JP6080747B2 - Ultrasonic probe and ultrasonic flaw detection system - Google Patents

Description

  The present invention relates to a technique of an ultrasonic probe and an ultrasonic flaw detection system used for ultrasonic flaw detection.

  In an ultrasonic flaw detection method for inspecting various structural materials or the like, conventionally, an ultrasonic probe composed of a single element is used for transmission and reception of ultrasonic waves. In such an ultrasonic flaw detection method, when an ultrasonic signal reflected by a defect or the like inside the inspection object is detected, the defect is detected based on the propagation time of the ultrasonic signal and the position of the ultrasonic probe. Has been done. At this time, the user moves the ultrasonic probe to scan the subject and search for a position where the ultrasonic wave reflected from the defect can be obtained. At this time, the defect is calculated by integrating the difference in the reception time of the reflected wave from the bottom surface (distant boundary surface) or the surface (near boundary surface) of the inspection target and the material sound speed (sound speed in the inspection target material). Dimensions are identified. Such an ultrasonic flaw detection method has a simple and clear operation principle and is relatively easy to use, and is therefore often used for general defect inspection. However, a high SN (Signal to Noise) ratio is required so that a received signal having a reflected waveform can be confirmed.

  Furthermore, there is a method of setting a gate that becomes a waveform recording range after a predetermined time with respect to a reflected wave from the surface with respect to a temporal reference (trigger signal) and detecting the presence or absence of the reflected wave within the gate. In such a method, a defect is detected by receiving a reflected wave from a certain depth inside the inspection object.

The following is disclosed as an ultrasonic probe used in these ultrasonic flaw detection methods.
For example, Patent Document 1 discloses an ultrasonic probe having a plurality of vibration elements arranged in an annular shape and concentrically in order to increase the depth of focus. By using such an ultrasonic probe, the technique described in Patent Document 1 delays the timing of transmitting and receiving ultrasonic waves from the vibration element to be used, according to the distance to the focal point where the ultrasonic waves are focused. As a result, the technique described in Patent Document 1 can transmit and receive ultrasonic waves with respect to a plurality of different focal positions, and mechanical scanning in the ultrasonic propagation direction becomes unnecessary. Further, according to the technique described in Patent Document 1, a plurality of inspection layers can be inspected in one two-dimensional scanning.

  Patent Document 2 discloses an ultrasonic probe having a backing arranged so that the density increases stepwise outward from the center.

JP2013-11468A Japanese Patent Application Laid-Open No. 2006-314397

  In the method of flaw detection in which the reflected wave from the surface is set to a time reference (trigger signal) and the reflected wave from a certain depth inside the specimen is received after a certain time, the reflected wave from the surface is reflected. And the S / N ratio of both reflected waves from the inside of the test body needs to be high.

  In an ultrasonic probe capable of transmitting ultrasonic waves having a plurality of focal points, generally, an ultrasonic wave having a long propagation path distance has a higher attenuation of a high-frequency component than a short ultrasonic wave. Therefore, there exists a subject that the resolution of the image | video obtained from an ultrasonic wave with a long propagation path falls. The techniques described in Patent Documents 1 and 2 do not consider this point.

  Moreover, since the technique described in Patent Document 1 performs transmission / reception of a plurality of vibration elements, there is a problem that an advanced technique is required for control and the apparatus is expensive.

  The present invention has been made in view of such a background, and an object of the present invention is to improve the resolution of ultrasonic waves having a long propagation path.

In order to solve the above-described problem, the present invention provides an acoustic lens having a concave portion with a large curvature and a concave portion with a small curvature, and a frequency of vibration at a portion corresponding to the concave portion with a small curvature in the concave portion with a large curvature. And a vibration part higher than the frequency of vibration at a corresponding location.
Other solutions will be described as appropriate in the embodiments.

  According to the present invention, it is possible to improve the resolution of ultrasonic waves having a long propagation path.

