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JP2013062773

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DESCRIPTION JP2013062773
PROBLEM TO BE SOLVED: To provide an audio reproduction apparatus including a directivity
control unit for controlling the directivity of a speaker, which has a simple configuration and
better than the actual position of the speaker for a monaural component common to left and
right channels. SUMMARY OF THE INVENTION The present invention provides an audio
reproduction device capable of obtaining sound image localization far and a stereoscopic video
reproduction device including the same. SOLUTION: A sound reproducing device comprises a left
speaker, a right speaker, a center front speaker having a sound path defining an opening on an
extension surface of a speaker mounting surface on the front side of its diaphragm, and a stereo
amplifier capable of BTL connection. A circuit and a phase inverting circuit that inverts one of the
left signal and the right signal and inputs the result to the stereo amplifier circuit, and one of the
left speaker and the right speaker is phase inverted and connected to the stereo amplifier circuit;
The front speaker is phase-inverted to the stereo amplifier circuit and BTL-connected to obtain a
directivity control unit for obtaining unidirectional radiation characteristics. [Selected figure]
Figure 1
Sound reproduction apparatus and 3D image reproduction apparatus including the same
[0001]
The present invention relates to a sound reproduction apparatus including a directivity control
unit for controlling the directivity of a speaker, and relates to a sound reproduction apparatus
capable of obtaining sound image localization farther than the actual position of the speaker.
[0002]
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1
As a method to control the change in acoustic radiation characteristics depending on the
direction (hereinafter referred to as “directivity”) using a speaker that reproduces sound waves
in the audible range, two nondirectional speakers are connected in antiphase to be bidirectional
In the case of sex, or a method of giving a unidirectional beam or directional beam in a certain
direction by three or more speaker arrays is proposed.
For example, the applicant has proposed a directional control device and a gaming machine using
the same, which can obtain clear unidirectional radiation characteristics only by using two
speakers (Patent Document 1).
[0003]
In the conventional method, a time delay is basically given to each speaker depending on the
structure of the speaker and the signal processing, and the desired directivity is realized by
utilizing spatial phase interference of sound waves. In particular, when unidirectionality is
realized, a direction in which the volume is reproduced at a high level (referred to as a “beam
direction”) and a direction reproduced at a low level (referred to as a “zero point direction”)
occur. A sound reproduction system using the has been proposed. In this case, the area in the
beam direction is usually used as an area in which the listener is located, and the area in the zero
point direction is mainly used for the purpose of reducing the volume.
[0004]
On the other hand, the applicant drives a pair of speakers for reproducing sound waves in the
audible range to obtain uni-directional characteristics, and an arrangement method of the
speaker device in which the sound image is felt farther than the actual arrangement position of
the speakers. And a sound reproduction device using the speaker device (Patent Document 2). In
the case of reproducing monaural sound in a normal stereo reproduction apparatus, if it is
reproduced with one speaker, the perceived sound image becomes the installation position of the
speaker. On the other hand, if stereo sound is reproduced equally by dividing it into two speakers
equidistant from the listener, that is, if monaural sound is given to the left channel and the right
channel and reproduced, a phantom is generated at the center of the speakers of both channels.
The monaural sound is localized and perceived as a sound image. However, in the case of Patent
Document 2, if the monaural sound as described above is reproduced by the left and right
channels, the phantom sound image is localized farther than the actual arrangement position of
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2
the speakers.
[0005]
However, in the prior art of Patent Document 2, when reproducing standard left and right twochannel stereo signals, a total of four speakers and an amplifier for four channels are required,
which is a total compared to the usual case. There is a problem that cost is increased by two
speakers and two channels of amplifiers. In addition, although it can be assumed that the prior
art of Patent Document 2 reproduces a stereo signal with a total of two speakers and an amplifier
for two channels, it is conceivable to simply use a comb filter for a monaural component common
to the left and right channels. There is a problem that audio information is lost at the signal level
stage. Further, due to the relationship of the arrangement position of the speakers, it is
impossible to give the listener a sense of localization in the depth direction of the sound image as
in Patent Document 2.
[0006]
Also, conventionally, there is an output circuit which is provided with a center speaker separately
from a stereo speaker, BTL-amplifies two amplifiers, and drives the center speaker with a (L + R)
signal (Patent Documents 3, 4 and 5). A so-called "3D system using BTL amplification", in a stereo
amplifier that can be connected to BTL, a phase inversion circuit is inserted in one channel, and
speakers in one or the other channel are connected in reverse phase, and stereo power This is a
circuit in which the center speaker is connected by BTL between the hot of the amplifier to
reproduce the L + R component.
