JPH02277400

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DESCRIPTION JPH02277400
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
audio reproducing apparatus for AV (Audio-Visual) equipment including a speaker system, and
more particularly to a television set, a radio cassette tape recorder with a CD player, a car stereo,
etc. The present invention relates to a suitable audio reproduction device for AV equipment
capable of achieving expansion of low range reproduction. (Prior Art) As one of the conventional
speaker systems for stereo reproduction of, for example, a television set, the one having an open
rear type not enclosing the rear of the speaker as shown in FIG. 6 (A) there were. In the figure,
51 is a television set, 52 is a speaker, 53 is a back housing, 54 is a housing space, 56 is a heat
dissipation slit, 57 is a Braun tube, and 58 is a circuit board. In the speaker system of the abovedescribed configuration, the sound wave radiated to the rear of the spica 52 leaks from the heat
dissipation slit 56, and then is diffracted and travels to the front of the speaker 52. For this
reason, there has been a problem that the sound wave radiated to the front of the speaker 52 and
the sound wave diffracted and directed to the front cause interference, making it difficult to
reproduce the bass. In order to solve this problem, as shown in FIG. 6 (B), a separate cabinet 55
is inserted into the housing space 54 of the back housing 53, and the rear of the speaker 52 is
surrounded and radiated to the front of the speaker. Measures were taken to acoustically insulate
the sound wave from the sound wave directed to the rear of the speaker. However, if this
measure is taken, the housing space 54 has the Braun tube 57, the circuit board 58, etc., and the
actual housing space 54 is narrow, so the volume of the cabinet 55 becomes small and it is
difficult to reproduce bass sounds of 100 Hz or less. The problem arose. Furthermore, the
cabinets 5555 'of the left and right channels often have the same shape and the same volume,
and the volume of the cabinet 55.55- becomes even smaller, which causes the above problem. In
order to eliminate these problems, a system as described in JP-A-63242099 has been considered.
In this system, the first cabinet for supporting the speaker is housed in a second cabinet, and a
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port or a duct is formed in the first cabinet. However, when the housing space 54 is small, the
first cabinet is used. It had a drawback that it was difficult to get internal. On the other hand,
there is a 3D system (3D dimension system) in which channels for low sound are added as shown
in the block diagram of FIG. In this system, the audio signals of the left and right channels are
mixed by a mixing circuit 59 and amplified by a power amplifier 61 additionally provided
through a low pass filter (LPF) 60.
Next, the output of the amplifier 61 is reproduced by the center channel of the low sound
speaker 62. The cabinet 63 for mounting the low sound speaker 62 needs to be larger than the
volume of the cabinet 55.55-for mounting the left and right channel speakers 52.52-. Also in this
system, the housing space 54 must be enlarged. There was a problem that. Further, when the
volume of the cabinet 63 is limited, the problem that desired bass can not be reproduced and the
problem of cost increase due to the addition of the center channel have arisen. (Problems to be
Solved by the Invention) As mentioned above, although the above-mentioned prior art is not
considered about the bass range reproduction, although the bass component of the minimum
frequency of 100 to 200 Hz necessary for the television set etc. is reproduced, There has been a
problem that the 50 to 100 Hz bass component that produces a more realistic and powerful
feeling is difficult to reproduce. The above problems can be solved by connecting the audio signal
of the television set to a Hi-Fi stereo set and playing it back, but it is a good solution when
considering housing conditions, connection complexity, etc. is not. The object of the present
invention is to use a relatively small cabinet and a small diameter speaker in order to eliminate
the problems of the above-mentioned conventional apparatus and to provide an AV device such
as a television set with an all in one function. It is an object of the present invention to provide an
audio reproducing apparatus for AV equipment capable of expanding the bass range. (Means for
Solving the Problems) In order to achieve the above object, the invention of the above-mentioned
claim (1) encloses a first enclosure that encloses the rear of the first speaker and a rear of the
second speaker, And a second enclosure having a larger volume than the first enclosure, applying
an electrical signal of one channel of the stereo to the first speaker, and the other channel of the
stereo to the second speaker The low frequency components of the electric signal of the one
channel are mixed and applied to the electric signal of (1). Also, the invention of claim (2) is
characterized in that the first enclosure is removed, and a high frequency component of an
electric signal of one channel of the stereo is applied to the first speaker, and the second The
speaker is characterized in that the low frequency components of the electric signal of one of the
channels are mixed and applied to the electric signal of the other channel of the stereo. Also, in
