Abstract:
An ultrasonic inspection apparatus obtaining information on the interface of a sample as digital waveform data for any “unit measurement range” provided with at least two data memories and controlled by a scan state monitoring signal showing the scan state of a unit measurement range belonging to a first group or a unit measurement range belonging to a second group and a comparator-register/memory-control-circuit outputting the scan state monitoring signal to the at least two data memories, the operating states of the two data memories being controlled by the scan state monitoring signal to alternate between writing of digital waveform data and readout of digital waveform data, whereby digital type ultrasonic inspection and a high speed data transfer not having an effect on the data sampling at the time of scanning in a specific direction in any scan are realized, the dead time at the time of scanner scanning by transfer of a large volume of data is reduced to zero, and high speed planar scanning is performed.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to an ultrasonic inspection apparatus, and more particularly, relates to a digital type ultrasonic inspection apparatus reducing the dead time in the scan operation of a scanner to zero by utilizing large-volume data transfer.  
           [0003]    2. Description of the Related Art  
           [0004]    A conventional general analog-type ultrasonic inspection apparatus will be explained first referring to FIG. 3. A sample or an inspected object  101  is placed in the water of a water tank  102 . The water tank  102  is placed on a measurement stage  103 . A scanner  104  is placed on the water tank  102 . The scanner  104  is attached to the measurement stage  103 . The scanner  104  is comprised of an X-axis scanner  105 , Y-axis scanner  106  and Z-axis scanner  107 . The Z-axis scanner  107  is provided at its bottom with an ultrasonic probe  108 . The tip of the ultrasonic probe  108  faces the sample  101  at the bottom side. The X-axis, Y-axis and Z-axis as axes of the scan operation of the scanner  104  are perpendicular to each other. The operations of the X-axis scanner  105 , Y-axis scanner  106  and Z-axis scanner  107  are controlled by a motor controller  109 . Under the control of the motor controller  109 , the scanner  104  independently scans along the X-axis, Y-axis and Z-axis. The motors of the scanner  104  for the three axes have encoders  110  respectively. The encoders  110  for the X-axis, Y-axis and Z-axis output trigger signals indicating the positional coordinates on the X-axis, Y-axis, and Z-axis by resolutions set in advance.  
           [0005]    A pulser/receiver circuit  111  transmits a drive pulse signal to the ultrasonic probe  108  and receives a reflection echo signal from the ultrasonic probe  108 . An analog peak detector  112  extracts the reflection echo signal relating to a desired inspection surface from the reflection echo signal received through a gate circuit and holds the peak value. An A/D conversion circuit  113  converts the analog peak values of the reflection echo signal to digital values while linking them with the trigger signals output from the encoders  110 . A computer  114  is comprised of a CPU  115 , keyboard  116 , and main memory  117 . The computer  114  controls the motor controller  109 . Further, the computer  114  stores the digital peak values of the reflection echo signal in the main memory  117  through a data bus  118  and further displays the peak values on a monitor  119  in accordance with the planar coordinates. The data stored in the main memory  117  is used for various types of data processing. In addition, the pulser/receiver circuit  111  is similarly connected to an oscilloscope  120 .  
           [0006]    In the ultrasonic inspection apparatus shown in FIG. 3, the X-axis scanner  105  and the Y-axis scanner  106  scan planarly, while the ultrasonic probe  108  transmits an ultrasonic pulse toward the sample  101  based on the drive pulse signal given from the pulser/receiver circuit  111 . The ultrasonic probe  108  receives the reflection echo signal returned from the sample  101 . Using the received reflection echo signal, the analog peak detector  112  holds the peak values of the reflection echo signal near the desired inspection surface. The A/D conversion circuit  113  uses position trigger signals output from the encoders  110  to sample the data. Next, the computer  114  obtains the data, then displays an image based on the obtained signal on the monitor  119 . In this way, a picture of the desired inspection surface in the sample  101  is obtained.  
           [0007]    There are two methods as shown in FIG. 2A and FIG. 2B for the X-axis and Y-axis planar scan by the X-axis scanner  105  and Y-axis scanner.  
