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■ Ultrasonic radiation device ■ Japanese Patent Application No. 43-95683 [Phase] Application
No. 43 (1968) December 25 @ Inventor Kiyoshi Kuwahara Yoshitomo Mori Hideharu Shomatsu
■ Applicant Kiyotaka Kouno 52 52
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view showing an embodiment
of the present invention, and FIG. 2 is a comparison view showing directivity characteristics in
the conventional device and the present invention device.
Detailed Description of the Invention For example, it is proposed that ultrasonic waves or the like
be sensed to detect the presence of a person, a car or the like when a truck or the like retreats.
The present invention relates to the structure of an ultrasonic transducer used for such purpose,
and it is an object of the present invention to obtain an ultrasonic beam having desired directivity
characteristics and almost no side lobes. This will be described below with reference to the
embodiment shown in the drawings. In FIG. 1, reference numeral 1 denotes a ferrite
magnetostrictive oscillator, which is excited by an alternating current. The excitation wire ring is
omitted because it is not directly related to the present invention. A horn 2 is bonded to the
vibrating surface of the vibrator 1 and is formed to be elongated toward the tip. Slits 3, 4 and 5
° 6 are provided on the horn tip surface P at positions close to the upper and lower ends. In
addition, the thing inside the slit was only shown by the dotted line. By narrowing the ultrasonic
radiation surface P in this manner, the directivity characteristics of the ultrasonic energy to be
emitted from this can be obtained in the form of a plate which is narrow in the vertical direction
and wide in the horizontal direction, as shown mosaically in FIG. In order to obtain a narrow
beam both in the vertical [111111] direction and in the horizontal direction, the radiation surface
P should be as wide as possible. That is, the desired directivity characteristic is obtained by the
shape of the horn 2. In the present invention, in order to further reduce the side lobes, the upper
and lower ends of the surface P are provided with slits 3, 4 and 5 whose depth is designed to be
a half wavelength as shown in the figure. In this way, the radiation pressure in this portion is
reduced and the side lobes are minimized. In the experiment, the one with 50 KC is used as the
ferrite vibrator 1, the horn 2 is made of aluminum, the area S1 is 4 × 2 crr L, the S2 is 0.6 × 9.4
cm, J! -Using the one with 5.4 accuracy, the result of using 4 slits with a width of 2 3 and a depth
of 3.4 mm at positions 3 mm and 8 よ り away from the upper and lower ends respectively The
sound pressure half-half angle in the vertical direction was 2.5 degrees, and that in the horizontal
direction was 45 degrees. Also, as shown in Fig. 2a, the directional characteristics in the case of
only the vibrator without the horn 2 were the sound pressure half angle half angle 6 ° and the
first side lobe was as much as 22% of the main lobe. And, as in b, the half-half angle is very sharp
at 2.5 degrees, and when the slit is drilled, the side lobe can be improved by as much as 10%
(about 20 db) or more like C. The As described above, according to the present invention, even if
the same vibrator is used, an ultrasonic beam having desired directivity can be obtained by
preparing various horn shapes to be combined therewith. By forming the slits, there is an
advantage that not only the area weight but also the topological weight can be added to the
energy and the side lobes can be greatly reduced.
The value of L in FIG. 1 is determined by the following equation. [111111] EndPage: 1 but