JPS61146098A - Composite type ultrasonic wave transmission/reception device - Google Patents

Abstract

PURPOSE:To detect a curved surface with high accuracy by providing an electrode divided into >=3 on the rear side of a recessed oscillator which transmits/ receives ultrasonic waves and one electrode at the front side, and crossing the center axes, of ultrasonic beam sent from the divided electrodes. CONSTITUTION:An electrode 2 is divided into at least 3 and they are attached to the rear side of the recessed oscillator 1 which transmits/receives ultrasonic waves, and an electrode 3 is attached to the front side of oscillator, and an acoustic adjusting layer 5 covers over it. The divided electrodes are so located that the central axes of ultrasonic beam generated by them shall cross at the focal point of the recessed oscillator 1, and are electrically connected to a transmitter 8 and receiver by a lead wire 6 through a terminal 7. When the divided electrode is alternatively driven, the detection angle is enlarged, by facilitating the retrieval of the object having the curved surface. Also, when the transmitter/receiver is placed at a vertical position per to the object, and when the divided electrodes are parallelly driven, the beam radius becomes small, and the detection capacity is enhanced. This is most suitable for welding robots.

Description

[Detailed description of the invention] Industrial application field The present invention transmits and receives ultrasonic waves in the air, and
Alternatively, it relates to an ultrasonic transducer that recognizes the shape of an object.

2. Description of the Related Art Recently, ultrasonic transducers have come to be widely used in the fields of range finders and proximity sensors. This ultrasonic transducer consists of a single ultrasonic transducer, for example, as described in Yoshiaki Yamamoto, "Acoustic Recognition," Electronic Technology Vol. 26, No. 6, PP52.
There are known ultrasonic vibrators that utilize the bimorph structure of piezoelectric ceramic vibrators, as summarized in No. 57, and capacitor-type ultrasonic vibrators. These are tens of KHz
However, the directivity of the ultrasonic beam is wide, and it cannot be used as an ultrasonic sensor for tracking extremely small objects or steps such as welding lines.

On the other hand, as a composite type ultrasonic transducer, for example, an annular array type probe used in medical diagnostic equipment is known. A 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 transducer, 2 is a divided electrode provided concentrically on the back of the concave transducer, 3 is an electrode provided on the front side of the ultrasonic transducer, 4 is a back load, and 5 6 is an acoustic matching layer, 6 is a lead wire connected to each electrode, and 7 is a drive terminal connected to each lead wire 6. The portions of the concave transducer provided with the divided electrodes 2 can each operate as independent ultrasonic transducers, and transmit and receive ultrasonic waves into the subject using transceivers (not shown).

When a composite ultrasonic transducer with such a configuration is used in the air, the central axes of the ultrasonic beams emitted from the individual ultrasonic transducers all lie on the same straight line. On the other hand, the ultrasonic beam diameter changes depending on each ultrasonic transducer, and the ultrasonic beam from the outermost portion is the narrowest.

On the other hand, in welding robots and the like, there are many requests for sensors for automatically detecting steps in overlap welding. In this case, the conditions required of the sensor for automatic detection are, for example, considering the size of the object from a flat plate type to a three-dimensional curved surface type, the following characteristics are required of the detector.

(1) It is possible to detect sloped parts. (2) The detection accuracy of stepped parts must ultimately be as high as 1 trend or less. (3) The detection speed is fast. (2) In order to achieve this, the ultrasonic transducer must have an ultrasonic frequency of about 1 MHz and be a focus type vibrator.

Problems to be Solved by the Invention The conventionally used single type ultrasonic transducer of several tens of KH2 does not have a high precision detection ability of 1H or less even if a plurality of these are used as a composite ultrasonic transducer. Does not occur.

Next, when using a conventional hybrid ultrasonic transducer used for medical purposes, as shown in Figure 6, in order to achieve detection accuracy, it is necessary to transmit and receive an ultrasonic frequency of about 1 MHz. It is necessary to wave. In the case of a PZT-based piezoelectric ceramic resonator, a concave resonator with a thickness of about 21flI is used, and a diameter of 20
ff, if a concave surface with a radius of curvature of 601 m is used, 1 fl
The following ultrasound beam diameters are obtained. There is also the advantage that the delay of each independent ultrasonic transducer can be controlled to control the focus point when transmitting and receiving waves; in this case, the transmitting section.

This has the disadvantage that the configuration of the receiving section is complicated. On the other hand, using such an ultrasonic transducer as a sensor for a welding robot,
When used to detect objects with curved surfaces, the detectable viewing angle is about 10 degrees in solid angle, so it is necessary to always set the ultrasonic transducer at a position close to perpendicular to the curved surface, making it difficult to detect slopes. This poses a problem in that the robot's movement is restricted, and the detection time becomes long.

The present invention solves the above problem, and includes a transmitter.

It is an object of the present invention to provide a composite ultrasonic transducer that has a simple receiving section, enables detection of slopes, and increases detection speed.

The means for solving the problem is to achieve the above-mentioned object, and includes a concave transducer for transmitting and receiving ultrasonic waves, at least three divided electrodes provided on the back side of the concave transducer, and the concave transducer. The split electrodes are provided with electrodes provided on the front side of the vibrator and lead wires connected to each of the electrodes, and the split electrodes are arranged so that the central axes of the ultrasound beams transmitted and received from the split electrode portions intersect with each other. The present invention provides a composite ultrasonic transducer characterized in that:

According to the above-mentioned structure, the present invention drives each divided electrode independently for rough sensing of an object, and simultaneously drives it for higher detection resolution, thereby enabling sensing from multiple directions and detecting slopes. This makes it possible to improve the detection speed.

