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DESCRIPTION JP2010283491

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DESCRIPTION JP2010283491
An object of the present invention is to prevent pendulum movement in a low frequency region
of a weight of a passive radiator, and suppress the generation of abnormal noise inexpensively
and easily in production. A weight is divided into a plurality of parts to prevent pendulum
movement by increasing resonance frequency and reducing amplitude. The division bisects the
weight at a dividing line perpendicular to the main direction of pendulum movement. In two
types of pendulum motion generated by making main directions orthogonal at different
frequencies, weights are equally divided by two orthogonal division lines. In a long elliptical
passive radiator, the short axis and the long axis become orthogonal division lines. The passive
radiator body holds each divided portion of the weight in the middle in the thickness direction,
and thickens the gap along the dividing line to share the center of gravity of the weight with the
passive radiator. [Selected figure] Figure 1
パッシブラジエーター
[0001]
The present invention relates to a passive radiator which is suitable for use in bass reproduction
in an acoustic reproduction system used in a small and thin apparatus such as a liquid crystal TV.
[0002]
The sound reproduction system comprises a speaker system, an electric circuit for signal
processing and the like, and the speaker system comprises a speaker, a passive radiator provided
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as needed, and a cabinet.
That is, in a speaker system, together with a speaker that is usually a woofer for bass
reproduction, a passive radiator, also called a drone cone, is attached to a cabinet because it
consists only of a cone without a voice coil, Passive radiators may vibrate, resonate and reverse
the phase, enhancing the bass radiated out of the cabinet.
[0003]
Along with the downsizing and thinning of equipment, the speaker is also miniaturized and
thinned, and the shape thereof is becoming mainstream from a cone type to a flat type, and at the
same time, a passive radiator is also a flat type. In particular, in a speaker system intended to
reproduce bass, as shown in FIG. 10, the outer peripheral portion of the passive radiator main
body 1 is provided in order to ensure the vibration of a small-area flat passive radiator and to
ensure sufficient amplitude. A flat weight 3 is attached as an additional mass to one side of a flat
portion surrounded by the provided semi-cylindrical edge 2. In order to widen the reproduction
band at low frequencies, it is necessary to set this additional mass large.
[0004]
Passive radiators have been proposed that are not miniaturized but include mass elements that
allow for relatively large air volume discharges even with limited lateral dimensions when used in
bass reflex speaker systems (Patent Document 1). In this prior example, mass elements consisting
of a plurality of cylindrical bodies with different diameters are concentrically connected with
each other by means of an elastic connection unit with the central axis as a translational axis
movably connected, and the end faces of the cylindrical bodies are closed. The accumulation of
individual movements of mass elements results in relatively large movements of the peripheral
frame as a whole. In order to shift the phase of this movement so as not to cause acoustic
distortion or attenuation, the mass spring system by the mass element and the elastic connection
unit is made to have the same resonance frequency.
[0005]
Japanese Patent Publication No. 2003-501927
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2
[0006]
In a passive radiator as a vibrator having a single additional mass as described above, it is
necessary to set a large weight as the additional mass in order to realize sufficient bass
reproduction with a small volume.
However, as a result, as shown in FIG. 9 in the low frequency band, the pivoting motion of the
side portions about the center line of the weight 3, in this case the major or minor axis of the
long oval, that is, the pendulum motion Unwanted vibration called is induced, which causes
abnormal noise.
[0007]
This pendulum movement occurs not only in the longitudinal direction (long axis direction) of the
long elliptical weight but also in the lateral direction (short axis direction). The results obtained
by capturing the actual pendulum motion generated in the long oval weight with the laser
Doppler measuring device are schematically represented by symbols of positive direction (+)
displacement and negative direction (−) displacement in FIGS. 9 to 11. Fig. 9 shows the vertical
pendulum movement at a frequency of 26 Hz and a phase angle of 90 ° at 1 watt input, and the
weight is displaced in the opposite direction with the broken line part near the minor axis of the
long oval weight ing. FIG. 10 shows the lateral pendulum motion at a frequency of 34 Hz and a
phase angle of 90 ° at 1 watt input, and is displaced in the opposite direction with the broken
line part near the major axis of the weight as the boundary. FIGS. 11 (a) and 11 (b) show
pendulum movement viewed horizontally along lines aa and bb in FIG. 9, respectively, and it can
be seen that the displacement at a position away from the boundary is large.
