JP2004101422A - Ultrasonic inspection apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic inspection apparatus for externally inspecting the state of a subject disposed inside a closed container, without having to dip piezoelectric conversion elements into a liquid. <P>SOLUTION: The ultrasonic inspection apparatus is provided with a piezoelectric conversion part, having a plurality of the piezoelectric conversion elements, a solid sound propagation medium acoustically connected to the piezoelectric conversion part and a drive part for selecting the piezoelectric conversion element from the piezoelectric conversion part and generating an ultrasonic wave. Since a plurality of the disposed piezoelectric conversion elements are selected electronically and transmit ultrasonic waves, visualization can be implemented, without mechanical scanning. Since the subject is internally accommodated and the solid sound propagation medium penetrates the container for storing a liquid acoustic medium or is acoustically connected to an outer face of the container, the outer shape and the internal structure of the subject in the container can be visualized as the piezoelectric conversion elements are disposed outside the container. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ultrasonic inspection apparatus that visualizes a state in a subject using ultrasonic waves generated from a plurality of piezoelectric transducers.
[0002]
[Prior art]
2. Description of the Related Art An ultrasonic inspection apparatus that visualizes a state inside a subject and inspects the inside of the subject for a defect such as a void or a peeled joint is used. Here, in the ultrasonic inspection by the water immersion method, a piezoelectric transducer (an ultrasonic generator and a sensor) and an object are immersed in a liquid such as water, and the ultrasonic transducer is mechanically scanned while being superposed. The inside of the subject is visualized by transmitting and receiving sound waves (see Non-Patent Document 1).
[0003]
[Non-patent document 1]
Kokura, "Present State of Non-Destructive Inspection of Semiconductor Packages", Non-Destructive Inspection, Japan Non-Destructive Inspection Association, May 2001, Vol. 291-292
[0004]
[Problems to be solved by the invention]
However, in the water immersion method, since the piezoelectric transducer is immersed in the liquid, the liquid easily penetrates into the piezoelectric transducer and the durability thereof is easily reduced. In addition, it has been difficult to externally perform an internal inspection of a subject arranged inside a closed container.
In view of the above, an object of the present invention is to provide an ultrasonic inspection apparatus capable of externally inspecting the state of a subject arranged inside a closed container without immersing a piezoelectric transducer in a liquid.
[0005]
[Means for Solving the Problems]
An ultrasonic inspection apparatus according to the present invention includes a piezoelectric conversion section having a plurality of piezoelectric conversion elements, a flat solid acoustic propagation medium acoustically connected to the piezoelectric conversion section, and a piezoelectric conversion element from the piezoelectric conversion section. A drive unit that selects and generates ultrasonic waves, and a part of the ultrasonic waves transmitted from the piezoelectric conversion element selected by the drive unit is based on the reflected ultrasonic waves that are reflected from the subject in the liquid acoustic medium. A detection unit that detects an electric signal generated from the piezoelectric conversion element of the piezoelectric conversion unit, and an image generation unit that generates an image representing the internal state of the subject based on the electric signal detected by the detection unit. A display unit for displaying the image generated by the image generation unit.
[0006]
By electronically selecting and transmitting and receiving a plurality of piezoelectric transducers, visualization can be performed without mechanical scanning. In addition, the solid-state acoustic propagation medium is penetrated into the container that stores the subject inside and stores the liquid acoustic medium, or is connected acoustically to the outer surface of the container, so that the piezoelectric transducer is moved out of the container. It is possible to visualize the external shape and the internal structure of the subject in the container while being arranged.
Here, “acoustically connected” refers to a state in which sound can be transmitted between different acoustic media. Note that, by sandwiching the coupling agent between the acoustic media, the sound transmission characteristics between different acoustic media can be further improved.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
In the ultrasonic inspection apparatus according to the embodiment of the present invention, an array sensor in which piezoelectric conversion elements are arranged in a matrix or in a line is fixed to a shoe material via a coupling agent. The shoe material is connected to the outer surface of the test container containing the liquid acoustic medium, or penetrates the test container through an opening. As a result, it is possible to perform an internal inspection by collecting electrical signals of reflected ultrasonic waves or transmitted ultrasonic waves from a subject installed in the inspection container and synthesizing a visualized image from the collected data. .
[0008]
Here, when the position of the surface of the subject in the test container, that is, the surface of the piezoelectric transducer and the surface (interface) of the test object are known, the signal is transmitted from the piezoelectric transducer and reflected from the interface to be converted to the piezoelectric transducer. The sound velocity of the liquid acoustic medium in the inspection container is obtained from the propagation time of the reflected ultrasonic wave up to the time, and is used for correction in the image generation processing, so that the accuracy of image data can be improved.
