JPH0561589B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a mark display device for an ultrasonic flaw detector that attaches a mark to a specific reflected wave displayed on a display unit in an ultrasonic flaw detector. Regarding.

[Conventional technology]

Ultrasonic flaw detectors are well known as devices that inspect the presence or absence of flaws inside an object without destroying the object. This ultrasonic flaw detector will be explained using figures.

FIG. 19 is a block diagram of a conventional ultrasonic flaw detector. In the figure, 1 indicates the object to be inspected, and 1f indicates a defect existing in the object to be inspected 1. 2 is an ultrasonic probe that emits ultrasonic waves into the object to be inspected 1 and outputs an electric signal proportional to the reflected ultrasonic waves. 3 is an ultrasonic flaw detector, and ultrasonic probe 2
It outputs an ultrasonic generation pulse to the ultrasonic probe 2, receives a signal from the ultrasonic probe 2, and displays the waveform of this signal.

The ultrasonic flaw detector 3 is composed of the following elements. That is, 4 is a synchronous circuit that generates a signal voltage that temporally regulates the operation of the ultrasonic flaw detector 3, and 5 is a synchronous circuit that outputs pulses for generating ultrasonic waves to the ultrasonic probe 2 based on the signal from the synchronous circuit 4. This is the transmitter. 6'
A receiving section receives signals from the ultrasonic probe 2, and is composed of an attenuation circuit 6a consisting of a combination of voltage dividers made up of resistors, and an amplification circuit 6b'. 7 is a detection circuit for rectifying the signal from the amplifier circuit 6b', and 8 is a vertical axis amplifier circuit.

Reference numeral 9 represents a sweep circuit that generates a triangular wave based on the synchronization signal from the synchronization circuit 4, and reference numeral 10 represents an amplifier circuit that amplifies the triangular wave signal from the sweep circuit 9. 11 is a display unit that displays the signal waveform from the ultrasound probe 2, the horizontal axis is the time axis determined by the triangular wave output from the amplifier circuit 10, and the vertical axis is the vertical axis output from the amplifier circuit 8. It is considered to be the magnitude of the signal. A cathode ray tube is used as the display section 11, and a scale is displayed on its surface. 12 is the object to be inspected 1,
This is a measurement range setting section that sets the range to be inspected (measurement range) from the surface. Reference numeral 13 denotes a delay time setting section that adds a delay time to the sweep start signal and moves the position of the waveform displayed on the display section 11 in parallel.

Next, an outline of the operation of the conventional ultrasonic flaw detector described above will be explained. When a pulse is output from the transmitter 5 due to the signal voltage from the synchronous circuit 4, the ultrasonic probe 2
is excited by this pulse and emits ultrasonic waves to the object 1 to be inspected. A part of the emitted ultrasonic waves is immediately transmitted to the ultrasonic probe 2 from the surface of the object to be inspected 1.
, and the others propagate within the object to be inspected 1 , reach the bottom of the object to be inspected 1 , where they are reflected and return to the ultrasound probe 2 . On the other hand, if a defect 1f exists in the object to be inspected 1, the ultrasonic waves are also reflected from the defect 1f and return to the ultrasonic probe 2. The ultrasonic waves returned to the ultrasonic probe 2 excites the ultrasonic probe 2 in proportion to its magnitude, and the ultrasonic probe 2 outputs an electric signal corresponding to this.

This signal is input to the attenuation circuit 6a, adjusted to a size suitable for processing, and input to the detection circuit 7 via the amplifier circuit 6b'. The detection circuit 7 rectifies the input signal so that the display unit 11 displays a one-sided swing instruction. At this time, noise components mixed in the signal are also removed. The output signal of the detection circuit 7 is input to the display section 11 via the vertical axis amplifier circuit 8, and its magnitude is displayed on the vertical axis of the display section 11. On the other hand, the sweep circuit 9 generates a triangular wave voltage based on the synchronization signal from the synchronization circuit 4, and this voltage passes through the amplifier circuit 10 to the display section 11.
Applied to the deflection electrode of a cathode ray tube (cathode ray tube), it sweeps the electron beam. Due to this sweep and the input signal from the vertical axis amplifier circuit 8, the waveform of the reflected wave returned to the ultrasound probe 2 is displayed on the display section 11.

In flaw detection using such an ultrasonic flaw detector 3, the waveform of the reflected wave displayed on the display section 11 changes depending on the state of contact between the object to be inspected 1 and the ultrasonic probe 2. To avoid this, a water immersion method is usually adopted. FIG. 20 is a sectional view illustrating the water immersion method. In the figure, 1 is the object to be inspected,
1f is a defect and 2 is an ultrasonic probe, which are the same as those shown in FIG. 15 is an aquarium,
16 indicates water in the water tank 15. The object to be inspected 1 is submerged in a water tank 15, and the ultrasonic probe 2 is opposed to the object to be inspected 1 with water 16 in between. The ultrasonic waves from the ultrasonic probe 2 pass through the water 16 and reach the object 1 to be inspected.
Since the reflected waves from various parts of the object to be inspected 1 are input to the ultrasonic probe 2 via the water 16, a stable waveform is displayed on the display section 11.

FIG. 21 is a waveform diagram of the displayed reflected waves.
In the figure, the horizontal axis shows time and the vertical axis shows the magnitude of reflected waves. T is a transmitted wave of ultrasonic waves transmitted from the ultrasonic probe 2, S is a reflected wave from the surface of the object to be inspected 1,
F is a reflected wave from the defect 1f, B is a reflected wave from the bottom of the object to be inspected 1, and _Bs is a reflected wave from the bottom of the water tank 15. Note that since the sound speed of the ultrasonic wave within the object to be inspected 1 is constant, the horizontal axis (time axis) represents the distance, and from this waveform diagram, the defect 1f
The location of is revealed.

By the way, in general, when inspecting the object to be inspected 1, it is not necessarily necessary to inspect the entire object from the surface to the bottom, but a certain depth range (measurement range) within the object to be inspected 1 is displayed on the display section 11, and this In many cases, it is sufficient to inspect the range. In this case, expand or reduce the waveform by operating the coarse adjustment knob and fine adjustment knob of the measurement range setting section 12, and move the waveform by operating the knob of the delay time setting section 13. A desired measurement range in the waveform diagram shown in FIG. 21 is displayed on the display section 11. This allows the inspector to clearly and easily observe the area to be carefully inspected, reducing the time and effort required for inspection, and enabling more accurate inspection.

