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JPH08154300

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DESCRIPTION JPH08154300
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
sound reproducing apparatus capable of expanding a sound field by forming a plurality of sound
images in a stereo sound field.
[0002]
2. Description of the Related Art Generally, in a stereo reproduction apparatus, speakers 52 and
53 are disposed on the left and right of a display apparatus 51, as shown in FIG. Alternatively, as
shown in FIG. 9B, the speakers 52 and 53 are disposed below the display device 51 at an
appropriate distance w. In such a case, the width (size) of the sound field obtained in stereo
reproduction is determined roughly by the distance w between the speakers 52 and 53 disposed
on the left and right. Therefore, when stereo reproduction is performed at the speaker position as
shown in FIGS. 9A and 9B, the sound field can not be expanded beyond the distance w between
the speakers, and the sound field is narrow and the sense of reality is lost. was there. Further, in
the display device shown in FIG. 9B, there is a disadvantage that sound can be heard from the
lower side of the display device 51.
[0003]
Therefore, conventionally, as shown in FIG. 10, the polarity of one of left and right channel
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speakers 52 and 53 is reversely connected to the polarity (+ or −) of power amplifiers 55 and
56. A virtual sound image of the difference signal component (L-R or R-L) of the output signals of
the left and right channel speakers is formed to improve the sense of reality. However, if the
polarity of either the left or right channel speaker is connected in reverse, the reproduced sound
from the left or right channel speaker will be in opposite phase, so especially in long and low
frequency bands (mainly 1 kHz or less). The voice component is canceled out and the sound
quality is totally low.
[0004]
As a technique for solving such a problem, as described in JP-A-59-32300, one using two
speakers 57 to 60 respectively on the left and right as shown in FIGS. 11 and 13 is known. That
is, the difference signal components (L-R, L-R) of the output signals of the left and right channels
(L: left channel signal, R: right channel signal) for the main sound source are reproduced outside
the speaker 57 By providing the speakers 59 and 60 serving as auxiliary sound sources,
crosstalk between both ears shown by the dotted line 63 in FIG. 12 is cancelled, and the main
sound source reproduces the main sound source outside the left and right channel speakers 59
and 60. When the signal and the auxiliary sound source are reproduced, the virtual sound images
(L + (LR) and R + (RR)) are respectively formed by the combination of the difference components,
and an effect of increasing the sense of reality is produced. Further, since the main signal
components are reproduced in the same phase by the left and right channel speakers, the abovementioned cancellation of the audio components does not occur. In this case, a virtual sound
image is formed by the sum signal (L + R) at the center position of the left and right channel
speakers. Further, it is described in JP-A-59-32300 that the distance between the left and right
channel speakers 57 and 59, and 58 and 60 is preferably about 1.2 times the distance between
the left and right ears (about 16.5 cm). It is done.
[0005]
Now, when a video source such as a movie is used as a sound source, the frequency spectra of
the main signal component and the difference signal component reproduced by the respective
speakers 57, 58, 59, 60 in FIG. It is shown in FIG.
[0006]
In FIG. 14, 65 is a left main signal component (L) reproduced by the left main sound source
speaker 57, and 66 is a right main signal component (R) reproduced by the right main sound
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source speaker 58. 67 is the difference signal component (LR) reproduced by the speaker 59
which is the left side auxiliary sound source, and 68 is the frequency spectrum characteristic of
the difference signal component (RL) which is reproduced by the speaker 60 which is the right
side auxiliary sound source It is.
As shown in FIG. 14, in the low to middle frequency range, the main signal components (L, R) of
the left and right channels do not have much difference in magnitude and phase, so that
difference signals are less likely to occur. On the other hand, in the middle to high frequencies,
differences in magnitude and phase occur in the left and right channel signals (L and R), so the
high frequency spectrum of the difference signal components (LR and RL) Many ingredients are
produced. As described above, when the high frequency component is increased, there is a
problem that the human hearing sounds like it is increased in noise.
[0007]
As described in JP-A-2-277400, low-pass filters (LPFs) 71 and 72 are provided in front of the
speakers 59 and 60 serving as the left and right sub-sound sources as shown in FIG. It is known
to insert. That is, by inserting low pass filters (LPFs) 71 and 72 in front of the speakers 59 and
60 serving as the left and right auxiliary sound sources, high frequency components of the
difference signal components (L-R and R-L) are suppressed and the noise sensation is felt Can be
avoided.