[0007]
Patent documents 1: Unexamined-Japanese-Patent No. 2003-87888 (FIGS. 1-7) UnexaminedJapanese-Patent 2003-87893 (FIGS. 1-12) Real opening 61-134200 (Figs. 1-2) Japanese Patent
Application Laid-Open No. 62-129900 (FIG. 1) Japanese Patent Application Laid-Open No. 6311599 (FIGS. 1 and 2)
[0008]
The present invention has been made to solve the above-described problems of the prior art, and
its object is to provide an audio reproduction apparatus including a directivity control unit for
controlling the directivity of a speaker, which is more simple. It is an object of the present
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invention to provide a sound reproducing apparatus capable of obtaining sound image
localization far from the actual position of the speaker well even for monaural components
common to the left and right channels by the above configuration.
[0009]
The sound reproducing apparatus according to the present invention includes a speaker
mounting surface, a left speaker mounted on the speaker mounting surface to reproduce the left
signal, a right speaker mounted on the speaker mounting surface to reproduce the right signal,
and an extension surface of the speaker mounting surface The sound path defining the opening
is provided on the front side of the diaphragm, and the opening is disposed at an intermediate
position between the left speaker and the right speaker and at a position forming an
approximately isosceles triangle with the left speaker and the right speaker. And a stereo
amplifier circuit capable of BTL connection, and a phase inverting circuit for inverting one of left
and right signals and inputting the result to the stereo amplifier circuit, and one of the left
speaker and the right speaker Are phase-inverted and connected to the stereo amplifier circuit,
and the center front speaker is phase-inverted to the stereo amplifier circuit and BTL connected
And the directivity control part to obtain a single directional radiation characteristic, and the
sound path of the center front speaker is approximately the separation distance on the extension
surface of the speaker mounting surface of the left speaker and the right speaker and the center
front speaker. With equal sound path lengths, the left and right speakers in the speaker
mounting plane are arranged symmetrically towards the listener, and the center front speaker is
arranged closer to the listener than the left and right speakers There is.
[0010]
Preferably, in the sound reproducing device according to the present invention, the left speaker,
the right speaker, and the center front speaker are elongated electrodynamic speakers whose
length in the short diameter direction is shorter than the length in the long diameter direction.
The right speaker is disposed on the extension surface of the speaker mounting surface so that
the right speakers are arranged so that the major axis directions coincide with each other and the
separation distance from the opening of the center front speaker substantially matches the minor
axis length. It is placed close to the front speaker.
[0011]
Also preferably, in the sound reproduction device according to the present invention, the
directivity control unit cancels a left signal or a right signal canceled due to a separation distance
between the left speaker and the right speaker driven in opposite phase and the center front
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4
speaker. And compensation means for relatively increasing the level in the low frequency range
of
The sound reproduction apparatus according to any one of claims 1 to 4.
[0012]
Further, according to the sound reproduction device of the present invention, the directivity
control unit adjusts and outputs the relative level of the output signal to the center front speaker
with respect to the output signal to the left speaker or the output signal to the right speaker. It
further includes a circuit.
[0013]
Further, in the sound reproducing device of the present invention, the speaker mounting surface
is disposed along the horizontal direction, and the listener's head is disposed on the extension
surface.
[0014]
In addition, a stereoscopic video reproduction device of the present invention at least includes
the above-described sound reproduction device and a 3D display.
[0015]
Hereinafter, the operation of the present invention will be described.
[0016]
The sound reproducing apparatus according to the present invention comprises a speaker
mounting surface, a left speaker and a right speaker mounted on the speaker mounting surface,
and a center front speaker having a sound path defining an opening in an extension surface of
the speaker mounting surface; And an directivity control unit for driving a right front speaker
and a center front speaker to obtain unidirectional radiation characteristics, and capable of
giving a listener a sound image localization farther to the listener than an actual position of the
speakers It is.
[0017]
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The directivity control unit has a stereo amplifier circuit capable of BTL connection by
reproducing the left signal and the right signal, and a phase inverting circuit which inverts one of
the left signal or the right signal and inputs it to the stereo amplifier circuit.
In the directivity control unit, one of the left speaker and the right speaker is phase-inverted and
connected to the stereo amplifier circuit, and the center front speaker is phase-inverted to the
stereo amplifier circuit and BTL connected.
That is, the directivity control unit for obtaining unidirectional radiation characteristics outputs
the left signal to the left speaker, outputs the right signal to the right speaker, and outputs the
sum signal obtained by adding the left signal and the right signal by BTL connection to the center
front Output to the speaker.
As a result, the directivity control unit converts the left signal from the left speaker into a sound
wave and outputs the sound wave, and outputs the right signal from the right speaker so as to
reproduce the sound wave in phase with the left signal. The sum signal obtained by adding the
right signal and the right signal is output from the center front speaker as the sound wave of the
opposite phase is reproduced.
[0018]
The left speaker and the right speaker that respectively reproduce the left signal and the right
signal of the stereo signal are attached to the speaker mounting surface and arranged
symmetrically to the listener.
In addition, the center front speaker has a sound path that defines an opening on the extension
surface of the speaker mounting surface on the front side of the diaphragm, and on the middle
position between the left speaker and the right speaker, the left speaker and the right speaker
The opening is disposed at a position forming a substantially isosceles triangle.
