JPH04116457A - Ultrasonic wave visualizing apparatus and controlling method thereof and echo measuring apparatus - Google Patents

Abstract

PURPOSE:To quickly and surely adjust the apparatus and to save labor for inspection by storing the time from emission to reception of an ultrasonic wave when a peak of an echo is obtained, and automatically controlling the posture of the apparatus to a sample so as to maintain the same condition during scanning. CONSTITUTION:A pulse is generated from an ultrasonic wave transceiver part 2 in response to a command from an operating processor 10. When the ultrasonic pulse is sent to a sample 9 by an array transducer 1, an echo is generated at every discontinuous part such as a bonding surface or the like and sequentially received by the transducer 1. The received echo is detected and multiplied by the transceiver part 2 and sent to an echo measurer 3. At the start of the focus adjustment (referred to as the adjustment work), the measurer 3 detects a peak value of the echo of the connecting part at a reference point in the scanning range and the receiving time, and further detects a peak value of an echo and the receiving time during the adjustment work. The measurer 3 outputs errors and variance of these values. A mechanical coordinate control part 4 controls a Z-axis driving/detecting part 6 and a theta axis driving/ detecting part 7 of a scanner 5 so as to bring the errors and variance close to zero. Because of the adjustment work of the control part 4, the scanning focal plane is made close to the surface to be visualized.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is an ultrasonic technology that scans the joint surfaces in a laminated phase using focused ultrasonic waves and processes the echo signals to visualize the joint surfaces. The present invention relates to an ultrasound imaging device, and particularly to an ultrasound imaging device suitable for obtaining high-definition C-scope plane ultrasound images, a control method thereof, and an echo measuring device.

[Prior art] When joining two members and inspecting whether the joint surface is good or not, the joint surface is scanned with focused ultrasound and the echo signals are processed to visualize the joint surface. and examine whether there are any defects on the joint surface.

As a conventional bonding surface flaw detection method in such ultrasonic flaw detection technology, there is, for example, the method described in Japanese Patent Laid-Open No. 1-124762. In this conventional technique, the ultrasonic probe is moved in parallel along the inclination angle of the bonding surface, so that the focal point of the ultrasonic waves scans the bonding surface.

[Problems to be Solved by the Invention] In the above-mentioned prior art, since the joint surface is between large members and the periphery of the joint surface is exposed to the outside,
The angle of inclination of the joint surface with respect to the member reference plane is known in advance, and the ultrasonic probe can be moved along the angle of inclination.

However, in solder joints, etc., the process of melting and solidification occurs, so it becomes impossible to know the angle of inclination of the joint surface with respect to the component reference plane. Further, even when an IC is sealed within a package, parallelism between the package surface and the internal IC is not compensated for.

In other words, since the IC cannot be seen from the outside, the condition of the bonding surface between the IC and the package material cannot be determined.

When using an ultrasonic imaging device to obtain an image of the bonded surface in such a state, it is necessary to align the focus of the ultrasonic waves with the bonded surface, and it is also necessary to scan the focus along the bonded surface. However, since it is not possible to observe the condition of the bonded surface from the outside, conventionally an expert has to observe the amplitude of the echo from the sample and the time from ultrasonic irradiation to echo reception using an oscilloscope, etc. The height and tilt of the probe and sample stage had to be adjusted.

This adjustment is difficult because the speed of sound in the liquid medium in which the sample is immersed and the sample material are different, so it is difficult to linearly control it using only the echoes from the front (back) of the sample and align the focal plane with the bonding surface. , there is a problem in that it requires an extremely high level of skill and is difficult to automate because it can only be done by experts.

An object of the present invention is to provide an ultrasonic imaging apparatus, a control method thereof, and an echo measuring device that can automatically scan the inside of a sample and obtain a high-definition C-scope plane ultrasonic image.

[Means for Solving the Problems] The above object is to scan a surface to be inspected in a sample with focused ultrasonic waves from the ultrasonic transmitting/receiving means, and during this scanning, received signal information from the surface to be inspected is transmitted to the scanning surface. This is achieved by automatically controlling the attitude of the ultrasonic transmitting/receiving means with respect to the sample in a direction that eliminates this deviation when a deviation between the surface and the surface to be inspected is detected.

More specifically, the time from ultrasonic transmission to reception when an echo peak is obtained is memorized, and when a sample is scanned with ultrasonic waves, the time until reception of the echo peak is used as the memorized time during scanning. The attitude of the ultrasonic transmitting/receiving means with respect to the sample is automatically controlled so that they are the same.