           [0008]    The method of measurement shown in FIG. 2A includes the step of having the A/D conversion circuit  113  use the position trigger signals output from the encoders  110  during a two-directional scan to sample data and the step of having the computer  114  display an image of the inspection surface echo signal obtained on the monitor  119 . In this way, a picture of the desired inspection surface of the sample  101  is obtained on the monitor  119 . This measurement method requires that before the feed scan in the Y-direction by the Y-axis scanner  106  is completed and the return scan of the X-direction by the X-axis scanner  105  is started, the transfer of data from the A/D conversion circuit  113  to the computer  114  be completed and the A/D conversion circuit  113  can sample the data during the return scan.  
           [0009]    The method of measurement shown in FIG. 2B includes the step of having the A/D conversion circuit  113  use the position trigger signals output from the encoders  110  to sample data during the scan in the same direction at all times for the X-direction, and the step of having the computer  114  display an image based on the obtained inspection surface echo signal on the monitor  119 . In this way, a picture of the desired inspection surface of the sample  101  is obtained on the monitor  119 . This measurement method makes it possible to simultaneously perform a feed scan in the Y-direction by the Y-axis scanner  106  and return scan in the X-direction by the X-axis scanner  105 . Further, it requires that, before the start of the next X-axis outgoing scan, the transfer of the data from the A/D conversion circuit  113  to the computer  114  be completed and the A/D conversion circuit  113  can sample data at the time of the next outgoing scan.  
           [0010]    The number of the two-directional scans in the X-direction in the scan method of FIG. 2A is half that of the number in the scan method of FIG. 2B. Accordingly, in general, it is known that the scan time in FIG. 2A is shorter than the scan time in FIG. 2B.  
           [0011]    As explained above, the analog type ultrasonic inspection apparatus shown in FIG. 3 can extract the peak values of a reflection echo signal of a desired inspection surface and produce a picture of the peak values. This ultrasonic inspection apparatus, however, requires several analog peak detectors when trying to simultaneously obtain peak values of reflection echo signals of several inspection surfaces. Further, when the ultrasonic inspection apparatus has several analog peak detectors, the problems of variations in the circuit characteristics among the detectors and the detection gate technology for reliably separating the echoes arise.  
           [0012]    To solve these problems, a digital type ultrasonic inspection apparatus has been proposed. This digital type ultrasonic inspection apparatus uses a high speed A/D converter to convert the reflection echo signals to digital data and performs the gating and peak detection of the reflection echo signals at the desired positions digitally to instantaneously obtain information of several inspection surfaces.  
           [0013]    [0013]FIG. 4 shows an example of the digital type ultrasonic inspection apparatus. In FIG. 4, components in common with those of the analog type ultrasonic inspection apparatus explained above are assigned the same reference numerals for convenience in explanation. The digital type ultrasonic inspection apparatus has a peak detection program  121  within the memory of the computer  114  instead of the analog peak detector  112  of the analog type ultrasonic inspection apparatus. Further, instead of the A/D conversion circuit  113 , an A/D converter  122  is provided. The A/D converter  122  is comprised of an A/D conversion circuit  122   a  and a memory  122   b.    
           [0014]    In the digital type ultrasonic inspection apparatus shown in FIG. 4, the A/D converter  122  samples the waveform data of several hundred to several thousand of points from the surface to the bottom of the sample  101  for each position trigger signal output from the encoders  110 . The large number of waveform data sampled is stored in the memory  122   b . The computer  114  performs the gating of the waveforms and the detection of the peak values of the desired inspection surface for the waveform data stored in the main memory  117  by the peak detection program  121 . And it displays the digital peak values of the reflection echo signal of the desired inspection surface on the monitor  119 . Due to this, a picture of an inspection surface in the sample  101  is obtained. The above-mentioned two planar scan measurement methods of FIG. 2A and FIG. 2B can be similarly used in the digital type ultrasonic inspection apparatus as well.  
           [0015]    As explained above, in both the analog type and digital type ultrasonic inspection apparatus, the individual sampled data obtained based on the position trigger signals output from the encoders  110  are arranged as shown in FIGS. 2A and 2B. In particular, in the analog type ultrasonic inspection apparatus, peak detection values in the gates at the positions X 1−1 , X 1−2 , . . . , X m−n  corresponding to the arrangement of the sampling positions, that is, the digital peak values, are sampled at those positions. The digital peak values are for example 1 byte of peak value data.  
