive film of the electrode 320 and the vibrator
310 are opposed to each other with the elastic member 230 interposed therebetween.
[0022]
In the electrostatic speaker 1, an adhesive is applied to the lower surface side of the insulating
member 10, and the insulating member 10 is bonded to the upper surface side of the second
sound emitting unit 3. When the insulating member 10 is adhered to the upper surface side of
the second sound emitting portion 3, the position of the intersection of the diagonals of the
rectangular insulating member 10 and the rectangular second sound emitting portion 3 when
viewed from the upper surface It aligns and adheres so that the position of the intersection of a
diagonal may overlap. Further, the adhesive is applied also to the upper surface side of the
insulating member 10, and the first sound emitting unit 2 is adhered to the upper surface side of
the insulating member 10. When bonding the lower surface side of the first sound emitting unit
2 to the insulating member 10, when viewed from the upper surface side, the position of the
intersection of the diagonals of the insulating member 10 and the diagonal of the rectangular
first sound emitting unit 2 It aligns and adheres so that the position of an intersection may
overlap.
[0023]
Since the shapes of the first sound emitting unit 2 and the second sound emitting unit 3 are
similar when viewed from the upper surface side, the intersections of the diagonals of the first
sound emitting unit 2, the insulating member 10 and the second sound emitting unit 3 And the
distance a1 from the side on the right side of the first sound emitting portion 2 to the side on the
right side of the second sound emitting portion 3 when viewed from the upper surface side, and
the first sound emitting portion 2 The distance a2 from the side on the left side to the side on the
left side of the second sound emitting unit 3 is the same. The distance b1 from the side of the
first sound emitting portion 2 in the positive direction of the Y axis to the side in the positive
direction of the Y axis in the second sound emitting portion 3 as viewed from the top side The
distance b2 from the side on the negative side of the Y axis in the 1 sound emitting part 2 to the
side on the negative direction side in the Y axis on the second sound emitting part 3 is the same.
That is, the electrostatic speaker 1 has a point symmetrical shape when viewed from the upper
surface side.
04-05-2019
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[0024]
Next, an electrical configuration for driving 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.
The electrostatic speaker 1 includes an amplification unit 130, a transformer 110 which is a
boosting means, a bias power supply 120 for applying a DC bias voltage to the vibrating body
210 and the vibrating body 310, and female connectors 140A and 140B. The drive circuit 100
provided is connected. On the other hand, the electrostatic speaker 1 includes male connectors
141A and 141B which are fitted to the connectors 140A and 140B. The electrostatic loudspeaker
1 and the drive circuit 100 constitute a loudspeaker system.
[0025]
The amplification unit 130 is an amplification unit that amplifies and outputs an input acoustic
signal. The amplification unit 130 is connected to both ends of the primary coil of the
transformer 110. The AC acoustic signal amplified by the amplification unit 130 is supplied to
the primary coil of the transformer 110. The center tap of the secondary coil of the transformer
110 is connected to the ground GND which is the reference potential of the drive circuit 100.
One terminal of the secondary coil of transformer 110 is connected to the first terminal of
connectors 140A and 140B, and the other terminal of the secondary coil of transformer 110 is
connected to the third terminal of connectors 140A and 140B. It is done. The positive side of the
bias power supply 120 is connected to the second terminal of the connectors 140A and 140B via
the resistor R1, and the negative side of the bias power supply 120 is connected to the ground
GND.
[0026]
The first terminal of the male connector 141A is connected to the electrode 220U by a cable, and
the third terminal of the connector 141A is connected to the electrode 220L by a cable. Further,
the second terminal of the connector 141A is connected to the vibrating body 210 by a cable.
The first terminal of the male connector 141B is connected to the electrode 320U by a cable, and
the third terminal of the connector 141B is connected to the electrode 320L by a cable. Further,
the second terminal of the connector 141B is connected to the vibrating body 310 by a cable.
The terminals of the connectors 140A and 140B and the connectors 141A and 141B are
04-05-2019
10
insulated.
[0027]
Next, the operation of the first embodiment will be described. When driving the electrostatic
speaker 1 with the drive circuit 100, the connector 141A is fitted to the connector 140A and the
connector 141B is fitted to the connector 140B. Thereby, one terminal of the secondary coil of
transformer 110 is connected to electrode 220U and electrode 320U, and the other terminal of
the secondary coil of transformer 110 is connected to electrode 220L and electrode 320L. Also,
the resistor R 1 is connected to the vibrating body 210 and the vibrating body 310.
[0028]
After the electrostatic speaker 1 and the drive circuit 100 are connected by the connector, when
an AC acoustic signal is input to the amplification unit 130, the input acoustic signal is amplified
and supplied to the primary coil of the transformer 110. Ru. An acoustic signal boosted by the
transformer 110 and output from one terminal of the secondary coil is opposite in polarity to the
acoustic signal output from the other terminal of the secondary coil. Here, when a positive
acoustic signal is output from the first terminal of the connectors 140A and 140B and a negative
acoustic signal is output from the third terminal of the connectors 140A and 140B, a positive
voltage is applied to the electrodes 220U and 320U. As a result, a negative voltage is applied to
the electrodes 220L and 320L.
[0029]
In the above case, since a positive voltage is applied to the vibrating body 210 of the first sound
emitting unit 2 by the bias power supply 120, the vibrating body 210 is in a static state between
the vibrating body 210 and the electrode 220U to which the positive voltage is applied. While
the electrostatic attraction is weakened, the electrostatic attraction between the electrode 220L
to which a negative voltage is applied becomes stronger. Then, the vibrator 210 is displaced
toward the electrode 220L (in the negative direction of the Z axis) according to the difference
between the electrostatic attraction acting on the electrode 220U and the electrostatic attraction
acting on the electrode 220L. Further, in the above case, since a positive voltage is applied to the
vibrating body 310 of the second sound emitting unit 3 by the bias power supply 120, the
vibrating body 310 is between the electrode 320 U to which the positive voltage is applied.
