JP2002303612A - Method and device for correcting delay time of ultrasonic test equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and device by which the drop of the focusing accuracy of an electronic scanner can be corrected at every element in order to solve the problem that no method is available for measuring the time difference between elements with accuracy and, accordingly, it is difficult to improve accuracy when an ultrasonic wave is focused by means of the electronic scanner. SOLUTION: Ultrasonic test equipment which detects flaws from an array probe composed of a plurality of elements by means of the electronic scanner transmits driving signals to the elements, and receives the signals correspondingly to the elements by means of a probe for calibration through a test piece for calibration. Then the equipment matches the transmission by means of the elements to each other by correcting and setting the delay times of other elements on the basis of the element from which the probe receives the signals with the maximum delay time so that the delay times of all elements may become the same.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic scanning flaw detector capable of focusing an ultrasonic wave at an arbitrary position inside an object to be inspected. The present invention particularly relates to a method and an apparatus for correcting a delay time of an ultrasonic flaw detector which corrects a delay error and a sensitivity variation including a transmission / reception circuit by transmission / reception for each element using an array probe.

[0002]

2. Description of the Related Art When transmitting and receiving an ultrasonic drive signal by a plurality of elements, an electronic scan which enables the ultrasonic waves to be focused at an arbitrary position inside a test object by giving a phase difference to each element. There is a device. In this case, a method of detecting and correcting a time lag between received signals from a plurality of elements in an ultrasonic flaw detector using an array probe is disclosed in Japanese Patent Application Laid-Open No. 6-3093.
No. 1 publication. Control data for determining the delay time is stored in the storage means, correction data for correcting the control data is stored, and the transmission and reception delay times are determined based on the data obtained by adding both data.

[0003] Also, there is Japanese Patent Application Laid-Open No. 4-22848. The description is based on calculating a cross-correlation function for each of a pair of input received signals, a received signal from a predetermined oscillator, and an oscillator sequentially selected from a position closer to and farther from the predetermined oscillator. And a correlation function is determined using the received signals of the pair as a pair. Then, the delay time is corrected using this.

[0004] Also, there is Japanese Patent Application Laid-Open No. 3-268746. Here, a case where a fixed delay element group and a variable delay element group are used is described. An evaluation circuit that evaluates the quality of the correction by the variable delay element group is selected, and one of the fixed delay element groups is selected, and the pseudo reception signal from the pseudo reception signal generation circuit is simultaneously variable before and after the fixed delay element group. It is configured to be applied via a delay element, and the output signal of the delay circuit at that time is evaluated by the evaluation circuit to determine a correction amount.

With reference to FIG. 6, basic matters and problems regarding the electronic scanning according to the present invention will be described. FIG. 6A shows a case where there is no delay time for the drive signal. In this case, a drive signal (transmission signal) is given to the vibrator without a delay time (or a delay time due to a lead wire alone and no time delay element is added).
Where the wavefront is formed as shown. On the other hand, in the case of FIG. 6B, a delay time is provided for each element. When the delay time is set for the seven elements in FIG. 6, the wavefront is configured as shown in the figure. These are the characteristics of each element,
Especially when there is no variation in the delay time. Correction is important in the wavefront configuration because element variations actually exist.

In electronic scanning, a plurality of transducers are simultaneously driven to generate an ultrasonic beam. In this case, the shape of the wavefront is better if there is no variation among the elements. It is one of the objects of the present invention to correct the variation of these elements, but the desired delay time must be set accurately. Usually, a method of winding an electric wire in a coil shape to delay the transmission of an electric signal to give a time delay has been attempted. However, there is also variation in the time delay elements.

[0007]

In the conventional ultrasonic flaw detector, it is possible to optimize an ultrasonic beam formed by a plurality of ultrasonic transducer elements. However, in the measurement and correction of the variation between a plurality of elements of the apparatus and the array probe, the delay time calculated by calculation or electrical measurement is corrected by setting by a program or the like. In this method, there is a problem that accuracy in matching phases by a plurality of elements of the array probe is reduced, and that it takes time to adjust. Further, even if a desired delay time is set, there is variation in delay elements. In addition, there is a problem that the conventional method cannot cope with a change in the delay time characteristic over time including an array probe.

It is an object of the present invention to include variations in elements in an electronic scanning apparatus, deviations in delay times of electric circuits, delay times due to physical gaps between elements of an array probe, and variations in delay elements themselves. It is an object of the present invention to provide a method and an apparatus for correcting a delay time of an electronic scanning flaw detector capable of performing measurement and correction to maintain stable characteristics for a long period of time.

