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JPS62269079

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DESCRIPTION JPS62269079
[0001]
TECHNICAL FIELD The present invention relates to an ultrasonic transducer used in a reflection
type ultrasonic detector. [Background Art 1 In general, this type of ultrasonic transducer used in
a reflection type ultrasonic detector uses f! ! In order to obtain the directivity of the sound beam,
an m sound horn is attached in front of the ultrasonic transducer. For example, as shown in FIG.
7, the sound wave emitting surface 2a of the ultrasonic transducer 2 is brought close to the end
face of the throat portion 1a of the conical ultrasonic horn 1 whose diameter gradually increases
from the throat g1u toward the sound wave emission port 1b. It is attached. However, in such a
conventional example, since it is necessary to set the horn 艮 1 of the ultrasonic horn 1 to be
several waves or more of the sound wave to be transmitted and received, the overall length
becomes long by all means and miniaturization is realized. There was a problem that it was
impossible. That is, the relationship between the diameter d of the sound emission port 11J of
the ultrasonic horn 1 described above and the directivity characteristic is theoretically calculated
as a flat 'rf source, and is an angle at which the output sound pressure is reduced to half of the
peak level. The half-value angle θ can be obtained by the following equation when the
wavelength of the transmitted and received sound waves is a human. θl / 2 = 2 × 5in = '(0,
707d + / on) ... (1) Here, the above equation is a sound source with the ibi plane as a plane sound
source, and an ultrasonic wave In order to guide the sound wave emitted from the vibrator 2
from the throat portion 1a of diameter d2 to the sound wave emission port 1b of diameter d1
and make it a planar sound source, the horn length t1 of the ultrasonic horn 1 is several times
the wavelength λ of the sound wave Needs to be good, and the overall length has also increased,
which has become a major obstacle in achieving miniaturization. When the horn length e1 is
shortened, the half value angle θ1 / 2 becomes large, and there is a problem that a desired
directivity characteristic can not be obtained. On the other hand, in order to improve the
directivity characteristics of the ultrasonic beam (for example, to make the side rope smaller), as
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shown in FIG. 8, the throat end face 1a of the ultrasonic horn 1 and the sound wave emitting
surface 2a of the ultrasonic transducer 2 Sound I during! Although there is one in which the Itube portion 3 is provided, in such a case, there is a problem that the horn length t of the
ultrasonic horn 1 becomes too small and miniaturization becomes difficult. [Object of the
Invention] The present invention has been made in view of the above-mentioned point, and it is
an object of the invention to set the horn length of the ultrasonic horn to several waves or less
without increasing the half value angle of the directivity characteristic. It is an object of the
present invention to provide an ultrasonic transducer which can be shortened and can be easily
miniaturized. [Summary of the Invention] (Embodiment 1) FIG. 1 shows an embodiment of the
present invention, wherein an ultrasonic horn 1 whose diameter gradually increases from the
throat portion 1a toward the sound wave emission port 1b; In the ultrasonic transducer similar to
the conventional example including the ultrasonic transducer 2 attached to the throat portion 1 a
of the second embodiment, the sound wave emitting surface 2 a of the ultrasonic transducer 2 is
from the end surface of the throat portion 1 a of the ultrasonic horn 1 Also, the ultrasonic
transducer 2 is attached to the throat i'li 1 a of the ultrasonic horn 1 so as to be protruded to the
side of the sonic radiation port lb.
Here, in the embodiment, the diameter d2 of the throat portion 1a of the ultrasonic horn 1 is set
to 16 am, and the diameter d1 of the sound wave emission port 1b is set to 2811 horns t7 of 7 to
9 mm, 1.1 m. The amount of protrusion of the sound wave emitting surface 2a from the end face
of the throat portion is set to 2 to 3 III fi, so that directivity characteristics as shown in FIG. 2 can
be obtained. Now, in the embodiment, as shown in FIG. 2, good directivity characteristics are
obtained with the half value angle θ1 / 2 of about 25 ° and the side lobe level of 15 dB, and
the half value angle θ is obtained. , And the side rope level is the same as that of the
conventional example shown in FIG. 8, and the horn length Q2 of the ultrasonic horn 1 can be
reduced by the conventional method without increasing the half angle θ and 〆2 of the
directivity. It is possible to make the example horn [C + 1/3 or less (near one wavelength). The
directivity characteristic shown by the dotted line in FIG. 2 is that the horn length α2 is 7 to 911
I11, and the sound wave reflection surface 2a of the ultrasonic transducer 2 is ll111 retracted
from the end face of the throat portion 1a as in FIG. The half value angle θ1 / 2 is approximately
doubled (approximately 50 °). Further, since the horn length e2 of the ultrasonic horn 1 is
short, the entire length including the cylindrical portion for housing the ultrasonic transducer 2
can be shortened to about half of that of the conventional example. Can be miniaturized. FIG. 3
shows an example using a drip-proof ultrasonic transducer 2 'formed by bonding a piezoelectric
transducer to the inner bottom surface of a bottomed cylindrical case having a truncated cone
cross section. The bottom surface which is the sound wave emitting surface 2a of the ultrasonic
transducer 2 is also made to project toward the sound wave emitting port 1b side of the end of
the throat portion 1a of the ultrasonic ho 71 as well. (Embodiment 2) tjS4 shows another
embodiment, and in the ultrasonic transducer similar to the embodiment of tR3 shown in FIG. As
compared with the embodiment of FIG. 3, the side lobe level is suppressed by about 5 dB "C".
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(Third Embodiment) FIG. 5 shows still another embodiment, in which the shape of the sound
wave emission port 1b of the ultrasonic horn 1 is made elliptical, and the shape of the end face of
the throat portion 1a is made circular, From the throat portion 1a to the sound wave emission
port 1b, the sound wave emission surface 2a of the ultrasonic transducer 2 'is a sound wave
emission port 1bl more than the end face of the @ portion 1a. To be projected. Fig. 6 (a) shows
the directivity characteristics in the X direction, and 16 (Ii) shows the directivity characteristics
in the Y direction. An ultrasonic beam emitted is an ellipse that is thick in the X direction and
thin in the Y direction. It is a beam.
[Advantage of the Invention 1 As described above, the present invention comprises an irregular
wave horn that gradually expands in diameter from the throat to the sound emission port, and an
ultrasonic transducer attached to the throat of the ultrasonic horn. In the ultrasonic transducer,
the ultrasonic transducer is attached to the throat of the ultrasonic horn so that the sound
emitting surface of the ultrasonic transducer is projected to the side of the sound emitting
opening than the end face of the ultrasonic horn Therefore, at the time of pointing, the horn
length of the ultrasonic horn can be shortened to several waves or less (for example, one wave or
so) without increasing the half-value angle of sex, and miniaturization (about 1/2) is easy There
is an effect of being able to
[0002]
Brief description of the drawings
[0003]
FIG. 1 is a cross-sectional view of an embodiment of the present invention, FIG. 2 is an operation
explanatory view of the same, FIG. 5 is a cross-sectional view of another embodiment, and FIG. 5
(a) is another embodiment. FIG. 8B is a cross-sectional view of the same, FIG. 8 is a crosssectional view of a conventional example, and FIG. 8 is a cross-sectional view of the same.
1 is an ultrasonic horn, 1a is a throat portion, 1b is a sound wave emitting port, 2 is an ultrasonic
transducer, 2a is a sound wave emitting surface, 3 'is a sound ## tube portion. Agent Patent
Attorney Stone 1) 7 7 Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 X Cannon M m Figure 7
Figure 8
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