In addition, by installing a reflector for changing the ultrasonic wave transmission angle in the test container, measurement and visualization of the subject from the horizontal direction can be performed.
[0009]
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(First Embodiment)
FIG. 1 is a schematic diagram illustrating the configuration of the ultrasonic inspection apparatus according to the first embodiment of the present invention. As shown in FIG. 1, the ultrasonic inspection apparatus includes an array sensor 6, a transmission / reception switching device 8, an image synthesis device 9, and a display device 10, and is provided in a subject 3 immersed in water 2 in a container 1. The defect 4 can be visualized and represented. On the front surface of the array sensor 6, a flat shoe material 5 is closely fixed via a coupling agent 7. Further, a reflector 13 and a fixing jig 15 are installed in the container 1.
[0010]
The container 1 is a container for storing the water 2 and the subject 3, and is used for inspecting the subject 3 by ultrasonic waves while being immersed in the water 2.
Water 2 is a kind of liquid acoustic medium that propagates ultrasonic waves. That is, a liquid other than the water 2, for example, oil or the like can be used as the liquid acoustic medium.
The subject 3 is an object to be inspected by inspecting the internal state by ultrasonic waves and inspecting for the presence or absence of a defect 4 (for example, void, peeling of bond, etc.). The subject 3 is positioned and fixed in the container 1 by the fixing jig 15.
The shoe member 5 is an acoustic medium (solid acoustic medium) made of a flat solid and serves as a part of a propagation path of an ultrasonic wave between the array sensor 6 and the subject 3. Material.
The array sensor 6 functions as a piezoelectric conversion unit, and a plurality of piezoelectric conversion elements 20 are arranged in an array. The piezoelectric transducer 20 is a transducer that converts electricity into pressure and converts pressure into electricity. The piezoelectric transducer 20 transmits ultrasonic waves and receives reflected ultrasonic waves X reflected from the defects 4 and the like in the subject 3. it can.
The reflector 13 functions as a reflector, reflects the ultrasonic wave transmitted from the predetermined piezoelectric conversion element 20, changes its propagation direction, and makes the ultrasonic wave incident from the side of the subject 3.
The coupling agent 7 is a medium for improving an acoustic coupling state between the shoe material 5 and the array sensor 6, and is usually a semi-fluid acoustic medium having a moderate viscosity, for example, glycerin is used. Can be By interposing the coupling agent 7 between the shoe member 5 and the array sensor 6, transmission of ultrasonic waves between the shoe member 5 and the array sensor 6 can be performed efficiently, and the shoe member 5 The reflection (a kind of noise) of the ultrasonic wave at each interface of the array sensor 6 is reduced.
[0011]
The transmission / reception switching device 8 is a device for selecting an element for transmitting and receiving ultrasonic waves from the plurality of piezoelectric conversion elements 20 in the array sensor 6, and includes a driving element switching circuit 21, a signal generation unit 22, a signal detection circuit. 23 and an amplification unit 24.
The driving element switching circuit 21 functions as a driving unit, and is a switching circuit for inputting an electric signal generated by the signal generating unit 22 and selecting the piezoelectric conversion element 20 that generates ultrasonic waves.
The signal generation unit 22 is for generating an electric signal for generating ultrasonic waves in the piezoelectric conversion element 20, and generally includes an oscillation circuit.
The signal detection circuit 23 functions as a detection unit, and is a detection circuit that detects an electric signal generated by each of the piezoelectric conversion elements 20 by receiving an ultrasonic wave. Upon this detection, the piezoelectric conversion element 20 can be appropriately selected, and an electric signal corresponding to the selected piezoelectric conversion element 20 is sent to the amplification unit 24. At this time, a plurality of piezoelectric conversion elements 20 can be selected to improve parallelism of signal processing.
The amplification unit 24 is for amplifying the signal detected by the signal detection circuit 23, and amplifies the number corresponding to the number of outputs from the signal detection circuit 23 (the number of the selected piezoelectric conversion elements 20). The element is present.
That is, the transmission / reception switching device 8 selects a receiving element that receives the reflected ultrasonic wave X (ultrasonic echo X) from the piezoelectric conversion element 20, amplifies the electric signal E generated by the selected piezoelectric conversion element 20, and then displays the image. The data is sequentially transmitted to the synthesizing device 9.
[0012]
The image synthesizing device 9 functions as an image generating unit that generates an image, and includes an A / D converter 25 and an arithmetic device 26. The A / D converter 25 performs analog-to-digital conversion of the electric signal received by the drive element switching circuit 21.
