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DESCRIPTION JP2009296594

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DESCRIPTION JP2009296594
The present invention relates to a thermoacoustic apparatus and a sound transmission system
using the same, and more particularly to a thermoacoustic apparatus using carbon nanotubes
and a sound transmission system using the same. An apparatus of the present invention includes
an electromagnetic signal device and an acoustic wave generator including a carbon nanotube
structure. The electromagnetic signal device transmits an electromagnetic signal to the carbon
nanotube structure. Alternatively, the device of the present invention comprises an
electromagnetic signal device and an acoustic wave generator comprising a carbon nanotube
structure. The electromagnetic signal device transmits an electromagnetic signal to the carbon
nanotube structure. The carbon nanotube structure converts the electromagnetic signal into heat
to cause the medium to generate a thermoacoustic effect. [Selected figure] Figure 1
Thermoacoustic device
[0001]
The present invention relates to a thermoacoustic apparatus and a sound transmission system
using the same, and more particularly to a thermoacoustic apparatus using carbon nanotubes
and a sound transmission system using the same.
[0002]
In general, an acoustic device comprises a signal device and a sound generator.
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The signaling device transmits a signal to the sound generator (e.g. a speaker). The speaker can
convert an electrical signal to sound as an electroacoustic transducer.
[0003]
According to the principle of operation, speakers are classified into various types such as
dynamic speakers, magnetic speakers, electrostatic speakers, and piezoelectric speakers. The
various types of speakers all produce mechanical sound by means of mechanical vibration, that
is, they realize electro-mechanical force-sound conversion. Here, dynamic speakers are widely
used.
[0004]
Referring to FIG. 36, a conventional dynamic speaker 100 includes a voice coil 102, a magnet
104, and a cone 106. The voice coil 102 is disposed between the magnets 104 as a conductive
component. When a current is supplied to the voice coil 102, the cone 106 is vibrated by the
interaction of the electromagnetic field of the voice coil 102 and the magnetic field of the magnet
104 to continuously generate pressure fluctuation of air, thereby generating a sound wave. it
can.
[0005]
However, since the dynamic speaker 100 relies on the action of a heavy magnet and a magnetic
field, the structure of the dynamic speaker 100 is complicated. In addition, the magnet 104 of the
dynamic speaker 100 has a problem of adversely affecting an electronic device disposed close to
the speaker. Furthermore, since the dynamic speaker 100 operates under the condition of the
input of the electric signal, the dynamic speaker 100 can not operate when the electric signal is
not provided.
[0006]
Thermoacoustic phenomenon is a phenomenon in which sound and heat are related, and there
are two aspects, energy conversion and energy transport. Transferring the signal to the
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thermoacoustic device generates heat in the thermoacoustic device and propagates to the
surrounding media. Sound waves can be generated due to thermal expansion and pressure waves
generated by the transferred heat.
[0007]
H.D.Arnold、I.B.Crandall, “The thermophone as a
precision source of sound”, Phys. 1917, 10, 22-38, Alexander
Graham Bell, "Selenium and the Photophone", Nature, September 1880) Kaili Jiang, Qunqing Li,
Shoushan Fan, "Spinning continuous carbon nanotube yarns", Nature, 2002, 419, p. 801
[0008]
Non-Patent Document 1 discloses a thermophone manufactured by a thermoacoustic
phenomenon. Here, a platinum piece having a thickness of 7 × 10 <-5> cm is used as a
thermoacoustic component. However, for a platinum piece having a thickness of 7 × 10 <-5> cm,
the heat capacity per unit area is 2 × 10 <-4> J / cm <2> · K. Since the heat capacity per unit
area of platinum pieces is very high, there is a problem that the thermophone using platinum
pieces has very weak sound when used outdoors.
[0009]
The photoacoustic effect is a phenomenon in which sound and light are related, that is, a
molecule in which light energy is absorbed emits heat and generates an acoustic wave
(compression wave) by volume expansion due to the heat. . The photoacoustic effect is disclosed
for the first time in Non-Patent Document 2.
[0010]
Photoacoustic effects are currently used in the technical field of material analysis. For example, a
photoacoustic spectroscopy device by a photoacoustic effect, a photoacoustic microscope, etc.
are widely used in the technical field of material analysis. Conventionally, photoacoustic
spectrum devices include a light source (eg, a laser device), a sealed sample chamber, and a
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signal detector (eg, a microphone). A gas, liquid or solid sample is placed in the sample chamber,
and the sample is irradiated with a laser by the laser device. In this case, the sample generates a
sound pressure due to the photoacoustic effect. When irradiating lasers of different frequencies,
different materials have different maximum absorption capabilities for the laser. A microphone
can be used to detect the maximum absorption capacity. However, most of the sound pressure is
so weak that it can not be detected by the human ear, making it necessary to install a complex
sensor. Therefore, there are limitations to the application of the speaker.
[0011]
The present invention provides a lightweight thermoacoustic device in order to solve the abovementioned problems. The thermoacoustic apparatus of the present invention can generate sound
independently of a magnetic field and not by mechanical vibration.
[0012]
The device of the present invention comprises an electromagnetic signal device and an acoustic
wave generator comprising a carbon nanotube structure. The electromagnetic signal device
transmits an electromagnetic signal to the carbon nanotube structure.
[0013]
The device of the present invention comprises an electromagnetic signal device, an acoustic wave
generator comprising a carbon nanotube structure, and a medium. The electromagnetic signal
device transmits an electromagnetic signal to the carbon nanotube structure. The carbon
nanotube structure converts the electromagnetic signal into heat to cause the medium to
generate a thermoacoustic effect.
[0014]
The heat capacity per unit area of the carbon nanotube structure is 2 × 10 <-4> J / cm <2> · K or
less.
[0015]
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The device comprises an optical fiber.
[0016]
A modulation device is installed between the electromagnetic signal device and the sound wave
generator.
[0017]
In the carbon nanotube structure, carbon nanotubes are connected by intermolecular force and
uniformly distributed.
[0018]
The carbon nanotube structure includes at least one carbon nanotube film.
[0019]
The carbon nanotube structure includes a plurality of carbon nanotube wires.
[0020]
The apparatus is provided with a support for supporting the sound wave generator.
[0021]
The sound transmission system of the present invention includes a sound-electro converting
device, an electro-wave converting device, and a sound generator.
The sound generator includes a carbon nanotube structure.
The electromagnetic wave conversion device transmits an electromagnetic signal to the sound
wave generator.
The carbon nanotube structure converts an electromagnetic signal into heat to produce a
thermoacoustic effect in the medium.
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[0022]
Compared to the prior art, the thermoacoustic apparatus of the present invention has the
following advantages.
First, since the thermoacoustic apparatus of the present invention includes a carbon nanotube
structure, the structure is simple and the weight and size can be reduced as compared with the
conventional speaker.
