JPH0684960B2 - Ultrasonic transmitting / receiving method and device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic wave transmitting / receiving method and apparatus for scanning an ultrasonic beam to detect flaws in, for example, a steel material. The present invention relates to an electronic scanning ultrasonic wave transmitting / receiving method and apparatus for scanning an ultrasonic beam with various configurations.

[Background of the Invention]

An electronic scanning ultrasonic flaw detector using an array probe excites each array element, superimposes the ultrasonic waves by timing control of transmitting and receiving ultrasonic waves, and deflects and focuses the ultrasonic beam within the subject. The method is known.
Examples of this type include "Electron scanning ultrasonic flaw detection technology and apparatus", Journal of Japan Society of Mechanical Engineers, Vol. 87, No. 793, pp. 23-28, JP-A-56-111426.

FIG. 16 shows an example of an apparatus configuration by the electronic scanning ultrasonic flaw detection method. Ultrasonic beam control circuit using arithmetic circuit
After the delay time of each array element in the delay circuit 102 is set at 101, the ultrasonic transmission circuit 103 is set through this delay circuit 102.
The pulse voltage from is applied to the array probe 106. As a result, the ultrasonic waves emitted from each array element interfere with each other to form a wavefront, and the ultrasonic waves are transmitted in a predetermined direction inside the subject 108. At this time, the ultrasonic waves are deflected in the θ direction according to the delay time set in the delay circuit 102.

Ultrasonic reflector of subject 108 (front surface 110, bottom surface 111, defect 109)
The ultrasonic wave reflected from is received by the array probe 106 and is sent to the ultrasonic wave receiving circuit 104 via the delay circuit 102. This ultrasonic reception signal is sent to the display circuit 105 after being detected and rectified by the ultrasonic reception circuit 104. The position signal of the ultrasonic beam is displayed on the display circuit 105 by the ultrasonic beam control circuit 10
It is sent separately from 1. Based on these signals, the CRT10
A surface image 112, a bottom image 113, and a defect image 114 are displayed on the screen 7.

However, in this type of example, since a delay circuit is used for the timing control of ultrasonic transmission / reception and the timing is controlled by switching the signal delay amount, the delay circuit is required for the number of array elements, and the wiring is complicated. It is also huge. A coil is usually used for this delay circuit, but it requires high-level manufacturing technology and is expensive (about 300,000 yen /
Individual). Therefore, there is a problem that it is difficult to reduce the size of the ultrasonic transmitting / receiving device and the cost is high.

[Object of the Invention]

An object of the present invention is to provide an electronic scanning ultrasonic transmission / reception method and apparatus capable of setting a beam method without using an expensive delay circuit in addition to occupying a large space and capable of displaying defects in a subject in real time. Is to provide.

[Outline of Invention]

In order to achieve the above object, the present invention selects some conversion elements at intervals according to a beam direction to be set from an array probe in which a plurality of ultrasonic electric conversion elements are arranged, and selects the selected conversion element. To transmit ultrasonic waves simultaneously, propagate the ultrasonic beam in a predetermined direction by interference between wavefronts that are shifted by one wavelength among spherical waves transmitted from adjacently selected conversion elements, and receive the reflected wave An ultrasonic transmission / reception method characterized by the above is proposed.

In order to achieve the above-mentioned object, the present invention also provides an array probe composed of a plurality of ultrasonic electric conversion elements that come into contact with a subject, and a continuous wave transmission that outputs a continuous wave to be applied to these probes. And a transmission / reception changeover switch arranged between the probe and the continuous wave oscillator to switch between transmission and reception, and arranged between the transmission / reception changeover switch and the array probe to set the beam direction to be set. Several transducers are selected from the array probe at appropriate intervals, ultrasonic waves are simultaneously transmitted to the subject from the transducers selected, and one of the spherical waves transmitted from the transducers selected adjacently is selected. Addition that captures and adds received signals from between the transmission / reception changeover switch and the transmission / reception changeover switch, and the transmission / reception changeover switch that propagates the ultrasonic beam in the specified direction due to the interference of wavefronts that are shifted by wavelength A road, an amplifier circuit for detecting amplifying summed signal, and a display unit for displaying the results, is to propose an ultrasonic transmitting and receiving apparatus comprising a switch control circuit that controls operation of the respective units.

