JP2002040002A - Abnormal spot detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an abnormal spot detection device capable of transmitting/ receiving an elastic surface wave having minimally necessary frequency components, and detecting binary information relative to existence of an abnormal point at a time in a wide range. SOLUTION: This device is composed of a transmitter 3 for transmitting the elastic surface wave to a test object 1, a receiver 4 for receiving the elastic surface propagated through the test object, a signal generation part 5 for generating a transmission signal, a transmission part 6 for amplifying the transmission signal, and transmitting the signal to the transmitter, a reception part 7 for amplifying the signal received by the receiver, a signal processing part 8 for executing signal processing of the signal amplified by the reception part, and a determination part 9 for determining existence of the abnormal spot on the test object based on a processed result by the signal processing part. Assuming the frequency of the transmission signal as f, the depth from the test object surface to be inspected as L, and the propagation velocity of the elastic surface wave propagated through the test object as v, the signal generation part 5 is formed so as to have a function for transmitting a continuous wave comprising a single frequency component shown by f=v/L.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an abnormal location detecting apparatus for detecting an abnormal location in a device under test using surface acoustic waves. The present invention relates to an abnormal point detecting device that detects an abnormal point in a test body.

[0002]

2. Description of the Related Art Conventionally, as this kind of abnormal point detecting device, reference [1] (Miyajima et al., "A trial of ultrasonic spectroscopy in concrete inspection", Nondestructive inspection, Vo
l. 37, No. 9A, pp. 869-870, 1988).
FIG. 7 shows the configuration of the conventional abnormal point detection device shown in Document [1]. In FIG. 7, 1 is a test object, 2 is an abnormal part, 3 is a transmitter, 4 is a receiver, 13 is an ultrasonic flaw detector, 14 is a preamplifier, 14 is an A / D converter,
15 is a computer.

Next, the operation will be described. The sender 3
The transmission signal transmitted from the ultrasonic flaw detector 13 is subjected to electroacoustic conversion, and a surface acoustic wave is transmitted to the DUT 1. Receiver 4
The surface acoustic wave transmitted through the device under test 1 is received, and a receiver signal is sent to the preamplifier 14. The preamplifier 13 amplifies the receiver signal and sends it to the A / D converter 15. The A / D converter 15 A / D converts the receiver signal and converts the
6 and the computer 16 performs a Fourier transform on the received signal, and calculates an abnormal point 2 from the center frequency of the frequency spectrum.
Specify the size of At this time, since the size of the abnormal part 2 is specified from the frequency spectrum, the transmission signal is considered to be a signal having a plurality of frequency components over a certain bandwidth.

[0004] Further, as another abnormal location detecting apparatus, reference [2] (Sakata et al., "Evaluation of defect of concrete structure by response spectrum based on surface method", West Japan Society of Civil Engineers Research Conference, Vol. 1987, pp. 546-547, 198
8) is known. In Reference [2], the position and direction of the abnormal location 2 are detected from the frequency spectrum of the received signal when a sweep signal is used as the transmitted signal.
Therefore, the transmission signal contains a plurality of frequency components.

[0005]

As described above, in the conventional abnormal location detecting device, the size of the abnormal location 2
In order to specify the position and the direction, a signal having a plurality of frequency components is used as a transmission signal transmitted from the transmitter 3. However, in the soundness inspection of a large structure such as a tunnel, binary information on the presence or absence of the abnormal spot 2 in a wide range is inspected at once, rather than specifying the size, position, and direction of the abnormal spot 2. Things are required. As will be described later, when a binary inspection is performed for the presence / absence of the abnormal part 2, it is sufficient that the transmission signal includes only a single frequency component. Frequency components other than a single frequency component are meaningless frequency components. The conventional abnormal point detecting device has a problem that power consumption becomes meaninglessly large by transmitting such meaningless frequency components.

In order to perform a wide range of inspections at one time, it is necessary to increase the distance between the transmitter and the receiver. in this case,
Since the conventional abnormal point detecting device has a configuration in which the transmitting and receiving device is integrated, a long cable for connecting the transmitting and receiving unit and the transmitting and receiving elements 3 and 4 is required, and there is a problem that it takes time to set up the entire device. Further, in order to perform a wide range inspection at a time, it is necessary to transmit and receive a high power surface acoustic wave to and from the device under test 1. However, in the conventional abnormal location detecting device, the number of the transmitters 3 and the number of the receivers 4 are one each, and a surface acoustic wave with sufficient power could not be transmitted and received in a wide range of inspections.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and is capable of transmitting and receiving surface acoustic waves having a minimum necessary frequency component and detecting binary information on the presence or absence of an abnormal portion at once and in a wide range. It is an object of the present invention to provide a device capable of detecting an abnormal point.

[0008]

According to the present invention, there is provided an abnormal location detecting apparatus for transmitting a surface acoustic wave to a device under test, and receiving a surface acoustic wave propagated through the device under test. And a signal generator for generating a transmission signal, a transmitter for amplifying a transmission signal from the signal generator and transmitting the amplified signal to the transmitter, and a signal received by the receiver. A receiving unit for amplifying the signal, a signal processing unit for performing signal processing on the signal amplified by the receiving unit, and determining whether there is an abnormal portion of the DUT based on a result processed by the signal processing unit. A signal generator for determining the frequency of the transmission signal, the depth L from the surface of the device under test requiring inspection, and the propagation speed of the surface acoustic wave propagating through the device under test. v and a single frequency component of f = v / L It is characterized in transmitting a continuous wave comprising.

The signal processing section averages the received signal at regular time intervals.

[0010] In addition, the determination section sets a predetermined maximum value of the amplitude of the received signal when no abnormal portion exists in the DUT, and sets the maximum value of the amplitude of the received signal averaged by the signal processing section to A. The maximum value is B, and the presence or absence of an abnormal portion is determined from the magnitude relationship between A and B.

The signal processing unit obtains a frequency spectrum by Fourier transforming the averaged received signal, and the determining unit sets a predetermined frequency spectrum in a case where there is no abnormal portion in the device under test. The absolute value of the frequency component of the transmitted signal is C, and the absolute value of the frequency component of the transmitted signal in the frequency spectrum obtained by the signal processing unit is D, and the presence or absence of an abnormal part is determined from the magnitude relationship between C and D. It is characterized by the following.