Second, since the thermoacoustic apparatus of the present invention generates an acoustic wave
by heating the carbon nanotube structure, it is not necessary to use a magnet.
Third, since the carbon nanotube structure has a small heat capacity per unit area, a large
specific surface area, and a high rate of heat exchange, sound can be generated favorably.
Fourth, since the carbon nanotube structure is thin, a transparent acoustic device can be
manufactured. Fifth, since the thermoacoustic apparatus of the present invention can transmit an
electromagnetic signal in a vacuum atmosphere, the thermoacoustic apparatus of the present
invention can be used in an extreme environment. The thermoacoustic apparatus of the present
invention can be used under conditions where it can not receive an electrical signal (eg, a
flammable environment).
[0023]
It is a schematic diagram of the thermoacoustic apparatus in Example 1 of this invention. It is a
SEM photograph of the carbon nanotube film in Example 1 of this invention. It is a schematic
diagram of the carbon nanotube segment in Example 1 of this invention. It is a SEM photograph
of the carbon nanotube film in Example 1 of this invention. It is a SEM photograph of the
segment of the carbon nanotube film in Example 1 of the present invention. It is a SEM
photograph of the carbon nanotube wire in Example 1 of this invention. It is a SEM photograph
of the twisted carbon nanotube wire in Example 1 of the present invention. It is a schematic
diagram of textiles which consist of a plurality of carbon nanotube films and / or carbon
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nanotube wires in Example 1 of the present invention. It is a frequency response curve of the
thermoacoustic apparatus in Example 1 of this invention. It is a schematic diagram of the
thermoacoustic apparatus in Example 1 of this invention. It is a schematic diagram of the
thermoacoustic apparatus in Example 2 of this invention. It is a schematic diagram of the
thermoacoustic apparatus in Example 3 of this invention. It is a schematic diagram of the
thermoacoustic apparatus in Example 4 of this invention. It is a schematic diagram of the
thermoacoustic apparatus in Example 5 of this invention. It is a schematic diagram of the
thermoacoustic apparatus in Example 6 of this invention. It is a circuit diagram in Example 6 of
this invention. It is a graph which shows the bias voltage which used the power amplifier in
Example 6 of this invention. It is a schematic diagram of the thermoacoustic apparatus in
Example 6 of this invention. It is a schematic diagram of the thermoacoustic apparatus in
Example 6 of this invention. It is a schematic diagram of the thermoacoustic apparatus in
Example 7 of this invention. It is a schematic diagram of textiles which consist of a plurality of
carbon nanotube films and / or carbon nanotube wires in Example 7 of the present invention. It
is a figure which shows adhering the carbon nanotube film shown by two sheets of FIG. 2 to a
frame part. It is a related curve of the sound pressure of the thermoacoustic apparatus in
Example 7 of this invention, and time. It is a chart which shows the relationship between the
sound pressure of the thermoacoustic apparatus in Example 7 of this invention, and an output. It
is a chart which shows the relationship between the sound pressure of the thermoacoustic
apparatus in Example 7 of this invention, and an output. It is a chart which shows the
relationship between the sound pressure of the thermoacoustic apparatus in Example 7 of this
invention, and an output. It is a chart which shows the relationship between the sound pressure
of the thermoacoustic apparatus in Example 7 of this invention, and an output. It is a schematic
diagram of the thermoacoustic apparatus in Example 8 of this invention. It is a schematic
diagram of the thermoacoustic apparatus in Example 9 of this invention. It is a schematic
diagram of the thermoacoustic apparatus in Example 10 of this invention.
It is a schematic diagram of the thermoacoustic apparatus in Example 11 of this invention. It is a
schematic diagram of the thermoacoustic apparatus in Example 12 of this invention. It is a top
view of the thermoacoustic apparatus in Example 12 of this invention. It is a schematic diagram
of the sound transmission system of this invention. It is a chart of the sound wave generation
method of the present invention. It is a schematic diagram of the conventional speaker.
[0024]
Hereinafter, embodiments of the present invention will be described with reference to the
drawings.
[0025]
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Example 1 Referring to FIG. 1, the thermoacoustic device 10 of the present invention includes a
signal device 12, a sound wave generator 14, a first electrode 142, and a second electrode 144.
The first electrode 142 and the second electrode 144 are each electrically connected to the
sound wave generator 14 so as to be separated by a predetermined distance. The first electrode
142 and the second electrode 144 are electrically connected to the signal device 12 respectively.
The first electrode 142 and the second electrode 144 transfer the signal from the signal device
12 to the sound generator 14.
[0026]
The sound wave generator 14 includes a carbon nanotube structure. The carbon nanotube
structure has a large specific surface area (eg, 100 m <2> / g or more). The heat capacity per unit
area of the carbon nanotube structure is 0 (not including 0) to 2 × 10 <-4> J / cm <2> · K, but
preferably 0 (not including 0). It is -1.7 * 10 <-6> J / cm <2> * K, and it is 1.7 * 10 <-6> J / cm
<2> * K in a present Example. Furthermore, a metal layer can be formed on the surface of the
carbon nanotube structure. A plurality of carbon nanotubes are uniformly dispersed in the
carbon nanotube structure. The plurality of carbon nanotubes are connected by intermolecular
force. The carbon nanotube structure needs to contain metallic carbon nanotubes. In the carbon
nanotube structure, the plurality of carbon nanotubes are arranged in an oriented manner or not
oriented. The carbon nanotube structures are classified into two types of non-oriented carbon
nanotube structures and oriented carbon nanotube structures according to the arrangement of
the plurality of carbon nanotubes. In the non-oriented carbon nanotube structure in this
embodiment, the carbon nanotubes are arranged or entangled along different directions. In the
oriented carbon nanotube structure, the plurality of carbon nanotubes are arranged along the
same direction. Alternatively, in the oriented carbon nanotube structure, when the oriented
carbon nanotube structure is divided into two or more regions, a plurality of carbon nanotubes in
each region are aligned along the same direction. In this case, the alignment directions of carbon
nanotubes in different regions are different. The carbon nanotube is a single-walled carbon
nanotube, a double-walled carbon nanotube, or a multi-walled carbon nanotube. When the
carbon nanotube is a single-walled carbon nanotube, the diameter is set to 0.5 nm to 50 nm, and
when the carbon nanotube is a double-walled carbon nanotube, the diameter is set to 1 nm to 50
nm, and the carbon nanotube is a multilayer carbon In the case of nanotubes, the diameter is set
to 1.5 nm to 50 nm.
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[0027]
The carbon nanotube structure is flat and has a thickness of 0.5 nm to 1 mm. The heat capacity
per unit area of the carbon nanotube structure increases as the specific surface area of the
carbon nanotube structure decreases. As the heat capacity per unit area of the carbon nanotube
structure is higher, the sound pressure of the thermoacoustic device is lower.
