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JP2013051663

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DESCRIPTION JP2013051663
Abstract: To provide an acoustoelectric converter capable of changing the directivity
characteristics according to the preference and use of a user with a simple configuration. An
electrostatic speaker 1 includes a fixed electrode 10 and a fixed electrode 10 and a sheet-like
vibrating member spaced apart from the fixed electrode 10 and 50, and a vibrating member 30
and a fixed electrode 10 and 50. It is provided with elastic members 20 and 40 having air
permeability provided between them, and shape memory members 60A to 60H which are
deformed to any one of a plurality of shape patterns predetermined by energization and maintain
the shape after deformation. ing. When the shape memory members 60A to 60H are deformed,
the electrostatic speaker 1 is deformed into any one of a concave surface shape, a planar shape, a
convex surface shape, and a zigzag shape along with the deformation of the shape memory
members 60A to 60H. . [Selected figure] Figure 1
Acoustoelectric converter
[0001]
The present invention relates to an acoustoelectric transducer.
[0002]
Loudspeakers known as electrostatic speakers (capacitor speakers) are known, and are noted in
that they can be designed to be lightweight and compact.
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Here, an example of the configuration of the electrostatic speaker will be described. The
electrostatic loudspeaker comprises two fixed electrodes facing each other across a gap and a
sheet-like member (hereinafter referred to as a vibrator) having conductivity and supported so as
not to contact the fixed electrode between the fixed electrodes. Configured When a
predetermined voltage is applied between the fixed electrode and the vibrating body, a force that
pulls the vibrating body toward one of the electrodes acts by the generated potential difference.
On the other hand, when the direction of the voltage to be applied is reversed, a force in the
reverse direction acts on the vibrating body, and the vibrating body moves in the reverse
direction. As described above, the vibration state (such as the frequency and the amplitude) of
the vibrator can be changed by appropriately applying a voltage to the electrode. Therefore, if
the applied voltage value is changed according to the input signal, the vibrator is Is vibrated
accordingly, and a sound wave corresponding to the input signal is generated from the vibrator.
By forming the fixed electrode with a member having good sound wave permeability (for
example, a metal plate provided with a large number of holes), the generated sound wave passes
through the fixed electrode and is output as a sound to the outside of the speaker.
[0003]
By the way, in a so-called flat type speaker including an electrostatic type speaker, in order to
generate a sound wave having a large vibration area and close to a plane wave due to its
structure, control is performed to widen the directivity characteristics of the sound wave
generated by the vibrator. It is known to be difficult to do. In addition, various techniques have
been proposed for controlling directivity characteristics in a speaker. For example, Patent
Document 1 proposes a technique for collecting a sound wave reflected by a reflector horn at a
focal point by combining a spherical horn reflector horn and a speaker. Further, Patent
Document 2 proposes a technology for causing acoustic vibration to converge at one point by
using a curved acoustic vibration radiation plate. Further, according to Patent Document 3, a
plurality of speakers are arranged in a spherical shape or on a plane, and by adjusting the delay
amount and volume for outputting sound from each speaker, the sound output from each
speaker is focused. There has been proposed a speaker reproducing apparatus capable of
emitting sound. Further, Patent Document 4 proposes an electrostatic speaker that improves the
directivity of a high range by using an accordion curtain-like diaphragm. In addition, in Patent
Document 5, an electrostatic speaker having a diaphragm in which the diaphragm is bent in
accordion pleats, and a plurality of flat electrodes in which fixed electrodes are inserted from the
front and rear surfaces of the diaphragm into the fold thereof is disclosed. Proposed. Further,
Patent Document 6 proposes a capacitor speaker which has flexibility and can be deformed into
any of a concave surface shape, a planar shape, and a convex surface shape. Further, Patent
Document 7 proposes an electrostatic type speaker which can be changed into a predetermined
shape by energizing a shape memory member at the time of use, while making it possible to
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freely change the shape when not in use.
