JPH08201569A - Ultrasonic inspection equipment - Google Patents

Abstract

PURPOSE: To enable visualization of a remote object and to obtain an image of high resolution. CONSTITUTION: The shape of a piezoelectric vibrator 2 transmitting and receiving an ultrasonic wave is made convex and the center of curvature of this convex piezoelectric vibrator 2a is made a virtual position of transmission of the ultrasonic wave, that is, a virtual sound source 11. The central part of the convex piezoelectric vibrator 2a is cut 2d in the shape of a concentric circle and separated and the center of this separated piezoelectric vibrator 2c is made a position 11b of reception of the ultrasonic wave. Thus, an ultrasonic sensor part wherein a large aperture of the whole of the convex piezoelectric vibrator 2a is used at the time of transmission of the ultrasonic wave and a small aperture of the separated piezoelectric vibrator 2c is used at the time of reception of the ultrasonic wave is prepared. By this ultrasonic sensor part, the position of a reflecting source of the ultrasonic wave is visualized by using the virtual position of reception of the ultrasonic wave and a time required from transmission of the ultrasonic wave to reception thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention visualizes the structure of a reactor by scanning an ultrasonic transducer in opaque sodium in liquid metal sodium in the reactor vessel of a fast breeder reactor. The present invention relates to an ultrasonic inspection device that performs an inspection.

[0002]

2. Description of the Related Art A conventional ultrasonic inspection apparatus will be described with reference to FIG. In FIG. 6, the sensor unit indicated by reference numeral 1 is attached to the surface of the inspection robot and immersed in, for example, liquid metal sodium (hereinafter referred to as liquid metal). A high voltage pulse from the ultrasonic wave transmission unit 4 is applied to the piezoelectric vibrators 2 arranged in a plane on the surface of the sensor unit 1 based on a transmission command from the controller 3 through the transmission switching circuit 5 and selected. Ultrasonic waves are transmitted from the surface of the piezoelectric vibrator 2 into the liquid metal sodium.

Since the transmitted ultrasonic wave is reflected by the object 6 immersed in the liquid metal, the reflected ultrasonic wave is received by the piezoelectric vibrator 2 selected by the reception switching circuit 7, and the ultrasonic wave receiving section 8 is received. Then, the signal is amplified and analog-to-digital converted, and input to the signal processing device 9.

The signal processing device 9 performs aperture synthesis processing using the ultrasonic wave transmission position and the ultrasonic wave reception position and the propagation time of the ultrasonic wave reception signal reflected by the object. That is, since the ultrasonic wave reflection source of the object 6 is located on the ellipsoidal surface having a constant distance corresponding to the propagation time with the ultrasonic wave transmission position and the ultrasonic wave reception point as focal points, the ellipsoidal surfaces at different transmission and reception positions are The intersecting position becomes the reflection source position, and the images of the object 6 are reconstructed by superimposing the ellipsoids in many combinations of the transmitting position and the receiving position on the three-dimensional image memory,
It is displayed on the display device 10.

As described above, in the ultrasonic inspection apparatus using the aperture synthesis signal processing method, an ultrasonic beam is fan-shaped and transmitted, and an image with sufficient resolution can be obtained unless reflected ultrasonic waves from multiple directions are detected. Therefore, the piezoelectric vibrator 2 of the ultrasonic sensor unit 1 has a small opening, and its center is regarded as an apparent point sound source position as a transmitting position and a receiving position.

[0006]

However, although the accuracy of the transmitting and receiving positions is improved, the energy of the ultrasonic wave radiated is weak because the aperture of the piezoelectric vibrator 2 is small and the distance of the ultrasonic wave is attenuated. There is a drawback that reflected ultrasonic waves from a distant object cannot be detected.

To compensate for this drawback, as shown in FIG. 7 (a), a convex piezoelectric vibrator 2a having a relatively large opening is formed.
It is known that the center of curvature of the convex surface is used as a virtual point sound source 11 to increase the spread 12 of the ultrasonic beam and increase the radiant energy. In addition, in FIG.
Reference numeral 6'denotes a reflection point of the object, 13 an ultrasonic wave path, and 14 a reflected wavefront.

However, when the ultrasonic wave is received, since the opening of the piezoelectric vibrator 2a is large, the distance between the position of the reflection point 6'of the object and an arbitrary point on the surface of the convex piezoelectric vibrator 2a is not constant and the ultrasonic wave is not generated. Since there is a large distance difference Δl compared with the wavelength of, the ultrasonic receiving signal waveform is disturbed, and there is a problem that the measurement of the ultrasonic propagation time includes an error.

Further, as shown in FIG. 7B, a concave piezoelectric vibrator 2b having a relatively large opening is used, and the focal point of the concave piezoelectric vibrator 2b, which is the center of curvature, is used as a virtual point sound source 11. Even in a device that increases the divergence 12 of the acoustic wave beam and increases the radiant energy, the convex piezoelectric vibrator 2
As in the case of “a”, when the ultrasonic wave is received, the concave piezoelectric vibrator 2
Since the distance difference Δl between the surface b and the position of the reflection point 6 ′ of the object is large, the ultrasonic received signal waveform is disturbed, and there is a problem that the measurement of the ultrasonic propagation time includes an error.