[0028]
The carbon nanotube structure includes at least one carbon nanotube film 143a shown in FIG.
The carbon nanotube film 143a is obtained by drawing from a super-aligned carbon nanotube
array (refer to Non-Patent Document 3). In the single carbon nanotube film, a plurality of carbon
nanotubes are connected end to end along the same direction. Referring to FIGS. 2 and 3, the
single carbon nanotube film 143a includes a plurality of carbon nanotube segments 143b. The
plurality of carbon nanotube segments 143b are connected end to end by intermolecular force
along the length direction. Each carbon nanotube segment 143b includes a plurality of carbon
nanotubes 145 connected by intermolecular force in parallel to each other. The lengths of the
plurality of carbon nanotubes 145 are the same in the single carbon nanotube segment 143b.
Toughness and mechanical strength of the carbon nanotube film 143a can be enhanced by
immersing the carbon nanotube film 143a in an organic solvent. Since the heat capacity per unit
area of the carbon nanotube film immersed in the organic solvent is low, the thermoacoustic
effect can be enhanced. The carbon nanotube film 143a has a width of 100 μm to 10 cm and a
thickness of 0.5 nm to 100 μm.
[0029]
The carbon nanotube structure may include a plurality of stacked carbon nanotube films. In this
case, the adjacent carbon nanotube films are bonded by an intermolecular force. The carbon
nanotubes in the adjacent carbon nanotube film cross each other at an angle of 0 ° to 90 °.
When the carbon nanotubes in the adjacent carbon nanotube film intersect at an angle of 0 ° or
more, a plurality of micro holes are formed in the carbon nanotube structure. Alternatively, the
plurality of carbon nanotube films may be juxtaposed without gaps.
[0030]
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The carbon nanotube structure includes at least one carbon nanotube film. Referring to FIG. 4, in
the single carbon nanotube film, a plurality of carbon nanotubes are entangled and arranged
isotropically. In the carbon nanotube structure, the plurality of carbon nanotubes are uniformly
distributed. The plurality of carbon nanotubes are arranged without orientation. The length of
the single carbon nanotube is 10 cm or more. The carbon nanotube structure is formed in the
shape of a free-standing thin film. Here, the self-supporting structure is a mode in which the
carbon nanotube structure can be independently used without using a support material. The
plurality of carbon nanotubes are formed close to each other by intermolecular force and
mutually intertwined to form a carbon nanotube network. The plurality of carbon nanotubes are
arranged without being oriented to form many minute holes. Here, the diameter of the single
minute hole is 10 μm or less. Since the carbon nanotubes in the carbon nanotube structure are
arranged to be entangled with each other, the carbon nanotube structure is excellent in flexibility
and can be formed to be curved in an arbitrary shape. Depending on the application, the length
and width of the carbon nanotube structure can be adjusted. The thickness of the carbon
nanotube structure is 0.5 nm to 1 mm.
[0031]
The carbon nanotube structure includes one carbon nanotube film segment. Referring to FIG. 5,
all carbon nanotubes in the segment of the carbon nanotube film are parallel to one another and
parallel along a predetermined direction. In the carbon nanotube film segment, the length of at
least one carbon nanotube is the same as the entire length of the carbon nanotube film segment.
Accordingly, the dimensions of one of the segments of the carbon nanotube film are limited by
the length of the carbon nanotube. The carbon nanotube structure may include a plurality of
stacked carbon nanotube film segments. In this case, adjacent segments of the carbon nanotube
film are bonded by intermolecular force. The thickness of the segment of the carbon nanotube
film is 0.5 nm to 100 μm.
[0032]
The carbon nanotube structure includes at least one carbon nanotube wire. The heat capacity of
one carbon nanotube wire is 2 × 10 <-4> J / cm <2> · K or less, preferably 5 × 10 <-5> J / cm
<2> · K . The diameter of one carbon nanotube wire is 4.5 nm to 1 cm. Referring to FIG. 6, the
carbon nanotube wire comprises a plurality of carbon nanotubes connected by intermolecular
force. In this case, a single carbon nanotube wire includes a plurality of carbon nanotube
segments (not shown) connected end to end. The carbon nanotube segments have the same
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length and width. Furthermore, a plurality of carbon nanotubes of the same length are arranged
in parallel to each of the carbon nanotube segments. The plurality of carbon nanotubes are
arranged parallel to the central axis of the carbon nanotube wire. In this case, the diameter of
one carbon nanotube wire is 1 μm to 1 cm. Referring to FIG. 7, the carbon nanotube wire may
be twisted to form a twisted carbon nanotube wire. Here, the plurality of carbon nanotubes are
arranged in a spiral shape with the central axis of the carbon nanotube wire as an axis. In this
case, the diameter of one carbon nanotube wire is 1 μm to 1 cm. The carbon nanotube structure
may be formed of any one of the non-twisted carbon nanotube wire, the twisted carbon nanotube
wire, or a combination thereof.
[0033]
In the case where the carbon nanotube structure includes a plurality of carbon nanotube wires,
the plurality of carbon nanotube wires may be arranged in parallel or in parallel, or may be
woven or twisted. A fabric comprising a plurality of carbon nanotube wires 146 is shown in FIG.
A first electrode 142 and a second electrode 144 are respectively installed at opposite ends of
the fabric. The first electrode 142 and the second electrode 144 are electrically connected to the
carbon nanotube wire 146.
[0034]
Since the carbon nanotube structure is flexible, the carbon nanotube structure can be formed
into various shapes, and furthermore, the carbon nanotube structure can be placed on the
surface of a hard insulator or a flexible insulator (for example, a flag or cloth) can do. If the flag
on which the carbon nanotube structure is installed is windy, it can be used as the sound wave
generator 14. The cloth on which the carbon nanotube structure is installed can play music as a
player such as MP3. Furthermore, by using the cloth on which the carbon nanotube structure is
installed, it is possible to help disabled persons (e.g. deaf persons).
[0035]
Even when a part of the carbon nanotube structure used for the sound wave generator 14 is
ruptured, the carbon nanotube structure can generate sound waves. On the other hand, if the
diaphragm or cone of the conventional speaker is damaged, the sound wave can not be
generated.
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[0036]
As shown in FIG. 1, the sound wave generator 14 of the present embodiment includes a carbon
nanotube structure. The carbon nanotube structure includes a carbon nanotube film. In the
carbon nanotube film, carbon nanotubes are arranged along the same direction. The sound wave
generator 14 has a length of 3 cm, a width of 3 cm, and a thickness of 50 nm. If the sound wave
generator 14 is provided thin (10 μm or less in thickness), the sound wave generator 14 has
excellent transparency. Therefore, by using the transparent sound wave generator 14, a
transparent thermoacoustic device can be manufactured. The transparent thermoacoustic device
can be installed, for example, on the surface of a mobile phone or LCD. Alternatively, the
transparent thermoacoustic device can be affixed to the surface of the picture. The use of the
transparent sound wave generator 14 has the merit of making the thermoacoustic device
compact and lightweight.