[0004]
JP-A 04-339494 JP-A 11-239394 JP-A 03-159500 JP-A 52-096610 JP-A 56-100600 JP-A
2007-58658 JP-A 2009-194442 Official gazette
[0005]
By the way, it is preferable if the directivity characteristic can be appropriately changed in the
speaker in accordance with the preference and use of the user.
In the technique described in Patent Document 1, since the spherical shell-like reflector horn is
fixed, the directivity characteristic can not be changed. Further, even with the technique
described in Patent Document 2, the directivity characteristic can not be changed because the
shape of the acoustic vibration radiation plate is fixed. In the technique described in Patent
Document 3, in order to change the directivity, it is necessary to provide a delay circuit or a gain
adjustment circuit for each of the speakers constituting the speaker group to control the
operation of each circuit. Could be cumbersome. Further, the speaker array requires many
speaker units to form a wide-band sound field, which may be costly. Further, even with the
techniques described in Patent Documents 4 and 5, the shape of the vibrating membrane is fixed
in an accordion curtain shape (accordion pleat shape), and the directivity characteristic can not
be changed. Further, in the technique described in Patent Document 6, it is necessary to provide
a drive mechanism such as a motor to deform the speaker, which may make the device
configuration complicated. Further, even with the technology described in Patent Document 7,
the directivity characteristics can not be changed. Moreover, although it is also possible to use
the structure of these speakers as a structure of a microphone, also in this case, it was not
possible to change the directivity of the sound collection according to the user's preference or
application. The present invention has been made in view of the above-described background,
and it is an object of the present invention to provide an acousto-electric converter that can
change the directivity characteristics according to the user's direction and application with a
simple configuration.
[0006]
In order to solve the problems described above, according to the present invention, there is
provided an electrode, a sheet-like vibrator having conductivity, which is spaced apart from the
electrode, and a vent provided between the vibrator and the electrode. An elastic member having
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flexibility, fixed to at least one of the electrode and the elastic member, continuously performing
energization and heating, and applying a force, any one of a plurality of shape patterns A shape
memory member which is deformed to maintain the shape after deformation, and which has a
shape different in shape depending on the mode of energization and heating and / or the manner
of application of the force; There is provided an acoustoelectric transducer characterized in that
the electrode, the vibrator and the elastic member are deformed with the deformation of a shape
memory member.
[0007]
In a preferred aspect of the present invention, as the shape memory member is deformed, the
electrode, the vibrator, and the elastic member have a concave surface shape in which the center
is concaved in one direction, and the center in the one direction. May be deformed into at least
one of a convex curved surface shape, a flat surface shape and a serpentine shape.
[0008]
In a further preferred aspect of the present invention, the shape memory member may be made
of a plurality of shape memory alloys, and the shape may be changed depending on which of the
plurality of shape memory alloys is energized.
[0009]
According to the present invention, in the acoustoelectric transducer, the directional
characteristics can be changed according to the preference and the application of the user with a
simple configuration.
[0010]
FIG. 1 is a schematic view of an electrostatic loudspeaker 1 according to an embodiment of the
present invention.
FIG. 2 is a cross-sectional view of the electrostatic speaker 1;
FIG. 1 schematically shows the shape of an electrostatic speaker 1.
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FIG. 6 is a connection diagram showing a connection between shape memory members 60A to
60H and a power supply 80.
FIG. 2 is a cross-sectional view of an electrostatic microphone 2;
[0011]
Hereinafter, an embodiment of the present invention will be described with reference to the
drawings. In the present embodiment, an example in which the acoustoelectric 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. . 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 via a space. 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. Both ends of the fixed electrode 10 and the
fixed electrode 50 are fixed by a fixing member (not shown) made of an insulating material such
as rubber. The fixing member is fixed to the fixed electrode 10 and the fixed electrode 50 using
an adhesive or the like. 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.