[0012] Further, a transmitting device including the transmitting element, the signal generating section, and the transmitting section is separated from a receiving apparatus including the receiving element, the receiving section, the signal processing section, and the determining section. It is characterized by having been done.

A plurality of the transmitters are provided, where N is a positive integer, and are arranged at intervals of N / 2 of the wavelength of the surface acoustic wave at the frequency of the transmission signal along the transmission direction of the surface acoustic wave. It is characterized by having.

[0014] Further, a delay unit for delaying the transmission signal transmitted from the signal generation unit by a time corresponding to N / 2 times the cycle of the frequency of the transmission signal is further provided.

A plurality of the receivers are provided, where N is a positive integer, and are arranged at intervals of N / 2 of the wavelength of the surface acoustic wave at the frequency of the transmission signal along the transmission direction of the surface acoustic wave. It is characterized by having.

[0016] Further, a delay unit for delaying the reception signal amplified by the reception unit by a time corresponding to N / 2 times the frequency cycle of the transmission signal is further provided.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIGS. 1 and 2 show an abnormal point detection apparatus according to Embodiment 1 of the present invention.
This will be described with reference to FIG. FIG. 1 is a configuration diagram showing an abnormal point detection device according to Embodiment 1 of the present invention. Figure 1
In the above, 1 is a test object, 2 is an abnormal part of the test object 1,
3 is a transmitter for transmitting a surface acoustic wave to the device under test 1, 4 is a receiver for receiving a surface acoustic wave propagated through the device under test 1, and 5 is a single-frequency component. A signal generation unit for generating a transmission signal that is a continuous wave,
Reference numeral 6 denotes a transmitting unit for amplifying the transmission signal and transmitting the amplified signal to the transmitter 3. Reference numeral 7 denotes reception for amplifying a reception signal by the receiver 4 for receiving the surface acoustic wave propagated in the device under test 1. And 8 a signal processing unit for performing signal processing on the received signal amplified by the receiving unit 7, and 9 an abnormal part exists in the DUT 1 based on the result processed by the signal processing unit 8. It is a determination unit for determining whether to perform.

Here, the transmitter 3 is connected to the transmitter 6. The signal generator 5 includes a transmitter 6, a receiver 7,
It is connected to the signal processing unit 8 and the determination unit 9, respectively, and transmits a transmission signal or a control signal to them to control these operations. Further, the receiver 4 is connected to the receiver 7, and the receiver 7 is connected to the signal processor 8. The signal processing unit 8 is connected to the determination unit 9.

The signal generator 8 sets the frequency of the transmission signal to f, the depth from the surface of the device under test 1 requiring inspection to L, and the propagation speed of the surface acoustic wave propagating through the device under test 1 to v. It has a function of transmitting a continuous wave composed of a single frequency component shown in Expression (1). f = v / L (1)

Although the transmitter 3 is placed on the surface of the device under test 1, any device capable of transmitting a surface acoustic wave to the device under test 1 may be used. For example, the transmitter 3 may not be in direct contact with the DUT 1. FIG. 1 shows a case where the receiver 4 is in direct contact with the device under test 1. However, any device that can receive the surface acoustic wave propagating through the device under test 1 may be used.
If this object can be achieved, the receiver 4 does not have to be in direct contact with the DUT 1.

The abnormal part 2 of the test piece 1 is formed by the fact that the acoustic impedance inside the test piece 1 such as steel or concrete, such as cracks and voids, is different from the acoustic impedance of the test piece 1. Means that reflects surface acoustic waves.

The signal processing unit 8 has an averaging function for averaging the received signal at regular time intervals. The determining unit 9 sets the maximum value of the amplitude of the received signal when the abnormal part 2 does not exist in the DUT 1 to A (A is a known value set in advance), and calculates the maximum value of the averaged received signal. Let B be the maximum value of the amplitude,
A function of determining the presence or absence of an abnormal portion from the magnitude relationship between the maximum value A of the amplitude of the received signal and the maximum value B of the amplitude of the averaged received signal when the abnormal portion 2 does not exist in the DUT 1. have.

Next, the operation of the abnormal point detecting device shown in FIG. 1 will be described. First, the depth L from the surface of the device under test 1 requiring inspection and the propagation speed v of the surface acoustic wave propagating through the device under test 1 are input to the signal generator 5. Based on the signal, the signal generator 5 transmits a continuous wave of a single frequency f determined by the equation (1), and at the same time, operates the transmitter 6, the receiver 7, the signal processor 8, and the determiner 9 to operate. To send a control signal for

The transmission signal generated from the signal generator 5 is amplified in the transmitter 6 and transmitted to the transmitter 3. The transmission signal sent to the transmitter 3 is an electric signal, and the transmission signal is subjected to electroacoustic conversion by the transmitter 3 and
Is transmitted as a surface acoustic wave. The surface acoustic wave transmitted to the device under test 1 propagates through the device under test 1 and is received by the receiver 4.

The surface acoustic wave received by the receiver 4 is
The signal is converted into an electric signal, sent to the receiving unit 7 and amplified, and the amplified received signal is sent to the signal processing unit 8. The received signal sent to the signal processing unit 8 is A / D converted by an A / D conversion unit (not shown). Next, the signal is divided by a predetermined time interval by the averaging function of the signal processing unit 8 and then averaged.

By averaging the received signal by the averaging function of the signal processing unit 8, random noise such as electric noise and extraneous noise can be suppressed, and the signal-to-noise power ratio of the received signal can be reduced. The effect of improving occurs. Also, by improving the signal-to-noise power ratio of the received signal, it is possible to increase the arrangement interval between the transmitter 3 and the receiver 4 and to increase the inspection range in the direction along the surface of the device under test 1. The effect of doing so further occurs. The averaged received signal is sent to the determination unit 9.

Here, the relationship between the presence / absence of the abnormal part 2 and the amplitude of the received signal will be described. Reference [3] (SAW engineering, published by the Institute of Electronics, Information and Communication Engineers, 1983, p.4
As disclosed in 7), the surface acoustic wave propagates with most of the energy concentrated within one wavelength from the surface.

