JPH09327096A - Ultrasonic wave probe and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain high accuracy for a finished size by reducing production of a bent of an ultrasonic vibrator of the ultrasonic wave probe consisting of lamination of a plurality of piezoelectric element layers formed to be boards of a prescribed thickness. SOLUTION: An ultrasonic wave vibrator 1 is formed by laminating a plurality of piezoelectric element layers each formed to be a board of a prescribed thickness, external electrodes 4a, 4b are formed piezoelectric elements 5a-5c laminated in this way and inner flat electrodes 6a, 6b are formed to borders of the layers. One or a plurality of deformation preventing flat members 7 are inserted at an equal interval in the broadwise direction of the piezoelectric elements and the outer electrodes 4a, 4b on the uppermost and the lower most sides are connected to the different inner electrodes 6b, 6c at an interval of one layer and the deformation preventing flat members 7 are insulated and in this state, the entire piezoelectric elements are alternately polarized in opposite direction in the laminating direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic probe that emits an ultrasonic wave and receives a reflected wave thereof in an ultrasonic diagnostic apparatus, and more particularly to a piezoelectric element formed in a plate shape having a predetermined thickness. TECHNICAL FIELD The present invention relates to an ultrasonic probe capable of reducing the occurrence of warpage of an ultrasonic transducer formed by laminating a plurality of layers and achieving a highly accurate finished size and size, and a manufacturing method thereof.

[0002]

2. Description of the Related Art A conventional ultrasonic probe of this type, as shown in FIG. 7, is an ultrasonic vibrator 1 which emits ultrasonic waves and receives reflected waves, and a rear surface of the ultrasonic vibrator 1. And a backing material 2 provided on the front surface of the ultrasonic transducer 1 to prevent the ultrasonic waves emitted from the rear surface from returning to the transducer surface again, and the acoustic impedance of the ultrasonic transducer 1 and the sound of the living body. The acoustic matching layer 3 is provided to match the impedance. External electrodes 4a and 4b are provided on the upper surface and the lower surface of the ultrasonic vibrator 1, and the ultrasonic vibrator 1 made of a piezoelectric material is applied by applying a voltage between the electrodes 4a and 4b. Is designed to expand and contract in its thickness direction. Further, in FIG. 7, the ultrasonic transducer 1 is cut into strips with a predetermined pitch width, and a large number of the strip-shaped transducer elements 5, 5, 5.
Shown in an array.

When the ultrasonic transducer 1 having a large number of transducer elements 5, 5, ... Arranged in an array is used for a probe for scanning an electronic sector, the pitch width of each transducer element 5, 5 ,. Should be as small as possible to avoid the occurrence of grating lobes that cause artifacts in the resulting ultrasound image. However, if the pitch width of each of the transducer elements 5, 5, ... Is reduced, the size of the piezoelectric material per element is reduced, and as a result, the electrical capacitance is reduced while the electrical impedance is increased.
Further, in the case of a two-dimensional array probe using the ultrasonic transducer 1 in which a large number of transducer elements 5, 5, ... Are arrayed in a two-dimensional direction, the size of the piezoelectric material per element is further increased. Get smaller. Such a decrease in electrical capacity and an increase in electrical impedance cause poor electrical matching with the transmission circuit system on the ultrasonic diagnostic equipment body side, and the effect of the capacity of the cable connected to the ultrasonic diagnostic equipment body. As a result, the electrical matching is poor and the S / N as the ultrasonic probe is deteriorated.

On the other hand, as a measure for suppressing the decrease of the electric capacity and the increase of the electric impedance per element of the ultrasonic vibrator 1, as shown in FIG. There is a structure in which a material is thinly formed, a plurality of layers, for example, three layers are laminated (5a, 5b, 5c), and the internal electrodes 6a, 6b are inserted between the respective layers. In this case, in the three-layer laminated structure, the outer electrode 4a on the upper surface is connected to the inner electrode 6b on the second layer, and the outer electrode 4b on the lower surface is connected to the inner electrode 6a on the first layer, alternately in the laminating direction. The structure is polarized in the opposite direction. In this way, the piezoelectric elements 5a, 5b, 5c stacked in three layers are acoustically connected in series and electrically connected in parallel. As a result, FIG.
When the single-layer ultrasonic transducer 1 shown in FIG. 8 and the three-layer ultrasonic transducer 1 shown in FIG. 8 have the same thickness, the resonance frequencies of both are the same. Since the thickness per layer is 1 / n and the area is n times as large, the electric capacity becomes n ² times and the electric impedance becomes 1 / n ² .