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While the electrostatic attraction between the electrode 320L to which a negative voltage is
applied becomes stronger. Then, the vibrator 310 is displaced toward the electrode 320L (in the
negative direction of the Z axis) according to the difference between the electrostatic attraction
acting on the electrode 320U and the electrostatic attraction acting on the electrode 320L. That
is, the vibrating body 210 and the vibrating body 310 are displaced in the same direction. In the
present embodiment, since the polarity of the acoustic signal supplied to the electrode 220L and
the polarity of the acoustic signal supplied to the electrode 320U are opposite to each other, the
electrode 220U and the electrode 220U are affected by electrostatic attraction acting between
these electrodes. The electrodes 220L and 320U preferably have high rigidity (large Young's
modulus) so as not to displace the electrodes 320U. Further, in order to prevent the displacement
of the electrode 220L and the electrode 320U, the dimension of the insulating member 10 in the
Z-axis direction may be increased.
[0030]
Next, when the polarity of the acoustic signal changes, and a negative acoustic signal is output
from the first terminal of the connectors 140A and 140B and a positive acoustic signal is output
from the third terminal of the connectors 140A and 140B, the electrode 220U, A negative
voltage is applied to 320 U, and a positive voltage is applied to the electrodes 220 L and 320 L.
In this case, in the first sound emitting unit 2, a positive voltage is applied to the vibrating
member 210, so the vibrating member 210 weakens the electrostatic attractive force with the
electrode 220L to which the positive voltage is applied. On the other hand, the electrostatic
attractive force with the electrode 220U to which a negative voltage is applied is intensified.
Then, the vibrator 210 is displaced toward the electrode 220U (in the positive direction of the Z
axis) according to the difference between the electrostatic attraction acting on the electrode
220U side and the electrostatic attraction acting on the electrode 220L side. Further, in the
second sound emitting unit 3, since a positive voltage is applied to the vibrating body 310, while
the electrostatic attractive force between the vibrating body 310 and the electrode 320L to
which the positive voltage is applied is weakened. The electrostatic attraction between the
electrodes 320 U to which a negative voltage is applied is intensified. Then, the vibrating body
310 is displaced toward the electrode 320U (the positive direction of the Z axis) according to the
difference between the electrostatic attraction acting on the electrode 320U side and the
electrostatic attraction acting on the electrode 320L side. That is, even in this case, the vibrating
body 210 and the vibrating body 310 are displaced in the same direction.
[0031]
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As described above, the vibrators 210 and 310 are displaced in the positive direction of the Z
axis and the negative direction of the Z axis in accordance with the polarity of the acoustic signal,
and the displacement direction and the displacement amount thereof are in accordance with the
acoustic signal. By changing sequentially, it becomes a vibration, and a sound wave
corresponding to the vibration state (frequency, amplitude, phase) is generated from the
vibrators 210 and 310. Since the vibrators 210 and 310 are displaced in the same direction,
sound waves of the same phase are generated from each vibrator. The generated sound waves
pass through an elastic member or electrode having sound permeability and are emitted as
sound to the outside of the electrostatic speaker 1.
[0032]
Here, in a region where the vibrator 210 and the vibrator 310 do not overlap when the
electrostatic speaker 1 is viewed from the top side (the normal direction of the vibrator), only the
sound wave generated from the vibrator 310 is emitted. . On the other hand, in a region where
the vibrator 210 and the vibrator 310 overlap when the electrostatic speaker 1 is viewed from
the upper surface side, the sound wave generated from the vibrator 210 and the sound wave
generated from the vibrator 310 are added and emitted. Ru. Therefore, the sound pressure of the
sound generated from the area where the vibrator 210 and the vibrator 310 overlap when the
electrostatic speaker 1 is viewed from the upper surface side is higher than the sound pressure
of the sound generated from the non-overlapping area .
[0033]
As described above, in the electrostatic speaker 1, an area where the vibrator 210 and the
vibrator 310 do not overlap when the electrostatic speaker 1 is viewed from the top side (the
outer edges in the positive and negative directions of the X axis and the positive and negative
directions of the Y axis The sound pressure of the sound generated from the area including the
(1) is the area where the vibrating body 210 and the vibrating body 310 overlap when the
electrostatic speaker 1 is viewed from the top side (the vibrating body 210 inside the edge when
viewed from the top side) And the sound pressure of the sound generated from the region where
the vibrator 310 overlaps with each other. For this reason, in comparison with a conventional
electrostatic speaker configured of a single vibrating body having a constant surface density and
a pair of electrodes having a constant distance, the electrostatic speaker 1 of the present
embodiment The side lobes become smaller. As the side lobes become smaller, the main lobe
makes it possible to emit sound only in a specific direction. That is, in the present embodiment,
the directivity of the sound generated from the electrostatic speaker 1 is improved. Further, in
04-05-2019
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the present embodiment, since the shapes of the vibrating body 210 and the vibrating body 310
are similar, when arranged so that the intersections of the diagonals of the vibrating bodies
overlap as viewed from the upper surface side, the vibrating body viewed from the upper surface
side The distance from the edge of 310 to the edge of the vibrator 210 is the same in the X-axis
direction and the same in the Y-axis direction. That is, since each distance of a1, a2, b1 and b2 in
FIG. 5 is the same when viewed from the upper surface side, in the positive direction of X axis,
the negative direction of X axis, the positive direction of Y axis and the negative direction of Y
axis The side lobes become smaller equally.
[0034]
Second Embodiment Next, a second embodiment of the present invention will be described. FIG.
5 is a view showing the front, the top, and the side of the electrostatic loudspeaker 1A according
to the present embodiment. As shown in the figure, the electrostatic loudspeaker 1A has a
configuration in which a first sound emitting unit 2A, an insulating member 10, and a second
sound emitting unit 3A are stacked. The first sound emitting unit 2A is different from the first
sound emitting unit 2 of the first embodiment in that the first sound emitting unit 2A does not
include the elastic member 230L and the electrode 220L, and the other configuration is the same
as the first sound emitting unit 2. Further, the second sound emitting unit 3A is different from
the second sound emitting unit 3 of the first embodiment in that the second sound emitting unit
3A does not include the elastic member 330L and the electrode 320L, and the other
configuration is the same as the second sound emitting unit 3. . That is, the first sound emitting
unit 2A is a single-type electrostatic speaker including one electrode and one vibrator. In
addition, the second sound emitting unit 3A is also a single-type electrostatic speaker including
one electrode and one vibrator. Therefore, as in the first embodiment, the electrostatic
loudspeaker 1A has a configuration in which two sets of electrostatic loudspeakers having
different areas and similar in shape are overlapped with the insulating member 10 interposed
therebetween. .