It is a figure which shows the structural example of the ultrasonic flaw detection system which concerns on 1st Embodiment. It is a schematic diagram which shows the transmission path | route of the ultrasonic wave output from the ultrasonic probe which concerns on this embodiment. It is a figure which shows the attenuation state of the ultrasonic wave which concerns on this embodiment. It is a figure which shows the spectrum characteristic (at the time of transmission) of the ultrasonic wave by the ultrasonic probe which concerns on this embodiment. It is a figure which shows the spectrum characteristic (at the time of a focus arrival) of the ultrasonic wave by the ultrasonic probe which concerns on this embodiment. It is a figure which shows the modification (the 1) of the ultrasonic probe which concerns on 1st Embodiment. It is a figure which shows the modification (the 2) of the ultrasonic probe which concerns on 1st Embodiment. It is a cross-sectional schematic diagram of the ultrasonic probe which concerns on 2nd Embodiment. It is a figure which shows the modification (the 1) of the ultrasonic probe which concerns on 2nd Embodiment. It is a figure which shows the modification (the 2) of the ultrasonic probe which concerns on 2nd Embodiment. It is a cross-sectional schematic diagram of the ultrasonic probe which concerns on 3rd Embodiment. It is a figure which shows the modification (the 1) of the ultrasonic probe which concerns on 3rd Embodiment. It is a figure which shows the modification (the 2) of the ultrasonic probe which concerns on 3rd Embodiment.

Next, modes for carrying out the present invention (referred to as “embodiments”) will be described in detail with reference to the drawings as appropriate. In addition, in each figure, about the same component, the same code | symbol is attached | subjected and description is abbreviate | omitted.
<< First Embodiment >>
FIG. 1 is a diagram illustrating a configuration example of an ultrasonic flaw detection system according to the first embodiment, and FIG. 2 is a schematic diagram illustrating a transmission path of ultrasonic waves output from the ultrasonic probe according to the present embodiment. It is. In FIG. 1, (a) shows a schematic diagram of a cross section of the ultrasonic probe 1a (1) together with a configuration diagram of the ultrasonic flaw detection system 100, and (b) shows an ultrasonic probe 1a (1). A top view is shown.
As shown in FIG. 1 (a), the ultrasonic flaw detection system 100 controls the ultrasonic probe 1a (1) that transmits and receives ultrasonic waves and the transmission of ultrasonic waves from the ultrasonic probe 1a. And a processing device 10 that visualizes the internal structure of the subject from the ultrasonic waves received by the ultrasonic probe 1a. The ultrasonic probe 1a and the processing apparatus 10 are connected via the lead wire 11, but may be connected wirelessly via a wireless LAN (Local Area Network) or the like.

As shown in FIG. 1A, the ultrasonic probe 1 a includes a backing material 2 a (2), a vibration element 3 a (3), and an acoustic lens 5. The backing material 2a and the vibration element 3a are collectively referred to as a vibration part 4a (4).
The acoustic lens 5 is cylindrical as shown in FIG. As shown in FIG. 1A, the acoustic lens 5 has a concave portion 50 such that one end surface is a flat surface and the other end surface is a first concave portion 51 and a second concave portion 52. The centers of curvature of the first recess 51 and the second recess 52 are on the central axis 601 of the acoustic lens 5. However, the relationship between the curvature of the first recess 51 and the curvature of the second recess 52 is the curvature of the first recess 51> the curvature of the second recess 52. That is, the acoustic lens 5 is provided with a plurality of recesses having different curvatures at one end. Specifically, the curvature of the acoustic lens 5 is on the central axis 601 of the acoustic lens 5, and the outer concave portion 50 (second concave portion) is smaller than the inner concave portion 50 (first concave portion 51).
By making the shape of the acoustic lens 5 in this way, as shown in FIG. 2, the acoustic lens 5 can transmit two types of ultrasonic waves 201 and 202 having different focal points.

As shown in FIG. 1, the vibration element 3 a is bonded to the end surfaces of the acoustic lens 5 opposite to the first recess 51 and the second recess 52. The vibration element 3a is a circular element, for example, and has a uniform thickness. The vibration element 3a is made of a piezoelectric material such as PZT (lead zirconate titanate) or ZnO (zinc oxide), or a metal electrode such as gold, silver, or platinum.
When PZT is bonded to the acoustic lens 5 as the vibration element 3a, the same metal material as the electrode material having the same area or more as the vibration element 3a is formed in advance on the adhesive surface of the acoustic lens 5, and the vibration element 3a is bonded by diffusion bonding. Is glued.
When the vibration element 3a is made of ZnO, a metal electrode is formed in advance on the adhesion surface of the acoustic lens 5, and the vibration element 3a is bonded by a vacuum film formation method such as a sputtering method.

