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DESCRIPTION JPH0260399

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DESCRIPTION JPH0260399
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
speaker device. SUMMARY OF THE INVENTION According to the present invention, a duct is
provided on the back side or the front side of the speaker unit, so that as the listening position is
farther, the first one is taken out from the front side or the back side of the speaker unit. The
amount of offset between the sound and the second sound emitted from the duct is increased. 2.
Description of the Related Art As a conventional speaker device, ones of a closed type, a busless
type, a passive radiator type and the like are known. The closed type is constructed by sealing a
cabinet with a speaker knee attached thereto. Further, the busless type is configured by attaching
a duct to a cabinet to which a speaker unit is attached. The passive radiator type is constructed
by attaching the same cone as the speaker unit to the cabinet to which the speaker unit is
attached. In these speaker devices, it is possible to obtain an extended sound pressure
characteristic at a relatively low frequency. [Problems to be Solved by the Invention] When such
a loud speaker is used to reproduce a sound having a sufficiently low frequency, there is a
disadvantage that a problem of noise to the surroundings occurs. そこで1. The object of the
present invention is to reduce the ambient noise as described above. [Means for Solving the
Problems] In the present invention, a duct (2) is provided on the back side or front side of the
speaker unit (3), and the first sound emitted from the front side or back side of the speaker unit
(3) And the second sound emitted from the duct (2) are in a phase inversion relationship such
that the offset amount of the first and second sounds becomes larger as the listening position
gets farther. [Operation] In the above-mentioned configuration, since the offset amount of the
first and second sounds increases as the listening position gets farther, noise to the surroundings
due to, for example, low frequency sounds decreases. An embodiment of the present invention
will be described below with reference to FIGS. 1 and 2. FIG. In the figure, (1) is a cabinet, and a
duct (2) is formed on the lower side of the cabinet (1). On the front of the cabinet (1), a speaker
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unit (3) for medium and high sound is attached. A low-pitched speaker unit (4) is attached to the
lower rear side of the cabinet (1). Therefore, the duct (2) described above is provided on the front
side of the speaker unit (4).
A plurality of holes (5) are formed on the rear surface of the cabinet (1). Further, a flat plate (6) is
disposed at the center of the cabinet (1) to block the front side and the rear side. Thus, the closed
speaker device is configured on the front side of the speaker unit (3) and the cabinet (1). FIG. 3
shows an acoustic equivalent circuit of the speaker device formed on the back side of the speaker
unit y) (4) for bass and the cabinet 7) (1). In the figure, M [], Ctj, and Rd respectively indicate the
equivalent mass, compliance, and acoustic resistance of the vibration system. Vs represents a
sound source, that is, a force that pushes the diaphragm back and forth. Cf and Mf indicate the
compliance and equivalent mass of the duct (2), respectively. The compliance cb of the pack
cavity is omitted because the air permeability is high due to the hole (5) and the acoustic low
band Rb is substantially O. In the above configuration, with regard to the speaker unit [4], the
sound pressure P reaching the viewer's ear is the sound pressure Pb of the sound emitted from
the back side of the speaker unit (4) and the duct (2) from the front side. It becomes the sum Pb
ten Pf with sound pressure Pf of the sound to come out. Pb and Pf are expressed by the following
equations. Pb −α • where α is a constant determined by the speaker unit, ω is an angular
frequency, and 2 is the impedance of the circuit. Here, the volume on the front side of the cabinet
(1) is 2β, the volume on the back side is 1.2 p, the equivalent mass of the speaker unit (4) Md =
7.3 g, the low resonance frequency fo = 45, the diaphragm Radius a = 4 cm, resonance sharpness
Qo = 0.32, duct (2) length 35 cm, cross section 1.5 cm x 12 cm, 10 cm from the outlet of duct (2)
(from acoustic terminal to lQ cm SB) The emulation value of the sound pressure Pb PfP at the
point P of 45 to 45 cm) is as shown in FIG. Also, the emulation values of the sound pressure Pb,
Pf, P at point P2 35 cm (35 cm from acoustic terminal c, 70 cm from B) from the outlet of duct
(2) are as shown in FIG. It can be seen that the synthetic sound pressure P is reduced as
compared with that of Furthermore, the simulated values of the sound pressure Pb and PfP at
points equidistant from both of the sound terminals A and B are as shown in FIG. C, and the
sound coming out from the back side of the speaker unit (4) in the low band It can be seen that
the sound emitted from the duct (2) is offset. Although not described above, the speaker unit (4)
is driven by being supplied with an audio signal whose middle and high frequencies are cut.
