JP2000253492

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DESCRIPTION JP2000253492
[0001]
TECHNICAL FIELD The present invention relates to a speaker using a piezoelectric vibrator.
[0002]
2. Description of the Related Art It is known to use a piezoelectric diaphragm, for example, a
bimorph, as a sound source of an audio device such as a speaker. In this type of speaker, the
piezoelectric diaphragm is attached to one surface of a reinforced plastic acoustic diaphragm
containing carbon fiber or the like via a columnar support member, and the piezoelectric signal is
applied to the piezoelectric diaphragm to apply the audio signal. The diaphragm is vibrated, and
this vibration is transmitted to the acoustic diaphragm through the support member to obtain the
generation of sound corresponding to the audio signal.
[0003]
SUMMARY OF THE INVENTION In order to efficiently transmit the vibration of the piezoelectric
diaphragm to the acoustic diaphragm, it is first necessary to not limit the vibration of the
piezoelectric diaphragm. Therefore, the columnar support member for attaching the piezoelectric
diaphragm to the acoustic diaphragm should not be too thick. Heretofore, bonding or bonding of
the support member to the piezoelectric diaphragm has been widely performed generally by
bonding the support member to the piezoelectric diaphragm with an adhesive. However, as
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described above, it is impossible to obtain sufficient strength of the bonding portion because the
supporting member can not be thickened, and the bonding portion by the bonding agent is
damaged because the piezoelectric diaphragm vibrates with very large energy. The piezoelectric
diaphragm may fall off.
[0004]
Instead of an adhesive, a through hole is formed at the center of the piezoelectric diaphragm, a
screw is formed at the tip of the support member, the screw is inserted into the through hole,
and the support member is the piezoelectric diaphragm with a nut However, in this
configuration, there is a problem that the screw is loosened due to the vibration of the
piezoelectric diaphragm. Furthermore, in this configuration, the ceramic covered metal portion of
the piezoelectric diaphragm is exposed along the through hole by forming the through hole,
which causes the problem that the portion must be electrically isolated. .
[0005]
The present invention has as its technical object the solution of the problems of the prior art, and
it is an object of the present invention to provide a speaker using a piezoelectric diaphragm in
which the piezoelectric diaphragm is prevented from falling off from a support member And
[0006]
According to the present invention, there is provided a speaker in which a central portion of a
piezoelectric diaphragm is attached to an acoustic diaphragm via a support member, wherein a
through hole is provided at the center of the piezoelectric diaphragm and the through hole is A
speaker is characterized in that the support member is fixed to the piezoelectric diaphragm by
inserting the end portion of a plastic support member and caulking the end portion.
[0007]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, a speaker 10
according to an embodiment of the present invention comprises a piezoelectric diaphragm 12
attached to an acoustic diaphragm 14 via a plastic support member 16. As shown in FIG.
The piezoelectric diaphragm 12 has piezoelectric element layers 12 b formed on both side
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surfaces of a circular metal plate 12 a, and a through hole is formed in the center of the
piezoelectric diaphragm 12.
When an audio signal is applied to the piezoelectric diaphragm 12, the piezoelectric diaphragm
12 repeats bending in the front-rear direction according to the audio signal, and this vibration is
transmitted to the acoustic diaphragm 14 through the support member 16 and the audio signal
Is transmitted from the acoustic diaphragm 14 to the ambient air.
[0008]
The support member 16 has a foot portion 16d formed to be flared toward the acoustic
diaphragm 14, and a columnar portion 16c extending from the foot portion 16d to the
piezoelectric diaphragm 12 side. The tip of the columnar portion 16 c is a protrusion 16 b having
a small diameter, and the protrusion 16 b is inserted into the center hole of the piezoelectric
diaphragm 12. A portion of the protrusion 16 b that protrudes beyond the piezoelectric
diaphragm 12 is crimped while applying heat to form a head 16 a, whereby the support member
16 is fixed to the piezoelectric diaphragm 12.
[0009]
On the other hand, since the supporting member 16 is formed so as to diverge toward the
acoustic diaphragm 14 and has a large bonding surface, the energy density of the vibration is
reduced, so the adhesive is adhered to the acoustic diaphragm 14. However, the bonded portion
is not damaged by vibrational energy. Further, in FIG. 1, the support member 16 is formed
separately from the acoustic diaphragm, but the acoustic diaphragm 14 and the support member
16 may be integrally molded.
[0010]
In the present embodiment, by forming the head portion 16a by caulking the projection 16b, the
problem of loosening the nut or damaging the adhesive as in the prior art is solved. Furthermore,
when the through hole is formed in the piezoelectric diaphragm 12, the metal plate 12a is
exposed along the through hole, but according to the present embodiment, since the support
member 16 is formed of plastic, the metal plate 12a is formed. It is electrically insulated with
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respect to the metal plate 12a.
[0011]
According to the present invention, by forming the head portion 16a by caulking the projection
16b, the problem that the nut is loosened or the adhesive is damaged as in the prior art is solved.
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