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DESCRIPTION JP2006173943

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DESCRIPTION JP2006173943
PROBLEM TO BE SOLVED: In a small-sized thin display device incorporating a bass reflex speaker
system audio reproduction apparatus, a stereo by means of medium / high frequency band
voices emitted and emitted from left and right voice channel bass reflex ports arranged close to
each other. A means is provided for preventing deterioration of left and right audio channel
separation characteristics at the time of program reproduction. SOLUTION: By setting the sound
emission axis of the bass reflex port opening to the front lower side of the front surface of the
thin display device, a medium / high frequency voice with strong directional characteristics
reaching a viewer located on the front surface of the thin display device Is a thin display device
equipped with a bass reflex speaker system with high bass reproduction capability, which has
more attenuation than voice in the low frequency range, prevents deterioration of the left and
right audio channel separation characteristics during stereo program playback, and To visually
appeal to the user. [Selected figure] Figure 1
Low-profile display with built-in bass reflex speaker system
[0001]
The present invention relates to a bass reflex speaker system for improving the low frequency
range reproduction capability of an audio reproduction device incorporated in a thin display
device, and more specifically, the sound emission axis of the bass reflex port is the lower front of
the thin display device. By this, it is possible to prevent the deterioration of the left and right
audio channel separation characteristics at the time of reproducing the stereo program by the
medium / high frequency range audio leaked from the bass reflex port and arrange the opening
of the bass reflex port in the viewer's visible area. Thus, it is possible to visually appeal to the
user that the product is equipped with a bass reflex speaker system with excellent reproduction
ability in the low frequency range.
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[0002]
As means for improving the audio reproduction capability in the low frequency range output
from the audio reproduction apparatus, the aperture of the speaker diaphragm, the rigidity of the
speaker diaphragm, the flexibility of the diaphragm support member of the speaker diaphragm,
the speaker diaphragm support structure And a large-aperture speaker that can be realized by
storing a large-aperture speaker that maintains a low minimum resonance frequency determined
by factors such as the mass of the entire vibration system including the energizing voice coil for
driving the speaker diaphragm. However, a bass reflex speaker system using Helmholtz
resonance has been devised, and the combination of a low-aperture speaker whose minimum
resonance frequency of the loudspeaker is not sufficiently low, and a low-volume speaker box
can also reproduce good low-frequency sound. It became possible to realize the characteristics.
Therefore, the bass reflex speaker system is widely used in a small bookshelf type component
audio product or the like designed for a space saving environment.
[0003]
FIG. 4 (a) is a front view showing a sound output portion of a conventional bass reflex speaker
system according to the related art of a thin display device incorporating a bass reflex speaker
system, and FIG. 4 (b) is a side view. In FIG. 4 (a), 12a shows a left speaker part and 12b shows a
right speaker part. In order to realize good left and right audio channel separation characteristics
at the time of stereo program reproduction, it is necessary to increase the separation distance
between the left speaker unit 12a and the right speaker unit 12b as much as possible. Usually, it
is disposed at the left and right ends of the cabinet.
[0004]
In FIG. 4A, reference numeral 13a denotes a left bass reflex port, and 13b denotes a right bass
reflex port. As described above, the left and right speakers 12a and 12b are respectively disposed
at the left and right ends of the front face of the cabinet 14. As a result, the positions of the left
bass reflex port 13a and the right bass reflex port 13b are necessarily the cabinet 14 It is closer
to the center of the front, and the left and right audio channel separation characteristics output
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from the left and right bass reflex ports are degraded. However, the ability to identify the
direction of arrival of the auditory sense is not a practical problem because it is inferior to the
voice in the low frequency band mainly output from the bass reflex port compared to the voice in
the medium / high frequency band.
[0005]
FIG. 4C shows a block diagram of the audio output circuit. The left channel audio signal input
from the left channel audio signal input terminal 12c drives the left speaker unit 12a via the left
channel preamplifier 12e and the left channel power amplifier 12g. The left speaker unit 12a
constitutes a Helmholtz resonance box for emphasizing the low frequency range indicated by a
broken line in FIG. 4C, and is accommodated in a small speaker box provided with the left bass
reflex port 13a. The speaker box is built in the cabinet 14. The right channel audio circuit is also
separately provided with the same configuration as that of the above left channel audio circuit to
realize a two channel audio output function.
[0006]
The bass reflex speaker system is a technical means for achieving emphasized and rich low
frequency range voice output, and hence the bass reflex port mainly outputs low frequency range
voice. However, the voice in the middle / high frequency range also leaks although at a low level.