The sound path of the center front speaker has a sound path length substantially equal to the
separation distance on the extension surface of the speaker mounting surface of the left speaker
and the right speaker and the center front speaker.
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The opening of the center front speaker is disposed closer to the listener than the left speaker
and the right speaker.
That is, since the diaphragm of the center front speaker is disposed at a position deep in the
sound path from the opening, the sound wave reproduced from the front side of the diaphragm is
delayed by the time for the sound wave to transmit the sound path length. It is emitted from the
department.
[0019]
As a result, with regard to the left signal, a unidirectional sound emission characteristic in which
the listener side is made the zero point direction by the left speaker and the center front speaker,
and the back side of the left speaker along one side of the isosceles triangle is the beam direction.
For the right signal, a single directional acoustic emission, with the listener side at the zero point
direction by the right speaker and the center front speaker, with the back side of the right
speaker along one side of the isosceles triangle as the beam direction Characteristics are realized.
Thus, the listener can obtain sound image localization farther on the left signal than the actual
position of the left speaker and sound image localization farther on the right signal than the
actual position of the right speaker. Even in the case of reproducing monaural sound in which the
left signal and the right signal have substantially the same amplitude and phase relationship, the
phantom sound image is localized farther than the actual arrangement position of the speakers.
When reproducing standard left and right two-channel stereo signals, only a total of two
speakers and an amplifier capable of BTL connection for two channels are required, and the
delay circuit becomes unnecessary. That is, since the digital circuit necessary for providing the
delay circuit is not necessary, and the design can be performed only with the analog circuit, the
stereo sound field is far from the cost increase as compared with the prior art of Patent
Document 2 The same effect of spreading can be obtained. In addition, since the left signal and
the right signal are respectively reproduced by the left speaker and the right speaker, there is an
advantage that there is no problem that the main audio information is lost by the comb filter.
[0020]
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7
Particularly preferably, the left speaker, the right speaker, and the center front speaker may be
long and thin electrodynamic speakers whose length in the minor axis direction is shorter than
the length in the major axis direction. The short and slender electrodynamic speaker is preferably
a speaker including a rectangular flat diaphragm, and in the sound reproducing apparatus of the
present invention, the left speaker and the right speaker are arranged such that their major axis
directions coincide with each other. And, it is disposed close to the center front speaker so that
the distance between the center front speaker and the minor axis direction length substantially
match. When realized with a speaker of a flat diaphragm having a short minor axis direction and
a long major axis direction, the distance between the loudspeakers can be narrowed as compared
with a normal round speaker. The substantial separation distance between the center front
speaker disposed on the front side, and the left and right speakers can be approximated by the
minor axis length. If the substantial separation distance is shortened, the delay time in the sound
path can be shortened, and unidirectional control can be performed up to high frequencies.
Furthermore, since the width can be made in the direction of the zero point in the
unidirectionality, the effect that the sound image can be felt in the distance can be enhanced.
[0021]
Also, the directivity control unit relatively increases the level of the low frequency region of the
left signal or the right signal canceled due to the separation distance between the left speaker
and the right speaker and the center front speaker driven in opposite phase. If it further includes
compensating means, it is possible to compensate for the bass component lost by the
unidirectional control. The bass component can be relatively emphasized by canceling out the
bass component between the left speaker and the center front speaker disposed close to the right
speaker, and the sound image perceived to be distant to the listener can be well balanced. . Also,
with regard to the negative phase component (for example, (left signal-right signal)) of the stereo
signal, although the bass component is likely to be canceled between the left speaker and the
right speaker disposed close to each other, the low band is relatively Since the compensation
circuit emphasizing in, it is possible to maintain the sense of the spread of the stereo sound field.
[0022]
Note that the speaker mounting surface may be disposed along the horizontal direction, and if
the listener's head is disposed on the extension surface of the speaker mounting surface, a single
directivity with the listener side as the zero point direction Acoustic emission characteristics of
sex are realized, making it easier for the listener to obtain sound image localization farther than
the actual position of the speaker.
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[0023]
Further, the sound reproduction apparatus further includes a level adjustment circuit in which
the directivity control unit adjusts and outputs the relative level of the output signal to the center
front speaker with respect to the output signal to the left speaker or the output signal to the right
speaker. If included, the sense of localization in the depth direction of the sound image can be
changed.
By reducing the output level of the output signal from the directivity control circuit to the center
front speaker, the sound image can be localized to the front side, and when the output level is
increased, the sound image can be localized to the rear side. In particular, in the threedimensional video reproduction apparatus including the sound reproduction apparatus and the
3D display, it is possible to realize video / sound reproduction with a more realistic sensation.
[0024]
The sound reproducing apparatus according to the present invention includes the directivity
control unit for controlling the directivity of the speaker, and the simple configuration allows the
monaural component common to the left and right channels to be better than the actual position
of the speaker. Sound image localization can be obtained.
