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JP2013098838

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DESCRIPTION JP2013098838
Abstract: To provide an electroacoustic transducer that achieves desired directivity without
performing complicated processing on a vibrator or an electrode. SOLUTION: An electrostatic
speaker 1 (electro-acoustic transducer) is disposed in a sheet-like shape, which is disposed apart
from fixed electrodes 10, 50 and fixed electrodes 10, 50, and is displaced according to a
potential difference between fixed electrodes 10, 50. The vibration member 30 is deformed into
any one of a plurality of shape patterns predetermined by energization, and elastic members 20
and 40 having air permeability provided between the vibration member 30 and the fixed
electrodes 10 and 50. , And shape memory members 60A to 60H which maintain the shape after
deformation. When the shape memory members 60A to 60H are deformed, the electrostatic
speaker 1 is deformed into one of a plurality of shapes different in the shape of the serpentine
along with the deformation of the shape memory members 60A to 60H. [Selected figure] Figure
1
Electro-acoustic transducer
[0001]
The present invention relates to an 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.
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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, the amplitude decreases and the sound pressure decreases in the region where the
surface density is large in the vibrating film, 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 of the region near the outer edge is
increased in the electrostatic speaker, the sound pressure in the region near the outer edge is
reduced, so that the side lobe is suppressed.
[0003]
In addition, a speaker using an accordion pleated vibrating film has been proposed for an
electrostatic speaker. For example, in Patent Document 3, a vibrating membrane is a membrane
bent in an accordion pleated shape, and a fixed electrode is a plurality of planar electrodes
disposed so as to enter the fold from the front surface and the rear surface of the vibrating
membrane. Electrostatic speakers have been proposed that perform frequency band and high
efficiency reproduction. Further, Patent Document 4 proposes an electrostatic speaker that
improves the directivity of a high range by using an accordion curtain-like diaphragm.
[0004]
JP-A-2007-274363 JP-A-2007-274362 JP-A-56-100600 JP-A-52-069610
[0005]
By the way, in the invention of Patent Document 1, it is necessary to increase the surface density
of the vibrating film closer to the outer edge, but since the thickness of the vibrating film is very
thin, the surface density in a plurality of regions in one vibrating film is It is difficult to configure
a vibrating body differently.
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In addition, although it is conceivable to use a plurality of diaphragms different in surface density
instead of one diaphragm, this configuration requires a wiring for supplying a bias voltage for
each diaphragm. In addition, although it is possible to use the configuration of this electrostatic
speaker as the configuration of a microphone, in this case, sound (sound) is an acoustic signal
(sound wave) by the sound wave of the sound generated outside vibrating the diaphragm. Will be
converted to electrical signals. Therefore, in order to control the directional characteristics of the
microphone, it is necessary to increase the surface density of the vibrating film closer to the
outer edge as in the case of the electrostatic speaker, and as in the electrostatic speaker
described above, it is complicated Processing is required.
[0006]
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. In addition, although it
is conceivable to use a plurality of electrodes instead of one electrode, and a method of making
the distance between each electrode and the vibrating film different, this configuration requires a
wiring for supplying a signal to each electrode. In addition, although it is possible to use the
configuration of this electrostatic speaker as the configuration of a microphone, also in this case,
complicated processing is required for the vibrator and the electrode as in the case of the
electrostatic speaker.
[0007]
Further, in the technology described in Patent Document 3, although reproduction in a wide
frequency band and high efficiency can be performed, directivity control such as suppression of
side lobes can not be performed. Moreover, although the technique described in Patent
Document 4 can improve the directivity of the high sound range, the directivity can not be
controlled to suppress the side lobes. In addition, although it is possible to use the configuration
of these electrostatic speakers as the configuration of the microphone, also in this case, the
sound from the front direction is efficiently collected and the sound from the outer edge
direction is not collected so much. It was not possible to control the directivity. 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 realizing desired directivity without performing
complicated processing on a vibrator or an electrode in an electroacoustic transducer. .
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[0008]
In order to solve the problems described above, according to the present invention, an electrode,
a sheet-like vibrating body disposed so as to face the electrode and separated according to a
potential difference with the electrode, a vibrating body, and the electrode And an air-permeable
elastic member provided between them, and in a state in which the electrode, the vibrator and
the elastic member are stacked, peaks and valleys alternate in a region of a part or all of the
vibrator. An electro-acoustic transducer is provided, which has a repeating zigzag shape and
different shapes in a plurality of different regions of the vibrator in a stacked state.
[0009]
In a preferred aspect of the present invention, the shape of the zigzag may be continuously
changed in a region of a part or all of the vibrator, and the vibrator and the elastic member.
[0010]
Further, in a further preferable aspect of the present invention, in the electrode, the vibrator and
the elastic member, even if the length between adjacent peaks and valleys in the serpentine
shape is shortened on the outer edge side of the vibrator. Good.
Further, in another preferable aspect of the present invention, in the electrode, the vibrator, and
the elastic member, at least one of an interval between adjacent peaks or an interval between
adjacent valleys in the serpentine shape is It may be wider at the outer edge side of the vibrator.
