JPH01220598

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DESCRIPTION JPH01220598
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
speaker diaphragm used for an acoustic output device or the like. In recent years, in the audio
characteristics of cassette tape recorders, microcassette tape recorders, and high fidelity stereo
speakers in the audio output equipment industry, speakers having better output sound pressure,
distortion rate, and flatness than in the past are desired. Speaker diaphragms, which influence
the acoustic characteristics, are increasingly regarded as important. The operation of the abovedescribed conventional speaker will be described below. The speaker is composed of a vibration
system such as a diaphragm, a voice coil bobbin, and a voice coil, and a magnetic circuit system
including a magnet, a pole, a plate, and a yoke. When a voice current flows in a voice coil in a
magnetic field like this, a vertical electromagnetic force is generated in the voice coil and vibrates
according to the current. This vibration is correctly transmitted to the vibration of the diaphragm
and emitted as a sound wave (for example, Hisao Hayasaka: Introduction to Acoustics, Nikkan
Kogyo Shimbun). However, although it is ideal for the diaphragm of the speaker to move in a
piston over the frequency band to be used, sound pressure-frequency characteristics when the
diaphragm is deformed or split vibration occurs during vibration. The distortion rate, the phase
characteristic, etc. deteriorate, which hinders high fidelity reproduction. Moreover, since the E / p
(where E: elastic modulus, p: density) possessed by the diaphragm material is small, the
conventional high-resonance frequency is low and the speaker can reproduce up to the high
region because the conventional 祇 cone diaphragm and plastic diaphragm have There was a
drawback that it was impossible. SUMMARY OF THE INVENTION In view of the above problems,
the present invention provides a speaker diaphragm having a high high-resonance frequency
without causing deformation of the diaphragm or causing divided vibration during vibration.
Means for Solving the Problems In order to achieve this object, the speaker diaphragm of the
present invention is made of a material having a large elastic modulus whisker made of zinc
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oxide in which crystals are grown in four directions different from the kraft valve. It is used as a
diaphragm. In the present invention, due to the above-described configuration, the elastic
modulus is very large, and when this is used as a diaphragm, the flexural rigidity of the
diaphragm becomes very large, and the diaphragm is deformed during vibration or split
resonance occurs. Also, since a material having a large elastic modulus whisker made of zinc
oxide in which crystals are grown in four different directions from the above-mentioned center is
used as a substrate and a specific elastic modulus, E / P (where E: elastic modulus, :: large
density, and when this is used as a diaphragm, the reproduction band of the speaker is extended,
and the speaker has excellent sound pressure-frequency characteristics, distortion rate, and
phase characteristics) You can get it.
In addition, since this diaphragm material is a mixture of a kraft valve and a whisker made of zinc
oxide in which crystals grow in four different directions from the center, the kraft valve and the
whisker are entangled and the conventional needle is good The elastic modulus can be increased
as compared with the whiskers. Further, since this diaphragm material is made of a material
having a kraft valve as a main component, it can be manufactured by the conventional paper
making method, and therefore it is very excellent in mass productivity. EXAMPLE Hereinafter, a
speaker diaphragm according to an example of the present invention will be described. The
speaker in one embodiment of the present invention uses, as a diaphragm, a material in which
whiskers made of zinc oxide in which crystals grow in four directions different from the kraft
valve are mixed. The diaphragm is fixed to a voice coil bobbin, and a voice coil provided at the tip
of the voice coil bobbin is inserted into the magnetic gap of the magnetic circuit. The operation of
the loudspeaker configured as described above will be described below. The speaker is composed
of a vibration system such as a diaphragm, a voice coil bobbin, and a voice coil, and a magnetic
circuit system including a magnet, a pole, a plate, and a yoke. When a voice current flows in a
voice coil in a magnetic field such as this, a vertical electromagnetic force is generated in the
voice coil and vibrates according to the current. This vibration is correctly transmitted to the
vibration of the diaphragm and emitted as a sound wave. Next, the method of manufacturing the
diaphragm will be described. The weight ratio of whisker (powder, 300 mesh pass) and epoxy
binder consisting of zinc oxide in which crystals are grown in four directions different from the
kraft valve. The mixture was mixed at a ratio of 2: 1, and papermaking was carried out according
to the circular mesh method, and it was used as a dome-shaped diaphragm with a gauge of 30 g /
− with a 28-diameter crane. As described above, according to the present embodiment, a
speaker using a diaphragm incorporating a whisker made of zinc oxide in which crystals grow in
four directions different from the kraft valve and the center is good without deformation of the
diaphragm and split resonance. Acoustic characteristics are obtained, and the distortion factor
can be reduced by 25 dB as compared with the aluminum dome diaphragm of the same shape. In
addition, the high frequency resonance frequency could be raised to 39 kHz from 21 kHz. In
addition, the peak sound pressure of the output sound pressure can also be reduced by about ±
3 dB as compared to the aluminum diaphragm by ± 3 dB. Further, in comparison of the
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characteristics of diaphragms using conventional needle-like whiskers, an improvement of 3 dB
in distortion rate and an improvement of 4 kHz in the high region resonance frequency were
observed.
Effects of the Invention As described above, the present invention uses as a diaphragm a material
obtained by mixing kraft made of zinc oxide in which crystals grow in four directions different
from the center as a kraft valve, and has a small distortion factor and high frequency resonance A
speaker having a high frequency and a large acoustic output can be obtained, and an excellent
speaker having good acoustic characteristics can be realized.
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