[0009]

According to the present invention, the delay time can be corrected by the following method and apparatus. An ultrasonic flaw detector having an array probe composed of elements that are a plurality of ultrasonic transducers, transmitting a drive signal to each of the plurality of elements, and calibrating a test piece corresponding to each of the elements. Received by the calibration probe through the, the delay time with respect to the other elements to the same time delay with reference to the element showing the maximum delay of the received signal at the probe, and set the correction, the element It is characterized in that matching between elements in the transmission of the data is performed.

In addition to the correction of the delay time of the transmission signal, a driving signal is transmitted from the calibration probe to each of the plurality of elements, and the transmission signal from the calibration probe is transmitted to each of the elements. , The reception delay time for the other elements is corrected and set so that the same time delay is obtained based on the element showing the maximum delay of the reception signal,
Matching between elements in receiving the plurality of elements. The position of the calibration probe corresponding to the element is obtained by a signal of an encoder connected to the calibration probe. It is characterized in that the time delay matching setting is performed by using a virtual address to specify a read address, and to correct variation between elements or variation in set delay time.

A transmission circuit for transmitting a drive signal to each of the plurality of elements, one calibration probe for receiving the transmission signal via a calibration test piece corresponding to each of the elements, A waveform storage memory for storing a received signal, a correction amount calculation circuit for calculating a transmission delay time correction amount for another element so as to have the same time delay based on the element showing the maximum delay from the signal of the waveform storage memory; And a delay control circuit for applying the calculated correction amount to each transmission signal.

In addition to the correction of the transmission signal, a receiving circuit for receiving a transmission signal from the calibration probe for each of the plurality of elements, and a calibration test piece corresponding to each of the elements And a waveform storage memory for storing a waveform of the transmission signal received via the CPU, and a delay time with respect to the other elements is calculated so as to have the same time delay based on the element showing the maximum delay from the signal of the waveform storage memory. A correction amount calculation circuit, a delay control circuit that corrects the calculated correction amount for each received signal,
It is characterized by having the following.

A transmission circuit including a transmission delay circuit for delaying a drive signal for each element of the array probe; a reception circuit including a delay memory for storing a signal received by the array probe; A waveform storage memory for receiving a transmission signal from a slave and storing a waveform together with the transmission signal; a correction amount calculation circuit of a reception circuit for achieving matching based on an element indicating a maximum delay time; and a drive from the transmission circuit. The waveform storage memory for receiving and storing a signal with the calibration probe, and the correction amount for calculating a correction amount of a transmission circuit for matching with another element based on an element indicating a maximum delay time An arithmetic circuit and delay time correction setting are respectively performed based on the calculated correction amount of the transmission circuit and the calculated correction amount of the reception circuit. Shin delay circuit and the delay memory, it is characterized in that it comprises a.

[0014]

Embodiments of the present invention will be described below. 1 shows a block diagram according to the present invention, FIG. 2 shows a method of using a delay memory, and FIG. 3 shows an example of a calibration method.

First, the overall configuration will be described with reference to FIG. FIG. 1 is a block diagram schematically showing an electronic scanning device and an array probe 19 driven by the electronic scanning device and a case where the array probe 19 is calibrated. 3 is a transmission circuit, and 12 is a reception circuit. A drive signal of the ultrasonic transducer is transmitted from the transmission circuit 3,
The receiving circuit 12 receives an echo signal from the flaw detection object.

Reference numeral 1 denotes a transmission delay circuit, and reference numeral 2 denotes a transmission switching circuit, which can be used to select and use elements. 5T is an amplifier circuit for transmission. The reception signals from the N array probes 19 are processed by the reception circuit 12.
The receiving circuit 12 is composed of the following circuits. Reference numeral 4 denotes a reception signal switching circuit (including selection use as in the case of the above transmission), and its output signal is amplified by an amplification circuit 5R.
After being converted by the / D converter 6, it is stored in the delay memory 7, and when read out, it becomes a signal in which the variation of the receiving circuit including the element has been corrected. The output is added by the adder circuit 8 during normal measurement.