[0011]
Further, according to the present invention, there is provided an air vent provided between a
vibrating member in the form of a sheet, which is disposed to face the electrode and is spaced
apart from the electrode and displaced according to a potential difference with the electrode, And
an elastic member having elasticity, and in the laminated state, the electrode, the vibrator and the
elastic member are alternately in a zigzag shape in which peaks and valleys are alternately
repeated in a region of a part or the whole of the vibrator. There is provided an electro-acoustic
transducer characterized in that at least one of an envelope connecting the serpentine peaks and
an envelope connecting the valleys has a curved shape.
[0012]
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Further, in a further preferable aspect of the present invention, the electrode, the vibrator and
the elastic member may have a zigzag shape in a partial region of the vibrator, and may have a
planar shape in another region. .
[0013]
In a preferred aspect of the present invention, a shape which is fixed to at least one of the
electrode and the elastic member, and is continuously transformed into a plurality of the
serpentine shape patterns by continuously performing energization or heating, and maintaining a
shape after deformation A memory member may be provided, and part or all of the electrode, the
vibrator and the elastic member may be deformed into the zigzag shape along with the
deformation of the shape memory member.
[0014]
According to the present invention, in the electroacoustic transducer, desired directivity can be
realized without performing complicated processing on the vibrator and the electrode.
[0015]
FIG. 1 is a schematic view of an electrostatic loudspeaker 1 according to an embodiment of the
present invention.
FIG. 1 is a cross-sectional view and an electrical configuration of an electrostatic speaker 1.
It is a figure which shows the shape of the electrostatic type speaker 1 roughly.
It is a figure which shows the shape of the electrostatic type speaker 1 roughly.
It is a figure which shows the shape of the electrostatic type speaker 1 roughly.
FIG. 6 is a connection diagram showing a connection between shape memory members 60A to
60H and a power supply 80. It is a figure which shows the shape of the electrostatic type speaker
1 roughly. It is a figure which shows the shape of the electrostatic type speaker 1 roughly. It is a
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figure which shows the shape of the electrostatic type speaker 1 roughly. It is a figure which
shows the shape of the electrostatic type speaker 1 roughly. It is a figure which shows the shape
of the electrostatic type speaker 1 roughly. It is a figure which shows the shape of the
electrostatic type speaker 1 roughly. It is a figure which shows the shape of the electrostatic type
speaker 1 roughly. It is a figure which shows the shape of the electrostatic type speaker 1
roughly. FIG. 2 is a cross-sectional view of the microphone 2 and a diagram schematically
showing an electrical configuration.
[0016]
Hereinafter, an embodiment of the present invention will be described with reference to the
drawings. In this embodiment, an example in which the electroacoustic transducer is applied as
an electrostatic speaker that converts an acoustic signal (electric signal) into a sound wave
(sound) will be described. In the following description, sound and sound wave are used
synonymously. FIG. 1 is a view schematically showing the appearance of an electrostatic speaker
1 according to an embodiment of the present invention, and FIG. 2 is a view schematically
showing a cross section and an electrical configuration of the electrostatic speaker 1. It is. The
electrostatic speaker 1 according to the present embodiment has a flexible structure in which the
plane is rectangular and thin. The X, Y, and Z axes in these figures respectively indicate the
longitudinal direction, the width direction, and the thickness direction of the electrostatic speaker
1. Moreover, the symbol in which "*" was described in "(circle)" in FIG. 2 has shown going to the
front from the back of a drawing. The electrostatic loudspeaker 1 shown in FIGS. 1 and 2 is a socalled push-pull electrostatic loudspeaker having a rectangular flat fixed electrode 10 and a fixed
electrode 50 provided substantially in parallel at a predetermined distance. The electrostatic
speaker 1 has a vibrating body 30 sandwiched between the fixed electrode 10 and the fixed
electrode 50. Between the fixed electrode 10 and the vibrating body 30 and between the fixed
electrode 50 and the vibrating body 30, rectangular flat elastic members 20 and 40 having
elasticity and air permeability are provided, respectively. 30 is movable to the fixed electrode 10
side and the fixed electrode 50 side. The dimensions of the components such as the vibrator 30
and the fixed electrodes 10 and 50 in the drawing are different from the actual dimensions so
that the shapes of the components can be easily understood.
[0017]
(Configuration of Electrostatic Loudspeaker 1) First, each part of the electrostatic loudspeaker 1
will be described. The fixed electrode 10 and the fixed electrode 50 are made of non-woven
fabric in which a conductive material such as metal is deposited by sputtering. By making the
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non-woven fabric in this way, sound waves can pass through the gaps of the fibers of the nonwoven fabric. The fixed electrode 10 and the fixed electrode 50 may be formed of a non-woven
fabric coated with a conductive dye. In addition, the fixed electrode 10 and the fixed electrode 50
may be formed of a warp having a conductivity and a conductive cloth formed by weaving a weft
having a conductivity as well. In short, the fixed electrode 10 and the fixed electrode 50 may be
made of materials having both conductivity, sound wave transmission (air permeability) and
flexibility. Since the fixed electrode 10 and the fixed electrode 50 are made of flexible members
that can be bent, they can be deformed into any shape, for example, a serpentine shape.
[0018]
The vibrating body 30 is a thin foil-like rectangular electrode. The vibrating body 30 is formed
by depositing a conductive material such as metal on a film (thin film or sheet) using a polymer
material such as PET (polyethylene terephthalate, polyethylene terephthalate), PP
(polypropylene, polypropylene) or polyester. It is formed. Vibrator 30 may be formed of a
material obtained by applying a conductive dye to a film. As described above, in the present
embodiment, since the vibrating body 30 is also made of a flexible member that can be bent, it
can be deformed into an arbitrary shape, for example, a zigzag shape.