[Problem that the invention seeks to solve]

By the way, in the above-mentioned ultrasonic flaw detector, a predetermined measurement range is displayed on the display unit 11 by operating the measurement range setting unit 12 and the delay time setting unit 13 as described above. , or in the vicinity of the bottom surface, means is used to constantly display the reflected wave S or the reflected wave B on the display unit 11 to accurately recognize the position of the defect 1f. However, if the observation is resumed after being temporarily interrupted, or if the observer is changed midway through the observation, the display unit
It may become impossible to determine whether the reflected wave displayed in 1 is the reflected wave S or the reflected wave SB, which may cause confusion. Such confusion may occur, for example, if there are multiple defects 1f and the display range is narrowed to more accurately observe their positions, and the reflected wave S or reflected wave B is removed from the display section 11, the waveform may be moved. This also occurs when the reflected wave S or reflected wave B is displayed again. In this case, the observer cannot tell which part of the object 1 to be inspected is being observed.

Furthermore, if the gain is reduced by mistake and the reflected wave is no longer displayed at the position where it should be displayed, the observer may mistakenly think that a failure has occurred in the ultrasonic flaw detector and locate the failure location. It would be a waste of time and effort to detect the flaws.

Furthermore, when flaw detection is carried out by directly contacting the probe 2 with the object to be inspected 1 without using the above-mentioned water immersion method, if the contact of the flaw probe 2 is poor or the contact surface is rough, In some cases, reflected waves may not be obtained, and in this case, the observer must check whether the contact is not good or not.
It becomes impossible to determine whether the gain is insufficient, whether the wrong location is being detected, or whether the ultrasonic flaw detector is malfunctioning.

The above-mentioned drawbacks are all due to the inability to confirm the reflected waves S and B, and it is thought that they can be resolved if this can be confirmed.

The present invention has been made in view of the above circumstances, and its purpose is to solve the problems of the prior art described above, to be able to reliably recognize a predetermined reflected wave, and to be able to recognize the predetermined reflected wave. The goal is to provide an ultrasonic flaw detector that can easily display this when it is not visible.

[Means for solving problems]

In order to achieve the above object, the present invention assigns a desired code to the reflected waves S, B, etc., and is configured to digitally process the signal obtained by the receiving section. That is, the present invention includes a transmitter that outputs a predetermined pulse to an ultrasound probe, a receiver that receives a signal from the ultrasound probe, and a transmitter that outputs a predetermined pulse to an ultrasound probe. In an ultrasonic flaw detector, the ultrasonic flaw detector includes a waveform memory that sequentially stores the input signal received by the receiving section in addresses at a predetermined sampling period, and a display section that displays the waveform of the signal on the display section. a display memory for storing data; a selection means for selecting an address of the waveform memory according to a measurement range to be displayed on the display section; and an address of the display memory corresponding to the data at the address selected by the selection means. a waveform display means for displaying the data in the display memory on the display section; a reflected wave selection means for selecting a predetermined reflected wave from among the displayed reflected waves; a calculation means for calculating a distance of , an address determination means for determining an address of the display memory corresponding to the calculated distance, and a mark display for displaying a predetermined mark at a position on the display section corresponding to the determined address. and mark search means for changing the starting point of the measurement range and displaying the mark on the display when the mark is not displayed on the display.

[Effect]

The signal received by the receiver is stored in a waveform memory as a digital signal. Then, predetermined data of the data stored in the waveform memory is transferred to the display memory according to the measurement range, and the data in the display memory is displayed on the display section by the waveform display means. Next, a predetermined one is selected from among the displayed reflected waves, and the distance of the peak value of the reflected wave is calculated. Then, based on this distance, an address corresponding to the distance in the display memory is determined, and a predetermined mark is displayed on the display surface of the display section corresponding to this address. During measurement, if the reflected wave with a mark is not displayed and it is desired to display it, the mark is displayed on the display screen together with the reflected wave by the mark search means.

〔Example〕

Hereinafter, the present invention will be explained based on illustrated embodiments.

FIG. 1 is a block diagram of an ultrasonic flaw detector according to an embodiment of the present invention. In the figure, the same parts as those shown in FIG. 19 are denoted by the same reference numerals, and the description thereof will be omitted.
In addition, in the ultrasonic flaw detector, there are cases where reflected waves are detected and displayed, and cases where reflected waves are displayed without detection, and the present invention is applicable in either case. Therefore, in the following, the combination of the amplifier 6b' and the detection circuit 7 in FIG. 19 will be referred to as the amplifier circuit 6b.
An example will be shown in which the receiving section 6 is configured as follows and detection is performed. Reference numeral 21 indicates an ultrasonic flaw detector of this embodiment.
This ultrasonic flaw detector 21 is composed of the following elements. That is, 22 is an A/D converter that converts the output signal of the receiver 6 into a digital value, and 23 is an A/D converter.
A waveform memory 24 stores the values converted by the D converter 22, and an address counter 24 sequentially designates each address of the waveform memory 23. Reference numeral 25 denotes a timing circuit, which provides activation signals to the transmitter 5, the A/D converter, and the address counter 24, respectively. A crystal oscillator is used for oscillation of this timing circuit 25.

26 is a CPU (central processing unit) that performs necessary calculations and control, and 27 is a RAM (random access memory) that temporarily stores parameters and data for calculations.
memory), 28 stores the processing procedure of the CPU 26
It is ROM (read only memory). 30
is a keyboard input section for inputting the speed at which ultrasonic waves propagate within the object 1 to be inspected (sound velocity) and other values. 31 is the liquid crystal display section, 32 is the calculation of the CPU 26,
This is a display unit controller that controls the display of the liquid phase display unit 31 based on data obtained as a result of control. 32m is a display memory provided in the display unit controller 32, and data to be displayed on the liquid crystal display unit 31 is stored in this display memory 32m.
The number of addresses in the display memory 32m is the same as the number of liquid crystal dots arranged in the horizontal direction in the liquid crystal display section 31. 33 is a mark setting section, which is used to mark the reflected wave. This mark setting section will be further described later with reference to FIG. 34
is a cursor starting point setting section that determines the starting point position of the cursor when displaying a cursor on the display section 31;
35 is a cursor width setting section that specifies the width of the cursor. 36 is a display start point setting section for setting a display start point when displaying a waveform on the display section 31; 37;
is a measurement range setting section that determines the measurement range.