[0037]
The first electrode 142 and the second electrode 144 are made of any conductive material of
metal, conductive adhesive, carbon nanotube, and ITO. In the present embodiment, the first
electrode 142 and the second electrode 144 are rod-like metal electrodes. The sound wave
generator 14 is electrically connected to the first electrode 142 and the second electrode 144,
respectively. Since the carbon nanotube structure used for the sound wave generator 14 has
adhesiveness, the sound wave generator 14 can be directly bonded to the first electrode 142 and
the second electrode 144. Furthermore, the first electrode 142 and the second electrode 144 are
connected to both ends of the signal device 12 by conductive wires 149, respectively.
[0038]
Conductivity between the first electrode 142 or the second electrode 144 and the sound wave
generator 14 in order to make a good electrical connection between the first electrode 142 or
the second electrode 144 and the sound wave generator 14 An adhesive layer (not shown) can
also be provided. The conductive adhesive layer may be disposed on the surface of the sound
wave generator 14. The conductive adhesive layer is made of silver paste.
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12
[0039]
The signal device 12 is any one of an electrical signal device, a direct current pulsation signal
device, an alternating current device, and an electromagnetic wave signal device (for example, an
optical signal device, a laser). The signal transferred from the signal device 12 to the sound wave
generator 14 is, for example, an electromagnetic wave (for example, an optical signal), an electric
signal (for example, alternating current, direct current pulsation signal, audio electric signal) or a
mixed signal thereof. is there. The signal is received by the carbon nanotube structure and
emitted as heat. The radiation of heat changes the pressure intensity of the surrounding medium
(environment), so that a detectable signal can be generated. When the thermoacoustic device 10
is used for an earphone, the input signal is an AC electrical signal or an audio electrical signal.
When the thermoacoustic apparatus 10 is used for a photoacoustic spectrum device, the input
signal is an optical signal. In the present embodiment, the signal device 12 is a photoacoustic
spectrum, and the input signal is an electrical signal.
[0040]
The placement of the first electrode 142 and the second electrode 144 is optional for different
types of the signal devices 12. For example, if the signal from the signal device 12 is an
electromagnetic wave or light, the signal device 12 can transfer the signal to the sound wave
generator 14 without using the first electrode 142 and the second electrode 144. .
[0041]
In the signal device 12, since the carbon nanotube structure of the sound wave generator 14
includes a plurality of carbon nanotubes and the heat capacity per unit area is small, the
temperature wave generated by the sound wave generator 14 causes pressure on the
surrounding medium. Vibration can be generated. When a signal (e.g., an electrical signal) is
transferred to the carbon nanotube structure of the sound wave generator 14, heat is generated
in the carbon nanotube structure by the signal strength and / or the signal. The diffusion of the
temperature wave thermally expands the surrounding air to produce a sound. This principle is
largely different from the principle of generating sound by the pressure wave generated by the
mechanical vibration of the diaphragm in the conventional speaker. If the input signal is an
electrical signal, the thermoacoustic device 10 operates according to an electro-thermal-sound
conversion scheme, but if the input signal is an optical signal, the thermo-acoustic device 10 may
be a photo-thermal device. -Operate by the sound conversion system. The energy of the optical
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signal is absorbed by the sound generator 14 and emitted as heat. As the heat radiation changes
the pressure intensity of the surrounding medium (environment), a detectable signal can be
generated.
[0042]
FIG. 9 is a frequency response curve of the thermoacoustic apparatus in Example 1 of the present
invention. In this case, an AC electrical signal of 50 V is provided to the carbon nanotube
structure. In order to detect the performance of the thermoacoustic apparatus 10, a microphone
is installed at a distance of 5 cm from the sound wave generator 14 so as to face one side of the
sound wave generator 14. It can be understood from FIG. 9 that the frequency response range of
the thermoacoustic device 10 is wide and the sound pressure level is high. The sound pressure
level of the thermoacoustic device 10 is 50 dB to 105 dB. Thermoacoustic Device 10 When a
voltage of 4.5 W is applied to the thermoacoustic device 10, the frequency response range of the
thermoacoustic device 10 is 1 Hz to 100 KHz. The harmonic distortion of the thermoacoustic
device 10 can be very small, for example reaching as low as 3% in the range of 500 Hz to 40
KHz.
[0043]
When the carbon nanotube structure of the thermoacoustic device 10 includes five carbon
nanotube wires, the distance between the adjacent carbon nanotube wires is 1 cm, and the
diameter of one carbon nanotube wire is 50 μm. It is. When transferring a 50 V AC electrical
signal to the carbon nanotube structure, the sound pressure level generated by the
thermoacoustic device 10 is 50 dB to 100 dB. When a voltage of 4.5 W is applied to the
thermoacoustic device 10, the frequency response range of the thermoacoustic device 10 is 100
Hz to 100 KHz.
[0044]
Furthermore, because the carbon nanotube structure has excellent mechanical strength and
toughness, it is possible to provide the carbon nanotube structure in the desired shape and size,
whereby a large number of desired shapes and sizes can be obtained. It is possible to obtain a
thermoacoustic device 10. The thermoacoustic apparatus 10 can be used, for example, for an
acoustic system, a mobile phone, an MP3, an MP4, a TV, a computer, and the like.
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14
[0045]
Example 2 Referring to FIG. 10, the thermoacoustic apparatus 20 of the present example
includes a signal apparatus 22, a sound wave generator 24, a first electrode 242, a second
electrode 244, and a third electrode 246; And a fourth electrode 248. The configuration,
characteristics, and functions of the thermoacoustic apparatus 20 of the present embodiment are
the same as those of the thermoacoustic apparatus 10 of the first embodiment. The difference
between the present embodiment and the first embodiment is that the thermoacoustic device 20
of the present embodiment includes four electrodes (first electrode 242, second electrode 244,
third electrode 246, fourth electrode 248). is there. The four electrodes are rod-shaped, and are
separately installed at predetermined distances. The sound wave generator 24 is electrically
connected to the four electrodes so as to surround the four electrodes. Furthermore, the first
electrode 242 and the third electrode 246 are electrically connected in parallel to one end of the
signal device 22 by a first conductive wire 249. The second electrode 244 and the fourth
electrode 248 are electrically connected in parallel to the other end of the signal device 22 by a
second conductive line 249 '. Since the electrodes are connected in parallel to the signal device
22, the voltage applied to the thermoacoustic device 20 is low.
[0046]
Referring to FIG. 11, the four electrodes may be disposed in the same plane. In this case, the
plurality of electrodes can be installed in the thermoacoustic device 20 without being limited to
the four electricitys.