[0019]
The elastic members 20 and 40 are made of a soft and air-permeable member, and may be, for
example, a material obtained by compressing heat with a batt, and a synthetic resin in the form
of a sponge or a non-woven cloth. It may be. Other members may be used as long as they are
flexible and have insulation and sound transmission. In this embodiment, although the thing
which has air permeability as an elastic member is used, an elastic member may not have air
permeability and should just have insulation and sound permeability. Since the elastic members
20 and 40 are formed of flexible members that can be bent, they can be deformed into any
shape, for example, a serpentine shape. In the present embodiment, the lengths of the elastic
members 20 and 40 in the X and Y directions are longer than the lengths of the fixed electrode
10 in the X and Y directions, and the X and Y directions of the vibrating body 30 It is longer than
the length of Further, the thicknesses (the heights in the Z direction) of the elastic member 20
and the elastic member 40 are the same.
[0020]
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7
The shape memory members 60A to 60H are members in which the surface of a linear shape
memory alloy having a circular cross section is coated with a synthetic resin having insulation
properties and heat resistance. The shape memory members 60A to 60H are disposed by
adhering to the fixed electrode 10 with an adhesive, an adhesive tape, or the like. In this case, the
shape memory members 60A, 60C, 60E, and 60G are disposed adjacent to each other, and are
provided along one end of the fixed electrode 10 in the width direction. The shape memory
members 60B, 60D, 60E, 60G are disposed adjacent to each other, and are provided along the
other end of the fixed electrode 10 in the width direction. For example, when the fixed electrode
10 is a non-woven fabric or a conductive cloth, the shape memory members 60A to 60H may be
attached by sewing to the fixed electrode. The point is that the shape memory members 60A to
60H may be fixed to the fixed electrode 10, and the shape of the fixed electrode 10 may be
deformed in conjunction with the change of the shape of the shape memory members 60A to
60H. The shape memory alloy of the shape memory members 60A to 60H is, for example, a
shape memory alloy disclosed in Japanese Patent Application Laid-Open No. 2002-20848.
[0021]
When current flows, the shape memory members 60A to 60H increase in temperature due to
Joule heat, shrink hard and deform into a memorized shape. On the other hand, when the
energization of the shape memory members 60A to 60H is stopped, the temperature decreases,
and the shape memory members 60A to 60H become soft and can be easily deformed. The shape
memory members 60A and 60B in this embodiment store linear shapes. On the other hand, the
shape memory members 60C and 60D, as shown in FIG. 3, have a so-called serpentine shape in
which peaks and valleys are alternately repeated, and the depth of the fold (the length d1
between adjacent peaks and valleys in the serpentine Stores a shape (hereinafter, referred to as a
“tangled shape A1”) that becomes shallower toward the outer edge side of the vibrating body
30. As illustrated, in the serpentine shape A1, the depth of the folds decreases continuously and
continuously from the inside to the outer edge side of the vibrating body 30, and an envelope
connecting a plurality of peaks formed on the fixed electrode 10 side The line S11 is a straight
line, while the envelope S12 connecting a plurality of valleys formed on the fixed electrode 50
side has a convex shape in which a substantially central portion of the vibrating body 30 is
expanded.
[0022]
The shape memory members 60E and 60F, as shown in FIG. 4, have a zigzag shape in which
04-05-2019
8
peaks and valleys are alternately repeated, and an envelope S21 connecting a plurality of peaks
and an envelope S22 connecting a plurality of valleys are fixed electrodes 10. A shape
(hereinafter, referred to as “serpent shape A2”) having an arc shape in which the center of the
circle is positioned on the side is stored. In the serpentine shape A2, as shown in the drawing, the
depth of the serpentine folds is uniform throughout. In addition, an envelope shape is not limited
to the meaning of a circular arc shape, for example, the shape which forms a part of ellipse may
be sufficient. In short, the envelope may be a curve convex to only one side.
[0023]
The shape memory members 60G and 60H have a zigzag shape in which peaks and valleys are
alternately repeated as shown in FIG. 5, and an envelope S31 connecting the peaks and an
envelope S32 connecting the valleys are circular on the fixed electrode 50 side. A shape
(hereinafter referred to as a “serpently-folded shape A3”) having an arc shape in which the
center is located is stored. In the serpentine shape A3, as shown, the serpentine folds have a
uniform depth throughout. The envelopes S31 and S32 are also the same as those in FIG. 4
described above, and the envelope is not limited to the arc shape, and may be, for example, a
shape forming a part of an ellipse. In short, the envelope may be a curve convex to only one side.
[0024]
FIG. 6 is a connection diagram showing a connection between shape memory members 60A to
60H and a power supply 80. As shown in FIG. As shown in FIG. 6, one end of each of the shape
memory members 60A, 60C, 60E, 60G is connected to the positive terminal of the power supply
80 through the switches 81A, 81B, 81C, 81D. The other ends of shape memory members 60A,
60C, 60E and 60G are connected to one ends of shape memory members 60B, 60D, 60F and
60H respectively, and the other ends of shape memory members 60B, 60D, 60F and 60H are
power supplies It is connected to the negative terminal of 80. The broken line shown in FIG. 6
shows the outer edge of the fixed electrode 10 when the electrostatic speaker 1 is placed on a
flat and horizontal surface, and is arranged inside the outer edge of the lead L used for the abovementioned connection. The surface is covered with a synthetic resin having insulating properties
and heat resistance, and is formed of a flexible material to such an extent that the flexibility of
the electrostatic speaker 1 is not impaired. These lead wires are also fixed to the fixed electrode
10 by an adhesive, an adhesive tape or the like as in the shape memory members 60A to 60H.