  A lead wire 11 is wired from the vibration element 3a. When a voltage is applied to the vibration element 3 a via the lead wire 11, the vibration element 3 a vibrates, and the vibration is transmitted to the acoustic lens 5, whereby ultrasonic waves are transmitted from the acoustic lens 5. Further, at the time of reception, the vibration transmitted through the acoustic lens 5 is converted into a voltage by the vibration element 3a. The converted voltage is sent to the processing apparatus 10 through the lead wire 11. That is, the vibration element 3a (vibration part 4a) is provided on the surface of the acoustic lens 5 opposite to the concave part 50, and vibrates when a voltage is applied.

In the vibration element 3 a, a backing material 2 a made of an epoxy resin or an epoxy resin containing tungsten is bonded to the surface that is not in contact with the acoustic lens 5.
As shown in FIGS. 1 (a) and 1 (b), the backing material 2a has a cylindrical shape, and is disposed around the first backing material 21 near the center and around the first backing material 21 (outer peripheral portion). And a second backing material 22.
The first backing material 21 and the second backing material 22 have different acoustic impedances. When the acoustic impedance of the first backing material 21 is Za and the acoustic impedance of the second backing material 22 is Zb, there is a relationship of Za> Zb. That is, the acoustic impedance of the second backing material 22 at the outer peripheral portion is smaller than the acoustic impedance of the first backing material 21 at the central portion. In other words, the vibration part 4a has a vibration frequency at a location corresponding to the concave portion having a small curvature of the acoustic lens 5 higher than a vibration frequency at a location corresponding to the concave portion having a large curvature. Specifically, the acoustic impedance of the backing material 2a is larger at a location corresponding to the first concave portion 51 having a larger curvature, and smaller at a location corresponding to the second concave portion 52 having a smaller curvature.

The adjustment of the acoustic impedance in the first backing material 21 and the second backing material 22 is performed by adjusting the content of tungsten in the backing material 2a.
As described above, when a voltage is applied to the vibration element 3a via the lead wire 11, the vibration element 3a vibrates. At this time, a portion of the vibration element 3a that is in contact with the second backing material 22 having a low acoustic impedance vibrates with a low frequency. On the other hand, in the vibration element 3a, the portion in contact with the first backing material 21 having a large acoustic impedance can only vibrate with a large frequency. In general, a member in contact with a material having a large acoustic impedance has a small amplitude and can only vibrate at a low frequency, and a member in contact with a material having a low acoustic impedance has a large amplitude and a frequency. This is because a large vibration can be performed.

Thereby, as shown in FIG. 2, the acoustic lens 5 transmits the low-frequency first ultrasonic wave 201 from the central portion, and transmits the high-frequency second ultrasonic wave 202 from the outer peripheral portion.
As described above, the acoustic impedance of the second backing material 22 in the outer peripheral portion is made smaller than the acoustic impedance of the first backing material 21 in the central portion, so that the region of the outer peripheral portion in the ultrasonic probe 1a. The second ultrasonic wave 202 transmitted from can be increased in frequency.

(Characteristic)
Here, with reference to FIG. 2, the focusing property of the ultrasonic wave by the ultrasonic probe 1a according to the present embodiment will be described. In the following drawings, the lead wire 11 and the processing device 10 are not shown, but actually, the ultrasonic probe 1a and the processing device 10 are connected by the lead wire 11 as in FIG.
The ultrasonic waves generated by applying a voltage to the vibration element 3a propagate through the acoustic lens 5 and are refracted by the first concave portion 51 and the second concave portion 52, whereby the first ultrasonic wave 201 and the second ultrasonic wave 202 are generated. Sent. The medium in the propagation path is water or alcohol. Thus, according to the ultrasonic probe 1a according to the present embodiment, the ultrasonic waves 201 and 202 are focused at the positions of the focal point 211 of the propagation distance 221 and the focal point 212 of the propagation distance 222. That is, the ultrasonic probe 1a according to the present embodiment can transmit two types of ultrasonic waves 201 and 202 having different focal points 211 and 212. Here, the propagation distances 221 and 222 are distances from the intersection of the concave portion where the ultrasonic wave is transmitted and the acoustic lens 5. Incidentally, the propagation distance 222 is a distance from the intersection of the assumed second recess 52 and the acoustic lens 5.