[0035]
In the electrostatic speaker 1A, an adhesive is applied to the lower surface of the insulating
member 10, and the insulating member 10 is bonded to the upper surface of the second sound
emitting unit 3A (electrode 320U). When the insulating member 10 is bonded to the upper
surface of the second sound emitting unit 3A, the position of the intersection of the diagonal of
the insulating member 10 and the rectangular second discharge when viewed from the upper
surface side (positive side of the Z axis) It aligns and adheres so that the position of the
04-05-2019
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intersection of the diagonal of the sound part 3A may overlap. In addition, an adhesive is applied
also to the upper surface of the insulating member 10, and the first sound emitting portion 2A
(the vibrating body 210) is adhered to the upper surface of the insulating member 10. When
bonding the lower surface of the first sound emitting portion 2A to the insulating member 10,
when viewed from the upper surface side, the position of the intersection of the diagonals of the
insulating member 10 and the intersection of the diagonal of the rectangular first sound emitting
portion 2A It is aligned and bonded so that it overlaps with the position of.
[0036]
When the positions of the respective sound emitting portions and the insulating member 10 are
aligned and adhered in this manner, as in the first embodiment, the second sound emitting
portion 3A is viewed from the right side of the first sound emitting portion 2A as viewed from
the front side. The distance a1 to the right side and the distance a2 from the left side of the first
sound emitting unit 2A to the left side of the second sound emitting unit 3A are the same. The
distance b1 from the side of the first sound emitting portion 2A in the positive direction of the Y
axis to the side in the positive direction of the Y axis in the second sound emitting portion 3A as
viewed from the top side The distance b2 from the side in the negative direction of the Y axis in
the 1 sound emitting portion 2A to the side in the negative direction of the Y axis in the second
sound emitting portion 3A is the same.
[0037]
Next, the electrical configuration of the electrostatic speaker 1 will be described. FIG. 6 is a
diagram showing the configuration of a drive circuit 100A that drives the electrostatic speaker
1A. The drive circuit 100A includes an amplification unit 130, a boosting unit 115, and female
connectors 140A and 140B. The booster unit 115 includes a circuit that adds a positive voltage
to the AC acoustic signal amplified by the amplifier unit 130 and a booster circuit that boosts the
acoustic signal to which the positive voltage is added. The acoustic signal boosted by the booster
115 is supplied to the connector 140A and the first terminal of the connector 140B. In the
present embodiment, the second terminal of the connector 140A and the connector 140B is
connected to the ground GND. The first terminal of the connector 141A is connected to the
electrode 220U, and the first terminal of the connector 141B is connected to the electrode 320U.
The second terminal of the connector 141A is connected to the vibrator 210, and the second
terminal of the connector 141B is connected to the vibrator 310.
04-05-2019
15
[0038]
Next, the operation of the second embodiment will be described. When driving the electrostatic
speaker 1A by the drive circuit 100A, the connector 141A is fitted to the connector 140A and
the connector 141B is fitted to the connector 140B. Thus, the booster unit 115 is connected to
the electrode 220U and the electrode 320U, and the ground GND of the drive circuit 100A is
connected to the vibrating body 210 and the vibrating body 310.
[0039]
Next, when an AC acoustic signal is input to the amplification unit 130, the input acoustic signal
is amplified and supplied to the boosting unit 115. In the booster unit 115, a positive voltage is
added to the supplied acoustic signal. As a result, the acoustic signal becomes a direct current
acoustic signal having the same waveform as the input acoustic signal. The direct-current
acoustic signal is boosted by the booster circuit included in the booster unit 115 and supplied to
the electrode 220U and the electrode 320U.
[0040]
In the present embodiment, when the voltage of the acoustic signal input to the amplification
unit 130 becomes positive, the voltage of the signal output from the boosting unit 115 becomes
larger than when the voltage of the acoustic signal is zero. Here, in the first sound emitting unit
2A, since the vibrating body 210 is connected to the ground GND, the potential difference
between the vibrating body 210 and the electrode 220U is larger than when the voltage of the
acoustic signal is zero. Then, the electrostatic attractive force between the vibrating body 210
and the electrode 220U becomes strong, and the vibrating body 210 is displaced toward the
electrode 220U. Further, in the second sound emitting unit 3A, since the vibrating body 310 is
connected to the ground GND, the potential difference between the vibrating body 310 and the
electrode 320U is larger than when the voltage of the acoustic signal is zero. Then, the
electrostatic attractive force between the vibrating body 310 and the electrode 320U becomes
strong, and the vibrating body 310 is displaced to the electrode 320U side. That is, the vibrating
body 210 and the vibrating body 310 are displaced in the same direction.
[0041]
04-05-2019
16
In the present embodiment, electrostatic attraction also acts between the vibrator 210 and the
electrode 310. Here, the electrostatic force between the vibrating body 210 and the electrode
320U is opposite in direction to the electrostatic attractive force between the vibrating body 210
and the electrode 220U. The electrostatic attractive force is inversely proportional to the square
of the distance from the vibrating body to the electrode, so if the distance from the vibrating
body 210 to the electrode 220U is the same as the distance from the vibrating body 210 to the
electrode 310U, the electrode 220U and the vibrating body The electrostatic attraction between
210 and 210 is offset by the electrostatic attraction between the electrode 320 U and the
vibrator 210. For this reason, in the present embodiment, the length of the insulating member 10
in the Z-axis direction is from the vibrating body 210 so that the distance from the vibrating
body 210 to the electrode 320U is longer than the distance from the vibrating body 210 to the
electrode 220U. It is longer than the distance to the electrode 220U.
