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JP2009278498

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DESCRIPTION JP2009278498
An object of the present invention is to provide a flexible stereo speaker which can reproduce
stereo signals with less loss of stereo feeling. A flexible stereo speaker 1 extracts a left channel
input signal included in a diaphragm 11, a left channel electrode 12, a right channel electrode
13, a substrate 14, and an input stereo signal at a predetermined frequency interval. And the left
channel comb filter 21 generating the left channel drive signal and the amplitude characteristic
reverse to that of the left channel comb filter 21 and the right channel input signal included in
the input stereo signal is at a predetermined frequency interval. And a right channel comb filter
22 for extracting and generating a right channel drive signal. [Selected figure] Figure 1
フレキシブルステレオスピーカ
[0001]
The present invention relates to a flexible stereo speaker for stereo reproduction of an input
stereo signal.
[0002]
Conventionally, a flat panel speaker is known (see, for example, Patent Document 1).
In the panel speaker described in Patent Document 1, a drive unit (electrode) for the right
channel is provided on the right side of one diaphragm, and a drive unit (electrode) for the left
channel is provided on the left side. And the panel speaker described in patent document 1
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carries out the stereo reproduction | regeneration of a stereo signal, when the drive part
(electrode) of the both ends on either side drives based on the left channel and right channel of a
stereo signal, respectively.
[0003]
In recent years, flat flexible loudspeakers have attracted attention. Flexible speakers are thin and
light, so they are easy to carry and flexible, so their installation is highly flexible. For example, a
flexible speaker can be installed in a place where it is difficult for a conventional speaker, such as
being attached to an indoor wall or a display, and space efficiency is excellent. Here, since the
flexible speaker is basically a mechanism in which one diaphragm vibrates to generate sound, it
does not correspond to a stereo signal, and a monaural signal is input and reproduced in
monaural. Is common. JP 2004-343481 A
[0004]
However, as for currently available audio contents (for example, music programs and music CDs),
stereo signals (stereo format) of two channels including the left channel input signal and the
right channel input signal are mainstream. As described above, since the flexible speaker does
not correspond to the stereo signal, there is a problem that the main stream audio content can
not be reproduced in stereo without losing the sense of stereo. In addition, as the practical use of
flexible speakers progresses, there is a strong demand for stereo reproduction of stereo signals
without losing the sense of stereo.
[0005]
Further, in the configuration in which the drive parts are provided at the left and right ends of
the diaphragm, starting with the panel speaker described in Patent Document 1, the vibration
wave by the left channel input signal and the vibration wave by the right channel input signal are
mixed, etc. There is a problem that a correlation occurs between the left channel and the right
channel and the sense of stereo is lost.
[0006]
Then, an object of the present invention is to provide a flexible stereo speaker which is less likely
to lose stereo feeling and can reproduce stereo signals in stereo.
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[0007]
In order to solve the problems described above, a flexible stereo speaker according to claim 1 is a
flexible stereo speaker that receives a stereo signal including a left channel input signal and a
right channel input signal and reproduces a stereo signal in stereo. Filter, a right channel comb
filter having an amplitude characteristic opposite to that of the left channel comb filter, a flat
diaphragm made of an electric field driven polymer vibrating in response to an electric field, and
the diaphragm facing each other on both sides Pair of right channel electrodes formed to be
parallel to each other, a pair of right channel electrodes formed to be opposite to each other on
both sides of the diaphragm and adjacent to the left channel electrode, and one side of the
diaphragm And a substrate closely attached to the left channel electrode and the right channel
electrode on the side of.
[0008]
In such a configuration, the flexible stereo speaker extracts the left channel input signal at a
predetermined frequency interval and generates the left channel drive signal by the left channel
comb filter.
Here, the left channel comb filter generates the left channel drive signal by extracting the left
channel input signal at fine frequency intervals so that human hearing hardly feel the difference
from the original left channel input signal. Do.
[0009]
In addition, the flexible stereo speaker extracts the right channel input signal at a predetermined
frequency interval by the right channel comb filter, and generates the right channel drive signal.
Here, the right channel comb filter generates the right channel drive signal by extracting the
right channel input signal at fine frequency intervals so that human hearing hardly feel the
difference from the original right channel input signal. Do.
Furthermore, since the right channel comb filter has an amplitude characteristic opposite to that
of the left channel comb filter, it generates a right channel drive signal that is less correlated with
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the left channel drive signal.
[0010]
Also, the flexible stereo speaker generates an electric field to vibrate the diaphragm based on the
left channel drive signal generated by the left channel comb filter by the left channel electrode.