Therefore, when the wavelength of the surface acoustic wave transmitted from the transmitter 3 is equal to or less than the distance from the surface of the device under test 1 to the abnormal point 2, the surface acoustic wave is transmitted to the abnormal point 2
Is not considered to be scattered. For this reason, it is considered that the maximum value of the absolute value of the amplitude of the surface acoustic wave received by the receiver 4 is the same as the case where there is no abnormal part in the DUT 1.

On the other hand, when the wavelength of the surface acoustic wave transmitted from the transmitter 3 is longer than the distance from the surface of the device under test 1 to the abnormal location 2, the surface acoustic wave is scattered by the abnormal location 2. . For this reason, it is considered that the maximum value of the absolute value of the amplitude of the surface acoustic wave received by the receiver 4 is smaller than the case where the DUT 1 does not have the abnormal part 2.

Therefore, if the transmission signal generated by the signal generator 5 is a signal having a single frequency, an abnormal portion in a region where the depth from the surface of the DUT 1 is equal to or less than the wavelength of the surface acoustic wave to be transmitted. The presence or absence of 2 can be detected in a binary manner. From the above, it can be seen that there is an effect that the inspection range in the depth direction from the surface of the device under test 1 can be freely set by determining the frequency of the transmission signal by Expression (1).

Using the above-described relationship between the presence / absence of the abnormal part 2 and the amplitude of the received signal, the determination unit 9 performs the following operation. The determination unit 9 determines the maximum value A (set value) of the absolute value of the amplitude of the received signal and the maximum value B of the absolute value of the amplitude of the received signal when the abnormal point 2 does not exist in the DUT 1.
Compare with The maximum value A of the absolute value of the amplitude of the received signal when the abnormal point 2 does not exist in the DUT 1 is stored in a memory (not shown) in the determination unit 9 in advance.

Next, the maximum value A of the absolute value of the amplitude of the received signal when the abnormal point 2 does not exist in the DUT 1,
The presence or absence of the abnormal part 2 is determined from the magnitude relationship between the absolute value of the amplitude of the received signal and the maximum value B. In the determination of the presence or absence of the abnormal part 2, the ratio between the maximum value A of the absolute value of the amplitude of the received signal and the maximum value B of the absolute value of the amplitude of the received signal when the abnormal part 2 does not exist in the DUT 1 is determined. Is determined in advance from the result of the preliminary experiment, and if B / A is equal to or larger than the threshold S, it is determined that the abnormal part 2 does not exist. Also,
If B / A is equal to or smaller than the threshold value S, it is determined that the abnormal point 2 exists. This makes it possible to binaryly detect the presence or absence of the abnormal part 2 when a continuous wave of a single frequency is used for the transmission signal.

The determination of the presence or absence of the abnormal part 2 may be performed as follows. The signal processing unit 8 is configured to have a function of performing a Fourier transform after averaging the received signal. send.

The absolute value of the component of the frequency f of the transmission signal set in advance in the frequency spectrum when the abnormal point 2 does not exist in the DUT 1 is C, and the frequency spectrum of the reception signal obtained by the signal processing unit 8 is C. Let D be the absolute value of the component of the frequency f of the transmission signal at.

The determination unit 9 determines the absolute value C of the component of the frequency f of the transmission signal in the frequency spectrum when the abnormal part 2 does not exist in the device under test 1 and the frequency f of the transmission signal in the frequency spectrum of the reception signal. The absolute value D of the component is compared. The frequency f of the transmission signal in the frequency spectrum when there is no abnormal part 2 in the DUT 1
Although not shown, the absolute value C of the component is stored in a memory in the determination unit 9 in advance.

Next, the frequency f of the transmission signal in the frequency spectrum when the abnormal point 2 does not exist in the DUT 1
Is determined from the magnitude relationship between the absolute value C of the component and the absolute value D of the component of the frequency f of the transmission signal in the frequency spectrum of the reception signal.

In the determination of the presence or absence of the abnormal part 2, the absolute value C of the component of the frequency f of the transmission signal in the frequency spectrum when the abnormal part 2 does not exist in the DUT 1 and the transmission signal in the frequency spectrum of the reception signal Frequency f
The threshold S for the ratio of the component to the absolute value D is determined in advance from the result of the preliminary experiment, and if D / C is equal to or larger than the threshold S,
It is determined that the abnormal point 2 does not exist. If D / C is equal to or smaller than the threshold value S, it is determined that the abnormal point 2 exists.
This makes it possible to binaryly detect the presence or absence of the abnormal part 2 when a continuous wave of a single frequency is used for the transmission signal.

The abnormal point detecting device shown in FIG.
The transmitting device includes a transmitter 3, a signal generating unit 5, and a transmitting unit 6, and the receiving device includes a receiver 4, a receiving unit 7, a signal processing unit 8, and a determining unit 9. The structure may be different. FIG. 2 shows a configuration of the abnormal point detecting device when the transmitting device 11 and the receiving device 12 are separated. Although not shown in the drawing, the receiving device 12 includes switches for starting the operation of the receiver 4, the receiving unit 7, the signal processing unit 8, and the determining unit 9. As shown in FIG. 2, by separating the transmission device 11 and the reception device 12, the cable connecting the transmission unit 6 and the transmission element 3 or the cable connecting the reception unit 7 and the reception element 4 can be shortened. .

Thus, the inspection range is wide,
When the distance between the transmitter 3 and the receiver 4 is large,
This eliminates the need for a long cable equivalent to the separation distance between the transmitter 3 and the receiver 4 and simplifies the setup of the inspection and shortens the time required for the setup. Further, it also has an effect that the influence of external noise mixed from the cable can be reduced.

When a pulse signal having a plurality of frequency components is used as a transmission signal, the transmission device 11
2, a control signal for starting the operation of the receiving device 12 at the same timing as the transmitting device 11 must be sent. However, in the present invention, since a continuous wave having a single frequency is used for the transmission signal, the transmitting device 11 and the receiving device 12 do not need to start operating at the same timing. Therefore, the fact that the abnormal point detecting device can be configured as shown in FIG. 2 is an effect of using a continuous wave having a single frequency for a transmission signal.