The calibration portion includes a calibration test piece 22 and a calibration probe 14, and the calibration array probe 1
It comprises an encoder 13 for detecting a transmission / reception positional relationship between the calibration probe 9 and the calibration probe 14. Specifically, as shown in FIG. 3, a corresponding element is specified via the test piece 22 from the distance between the calibration probe 14 and the encoder 13 for detecting the transmission / reception positional relationship, and calibration is performed. The electronic scanning apparatus can transmit and receive N elements (20 to 21) of the array probe 19 individually or simultaneously to a plurality of elements.
The transmission and reception signals can be given a delay time for each element individually by the delay control circuit 10.

The received signals from the N elements are amplified by an amplifier circuit 5R, converted into digital signals by an A / D converter 6, and stored in a delay memory 7. There, the data is written and stored at an address position corresponding to the delay time corresponding to each of the N elements. Then, this can be read out by the address control and combined into one signal by the adding circuit 8.

Further, the use of the calibration probe 14 enables transmission and reception of ultrasonic signals. The received signals are converted into digital signals by the A / D converter 18 and stored in the waveform storage memory 9. . Reference numeral 16 denotes a calibration probe reception circuit, and reference numeral 15 denotes a calibration probe transmission circuit. Further, an encoder 13 for measuring the position of the calibration probe 14 is connected, and the position of the calibration probe 14 corresponding to each element can be specified from the distance. The position signal 17 is transmitted to the array probe 19 or the calibration probe 14.
Is stored in the waveform storage memory 9 in the same manner as the received signal.

The calibration probe 14 has the same flaw detection frequency as the frequency of the array probe 19, and is connected to the encoder 13. The encoder 13 can detect and measure the position of the calibration probe 14 when the calibration probe 14 moves through a range of N elements of the array probe 19 via the calibration test piece 22.

FIG. 2 is an explanatory diagram in the case where a correction amount of the delay time is set in order to match the delay time for each element. The correction amount calculated from the delay control circuit 10 is set using the virtual address. FIG. 2A shows a case where the delay time is zero, that is, a case where the write address and the read address are the same address (address 0). FIG. 2B shows a case where the set delay time is 1, that is, the delay time is 1 in virtual address units. The address to be written is virtual address 1 and the read address is address 0. FIG. 2C shows the case of the delay time N, where the write address is the virtual address N and the read address is the address 0.

Therefore, when these signals 23 are read out, a signal waveform having a corrected delay time is obtained as shown by a signal 24. In this way, it is possible to use the apparatus without any variation in the delay time during the actual measurement. Of course, for each element, FIG.
In order to form such a wavefront, matching can be achieved in a similar manner even when a delay time is set. That is, it can be realized by determining a virtual address as a variation including a set time delay.

Here, the calibration of the receiving circuit 12 will be described. In this embodiment, the encoder 13 is connected to the array probe 19.
The array probe 1 is opposed to the
In this method, the element is fixed at a position parallel to the arrangement direction of the elements 9 and connected to the calibration probe 14 with a wire, and the position is specified from the length of the wire. The calibration test piece 22 is set between the array probe 19 and the calibration probe 14 and transmitted from the calibration probe 14 to the first element 2 of the array probe.
The measurement is performed sequentially from the position of 0 to the N-th element 21.

In the actual calibration, the position of the element of the array probe 19 corresponding to the position of the calibration probe 14 is measured from the position signal of the encoder 13. And
Calibration probe 14 at a position facing the element to be measured
Of the calibration test piece 22
Then, a signal is transmitted from the calibration probe 14 and a signal obtained from the element to be measured by the array probe 19 via the calibration test piece 22 is received. At that time, the electronic scanning device converts the received signal of the element measured by the array probe 19 into a digital signal by the A / D converter 6 and stores the digital signal in the delay memory 7. At this time, the delay control by the signal from the delay control circuit 10 according to the command from the control device 50 is not performed.

In the calibration mode as described above,
The addition with the reception signal from another element by the addition circuit 8 is not performed by the signal from the control device 50. Only the signal of the element to be measured out of the N received signals is passed by the delay control circuit 10 and stored in the waveform storage memory 9 together with the position signal 17. FIG. 4 shows an example of a waveform storage state for each of these elements.

The calibration of the receiving circuit 12 will be described with reference to FIGS. FIG. 4A shows a waveform of a transmission signal from the probe 14. In contrast, FIG.
(B) shows the first element 20 of the array probe.
It is a reception waveform of (E1). The rise of the waveform is t
_{At 1} , the reception waveform rises with a delay from the transmission waveform of the probe 14. That is, there is a delay time of (t ₁ -t _C ).