FIG. 3 is a diagram showing an attenuation state of ultrasonic waves according to the present embodiment.
In FIG. 3, the vertical axis represents frequency, and the horizontal axis represents propagation distance.
In FIG. 3, reference numeral 311 indicates an attenuation curve of the first ultrasonic wave 201 (FIG. 2), and reference numeral 301 indicates the frequency at the time of transmission of the first ultrasonic wave 201 (actually, the spectrum of the first ultrasonic wave 201. Frequency at the peak).
Similarly, reference numeral 312 indicates an attenuation curve of the second ultrasonic wave 202 (FIG. 2), and reference numeral 302 indicates a frequency at the time of transmission of the second ultrasonic wave 202 (actually, a frequency at the peak of the spectrum of the second ultrasonic wave 202). ).
As shown in FIG. 2, since the propagation path of the ultrasonic wave 202 is longer than that of the ultrasonic wave 201, the attenuation amount of the high frequency component in the second ultrasonic wave 202 is large. This is due to the property of sound that high frequency components are more easily attenuated.
Therefore, as shown in FIG. 1, by reducing the acoustic impedance of the backing material 2a from the central portion to the outer peripheral portion, the frequency of the second ultrasonic wave 202 is changed to the first super frequency as shown in FIG. The frequency is higher than that of the sound wave 201.

  The first ultrasonic wave 201 and the second ultrasonic wave 202 attenuate the high frequency components as they travel along the propagation path.

Reference numeral 211 indicates the focal point of the first ultrasonic wave 201 as with the reference numeral 211 in FIG. 2, and reference numeral 212 indicates the focal point of the second ultrasonic wave 202 as with the reference numeral 212 in FIG. 2.
By adjusting the acoustic impedance of the first backing material 21 and the second backing material 22, the frequency of the ultrasonic waves 201 and 202 at the time of transmission can be adjusted. As a result, the frequencies at the focal points 211 and 212 can be aligned with the frequency indicated by reference numeral 321 as shown in FIG.

Thus, by adjusting the acoustic impedance of the first backing material 21 and the second backing material 22, the frequencies at the focal points 211 and 212 of the first ultrasonic wave 201 and the second ultrasonic wave 202 can be made uniform. Thereby, the resolution at the focal point 212 can be improved.
As shown in FIG. 3, the resolution at the focal point 212 can be improved by increasing the frequency of the second ultrasonic wave 202 without aligning the frequencies at the focal points 211 and 212.

4 and 5 are diagrams showing the spectral characteristics of the ultrasonic waves obtained by the ultrasonic probe according to the present embodiment. Here, FIG. 4 shows a spectrum characteristic at the time of transmission.
In FIG. 4, reference numeral 401 (broken line) indicates a spectral characteristic when the first ultrasonic wave 201 is transmitted. Reference numeral 301 indicates a spectrum peak, and the frequency thereof is the frequency indicated by reference numeral 301 in FIG.
Similarly, reference numeral 402 (solid line) indicates a spectral characteristic when the second ultrasonic wave 202 is transmitted. Reference numeral 302 indicates a spectrum peak, and the frequency thereof is the frequency indicated by reference numeral 302 in FIG.
As shown in FIG. 4, at the time of transmission, the backing material 2a is configured so as to make the acoustic impedance of the outer peripheral portion smaller than the central portion, whereby the characteristic of the reference numeral 402 is biased to the high frequency side than the reference numeral 401.