As described above, the abnormal point detecting apparatus according to the first embodiment of the present invention uses a continuous wave having a single frequency required for inspection as a transmission signal. Therefore, unlike the conventional abnormal point detection device, the power consumption of the device can be reduced without transmitting meaningless frequency components.

Embodiment 2 An abnormal point detecting device according to a second embodiment of the present invention will be described with reference to FIGS. FIG. 3 is a configuration diagram showing an abnormal point detection device according to Embodiment 2 of the present invention. In FIG.
Reference numeral 10 denotes a delay unit for delaying the transmission signal transmitted from the signal generation unit 5, reference numeral 31 denotes an even transmitter, and reference numeral 32 denotes an odd transmitter. In FIG. 3, reference numerals 61 and 62 are the same transmission units as the transmission unit 6 shown in FIG.

The abnormal point detecting device shown in FIG.
Are provided. The plural transmitters 3 are the even transmitters 3
1 and odd transmitter 32. The plurality of transmitters 3 set N as a positive integer and set N / N of the wavelength of the surface acoustic wave at the frequency of the transmission signal along the transmission direction of the surface acoustic wave.
They are arranged at twice the interval. The even transmitters 31 and the odd transmitters 32 are arranged every other one.

Further, among the plurality of transmitters 3, the even transmitter is connected to the transmitting unit 61, and the odd transmitter is connected to the transmitting unit 62.
It is connected to the. Further, the transmission unit 62 is connected to the delay unit 10. The signal generation unit 5 is connected to the transmission unit 61, the transmission unit 62, the reception unit 7, the signal processing unit 8, the determination unit 9, and the delay unit 10, and transmits a transmission signal or a control signal thereto. Control the operation. Further, the receiver 4 is connected to the receiver 7, and the receiver 7 is connected to the signal processor 8. The signal processing unit 8 is connected to the determination unit 9.

The signal generator 8 sets the frequency of the transmission signal to f, the depth from the surface of the device under test 1 requiring inspection to L, and the propagation speed of the surface acoustic wave propagating through the device under test 1 to v, It has a function of transmitting a continuous wave composed of a single frequency component of Expression (1). Further, the signal processing unit 8 has an averaging function for averaging the received signal at regular time intervals.

The determination unit 9 sets the maximum value of the amplitude of the received signal to A (a known value set in advance) when the abnormal part 2 does not exist in the DUT 1, and Let B be the maximum value of the amplitude of the signal, and let A be the maximum value of the amplitude of the received signal and B be the averaged amplitude of the received signal when the abnormal part 2 does not exist in the DUT 1. It has a function to determine the presence or absence of an abnormal part from the magnitude relation. In addition, the delay unit 10 has a function of delaying the transmission signal transmitted from the signal generation unit 5 by a time corresponding to N / 2 times the frequency cycle of the transmission signal.

Next, the operation of the abnormal point detecting device shown in FIG. 3 will be described. First, the depth L from the surface of the DUT 1 requiring inspection and the propagation speed v of the surface acoustic wave propagating through the DUT 1 are input to the signal generator 5. The signal generating unit 5 transmits a continuous wave of a single frequency f determined by the equation (1), and simultaneously transmits the continuous wave to the transmitting unit 61, the transmitting unit 62, the receiving unit 7, the signal processing unit 8, the determining unit 9, and the delay unit 10. , Transmit control signals for them to operate.

The transmission signal generated from the signal generator 5 is amplified in the transmitter 61 and transmitted to the even transmitter 31. The transmission signal generated from the signal generation unit 5 is delayed in parallel with the transmission signal by a time corresponding to N / 2 times the frequency cycle of the transmission signal in the delay unit 10 and transmitted to the odd transmission unit 32. You. The transmission signals sent to the transmitters 3 are electric signals, are subjected to electroacoustic conversion by the transmitters 3, and transmit surface acoustic waves to the device under test 1.

Since these transmitters 3 are arranged at intervals of N / 2 times the wavelength of the surface acoustic wave at the frequency of the transmission signal, the surface acoustic waves transmitted from each transmitter 3
The components propagating along the direction in which the transmitters 3 are arranged interfere with each other in phase and reinforce each other, increasing the power of the surface acoustic wave propagating along the direction in which the transmitters 3 are arranged, thereby enabling a wider inspection. The effect occurs.

The effect will be described. Even transmitter 3
The surface acoustic wave transmitted in the direction from 1 to the odd transmitter 32 arrives at the odd receiver 32 after a time corresponding to N / 2 periods of the transmission frequency. The surface acoustic wave transmitted from the odd transmitter 32 is a signal that is delayed from the surface acoustic wave transmitted from the even transmitter 31 by a time corresponding to the N / 2 cycle of the transmission frequency. Therefore, the surface acoustic wave transmitted from the even transmitter 31 and the surface acoustic wave transmitted from the odd transmitter 32 interfere with each other in phase and reinforce each other.

When N is an even number, the delay corresponding to the N / 2 cycle is equivalent to no delay time. The generated surface acoustic wave and the surface acoustic wave transmitted from the odd transmitter 32 interfere with each other in the same phase and strengthen each other. In this case, there is an effect that the cost of the entire apparatus can be reduced by removing the delay unit 10. The value of the integer N may be appropriately determined according to the configuration of the even transmitter 31 and the odd transmitter 32, the state of the surface of the device under test 1, and the like.

The surface acoustic wave transmitted to the device under test 1 propagates through the device under test 1 and is received by the receiver 4. The surface acoustic wave received by the receiver 4 is converted into an electric signal by the receiver 4, sent to the receiver 7 and amplified, and the amplified received signal is sent to the signal processor 8.

The received signal sent to the signal processing unit 8 is A / D converted by an A / D conversion unit, though not shown.
Next, the received signal is averaged after being divided at regular time intervals by the averaging function. By performing averaging, random noise such as electric noise and extraneous noise can be suppressed, and the effect of improving the signal-to-noise power ratio of the received signal is produced. Also, by improving the signal-to-noise power ratio of the received signal, it is possible to increase the arrangement interval between the transmitter 3 and the receiver 4 and to increase the inspection range in the direction along the surface of the device under test 1. The effect of doing so further occurs. The averaged received signal is sent to the determination unit 9.