[0042]
On the other hand, when the voltage of the acoustic signal input to the amplification unit 130
becomes negative, the voltage of the signal output from the boosting unit 115 becomes smaller
than when the voltage of the acoustic signal is zero. Here, in the first sound emitting unit 2A,
since the vibrating body 210 is connected to the ground GND, the potential difference between
the vibrating body 210 and the electrode 220U is smaller than when the voltage of the acoustic
signal is zero. Then, the electrostatic attraction between the vibrating body 210 and the electrode
220U is weakened, and the vibrating body 210 is displaced to the opposite side to the electrode
220U by the elastic force of the elastic member 230U. Further, in the second sound emitting unit
3A, since the vibrating body 310 is connected to the ground GND, the potential difference
between the vibrating body 310 and the electrode 320U is smaller than when the voltage of the
acoustic signal is zero. Then, the electrostatic attractive force between the vibrating body 310
and the electrode 320U is weakened, and the vibrating body 310 is displaced to the opposite side
to the electrode 320U by the elastic force of the elastic member 330U. That is, the vibrating body
210 and the vibrating body 310 are displaced in the same direction also here.
[0043]
In the region where the vibrating body 210 and the vibrating body 310 do not overlap when the
electrostatic speaker 1A is viewed from the upper surface side (the normal direction of the
vibrating body), only the sound wave generated from the vibrating body 310 is emitted. On the
other hand, in a region where the vibrator 210 and the vibrator 310 overlap when the
04-05-2019
17
electrostatic speaker 1A is viewed from the upper surface side, the sound wave generated from
the vibrator 210 and the sound wave generated from the vibrator 310 are added and radiated Be
done. For this reason, the sound pressure of the sound generated from the area where the
vibrator 210 and the vibrator 310 overlap is higher than the sound pressure of the sound
generated from the area where the vibrator 210 and the vibrator 310 do not overlap.
[0044]
As described above, also in the electrostatic speaker 1A, the electrostatic speaker 1A is viewed
from the upper surface side and is generated from a region where the vibrator 210 and the
vibrator 310 do not overlap (region near the edge in the horizontal direction and the depth
direction) The sound pressure of the sound to be generated is relative to the sound pressure of
the sound generated from the area where the vibrator 210 and the vibrator 310 overlap (the
center area as viewed from the top side) when the electrostatic speaker 1A is viewed from the
top side. Become smaller. For this reason, in the electrostatic speaker 1A, the side lobes become
smaller, and the directivity of the sound generated from the electrostatic speaker 1A is improved
as compared with the conventional electrostatic speaker.
[0045]
Third Embodiment Next, a third embodiment of the present invention will be described. FIG. 7 is
a view showing a plane, a side, and a front of the electrostatic loudspeaker 1B according to the
present embodiment. The electrostatic speaker 1B has a configuration in which a plurality of
electrodes, an elastic member, and a vibrator are stacked. In the following description, members
having the same configurations as those in the above-described embodiment are denoted by the
same reference numerals, and the descriptions thereof will be omitted. Points different from the
above-described embodiment will be described.
[0046]
The vibrating body 410 is different from the vibrating body 210 only in the dimensions in the Xaxis direction and the Y-axis direction, and the other configuration is the same as the vibrating
body 210. The length in the X-axis direction of the vibrating body 410 is shorter than that of the
vibrating body 210, and the length in the Y-axis direction is shorter than that of the vibrating
body 210. The elastic member 430 is different from the elastic member 230 only in the
04-05-2019
18
dimensions in the X-axis direction and the Y-axis direction, and the other configuration is the
same as the elastic member 230. In the present embodiment, the dimensions of the elastic
member 430 in the X-axis direction and the Y-axis direction are the same as those of the
vibrating body 410.
[0047]
In the electrostatic speaker 1B, the elastic member 330U is superimposed on the vibrating body
310, and the electrode 320U is superimposed on the elastic member 330U. Further, not the
insulating member 10 but the elastic member 230L is superimposed on the electrode 320U. The
vibrator 210, the elastic member 230U, and the electrode 220U are sequentially stacked on the
elastic member 230L. The elastic member 430 is stacked on the electrode 220U, and the
vibrating body 410 is stacked on the elastic member 430. The members are aligned and bonded
so that the positions of the intersections of the diagonals of the members overlap when viewed
from the upper surface side. When the respective members are superimposed in this manner, in
the electrostatic speaker 1B, the region where the vibrator 410, the vibrator 210, and the
vibrator 310 overlap when viewed from the upper surface side overlaps the vibrator 210 and the
vibrator 310. It can be an area.
[0048]
Next, the configuration for driving the electrostatic speaker 1B will be described. FIG. 8 is a
diagram showing the configuration of a drive circuit 100B that drives the electrostatic speaker
1B. The electrostatic loudspeaker 1B is connected to a drive circuit 100B including an
amplification unit 130, a transformer 110, bias power supplies 120A and 120B, and a female
connector 142. The bias power supply 120A is a power supply that applies a DC bias voltage to
the center tap of the transformer 110, the positive side is connected to the center tap of the
transformer 110, and the negative side is connected to the ground GND. The ground GND is
connected to the first terminal of the connector 142 via the resistor R1, and is connected to the
fifth terminal of the connector 142 via the resistor R3. The bias power supply 120B is a power
supply that applies a DC bias voltage to the vibrator 210, the negative side is connected to the
ground GND, and the positive side is connected to the third terminal of the connector 142 via the
resistor R2. It is done. Further, one terminal of the secondary coil of the transformer 110 is
connected to the second terminal of the connector 142, and the other terminal of the secondary
coil is connected to the fourth terminal of the connector 142.
04-05-2019
19
[0049]
The first terminal of the male connector 143 is connected to the vibrating body 410 by a cable,
and the second terminal of the connector 143 is connected to the electrode 220U. The third
terminal of the connector 143 is connected to the vibrator 210, the fourth terminal is connected
to the electrode 320 U, and the fifth terminal is connected to the vibrator 310.
[0050]
Next, the operation of the third embodiment will be described. When driving the electrostatic
speaker 1 </ b> B by the drive circuit 100 </ b> B, the connector 143 is fitted to the connector
142. Thereby, one terminal of the secondary side coil of transformer 110 is connected to
electrode 220U, and the other terminal of the secondary side coil of transformer 110 is
connected to electrode 320U. Also, the vibrating body 410 is connected to the ground GND via
the resistor R1, the vibrating body 210 is connected to the bias power supply 120B via the
resistor R2, and the vibrating body 310 is connected to the ground GND via the resistor R3.