the invention of the above (4), the first and / or second enclosure is formed into a bag shape
from a flexible material such as a plastic sheet, a rubber sheet, etc., and a sound absorbing
material is filled therein. It has a feature in
(Operation) According to the invention of claim (1), since the volume of the second enclosure is
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large, it is possible to reproduce deep bass (50 to 100 Hz) from the second speaker. Further,
according to the invention of claim (2), since the first enclosure is removed, it can be produced
inexpensively. Also, since the high frequency component of one channel of stereo is applied to
the first speaker, the sound wave that has come out of the air gap of the casing is diffracted, and
from the first speaker or the second speaker Even if it interferes with the sound wave output to
the front, the bass part of the sound wave is not canceled out, and the deep bass can be
reproduced as in the above-mentioned claim (1). Furthermore, according to the invention of
claim (4), the volume of the enclosure can be apparently increased by 20 to 30%, and the bass
can be reproduced more effectively. Hereinafter, the present invention will be described in detail
with reference to the drawings. FIG. 1 (A) shows a block diagram of a first embodiment of the
sound reproducing apparatus for AV equipment of the present invention. In the figure, 1 is a first
enclosure with a large volume, 2 is a second enclosure with a volume smaller than the first
enclosure, 3 and 4 are first and second speakers, respectively, and 5 is a deep bass radiator. , 6
and 7 are first and second power amplifiers for driving the first and second speakers 3 and 4
respectively, 8 is a low pass filter (L, P, F) for extracting a bass component, and 9 is a mixture It is
a circuit. An audio circuit 10 comprises the first and second power amplifiers 6.7, the low pass
filter 8 and the mixing circuit 9. In this embodiment, the volume of the first enclosure 1 is 5N,
and the volume of the second enclosure 2 is 2 g. As the second speaker 3.4, a speaker with an
aperture of 10 and a constant of fo = 70 Hz SQo = 0.7 was used. Also, since the music source
generally has many bass components in the right channel (Rch), the first enclosure 1 was used
for the right channel, and the second enclosure 2 was used for the left channel. In the present
embodiment, the cutoff frequency fc of the LPF 8 is selected to be about 150 Hz. Therefore, the
bass component of 150 Hz or less of the left channel (L ch) passes through the LPF 8 and is
mixed with the signal of the right channel by the mixing circuit 9 and amplified by the first
power amplifier 6. The amplified signal is reproduced by a first speaker 3 attached to the first
enclosure 1.
On the other hand, the left channel signal is amplified by the second power amplifier 7 and
reproduced by the second speaker 4 attached to the second enclosure 2. Since the present
embodiment is configured as described above, the reproduction of the deep bass is possible from
the first speaker 3 attached to the first enclosure 1 having a large volume regardless of the
relatively small aperture. It became possible. The second speaker 4 attached to the second
enclosure 2 having a small volume was able to reproduce a band of 150 Hz or more. Although
the cutoff frequency fc of the LPF 8 is selected to be about 150 Hz in the above embodiment, the
present invention is not limited to this. That is, the cutoff frequency fc of the LPF 3 can be
selected to be 80 to 200 Hz as the volume of the first and second enclosures 1 and the
performance of the first and second speakers 3 and 4. Further, without using the same aperture
and performance as the first and second speakers 3 and 4, the effect can be further enhanced by
using a unit having a larger aperture and a lower fO as the first spica 3. Next, a configuration
example of a television set embodying the first embodiment will be described with reference to
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FIG. 1 (B). FIG. 1 (B) is a schematic view of a cross section of the television set. In the figure, 11 is
a baffle for mounting the first and second speakers 3 ° 4, 12 is a cathode ray tube, 13 is a
portion of a circuit board such as a video / audio tuner, 14 is a back housing, and 15 is a back
housing 14. The housing space 16 is a sound conduit, 17 is a television set, and the other
numerals indicate the same or the same as those in FIG. 1 (A). In the present embodiment, the
circuit board 13 is concentrated on the left side of the housing space 15 formed by the back
housing 14. As a result, the right side of the housing space 15 can be enlarged, and the volume
of the first enclosure 1 can be increased. In addition, since the bass has a small directivity, the
emission port 5 of the deep bass may be provided in the baffle 11 to which the speaker 3 of the
right channel is attached, but when the cathode ray tube 12 becomes large, the deep bass is
heard from the right Since the feeling may be generated or the contents of the movie software
may be unnatural, it is preferable to provide a deep bass emission opening 5 at the lower center
of the cathode ray tube. Further, the radiation hole 5 and the first enclosure 1 may be connected
by a sound conduit 16 (a bass reflex type enclosure system). Further, a passive radiator may be
attached to the radiation port 5 (passive type enclosure method).