[0008]
Conventionally, in order to prevent such a pendulum motion from adversely affecting the
performance of the speaker system, a sharp filter is configured by an electric circuit as an
electric measure for removing an abnormal electric signal caused by unnecessary vibration.
Signal processing prevents adverse effects of pendulum movement. However, regardless of the
fact that the cost of the pendulum movement is actually controlled by differences in individuals
that make up the weight, and changes in the surrounding environment such as temperature,
regardless of whether this alone leads to an increase in manufacturing costs. Therefore, setting of
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the filter cut-off frequency is not an effective preventive measure unless such a change is taken
into consideration.
[0009]
Patent document 1 makes it possible to draw out a large volumetric displacement from a
relatively small radiator body using a plurality of mass elements, and makes acoustic distortion
and attenuation by making the resonance frequency of a mass spring system including each mass
element the same. Teach to prevent. However, because each mass element used has threedimensional size, it is not suitable for miniaturization, and the number of parts is large as a
whole, so the manufacturing process in the case of miniaturization becomes precise and
complicated, making cost reduction difficult. It becomes.
[0010]
The present invention has been proposed to solve the problems associated with such
conventional passive radiators, and the object of the present invention is to prevent the
occurrence of pendulum motion in the low frequency region of a flat weight provided in the
passive radiator. Another object is to provide a passive radiator which can suppress the
generation of abnormal noise due to the pendulum movement physically, at low cost and with
easy measures.
[0011]
The passive radiator according to the present invention of claim 1 comprises: a thin plate-like
passive radiator body having an edge at its outer periphery; and a weight as a flat additional
mass which covers and bonds substantially the entire surface of the passive radiator body
surrounded by the edge. The weight is characterized by being composed of a plurality of divided
portions divided by dividing lines which reduce the amplitude of pendulum motion generated in
the bass reproduction band to suppress pendulum motion.
In the invention of claim 2, the passive radiator according to claim 1 is characterized in that the
dividing line of the weight is a line perpendicular to the direction of the lowest frequency
pendulum movement that occurs first. In the invention of claim 3, the passive radiator according
to claim 1 is characterized in that the dividing lines of the weight are lines in which the plurality
of divided parts have the same shape. In the invention of claim 4, the passive radiator according
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to claim 1 is characterized in that the dividing line of the weight is a first dividing line
perpendicular to the direction of the first pendulum motion of the lowest frequency generated
first and the lowest frequency And a second parting line perpendicular to the direction of the
second pendulum movement generated at the upper frequency and orthogonal to the first
parting line. In the invention of claim 5, in the passive radiator according to claim 4, the first and
second dividing lines of the weight are determined at positions where the shapes of the dividing
portions are the same and the number of divisions is the minimum. It is characterized by
According to the invention of claim 6, in the passive radiator according to any one of claims 1 to
5, the passive radiator body holds the divided portions of the weight in the mounting position in
the region surrounded by the edge and drops off. A bag is provided to prevent mutual contact. In
the invention of claim 7, in the passive radiator according to claim 6, the bag body of the passive
radiator main body comprises a bottom portion covering at least the bottom of each divided
portion of the weight and a side portion covering the side end surface. It features. In the
invention of claim 8, in the passive radiator according to claim 7, the bag body of the passive
radiator body shares the center of gravity of the passive radiator body in the mounting mode of
the passive radiator at the center of gravity of the entire divided portion of the weight to be held.
It is characterized in that it is positioned to In the invention of claim 9, the passive radiator
according to claim 8 is characterized in that the passive radiator main body has a gap between
the divided parts of adjacent weights as a bridge with a large thickness. In the invention of claim
10, the passive radiator according to any one of claims 1 to 9 is characterized in that the divided
portions of the weight each have a through hole for degassing generated upon bonding to the
passive radiator main body. I assume.
[0012]
The present invention relates to a line dividing a flat weight of a passive radiator into a plurality
of parts, preferably a perpendicular line to the main direction of the pendulum movement of the
weight, or a crossing line of the vertical line and the horizontal line By dividing the weight into
multiple parts along the dividing line that forms the inclined line, the resonance frequency of the
pendulum movement of the weight is raised and amplitude is smaller than in the case of the
single-body weight, and a large unwanted vibration is generated. Can be suppressed to prevent
abnormal sound generation in the low frequency range.
[0013]
FIG. 1 is a perspective view of a passive radiator according to a first embodiment of the present
invention.
