JPS6177499A - Ultrasonic probe - Google Patents

Abstract

PURPOSE:To increase efficiency of a transmitting wave and a receiving wave by polarizing with an electric field impressed between electrodes AB and between electrodes BC in the ultrasonic probe having plurally divided second electrodes. CONSTITUTION:In addition to electrodes B divided plurally so that it can electrically drive to the second surface of the plate-shaped piezoelectric body independently, electrodes C having a shape separating them mutually and electrically are provided, an electric field is impressed even in the thickness direction and polarizing is executed. An arrow mark in the drawing shows an electric force line in polarizing typically. An electric field is impressed not only between adjoining electrodes B-C on the second surface but also between an electrode on the second surface and an electrode on the first surface B-C and C-A, and electrode processing is executed. By the effect of the processing, when signal electric potential on the basis of an electric potential of the electrode A is given to the electrode B or C, a transmitting wave efficiency or a receiving efficiency is widely improve compared with a conventional efficiency.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to an electronic scanning type or electronic focusing type array probe used in an ultrasonic diagnostic device, an ultrasonic flaw detection device, an ultrasonic treatment device, etc. .

[Background of the invention]

Conventional ultrasonic probes of this type cut a plate-shaped piezoelectric material uniformly polarized in the thickness direction into thin strips, attach electrodes to the front and back surfaces, and detect the thickness vibration of each piece of wood. It has a structure that converts between ultrasonic waves and electrical signals. However, in recent years, the spatial resolution required in ultrasonic diagnosis and measurement has progressed to higher levels, and the strip processing technology required for this is approaching its limit. In other words, in order to achieve high resolution, it is necessary to increase the ultrasonic frequency or increase the aperture used for transmitting and receiving ultrasonic waves, but in either case, the width of the element must be narrowed. This is a major problem when cutting strips.

Attempts to provide an electronic scanning type or an electronic focusing type array probe without a cutting process include published patent publications (1982-42968) and (1983-1989).
156295) Van d as described in
Probe structures with an er pauw type structure are already known. Of these, the latter has a uniform electrode on the first surface of the piezoelectric plate and a plurality of drive electrodes B on the second surface, and the polarity of the polarization directly under the adjacent electrode B is have a structure in which the polarities are opposite to each other, and a schematic cross-sectional view of the structure is shown in FIG.

Here, the arrows in the figure indicate the lines of electric force during the polarization process.

However, when trying to transmit or receive sound waves into the medium to be measured through the second surface using the probe having this structure, the following problems occur. Now, consider the case where one divided electrode B3 of electrodes K and B is driven as shown in FIG. Mawashi electrode Bl, B2°B4. Consider that B5 is at ground potential like electrode A. Then, a displacement as schematically shown in FIG. 3 occurs on the second surface of the piezoelectric plate, and the displacement propagates as a surface wave in the direction of the dotted arrow in the figure. Therefore, when a sound wave is transmitted into the medium to be measured through the second surface, in addition to the sound wave due to the original thickness displacement, a surface wave (strictly speaking, it propagates through the interface with the medium in contact with the second surface) A sound wave caused by a boundary wave (boundary wave) is transmitted into the measured medium. Therefore, the directivity characteristic of the split electrode l element becomes as shown in FIG. 4, and an unnecessary response occurs in the direction of the angle θS between the sound velocity of the surface wave and the sound velocity of the medium to be measured. Unwanted responses in element directivity often cause undesired responses in array directivity, and are problematic in this sense.

In addition, when the electrodes are driven fc as shown in Figure 2, not only between the B electrodes but also between the drive electrode B3 and the electrode A on the first surface as shown by the dotted arrow in the figure. However, in the polarization treatment method shown in FIG. 1, polarization parallel to these lines of electric force is not formed.

Therefore, the second problem occurs when the displacement caused in the piezoelectric body by the lines of electric force is only slight, and the corresponding power is mostly reactive power.

[Purpose of the invention]

In view of the problems in the prior art described above, a first object of the present invention is to provide an ultrasonic probe with fewer unnecessary responses caused by the generation of surface waves.

A second object of the present invention is to provide an ultrasonic probe with high transmission or reception efficiency.

[Summary of the invention]

In order to achieve the first object described above, the present invention proposes a probe structure that transmits and receives sound waves into a medium to be measured via the first surface on which the electrode A is attached. Another feature of the present invention is to apply an electric field not only between the B electrodes but also between the electrodes A and B to achieve polarization, in order to achieve the second object described above.