[0047]
Example 3 Referring to FIG. 12, the thermoacoustic apparatus 30 of the present example
includes a signal device 32, a sound wave generator 34, a first electrode 342, and a second
electrode 344. The configuration, characteristics, and functions of the thermoacoustic apparatus
30 of the present embodiment are the same as the thermoacoustic apparatus 10 of the first
embodiment. The difference between the present embodiment and the first embodiment is that
the thermoacoustic apparatus 20 of the present embodiment includes a support 36. The sound
wave generator 34 is mounted on the surface of the support 36. The shape of the support 36 is
determined according to the shape of the sound wave generator 34. The support 36 is flat or /
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and curved. The support 36 is any one of a screen, a wall, a desk, and a display. The sound wave
generator 34 can be in contact with the support 36.
[0048]
The support 36 is made of a hard material such as diamond, glass or quartz, or a flexible material
such as plastic, resin or fabric. The support 36 is thermally insulating and can not absorb the
heat generated by the sound wave generator 34. Furthermore, it is preferable that the surface in
contact with the support 36 and the sound wave generator 34 be provided rough. As a result, the
area in which the sound wave generator 34 contacts the peripheral catalyst can be increased.
Since the carbon nanotube structure has a large specific surface area, the sound wave generator
34 can be directly adhered to the support 36.
[0049]
An adhesive layer (not shown) may be provided between the sound wave generator 34 and the
support 36 in order to make a good connection between the sound wave generator 34 and the
support 36. The adhesive layer may be disposed on the surface of the sound wave generator 34.
In this embodiment, the conductive adhesive layer is made of silver paste.
[0050]
The first electrode 342 and the second electrode 344 are disposed on the same surface of the
sound wave generator 34 or respectively on opposing surfaces of the sound wave generator 34.
A plurality of electrodes can be installed on the thermoacoustic device 20 without being limited
to the two electrodes. The signal device 32 is connected to the sound wave generator 34 by a
conductive wire 349.
[0051]
Example 4 Referring to FIG. 13, the thermoacoustic apparatus 40 of this example includes a
signal apparatus 42, a sound wave generator 44, a support 46, a first electrode 442, a second
electrode 444, It includes a three electrode 446 and a fourth electrode 448. The configuration,
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characteristics, and functions of the thermoacoustic apparatus 30 of the present embodiment are
the same as the thermoacoustic apparatus 10 of the first embodiment. The difference between
the present embodiment and the third embodiment is that the sound wave generator 44 is
installed so as to surround the support 46. The support 46 is, for example, a three-dimensional
or two-dimensional structure such as a cube, a cone, or a cylinder. In the present embodiment,
the support 46 has a cylindrical shape, and the first electrode 442, the second electrode 444, the
third electrode 446, and the fourth electrode 448 are separated by a predetermined distance,
respectively. It is electrically connected to the sound wave generator 44. The manner in which
the first electrode 442, the second electrode 444, the third electrode 446, and the fourth
electrode 448 are connected to the signal device 42 is the same as in the first embodiment. Of
course, the plurality of electrodes can be installed in the thermoacoustic device 40 without being
limited to the four electricitys.
[0052]
Example 5 Referring to FIG. 14, the thermoacoustic apparatus 50 of the present example
includes a signal device 52, a sound wave generator 54, a support 56, a first electrode 542, and a
second electrode 544. Including. The configuration, characteristics, and functions of the
thermoacoustic apparatus 50 of the present embodiment are the same as the thermoacoustic
apparatus 30 of the third embodiment. The difference between this embodiment and the third
embodiment resides in that a space for sound collection is formed from the sound wave
generator 54 and the support 56 by placing a part of the sound wave generator 54 on the
support 56. It is. The space is a closed space or an open space. The support 56 is U-shaped or Lshaped. The thermoacoustic device 50 can include two or more of the supports 56. The support
56 is any one of wood, plastic, metal and glass. Referring to FIG. 14, in the present embodiment,
the support 56 is L-shaped, and the sound wave generator 54 extends from the first end 562 of
the support to the second end 564 so that the sound wave generator is A space for sound
collection can be formed from 54 and the support 56. The first electrode 542 and the second
electrode 544 are disposed on the surface of the sound wave generator 54 and are electrically
connected to the signal device 52. Thereby, the sound generated by the sound wave generator 54
is reflected by the inner wall of the support 56, so that the acoustic function of the
thermoacoustic device 50 can be enhanced.
[0053]
Example 6 Referring to FIGS. 15 and 16, the thermoacoustic apparatus 60 of this example
includes a signal device 62, a sound wave generator 64, a support 56, two electrodes 642, a
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power amplifier 66, and the like. ,including. The configuration, characteristics, and functions of
the thermoacoustic apparatus 60 of the present embodiment are the same as those of the
thermoacoustic apparatus 10 of the first embodiment. The difference between the present
embodiment and the first embodiment is that the thermoacoustic apparatus 60 of the present
embodiment includes a power amplifier 66. The power amplifier 66 is electrically connected to
the signal device 62. Furthermore, the signal device 62 includes a signal output device (not
shown), and the signal output device is electrically connected to the signal device 62. The power
amplifier 66 can amplify the output of the signal from the signal unit 62 and transfer it to the
sound generator 64. The power amplifier 66 includes two outputs 664 and an input 662. The
input unit 662 is electrically connected to the signal device 62, and the output unit 664 is
electrically connected to the sound wave generator 64.
[0054]
Referring to FIG. 17, when providing the thermoacoustic device 60 with an alternating current,
the frequency of the output signal of the sound wave generator 64 may be twice as high as the
frequency of the input signal. The cause of this is that an alternating current flows through the
sound wave generator 64 to alternately heat the sound wave generator 64 with a positive current
and a negative current, so that double frequency temperature oscillation and double frequency
sound pressure are generated. Thus, when using a conventional power amplifier (e.g., a bipolar
amplifier), the output signal (human voice or music) sounds strange as it is twice as large as the
input signal.
[0055]
The power amplifier 66 can provide an amplified signal (e.g., a voltage signal) and a bias voltage
to the sound generator 64 to reduce the input signal. Referring to FIG. 16, the power amplifier
66 is a class A power amplifier, and includes a first resistor R1, a second resistor R2, a third
resistor R3, a capacitor, and a triode. The triode includes a base B, an emitter E, and a collector C.
The capacitor is connected to the signal output of the signal unit 62 and to the base B of the
triode. The ADC voltage Vcc and the first resistor R1 are connected to the base B of the triode.
The base B of the triode is connected to the second resistor R2. The emitter E is electrically
connected to one output 664 of the power amplifier 66. The DC voltage Vcc is electrically
connected to the other output 664 of the power amplifier 66. The collector C is connected to the
third register R3. The two outputs 664 of the power amplifier 66 are connected to the two
electrodes 642, respectively. The register R2 and the register R3 are grounded.
