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DESCRIPTION JPS61214897

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DESCRIPTION JPS61214897
[0001]
Industrial Application Field of the Invention The present invention relates to the reduction of
abnormal noise due to friction generated from the bearing by the reciprocating motion of the
vibrating body by the sound absorbing means disposed at the front of the diaphragm. It relates to
a speaker. 2. Related Art In recent years, the progress of semiconductor technology has made
remarkable progress in the miniaturization of audio devices. A speaker for converting an
electrical signal to an acoustic signal has also been miniaturized, but there is a problem in the
acoustic characteristics of the bass region. In order to reproduce the low range with a small
speaker, it is necessary to increase the amplitude since the effective radius of the diaphragm is
reduced. For this reason, there is a speaker using a long voice coil in which the voice coil is
wound long in order to guarantee the driving force over a long amplitude region, but the
effective coil length in the magnetic circuit is small and the coil utilization factor is deteriorated.
Decreases. As a means to compensate for this, it is necessary to amplify the amplitude of the
voice coil and transmit it to the diaphragm. As a conventional technique, for example, a rotatable
pulley is attached to amplify the amplitude or a lever is used. there were. Since such a vibrating
body is supported by a component that causes friction, such as a fulcrum of a pulley or a lever,
there is a problem that an abnormal sound is generated from that portion when the diaphragm
reciprocates. Hereinafter, the conventional speaker described above will be described with
reference to the drawings. FIG. 5 shows a cross section of a conventional speaker using an
amplitude amplification mechanism. In FIG. 5, 1 is a pot yoke, 2 is a magnet, 3 is a pole piece,
and the pot yoke 1 and the pole piece 3 hold the magnet 2 to form a field portion 6 forming an
annular magnetic gap 4. A frame 6 fixes the field unit 5 at its bottom. The magnetic gap 4
reciprocates in response to the signal input. There is a vibrator 7, which comprises a voice coil
bobbin 9 around which a voice coil 8 is wound. At the upper end of the voice coil bobbin, a
bearing 11 provided with at least one or more rotatable pulleys 10 is fixed. A diaphragm 12 is
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formed of a cylindrical body 13 and a flat plate 14 closing an end face on one side thereof, and is
suspended from the frame 6 via a damper 15 formed of a rectangular cylindrical body. A ringshaped baffle plate 16 is fixed to the frame 16 at the outer periphery, and a seal 17 made of a
flexible material such as urethane foam is attached to the inner surface on the back surface on
the inner diameter side so as to contact the cylinder 13. A pair of belts, belts 17. A bell 818 is
wound, and one end of each is fixed to a fixing base 19 fixed to the upper surface of the pole
piece 3 with a screw 20 or the like, and the other end is similarly fixed to the cylindrical inner
wall of the diaphragm.
The operation of the conventional speaker configured as described above will be described
below. First, by applying an input signal to the voice coil 8, the vibrator 7 reciprocates in
accordance with the input signal. Therefore, the bearing portion 11 and the pulley 1 o attached
to the upper end of the vibrating body are a pair of belts, Peltom 17. Bell) will squeeze 818. Since
one end of each of the pair of belts is fixed to the fixing base 19, the other end of the belt is
displaced twice as much as the displacement of the vibrating body 7. Problems to be Solved by
the Invention However, in the configuration as described above, the pulley 1o reciprocates while
the fixing base 19 and the cylinder 13 contact each other, and in the bearing portion 11, the
pulley rotates around the rotation of the bearing portion. Therefore, the friction generates a
rubbing sound of a frequency higher than that of the music signal due to the friction in each part,
and this is emitted from the i moving plate directly and by conduction. Since this is synthesized
with the music signal, it has become a sound with many distortions and abnormal sounds. Means
for Solving the Problems In order to achieve this object, the speaker of the present invention is
disposed on a baffle plate disposed on the outer periphery of the diaphragm and the diaphragm
by being fixed to the frame through an annular gasket. The porous plate is made of one or more
porous plates disposed through an annular spacer, and one or more sound absorbing materials
made of glass wool or needle metals disposed between the porous plates. In addition, two
concentric cylindrical cavities which are combined with or in addition to the sound absorbing
material are arranged around the annular shape. According to this configuration, both the music
signal reproduced in response to the input signal and the abnormal sound or distorted sound
generated from the friction portion reach the porous plate and the sound absorbing material
disposed on the diaphragm, but the music Since the frequency of the frictional noise is higher
than that of the signal, and the high-frequency sound is absorbed more easily than the lowpitched sound absorbing material, the music signal passes through the porous plate and the
sound absorbing material and only the rubbing noise is absorbed. Also, if a cavity in which a
Holm Hertz resonator is constituted by two concentric cylinders is arranged on an annular
spacer, and its resonance frequency is tuned to the frequency of the rubbing noise, only the
rubbing noise is absorbed as well. If this sound absorption mechanism is combined, the high
frequency of a wider frequency is absorbed. Implementation Side One embodiment of the present
invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a
loudspeaker according to a first embodiment of the present invention. In FIG. 1, reference
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numeral 1 denotes a pot yoke, 2 a magnet, and 3 a pole piece. The pot yoke 1 and the pole piece
3 sandwich the magnet 2 to form a field portion 6 forming an annular magnetic gap 4.