Using the above-described relationship between the presence / absence of the abnormal part 2 and the amplitude of the received signal, the determination unit 9 performs the following operation. The determination unit 9 compares the maximum value A of the absolute value of the amplitude of the received signal and the maximum value B of the absolute value of the amplitude of the received signal when the abnormal point 2 does not exist in the DUT 1. Although not shown, the maximum value A of the absolute value of the amplitude of the received signal when the abnormal point 2 does not exist in the DUT 1 is stored in advance in a memory in the determination unit 9.

Next, the maximum value A of the absolute value of the amplitude of the received signal when the abnormal point 2 does not exist in the DUT 1
The presence or absence of the abnormal part 2 is determined from the magnitude relationship between the absolute value of the amplitude of the received signal and the maximum value B.

In the determination of the presence or absence of the abnormal location 2, the maximum value A of the absolute value of the amplitude of the received signal and the maximum value B of the absolute value of the amplitude of the received signal when the abnormal location 2 does not exist in the DUT 1 are determined. Is determined in advance from the result of the preliminary experiment, and if B / A is equal to or larger than the threshold S, it is determined that the abnormal point 2 does not exist. If B / A is equal to or smaller than the threshold value S, it is determined that the abnormal point 2 exists.

The determination of the presence / absence of the abnormal part 2 may be performed as follows. The signal processing unit 8 is configured to have a function of performing a Fourier transform after averaging the received signal. Send to

The absolute value of the component of the frequency f of the transmission signal in the frequency spectrum when the abnormal point 2 does not exist in the DUT 1 is represented by C (set value), and the component of the frequency f of the transmission signal in the frequency spectrum of the reception signal Is D. The determination unit 9 determines the absolute value C of the component of the frequency f of the transmission signal in the frequency spectrum when the abnormal part 2 does not exist in the DUT 1 and the absolute value C of the component of the frequency f of the transmission signal in the frequency spectrum of the reception signal. Compare with value D. Although not shown, the absolute value C of the component of the frequency f of the transmission signal in the frequency spectrum in the case where the abnormal point 2 does not exist in the DUT 1 is stored in advance in a memory in the determination unit 9.

Next, the frequency f of the transmission signal in the frequency spectrum when there is no abnormal part 2 in the DUT 1
Is determined from the magnitude relationship between the absolute value C of the component and the absolute value D of the component of the frequency f of the transmission signal in the frequency spectrum of the reception signal. In the determination of the presence / absence of the abnormal part 2, the threshold value S relating to the ratio between the absolute value C of the component of the frequency f of the transmission signal of the frequency spectrum and the absolute value D of the component of the frequency f of the transmission signal in the frequency spectrum of the reception signal is determined. Determined in advance from the results of the preliminary experiment, D /
If C is equal to or larger than the threshold value S, it is determined that the abnormal location 2 does not exist. If D / C is equal to or smaller than the threshold value S, it is determined that the abnormal point 2 exists. This makes it possible to binaryly detect the presence or absence of the abnormal part 2 when a continuous wave of a single frequency is used for the transmission signal.

The abnormal point detecting device shown in FIG.
The transmitter 3, the signal generator 5, the transmitter 61, and the transmitter 6
2, a transmitting device including the modulating unit 10, a receiving element 4, a receiving unit 7, a signal processing unit 8, and a receiving device including the determining unit 9.

FIG. 4 shows the configuration of an abnormal point detecting device when the transmitting device 11 and the receiving device 12 are separated. Although not shown, the receiving device 12 includes a receiver 4, a receiver 7,
It has a switch for starting the operation of the signal processing unit 8 and the determination unit 9. By separating the transmitting device 11 and the receiving device 12 as shown in FIG. 4, the cable connecting the transmitting unit 61 and the transmitting unit 62 to the transmitter 3 or the cable connecting the receiving unit 7 and the receiver 4 is shortened. be able to.

As a result, the inspection range is wide,
When the distance between the transmitter 3 and the receiver 4 is large,
This eliminates the need for a long cable equivalent to the separation distance between the transmitter 3 and the receiver 4 and simplifies the setup of the inspection and shortens the time required for the setup. Further, it also has an effect that the influence of external noise mixed from the cable can be reduced.

As described above, in the abnormal point detecting device according to the second embodiment of the present invention, the transmitters 3 are arranged at intervals of N / 2 times the wavelength of the surface acoustic wave at the frequency of the transmission signal. Accordingly, the surface acoustic waves transmitted from each transmitter 3 interfere with each other in the same phase with respect to the component propagating along the direction in which the transmitters 3 are arranged, and reinforce each other. The power of the wave can be increased, and a wider inspection can be performed.

Further, since a plurality of transmitters 3 are provided and each of them is separately arranged, when the surface of the device under test 1 has irregularities, for example, reference [4] (Surface acoustic wave engineering, IEICE) Published, 1983, p. 57), the transmitter 3 can be mounted on the device under test 1 with a sufficient pressure as compared with the case of using a comb-shaped transducer as shown in FIG. Waves can be transmitted.

Embodiment 3 An abnormal point detecting device according to Embodiment 3 of the present invention will be described with reference to FIGS. FIG. 5 is a configuration diagram showing an abnormal point detection device according to Embodiment 3 of the present invention. In FIG. 5, reference numerals 101 and 102 denote the same delay units as the delay unit 10 shown in FIG. 41 is an even receiver and 42 is an odd receiver.

The abnormal point detecting device shown in FIG.
Are provided. The plural transmitters 3 are the even transmitters 3
1 and odd transmitter 32. The plurality of transmitters 3 are arranged at an interval of N / 2 times the wavelength of the surface acoustic wave at the frequency of the transmission signal along the transmission direction of the surface acoustic wave, and the even transmitter 31 and the odd transmitter 32 It is arranged every other one.