In FIG. 5, reference numeral 501 (broken line) indicates a spectral characteristic when the first ultrasonic wave 201 is transmitted when the focal point 211 is reached.
Similarly, reference numeral 502 (solid line) indicates the spectral characteristic of the second ultrasonic wave 202 when the focal point 212 is reached.
In FIG. 5, the spectrum curves 501 and 502 are biased toward the lower frequency side than the spectrum curves 402 and 401 shown in FIG. Note that, as the ultrasonic wave 200 travels in the medium, not only the high frequency component but also the overall frequency intensity attenuates. Therefore, in FIG. 5, the frequency component on the lower frequency side than in FIG. It is decaying.
Here, the second ultrasonic wave 202 propagating through the propagation path longer than the first ultrasonic wave 201 has a higher attenuation of the high frequency component, and the peak of the spectrum coincides with the reference numeral 321. Here, the frequency of the code | symbol 321 is a frequency shown to the code | symbol 321 of FIG.

According to the first embodiment, it is possible to increase the frequency of the second ultrasonic wave 202 transmitted from the second recess 52 by reducing the acoustic impedance of the backing material 2a toward the outer periphery. In other words, by reducing the acoustic impedance toward the outer peripheral portion, it is possible to increase the frequency of ultrasonic waves having high damping (attenuation) characteristics in the region that propagates in the outer peripheral portion rather than the central portion.
Since the second ultrasonic wave 202 transmitted from the second recess 52 has a long propagation path, high-frequency components are attenuated. However, since the second ultrasonic wave 202 is increased in frequency in advance by the above-described configuration, the second ultrasonic wave 202 can maintain a necessary high-frequency component when reaching the focal point 212 even when the high-frequency component is attenuated. it can.

The technique described in Patent Document 2 also aims to improve the spatial resolution, but the backing density is minimum at the central portion and maximum at the outer peripheral portion. By doing in this way, the technique of patent document 2 strengthens the sound pressure of the ultrasonic wave transmitted from a center part, and weakens the sound pressure of the ultrasonic wave transmitted from an outer peripheral part. By doing in this way, the technique of patent document 2 makes the image by a main lobe stand out.
Such a technique described in Patent Literature 2 increases the frequency of the second ultrasonic wave 202 transmitted from the second concave portion 52 that is the outer peripheral portion, thereby resolving the resolution of the image from the second ultrasonic wave 202 having a long propagation path. This is completely different from the technique of the present embodiment that improves the above.
Moreover, according to this embodiment, control and manufacture become easy by using one vibration element 3a.
Furthermore, in the present embodiment, the curvature of the acoustic lens 5 is on the central axis 601 (FIG. 1) of the acoustic lens 5 so that the outer second concave portion 52 is smaller than the inner first concave portion 51. To do. By doing in this way, the 1st recessed part 51 and the 2nd recessed part 52 can be created using the iron ball etc. which have the curvature of each recessed part 51 and 52 and apply | coated the abrasive | polishing agent on the surface. Therefore, it is possible to easily create the first concave portion 51 and the second concave portion 52.

(Modification)
Here, a modification of the ultrasonic probe according to the first embodiment is shown.
6 and 7 are schematic cross-sectional views showing modified examples of the ultrasonic probe according to the first embodiment. In the following drawings, the acoustic lenses 5 and 5a are assumed to have a cylindrical shape as in FIG.
In the ultrasonic probe 1b (1) shown in FIG. 6, the acoustic impedance of the backing material 23 (2b, 2) in the vibrating part 4b (4) is continuously changed. Incidentally, the backing material 23 has a cylindrical shape.
In the ultrasonic probe 1c (1) shown in FIG. 7, the acoustic lens 5a (5) has three concave portions 50 (reference numerals 51 to 53). Since the acoustic lens 5a has such a configuration, it is possible to transmit ultrasonic waves having three focal points 211 to 213 as shown in FIG.
In FIG. 7, in the vibrating portion 4 c (4), the backing material 2 c (2) is a first backing material 21, a second backing material 22, and a third backing material 24 in order from the central portion to the outer peripheral portion. . At this time, if the acoustic impedance of the first backing material 21 is Za, the acoustic impedance of the second backing material 22 is Zb, and the acoustic impedance of the third backing material 24 is Zc, a relationship of Za>Zb> Zc is established. The first backing material 21 and the second backing material 22 have the same configuration as that shown in FIG. 1, and the third backing material 24 has an annular shape.
By adopting such an acoustic impedance configuration, the ultrasonic wave having a longer propagation path among the ultrasonic waves having the focal points 211, 212, and 213 can be increased in frequency, and the resolution can be improved.