FIG. 2 is a layout diagram of key switches in the mark setting section 33 shown in FIG. 1. In this embodiment, the key switches of the mark setting section 33 are 0 to 9.
10 numeric key switches 33a, 26 alphanumeric key switches 3 from A to Z
3d, a mark key switch 33b with a "mark" display, a set key switch 33c with a "set" display, and a search key switch 33e with a "search" display. The mark key switch 33b has a function of starting a processing operation for setting a mark, and
3c has a function of outputting an input end signal,
Further, the search key switch 33e has a function of displaying the reflected waves with marks on the liquid crystal display section 31.

Next, the operation of this embodiment will be explained. In this embodiment, as can be seen from FIG. 1 and its explanation, the ultrasonic signal waveform received by the receiving section 6 is digitally processed and input to the waveform memory 23 (waveform memory input means). The measurement start point setting section 36 and the measurement range setting section 37 select a signal in a desired range and display it on the liquid crystal display section 31 (measurement range display means), and a predetermined reflection of the displayed signal waveform is selected. Wave cursor start point setting section 3
4. Operate the cursor width setting unit 35 to make a selection with the cursor (cursor display means), and add a desired mark to the selected reflected wave by the mark setting unit 33 (marking unit), and display the waveform to which the mark has been added. Display it on the display (mark search means)
This operation is executed. The waveform memory input means, measurement range display means, cursor display means, mark adding means and mark search means will be explained below.

() Waveform Memory Input Means First, the operation of storing data in the waveform memory 23 will be explained with reference to the waveform diagram of the reflected wave shown in FIG. 3 and the block diagram of the waveform memory 23 shown in FIG. From the timing circuit 25 to the transmitter 5
When the trigger signal is output, the transmitter 5 outputs a pulse to the ultrasound probe 2, and
Ultrasonic waves are radiated into the object 1 to be inspected. This reflected ultrasound wave is converted into an electrical signal by the ultrasound probe 2, and this signal is received by the receiver 6. The receiving unit 6 outputs the received reflected wave signal as a value suitable for subsequent processing. This output reflected wave signal is converted into a digital value in the A/D converter 22 at every predetermined sampling period, and the converted value is sequentially stored in the waveform memory 22.
3 is stored. This storage is performed by the address counter 24 sequentially specifying the addresses of the waveform memory 23. Sampling of the reflected wave signal and addressing of the waveform memory 23 are executed by a start signal output from the timing circuit 25. The sampling of such a reflected wave signal and the storage of its digital value in the waveform memory 23 will be explained with reference to FIGS. 3 and 4.

FIG. 3 is a waveform diagram of the reflected wave signal. In the figure,
The horizontal axis shows time, and the vertical axis shows the magnitude (voltage) of the reflected wave signal. T and F indicate the same reflected waves as shown in FIG. In addition, in FIG. 3, only the horizontal axis is extremely enlarged. Next, FIG. 4 is a block diagram of the waveform memory 23. Each block shown in a column means a data storage section in the waveform memory 23, and D ₍₀₎ , D ₍₁₎ , ... D _(o-1) , written in each storage section.
D _(o) , D _(o+1) . . . are reflected wave signal data converted into digital values by the A/D converter 22. These data are expressed as D _(i) in general form.
In addition, the code A _{M (0)} written on the left side of each storage section,
A _M(1) , ...A _M(o-1) , A _M(o) , A _M(o+1) ...indicate the addresses of the corresponding storage units. These addresses are expressed as A _M(i) in general form.

Now, at time t ₀ shown in FIG. 3, when a start signal is output from the timing circuit 25 to the A/D converter 22 and the address counter 24,
The A/D converter 22 A/D converts the voltage of the reflected wave T at that time to obtain data D ₍₀₎ . Further, the address counter 24 specifies address A _{M (0)} of the waveform memory 23. As a result, data D ₍₀₎ is stored at address A _{M (0)} of waveform memory 23.
Next, at time t ₁ after time τ _s has elapsed, when the timing circuit 25 outputs the activation signal to the A/D converter 22 and address counter 24 again, the voltage of the reflected wave T at that time also becomes A/D.
Data D ₍₁₎ is obtained through conversion by the D converter 22, and the address counter 24 reads the next address.
Since A _M(1) is specified, data D ₍₁₎ is stored at address A _M(1) of the waveform memory 23. In this case, the time τ _s is the sampling time (e.g. 50ns)
becomes. Similarly, the reflected waves T, S, F,
B _s ... data will be stored in the waveform memory 23.

() Measurement Range Display Means The waveform data stored in the waveform memory 23 as described above is not used for displaying all of them, but only data within a desired range is used for displaying. That is, desired data from among the data is selected and input into the display memory 32m of the display unit controller 32, and a display is performed based on these input data.

Here, first, the waveform memory 23 and the liquid crystal display section 3
1. An overview of the relationship between the controller 32 and the display memory 32m will be explained. The liquid crystal display section 31 has a certain number of liquid crystal dots arranged in the horizontal direction, and the display section controller 32 is provided with a display memory 32m having the same number of addresses as the number of the arrangement, as described above. . now,
Assuming that the number of liquid crystal dot arrays is 200, the address of the display memory 32m {this is the number of A _L(j) from address A _L(0) to address A _L(199)
It will be 200. Also, the address of the waveform memory 23
The number of addresses in which reflected waves T, S, F, B, and _Bs are stored in A _M(i) is, for example, 1000. On the other hand, the number of display memories is 200, so
In order to display all areas, it is necessary to thin out the data to be displayed. Therefore, among the above 1000 addresses {addresses A _M(0) to _{A M(999)} }, every fifth address {addresses A _M(0) , A _M(5) ,
_{. _ _} By displaying on the liquid crystal display section 31, each reflected wave T to _Bs can be displayed.

Now, based on the above relationship, the operation of displaying the waveform of a desired measurement range will be explained next with reference to the waveform diagram shown in FIG. 5 and the flowchart shown in FIG. 6. In Figure 5, T, S, F, B,
B _s is the same waveform of the reflected wave as shown in FIG. A portion 31A surrounded by a dashed line is a desired measurement range to be displayed on the liquid crystal display section 31. In addition, the measurement range 31A is the liquid crystal display section 3.
1, this is the area for displaying waveforms. moreover,
C _S and C _E are a front cursor and a back cursor displayed on the liquid crystal display section 31, respectively. 31B
indicates an area sandwiched between the front cursor C _S and the rear cursor C _E , and is selected within the measurement range 31A. X ₁ , X ₂ , and X ₃ are distances l _S and
Indicates the position where l _R and l _E are displayed on the screen. The previous cursor C _S and the subsequent cursor C _E will be explained in the section ( ) cursor display means described later. The state shown in FIG. 5 is a state in which the area of measurement range l _R on both sides of the area 31B sandwiched between the cursors C _S and _CE is displayed on the liquid crystal display section 31. It is shown schematically. Here, the illustrated dimensions (distances) will be described.