Even if the sound in the middle / high frequency range leaked from the bass reflex port is low
level, the left and right bass reflex ports are close, which causes the degradation of the left and
right voice channel separation characteristics, and the stereo acoustic effect at the time of stereo
program playback Lose In FIG. 4 showing an embodiment of the prior art, the sound emission
axis directions of the left bass reflex port 13a and the right bass reflex port 13b are arranged
close to each other on the front of the cabinet 14 of the thin display device. Because of this, audio
output in the middle / high frequency range leaking from the left bass reflex port 13a and the
right bass reflex port 13b degrades the left and right voice channel separation characteristics
and causes loss of stereophonic effects during stereo program playback. .
[0007]
Therefore, in another embodiment of the prior art shown in FIGS. 5 (a) to 5 (c), in addition to the
left speaker portion 22a and the right speaker portion 22b, a low frequency is provided in order
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to improve the audio reproduction capability in the low frequency range. A dedicated woofer 25
for selectively outputting the voice of the region is mounted, and a bass reflex speaker system is
applied to the woofer 25. The bass reflex port 23 is disposed on the bottom of the cabinet 24 so
that the sound emission axis direction from the bass reflex port 23 is directed from the bottom of
the thin display device to the installation plane. However, since the mutual distance between the
bass reflex port 23 and the installation surface on which the thin display device is installed
becomes small, the radiation impedance of the low frequency sound from the bass reflex port 23
depending on the components of the installation surface or the surface condition of the
installation surface. Are affected, and the sound effects fluctuate. Furthermore, as shown in FIG.
5D, the left channel low pass filter 26a, the right channel low pass filter 26b, the superimposing
circuit 27, and the low frequency range speech are further extracted to extract the low frequency
range speech signal. It requires a dedicated woofer power amplifier 28 and has a problem that
the circuit configuration is complicated. JP, 2000-287287 "Speaker system and display device
using the same"
[0008]
In a thin display device equipped with a bass reflex speaker system capable of playing low
frequency range voices giving rich sense of sound when playing back an audio program, the user
can visually recognize the bass reflex port as a low frequency range speech emitting section By
arranging on the front of the cabinet, it is possible to appeal to the user the excellent
functionality possessed by the audio reproduction device built into the thin display device.
However, mid- and high-frequency range audio of the left and right audio channels of the stereo
program leaks from the left and right bass reflex ports arranged in close proximity, and when
emitted, the left and right audio channel separation characteristics deteriorate and stereo The
stereophonic effects of the program are impaired.
[0009]
In a thin display device incorporating a bass reflex speaker system as an audio reproduction
device, the sound emission axis direction from the bass reflex port is an angle of more than 0
degrees and less than 90 degrees with respect to the display screen of the thin display device. By
placing it inside, by utilizing the nature that the directivity of the sound differs depending on the
audio frequency, the medium / high frequency range audio leaking from the bass reflex port is
selectively attenuated and located in front of the thin display device It prevents reaching the
viewer's ear, and the stereophonic sound effect during stereo program playback is not impaired.
[0010]
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In addition, by providing a bass reflex port opening on the curved surface having the center of
curvature obliquely downward at the lower front center of the cabinet of the thin display device,
the user can visually recognize the bass reflex port as a low frequency sound emitting section.
Also, it is possible to appeal to the user the excellent functionality possessed by the audio
playback device built into the thin display device.
[0011]
Further, the speaker box is floatingly fixed to the front cabinet and / or the rear cabinet via a
buffer member, so that the airtightness of the bass reflex port is maintained, and the vibration
from the speaker box is transmitted to the cabinet and thin display Problems such as effects on
the screen of the device are also suppressed.
[0012]
Further, by arranging the sound emission axis of the speaker and the sound emission axis of the
bass reflex port at a predetermined angle in the state of the speaker box, processing on the
cabinet side of the thin display device is simplified and the thin display device Assembly is also
easy.
[0013]
The directivity of the sound emitted from the speaker differs depending on the frequency, and in
the medium / high frequency band of approximately 3000 Hz or more that leaks from the bass
reflex port of the bass reflex speaker system that mainly outputs the low frequency band, the low
frequency band The directivity is stronger than that of voice, and the radiation is strongly
emitted in the sound emission axis direction but is rapidly attenuated in the angular direction
away from the axis.
Therefore, the low level medium / high frequency range audio leaking from the bass reflex port
arranged with the sound emission axis directed downward and forward of the cabinet does not
directly reach the ears of the viewer located in front of the cabinet It does not cause deterioration
of the left and right audio channel separation characteristics, and it is also possible to avoid that
the acoustic effect fluctuates under the influence of the installation surface on which the thin
display device is installed.
[0014]
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Also, the bass reflex port is provided on a curved surface having a center of curvature obliquely
downward at the lower center of the front cabinet, allowing the user to visually recognize the
bass reflex port as a sound emitting portion for low frequency range speech, and the thin display
It is also possible to appeal to the user the excellent functionality of the audio playback device
built into the device.