The arithmetic unit 26 functions as a sound speed correction unit and an image generation unit, and performs a signal processing for visualizing a state of an inspection target based on a signal digitized by the A / D converter 25. It is.
The display device 10 is a display device that displays information guided from the image synthesizing device 9, and for example, a CRT or a liquid crystal display device can be used.
[0013]
(Operation of ultrasonic inspection equipment)
Hereinafter, the operation of the ultrasonic inspection apparatus will be described.
(1) The ultrasonic wave is transmitted from the piezoelectric conversion element 20 by the electric signal input to the piezoelectric conversion element 20 from the signal generation unit 22 via the drive element switching circuit 21. The ultrasonic wave transmitted from the piezoelectric transducer 20 reaches the defect 4 in the subject 3 via the shoe material 5 and the water 2. This ultrasonic wave is reflected by the defect 4 to become a reflected ultrasonic wave X, and is received again by the piezoelectric conversion element 20 via the water 2 and the shoe material 5.
[0014]
(2) An electric signal generated from each piezoelectric conversion element 20 by the received reflected ultrasonic wave X is detected, amplified, and digital-converted by the signal detection circuit 23, the amplification unit 24, and the A / D converter 25, and is converted by the arithmetic unit 26. Image synthesis processing is performed.
This image synthesis processing can be performed by aperture synthesis processing using transmission / reception propagation time td from transmission to reception of ultrasonic waves and intensity (amplitude value) Ad of reflected ultrasonic waves X.
That is, the ultrasonic reflection source (for example, the defect 4) of the subject 3 is placed on an elliptical surface (equidistant propagation surface 12) having a constant distance corresponding to the transmission / reception propagation time td with the transmission position and the reception position of the ultrasonic wave as focal points. Therefore, the positions where the ellipsoids intersect at different transmission positions and reception positions are the reflection source positions, and the elliptical surfaces at many combinations of the transmission positions (piezoelectric conversion elements 20) and the reception positions (piezoelectric conversion elements 20) are obtained. By performing the superposition on a three-dimensional image memory, for example, an image inside the subject 3 can be reconstructed.
Specifically, the equidistant propagation surface 12 corresponding to the transmission / reception propagation time td is calculated for each pair of piezoelectric transducers 20 selected on the transmission side and the reception side, and the calculated equidistant propagation surface 12 is calculated. Is added to the amplitude value Ad of the reflected ultrasonic wave X. A plurality of equidistant propagation surfaces 12 corresponding to each combination of the piezoelectric transducers 20 selected on the transmission side and the reception side are calculated, and the amplitude values of the reflected ultrasonic waves X on the plurality of equidistant propagation surfaces 12 are calculated. By the addition, an image of the subject 3 can be generated including the defect 4 and the like therein.
The transmission / reception propagation time td is a time required from the transmission of the ultrasonic wave to the reception of the reflected ultrasonic wave X, and the time t1 at which the ultrasonic wave was transmitted from the piezoelectric conversion element 20 on the transmission side and the time when the reception-side piezoelectric conversion element 20 This is the difference (t2-t1) between the times t2 at which the ultrasonic waves were received.
[0015]
(3) In calculating the equidistant propagation surface 12 from the transmission / reception propagation time td, it is necessary to take into account refraction at both interfaces of “the interface between the shoe material 5 and the water 2” and “the interface between the subject 3 and the water 2”. preferable. More specifically, the equidistant propagation surface 12 is calculated more precisely in consideration of the Snell's equation expressed by the following equations (1) and (2).
C5 / sin θ52 = C2 / sin θ25 Equation (1)
C2 / sin θ23 = C3 / sin θ32 Equation (2)
Here, C5: velocity of ultrasonic wave in shoe material 5 C2: velocity of ultrasonic wave in water 2 C3: velocity of ultrasonic wave in subject 3 θ52: ultrasonic wave from shoe material 5 to water 2 (Emission) angle θ25 of the ultrasonic wave from the shoe material 5 to the water 2 θ23: incident (emission) angle of the ultrasonic wave from the water 2 to the object 3 θ32: the object 3 from the water 2 Is the angle of emission (incidence) of the ultrasonic wave to the.
[0016]
(4) The ultrasonic wave transmitted from the piezoelectric transducer 20 is reflected in the horizontal direction by the reflector 13 fixed in the container 1, and the ultrasonic wave Z for horizontal measurement can be incident on the side surface of the subject 3. . The ultrasonic wave Z for horizontal direction measurement is reflected by the side surface of the subject 3 and the defect 4 inside the subject 3, is received by the piezoelectric conversion element 20, and can be used in the image synthesizing process in the arithmetic unit 26.