[0012]
(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
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fabric in which a conductive material such as metal is deposited by sputtering. By making the
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.
[0013]
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.
[0014]
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.
[0015]
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The shape memory members 60A to 60H are members in which the surface of a linear shape
memory alloy 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. Shape memory members 60B, 60D, 60F, 60H 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 change of the shape memory members 60A to 60H may be interlocked with the
fixed electrode 10. 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. 200220848.
[0016]
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 an arc shape such that the fixed
electrode 10 side is inside the circle as shown in FIG. 3A. Shape memory members 60C and 60D
store linear shapes, and shape memory members 60E and 60F store arc-like curved shapes such
that the fixed electrode 10 side is outside the circle as shown in FIG. 3 (b). ing. As shown in FIG.
3C, the shape memory members 60G and 60H store so-called serpentine shapes in which peaks
and valleys are alternately repeated.
[0017]
FIG. 4 is a connection diagram showing a connection relationship between shape memory
members 60A to 60H and a power supply 80. As shown in FIG. As shown in FIG. 4, one end of
each of the shape memory members 60A, 60C, 60E, and 60G is connected to the positive
terminal of the power supply 80 through the switches 81A, 81B, 81C, and 81D, respectively. The
other ends of shape memory members 60A, 60C, 60E and 60G are connected to one ends of
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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. 4 shows the outer edge of the fixed electrode 10
when the electrostatic speaker 1 is placed on a flat and horizontal surface, and is disposed inside
the outer edge of the conductors L used for the above-mentioned 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 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.
[0018]
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 is an operation receiving
unit that receives an operation for specifying a shape from the user, and the shape memory
members 60A to 60C in a mode corresponding to the specified shape so that the shape
corresponds to the received operation. It is a deformation ¦ transformation means which deform ¦
transforms shape memory member 60A-60H by supplying with respect to 60H. 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.
[0019]
(Operation of Electrostatic Type Speaker 1) In the electrostatic type speaker 1, there is no
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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, 60F, and the switch 81D is
off when the switch 81D is off There is no conduction with the shape memory member 60G, and
no current flows from the power supply 80 to the shape memory members 60G and 60H. Shape
memory members 60A to 60H can be softened and freely deformed when no current flows.
[0020]
On the other hand, when the switch 81A is turned on, 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 shape memory members 60A, 60B rises due to Joule heat, The
storage members 60A and 60B are deformed into an arc-like curved shape such that the fixed
electrode 10 side is inside the circle. 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. Both ends in the width direction of 1) are curved, whereby the entire
electrostatic speaker 1 is curved. FIG. 3A schematically shows the shape of the electrostatic
speaker 1 when the switch 81A is turned on. Since the shape memory members 60A and 60B are
located along two sides in the longitudinal direction of the fixed electrode 10, when the shape
memory members 60A and 60B are deformed in a curved shape, the electrostatic speaker 1 is
shaped by human hands Even without preparation, it becomes a curved curved surface shape in
the longitudinal direction. That is, when the switch 81A is turned on, the fixed electrodes 10 and
50, the vibrator 30, and the elastic members 20 and 40 are viewed from the front when the Z
direction is the front as the shape memory members 60A and 60B are deformed. Deforms into a
concave shape with a hollow center.
[0021]
When the switch 81B is turned on, current flows from the power supply 80 to the shape memory
members 60C and 60D, and when current flows in the shape memory members 60C and 60D,
the temperature of the shape memory members 60C and 60D rises due to Joule heat, and the
shape The shapes of the storage members 60C and 60D are deformed. Since the shape memory
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members 60C and 60D are located along the both widthwise ends of the fixed electrode 10,
when the shape memory members 60C and 60D are deformed in a straight line, the electrostatic
speaker 1 is not shaped by human hands. Is a planar shape as illustrated in FIG. That is, with the
deformation of the shape memory members 60C and 60D, the fixed electrodes 10 and 50, the
vibrator 30, and the elastic members 20 and 40 are deformed into a planar shape.