[Operation] When the scanning surface deviates from the surface to be inspected, the waveform of the echo from the surface to be inspected changes. Therefore, by automatically controlling the attitude of the ultrasonic transmitting/receiving means with respect to the sample so that there is no change in this waveform, the scanning plane matches the surface to be inspected, and by processing the received signal of the ultrasonic transmitting/receiving means, It becomes possible to obtain a good image of the surface.

[Example] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

In the first embodiment of the present invention, a storage device that stores the waveform of an echo from a sample as a reference waveform in advance, and an ultrasonic transducer made of an ultrasonic transducer scan an ultrasonic beam transmitted and received. A peak time detector that calculates the correlation function between the reflected echo and its reference waveform and detects the time when the envelope peaks as a relative time difference with the reference waveform, and the distance and inclination between the ultrasonic beam scanning surface and the sample. The system detects the reception times of echoes in the order in which they are received, and adjusts and controls the focal scanning plane of the focused ultrasound beam so that the reception times of the echoes in the preset order are constant. Adjust the distance and inclination between the surface of the sample and the surface to be visualized.
It is something to control.

In FIG. 1, a pulse signal is generated from an ultrasonic transmitting/receiving section 2 having a pulse generator according to a command from an arithmetic control section 10, and an ultrasonic pulse is transmitted from an array transducer 1, which is an ultrasonic transducer.

This ultrasonic pulse progresses while being focused in the liquid medium (for example, water or methyl alcohol) in the water tank 8, and
reach the surface of. Generally, the speed of sound in a sample is different from the speed of sound in a liquid medium, so the shape of the ultrasound beam also changes due to refraction. Some of the ultrasound waves are reflected from the surface of the sample 9 and return to the transducer 1 as surface echoes. The rest is sample 9
It propagates inside and generates echoes at each discontinuity such as the joint surface,
are received by the transducer 1 in sequence. The received echo is received and amplified by the ultrasonic transmitter/receiver 2 and sent to the echo measuring device 3.

At the beginning of the focusing work (hereinafter referred to as adjustment work), the echo measuring device 3 detects the peak value of the junction echo and its reception time at a reference point within the scanning range, and during the subsequent adjustment work, Similarly, the peak values of junction echoes and their reception times at points within the scanning range are detected, and their errors and variations are output.

The mechanical coordinate control unit 4, which serves as both a basic axis control device and a scanning control device, adjusts the Z@ drive detection unit 6 and O-axis drive of the scanner 5 so that the peak values approach zero based on the peak value and its reception time. It controls the detection unit 7 and performs adjustment work. At this time, by controlling to minimize the variation, the scanning focal plane and the imaging target surface can be brought as close as possible overall, even if there is a warp on the bonded surface or the scanning focal plane is not a perfect plane. be able to.

Details of the echo measuring device 3 are shown in FIG. 2, and the amplified echo waveform is stored in a wave memory 31 which is a storage device.
recorded in An example of the recorded echo waveform is shown in FIG. At the beginning or before the adjustment work, only one typical echo waveform is cut out as a gate waveform according to a command from the arithmetic and control unit 10, and is stored in the reference waveform memory 32 as a reference wave.

Adjustment work begins, and echo signals recorded in the same way are used as the second
The waveform correlation calculation unit 33 shown in the figure performs a correlation calculation with the reference wave and outputs it as a correlation waveform. The center frequency of the correlation waveform is almost double the center frequency of the original echo waveform, so
The envelope is extracted by passing it through a filter with a cutoff frequency at the center frequency of the original echo. After performing these operations, the correlation peak time detection unit 34, which corresponds to the peak time detector, detects the peak value pj of the envelope, and uses the time t1 indicating the peak as a reference waveform by the time step of the correlation calculation. The relative time difference between the two echoes is calculated, and both are output together with the number 1 representing the order in which the echoes were received. After capturing the reference wave, the reference time memory 35 stores the peak time trj- of the reflected wave (i-th echo) from the imaging target surface at a scanning reference point, for example, the center of the scanning range.
and its peak values pri and i are stored. During adjustment work, the time deviation detection unit 36 detects tyu and pi at points within the scanning range other than the reference point, and tri and Pri at the reference point.
and outputs the difference dti=tj-trj and dPi=pi-Pri. Since the order of discontinuities across the ultrasound beam corresponds to i, the deviation between the scanning focal plane and the imaging target surface is determined by specifying the order corresponding to the imaging target surface.

