JPS61184100A - Ultrasonic wave probe - Google Patents

Abstract

PURPOSE:To eliminate acoustic crosstalk and to prevent deterioration in azimuth resolution characteristic of an ultrasonic wave picture by packing a packing agent with major component such as rubber mixed with powder such as metallic powder and micro baloon to the gap of plural piezoelectric vibrators. CONSTITUTION:The piezoelectric vibrator 1 is split into plural number, and a back load agent 2 is provided to one face by lowing or bonding. The packing agent is packed to the gap of the vibrators 1, two layer of acoustic matching layers 4, 5 are provided on the other face of the vibrators 1, and an acoustic lens 6 is provided on it. As the packing agent 3, rubber member mixed with metallic powder or insulation powder and micro baloon. Thus, the acoustic impedance of the packing agent 3 is low and the sound wave attenuation coefficient is high, then the propagation of the sound wave to adjacent vibrators is prevented due to the difference in the acoustic impedance between the adjacent vibrators 1 and the crosstalk is reduced and the ultrasonic wave picture having high azimuth resolution is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an ultrasound probe used in a medical ultrasound diagnostic apparatus.

2. Description of the Related Art Recently, ultrasonic probes have been widely used in the field of ultrasonic diagnostic equipment and the like. As a conventional ultrasonic probe, the configuration described in, for example, Japanese Patent Laid-Open No. 55-35654 is known. Hereinafter, a conventional ultrasonic probe will be explained with reference to FIG. Back load material 102
A plurality of piezoelectric vibrators 1o1 divided into elongated rectangles are arranged on the surface of the piezoelectric vibrator 101, and the piezoelectric vibrator 101 is equipped with an electrode (not shown), which is connected to an electric terminal (not shown).
is connected to the drive circuit via. An acoustic matching layer 1o3 made of a glass material and having a thickness of 1/4 wavelength is adhered to the surface of the piezoelectric vibrator 101 divided into a plurality of pieces using an epoxy adhesive. During this bonding, an epoxy adhesive 104 is flowed into the gap formed by the side surface of each piezoelectric vibrator 101 and the surface of the back load material 102, and the acoustic matching layer is placed on the adhesive 104. 10
Glue 3.

In this way, an acoustic matching layer 10 is placed between each piezoelectric vibrator 101.
The leakage of sound waves (acoustic crosstalk) is prevented by filling an epoxy resin adhesive 104 that is smaller than the acoustic impedance value of No. 3 and creating an acoustically discontinuous coupling between each piezoelectric vibrator 1o1. The aim is to prevent this and improve the lateral resolution of ultrasound images.

Ideally, in order to almost completely prevent acoustic crosstalk, there should be a very large difference between the acoustic impedance of each piezoelectric vibrator 101 and the acoustic impedance of the gap. That is, the ideal configuration is such that air with extremely low acoustic impedance is present in the gap between the piezoelectric vibrators 101.

Because it is difficult, it is filled with some material.

Therefore, it is difficult to almost completely prevent acoustic crosstalk. Therefore, in order to increase the difference in the acoustic impedance of the material filled in the gap between each piezoelectric vibrator 101 with respect to the acoustic impedance of each piezoelectric vibrator 101, this material has an acoustic impedance of about 3 x 10 y/d -
Currently, an epoxy adhesive with a certain small size S is used to reduce acoustic cross-reflection.

Another method for reducing acoustic crosstalk is to fill the gap between each piezoelectric vibrator 1o1 with a material having an extremely large acoustic wave attenuation coefficient, and use this filling material to reduce acoustic crosstalk to the adjacent piezoelectric vibrator 101. It attenuates the
It is conceivable that the adjacent piezoelectric vibrators 101 be subjected to K so that there is no leakage.

In order to prevent acoustic crosstalk in this way, the desirable characteristics of the material filled in the gap between the piezoelectric vibrators 1o1 are as follows:
) The difference from the acoustic impedance of the piezoelectric vibrator is large, that is, the acoustic impedance value is small, and (2) the acoustic wave attenuation coefficient is large.