[0008]
In the above-mentioned prior art, for example, when applied to a display device, since the
speakers 59 and 60 of the sub sound source are respectively provided on the outside of the left
and right channel speakers 57 and 58 as the main sound source There is a disadvantage that the
horizontal width of the television receiver 51 itself becomes large (see FIG. 16). Furthermore, in
this case, there is a problem that the manufacturing cost is increased by providing a total of four
speakers.
[0009]
In addition, there is a problem that the manufacturing cost is increased by providing the low pass
filters 71 and 72 in order to suppress the sense of noise.
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[0010]
Therefore, it is an object of the present invention to provide a small-sized, low-cost sound
reproducing apparatus by reducing the number of speakers provided while maintaining the
expansion of the sound field.
[0011]
In addition, it is an object of the present invention to reduce the manufacturing cost while
improving the sound quality in such a sound reproducing apparatus.
[0012]
In order to achieve the above object, according to the present invention, there is provided an
audio reproduction apparatus comprising two channel output speakers for reproducing an audio
according to a corresponding channel signal, wherein The channel output speaker comprises a
first voice coil for inputting the corresponding channel signal, a channel signal inputted to the
first voice coil, and a first voice coil provided for the other channel output speaker And a second
voice coil for inputting a difference signal with a channel signal input to each of the first voice
coil and the second voice coil, wherein the first voice coil and the second voice coil are stacked
and wound. To provide a sound reproduction apparatus.
[0013]
Further, the sound reproducing apparatus is provided with a difference signal output circuit
which receives a channel signal input to the speaker for each channel output and outputs a
difference signal, and the speaker for each channel output includes A second voice coil provides
a sound reproducing apparatus characterized by connecting to the output circuit in series or in
parallel.
[0014]
According to the sound device of the present invention, the first voice coil of each of the channel
output speakers receives the corresponding channel signal as the input, and the second voice coil
of each of the channel output speakers The difference signal of the channel signal inputted into
the first voice coil and the channel signal inputted into the first voice coil provided in the other
one of the channel output speakers is the input.
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In each of the channel output speakers, by stacking and winding the first voice coil and the
second voice coil, the speakers for each channel output speaker are apparently one by one.
Therefore, the width dimension of the display device itself becomes smaller.
[0015]
Further, when the inductance of the second voice coil of each of the channel output speakers is
made larger than the inductance of the first voice coil, the high frequency component of the
acoustic signal converted by the second voice coil is suppressed. Be done.
Therefore, it is not necessary to specially provide a means for suppressing a sense of noise such
as a low pass filter, and the manufacturing cost can be reduced.
[0016]
Furthermore, when a difference signal output circuit is provided, the difference signal output
circuit receives a channel signal input to the speaker for each channel output and outputs the
difference signal.
As a result, since the difference signal input to the second voice coil can be stably obtained, the
sound quality is improved.
[0017]
Embodiments of the present invention will now be described with reference to the accompanying
drawings.
[0018]
In this embodiment, the number of speakers provided is reduced while maintaining the
expansion of the sound field, thereby providing a small-sized, low-cost sound reproducing
apparatus.
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In addition, in such a sound reproducing device, the manufacturing cost is reduced while
improving the sound quality.
[0019]
First, the configuration of a sound reproducing apparatus for reducing the number of speakers
provided while maintaining the spread of the sound field will be described using FIGS. 1 and 2.
FIG.
[0020]
FIG. 1 is an example of the block diagram of the sound reproduction apparatus based on a
present Example.
[0021]
In FIG. 1, reference numeral 1 denotes a left channel speaker for reproducing a left channel
signal, and reference numeral 2 denotes a right channel speaker for reproducing a right channel
signal.
The left channel speaker 1 has a first voice coil 1a for reproducing the main signal component
(L) of the left channel, and a difference signal component between the main signal component (L)
of the left channel and the main signal component (R) of the right channel. And a second voice
coil 1b for reproducing (LR).
Similarly, the right channel speaker 2 includes a first voice coil 2a for reproducing the main
signal component (R) of the right channel, a main signal component (R) of the right channel, and
a main signal component (R) of the left channel. And a second voice coil 2b for reproducing the
difference signal component (R-L).
[0022]
Here, the first voice coils 1a and 2a included in the left and right channel speakers 1 and 2 are
connected to the power amplifiers 3 and 4 of the left and right channels, respectively.