As described above, in the ultrasonic imaging by the aperture synthesis processing, in order to obtain a high-resolution image, it is important to spread the ultrasonic beam as much as possible, and to ensure the accuracy of the ultrasonic transmission and reception positions and the ultrasonic propagation time. For that purpose, the opening of the piezoelectric vibrator must be made small, but in that case, there is a problem that the ultrasonic radiation energy becomes weak and the object at a distance cannot be measured.

On the other hand, when an ultrasonic beam whose radiant energy is increased by a piezoelectric vibrator having a large aperture is spread, the waveform of the ultrasonic signal received is disturbed and the ultrasonic propagation time measurement accuracy deteriorates, making it impossible to obtain a high-resolution image. There are two conflicting challenges.

The present invention has been made to solve the above-mentioned problems, and it is possible to increase the ultrasonic radiation energy to enable imaging of a distant object and to obtain an ultrasonic inspection apparatus capable of obtaining a high-resolution image. To provide.

[0013]

The present invention is an ultrasonic inspection apparatus for visualizing a structure in liquid metal in a reactor vessel of a liquid metal cooled fast breeder reactor, for example, even if a distant object is high. The following means are provided to enable high resolution imaging.

According to the first aspect of the invention, the piezoelectric vibrator for transmitting and receiving ultrasonic waves has a convex shape, and the ultrasonic sensor section is formed by concentrically separating a part of the central portion of the convex piezoelectric vibrator. ing. Then, when transmitting ultrasonic waves, the large opening of the entire piezoelectric vibrator is used, and when receiving ultrasonic waves, the small opening in the center of the piezoelectric vibrator is used, so that the center of curvature of the convex piezoelectric vibrator is set as the ultrasonic wave transmitting position. The object is imaged from the ultrasonic reception signal waveform with the center of the opening of the piezoelectric vibrator at the ultrasonic reception position.

According to the second aspect of the invention, the piezoelectric vibrator for transmitting and receiving ultrasonic waves has a concave shape, and the sound insulating plate has a hole diameter equivalent to the diameter of the focus at the focus position which is the center of curvature of the concave piezoelectric vibrator. And an ultrasonic sensor section configured by providing. Then, ultrasonic waves are transmitted and received through a large opening, and the object is imaged from the ultrasonic wave reception signal waveform in which the focal position is the ultrasonic wave transmission position and ultrasonic wave reception position.

In the third invention, an array type ultrasonic sensor section in which a large number of minute piezoelectric vibrators are regularly arranged on the same plane and an ultrasonic beam is generated by controlling the transmission timing of each piezoelectric vibrator. It is equipped with a phased array type ultrasonic wave transmitter that synthesizes it. Then, at the time of ultrasonic wave transmission, a spherical wave having a virtual focal point behind the array sensor as a transmission source is transmitted, and ultrasonic waves are received by respective piezoelectric vibrators, and the virtual focal point is set as an ultrasonic wave transmitting position. The object is imaged from the ultrasonic reception signal waveform in which the opening center of the piezoelectric vibrator is the ultrasonic reception position.

According to the fourth aspect of the invention, an array type ultrasonic sensor unit in which a large number of minute piezoelectric vibrators are regularly arranged on the same plane, and the ultrasonic beam is generated by controlling the transmission timing of each piezoelectric vibrator. It is equipped with a phased array type ultrasonic wave transmitter that synthesizes it. Then, when ultrasonic waves are transmitted, the ultrasonic beams that have converged in the region you want to visualize are combined and performed.
Ultrasonic waves are received by the respective piezoelectric vibrators, the ultrasonic wave transmitting position is defined as the intersection of the central axis of the ultrasonic beam and the array sensor surface, and the ultrasonic wave center is defined as the ultrasonic wave receiving position at the opening center of each piezoelectric vibrator. The object is imaged from the sound wave reception signal waveform.

According to the fifth aspect of the invention, an array type ultrasonic sensor section in which a large number of minute piezoelectric vibrators are regularly arranged on the same plane, and the ultrasonic beam is generated by controlling the transmission timing of each piezoelectric vibrator. It is a phased array ultrasonic wave synthesizing unit for synthesizing and is capable of ultrasonic wave oscillating with a waveform obtained by synthesizing a plurality of random burst waves. Then, when ultrasonic waves are transmitted, ultrasonic waves are simultaneously synthesized in multiple directions, and when ultrasonic waves are received, the waveforms received by the respective piezoelectric vibrators are combined with the respective random burst waves used for ultrasonic wave transmission. With the correlation calculation processing means, the target object is imaged from the received signal waveforms separated and detected for each ultrasonic wave transmission direction.

In the sixth invention, in order to visualize the inside of the structure in the liquid metal, an array type ultrasonic sensor section in which a large number of minute piezoelectric vibrators are regularly arranged on the same plane, and This is a phased array type ultrasonic wave transmitter / receiver unit that controls the transmission / reception timing of the piezoelectric vibrator to synthesize ultrasonic waves, and that can transmit ultrasonic waves with a waveform that combines multiple random burst waves. It has a simple structure.

