JP4560417B2 - Ultrasonic transducer, manufacturing method thereof, and ultrasonic probe - Google Patents

Description

  The present invention relates to a backing material, an ultrasonic transducer having a piezoelectric element disposed on the surface of the backing material, a manufacturing method thereof, and an ultrasonic probe.

  In recent years, medical diagnosis using ultrasonic images has been put into practical use in the medical field. Ultrasound images are obtained by irradiating the required part of the living body from the ultrasonic probe and electrically detecting the echo signal from the living body with an ultrasonic observation device connected to the ultrasonic probe via the connector. can get. It is also possible to obtain an ultrasonic tomographic image by irradiating while scanning with ultrasonic waves. Multiple ultrasonic transducers that transmit and receive ultrasonic waves are arranged, and the ultrasonic transducers to be driven are selectively selected with an electronic switch or the like. There is also known an ultrasonic probe of an electronic scan scanning method that switches to the above.

The ultrasonic transducer includes a backing material, a piezoelectric element, an electrode, and an acoustic matching layer, and is built into the distal end of the insertion portion of the ultrasonic probe (see Patent Document 1). The backing material is provided to absorb ultrasonic waves emitted from the piezoelectric element in a direction opposite to that of the living body and suppress excessive vibration of the piezoelectric element.
JP-A-8-172695

  By the way, in order to reduce the burden on the patient when the ultrasonic probe is inserted into the living body, an ultrasonic probe for an inspection object having a smaller diameter (such as a blood vessel or a bronchus) or a necessary part of the living body is used. In the production of a so-called ultrasonic endoscope in which an image pickup device for acquiring an optical image is incorporated together with an ultrasonic transducer, the diameter of the insertion portion of the ultrasonic probe is reduced, and further, it is built in the distal end of the insertion portion. The most important issue is miniaturization of ultrasonic transducers.

  The size of the ultrasonic transducer depends on the size of the backing material, piezoelectric element, electrode, and acoustic matching layer that are components of the ultrasonic transducer. Among these components, the size of the piezoelectric element and the acoustic matching layer is large. With respect to this, it is uniquely determined by the frequency of the oscillating ultrasonic wave. Therefore, in order to realize the miniaturization of the ultrasonic transducer, it is effective to reduce the size, particularly the thickness, of the backing material. However, if the thickness of the backing material is simply reduced, there is a risk that noise will be added to the echo signal due to the ultrasonic waves reflected by the back surface of the backing material.

  The present invention has been made in view of the above problems, and an ultrasonic transducer capable of preventing noise from being added to an echo signal and contributing to a reduction in the diameter of an insertion portion of an ultrasonic probe, and a method for manufacturing the same The purpose is to provide.

  It is another object of the present invention to provide an ultrasonic probe that can realize a reduction in the diameter of the insertion portion.

  In order to achieve the above object, an invention according to claim 1 is an ultrasonic transducer having a backing material and a piezoelectric element disposed on a surface of the backing material, wherein the surface of the backing material is formed on the back surface of the backing material. A groove for preventing ultrasonic waves from reflecting in the direction or the direction of a piezoelectric element that receives an echo signal from a living body is formed.

  In addition, it is preferable to add an ultrasonic scattering material to at least a portion of the backing material where the groove is formed. Moreover, it is preferable to form the groove using any one of sandblasting, dicing, embossing, or mold forming. Furthermore, it is preferable that the backing material has a curvature.

  The invention according to claim 5 is a method of manufacturing an ultrasonic transducer having a backing material and a piezoelectric element disposed on the surface of the backing material, and the direction of the surface or the living body on the back surface of the backing material. And a step of forming a groove for preventing the ultrasonic wave from reflecting in the direction of the piezoelectric element that receives the echo signal from the head.

  In addition, it is preferable to include a step of adding an ultrasonic scattering material to at least a portion of the backing material where the groove is formed. Moreover, it is preferable to form the groove using any one of sandblasting, dicing, embossing, or mold forming.

  According to an eighth aspect of the present invention, in the ultrasonic probe, the ultrasonic transducer according to any one of the first to fourth aspects is incorporated. In addition, it is preferably used for in-vivo diagnosis that is inserted into a body cavity. Moreover, it is preferable that the image pick-up element for acquiring the optical image of the required part of a biological body is incorporated.

  According to the ultrasonic transducer and the manufacturing method thereof of the present invention, the ultrasonic wave is reflected on the back surface of the backing material in the direction of the surface of the backing material or in the direction of the piezoelectric element that receives an echo signal from a living body. Since the groove to be prevented is formed, it is possible to prevent noise from being added to the echo signal. In addition, the thickness of the backing material can be reduced, which can contribute to reducing the diameter of the insertion portion of the ultrasonic probe.

