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JPS53155631

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This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
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DESCRIPTION JPS53155631
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of the main part of a
conventional speaker magnetic circuit, and FIG. 2 is a cross-sectional view of a main part of a
speaker magnetic circuit according to the present invention. 1 и и и и и и и и и и и и и и и и и и и pole piece, 2 и
и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и pl / -, 1-16 иииииииииииииииииииииииииииииииии Sound
absorber.
DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the improvement
of a loudspeaker having an external magnet type magnetic circuit. The speaker vibrates the cone
by supplying an acoustic signal to a voice coil provided in a part of the cone, and converts the
electric signal to sound by this vibration, and a speaker having various structures is produced b
Ru. FIG. 1 shows an external-magnet-type magnetic circuit generally used in the prior art,
wherein (1) is a cross-sectional reverse T-shape having a cylindrical body (3) protruding from the
center of the disc portion (2). No. 1) Pole piece, (4) is a ferrite magnet placed around the
cylindrical body (3) and on the disc part Q), (5) is the disc part of the pole piece (1) The inner
peripheral surface of this play (5) faces the cylindrical body (3) of the pole piece (1) by the
magnet (which is a ring-shaped plate for holding the four) by (2) and K, and is shown between
Not a voice coil is located. In the speaker configured as above, when an acoustic signal is
supplied to the voice coil, the magnetic field generated from the voice coil and the magnetic field
generated between the pole piece (1) and the plate (5) due to the magnet (4) being busy. And the
voice coil vibrates in response to the tone change signal, and the sound is generated from K.
However, in the loudspeaker according to the above configuration, the magnetic flux ACAC
generated from the voice coil is superimposed on the DC magnetic flux DCDC generated from the
magnet (4) which makes a circuit of the pole piece (1) -magnet (4) -plate 6). And it follows the
magnetic circuit. Then, when the direct current magnetic flux density and the alternating current
magnetic flux density in this case are expressed as BnclBhC as (2), respectively, BAC = AIeosuJt.
Further, the driving force F is expressed as F = Bt-t-1 = (Bnc + mIeoslJt) .tllI @ cosLIIt = BDC. Here,
01-05-2019
1
Bf is a gap magnetic flux density, t is an effective length of the voice coil, and l is an alternating
current flowing through the voice coil. As indicated by the above equation, in the conventional
magnetic circuit, a frequency component twice as high as that of the drive is generated by the AC
magnetic flux circulating in the magnetic circuit, and the second harmonic distortion is generated
due to the fall. In the magnetic circuit according to the above-described configuration, the inside
of the magnet (4). The air in the space surrounded by the pole piece (1) and the plate 6) is
compressed and expanded by the voice coil that reciprocates between the magnetic gaps, and a
resonance occurs, and this resonance causes the sound quality from mid to high Have various
disadvantages, such as harming (3).
Therefore, an object of the present invention is to provide a speaker in which the occurrence of
second harmonic distortion is prevented. Another object according to the present invention is to
provide a loudspeaker which is not harmed to middle and high range by the occurrence of
resonance. Hereinafter, the speaker according to the present invention will be described in detail
using the drawings. FIG. 2 is a cross-sectional view of an essential part showing an embodiment
of a loudspeaker according to the present invention, in which the same parts as those in FIG. In
the figure, the difference from Fig. 1 is that the sound absorber g having conductivity in the
space (6) surrounded by the pole piece (1), the magnet (4) and the plate (5) VC is a cylindrical
portion (3) It is that it was arranged to short-circuit the circumference of). As the sound absorber
(7) having this conductivity, for example, a stainless steel fiber (diameter 8 to 12 .mu.m) is cut
into an appropriate length, and this is cut into a cotton-like shape by an opening machine, and a
glass fiber is also used as a sound absorber. While having a value almost comparable to the heat
insulating material, the specific electrical resistance also has a low value of 72 О 109 countries.
The magnetic circuit is looped by arranging the sound absorber (7) having such conductivity to
short-circuit the outer circumference of the ball bees (4) (circumferentially around the outer
circumference of the ball) and acting as a short ring. And cancel the alternating magnetic flux,
and absorb the natural resonance of the space surrounded by the pole piece (1), the magnet (4)
and the plate (5). As described above, since the speaker according to the present invention has
the conductive sound absorbing material disposed in the space surrounded by the pole piece, the
magnet and the plate so as to short the outer periphery of the pole piece, the second harmonic
Wave distortion is prevented, and resonance of a space is prevented, and it has various
outstanding effects, such as the tone quality of middle and high frequency range improving. In
the present invention, the effect of the present invention is large in a long voice coil type speaker
in which the winding width of the voice coil is wider than the thickness of the plate (5).
01-05-2019
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