The phased array control of the first random burst wave is performed based on the speed of sound of the liquid metal,
Correlation calculation processing means between the obtained received signal waveform and the first random burst wave selectively detects a reflection signal from the structure in the liquid metal, and the reflection signal is used to image the position and shape. Further, the phased array control of the second random burst wave is performed based on the position and shape of the priest and the speed of sound obtained by imaging. The correlation calculation processing means of the obtained received signal waveform and the second random burst wave selectively detects the reflection signal from the inside of the structure, and the reflection signal is used to image the inside of the structure. The two images are combined and displayed.

[0021]

According to the first aspect of the invention, the piezoelectric vibrator of the ultrasonic sensor section has a convex shape, and a part of the central portion of the piezoelectric vibrator is concentrically separated. Therefore, at the time of transmitting ultrasonic waves, the large opening of the entire piezoelectric vibrator can be used, so that the radiant energy of ultrasonic waves can be increased with the ultrasonic beam expanded and the detection sensitivity is improved. Further, the ultrasonic wave transmitting position at that time can be virtually set to the center of curvature of the convex piezoelectric vibrator.

On the other hand, when ultrasonic waves are received, since a small opening in the center of the piezoelectric vibrator is used, the distance difference between an arbitrary position on the receiving vibrator surface and the reflection source position of the object is small, and the received signal waveform is not disturbed. Also, since the ultrasonic wave reception position can be regarded as the center of the opening of the piezoelectric vibrator, highly accurate transmission / reception position accuracy and ultrasonic wave propagation time measurement accuracy can be obtained.

In the second invention, the shape of the piezoelectric vibrator of the ultrasonic sensor portion is concave, and a sound insulating plate having a hole diameter equal to the diameter of the focus is provided at the focus position which is the center of curvature of the piezoelectric vibrator. It has a structure. As a result, since a large opening of the entire piezoelectric vibrator is used during ultrasonic wave transmission, ultrasonic wave radiant energy can be increased with the beam expanded, and detection sensitivity is improved. Further, the transmission position can be virtually the center of curvature of the concave piezoelectric vibrator.

On the other hand, since the sound insulating plate is provided at the ultrasonic wave receiving position, only the ultrasonic wave on the path passing through the hole of the sound insulating plate reaches the concave piezoelectric vibrator surface, so that the center of curvature can be set. Highly accurate transmission / reception position accuracy and propagation time measurement accuracy can be obtained.

According to the third aspect of the invention, an array type ultrasonic sensor section in which a large number of minute piezoelectric vibrators are regularly arranged on the same plane, and the ultrasonic beam is generated by controlling the transmission timing of each piezoelectric vibrator. It is equipped with a phased array type ultrasonic wave transmitter that synthesizes it.

Thus, when ultrasonic waves are transmitted, phased array control is performed so as to transmit a spherical wave having a virtual focal point behind the array sensor as a transmission source, and ultrasonic waves are transmitted by the convex piezoelectric vibrator of the first invention. It is possible to increase the radiant energy as well as to synthesize the expanded ultrasonic beam with the one that performs the same action as.

The ultrasonic waves are received by the respective piezoelectric vibrators, but the openings of the piezoelectric vibrators are sufficiently small so that the center of the opening can be the ultrasonic wave reception position, and the high precision transmission / reception position accuracy and propagation time can be obtained. Measurement accuracy can be obtained.

In the fourth invention, an array type ultrasonic sensor section in which a large number of minute piezoelectric vibrators are regularly arranged on the same plane, and the ultrasonic beam is generated by controlling the transmission timing of each piezoelectric vibrator. It is equipped with a phased array type ultrasonic wave transmitter that synthesizes it.

Thus, when ultrasonic waves are transmitted, phased array control is performed so as to synthesize the ultrasonic beams converged in the region to be visualized, and the ultrasonic radiation energy is further increased. If the ultrasonic wave convergence at this time is a sufficiently long area in the ultrasonic axis direction, the intersection of the central axis of the ultrasonic beam and the array sensor surface can be regarded as the ultrasonic wave transmitting position in that area.

Further, since the apertures of the respective piezoelectric vibrators are sufficiently small at the reception position, the center of the aperture can be set as the ultrasonic reception position, and highly accurate transmission / reception position accuracy and propagation time measurement accuracy can be obtained.

In the fifth aspect of the invention, an array type ultrasonic sensor section in which a large number of minute piezoelectric vibrators are regularly arranged on the same plane, and the ultrasonic beam is generated by controlling the transmission timing of each piezoelectric vibrator. It has a phased array type ultrasonic wave oscillating section for synthesizing and is capable of ultrasonic wave oscillating with a waveform obtained by synthesizing a plurality of random burst waves.

At the time of ultrasonic wave transmission, independent random burst waves are prepared in a plurality of directions in a one-to-one manner, and the transmission timings of these independent random burst waves are synthesized by phased array control for each ultrasonic beam direction. The respective piezoelectric vibrators are driven by the generated waveform. As a result, the ultrasonic beams can be simultaneously combined and emitted in a plurality of directions.

