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Description 1, title of the invention
Electro-acoustic transducer
3. Detailed description of the invention The present invention relates to an electroacoustic
transducer such as a speaker, a microphone, etc., and an object thereof is to provide an excellent
electroacoustic window converter with a simple configuration and a low distortion over a wide
band. It is. In general, the diaphragm of the electroacoustic transducer is often composed of
paper. By the way, although it is possible to obtain relatively good characteristics even with a
diaphragm made of paper, it is not necessarily sufficient in recent years where the limit is
naturally required to have higher performance than the case. Accordingly, the present invention
aims to provide an electro-acoustic transducer which is further excellent in performance, and
specifically, the diaphragm is made of a ceramic material mainly composed of aluminum oxide or
the like. It is a thing. Hereinafter, the electro-acoustic transducer of the present invention will be
described with reference to the drawings of the embodiments. The figure shows the edge of the
electroacoustic moving board 1 of the present invention, 3 is a plate, 4 is a magnet, 5 is a voice
coil, 6 is a center pole, 7 is a damper, 8 is a claim, 9 is a voice coil bobbin, and 10 is a dust cap. is
there. In the above embodiment, since the diaphragm 1 is made of a ceramic material, the sound
pressure frequency characteristics EndPage: 13t,-: 'a very high frequency flat to a very high
frequency, a sufficient rigidity can be obtained, and distortion is It can be significantly reduced.
That is, in the sound pressure frequency characteristics, when the diaphragm is a conical cone,
the frequency far at which division vibration starts is generally represented by. Here, C is the
sound speed α inside the diaphragm, the half apex angle of the diaphragm, R is the radius of the
diaphragm, and a is the Poisson's ratio. Therefore, in order to increase the frequency far at which
the divided vibration starts, the sound speed C may be increased. However, looking at the speed
of sound C, the ceramic material whose main component is aluminum oxide, which is shown in
the table below, is approximately 3.5 times the color of the paper usually used. Therefore, in the
electro-acoustic transducer using this type of diaphragm, the bandwidth can be expanded about
3.5 times as compared with a normal electro-acoustic transducer. When looking at the unilateral
bending stiffness S, assuming that the bending stiffness S is E and the constant determined by the
shape of the diaphragm is 1, 5 = IE. -Since it is expressed by (2) and is proportional to Young's
modulus E, the diaphragm of the ceramic material mainly composed of aluminum oxide has
about 100 times the bending rigidity as compared with the diaphragm made of ordinary paper.
Well, it will be less distortion. These characteristics are not limited to diaphragms using
aluminum oxide, and diaphragms using other ceramic materials can obtain the same
characteristics as those of SO.
In the embodiment shown in FIG. 1, the diaphragm 1 is simply made of a ceramic material, but as
shown in FIG. 2, the diaphragm 1 is bonded to the diaphragm body 11 and the thin film 12.13.
The diaphragm body 11 may be made of a ceramic material. Further, in this case, it is more
effective if the diaphragm main body 11 is provided with a large number of through holes 14
having a diameter of 1 mist or less to reduce the weight of the entire diaphragm 1. Further, in
this case, it is also possible to fill the through holes 14 with a foam material. As described above,
the present invention is characterized in that the diaphragm is made of a ceramic material, and it
is possible to extend the voltage frequency characteristics to a remarkably wide band, and its
overstretching is also small, which is extremely advantageous in practical use. It is a thing.
4. Brief Description of the Drawings FIG. 1 is a cross-sectional side view of one embodiment of
the electro-acoustic transducer of the present invention, and FIG. 2 is a perspective view of the
main part of another embodiment. 1 · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · ·
· · · · · hole. Name of agent Attorney Nakao Toshio has 1 person EndPage: 2