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FIG. 2 is a perspective view of a passive radiator according to a second embodiment of the
present invention. FIG. 3 is a perspective view of a passive radiator according to a third
embodiment of the present invention. FIG. 4 is a cross-sectional view taken along a section line
parallel to the short axis of the oblong passive radiator of FIG. 3; 5 (a) and 5 (b) show 28 Hz
vibration at 1 watt input of the passive radiator in the embodiment 1 of FIG. 1 with a phase angle
of 90 ° in FIG. 5 (a) and a phase angle in FIG. 5 (b) It is a vibration measurement figure which
shows typically the result of having measured by the laser Doppler measuring device by -90
degrees by the symbol of a positive direction (+) displacement and a negative direction (-)
displacement. FIGS. 6 (a) and 6 (b) are vibration measurement diagrams obtained under the same
conditions except that the vibration measurement in FIGS. 5 (a) and 5 (b) has a frequency of 34
Hz. FIG. 7 is a perspective view of a passive radiator according to a fourth embodiment of the
present invention. FIG. 8 is a perspective view of a passive radiator according to a fifth
embodiment of the present invention. FIG. 9 is a cross-sectional view schematically showing
pendulum movement in a conventional single-body passive radiator. FIG. 10 is a perspective view
of a conventional single-body passive radiator. FIG. 11 shows, among the vibrations of the
conventional passive radiator of FIG. 10 performed in the same manner as FIG. 5 except that the
frequency is 26 Hz, in particular, the longitudinal direction around the short axis of the oblong
passive radiator. It is a vibration measurement figure which shows typically pendulum motion by
the displacement display by positive / negative sign. FIG. 12 is a vibration measurement diagram
schematically showing vibration similar to FIG. 11 at a frequency of 34 Hz, and in particular, a
lateral pendulum motion around a long axis of a long elliptical passive radiator in a displacement
display by positive and negative signs is there. FIGS. 13 (a) and 13 (b) are vibration measurement
diagrams of the longitudinal pendulum motion in the position shown by the aa and bb lines in
FIG. .
[0014]
Measures to prevent the pendulum movement of the flat weight in the low frequency range of
the passive radiator and to reduce the occurrence of abnormal noise inexpensively and easily can
be realized by the present invention shown in the following several embodiments.
[0015]
FIG. 1 shows a passive radiator according to a first embodiment of the present invention, and a
passive radiator main body 11 made of vulcanized rubber such as IIR, SBR or the like, for
example, in an oblong shape has a substantially semicircular cross section along the outer
peripheral edge An upper surface of a flat plate region having an edge 12 and surrounded by the
edge 12 is bonded with a weight 13 formed into a substantially elliptical flat plate made of, for
example, iron or stainless steel, selected on the condition that the density is large and
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inexpensive. As a feature according to the invention, the weight 13 is bisected into parts 13a and
13b by a dividing line 14 along its minor axis.
That is, the dividing line 14 is a line perpendicular to the pendulum movement whose main
direction is the longitudinal direction along the long axis of the long elliptical weight shown in
FIG. 11, and the pendulum movement is divided by this dividing line, As the resonance frequency
is increased, the amplitude is reduced and the adverse effect on bass reproduction is significantly
reduced.
[0016]
The divided portions 13a and 13b of the weight each have a gas venting hole 15 penetrating in
the thickness direction to eliminate the influence on the vibration due to the retention of gas
generated at the time of bonding to the passive radiator main body 11. Further, if the divided
portions 13a and 13b are formed so as to equalize the mass and the shape with each other so
that the same performance can be obtained regardless of the respective installation positions,
manufacturing while minimizing the number of parts. The process can be easily kept.
[0017]
The second embodiment of the present invention shown in FIG. 2 differs from the first
embodiment in that the dividing lines of the weight are the same as those of the first embodiment
in addition to the first dividing line 14 along the substantially elongated minor axis. And a second
parting line 16 along the major axis, whereby the divided parts of the weight divided in the
longitudinal direction are further bisected in the lateral direction, the weight being divided into
four divided parts 13c, 13d, 13e , 13f. The second dividing line 16 divides the horizontal
pendulum movement of FIG. 11 generated at a frequency different from that of the vertical
pendulum movement of FIG. can get. It is desirable that each of the divided portions 13c to 13f
of the weight has a vent hole 15 for exhaustion, and is formed to have the same mass and shape
as each other.