The flexible stereo speaker generates an electric field to vibrate the diaphragm based on the right
channel drive signal generated by the right channel comb filter by the right channel electrode.
Furthermore, the flexible stereo speaker holds the diaphragm or excites the vibration of the
diaphragm by the substrate. As a result, the flexible stereo speakers perform stereo reproduction
based on the left channel drive signal and the right channel drive signal which have little
correlation with each other and hardly sense a difference from the original stereo signal in
human hearing. Can.
[0011]
Further, in order to solve the above-mentioned problems, a flexible stereo speaker according to
claim 2 is a flexible stereo speaker to which a stereo signal including a left channel input signal
and a right channel input signal is input and which reproduces a stereo signal in stereo. A
channel drive signal generation means, a right channel drive signal generation means, a flat
diaphragm made of an electric field drive type polymer vibrating according to an electric field,
and the left channel so as to face each other on both sides of the diaphragm A pair of left channel
electrodes formed at positions adjacent to the electrodes, a pair of right channel electrodes
formed to face each other on both sides of the diaphragm, and a left channel electrode on the one
side of the diaphragm and the right And a substrate closely attached to the channel electrode.
[0012]
In this configuration, the flexible stereo speaker multiplies the left channel input signal from the
left channel input signal by the left channel drive signal generation unit, subtracts the right
channel input signal in reverse phase by multiplying the left channel drive signal, Generate
Further, the flexible stereo speaker generates a right channel drive signal by subtracting the left
channel input signal in antiphase from the right channel input signal by multiplying the transfer
coefficient by the right channel drive signal generation means. By using the transfer coefficient in
this manner, the flexible stereo speaker generates a left channel drive signal and a right channel
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drive signal that are less correlated with each other.
[0013]
In addition, the flexible stereo speaker generates an electric field to vibrate the diaphragm based
on the left channel drive signal generated by the left channel drive signal generation unit by the
left channel electrode. The flexible stereo speaker generates an electric field to vibrate the
diaphragm based on the right channel drive signal generated by the right channel drive signal
generation unit by the right channel electrode. Furthermore, the flexible stereo speaker holds the
diaphragm or excites the vibration of the diaphragm by the substrate. Thereby, the flexible stereo
speaker can perform stereo reproduction based on the left channel drive signal and the right
channel drive signal which are less correlated with each other.
[0014]
Furthermore, in order to solve the above-mentioned problems, a flexible stereo speaker
according to claim 3 is a flexible stereo speaker that receives a stereo signal including a left
channel input signal and a right channel input signal and reproduces a stereo signal in stereo.
Addition means, a low pass filter, a flat diaphragm made of an electric field drive type polymer
vibrating according to an electric field, a pair of left channel electrodes formed to face each other
on both sides of the diaphragm, and vibration A pair of bass channel electrodes formed on both
sides of the plate so as to face each other and adjacent to the left channel electrode, and so as to
face each other on both sides of the diaphragm and adjacent to the bass channel electrode A pair
of right channel electrodes formed at the same position, a left channel electrode on one side of
the diaphragm and a bass A plate contacting the right channel electrodes and, was configured
with a.
[0015]
In such a configuration, the flexible stereo speaker outputs the left channel input signal as the
left channel drive signal and the right channel input signal as the right channel drive signal by
the signal adding means, and the left channel input signal and the right channel input signal. And
add.
[0016]
Further, the flexible stereo speaker generates a bass channel drive signal by extracting a bass
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region of the left channel input signal and the right channel input signal added by the signal
addition means by a low pass filter.
By this, the flexible stereo speaker generates a bass drive signal in which only a bass region that
is difficult to reproduce by vibration with small amplitude is extracted from the stereo signal.
[0017]
Further, the flexible stereo speaker generates an electric field to vibrate the diaphragm by the left
channel electrode based on the left channel drive signal outputted by the signal addition means.
The flexible stereo speaker vibrates the diaphragm by generating an electric field based on the
right channel drive signal output from the signal addition means by the right channel electrode.
As a result, the flexible stereo speaker reproduces in stereo the sound including the high-tone
area and the low-pitch area that easily affect the localization (sound sense) of the sound in the
left and right parts of the diaphragm separated from each other.
[0018]
In addition, the flexible stereo speaker generates an electric field to vibrate the diaphragm based
on the bass channel drive signal generated by the low pass filter using the bass channel
electrode. Then, the flexible stereo speaker holds the diaphragm or vibrates the vibration of the
diaphragm by the substrate. By this, the flexible stereo speaker has a small influence on the
localization of the sound, and in addition to the left and right portions of the diaphragm, the bass
region sound which is difficult to reproduce by the vibration with small amplitude is also
reproduced at the center portion of the diaphragm. .