           [0016]    On the other hand, in the digital type ultrasonic inspection apparatus, since a program is used for peak detection, digital data of waveforms at the positions X 1−1 , X 1−2 , . . . , X m−n  corresponding to the arrangement of the sampling positions, for example, the waveform data of several hundred to several thousands of points (for example, unit: bytes), are sampled at those positions. Therefore, the number of points of data sampled in the digital type ultrasonic inspection apparatus becomes several hundred to several thousand times the amount of data sampled in the analog type ultrasonic inspection apparatus. Therefore, when configuring the digital type ultrasonic inspection apparatus, in particular in the case of FIG. 2A, it is required that before the feed scan in the Y-direction and the return scan in the X-direction are started, the transfer of data from the memory  122   b  of the A/D converter  122  to the computer  114  be completed and the A/D converter  122  can sample data at the time of the return scan. Therefore, the digital type ultrasonic inspection apparatus requires technology for a high-speed data transfer system.  
           [0017]    In the above-explanation, the problems in the planar scan by the ultrasonic inspection apparatus were explained. However, the problems are not limited to the planar scan. The above problems similarly occur in spiral rotational scans or inclined scans by the ultrasonic inspection apparatus.  
         SUMMARY OF THE INVENTION  
         [0018]    An object of the present invention is to provide an ultrasonic inspection apparatus of a digital type realizing a system of high speed data transfer not affecting data sampling at the time of scanning in, for example, a two-directional type planar scan, enabling transfer of a high volume of data, and thereby reducing the dead time at the time of scanner scans to zero to enable measurement by high speed scans.  
           [0019]    The ultrasonic inspection apparatus according to the present invention is configured as follows to achieve the above object.  
           [0020]    The first ultrasonic inspection apparatus of the invention scans a sample by an ultrasonic probe by scanners of at least two axes, transmits an ultrasonic wave from the ultrasonic probe toward the sample, and receives the reflection echo signal returning from the sample. The waveforms received at the A/D converter are converted to digital waveform data with each sampling position trigger output from the encoders of the scanners. The digital waveform data output from the A/D converter is transferred to the computer where it is processed in various ways. The ultrasonic inspection apparatus is further provided with at least two data memories controlled in operating states by a scan state monitoring signal setting a unit measurement range in accordance with the operating state in advance and changing with each change of the unit measurement range when continuously scanning a plurality of unit measurement ranges and a memory controller for receiving as input a trigger signal based on the detection values of the above encoders, changing the scan state monitoring signal with each change of the unit measurement range, and outputting the scan state monitoring signal to the at least two data memories. In the above configuration, the memory controller controls the operation states of the at least two data memories based on the scan state monitoring signal, that is, performs control to alternately write digital waveform data from the A/D converter to a data memory, read digital waveform data from a data memory by the computer, and transfer data to the memory of the computer.  
           [0021]    The second ultrasonic inspection apparatus that has the configuration of the above-mentioned first apparatus, is preferably configured such that the memory controller is provided with a counter for counting the number of the position triggers determined by encoders corresponding to the sampling position coordinates when scanning a unit measurement range, a comparator-register for comparing the count of the counter and the number of position triggers in the set unit measurement range and outputting a signal for changing the scan state monitoring signal each time the results of the comparison are a match, and a memory-control-circuit for outputting a scan state monitoring signal for controlling the operating states of the at least two data memories based on the signal given from this comparator-register.  
           [0022]    The third ultrasonic inspection apparatus that has the configurations of the above apparatuses, is preferably configured such that the at least two data memories are comprised of a first data memory and second data memory and the memory controller outputs a scan state monitoring signal of a first state and second state. When the scan state monitoring signal is the first state, it is possible to write data into the first data memory and read out data from the second data memory. The digital waveform data outputted from the A/D converter is continuously written into the first data memory, and simultaneously the digital waveform data is continuously read out from the second data memory in the computer. When the scan state monitoring signal is the second state, it is possible to read out data from the first data memory and write data into the second data memory. The digital waveform data obtained by sampling operation of the A/D converter is continuously written into the second data memory, and simultaneously the digital waveform data is continuously read out from the first data memory.  
