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JPS61146098

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DESCRIPTION JPS61146098
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
ultrasonic transducer that transmits and receives ultrasonic waves in the air and recognizes the
distance to an object or the shape of an object. 2. Related Art Recently, ultrasonic transducers
have been widely used in the field of range finders and proximity sensors. As this ultrasonic
transducer is composed of a single ultrasonic transducer, for example, as described in the
document, Yoshiaki Yamamoto, "Acoustic recognition", Electronic Technology, vol. 26, No. 6,
PP52-57. There is known one using a bimorph structure or a condenser type ultrasonic
transducer. These can transmit and receive ultrasonic waves of several tens of KHz to about 200
KHz, but as ultrasonic sensors that follow the step of the ultrasonic beam with wide directivity,
extremely small ones, or those with steps such as welding lines. Can not be used. On the other
hand, as a composite ultrasonic transducer, for example, an anilula array type probe used in a
medical diagnostic apparatus is known. The conventional composite ultrasonic transducer will be
described below with reference to FIG. a shows a front view and b shows a rear view. In FIG. 6, 1
is a concave vibrator, 2 is a divided electrode provided concentrically on the back of the concave
vibrator, 3 is an electrode provided on the front side of the ultrasonic vibrator, 4 is a back load, 5
Is an acoustic matching layer, 6 is a lead connected to each electrode, and 7 is a drive terminal
connected to each lead 6. The portion of the concave vibrator provided with the divided
electrodes 2 can operate as an independent ultrasonic transducer, and an ultrasonic wave (not
shown) is transmitted / received into the subject by a transmitter / receiver not shown. When the
composite ultrasonic transducer having such a configuration is used for airborne applications,
the central axes of ultrasonic beams emitted from the individual ultrasonic transducers are all on
the same straight line. On the other hand, the diameter of the ultrasonic beam varies with each
ultrasonic transducer, and the ultrasonic beam from the outermost part becomes the narrowest.
On the other hand, in welding robots and the like, there are many requests for sensors for
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automatically detecting stepped portions in case of lap welding. In this case, the following
characteristics are required for the detector in terms of, for example, a flat type to a threedimensional curved type as an object, as a condition required for a sensor for performing
automatic detection. (1) It is also possible to detect the slope (2) The detection accuracy of the
step is finally high accuracy of 1 ? or less (3) high detection speed is satisfied (2) For this
purpose, it is necessary to use an ultrasonic frequency of about 1 MHz as an ultrasonic
transducer and to use a focus type transducer.
Problems to be solved by the invention With a single type ultrasonic transducer of several tens of
KH2 conventionally used, even if it is used as a composite type ultrasonic transducer by using a
plurality of these, a high accuracy detection capability of 1 H or less is obtained. It does not
occur. Next, as shown in FIG. 6, in the case of using a composite ultrasonic transducer
conventionally used for medical treatment, as in the above, in order to obtain detection accuracy,
an ultrasonic frequency of about 1 MHz is transmitted and received. It is necessary to wave. In
the case of using a PZT-based piezoelectric ceramic vibrator with a concave vibrator having a
thickness of about 21 flI and a diameter of 20 ff and a concave curvature radius of 601 m, an
ultrasonic beam diameter of 1 fl or less can be obtained. In addition, there is an advantage that it
is possible to control the focus point by delaying and controlling each of the independent
ultrasonic transducers, and in this case, the transmission unit. There is a drawback that the
configuration of the receiving unit is complicated. On the other hand, when such an ultrasonic
transducer is used as a sensor for a welding robot and used to detect an object having a curved
surface, the detectable viewing angle is approximately 10 ░ in solid angle, so it is always
perpendicular to the curved surface. It is necessary to set an ultrasonic transducer at a close
position, which makes it difficult to detect a slope, restricts the movement of the robot, and
causes a long detection time. The present invention solves the above problems, and a transmitter.
It is an object of the present invention to provide a composite ultrasonic transducer that
simplifies the receiving unit, enables detection of a slope, and accelerates the detection speed.
Means for solving the problem is to achieve the above object, and a concave vibrator for
transmitting and receiving an ultrasonic wave, at least three divided electrodes provided on the
back side of the concave vibrator, and the concave face. An electrode provided on the front side
of the vibrator and a lead wire connected to each of the electrodes, and the divided electrodes are
arranged such that central axes of ultrasonic beams transmitted and received from the divided
electrode portions intersect with each other It provides a composite ultrasonic transducer
characterized in that it is arranged. According to the present invention, according to the abovementioned configuration, in the case of rough sensing of an object, each divided electrode is
driven independently, and in the case of enhancing detection resolution, sensing is performed
from plural directions and slope detection by simultaneously driving. And to improve the
detection speed. Embodiment Hereinafter, a first embodiment of the present invention will be
described with reference to the drawings. FIG. 1 is a side sectional view of a composite ultrasonic
transducer according to a first embodiment of the present invention. In FIG. 1, 1 is a spherical
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concave vibrator made of, for example, a PZT piezoelectric ceramic, 2 is a divided electrode
provided on the back side of the concave vibrator, and the dividing method is shown in FIG.
