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JPS57168600

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DESCRIPTION JPS57168600
Description 1, title of the invention
Pronunciation body
3. Detailed Description of the Invention The present invention relates to a sound generator that
utilizes the bending vibration of a plate, for example, a sound generator such as a dynamic
earphone. As a conventional sound producing body utilizing the bending vibration of a teaching
material, a piezoelectric sound producing body utilizing an electrostrictive phenomenon is well
known. This piezoelectric type sounding body is a bimorph diaphragm bonded with two sheets of
piezoelectric temporary tacking, or unimorph vibration @ bonded with piezoelectric temporary
tacking on a metal machine with a suitable frequency of 0) electric field application of bending
vibration by C2 It is made to sound by using vibration ? at that time. In the piezoelectric
speaker, the change in input impedance and the change in sound pressure with respect to the
frequency f of the applied electric field have characteristics as shown in FIG. Curve A in FIG. 1
shows an input impedance characteristic curve, and curve B shows a sound pressure
characteristic curve. As is clear from the curve A in FIG. 1, as indicated by the curve A, there are
two face amounts (two) in which the input impedance 1z becomes larger as the same wave
number f becomes lower in C, the piezoelectric type sounding body. This is because the
piezoelectric type sounding body is a one-piece conden, and so is the case of the capacitance &&
O as a capacitor. Therefore, as the frequency f of the applied electric field decreases, the loss
increases and the 5EndPage: 1 sound pressure level decreases as shown by the curve B in FIG.
There was a despicable drawback of getting worse. In addition, since the input impedance Iz'l
changes with the frequency f of the applied electric field, there is also a disadvantage that
impedance matching with the drive circuit is difficult. In addition, as shown in FIG. 1 ((2), (2), the
pressure-generating body has a minimum human impedance IZ + near the resonance frequency
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fr, and a maximum ratio level. Therefore, in the piezoelectric type sounding body, in order to
raise the sound pressure level 7, driving is not performed at a very small point of the input
impedance Iz'l. Also, it is difficult to match the impedance with the drive circuit whose output
impedance is fixed. Assuming that the resonance frequency fr is the diameter D of the
piezoelectric speaker and the thickness is t, f, = + 7 ░░ ииииииииииии [11 and Become. On the other
hand, the input impedance IZ + of the pressure speaker is inversely proportional to the
capacitance C as a capacitor, as in a cascade. The capacitance C is proportional to the area S of
the tail speaker B, and the thickness t (in inverse proportion to two), the input impedance lzl is
eventually obtained. That is, in the case of the piezoelectric and shaped sounding body, when the
diameter D and the thickness t thereof are determined, the resonance frequency f and the manual
impedance Izl are simultaneously determined n.
For this reason, if the shape is extra-n, the material of the frequency 7 can be changed, or the
vibration frequency (a bi-lateral shape, a weight of a weight attached to it, a resonance Q of the
resonance, etc. There is also a disadvantage that the structural instability O) causes the reduction
of reliability. It is an object of the present invention to provide a sounding body which does not
have the above-mentioned disadvantages, has a good sound reproduction in the low band, has a
wide frequency bandwidth, and has a high degree of freedom in design. In order to achieve this
object, the sounding body according to the present invention causes the magnetostrictive plate to
generate a magnetic field and change the field (by two N1 swings, and then generate the betting
vibration generated in the l'll J magnetostrictive plate) It is a feature. It is well known that the
metal of a certain ridge has a magnetostrictive material that causes physical distortion in a
magnetic field. The magnitude and direction of the magnetostriction largely differ depending on
the type of magnetostrictive material. For example, as shown in FIG. 2, C2, 37-Niskel steel, AF
gold alloy and 40-cobalt steel are strained in the magnetic field H in the direction in which the
length is extended, while pure iron, 92 tinkel steel and pure nickel steel etc. The strain is
distorted in the direction in which the length look shrinks, and also depends on the strength and
direction of the magnetostrictive field H. For example, in the example shown in FIG. 2, when the
magnetic field H changes from 0 (oe) to 100 (..), the change in the strain rate 5L / L becomes
maximum. In the present invention, in view of the magnetostriction phenomenon of this et al.,
The magnetostrictive plate magnetic field is changed and excited, and at that time, it is made to
generate using the bending vibration which occurs in magnetostriction C2. More specifically, in
the characteristic diagram of FIG. 2, the magnetostrictive plate in which the direction of
magnetostriction is on the side where the length is extended (to) and the magnetostrictive plate
on which the length is reduced on the (?) side For example, a diaphragm is formed by bonding
using means such as a metal bath observation method, and this diaphragm is excited in a
magnetic field of varying strength or direction, such as a father's magnetic field, as shown in FIG.
The bending vibration as shown is performed. In this case, the magnetic field for exciting the
magnetostrictive plate can be easily obtained by flowing a father's ball or pulse caustic in the coil.