l _S : Distance from the starting point (in this example, the peak position of the reflected wave S from the surface) to the left end of the measurement range 31A l _R : Distance corresponding to the width of the measurement range 31A l _CS : From the left end of the measurement range 31A to the front Distance to cursor C _S l _CE : From left end of measurement range 31A to rear cursor C _E
Distance l _W : Width of the area 31B between the front cursor C _S and the rear cursor C _E (cursor width) Here, the starting point of the distance l _S will be explained. This starting point (l _S =0) is the waveform memory 2 in this embodiment.
In step 3, a method is used to calculate the speed of sound from the elapsed time from the time when data storage is started (assuming that the transmission pulse output and data storage start are performed at the same time) and the speed of sound (known). Note that the starting point of such distance measurement is not limited to the position of the reflected wave S as in this embodiment, and can be set at any position. In that case, the address of the corresponding waveform memory 23 may be made to correspond to the start address of the display memory 32m of this embodiment. In the following explanation, the position corresponding to the start address of the waveform memory 23 is assumed to have a distance of 0.

Next, the operation when displaying a waveform as shown in FIG. 5 on the liquid crystal display section 31 will be described below. First, the sound speed at which the ultrasonic wave propagates inside the object to be inspected 1 (this sound speed is
_VS ), and also input the measurement start point setting section 3.
6 and the measurement range setting section 37, the distance l _S from the starting point to the left end of the measurement area and the width l _R of the measurement range 31A are input, respectively. Also, the number of addresses A _L(j) of the display memory 32m is
1, and is stored in advance. The number of addresses A _L(j) (200 in the explanation of the origin setting) is set to K _L
Expressed as

The measurement start point setting section 36 and the measurement range setting section 37 are each composed of a rotary switch, and the unit value Δl is determined by rotation of a unit angle in one direction, for example, clockwise (positive direction).
is added to the current value and subtracted by rotation of unit angle in the opposite direction (negative direction). Such addition and subtraction will affect the operating amount of each rotary switch.
This is done by reading the data into the CPU 26, which sets the distance l _S in the measurement start point setting section 36 and the distance l _R in the measurement range setting section 37, and uses these values l _S and l _R to measure from the starting point. The distance l _E (l _E =l _S +l _R ) to the end of the range is determined.
These values l _S , l _R , l _E are at the positions X ₁ ,
Displayed in X ₂ and X ₃ respectively.

Once each of the above values v _S , l _S , l _R , and K _L are determined, the CPU
26 sequentially reads these numerical values according to the procedure stored in the ROM 28 (procedure P ₁₁ shown in FIG. 6).

Next, in order to display the waveform within the measurement range 31A of the liquid crystal display section 31, it is calculated how to retrieve the data stored in the waveform memory 23 (step P ₁₂ ). This calculation will be explained below.

The waveform memory 23 stores the reflected wave T as described above.
The following reflected wave data is stored. However, as described above, what is needed is the data within these measurement ranges 31A, and it is sufficient to display the data within these measurement ranges 31A on the liquid crystal display section 31. Therefore, in the above calculation, data within the measurement range 31A is displayed on the liquid crystal display section 3.
1, this calculation is for determining how to select an address in the waveform memory 23 to store data within the measurement range.

For example, L _SB is the distance between the surface and the bottom of the object to be inspected 1, that is, the distance between the reflected waves S and B, ΔK is the number of addresses in the waveform memory 23 that stores data between them, and the reflected wave S is received. The following equation holds true, where t is the time from when the reflected wave B is received.

2L _SB = v _S・t=v _S・ΔK・τ _S ...(1) ΔK=2L _SB /v _S・τ _S ...(2) In other words, store the data of the distance L _SB of the object to be inspected 1. The number ΔK of addresses in the waveform memory 23 is expressed by the above equation (2). Therefore, the number ΔK' of addresses in the measurement range 31A of distance l _R is ΔK'=2l _R /v _S ·τ _S (3). In this equation (3), if 2/v _S・τ _S =β, then ΔK'=βl _R ...(4).

To display the measurement range 31A on the entire liquid crystal display 31, select the number _KL of addresses in the display memory 23m from each address constituting the number ΔK' of addresses in the waveform memory 23, and select the address A of the display memory 23m. Just make it correspond to _L(j) . Therefore, the ratio α of the number ΔK′ and the number K _L
Taking α=K _L /ΔK′=v _S・τ _S /2l _R K _L ……(5). That is, the address A _M(i) of the waveform memory 23
It is only necessary to select the address A L(j) of the display memory 32m by selecting it every 1/α from the address A _L(j) .

On the other hand, the distance from the peak point (starting point) of the reflected wave S is
The address of the waveform memory 23 at the left end of the measurement area at l _S is determined by the fact that the address of the peak point is A _M(S) and that the number of addresses between distance l _S is βl _S from equation (4). From this, we know that A _M(S+ dl _S) . Therefore, in order to display the measurement range 31A, the address of the waveform memory 23 must be
Addresses may be selected from A _M(S+ dl _S) every 1/α (step P ₁₃ ). That is, in the address A _M(i) of the waveform memory 23, the address number i to be selected is expressed by the following equation.

i=s+βl _S +j/α (6) In equation (6), j is the address number of the display memory 32m, and when K _L =200, j=0 to 199.

In the calculation of formula (6), the number j/α may not be an integer, so in this case, the number i is converted to an integer by an appropriate method such as rounding to the nearest 50 (procedure).
_P14 ). In this way, the addresses selected by the above means among the addresses of the waveform memory 23 are made to correspond to each address of the display memory 32m, and the data stored in the former is transferred to the latter (step P ₁₅ ). Then, the display unit controller 32 displays the data at each address in the display memory 32m on the display unit 11 (step P ₁₆ ), thereby making it possible to display the desired measurement range 31A.

In this way, by operating the measurement start point setting section 35 and the measurement range setting section 37, it is possible to enlarge or reduce any part of the reflected waveform and display it.

() Cursor Display Means Next, the operation of displaying a cursor on the liquid crystal display section 31 will be described with reference to the waveform diagram shown in FIG. 5 and the flowchart shown in FIG. 7. As described above, the cursor display is a display used to clarify the area 31B within the measurement range 31A of the object 1 to be inspected that should be observed carefully. Now, when a display as shown in FIG. 5 is performed, the area 31B is from the position of the previous cursor C _S (l _S +l _CS ) to the position of the next cursor C _E (l _S +l _CE ). A case in which such a cursor display is performed will be described below.