[0018]
In the third embodiment of the present invention shown in FIG. 3, while forming the divided
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portions 13c to 13f of the weight by the first and second dividing lines 14 and 16 in the same
manner as in the second embodiment, the passive radiator main body 11 is an edge In the region
surrounded by 12, a bag body is provided which positions each of the divided portions 13c to
13f, prevents the respective detachment, and prevents mutual contact. As shown in a sectional
view in FIG. 4, the bag is integrally formed with the passive radiator main body 11, and the
bottom 11a covering the bottom of each divided portion, the side 11b covering the side end, and
the upper end of the side 11b The covering edge 11c covers the edge portion of the upper
surface of the divided portion, and any bag portion is bonded to the divided portion or bonded at
least at the bottom portion 11a facing the gas vent 15.
[0019]
Moreover, the built-in structure of the weight 13 to the passive radiator main body 11 shown in
FIG. 4 assumes that both share a gravity center. Therefore, the flat plate portion surrounded by
the edge 12 of the passive radiator body 11 holds each of the divided portions 13d to 13f of the
weight 13 substantially at the center in the thickness direction, and the adjacent portions along
the dividing lines 14 and 16 of the weights The thickness of the flat plate portion is increased
and optimized in the gap 11 d between the divided portions. By sharing the center of gravity in
this manner, the stability can be increased not only during vibration but also at rest.
[0020]
The vibration mode at a frequency of 28 Hz of the passive radiators of Examples 1 to 3 according
to the present invention is shown in FIG. 5, and the vibration mode at a frequency of 34 Hz is
shown in FIG. 5 and 6 (a) is a symbol of the phase angle of 90 degrees in the positive direction
(+), and (b) is a model of the displacement of -90 degrees in the negative direction (-). Show. In
any bass vibration mode, uniform translational motion is realized in the same direction, which
indicates that good bass reproduction is performed.
[0021]
The fourth embodiment of the present invention shown in FIG. 7 shows a tendency of pendulum
motion in the conventional passive radiators of FIGS. 11 and 12 to be generated in an oblique
direction, so long oval short as a measure to prevent such motion. The weight is divided by an
oblique dividing line 17 that obliquely intersects the axis or the major axis, but since the
pendulum motion in the oblique direction also occurs at symmetrical positions, the two oblique
dividing lines 17 cross in an X shape, It is desirable to use four divisions of two pairs of divisions
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13g and 13h.
[0022]
In the fifth embodiment of the present invention shown in FIG. 8, V-shaped oblique dividing lines
18 extending from one side edge to the other side edge of the oblong weight are also used as a
measure to cope with pendulum motion generated in an oblique direction. It may be divided into
three parts of a pair of diagonally divided parts 13i and V-shaped divided parts 13j at both ends.
[0023]
Although all of the above examples are limited to the use of oblong passive radiators, they are
generally oblong in order to obtain sufficient bass reproduction in small, thin acoustic devices
such as LCD TVs. It is because use becomes mainstream.
On the other hand, the pendulum movement changes the main direction according to the
external shape and frequency of the passive radiator, but when the external shape is substantially
rectangular or oblong, a pendulum whose main direction is the longitudinal direction (long axis
direction) at frequency 26-28 Hz. In order to prevent this, the weight is bisected at a dividing line
perpendicular to the major axis (in the direction of the minor axis).
At a frequency of 34 Hz, a pendulum motion whose main direction is the lateral direction (short
axis), the weight is equally divided by the dividing line in the long axis direction in order to
suppress this. As a practical low-pass passive radiator, the pendulum motion of these two bands
should be able to be suppressed. Therefore, in Example 2, the weight is bisected in the
longitudinal direction by two orthogonal dividing lines and further in the transverse direction.
The whole is divided into four equal parts.
[0024]
If the passive radiator is circular, pendulum movement can occur in any direction, so it is
effective to determine the direction by experiment and use a line perpendicular to the diameter
line along the pendulum movement direction as the dividing line of weights. is there.
[0025]
The present invention is intended to improve the bass characteristics only by dividing the weight
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of the conventional passive radiator, and does not change the outer shape and dimensions at all,
so the compactness and thinness of conventionally achieved acoustic devices The speaker system
can be integrated with the speaker as it is into a small, thin speaker system with excellent bass
characteristics.
[0026]
11 Passive Radiator Body 11a Bottom Part 11b Side Part 11c Covered Edge Part 11d Clearance
Part 12 Edge 13 Weight 13a to 13j Division Part 14 Division Line 15 Gas Vent Hole 16 Second
Division Line 17 X-shaped Crossing Division Line 18 V-shaped Cross sectioning line
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