Depending on the arrangement of the circuit board 13, the left and right channel enclosures 1.2
are replaced to increase the volume of the left channel enclosure 2, and the right channel bass
component is mixed with the left channel mixing circuit 9 through the LPF 8. You may make it
mix via. Generally, in stereo reproduction, since spectra of different characteristics are
reproduced for both left and right channels, there is little need to completely equalize the sound
pressure frequency characteristics of the left and right channel speaker systems, and 150 to
3000 Hz with many monaural components (for example, , And voice) may be reproduced to the
same characteristics. The low directivity of 150 Hz or less is not a hindrance to playback from
either the left or right channel. Next, FIG. 2 (A) shows a second embodiment of the present
invention. This will be described with reference to (B). FIG. 2 (A) is a block diagram, and FIG. 2 (B)
is a cross-sectional view of a configuration example of a television set embodying the present
embodiment. In the first embodiment, the rear parts of the speakers 3 and 4 are enclosed by the
enclosures 1 and 2 in both left and right channels. This increases the cost of the molds of the
enclosures 1 and 2. Therefore, in the present embodiment, as shown in FIGS. 2A and 2B, only the
right channel (Rch,) is enclosed by the enclosure 1 of large volume and the rear of the speaker 3
is enclosed, and the rear of the speaker 4 of the left channel is As a back open type not enclosed,
the cost of the mold was reduced. However, if the rear portion of the speaker 4 is not enclosed,
as described in the conventional example, the sound wave of the low frequency radiated to the
rear portion of the speaker 4 leaks from the heat dissipation slit 18 of the back housing 14 and is
diffracted. Head to the front. Since the sound wave radiated to the front of the speaker 4 and the
sound wave directed to the front are in opposite phase, they cancel each other and cancel each
other out, and no bass is emitted. In addition, the speaker 3 of the right channel is similarly
adversely affected. Therefore, in the present embodiment, as shown in FIG. 2 (A), a bypass filter
(HPF) 20 is inserted in the front stage of the power amplifier 7 of the left channel so that Spica 4
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does not reproduce harmful bass components. . In the present embodiment, the cutoff frequency
of the HPF 20 is selected to be 150 to 200 Hz. Next, the operation of this embodiment will be
described. In FIG. 2 (A), the audio signal input from the left channel is removed of the bass
component by the HPF 20, amplified by the power amplifier 7, and input to the speaker 4
attached to the second enclosure 2. For this reason, the speaker 4 emits a sound wave which
does not contain the bass component as shown in FIG.
On the other hand, the bass component of 150 Hz or less of the audio signal of the left channel is
extracted by the LPF 8, mixed with the audio signal of the right channel in the mixing circuit 9,
amplified by the power amplifier 6, and attached to the first enclosure 1. Input to the speaker 3.