<< Second Embodiment >>
Next, a second embodiment of the present invention will be described with reference to FIG.
FIG. 8 is a schematic cross-sectional view of an ultrasonic probe according to the second embodiment. In FIG. 8, the same components as those in FIG. 1 are denoted by the same reference numerals, description thereof will be omitted, and only differences from the first embodiment will be described.
The ultrasonic probe 1d (1) shown in FIG. 8 is different from the ultrasonic probe 1 shown in FIG. 1 in that the backing material 25 (2d) in the vibrating part 4d (4) is the central part 251 and the outer peripheral part 152. And the thickness of the backing material 25 is different. Specifically, as shown in FIG. 8, the central portion 251 of the backing material 25 is thick, and the outer peripheral portion 252 is thin. The backing material 25 is homogeneous, and both the central portion 251 and the outer peripheral portion 252 have a cylindrical shape.
Since the bonding method and the like of the vibration element 3a are the same as those in the first embodiment, description thereof is omitted here.

  A portion of the vibration element 3a that is in contact with the outer peripheral portion 252 where the backing material 25 is thin vibrates at a low frequency. On the other hand, in the vibration element 3a, the portion in contact with the central portion 251 where the backing material 25 is thick can only vibrate with a large frequency. This is because the portion in contact with the portion where the backing material 25 is thin can perform more detailed vibration than the portion in contact with the thick portion.

With the configuration shown in FIG. 8, the ultrasonic probe 1d has the same effect as the ultrasonic probe 1 shown in the first embodiment, and the backing material 25 is made of the same material. Therefore, the creation can be simplified. Further, the backing material 25 is made of the same material, and the vibration of the vibrator 3a is controlled by the thickness of the backing material 25, whereby the vibration element 3a can be easily controlled.
In FIG. 8, the backing material 25 may be integrated with the central portion and the outer peripheral portion, or may be configured with separate backing materials.

(Modification)
FIG. 9 and FIG. 10 are schematic cross-sectional views showing modifications of the ultrasonic probe according to the second embodiment.
Moreover, you may make it a backing material change thickness continuously, as shown in FIG.9 and FIG.10.
In the ultrasonic probe 1e (1) shown in FIG. 9, in the vibrating portion 4e (4), the backing material 26 (2e, 2) is thickest near the center and becomes thinner toward the outer peripheral portion. The thickness is changed. That is, the backing material 26 has a spherical crown shape. Further, in the ultrasonic probe 1f (1) shown in FIG. 10, in the vibrating portion 4f (4), the backing material 27 (2f, 2) is the thickest in the vicinity of the center and linearly becomes thinner toward the outer peripheral portion. The thickness is changed. That is, the backing material 27 has a conical shape. That is, the thickness of the backing material is thicker at a portion corresponding to the first concave portion 51 having a larger curvature and thinner at a portion corresponding to the second concave portion 52 having a smaller curvature.

<< Third Embodiment >>
Next, a third embodiment of the present invention will be described with reference to FIG.
FIG. 11 is a schematic cross-sectional view of an ultrasonic probe according to the third embodiment. In FIG. 11, the same components as those in FIG. 1 are denoted by the same reference numerals, description thereof is omitted, and only differences from the first embodiment will be described.
The ultrasonic probe 1g (1) shown in FIG. 11 is different from the ultrasonic probe 1 shown in FIG. 1 in that the backing material 2 (FIG. 1) is omitted in the vibration part 4g (4), and the central part. 31 and the outer peripheral part 32 differ in the thickness of the vibration element 3b (3). That is, as shown in FIG. 11, the center part 31 of the backing material 3b is thick, and the outer peripheral part 32 is thin. Both the central portion 31 and the outer peripheral portion 32 have a cylindrical shape.
Since the bonding method of the vibration element 3b is the same as that of the first embodiment, the description thereof is omitted here.

  Of the vibration element 3b, the thin outer peripheral portion 32 vibrates with a small frequency. On the other hand, the thick central portion 31 of the vibration element 3b can only vibrate with a large frequency. This is because a portion where the thickness of the vibration element 3b is thin can perform finer vibration than a thick portion.

