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JPH0290893

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DESCRIPTION JPH0290893
[0001]
TECHNICAL FIELD The present invention relates to a speaker system having an acoustic pipe on
one side of a speaker unit. One of the prior art techniques for expanding the bass range of prior
art loudspeaker systems is the acoustic maze form. Hereinafter, a conventional acoustic maze
speaker system will be described with reference to the drawings. FIG. 6 is a structural crosssectional view of the above speaker system. In FIG. 6, 1 is a cabinet, 2a and 2b. 2c, 2d and 2e are
partition plates provided on the front and back plates of the cabinet 1, 3 is an opening provided
on the lower portion of the front plate of the cabinet 1, and 4 is a speaker unit provided on the
top of the front plate is there. The operation of the acoustic maze speaker system configured as
described above will be described below. Partition plate 2 a provided in the cabinet 1. 2b, 2c, 2d
and 2e constitute an acoustic tube, and the sound emitted from the back of the speaker unit 4 is
guided to the above-mentioned acoustic tube and emitted from its opening. The acoustic tube
resonates at a specific frequency determined by its total length. Assuming that the total length of
the acoustic tube is L and the speed of sound in the air is C, resonance frequency fn = C / 4Lx (2n
+ 1), where nQ, 1, 2. · · · · · · N, Ha wavelength becomes n = O occurs equally be resonance
acoustic pipe length, significant in the vicinity acoustically increased sound emitted bass
reproduction limit the opening 3 of the acoustic tube Efficiency can be improved. In addition, at a
frequency at which the 34 wavelengths are equal to the acoustic pipe length, the speaker unit 4
emitted from the opening 3 of the acoustic pipe, which is inherently in reverse phase to the
sound emitted from the front of the speaker unit 4 and the sound from the front. The sound from
the back of is added in phase due to the half wavelength phase delay and is added to increase the
sound pressure level. Further, when n = 2, the% wavelength is equal to the acoustic pipe length,
and the resonance phenomenon occurs in the acoustic pipe, and the sound n acoustically
increased n is emitted from the aperture 3 of the acoustic pipe as in the case of n-0 . Therefore, a
highly efficient speaker system can be realized in the low frequency range. SUMMARY OF THE
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INVENTION However, in the configuration as described above, the frequency equal to the I ′ ′
i eight-wavelength echo tube length becomes the bass reproduction limit frequency as the
speaker system, and therefore the acoustic tube is used to reproduce the bass region. It has to be
long, and the cabinet has a large size. In addition, when used as a speaker system for bass
reproduction, it is desirable to use up to near the frequency where the% wavelength is equal to
the acoustic pipe length as a reproduction limit of the treble range as shown in FIG. In the
conventional method, the acoustic activity rate at the time of resonance of the acoustic tube
increases with the increase in frequency, so the sound pressure peaks near the frequency where
the% wavelength becomes equal to the acoustic tube length, and this band is flattened by the
electrical circuit. It was difficult and deteriorated the characteristics of the Spica system and
lowered the sound quality.
