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BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
ultrasonic transducer used in an ultrasonic distance measuring device or the like. The
configuration of the conventional example and its problems The frequency used in the
conventional ultrasonic distance measuring apparatus in the air is a frequency of about 20 kHz
to 1 oo kHz, the ultrasonic wavelength is relatively long, and the outer rice noise level is also
high. It was difficult to measure distance 1 with high accuracy and distance 4 with a distance of
10 cm or less. For this reason, attempts have also been made to use an ultrasonic transducer
capable of transmitting and receiving an ultra- # wave frequency of about several six to one inch.
In the case of using this one-piece ultrasonic transducer for a distance measurement device or
the like, fluctuations in air due to wind or temperature change cause large fluctuations in the
transmission and reception signals of the ultrasonic wave, resulting in deterioration of
measurement accuracy. In particular, when the ultrasonic transducer is subjected to a fan-shaped
scan to perform a wide range of measurement, air fluctuation caused by the rotation of the
ultrasonic transducer becomes a problem. Furthermore, in the conventional ultrasonic
transducer, as shown in FIG. 1, the structure is as shown in FIG. 1, from the piezoelectric vibrator
1, the sound wave festival unit 2 provided on the front surface, and the rear load 3 provided on
the rear surface. It has become. As is well known, the characteristic of the material used for the
acoustic matching body 2 is desirably a value close to one layer square of the product of the
pressure of the acoustic impedance of each of the pressure transducer 14 and air, and thus the
piezoelectric vibration When a general piezoelectric ceramic material is used as the element 1,
two layers m ? и S correspond to 0 to 1 X 106 as acoustic impedance suitable for the acoustic
matching body 2. However, even if these ranges are used, there is a drawback that the frequency
band characteristics of the ultrasonic transducer are narrow and the response characteristics
deteriorate because the echo impedance difference between the piezoelectric vibrator 1 and air is
extremely large as about 105: 1. . On the other hand, in a medical ultrasonic transducer, there is
also well known a system in which a piezoelectric transducer for transmitting and receiving
ultrasonic waves of several liters is mechanically scanned at high speed mechanically at high
speed in an ultrasonic cell to obtain five ultrasonic tomographic units. In this case, however, the
object of the extraneous material waves in this case is the human body, and if the VC ultrasonic
wave in the air is emitted, the sensitivity becomes extremely low and it becomes difficult to use.
SUMMARY OF THE INVENTION The present invention has been made to solve the abovementioned conventional problems, and it has very few air fluctuations even if it scans an
ultrasonic beam at high speed for 5 air use, and it is about 1 stone. It is an object of the present
invention to provide an efficient ultrasonic transducer which can operate sufficiently even in the
ultrasonic cyclic mantissa band and which can be used for an ultra-clear distance measuring
apparatus, an ultrasonic imaging apparatus or the like. Configuration of the Invention In order to
achieve this object, the present invention manages the acoustic matching between the
piezoelectric vibrator and the liquid which is the I) E electrovibration excited sound wave
propagation medium, and is provided in the 1iJ curve of the piezoelectric vibrator. An ultrasonic
cell incorporating the first acoustic matching body, an acoustic window provided in front of the
ultrasonic cell, and a second acoustic wave for efficiently transmitting and receiving ultrasonic
waves into the air to the O1 J Ultrasonic transmission and reception with matching body and
+ M (j: '4iE is provided. With such a configuration, even if the beam is scanned at a high speed, it
does not shake the whole area of the air, and the loss of ultrasonic waves is extremely reduced,
even in the high frequency region. It is a long distance reconnaissance. Description of the
Embodiments Embodiments of the present invention will be described below with reference to
the drawings. FIG. 2 is a cross-sectional view showing an ultrasonic transducer according to an
embodiment of the present invention. In the same figure, the ultrasonic signal 4 of several 6kll +
radiated from the piezoelectric vibrator 1 made of piezoelectric ceramic or the like is a first
acoustic matching member 5 (for example, 1 made of tungsten epoxy) provided on the front
surface of the piezoelectric vibrator 1. Depending on the layer structure, or a two-layer structure
consisting of baccarus and epoxy) efficiently consisting of water or oil such as silicone oil or
liquid such as fluorine inert liquid such as difloryl or Fluorinert (brand name) Super) -1 wave
propagation medium 6 all pass, it passes acoustic window 8 of the ultrasonic self which consists
of polyethylene or dimethyl pentene etc, the 2nd acoustic matching body 91tl which is provided
in front of acoustic window 8 If it is silicone rubber membrane And one layer til structure made
of silicone rubber film with plastic hollow sphere, or two layers of hollow sphere with different
acoustic impedance The ultrasonic signal 11 efficiently radiated into the air 10 by the two-layer
structure made of silicone rubber or epoxy resin is reflected by the object 12, received again by
the piezoelectric vibrator 1 through the same propagation path, The distance = t nttl and
ultrasound + @ are provided at home by a signal processing system that is not used. In the case
where the piezoelectric vibrator 1 performs fan-shaped scanning, it is attached to the tip of a
rotating system or a reciprocating vibration system to enable high-speed scanning. Here, to scan
the rotation system, the pulley 16 provided on the piezoelectric vibrator 1 side is rotated via the
belt 16 from the scanner (the motor 14 provided in the 71713), and the piezoelectric vibrator 1
is Rotate. Here, 3 is a rear surface load, 17 is a rotation center, 18 is a sound absorbing body for
absorbing unnecessary super # his signal in the ultrasonic self, and is provided in a portion other
than the acoustic window 8. When the ultrasonic transducer as described above is used, the field
1iJ and the transducer 1 are scanned at high speed in the ultrasonic self shut off from the air 10,
and the first and second sounds #a! By means of the unions 5 and 9, the acoustic matching
between the piezoelectric vibrator 1 and the ultrasonic wave propagation medium 6 of the liquid
and between the ultrasonic wave propagation medium 6 and the air 10 is achieved respectively.