[0022]
In addition, when the switch 81C is turned on, current flows from the power supply 80 to the
shape memory members 60E and 60F, and the shape memory members 60E and 60F are curved
in an arc shape such that the fixed electrode 10 side is outside the circle. Deform. FIG. 3B 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 the widthwise ends
of the fixed electrode 10, when the shape memory members 60E and 60F are deformed into a
convex curve, both ends in the width direction of the electrostatic speaker 1 are curved. As a
result, the electrostatic speaker 1 has a convex curved shape which is curved in the longitudinal
direction. That is, with the deformation of the shape memory members 60E and 60F, the fixed
electrodes 10 and 50, the vibrator 30, and the elastic members 20 and 40 have convex curved
shapes in which the center is expanded as viewed from the front when the Z direction is the
front. Transform into
[0023]
When the switch 81D is turned on, current flows from the power supply 80 to the shape memory
members 60G and 60H, and the shape of the shape memory members 60G and 60H is deformed
into a zigzag shape. FIG. 3C schematically shows the shape of the electrostatic speaker 1 when
the switch 81D is turned on. Since the shape memory members 60G and 60H are positioned
along the widthwise ends of the fixed electrode 10, when the shape memory members 60G and
60H are deformed into a serpentine shape, the electrostatic speaker 1 has a shape that is
serpentine folded in the longitudinal direction. Become. That is, with the deformation of the
shape memory members 60G and 60H, the fixed electrodes 10 and 50, the vibrator 30, and the
elastic members 20 and 40 are deformed into a serpentine shape. 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 concave
surface shape, a planar shape, a convex surface shape, and a serpentine shape. It deforms into
one of the shapes.
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[0024]
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 to which the bias voltage is applied. Thereby, the vibrating body 30
vibrates corresponding to the input signal. As a result, a sound wave corresponding to the input
signal is generated, and the generated sound passes through the fixed electrodes 10 and 50 and
is emitted to the outside of the electrostatic speaker 1.
[0025]
In the case where the electrostatic speaker 1 has a concave surface shape with respect to the Z
direction in the drawing, the sound wave output from the electrostatic speaker 1 in the Z
direction is focused and the sound wave propagates only in a narrow range. A sound field is
formed which is less likely to cause sound leakage to the surroundings (sound waves are
concentrated at the focal point). On the other hand, when the electrostatic speaker 1 has a planar
shape, the sound wave output from the electrostatic speaker 1 has a strong rectilinearity, so that
a sound field in which the sound propagates to a distance with little attenuation is formed ( Plane
waves are generated). When the electrostatic speaker 1 has a convex curved surface shape in the
Z direction, the sound wave output from the electrostatic speaker 1 in the Z direction is diffused,
so the sound is propagated in a wide range (corresponding to the convex curved surface) Surface
waves are generated). In the case where the electrostatic speaker 1 has a serpentine shape, air is
compressed and pushed out in each of the serpentine concave portions, and the acoustic wave
output from the electrostatic speaker 1 is more omnidirectional than the convex curved shape. A
sound field close to (a curved wave close to a point sound source is generated).
[0026]
In this embodiment, by changing the shape of the electrostatic speaker 1 from a planar shape to
a zigzag shape, it is possible to change from a narrow directional flat speaker to a wide
directional speaker. Even in the case of the convex curved shape, the directivity is wide, but in
the case of the convex curved shape, the width of the speaker is not so narrow because it is
configured by only one convex curved surface, while the shape of the electrostatic speaker 1 is
twisted. In the case of the shape, since the vibrating body is composed of a plurality of folds (that
is, a plurality of convex curved surfaces and a concave curved surface), the speaker width can be
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significantly reduced. Further, in the case of the convex curved surface shape, the depth before
and after the electrostatic speaker 1 is required to some extent, but in the case of the serpentine
shape, the depth can be narrower than the convex curved surface shape. In addition, since the
serpentine shape is a flat shape when viewed as a whole, it can be said that it is more stable than
the curved shape.