           [0023]    The fourth ultrasonic inspection apparatus that has the configuration of the above apparatuses, is preferably configured such that the second data memory write-enabled by the change of the scan state monitoring signal from the first state to the second state is continuously written with data from the digital waveform data after the final digital waveform data in the first data memory write-enabled when the scan state monitoring signal is the first state so as to preserve the continuity of data stored between the first data memory and second data memory.  
           [0024]    The fifth ultrasonic inspection apparatus that has the configuration of the above apparatuses, is preferably configured such that the computer is provided with means for storing the digital waveform data read out from the at least two data memories at addresses corresponding to the sampling positions on the memory of the computer. Due to this means, the data is transferred continuously from the data memories to addresses on the memory of the computer by direct memory access (DMA).  
           [0025]    In the configuration of the ultrasonic inspection apparatus according to the present invention, the waveform data obtained by the measurement is processed digitally. The reflection echo returned from the inspected object or the sample is received by an ultrasonic probe and converted into an electric analog signal. The analog signal is converted (digitalized) to digital waveform data at several hundred to several thousand of points of the waveform from the sample surface to bottom using a high speed A/D converter for each position trigger corresponding to a sampling position output from the encoders of the scanners.  
           [0026]    In the digital type ultrasonic inspection apparatus according to the present invention, the converted digital waveform data is temporarily stored in the data memory section, then transferred to the memory of the computer for storage. The data memory section is comprised of at least two data memories. In the measurement scan, since a large amount of digital waveform data of several hundred to several thousand of points is prepared and stored, a unit measurement range corresponding to a scan operation is set and a data memory for storing the waveform data is selected and temporarily stored-in based on a switching operation by the memory controller. Due to this, it is possible to continuously perform measurement scans, sample waveform data by the A/D converter, and transfer digital waveform data from the data memories to the computer side memory by the computer without stopping. Therefore, it is possible to eliminate loss time due to transfer of data.  
           [0027]    When the sample scan at the ultrasonic inspection apparatus according to the present invention is a planar scan for a representative XY plane, a two-dimensional scan by the X-axis scanner and Y-axis scanner is performed. During the two-dimensional scan, it is possible to continuously sample waveform data through the A/D converter and transfer digital waveform data from the data memories to the computer side memory by the computer without stopping. In this case, after the first line scan operation in the X-direction by the X-axis scanner and the feed operation in the Y-direction by the Y-axis scanner after that, without waiting for the end of the transfer of the first line digital waveform data, a second line X-direction scan and the later Y-direction feed become possible, so it is possible to eliminate loss time due to transfer of data.  
           [0028]    In the case of a planar scan of the XY plane, the above-mentioned “unit range of measurement” is, for example, one line in the X-direction. In this case, the odd numbered one-line scan portions become odd-numbered measurement ranges, while the even-numbered one-line scan portions become even-numbered one-line scan portions. The changes in the two signal shapes of a scan state monitoring signal arise in accordance with changes from the even-numbered measurement range from the odd-numbered measurement range or changes from the odd-numbered measurement range from the even-numbered measurement range. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0029]    These and other objects and features of the present invention will become clearer from the following description of the preferred embodiments given with reference to the attached drawings, wherein:  
         [0030]    [0030]FIG. 1 is a block diagram of a representative embodiment of an ultrasonic inspection apparatus according to the present invention;  
         [0031]    [0031]FIG. 2A is a schematic view of a two-dimensional scan of an X-axis scanner and Y-axis scanner and the sampling positions of digital waveform data at that time and shows the case of a two-directional scan;  
         [0032]    [0032]FIG. 2B is a schematic view of a two-dimensional scan of an X-axis scanner and Y-axis scanner and the sampling positions of digital waveform data at that time and shows the case of a one-directional scan;  
         [0033]    [0033]FIG. 3 is a block diagram of a conventional analog type ultrasonic inspection apparatus; and  
         [0034]    [0034]FIG. 4 is a block diagram of a conventional digital type ultrasonic inspection apparatus. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0035]    Preferred embodiments of the present invention will be described in detail below while referring to the attached figures. A representative embodiment of the present invention will be explained first with reference to FIG. 1 and FIG. 2A. This embodiment shows the configuration of a digital type ultrasonic inspection apparatus. In this apparatus, the X-axis scanner and Y-axis scanner perform a two-directional type two-dimensional scan, that is, a planar scan. That is, this embodiment explains an example of measurement by scanning a plane (XY plane) defined by the X-axis and Y-axis. Components shown in FIG. 1 being as same as the components explained in FIG. 3 and FIG. 4 above are assigned the same reference numerals.  