Connected Thus, a positive bias voltage is applied as a direct current to the vibrating body 210,
and the potentials of the vibrating body 310 and the vibrating body 410 become equal to the
ground GND.
[0051]
After the female connector and the male connector are connected, when an AC acoustic signal is
input to the amplification unit 130, the input acoustic signal is amplified and supplied to the
primary coil of the transformer 110. Since a positive bias voltage in direct current is applied to
the center tap of the transformer 110, an acoustic signal boosted by the transformer 110 and
output from one terminal of the secondary coil is the other of the secondary coil. The amplitude
is the same as that of the acoustic signal output from the terminal of V and the voltage is
different.
[0052]
When a positive acoustic signal is input to the amplification unit 130, the voltage of the electrode
220U is higher and the voltage of the electrode 320U is lower than when the voltage of the
04-05-2019
20
acoustic signal is 0 V. Since a positive voltage is applied to the vibrating body 210 by the bias
power supply 120B, the electrostatic attracting force with the electrode 220U is weakened while
the electrostatic attracting force with the electrode 320U is strengthened. . Then, the vibrator
210 is displaced toward the electrode 320U (in the negative direction of the Z axis) according to
the difference between the electrostatic attraction acting on the electrode 220U side and the
electrostatic attraction acting on the electrode 320U side. In addition, since the vibrating body
410 is connected to the ground GND, the electrostatic attraction between the vibrating body 410
and the electrode 220U is strengthened, and the vibrating body 410 is displaced to the electrode
220U side (the negative direction of the Z axis). Further, since the vibrating body 310 is
connected to the ground GND, the electrostatic attractive force with the electrode 320U is
weakened, and the vibrator 310 is displaced in the opposite side to the electrode 320U (in the
negative direction of the Z axis). That is, the vibrators 210, 310, and 410 are displaced in the
same direction (the negative direction of the Z axis).
[0053]
Next, when a negative acoustic signal is input to the amplification unit 130, the voltage of the
electrode 220U decreases and the voltage of the electrode 320U increases as compared to the
case where the voltage of the acoustic signal is 0 V. Since a positive voltage is applied to the
vibrating body 210 by the bias power supply 120B, the electrostatic attracting force between the
vibrating body 210 and the electrode 220U is strengthened, while the electrostatic attractive
force between the electrode 320U and the electrode 320U is weakened. . Then, the vibrating
body 210 is displaced to the electrode 220U side (the positive direction of the Z axis) according
to the difference between the electrostatic attractive force acting on the electrode 220U side and
the electrostatic attractive force acting on the electrode 320U side. In addition, since the
vibrating body 410 is connected to the ground GND, the electrostatic attraction between the
vibrating body 410 and the electrode 220U is weakened, and the vibrating body 410 is displaced
to the opposite side (positive direction of the Z axis) to the electrode 220U. Further, since the
vibrating body 310 is connected to the ground GND, the electrostatic attractive force with the
electrode 320U is intensified, and the vibrating body 310 is displaced to the electrode 320U side
(the positive direction of the Z axis). That is, the vibrating bodies 210, 310, and 410 are
displaced in the same direction (the positive direction of the Z axis) here as well.
[0054]
As described above, the vibrators 210, 310, and 410 are displaced in the positive direction of the
Z axis and the negative direction of the Z axis in accordance with the acoustic signal, and the
04-05-2019
21
displacement direction changes sequentially to become vibration, and the vibration state Sound
waves corresponding to (frequency, amplitude, phase) are generated from the vibrators 210,
310, 410. Since the vibrators 210, 310, and 410 are displaced in the same direction, sound
waves of the same phase are generated from each vibrator. The generated sound waves pass
through an elastic member or electrode having sound permeability and are emitted as sound to
the outside of the electrostatic speaker 1B.
[0055]
In the region where the vibrator 210 and the vibrator 410 do not overlap the vibrator 310 when
the electrostatic speaker 1B is viewed from the upper surface side (the normal direction of the
vibrator), only the sound wave generated from the vibrator 310 is radiated Be done. Further, in a
region where the vibrators 210 and 310 overlap when the electrostatic speaker 1B is viewed
from the top side and the vibrators 410 do not overlap, the sound waves generated from the
vibrator 210 and the sound waves generated from the vibrator 310 are It is added and emitted.
For this reason, the sound pressure of the sound generated from this area is higher than the
sound pressure of the sound generated outside this area. Further, in a region where the vibrators
210, 310 and 410 overlap when the electrostatic speaker 1B is viewed from the upper surface
side, the sound waves generated from the vibrator 210, the sound waves generated from the
vibrator 310 and the vibrator 410 generated. The sound waves are summed and emitted. For this
reason, the sound pressure of the sound generated from this area is higher than the sound
pressure of the sound generated outside this area.
[0056]
As described above, in the electrostatic speaker 1B, the electrostatic speaker 1B is viewed from
the upper surface side and is generated from a region (region near the edge in the horizontal
direction and the depth direction) in which the other vibrator does not overlap the vibrator 310
The sound pressure of the sound to be generated is relative to the sound pressure of the sound
generated from the area where the other vibration body overlaps the vibration body 310 when
the electrostatic speaker 1B is viewed from the top side (the center area when viewed from the
top side) Become smaller. For this reason, the sound generated from the electrostatic speaker 1B
has a small side lobe, and the directivity thereof is improved as compared with the conventional
electrostatic speaker. Although the electrostatic loudspeaker 1 </ b> B according to the present
embodiment includes the vibrating body 410 and the elastic member 430, the vibrating body
410 and the elastic member 430 may not be provided.
04-05-2019
22
[0057]
[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.
[0058]
(Modification 1) Although the distance a1 and the distance a2 are the same in the embodiment
described above, the distances a1 and a2 may be different. Moreover, although the distance b1
and the distance b2 are the same in the above-described embodiment, the distances b1 and b2
may be different. In short, each distance is not limited to a configuration that completely
matches, and each distance may be different depending on the variation of the dimensions of the
vibrating body, the accuracy at the time of assembly, etc. as long as the side lobe can be
suppressed. Further, in the embodiment described above, the dimensions may be described to be
the same for a plurality of parts, but “same” is not limited to perfect matching, and variations
in dimensions at the time of manufacture are “same” It becomes a range.
