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FIELD OF THE INVENTION The present invention relates to an ultrasonic ceramic microphone
used in an apparatus such as an ultrasonic transmitter / receiver used outdoors such as an
ultrasonic distance meter obstacle detection system using ultrasonic waves. 2. Related Art
Conventionally, this type of ultrasonic ceramic microphone has a configuration as shown in FIG.
In FIG. 3, a piezoelectric ceramic vibrator 1 is bonded to the bottom surface 2a of a cylindrical
case 2 having a truncated conical bottom surface to form a bimorph vibrating portion integrated
with the cylindrical case. A ring-shaped resonator 3 is fixed to the inside of the cylindrical case 2.
A terminal plate 4 is formed by implanting the terminals sa and sb. The elastic member 6 is fixed
to the opening end of the cylindrical case 2 by twisting. 7a。 Reference numeral 7b denotes a
lead wire for connecting the upper and lower electrode surfaces of the piezoelectric ceramic
vibrator 1 and the terminals 5a and 8b. Problems to be Solved by the Invention In such a
conventional configuration, since the cylindrical case integrated with the vibrating portion is
mechanically supported at the time of attachment to the device, the vibration is easily suppressed
by the support state, and the supporting method There is a problem that the characteristics are
easily changed, the structure is complicated, and it takes time to assemble. The present invention
solves these problems, and the purpose of the present invention is to attach to the vessel to
absorb the supporting pressure at the time, to provide a structure having a small characteristic
change by the supporting method, and to facilitate the assembly. It is a thing. Means for Solving
the Problem In order to solve the problem, the present invention is characterized in that the
diaphragm at the outer peripheral end has a thickness 1.6 times or more as large as that at the
center and the central portion of the diaphragm. A piezoelectric ceramic vibrator is bonded, and
it has a bimorph vibrator, made of an elastic material), a holding part for holding the diaphragm,
has a horn-like radiation part at one end opening, and a bottom face at the other end It comprises
from the support body to have. With this configuration, the thickness of the outer peripheral
edge of the diaphragm of the vibrating portion is increased to increase vibration energy, and a
horn-like radiation portion is formed at the open end of the support to increase the acoustic
radiation level to radiate high-power ultrasonic waves. At the same time, since the support is
made of an elastic member, even if an external impact is applied, the support absorbs the
vibration, and the influence on the vibrating portion is significantly reduced. Embodiment 1 FIG.
1 is a cross-sectional view of an ultrasonic ceramic microphone according to an embodiment of
the present invention. In FIG. 1, reference numeral 1 denotes a piezoelectric ceramic vibrator. A
diaphragm 8 has ring-shaped flanges 8a of different thicknesses at its outer peripheral end and a
vibrating surface 8b having a uniform flat surface, and made of metal aluminum or alumina of a
ceramic crucible.
The piezoelectric ceramic vibrator 1 was bonded to the vibrating surface 8 b to constitute a
bimorph vibrator. The thickness of the diaphragm 8 is expressed by tO-8rIrln + outside diameter
φ13.0. , Thickness of the outer peripheral end of the diaphragm t 5-01 rr r r width 2. C) By
setting + oa and the thickness t Oo -31a outer diameter φ 8.0 + ma of the piezoelectric oscillator,
a resonance frequency of 40 KHz and an output sound pressure level of 116 dB can be obtained.
As shown in relation to the change in output sound pressure level due to external pressure, when
the thickness of the moving plate 8 is greater than or equal to 6 non, the thickness of the flange
portion 8a provided around the diaphragm is 1.6 times or more of the diaphragm In this
configuration, the characteristic change upon receiving the external pressure is reduced. 9 is
made of an elastic material such as silicone rubber or butyl rubber and has a bottom portion 9a,
a horn-like radiation portion 9b formed at the other end open end, and a recess 9C in the outer
peripheral portion to facilitate attachment to equipment It is a support provided. Inside the
support 9, a holding portion for holding the outer peripheral end of the diaphragm 8 was formed.
Holes 10a1ob are provided on the bottom surface of the support 9, lead wires 11a and 11b for
extracting electricity from both electrodes of the bimorph oscillator are respectively connected,
and the holes 10 & 10b are penetrated to lead wires 11a and 11b. 12 is an adhesive for sealing
the holes 10a and 10b. The piezoelectric ceramic vibrator and the lead wire connection portion
were sealed by a support. Effects of the Invention As described above, according to the present
invention, assembly is easy because of a simple structure composed of a support and a bimorph
vibrator in which a piezoelectric ceramic vibrator is bonded to a vibrating plate, and it is possible
to use an elastic material. Since the vibrating portion is covered with the support, the external
supporting pressure can be buffered, and the characteristic change can be made small without
damping the vibration of the vibrating portion. In addition, it has a drip-proof structure that can
be used for equipment used outside because of the piezoelectric vibrator and the connection part
being sealed. By changing the thickness of the outer peripheral edge of the 0 diaphragm and
around the central part The acoustic characteristics can be adjusted by increasing the resonance
Q, increasing the electro-acoustic conversion efficiency, making a high-power ultrasonic
transducer, and optionally setting the horn-like radiation part provided integrally with the
support, And it has an effect which improves sound output.
Brief description of the drawings
FIG. 1 is a cross-sectional view showing an ultrasonic ceramic microphone according to an
embodiment of the present invention, FIG. 2 is a characteristic view showing a relationship
between a diaphragm thickness ratio of the present invention and output sound pressure level
change due to external pressure, The figure is a cross-sectional view showing a conventional
ultrasonic ceramic microphone.
1 · · · Piezoelectric S unit vibrator · · · · · · · · · · Moving plate, 8a · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · ·
vibration surface, 9 · · · · Support body 9 · · · · · · · · · Bottom surface 9b · · · · · · radiation portion, 9C
· · · · · recess, 10a, 10b · · · · · · · · hole portion 11a, 11b · · · .... Lead wire, 12 ..... Adhesive. Name of
Agent Attorney Nakao Toshio One other person E-Piezoelectric 1 self 21 Noodle Rb--Issukushi
bacteria? -F 驕 俸 Qa,--1 1 Δ curve qb---Murano 9c-Concealed, etc. fDb = constant F number 1 fbm-word line Fig. 2 Man 3