         [0036]    The configuration will be explained with reference to FIG. 1. A sample  101  is placed in the water of a water tank  102 . A scanner  104  is placed at the water tank  102 . The water tank  102  is placed on a measurement stage  103 . The scanner  104  is attached to the measurement stage  103 . The scanner  104  is comprised of an X-axis scanner  105  for performing a scan in the X-direction, a Y-axis scanner  106  for performing a scan in the Y-direction, and Z-axis scanner  107  for performing a scan in the Z-direction. The Z-axis scanner  107  is provided at its bottom with an ultrasonic probe (ultrasonic sensor)  108 . The tip of the ultrasonic probe  108  faces the sample  101 . The scan X-axis, Y-axis and Z-axis of the scanner  104  are perpendicular to each other. The operations of the X-axis scanner  105 , Y-axis scanner  106 , and Z-axis scanner  107  of the scanner  104  are controlled by a motor controller  109 . Based on the control of the motor controller  109 , the scanner  104  performs scan operations along the three axes, which are mutually independent and perpendicular. The motors of the three axes have encoders  110  respectively. The encoders  110  for the X-axis, Y-axis and Z-axis output signals of position triggers corresponding to the positional coordinates on the three axes. The encoders  110  are provided with a counter  131 . A pulser/receiver circuit  111  transmits an ultrasonic wave pulse use drive signal to the ultrasonic probe  108  and receives a reflection echo signal from the ultrasonic probe  108 . The received reflection echo signal is input to an A/D converter  132 . The A/D converter  132  is comprised of an A/D conversion circuit  132   a  and a memory  132   b . The memory  132   b  of the A/D converter  132  is further provided with at least two data memories  133  and  134 . The number of the data memories is preferably two, but is not limited to two. The data memories  133  and  134  store the sampled and digitized waveform data. The storage capacities of the data memories  133  and  134  are determined in accordance with the unit measurement ranges as discussed later (for example, measurement range of one scan line in X-direction).  
         [0037]    The computer  140  is provided with a CPU  141 , keyboard  142 , and main memory  143 . The computer  140  is further provided with a monitor  144 . The computer  140  is additionally provided with a comparator-register/memory-control-circuit  151 . The comparator-register/memory-control-circuit  151  receives as input the output signal from the counter  131  (signal relating to count) and controls the drive states of the data memories  133  and  134  based on the scan state monitoring signal output to the data memories  133  and  134 . It also controls the transfer of the stored data to the CPU  141 . The internal memory of the computer  140  is provided with a peak detection program. The peak detection program is executed by the CPU  141  and thereby forms a peak detector. The computer  140  controls the operations of the motor controller  109 , counter  131 , and comparator-register/memory-control-circuit  151 . In addition, the computer  140  gives data relating to the number of position triggers in a preset unit measurement range to the comparator-register/memory-control-circuit  151 . Further, the counter  131  counts the number of position triggers determined by the encoders  110  corresponding to the sampling position coordinates at the time of scanning the unit measurement range.  
         [0038]    The comparator-register/memory-control-circuit  151  compares the count of the counter  131  and the number of the position triggers in the set unit measurement range. The comparator-register/memory-control-circuit  151  outputs the above scan state monitoring signal to the two data memories  133  and  134  each time the results of comparison of the two are a match. The scan state monitoring signal, as one example, uses for example one multiple of one scan line (in general a whole number multiple) as the “unit measurement range” and indicates the scan state of odd-numbered measurement ranges (in general measurement ranges belonging to a first group) or even-numbered measurement ranges (in general measurement ranges belonging to a second group) when continuously scanning a plurality of measurement ranges.  