The cursor display is performed by the cursor starting point setting section 3.
4 and the cursor width setting section 35. Both the cursor start point setting section 34 and the cursor width setting section 35 are composed of rotary switches with a fixed 0 point, and when they are rotated in the positive direction, a numerical value (distance) is continuously added, and when they are rotated in the negative direction, the numeric value (distance) is continuously added. is continuously subtracted by

By the way, since the cursor is also displayed on the liquid crystal display section 31, it is natural that the positions (l _S +l _CS ) and (l _S +l _CE ) are displayed at the address A _{L (i )} . This response will be explained below. Now, set the distance (l _S
+l _CS ), but also the distance l _W in the cursor width setting section 35
If (l _W = l _CE −l _CS ) is indicated, then the distance l _S
Since is already known, the distance l _CS is first calculated (step P ₂₁ shown in FIG. 7). Then the values l _CS , l _W , l _R , l _L
is read (step P ₂₂ ), and the address corresponding to the distance l _CS in the display memory 32m, that is, the address of the previous cursor C _S , and the address corresponding to the distance l _CE , that is, the address of the next cursor C _E , are calculated by calculation. (Step P ₂₃ ). These addresses are the total number of addresses in the display memory 32m.
It is obtained by making the ratio of the addresses of both cursors to K _L equal to the ratio of the distance of both cursors to distance l _R. In other words, the address A _L(CS) of the previous cursor C _S and the address of the next cursor C _E are
If A _L(CE) , then each of these addresses is A _L(CS) ^* ,
Using A _L(CE) ^* , A _L(CS) ^* =l _CS /l _R ×K _L ……(7) A _L(CE) ^* =l _CE /l _R ×K _L =l _CS +l _w / l _R ×K _L ...(8) Convert A _L(CS) ^* and A _L(CE) ^* in equations (7) and (8) to integers (step P ₂₄ ), and as a result, the display memory will be 23 m The address A _{L (CS)} of the previous cursor C _S and the address A _{L (CE)} of the next cursor C _E are determined. Although waveform data has already been stored in each of these addresses, this data is changed to data displayed with a broken line indicating a cursor (step _P25 ). Next, the display unit controller 32 is driven to display data at addresses A _L(CS) and A _L(CE) (procedure).
P ₂₆ ) and cursors C _S and _E shown in FIG. 5 are displayed on the liquid crystal display section 31.

The operation of the cursor display has been explained above, but the cursor is originally intended to make it easier to see the area that you want to carefully observe.On the other hand, the area you want to observe is generally not limited to the same area, so
In normal usage, the cursor is displayed in the cursor start point setting section 34 and the cursor width setting section 3.
It is often moved by continuously rotating the rotary switch No. 5. Therefore, below, we will explain the movement of the cursor display in Figure 8 and Figure 1.
Flowchart shown in Figure 0, and Figures 9a to 9
e, will be explained with reference to the waveform diagrams shown in FIGS. 11a to 11c.

First, we will explain the operation when the widths (l _W ) of the front cursor C _S and the rear cursor C _E do not change, and both cursors C _S and C _E are moved left and right while maintaining these widths. In this case, the rotary switch of the cursor starting point setting section 34 is operated. The CPU 26 monitors whether or not this rotary switch has been operated (step P ₃₁ in Fig. 8), and if it has not been operated, the distances l _S , l _CS , l _W , l _CE
Let the value remain as it is (step P ₃₂ ), and first set the seventh
The cursor display process explained using the flowchart shown in the figure is executed (step _P33 ). In the flowcharts shown in FIGS. 8 and 10, each distance before executing the cursor position processing is expressed with a dash (l _S ′, l _CS ′, l _W ′, l _CE ′), Each distance after performing the above processing is expressed as (l _S , l _CS , l _W , l _CE ) without a dash. In the following, the cursor width setting section 35, the measurement range setting section 3
7 is not operated, so l _W = l _W ′, l _R = l _R ′
It is.

When the rotary switch of the cursor start point setting section 34 is operated, this is determined in step _P31 .
Next, it is determined whether the rotary switch has been rotated in the positive direction or in the negative direction (step _P34 ). When the rotary switch is rotated in the positive direction, that is, when the cursors C _S and _CE are moved to the right in FIG. 5, the operating amount of the rotary switch is read (step P ₃₅ ). Below, the operation amount in any direction is determined by moving the cursors C _S and C _E by the distance Δl ₁
This will be explained as the amount of movement. This distance Δl ₁ is added to the current distance l _CE ′ (l _CE ′ + Δl ₁ ) and the width l _R
(Step P ₃₆ ).

Here, the processing after the comparison will be explained with reference to the waveform diagrams shown in FIGS. 9a to 9c. Each figure {including FIGS. 9 d and 9 e} shows the display surface of the liquid crystal display section 31, and the same parts as shown in FIG. 5 are given the same reference numerals. In Figure 9a, the cursors C _S and C _E are at the 5th position.
The state is shown in the same position as shown in the figure, and this is considered the current position, and the following explanation will be about the movement of the cursors C _S and C _E from this position.

If it is determined in step _P36 that {(l _CE ′+Δl)<l _R }, the cursors C _S and _CE are at the positions shown in FIG. 9b, and {(l _CE ′+Δl ₁ )=l _R }, the cursors C _S and C _E will move to c in Figure 9.
The position shown in , that is, the rear cursor C _E is measurement range 3.
This is a case where the position coincides with the right end of 1A.
In these cases, the distances l _S , l _W remain the same,
Also, the distance l _CS is changed to the distance (l _CE ′+Δl ₁ ),
The distance l _CE is changed to the distance (l _CE ′+Δl ₁ ) (step P ₃₇ ). Cursor display processing is performed based on these distances (step _P33 ), and the cursors C _S and C _E move to the right, and cursor displays as shown in FIGS. 9b and 9c appear.

If it is determined in step _P36 that {(l _CE ′+Δl ₁ )>l _R }, this is a case where the rear cursor C _E deviates further to the right from the right end of the measurement range 31A. In this case, the rear cursor C _E remains stopped at the right end position as shown in FIG. 9c. i.e. distance
l _CE is l _CE = l _R ′, distance l _CS is l _CS = l _R − (l _CE ′−l _CS ′)
−l _R
-l _W (Step P ₃₈ ).