As a method of manufacturing the ultrasonic transducer 1 having such a multi-layered structure, the piezoelectric elements 5a, 5b, 5c having a multi-layered structure and the internal electrodes 6 inserted between the respective layers are used.
The integral firing lamination method has been used in which a and 6b are fired at the same time to be integrated.

[0006]

However, in the conventional ultrasonic transducer 1 having a multi-layer laminated structure as described above, the piezoelectric elements 5a, 5b, 5c in which a plurality of layers are laminated and the internal electrodes 6a inserted between the respective layers are provided. , 6b are fired at the same time, the warp of the ultrasonic transducer 1 occurs after firing, and
The degree of warpage varies and the thickness also varies, which makes it difficult to manufacture the ultrasonic transducer 1 with a highly accurate size and size. In particular, the above problems become more remarkable as the thickness of the piezoelectric material per layer increases. From this, the conventional ultrasonic probe may not be able to obtain a vibration mode having a single resonance frequency, and may not be able to obtain an ultrasonic image of good quality as an ultrasonic diagnostic apparatus.

Therefore, the present invention addresses such problems and reduces the occurrence of warpage of an ultrasonic transducer formed by laminating a plurality of piezoelectric elements formed in a plate shape having a predetermined thickness. It is an object of the present invention to provide an ultrasonic probe and a method for manufacturing the ultrasonic probe, which can make the finished size and size highly accurate.

[0008]

In order to achieve the above object, an ultrasonic probe according to the present invention is an ultrasonic transducer that emits an ultrasonic wave and receives a reflected wave thereof, and an ultrasonic transducer of the ultrasonic transducer. A backing material provided on the back surface to prevent the ultrasonic waves emitted from the back surface from returning to the transducer surface again, and an acoustic impedance of the ultrasonic transducer provided on the front surface of the ultrasonic transducer and an acoustic impedance of a living body. In an ultrasonic probe having an acoustic matching layer for matching
The ultrasonic vibrator is formed by laminating a plurality of layers of piezoelectric elements formed in a plate shape having a predetermined thickness, forming external electrodes on the entire upper surface and the lower surface of the laminated piezoelectric elements, and Plate-shaped internal electrodes are formed at the boundaries, and one or more plate-shaped deformation preventing materials are inserted at equal intervals within the thickness of each layer of the piezoelectric element. The electrodes are connected to different internal electrodes every other layer, and are insulated from the flat plate-shaped deformation preventing material in each layer, and in this state, the whole piezoelectric element laminated in the plurality of layers is alternately reversed in the laminating direction. The structure is polarized in the direction.

Further, the plate-shaped deformation preventing material inserted within the thickness of each layer of the piezoelectric element is made of a material having the same or equivalent coefficient of thermal expansion as the plate-shaped internal electrode.

Further, the plate-shaped deformation preventing material inserted into the thickness of each layer of the piezoelectric element is made of a conductive material or an insulating material.

In a method of manufacturing an ultrasonic probe as a related invention, a flat piezoelectric element piece is formed with a predetermined thickness by using a piezoelectric material, and one surface of the piezoelectric element piece is used as an internal electrode. Conductive paste is applied by printing, and a plurality of piezoelectric element pieces that are applied by applying this conductive paste are laminated and heat-pressed,
After firing at a predetermined temperature, a conductive paste for external electrodes is baked on the entire upper surface and lower surface of the piezoelectric element pieces laminated in a plurality of layers, and the external electrodes on the upper surface and the external electrodes on the lower surface are different in every plural layers. While being connected to the conductive paste for the internal electrodes and insulated from other conductive pastes, a high DC electric field is applied between the external electrodes on the upper surface and the external electrodes on the lower surface to form the piezoelectric layers laminated. The entire element piece is polarized to form an ultrasonic transducer, and a backing material is provided on the back side of this ultrasonic transducer to prevent the ultrasonic waves from the back surface from returning to the transducer surface again. It is manufactured by providing an acoustic matching layer for matching the acoustic impedance of the ultrasonic transducer and the acoustic impedance of the living body on the front side of the ultrasonic transducer.