When the fixed electrode 10 is a non-woven fabric or a conductive cloth, the lead may be
attached to the fixed electrode 10 by sewing. Further, the ends of the leads L connected to the
switches 81A, 81B, 81C, 81D are arranged in a harness shape on the fixed electrode 10 and are
04-05-2019
9
connected to the terminals of the connector CN, via the connector CN. The switches 81A, 81B,
81C, 81D and the power supply 80 are connected.
[0025]
As shown in FIG. 2, the electrostatic speaker 1 includes a transformer 70, an input unit 71 to
which an acoustic signal is input from the outside, and a bias power supply 72 which applies a
DC bias to the vibrator 30. The bias power supply 72 is connected to the vibrating body 30 and
the middle point on the output side of the transformer 70, and the two fixed electrodes 10 and
50 are connected to one end and the other end of the output side of the transformer 70,
respectively. . The operation unit 83 is an operation unit that includes an operation element such
as a button and outputs a signal according to the content operated by the user. The switch
control unit 82 controls on / off of the switches 81A, 81B, 81C, and 81D in accordance with a
signal output from the operation unit 83. The switch control unit 82 receives an operation for
designating a shape from the user, and applies power to the shape memory members 60A to 60H
corresponding to the designated shape so as to have a shape corresponding to the received
operation. As a result, the shape memory members 60A to 60H are deformed. In addition, in FIG.
2, in order to prevent that a drawing becomes complicated, only shape memory member 60A,
60B is shown in figure, and illustration of shape memory members 60C-60H is abbreviate |
omitted.
[0026]
(Operation of Electrostatic Type Speaker 1) In the electrostatic type speaker 1, there is no
conduction between the power source 80 and the shape memory member 60A when the switch
81A is off, and current flows from the power source 80 to the shape memory members 60A, 60B.
Not flowing. Similarly, when the switch 81B is off, there is no conduction between the power
supply 80 and the shape memory member 60C, and no current flows from the power supply 80
to the shape memory members 60C and 60D. Similarly, there is no conduction between the
power supply 80 and the shape memory member 60E when the switch 81C is off, and no current
flows from the power supply 80 to the shape memory members 60E and 60F. There is no
conduction with the storage member 60G, and no current flows from the power supply 80 to the
shape storage members 60G and 60H. Shape memory members 60A to 60H can be softened and
freely deformed when no current flows.
[0027]
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10
On the other hand, when the switch 81A is turned on with the switches 81B, 81C, 81D turned
off, current flows from the power supply 80 to the shape memory members 60A, 60B and when
current flows in the shape memory members 60A, 60B The temperature of the members 60A
and 60B rises. The shape memory members 60A and 60B are deformed into a linear shape by
the rise in temperature. Since the shape memory members 60A and 60B are fixed to the fixed
electrode 10, the fixed electrodes 10 and 50, the elastic members 20 and 40, and the vibrator 30
(i.e., electrostatic speakers) along with the deformation of the shape memory members 60A and
60B. 1) has a planar shape as illustrated in FIG. That is, with the deformation of the shape
memory members 60A and 60B, the fixed electrodes 10 and 50, the vibrator 30, and the elastic
members 20 and 40 are deformed into a planar shape.
[0028]
When the switch 81B is turned on with the switches 81A, 81C, 81D turned off, current flows
from the power supply 80 to the shape memory members 60C, 60D, and when current flows in
the shape memory members 60C, 60D, shape memory is generated by Joule heat. The
temperature of the members 60C and 60D rises. Due to the rise in temperature, the shape
memory members 60C and 60D are deformed into the above-described zigzag shape A1. Since
the shape memory members 60C and 60D are fixed to the fixed electrode 10, the fixed electrodes
10 and 50, the elastic members 20 and 40, and the vibrator 30 (that is, an electrostatic speaker)
along with the deformation of the shape memory members 60C and 60D. Both ends in the width
direction of 1) are deformed, whereby the entire electrostatic speaker 1 is deformed into a zigzag
shape A1 as shown in FIG. FIG. 3 is a view schematically showing the shape of the electrostatic
speaker 1 when the switch 81B is turned on. Since the shape memory members 60C and 60D are
located along two sides in the longitudinal direction of the fixed electrode 10, when the shape
memory members 60C and 60D are deformed into the zigzag shape A1, the electrostatic speaker
1 is shaped by a human hand Even if it does not arrange, it becomes a zigzag shape A1 as shown
in FIG. That is, when the switch 81B is turned on, the fixed electrodes 10 and 50, the vibrator 30,
and the elastic members 20 and 40 have depths at the outer edge side of the vibrator 30 with
deformation of the shape memory members 60C and 60D. The shape is a serpentine shape that
becomes gradually shallower, and it deforms into a serpentine shape in which the depth of the
folds decreases continuously and gradually.