The same applies to other elements. In this example, among the elements, the case of the element E2 indicates the maximum delay time. Therefore, the delay time is corrected (adjusted) in accordance with the E2 element. (T ₂ −
t ₁ ), for the element Ei, the delay time of (t ₂ −t _i ) is adjusted. If the time delay is adjusted for each element in this manner, it is set by the virtual address method shown in FIG. be able to. However, although there is a delay time of (t ₂ −t _C ) as a whole, variation between elements can be minimized. This is effective for forming a wavefront.

The specific setting of these delay times is performed by setting the delay time according to the example of setting the delay time in the delay memory shown in FIG. 2 and the concept of FIGS. 2A, 2B and 2C. I just need. FIG. 2B shows the actual delay time T
₁ is used to write a waveform from virtual address 1 using a virtual address. Then, after the delay 1 has elapsed, the actual waveform is written from address 0. The same applies to FIG. 2 (C), where the delay time is T _N ,
When writing is performed from the virtual address N, a significant waveform is stored from the address 0.

Even if the waveforms have the delay times T ₁ and T _N , if the reading is performed from the address 0, the waveform can be read as a waveform having no delay time as shown as the read waveform 24. By writing to and reading from the delay memory 7 in this manner, the delay time of the receiving circuit can be corrected.

FIGS. 4F to 4J show the case of calibrating the transmission circuit 3. FIG. In this case, the drive signal is switched and transmitted to the elements 1 to N by the transmission circuit 3,
Received by the calibration probe 14. Selection of an element by the encoder 13 is performed by the receiving circuit 1.
This is the same as the case of the calibration of 2. FIG. 4F shows a waveform of a transmission signal transmitted to the elements E1 to EN. FIG. 4G shows a signal received by the probe 14 for the element E1. In this case, the reception has been completed without any time delay.

The element indicating the maximum delay time in this case is the i-th element, and the delay time is adjusted accordingly. That is, the first element is (t
_i− t ₁ ), the second element is delayed by (t _i −t ₂ ), the Nth element is delayed by (t _i −t _N ), and the matching is performed in accordance with the i th element. Eventually, the variation of each element is adjusted to the element having the maximum delay time, so that the overall delay time remains, but the variation of the element as a whole is eliminated and matching is achieved. The waveform storage memory 9 stores the waveform of FIG. The setting of these delay times is performed by the transmission delay circuit 1.

The calculation of the delay time is performed by the correction amount calculation circuit 11 according to a command from the control device 50. Based on these calculation results, the setting is matched by the transmission delay circuit 1 in the case of the transmission circuit, and by the delay memory 7 corresponding to the reception delay circuit in the case of the reception circuit, and the flaw detection is performed via the delay time. It is. Therefore, it can be used after correcting the variation of the element.
In order to cope with a temporal change, the above correction may be performed periodically. Since the aging of the calibration probe 14 can be considered, only the calibration probe 14 needs to be replaced at that time.

Here, a case has been described in which correction is performed with a primary focus on variation for each element. However, for example, when a wavefront is formed as shown in FIG. 6B, it is necessary to set a different delay time for each element. . In this case, if there is no variation in the set delay time, there is no problem with the above calibration. However, in practice, the setting may vary, and, rarely, a new variation may occur in the transmission / reception circuit due to the set delay time. That is, the set delay time varies. For example, FIG.
In this case, the read address is read out with a shift of the set time. Then, the variation with respect to the set time may be corrected using the virtual address.

Even in such a case, calibration can be performed including the set delay time. The present invention employs a method of individually measuring and correcting the characteristics of each element, so that it is possible to cope with such a case and perform accurate calibration.

With the calibration probe 14 in the same position, an ultrasonic signal is transmitted from the element to be measured by the array probe 19 to the calibration test piece 22, and the calibration probe 14 is
And converted into a digital signal by the A / D converter 18. Then, it is stored in the waveform storage memory 9 together with the position signal 17 of the encoder 13. This is the case where the calibration probe 14 is placed at the same position and calibration of transmission and reception is performed. Such correction of transmission / reception may be performed one element at a time.

Similarly, the calibration probe 14 is moved from the second element to the N-th element 21 and the array probe 1 is moved.
The transmission / reception of the ultrasonic signal is performed for all the elements 9. This operation is repeated to store the data of the received waveform and the position signal 17 for all the elements in the waveform storage memory 9 for correction.