Further, the ultrasonic transducer may be formed into an array by cutting the entire piezoelectric element pieces laminated in a plurality of layers and then cutting them into strips with a predetermined pitch width.

[0013]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a partial sectional perspective view showing an embodiment of an ultrasonic probe according to the present invention.
This ultrasonic probe emits ultrasonic waves in an ultrasonic diagnostic apparatus and receives the reflected waves thereof. As shown in FIG. 1, the ultrasonic transducer 1, the backing material 2, and the acoustic matching layer are used. 3 and 3.

The ultrasonic transducer 1 emits ultrasonic waves and receives reflected waves thereof, and is made of a piezoelectric material for converting electric energy and ultrasonic energy. As this piezoelectric material, for example, zircon / lead titanate (PZT) -based piezoelectric ceramics or lead titanate (PZT)
Examples include bTiO ₃ ) -based piezoelectric ceramics. PZT-based piezoelectric ceramics are characterized by a large electromechanical coupling coefficient representing the conversion efficiency between electric energy and ultrasonic energy, a large dielectric constant, and easy electrical impedance matching with an electric circuit system. Also, PbTi
O ₃ -based piezoelectric ceramics are characterized in that the transverse effect vibration coupling is extremely weak, so that unnecessary vibrations are drastically reduced, and the transmission / reception characteristics close to the ideal of pure thickness longitudinal vibration are obtained.

The backing material 2 is provided on the back surface of the ultrasonic vibrator 1 so as to prevent the ultrasonic waves emitted from the back surface from returning to the vibrator surface again. ing. The acoustic matching layer 3 is provided on the front surface of the ultrasonic transducer 1 to match the acoustic impedance of the ultrasonic transducer 1 with the acoustic impedance of the living body, and thereby the vibration of the ultrasonic transducer 1 is generated. Can be efficiently transmitted to the living body. Two acoustic matching layers 3 may be provided. Although not shown in FIG. 1, an acoustic lens may be provided on the front surface of the acoustic matching layer 3.

External electrodes 4a and 4b are provided on the upper surface and the lower surface of the ultrasonic vibrator 1, respectively.
By applying a voltage between both electrodes 4a and 4b, the ultrasonic transducer 1 made of a piezoelectric material is expanded and contracted in the thickness direction to generate ultrasonic waves. Further, in FIG. 1, the ultrasonic transducer 1 is cut into strips with a predetermined pitch width, and a large number of the strip-shaped transducer elements 5,
It is shown that 5, ... Are arranged in an array.

Here, in the present invention, as shown in FIG. 2, the ultrasonic transducer 1 is formed by laminating a plurality of layers of piezoelectric elements 5a, 5b, 5c formed in a plate shape having a predetermined thickness. External electrodes 4a and 4b are formed on the entire upper and lower surfaces of the piezoelectric elements 5a to 5c laminated in a plurality of layers, and flat plate-shaped internal electrodes 6a and 6b are formed at the boundaries between the layers,
Further, one or a plurality of flat plate-shaped deformation preventing members 7, 7, ... Are inserted at equal intervals within the thickness of each layer of the piezoelectric elements 5a, 5b, 5c.

That is, for example, three layers of piezoelectric elements 5a, 5b, 5c each having a thickness of about 0.21 mm are laminated, and each layer 5a,
Plate-shaped internal electrodes 6a and 6b are formed at the boundaries of 5b and 5c, respectively, and two plate-shaped deformation preventing members 7 are arranged at intervals of 0.07 mm within the thickness of each piezoelectric element 5a, 5b and 5c, 7, ... have been inserted. Therefore, the ultrasonic transducer 1 according to the example of FIG. 2 includes a piezoelectric element having a thickness of 0.07 mm, for example.
A total of about 0.63 mm thick when laminated. The deformation preventing members 7, 7, ... Are made of the same material as the internal electrodes 6a, 6b, and are made of a conductive material having the same coefficient of thermal expansion as the internal electrodes 6a, 6b.