On the other hand, when ultrasonic waves are received, the waveforms received by the respective piezoelectric vibrators are separated and detected for each ultrasonic wave transmission direction by the correlation calculation processing means with the respective random burst waves used for ultrasonic wave transmission. It is possible. This is because there is no correlation between random burst waves and
This is because there is a correlation only in the ultrasonic wave reflection waveform due to the burst wave itself, and as a result, the correlation pulse waveform can be obtained at the delay time corresponding to the ultrasonic wave propagation time, enabling highly accurate propagation time measurement. .

In the sixth aspect of the invention, an array type ultrasonic sensor section in which a large number of minute piezoelectric vibrators are regularly arranged on the same plane, and the ultrasonic beam is controlled by controlling the transmission / reception timing of each piezoelectric vibrator. Has a phased array type ultrasonic wave transmitting / receiving unit for synthesizing a plurality of random burst waves and is capable of transmitting ultrasonic waves with a waveform obtained by synthesizing a plurality of random burst waves.

Thus, the phased array control of the first random burst wave is performed based on the speed of sound of the liquid metal, and the correlation calculation means between the obtained received signal waveform and the first random burst wave The reflected signal from the structure can be selectively detected.

The position and shape of the structure are imaged by using the reflected signal, and the phased array control of the second random burst wave is performed based on the position and shape of the structure and the speed of sound obtained by imaging. The reflected signal from the inside of the structure is selectively detected by the correlation calculation processing means of the obtained received signal waveform and the second random burst wave.

The inside of the structure is imaged by using the reflection signal, and the image of the position and shape of the object is synthesized and displayed. As a result, both the inside of the liquid metal and the inside of the structure are scanned with the optimum ultrasonic beam, so that the inside of the structure in the liquid metal can be displayed with a highly accurate image.

[0038]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the ultrasonic inspection apparatus according to the present invention will be described with reference to FIG. In addition, in this embodiment, FIG.
The same parts as those shown in FIG. 2 are assigned the same reference numerals and overlapping description will be omitted, and only the main part of the present embodiment will be described.

In FIG. 1, in the ultrasonic sensor section, the shape of the piezoelectric vibrator 2 for transmitting and receiving ultrasonic waves is a large-diameter convex piezoelectric vibrator 2a, and a part of the center of the central portion of the convex piezoelectric vibrator 2a is used. A circular cutout 2d, the cutout 2d is concentrically separated, and the separated small-diameter convex piezoelectric vibrator 2c is configured as a receiving portion.

When transmitting ultrasonic waves, the transmission switching circuit 5 is turned on.
In addition, by turning off the reception switching circuit 7, the large-diameter convex piezoelectric vibrator 2a and the separated small-diameter convex piezoelectric vibrator 2c are simultaneously driven by the high voltage pulse of the ultrasonic wave transmitting section 4 to form a large opening. , Increasing the ultrasonic radiant energy. In FIG. 1, reference numeral 6'indicates a reflection point of the object, 8 indicates an ultrasonic wave receiving portion, 13 indicates a beam path, and 14 indicates a reflected wave front.

At this time, the spread 12 of the ultrasonic beam is obtained with the center of curvature of the convex piezoelectric vibrator 2a as the virtual point sound source 11, and this virtual point sound source 11 can be used as the ultrasonic wave transmitting position. On the other hand, when receiving ultrasonic waves, the transmission switching circuit 5
Is turned off and the reception switching circuit 7 is turned on, so that the small-diameter convex-shaped piezoelectric vibrator 2c in which the central portion of the large-diameter convex-shaped piezoelectric vibrator 2 is separated is selected as the receiving vibrator.

Since the opening of the selected small-diameter convex-shaped piezoelectric vibrator is sufficiently small and can be regarded as a point, the reception position 11b of the ultrasonic convex-shaped piezoelectric vibrator is set as the center position of the opening in the central part of the piezoelectric vibrator. With the spread of ultrasonic beam and the transmission of ultrasonic waves with strong radiant energy,
It is possible to improve the accuracy of the transmitting / receiving position and the accuracy of measuring the ultrasonic wave propagation time.

As a result, the conventional ultrasonic inspection apparatus shown in FIG. 6 is replaced with the ultrasonic sensor section of this embodiment and the receiving and receiving switching circuits associated therewith, so that high resolution can be achieved even for a distant object. It is possible to realize various images.

Next, a second embodiment of the ultrasonic inspection apparatus according to the present invention will be described with reference to FIG. Note that FIG. 2 shows only the main part of this embodiment, and the same parts as those of the conventional example are omitted.

In FIG. 2, the ultrasonic sensor unit forms the shape of the piezoelectric vibrator 2 for transmitting and receiving ultrasonic waves into a concave surface, and defines the concave piezoelectric vibrator 2b as a focal point which is the center of curvature of the concave piezoelectric vibrator 2b. A sound insulating plate 15 having a hole diameter equivalent to the diameter of the focal point is provided at a position, and the sound insulating plate 15 is attached by a support rod 16.