[0029]
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Further, when the switch 81C is turned on with the switches 81A, 81B and 81D turned off,
current flows from the power supply 80 to the shape memory members 60E and 60F, and when
current flows in the shape memory members 60E and 60F, shape memory is caused by Joule
heat The temperature of the members 60E and 60F rises. The rise in temperature causes the
shape memory members 60E and 60F to be deformed into the above-described zigzag shape A2.
Since the shape memory members 60E and 60F are fixed to the fixed electrode 10, the fixed
electrodes 10 and 50, the elastic members 20 and 40, and the vibrator 30 (that is, an
electrostatic speaker) along with the deformation of the shape memory members 60E and 60F.
Both ends in the width direction of 1) are deformed, whereby the entire electrostatic speaker 1 is
deformed into a zigzag shape A2 as shown in FIG. FIG. 4 is a view schematically showing the
shape of the electrostatic speaker 1 when the switch 81C is turned on. Since the shape memory
members 60E and 60F are located along two sides in the longitudinal direction of the fixed
electrode 10, when the shape memory members 60E and 60F are deformed into the serpentine
shape A2, the electrostatic speaker 1 is shaped by human hands Even if it does not arrange, it
becomes a zigzag shape A2 as shown in FIG. That is, when the switch 81C is turned on, the fixed
electrodes 10 and 50, the vibrating body 30, and the elastic members 20 and 40 connect the
peak connecting the peak and the envelope connecting the valley with the deformation of the
shape memory members 60E and 60F. Then, it is deformed into a serpentine shape having an arc
shape in which the center of the circle is positioned on the fixed electrode 10 side.
[0030]
In addition, when the switch 81D is turned on with the switches 81A, 81B and 81C turned off,
current flows from the power supply 80 to the shape memory members 60G and 60H, and when
current flows in the shape memory members 60G and 60H, shape memory is generated by Joule
heat The temperature of the members 60G and 60H rises. The rise in temperature causes the
shape memory members 60G and 60H to deform into the above-described zigzag shape A3.
Since the shape memory members 60G and 60H are fixed to the fixed electrode 10, the fixed
electrodes 10 and 50, the elastic members 20 and 40, and the vibrator 30 (that is, an
electrostatic speaker) along with the deformation of the shape memory members 60G and 60H.
Both ends in the width direction of 1) are deformed, whereby the entire electrostatic speaker 1 is
deformed into a zigzag shape A3 as shown in FIG. FIG. 5 schematically shows the shape of the
electrostatic loudspeaker 1 when the switch 81D is turned on. Since the shape memory members
60G and 60H are located along two sides in the longitudinal direction of the fixed electrode 10,
when the shape memory members 60G and 60H are deformed into the serpentine shape A3, the
electrostatic speaker 1 is shaped by human hands Even if it does not arrange, it becomes
serpentine shape A3 as shown in FIG. That is, when the switch 81D is turned on, the fixed
electrodes 10 and 50, the vibrating body 30, and the elastic members 20 and 40 connect the
peaks connecting the envelopes and the valleys with the deformation of the shape memory
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members 60G and 60H. Then, it is deformed into a serpentine shape having an arc shape in
which the center of the circle is positioned on the fixed electrode 50 side. As described above, in
the present embodiment, as the shape memory members 60A to 60H are deformed, the fixed
electrodes 10 and 50, the vibrator 30, and the elastic members 20 and 40 have a planar shape, a
serpentine shape A1, a serpentine shape A2, a serpentine shape It deforms into any shape of A3.
[0031]
When an acoustic signal is input to the input unit 71 in a state in which the electrostatic speaker
1 is deformed, a voltage corresponding to the input acoustic signal is applied to the fixed
electrodes 10 and 50. As a result, the vibrator 30 to which the bias voltage is applied by the bias
power source 72 vibrates in response to the acoustic signal, and as a result, a sound wave
corresponding to the acoustic signal is generated. It passes through and is emitted to the outside
of the electrostatic speaker 1.
[0032]
When the electrostatic speaker 1 has a planar shape as shown in FIG. 1, since the sound wave
output from the electrostatic speaker 1 is a plane wave, there is little attenuation due to distance
and a sound field is formed to propagate the sound to the far side. . On the other hand, when the
electrostatic speaker 1 has a serpentine shape A1 shown in FIG. 3, the sound waves generated by
compression and expansion of air in each of the serpentine recessed spaces are basically plane
waves, but A sound field with a relatively wide directivity is formed compared to the case of the
planar shape of (a curved wave close to a point sound source can also be generated).
Furthermore, since the depth of the folds becomes shallower toward the outer edge side of the
vibrating body 30, the volume velocity of the sound emitting surface becomes smaller toward the
outer edge side of the vibrating body 30, and the emitted sound pressure becomes smaller. Can
obtain the suppressed directivity.
[0033]
Further, when the electrostatic speaker 1 has a zigzag shape A2 shown in FIG. 4, the sound wave
output from the electrostatic speaker 1 in the positive direction of the Z axis in the drawing
corresponds to the radiation surface of the concave surface. Since a curved surface wave having
a focal point is generated, the sound waves are concentrated in a narrow range, and a sound field
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in which sound leakage to the surroundings is unlikely to occur is formed. When the electrostatic
speaker 1 has a zigzag shape A3 shown in FIG. 5, the acoustic wave output from the electrostatic
speaker 1 in the positive direction of the Z axis in the drawing is a curved wave corresponding to
the emission surface of the convex curved surface. Because the sound is generated, the sound is
propagated to a wide range.