10-04-2019
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[0056]
A plurality of electrodes may be electrically connected to the sound wave generator 64. Adjacent
ones of the electrodes are connected to different ends 664 of the power amplifier 66. When the
electrodes are not installed, the two output parts 664 of the power amplifier 66 are electrically
connected to the sound wave generator 64 by conductive wires.
[0057]
Referring to FIG. 15, in order to reduce the frequency of the signal from the signal device 62, a
frequency reduction circuit 69 is provided. The frequency reduction circuit 69 can transfer the
signal to the power amplifier 66, for example, after reducing the signal frequency to half. The
power amplifier 66 is, for example, a conventional power amplifier and does not provide an
amplified voltage signal and a bias voltage to the sound wave generator 64. The frequency
reduction circuit 69 may be integrated with the power amplifier 66.
[0058]
With reference to FIGS. 18 and 19, the thermoacoustic apparatus 60 further includes a plurality
of sound wave generators 64 and a calibration device 68. The calibrator 68 is connected to the
input 662 or the output 664 of the power amplifier 66. Referring to FIG. 18, when the calibrator
68 is connected to the output 664 of the power amplifier 66, the calibrator 68 divides the
amplified signal from the power amplifier 66 into sub-signals of a plurality of frequency bands.
The sub-signals are transferred to the plurality of sound wave generators 64 respectively.
Referring to FIG. 19, when the calibrator 68 is connected to the input 662 of the power amplifier
66, the thermoacoustic device 60 includes a plurality of power amplifiers 66. The calibrator 68
recognizes the signals from the signal unit 62 into sub-signals of a plurality of frequency bands
and transfers the sub-signals to the plurality of power amplifiers 66, respectively. Each power
amplifier 66 corresponds to one sound generator 64.
[0059]
Example 7 Referring to FIG. 20, the thermoacoustic device 70 of the present example includes an
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19
electromagnetic signal device 712, a sound wave generator 714, a support 716, and a modulator
718. The sound wave generator 714 is supported by the support 716. Alternatively, the sound
wave generator 714 having a freestanding structure can be installed without using the support
716. The electromagnetic signal device 712 is installed at a predetermined distance from the
sound wave generator 714 and transmits an electromagnetic signal 720. The modulation device
718 may be disposed between the electromagnetic signal device 712 and the sound wave
generator 714 to modulate the density and / or frequency of the electromagnetic signal 720
from the electromagnetic signal device 712. The electromagnetic signal 720 modulated by the
modulator 718 is transmitted to the sound generator 714. The sound wave generator 714 is in
contact with the surrounding medium.
[0060]
As in the first embodiment, the sound wave generator 714 of the present example has good
transparency and flexibility, so the sound wave generator 714 can be installed in another device.
The support 716 may be a display device, a mobile phone, a computer, a resonance box, a door, a
window, a screen, furniture, a textile, an aircraft, or the like.
[0061]
The sound wave generator 714 includes a carbon nanotube structure. The carbon nanotube
structure includes a plurality of carbon nanotube wires. The plurality of carbon nanotube wires
are arranged parallel to one another, or cross or interwoven or twisted. Referring to FIG. 21, the
carbon nanotube structure is formed by interweaving the carbon nanotube wire of FIG. 6 or FIG.
Of course, a carbon nanotube film and / or a carbon nanotube wire structure can also be used to
form the carbon nanotube structure of FIG. Since the thermoacoustic apparatus 70 transmits
signals using electromagnetic waves, it is not necessary to install an electrode on the sound wave
generator 714.
[0062]
The support 716 may be the support 36 of Example 3 or the support 46 of Example 4. The
sound wave generator 714 may be mounted on the surface of the support 716. When the sound
wave generator 714 has a free standing structure, the sound wave generator 714 may be directly
installed, or the periphery of the sound wave generator 714 may be fixed to the frame and the
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other parts may be suspended. The area where the suspended portion of the sound wave
generator 714 contacts the surrounding medium is large. Referring to FIG. 22, the two carbon
nanotube films shown in FIG. 2 are adhered to the frame portion 722. The two carbon nanotube
films are adhered to cross at 90 °.
[0063]
The electromagnetic signal device 712 includes an electromagnetic signal generator (not shown).
The electromagnetic signal generator generates electromagnetic waves of different density and
frequency to produce the electromagnetic signal 720. The carbon nanotube structure may
receive the electromagnetic signal 720 to convert electromagnetic energy into thermal energy.
Since the heat capacity per unit area of the carbon nanotube structure is very low, the
temperature of the carbon nanotube structure rapidly changes with the reception of the
electromagnetic signal 720 under the same frequency condition, and the heat wave is peripheral.
Transmitted to the medium of Accordingly, by transmitting the electromagnetic signal 720, the
surrounding medium (eg, environmental air) can be heated at the same frequency, and the heat
wave can generate a pressure wave in the surrounding environment and generate an acoustic
wave. The thermoacoustic device 70 is operated by “light-heat-sound” conversion, so it is
largely different from a conventional speaker operated by mechanical vibration of a diaphragm.
The carbon nanotube can uniformly absorb all electromagnetic spectrum (eg, radio, far infrared,
near infrared, ultraviolet, X-ray, gamma ray, high energy gamma ray), so the electromagnetic
spectrum of the electromagnetic signal 720 is Includes radio, far infrared, near infrared,
ultraviolet, x-rays, gamma rays, high energy gamma rays. In the present embodiment, the
electromagnetic signal 720 is an optical signal, and the frequency of the optical signal is in the
range from the far infrared frequency to the ultraviolet frequency.
[0064]
The average power density of the electromagnetic signal 720 is 1 μW / mm <2> to 20 W / mm
<2>. If the average power density of the electromagnetic signal 720 is too low, the surrounding
media can not be heated. If the average power density of the electromagnetic signal 720 is too
high, the carbon nanotube structure may be damaged. In the present embodiment, the
electromagnetic signal generator is a pulse laser generator (for example, an infrared diode laser).
Furthermore, the electromagnetic device 70 comprises a focusing element (not shown), for
example a lens. The focusing element can reduce the average power density of the
electromagnetic signal 720 by focusing the electromagnetic signal 720 generated by the sound
wave generator 714.
10-04-2019
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[0065]
The sound wave generator 714 may transmit the electromagnetic signal 720 to the sound wave
generator 714 at any angle. In this embodiment, the traveling direction of the electromagnetic
signal 720 is perpendicular to the surface of the carbon nanotube structure. The distance
between the electromagnetic signal generator and the sound generator 714 may be set so that
the sound generator 714 can successfully receive the electromagnetic signal 720.
[0066]
The modulator 718 is disposed in the transmission path of the electromagnetic signal 720.