Problems to be Solved by the Invention However, when an epoxy adhesive is used as a material to fill the gaps in the piezoelectric vibrator 101, the piezoelectric vibrator 1 has a plurality of acoustic matching layers 103 made of glass or the like arranged.
Although there is an advantage in the manufacturing process that the epoxy adhesive can be filled into the gap between the piezoelectric vibrators 101 and the piezoelectric vibrators 101 at the same time, it is not sufficient to prevent acoustic crosstalk between the piezoelectric vibrators 101. be. That is, the acoustic impedance of the piezoelectric vibrator 101 (generally, in the case of a piezoelectric ceramic vibrator such as PZT, 20×105 to 36×
1051/ad-S. ) is about one digit, but the transmission coefficient related to acoustic losstalk from the piezoelectric vibrator 101 to the epoxy adhesive is approximately 15 to 26%. Moreover, the sound wave attenuation coefficient of epoxy adhesive is 3.0.
Since M) l z is small at around 1 dB/m, the transmitted sound waves (crosstalk) can hardly be attenuated and propagate to the adjacent piezoelectric vibrator 101 . Therefore, there are problems in that it becomes impossible to form a predetermined ultrasound beam beam, and that characteristics such as azimuth resolution required for the image quality of ultrasound images deteriorate.

Therefore, in order to solve the above-mentioned problems, the present invention aims to provide an ultrasound probe that eliminates acoustic crosstalk and prevents deterioration of characteristics such as lateral resolution of ultrasound images. It is something.

Means for solving the problems and technical means of the present invention for solving the above problems include a piezoelectric vibrator, a back load material provided on one side of the piezoelectric vibrator, and a piezoelectric vibrator. At least the piezoelectric vibrator is divided into a plurality of pieces, and a base material such as a rubber material or a synthetic resin is coated with metal powder or It is filled with a filler containing powder such as insulating powder and microballoons.

According to the above-described structure, the present invention allows the material to be filled into the gap between the piezoelectric vibrators to be arbitrarily selected within a range of acoustic impedance that is smaller than that of conventional epoxy adhesives, and moreover, it has a lower acoustic impedance than conventional epoxy adhesives. The coefficient is also as large as 35 times or more. Therefore, the difference in acoustic impedance between the piezoelectric vibrator and the filling material can be increased, and acoustic crosstalk between adjacent piezoelectric vibrators can be reduced. Furthermore, even if there is a small amount of acoustic crosstalk, the filling material has a large sound wave attenuation coefficient and can be attenuated by this filling material.

EXAMPLE Hereinafter, an example of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view of the ultrasonic probe of the present invention. A piezoelectric vibrator 1 has electrodes (not shown) on both sides, and an electric terminal is taken out from one electrode. A back load material 2 is provided on one side of the piezoelectric vibrator 1 by means of pouring or bonding. The piezoelectric vibrator 1 is divided into a plurality of pieces by machining or the like. A filler 3 is filled in the gap between each piezoelectric vibrator 1, and two acoustic matching layers 4 and 6 are provided on the other side of the piezoelectric vibrator 1 by pouring or bonding. Note that an acoustic lens 6 is provided on the acoustic matching layer 5 if necessary.

The filler 3 to be filled into the gap between the piezoelectric vibrators 10 is a mixture of two types of rubber material: powder such as metal powder or insulating powder, and microballoons. For example, if silicone rubber is used as the rubber material and filler material 3 is made by mixing tungsten powder and plastic microballoons at a weight ratio of 200% and 1.5%, respectively, with respect to the silicone rubber base material, the acoustic Impedance is 1606X10551/d
-S, the sound wave attenuation coefficient is approximately 40 dB/m at 3 MHz.

As described above, due to the difference in acoustic impedance between adjacent piezoelectric vibrators 1, propagation of sound waves to the adjacent piezoelectric vibrators 1 can be prevented, and cross-storage can be reduced. As the filler 3, a material with an acoustic impedance of 1.06X1d and ff1-8 was used, while as the piezoelectric vibrator 1, a material with an acoustic impedance of 20X1 was used.
By using PZT ceramic material with a size of 0 to 35 x 10 mm, the acoustic transmission coefficient between the piezoelectric vibrator 1 and the filler 3 is approximately 6 to 10%, which makes it easier to use conventional epoxy adhesives. When used as a filler, it is 15 to 26%, so it is clear that acoustic crosstalk can be significantly reduced according to this example.

Furthermore, the sound wave attenuation coefficient of the filler 3 of the above embodiment is 40 dB/w at 3 MHz, which is about 40 times larger than the sound wave attenuation coefficient of 1 dB/a of the conventional filler using epoxy adhesive. , the transmission coefficient of 6 to 10%, which results in acoustic crosstalk, can be almost completely attenuated by the filler 3. Therefore, by using the filler 3 of the embodiment described above, it is possible to substantially eliminate acoustic crosstalk between adjacent piezoelectric vibrators 1, and it is possible to obtain an ultrasonic image with high lateral resolution.