[0034]
As described above, the user of the electrostatic speaker 1 can select and use the shape of the
electrostatic speaker 1 according to the application and purpose to be installed, the installation
environment, the preference of the user, and the like. Specifically, for example, when it is desired
to use the electrostatic speaker 1 in the zigzag shape A1 shown in FIG. 3, the user performs an
operation for turning on the switch 81B using the operation unit 83. The switch control unit 82
turns on the switch 81B according to the signal output from the operation unit 83. When the
switch 81B is turned on, the electrostatic loudspeaker 1 is deformed into a zigzag shape A1 as
shown in FIG.
[0035]
In this embodiment, the shape of the electrostatic speaker 1 can be changed to a speaker having
different directivity by deforming it from a planar shape into a zigzag shape of a different aspect.
Further, in the present embodiment, the directivity of the generated sound wave can be
controlled by changing the shape of the serpentine shape of the electrostatic speaker 1 to a
different form. Further, in the present embodiment, a circuit for controlling an acoustic signal
supplied to the speaker unit to control directivity is unnecessary, and the device configuration
can be simplified.
[0036]
[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. (1) In the above-described embodiment, the electrostatic
speaker 1 is deformed into a plurality of shapes by the shape memory members 60A to 60H, but
the electrostatic speaker 1 is not limited to being deformable into a plurality of shapes. And may
04-05-2019
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be deformed into one shape. Specifically, for example, only the shape shown in FIG. 3 may be
deformed.
[0037]
Furthermore, the electrostatic speaker 1 is not limited to a deformable one, and may be fixed in a
serpentine shape. In this case, the electrostatic speaker 1 may be configured using a member in
which the fixed electrode, the vibrator, and the elastic member are formed in different shapes in
a plurality of zigzag shapes.
[0038]
(2) The shape of the electrostatic speaker 1 (the shapes of the fixed electrodes 10 and 50, the
vibrator 30, and the elastic members 20 and 40) is not limited to the shape shown in the above
embodiment, but may be another shape. Good. Specifically, for example, the shapes shown in
FIGS. 7 and 8 may be used. In the example shown in FIG. 7, the shape memory member has a
serpentine shape, and the depth of the folds is stepped from the inside to the outer edge side of
the vibrating body 30 every plural areas (five areas in the same figure). A shape which becomes
shallower (hereinafter, referred to as “serpent shape A4”) is stored. In the zigzag shape A4, as
shown in the figure, an envelope S41 connecting a plurality of peaks formed on the fixed
electrode 10 side is a straight line, while an envelope S42 connecting a plurality of valleys
formed on the fixed electrode 50 side. Has a convex shape in which a substantially central
portion of the vibrating body 30 is expanded stepwise.
[0039]
In the example shown in FIG. 7, when the current flows in the shape memory member, the shape
memory member is positioned along the both widthwise ends of the fixed electrode 10, so as the
shape memory member deforms into the serpentine shape A4, The fixed electrodes 10 and 50,
the vibrating body 30, and the elastic members 20 and 40 have a serpentine shape in which the
depth of the folds becomes shallow on the outer edge side of the vibrating body 30, and the
depths of the folds change stepwise in a plurality of regions Transform into a zigzag shape. In the
case of this shape, since the depth of the folds is shallower toward the outer edge side of the
vibrating body 30, the volume velocity of the sound wave radiated becomes smaller toward the
outer edge side of the vibrating body 30, and the side lobe is suppressed. You can get sex.
04-05-2019
15
[0040]
Further, in the example shown in FIG. 8, the shape memory member has a serpentine shape, and
the distance (pitch) between adjacent peaks and peaks (or adjacent valleys and valleys) is outside
the inside of the vibrating body 30. A shape (hereinafter, referred to as “serpent shape A5”)
which gradually widens for each of a plurality of regions (three regions in the same drawing)
toward the edge side is stored. In the zigzag shape A5, as shown in the same figure, an envelope
S51 connecting a plurality of peaks formed on the fixed electrode 10 side and an envelope S52
connecting a plurality of valleys formed on the fixed electrode 50 are straight lines.
[0041]
In the example shown in FIG. 8, when the current flows in the shape memory member, the shape
memory member is located along the both widthwise ends of the fixed electrode 10, and
accordingly, as the shape memory member is deformed into the zigzag shape A5, The fixed
electrodes 10 and 50, the vibrator 30, and the elastic members 20 and 40 have a serpentine
shape in which the pitch of the folds becomes wider on the outer edge side of the vibrator 30,
and the pitch of the folds changes stepwise in a plurality of regions. Transform into a shape. In
the case of this shape, the pitch of the folds becomes wider toward the outer edge side of the
vibrating body 30, so that the volume velocity of the sound wave radiated becomes smaller
toward the outer edge side of the vibrating body 30, and directivity with suppressed side lobes is
obtained. be able to.