[0019]
Further, in the flexible stereo speaker according to claim 3, the signal adding means extracts a
left channel input signal at a predetermined frequency interval to generate a left channel drive
signal, and a left channel comb filter And a right channel comb filter for extracting a right
channel input signal at a predetermined frequency interval to generate a right channel drive
signal.
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[0020]
In such a configuration, the flexible stereo speaker generates a left channel drive signal and a
right channel drive signal that are less correlated with each other.
[0021]
Further, in the flexible stereo speaker according to claim 3, the signal addition means removes
the signal for the bass channel (bass region) from the right channel input signal which has a
reverse phase by multiplying a preset transfer coefficient, and outputs it. And a left channel drive
signal generating means for generating a left channel drive signal by subtracting the signal
output from the first high pass filter from the left channel input signal; A second high pass filter
that removes and outputs a bass channel signal (bass region) from the left channel input signal
and a signal output by the second high pass filter from the right channel input signal and outputs
a right channel drive signal A right channel drive signal generation unit for generating the right
channel drive signal.
[0022]
In such a configuration, the flexible stereo speaker generates a left channel drive signal and a
right channel drive signal that are less correlated with each other.
[0023]
The flexible stereo speaker according to the present invention has the following excellent effects.
According to the invention of claim 1, since stereo reproduction is performed based on the left
channel drive signal and the right channel drive signal which are less correlated with each other,
the separation of the signal sound between the left and right channels becomes clear, and the
sense of stereo is impaired. It becomes difficult.
[0024]
According to the second aspect of the invention, the interference of the vibration wave to the
right channel by the left channel drive signal and the interference of the vibration wave to the
left channel by the right channel drive signal are reduced, and the stereo feeling is less likely to
be impaired.
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[0025]
According to the third aspect of the present invention, since the sound including the high-tone
area that easily affects the localization of the sound is reproduced in stereo at the left and right
portions of the diaphragms separated from each other, the stereo feeling is less likely to be lost.
Further, according to the invention of claim 3, the central portion of the diaphragm is added to
the left and right portions of the diaphragm with the sound of the bass region having little
influence on the localization of the sound and the reproduction of the stereo feeling being
difficult. However, since it reproduces, it is possible to give the listener a feeling of bass which is
often lacking in conventional flexible speakers and panel speakers.
[0026]
According to the invention of claims 4 and 5, since the left channel drive signal and the right
channel drive signal having a small correlation with each other are generated, the stereo feeling
is less likely to be impaired.
[0027]
Hereinafter, embodiments of the present invention will be described in detail with reference to
the drawings.
In each embodiment, the same means and the same members are denoted by the same reference
numerals, and the description thereof is omitted.
[0028]
First Embodiment [Configuration of Flexible Stereo Speaker] The configuration of a flexible stereo
speaker according to a first embodiment of the present invention will be described with reference
to FIGS.
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FIG. 1 is a schematic configuration diagram of a flexible stereo speaker according to a first
embodiment of the present invention.
FIG. 2 is a side view of the flexible stereo speaker of FIG.
[0029]
In FIG. 1, the left channel electrode 12 b (12) and the right channel electrode 13 b (13) formed
on the lower surface of the diaphragm 11 are not shown.
Further, in FIG. 1, the left channel input signal included in the input stereo signal is Lch, and the
right channel input signal of the stereo signal is Rch. Moreover, in FIG. 2, the control means 20
and the conducting wire 15 were abbreviate | omitted.
[0030]
The flexible stereo speaker 1 receives a stereo signal including a left channel input signal and a
right channel input signal, and reproduces a stereo signal in stereo. The flexible stereo speaker 1
of FIG. 1 includes a diaphragm 11, a left channel electrode 12a (12), a right channel electrode
13a (13), a substrate 14, four conducting wires 15a to 15d (15), and a control means. And 20.
[0031]
The diaphragm 11 vibrates according to an electric field, that is, is a flat plate made of an electric
field driven polymer having a piezoelectric effect. For example, the diaphragm 11 can be formed
of polyvinylidene fluoride (PVDF), or an electric field driven elastomer in which an electrode is
formed on an acrylic elastomer, a silicone elastomer, a urethane elastomer, or the like. Further,
when the diaphragm 11 is made of polyvinylidene fluoride, as shown in FIG. 2, the thickness of
the diaphragm 11 is, for example, 80 μm.
[0032]
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The left channel electrode 12 is formed on both sides of the diaphragm 11 so as to face each
other, and based on a left channel drive signal generated by a left channel comb filter 21
described later, the left channel electrode 12 a and the left channel electrode 12 b are An electric
field is generated between them to vibrate the diaphragm 11. Hereinafter, the left channel
electrodes 12a and 12b are simply referred to as the left channel electrode 12 when the
description is made without distinction.