Now, in step _P34 , when the rotary switch is rotated in the negative direction, that is, when the cursors C _S and C _E are moved to the left in Fig. 5, the operation amount (distance Δl ₁ ) of the rotary switch is read. (procedure
P ₃₉ ), and whether the value (l _CS ′−Δl ₁ ) is positive or negative is determined (step P ₄₀ ). If the value (l _CS ′−Δl ₁ ) is determined to be positive, the cursors C _S and C _E are
The position is as shown in , and the value (l _CS ′−Δl ₁ )
is determined to be 0, the cursor C _S ,
C _E is at the position shown in Figure 9 e, i.e. the previous cursor C _S
This is the case where the position coincides with the left end of the measurement range. In these cases, the distances l _S and l _W remain the same, the distance l _CS becomes the distance (l _CS ′−Δl ₁ ), and the distance l _CE
is changed to the distance (l _CE ′−Δl ₁ ) (step P ₄₁ ), and then the process of step P ₃₃ is performed, and the cursors C _S , C _E
moves to the left, and a cursor display as shown in FIG. 9d and e appears.

If it is determined in step _P40 that {( _lCE' -Δl)<0}, this means that the previous cursor C _S is further leftward from the left end of the measurement range 31A. In this case, the distance l _CS becomes 0, and the distance l _CE becomes l _CE = l _CE ′−
After changing to l _CS ′=l _W (step P ₄₂ ), step P ₃₃
is processed, the previous cursor C _S matches the left edge of the display screen, and the cursor stops. The above process allows you to move the cursor without changing the cursor width.
C _S and C _E can be moved.

Next, the operation when changing the width of the front cursor C _S and the rear cursor C _E (width of the measurement range) will be explained. In this case, the rotary switch of the cursor width setting section 35 is operated. CPU
26 monitors whether or not this rotary switch has been operated (step P ₅₁ in Figure 10), and if it has not been operated, the distances l _CS , l _W , l _CE remain at their current values (step P 51 in Figure 10). _P52 ), and performs cursor display processing (step _P53 ).

When the rotary switch of the cursor width setting section 35 is operated, this is determined in step _P51 , and then the direction of the operation is determined (step _P54 ). When the rotary switch is rotated in the positive direction to widen the cursor width, the operating amount of the rotary switch is read (step P ₅₅ ).Hereafter, the operating amount in any direction is calculated by dividing the cursor width by a distance Δl ₂ This will be explained as the amount to be changed. Next, the value obtained by adding the distance Δl ₂ to the distance l _CE ′ is compared with the distance l _R (step P ₅₆ ). This comparison shows that when the cursor width is expanded to the right by moving the rear cursor C _E to the right, the rear cursor C _E is within the measurement range 31.
This is to determine whether or not it deviates from the right end of A. If the distance (l _CE ′+Δl ₂ ) is less than the distance l _R , that is, if the rear cursor C _E does not deviate from the right edge of the measurement range 31A, change the distance to l _CE (l _CE ′+Δl ₂ ) (Step P ₅₇₎ . ). This case is shown in the waveform diagrams of FIGS. 11b and 11c. When the distance (l _CE ′+Δl ₂ ) is less than the distance l _R , the waveform diagram in FIG. 11 b shows the distance (l _CE ′+Δl ₂ ).
is a waveform diagram when is equal to the distance l _R. In addition,
Figure 11a is the same waveform diagram as Figure 9a. In step _P56 , if it is determined that the rear cursor C _E is out of the right end of the measurement range 31A, the distance l _CE is set as l _CE = l _R. (Step _P56 ), cursor display processing is performed (Step _P53 ), and even if the rotary switch is operated, the cursor is stopped in the state shown in FIG. 11c.

On the other hand, if it is determined in step _P54 that the direction in which the rotary switch is operated is in the negative direction, that is, in the direction of reducing the cursor width, the amount of operation is read (step _P59 ), and then the distance is calculated from the distance l _CE '. It is determined whether the value obtained by subtracting Δl ₂ is greater than l _CS (step P ₆₀ ). This judgment is made as to whether the operating amount of the rotary switch (distance Δl ₂ ) exceeds the current cursor width l _W '. If it is determined in step P ₆₀ that the distance Δl ₂ is less than or equal to the cursor width l _W ′, the distance l _CS is left as is, the distance l _W is the distance (l _W ′ − Δl ₂ ), and the distance l _CE is the distance ( l _CE ′−Δl ₂ ) (step P ₆₁ ), and cursor display processing is performed. Processing in step P ₆₁ moves the cursor C _E to a distance Δl ₂
This process reduces the cursor width by moving the cursor to the left.

If it is determined in step P ₆₀ that the distance (l _CE ′−Δl ₂ ) is greater than the distance l _CS , the distances l _CS and l _CE are set to the distance l _CS , and the distance l _W is set to 0 ( Step P ₆₂ ),
Performs cursor display processing. The process of step _P62 is a process of superimposing the next cursor C _E on the previous cursor C _S so that only one cursor is displayed.

In this way, by operating the rotary switches of the cursor start point setting section 34 and the cursor width setting section 35, the cursor position can be freely moved, and a desired area can be further freely selected from the measurement range. .

() Mark Adding Means Next, a mark adding means for adding a mark to an arbitrary waveform will be explained. In this embodiment, an example in which the letter "A" is added to the surface wave S will be described. First, the measurement start point setting section 36 and the measurement range setting section 37 display the reflected waves T to B _S shown in FIG. 21 on the liquid crystal display section 31 according to the process described in the measurement range display means described above.
After performing this display, the mark setting process is executed by pressing the mark key switch 33b of the mark setting section 33 shown in FIG. The mark setting process will be described with reference to flowcharts shown in FIGS. 12, 15, and 16 and plan views of the display section shown in FIGS. 13 and 14.

When the mark key switch 33b is pressed, the 13th
As shown in the figure, the message ``Please send an echo'' is first displayed on the display screen. Since such display means are well known, their explanation will be omitted. At the same time, a previous cursor C _S and a subsequent cursor C _E are displayed on the display screen. The initial display state of these cursors may be in any state, but for example, if the previous cursor C _S is at the left end of the display surface, and the width l _W of the cursor is an appropriate ratio of the measurement range l _R , For example, if it is about 1/5, the echo selection operation becomes easy. Next, the cursor start point setting section 34 and the cursor width setting section 35 operate the display screen to execute the processing in the cursor display means described above, and as shown in FIG. 13, the front cursor C _S and the rear cursor C _E and performs cursor processing to sandwich the reflected wave S (steps in Figure 12).
_P71 ).