[0025]
It is a figure explaining the sound reproduction apparatus 1 by preferable embodiment of this
invention.
(Example 1) It is a figure explaining the speaker part 3 which comprises the sound reproduction
apparatus 1 by preferable embodiment of this invention. (EXAMPLE 1) A diagram conceptually
illustrating uni-directional radiation characteristics and a reproduction sound field reproduced by
the sound reproduction device 1 according to a preferred embodiment of the present invention.
(EXAMPLE 1) A diagram for conceptually explaining the omnidirectional radiation characteristics
and the reproduction sound field reproduced by the speaker unit 30 of the sound reproduction
device of the comparative example. (Comparative Example 1) FIG. 6 is a view for explaining an
elongated electrodynamic speaker 20 which constitutes the speaker portion 3 of the sound
reproducing apparatus 1 according to another preferred embodiment of the present invention.
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(Example 2) FIG. 6 is a view for explaining a speaker unit 3 which constitutes a sound
reproducing apparatus 1 according to another preferred embodiment of the present invention.
(Example 2)
[0026]
Hereinafter, an audio reproduction apparatus according to a preferred embodiment of the
present invention and a stereoscopic video reproduction apparatus including the same will be
described, but the present invention is not limited to these embodiments.
[0027]
FIGS. 1 and 2 are diagrams for explaining a sound reproduction device 1 according to a preferred
embodiment of the present invention.
Specifically, FIG. 1 is a block diagram showing the configuration of the sound reproduction
device 1. Further, FIG. 2 is a view for explaining the speaker unit 3 constituting the sound
reproduction device 1, FIG. 2 (a) is a plan view, and FIG. 2 (b) is a side sectional view.
Furthermore, FIG. 3 is a diagram for conceptually explaining the unidirectional radiation
characteristic and the reproduction sound field reproduced by the sound reproduction device 1,
and FIG. 3 (a) is a plan view, FIG. 3 (b) Shows a side view (partial sectional view). In addition,
illustration and description are abbreviate | omitted for the one part structure unnecessary for
description, an internal structure, etc. FIG.
[0028]
The sound reproduction device 1 is composed of a directivity control circuit 2 and a speaker
system 3. The sound reproducing device 1 is a sound reproducing device capable of giving the
listener 4 sound image localization farther than the actual position of the speaker system 3 as
shown in FIG. The directivity control circuit 2 has input terminals Lin and Rin for inputting the
left signal L and the right signal R, and three output terminals Lout, Rout and Fout. The
directivity control circuit 2 inputs a stereo signal (the left signal L and the right signal R) to
relatively increase the level in each low frequency region, and one of the left signal L and the
right signal R ( In the case of this embodiment, it includes at least a phase inverter 6 for inverting
the phase of the right signal R), and two amplifier circuits 7L and 7R which can be BTLconnected. Specifically, the directivity control circuit 2 can be configured by a stereo amplifier
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apparatus incorporating a BTL amplifier circuit corresponding to stereo sound, or an amplifier
device or the like.
[0029]
The speaker system 3 forms a speaker mounting surface 32 on the top surface side of the
cabinet 31 formed of resin or the like, and the left speaker Lsp and the right speaker Rsp
mounted on the speaker mounting surface 32 and an extension surface of the speaker mounting
surface 32 The sound path 34 defining the opening 33 is on the front side of the diaphragm, and
an approximately isosceles triangle is formed with the left speaker Lsp and the right speaker Rsp
at an intermediate position between the left speaker Lsp and the right speaker Rsp. And a central
front speaker Fsp in which the central portion of the opening 33 is disposed at the position
where The left speaker Lsp and the right speaker Rsp in the present embodiment are 8 cm
diameter electrodynamic speakers having circular shaped outside diameter cone diaphragms, so
that the respective cone diaphragms are aligned in the same top surface direction The speaker
mounting surface 32 is attached.
[0030]
In addition, the center front speaker Fsp is an electrodynamic speaker with a diameter of 8 cm
having a cone diaphragm having the same outer dimensions as the left speaker Lsp and the right
speaker Rsp, and differs in that it has the opening 33 and the sound path 34 The other is a
common electrodynamic speaker. These three speakers preferably have approximately the same
acoustic emission characteristics, and most preferably the same. The three speakers need to align
the positive and negative terminals of the magnetic circuit and the voice coil so that at least the
audio signal is radiated in phase.
[0031]
The sound path 34 of the center front speaker Fsp has a sound path length d substantially equal
to the separation distance d on the extension surface of the speaker mounting surface 32
between the left speaker Lsp and the right speaker Rsp and the center front speaker Fsp. The
cone diaphragm of the center front speaker Fsp is disposed at a deep position of the sound path
34 from the opening 33. Therefore, the sound wave reproduced from the front side of the
diaphragm is delayed by the time when the sound wave transmits the sound path length d. Then,
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the light is emitted from the opening 33. The opening 33 of the center front speaker Fsp is
disposed closer to the listener 4 than the left speaker Lsp and the right speaker Rsp. In the case
of the present embodiment, the sound path 34 is a sound path whose cross-sectional area does
not change up to the opening 33, but in other cases the sound path 34 has a horn shape from the
cone diaphragm to the opening 33 The cross-sectional area may be enlarged.