Here, in order to reconfirm the problem to be solved, the relationship between the scanning focal plane and the imaging target plane will be explained with reference to FIG.

When the transducer is scanned in the XY direction, the surface formed by the trajectory of the acoustic radiation surface is the transducer scanning surface 11. A scanning focal plane 12 is a plane formed by the focal point of the ultrasonic beam 14 emitted and detected by the transducer 1 as it scans. These two sides have points on them one to one with each other.
Therefore, the flatness of this surface 12 is determined depending on the accuracy of the scanner 5.

On the other hand, the joint surface 13 inside the sample 9, which is the surface to be visualized, is
It is fixed by the top surface 81 of the sample stage, such as the bottom surface of the water tank 8 in FIG. 1, and its surface accuracy is determined by the precision between the surface 81 and the external dimensions of the sample. That is, focusing here refers to the work of aligning the surface 12 and the surface 13, and the scanner 5. Due to the accuracy of the 8° water tank and sample 9, the two sides generally do not match.

The problem to be solved in the embodiment is to make this match. The basic procedure for reducing both sides to -m is: first, the peak value takes the maximum value at the center of the scanning plane, and then the peak time is constant over the front of the scanning range, that is, the peak value at that time is The point is to control so that the variation is minimized.

FIG. 5 is a flowchart showing the procedure of focusing work, which is adjustment work. First, after storing the reference wave in the reference waveform memory 32, adjust Z so that the peak value pi of the surface echo is maximized at the reference point in the center of the scanning range, and focus on the surface (Step Co.) . At this time, pi can be controlled to be maximized by comparing the change in pi for each small step of Z and driving in the same direction while it increases, and in the opposite direction when it decreases. . Next, 0 is adjusted so that ti does not differ from the reference point within the range in which surface echoes are detected within the scanning range, and the difference dti becomes zero (step 2). and,
Adjust Z so that eco is maximized again (Step 3
). In the next step 4, it is determined whether the changes dz and dθ in Z and θ in the steps 2 and 3 are smaller than the preset error E, and if smaller, the next step (step 5) is performed. If it is large, return to step 2. At the end of this step, the scanning focal plane coincides with the sample surface.

In step 5, for the bonded interface echo, which is the surface to be visualized, repeat the same operation that was performed on the surface first, control Z at the reference point, and match the focus at the reference point to the surface to be visualized. let In the next step 6 to step 8, the same operations as steps 2 to 4 are sequentially performed for the cemented surface echo. This causes the scanning focal plane to coincide with the bonding interface in the final step 9.

In this embodiment, coarse adjustment can be made using surface echoes and fine adjustment can be made using cemented surface echoes, so that the adjustment work can be performed reliably. Furthermore, X
Convergence can be accelerated by finding the regression plane that minimizes the root mean square of dz at the sample point on the Y scanning plane and adjusting the scanning focal plane to it while taking into account changes in focal length due to refractive index. It is possible. These adjustment procedures are controlled by the calculation control section 10.

In order to control the array transducer and scan the ultrasonic beam for imaging, a circuit having a configuration as shown in FIG. 6, for example, can be used. Ultrasonic waves are transmitted from the array transducer 1, which is an ultrasonic transducer, at a timing determined by the transmission timing signal generator 21 in response to a command from the arithmetic control unit 1o. At each timing, a matrix switch circuit 24, which is a connection switch, connects each simultaneously driven vibration element determined by the electronic scanning control section 22 and each channel of the multichannel pulse generator 23. Each channel of the pulse generator 23 drives each simultaneously driven element of the array transducer 1 at a timing according to a delay time for focusing the ultrasound beam, and generates an ultrasound pulse toward the sample. The echo that came back from the sample was
It is received by the same array transducer 1 and converted into an electrical signal. At this time, the matrix switch 24 connects each simultaneously driven element 1 and each channel of the multi-channel receiver 25, and the received echoes are subjected to phase correction in the receiver 25 according to the delay time. The signals are amplified, combined, and output to the echo measuring device 3 and the video device 26. The video device 26 processes the output signal of the receiver 25 with an image processing section 26a and displays it on a CRT 26b. Here, the arithmetic control section 10 commands the operation of each section, selects the simultaneously driven elements of the array, and sets the delay time given to each channel. As described above, according to the first embodiment, highly accurate focusing is possible.