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By this connection, each first voice coil reproduces the main signal component.
[0023]
On the other hand, the second voice coil speaker 1b provided in the left channel speaker 1 has
the input terminal + connected to the output terminal + of the left channel power amplifier 3 and
the input terminal − connected to the output terminal + of the right channel power amplifier 4
Do.
Similarly, the second voice coil speaker 2b included in the right channel speaker 2 has an input
terminal + at the output terminal + of the right channel power amplifier 4 and an input terminal
− at the output terminal + of the left channel power amplifier 3 Connecting. By this connection,
each second voice coil reproduces a difference signal component.
[0024]
By such connection, a virtual sound image having (LR) or (RL) as a component is formed at the
central position of the left and right channel signal speakers by combining the left and right main
signal components. Further, on the outside of the left and right channel speakers 1 and 2, virtual
sound images (L + (LR) and R + (RL)) are formed by combining the main signal component and
the difference signal component. As a result, an effect of improving the sense of reality is
produced. At this time, if the impedance value of the second voice coil is set to a half of the
impedance value of the first voice coil, the sound pressure level of the difference signal is
increased to increase the sense of reality. However, at the same time, there are many high
frequency components in the spectrum of the difference signal components (L-R and R-L), and
there is a drawback that the human hearing sounds like a lot of noise.
[0025]
The second voice coils 1b and 2b provided in the left and right channel speakers 1 and 2 may be
connected as shown in FIG. That is, the negative terminals of the second voice coils 1b and 2b of
the left and right channel speakers 1 and 2 are connected to each other. Furthermore, the +
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terminals of the second voice coils 1 b and 2 b of the left and right channel speakers 1 and 2 are
connected to + of the output terminals of the power amplifiers 3 and 4 of the respective
channels. Such connection also produces the same effect as the connection shown in FIG.
[0026]
FIG. 2 is a cross-sectional view of the left and right channel speakers used in the sound
reproduction apparatus according to the present embodiment.
[0027]
In FIG. 2, 1a and 2a are first voice coils for reproducing a main signal, 1b and 2b are second
voice coils for reproducing a difference signal, 1c and 2c are voice coil bobbins, 5 is a magnetic
circuit, and 6 is a diaphragm. , 7 is a frame for supporting the magnetic circuit 5 and the
diaphragm 6.
[0028]
By winding the first voice coil 1a, 2a and the second voice coil 1b, 2b having independent input
terminals around the common voice coil bobbins 1c, 2c, the same speaker as the main signal
component and the difference signal component Play with.
[0029]
With such a configuration, in the sound reproducing apparatus according to the present
embodiment, it is possible to reduce the number of speakers provided while maintaining the
expansion of the sound field.
As a result, it is possible to realize the reduction of the lateral dimension of the sound
reproducing device and the reduction of the manufacturing cost.
[0030]
This completes the description of the configuration of the sound reproduction device for
reducing the number of speakers provided while maintaining the spread of the sound field.
[0031]
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Hereinafter, a method of reducing the manufacturing cost while improving the sound quality in
the sound reproducing apparatus according to the present embodiment will be described.
[0032]
By the way, as described above, when a video source such as a movie is used as a sound source, a
lot of high frequency components are generated in the spectrum of difference signal components
(LR and RL), so that human hearing is noisy. There was a problem that I could hear it.
[0033]
Therefore, a method of suppressing such a high frequency component of the spectrum of the
difference signal component in the sound reproducing apparatus according to the present
embodiment will be described with reference to FIGS. 4 and 5. FIG.
[0034]
FIG. 4 is an example of the block diagram of the sound reproduction apparatus based on a
present Example.
[0035]
FIGS. 4A and 4B show the left and right channel speakers used in the sound reproduction
apparatus according to the present embodiment, in which the inductance of the second voice coil
b provided is larger than that of the first voice coil a. .
That is, by increasing the number of winding layers of the second voice coil b more than the first
voice coil a in FIG. 4A, on the other hand, in FIG. By increasing the winding width of the second
voice coil b, the inductance of the second voice coil b provided is made larger than that of the
first voice coil a.
[0036]
FIG. 5 shows impedance curves and sound pressure frequency characteristics of the first voice
coil and the second voice coil provided in the speaker shown in FIG.
[0037]
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In FIG. 5, 8 and 9 are the impedance curve and sound pressure frequency characteristics of the
first voice coil, and 10 and 11 are the impedance curve and sound pressure frequency
characteristics of the second voice coil, respectively.