3 is an electrode provided on the front side of the concave vibrator, 4 is a back load, 6 is an
acoustic matching layer, 6 is a lead wire connected to the divided electrode 2 and the electrode 3,
and a transmitter 8 and a receiver through an input terminal 7 It is electrically connected to 9.
10 is an ultrasonic beam emitted into the air. FIG. 2 shows the divided electrodes of this
embodiment, and six divided electrodes 21.2b, 2c and 2d, one on each of the upper and lower
and right and left sides of the central divided electrode 2a. It consists of 2e. The operation of the
above configuration will be described below. First, the state of the ultrasonic beam 1o which is
driven in order from the divided electrodes 2a to 2e and transmitted / received is as shown in
FIG. Here, the central axis along the traveling direction of the ultrasonic beam transmitted /
received from the part of the split electrodes 22L to 2e corresponds to each split electrode and
radiates from four directions centered on 11'a-like 11a to 11el. And intersect at focal point 12.
The beam diameter ? at the focal point 12 of these ultrasonic beams is determined by the
following equation. F-f Here, F is the distance from the concave transducer surface to the focal
point 12, D is the diameter of the electrode, ? is the speed of sound in air, and f is the ultrasonic
frequency. From this, assuming that F is 50 mm, D is 10 wz, V is -34 om / s, and f is 1 MHz, the
ultrasonic beam diameter ? is in the order of 1.7. The angle between the central axes 11ia and
11d is about 21.8 degrees. The azimuth that can be detected by one ultrasonic beam is around
10 ░ in solid angle, but the azimuth angle that can be detected by using this composite
ultrasonic transducer is expanded to approximately 300, and the object with a curved surface is
It is also easy to follow. Furthermore, when the position of the object is determined, and the
composite ultrasonic transducer is set to be substantially perpendicular to the object, the
individual ultrasonic transducers are electrically connected in parallel, simultaneously driven,
and received. This makes it possible to further narrow the diameter of the ultrasonic beam to be
emitted and to improve the aperture detection resolution as well as to enhance the transmission /
reception sensitivity. As is apparent from the above description, according to the present
embodiment, since a plurality of ultrasonic transducers are configured by electrode division on
one concave vibrator to enable independent operation, detection is possible. The azimuth angle
which can be made can be expanded and detection of the object with a curved surface can also
be made possible. Further, by simultaneously driving, it is also possible to enhance the detection
accuracy, and it is easy to set the detection accuracy to 1 m or less. Next, a second embodiment
of the present invention will be described. FIG. 4 is a schematic block diagram of composite type
ultrasonic wave transmission / reception in the second embodiment of the present invention. In
FIG. 4, the difference from the configuration of FIG. 1 is that three ultrasonic transducers 132L to
13C are disposed at rotational symmetry positions with respect to the center of concave
transducer 1, and the remaining ones are different. It is that the electrode 14 was provided
separately also in the part.
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The operation of the above configuration will be described below. The operation of each
ultrasonic transducer is the same as in the first embodiment, and ultrasonic waves can be emitted
sequentially from three directions to enable wide detection of the viewing angle. Next, when the
position of the object is determined, if the remaining electrodes 14 as well as the other electrodes
14 are used simultaneously for transmission and reception, an ultrasonic beam with higher
sensitivity and fewer side ropes than in the first embodiment can be obtained. As described
above, according to this embodiment, as in the first embodiment, even when the object has a
curved surface, the detection capability is high because the viewing angle is wide, and the
sensitivity is high, and furthermore, the side lobes are small. Signals with good S / N ratio can be
received. In the above description, a spherical concave vibrator is used, but a concave vibrator
having another shape such as a paraboloid may be used here. Furthermore, the electrode area is
not the same. For example, in the first embodiment, the central electrode may be large and the
peripheral electrodes may be small to widen the viewing angle. As described above, according to
the present invention, a plurality of divided electrodes are provided on the back side of the
concave vibrator to configure an independent small ultrasonic transducer, and ultrasonic waves
are transmitted and received from a plurality of directions. A wide field of view can be detected,
and detection of a curved object can be facilitated. Furthermore, the detection accuracy can be
performed at 1 jIM or less and has high resolution characteristics. When such a composite
ultrasonic transducer is used for a sensor such as a welding robot, a wide field of view can be
detected, so the search time for the object can be shortened, quick processing capability can be
obtained, and the effect is large. .
[0002]
Brief description of the drawings
[0003]
FIG. 1 is a cross-sectional view of a composite ultrasonic transducer according to a first
embodiment of the present invention, and FIG. 2 is a layout diagram of divided electrodes on the
back surface of the concave transducer of the composite ultrasonic transducer, The figure shows
the central axis of the ultrasonic beam emitted from the composite ultrasonic transducer, and
FIG. 4 shows the arrangement of the split electrodes on the back surface of the concave
transducer in the second embodiment of the present invention, the sixth The figure is a
schematic block diagram of a conventional composite ultrasonic transducer, where a is a rear
view and b is a plan view.
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1 ...... concave transducer, 2.2N?26,13 ░ 13 a to 13 c ...... divided electrodes, 3 ...... electrode, 4
...... the backing, 5 иииииии Acoustic matching layer, 6 иииииииии Lead wire. Name of agent Attorney Nakao
Toshio Other 1 confectionery 1 figure @ t @ figure 4 figure 5 (a) (?
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