In this state, the external electrode 4 on the upper surface is
The outer electrodes 4a on the lower surface and the outer electrodes 4b on the lower surface are connected to different internal electrodes 6a and 6b, respectively, and they are insulated from the flat plate-shaped deformation preventing materials 7, 7 ,. That is,
One side electrode 8a continuous with the external electrode 4a on the upper surface is provided, and a part of this side electrode 8a is connected to the internal electrode 6b of the second layer, and the other side electrode continuous with the external electrode 4b on the lower surface. 8b is provided, and a part of the side electrode 8b is connected to the internal electrode 6a of the first layer. At this time, one side electrode 8a is
The other internal electrodes 6a and the deformation preventing material 7 are filled with an insulating material except the portion connected to the second layer internal electrode 6b.
Insulated from 7, ... Also, the other side electrode 8b
Are insulated from the other internal electrodes 6b and the deformation preventing members 7, 7, ... By filling an insulating material with the exception of the portions connected to the first layer internal electrodes 6a. As a result, the upper external electrode 4a is connected only to the second-layer internal electrode 6b, and the lower external electrode 4b is connected only to the first-layer internal electrode 6a. As a result, the piezoelectric elements 5a, 5 laminated in three layers
b and 5c are acoustically connected in series and electrically connected in parallel.

In this state, the whole of the piezoelectric elements 5a to 5c, which are laminated in a plurality of layers, have a structure in which the piezoelectric elements 5a to 5c are alternately polarized in the opposite direction. That is, a direct current high electric field is applied between the external electrode 4a on the upper surface and the external electrode 4b on the lower surface to perform polarization processing, and each layer of the piezoelectric elements 5a to 5c is polarized to impart piezoelectricity. This constitutes the ultrasonic transducer 1 according to the present invention. In this case, the piezoelectric elements 5a, 5 of each layer
The presence of the deformation preventing members 7, 7, ... Inserted in b, 5c reduces the occurrence of warpage when firing the entire piezoelectric elements 5a to 5c laminated in a plurality of layers, and increases the finished size and size. Can be accurate. Note that FIG. 2 shows a case where two acoustic matching layers 3 (3a, 3b) are provided.

In FIG. 1 and FIG. 2, the ultrasonic transducer 1 is formed by stacking three layers (5a, 5b, 5c) of piezoelectric elements, but the present invention is not limited to this, and two or more layers are provided. Any number of layers may be used as long as they are plural layers. In addition, the piezoelectric element 5 of each layer
Deformation preventing materials 7, 7, ... Inserted in a, 5b, 5c are also 2
The number is not limited to one, and may be any number. Further, the deformation preventing member 7 is made of a material having the same coefficient of thermal expansion as that of the internal electrodes 6a and 6b, but the present invention is not limited to this and may be made of a material having a substantially similar coefficient of thermal expansion. . Furthermore, the deformation preventing material 7 may be either a conductive material or an insulating material as long as it is made of a material having the same or similar coefficient of thermal expansion as the internal electrodes 6a and 6b. If the deformation preventing material 7 is an insulating material, it is not necessary to fill an insulating material between the inner side surfaces of the side electrodes 8a and 8b and the ends of the deformation preventing material 7 in the above description.

Next, a method of manufacturing an ultrasonic probe as a related invention of the ultrasonic probe will be described with reference to FIGS. 3 and 4. First, in FIG. 3, flat plate-shaped piezoelectric element pieces 9, 9, ... With a predetermined thickness are formed using a piezoelectric material. That is, PZT-based or PbTiO _{3 is} used as the piezoelectric material.
A piezoelectric ceramic powder of a system is used, an organic binder is added thereto, and a flat piezoelectric element piece 9 having a predetermined thickness is manufactured by a manufacturing method called a doctor blade method. At this time,
The thickness may be set so as to have a predetermined thickness, for example, 0.07 mm without polishing after firing in consideration of shrinkage in the subsequent pressure-bonding firing process.