Next, the maximum peak value of the waveform in the area sandwiched between the cursors C _S and _CE is selected and extracted (step P ₇₂ ). This selection is made as follows. That is, distance l _CS , l _CE and distance l _S
The sum of the values (l _CS + l _S ) and (l _CE + l _S ) are the values L _S , L _E
Then, these are the addresses of the waveform memory 23.
It can be made compatible with A _M(LS) and A _M(LE) . This correspondence can be obtained by converting A _M(LS) ^* = β·L _S ...(9) A _M(LE) ^* = β·L _E ...(10) into integers. The address of the waveform memory 23 obtained in this way
The maximum value of the data D _(o) stored at the address between A _M(LS) and address A _M(LE) is determined by known means. Then, the address storing the maximum value is determined (step _P73 ). Let this address be address A _M(p) . Then the address
The distance l _{(MK ) of A M(p} ) is determined from the relationship between the waveform memory 23 and the distance using the following equation (step P ₇₄ ).

l _(MK) = A _M(p) /β (11) Next, a mark to be added to the reflected wave S is selected (step P ₇₅ ). This mark selection is performed as follows. When the set key switch 33c of the mark setting section 33 is pressed (this operation is performed when the cursor
This is done when the reflected wave S is sandwiched between C _S and _CE . ), the distance l _(MK) is registered at a predetermined address in the RAM 27, and the message ``SET MARK'' is displayed on the display screen as shown in FIG. Therefore,
In accordance with this display, the character "A" is selected by pressing the key switch for the character "A" among the character key switches 33d of the mark setting section 33. That is, characters A to Z in the ROM 28 are stored, and each address of these is A _C(0) to
If A _C(25) , pressing each key switch of the character key switch 33d selects the corresponding address. This character selection operation will be explained with reference to the flowchart shown in FIG.
Note that the character data is stored at a predetermined address in the ROM 27.

First, it is monitored whether any of the character keyswitches 33d has been pressed (step P81), and if it is determined that it has been pressed, the address corresponding to the pressed key switch is specified (step _P81 ). ₈₂ ), then the character data stored at the designated address is read out (step _P83 ).

The process of step _P75 in the flowchart shown in FIG. 12 has been described above. When the letter "A" is extracted as described above, next, means for displaying the letter "A" on the display screen is executed. Such display processing means will be explained with reference to the flowchart shown in FIG.
This process is a process in which the distance l _(MK) obtained in step _P74 in the mark setting process shown in FIG. 12 is made to correspond to the address A _{L (MK)} of the display memory 32m.

First, it is determined whether the distance l _(MK) is within the measurement range (displayed range) (step P ₁₀₁ ).
This determination is made based on l _S ≦l _(MK) ≦ (l _S +l _R ).
Distance l If _MK is outside the measurement range, no display will be made. When it is within the measurement range, calculate which address in the display memory this distance l _(MK) corresponds to (step P ₁₀₂ ). This calculation is performed using the following formula.

A _L(MK) ^* =K _L ×l _(MK) −l _S /l _R ...(12) As mentioned above, K _L is the display memory of 32 m.
is the total number of addresses. Calculated number A _L(MK) ^*
By converting to an integer (step P ₁₀₃ ), the address
A _L(MK) is determined. Then this address
A position corresponding to _L(MK) , i.e., Fig. 13, 1
In order to display the letter "A" extracted in step _P75 of FIG. 12 at the position corresponding to the peak position of the reflected wave S on the horizontal axis (distance axis or time axis) in FIG. letter "A"
Set the data (Step P ₁₀₄ ). Then, under the control of the controller 32, the address
A Display the letter “A” that corresponds to _L(MK) (procedure
_P105 ). This display is located at a position that does not overlap with the waveform display.
For example, it is desirable to place it on the upper part of the display screen.

Once the letter "A" is added to the reflected wave S by the mark display process described above, from now on, even if the measurement range is changed, the already registered distance l _(MK) will be used and step P will be applied each time the measurement range is changed. If the processes ₁₀₁ to _P105 are executed, the letter "A" will always be displayed accompanying the reflected wave S.

One display example will be explained below using a diagram. FIGS. 17a to 17e are plan views of the display section. 17th
Figure a is a diagram displayed on a display unit so that reflected waves T, S, and B can be observed. Among the reflected waves displayed in this way, as shown in FIG. 17b, the letter "A" is displayed above the reflected waves S by the above-described processing. Incidentally, the letter "B" is added to the upper part of the reflected wave B by the same process. FIG. 17c shows the display screen when measuring near the reflected wave S by changing the measurement range. In this case as well, the letter "A" is given to the reflected wave S by the process shown in the flowchart shown in FIG. If the gain is reduced in this state or a contact failure occurs in the probe 2, the reflected wave S will no longer be displayed as shown in FIG. 17d.
However, the letter "A" remains displayed unless a failure occurs in the ultrasonic flaw detector.
Therefore, when a display screen as shown in FIG. 17d appears, it can be determined that the gain is insufficient or the probe 2 has a poor contact. Figure 17c
If you want to measure the vicinity of reflected wave B from the state shown in Fig. 17, by operating the measurement start point setting section 36 to move the waveform, the reflected wave B and the letter "B" will be displayed as shown in Fig. 17e. appear. Thereby, it can also be confirmed that this reflected wave is reflected wave B. That is, in order to display the reflected wave B, it is sufficient to operate the measurement start point setting section 36 until the letter "B" appears regardless of the waveform, making the operation extremely easy.

() Mark search means Here, Fig. 18 shows a means for displaying when the reflected wave S or reflected wave B marked with the letter "A" or the letter "B" as described above is not displayed on the display section. This will be explained with reference to the flowchart shown. This kind of display is not limited to cases where you want to measure the vicinity of reflected wave B after measuring the vicinity of reflected wave S as described above, but also when you want to measure the vicinity of reflected wave B next time. This is also necessary when confirming which range you are currently in.

It is now assumed that the letters "A" and "B" are assigned to the reflected wave S and the reflected wave B, respectively, and that neither reflected wave is displayed on the liquid crystal display section 31. If you want to display the reflected wave S here, first press the search key switch 3.
Press 3e. As a result, the measurement range automatic setting process shown in the flowchart shown in FIG. 18 becomes executable. Press the search key switch 33e and then press the key switch labeled "A". Thereby, the character of the key switch pressed by the CPU 26 is identified (step P ₁₁₁ ), and it is determined whether this character matches the character already set and stored in the RAM 27 (step P ₁₁₂ ). If they match, read out the distance l _(MK) of the peak of the reflected wave S corresponding to this letter "A" from the RAM 27 (step P ₁₁₃ ), and select the distance l _(MK) that has already been set. Calculate the distance l _R (step P ₁₁₄ ).

l _S = l _(MK) -1/2l _R ...(13) When normal waveform display is performed using the new distance l _S determined by equation (13), the reflected wave S will be It is displayed at the center of the display screen of the liquid crystal display section 31 along with "A". In this case, the reflected wave S
Even if it is not displayed due to lack of gain or the like, the letter "A" is displayed, so the position of the reflected wave S can be reliably grasped.