Furthermore, the modulation device 718 includes a density modulation element (not shown) and
/ or a frequency modulation element (not shown). The modulator 718 modulates the density and
/ or frequency of the electromagnetic signal 720 to generate a sound wave. An on / off control
circuit can be installed in the modulator 718 to control the state of the electromagnetic signal
720. In the present embodiment, the modulation device 718 directly modulates the density of the
electromagnetic signal 720. The modulator 718 and the electromagnetic signal device may be
integrated or spaced apart by a predetermined distance. In the present embodiment, the
modulator 718 is an electro-optic crystal. If the electromagnetic signal 720 is a fluctuating signal
(e.g., a pulse laser), the modulator 718 can be selectively installed.
[0067]
In the present embodiment, the density of sound waves generated from the thermoacoustic
device 70 is 50 dB SPL. When the input power is 4.5 W, the range of the frequency response of
the thermoacoustic device 70 is 1 Hz to 100 KHz. In this case, the sound wave generated by the
thermoacoustic device 70 can reach about 70 dB.
[0068]
Referring to FIG. 23, the carbon nanotube film of Example 1 is irradiated using one pulsed
femtosecond laser signal. In this case, the wavelength of the femtosecond laser signal is 800 nm.
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22
Referring to FIG. 23, after receiving the femtosecond laser signal, the carbon nanotube film
generates a sound pressure signal. The width of the sound pressure signal is 10 μm to 20 μm.
When the width of the laser signal is 20 μm or more, the width of the sound pressure signal
increases as the width of the laser signal increases. When the carbon nanotube film is irradiated
with a laser having a width of 100 μm, the carbon nanotube film may generate a sound pressure
signal having a width of 100 μm. Referring to FIGS. 24 to 27, sound pressure signals generated
by the carbon nanotube film are measured by irradiating the carbon nanotube structure using
lasers having different wavelengths. The lasers used in FIGS. 24 to 27 are ultraviolet light with a
wavelength of 355 nm, visible light with a wavelength of 532 nm, infrared light with a
wavelength of 1.06 μm, and far infrared light with a wavelength of 10.6. Referring to FIGS. 24 to
27, it can be seen that the sound pressure generated from the carbon nanotube film increases as
the output power of the laser increases.
[0069]
Eighth Embodiment Referring to FIG. 28, the thermoacoustic apparatus 80 of the present
embodiment has the following differences as compared with the seventh embodiment. The
thermoacoustic device 80 of the present embodiment includes an electromagnetic signal device
812, a sound wave generator 814, a frame portion 816, and a modulation device 818. The frame
816 supports the sound wave generator 814 by two bars. Thereby, a part of the sound wave
generator 814 is suspended. The electromagnetic signal device 812 may be spaced apart from
the sound wave generator 814 at a predetermined distance to generate an electromagnetic signal
820.
[0070]
The thermoacoustic device 80 further includes a sound collector 822. The sound collector 822 is
installed on the opposite side of the sound wave generator 814 opposite to the side facing the
electromagnetic signal device 812 so as to be separated from the sound wave generator 814 by a
predetermined distance. Thus, a sound collecting space is formed between the sound wave
generator 814 and the sound collector 822. The sound collector 822 may have a flat or curved
surface. The sound collection space 824 can be used to enhance the sound quality of the
thermoacoustic device 80. Depending on the size of the sound wave generator 814, the distance
between the sound collector 822 and the sound wave generator 814 is set to 1 cm to 1 m.
[0071]
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23
Ninth Embodiment Referring to FIG. 29, the thermoacoustic apparatus 90 of the present
embodiment is different from the eighth embodiment in the following points. The thermoacoustic
apparatus 90 of the present embodiment includes an electromagnetic signal apparatus 912, a
sound wave generator 914, a frame 916, and a modulation apparatus 918. The electromagnetic
signal device 912 is spaced apart from the sound wave generator 914 at a predetermined
distance to generate an electromagnetic signal 920.
[0072]
As long as the sound collecting space 924 having the opening 926 can be formed by the frame
916 and the sound wave generator 914, the frame 916 can be provided in any shape. In the
present embodiment, the frame 916 has a shape such as an L shape or a U shape (refer to the
support 56 of the fifth embodiment). The sound wave generator 914 covers the opening 926 of
the frame 916 and forms a Helmholtz resonator with the frame 916. Since the sound waves
generated by the sound wave generator 914 are reflected by the side wall of the frame 916, the
sound quality of the thermoacoustic device 90 can be enhanced. Of course, the sound collecting
space 924 is an open space or a sealed space.
[0073]
Tenth Embodiment Referring to FIG. 30, the thermoacoustic apparatus 1000 of the present
embodiment has the following difference as compared with the seventh embodiment. The
thermoacoustic apparatus 1000 of the present embodiment includes an electromagnetic signal
apparatus 1012, a sound wave generator 1014, a support 1016, and a modulation apparatus
1018. The electromagnetic signal device 1012 further includes an optical fiber 1022. An
electromagnetic signal generator 1024 is installed at a predetermined distance from the sound
wave generator 104. An optical signal from the electromagnetic signal generator 1024 is
transmitted by the optical fiber 1022. The modulation device 1018 may be installed at one end
of the optical fiber or between both ends of the optical fiber. In the present embodiment, the
modulation device 1018 is installed near the sound wave generator 1014 so as to be connected
to one end of the optical fiber 1022. Furthermore, an electromagnetic reflection element can be
installed to transmit the electromagnetic signal 1020 along a predetermined traveling direction.
[0074]
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24
Eleventh Embodiment Referring to FIG. 31, the thermoacoustic apparatus 2000 of the present
embodiment has the following differences as compared with the seventh embodiment. The
thermoacoustic apparatus 2000 of the present embodiment includes an electromagnetic signal
apparatus 2012 and a sound wave generator 2014. The electromagnetic signal device 2012 is
installed to be separated from the sound wave generator 2014 at a predetermined distance to
generate an electromagnetic signal 2020. The electromagnetic signal device 2012 generates
signals having different densities and / or frequencies. In the present embodiment, the
electromagnetic signal device 2012 is a pulse laser generator that emits a pulse laser. Of course,
as in all the embodiments described above, the thermoacoustic apparatus 2000 of the present
embodiment includes a frame or / and a support for supporting the sound wave generator 2014.
[0075]
Example 12 Referring to FIGS. 32-33, the thermoacoustic apparatus 3000 of the present example
includes an electromagnetic signal apparatus 3012 and a sound wave generator 3014. The
electromagnetic signal unit 3012 generates an electromagnetic signal 3020. The electromagnetic
signal device 3012 generates signals having different densities and / or frequencies. Further, the
thermoacoustic apparatus 3000 includes a modulation circuit 3018. The modulation circuit
3018 is electrically connected to the electromagnetic signal device 3012 and can modulate the
density and frequency of the electromagnetic signal transmitted from the electromagnetic signal
device 3012 according to the input electric signal.