In view of the above problems, the present invention extends the reproduction limit of the bass
region without lengthening the acoustic tube, and suppresses the peak of the sound pressure in
the vicinity of the frequency at which the% wavelength becomes equal to the acoustic tube
length. A speaker system having characteristics is provided. Means for Solving the Problem In
order to achieve this object, the speaker system of the present invention comprises an acoustic
tube which is continuously extended from one side of the speaker unit and whose opening is
open to the sound field space, and the upper front acoustic tube The substantially central portion
of the speaker is configured to set one prayer larger than the cross-sectional area at the speaker
unit side and the opening of the acoustic tube. In the present invention, since the cross-sectional
area of the substantially central portion of the acoustic pipe is a dog at both ends thereof, the
volume in the acoustic pipe increases, the equivalent acoustic capacity increases, and the
frequency at which the resonance phenomenon occurs in the acoustic pipe decreases. It is
possible to obtain a sound-incident characteristic substantially equivalent to a lengthened
acoustic tube. In addition, the volume in the acoustic tube, that is, the reactance component
exhibited by the acoustic capacity blocks the middle and high frequency range radiated from the
speaker unit. The peak of the peak is suppressed by one. EXAMPLES Examples of the present
invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a
spica system according to a first embodiment of the present invention. In FIG. 1, 5 is a speaker
unit, 6 is a first sound W W joined to the back surface of Sbika uninot 5, 5 is a second acoustic
tube having a cross-sectional area equal to that of the first acoustic tube, and 8 is The two
acoustic tubes are joined at both ends and positioned approximately at the center of the two, and
A third acoustic tube having a cross-sectional area S2 larger than the cross-sectional area S of the
second acoustic tube 6. A ring-shaped pedestal 9 provided at the lower end of the acoustic tube
3, an opening of the 101'j acoustic tube 7. The diffuser 11 has a convex center at the center, and
11 is a pipe composed of a plurality of three or more, which is provided between the pedestal 9
and the diffuser 10 and holds the entire speaker system vertically. The operation of the speaker
system configured as described above will be described below. The sound tube 6 ° 7.8 is rigidly
coupled and disposed as a single sound tube on the back of the speaker unit 5, the opening of
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which is directed to the floor and with the diffusion plate 10 by means of a pipe 11 supporting
the entire speaker system Is held with a gap. Therefore, the sound from the back of the speaker
unit 5 passes through the sound tube 6, 8.7 and is emitted to the floor surface from the opening
through the diffusion plate.
The acoustic tube 8 having a cross-sectional area S2 larger than the cross-sectional area S1 of
the acoustic tubes 6 and 7 increases the volume in the acoustic tube, thereby increasing the
equivalent acoustic capacity and reducing the frequency at which the resonance phenomenon
occurs in the acoustic tube. FIG. 2 (compare the sound pressure frequency characteristics and the
amplitude characteristics of the diaphragm in the case where a conventional sound tube with a
cross section of-and the sound tube of the present invention are used. At the time of resonance of
the acoustic tube, the acoustic impedance of the acoustic tube viewed from the speaker unit 5
becomes very large, and this is an anti-resonance operation for stopping the movement of the
diaphragm. The frequency at which the phenomenon occurs is known. From FIG. 2, it can be seen
that the acoustic tube of the present invention reduces the antiresonance frequency and
increases the sound pressure level in the bass limit range. Furthermore, the sound pressure peak
in the vicinity of the frequency at which the% wavelength is equal to the sound tube length in the
conventional sound tube is suppressed in the sound tube of the present invention. This is
because the volume in the acoustic tube, that is, the reactance component exhibited by the
acoustic capacity operates as a high cut filter. Here, the cross-sectional area and the length of the
acoustic tube 8 in the central part with a large cross-sectional area are very important. Therefore,
first, the length of the entire acoustic tube obtained by combining the acoustic tubes 6 and 7.8 is
2 and the length of the acoustic tube 8 is 22, and the change of the sound pressure frequency
characteristics due to the ratio 21 / s is shown in FIG. Here, the ratio S2 / 51 = 2 of the crosssectional area of the acoustic tube is fixed). In order to lower the bass reproduction limit and
ensure the flattening of the sound pressure in the bass reproduction band, it is sufficient if 0.2 ≦
'1 / 2 ≦ 0.8, and the target is set within this condition. You can select the sound you have.