Next, the principle of the ultrasonic transmission / reception method of the present invention will be described.

FIG. 2 shows the principle of lobe generation used in the present invention, and FIG. 3 shows the sound pressure distribution of the ultrasonic beam. Second
As shown in the figure, when each element of the array probe 9 is simultaneously emitted (the transmitting element is shown in black in the figure), a spherical wave is emitted from each element. These spherical waves interfere with each other in the front to form a wavefront. What the transmitted ultrasonic wave forms an interference band in the 0 ° direction is called a main lobe. Besides this, θ
An ultrasonic interference band is also formed in the direction. This is called a side lobe. This occurs because spherical waves with one wavelength shift interfere with each other between adjacently selected elements and form a wavefront also in the θ direction. The side-lobe generation angle θ is obtained by the following equation (1) from the triangle indicated by the diagonal lines in the figure.

Here, d is the distance between adjacent elements, and λ is the wavelength.

As can be seen from the equation (1), the deflection angle θ of the side lobe can be changed by changing the interval between the adjacent elements. The present invention utilizes side lobes to scan the ultrasonic beam by changing the distance between the transmitting elements of the array probe 9.

FIG. 3 shows the spread of the ultrasonic beam when the array probe is transmitted as shown in FIG. The sound pressure of ultrasonic waves is maximized in the direction directly below the array probe 9
There is a main lobe 14 of the next interference wave. In addition, sideways 15 of ± first-order interference waves in which the sound pressure of ultrasonic waves is maximized also exist in the ± θ directions. Generally, the sound pressure of the side lobe is lower than that of the main lobe.

Next, a method of transmitting ultrasonic waves when using the array probe will be described. FIG. 4 is a conventional ultrasonic wave transmitting method, and FIG.
The figure shows an ultrasonic wave transmission method of the present invention. Conventionally, a high-voltage spike pulse was applied to the array probe as shown in FIG. Then, from each array element, an ultrasonic wave signal having a continuous wavelength of 2 to 3 is transmitted. Therefore, ultrasonic waves do not interfere with each other between elements separated by a few elements. Since the sound pressure of the side lobe becomes low, conventionally only the use of the main lobe has been considered.

On the other hand, in the present invention, as shown in FIG. 5, a sine wave in which a predetermined number of wavefronts λ continues is transmitted. Moreover, the number n of wavelengths in the duration a of the transmitted wave is made equal to the number of array elements. With this configuration, all the ultrasonic waves emitted from each element of the array probe interfere with each other, and the sound pressure of the side lobe can be increased.

FIG. 6 is an experimental result of the sound pressure distribution of the transmitted ultrasonic wave when the pulse wave and the sine wave are transmitted. The experimental conditions are: spacing between transmitting elements 8 mm, element width 2 mm, wavelength 2.62.
mm. As is clear from this result, the sound pressure of the side lobe is higher when the sine wave of the present invention is emitted than when the conventional pulse wave is emitted, and the sound pressure is about twice as high as when the pulse wave is emitted. It becomes the size. As described above, according to the present invention, an ultrasonic beam with high sound pressure for transmitting ultrasonic waves with a sine wave can be obtained.

Example of Invention

Next, examples of the present invention will be described. FIG. 1 is a block diagram showing the configuration of an embodiment of an ultrasonic transmitting / receiving apparatus according to the present invention. In the figure, continuous wave signals P _{1 to} P ₈ are transmitted from the continuous wave oscillator 2 to the isolator 8 and the transmission / reception switching switch.
16, applied to the array probe 9 via the transmission / reception pattern switching switch 17. On the other hand, the ultrasonic signals u _{1 to} u ₈ received by the array probe 9 are input to the adder circuit 4 via the transmission / reception pattern switching switch 17. The adder circuit 4 adds the ultrasonic wave reception signals u _{1 to} u ₈ . The added ultrasonic wave reception signal u is detected and rectified by the amplifier circuit and further amplified to become the detected signal U, which is input to the display circuit 6.