[0059]
(Modification 2) In the first embodiment described above, two sound emitting units are stacked,
but the number of sound emitting units to be stacked is not limited to two. For example, as
shown in FIG. 9, the insulating member 11 is stacked on the first sound emitting unit 2, and the
vibrating body 410 having an area smaller than the vibrating member 21 of the first sound
emitting unit 2 is further provided on the insulating member 11. The third sound emitting unit 4
may be overlapped.
[0060]
The insulating member 11 has only short dimensions in the lateral direction and the depth
direction as compared to the insulating member 10, and the other configuration is the same as
04-05-2019
23
that of the insulating member 10. The third sound emitting unit 4 has a rectangular shape when
viewed from the upper surface side, and the shape when viewed from the upper surface side is
similar to the first sound emitting unit 2. The third sound emitting unit 4 includes a vibrating
body 410, electrodes 420U and 420L, and elastic members 430U and 430L. The configurations
of the electrode 420U and the electrode 420L are the same, and the configurations of the elastic
member 430U and the elastic member 430L are the same. The dimensions of the respective
members in the drawing are different from the actual dimensions so that the shapes and
positional relationships of the respective members can be easily understood.
[0061]
The vibrating body 410 is different from the vibrating body 210 only in the dimensions in the Xaxis direction and the Y-axis direction, and the other configuration is the same as the vibrating
body 210. The dimensions of the vibrating body 410 in the X-axis direction and the Y-axis
direction are shorter than that of the vibrating body 210. The electrodes 420U and 420L also
differ from the electrode 220 only in the dimensions in the X-axis direction and the Y-axis
direction, and the other configurations are the same as the electrode 220. In the present
embodiment, the dimensions in the X-axis direction and the Y-axis direction of the electrode 420
are the same as those of the vibrating body 410. The elastic members 430U and 430L also differ
from the elastic member 230 only in the dimensions in the X-axis direction and the Y-axis
direction, and the other configurations are the same as the elastic member 230. In the present
embodiment, the dimensions of the elastic member 430 in the X-axis direction and the Y-axis
direction are the same as those of the vibrating body 410.
[0062]
Also in the third sound emitting unit 4, an adhesive is applied to each member with a width of
several mm from the edge, and from the bottom, the electrode 420L, the elastic member 430L,
the vibrator 410, the elastic member 430U, and the electrode 420U are stacked in this order And
glued together. In the electrode 420U, the side with the conductive film is in contact with the
elastic member 430U, the side with the conductive film is in contact with the elastic member
430L, and the conductive film of the electrode 420 and the vibrating body 410 sandwich the
elastic member 430. Are facing each other. Further, the third sound emitting unit 4 is aligned so
that the position of the intersection of the diagonals overlaps the position of the intersection of
the diagonals of the first sound emitting unit 2 when viewed from the upper surface side.
04-05-2019
24
[0063]
The electrode 420U is connected to the terminal connected to the first terminal of the connector
140A and the connector 140B in the secondary coil of the transformer 110 of the drive circuit
100 of the first embodiment, and the electrode 420L is connected to the second terminal of the
transformer 110. It is connected to the terminal connected to the 3rd terminal of connector
140A and connector 140B in the following coil. The vibrating body 410 is also connected to the
resistor R1 of the drive circuit 100.
[0064]
According to this configuration, the vibrating body 410 vibrates in the same direction as the
vibrating body 210 and the vibrating body 310 according to the acoustic signal input to the
amplification unit 130. Then, the sound pressure of the sound emitted from the edge of the
electrostatic speaker 1C seen from the upper surface side is lower than the sound pressure of the
sound emitted from the region where the vibrators 210, 310 and 410 overlap at the center.
Become. For this reason, in the electrostatic speaker 1C, the side lobes become small, and the
directivity of the sound generated from the electrostatic speaker 1C is improved as compared
with the conventional electrostatic speaker.
[0065]
In the configuration in which three sound emitting units are overlapped, the second sound
emitting unit 3 may be overlapped, and the first sound emitting unit 2 or the third sound
emitting unit 4 may be overlapped thereon. . In addition, the first sound emitting unit 2 is
stacked on the second sound emitting unit 3, and the first sound emitting unit 2 is further
stacked thereon, or the third sound emitting unit 4 on the second sound emitting unit 3. And the
third sound emitting unit 4 may be further superimposed thereon.
[0066]
(Modification 3) In the modification 2 described above, although the third sound emitting unit 4
is superimposed on the first sound emitting unit 2, the arrangement of the third sound emitting
unit 4 is limited to this arrangement is not. FIG. 10 is a view showing another configuration in
04-05-2019
25
the case where the first sound emitting unit 2, the second sound emitting unit 3 and the third
sound emitting unit 4 are overlapped. As shown in FIG. 10, the sound emitting units may be
overlapped in the order of the third sound emitting unit 4, the second sound emitting unit 3, and
the first sound emitting unit 2 from the bottom.
[0067]
(Modification 4) In the embodiment described above, when a plurality of vibrators are arranged
in the vertical direction, the vibrators having a large area are viewed in the X-axis direction and
the Y-axis direction as viewed from the upper surface side with respect to the vibrator having a
narrow area. Although there is a region that does not overlap in both, it is not limited to this
configuration. For example, in the case of overlapping two sound emitting units, the
configuration shown in FIG. 11 may be used. The electrostatic loudspeaker 1E shown in FIG. 11
has line symmetry when viewed from the upper surface side, and includes a first sound emitting
portion 2E, an insulating member 10E, and a second sound emitting portion 3E. The first sound
emitting unit 2E is the same as the first sound emitting unit 2 except for the dimension in the Xaxis direction, and the second sound emitting unit 3E is the same as the second sound emitting
unit 3. The insulating member 10E is the same as the insulating member 10 except for the
dimension in the X-axis direction. As shown in FIG. 11, the lengths of the first sound emitting unit
2E and the second sound emitting unit 3E in the X-axis direction (second direction) are the same,
and the Y-axis direction of the first sound emitting unit 2E (first The length of the direction) may
be shorter than the length of the second sound emitting portion 3E in the Y-axis direction. In this
configuration, when viewed from the upper surface side, the vibrating body of the first sound
emitting unit 2E has a smaller area than the vibrating body of the second sound emitting unit 3E.