[0033]
Here, for the left channel electrode 12, an electrode made of, for example, indium tin oxide (ITO),
aluminum or the like is formed on the substantially left half of the diaphragm 11 by a sputtering
method. Here, as shown in FIG. 1, the shape of the left channel electrode 12 is a rounded square,
but this shape is not particularly limited, and may be a square, a rectangle, a circle or an ellipse.
[0034]
As shown in FIG. 2, the left channel electrode 12 a is formed on the upper surface 11 a of the
diaphragm 11. Also, the left channel electrode 12 b is formed on the lower surface 11 b of the
diaphragm 11 so as to face the left channel electrode 12 a. The left channel electrode 12a is
connected to the left channel comb filter 21 via the conducting wire 15a, and the left channel
electrode 12b is connected to the left channel comb filter 21 via the conducting wire 15b.
[0035]
The right channel electrode 13 is formed on the both sides of the diaphragm 11 so as to face
each other and at a position adjacent to the left channel electrode 12, based on the right channel
drive signal generated by the right channel comb filter 22 described later. An electric field is
generated between the right channel electrode 13a and the right channel electrode 13b to
vibrate the diaphragm 11. Hereinafter, the right channel electrodes 13a and 13b will be simply
referred to as the right channel electrode 13 when the description is made without distinction.
[0036]
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Further, the right channel electrode 13 is formed on the substantially right half of the diaphragm
11 with, for example, the same shape and material as the left channel electrode 12. Here, as
shown in FIG. 2, the right channel electrode 13 a is formed on the upper surface 11 a of the
diaphragm 11. The right channel electrode 13 b is formed on the lower surface 11 b of the
diaphragm 11 so as to face the right channel electrode 13 a. The right channel electrode 13a is
connected to the right channel comb filter 22 via the conducting wire 15c, and the right channel
electrode 13b is connected to the right channel comb filter 22 via the conducting wire 15d. In
order to secure the area of the diaphragm 11 while making it difficult to impair the stereo
feeling, the distance between the left channel electrode 12 and the right channel electrode 13 is
preferably, for example, 5 mm or more and 20 mm or less.
[0037]
The substrate 14 is a diaphragm which is vibrated by the diaphragm 11 in order to maintain the
strength of the flexible stereo speaker 1 and is, for example, a film of polyethersulfone (PES),
polycarbonate or polyethylene terephthalate (PET). As shown in FIG. 2, the substrate 14 is
formed of, for example, an adhesive or a double-sided tape on the left channel electrode 12b and
the right channel electrode 13b on one side of the diaphragm 11 (here, the lower surface 11b of
the diaphragm 11). to paste together. When the substrate 14 is made of polyether sulfone, the
thickness of the substrate 14 is, for example, 200 μm.
[0038]
The conductors 15 a and 15 b transmit the left channel drive signal generated by the left channel
comb filter 21 to the left channel electrode 12. The conductors 15 c and 15 d transmit the right
channel drive signal generated by the right channel comb filter 22 to the right channel electrode
13. Hereinafter, when demonstrating without distinguishing lead wires 15a-15d, it only describes
as lead wire 15. For example, as the conducting wire 15, a metal wire such as a copper wire or an
aluminum wire can be used.
[0039]
The control means 20 receives a stereo signal including a left channel input signal and a right
channel input signal, and as shown in FIG. 1, a left channel comb filter 21 and a right channel
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comb filter 22; Equipped with Here, an example is shown in which the left channel input signal
and the right channel input signal are separately input, but the control means 20 separates the
left channel input signal and the right channel input signal from the input stereo signal. A circuit
may be provided (not shown). Furthermore, the control unit 20 may include an amplification
circuit (not shown) that amplifies the left channel drive signal and the right channel drive signal.
[0040]
Although the left channel electrode 12 and the right channel electrode 13 are provided on one
diaphragm 11 in FIG. 2, the number of the diaphragms 11 is not limited to one. For example, two
diaphragms 11 with a slightly larger area than the left channel electrode 12 and the right
channel electrode 13 are prepared, and the left channel electrodes 12 are formed on both sides
of one diaphragm 11. Channel electrodes 13 are formed (not shown). Then, the two diaphragms
11 are attached to the substrate 14.
[0041]
The left channel comb filter and the right channel comb filter of FIG. 1 will be described below
with reference to FIG. 3 (see FIG. 1 as needed). FIG. 3 is a graph showing the characteristics of
the left channel comb filter and the right channel comb filter of FIG. 1, (a) is a graph showing the
characteristics of the left channel comb filter, (b) is a graph showing the right It is a graph which
shows the characteristic of a channel comb filter.
