JPH09218186A - Ultrasonic probe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily reduce the reflected wave from a damper material to a piezoelectric element by providing grooves for scattering ultrasonic waves on the end surface and side surface of the damper material on the piezoelectric element back surface side of an ultrasonic probe. SOLUTION: A piezoelectric element 1, which is manufactured into a plate by use of a piezoelectric ceramic or piezoelectric thin film, generates ultrasonic waves by voltage application. A damper material 2, which is situated on the back surface of the element 1, suppresses the vibration of the element 1 after voltage application by use of metal lead and influences the depth resolution of the probe. A sound absorbing material 3, which is manufactured by mixing heavy metal (tungsten or the like) to a resin, absorbs the ultrasonic waves transmitted by the damper material 2. To connect the element 1 to the damper material 2, a low temperature connection free from adhesive layer is adapted in order to improve the depth resolution, and grooves are formed on the end surface and side surface opposite to the element 1 of the damper material 2 to scatter the ultrasonic waves. Further, the sound absorbing material 3 is buried in the grooves.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic probe used as a sensor of an ultrasonic flaw detector, and particularly to reducing reflected waves from a damper material (backing material) arranged on the back side of a piezoelectric element. The present invention relates to an ultrasonic probe having a structure.

[0002]

2. Description of the Related Art In a conventional ultrasonic probe, an acoustic matching layer for preventing reflected waves is provided between a piezoelectric element and a damper material (backing material) as described in, for example, Japanese Patent Laid-Open No. 2-264643. Is provided to reduce the reflected wave from the damper material to the piezoelectric element.

[0003]

The acoustic impedance of the acoustic matching layer for preventing reflected waves in the ultrasonic probe of the above-mentioned prior art needs to have a specific relationship with the acoustic impedance of the piezoelectric element and the damper material (backing material). Because there is
It is difficult to adjust the acoustic impedance, and the thickness of the acoustic matching layer for preventing reflected waves is λ of the wavelength λ of the generated ultrasonic waves.
It must be equal to 4, and its production is not easy.

An object of the present invention is to provide an ultrasonic probe having a structure that easily reduces the reflected wave from the damper material to the piezoelectric element without performing the adjustment and precision machining of the above-mentioned prior art.

[0005]

According to the present invention, grooves for scattering ultrasonic waves are provided on the end surface and the side surface of the damper material on the piezoelectric element rear side of the ultrasonic probe. In the present invention, a sound absorbing material that absorbs ultrasonic waves is provided in the groove of the damper material.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.
4 will be described with reference to FIG. FIG. 1 is a longitudinal sectional view showing an embodiment of the ultrasonic probe of the present invention. In FIG.
Reference numeral 1 is a piezoelectric element that generates ultrasonic waves by applying a voltage, and is manufactured in a plate shape from a piezoelectric ceramic (PbTiO ₃ or the like) or a piezoelectric thin film (ZnO or the like). A damper material (backing material) 2 is located on the back surface of the piezoelectric element 1, suppresses vibration of the piezoelectric element 1 after a voltage is applied, and uses metallic lead or the like to affect the depth resolution of the probe. A sound absorbing material 3 absorbs ultrasonic waves transmitted from the damper material 2 and is manufactured by mixing a heavy metal (such as tungsten) into the resin.

The piezoelectric element 1 and the damper material 2 of the probe are
In order to improve the depth resolution, low temperature bonding without adhesive layer is performed. A groove is cut in the end surface and the side surface of the damper material 2 opposite to the piezoelectric element 1 to scatter ultrasonic waves. Further, a sound absorbing material 3 is embedded in the groove, and the sound absorbing material 3 is manufactured by mixing a heavy metal (tungsten or the like) into a resin and has an acoustic impedance of 14 (× 10 ⁶ kg It is possible to manufacture up to about / (m ² · s).

FIG. 2 is a directivity characteristic diagram of ultrasonic waves of the piezoelectric element 1 of FIG. As shown in FIG. 2, when a pulse voltage is applied to the piezoelectric element 1 of FIG. 1 from a power source (not shown), ultrasonic waves are applied in the thickness direction of the damper material 2 on the back side as well as the subject side of the piezoelectric element 1. In addition to the longitudinal wave, a transverse wave and a surface wave are generated.