In the speaker device of this example, as the listening position is farther, the ratio of the distance
from both of the acoustic terminals A and B is not small. Therefore, noise to the surroundings can
be prevented. In this example, although the explanation is made to listen on the side of the
speaker unit (3), the audition may be made on the side of the speaker unit (4). In this case, the
relationship between the sound pressures Pb and Pf in FIG. 5 is reversed. Next, another
embodiment of the present invention will be described with reference to FIG. In the figure, (11) is
a cabinet, and a speaker unit (12) for bass is attached to the bottom of the cabinet (11), for
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example. And while a hole is formed in the side of this cabinet (11), duct (13) is attached so that
it may be connected to this hole. Therefore, the duct (13) is provided on the back side of the
speaker unit (12). FIGS. 7A, 7B, 7C, and 7D are respectively a plan view, a front view, a bottom
view, and a cross-sectional view along the line A-A 'of the cabinet (11). A cylindrical projection
(lla) is formed on the front side of the cabinet (11). Then, a plurality of concave grooves (llb)
extending in the height direction at angular intervals of a predetermined angle θ are formed in
the projection (lla). 8A, 8B, 8C, and 8D are respectively a rear view, a front view, and a right side
view of the duct (13). The duct (13) is formed in a square in cross section, and a hole (13a)
communicating with the inside is formed on the back side surface. The diameter of the hole (13a)
is made substantially equal to the diameter of the protrusion (lla) of the above-mentioned cabinet
(11), and the protrusion (13b) engaged with the recess (llb) of the protrusion (lla) Are formed at
angular intervals of a predetermined angle θ. The cabinet (11), the duct (13) is configured as
described above, and the duct (13) is made the cabinet by inserting the projection C1l & of the
cabinet (11) into the hole (13a) of the duct (13). Attached to (11). In this case, the convex portion
(13b) of the hole (13a) engages with the concave groove (llb) of the projection (lla), and the
rotational position of the duct (13) is fixed at the rotational position at the time of insertion
Because it can be any pivot position. The speaker device of this example also has the same
configuration as that of the speaker device formed on the back side of the low frequency speaker
unit (4) and the cabinet (1) in FIGS. 1 and 2 examples. The acoustic equivalent circuit of the
speaker device is also as shown in FIG.
In the above configuration, the volume of the cabinet (11) is 0.25 [, equivalent mass Md 8.0 g of
the speaker unit (12), low resonance frequency fo = 45 Hz, radius of the diaphragm a = 4.5 cm,
resonance sharp Sound pressure pb at the point of lQ cm from the acoustic terminal A 'and 50
cm from B' when the equivalent mass Mf of the duct (13) is 14 g, the sound pressure of the
sound coming out of the acoustic terminal A ' The simulated values of P f (sound pressure of
sound coming out of the acoustic terminal B ′) and P (synthetic sound pressure) are as shown in
FIG. 9A. Also, the simulated values of the sound pressure Pb, Pf, and P at points equidistant from
both the acoustic terminals A ′ and B ′ are as shown in FIG. B, and in the low band, the front
surface of the speaker unit (12) The sound from the side and the sound from the dach) (13) will
be offset. 9C shows measured values at the same points as in FIG. 9A. In the high region, peaks
and valleys are generated due to tube resonance, but it can be seen that the low region
substantially matches the simulated value when compared to the drawing. Also in the speaker
apparatus of FIG. 6, since the ratio of the difference in distance from both of the acoustic
terminals A ′ and B ′ becomes smaller as the listening position is farther, the sound in the low
range is canceled and the sound pressure level is reduced. Can reduce noise to the surroundings.
In addition to the above-described embodiment, as shown in FIG. 10, it is also conceivable to
directly attach the speaker unit (22) to the duct (21). Also in this case, it is obvious that the same
effect can be obtained for the same reason as the above-mentioned embodiment. According to
the present invention, the duct is provided on the back side or the front side of the speaker unit,
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and as the listening position is farther, the first sound and duct emitted from the front side or the
back side of the speaker unit are emitted. Since the offset amount of the second sound to be
transmitted is increased, the noise to the surroundings can be well prevented.
[0002]
Brief description of the drawings
[0003]
1 and 2 are block diagrams showing an embodiment of the present invention, FIGS. 3 to 5 are
diagrams for explaining the same, and FIG. 6 is a block diagram showing another embodiment of
the present invention, FIG. 7 to FIG. 9 are diagrams for explaining the same, and FIG. 10 is a
configuration diagram showing still another embodiment of the present invention.
(1)、(11)はキャビネット、(2)、(13)、(21)はダクト、(3)、(12)、
(22)はスピーカユニットである。 Agent 貞 貞 盛 珈 唄 珈 唄 珈 唄 吾 峨 徊 徊 Q 褥 褥 Q Q
Δ-ン--> 5>
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