[0042]
The left channel comb filter 21 generates a left channel drive signal by extracting the left channel
input signal contained in the input stereo signal at a predetermined frequency interval (for
example, 1/30 octave band interval). . As shown in FIG. 3A, the left channel comb filter 21 sets
the left channel input signal at a predetermined frequency interval, for example, a reference
value of -20 dB, and the band to be amplified becomes 0 dB at maximum, Perform signal
processing to achieve a minimum of -40 dB. In this manner, the left channel comb filter 21
generates a left channel drive signal that hardly senses a difference from the left channel input
signal included in the input stereo signal in human auditory sense.
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[0043]
For example, assuming that the left channel input signal is l (t), the characteristic of the left
channel comb filter 21 is H (z), and the left channel drive signal is L (t), the left channel comb
filter 21 The left channel drive signal is generated using equation (1). L (t) = l (t) × H (z) formula
(1)
[0044]
The left channel comb filter 21 outputs the generated left channel drive signal to the left channel
electrode 12. Then, based on the left channel drive signal, an electric field is generated between
the left channel electrode 12a and the left channel electrode 12b, and the diaphragm 11 is
vibrated by the electric field and a sound corresponding to the left channel drive signal is
generated. .
[0045]
The right channel comb filter 22 has an amplitude characteristic opposite to that of the left
channel comb filter 21 and extracts the right channel input signal contained in the input stereo
signal at a predetermined frequency interval to obtain a right channel drive signal, It is
generated. Here, as shown in FIG. 3B, the right channel comb filter 22 has an amplitude
characteristic opposite to that of the left channel comb filter 21 at the same frequency interval as
the left channel comb filter 21. That is, when the amplitude of the left channel comb filter 21 in
FIG. 3A is a peak, the amplitude of the right channel comb filter 22 in FIG. 3B is a valley, and the
left channel comb in FIG. When the amplitude of the pattern filter 21 is a valley, the amplitude of
the right channel comb filter 22 in FIG. 3B is a peak.
[0046]
Further, as shown in FIG. 3B, the right channel comb filter 22 is a portion having a small
correlation with the left channel drive signal, specifically, the right channel input signal at a
predetermined frequency interval, for example, a reference value Is set to −20 dB, and signal
processing is performed such that the band to be amplified becomes 0 dB at maximum and the
band to be suppressed becomes −40 dB at minimum. In this manner, the right channel drive
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signal having little correlation with the right channel comb filter 22 and the left channel drive
signal, and having almost no difference with the right channel input signal included in the input
stereo signal, is detected by human hearing. Generate
[0047]
For example, assuming that the right channel input signal is r (t), the characteristic of the right
channel comb filter 22 is G (z), and the right channel drive signal is R (t), the right channel comb
filter 22 The right channel drive signal is generated using equation (2). Note that G (z) exhibits
the amplitude characteristic opposite to that of H (z) described above. R (t) = r (t) × G (z) (2)
[0048]
Further, the right channel comb filter 22 outputs the generated right channel drive signal to the
right channel electrode 13. Then, based on the right channel drive signal, an electric field is
generated between the right channel electrode 13a and the right channel electrode 13b, and the
diaphragm 11 is vibrated by the electric field, and a sound corresponding to the right channel
drive signal is generated. .
[0049]
As described above, since the flexible stereo speaker 1 uses a comb filter which is less necessary
for a general stereo speaker including two speakers, the separation of the signal sound between
the left and right channels becomes clear, and a sense of stereo feeling is realized. Is less likely to
be lost.
[0050]
Second Embodiment [Configuration of Flexible Stereo Speaker] The configuration of a flexible
stereo speaker according to a second embodiment of the present invention will be described with
reference to FIG.
FIG. 4 is a schematic configuration diagram of a flexible stereo speaker according to a second
embodiment of the present invention.
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[0051]
In FIG. 4, the left channel electrode 12 b (12) and the right channel electrode 13 b (13) formed
on the lower surface of the diaphragm 11 are not shown. Further, in FIG. 4, the left channel input
signal included in the input stereo signal is Lch, and the right channel input signal of the stereo
signal is Rch.
[0052]
The flexible stereo speaker 1B of FIG. 4 includes a diaphragm 11, a pair of left channel electrodes
12a (12), a pair of right channel electrodes 13a (13), a substrate 14, and four conducting wires
15a to 15d ( 15) and control means 30.