With the configuration shown in FIG. 11, the ultrasonic probe 1g has the same effect as the ultrasonic probe 1 shown in the first embodiment, and the backing material 2 (FIG. 1) is omitted. Therefore, the creation is simple.
In addition, as for the vibration element 3b, it is desirable that the center part and the outer peripheral part are united.
Further, in the vibration element 3 b, the backing material 2 (FIG. 1) may be provided on the surface opposite to the bonding surface with the acoustic lens 5. At that time, the backing material 2 may be configured as shown in FIG. 1 or FIG.

(Modification)
12 and 13 are schematic cross-sectional views showing modifications of the ultrasonic probe according to the third embodiment.
The vibration element may be continuously changed in thickness as shown in FIGS. 12 and 13.
In the ultrasonic probe 1h (1) shown in FIG. 12, in the vibration part 4h (4), the vibration element 3c (3) is thickest in the vicinity of the center, and is thinly curved toward the outer peripheral part. Is changing. That is, the vibration element 3c has a spherical crown shape. In the ultrasonic probe 1i (1) shown in FIG. 13, in the vibrating portion 4i (4), the vibrating element 3d (3) is linear so that it is thickest near the center and becomes thinner toward the outer peripheral portion. The thickness is changed. That is, the vibration element 3d has a conical shape. That is, the thickness of the vibration elements 3c and 3d is thicker at a portion corresponding to the first concave portion 51 having a larger curvature and thinner at a portion corresponding to the second concave portion 52 having a smaller curvature.

  As described above, according to the present embodiment, the ultrasonic signal intensity on the surface and the flaw detection surface is improved, and the effect of not reducing the resolution is obtained. In addition, by selecting the focal position of the ultrasonic wave by the acoustic lens 5, it is possible to reduce the ultrasonic wave that becomes noise from other than the focal position. Furthermore, by making the vibration element 3 electrically one, control becomes easy and manufacture becomes easy.

In the present embodiment, the curvature of the inner recess 50 is greater than the curvature of the outer recess 50, but the curvature of the inner recess 50 may be greater than the curvature of the outer recess 50. For example, the concave portion 50 having a small curvature may be provided at the center, and the concave portions 50 having a small curvature may be arranged in a plurality of circles in the vicinity of the edge of the concave portion 50.
In this case, the propagation path of the first ultrasonic wave 201 transmitted from the inner recess 50 is shortened. When the acoustic lens 5 having such a configuration is used, the acoustic impedance of the backing material 2 in the outer peripheral portion is large, and the acoustic impedance of the backing material 2 in the central portion is reduced. Alternatively, the backing material 2 may have a concave shape, or a thick outer peripheral portion and a thin central portion. Alternatively, the vibration element 3 may have a concave shape, or a structure having a thick outer peripheral portion and a thin central portion.
Further, even when the acoustic lens 5 has three or more concave portions as shown in FIG. 7, the curvature is not limited to the format shown in FIG.

  In the present embodiment, the centers of curvature of the recesses 51 to 53 provided in the acoustic lens 5 are on the same axis, but the present invention is not limited to this. However, the acoustic impedance and thickness of the backing material 2 and the vibration element 3 need to correspond to the recess 50 in the acoustic lens 5. Specifically, it is necessary that the concave portion having a large curvature corresponds to the vibrating portion 4 having a large acoustic impedance, or the backing material 2 or the vibrating element 3 having a large thickness. In addition, the concave portion 50 having a small curvature needs to correspond to the vibrating portion 4 having a small acoustic impedance, or having the backing material 2 or the vibrating element 3 having a small thickness.

  For example, when the side surface of the acoustic lens 5 is viewed from one side, a concave portion 50 having a large curvature is provided on the left side, and a concave portion 50 having a small curvature is provided independently on the right side. The backing material 2 or the vibration element 3 on the side (left side) where the concave portion 50 having a large curvature is provided has a large acoustic impedance or a thick thickness. And the backing material 2 and the vibration element 3 on the side (the right side) where the concave portion 50 having a small curvature is provided have a small acoustic impedance or a thin thickness.