[0015]
Further, by arranging the sound emission axis of the speaker and the sound emission axis of the
bass reflex port at a predetermined angle in the state of the speaker box, processing on the
cabinet side of the thin display device is simplified and the thin display device Assembly is also
easy.
[0016]
The case where the embodiment of the present invention is applied to a liquid crystal television
will be described below based on the drawings.
1 (a) is an external perspective view of the front of the liquid crystal television, FIG. 1 (b) is a
front view of the liquid crystal television, and FIG. 1 (c) is a bottom view of the liquid crystal
television.
In FIG. 1, 1 is a liquid crystal television, 1a is a liquid crystal display panel for image display, 2a is
a left speaker unit, 2b is a right speaker unit, 3a is a left bass reflex port of a bass reflex speaker
system, 3b is a right bass reflex port, 4 is a cabinet , 5 indicates a stand.
[0017]
FIG. 3 is a view showing a speaker box disposed on the right side of the liquid crystal television
1. FIG. 3 (a) is an external perspective view of the speaker box, and FIG. 3 (b) is a broken line H-H
in FIG. 1 (b). It is a longitudinal cross-sectional perspective view of the liquid crystal television 1
lower part cut | disconnected along the cutting plane line shown by these.
In FIG. 3, 4a is a front cabinet, 4b is a rear cabinet, 4c is a bass reflex port opening, 6 is a speaker
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box, 6a is a loudspeaker, 6b is a bass reflex port, 6c is a duct, 6d is a floating rubber, and 6e is a
rubber spacer Indicates
The speaker box 6 is configured as a Helmholtz resonance box in which the speaker 6a and the
port 6b are integrated.
Although the illustration of the speaker box disposed on the left side is omitted, the positions of
the speaker 6a and the port 6b of the speaker box 6 disposed on the right side are disposed in
reverse, and are similarly configured as Helmholtz resonance boxes.
[0018]
In addition, the liquid crystal display panel 1a for image display and the mounting surface of the
speaker 6a and the left speaker are mounted substantially parallel, and the left bass reflex port
3a and the right bass reflex port 3b have a curvature obliquely downward at the lower center of
the front cabinet 4a. The curved surface having a center is provided at an angle of about 40
degrees with the surface of the liquid crystal display panel 1a. Further, the sound emission axis
of the speaker 6a and the sound emission axis of the port 6b in the speaker box 6 are also
provided at an angle of about 40 degrees.
[0019]
In the speaker box 6, after inserting the rubber spacer 6e in the port 6b portion, the floating
rubber 6d and the rubber spacer 6e are respectively provided to the three bosses for attaching
the speaker box 6 provided in the front cabinet 4a and the bass reflex port opening 4c. After
performing the alignment of, fixed with screws. Although the rear cabinet 4b is fixed to the front
cabinet 4a in the final assembly process of the liquid crystal television 1, the speaker box 6 is
fixed to only the front cabinet 4a.
[0020]
The rubber spacer 6e maintains the secrecy between the port 6b and the right bass reflex port
3b, and is also floatingly fixed to the front cabinet 4a together with the floating rubber 6d,
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thereby suppressing the propagation of the vibration from the speaker box 6 to the cabinet 4 ing.
The speaker box located in the left speaker unit 2a is also assembled similarly to the right
speaker unit 2b, and is separately provided separately for the left and right audio channels.
[0021]
The left bass reflex port 3a and the right bass reflex port 3b mainly output low frequency range
voices, but medium / high frequency range voices of about 3000 Hz or more are also leaked
although they are at a low level compared to low frequency voices. It is output. However, the
voice in the middle / high frequency range is more directional than the voice in the low
frequency range, and emits strongly in the sound emission axis direction but rapidly attenuates
in the angular direction away from the sound emission axis. Therefore, the low-level mid / high
frequency range audio leaked from the bass reflex ports 3a and 3b disposed with the sound
emission axis directed to the lower front of the cabinet 4 to the ears of the viewer located on the
front of the cabinet 4 It does not directly reach, and does not cause deterioration of the left and
right audio channel separation characteristics during stereo program playback.
[0022]
Fig.2 (a) is a longitudinal cross-sectional view of the main body of the liquid crystal television 1
cut | disconnected along the cutting plane line shown by dashed-dotted line CC in FIG.1 (b). The
sound emission axis from the left bass reflex port 3a disposed on the bottom surface of the
cabinet 4 is directed downward in the front of the cabinet 4 as indicated by a dashed-dotted
arrow "A" in FIG. 2) in the direction from the left bass reflex port 3a to the viewer 7 located in
front of the liquid crystal television 1 as indicated by the dashed arrow “B” is offset by an
angle “α” shown in FIG. ing.