[0053]
Here, in the flexible stereo speaker 1B, the diaphragm 11, the left channel electrode 12, the right
channel electrode 13, the substrate 14 and the lead 15 are the same as the flexible stereo
speaker 1 of FIG. Do.
[0054]
The control means 30 receives a stereo signal including a left channel input signal and a right
channel input signal, and as shown in FIG. 4, the left channel drive signal generation means 31
and the right channel drive signal generation means 32. And.
[0055]
The left channel drive signal generating means 31 multiplies the left channel input signal
contained in the input stereo signal by a preset transfer coefficient to subtract the right channel
input signal in reverse phase to obtain the left channel drive signal, It is generated.
[0056]
Here, for example, the transfer coefficient is α (for example, amplitude 0.5 times, time delay
0.0001 sec), the left channel input signal is l (t), the left channel drive signal is L (t), and the right
channel When the input signal is r (t), the left channel drive signal generating means 31
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generates a left channel drive signal using the following equation (3).
L (t) = 1 (t)-alpha r (t) formula (3) However, in formula (3), 0 <alpha <1 is satisfied.
[0057]
Further, the left channel drive signal generating means 31 outputs the generated left channel
drive signal to the left channel electrode 12.
Then, based on the left channel drive signal, an electric field is generated between the left
channel electrode 12a and the left channel electrode 12b, and the diaphragm 11 is vibrated by
the electric field and a sound corresponding to the left channel drive signal is generated. .
[0058]
The right channel drive signal generation means 32 generates a right channel drive signal by
subtracting the left channel input signal in antiphase from the right channel input signal
contained in the input stereo signal by multiplying the transfer coefficient. is there.
[0059]
Here, when the transfer coefficient is α, the left channel input signal is l (t), the right channel
input signal is r (t), and the right channel drive signal is R (t), the right channel drive signal
generation unit 32 Generates a right channel drive signal using the following equation (4).
R (t) = r (t) −α · l (t) equation (4) where 0 <α <1 is satisfied in equation (4).
[0060]
Further, the right channel drive signal generating means 32 outputs the generated right channel
drive signal to the right channel electrode 13.
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Then, based on the right channel drive signal, an electric field is generated between the right
channel electrode 13a and the right channel electrode 13b, and the diaphragm 11 is vibrated by
the electric field, and a sound corresponding to the right channel drive signal is generated. .
[0061]
As described above, by multiplying the input stereo signal by the transfer coefficient, the flexible
stereo speaker 1B causes interference of the vibration wave by the left channel drive signal to the
right channel, and to the left channel of the vibration wave by the right channel drive signal.
Interference is reduced and stereo feeling is less likely to be impaired.
[0062]
Third Embodiment [Configuration of Flexible Stereo Speaker] The configuration of a flexible
stereo speaker according to a third embodiment of the present invention will be described with
reference to FIGS.
FIG. 5 is a schematic configuration diagram of a flexible stereo speaker according to a third
embodiment of the present invention.
6 is a side view of the flexible stereo speaker of FIG.
[0063]
In FIG. 5, the left channel electrode 12b formed on the lower surface 11b of the diaphragm 11,
the right channel electrode 13b, and the bass channel electrode 16b are not shown. Further, in
FIG. 5, the left channel input signal included in the input stereo signal is Lch, and the right
channel input signal of the stereo signal is Rch. Moreover, in FIG. 6, the control means 40 and the
conducting wire 15 were abbreviate | omitted.
[0064]
As shown in FIG. 5, a flexible stereo speaker 1C includes a diaphragm 11, a pair of left channel
electrodes 12a (12), a pair of right channel electrodes 13a (13), a substrate 14, and six
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conducting wires. 15a-15f (15), a pair of bass channel electrodes 16a (16), and a control means
40.
[0065]
Here, in the flexible stereo speaker 1C, the diaphragm 11 and the substrate 14 are the same as
the flexible stereo speaker 1 of FIG.
[0066]
The left channel electrode 12 is formed, for example, on the left side of the diaphragm 11 so as
to open the central portion of the diaphragm 11.
The right channel electrode 13 is formed at a position adjacent to the bass channel electrode 16
described later, for example, formed on the right side of the diaphragm 11 so as to open the
central portion of the diaphragm 11.
[0067]
The bass channel electrode 16 generates an electric field between the bass channel electrode 16a
and the bass channel electrode 16b to vibrate the diaphragm 11 based on a bass channel drive
signal generated by a low pass filter 42 described later.
Hereinafter, in the case where the bass channel electrodes 16a and 16b are described without
distinction, they are simply referred to as the bass channel electrode 16.