Therefore, when viewed from the upper surface side, the vibrating body of the first sound
emitting portion 2E has a region not overlapping with the vibrating body of the second sound
emitting portion 3E in the Y axis direction, and there is no region not overlapping in the X axis
direction It becomes. According to this configuration, the sound pressure of the sound emitted
from near both ends in the Y-axis direction as viewed from the upper surface side is the vibration
of the first sound emitting portion 2E and the second sound emitting portion 3E as viewed from
the upper surface side. It becomes smaller than the area where vibrators overlap. For this reason,
the side lobes become smaller, and the directivity of the sound generated from the electrostatic
speaker 1E is improved as compared with the conventional electrostatic speaker.
[0068]
(Modification 5) In the embodiment described above, each member is rectangular when viewed
04-05-2019
26
from the upper surface side, but the shape of each member when viewed from the upper surface
side is not limited to the rectangle. For example, in the case of overlapping two sound emitting
units, the configuration shown in FIG. 12 may be used. The electrostatic loudspeaker 1F shown in
FIG. 12 is configured of a first sound emitting unit 2F, an insulating member 10F, and a second
sound emitting unit 3F. The shape of each member is circular when viewed from the upper
surface side of the first sound emitting portion 2F, and the configuration other than this shape is
the same as that of the first sound emitting portion 2. The shape of each member is also circular
when viewed from the upper surface side of the second sound emitting unit 3F, and the
configuration other than this shape is the same as that of the second sound emitting unit 3.
Further, the insulating member 10F also has an annular shape when viewed from the upper
surface side, and the configuration other than this shape is the same as that of the insulating
member 10. The first sound emitting portion 2F, the insulating member 10F, and the second
sound emitting portion 3F are overlapped such that the centers thereof overlap with each other
when viewed from the upper surface side. In the electrostatic speaker 1F, since the area of the
vibrating body of the second sound emitting unit 3F is larger than the area of the first sound
emitting unit 2F, the vibrating body of the second sound emitting unit 3F at the edge side There
is a region where the vibrators of the first sound emitting unit 2F do not overlap. In this region,
the sound pressure is lower than that of the central portion as viewed from the upper surface
side. For this reason, in the present modification, the side lobe is reduced, and the directivity of
the sound generated from the electrostatic speaker 1F is improved as compared with the
conventional electrostatic speaker.
[0069]
In addition, although the shape of each member of the sound emission part is circular seen from
the upper surface side in FIG. 12, the shape of each member which comprises a sound emission
part may be a polygon other than an ellipse or a rectangle. . Further, when the electrostatic
speaker 1 has a plurality of vibrators, the shapes of the vibrators are not limited to similar ones,
and the shapes may be different.
[0070]
(Modification 6) In the embodiment and the modification described above, although the elastic
member is disposed between the vibrator and the electrode, the configuration for providing a
space between the electrode and the vibrator uses the elastic member. It is not limited to the
configuration. For example, not the elastic member 230 but the insulating member 10 may be
disposed between the vibrating body 210 and the electrode 220U, and between the vibrating
04-05-2019
27
body 210 and the electrode 220L, and the vibrating body 210 may be sandwiched between two
insulating members. Good. Also in this configuration, the vibrating body 210 is disposed at a
distance from the electrode 220, and vibrates in accordance with the potential difference with
the electrode. In this configuration, it is preferable that the front surface and the back surface of
the vibrator be coated with an insulating material such as a synthetic resin.
[0071]
(Modification 7) In the embodiment and modification which were mentioned above, although the
area of the electrode and elastic member seen from the upper surface side differed by the 1st
sound emission part and the 2nd sound emission part, the 1st sound emission part In the second
sound emitting portion, the areas of the electrode and the elastic member may be the same.
[0072]
(Modification 8) In the modification described above, three vibrators are arranged at intervals in
the direction of the Z axis, but the number of vibrators arranged at intervals in the direction of
the Z axis is The number is not limited to three or less, and may be four or more.
[0073]
(Modification 9) In the modification described above, the configuration is described in which the
region where the vibrators do not overlap only in the Y-axis direction when viewed from the
upper surface side is provided, but in this configuration, three sound emitting portions are
overlapped. May be
FIG. 13 is a view showing a plane, a side, and a front of an electrostatic loudspeaker 1G according
to this modification.
The electrostatic speaker 1G includes a first sound emitting unit 2G, an insulating member 10G,
and a second sound emitting unit 3G. The first sound emitting unit 2G has the same
configuration as the second sound emitting unit 3, and the dimension in the X-axis direction and
the dimension in the Y-axis direction are also the same as the second sound emitting unit 3. The
second sound emitting unit 3G also has the same configuration as the second sound emitting unit
3, and the dimension in the X-axis direction and the dimension in the Y-axis direction are also the
same as the second sound emitting unit 3. That is, the first sound emitting unit 2G and the
second sound emitting unit 3G have the same configuration, and the shape and the area are the
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same when viewed from the upper surface side. The insulating member 10G is different from the
insulating member 10 in the dimension in the X-axis direction and the dimension in the Y-axis
direction.
[0074]
As shown in FIG. 13, the first sound emitting unit 2G and the second sound emitting unit 3G are
overlapped without being shifted in the X axis direction when viewed from the upper surface
side, but are shifted in the Y axis direction. It is piled up. In this configuration, the vibrating body
of the first sound emitting unit 2G and the vibrating body of the second sound emitting unit 3G
have regions which do not overlap each other on the positive direction side and the negative
direction side of the Y axis when viewed from the upper surface side. In this region, the sound
pressure of the emitted sound is smaller than the region where the two vibrators overlap, so the
side lobes become smaller, and the directivity of the sound generated from the electrostatic
speaker 1 G is This is an improvement over electrostatic speakers. In FIG. 13, two sound emitting
units are overlapped, but the number of sound emitting units to be overlapped is not limited to
two, and three sound emitting units having the same configuration in the Y-axis direction (
Alternatively, they may be overlapped in the X axis direction). Further, in the configuration in
which sound emitting portions having the same area are overlapped, the shape of the sound
emitting portions viewed from the upper surface side may be rectangular, and may be
overlapped so as to intersect each other when viewed from the upper surface side. In this
configuration, if a plurality of sound emitting portions are overlapped in a form orthogonal or
nearly orthogonal, as viewed from the upper surface side, the end in the positive direction and
the negative direction in the X-axis direction and the positive direction in the Y-axis direction And
at the end in the negative direction, there is a region where the vibrators of the sound emitting
parts do not overlap each other, and the side lobes become smaller.