[0023]
FIG. 2B schematically shows the directivity characteristics of the voice in the low frequency range
mainly output from the left bass reflex port 3a by a broken line as a vector diagram. As shown in
FIG. 2B, the sound pressure level "E" in the low frequency range reaching the viewer 7's ear is
substantially equal to the sound pressure level in the sound emission axis direction "D" of the
bass reflex port 3a. Become. However, as shown in the directivity characteristic of the voice in
the middle / high frequency range in FIG. 2C, the sound pressure level “G” in the middle / high
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frequency range reaching the ear of the viewer 7 corresponds to that of the bass reflex port 3a.
The sound pressure level in the sound emission axis direction "F" is significantly attenuated.
[0024]
As described above, by directing the sound emission axis direction of the left bass reflex port 3a
downward on the front surface of the cabinet 4, it is possible to selectively lower the sound
pressure level in the middle / high frequency range reaching the viewer 7 As a result, it is
possible to prevent the deterioration of the left and right audio channel separation characteristics
and to avoid the loss of the stereophonic sound effect at the time of reproducing the stereo
program. In the above description, although the left bass reflex port 3a is taken as an example, it
is not to say that the same applies to the right bass reflex port 3b.
[0025]
In addition, the bass reflex ports 3a and 3b are provided on a curved surface having a center of
curvature obliquely downward at the lower center of the front cabinet 4a at an angle of about 40
degrees with the surface of the liquid crystal display panel 1a, thereby allowing low frequency
range speech The user can visually recognize the bass reflex ports 3a and 3b as the sound output
unit, and can appeal to the user the excellent functionality possessed by the audio reproduction
device incorporated in the thin display device.
[0026]
In the present embodiment, the bass reflex ports 3a and 3b are provided on a curved surface
having a center of curvature obliquely downward at the lower center of the front cabinet 4a at an
angle of about 40 degrees with the surface of the liquid crystal display panel 1a. As described
above, the same effect can be obtained by providing the cabinet 4 in the front, top, bottom, left,
and right peripheral portions.
[0027]
Although the present invention describes a thin display apparatus incorporating a bass reflex
speaker system as an embodiment, it is difficult to place the back of the speaker box in contact
with the wall surface and to dispose the bass reflex port on the back of the loudspeaker box It is
also suitable to be applied to a wall-mounted bass reflex speaker system.
[0028]
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(A) of the liquid crystal television which is an Example of this invention is an external appearance
perspective view, (b) is a front view of a liquid crystal television main body, (c) is a bottom view
of a liquid crystal television main body.
(A) is a longitudinal sectional view cut along a cutting line C-C indicated by a chain line in FIG. 1
(b), (b) is a directivity characteristic in low frequency range speech, and (c) is a middle / high
frequency range speech It is a schematic diagram which shows the directional characteristic in.
(A) of the speaker box which is an Example of this invention is an external appearance
perspective view, (b) is a longitudinal cross-sectional perspective view of the liquid-crystal
television lower part cut along the cutting plane line HH in FIG.1 (b).
(A) is a front view showing an example of the prior art, (b) is a side view, and (c) is an audio
circuit block diagram. (A) is a front view showing another embodiment of the prior art, (b) is a
side view, (c) is a bottom view, and (d) is an audio circuit block diagram.
Explanation of sign
[0029]
1: LCD TV 1a: Liquid crystal display panel 2: Speaker 2a: Left speaker 2b: Right speaker 3: Bass
reflex port 3a: Left bass reflex port 3b: Right bass reflex port 4: Cabinet 4a: Front cabinet 4b:
Rear cabinet 4c: Bass reflex port opening 5: stand 6: speaker box 6a: speaker 6b: port 6c: duct
6d: floating rubber 6e: rubber spacer 7: viewer 12: speaker unit 12a: left speaker unit 12b: right
speaker unit 12c: left channel Audio signal input terminal 12d: Right channel audio signal input
terminal 12e: Left channel preamplifier 12f: Right channel preamplifier 12g: Left channel power
amplifier 12h: Right channel power amplifier 13: Bass reflex port 13 a: left bass reflex port 13b:
right bass reflex port 14: cabinet 22: speaker section 22a: left loudspeaker section 22b: right
loudspeaker section 22c: left channel audio signal input terminal 22d: right channel audio signal
input terminal 22e: left channel preamplifier 22f: right channel preamplifier 22g: left channel
power amplifier 22h: right channel power amplifier 23: bass reflex port 24: cabinet 25: woofer
26: low pass filter 26a: left channel low pass filter 26b: right channel low pass Filter 27:
Superimposed circuit 28: Woofer power amplifier
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