In addition, when using silicone rubber as a base material and mixing 100% tungsten powder in a weight ratio to silicone rubber and 2% plastic micro balloons in the same weight ratio, the acoustic impedance and sound attenuation coefficient are 0.7 x 1, respectively.
0 L4 and 50 dB/wm (3 MHz), and when tungsten powder and plastic micro balloons are mixed at a weight ratio of 400 cm and 0.8% to silicone rubber, the acoustic impedance and sound wave attenuation coefficient are 2, respectively. ×1o5P/d-E3,35dB/
It becomes the value of a. By varying the amounts of tungsten powder and plastic microballoons mixed into silicone rubber in this way, a sound wave attenuation coefficient of 35 to 5 degrees can be achieved.
dB/+w, acoustic impedance 0.7×105~2
The filler 3 can be obtained in the range of x105 g/d-3, and in the present invention, it may be selected as appropriate within this range.

Furthermore, in the above embodiment, the case where silicone rubber was used as the base material of the filler 3 was described, but in addition to this, urethane rubber, butyl rubber, neoprene rubber, or synthetic resins such as epoxy resin, urethane resin, etc. may be used. What they can do is clear from their characteristics.

Furthermore, in the above embodiment, a case was described in which tungsten powder was used as a powder such as metal powder or insulating powder.
In addition, it is clear from their properties that tantalum powder, ferrite powder, zinc powder, silicon carbide powder, tungsten carbide powder, iron powder, etc. can be used. Of course, it is also clear that two or more of these metal powders or insulating powders can be used.

Further, the acoustic matching layer 4 on the piezoelectric vibrator 1 side in the embodiment described above
It is also possible to divide the piezoelectric vibrator together with the piezoelectric vibrator into a plurality of pieces, and fill the gaps therewith with the filler 3 in the same manner as the piezoelectric vibrator 1.

Furthermore, in the embodiment described above, a so-called array type ultrasonic probe in which piezoelectric vibrators 1 are arranged in a linear manner is described.
The present invention can be applied to various other types, such as arranging the piezoelectric vibrators in an arc shape, two-dimensionally, or in a ring shape.

Effects of the Invention As is clear from the above explanation, the present invention includes a piezoelectric vibrator, a back load material provided on one side of the piezoelectric vibrator, and a back load material provided on the other side of the piezoelectric vibrator. At least the piezoelectric vibrator is divided into a plurality of pieces, and a powder such as metal powder or insulating powder is applied to a base material such as rubber material or synthetic resin in the gap between the piezoelectric vibrators. It is filled with a filling material mixed with microballoons. Since the acoustic impedance of the filler is small in this way, the difference from the acoustic impedance of the piezoelectric vibrator is large, and the sound wave attenuation coefficient is also large, so the acoustic loss talk between the piezoelectric vibrators divided into multiple pieces is reduced. It can be made extremely small. Therefore, it becomes possible to form a predetermined ultrasonic beam pattern, improve the lateral resolution characteristics required for ultrasonic image quality, and obtain an ultrasonic probe with high resolution characteristics. can.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing one embodiment of the ultrasonic probe of the present invention, and FIG. 2 is a cross-sectional view of a conventional ultrasonic probe. DESCRIPTION OF SYMBOLS 1...Piezoelectric vibrator, 2...Back load material, 3, 4...Acoustic matching layer, 5...Filling material, 6...・Acoustic lens. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
figure

Claims (4)

[Claims] (1) A piezoelectric vibrator, a back load material provided on one side of the piezoelectric vibrator, and one or more acoustic matching layers provided on the other side of the piezoelectric vibrator, and at least the piezoelectric vibrator The child is divided into a plurality of parts, and the gaps between the parts are filled with a filler in which powder such as metal powder or insulating powder and microballoons are mixed into a base material such as rubber material or synthetic resin. Ultrasonic probe. (2) The ultrasonic probe according to claim 1, wherein the rubber material that is the base material is silicone rubber, urethane rubber, butyl rubber, or neoprene rubber. (3) The ultrasonic probe according to claim 1, wherein the synthetic resin as the base material is either an epoxy resin or a urethane resin. (4) The ultrasonic probe according to claim 1, wherein the powder is one or more of tungsten powder, tantalum powder, ferrite, zinc, silicon carbide, tungsten carbide, and iron powder.