As described above, by capturing the data of the ultrasonic wave Z for horizontal direction measurement, it is possible to simultaneously perform the horizontal position measurement of the side surface of the subject 3 and the defect 4 therein or the imaging in the horizontal direction.
By dividing the piezoelectric transducer 20 for transmitting and receiving the horizontal direction measurement ultrasonic wave Z from the piezoelectric transducer 20 for transmitting and receiving the reflected ultrasonic wave X, the subject by the reflected ultrasonic wave X can be used. 3 can be easily distinguished from an image in the lateral direction of the subject 3 by the ultrasonic wave Z for horizontal measurement. Further, when the front image and the side image thus classified are displayed in different display colors upon display on the display device 10, the images can be easily identified.
[0017]
(5) Since the sound speed in the water 2 varies depending on the water temperature or the like, a more precise image can be generated by correcting the sound speed.
This correction may be performed by inputting and storing the value of the sound velocity in the water 2 into the image synthesizing device 9, but is performed based on the transmission / reception propagation time td of the reflected ultrasonic wave X from the surface of the subject 3. You can also.
Assuming that the thickness d5 of the shoe material 5, the distance L from the shoe material 5 to the surface of the subject 3, and the sound speed C5 in the shoe material 5 are known, the sound speed C2 in the water 2 is represented by the following equation ( It can be calculated by 3).
td = 2 · (d5 / C5) + 2 · (L / C2) Equation (3)
Here, the sound velocity in the water 2 is automatically corrected by extracting the surface of the subject 3 by image analysis of the synthesized image based on the characteristic of the shape of the surface of the subject 3 (for example, a plane or a curved surface). It becomes possible. Specifically, the composite image is binarized to extract the contour of the subject 3, select a point close to the piezoelectric transducer 20 from the contour, and determine the transmission / reception propagation time td corresponding to this point. Thus, the sound speed C2 in the water 2 is corrected.
[0018]
(Second embodiment)
FIG. 2 is a schematic diagram illustrating a configuration of an ultrasonic inspection apparatus according to a second embodiment of the present invention. As shown in the figure, this ultrasonic inspection apparatus uses an array sensor 6 for reception only, and additionally has an additional shoe material 45 and a transmission material that is tightly fixed to the shoe material 45 via a coupling agent 47. It has an array sensor 46.
The shoe material 45 is a solid acoustic medium having a flat plate structure fixed in the water 2 at a position sandwiching the subject 3 with respect to the shoe material 5 so as to be parallel to the surface of the shoe material 5. Similar materials can be used.
[0019]
A plurality of piezoelectric conversion elements 40 are arranged in an array on the transmission array sensor 46, and have a configuration similar to that of the array sensor 6.
The coupling agent 47 is a medium for improving the acoustic coupling state between the shoe member 45 and the array sensor 46, and can use the same material as the coupling agent 7.
[0020]
Hereinafter, the operation of the ultrasonic inspection apparatus according to the second embodiment will be described.
A specific piezoelectric conversion element 40 is selectively driven from the plurality of piezoelectric conversion elements 40 in the array sensor 46 by the transmission / reception switching device 8, and the transmitted ultrasonic wave U is transmitted from the selectively driven piezoelectric conversion element 40. The transmitted ultrasonic wave U transmits through the shoe material 45, the water 2, and the inside of the subject 3, and is further received by the array sensor 6 via the water 2 and the shoe material 5. Electric signals E generated by the plurality of piezoelectric conversion elements 20 are selectively detected by the transmission / reception switching device 8. The image synthesizing device 9 synthesizes a transmission image of the subject 3 from the detected electric signal E, and the display device 10 displays the synthesized transmission image synthesis processing result.
As a result, the inside of the subject 3 in the water 2 can be visualized while the array sensor 6 is installed outside the container 1.
[0021]
The image synthesizing process in the image synthesizing device 9 is performed based on the transmission / reception propagation time and the amplitude value of the transmitted ultrasonic wave U. If a medium different from water 2 (for example, the internal structure of the subject 3 itself or the defect 4) is present in the path of the ultrasonic wave from the piezoelectric transducer 40 for transmission to the piezoelectric transducer 20 for reception, the interface thereof (For example, the surface of the subject 3 or the defect 4 or the like), the ultrasonic waves are reflected, and the amplitude of the transmitted ultrasonic waves U received decreases. Further, the transmission and reception propagation time changes as the transmitted ultrasonic wave U passes through the inside of the medium. As described above, the transmission / reception propagation time and the amplitude value of the transmission ultrasonic wave U are calculated corresponding to the ultrasonic path (ultrasonic transmission path) from the transmission piezoelectric conversion element 40 to the reception piezoelectric conversion element 20. Thus, a transmission image of the defect 4 inside the subject 3 can be synthesized.