[0032]
The cabinet 31 has a space for defining an acoustic capacity in order to increase the bass range
near and below the lowest resonance frequency of each speaker. The interior of the cabinet 31 is
preferably divided for each speaker so that the sound waves radiated to the back side of the cone
diaphragm do not interfere with each other. The cabinet 31 can adopt cabinets of various types
such as a closed type, a bass reflex type, a Kelton type, and the like. The cabinet 3 of the speaker
system 2 may be provided with a front grille (not shown), a punching net, etc. so as to protect the
exposed speakers 10.
[0033]
As illustrated, the left speaker Lsp and the right speaker Rsp are disposed symmetrically to the
listener 4. In addition, the center front speaker Fsp is located at an intermediate position between
the left speaker Lsp and the right speaker Rsp on the speaker mounting surface 32, and the
opening 33 is formed at a position forming an approximately isosceles triangle with the left
speaker Lsp and the right speaker Rsp. It is arrange | positioned and is arrange | positioned
rather than the left speaker Lsp and the right speaker Rsp toward the listener 4. FIG. That is,
when viewed from the three speakers, the listener 4 is positioned in the direction in which the
vertical bisector passes through the vertex formed by the two equal-length sides of the isosceles
triangle. In the case of this embodiment, the three speakers are arranged at positions forming a
substantially equilateral triangle, and the separation distance d between the respective speakers
is about 10 cm. The separation distance d between the loudspeakers can be calculated by the
distance between the central positions of the respective diaphragms. Also, the speaker mounting
surface 32 is disposed along the horizontal direction, and the head of the listener 4 is located on
the extension surface thereof.
[0034]
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The directivity control circuit 2 amplifies and outputs the left signal L and the right signal R
which are analog voice signals. The input left signal L and right signal R are each input to the
compensation filter 5. The output of the compensation filter 5 to which the left signal L is input
is input to the amplifier circuit 7L which can be connected to BTL. On the other hand, the output
of the compensation filter 5 to which the right signal R is input is input to the amplifier circuit 7R
capable of BTL connection via the phase inverter 6. The BTL connectable amplifier circuits 7L
and 7R have substantially the same output characteristics.
[0035]
In addition, the positive output (+) of the amplifier circuit 7L is connected to the positive terminal
(+) of the output terminal Lout of the directivity control circuit 2, and the negative output of the
amplifier circuit 7L is connected to the negative terminal (-) of the output terminal Lout. (-) Is
connected. The negative output (-) of the amplifier circuit 7R is connected to the positive terminal
(+) of the output terminal Rout of the directivity control circuit 2. The negative terminal (-) of the
output terminal Rout is connected to the positive output (+) of the amplifier circuit 7R. Is
connected. Furthermore, the positive terminal (+) of the amplifier circuit 7L and the positive
output (+) of the amplifier circuit 7R are BTL connected to the positive terminal (+) of the output
terminal Fout of the directivity control circuit 2, and the negative terminal of the output terminal
Fout The negative output (-) of the amplifier circuit 7L and the negative output (-) of the amplifier
circuit 7R are BTL connected to (-).
[0036]
Therefore, the left signal L is amplified and output to the output terminal Lout of the directivity
control circuit 2 and becomes an output of positive phase with respect to the input signal. The
right signal R is amplified and output to the output terminal Rout of the directivity control circuit
2. The right signal R that is amplified and output is inverted in phase by the phase inverter 6 and
the amplifier circuit 7R, so that it becomes an output of positive phase with respect to the input
signal. It becomes a phase. On the other hand, the sum signal (L + R) of the left signal L and the
right signal R is BTL amplified and output to the output terminal Fout of the directivity control
circuit 2. Since the right signal R is phase-inverted by the phase inverter 6 and the amplifier
circuit 7R respectively, the sum signal (L + R) that is amplified and output is also in phase with
the left signal L in relative relation. . Therefore, a positive phase sum signal (L + R) output is
obtained from the output terminal Fout with respect to the input signal.
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[0037]
Thus, the directivity control circuit 2 outputs the left signal L having the level in the low
frequency region relatively increased to the output terminal Lout, and the level in the low
frequency region relatively increased to the output terminal Rout. While outputting the signal R,
the sum signal (L + R) obtained by adding the left signal L and the right signal R to relatively
increase the level in the low frequency region is output to the output terminal Fout. The output
terminal Fout further includes an attenuator (not shown) so as to further include a level
adjustment circuit for adjusting the output level of the output of the sum signal (L + R), as
described in another embodiment described later. It is good.