From the data stored in the waveform storage memory 9, it is possible to detect the variation in the transmission delay time and the variation in the reception delay time of each element. Calibration test piece 2
Of the array probe 19 and the calibration probe 14 through the
The correction amount calculation circuit 11 calculates the time difference (correction amount) of each element with reference to the element of the maximum time delay of the ultrasonic signal in reception or transmission.
The correction amount calculation circuit 11 adds the calculated correction value to the data stored in the delay control circuit 10 and stores the data.
In the correction of the array probe 19 with respect to the N transmission / reception elements, the delay time error on the reception side can be corrected by this method.

Further, after the measurement is completed, the correction amount calculating circuit 11
As a result, the magnitude of the received signal received by the array probe 19 from the calibration probe 14 via the calibration test piece 22 is compared with the received signal of each element stored in the waveform storage memory 9, and the variation in reception sensitivity is obtained. Is calculated, and the sensitivity difference is corrected by changing the amplification factor (degree) of the amplification circuit 5R corresponding to each element for each circuit.

Next, in each element of the array probe 19, an ultrasonic signal is transmitted via the calibration test piece 22, and the magnitude of the received signal received by the calibration probe 14 is compared. The variation is calculated, and the transmission voltage of the transmission circuit 3 of the electronic scanning device corresponding to each element is changed for each circuit to correct the output difference.

The correction amount calculation circuit 11 stores the calculated correction value in the data of the same element of the delay control circuit 10.
The sensitivity correction of the N transmitting and receiving elements of the array probe 19 can be corrected by correcting the amplification on the receiving side and the voltage on the transmitting side by this method.

When adjusting the transmission energy or the reception sensitivity of each element by comparing the signal magnitudes, the threshold value TH is set as shown in FIG. (Or if a signal above the threshold is detected if a value equivalent to the upper limit is set as the threshold), the element for which the signal is detected is not adjusted and corrected, Judge as abnormal. In FIG. 5A, the threshold values TH1 and TH2 are set as the lower limit values. If the threshold values TH1 and T2 are exceeded as shown in FIG. In the case of FIG. 5B, since the detected signal is equal to or less than TH3 and TH4, it is determined that the element is abnormal. In this way, it is possible to detect an abnormality of the electronic scanning device or the array probe 19.

Although the above-described configuration uses the encoder 13, the driving elements of the array probe 19 are sequentially switched from No. 1 to No. N in order without using the encoder 13, and the calibration probe 14 is used. Between the transmission and reception, the position where the echo height is highest is recognized as transmission and reception of the selected element and the calibration probe 14, and the calibration probe 14 is sequentially moved, A method of measuring the delay data of the corresponding element may be used.

According to the present invention, the delay time, the transmission output, and the reception sensitivity can be easily measured and automatically corrected for each of a plurality of elements of the array probe. As a result, the delay time given to a plurality of elements can be given with high accuracy, and variations in transmission output and variations in reception sensitivity can be eliminated. Even if a different type of array probe is connected or the test environment changes, correction can be performed in a short time using the calibration test piece, calibration probe, and encoder. There is an effect that the time can be significantly reduced. Also, by storing the corrected values in the apparatus according to the specifications of the array probe, it becomes possible to correct and manage the aging of the apparatus and the probe.

According to the present invention, the time difference between the transmission circuit and the reception circuit of the electronic scanning device and the ultrasonic transmission and reception elements of the array probe and the plurality of transmission and reception of the transmission circuit and the array probe of the electronic scanning device are different. It is possible to measure and correct the variation in output between elements and the variation in sensitivity between a plurality of elements for receiving ultrasonic waves of the receiving circuit and the array probe of the electronic scanning device, and to correct them. It is possible to accurately set the delay time, the transmission signal, and the reception signal.

[0045]

According to the present invention, it is possible to easily correct the transmission circuit and the reception circuit including the variation of each of a plurality of elements of the array probe. Even if there is a change with time, the correction can be made correspondingly.

[Brief description of the drawings]

FIG. 1 is an overall block diagram of an electronic scanning device according to the present invention.

FIG. 2 is a diagram for explaining how to use an electronic scanning device delay memory.

FIG. 3 is an explanatory diagram of a method of calibrating an electronic scanning device.

FIG. 4 is a diagram for explaining variation correction in reception and transmission.

FIG. 5 is a diagram illustrating an example in which a threshold value is provided for a received signal to determine whether an element is abnormal.

FIG. 6 is an explanatory diagram of a wavefront configuration with or without a delay time in electronic scanning.