???????????????? Assuming that L, the impedance IZ + of the coil is IZI +
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2?fL, which is proportional to the frequency f of the current flowing through the coil. Therefore,
unlike the conventional piezoelectric type sounding body, the sounding body according to the
present invention tends to decrease the loss of the sounding body itself and to increase the
supplied power when the frequency f is lowered, and the sound reproduction in the low
frequency range Very good (two). Also, since the betting vibration of the magnetostrictive plate is
determined by the frequency of the magnetic field, the frequency band width is greatly expanded
unlike the pressure radiation sound generator.
Moreover, since the frequency characteristics depend only on the coil and there is no close
contact relation with the magnetostrictive plate, it is possible to keep the sound reproduction in
the low region good while aiming at the small EndPage: 2 diameter ratio of the diaphragm.
become. Furthermore, since the input impedance as the sound generator can be easily changed
according to the number of turns of the coil, etc., there is an advantage that impedance matching
with respect to the output impedance of the external drive circuit becomes easy. Next, the
contents of the present invention will be specifically described with reference to an embodiment.
First, in the embodiment shown in FIG. 4, one end of the diaphragm 2 is supported in a
cantilevered manner at 7t 1 and the iron core 4 gap 01 on which the coil 3 is wound is separated
at the other end of the diaphragm 2. When facing each other, the permanent magnet 5 for
magnetic bias and the space G2 are disposed opposite to each other on the mounting base side of
the diaphragm 2. As described above, the diaphragm 2 has a structure in which the
magnetostriction number 2 person whose displacement direction of magnetostriction is on the
output side is combined with the publication tJI1.l (two magnetostrictive plates 2B are bonded.
As a combination of the magnetostriction number 2 ? ? 2 B, it is desirable that a combination
of one in which the magnetostriction rate 4 is maximized on the ? + 1 side and the other in
which the magnetostriction rate 4 is maximized on the publication side. In the example shown in
FIG. 2, the combination of 40% copal) 1 ifl and pure nickel is most preferred. In the sounding
body having the above structure, 6 is a yoke, when a father's battery or the like is supplied to the
coil from the drive circuit e, the magnetic field of the permanent magnet 5 is generated by the
father's magnetic field where the coil 5 and iron core are formed. While being biased, the
diaphragm 2 performs a bending action in the opposite direction every half cycle, and a vibration
noise is obtained. Next, the one shown in FIG. 5 is mounted on the end face of the cylindrically
formed support 1 with a frequency 2 formed in a solid number, and the inner diameter portion of
the support 1 has five cylinders. Of the permanent stone 5 and the iron core 4 around which the
coil 5 is wound is provided, which has a structure similar to that of a conventional dynamic
earphone . The advantage of this embodiment is that it is easy to assemble and has high mass
productivity. C 2 Fig. 6 ? 1. (Bl indicates that two or more frequencies 2.2 are arranged side by
side, and two frequencies C ?? 2 are mutually connected by this frequency 2.2 ? non-magnetic
coupling body 7 (=, middle part 7 sounding of coupling body 7 It is embedded in the plate 8 and,
due to the cooperative action C2 of the diaphragm 2.2, the sounding plate 8 is bent and vibrated
to generate a sound. The coil 5 and the iron core 4 are provided at each frequency 2.2 0 The
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feature of this embodiment is that the cooperative action of the plurality of diaphragms 2.2 (two
by which the sound generating plate 8 is driven Bandwidth is to be expanded.
4 to 6 show limited embodiments of the present invention, and it goes without saying that
various modifications are possible. For example, various modifications can be made, such as
changing the frequency 2, the shape of the iron core 4, the shape of the permanent magnet 5 or
the yoke, the number, the relative positional relationship or the assembling method, and the
waterproof structure. As described above, since the sounding body according to the present
invention is characterized by being excited by a change in the magnetic field of the
magnetostrictive plate and generating bending using bending vibration generated at that time,
the piezoelectric sounding body etc. Compared to other types, especially the sound reproduction
in the low range is good, the frequency bandwidth is wide, and miniaturization is easy, is it? Also,
it is possible to provide a new sounding body having a degree of freedom in design, such as
impedance matching with a drive circuit.
4. Brief description of the drawings Fig. 1 shows the frequency characteristics of the piezoelectric
speaker, Fig. 2 shows the magnetostriction phenomenon 2, Fig. 6 shows the present invention (operation of the speaker according to the present invention. , FIG. 4 and FIG. 5 are sectional
views of different embodiments of the sounding body according to the present invention, FIG. 6
(Al is a front view of another embodiment similarly, FIG. 6 (Bl is a plan view of the same It is. 2 иии
Vibration y 2 A, 2 B иии Magnetostrictive plate 6 иии Coil 4 иии Iron core 5 иии Permanent magnet
EndPage: ?
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