[0038]
The output terminal Lout of the directivity control circuit 2 is connected to the left speaker Lsp
of the speaker system 3 in normal phase. That is, the positive terminal (+) of the output terminal
Lout and the positive terminal (+) of the left speaker Lsp are connected, and the negative
terminal (-) of the output terminal Lout and the negative terminal (-) of the left speaker Lsp are
connected. The output terminal Rout of the directivity control circuit 2 is connected to the right
speaker Rsp of the speaker system 3 in positive phase. That is, the positive terminal (+) of the
output terminal Rout is connected to the positive terminal (+) of the right speaker Rsp, and the
negative terminal (-) of the output terminal Rout is connected to the negative terminal (-) of the
right speaker Rsp. Therefore, the left signal L is acoustically emitted as a sound wave from the
left speaker Lsp, and the right signal R is acoustically emitted as a sound wave from the right
speaker Rsp.
[0039]
The output terminal Fout of the directivity control circuit 2 is connected to the center front
speaker Fsp of the speaker system 3 in reverse phase. That is, the positive terminal (+) of the
output terminal Fout is connected to the negative terminal (-) of the center front speaker Fsp, and
the negative terminal (-) of the output terminal Fout is connected to the positive terminal (+) of
the center front speaker Fsp Do. The sum signal (L + R) in antiphase is acoustically emitted as a
sound wave from the center front speaker Fsp. However, as described above, the center front
speaker Fsp is provided with the sound path 34 having the sound path length d reaching the
opening 33 on the diaphragm front side. Therefore, from the opening 33 of the center front
speaker Fsp, the sound path 34 of the sound path length d is delayed by the time for the sound
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wave to transmit, and the sum is in antiphase with the sound wave acoustically radiated from the
left speaker Lsp or the right speaker Rsp. The signal (L + R) will be acoustically emitted.
[0040]
As a result, as shown in the conceptual diagram of FIG. 3, with regard to the left signal L, the
listener 4 side is set to the zero point direction by the left speaker Lsp and the center front
speaker Fsp, and the left speaker Lsp along one side of the isosceles triangle Unidirectional
acoustic radiation characteristics are realized with the back side as the beam direction. The
radiated sound wave by the left signal L and the radiated sound wave by the L signal component
in the delayed and antiphased sum signal (L + R) interfere with each other, and in one direction
determined by the left speaker Lsp and the center front speaker Fsp This is because it creates a
unidirectional zero point. Similarly, with regard to the right signal R, a single directivity in which
the listener 4 side is set to the zero point direction by the right speaker Rsp and the center front
speaker Fsp, and the back side of the right speaker Rsp along one side of the isosceles triangle is
the beam direction. The acoustic radiation characteristics of are realized. Therefore, the listener 4
located in the direction of the zero point of the unidirectional acoustic radiation characteristic
can obtain sound image localization farther from the actual position of the left speaker with
respect to the left signal L, and the listener 4 with respect to the right signal R can obtain Sound
image localization can be obtained farther than the actual position.
[0041]
Even in the case of reproducing monaural sound in which the left signal L and the right signal R
have substantially the same amplitude and phase relationship, the sound reproducing apparatus
1 of this embodiment is more than the actual arrangement positions of the left speaker Lsp and
the right speaker Rsp. The phantom sound image can be localized at a distance. In a normal
stereo audio signal such as music or broadcast, the left signal L and the right signal R have a high
ratio of including the common monaural component M. Therefore, the listener 4 located in the
direction of the zero point of the unidirectional acoustic radiation characteristic can obtain sound
image localization farther than the actual positions of the left and right speakers with respect to
this monophonic component M as well.
[0042]
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In addition, the compensation filter 5 of the directivity control circuit 2 of the present
embodiment cancels the left signal Lsp driven in the opposite phase and the left signal L canceled
due to the separation distance d between the right speaker Rsp and the center front speaker Fsp.
Alternatively, the level of the low frequency region of the right signal R may be relatively
increased in advance. The compensation filter 5 can relatively emphasize the bass component in
which the bass component is canceled among the three speakers arranged close to each other,
and can improve the balance of the sound image felt distant to the listener 4. The compensation
filter 5 compensates also for the negative phase component (for example, (L−R)) where the bass
component is likely to be canceled between the left speaker Lsp and the right speaker Rsp
arranged close to each other. You can keep
[0043]
The sound reproducing apparatus 1 of this embodiment only requires a total of three speakers
and two BTL amplifiers for reproducing stereo signals of standard left and right two channels,
and a DSP or D / A converter The digital circuit also becomes unnecessary, and compared with
the prior art as in Patent Document 2, it is possible to obtain the same effect that the stereo
sound field is easily spread to a distant place while suppressing the cost increase. Further, in the
sound reproduction device 1, the left signal L and the right signal R are respectively reproduced
by the left speaker Lsp and the right speaker Rsp. The directivity control circuit 2 does not
perform signal processing such as delaying and dividing the sum signal (L + R) from the left
signal L or delaying and dividing the sum signal (L + R) from the right signal R. The problem that
the common monaural component M is lost as if it passes through the comb filter does not occur.