When ultrasonic waves are transmitted, ultrasonic waves are transmitted through a large opening of the entire concave piezoelectric vibrator 2b by a high voltage pulse from the ultrasonic wave transmitting portion to focus on the curvature center position.
As a result, the spread 12 of the ultrasonic beam with the focus as a virtual point sound source 11 is obtained, and strong radiant energy is also obtained. At this time, since the hole diameter of the sound insulating plate 15 is made coaxial with the diameter of the focal point, it does not affect the ultrasonic beam.

On the other hand, when ultrasonic waves are received, the wavefront of the ultrasonic waves reflected from the object 6 is larger than the hole diameter of the sound insulating plate 15, but the concave piezoelectric vibrator 2b can receive through the hole of the sound insulating plate 15. It is only the wave front that does. That is, the transmitting wavefront and the receiving wavefront of the ultrasonic wave always pass through the center of curvature of the concave piezoelectric vibrator 2b, and the center of curvature can be set as a virtual ultrasonic wave transmitting / receiving position.

Therefore, if ultrasonic waves are transmitted and received by the concave piezoelectric vibrator 2b having the sound insulating plate 15 of the present embodiment, ultrasonic waves having a large beam spread due to strong radiant energy and positional accuracy of ultrasonic wave transmission and reception are generated. And the image resolution can be improved. As a result, by replacing the ultrasonic sensor unit of the present embodiment in the conventional ultrasonic inspection apparatus shown in FIG. 6, high resolution imaging can be realized even for a distant object.

Next, a third embodiment of the ultrasonic inspection apparatus according to the present invention will be described with reference to FIGS. 3 (a) and 3 (b).

In FIG. 3 (a), an array type ultrasonic sensor section 1 in which a large number of micro piezoelectric vibrators 2e are basically arranged on the same plane and a micro piezoelectric vibrator 2e have a one-to-one correspondence with each other. A transmission phase delay unit 17 is connected via the sound wave transmission unit 4. The transmission phase delay unit 17 is connected to the controller 3, and the controller 3 is connected to output to the ultrasonic wave receiving unit 8, the signal processing device 9 and the display device 10.

A high voltage pulse based on the ultrasonic wave transmission timing of the phase delay unit 17 set by a command from the controller 3 is applied from the ultrasonic wave transmitter 4 to each piezoelectric vibrator 2e arranged in an array.

Thus, the piezoelectric vibrator of the phased array type sensor unit shown in FIG. 3B is generated by the ultrasonic wave transmission of the phased array system which controls the synthesis of the ultrasonic beams by utilizing the interference of the generated ultrasonic wave fronts. Virtual sound source on the back of 2e
That is, by setting a virtual ultrasonic focal point and synthesizing an outgoing spherical wave 18 having the focal point position as a point sound source, an ultrasonic wave having strong ultrasonic radiation energy and a large beam spread is generated.

According to the second embodiment, the same operation as the ultrasonic wave generation using the convex piezoelectric vibrator 2a of the first embodiment can be realized by the minute piezoelectric vibrator 2e of the array type sensor section 1. become.

Further, when the ultrasonic wave is received, the reflected ultrasonic wave from the object 6 returns by the transmitted spherical wave 18 centered on the position of the reflection source, so that the minute piezoelectric vibrator 2e of the array type sensor unit 1 is used.
Can be received respectively. The received signal is the ultrasonic wave receiver 8
Received signal waveform data digitized by a signal amplifier and a high-speed analog-to-digital (A / D) converter built in the input device are input to the signal processing device 9. In FIG. 3B, reference numeral 12 denotes the beam spread, 13 denotes the ultrasonic wave path from the reflection point 6 ′ of the object, and 14 denotes the reflected wave front.

Under the control of the controller 3, the series of operations from the transmission of ultrasonic waves to the reception of ultrasonic waves are repeatedly performed by changing the transmission position to record a large number of ultrasonic wave waveform data, and the signal processing device 9 performs ultrasonic wave data recording. The object is imaged by aperture synthesis processing using the sound wave transmitting position and receiving position and the received signal waveform data, and displayed on the display device 10.

In this case, the ultrasonic wave transmitting position can be regarded as the virtual focus position, and the receiving position can be regarded as the receiving position because the opening of the micro-piezoelectric vibrator 2e of the array type sensor unit 1 is sufficiently small so that the center of the opening can be regarded as the receiving position. The sound wave transmission / reception position accuracy and the propagation time measurement accuracy are improved, and as a result, high-resolution imaging can be obtained even for a distant object.

Next, a fourth embodiment of the ultrasonic inspection apparatus according to the present invention will be described with reference to FIGS. 3 and 4.

In this fourth embodiment, the controller 3 shown in FIG. 3 spreads the focused ultrasonic beam 12 within the visualization region 19 to be visualized with respect to the transmission phase delay unit 17 as shown in FIG. Is set, the transmission phase delay amount 20 of each of the micro piezoelectric vibrators 2e arranged in the phased array type of the sensor unit 1 based on the ultrasonic beam converging position f of the focal point is set to perform the phased array control. In FIG. 4, reference numeral 6 is an object, 13 is an ultrasonic wave path, 14 is a reflected wavefront, 22 is a transmitting / receiving position, and f is an ultrasonic beam converging position.