  In addition, according to the ultrasonic probe of the present invention, since the ultrasonic transducer according to any one of claims 1 to 4 is built in, it is possible to reduce the diameter of the insertion portion.

  In FIG. 1, an ultrasonic diagnostic apparatus 2 includes an ultrasonic endoscope 10, an ultrasonic observation device 11, a light source device (not shown), and the like. The ultrasonic endoscope 10 is connected to an insertion unit 12 inserted into a living body, an operation unit 13 connected to a proximal end portion of the insertion unit 12, an ultrasonic observation device 11, and a light source device. A cord 14 and a universal cord 15 are provided. The operation unit 13 is provided with a forceps port 16 through which a treatment tool is inserted. In addition, the distal end 12a of the insertion portion 12 incorporates an ultrasonic transducer 17 and an imaging element 18 (both see FIG. 2) constituting an imaging device for in-vivo imaging.

  The light source device includes a light source that supplies illumination light to the ultrasonic endoscope 10 through the universal cord 15. Illumination light from the light source is applied to a required part of the living body through an illumination window provided at the tip 12a. In addition, the distal end 12a is provided with an observation window in which an objective optical system for taking image light of an observation site in the living body into the image sensor 18 is incorporated. The optical image acquired by the image sensor 18 is displayed on an endoscope monitor (not shown) dedicated to optical image display.

  In the ultrasonic diagnostic apparatus 2, an image inside the living body is acquired by the image sensor 18, and a necessary part of the living body searched by observing this image is irradiated while scanning the ultrasonic wave from the ultrasonic transducer 17. Thus, an ultrasonic tomographic image can be obtained. An ultrasonic tomographic image obtained by the ultrasonic endoscope 10 is displayed on the monitor 19 of the ultrasonic observation device 11.

  In FIG. 2, the ultrasonic transducer 17 has a plurality of (for example, 192) piezoelectric elements 20 sandwiched between electrodes (not shown) and arranged on the surface 21a (see FIG. 3) of the backing material 21. An electronic scanning method is adopted. Although not shown, an acoustic matching layer and an acoustic lens are disposed on the piezoelectric element 20.

  The entire operation of the ultrasonic observation device 11 is controlled by the CPU 22. An operation unit 23 having an input device such as a keyboard and a mouse is connected to the CPU 22. In response to the operation signal from the operation unit 23, the CPU 22 operates each unit of the ultrasonic observation device 11.

  The transmission / reception circuit 24 transmits the drive signal (voltage pulse for exciting the ultrasonic transducer 17) to the ultrasonic transducer 17 and the echo signal from the living body obtained by the ultrasonic transducer 17 under the control of the CPU 22. The signal switching timing and the ultrasonic transducer 17 to be driven are selected.

  The echo signal received by the transmission / reception circuit 24 is input to an A / D converter (A / D) 25. The A / D 25 digitally converts the echo signal input from the transmission / reception circuit 24 and transmits it to the buffer memory 26. The buffer memory 26 temporarily stores the echo signal digitally converted by the A / D 25.

  A digital scan converter (DSC) 27 reads an echo signal from the buffer memory 26 under the control of the CPU 22, converts it into a television signal scanning system (NTSC system), and transmits it to the image memory 28. To do. The D / A converter (D / A) 29 reads the signal converted into the NTSC system by the DSC 27 from the image memory 28, and converts it again into an analog signal. The monitor 19 displays the analog signal converted by the D / A 29 as an ultrasonic tomographic image.

As shown in FIG. 3, when the ultrasonic transducer 17 scans the living body with ultrasonic waves, several to several tens of the plurality of piezoelectric elements 20 within the range of the angle θ ₁ are formed as one block. Driven simultaneously. When receiving an echo signal from a living body, several to several tens of blocks within the range of the angle θ ₁ are simultaneously driven. Further, at each transmission / reception of the drive signal and the echo signal, at least one piezoelectric element 20 to be driven is shifted clockwise as shown in FIG. 3, and the piezoelectric element 20 for transmitting / receiving the drive signal and the echo signal is selectively used. Can be switched to.

A groove 30 is formed on the back surface 21 b of the backing material 21. One groove 30 is provided for each piezoelectric element 20, has a V shape with the center of the piezoelectric element 20 as the axis of symmetry, and has the same size as the width L ₁ of the piezoelectric element 20. .

  In forming the groove 30, any one of sand blasting, dicing, embossing, or mold forming is used. Specifically, when a relatively soft material is selected for the backing material 21, the grooves 30 are directly formed in the backing material 21 by sandblasting, dicing, or embossing. When a plastic that can be melt-molded is used for the backing material 21, a groove corresponding to the groove 30 is formed in the mold by sandblasting or dicing, and the molten plastic is poured into the mold and solidified.