A frame 6 fixes the field unit 5 at its bottom. The magnetic gap 4 reciprocates in response to the
signal input. There is a vibrating body 7 which comprises a voice coil bobbin 9 wound with a
voice coil 8. At the upper end of the voice coil bobbin, a bearing portion 11 provided with at least
one rotatable free wheel 10 is fixed. A diaphragm 12 is formed of a cylindrical body 13 and a flat
plate 14 closing an end face on one side thereof, and is suspended from the frame 6 via a damper
15 formed of a rectangular cylindrical body. A ring-shaped baffle plate 16 is fixed to the frame
16 at its outer periphery, and a seal 17 made of a flexible material such as urethane foam is
stuck on the inner diameter side back surface so as to contact the cylinder 13 of the diaphragm
There is. Pulleys □ -10 a pair of belts in opposite directions, Pertom 17. Bell) B18 is wound, one
end of each is fixed to the fixing base 19 fixed to the upper surface of the pole piece 3 with a
screw 20 or the like, and the other end is similarly fixed to the inner wall surface of the cylinder
13 of the diaphragm. . An annular gas foot 20 having a height greater than the maximum
amplitude distance of the diaphragm 12 is fixed on the baffle plate 16. A plurality of porous
plates 211 L and 21 b having a large number of holes formed on the gasket 20 are fixed to the
gasket 20 opposite to each other with the spacer 22 interposed therebetween. A sound absorbing
material 23 made of glass wool or needle-like metal is disposed between the porous plates 211L
and 21b. The operation of the present embodiment configured as described above will be
described. First, when the diaphragm 12 vibrates back and forth in response to an input to
generate a sound wave, a sound pressure corresponding to a signal is generated between the
pulley 10, the fixing base 19, the cylinder 13, the pertom 17 and the belt 18. Rubbing noise
occurs when making contact. Further, the same noise is generated from the bearing 11 of the
boom IJ-10. These rubbing noises include the sound radiated directly from each contact portion
and the sound conducted to the diaphragm and radiated from the diaphragm. These sounds are
considerably higher in frequency than the bass according to the input signal. Two sounds of low
frequency and rubbing noise according to these input signals are emitted to the front of the
speaker, but the sound absorbing material 23 is disposed between the porous plate 211L and the
porous plate 21b on the front surface of the diaphragm The bass component corresponding to
the lath input signal passes, but the rubbing noise has a high frequency, so that the sound
absorbing material 23 absorbs the sound. Therefore, the rubbing noise coming to the front of the
speaker is significantly attenuated. A speaker having this amplitude amplification mechanism is
intended to reproduce sound in a very large area of diaphragm amplitude of 20 to 200 Hz.
Therefore, if the sound absorbing material 23 is made of glass wool or needle metal, the sound
absorption of these materials is absorbed. From the characteristics, the sound of 200 H 2 or
more is absorbed, and only the necessary 200 Hz sound or less passes.
As described above, according to the present embodiment, the rubbing noise generated by the
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pulley 10 and the bearing portion 11 is absorbed by the sound absorbing material 23 disposed at
the front of the moving plate, so the listening point corresponds to the input signal. Only bass
can be transmitted, which can reduce distortion and abnormal sound. Another embodiment of the
present invention will be described with reference to the drawings. FIG. 2 is a cross-sectional
view of a loudspeaker according to another embodiment of the present invention. The same
reference numerals as in FIG. 1 denote the same parts in FIG. The feature of this embodiment is
that the resonance 624'e formed of concentric cylinders instead of the sound absorbing material
2.3 in the first embodiment is disposed inside the spacer 22. This resonator has a small radius at
the bottom of the inlet, and the bottom of the back cylinder is a large so-called Holm Hertz
resonator. Since the resonance frequency of this resonator is such that the rubbing noise is
matched to the highest level frequency, the rubbing noise is attenuated by the resonator and the
sound radiated to the front of the speaker is only the bass according to the input signal. The first
one. As shown in FIG. 3, the driving method using the pulley shown in the drawing of the second
embodiment is suspended by the damper 29 in the magnetic circuit in which the magnet 26 is
sandwiched by the center pole 26 and the top plate 27. The voice coil 28 may be driven by one
side of a lever that drives the diaphragm 32 using a lever having the bearing 31 at the center as
a fulcrum 30, and can be applied to a speaker by a driving method having a contact portion
having friction in the movable portion Needless to say. Further, as shown in FIG. 4, a plurality of
sound absorbing materials 23 & 23bf and porous plates 21a to 21C and spacers 22a and 22b
are disposed, and the material is changed to widen the frequency band for absorbing sound, and
sound absorbing materials and resonators of Holm Hertz. It is needless to say that a combination
(not shown) may be used. According to the present invention, a plurality of porous plates
disposed on the front of the diaphragm of a speaker having a drive portion having mechanical
contacts and fixed to the frame via the annular gas target via the annular spacer are provided.
Since individual sound absorbers and resonators are disposed between the perforated plates, it is
possible to attenuate rubbing noise of a frequency higher than the input signal generated with
the vibration of the diaphragm. Therefore, it is possible to realize a speaker with a low rate of
abnormal sound.
[0002]
Brief description of the drawings
[0003]
FIG. 1 is a cross-sectional view of a speaker according to a first embodiment of the present
invention, and FIGS.
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FIG. 4 is a cross-sectional view of a main part of the fourth embodiment, and FIG. 6 is a crosssectional view of a conventional speaker. 1 o · · · · · · · · · · · · · · · · · · pulleys, 11 · · · · · · bearing
portion, 12 · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · gasket 21 b ......
Perforated plate, 22 ...... Spacer. 23 · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · Resonator.
Name of agent Attorney Nakao Toshio 1 person Fig. 1 3F-Ruby or 2nd cause J ho and ruby 9
people Fig. 4 ztc Zjb Fig. 3 Bo J Shi-Su
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