As a result, since the sound wave of the low frequency sound is not emitted from the slit 18 for
heat dissipation, the low frequency sound emitted from the speaker 3 is not canceled out, and as
shown by the solid line port of FIG. Next, a third embodiment of the present invention will be
described with reference to FIG. In the figure, 21 is a first enclosure in which a flexible plastic,
rubber or the like sheet is formed into a bag shape, 22 is a second enclosure formed of a similar
material, and 23 is a shape of the enclosure 21.22. The sound absorbing material is uniformly
filled therein, and the other reference numerals indicate the same or the same as in FIG. 1 (B). As
the sound absorbing material 23, for example, a synthetic material in a cotton-like shape or an
open-cell foam-like substance can be used. In the present embodiment, the sound absorbing
material 23 is filled in the enclosure 21.22 so that the shape of the enclosure 0-ja 21.22 can be
made into a desired shape. Also, since the sound absorbing material 23 or the enclosure 21.22 is
uniformly filled, the action of air inside the enclosure 21.22 physically changes from adiabatic
change to isothermal change, so that constant pressure specific heat and constant volume
specific heat The ratio γ is γ = 1.1 to 1.2 (in air, γ-1 and 4). For this reason, the volume V of
the enclosure 21. 22 acts as if it were apparently increased by 20 to 30%, and the bass expansion
is greatly improved. Further, according to the present embodiment, since the shape of the
enclosure 21 ° 22 can be formed into a desired shape, the housing space formed by the back
housing 14 can be used without waste. Also, if the circuit board is changed in size, mounted, or
changed in position, and the back housing 14 is changed in shape, it is possible to easily cope
with the need to change the shape of the enclosure 21 ° 22. Moreover, when a foam-like sheet
is used as the material of the enclosure 21.22, an effect of reducing abnormal noise such as
chattering noise generated when the speakers 3 and 4 are driven can be obtained. Further, as
shown in FIG. 5, when the bag-like enclosure 21.22 is provided with a brim 24 also serving as a
backing and is fixed to the baffle 11 together with the speakers 1 and 2, the degree of sealing is
increased. It is more effective. Furthermore, the lowest resonance frequency fO of the speakers 3
and 4.
Even if design changes such as the effective mass mo of the resonance sharpness Qos vibration
system occur, the volume of the enclosure 21 ° 22 can be easily changed, and an optimum
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enclosure design can be made according to the speaker. When there is a risk that the enclosure
21.22 may be ignited by the heat generation of the circuit board 10, a self-extinguishing material
or a heat-resistant material may be used. It goes without saying that the enclosure 21.22 of this
embodiment is effective not only in combination with the first or second embodiment, but also
when it is used in place of the conventional speaker cabinet. Although the said Example was an
example which applied this invention to the television set, this invention is not limited to this, The
audio ¦ voice for AV apparatuses, such as a radio cassette tape recorder with CD player with a
small housing space, a car stereo, etc. It can also be applied to a playback device. (Effects of the
Invention) According to the invention of the above-mentioned claim (1), the electric signal of one
of the left and right channels of the stereo and the other are taken in the enclosure having the
large volume (= 7 parts). Since the electric signal mixed with the low frequency component of the
electric signal of the channel is applied, there is an effect that the deep bass (50 to 100 Hz) of
100 Hz or less can be reproduced. Further, according to the invention of claim (2), in addition to
the effect possessed by the claim (1), there is an effect that it can be manufactured inexpensively.
In addition, there is also an effect that it is not necessary to enlarge the casing of the AV device.
Furthermore, according to the invention of claim (4), since the enclosure is formed of a flexible
sheet-like material and is filled with a sound absorbing material, the volume of the enclosure is
apparently 20. There is an effect to increase by 30%, and it is possible to greatly improve the
effect of bass reproduction enlargement.
[0002]
Brief description of the drawings
[0003]
1 (A) and 1 (B) are respectively a block diagram and a structural schematic view of an
embodiment of the present invention, and FIGS. 2 (A) and 2 (B) are a block diagram and a second
embodiment of the present invention, respectively. A structural schematic diagram, FIG. 3 is a
sound pressure frequency characteristic diagram showing the effect of the present invention, FIG.
4 is an imitation schematic diagram of the third embodiment of the present invention, and FIG. 5
is the embodiment shown in FIG. FIG. 6 (A) and FIG. 6 (B) are structural schematic views showing
a modified example, and FIGS. 7 (A) and 7 (B) are block diagrams showing the conventional
example.
1.2 · · · enclosure, 3, 4, · · · speakers, 5 · · · bass radiation port, 6, 7 · · · power amplifier, 8 · · ·
Lobass filter, 9 · · · mixed circuit, 10 · · · · · · Audio circuit, 11 · · · baffle, 12 · · · CRT · 13 · circuit
board, 14 · · · · · · · · · · Back housing, 15 · · · Housing space, 21.22 · · · · · · · · · · ·・ Sound absorbing
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material, 24 ・・・ Brim of enclosure. Attorney Attorney Hiraki Tsutohito 1 other person
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