The shape of the groove 30 is determined so as to prevent the ultrasonic wave from being reflected in the direction of the surface 21 a of the backing material 21 or the direction of the piezoelectric element 20 that receives an echo signal from a living body. That is, the inner radius R ₁ of the backing material 21, the outer radius R _2, if the angle of the groove 30 and the theta _2, preferably theta ₂ is to satisfy the condition of the following expression, a groove 30 is formed.
θ ₂ <arccos {(R ₁ −R ₂ cos θ ₁ ) / (R ₁ ² + R ₂ ² −2R ₁ R ₂ cos θ ₁ ) ^1/2 }

Here, for example, when θ ₁ is 35 ° and the inner radius R ₁ of the backing material 21 is 3.25 mm, the thickness of the backing material 21 is conventionally required to be about 1.25 mm, but θ ₂ < If the groove 30 is formed at 89.64 °, for example, θ ₂ = 85 °, the thickness of the backing material 21 can be reduced to 0.7 mm. In addition, the shape of the groove | channel 30 by said Formula is an example, and does not specifically limit this invention.

  Next, an operation procedure of the ultrasonic diagnostic apparatus 2 having the above configuration will be described. First, the insertion part 12 of the ultrasonic endoscope 10 is inserted into a living body, and a required part in the living body is searched while an image obtained by the imaging element 18 is observed. When the distal end 12a of the insertion portion 12 of the ultrasonic endoscope 10 reaches a required portion in the living body and the operation portion 23 is operated to release the freeze, the transmission / reception circuit 24 controls the CPU 22 under the control of the CPU 22. A drive signal is issued to the ultrasonic transducer 17. The ultrasonic transducer 17 is excited by this drive signal, and thereby ultrasonic waves are irradiated to a required part of the living body.

  After transmission of the drive signal, transmission / reception of the transmission / reception circuit 24 is switched under the control of the CPU 22, and an echo signal from the living body acquired by the ultrasonic transducer 17 is input to the transmission / reception circuit 24. At this time, the groove 30 formed on the back surface 21b of the backing material 21 prevents noise from being added to the echo signal.

  The echo signal input to the transmission / reception circuit 24 is digitally converted by the A / D 25 and temporarily stored in the buffer memory 26. The digitally converted echo signal stored in the buffer memory 26 is converted into the NTSC system by the DSC 27 and transmitted to the image memory 28. Then, it is converted again into an analog signal by the D / A 29 and displayed on the monitor 19 as an ultrasonic tomographic image.

  As described above in detail, the ultrasonic wave is prevented from being reflected on the back surface 21b of the backing material 21 in the direction of the front surface 21a of the backing material 21 or the direction of the piezoelectric element 20 that receives an echo signal from a living body. Since the groove 30 is formed, it is possible to prevent noise from being added to the echo signal, and to contribute to reducing the diameter of the insertion portion 12a of the ultrasonic endoscope 10.

  In addition, miniaturization of the ultrasonic transducer is most important, such as the ultrasonic endoscope 10 as in the above embodiment, the ultrasonic probe for a smaller diameter inspection target (blood vessel, bronchi, etc.), and the capsule endoscope. If the present invention is applied to a problem, a particularly excellent effect is obtained.

  In addition, when a material having a curvature is used for the backing material 21 as in the radial electronic scanning ultrasonic probe 2 of the above embodiment, an echo signal from a living body can be obtained without increasing the angle of the groove 30. The ultrasonic wave can be prevented from being reflected in the direction of the piezoelectric element 20 that receives the noise, and noise can be prevented from being more easily applied to the echo signal.

  In the above embodiment, one groove 30 is provided for each piezoelectric element 20, but a plurality of grooves 30 (three in this case) are provided for each piezoelectric element 20, as shown in FIG. Also good. Further, as shown in FIG. 5, an ultrasonic scattering material 40 made of alumina, tungsten, PZT (lead zirconate titanate) powder or the like is added to at least a portion of the backing material 21 where the groove 30 is formed. Good. In this way, it is possible to reduce the ultrasonic wave itself reflected on the back surface 21b of the backing material 21, and to further reduce the thickness of the backing material 21.

  Furthermore, as shown in FIG. 6, the shape of the groove 30 may be devised so that an ultrasonic wave is captured in the groove 30 and is not reflected outside the groove 30. Moreover, as shown in FIG. 7, you may employ | adopt the structure used for the wall surface of an anechoic chamber which arrange | positioned the groove | channel 30 by the vertical and horizontal direction alternately.