Next, a conductive paste 10 to be the internal electrodes 6a and 6b shown in FIG. 2 is printed and applied on one surface of the piezoelectric element piece 9, and the plurality of piezoelectric element pieces 9 and 9 coated with the conductive paste 10 are applied. ,… Are laminated and thermocompression bonded. That is, a material such as silver palladium is used as the conductive paste 10, and this silver palladium or the like is applied to the entire surface of the piezoelectric element piece 9 by screen printing or the like. At this time, the above-mentioned conductive paste 1 is formed on the surface of the piezoelectric element piece 9 located at the top.
0 is not applied by printing. Then, after drying the piezoelectric element pieces 9, 9 on which the conductive paste 10 is applied by printing, for example, nine piezoelectric element pieces 9 are stacked and thermocompression-bonded in a mold.

Next, the thermocompression-bonded piezoelectric element piece 9,
The laminated body of 9, ... Is fired at a predetermined temperature. At this time, the organic binder in the piezoelectric element piece 9 is removed while gradually raising the temperature, and is further fired at 1150 ° C. for 5 hours, for example. Then, after this firing, the outer shape of the laminated body of the piezoelectric element pieces 9, 9, ... Is processed into desired dimensions.

Next, the external electrodes 4a and 4b are formed on the entire upper and lower surfaces of the piezoelectric element pieces 9, 9, ...
A conductive paste for baking the external electrode 4a on the upper surface.
And the external electrodes 4b on the lower surface are connected to the conductive pastes for the different internal electrodes 6a and 6b in the same number of plural layers, respectively, and are insulated from other conductive pastes. The external electrodes 4a and 4b may be formed of a conductive material by vapor deposition or plating. In this embodiment, as shown in FIG. 4, among the nine piezoelectric element pieces 9 stacked in FIG. 3, the third and sixth piezoelectric element pieces 9 counted from the bottom are coated on one surface. The conductive pastes are the internal electrodes 6b and 6a, respectively, and the conductive pastes applied to the other surface of the piezoelectric element piece 9 are all the deformation preventing materials 7.

Then, one side electrode 8a continuous with the outer electrode 4a on the upper surface is provided by baking or the like, a part of this side electrode 8a is connected to one inner electrode 6b, and the outer electrode 4b on the lower surface is connected. The other continuous side electrode 8b is provided by baking or the like, and a part of this side electrode 8b is connected to the other internal electrode 6a. At this time, the one side electrode 8a is filled with an insulating material other than the portion connected to the internal electrode 6b, and the other internal electrode 6a and the deformation preventing materials 7, 7 ,.
Is insulated from Further, the other side electrode 8b is filled with an insulating material except the portion connected to the internal electrode 6a, and the other internal electrode 6b and the deformation preventing members 7, 7 ,.
Is insulated from Thereby, the external electrode 4a on the upper surface
Is connected only to one internal electrode 6b, and the external electrode 4b on the lower surface is connected only to the other internal electrode 6a. As a result, the piezoelectric elements 5a, 5b, 5c laminated in three layers with the internal electrodes 6a, 6b as a boundary are acoustically in series,
It is electrically connected in parallel.

Thereafter, a high direct current electric field is applied between the external electrode 4a on the upper surface and the external electrode 4b on the lower surface to polarize the entire piezoelectric element pieces 9, 9, ... And the ultrasonic transducer 1 is configured. In this case, due to the presence of the deformation preventing materials 7, 7, ... Inserted in the piezoelectric elements 5a, 5b, 5c of the respective layers, warpage occurs when the entire piezoelectric elements 5a to 5c having a plurality of layers are fired. It is possible to reduce the size and finish the size and size with high accuracy. In the ultrasonic transducer 1 manufactured in this way, for example, the piezoelectric elements 5a, 5b, 5c laminated in three layers with the internal electrodes 6a, 6b as boundaries each have a thickness of 0.21 mm, and the total thickness is It is equivalent to an ultrasonic transducer with a 3-layer laminated structure with a thickness of 0.63 mm.

