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DESCRIPTION JP2005130032

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DESCRIPTION JP2005130032
PROBLEM TO BE SOLVED: To provide a speaker device capable of setting a desired resonant
frequency by varying the resonant frequency. SOLUTION: In a speaker device 1 including a
speaker 2, an acoustic volume 4 to which the speaker 2 is attached, and an acoustic tube 5
attached to the acoustic volume 4, a sound emission side opening of the acoustic tube 5 is used
to change a resonance frequency. By providing the acoustic pipe length variable device 6, the
length of the acoustic pipe can be changed to change the resonance frequency. [Selected figure]
Figure 1
Speaker device
[0001]
The present invention relates to a speaker device, and more particularly to a speaker device
responsible for bass reproduction.
[0002]
For example, a subwoofer device has been proposed as a speaker device that reproduces a bass
or bass range (see, for example, Patent Document 1).
Such a loudspeaker device comprises an acoustic tube, the resonant frequency of which is
determined by the length of the acoustic tube. Japanese Patent Application Laid-Open No. 9275595
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[0003]
However, since the length of the acoustic tube is fixed, the resonant frequency is fixed. For this
reason, the bass frequency to be reproduced is fixed, and the desired reproduction frequency can
not be changed. The subject of this invention is mentioned as an example to provide the speaker
apparatus which can set a desired resonant frequency by varying a resonant frequency.
[0004]
The speaker device according to claim 1 includes a speaker, an acoustic volume portion to which
the speaker is attached, and an acoustic tube attached to the acoustic volume portion, wherein
the length of the acoustic tube at the sound emission side opening portion of the acoustic tube
An acoustic pipe length variable device for changing a resonance frequency for changing
[0005]
Hereinafter, embodiments of the present invention will be described with reference to the
drawings.
First Embodiment FIG. 1 shows a configuration of a speaker apparatus according to a first
embodiment of the present invention. As illustrated, the speaker device 1 includes an acoustic
volume 4 defined by a drive speaker 2 (speaker) and a housing 3 to which the drive speaker 2 is
attached, and an acoustic tube (first acoustic tube) 5 attached to the acoustic volume 4 And a
second acoustic pipe (acoustic pipe length variable device) 6 attached to the sound emission side
opening of the acoustic pipe 5. The acoustic volume 4, the acoustic tube (first acoustic tube) 5
and the second acoustic tube 6 constitute a Helmholtz resonator.
[0006]
In FIG. 1, the resonance frequency fo of the Helmholtz of the speaker device 1 by the acoustic
volume 4 and the acoustic tube 5 without attaching the second acoustic tube 6 is B, the acoustic
volume of the acoustic volume 4 is B, and the cross-sectional area of the acoustic tube 5 is
Assuming that S, the length of the acoustic tube 5 is L1, and the speed of sound is C, this is set by
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the equation (1). fo = (C / 2π) × √S / L1 · B (1)
[0007]
When the resonance frequency foo of the Helmholtz of the speaker device 1 in which the second
acoustic tube 6 is connected to the acoustic tube 5 is the same as that of the acoustic tube 5 and
the length of the second acoustic tube 6 is L2 , Is set by equation (2). foo = (C / 2π) × √S / (L1
+ L2) · B (2) Therefore, by attaching the second acoustic pipe 6 having a predetermined length or
a predetermined cross-sectional area, the resonance frequency of the speaker device 1 is set to a
desired value it can.
[0008]
Next, specific examples of the attachment of the acoustic tube 5 and the second acoustic tube 6
will be described with reference to FIGS. 2 and 3. In FIG. 2, a weir 7 is provided at the sound
emitting side opening of the acoustic tube 5, and a weir 8 having the same shape is provided also
at the opening opposite to the sound emitting side opening of the second acoustic tube 6. Screw
holes are formed in the weirs 7 and 8. The length of the second acoustic tube 6 is set to a desired
length, and the cross-sectional area is made the same as that of the acoustic tube 5. Then, both
the sound tubes 5 and 6 are fixed by screwing the weirs 7 and 8 through the screw holes. It is
preferable that the acoustic tube 5 and the second acoustic tube 6 use the same material.