[0038]
As shown in FIG. 5, when the inductance of the second voice coil is increased, the impedance
curve 10 rises as the frequency becomes higher, and the sound pressure frequency characteristic
11 is attenuated.
This indicates that the second voice coil suppresses the high frequency component of the
difference signal component reproduced by the second voice coil by increasing the inductance.
At the same time, it indicates that good reproduced sound can be obtained.
[0039]
Therefore, by adopting such a configuration, it is not necessary to provide a low pass filter or the
like in order to suppress the high frequency component of the spectrum of the difference signal
component, and the manufacturing cost can be reduced.
[0040]
This is the end of the description of the method for reducing the manufacturing cost while
improving the sound quality in the sound reproducing apparatus according to the present
embodiment.
Further, by using a method as described later in such a sound reproducing apparatus, the sound
quality can be further improved.
[0041]
Now, a method of improving the sound quality of the sound reproduction apparatus used in the
embodiment according to the present invention will be described below.
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[0042]
FIG. 6 shows an example of the configuration when the tweeter is provided in the sound
reproducing apparatus according to the present embodiment, that is, the sound reproducing
apparatus having the configuration shown in FIG.
[0043]
In FIG. 6, the left and right channel speakers 1 and 2 increase the inductance of the second voice
coil provided by any of the configurations shown in FIGS. 4 (A) and 4 (B).
In addition, the left and right channel speakers 1 and 2 respectively include tweeters 12 and 13
for reproducing the missing high sound.
That is, the tweeters 12 and 13 are connected in parallel to the first voice coils 1a and 2a via the
high pass filters 14 and 15, respectively, and compensate the high frequency components of the
main signal component reproduced by the first voice coil. .
As a result of using the tweeters 12 and 13 together in this way, a clear reproduced sound can be
obtained, which is well-balanced from low to high frequencies.
[0044]
By the way, as shown in FIG. 1, FIG. 3 and FIG. 6, when the first and second voice coils are
connected to one power amplifier, the output impedance of the power amplifier is lowered and
the operating state becomes unstable. Sometimes.
Therefore, in order to obtain the stability of the operation of the power amplifier, it is necessary
to consider the impedance values of the first and second voice coils 1a, 2a, 1b, 2b provided in the
speakers 1, 2, respectively.
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For example, in the power amplifier used in the present embodiment, when the output
impedance is 8Ω, a stable output can be obtained. For that purpose, the impedance of the first
and second voice coils 1a, 2a, 1b, 2b is 16Ω to It should be 24 Ω.
However, if the wire diameter of each voice coil is made the same in order to make the allowable
input the same, the wire length of the voice coil becomes longer than necessary, and as a result,
the winding width becomes large, which is not preferable.
[0045]
Therefore, as shown in FIG. 7, in the left and right channel output speakers, the first voice coils
1a and 2a and the second voice coils 1b and 2b are applied by separate power amplifiers 3, 4, 16
and 17, respectively. Do.
At this time, subtraction circuits 18 and 19 which take the difference between the left and right
channels, respectively, are inserted in front of the power amplifiers 16 and 17 so that the second
voice coils 1b and 2b reproduce the difference signal component.
[0046]
As a result, the operations of the power amplifiers 3, 4 and 16, 17 become stable, and each voice
coil can obtain a stable input signal, so that the sound quality of the reproduced sound is
improved.
[0047]
Further, between the power amplifiers 16 and 17 for driving the second voice coils 1b and 2b
and the subtraction circuits 18 and 19 at the previous stage, bandpass filters 20 and 21 for
extracting a specific band of the input signal, and The delay circuits 22 and 23 for adjusting the
delay time τ and the phase shift circuits 24 and 25 for adjusting the phase 入 力 of the input
signal are inserted to adjust the frequency band and the phase of the input signal applied to the
power amplifiers 16 and 17 Compared with the case where input signals are directly applied
from the subtraction circuits 18 and 19, it is possible to obtain a sense of expansion and a sense
of depth of the reproduction sound field.
[0048]
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When more emphasis is placed on low frequency components, if low pass filters 26 and 27 are
inserted to cut off the high frequency components of the input signal, a natural sound without
noise will be obtained.
Further, in the case of the configuration shown in FIG. 8, the number of power amplifiers can be
reduced.