[Explanation of symbols]

1: Transmission delay circuit 2: Transmission switching circuit 3: Transmission circuit
4: Reception switching circuit 5T, 5R: Amplifier circuit 6: A / D
Converter 7 Delay memory 8 Adder circuit 9 Waveform storage memory 10 Delay control circuit 11 Correction amount calculation circuit
DESCRIPTION OF SYMBOLS 12 ... Receiving circuit 13 ... Encoder 14 ... Calibration probe 15 ... Calibration probe transmission circuit 16 ... Calibration probe receiving circuit 17 ...
Position signal 18 A / D converter 19 Array probe 20 First element 21 Nth element 22 Calibration test piece 23 Array probe reception signal waveform 24 Signal waveform after phase matching due to delay
Reference numeral 30: transmission signal generator 40: switching control circuit 50: control device

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2G047 BA03 CA01 DB02 EA10 EA11 GB02 GB16 GJ21 4C301 AA02 BB22 EE11 EE12 GB04 LL17

Claims (7)

[Claims] 1. An ultrasonic flaw detector which performs flaw detection by electronic scanning on an array probe comprising elements as a plurality of ultrasonic transducers, wherein a driving signal is transmitted to each of the plurality of elements, and The other elements are received by the calibration probe via the calibration test piece corresponding to the element, and the other elements are delayed by the same time with respect to the element indicating the maximum delay of the received signal at the probe. A method for correcting a delay time of an ultrasonic flaw detection apparatus, wherein a delay time with respect to the delay time is corrected and set, and matching between elements in transmission of the element is performed. 2. The calibration probe according to claim 1, wherein a drive signal is transmitted from a calibration probe to each of the plurality of elements in addition to the delay time correction of the transmission signal. Receiving a transmission signal from the stylus, correcting and setting the reception delay time with respect to the other elements so as to have the same time delay based on the element indicating the maximum delay of the reception signal, A method for correcting a delay time of an ultrasonic flaw detector, wherein matching is performed. 3. The ultrasonic flaw detector according to claim 1, wherein the position of the calibration probe corresponding to the element is obtained by a signal of an encoder connected to the calibration probe. Delay time correction method. 4. An ultrasonic wave according to claim 1, wherein the time delay matching is set by a virtual address, a read address is specified, and a variation between elements or a variation in a set delay time is corrected. A method for correcting a delay time of a flaw detector. 5. An ultrasonic flaw detector which performs flaw detection by changing a flaw detection angle by electronic scanning with respect to an array probe comprising elements as a plurality of ultrasonic transducers, wherein a drive signal is transmitted to each of the plurality of elements. A calibration circuit that receives the transmission signal via a calibration test piece corresponding to each of the elements, a waveform storage memory that stores a received signal, and a waveform storage memory that stores the received signal. A correction amount calculating circuit for calculating a transmission delay time correction amount for other elements so as to have the same time delay based on the element showing the maximum delay from the signal, and applying the calculated correction amount to each transmission signal. A delay control circuit for the ultrasonic flaw detector. 6. A receiving circuit according to claim 5, wherein said receiving circuit receives a transmission signal from said calibration probe for each of said plurality of elements, in addition to correcting said transmission signal. A waveform storage memory for storing the waveform of the transmission signal received via the calibration test piece, and other elements so as to have the same time delay based on the element showing the maximum delay from the signal of the waveform storage memory. Delay time correction for an ultrasonic flaw detection apparatus, comprising: a correction amount calculation circuit for calculating a delay time with respect to a signal; and a delay control circuit for correcting the calculated correction amount for each received signal. apparatus. 7. An electronic scanning ultrasonic flaw detector which has an array probe composed of a plurality of elements as ultrasonic transducers and performs an ultrasonic probe, a transmission for delaying a drive signal for each element of the array probe. A transmission circuit including a delay circuit, a reception circuit including a delay memory that stores a signal received by the array probe, a waveform storage memory that receives a transmission signal from the calibration probe and stores a waveform together with the transmission signal. A correction amount calculating circuit of a receiving circuit for matching based on an element indicating a maximum delay time, and the waveform storage memory for receiving and storing a drive signal from the transmitting circuit by the calibration probe, The correction amount calculation for calculating a correction amount of a transmission circuit for achieving matching with another element based on the element indicating the maximum delay time. Circuit, a transmission delay circuit and a delay memory for performing correction setting of the delay time based on the calculated correction amount of the transmission circuit and the correction amount of the reception circuit, respectively, Delay time correction device.