  In the present embodiment, each of the backing material 2 and the vibration element 3 is circular when viewed from above, but is not limited thereto, and may be a polygon or the like. Alternatively, the backing material 2 and the vibration element 3 may not be cylindrical or polygonal. If the backing material 2 having a large acoustic impedance, the backing material 2 having a large thickness, and the vibration element 3 correspond to the concave portion having a large curvature of the acoustic lens 5, the shapes of the backing material 2 and the vibration element 3 are as follows. It can be anything. Similarly, if the backing material 2 having a small acoustic impedance, the backing material 2 having a small thickness, and the vibration element 3 correspond to the concave portion having a small curvature of the acoustic lens 5, the backing material 2 and the vibration element 3 are used. Any shape may be used.

  The present invention is not limited to the above-described embodiment, and includes various modifications. For example, the above-described embodiment has been described in detail for easy understanding of the present invention, and is not necessarily limited to having all the configurations described. In addition, a part of the configuration of a certain embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of a certain embodiment. In addition, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

DESCRIPTION OF SYMBOLS 1,1b-1i Ultrasonic probe 2,2b-2f, 21-27 Backing material 3,3a-3d Vibration element 4,4b-4i Vibration part 5,5a Acoustic lens 10 Processing apparatus 11 Lead wire 100 Ultrasonic flaw detection System 201-202 Ultrasound 601 Central axis

Claims (10)

An acoustic lens having a plurality of recesses having different curvatures provided at one end; and
A vibration part that is provided on the surface of the acoustic lens opposite to the concave part and vibrates when a voltage is applied;
Have
The vibrating part is
The ultrasonic probe, wherein a frequency of the vibration in a portion corresponding to the concave portion having a small curvature is higher than a frequency of the vibration in a portion corresponding to the concave portion having a large curvature. The vibration unit includes a backing material and a vibration element,
2. The ultrasonic probe according to claim 1, wherein the acoustic impedance of the backing material is larger in a portion corresponding to the concave portion having a larger curvature and smaller in a portion corresponding to the concave portion having a smaller curvature. The vibration unit includes a backing material and a vibration element,
2. The ultrasonic probe according to claim 1, wherein the backing material is thicker at a portion corresponding to the concave portion having a larger curvature and thinner at a portion corresponding to the concave portion having a lower curvature. The vibration unit has a vibration element,
2. The ultrasonic probe according to claim 1, wherein a thickness of the vibration element is thicker at a portion corresponding to the concave portion having the larger curvature and thinner at a portion corresponding to the concave portion having the smaller curvature. The ultrasonic probe according to claim 1, wherein a curvature of the acoustic lens is on a central axis of the acoustic lens, and the outer concave portion is smaller than the inner concave portion. A plurality of concave portions having different curvatures are provided on the surface of the acoustic lens provided at one end and the acoustic lens on the opposite side of the concave portion, and vibrates when a voltage is applied. A vibration part in which the frequency of the vibration at a location corresponding to a small recess is higher than the frequency of the vibration at a location corresponding to the recess having a large curvature;
And having an ultrasonic transducer comprising
An ultrasonic flaw detection system comprising: a processing device that processes an ultrasonic signal obtained from the ultrasonic transducer. The vibration unit includes a backing material and a vibration element,
The ultrasonic flaw detection system according to claim 6, wherein an acoustic impedance of the backing material is larger in a portion corresponding to the concave portion having a large curvature, and smaller in a portion corresponding to the concave portion having a small curvature. The vibration unit includes a backing material and a vibration element,
The ultrasonic flaw detection system according to claim 6, wherein the thickness of the backing material is thicker at a portion corresponding to the concave portion having a large curvature and thinner at a portion corresponding to the concave portion having a small curvature. The vibration unit has a vibration element,
The ultrasonic flaw detection system according to claim 6, wherein a thickness of the vibration element is thicker in a portion corresponding to the concave portion having a large curvature and thinner in a portion corresponding to the concave portion having a small curvature. The ultrasonic flaw detection system according to claim 6, wherein a curvature of the acoustic lens is on a central axis of the acoustic lens, and the outer concave portion is smaller than the inner concave portion.

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