[0042]
Further, the present invention is not limited to the example shown in FIG. 8 and may be, for
example, a serpentine shape in which the pitch of the folds changes continuously from the inside
to the outer edge side of the vibrating body. As another example, for example, as shown in FIG. 9,
the spacing P1 between valleys is constant, and the spacing P2 between peaks is wider at the
outer edge side of the vibrator. It may have a shape A6. Also, for example, the spacing between
the peaks may be constant, and the spacing between the valleys may be a serpentine shape in
which the spacing between the valleys becomes wider on the outer edge side of the vibrator. That
is, the fixed electrodes 10 and 50, the vibrating body 30, and the elastic members 20 and 40 may
have a zigzag shape in which the distance between the peaks and the peaks or the valleys and the
04-05-2019
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valleys is wide on the outer edge side of the vibrating body 30. .
[0043]
Moreover, the pitch of the serpentine folding is not limited to the shape described above, for
example, as shown in (a) and (b) of FIG. 10, in the width direction of the fixed electrodes 10 and
50, the vibrating body 30 and the elastic members 20 and 40 It may be a zigzag shape A7 which
is different at both ends in the Y axis direction in the drawing. In the example shown in FIG. 10,
the zigzag shape has a shape in which the pitch is different at both ends in the Y-axis direction in
the drawing. More specifically, the pitch decreases in the direction from the front to the back in
the Y-axis direction. In the case of the serpentine shape shown in FIG. 10, since the pitch on the
near side in the figure in the Y axis direction is large, the side lobe is suppressed only in the area
on the near side in the figure in the Y axis direction. In addition, the shape may be a combination
of the serpentine shape and the serpentine shape shown in FIG. That is, the shapes of the fixed
electrodes 10 and 50, the vibrator 30, and the elastic members 20 and 40 are such that the pitch
is different at both ends in the Y-axis direction in the figure, and the distance between peaks and
peaks or the distance between valleys and valleys May be a serpentine shape that widens on the
outer edge side of the vibrating body 30.
[0044]
Further, as another example, for example, as shown in (a) of FIG. 11, an envelope S81 connecting
a plurality of serpentine peaks and an envelope S82 connecting a plurality of valleys both have
the center of the circle on the fixed electrode 10 side. It may be an arc shape that is positioned,
and a shape in which the serpentine folds become shallower toward the outer edge side. Further,
for example, as shown in (b) of FIG. 11, an arc S91, in which both an envelope S91 connecting a
plurality of serpentine peaks and an envelope S92 connecting a plurality of valleys have the
center of the circle positioned on the fixed electrode 50 side. The shape may be such that the
serpentine folds become shallower toward the outer edge. Further, as shown in FIG. 12, an
envelope S101 connecting a plurality of serpentine peaks is an arc shape in which the center of
the circle is positioned on the fixed electrode 10 side, and an envelope S102 connecting a
plurality of valleys is a fixed electrode 50. The arc shape may be such that the center of the circle
is located on the side, and the serpentine fold may be shallow toward the outer edge. In addition,
an envelope shape is not limited to the meaning of a circular arc shape, for example, the shape
which forms a part of ellipse may be sufficient. In short, the envelope may be a curve convex to
only one side.
04-05-2019
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[0045]
As another example, for example, as shown in FIG. 13, the fixed electrodes 10 and 50, the
vibrator 30, and the elastic members 20 and 40 are in a serpentine shape in a partial region R11
of the vibrator 30 in a stacked state. And may be planar in the other regions R12 and R13.
Further, for example, as shown in FIG. 14, the fixed electrodes 10 and 50, the vibrator 30, and
the elastic members 20 and 40 are in a serpentine shape in a region R21 of a part of the vibrator
30 in a stacked state. The regions R22 and R23 may have a planar shape, and the zigzag shape in
the region R21 may have different shapes in the plurality of regions R211 and R212 and R213.
In addition, shapes other than these may be used. In short, the fixed electrodes 10 and 50, the
vibrating body 30, and the elastic members 20 and 40 are stacked in a state in which some or all
of the area of the vibrating body 30 has peaks. The valleys may be alternately in a zigzag shape,
and different shapes may be used in a plurality of different regions of the vibrator 30 in a
stacked state. Alternatively, the fixed electrodes 10 and 50, the vibrator 30, and the elastic
members 20 and 40 have a zigzag shape in which peaks and valleys are alternately repeated in a
region of a part or the whole of the vibrator 30 in a stacked state. It may be a shape in which at
least one of an envelope connecting a plurality of serpentine peaks or an envelope connecting a
plurality of valleys has a curved shape.
[0046]
(3) In the embodiment described above, although two power supplies are required for the bias
power supply 72 and the power supply 80, voltage division is performed from the bias power
supply 72, a current is supplied to the shape memory members 60A to 60H, and one power
supply is provided. It may be In this configuration, if a current flows from the bias power supply
72 by a switch only when the electrostatic speaker 1 is used, the electrostatic speaker 1 is
deformed into a predetermined shape only by turning on the electrostatic speaker 1. be able to.
In addition, since no current flows in the shape memory members 60A to 60H in a state where
the bias power supply 72 is not turned on and the electrostatic speaker 1 can not produce sound,
deformation of the electrostatic speaker 1 is wasted when it is not caused to produce sound The
power consumption can be reduced without causing the problem.
[0047]
(4) Further, in the present invention, the shapes of the fixed electrodes 10 and 50, the elastic
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18
members 20 and 40, and the vibrating body 30 are not limited to rectangles, and may be other
shapes such as polygons, circles and ovals. It may be. Further, in the present invention, the whole
of the electrostatic speaker 1 may be covered with a nonconductive and acoustically transparent
member.