Next, FIG. 4 shows the change in sound pressure frequency characteristics according to the ratio
S2 / S1 of the cross-sectional area S1 of the acoustic tubes 6, 7 and the cross-sectional area S2 of
the acoustic tube 8 (here, the length of the acoustic tube is The ratio is Q2 / 121 = 0.2. The
higher the S2 / S1, the lower the bass limit frequency, and the higher the sound pressure level at
this frequency, but due to the acoustic capacity, the effect of the i-pass filter is increased, and the
middle and high range playback limit within the playback band And since the sound pressure
level is lowered, it is desirable that 2 ≦ S2 / S1 ≦ 5. FIG. 5 shows a cross-sectional view of a
spica / stem according to a second embodiment of the present invention. In FIG. 5, 12 is a
speaker unit, 13 is a first acoustic pipe coupled to the upper surface of the speaker unit, 14 is a
second acoustic pipe having a cross section larger than sound -71 'and 13 and 15 is a center The
top plate is concave, 16 is a third acoustic tube connected to the outer periphery of the top plate
15, 17 is a fourth acoustic tube joined to the lower end of the acoustic tube 16, and the opening
is a horn open to the outer periphery It has become a state.
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18 is a pedestal provided at the lower end of the acoustic tube 16, 19 is a diffusion plate holding
the spicauninot 12 in a central recess, 2o is provided between the pedestal 18 and the diffusion
plate 20, and supports the i sound tube 16.17. It is a pipe. The operation of the speaker system
configured as described above will be described below. In the figure, the cross-sectional area
between the outer periphery of the acoustic tube 14 and the inner periphery of the acoustic tube
16 is equal to the cross-sectional area of the acoustic tube 14. Similarly, the cross-sectional score
between the outer periphery of the acoustic tube 13 and the inner periphery of the acoustic tube
17 is set equal to the cross-sectional area of the acoustic tube 13. Immediately, this speaker
system has a structure in which the acoustic tube is not folded straight, but is folded at the
center. Therefore, the basic operation of the speaker system can be the same as that of the first
embodiment of the present invention shown in FIG. A major difference from the first embodiment
is that the openings of the speaker unit and the acoustic tube are on the same floor. In the
implementation I 91 of 4S1, only the opening of the acoustic tube was directed to the floor
surface, so there was little improvement in the activity rate due to the buckling effect of the floor
surface. However, in the embodiment of the second embodiment, since both the speaker unit and
the opening are on the floor surface, the baffle effect is large, and it is possible to improve the
efficiency in the low range as compared with the first embodiment. Still, in the installation of the
loudspeaker system, it is possible to lower the overall height of the loudspeaker system
according to the second embodiment when its height is limited. As described above, according to
the present invention, the acoustic tube is formed on one side of the speaker unit, and the crosssectional area sound of the acoustic tube at substantially the center of the speaker unit and the
cross-sectional area of the acoustic tube at the opening thereof. By increasing the frequency, the
bass reproduction limit frequency is lowered without changing the length of the acoustic pipe,
and the sound pressure level at that frequency is raised, and the high sound area limit frequency
in the bass reproduction band is increased. It is possible to realize a speaker system having high
efficiency and flat bass characteristics by suppressing the peak of sound pressure.
[0002]
Brief description of the drawings
[0003]
FIG. 1 is a cross-sectional view of the structure of the Svica system according to the first
embodiment of the present invention, FIG. 2 is a graph showing the sound pressure of the
speaker system and the conventional speaker system and the amplitude frequency characteristics
of the diaphragm, FIG. The figure shows the design conditions and sound pressure frequency
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characteristics of the acoustic tube of the present invention, FIG. 5 is a structural sectional view
of the speaker system in the second embodiment of the present invention, and FIG. 6 is a
structural sectional view of the conventional loudspeaker system. .
5.12 ...... Suhi - Kayuniso), 6,7,8 ° 13.14,16.17 ...... acoustic tube, 10, 12 ...... diffuser. Name of
agent Attorney Attorney Shigetaka and one other person, Thailand O- ˜ -1Qn: Treatment 2nd
Figure □ Akira Honke 11 1 1 1 Follower Hee 5. Skin length ([email protected] tau everyone & Minami (1-1,
破 (JJr)---3t / 3t = 5a ■ 5a 1 height <Ih う
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