[0027]
The user of the electrostatic loudspeaker 1 can select and use the shape of the electrostatic
loudspeaker 1 according to his / her preference and application. Specifically, for example, when
it is desired to use the electrostatic speaker 1 in a zigzag shape, the user performs an operation
for turning on the switch 81D using the operation unit 83. The switch control unit 82 turns on
the switch 81D according to the signal output from the operation unit 83, and when the switch
81D is turned on, the electrostatic speaker 1 is deformed into a serpentine shape as described
above.
[0028]
Flat-shaped speakers are characterized by narrow directivity, but in some cases they may want to
emit sound over a large area. Even in such a case, according to the present embodiment, one
electrostatic speaker 1 realizes both a flat-shaped (narrow directivity) speaker and a zigzagshaped (wide directivity) speaker can do. As described above, according to the present
embodiment, the user can use the electrostatic speaker 1 to realize directivity characteristics
according to his or her preference and application without performing complicated operations.
Moreover, in this embodiment, there is no need to separately provide a drive mechanism such as
a motor for deforming the electrostatic speaker 1, and the device configuration can be simplified.
[0029]
[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 embodiment described above, although two power
supplies are required for the bias power supply 72 and the power supply 80, voltage division is
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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 the 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.
[0030]
(2) Further, in the present invention, the shapes of the fixed electrodes 10 and 50, the elastic
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.
[0031]
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.
[0032]
(3) 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 (1), shape memory members
may be arranged along the four sides).
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 .
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[0033]
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.
[0034]
(4) In the embodiment described above, the electrostatic speaker 1 has been described as being
deformed into a concave surface shape, a planar shape, a convex surface shape, or a serpentine
shape, but the shape of the electrostatic speaker 1 Are not limited to those described above, but
may be in other shapes. The point is that the fixed electrodes 10 and 50, the vibrator 30, and the
elastic members 20 and 40 may be deformed into a plurality of shapes in accordance with the
deformation of the shape memory member.
[0035]
(5) 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.
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[0036]
(6) 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.
[0037]
(7) In the embodiment and the modification described above, an example in which the
acoustoelectric converter is applied to an electrostatic speaker that converts an acoustic signal
(electric signal) into sound (sound) has been described. , And may be applied to electrostatic
microphones that convert sound waves (sounds) into sound signals (electric signals). FIG. 5 is a
diagram showing the electrical configuration of the electrostatic microphone 2 according to this
modification. The configuration of the electrostatic microphone 2 shown in FIG. 5 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.
[0038]
When a sound is generated outside, the vibrating body 30 is vibrated by the sound, and the
distance between the vibrating body 30 and the electrodes 10 and 50 changes according to the
vibration. , 50 change in capacitance occurs. The change in capacitance causes a current to flow
between the electrode 10 and the electrode 50, thereby providing a voltage output, that is, an
acoustic signal. Then, this acoustic signal is supplied to the transformer 70, transformed by the
transformer 70, and output to the output terminal 73.
[0039]
The electrostatic microphone 2 can also be deformed into various shapes as the electrostatic
speaker 1 in the above-described embodiment. The user of the electrostatic microphone 2 can
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select and use the shape of the electrostatic microphone 2 in accordance with his / her
preference and application. Specifically, for example, when it is desired to use the microphone 2
in a zigzag shape, the user performs an operation for turning on the switch 81D using the
operation unit 83. The switch control unit 82 turns on the switch 81D according to the signal
output from the operation unit 83, and when the switch 81D is turned on, the microphone 2 is
deformed into a zigzag shape as in the above-described embodiment.
[0040]
DESCRIPTION OF SYMBOLS 1 ... electrostatic type speaker (acoustic electrical 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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