[0048]
When a conductive cloth is used as the fixed electrodes 10 and 50, the above-described shape
memory alloy may be formed into a thread and woven into the fixed electrodes 10 and 50, and
current may be supplied to the shape memory alloy thus made to be deformed. Good.
[0049]
(5) In the embodiment described above, the shape memory members 60A to 60H are positioned
along two sides in the longitudinal direction (X direction in FIG. 1) of the fixed electrode 10.
However, each side of the fixed electrode 10 (rectangle In the case of (1), shape memory
members may be arranged along the four sides), and the direction in which the folds extend may
be different.
Further, the shape memory member may be disposed along two sides in the Y direction of the
fixed electrode 10. In the embodiment described above, the shape memory members 60A to 60H
are positioned along the respective sides of the fixed electrode 10. However, the shape memory
members may be positioned along the diagonals of the fixed electrode 10 .
[0050]
Further, a plurality of shape memory members may be positioned between the fixed electrode 10
and the elastic members 20 and 40 in parallel with the shape memory members 60A to 60H.
Further, the shape memory members 60A to 60H are arranged not only at the edge portion of
the fixed electrode 10 but also at the edge portion of the fixed electrode 50 so that the
electrostatic speaker 1 can be deformed using both surfaces of the electrostatic speaker 1 You
may In addition, the shape memory members 60A to 60H may be disposed on both the elastic
member 20 and the elastic member 40 or either of the elastic members 20 and 40 instead of the
fixed electrodes 10 and 50.
04-05-2019
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[0051]
(6) In the above embodiment, although a plurality of shape memory alloys are used as the shape
memory members, the shape memory members are not limited to those described above, for
example, they are deformed by applying a force, and the shape after deformation is maintained It
may be a member. The point is that the shape memory member is a shape memory member that
is deformed into any of a plurality of shape patterns and maintains the shape after deformation
by at least one of continuously performing energization and heating and applying a force. Any
shape may be used as long as it has a different shape depending on the mode of energization and
heating and / or the manner of application of force. As a mode of energization, the shape may be
made different depending on which of the plurality of shape memory alloys is energized.
Moreover, as a mode of heating, for example, a plurality of bimetals that are deformed by a
change in temperature may be used as a shape memory member, and the shape may be changed
depending on which bimetal is heated. Also, for example, the shape may be changed by changing
the temperature of heating.
[0052]
(7) Moreover, in the above-mentioned embodiment, the aspect in which the electrostatic
loudspeaker 1 is a push-pull electrostatic loudspeaker has been described. However, the
electrostatic speaker 1 may be a so-called single electrostatic speaker having only one fixed
electrode.
[0053]
(8) In the above-described embodiment and modification, an example has been described in
which the electro-acoustic transducer is applied to an electrostatic speaker that converts an
acoustic signal (electric signal) into sound (acoustic). , And may be applied to electrostatic
microphones that convert sound waves (sounds) into sound signals (electric signals). FIG. 15 is a
diagram showing the electrical configuration of the microphone 2 according to this modification.
The configuration of the electrostatic microphone 2 shown in FIG. 15 is different from that of the
electrostatic speaker 1 of FIG. 2 described above in that an output terminal 73 is provided
instead of the input unit 71. In addition, the transformation ratio of the transformer 70 is
adjusted suitably.
04-05-2019
20
[0054]
When a sound wave is generated outside, the vibration body 30 vibrates due to the sound wave,
and the distance between the vibration body 30 and the electrodes 10 and 50 changes according
to the vibration. , 50 change in capacitance occurs. Here, since the vibrating body 30 is
connected to the bias power supply 72 and the vibrating body 30 is connected to the ground (not
shown), the charge remains constant even if the capacitance changes. In this state, when the
vibrating body 30 vibrates, a voltage output proportional to the displacement of the vibration,
that is, an acoustic signal is obtained. Then, this acoustic signal is supplied to the transformer 70,
transformed by the transformer 70, and output to the output terminal 73.
[0055]
Similarly to the electrostatic speaker 1 in the above-described embodiment, the electrostatic
microphone 2 can also be deformed into various zigzag shapes. For example, when the
electrostatic microphone 2 is deformed into the zigzag shape A1 shown in FIG. 3, the depth of
the folds becomes shallower toward the outer edge side of the vibrating body 30, so that the
volume of the sound collecting surface approaches the outer edge side Because the speed
decreases and the sound collection on the outer edge side becomes weak, the directivity of
efficiently collecting the sound from the front direction of the vibrating body 30 and preventing
the sound from the outer edge direction to be collected is realized can do. The same applies to
the case where the electrostatic microphone 2 has another zigzag shape, and the directivity
control similar to that of the electrostatic speaker 1 can be performed.
[0056]
DESCRIPTION OF SYMBOLS 1 ... electrostatic type speaker (electroacoustic transducer), 2 ...
electrostatic type microphone (electroacoustic transducer) 10, 50 ... fixed electrode, 20, 40 ...
elastic member, 30 ... vibrating body, 60A, 60B, 60C 60D, 60E, 60F, 60G ... shape memory
member, 70 ... transformer, 71 ... input unit, 72 ... bias power supply, 80 ... power supply, 81A,
81B, 81C, 81D ... switch, 82 ... switch control unit, 83 ... Operation unit.
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