The abnormal point detecting device shown in FIG. 5 has a plurality of receivers 4. The plurality of receivers 4 are identified as even receivers 41 and odd receivers 42. The plurality of transmitters 3 are arranged at intervals of N / 2 times the wavelength of the surface acoustic wave at the frequency of the transmission signal along the transmission direction of the surface acoustic wave, and the even receiver 41 and the odd receiver 42 are arranged. Is
It is arranged every other one.

Of the plurality of transmitters 3, the even transmitter 31 is connected to the transmitting unit 61, and the odd transmitter 32 is connected to the transmitting unit 62. Further, the transmitting section 62 is connected to the delay section 101. Also, among the plurality of receivers 4, the even receiver 4
1 is connected to the receiving unit 71, and the odd receiver 72 is connected to the receiving unit 7.
2 are connected. In addition, the receiving unit 72 includes a delay unit 102
It is connected to the.

The signal generator 5 is connected to the transmitter 61, the transmitter 62, the receiver 71, the receiver 72, the signal processor 8, the determiner 9, the delay unit 101, and the delay unit 102.
A transmission signal or a control signal is transmitted to these to control these operations. The receiving section 71 and the delay section 102 are connected to the signal processing section 8. The signal processing unit 8 is connected to the determination unit 9.

The signal generator 8 sets the frequency of the transmission signal to f, the depth from the surface of the device under test 1 requiring inspection to L, and the propagation speed of the surface acoustic wave propagating through the device under test 1 to v, It has a function of transmitting a continuous wave composed of a single frequency component of Expression (1). Further, the signal processing unit 8 has an averaging function for averaging the received signal at regular time intervals.

The determining unit 9 sets the maximum value of the amplitude of the received signal when the abnormal part 2 does not exist in the DUT 1 to A (a known value set in advance), and Let B be the maximum value of the amplitude of the signal, and let A be the maximum value of the amplitude of the received signal and B be the averaged amplitude of the received signal when the abnormal part 2 does not exist in the DUT 1. It has a function to determine the presence or absence of an abnormal part from the magnitude relation.

The delay section 101 has a function of delaying the transmission signal by a time corresponding to N / 2 times the frequency cycle of the transmission signal. Further, the delay unit 102 has a function of delaying the reception signal received by the odd receiver 42 by a time corresponding to N / 2 times the frequency cycle of the transmission signal.

Next, the operation of the abnormal point detecting device shown in FIG. 5 will be described. First, the depth L from the surface of the test object requiring inspection and the propagation speed v of the surface acoustic wave propagating through the test object are input to the signal generator 5. The signal generator 5 transmits a continuous wave having a single frequency f determined by the equation (1), and simultaneously transmits the transmitter 61, the transmitter 62, and the receiver 7.
1, receiving unit 72, signal processing unit 8, determination unit 9, delay unit 10
1. A control signal for causing these to operate is transmitted to the delay unit 102.

The transmission signal generated by the signal generator 5 is amplified in the transmitter 61 and transmitted to the even transmitter 31. The transmission signal generated from the signal generation unit 5 is delayed in parallel with the transmission signal by a time corresponding to N / 2 times the frequency cycle of the transmission signal in the delay unit 101, and transmitted to the odd transmission unit 32. You. The transmission signal sent to the transmitter 3 is an electric signal, is subjected to electroacoustic conversion by the transmitter 3, and transmits a surface acoustic wave to the device under test 1.

The surface acoustic wave transmitted to the device under test 1 propagates through the device under test 1 and is received by the receiver 4. The surface acoustic wave received by the even receiver 41 is
, And is sent to the receiving unit 71 to be amplified. The surface acoustic wave received by the odd receiver 42 is converted into an electric signal by the receiver 42 and
To be amplified. Next, the amplified received signal is
N / 2 of period of frequency of transmission signal in delay section 102
It is delayed by a time corresponding to twice. The signal from the receiving unit 71 and the signal from the delay unit 102 are added and sent to the signal processing unit 8.

Since the receivers 4 are arranged at intervals of N / 2 times the wavelength of the surface acoustic wave at the frequency of the transmission signal, the surface acoustic waves received by each receiver 4
The components propagating along the direction in which the receiver 4 is arranged interfere with each other in the same phase when the signal from the receiving unit 71 and the signal from the delay unit 102 are added, and are strengthened. The reception sensitivity of the surface acoustic wave propagated along the line is increased, and an effect that enables a wider range of inspection is produced.

This effect is obtained because the transmitters 3 are arranged at intervals of N / 2 times the wavelength of the surface acoustic wave at the frequency of the transmission signal, so that the surface acoustic waves propagating along the direction in which the transmitters 3 are arranged are arranged. And the same reason.

The received signal sent to the signal processing section 8 is A / D converted by an A / D conversion section, though not shown.
Next, the received signal is averaged after being divided at regular time intervals by the averaging function. By performing averaging, random noise such as electric noise and extraneous noise can be suppressed, and the effect of improving the signal-to-noise power ratio of the received signal is produced. Also, by improving the signal-to-noise power ratio of the received signal, it is possible to increase the arrangement interval between the transmitter 3 and the receiver 4 and to increase the inspection range in the direction along the surface of the device under test 1. The effect of doing so further occurs. The averaged received signal is sent to the determination unit 9.

Using the above-described relationship between the presence / absence of the abnormal portion 2 and the amplitude of the received signal, the determination section 9 performs the following operation. The determination unit 9 compares the maximum value A of the absolute value of the amplitude of the received signal and the maximum value B of the absolute value of the amplitude of the received signal when the abnormal point 2 does not exist in the device under test 1. Although not shown, the maximum value A of the absolute value of the amplitude of the received signal when the abnormal point 2 does not exist in the DUT 1 is stored in advance in a memory in the determination unit 9.

Next, the maximum value A of the absolute value of the amplitude of the received signal when the abnormal point 2 does not exist in the DUT 1
The presence or absence of the abnormal part 2 is determined from the magnitude relationship between the absolute value of the amplitude of the received signal and the maximum value B. In the determination of the presence or absence of the abnormal part 2, the ratio between the maximum value A of the absolute value of the amplitude of the received signal and the maximum value B of the absolute value of the amplitude of the received signal when the abnormal part 2 does not exist in the DUT 1 is determined. Is determined in advance from the result of the preliminary experiment, and if B / A is equal to or larger than the threshold S, it is determined that the abnormal part 2 does not exist. Also,
If B / A is equal to or smaller than the threshold value S, it is determined that the abnormal point 2 exists.