The calculation of the ultrasonic transmission path is performed based on the positional relationship between the transmitting piezoelectric conversion element 40 and the receiving piezoelectric conversion element 20. When calculating the ultrasonic transmission path, it is possible to calculate the ultrasonic transmission path more precisely by considering the refraction of the “interface between the shoe material 5 and the water 2” and the “interface between the shoe material 45 and the water 2”. . That is, the Snell formulas of the formulas (1) and (2) are appropriately considered.
[0022]
【The invention's effect】
According to the present invention, it is possible to provide an ultrasonic inspection apparatus capable of externally inspecting the state of a subject arranged inside a closed container without immersing a piezoelectric transducer (ultrasonic sensor) in a liquid. Become. As a result, the durability of the piezoelectric transducer is improved because the piezoelectric transducer is not immersed in the liquid.
[Brief description of the drawings]
FIG. 1 is a schematic diagram illustrating an ultrasonic inspection apparatus according to a first embodiment of the present invention.
FIG. 2 is a schematic diagram illustrating an ultrasonic inspection apparatus according to a second embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Container, 2 ... Water, 3 ... Subject, 4 ... Defect, 5, 45 ... Shoe material, 6, 46 ... Array sensor, 7, 47 ... Couprant, 8 ... Transmission / reception switching device, 9 ... Image synthesis device, DESCRIPTION OF SYMBOLS 10 ... Display apparatus, 12 ... Equidistant propagation surface, 13 ... Reflector, 15 ... Fixed jig, 20, 40 ... Piezoelectric conversion element, 21 ... Drive element switching circuit, 22 ... Signal generation part, 23 ... Signal detection circuit, 24 ... Amplifier, 25 ... A / D converter, 26 ... Calculator

Claims (6)

A piezoelectric conversion unit having a plurality of piezoelectric conversion elements,
A plate-shaped solid acoustic propagation medium acoustically connected to the piezoelectric transducer,
A drive unit that selects a piezoelectric conversion element from the piezoelectric conversion unit and generates ultrasonic waves,
Based on the reflected ultrasonic waves generated by reflecting a part of the ultrasonic wave transmitted from the piezoelectric conversion element selected by the driving unit from the subject in the liquid acoustic medium, the electric power generated from the piezoelectric conversion element of the piezoelectric conversion unit. A detection unit for detecting a signal,
Based on the electrical signal detected by the detection unit, an image generation unit that generates an image representing the internal state of the subject,
A display unit that displays the image generated by the image generation unit,
An ultrasonic inspection apparatus, comprising: The ultrasonic inspection apparatus according to claim 1, further comprising a container having an opening through which the solid acoustic propagation medium passes, accommodating the subject therein, and storing the liquid acoustic medium. . 2. The ultrasonic wave according to claim 1, further comprising a container in which the solid acoustic propagation medium and the outer surface are acoustically connected, and which accommodates the subject inside and stores the liquid acoustic medium. Inspection equipment. A sound speed that corrects the sound speed in the liquid acoustic medium based on the ultrasonic wave propagation time until the ultrasonic wave transmitted from the piezoelectric conversion unit is reflected on the surface of the subject and received by the piezoelectric conversion unit. A correction unit;
The ultrasonic inspection apparatus according to claim 1, further comprising: A reflecting unit that reflects a part of the ultrasonic wave transmitted from the piezoelectric conversion unit and irradiates the subject with the ultrasonic wave.
The ultrasonic inspection apparatus according to claim 1, further comprising: A first piezoelectric conversion unit having a plurality of piezoelectric conversion elements,
A first solid-state acoustic propagation medium acoustically connected to the piezoelectric conversion unit;
A drive unit that selects a piezoelectric conversion element from the first piezoelectric conversion unit and generates ultrasonic waves,
A second solid-state sound propagation medium disposed opposite to the first solid-state sound propagation medium;
A second piezoelectric conversion unit acoustically connected to the second solid acoustic propagation medium and having a plurality of piezoelectric conversion elements;
A detection unit that detects an electric signal generated by the second piezoelectric conversion unit;
An image generation unit that generates an image based on the electric signal detected by the detection unit,
A display unit that displays the image generated by the image generation unit,
An ultrasonic inspection apparatus, comprising:

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