FIG. 7 shows another embodiment of the present invention for realizing an echo measuring device. In this embodiment, the echo waveform received by the ultrasonic transmitter/receiver 2 is first transmitted to the gate circuit 371.
By extracting only the echoes at the time when the echoes are received from the surface to be roughly visualized, a phase shifter 37 creates a waveform with a phase difference corresponding to 1/4 of the wavelength determined by the center frequency, and then squares them. Adder 391
In addition, the harmonic frequency components are removed by a low-pass filter 392 whose cutoff frequency is close to the center frequency of the echo.
The peak time detector 34 detects and outputs the peak value pi and the reception time tj.

The arithmetic control unit 10 in FIG. 1 statistically processes them to match the scanning focal plane and the imaging target plane. According to this embodiment, the configuration is simplified and the processing speed is increased.

In the embodiments described above, the scanning of the ultrasonic beam has been explained assuming electronic scanning by an array transducer. In this case, the effect of reducing the adjustment work time is remarkable, but it is not limited to this condition, and it can also be applied when mechanically scanning a single focusing probe, and precision scanning at a finer pitch can be achieved. Adjustments can be expected.

In addition, in the second embodiment, the coordinate axis for adjusting the distance between the scanning focal plane and the imaging target surface of the sample was represented by Z, and the coordinate axis for adjusting the inclination between both surfaces was represented by the θ axis. In addition, one axis (for example, the φ axis) can be taken in addition to the direction perpendicular to the plane of the paper in FIG. 1, and it may be possible to adjust not only the left and right sides of the scanning plane but also the front and back inclination. Similarly, Z is not limited to one axis. On the other hand, the inclination of the imaging target surface can also be adjusted by providing a mechanism for this purpose, for example, an actuator that adjusts the height for each support point with three-point support, which has the effect of allowing adjustment over a wider range.

〔Effect of the invention〕

According to the present invention, adjustment to match the scanning focal plane and the imaging target plane can be quickly and reliably performed, making it possible to save labor and time in high-speed, high-resolution inspection.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of main parts of an ultrasound imaging device according to the embodiment of the present invention, FIG. 2 is a detailed configuration diagram of the echo measuring device shown in FIG. 1, and FIG. 4 is a diagram showing the concept of focus adjustment, which is a problem of the present invention; FIG. 5 is a flowchart showing the procedure of focus adjustment, which is a problem of the present invention; 6. This figure is a block diagram of the ultrasonic transmitter/receiver section shown in FIG. 1 when using an array I transceiver, and FIG. 7 is a diagram showing the structure of another embodiment of the present invention regarding an echo measuring device. Array 1 - Lancer, 2... Ultrasonic transmitter/receiver 3...
-Echo measuring device, 32...Reference waveform memory, -Waveform correlation calculation unit, 34 -Peak time detection unit, time deviation detection unit, 4...Mechanical coordinate control 9...Sample. 1. Sozu, Department, Representative Patent Attorney Masaaki Akimoto Real Number 1 Simplified Diagram L-Itaichi

Claims (1)