The switch control circuit 3 is, for example, a microprocessor, and outputs control signals C ₁ and C ₂ for controlling on / off of the switches of the transmission / reception switching switch 16 and the transmission / reception pattern switching switch 17. Further, depending on the ON / OFF state of the transmission / reception pattern switching switch 17, the deflection angle θ of the side lobe and the position signal L of the array element in use are output to the display circuit 6. The display circuit 6 performs a process of obtaining a cross-sectional image (surface image 71, bottom image 72, defect image 73) inside the subject 10 on the CRT 7 based on the detection signal U and the position signal L. The synchronizing circuit 1 applies a synchronizing signal T to the continuous wave oscillator 2, the amplifying circuit 5, the display circuit 6, and the switch control circuit 3 to synchronize each circuit. The isolator 8 receives the ultrasonic reception signals u _{1 to} u.
_A description will be given of the flaw detection method of the present invention in which 8 is prevented from being added before being input to the adder circuit 4 by turning on the transmission / reception switching switch 16 and the transmission / reception pattern switching switch 17. For simplicity, the number of array elements is eight here. The switches 161-164 of the transmission / reception switching switch 16 are turned on, and the elements of the array probe 9 for transmitting ultrasonic waves are 91-94. Next, the intervals of the transmitting elements are selected by the transmission / reception pattern switching switches 171 to 174 so that side lobes are generated in the θ direction. Also, in the array elements 95 to 98, the intervals between the receiving elements are selected by the transmission / reception pattern switching switches 175 to 178 so that side lobes are generated in the θ direction. After that, the ultrasonic reception signals P _{1 to} P ₄ are transmitted to the array element.
It is applied to 91 to 94 to generate side lobes in the θ direction.
On the other hand, the array elements 95 to 98 receive ultrasonic waves with a reception pattern that generates side lobes in the θ direction, and
Get u _{5 to} u ₈ . In this way, side lobes are used to transmit and receive ultrasonic beams.

Of course, as is generally done, the array element may be used for both transmission and reception.

An embodiment for correcting a difference in ultrasonic wave transmission / reception sensitivity depending on the number of selected array elements will be described with reference to FIG. The switch control circuit 3 includes a switch switching circuit 31 and a sensitivity correction circuit 32. The switch switching circuit 3 is
Switching control signals C ₁ and C ₂ are sent to the transmission / reception switching switch 16 and the transmission / reception pattern switching switch 17 to control the ultrasonic transmission / reception pattern. Further, it outputs to the sensitivity correction circuit 32 an element selection signal S depending on the number of selected transmission / reception array elements. The sensitivity correction circuit 32 produces an amplitude control signal A for controlling the amplitude of the ultrasonic wave oscillation voltage from the element selection signal S and outputs it to the continuous wave oscillator 2. The continuous wave oscillator 2 includes a sine wave oscillator 22, a peak value control circuit 23, a trigger signal generator 21, an analog switch 24, and a power amplifier 25.
Composed of. The sine wave oscillator 22 generates a sine wave S ₁ which is the basis of ultrasonic wave transmission. In the crest value control circuit 23, the crest value of the sine wave S ₁ is changed according to the amplitude control signal A to obtain the signal S ₂ . The waveform of this sine wave signal S ₂ is checked by the analog switch 24 by the trigger signal K and becomes a signal S ₃ . The check signal S ₃ is amplified by the power amplifier 25 to obtain the ultrasonic wave transmission signal P.

The operation of the circuit of FIG. 7 will be described with reference to the time chart of FIG. S ₁ is the basic sine wave signal. The peak value control circuit 23 adjusts the peak value according to the number of selected array elements, and becomes the signal S ₂ . The signal K is a signal for cutting out a sine wave. Only when the signal K is 1, the analog switch 24 cuts out the signal S ₂ and outputs the check signal.
Create S ₃ . This chip signal S ₃ is amplified by the power amplifier 25 and becomes a transmission signal P. In this way, the peak value of the ultrasonic wave transmission signal is changed according to the number of elements to be transmitted / received (for example, when the number of elements is small, the peak value of the transmission signal is increased) to correct the difference in transmission / reception sensitivity and detect flaws. . This is especially effective when the number of elements is small.