EXAMPLE A first example of the present invention will be described below 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 concave vibrator made of, for example, PZT-based piezoelectric ceramic, and 2 is a dividing electrode provided on the back side of the concave vibrator. The dividing method is shown in FIG. 3 is an electrode provided on the front side of the concave vibrator, 4 is a rear load, 6 is an acoustic matching layer, 6 is a lead wire connected to the split electrode 2 and electrode 3, and is an input terminal 7.
The transmitter 8 and the receiver 9 are electrically connected through the transmitter 8 and the receiver 9 . 10 is an ultrasonic beam radiated into the air. Second
The figure shows the divided electrodes of this embodiment, and there are a total of six divided electrodes 21.
2b, 2c, 2d.

It is composed of 2e.

The operation of the above configuration will be explained below.

First, the state of the ultrasonic beam 1o that is sequentially driven and transmitted and received from the divided electrodes 2a to 2e is as shown in FIG. Here, the central axis along the traveling direction of the ultrasonic beam transmitted and received from the divided electrodes 22L to 2e is radiated from four directions with 11'a- as the center, like 11a to 11el, corresponding to each divided electrode. and intersect at focal point 12. The beam diameter ω at the focal point 12 of these ultrasonic beams is determined by the following equation.

F fist ■ -f Here, F is the distance from the concave vibrator 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, F2 50mm, D=10wz, V=-3
When 4 om/s and f=1 MHz, the ultrasonic beam diameter ω is in the order of 1.7. Further, the angle between the central axes 11ia and 11d is about 21.8 degrees. The azimuth that can be detected with one ultrasonic beam is approximately 10 degrees in solid angle, but when this composite ultrasonic transducer is used, the azimuth that can be detected is approximately 300 degrees.
This makes it easier to track objects with curved surfaces.

Furthermore, once the position of the object is determined and the composite ultrasonic transducer is set almost perpendicular to the object, the individual ultrasonic transducers are electrically connected in parallel and driven and received simultaneously. This makes it possible to further narrow the diameter of the emitted ultrasonic beam and improve the aperture detection resolution, as well as to increase the wave transmission and reception sensitivity.

As is clear from the above description, according to this embodiment, multiple ultrasonic transducers are configured with divided electrodes on one concave transducer, and the structure enables independent operation, so detection is possible. The possible azimuth angles can be expanded, and it is also possible to detect objects with curved surfaces. Furthermore, by driving at the same time, it is possible to improve the detection accuracy, and it is easy to achieve a detection accuracy of 1 m or less.

Next, a second embodiment of the present invention will be described.

FIG. 4 is a schematic diagram of a complex wave ultrasonic transmission/reception system according to a second embodiment of the present invention. In Figure 4,
The difference from the configuration in FIG. 1 is that each ultrasonic transducer 13
The three electrodes 2L to 13C are arranged in rotationally symmetrical positions with respect to the center of the concave vibrator 1, and the electrodes 14 are separately provided in the remaining parts.

The operation of the above configuration will be explained below.

The operation of each ultrasonic transducer is the same as in the first embodiment, and by sequentially emitting ultrasonic waves from three directions, detection with a wide viewing angle is possible. Next, when the position of the object is determined, if the remaining electrodes 14 are also used for wave transmission and reception at the same time, an ultrasonic beam with higher sensitivity and fewer side lobes than in the first embodiment can be obtained.

As described above, similar to the first embodiment, even when the object has a curved surface, the detection ability is high because the viewing angle is wide, the sensitivity is high, and there are fewer side lobes. A signal with a good S/N ratio can be received.

Note that although a spherical concave vibrator is used in the above description, a concave vibrator of other shapes such as a paraboloid may also be used. Furthermore, instead of making the electrode area the same, for example,
In the first embodiment, the central electrode may be made larger and the surrounding electrodes may be made smaller to further widen the viewing angle.

Effects of the Invention As described above, the present invention provides a plurality of divided electrodes on the back side of a concave transducer to constitute an independent small ultrasonic transducer, and transmits and receives ultrasonic waves from a plurality of directions. Detection with a wide field of view becomes possible, and it becomes easier to detect objects with curved surfaces. Furthermore, detection accuracy can be achieved at 1jIM or less, and it has high resolution characteristics. When such a composite ultrasonic transducer is used in a sensor such as a welding robot,
Since it is possible to detect a wide field of view, the search time for the target object is shortened, and fast processing capacity is obtained, which is highly effective.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a composite ultrasonic transducer according to a first embodiment of the present invention, FIG. The figures show the central axis of the ultrasonic beam emitted from the composite ultrasonic transducer, FIG. The figure is a schematic configuration diagram of a conventional composite ultrasonic transducer, in which a is a rear view and b is a plan view. 1...Concave vibrator, 2.2N~26,13゜1
3a to 13C...divided electrode, 3...electrode, 4...back load, 5...acoustic matching layer, 6...lead line. Name of agent: Patent attorney Toshio Nakao and 1 other famous person 1
Figure 4 Figure 5 (a) (υ

Claims (2)

[Claims] (1) a concave vibrator that transmits and receives ultrasonic waves, and at least three divided electrodes provided on the back side of the concave vibrator;
It comprises an electrode provided on the front side of the concave transducer and a lead wire connected to each of the electrodes, so that the central axes of the ultrasonic beams transmitted and received from the divided electrode portions intersect with each other. A composite ultrasonic transducer characterized in that split electrodes are arranged. (2) The composite ultrasonic transducer according to claim 1, wherein the divided electrodes are arranged at rotationally symmetrical positions with respect to the center of the concave transducer.