[0075]
(Modification 10) In the above description, the electrode facing the vibrator is flexible, but the
electrode may be a metal such as punching metal which does not have flexibility.
[0076]
(Modification 11) In the above-described embodiment, the configuration in which the electrodes,
the vibrator and the elastic member are stacked is used as a sound output unit (speaker) that
converts an acoustic signal into a sound. It is also possible to use an electrostatic microphone
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(electrostatic electroacoustic transducer) that converts into
FIG. 14 is a diagram showing a configuration of an electrostatic microphone 5 according to the
present modification and an acoustic signal generation circuit 100C that generates an acoustic
signal representing a sound collected by the electrostatic microphone 5. In the present
modification, the electrostatic microphone 5 includes the same members as the electrostatic
speaker 1 described above. Therefore, the members constituting the electrostatic microphone 5
include the members of the electrostatic speaker 1 and the like. The same reference numerals are
given and the description thereof is omitted. Further, the configuration of the acoustic signal
generation circuit 100C 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. Therefore, the components
included in the acoustic signal generation circuit 100C include the components included in the
drive circuit 100. The same reference numerals are given and the description of each part is
omitted. The transformation ratio of the transformer 110 and the resistance value of each
resistor are appropriately adjusted.
[0077]
In the electrostatic microphone 5, the electrode 220 (electrode 320) as a conductor and the
vibrating body 210 (vibrating body 310) as a conductor are disposed opposite to each other at a
distance, and the electrode 220 (320) and the vibrating body 210 (310) functions as a capacitor
constituted by parallel flat conductors. Since a bias voltage is applied to each vibrating body,
when no sound has reached the electrostatic microphone 5, a constant charge is accumulated in
this capacitor. When the sound reaches the electrostatic microphone 5, each vibrator vibrates by
the sound reached. When each vibrating body vibrates, the distance between the vibrating body
210 (310) and the electrodes 220U (320U) and 220L (320L) changes, so that the capacitance
between the vibrating body and the electrode changes.
[0078]
For example, when the vibrating body 210 (310) is displaced toward the electrode 220U (320U),
the distance between the electrode 220U (320U) and the vibrating body 210 (310) becomes
short, and the electrode 220U (320U) and the vibrating body 210 (310U) The capacitance
between them and 310) increases. Further, the distance between the electrode 220L (320L) and
the vibrating body 210 (310) is increased, and the capacitance between the electrode 220L
(320L) and the vibrating body 210 (310) is decreased. Thus, when the capacitance changes, the
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potential of the electrode 220U (320U) changes so that the potential difference between the
electrode 220U (320U) and the vibrating body 210 (310) decreases, and the electrode 220L
(320L) and the vibrating body 210 change. The potential of the electrode 220L (320L) changes
so as to increase the potential difference with (310). Here, since a potential difference occurs
between the electrode 220U (320U) and the electrode 220L (320L), current flows in the
secondary coil of the transformer 110.
[0079]
In addition, when the vibrating body 210 (310) is displaced toward the electrode 220L (320L),
the distance between the electrode 220L (320L) and the vibrating body 210 (310) becomes
short, and the electrode 220L (320L) and the vibrating body 210 (310L) The capacitance
between them and 310) increases. Further, the distance between the electrode 220U (320U) and
the vibrating body 210 (310) is increased, and the capacitance between the electrode 220U
(320U) and the vibrating body 210 (310) is decreased. Then, the potential of the electrode 220L
(320L) changes so that the potential difference between the electrode 220L (320L) and the
vibrating body 210 (310) decreases, and the potential difference between the electrode 220U
(320U) and the vibrating body 210 (310) increases. Thus, the potential of the electrode 220U
(320U) changes. Here, a potential difference occurs between the electrode 220U (320U) and the
electrode 220L (320L), and the vibrator 210 (310) is displaced in the direction of the electrode
220U (320U) in the secondary coil of the transformer 110 A current flows in the opposite
direction to the time.
[0080]
When current flows in the secondary coil of the transformer 110, current also flows in the
primary coil of the transformer 110 in response to this current. The signal that has flowed to the
primary side 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 electrostatic
microphone 5. That is, the portion that is the first sound emitting unit 2 in the electrostatic
speaker 1 and the portion that is the second sound emitting unit 3 in the electrostatic speaker 1
function as a sound collection unit that collects sound. Do.
[0081]
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In the present modification, when the impedance of the transformer 110 is low, the frequency
characteristics at a low frequency may be degraded due to the influence of the load capacity of
the electrostatic microphone 5. In this case, in place of the transformer 110, an amplifier with
high impedance may be connected to the electrodes 220U (320U) and 220L (320L) to suppress
a decrease in frequency characteristics. Further, even in the configurations of FIG. 6 and FIG. 8,
the signal obtained from the electrostatic microphone 5 can be output as an acoustic signal by
changing the flow direction of the signal as in the above-described modified example.
[0082]
1, 1A to 1F: electrostatic speaker, 2, 2A, 2E, 2F: first sound emitting portion, 3, 3A, 3E, 3F: second
sound emitting portion, 4: third sound emitting portion, 5: static Electric microphone, 10, 10E,
10F ... insulation member, 11 ... insulation member, 100, 100A, 100B ... drive circuit, 100C ...
acoustic signal generation circuit, 110 ... transformer, 115 ... boost unit, 120, 120A, 120B ... Bias
power supply, 140 A, 140 B, 141 A, 141 B: connector, 210: vibrator, 220, 220 U, 220 L:
electrode, 230, 230 U, 230 L: elastic member, 310: vibrator, 320, 320 U, 320 L: electrode, 330,
330 U, 330 L: elastic member, 410: vibrator, 420, 420 U, 420 L: electrode, 430, 430 U, 430 L:
elastic member, R1, R2, R3 ... Vessel
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