After that, as shown in FIG. 2, a backing material 2 is provided on the back side of the ultrasonic transducer 1 so as to prevent the ultrasonic waves emitted from the back side from returning to the transducer surface again. Acoustic matching layers 3a and 3b for matching the acoustic impedance of the ultrasonic transducer 1 and the acoustic impedance of the living body are provided on the front side of the transducer 1. Thereby, the ultrasonic probe of the present invention is manufactured.

In the process of manufacturing the ultrasonic probe, when the ultrasonic vibrator 1 is manufactured as shown in FIG. 4, the ultrasonic vibrator 1 is formed with a predetermined pitch width p, p ,. It may be cut into strips to form an array. In this case, an electronic scanning type ultrasonic probe in which a large number of transducer elements are arranged in an array can be manufactured.

5 and 6 are explanatory views showing another example of the method for manufacturing the ultrasonic probe. The manufacturing method according to this example is
Although it is basically the same as the manufacturing method shown in FIGS. 3 and 4, the piezoelectric element piece 9 is formed into a flat plate-like piezoelectric element piece 9 with a predetermined thickness by using a piezoelectric material. When the conductive paste 10 to be the internal electrodes 6a and 6b shown in FIG. 2 is printed and applied on one surface of the above, the insulating portions 11 on which the conductive paste 10 is not applied are formed on both side portions thereof.
At this time, the internal electrodes 6a and 6b shown in FIG.
When printing and applying the conductive paste 10 to be used, the insulating portion 11 is not formed on the side connected to the external electrodes 8a and 8b.

In such a state, as shown in FIG.
.. are laminated, the internal electrodes 6a, 6b and the deformation preventing members 7, 7, ... Are formed, the external electrodes 4a, 4b are formed on the upper and lower surfaces, and the side electrodes 8a, 8a are formed on both side surfaces. 8b is formed. Then, the side electrode 8a continuous with the external electrode 4a on the upper surface is connected to one internal electrode 6b,
The side electrode 8b continuous with the external electrode 4b on the lower surface is connected to the other internal electrode 6a. By manufacturing in this manner, it is not necessary to fill an insulator between the inner side surfaces of the side electrodes 8a and 8b and the side end portions of the nine-layer piezoelectric element piece in FIG. 4, and the manufacturing process is simplified. Can be converted.

[0032]

Since the ultrasonic probe according to the present invention is constructed as described above, the ultrasonic transducer is formed by laminating a plurality of piezoelectric elements formed in a plate shape having a predetermined thickness. External electrodes are formed on the upper surface and the lower surface of the whole of the laminated piezoelectric element, and a flat plate-shaped internal electrode is formed at the boundary of each layer, and one or a plurality of layers are formed within the thickness of each layer of the piezoelectric element. Insert the flat plate-shaped deformation preventive material at equal intervals, connect the external electrodes on the upper surface and the external electrodes on the lower surface to different internal electrodes every other layer, and define the flat plate-shaped deformation preventive material in each layer. Insulation is performed, and in this state, the entire piezoelectric element having the plurality of laminated layers is polarized in the opposite direction alternately in the laminating direction, so that the thickness per layer laminated by the insertion of the deformation preventing material is increased. Can be made substantially thinner, and The presence of form-preventing member, to reduce the occurrence of warpage during the firing of the whole of the plurality of layers stacked piezoelectric element, the dimensions size of the finished can be a high precision. Therefore, according to the ultrasonic probe of the present invention,
A vibration mode with a single resonance frequency can be obtained, and an ultrasonic image with good image quality can be obtained as an ultrasonic diagnostic apparatus.

In particular, when the deformation preventing material inserted in the thickness of each layer of the piezoelectric element is made of a material having the same or similar coefficient of thermal expansion as the internal electrode, the piezoelectric element having a plurality of layers is laminated. It is possible to further reduce the occurrence of warpage when firing the whole and to further improve the dimensional size of the finished product.

Further, according to the method of manufacturing an ultrasonic probe according to the present invention, the occurrence of warpage during firing of the entire piezoelectric element having a plurality of laminated layers is reduced, and the finished size and size are highly accurate. The sonic oscillator can be easily manufactured.

[Brief description of drawings]

FIG. 1 is a partial sectional perspective view showing an embodiment of an ultrasonic probe according to the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a perspective explanatory view showing a part of the steps of the method for manufacturing the ultrasonic probe.

