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BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
ultrasonic ceramic microphone for transmitting and receiving ultrasonic waves for use in an air
communication device requiring high output. The structure of the prior art and its problems The
structure of the conventional microphone of this type is configured as shown in FIG. That is, the
piezoelectric vibrator 1 and the metal diaphragm 2 are bonded together to form a bimorph
vibrator, and the conical metal resonator 4 is fixed to the center through the coupling shaft 3 to
form a composite resonator. The composite resonator is adhered and fixed to the central
mounting portion (annular convex portion) of the terminal plate 5 made of resin via the elastic
adhesive 6. Reference numerals 7a and 7b denote lead wires, and reference numerals 8a and 8b
denote terminals embedded in the terminal plate 5. A case 9 accommodates the composite
resonator and the terminal plate 5. Further, according to the conventional structure of O or more,
which is attached to the open end of the case 9 and protects the inside, 10 is a mesh, to increase
the vibration efficiency of the complex resonator, a bimorph of the complex resonator is used.
The mounting portion (annular convex portion) of the terminal plate is positioned on the
vibration mode node circle of the bimorph vibrator of the vibrator, and the composite resonator
is bonded via an elastic adhesive. Therefore, the resonance can be effectively used without
disturbing the vibration of the bimorph oscillator. However, there is a limit when higher power
levels are required. When the voltage applied to the nrrs bimorph oscillator increases, heat
generation due to vibrational energy corresponding to the n increases, and the adhesive layer on
the bonding surface of the bimorph oscillator softens and vibration damping increases. That is,
since the conventional terminal board is made of a resin material, there is a problem that the heat
radiation effect is small and the output is reduced due to heat generation. SUMMARY OF THE
INVENTION The object of the present invention is to eliminate such conventional drawbacks, and
to provide an ultrasonic ceramic microphone in which heat due to vibrational energy of a
bimorph vibrator is efficiently dissipated and the applied voltage is improved. It is In order to
achieve the above object, the present invention provides a composite resonator in which a metal
resonator is attached to a central portion of a bimorph resonator formed by bonding a metal
diaphragm to a piezoelectric ceramic resonator via a coupling axis. And an annular convex
portion provided with one or more through holes at a central portion thereof, and adhesively
fixed to the annular convex portion of the mount made of a metal material via an elastic adhesive,
The composite resonator and the mount are housed in a metal case having a through hole.
Description of the Embodiments Hereinafter, one embodiment of the present invention will be
described with reference to FIG. 2 and FIG.
In FIGS. 2 and 3, the same parts as in FIG. 1 are given the same reference numerals. In the figure,
a 11'i piezoelectric ceramic vibrator is bonded to a metal diaphragm 2 to form a bimorph
vibrator. Then, the inner pyramidal metal resonator 4 is passed through the connecting shaft 3
fixed to the central portion of the bimorph oscillator, and the metallic resonator 4 is bonded and
fixed to the central portion of the bimorph oscillator, thereby making a complex resonance. I
have a body. Reference numeral 11 denotes a metal mounting table, which has an annular
convex portion 11a (i7 at its central portion and is provided with one or more through holes 11b
on the side of the convex portion 11a, and the composite resonator is It fixes to the said annular
convex part 11a via the elastic adhesive agent 6. As shown in FIG. 7a / 'j, a lead wire soldered to
the electrode surface of the piezoelectric ceramic vibrator 1; 7b a continuous lead wire connected
to the metal diaphragm 2 having the same potential as the other electrodes of the piezoelectric
ceramic vibrator 1; The lead wires 7a and 7bi are taken out from the lead wire takeout holes 11c
and 11d provided in the metal mount 11. Reference numerals 12 and 13 denote elastic adhesives
for fixing the lead wires 7a and 7b. A metal case 14 has a plurality of through holes 14a'i on its
side surface and an ultrasonic radiation port 14b at one end thereof. The composite resonator
and mounting base 11 are housed in the case 14 by forming an ultrasonic radiation port 14b. It
is Here, even if a net is provided in the ultrasonic radiation port 14b of the case 14 in the one
embodiment, the intended effect of the present invention can be obtained. −! Although the lead
wires 7a and 7b are also used as external terminals, the lead terminals 7a and 7b may be
connected to the terminals by implanting external terminals on the mount 11. Furthermore,
although the through hole 11bi is provided in the annular convex portion 11a of the mounting
table 11, the purpose is to increase the heat radiation effect, so a U-shaped through hole may be
cut from the upper surface of the annular convex portion 11a. As described above, heat
generated when the bimorph vibrator is forcedly vibrated by the application of an electric signal
is the through hole 14 a by the through hole 14 a provided in the case 14 and the through hole
11 b provided in the mounting base 11. The heat can be dissipated efficiently by 11b. Effect of
the Invention As described above, the ultrasonic ceramic microphone according to the present
invention comprises the case and the mount made of a metal material having high thermal
conductivity, provides a through hole in the case and the mount to make a flow path of air, and
dissipates heat. By raising the effect, the input voltage resistance of the bimorph oscillator can be
increased, and the vibration amplitude can be made large, so that it can be used for high output.
Further, since the bimorph oscillator is surrounded by the metal material, the electric shielding
effect is high, the response to ambient temperature changes is quick, and the design of the
temperature correction circuit can be facilitated.
Brief description of the drawings
FIG. 1 is a sectional view showing a conventional ultrasonic ceramic microphone, FIG. 2 is a
sectional view of an ultrasonic ceramic microphone according to an embodiment of the present
invention, and FIG. 3 is an exploded perspective view thereof.
DESCRIPTION OF SYMBOLS 1 ···· Piezoelectric ceramic vibrator, 2 ···· Metal diaphragm, 3 ···
Connecting shaft, 4 ··· Metal resonator, 6 ···· Elastic adhesive , 7a, 7b ······ lead wire, 11
····································································································································· Metal case , 14a · · Perforated.
Name of Agent Attorney Nakao Toshio Other 1 person Figure 1 Figure 2 Figure 3 (B) 3! 11a。