In this case, assuming that the ultrasonic focusing is a region sufficiently long in the beam axis direction, in that region, the ultrasonic beam is
The transmission position 22 at the intersection of the ultrasonic beam center 21 of the central axis of 12 and the surface of the micro piezoelectric vibrator 2e of the array type sensor unit can be regarded as the ultrasonic transmission position.

On the other hand, ultrasonic waves are received by the micro-piezoelectric vibrators 2e of the respective array type sensor units, and their transmitting positions 22
The received signal waveform data is recorded and the aperture synthesis processing is performed by the signal processing device 9 shown in FIG. In this case, the visualization area 19
Spreading the transmitted ultrasonic beam rather than doing the whole thing
A limit is set in the range of 12 to shorten the aperture synthesis processing time. This series of operations is performed every time the ultrasonic beam transmission position 22 and the direction are changed, and the entire visualization region 19 is imaged.

According to this embodiment, since a focused ultrasonic beam is used, a very large radiant energy is obtained, and the detection ability of a distant object is improved. Also, since the transmitted ultrasonic beam is narrow, the effect of aperture synthesis processing is small,
Since not only the position of the transmitted ultrasonic wave is changed but also the direction of the ultrasonic beam is changed, a good effect of aperture synthesis is obtained in total.

A fifth embodiment of the ultrasonic inspection apparatus according to the present invention will be described with reference to FIGS. 3 and 5. This fifth
In this embodiment, instead of the ultrasonic pulse transmission in the configuration of the third embodiment, it is possible to perform ultrasonic transmission with a random burst wave and also with a waveform obtained by combining a plurality of random burst waves. The ultrasonic wave transmission unit 4 and the transmission phase delay unit 17 shown in FIG. 3 are configured as follows.

The delay circuit of the transmission phase delay unit 17 shown in FIG. 3 reads the waveform data previously written in the memory at high speed, converts it into digital / analog (D / A), and inputs it to the ultrasonic wave transmission unit 4. The ultrasonic wave transmission unit 4 is composed of a power amplifier, power-amplifies the input waveform, and drives the micro piezoelectric vibrator 2e of the array type sensor unit. At this time, the delay circuit, D
/ A converter and power amplifier are one-to-one with the micro piezoelectric vibrator 2e
It corresponds in.

The delay amount of the transmission phase delay unit 17 is set by shifting the writing position of the waveform data in the memory, and the synthesis of a plurality of waveforms is also performed by the method of writing the synthesized waveform data in the memory. The signal processing device 9 is adapted to perform aperture synthesis by using the result of the correlation calculation processing of the received signal waveform from the ultrasonic wave reception unit 8 and the burst waveform used for transmission.

In such a configuration, for the transmission of ultrasonic waves, an independent random burst wave corresponding to a plurality of directions or positions in a one-to-one correspondence is prepared in advance, and as shown in FIG. The required phase delay amount 20a is obtained for each direction.

Then, the previously prepared random burst waveform is written in the memory in the transmission delay setting section 17 of the corresponding micro-piezoelectric vibrator 2e of the array type sensor section with a shift corresponding to the phase delay time amount 20a. This operation is performed for all the memories of the delay circuit corresponding to the micro piezoelectric vibrator 2e necessary for beam synthesis.

Next, the phase delay time amount 20b in the position direction of the special ultrasonic beam is obtained, and the same operation as the above is performed, but the writing of the random burst waveform is performed by the addition with the already written waveform data. Become.

These operations are repeated for each position of the ultrasonic beam direction, and the micro piezoelectric vibrator 2e is driven under this setting condition, whereby the ultrasonic beams can be simultaneously synthesized and emitted to a plurality of positions and directions.

That is, when an ultrasonic wave is transmitted with a waveform obtained by combining a plurality of independent random burst waves, an ultrasonic beam is formed at a directional position where the wavefronts of the same random burst wave component are aligned in the same phase, The ultrasonic beam is not formed at the other positions because the phases are not aligned.

On the other hand, in the reception of ultrasonic waves, the reflected waves from the object by a plurality of ultrasonic beams are received by the minute piezoelectric vibrator 2e, but the waveforms of the synthesized ultrasonic beams are independent random waveforms. Therefore, it is possible to separate and detect each ultrasonic wave transmission direction by means of the correlation calculation means with the random burst wave used for transmission. This is random
This is because the burst waves have no correlation with each other, but only with the reflected waveform of the random burst waves themselves.

As a result, since the correlation pulse is obtained at the delay time corresponding to the ultrasonic wave propagation time for each ultrasonic wave transmitting position direction, it is possible to measure the propagation time with high accuracy and the image of the object by the aperture synthesizing process is obtained. Resolution is improved. Also,
Data recording time is improved because ultrasonic beams can be emitted simultaneously in multiple directions.

Furthermore, the fact that ultrasonic waves can be transmitted and received with a plurality of random burst waves means that for a structure in liquid metal, for example, a phased array of random burst waves based on the speed of sound in liquid metal is used. By control, the position and shape of the structure in the liquid metal are imaged and detected.

Also, using another random burst wave,
It is possible to perform phased array control at the sound velocity of the structure, detect a reflection signal from the inside of the structure to form an image, and synthesize and display the image of the structure immersed in the liquid metal.