The ultrasonic wave transmitting / receiving method according to the present invention will be described in detail with reference to FIG. Ultrasonic waves are transmitted into the subject 10 using the first to i-th array elements to generate side lobes 15 in the θ direction. On the other hand, ultrasonic waves are received in a reception pattern that generates side lobes 15 in the θ direction using the i + 1th to jth array elements. Next, ultrasonic waves are transmitted using the 2nd to i + 1th array elements, and ultrasonic waves are received using the i + 2nd to j + 1th array elements. Such an operation is sequentially performed up to the m-th element while shifting the transmitting and receiving array elements one by one. In this way, the subject 10 is scanned with the ultrasonic beam in the θ direction in the arrow direction. After the above operation is completed, the deviation angle θ of the side lobe 15 is changed, and the above operation is repeated. With this configuration, the inside of the subject 10 can be inspected by making the ultrasonic beam incident on the subject 10 at any angle.

The above is the embodiment in which the intervals of the transmitting elements are equal, but FIGS. 10 to 13 show an embodiment in which the intervals of the transmitting elements are made uneven. Fig. 10 shows an example in which the sound pressure of the side lobes is transmitted so that it is left-right. Also,
Figure 11 shows the sound pressure distribution obtained from the transmission. In FIG. 10, the elements of the array probe 9 are transmitted so that ultrasonic waves overlap at point P. The black-painted part is the transmitting element. ▲ ₁ ▼ ＝ a, ▲ ₂ ▼ ＝ a + λ, ▲
_3. Select B ₁ , B ₂ , and B _n of the elements so that ▼ = a + 2λ, ... ▲ _n ▼ = a + nλ and transmit. Where λ is the wavelength. Then, as shown in FIG. 11, the sound pressure of the side lobe 15 (a) becomes larger than that of the side lobe 15 (b), and the sound pressure can be increased.

FIG. 12 shows an example in which ultrasonic waves are transmitted so as to be concentrated immediately below the array probe 9. Further, FIG. 13 shows the sound pressure distribution obtained by the transmission. In FIG. 12, so that the ultrasonic waves overlap at point P, An element at a point (so-called Fresnel half-wave band) is selected to emit ultrasonic waves. Then, as shown in FIG. 13, the ultrasonic beam 15 can be focused right under the array probe 9.

Up to now, the example using the one-dimensional array probe has been described, but next, an example in which the two-dimensional array probe is used will be described with reference to FIGS. 14 and 15. FIG. 14 shows an embodiment in which a two-dimensional array probe 9 composed of M × N elements is used. In this example, flaw detection is performed with L elements as one set. That is, {911-91L},
{912 to 91 (L + 1)} …………, and {91 (N- (L
+1) to 91N} are sequentially inspected, and the inspection is moved to the next line. {921 to 92L}, {922 to 92 (L +
1)}, ..., and {92 (N- (L + 1) to 92N}) are sequentially combined for flaw detection.
ML}, {9M2 to 9M (L + 1)}, ..., and {9M (N−
Repeat from (L + 1) to 9MN}.

FIG. 15 shows an embodiment in which ultrasonic waves are focused by using the two-dimensional array probe 9. When the two-dimensional array probe 9 is transmitted in a Fresnel pattern as shown in FIG. 15, it is possible to realize an ultrasonic beam in which ultrasonic waves emitted from each element are all overlapped and focused at the point P of the subject.