[0009]
In FIG. 3, the outer diameter of the second acoustic tube 6 is set to be slightly smaller than the
inner diameter of the acoustic tube 5, and the second acoustic tube 6 can be stored in and
withdrawn from the acoustic tube 5. And the contact surface of the 2nd acoustic tube 6 and the
acoustic tube 5 is comprised by the surface which has a predetermined | prescribed coefficient of
friction so that both the acoustic tubes 5 and 6 can be latched in a predetermined position.
Alternatively, minute uneven surfaces are formed on both the sound tubes 5 and 6. The material
of the second acoustic tube 6 is desirably made of a metal or hard synthetic resin having high
rigidity in order to reduce the thickness of the tube so as to be equal to the cross-sectional area
of the acoustic tube 5 as much as possible. As described above, by providing the second acoustic
pipe 6, it is possible to variably select a lower frequency desired by the listener for the frequency
of the low frequency reproduction band.
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[0010]
Second Embodiment FIGS. 4 and 5 show another embodiment of a speaker device according to
the present invention and an embodiment in which this is provided in a driver seat or a
passenger seat (vehicle seat) of a car. In FIG. 4, a pair of speakers 2 a and 2 b are attached to
both ends in the cylinder 9. Openings 10a and 10b corresponding to the diameter of the
diaphragms of the speakers 2a and 2b are formed at both ends. The diameter of the openings 10
a and 10 b is set to, for example, about half the diameter of the cylinder 9. At the center of the
cylinder 9, a sealing disk 11 is provided to prevent mutual interference between the two
speakers 2a and 2b. Outer cylinders 12a and 12b are mounted on both sides of the cylinder 9,
respectively. The inner diameter of the outer cylinder 12a, 12b is substantially equal to the outer
diameter of the cylinder 24, and the cylinder 9 is inserted into the outer cylinder 12a, 12b and
locked by the projections 13a, 13b provided on the outer peripheral surface of the cylinder 9.
The acoustic tubes 5a and 5b are connected to both end surface portions of the outer cylinders
12a and 12b, respectively. An acoustic space formed by the cylinder 9 and the outer cylinders
12a and 12b serves as an acoustic volume. Further, this speaker device is symmetrical in the leftright direction, and the speakers 2a and 2b, the outer cylinders 12a and 12b, and the acoustic
tubes 5a and 5b have the same shape and characteristics.
[0011]
The speakers 2a and 2b used here are double dampers and edgeless which can increase the
amplitude width because the effective vibration surface of the diaphragm is small. However, a
highly flexible shield that shields the front and back of the diaphragm from the edge part. The
material is used to increase the sound pressure level.
[0012]
In FIG. 5, the seat 14 includes a seat 15, a backrest 16 and a headrest 17.
Inside the backrest portion 16, the cylinder 9 and the outer cylinders 12a and 12b of the speaker
device shown in FIG. 4 are accommodated. These are disposed at the lower portion (the seat 15
side) of the backrest 16. As shown in FIG. 6, both the sound tubes 5a and 5b pass through the
inside of the backrest portion 16 and are exposed from locations adjacent to the left and right
sides of the headrest 17. The two acoustic tubes 5a and 5b are first led out horizontally from the
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outer cylinders 12a and 12b in the interior of the backrest portion 16, and then bent to extend
upward (to the side of the headrest 17) and further bent in the horizontal direction. And both
openings are exposed from the upper surface of the backrest 16. The second acoustic tubes 6a
and 6b are attached to the end openings of the exposed acoustic tubes 5a and 5b.
[0013]
FIG. 6 shows an embodiment of a structure in which the second acoustic tubes 6a and 6b are
attached. In this attachment example, as shown in FIG. 2, the flanges 7a and 7b are provided on
the acoustic tubes 5a and 5b, and the flanges 8a and 8b are provided on the second acoustic
tubes 6a and 6b. Then, the collars 7a, 7b and 8a, 8b are fixed by, for example, screws. As a result,
the length of the acoustic tube is the sum of the lengths of the acoustic tubes 5a and 5b and the
length of the second acoustic tubes 6a and 6b, and the resonance frequency of Hermholtz does
not attach the second acoustic tubes 6a and 6b. It will be lower than the ones.
[0014]
Left and right stereo signals L and R may be applied to the speakers 2a and 2b, respectively, or a
sum signal L + R may be applied. When a signal is applied to the speakers 2a and 2b, the
diaphragm is driven to cut off the volume of the acoustic volume portion defined by the cylinder
9 and the outer cylinders 12a and 12b and the disconnection of the acoustic tubes 5a and 5b and
the second acoustic tubes 6a and 6b. A low frequency band including a resonance frequency
determined by the area and length is emitted from the open end of the second acoustic tubes 6a
and 6b provided in the left and right close portions of the headrest 17.