         [0039]    The comparator-register/memory-control-circuit  151  more particularly is comprised of a comparator-register  151   a  and a memory-control-circuit  151   b . The comparator-register  151   a  compares the count of the counter  131  and the number of position triggers in the set unit measurement range and provides a coincidence signal to the memory-control-circuit  151   b  when the results of comparison are a match. The memory-control-circuit  151   b , based on the coincidence signal from the comparator-register  151 A, considers the operating states of the two data memories  133  and  134  and outputs the scan state monitoring signal determining the operating states of the two data memories  133  and  134  to the data memories  133  and  134 . The operating states of the two data memories  133  and  134  are switched by the scan state monitoring signal. The above counter, comparator-register, and memory-control-circuit form a memory control means for controlling the operating states of the data memories  133  and  134 .  
         [0040]    Next, the sequence at the time of operation of the digital type ultrasonic inspection apparatus having the above configuration will be explained. In this embodiment, the above “unit measurement range” is as one example made one scan line in the X-direction.  
         [0041]    The ultrasonic probe  108  transmits a pulse-like ultrasonic wave toward the inside interface of the sample  101  (XY plane inside sample) and receives a reflection echo from the sample  101  while moving from X 1−1  to X 1−n  along with the scan in the X-direction (scan from left to right). During this time, the encoder  110  in question outputs trigger signals at the preset sampling positions X 1−1 , X 1−2 , X 1−3 , . . . , X 1−n . At each position trigger, the A/D converter  132  samples the waveform data for example from the surface to the bottom of the sample (for example, 1000 points (unit: bytes) of data). The total number of points of the waveform data sampled at the time when one line finishes being scanned from X 1−1  to X 1−n  (n=number of position triggers, for example, n=1000) becomes (the number of waveform data ×n=1000×1000)=1 Megabyte. This is 1000 times greater than the number of data when the analog type ultrasonic inspection apparatus samples peak values obtained by peak value detection at an above sampling position under the same conditions.  
         [0042]    Linked with the scan of the first line and the sampling of the waveform data, the comparator-register/memory-control-circuit  151  is in the middle of measuring the first line waveform data, so outputs a write enable signal to the data memory  133  as the scan state monitoring signal to permit writing of digital waveform data from the A/D converter  132  and simultaneously outputs a read enable signal to the data memory  134  to permit reading of data from the computer  140  and transfer of data to the main memory  143 . The A/D converter  132  writes the converted digital waveform data sampled continuously to the data memory  133 . At this time, since it is in the middle of measurement of the first line, the data memory  134  does not store the desired waveform data, so the computer  140  does not read out the digital waveform data from the data memory  134 .  
         [0043]    Next, the end of the feed operation of the pitch (Y 1 ) corresponding to the distance between X 1−1  and X 1−2  by the Y-axis scanner  106  of the scanner  104  is awaited, then the X-axis scanner  105  performs a return scan (scan from right to left) while passing through the sampling positions of X 2−n , X 2−(n−1) , X 2−(n−2) , . . . , X 2−1  from X 1−n  to the direction of X 1−1 .  
         [0044]    At this time, assuming that the Y-axis scanner  106  is in the middle of measuring the X-direction second line waveform data from the point of time of the start of the feed scan of the pitch Y 1 , the comparator-register/memory-control-circuit  151  outputs a write enable signal to the data memory  134  as the scan state monitoring signal to permit writing of digital waveform data from the A/D converter  132 , and simultaneously outputs a read enable signal to the data memory  133  to permit reading of data by the computer  140  and transfer of data to the main memory  143 . The A/D converter  132  writes the second line digital waveform data sampled at the sampling positions passed through in the order of X 2−n , X 2−(n−1) , X 2−(n−2), , . . . , X 2−1  continuously in the data memory  134 . Simultaneously, the computer  140  continuously reads out the first line waveform data from the data memory  133 . To increase the speed of the data transfer, the computer  140  has a functional part for arranging digital waveform data by DMA (Direct Memory Access) transfer at addresses on the main memory  143 .  