The determination of the presence or absence of the abnormal part 2 may be performed as follows. The signal processing unit 8 is configured to have a function of performing a Fourier transform after averaging the received signal. Send to The absolute value of the component of the frequency f of the transmission signal in the frequency spectrum when the abnormal part 2 does not exist in the DUT 1 is C, and the absolute value of the component of the frequency f of the transmission signal in the frequency spectrum of the reception signal is D. .

The determination unit 9 determines the absolute value C of the component of the frequency f of the transmission signal in the frequency spectrum when the abnormal point 2 does not exist in the device under test 1 and the frequency f of the transmission signal in the frequency spectrum of the reception signal. The absolute value D of the component is compared. The frequency f of the transmission signal in the frequency spectrum when there is no abnormal part 2 in the DUT 1
Although not shown, the absolute value C of the component is stored in a memory in the determination unit 9 in advance.

Next, the frequency f of the transmission signal in the frequency spectrum when there is no abnormal part 2 in the DUT 1
Is determined from the magnitude relationship between the absolute value C of the component and the absolute value D of the component of the frequency f of the transmission signal in the frequency spectrum of the reception signal. In the determination of the presence / absence of the abnormal part 2, the threshold value S relating to the ratio between the absolute value C of the component of the frequency f of the transmission signal of the frequency spectrum and the absolute value D of the component of the frequency f of the transmission signal in the frequency spectrum of the reception signal is determined. Determined in advance from the results of the preliminary experiment, D /
If C is equal to or larger than the threshold value S, it is determined that the abnormal location 2 does not exist. If D / C is equal to or smaller than the threshold value S, it is determined that the abnormal point 2 exists. This makes it possible to binaryly detect the presence or absence of the abnormal part 2 when a continuous wave of a single frequency is used for the transmission signal.

The abnormal point detecting device shown in FIG.
The transmitter 3, the signal generator 5, the transmitter 61, and the transmitter 6
2, a transmitting device including the modulating unit 101, a receiver 4,
The receiving unit 71, the receiving unit 72, the signal processing unit 8, the determining unit 9, and the receiving device including the delay unit 102 may have a separated structure.

FIG. 6 shows the configuration of the abnormal point detecting device when the transmitting device 11 and the receiving device 12 are separated. Although not shown, the receiving device 12 includes a receiver 4, a receiver 7,
It has a switch for starting the operation of the signal processing unit 8 and the determination unit 9. By separating the transmitting device 11 and the receiving device 12 as shown in FIG. 6, a cable connecting the transmitting unit 61 and the transmitting unit 62 to the transmitting unit 3 or connecting the receiving unit 71 and the receiving unit 72 to the receiving unit 4 is connected. The cable can be shortened.

As a result, the inspection range is wide,
When the distance between the transmitter 3 and the receiver 4 is large,
This eliminates the need for a long cable equivalent to the separation distance between the transmitter 3 and the receiver 4 and simplifies the setup of the inspection and shortens the time required for the setup. Further, it also has an effect that the influence of external noise mixed from the cable can be reduced.

As described above, in the abnormal point detecting device according to the third embodiment of the present invention, the plurality of receivers 4 are arranged at intervals of N / 2 times the wavelength of the surface acoustic wave at the frequency of the transmission signal. Accordingly, for the component in which the surface acoustic wave received by each receiver 4 has propagated along the direction in which the receivers 4 are arranged, the signal from the receiver 71 and the signal from the delay unit 102 are added. At the same stage, they intensify by interfering with each other in the same phase to increase the receiving sensitivity with respect to the surface acoustic wave propagating along the arrangement direction of the receiver 4,
A more extensive inspection can be made possible.

Further, since there are a plurality of receivers 4 and these are arranged separately, when there are irregularities on the surface of the device under test 1, for example, reference [4] (Surface acoustic wave engineering, IEICE) Published in 1983, p. 57), the receiver 4 can be mounted on the DUT 1 with a sufficient pressure as compared with the case of using a comb transducer as shown in FIG. Can receive waves.

[0089]

As described above, according to the present invention, a transmitter for transmitting a surface acoustic wave to a device under test, and a transmitter for receiving a surface acoustic wave propagated through the device under test. A receiver, a signal generator for generating a transmission signal, a transmitter for amplifying a transmission signal from the signal generator and transmitting the signal to the transmitter, and amplifying a signal received by the receiver. And a signal processing unit for performing signal processing on the signal amplified by the receiving unit, and for determining the presence or absence of an abnormal portion of the device under test based on a result processed by the signal processing unit. A determination unit, the signal generation unit, the frequency of the transmission signal is f, the depth from the surface of the test object requiring inspection is L, the propagation velocity of the surface acoustic wave propagating in the test object is v, a continuous wave composed of a single frequency component of f = v / L Since the way to send and receive surface acoustic waves of the minimum frequency component,
Binary information on the presence or absence of an abnormal location can be detected at once and over a wide range.

Also, the signal processing section averages the received signal at regular time intervals, whereby
It is possible to suppress electrical noise and random noise such as extraneous noise, improve the signal-to-noise power ratio of the received signal, increase the spacing between transmitters and receivers, and reduce the noise on the surface of the device under test. It is possible to increase the inspection range in the along direction.

[0091] The determining unit sets the maximum value of the amplitude of the preset received signal to A when the abnormal part does not exist in the DUT, and sets the maximum value of the amplitude of the received signal averaged by the signal processing unit to A. By determining the maximum value as B and determining the presence or absence of an abnormal portion from the magnitude relationship between A and B, binary information on the presence or absence of an abnormal portion can be detected at once and in a wide range.

The signal processing unit obtains a frequency spectrum by Fourier-transforming the averaged received signal, and the determination unit sets a predetermined frequency spectrum in the case where no abnormal portion exists in the device under test. The absolute value of the frequency component of the transmitted signal is C, and the absolute value of the frequency component of the transmitted signal in the frequency spectrum obtained by the signal processing unit is D, and the presence or absence of an abnormal part is determined from the magnitude relationship between C and D. Thus, the presence or absence of an abnormal portion can be detected in a binary manner.