[Embodiments of the invention]

Examples of the present invention will be described in detail below.

When using a piezoelectric plate having the polarization structure shown in FIG. 1 to transmit or receive sound waves into the medium to be measured via the first surface on which the electrode A is attached, the directivity of one divided electrode element is as follows: It will look like Figure 5. What is strikingly different from FIG. 4 in the case of transmitting or receiving sound waves through the second surface is that there is almost no response corresponding to surface waves. The first problem has been solved.

FIG. 6 shows an embodiment of a probe according to the present invention in which a back loading material and a matching layer are added. The matching layer 2 is placed between the first surface on which the electrode A is attached and the medium to be measured, and the back loading material 3 is adhered to the second surface on which the split electrode B is attached.

As shown in FIG. 7, the second proposed probe of the present invention has an electrode B on the second surface of the piezoelectric plate, which is divided into a plurality of electrodes so that they can be electrically driven independently. The arrows in the figure indicate the lines of electric force in the polarization process. It is shown schematically.

Polarization treatment is performed not only between adjacent electrodes on the second surface (between B and C) but also between the electrodes on the second surface and the electrodes on the first surface (
An electric field is also applied between the electrodes B-A and C-A, which is different from the case of FIG. 1, in which polarization is applied only between the electrodes on the second surface. Due to the effect of this processing, the wave transmission efficiency or wave reception efficiency when applying a signal potential based on the potential of electrode A to electrode B or C is higher than that of a probe with the structure shown in Figure 1. This improves the second problem in the prior art.

Further, a similar embodiment is shown in FIG. in this case,
During polarization processing and operation, the electrode C is given the same polarity as the electrode. Unlike the case in FIG. 7, a signal potential independent of the 4th position of electrode A is applied only to electrode B. In the processing of the 4th signal in the example of Fig. 7, electrode B
It was necessary to treat the signal of the electrode C and the signal of the electrode C with different codes, but the example shown in FIG. 8 is characterized in that this is not necessary because only the electrode B is used as the signal electrode.

FIG. 9 shows an example in which both the first proposal and the second proposal of the present invention are implemented. This uses the plate-shaped piezoelectric material l shown in FIG.
Glue the back load material 3 to the surface and drill holes. This structure simultaneously solves the first and second problems in the prior art.

In the above explanation, for convenience of explanation, the linear one-dimensional array type probe was mainly described, but the scope of application of the present invention is not limited to this. This also extends to various two-dimensional arrays.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to provide an ultrasonic probe with high transmission efficiency or reception efficiency and small unnecessary response on a piezoelectric plate without cutting. , the industrial significance of the present invention is significant.

[Brief explanation of the drawing]

Figure 1 shows the structure of an ultrasonic probe using a plate-shaped piezoelectric material according to the prior art, and Figure 2 shows the lines of electric force during operation of the probe in Figure 1.
3 shows the generation of surface waves during operation of the probe shown in FIG. 1, FIG. 4 shows the directivity characteristics of the probe shown in FIG. 1, and FIG. Directional characteristics of tentacles, Part 6
Figure, Figure 7. FIGS. 8 and 9 each show an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Plate-shaped piezoelectric body, 2... Matching layer, 3... Back load material, A... Electrode on the surface of the plate-shaped piezoelectric body box 1, B...
Divided electrodes on the surface of the plate-shaped piezoelectric box 2, C... electrodes having a shape that isolates the divided electrodes B from each other. Rod 1 Figure C 2nd Eye 3 Figure Thread) Rei)・1 0 His S calculation 50 1 Fake・Seme 4E Rod 9 trouble

Claims (1)

[Claims] 1. The first surface of the plate-shaped piezoelectric body is provided with an electrically uniform first electrode, and the second surface is provided with a plurality of electrically uniform first electrodes so that they can be electrically driven independently. An ultrasonic probe having a second electrode divided into two electrodes, the ultrasonic probe transmitting or receiving sound waves into a medium to be measured via the first surface. 2. The first surface of the piezoelectric plate is provided with an electrode A that is uniform in terms of ventilation, and the second surface is provided with an electrode B that is divided into a plurality of parts so that they can be electrically driven independently; It is characterized by comprising an electrode C provided in a shape that electrically isolates the divided electrodes from each other in the gap between the divided electrodes B, and polarization processing is performed by an electric field applied between the electrodes AB and between the electrodes BC. Ultrasonic probe.