[0068]
Further, the bass channel electrodes 16 are formed at positions adjacent to the left channel
electrode 12, for example, at the central portion of the diaphragm 11 so as to face each other on
both sides of the diaphragm 11. Furthermore, the bass channel electrode 16 is formed, for
example, with the same shape and material as the left channel electrode 12.
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[0069]
Here, as shown in FIG. 6, the bass channel electrode 16a is formed at the central portion of the
upper surface 11a of the diaphragm 11, that is, between the left channel electrode 12a and the
right channel electrode 13a. Further, the right channel electrode 13 b is formed at the central
portion of the lower surface 11 b of the diaphragm 11, that is, between the left channel electrode
12 b and the right channel electrode 13 b.
[0070]
Here, the signal addition means 41 to be described later is connected to the left channel
electrode 12a via the conducting wire 15a, and is connected to the left channel electrode 12b via
the conducting wire 15b. Further, the signal adding means 41 is connected to the right channel
electrode 13a via the conducting wire 15e, and is connected to the left channel electrode 12d via
the conducting wire 15f. Further, a low pass filter 42 described later is connected to the bass
channel electrode 16a through the conducting wire 15c, and is connected to the bass channel
electrode 16b through the conducting wire 15d. In order to make it difficult to impair the sense
of stereo, it is preferable that the bass channel electrode 16 sets the distance between the left
channel electrode 12 and the right channel electrode 13 to, for example, 5 mm or more and 20
mm or less.
[0071]
The control means 40 receives a stereo signal including a left channel input signal and a right
channel input signal, and includes a signal adding means 41 and a low pass filter 42 as shown in
FIG.
[0072]
The signal addition means 41 outputs the left channel input signal included in the input stereo
signal as a left channel drive signal, and outputs the right channel input signal included in the
input stereo signal as a right channel drive signal. .
The signal addition means 41 adds the left channel input signal and the right channel input
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signal and outputs the result to the low pass filter 42.
[0073]
Although the signal adding means 41 is configured to output the input left channel input signal
and right channel input signal as it is, the signal adding means 41 includes the left channel comb
filter 21 and the right channel comb filter 22 of FIG. Also good (not shown). In this case, the
signal adding means 41 extracts the left channel input signal and the right channel input signal
at predetermined frequency intervals, and generates and outputs the left channel drive signal and
the left channel drive signal.
[0074]
The signal addition means 41 may include the left channel drive signal generation means 31 and
the right channel drive signal generation means 32 of FIG. 4 (not shown). In this case, the signal
addition means 41 multiplies the transmission coefficient by the first high-pass filter that
removes and outputs the bass channel signal from the right channel input signal that is in
reverse phase by multiplying the transfer coefficient, and is reversed in phase And a second high
pass filter for removing the bass channel signal from the left channel input signal (not shown).
Then, the signal addition means 41 subtracts the signal outputted by the first high pass filter
from the left channel input signal by the left channel drive signal generation means to generate a
left channel drive signal, and the right channel drive signal generation means The signal output
from the second high pass filter is subtracted from the right channel input signal to generate a
right channel drive signal.
[0075]
The low pass filter 42 extracts a bass region of the left channel input signal and the right channel
input signal added by the signal adding means 41 to generate a bass channel drive signal. Here,
as shown in FIG. 7, the low pass filter 42 extracts a frequency (bass region) equal to or lower
than a reference value (for example, 200 Hz) from a signal obtained by adding the left channel
input signal and the right channel input signal. The frequencies above the value are cut to
generate a bass channel drive signal.
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[0076]
The low pass filter 42 also outputs the generated bass channel drive signal to the bass channel
electrode 16. Then, an electric field is generated between the bass channel electrode 16a and the
bass channel electrode 16b based on the bass channel drive signal, and the diaphragm 11 is
vibrated by the electric field and a sound (bass) according to the bass channel drive signal
Occurs.
[0077]
As described above, since the flexible stereo speaker 1C is formed by separating the left channel
electrode 12 and the right channel electrode 13 so as to leave the central portion of the
diaphragm 11 apart, it includes a treble area that easily affects the localization of sound. The
sound is reproduced in stereo at the left and right portions of the diaphragm 11, and the stereo
feeling is less likely to be lost. In addition, since the flexible stereo speaker 1C has the bass
channel electrode 16 formed at the central portion of the diaphragm 11, the sound of the bass
region where the influence on the localization of the sound is small and the reproduction of the
stereo feeling is difficult is In addition to the left and right parts, the center part of the diaphragm
can be reproduced to give the listener a bass feeling.