[0076]
By emitting light having different frequencies and / or densities, the sound generator 3014 can
generate sound. In the present embodiment, the electromagnetic signal device 3012 includes at
least one light emitting diode (not shown) that emits visible light. The light emitting diode has a
rated voltage of 3.4 V to 3.6 V, a rated current of 360 mA, a rated output of 1.1 W, and a
luminous efficiency of 1 m / W. There is no limitation on the number of light emitting diodes. As
one example, when 16 light emitting diodes are used, the thermoacoustic apparatus 3000 is
provided with a frame 3016 for supporting the sound wave generator 3014. The sound
generator 3014 may be in contact with the surface of the light emitting diode. Alternatively, the
electromagnetic signal device 3012 may be installed near the sound wave generator 3014
(separated by 1 cm).
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25
[0077]
In addition, the thermoacoustic device 3000 includes an electrical signal device 3040 electrically
connected to the modulation circuit 3018. The electrical signal device 3040 transmits an
electrical signal to the modulation circuit 3018. For example, if the electrical signal device 3040
is an MP3 player, the thermoacoustic device 3000 can reproduce the sound of the MP3 player.
[0078]
Example 13 Referring to FIG. 34, a sound transmission system 4000 is provided in this example.
The sound transmission system 4000 includes an sound-to-electric conversion device 4040, an
electro-wave conversion device 4030, a sound wave generator 4014, and a support 4016. The
sound-electric conversion device 4040 is electrically connected to the electric-wave conversion
device 4030. The electromagnetic wave conversion device 4030 is spaced apart from the sound
wave generator 4014 by a predetermined distance.
[0079]
The sound pressure can be converted into an electric signal by the sound-electric conversion
device 4040, and the electric signal can be output to the electric-wave conversion device 4030.
The electromagnetic wave conversion device 4030 transmits an electromagnetic signal according
to the electric signal output from the sound-to-electric conversion device 4040. The sound wave
generator 4014 includes a carbon nanotube structure. After transmitting the electromagnetic
signal to the carbon nanotube structure, the carbon nanotube structure may convert the
electromagnetic signal into heat. When the heat is transferred to the surrounding medium in
contact with the carbon nanotube structure, a thermoacoustic effect will occur. The sound-toelectric conversion device 4040 is a microphone or a pressure sensor. In the present
embodiment, the sound-to-electric conversion device 4040 is a microphone.
[0080]
Further, the electromagnetic wave conversion device 4030 includes an electromagnetic signal
device 4012 and a modulation device 4018. The electromagnetic signal device 4012 and the
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26
modulation device 4018 may be separated or integrated at a predetermined distance. The
electromagnetic signal unit 4012 generates an electromagnetic signal 4020. The modulator
4018 is connected to the sound-to-electric converter 4040 and can modulate the density or / and
the frequency of the electromagnetic signal 4020 transmitted from the electromagnetic signal
unit 4012.
[0081]
The electromagnetic signal device 4012, the sound wave generator 4014 and the support 4016
are similar to the electromagnetic signal device, the sound wave generator and the support (or
frame) in the above-mentioned embodiments, respectively. The sound transmission system 4000
further includes an optical fiber (not shown). The optical fiber is connected to the
electromagnetic wave conversion device 4030, and the electromagnetic signal 4020 is
transmitted to the carbon nanotube structure. In the present embodiment, the electromagnetic
signal device 4012 is a laser device including a pump source and a resonator.
[0082]
In one of the above embodiments, the thermoacoustic device may utilize a plurality of different
input devices. For example, in one such embodiment, the thermoacoustic device can
simultaneously include an electrical input device and an electromagnetic input device.
[0083]
Referring to FIG. 35, the method of generating an acoustic wave according to the present
invention includes a first step of providing a carbon nanotube structure, and transferring a signal
to the carbon nanotube structure to generate heat in the carbon nanotube structure. The method
includes two steps, a third step in which heat is radiated to the surrounding medium in contact
with the carbon nanotube structure, and a fourth step in which a thermoacoustic effect is
generated.
[0084]
In the first step, the carbon nanotube structure is the same as the carbon nanotube structure
used for the thermoacoustic device 10.
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27
In the second step, the signal is transferred to the signal device by at least two electrodes. In the
third and fourth steps, the heat generated in the carbon nanotube structure heats the
surrounding medium. Sound waves can be generated by repeatedly heating the surrounding
medium. The above is the thermoacoustic effect.
[0085]
DESCRIPTION OF SYMBOLS 10 thermoacoustic apparatus 100 speaker 102 voice coil 104
magnet 106 cone 12 signal apparatus 14 sound wave generator 142 1st electrode 143a carbon
nanotube film 143b carbon nanotube segment 144 2nd electrode 145 carbon nanotube 146
carbon nanotube wire 149 conductive wire 20 thermoacoustic apparatus Reference Signs List 22
signal device 24 sound wave generator 242 first electrode 244 second electrode 246 third
electrode 248 fourth electrode 249 first conductive wire 249 'second conductive wire 30
thermoacoustic device 32 signal device 34 sound wave generator 342 first electrode 344 Second
electrode 349 conductive wire 36 support 40 thermoacoustic device 42 signal device 44
acoustic wave generator 442 first electrode 444 second electrode 446 third electrode 448 fourth
electrode 449 conductive wire 50 thermoacoustic device 52 Signal device 54 Sound wave
generator 542 First electrode 544 Second electrode 549 Conductive wire 56 Support 562 First
end 564 Second end 60 Thermoacoustic device 62 Signal device 64 Sound wave generator 66
Power amplifier 662 Input part 664 Output part 69 Frequency reduction circuit 70
Thermoacoustic device 712 Electromagnetic signal device 714 Sound wave generator 716
Support 718 Modulating device 720 Electromagnetic signal 722 Frame 80 Thermoacoustic
device 812 Electromagnetic signal device 814 Sound wave generator 816 Frame 818 Modulation
device 820 Electromagnetic signal 822 Sound device 824 Sound collection space 90
Thermoacoustic device 912 Electromagnetic signal device 914 Sound wave generator 916 Frame
part 918 Modulation device 920 Electromagnetic signal 924 Sound collection space 926
Opening 1000 Thermoacoustic device 1012 Electromagnetic signal device 1014 Sound wave
generator 1016 Support 1018 Tuning device 1022 Optical fiber 1024 Electromagnetic signal
generator 1020 Electromagnetic signal 2000 Thermoacoustic device 2014 Electromagnetic
signal device 2014 Acoustic wave generator 2020 Electromagnetic signal 3000 Thermoacoustic
device 3012 Electromagnetic signal device 3014 Acoustic wave generator 3018 Modulation
circuit 3020 Electromagnetic signal 3040 Electric signal device 4000 Sound transmission system
4012 Electromagnetic signal device 4014 Sound wave generator 4016 Support 4018 Modulator
4030 Electro-wave conversion device 4040 Sound-to-electrical conversion device
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