FIG. 4 is a perspective explanatory view showing an ultrasonic transducer manufactured by the method for manufacturing an ultrasonic probe.

FIG. 5 is a perspective explanatory view showing a part of steps of a method for manufacturing an ultrasonic probe according to another example.

FIG. 6 is a cross-sectional explanatory view showing an ultrasonic transducer manufactured by the method for manufacturing an ultrasonic probe.

FIG. 7 is a partial cross-sectional perspective view showing a conventional ultrasonic probe.

FIG. 8 is a partial cross-sectional perspective view showing an ultrasonic probe having a conventional ultrasonic transducer having a multi-layer laminated structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Ultrasonic vibrator 2 ... Backing material 3,3a, 3b ... Acoustic matching layer 4a, 4b ... External electrode 5 ... Transducer element 5a, 5b, 5c ... Piezoelectric element 6a, 6b ... Internal electrode 7 ... Deformation preventing material 8a , 8b ... Side electrode 9 ... Piezoelectric element piece 10 ... Conductive paste 11 ... Insulating portion

Claims (5)

[Claims] 1. An ultrasonic transducer that emits ultrasonic waves and receives reflected waves thereof, and an ultrasonic wave that is provided on the back surface of the ultrasonic transducer and that returns from the back surface does not return to the transducer surface. An ultrasonic probe comprising a backing material and an acoustic matching layer provided on the front surface of the ultrasonic transducer for matching acoustic impedance of the ultrasonic transducer and acoustic impedance of a living body, The acoustic wave vibrator is formed by laminating a plurality of layers of piezoelectric elements formed in a plate shape having a predetermined thickness, forming external electrodes on the entire upper surface and the lower surface of the laminated piezoelectric elements, and at the boundaries between the layers. Form a flat plate-shaped internal electrode, and insert one or a plurality of flat plate-shaped deformation preventing materials into the thickness of each layer of the piezoelectric element at equal intervals to form an external electrode on the upper surface and an external electrode on the lower surface. Every other layer is different In this state, the piezoelectric element is laminated in such a manner that it is insulated from the flat plate-shaped deformation preventing material in each layer, and in this state, the entire piezoelectric elements laminated in the above plural layers are alternately polarized in the laminating direction in opposite directions. An ultrasonic probe characterized in that. 2. The plate-shaped deformation preventing material inserted into the thickness of each layer of the piezoelectric element is made of a material having the same or similar coefficient of thermal expansion as the plate-shaped internal electrode. The ultrasonic probe according to claim 1. 3. The ultrasonic probe according to claim 2, wherein the plate-shaped deformation preventing material inserted in the thickness of each layer of the piezoelectric element is made of a conductive material or an insulating material. . 4. A flat piezoelectric element piece having a predetermined thickness is formed using a piezoelectric material, a conductive paste for internal electrodes is printed and applied on one surface of the piezoelectric element piece, and the conductive paste is printed and applied. After laminating a plurality of piezoelectric element pieces, thermocompression-bonding them, firing at a predetermined temperature, baking conductive paste for external electrodes on the entire upper and lower surfaces of the laminated piezoelectric element pieces, The electrodes and the external electrodes on the lower surface are connected to conductive pastes for different internal electrodes in the same number of layers, respectively, and insulated from other conductive pastes, and then between the external electrodes on the upper surface and the external electrodes on the lower surface. A high direct current electric field is applied to the whole of the piezoelectric element pieces to form an ultrasonic transducer by polarization, and the ultrasonic wave emitted from the rear surface of the ultrasonic transducer vibrates again. Back to the face It is manufactured by providing a backing material to prevent this and an acoustic matching layer for matching the acoustic impedance of the ultrasonic transducer and the acoustic impedance of the living body on the front side of the ultrasonic transducer. And a method for manufacturing an ultrasonic probe. 5. The ultrasonic transducer according to claim 1, wherein the piezoelectric element pieces laminated in a plurality of layers are entirely polarized and then cut into strips at a predetermined pitch to form an array. Item 5. A method for manufacturing an ultrasonic probe according to item 4.