That is, the second voice coils 1b and 2b of the left and right channel speakers 1 and 2 are
connected in series to the power amplifier 28 in the subsequent stage of the subtraction circuit
29 which takes the difference between the left and right channels. Connect to
Alternatively, they may be connected in parallel so that the inputs are in opposite phase. In this
way, the power amplifier 28 in the subsequent stage of the subtraction circuit 29 that takes the
difference between the left and right channels shares a circuit that generates the input signals of
the second voice coils 1 b and 2 b of the left and right channel speakers 1 and 2. Can reduce the
number of power amplifiers. However, in this case, as described above, it is necessary to consider
the impedance values of the first and second voice coils so as to obtain the stability of the
operation of the voltage amplifier. The band pass filter 30, the delay circuit 31, the phase shift
circuit 32, and the low pass filter 33 are inserted between the power amplifier 28 driving the
second voice coils 1b and 2b and the subtraction circuit 29 at the previous stage. The same effect
as the configuration shown in FIG. 7 can be obtained.
[0049]
According to the sound reproducing apparatus of the present invention, by reproducing the main
signal component and the difference signal component with the same speaker, the number of
speakers can be reduced while maintaining the spread of the sound field. Thus, the size of the
sound reproducing device can be reduced and the manufacturing cost can be reduced. In
addition, by providing means for suppressing the high frequency component of the difference
signal component in such an audio reproducing apparatus, it is possible to reduce the
manufacturing cost while improving the sound quality.
[0050]
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Brief description of the drawings
[0051]
1 is an example of a configuration diagram of a sound reproduction apparatus according to an
embodiment of the present invention.
[0052]
2 is a cross-sectional view of a speaker used in the sound reproduction device of the
configuration of FIG.
[0053]
3 is an example of a block diagram of the sound reproduction apparatus of the embodiment of
the present invention.
[0054]
4 is a cross-sectional view of a speaker used in the sound reproduction device of the
configuration of FIG. 1 and FIG.
[0055]
5 is a sound pressure frequency characteristic and an electrical impedance curve of the speaker
of FIG.
[0056]
6 is an example of a block diagram of the sound reproduction apparatus of the embodiment of
the present invention.
[0057]
7 is an example of a block diagram of the sound reproduction apparatus of the embodiment of
the present invention.
[0058]
8 is an example of a configuration diagram of the sound reproduction apparatus of the
embodiment of the present invention.
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[0059]
9 is a layout diagram of the main sound source speaker in the prior art.
[0060]
10 is an example of a configuration diagram showing the connection of the speaker in the prior
art.
[0061]
11 is an example of a configuration diagram showing the connection of the speaker in the prior
art.
[0062]
12 is a diagram for explaining the arrangement of speakers in the prior art example and
crosstalk between both ears.
[0063]
13 is a diagram for explaining the arrangement of the speakers of the main sound source and the
auxiliary sound source in the prior art example, and a method for canceling crosstalk between
both ears and crosstalk between both ears.
[0064]
14 is a spectrum frequency characteristic of the reproduced sound reproduced by the speakers
of the main sound source and the auxiliary sound source.
[0065]
15 is an example of a configuration diagram showing the connection of the speaker in the prior
art.
[0066]
16 is a layout diagram of speakers of the main sound source and the sub sound source in the
display device of the prior art.
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[0067]
Explanation of sign
[0068]
1 and 2: left and right channel speakers 1a and 2a: first voice coil of speakers 1, 2 1b and 2b:
second voice coil of speakers 1, 2 3: power amplifier for driving speaker 1 4 ... Power amplifier
for driving the speaker 2, 8, 10 ... Electric impedance curve in the speakers 1 and 2, 9, 11 ...
Sound pressure frequency characteristics in the speakers 1 and 2, 12, 13 ... tweeter, 14, 15 ...
high pass filter, 16 ... Power amplifier for driving the second voice coil of the speaker 1, 17 ...
Power amplifier for driving the second voice coil of the speaker 2, 18, 19 ... Difference signal (LR)
of the left and right channels, (RR ) Subtractor circuit, 20, 21 ... Band pass filter, 22, 23 ... Delay
circuit, 24, 25 ... Phase shift circuit, 26, 27 ... Low power Filter 28 Power amplifier for driving the
second voice coil of the speakers 1 and 2 29 Subtractor circuit for forming a difference signal
(LR) between left and right channels 30 Band pass filter 31 Delay circuit 32 Phase shift circuit,
33 ... low pass filter.
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