[0074]

EFFECTS OF THE INVENTION According to the present invention, for example, an ultrasonic inspection apparatus for visualizing a structure in liquid metal in a reactor vessel of a liquid metal cooled fast breeder reactor has the following effects.

(1) A convex piezoelectric vibrator is used for the ultrasonic sensor section, and a part of the central portion of the convex piezoelectric vibrator is separated into concentric circles. , And the ultrasonic wave transmission position is the center of curvature of the convex piezoelectric vibrator, and at the time of reception, the small opening in the center is used, so that the center of the opening is the reception position. It is possible to improve the image accuracy by strengthening and improving the receiving and transmitting position accuracy, and also improve the resolution in the distance.

(2) By using a concave piezoelectric vibrator in the ultrasonic sensor section and providing a sound insulating plate having a hole diameter equivalent to the focal point at the focal position which is the center of curvature, the ultrasonic wave transmission / reception path is always concave. Since it is located at the center of curvature of, it is possible to improve the image accuracy by improving the originating and receiving position accuracy and the distant resolution.

(3) The array type piezoelectric vibrator is used for the ultrasonic sensor section, ultrasonic waves are transmitted by phased array control so that a virtual point sound source is provided behind the piezoelectric vibrator, and ultrasonic waves are received by the array vibrator. Since this is performed for each, it is possible to improve the resolution in the distance as well as the image accuracy due to the improvement in the ultrasonic transmission / reception position accuracy. .

(4) The array type piezoelectric vibrator is used for the ultrasonic sensor section, the focused ultrasonic beam is emitted by the phased array control, and the ultrasonic radiation energy is further strengthened, so that the ultrasonic image can be made highly accurate. become.

(5) When an array type piezoelectric vibrator is used for the ultrasonic sensor section and a focused ultrasonic beam is synthesized by phased array control, ultrasonic waves are transmitted and received by a plurality of random burst waves and ultrasonic waves are transmitted in multiple directions. Since the beams are emitted at the same time, the ultrasonic radiation energy is further strengthened, and the accuracy of ultrasonic images can be improved.

[Brief description of drawings]

FIG. 1 is an ultrasonic beam diagram showing, in a partial block diagram, a convex ultrasonic sensor unit in a first embodiment of an ultrasonic inspection apparatus according to the present invention.

FIG. 2 is a schematic cross-sectional view showing a convex ultrasonic sensor unit in a second embodiment of the ultrasonic inspection apparatus according to the present invention, in which the ultrasonic beam line is partially used.

FIG. 3A is a block diagram showing an array type sensor unit and its ultrasonic transmitting / receiving unit system in a third embodiment of an ultrasonic inspection apparatus according to the present invention, and FIG. 3B shows the sensor unit of FIG. The ultrasonic beam diagram for explaining.

FIG. 4 is an ultrasonic beam diagram schematically showing a part of an array-type sensor in a fourth embodiment of the ultrasonic inspection apparatus according to the present invention.

FIG. 5 is an ultrasonic beam diagram showing a phased array with random burst waves in a fifth embodiment of the ultrasonic inspection apparatus according to the present invention.

FIG. 6 is a block diagram partially showing a conventional ultrasonic inspection apparatus.

7A is an ultrasonic beam diagram showing an example using a convex piezoelectric vibrator in the apparatus of FIG. 6, and FIG. 7B is an ultrasonic beam diagram showing an example using the same concave piezoelectric vibrator.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Sensor part, 2 ... Piezoelectric vibrator, 2a ... Convex piezoelectric vibrator, 2b ... Concave piezoelectric vibrator, 2c ... Separate convex piezoelectric vibrator, 2d ... Notch, 2e ... Micro piezoelectric vibrator, 3
... Controller, 4 ... Ultrasonic wave transmitting section, 5 ... Transmission switching circuit, 6 ... Object, 6 '... Reflection point of object, 7 ... Reception switching circuit, 8 ... Ultrasonic wave receiving section, 9 ... Signal processing device, 10
... Display device, 11 ... Virtual point sound source, 11b ... Receiving position of convex piezoelectric vibrator, 12 ... Beam spread, 13 ... Ultrasonic path, 14
… Reflected wavefront, 15… Sound insulation plate, 16… Support rod, 17… Transmitting phase delay part, 18… Transmitting spherical wave, 19… Visualization region, 20… Phase delay time amount, 21… Ultrasonic beam center, 22… Sending and receiving Position, f ...
Ultrasonic beam focusing position.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G01S 7/523 7/526 15/89 G21C 17/08 GDF // G06T 1/00 8907-2F G01S 7/52 J 8907-2F 15/89 B G06F 15/62 380 (72) Inventor Tsutomu Shioyama 1 Komukai Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Ltd. Corporate Research & Development Center (72) Inventor Yukinori Futami, 8 Shinsita-cho, Isogo-ku, Yokohama-shi, Kanagawa, Ltd. In Toshiba Yokohama Works, Inc. (72) Inventor, Hirokazu Karasawa 8-Shin-Sugita-cho, Isogo-ku, Yokohama, Kanagawa, Japan