         [0045]    Next, after the feed of the pitch Y 2  by the Y-axis scanner  106  is ended, the X-axis scanner  105  scans the third line while passing through the sampling positions of X 3−1 , X 3−2 , . . . , X 3−n  in the same way as from the above X 1−1  to the X 1−n  direction (left side to right side). Assuming that the Y-axis scanner  106  is in the middle of measuring the third line waveform data from the point of time of the start of the feed scan of the pitch Y 2 , the comparator-register/memory-control-circuit  151  outputs a write enable signal to the data memory  133  as the scan state monitoring signal to permit writing of data from the A/D converter  132 , and simultaneously outputs a read enable signal to the data memory  134  to permit reading of data by the computer  140 . The A/D converter  132  writes the third line digital waveform data sampled at the sampling positions passed through in the order of X 3−1 , X 3−2 , . . . , X 3−n  again continuously in the data memory  133 . Simultaneously, the computer  140  continuously reads out the second line waveform data from the data memory  134  and arranges the digital waveform data by the DMA transfer at the second line address in the main memory  143  of the computer  140 .  
         [0046]    As explained above, in the digital type ultrasonic inspection apparatus according to the present embodiment, the data memories  133  and  134  can alternately be read out from and written into linked with the scans of the X-axis and Y-axis odd-numbered lines and even-numbered lines. During the measurement, the X-axis scanner  105  and the Y-axis scanner  106  are never stopped by fetching of digital waveform data. In this way, it is possible to write and read out digital waveform data continuously without interruption. The above-mentioned sequence is repeated until the final line X m−1 , X m−2 , X m−3 , . . . , X m−n  digital waveform data finishes being arranged at the n—th line address in the main memory  143  of the computer  140 . High speed data transfer can be realized for transfer of the digital waveform data.  
         [0047]    The storage and transfer of digital waveform data according to the above embodiment can also be applied to the scan method of FIG. 2B. The storage capacities of the data memories  133  and  134  are determined by the amount of digital waveform data determined by the unit measurement range. Further, the unit measurement range does not have to be limited to one scan line. In storing the data according to the acquisition of the digital waveform data and transferring it to the main memory of the computer, this can be set in any way so long as it is possible to perform measurement without stopping the scan operation.  
         [0048]    In the above-mentioned embodiments, the CPU  141  executes the peak detection program, but it is also possible to have the processing for peak detection be performed by another CPU or digital signal processor (DSP) to lighten the load on the CPU  141 .  
         [0049]    Further, in the above-mentioned embodiments, the number of position triggers for sampling waveform data is counted and the memories are controlled by switching the scan state monitoring signal, but it is also possible to use other trigger signals than the above position triggers such as triggers linked with the scan in the Y-direction.  
         [0050]    In the above-mentioned embodiments, the explanation was given of the example of the planar scan for the XY plane, but the scan is not limited to the planar scan. The present invention can also be applied to a spiral rotational scan or an inclined scan in three dimensions etc. Further, even in the planar scan, the present invention can be applied to a scan in the XZ plane or YZ plane. Further, it is possible to freely set any “unit measurement range”, not only for each scan line, by linking it with a scan operation in advance.  
         [0051]    The present invention is the ultrasonic inspection apparatus processing the waveform data obtained by measurement digitally, where during scanning by scanners of at least two axes such as the X-axis scanner and Y-axis scanner, the writing of digital waveform data sampled by the A/D converter into the data memory, the reading of digital waveform data by the computer, and the transfer of data to the main memory of the computer are performed switched between at least two data memories. Therefore, it is possible to continuously perform a repetition of a scan of a first scanner in a first unit measurement range, feed in another direction later, scan of the first scanner in a second unit measurement range, and feed in another direction later without interruption. Further, it is possible to continue the scans from one to the next without waiting for the end of transfer of digital waveform data and possible to eliminate the wait time due to the scanners and perform ultrasonic inspections at a high speed.  
         [0052]    The present disclosure relates to subject matter contained in Japanese Patent Application No. 2002-65909, filed on Mar. 11, 2000, the disclosure of which is expressly incorporated herein by reference in its entirety.