Further, a transmitting device composed of the transmitter, the signal generator, and the transmitter is separated from a receiving device composed of the receiver, the receiver, the signal processor, and the determiner. By doing so, the connection cable can be shortened, the test setup can be simplified and the time can be shortened, and external noise mixed from the cable can be reduced.

A plurality of the transmitters are provided, where N is a positive integer, and are arranged at intervals of N / 2 of the wavelength of the surface acoustic wave at the frequency of the transmission signal along the transmission direction of the surface acoustic wave. This has the effect of increasing the power of the surface acoustic wave propagating along the direction in which the transmitters are arranged, and enabling a wider range of inspection.

Further, a delay unit for delaying the transmission signal transmitted from the signal generation unit by a time corresponding to N / 2 times the frequency cycle of the transmission signal is further provided, so that a surface acoustic wave which is not delayed is provided. Has the effect of strengthening the interference in the same phase.

A plurality of the receivers are provided, where N is a positive integer, and are arranged at intervals of N / 2 of the wavelength of the surface acoustic wave at the frequency of the transmission signal along the transmission direction of the surface acoustic wave. Thus, the receiving sensitivity for the surface acoustic wave propagated along the direction in which the receivers are arranged is increased, and a wider range of inspection can be performed.

Further, by further providing a delay unit for delaying the reception signal amplified by the reception unit by a time corresponding to N / 2 times the frequency cycle of the transmission signal, it is possible to obtain the same reception signal as the reception signal without delay. This has the effect of strengthening the interference in the phase.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an abnormal point detection device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a modified example of the abnormal point detection device according to the first embodiment of the present invention.

FIG. 3 is a block diagram illustrating a configuration of an abnormal point detection device according to a second embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of a modification of the abnormal point detection device according to the second embodiment of the present invention.

FIG. 5 is a block diagram showing a configuration of an abnormal point detection device according to a third embodiment of the present invention.

FIG. 6 is a block diagram showing a configuration of a modification of the abnormal point detection device according to the third embodiment of the present invention.

FIG. 7 is a block diagram illustrating a configuration of an abnormal point detection device according to a conventional example.

[Explanation of symbols]

1 DUT, 2 abnormal spots, 3 transmitters, 31 even transmitters, 32 odd transmitters, 4 receivers, 41 even receivers, 42 odd receivers, 5 signal generators, 6 transmitters,
11 transmitting device, 12 receiving device, 61 transmitting unit, 62
Transmitter, 7 receiver, 71 receiver, 72 receiver, 8
Signal processing unit, 9 judgment unit, 10 delay unit, 101 delay unit, 102 delay unit.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Koichiro Misu 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Inside Mitsubishi Electric Corporation (72) Inventor Shuzo Wakadaka 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Corporation F-term (reference) 2G047 AA10 BC03 BC04 BC07 CB03 GA13 GB03 GF05 GF11 GG09 GG12 GG24 GG33 GG38

Claims (9)

[Claims] 1. A transmitter for transmitting a surface acoustic wave to a device under test, a receiver for receiving a surface acoustic wave propagated through the device under test, and a device for generating a transmission signal. A signal generator, a transmitter for amplifying a transmission signal from the signal generator and transmitting the signal to the transmitter, a receiver for amplifying a signal received by the receiver, and amplification by the receiver. A signal processing unit for performing signal processing on the processed signal, and a determination unit for determining the presence or absence of an abnormal portion of the device under test based on a result processed by the signal processing unit. Where f is the frequency of the transmission signal, L is the depth from the surface of the device under test requiring inspection, and v is the propagation speed of the surface acoustic wave propagating through the device under test. From the single frequency component of f = v / L Abnormal point characterized by transmitting a continuous wave Detection device. 2. The abnormal point detecting device according to claim 1, wherein the signal processing unit averages the received signal at regular time intervals. 3. The abnormal point detecting device according to claim 2, wherein the determining unit sets a predetermined maximum value of the amplitude of the received signal to A when no abnormal point is present in the device under test.
An abnormal point detection device, wherein the maximum value of the amplitude of the received signal averaged by the signal processing unit is B, and the presence or absence of an abnormal point is determined from the magnitude relationship between A and B. 4. The abnormal point detecting apparatus according to claim 2, wherein the signal processing unit obtains a frequency spectrum by performing a Fourier transform on the averaged received signal, and the determining unit determines whether the DUT has an abnormality. The absolute value of the preset frequency component of the transmission signal in the frequency spectrum when there is no location is C, and the absolute value of the frequency component of the transmission signal in the frequency spectrum obtained by the signal processing unit is D, and C and D An abnormal point detection device that determines the presence or absence of an abnormal point based on the magnitude relation of 5. The abnormal point detecting device according to claim 1, wherein the transmitting device, the signal generating unit, and the transmitting unit include a transmitting device, the receiving device, the receiving unit, An abnormal point detecting device, wherein the signal processing unit and the receiving device configured by the determining unit are separated from each other. 6. The abnormal point detecting device according to claim 1, wherein a plurality of the transmitters are provided, N is a positive integer, and a transmission signal is transmitted along a transmission direction of the surface acoustic wave. An abnormal point detecting device, which is arranged at an interval of N / 2 of a wavelength of a surface acoustic wave at a frequency. 7. The abnormal point detecting device according to claim 6, further comprising: a delay unit that delays the transmission signal transmitted from the signal generation unit by a time corresponding to N / 2 times the frequency cycle of the transmission signal. An abnormal point detection device, comprising: 8. The abnormal point detecting device according to claim 6, wherein a plurality of the receivers are provided, N is a positive integer, and a surface acoustic wave at a frequency of a transmission signal along a transmission direction of the surface acoustic wave. An abnormal point detecting device, which is arranged at an interval of N / 2 of the wavelength. 9. The abnormal point detection device according to claim 8, further comprising a delay unit for delaying the reception signal amplified by the reception unit by a time corresponding to N / 2 times the frequency cycle of the transmission signal. An abnormal point detection device characterized by the following.