Therefore, the longitudinal wave of the ultrasonic wave of FIG. 2 is scattered mainly by the groove of the end surface of the damper material 2 of FIG. 1 and further absorbed by the sound absorbing material 3 due to the relationship of the directivity angle. Further, the surface wave and the transverse wave of the ultrasonic wave in FIG. 2 are scattered by the groove on the side surface of the damper material 2 in FIG. 1 and further absorbed by the sound absorbing material 3 due to the relationship of the directivity angle.

FIG. 3 is a side sectional view of the damper member 2 shown in FIG. As shown in FIG. 3, the surface wave and the transverse wave of the ultrasonic wave of FIG. 2 generated on the side of the damper material 2 by the piezoelectric element 1 of FIG. 1 are indicated by a practical arrow in the portion A of the groove on the side surface of the damper material 2 of FIG. It is reflected and transmitted as shown. The reflectance γ of the reflected wave here is the value of the following equation.

Γ = (14−22) / (22 + 14) ≈−0.222 where the negative sign indicates phase inversion, and 14 (× 10 ⁶ k
g / (m ² · s)) is the acoustic impedance of the sound absorbing material 3,
22 (× 10 ⁶ kg / (m ² · s)) is a damper material (lead) 2
Is the acoustic impedance of. Further, reflection and transmission are similarly performed in the B section, and the cumulative reflectance of the reflected wave here becomes a small value such as γ ² = 0.049 (0.0222 ² ). Since the attenuation of the surface wave and the transverse wave of the ultrasonic wave in the damper material (lead) 2 is also accumulated, the signal of the surface wave and the transverse wave of the ultrasonic wave received by the damper material 2 side of the piezoelectric element 1 of FIG. Is further reduced.

FIGS. 4 (a) and 4 (b) are comparison charts of the reception characteristics of the piezoelectric element 1 depending on the presence or absence of the reflected wave from the side surface of the damper material of FIG. 4A and 4B, when there is no groove on the side surface of the damper material 2 and the sound absorbing material 5 in FIGS.
As shown in (a), the received voltage of the reflected wave from the side surface of the damper material with respect to the received voltage of the transmitted wave T is measured on the time axis, and this causes noise in flaw detection with high gain, which affects the flaw detection result. Exert. On the other hand, when there is a groove on the side surface of the damper material 2 and the sound absorbing material 3 in FIGS.
As shown in (b), the received voltage of the reflected wave from the side surface of the damper material with respect to the received voltage of the transmitted wave T is reduced and is not measured on the time axis, which can improve the flaw detection result with high gain. it can.

[0012]

According to the present invention, it is possible to remarkably reduce the reflected waves from the end surface and the side surface of the damper material (backing material) on the back surface of the piezoelectric element of the ultrasonic probe and suppress the echo noise. Therefore, as a result of suppressing factors that affect the resolution during flaw detection, it is possible to perform flaw detection measurement with high resolution.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing an embodiment of an ultrasonic probe of the present invention.

FIG. 2 is a directional characteristic diagram of ultrasonic waves of the piezoelectric element of FIG.

FIG. 3 is a side elevational partial cross-sectional view of the damper member of FIG.

4 (a) and 4 (b) are reception characteristic comparison diagrams depending on the presence or absence of a reflected wave from the side surface of the damper material of FIG.

[Explanation of symbols]

 1 Piezoelectric element 2 Damper material 3 Sound absorbing material

Claims (2)

[Claims] 1. An ultrasonic probe having a piezoelectric element and a damper material on the back side of the piezoelectric element for transmitting and receiving ultrasonic waves to and from a subject, wherein grooves for scattering the ultrasonic waves are provided on the end surface and the side surface of the damper material. An ultrasonic probe equipped with. 2. The ultrasonic probe according to claim 1, wherein a sound absorbing material that absorbs ultrasonic waves is provided in the groove of the damper material.