[Scope of Claims] 1. In an ultrasonic imaging device that receives echoes of ultrasonic waves sent to a sample from an ultrasonic transmitter/receiver and processes the received signals into image signals, the ultrasonic wave when the echo peak is obtained is The time from sending out sonic waves to receiving them is memorized, and when scanning a sample with ultrasonic waves, the attitude of the ultrasonic transmitting/receiving means with respect to the sample is automatically adjusted so that the time until reception of the echo peak is the same as the memorized time during scanning. An ultrasonic imaging device characterized in that it is provided with attitude control means for controlling. 2. In an ultrasonic imaging device that receives echoes of ultrasonic waves sent to a sample from an ultrasonic transmitting/receiving means, processes the received signals, and converts them into image signals, the process from transmitting ultrasonic waves to receiving them when the peak of the echo is obtained is The method is characterized in that the time is memorized and the attitude of the ultrasonic transmitting/receiving means with respect to the sample is automatically controlled so that when the sample is scanned with ultrasonic waves, the time until reception of the echo peak is the same as the memorized time during scanning. A method for controlling an ultrasound imaging device. 3. In an ultrasonic imaging device that receives echoes of ultrasonic waves sent to a sample from an ultrasonic transmitting/receiving means, converts the received signal into a video signal, and displays it on a display device, the surface to be inspected in the sample is exposed to the ultrasonic waves. A scanning means that scans with focused ultrasound from a transmitting/receiving means, and when received signal information from the surface to be inspected detects a deviation between the scanning surface and the surface to be inspected during this scanning, the ultrasonic transmitting/receiving means moves in a direction to eliminate this deviation. 1. An ultrasonic imaging apparatus comprising: attitude control means for automatically controlling the attitude of the means with respect to a sample. 4. In an ultrasonic imaging device that receives echoes of ultrasonic waves sent to a sample from an ultrasonic transmitting/receiving means, converts the received signal into a video signal, and displays it on a display device, the surface to be inspected in the sample is exposed to the ultrasonic waves. When scanning with focused ultrasonic waves from the transmitting/receiving means, when received signal information from the surface to be inspected detects a deviation between the scanning surface and the surface to be inspected during this scanning, the ultrasonic transmitting/receiving means moves in a direction to eliminate this deviation. A method for controlling an ultrasonic imaging device, characterized by automatically controlling its posture with respect to a sample. 5. Ultrasonic transmitting/receiving means consisting of a one-dimensional array of vibrating elements that focuses and transmits ultrasonic waves to the sample, receives echoes from the sample, and converts them into electrical signals, and electronically scans the vibrating element group. an ultrasonic device comprising: a scanning means for scanning an ultrasonic beam focused on a bonded surface in a sample; and a display means for processing a received signal of the ultrasonic transmitting/receiving means to convert it into a video signal and displaying an image of the bonded surface. In the imaging device, there is provided a storage means for measuring and storing the time from sending out the ultrasonic waves to receiving the echo peak from the bonding surface, and a storage means for measuring and storing the time from sending out the ultrasonic waves to receiving the echo peak from the bonding surface, and a storage device for measuring and storing the time from sending out the ultrasonic wave to receiving the echo peak from the bonding surface; and means for automatically controlling the attitude of the ultrasonic transmitting/receiving means with respect to the sample so that the time from transmitting the ultrasonic waves to receiving the echo peak is constant with the storage time of the storage means. Imaging device. 6. Ultrasonic transmitting/receiving means consisting of a one-dimensional array of vibrating elements that focuses and transmits ultrasonic waves to the sample, receives echoes from the sample, and converts them into electrical signals, and electronically scans the vibrating element group. an ultrasonic device comprising: a scanning means for scanning an ultrasonic beam focused on a bonded surface in a sample; and a display means for processing a received signal of the ultrasonic transmitting/receiving means to convert it into a video signal and displaying an image of the bonded surface. In the imaging device, the time from transmitting the ultrasonic waves to receiving the echo peak from the bonded surface is measured and memorized, and when the echo peak from the bonded surface reaches its maximum during the electronic scanning, the ultrasonic wave A method for controlling an ultrasound imaging apparatus, comprising automatically controlling the attitude of the ultrasound transmitting/receiving means with respect to the sample so that the time from transmission to reception of the echo peak is the same as the stored time. 7. In an ultrasonic imaging device that receives echoes of ultrasonic waves sent to a sample from an ultrasonic transmitting/receiving means, processes the received signals, and converts them into image signals. When scanning a sample with ultrasonic waves by memorizing the time, the distance between the ultrasonic transmitting/receiving means for the sample and the surface to be visualized is set so that the variation in the time to receive an echo peak with respect to the memorized time is minimized during scanning. An ultrasonic imaging device characterized by being provided with a control means for automatic control. 8. In an ultrasonic imaging device that receives echoes of ultrasonic waves sent to a sample from an ultrasonic transmitting/receiving means, processes the received signals, and converts them into image signals. When scanning a sample with ultrasonic waves by memorizing the time, the distance between the ultrasonic transmitting/receiving means for the sample and the surface to be visualized is set so that the variation in the time to receive an echo peak with respect to the memorized time is minimized during scanning. A method of controlling an ultrasonic imaging device characterized by automatic control. 9. An echo measuring device installed in an ultrasonic imaging device equipped with a control mechanism for controlling the relative position, distance, and attitude between the ultrasonic transmitting/receiving means and the sample, which measures the echo of ultrasonic waves sent to a reference point of the sample. means for determining a deviation between a first time until reception and a second time until receiving an echo when scanning a sample with ultrasound and outputting a signal corresponding to the deviation as a control signal; An echo measuring device characterized in that the ultrasonic scanning surface is made to coincide with the surface to be inspected by controlling the control mechanism.