As described above, according to this embodiment, since the piezoelectric vibrator 1 is
disconnected from the air 10, air fluctuation does not occur even if the scanning mechanism 13
mechanically fixes the plate for commercial transportation.
That is, distance measurement and the like can be performed relatively stably even if ultrasonic
signals of several hundreds or more are transmitted to the air. The first and second acoustic
matching bodies 5 and 9 can be made of easily available matching layers by selecting a filler
material of the ultrasonic wave propagation medium 6, and the sensitivity and frequency band
characteristics can be improved. , Can efficiently transmit and receive the ultrasonic sound e in
the air. In addition, as the shape of the piezoelectric vibrator 1 is generally well-known, in order
to perform focusing, an acoustic lens may be attached to the concave vibrator or the flat and
moving element. Also, the shape of the ultrasonic cell is not limited to the cylindrical shape. FIG.
3 is a cross sectional view showing another embodiment of the present invention. The superblind his / her handset is arranged adjacently and electronically scanned piezoelectric oscillators
19 and 5 with a first acoustic matching body 20 provided in the same manner as in the previous
embodiment, and ultrasound The ultrasonic cell 22 filled with the propagation medium 21, the
acoustic window 23 provided in the ni1 plane thereof, the second acoustic matching body 24
further provided in the fjiJ 1fjl, and the surrounding sound absorbers 25. It comprises a sound
absorber 26 on the back. In such an ultrasonic transducer, since the piezoelectric vibrator group
19 is electronically switched in sequence and transmitted / received, distortion due to vibration,
a limit of durability, and the like are alleviated because mechanical constant distortion does not
occur. Ru. Further, the ratio of the acoustic impedance between the piezoelectric vibration
element group 19 and the 'MA sound wave propagation medium 21 is approximately (10 to 30):
1, and a wide band frequency characteristic is obtained by the first acoustic matching body 20.
Furthermore, the acoustic impedance ratio between the ultrasonic wave propagation medium 21
and the acoustic window 23 and the air 27 according to the second acoustic matching body 24 is
a train having the ultrasonic wave propagation medium 21 and the acoustic window 23 with
substantially the same value, When water and soft polyethylene are combined completely,
approximately 3 О 103: 1 9, which is extremely small compared to the ratio (105: 1) in the
conventional structure, it is easy to obtain the acoustic matching condition, and the broadband
characteristic is You will get it. This leads to the improvement of the pulse response, enables
transmission and reception of short ultrasonic pulse signals, and improves the accuracy of
ultrasonic distance measurement. In order to reduce the effects of the present invention, the
present invention provides a piezoelectric vibrator disposed in an ultrasonic wave cell filled with
an ultrasonic wave propagation medium, a first acoustic matching member provided on the front
surface of the piezoelectric vibrator, and + iiJ. An ultra-ff1 Ji transducer comprising an acoustic
window for advancing and retracting an ultrasonic signal provided to the cell and a second
acoustic matching body provided on the outer surface of the acoustic window. Because the
piezoelectric vibrator is isolated from the air, there is no air fluctuation even if the machine scan
is performed at high speed. 5 Further two types of acoustic matching materials can efficiently
emit ultrasonic waves into the air. In the case of using ultrasonic distance 1 measurement, or
ultra-clear wave imaging 1 image l и и ? ? i и can be used to improve the accuracy when used as
a transducer / I '.
Brief description of the drawings
FIG. 1 is a cross-sectional view showing a conventional super-injured supersonic wave
transducer, FIG. 2 is a cross-sectional view of an ultrasonic transducer according to an
embodiment of the present invention, and FIG. It is the same sectional view in an example.
1 и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и Piezoelectric vibrator 5, 20 и и и и 1st
acoustic matching body, 6, 21 и и и и и ultrasonic propagation medium 7, 22 и и и и и и и и и ultrasonic
cell, 8 ----- acoustic window, 9, 24 ..... second acoustic matching body, 13 ... ... scanning
mechanism 14 ... motor, 16 ... ... belt, 19 ииииии Piezoelectric vibration element group.
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description, jps60102577
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