〔The invention's effect〕

According to the present invention, the side lobes of the interference waves generated by the simultaneous excitation of the array probe are positively used, the element spacing is effectively changed, and the deflection angle of the side lobes is changed to scan the ultrasonic beam. Since the subject can be flaw-detected, the delay circuit and the complicated arithmetic circuit for controlling the delay circuit become defective. Therefore, the electronic scanning ultrasonic flaw detector can be downsized, and the cost of the device can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of an ultrasonic transmitting / receiving apparatus according to the present invention, FIG. 2 is a diagram showing the principle of lobe generation used in the present invention, and FIG. 3 is a sound pressure distribution of an ultrasonic beam. FIG. 4 is a diagram showing a conventional ultrasonic wave transmitting method, FIG. 5 is a diagram showing an ultrasonic wave transmitting method of the present invention, and FIG. 6 is a transmitted ultrasonic wave when transmitting with a pulse wave and a sine wave. FIG. 7 shows the sound pressure distribution, FIG. 7 shows the method of correcting the sensitivity difference by the number of array elements, and FIG. 8 shows its time chart.
FIG. 9 is a diagram showing an ultrasonic wave transmitting / receiving method according to the present invention, and FIG.
The figure shows an example in which the transmission element intervals are made uneven, FIG. 11 shows the sound pressure distribution, and FIG. 12 shows an example of transmitting ultrasonic waves by selecting an element in the Fresnel half-wavelength band. Fig. 13 shows the sound pressure distribution, Fig. 14
The figure shows an embodiment using a two-dimensional array probe, 15th
FIG. 16 is a diagram showing an embodiment in which ultrasonic waves are focused using a two-dimensional array probe, and FIG. 16 is a diagram showing an example of a conventional electronic scanning ultrasonic wave transmitting / receiving device. 1 ... Synchronous circuit, 2 ... Continuous wave oscillator, 3 ... Switch control circuit, 4 ... Adding circuit, 5 ... Amplifying circuit, 6 ... Display circuit, 7 ... CRT, 8 ... Isolator, 9 …… Array probe, 10 …… Subject, 11 …… Surface, 12 …… Bottom, 13
…… Defect, 14 …… Main lobe, 15 …… Side lobe,
16 …… Transmission / reception switching switch, 21 …… Trigger signal generator, 22 …… Sine wave oscillator, 23 …… Crest value control circuit, 24
...... Analog switch, 35 …… Power amplifier, 31 …… Switch switching circuit, 32 …… Sensitivity correction circuit, 71 …… Surface image, 72 …… Bottom image, 73 …… Defect image, 101 …… Ultrasonic beam control Circuit, 102 ... Delay circuit, 103 ... Ultrasonic wave transmitting circuit, 104 ... Ultrasonic wave receiving circuit, 105 ... Display circuit, 106 ...
… Array probe, 107 …… CRT, 108 …… Subject, 109 ……
Defect, 110 …… Surface, 111 …… Bottom, 112 …… Surface image, 113
…… Bottom image, 114 …… Defect image.

Claims (8)

[Claims] 1. A plurality of transducers are selected from an array probe having a plurality of ultrasonic electric transducers arranged at intervals according to a beam direction to be set, and ultrasonic waves are simultaneously transmitted from the selected transducers. , Ultrasonic waves characterized by propagating an ultrasonic beam in a predetermined direction by interference between wavefronts that are shifted by one wavelength among spherical waves transmitted from adjacently selected conversion elements and receiving the reflected wave How to send and receive. 2. The ultrasonic wave transmitting / receiving method according to claim 1, wherein the ultrasonic wave transmitted from the selected conversion element is a sine wave. 3. An ultrasonic wave transmitting / receiving method according to claim 1 or 2, wherein the conversion elements are selected at equal intervals. 4. The ultrasonic transmission / reception method according to claim 1 or 2, wherein the conversion elements are selected at unequal intervals. 5. The ultrasonic wave transmitting / receiving method according to claim 4, wherein a conversion element in the Fresnel half-wavelength band is selected and the beam is focused right under the array probe. 6. An array probe composed of a plurality of ultrasonic electric conversion elements in contact with a subject, a continuous wave oscillator for outputting a continuous wave to be applied to these probes, a probe and a continuous wave. It is placed between the transmitter and the transmitter / receiver selector switch that switches between transmitting and receiving, and between the transmitter / receiver selector switch and the array probe. Several transducers are selected, ultrasonic waves are simultaneously transmitted from the selected transducers to the subject, and due to interference between wavefronts that are shifted by one wavelength among the spherical waves transmitted from the transducers that are selected adjacent to each other. A transmission / reception pattern changeover switch that propagates an ultrasonic beam in a predetermined direction, an adder circuit that takes in and adds received signals from between the transmission / reception changeover switch and the transmission / reception pattern changeover switch, and the added signal is detected. An amplifier circuit for amplifying a display unit for displaying the results, the ultrasonic transmitting and receiving apparatus comprising a switch control circuit that controls operation of the respective units. 7. The continuous wave oscillator according to claim 6, wherein the continuous wave oscillator includes a peak value control circuit, the switch control circuit includes a sensitivity correction circuit, and the continuous wave output is changed according to the selected conversion element pattern. An ultrasonic transmitter / receiver characterized by correcting a sensitivity difference due to pattern change. 8. The ultrasonic transmitting / receiving apparatus according to claim 6 or 7, wherein the array probe is composed of conversion elements arranged two-dimensionally.