[0078]
Although the left channel electrode 12, the bass channel electrode 16, and the right channel
electrode 13 are provided on one diaphragm 11 in FIG. 6, the number of diaphragms 11 is not
limited to one. For example, three diaphragms 11 having a slightly larger area than the left
channel electrode 12, the right channel electrode 13, and the bass channel electrode 16 are
prepared, and the left channel electrodes 12 are formed on both sides of the first diaphragm 11;
The bass channel electrodes 16 are formed on both sides of the diaphragm 11 of the eye, and the
right channel electrodes 13 are formed on both sides of the third diaphragm 11 (not shown).
Then, the three diaphragms 11 are attached to the substrate 14.
[0079]
(Modification) In each embodiment mentioned above, although thickness of diaphragm 11
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explained as what was uniform, it is not limited to this. Hereinafter, with reference to FIG. 8, a
modification in which the thickness of the diaphragm 11 is made uneven will be described. FIG. 8
is a side view showing a modification of the flexible stereo speaker according to the first
embodiment of the present invention.
[0080]
In FIG. 8, the control means 20 and the substrate 14 are omitted, and only the conducting wire
15 in contact with the left channel electrode 12a is shown. Further, in FIG. 8, the thickness of the
end portion of the diaphragm 11 is T1, the thickness of the central portion of the diaphragm 11
is T2, and the thickness of the recess of the diaphragm 11 is T3. Furthermore, although T1 and
T2 are illustrated with substantially equal thickness in FIG. 8, T2 is thicker than T1. That is, in
FIG. 8, T1, T2 and T3 satisfy the following formula (5). T2> T1> T3 equation (5)
[0081]
As shown in FIG. 8, a concave portion is formed on the upper surface 11a of the diaphragm 11 so
that the diaphragm 11 becomes the thinnest at an intermediate position (position T3) of the two
conducting wires 15 in contact with the left channel electrode 12a. Further, the diaphragm 11
thickens the central portion (the position T2) between the left channel electrode 12a and the
right channel electrode 13a. Then, the left channel electrode 12a is formed in this recess, and the
two conducting wires 15 are brought into line contact substantially in parallel with the left and
right sides of the left channel electrode 12a. Here, the right channel electrode 13a is also formed
similarly to the left channel electrode 12a. By forming the diaphragm 11 in this manner and
performing the same signal processing as in the first embodiment, the flexible stereo speaker
according to the present invention can generate the vibration wave of the left channel electrode
12 and the vibration wave of the right channel electrode 13. Interference can be reduced.
[0082]
Furthermore, by providing the concave portion in the diaphragm 11, the flexible stereo speaker
according to the present invention can make the diaphragm 11 vibrate equally, with the electric
field strength in the diaphragm 11 being constant. In particular, it is effective when using an
elastomer having a low conductivity as compared with metal as the left channel electrode 12 and
the right channel electrode 13.
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[0083]
Although T2 is thicker than T1 and T1 is thicker than T3 in FIG. 8, the diaphragm 11 has only
the central portion (position of T2) of the diaphragm 11 with the same thickness of T1 and T3. It
may be thicker than T1 and T3 (not shown). Also in this case, the flexible stereo speaker
according to the present invention can reduce the interference between the vibration wave of the
left channel electrode 12 and the vibration wave of the right channel electrode 13 as described
above.
[0084]
It is a schematic block diagram of the flexible stereo speaker which concerns on 1st Embodiment
of this invention. It is a side view of the flexible stereo speaker of FIG. It is a graph which shows
the characteristic of the left channel comb filter and the right channel comb filter of FIG. 1, (a) is
a graph which shows the characteristic of a left channel comb filter, (b) is a right channel comb
filter It is a graph which shows the characteristic of. It is a schematic block diagram of the
flexible stereo speaker which concerns on 2nd Embodiment of this invention. It is a schematic
block diagram of the flexible stereo speaker which concerns on 3rd Embodiment of this
invention. It is a side view of the flexible stereo speaker of FIG. It is a graph which shows the
characteristic of the low pass filter of FIG. It is a side view showing a modification of a flexible
stereo speaker concerning a 1st embodiment of the present invention.
Explanation of sign
[0085]
Reference Signs List 1 flexible stereo speaker 1B flexible stereo speaker 1C flexible stereo
speaker 11 diaphragm 12 left channel electrode 12a left channel electrode 12b left channel
electrode 13 right channel electrode 13a right channel electrode 13b right channel electrode 14
substrate 15 conductor 15a conductor 15b conductor 15c conductor 15d conductor 15d
Conductor 15e Conductor 15f Conductor 16 bass channel electrode 16a bass channel electrode
16b bass channel electrode 20 control means 21 left channel comb filter 22 right channel comb
filter 30 control means 31 left channel drive signal generation means 32 right channel drive
signal generation means 40 Control means 41 signal addition means 42 low pass filter
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