[0044]
In the sound reproducing apparatus 1 of the present embodiment, the directivity control circuit 2
is provided with the phase inverter 6 and the phase is inverted by the amplifier circuit 7L, but
the phase is reversed from the center front speaker Fsp by other means and method. The
summed signal (L + R) thus generated may be acoustically emitted as a sound wave.
(Comparative example 1)
[0045]
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FIG. 4 is a diagram for conceptually explaining the omnidirectional radiation characteristics and
the reproduction sound field reproduced by the speaker unit 30 of the sound reproduction
device of the comparative example, and as in FIG. ) Shows a plan view and FIG. 4 (b) shows a side
view. The speaker unit 30 of the sound reproducing apparatus of the comparative example is an
example in the case of reproducing using only the left speaker Lsp and the right speaker Rsp
when reproducing standard left and right two-channel stereo signals. As shown in the conceptual
diagram of FIG. 4, when reproducing audio with a normal audio reproducing apparatus, sound
waves are emitted in all directions if reproduced with one speaker, so the perceived sound image
corresponds to the installation position of the speaker It becomes. The same applies to the
monaural component M common to the left signal L and the right signal R.
[0046]
FIG. 5 is a view for explaining an elongated electrodynamic speaker 20 constituting the speaker
unit 3 of the sound reproduction device 1 according to another preferred embodiment of the
present invention. Further, FIG. 6 is a view for explaining a speaker unit 3 using the
electrodynamic speaker 20 which constitutes the sound reproducing apparatus 1. As shown in
FIG. 6 (a) shows a plan view of the speaker unit 3 and FIG. 6 (b) shows a side sectional view as in
FIG. The speaker system 3 of the present embodiment and the speaker system 3 of the previous
embodiment are different in the configuration of the cabinet 3 including the left speaker Lsp, the
right speaker Rsp, and the center front speaker Fsp, and the arrangement relationship thereof. It
is common. Therefore, the same reference numerals are given to the same parts as those in the
previous embodiment, and the description and the illustration are omitted.
[0047]
As shown in FIG. 5, the electrodynamic speaker 20 of this embodiment includes a flat rectangular
diaphragm 25 with a thin rectangular shape, an edge 26 that vibratably supports the periphery
of the flat diaphragm 25, and a back surface of the flat diaphragm 25. A flat-screen flat-screen
speaker with full drive, which includes a voice coil assembly 21 fixed to the side, a damper 24 for
vibratably supporting the voice coil assembly 21, a frame 27, and a plurality of magnetic circuits
28 including magnets. is there. The voice coil assembly 21 connects three voice coils 23 in a
lattice by a bobbin 22, and the speaker 20 includes three magnetic circuits 28 corresponding to
the three voice coils 23. The thin rectangular speaker 20 has a length daL of about 12.5 cm in
the major axis direction da and a length dbL of about 4.8 cm in the minor axis direction db.
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[0048]
In the case of the present embodiment, the left speaker Lsp and the right speaker Rsp using the
electrodynamic speaker 20 are mounted on the speaker mounting surface 32 so that the flat
diaphragms 25 are aligned in the same top surface direction as illustrated. It is done. The left
speaker Lsp and the right speaker Rsp are arranged symmetrically to the listener 4. In addition,
the center front speaker Fsp is located at an intermediate position between the left speaker Lsp
and the right speaker Rsp on the speaker mounting surface, and the opening of the sound path
34 at a position forming an approximately isosceles triangle with the left speaker Lsp and the
right speaker Rsp. A central portion 33 is disposed, and is disposed closer to the listener 4 than
the left speaker Lsp and the right speaker Rsp. When viewed from the three speakers, the listener
4 is positioned in the direction of the vertex of the isosceles triangle.
[0049]
In the case of the present embodiment, since the three-speaker electrokinetic speaker 20 having
a short diameter direction length dbL shorter than the long diameter direction length daL is used
for the three speakers, these are formed at the positions forming the substantially isosceles
triangle. When placing the left speaker Lsp and the right speaker Rs in such a way that the
respective longitudinal directions da coincide with each other, and the center front speaker Fsp is
disposed at an intermediate position in the direction in which these minor directions coincide.
For example, the separation distance d (= 5.0 cm) from the center front speaker Fsp can be
shortened to substantially match the minor axis length dbL (= 4.8 cm). That is, if the frames 27 of
the elongated electrodynamic speaker 20 are adjacent to and adjacent to each other in the minor
axis direction so as not to interfere with each other, separation from the center front speaker Fsp
is required to realize unidirectional directivity of acoustic radiation characteristics. Since the
distance d can be shortened and disposed close to the left speaker Lsp and the right speaker Rs,
the distance between the speakers can be narrower compared to the round ordinary speaker as
in the previous embodiment.