Claims (6)

[Claims] 1. A sensor unit in which a piezoelectric vibrator that transmits ultrasonic waves to an object and receives ultrasonic waves reflected from the object is arranged, and an ultrasonic wave receiving unit that receives ultrasonic waves from the sensor unit. And a signal processing device connected to this ultrasonic receiving unit,
In an ultrasonic inspection apparatus including a display device connected to the signal processing device, a controller connected to an input side of the signal processing device, and an ultrasonic wave transmission unit connected to the controller, the sensor unit includes the piezoelectric vibration. The shape of the child is convex, the center of curvature of this convex piezoelectric vibrator is the virtual ultrasonic wave transmitting position, and the central portion of the convex piezoelectric vibrator is cut into concentric circles and separated, and this separation is performed. With the center of the piezoelectric vibrator as the ultrasonic wave reception position, a large opening of the entire convex piezoelectric vibrator is used for ultrasonic wave transmission, and a small opening of the separated piezoelectric vibrator is used for ultrasonic wave reception. An ultrasonic inspection apparatus, wherein an ultrasonic reflection source position is imaged using the virtual ultrasonic wave reception position and the time from ultrasonic wave transmission to reception. 2. A sensor unit in which a piezoelectric vibrator for transmitting ultrasonic waves to an object and receiving ultrasonic waves reflected from the object is arranged, and an ultrasonic wave receiving unit for receiving ultrasonic waves from the sensor unit. And a signal processing device connected to this ultrasonic receiving unit,
In an ultrasonic inspection apparatus including a display device connected to the signal processing device, a controller connected to the input side of the signal processing device, and an ultrasonic wave transmission unit connected to the controller, the sensor unit is a piezoelectric vibrator. Is a concave shape, and a sound insulating plate having a hole diameter equivalent to the diameter of the focal point is provided at the focal position formed on the front surface of the concave piezoelectric vibrator, and the focal position is a virtual ultrasonic wave transmitting / receiving position. An ultrasonic inspection apparatus, comprising: an ultrasonic sensor for performing ultrasonic imaging, and imaging an ultrasonic reflection source position using the virtual ultrasonic wave transmission / reception position and the time from ultrasonic transmission to reception. 3. A sensor unit in which a piezoelectric vibrator for transmitting ultrasonic waves to an object and receiving ultrasonic waves reflected from the object is arranged, and an ultrasonic wave receiving unit for receiving ultrasonic waves from the sensor unit. And a signal processing device connected to this ultrasonic receiving unit,
In an ultrasonic inspection apparatus including a display device connected to the signal processing device, a controller connected to the input side of the signal processing device, and an ultrasonic wave transmission unit connected to the controller, the sensor unit has a large number of minute portions. It consists of an array type ultrasonic sensor in which various piezoelectric vibrators are regularly arranged on the same plane, and when the ultrasonic wave is transmitted, the above-mentioned is performed by the phased array control that controls the individual transmission timings of the piezoelectric vibrators to synthesize an ultrasonic beam. Spherical waves are transmitted with the virtual focus behind the piezoelectric vibrator as the transmission source, and ultrasonic waves are received by each piezoelectric vibrator.The position of the virtual transmission source, the position of the reception oscillator, and the time from ultrasonic transmission to reception are used. An ultrasonic inspection apparatus characterized in that the ultrasonic reflection source position is imaged. 4. The array-type ultrasonic sensor synthesizes ultrasonic beams converged in a region to be visualized by phased array control when transmitting ultrasonic waves, and superimposes an intersection point between the central axis of the ultrasonic beam and the array sensor surface. At the sound wave transmission position, ultrasonic wave reception is performed by each piezoelectric vibrator, and the ultrasonic wave within the range of the directivity angle of the transmitted ultrasonic beam is calculated using the transmission position and the reception vibrator position and the time from ultrasonic wave transmission to reception. 4. The ultrasonic inspection apparatus according to claim 3, wherein a series of operations for imaging the position of the acoustic wave reflection source is repeated while changing the direction and position of the transmitted ultrasonic beam to image the entire visible region. . 5. A configuration in which the array type ultrasonic sensor is capable of transmitting ultrasonic waves having a waveform in which a plurality of random burst waves are combined and the delay time of each random burst wave can be set arbitrarily. , Phased array control to synthesize ultrasonic beams simultaneously in multiple directions,
At the time of reception, the waveform received by each array element is subjected to correlation calculation processing with each random burst wave used for ultrasonic wave transmission to obtain a received waveform for each ultrasonic wave transmission direction, and aperture synthesis processing is performed using that waveform. The ultrasonic inspection apparatus according to claim 3, wherein the ultrasonic reflection source is imaged. 6. When performing phased array control using a plurality of random burst waves using the array type ultrasonic sensor, an image of a liquid metal intermediate structure is imaged by a first random burst wave and its position And the shape of the structure is detected by the liquid metal medium speed of sound, and the phased array control is performed by the position and shape of the structure and the speed of sound so that the inside of the structure is imaged by the second random burst wave. The ultrasonic inspection apparatus according to claim 5, wherein the two images obtained are combined and displayed.