[0015]
In FIG. 6, the second acoustic tubes 6a and 6b may be slidably attached to the insides of the
acoustic tubes 5a and 5b and locked at a desired resonance frequency. In addition, the second
acoustic tubes 6a and 6b themselves may be configured to be variable in length such as a
bellows configuration so that the resonant frequency can be varied. Moreover, although this
embodiment demonstrated the example which accommodated the speaker apparatus in the front
seat of a vehicle, it is applicable also to a back seat.
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[0016]
Third Embodiment FIG. 7 shows a speaker device according to another embodiment of the
present invention. The speaker 2 is housed in the lower central portion of the housing 18. A pair
of partition plates 19a and 19b are formed in the housing 18 so as to partition the sound output
side portion of the speaker 2, and both ends thereof face each other at a predetermined interval.
Further, partition plates 20a and 20b are formed on the left and right outer sides of the partition
plates 19a and 19b, and a pair of left and right acoustic paths acoustically continuous from the
openings at the predetermined intervals are formed. The housing 18 is provided with a pair of
left and right acoustic tubes 5a and 5b. The acoustic tubes 5a, 5b are acoustically continuous
with the acoustic path. Second sound pipes 6a and 6b are attached to the sound emission side
openings of the sound pipes 5a and 5b, respectively.
[0017]
Spaces formed in the partition plates 19a, 19b constitute an acoustic volume portion, and are
attached to the acoustic volume portion by an acoustic path formed by the partition plates 20a,
20b, the acoustic tubes 5a, 5b and the second acoustic tubes 6a, 6b. Constitute a pair of left and
right acoustic tubes. The pair of left and right acoustic tubes are configured to have the same
cross-sectional area and length. When a signal is applied to the speaker 2, the diaphragm is
driven, and its vibration wave is from a pair of acoustic paths by the partitions 20a and 20b
through openings at predetermined intervals from the acoustic volume by the partitions 19a and
19b. Sound is emitted to the outside through the acoustic tubes 5a, 5b and the second acoustic
tubes 6a, 6b.
[0018]
At that time, the resonance of Helmholtz is generated respectively by the acoustic volume and
the pair of left and right acoustic tubes. This resonance frequency is the same for both, and the
resonance frequency of the Helmholtz is lowered by the second sound tubes 6a and 6b, so that
the bass range is emphasized. When the speaker device is mounted on, for example, a seat of a
vehicle shown in FIG. 5, the second acoustic tubes 6 a and 6 b are made to project from the
backrest 16. The second acoustic tubes 6a and 6b may have variable lengths.
[0019]
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As described above, one Helmholtz resonator can be configured with one speaker. Further, by
providing the acoustic path in the housing, it is possible to shorten the part projecting to the
outside of the acoustic tube, and the speaker device can be made compact as a whole. In addition,
the length of the acoustic tube is changed by providing the sound emitting side end of the
acoustic tube 5, 5a, 5b with an expandable structure such as a bellows structure without
separately providing the second acoustic tube 6, 6a, 6b. The resonance frequency may be
changed. In addition, the speaker device according to the present invention may be installed in a
listening room, or may be attached to a chair or a sofa as well as a seat of a vehicle.
[0020]
It is a figure which shows the structure of the speaker apparatus concerning 1st Embodiment of
this invention. It is a figure which shows the structure of the acoustic pipe of the speaker
apparatus concerning embodiment of this invention. It is a figure which shows the structure of
the acoustic pipe of the speaker apparatus concerning embodiment of this invention. It is a figure
which shows the structure of the speaker apparatus concerning 2nd Embodiment of this
invention. It is a figure which shows the example of attachment of the speaker apparatus
concerning embodiment of this invention. It is a figure which shows the structure of the acoustic
pipe of the speaker apparatus concerning embodiment of this invention. It is a figure which
shows the structure of the speaker apparatus concerning 3rd Embodiment of this invention.
Explanation of sign
[0021]
2, 2a, 2b Speaker 4 acoustic volume 5, 5a, 5b acoustic tube 6, 6a, 6b second acoustic tube 14
vehicle seat
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