In the above embodiment, the shape of the groove 30 is determined with reference to the inner radius R ₁ and the outer radius R ₂ of the backing material 21. In addition, the transmission / reception timings of the drive signal and the echo signal are determined. In consideration of the shape, the shape of the groove 30 may be determined.

  The number of piezoelectric elements 20 constituting the ultrasonic transducer 17, the number of piezoelectric elements 20 that are driven at a time, the position and number of piezoelectric elements 20 that receive an echo signal, and the like are the values given in the above embodiment. It is not limited, It can change suitably according to the specification of ultrasonic diagnostic equipment 2.

  In the above embodiment, the radial electronic scanning type ultrasonic endoscope 10 has been described as an example, but the present invention is also applied to other ultrasonic probes such as a convex electronic scanning type and a linear electronic scanning type. Is possible. Further, the present invention is not limited to the ultrasonic probe for in-vivo diagnosis but may be applied to the ultrasonic probe for extra-corporeal diagnosis.

It is the schematic which shows the structure of an ultrasound diagnosing device. It is a block diagram which shows the internal structure of an ultrasonic diagnosing device. It is an enlarged view of an ultrasonic transducer. It is an enlarged view which shows another embodiment of an ultrasonic transducer. It is an enlarged view which shows another embodiment of an ultrasonic transducer. It is an enlarged view which shows another embodiment of an ultrasonic transducer. It is an enlarged view which shows another embodiment of an ultrasonic transducer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 Ultrasonic diagnostic apparatus 10 Ultrasound endoscope 11 Ultrasonic observation device 12 Insertion part 12a Tip 17 Ultrasonic transducer 18 Imaging element 20 Piezoelectric element 21 Backing material 21a, 21b Surface, back surface 22 CPU
30 groove 40 ultrasonic scattering material

Claims (9)

Ultrasonic backing material shape having a curvature, and have a plurality of piezoelectric elements disposed on the surface of the backing material, transmitting and receiving ultrasonic waves and echo signals simultaneously a plurality as one block of the plurality of piezoelectric elements A transducer,
Forming a V-shaped groove on the back surface of the backing material to prevent ultrasonic waves from reflecting in the direction of the surface or in the direction of a piezoelectric element that receives an echo signal from a living body ;
The angle θ ₂ of the groove is the angle of the piezoelectric element for one block that simultaneously transmits and receives ultrasonic waves and echo signals, as seen from the inner radius of the curved surface of the backing material R ₁ , the outer radius of R ₂ , and the curved material center of the backing material. when the range was set to θ _1,
θ ₂ <arccos {(R ₁ −R ₂ cos θ ₁ ) / (R ₁ ² + R ₂ ² −2R ₁ R ₂ cos θ ₁ ) ^1/2 }
An ultrasonic transducer characterized by satisfying .   The ultrasonic transducer according to claim 1, wherein an ultrasonic scattering material is added to at least a portion of the backing material where the groove is formed.   The ultrasonic transducer according to claim 1 or 2, wherein the groove is formed by using any one of sandblasting, dicing, embossing, and mold forming. Ultrasonic backing material shape having a curvature, and have a plurality of piezoelectric elements disposed on the surface of the backing material, transmitting and receiving ultrasonic waves and echo signals simultaneously a plurality as one block of the plurality of piezoelectric elements A transducer manufacturing method comprising:
Forming a V-shaped groove on the back surface of the backing material to prevent ultrasonic waves from reflecting in the direction of the surface or in the direction of a piezoelectric element that receives an echo signal from a living body ,
The inner radius R ₁ of the curved surface of the backing _material, the outer radius R _2, viewed from the curved center of the backing material, when the angular range of one block of the piezoelectric element for transmitting and receiving ultrasonic waves and echo signal is a theta ₁ simultaneously, The angle θ ₂ of the groove is
θ ₂ <arccos {(R ₁ −R ₂ cos θ ₁ ) / (R ₁ ² + R ₂ ² −2R ₁ R ₂ cos θ ₁ ) ^1/2 }
A method for manufacturing an ultrasonic transducer, wherein the ultrasonic transducer is formed so as to satisfy the above . 5. The method of manufacturing an ultrasonic transducer according to claim 4 , further comprising a step of adding an ultrasonic scattering material to at least a portion of the backing material where the groove is formed. Sandblasting, dicing, embossing, or by using any of the molded, manufacturing method of an ultrasonic transducer according to claim 4 or 5, characterized in that the formation of the groove. An ultrasonic probe comprising the ultrasonic transducer according to any one of claims 1 to 3 . The ultrasonic probe according to claim 7 , wherein the ultrasonic probe is used for intracorporeal diagnosis that is inserted into a body cavity and used. The ultrasonic probe according to claim 7 or 8 , wherein an image pickup device for acquiring an optical image of a required part of a living body is incorporated.

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