[0050]
As in the present embodiment, when the substantial separation distance d between the speakers
in the speaker system 3 can be shortened, the sound path length of the sound path 34 can also
be shortened, and unidirectivity control to high frequencies is possible. Become. Since the
separation distance d is about 1/2 in the case of the present embodiment as compared with the
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previous embodiment, the frequency band in which unidirectional directivity control is possible
is also about twice (frequency at which dip occurs: about 1). 7 kHz to about 3.4 kHz). In addition,
since the elongated flat diaphragm 25 of the electrodynamic speaker 20 faces the minor axis
direction db in the direction toward the listener 4, the major axis direction da is in the lateral
direction and the diaphragm is relatively elongated. become. Therefore, in the sound reproducing
apparatus 1 of the present embodiment, since the width can be made in the direction of the zero
point in the unidirectionality, the listener 4 can enhance the effect that the sound image is felt in
the distance.
[0051]
Further, the sound reproducing apparatus 1 of the present embodiment uses three
electrodynamic speakers 20 including the flat diaphragm 25 and the voice coil assembly 21 in
the speaker system 3. In the voice coil assembly 21 of the electrodynamic speaker 20, the three
voice coils 23 are connected in a lattice shape by the bobbin 22 and divided vibration at the flat
diaphragm 25 can be suppressed. The piston vibration regeneration area is extremely wide. As a
result, compared to the prior art as in Patent Document 2, sound image localization can be
obtained better with a simpler configuration than in the actual position of the speaker.
[0052]
The sound reproducing apparatus 1 of the above embodiment changes the sense of localization
in the depth direction of the sound image so as to have a correlation with the image displayed on
the 3D display stereoscopically viewed in the depth direction of the screen, so that sound
reproduction with more realism is realized. It will be possible. That is, the sound reproduction
apparatus 1 can realize video and audio reproduction with a more realistic feeling by combining
with the 3D display. The sound reproduction device 1 may be used in combination with a 3D
display, or may be incorporated in a 3D image reproduction device (not shown).
[0053]
For example, in a stereoscopic video playback device (not shown) including at least the audio
playback device 1 and a 3D display, when viewed on the 3D display, the audio linked to the video
located on the front side of the 3D screen is on the front side The sound image can be localized
and the sound linked to the image located on the back side of the 3D screen can be sound image
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19
localized on the back side. In this case, the audio signal whose sound image is localized on the
back side is a monaural component common to the left signal L and the right signal R. For
example, in the case of using an autostereoscopic liquid crystal display (not shown) such as a
parallax barrier system, the 3D display is the front side of the cabinet 31 constituting the speaker
system 3 in the above embodiment and the listener 4 and the center front side It may be
attached at a position between the speaker Fsp. Further, also in the case of using a frame
sequential type (not shown) liquid crystal display in which the listener wears glasses in which the
left and right shutters open and close at high speed, the arrangement of the 3D display may be
the same.
[0054]
In order to change the sense of localization of the sound image in the depth direction, a level
adjustment circuit (not shown) for adjusting the level of the sum signal (L + R) output from the
output terminal Fout of the directivity control circuit 2 to the center front speaker Fsp It should
be provided. If the output level of the sum signal (L + R) from the output terminal Fout of the
directivity control circuit 2 is reduced, sound image localization can be made to the front side,
and if the output level of the sum signal (L + R) is increased, the sound image is displayed on the
back side It can be localized. The level adjustment circuit may adjust and output the relative level
of the sum signal with respect to the left signal or the right signal as described in the above
embodiments.
[0055]
Further, a decoder circuit (not shown) for extracting signal components for sound localization
from the left signal L and the right signal R to the back side is further provided, and the output of
this decoder circuit is common to the left signal L and the right signal R in the above
embodiment. (Not shown) as a monaural component to be added. A signal component for sound
image localization to the back side is output from the output terminal Fout of the directivity
control circuit 2 to the center front speaker Fsp, so that only a part of the left signal L and the
right signal R is sound image It will be localized. When the output level of the decoder circuit is
reduced, sound image localization can be performed on the front side, and when the output level
of the decoder circuit is increased, sound image localization can be performed on the back side.
[0056]
The sound reproducing apparatus according to the present invention is not only a stereo device
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that reproduces a stereo audio signal alone, or a speaker incorporated in video / audio
equipment such as a display as well as a multi-channel surround sound reproducing device, or a
speaker that reproduces audio. The present invention can also be applied to game machines
having a cabinet incorporating a game machine and game machines such as slot machines.
[0057]
DESCRIPTION OF SYMBOLS 1 sound reproduction apparatus 2 directivity control circuit 3, 30
speaker system 31 cabinet 32 speaker mounting surface 4 listener 5 compensation filter 6 phase
inverter 7L, 7R BTL amplifier circuit 20 speaker 21 voice coil assembly 22 bobbin 23 voice coil
24 damper 25 Flat diaphragm 26 Edge 27 Frame 28 Magnetic circuit Lsp Left speaker Rsp Right
speaker Fsp Center front speaker
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