If it is determined in step _P112 that the mark MK does not match the previously set mark, a mismatch process is executed (step _P115 ). Various types of processing can be considered for this mismatch processing, such as displaying a message to the effect that there is a mismatch.

In this way, in this embodiment, specific characters are given to predetermined reflected waves, so
A predetermined reflected wave that serves as a measurement guideline can be reliably recognized, allowing the observer to accurately grasp the location currently being measured, and if no reflected wave is obtained, the gain It is possible to immediately determine whether there is a lack of water, poor contact of the probe 2, or a malfunction of the ultrasonic flaw detector. moreover,
If the reflected wave with the text attached is not displayed and you want to display it, you can easily display it with a simple operation, which in turn facilitates the flaw detection operation.

In the above embodiments, a liquid crystal display section was used as an example of the display section, but the present invention is not limited to the liquid crystal display section, and ordinary cathode ray tubes, plasma displays, etc. can be used. In addition, although we have explained an example of adding letters (alphabet) to reflected waves, the mark may be any other kind of letters, symbols, or signs, and especially if accurate measurement is required, The exact position can be indicated by adding an arrow to the line segment corresponding to the peak position of the wave. Furthermore, although an example has been described in which a character is set using the key switch of the character concerned, the setting is not limited to this, and may be performed using a rotary switch, or may be set using a combination of key switches 0 to 9 as shown in Figure 2. You may also do this. Furthermore, although we have explained an example of displaying the reflected waves T to B _S when adding a mark, if a predetermined reflected wave is known, it is not necessary to display all of the reflected waves T to B _S. A limited range including the following may be displayed. In addition, in this example, marks were added to the reflected waves S and B from the surface and bottom of the object to be inspected 1, but it is also effective to add marks to the defective waves for test pieces with standard defects. It is. or,
Although an example has been described in which a cursor is displayed along with a message instructing selection of a predetermined reflected wave, the cursor can also be displayed at all times.

〔Effect of the invention〕

As described above, in the present invention, since a mark is attached to a predetermined reflected wave, it is possible to reliably recognize the reflected wave as a guide for measurement.
As a result, the observer can accurately grasp the current observation position, and if no reflected waves are obtained, the observer can determine whether the ultrasonic flaw detector is malfunctioning or not. You can avoid wasting time and effort. Furthermore, if the reflected wave with a mark is not displayed, it can be displayed with a simple operation, thereby facilitating the flaw detection operation.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an ultrasonic flaw detector according to an embodiment of the present invention, FIG. 2 is a layout diagram of a key switch in the mark setting section shown in FIG. 1, and FIG. 3 is a waveform diagram of a part of a reflected wave. FIG. 4 is a block diagram of the waveform memory shown in FIG. 1, FIG. 5 is a waveform diagram explaining the measurement range, cursor display, and marking, and FIGS.
The figures are flowcharts explaining the operation of measurement range display and cursor display, Figure 8 is a flowchart explaining cursor position processing, and Figures 9 a, b, c, d, and e are displays for cursor position processing. Waveform diagrams; FIG. 10 is a flowchart explaining cursor width processing; FIGS. 11a, b, and c are display waveform diagrams for cursor width processing; FIG. 12 is a flowchart explaining marking; FIG. 13 and FIG. 14 is a plan view of the display surface in the case of marking,
15 and 16 are flowcharts explaining in detail a part of the flowchart shown in FIG. 12, and FIGS. 17a, b, c, d, and e are display screens explaining reflected waves with marks added. 18 is a flowchart explaining the operation for making a reflected wave with a mark appear in the center of the display section, FIG. 19 is a block diagram of a conventional ultrasonic flaw detector, and FIG.
FIG. 0 is a cross-sectional view for explaining the water immersion method, and FIG. 21 is a waveform diagram of reflected waves. DESCRIPTION OF SYMBOLS 1...Object to be inspected, 1f...Defect, 2...Ultrasonic probe, 5...Transmitter section, 6...Receiver section, 21...
...Ultrasonic flaw detector, 22...A/D converter, 23...
... Waveform memory, 24 ... Address counter, 25
...Timing circuit, 26...CPU, 27...
RAM, 28...ROM, 30...Keyboard input section, 31...Liquid crystal display section, 32...Display controller, 32m...Display memory, 33...Mark setting section, 34...Cursor start point setting section, 35 …
...Cursor width setting section, 36...Measurement start point setting section,
37...Measurement range setting section.

Claims (1)

[Claims] 1. A transmitter that outputs a predetermined pulse to an ultrasound probe, a receiver that receives a signal from the ultrasound probe, and a receiver that receives a signal from the ultrasound probe. The ultrasonic flaw detector includes a waveform memory that sequentially stores the input signal received by the receiving unit in addresses at a predetermined sampling period, and a display unit that displays the waveform of the signal based on the signal. a display memory for storing data to be displayed, a selection means for selecting an address of the waveform memory according to a measurement range to be displayed on the display section, and a selection means for storing data at the address selected by the selection means in the corresponding display memory. data transfer means for transferring data to an address; waveform display means for displaying data in the display memory on the display section; reflected wave selection means for selecting a predetermined reflected wave from among the displayed reflected waves; calculation means for calculating the distance of the wave; address determination means for determining the address of the display memory corresponding to the calculated distance; and a mark for displaying a predetermined mark at a position on the display section corresponding to the determined address. An ultrasonic flaw detector comprising: a display means; and a mark search means for changing the measurement range starting point and displaying the mark on the display when the mark is not displayed on the display. Mark display device. 2. In claim 1, the reflected wave selection means includes cursor display means for displaying a cursor before and after the predetermined reflected wave, and a maximum value stored between these two cursors in the waveform memory. 1. A mark display device for an ultrasonic flaw detector, characterized in that the mark display device is comprised of arithmetic means for determining an address in which the address is stored. 3. The mark display device for an ultrasonic flaw detector according to claim 1, wherein the predetermined mark is selected by mark selection means from a plurality of marks stored in a storage section. 4. In claim 1, the mark search means includes another calculation means that calculates a starting point of a measurement range based on the distance calculated by the calculation means and the measurement range, and another calculation means. A mark display device for an ultrasonic flaw detector, comprising command means for commanding calculations.