JPH0534322A - Ultrasonic measuring device - Google Patents

Abstract

PURPOSE:To obtain a title item which can perform an optimum measurement without replacing a probe for a specimen whose sound speed changes with the measurement frequency. CONSTITUTION:A burst signal generation drive circuit 1a where the generation frequency can be controlled externally is provided, a wide-band probe 14 is driven by a burst signal for searching for a frequency and a sound speed which are most suitable for measurement of a specimen, and the wide-band probe 14 is driven by a burst signal with the obtained measurement frequency to sample an echo from the specimen, thus enabling an ultrasonic measurement to be made with an optimum or proper frequency, eliminating a need for replacing the probe, and achieving a highly accurate and efficient ultrasonic measurement for the specimen whose sound speed changes with frequency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic measuring device, and more particularly, it is an ultrasonic measuring device capable of performing optimum measurement on a subject whose sound velocity changes depending on the measuring frequency without replacing the probe. Regarding measuring device.

[0002]

2. Description of the Related Art In the field of ultrasonic measurement, which is one of nondestructive inspections, ultrasonic sound velocity measurement methods are standardized by JIS and the like. The ultrasonic sound velocity measurement is performed not only on a metal material but also on a material such as concrete, and the longitudinal sound velocity is measured to estimate the compressive strength and the like. The speed of sound is an important parameter in non-destructive inspection because it is related to the characteristics of the material, and it obviously depends on the temperature.However, for example, in the case of ceramics, plastics, soft metals such as lead, etc. Causes the speed of sound propagating there to change.

Generally, in ultrasonic measurement, if the measurement frequency is increased, the measurement resolution is improved and the measurement accuracy is increased, but conversely, the higher the frequency, the greater the attenuation inside the object.
It is difficult to collect the defect echo. Therefore, the measurement target (subject)
There is an optimum frequency depending on the ultrasonic wave, and an ultrasonic probe (probe) used in ultrasonic measurement usually has a narrow band frequency characteristic with a specific frequency as a resonance frequency. . Measurement is performed by generating ultrasonic waves by pulse-driving such a probe. Ultrasonic waves actually generated at this time mainly consist of this resonance frequency component, but in the case of pulse driving, ultrasonic waves of various frequencies are also generated.

[0004]

When measuring an object whose sound velocity changes according to the above-mentioned frequency, a probe having an optimum or appropriate measurement frequency characteristic depending on the material of the object to be measured and the like. Has to be attached and measured, and there is a drawback that the replacement is troublesome. Moreover, the frequency of ultrasonic waves generated by pulse driving is not always
It cannot be said that this is due to the echoes collected only with the optimum frequency component. Therefore, there is a problem that the defect position cannot be accurately detected in the subject whose sound velocity changes depending on the frequency even if the distance to the defect is calculated with the sound velocity at the frequency. Also, replacement of the probe requires adjustment of various measurement conditions, such as setting of gain of the receiver, etc., which reduces the measurement efficiency, and even if the probe is optimally selected. When the thickness of the subject or the position of the defect is λ / 2, λ / 4, etc., there is a problem that multiple reflections occur and the desired echo cannot be collected sufficiently.

An object of the present invention is to solve the above-mentioned problems of the prior art, and it is possible to perform an optimum measurement for a subject whose sound velocity changes depending on the measurement frequency without replacing the probe. It is to provide an ultrasonic measuring device capable of performing the above.

[0006]

Means for Solving the Problems In an ultrasonic measuring apparatus of the present invention for achieving such an object, a wide band ultrasonic probe and a burst signal whose frequency changes according to a control signal are provided. A burst signal generation drive circuit that generates and drives the ultrasonic probe, and generates the control signal that sequentially changes the frequency in a wide range to calculate the sound velocity in the subject from the received signal of the bottom surface echo of the subject. The sound velocity and the echo level of the bottom echo are stored in correspondence with the generation frequency, and the frequency at which a predetermined bottom echo level is obtained is detected by referring to the echo level, and the control signal corresponding to this frequency is generated to generate the super And a control circuit that drives the acoustic probe and obtains a measurement value for the subject according to the sound velocity corresponding to the detected frequency.

[0007]

A burst signal generation drive circuit capable of controlling the generation frequency from the outside is provided, and a wideband probe is driven by the burst signal to find the optimum frequency and sound velocity for measurement with respect to the subject, Since the wideband probe is driven again by the burst signal of the measurement frequency to collect the echo from the subject, it is possible to perform ultrasonic measurement at the optimum or appropriate frequency, which makes it necessary to replace the probe. Is high, the accuracy is high for a subject whose sound velocity changes with frequency,
It enables efficient ultrasonic measurement.

[0008]

1 is a block diagram of an embodiment of an ultrasonic measuring apparatus to which the present invention is applied, and FIG. 2 is an explanatory view of a transmission wave and a surface echo when driven by a burst signal. . In FIG. 1, 10 is an ultrasonic measurement device,
Reference numeral 1 is the flaw detector section. The flaw detector unit 1 includes a burst signal generation drive circuit 1a, a receiver 1b including a receiver and a gate circuit, and the like, and receives a control signal from a microprocessor (MPU) 5 via a bus 11. It is controlled according to this control signal.

The burst signal generation drive circuit 1a generates a transmission wave T (see FIG. 2A) of a burst signal of more than ten cycles from the transmission terminal 12 to the probe 14 at a predetermined measurement cycle and echoes from the probe 14. Received signal ((b) in FIG. 2)
Defect wave F (see bottom wave B in FIG. 2 (c)) is received by the receiving terminal 13, amplified by the receiver of the receiving section 1b, detected, and sent to the A / D conversion circuit 2. The burst signal generation drive circuit 1a has a built-in frequency sweep type oscillator 1c whose oscillation frequency can be continuously controlled by a digital value, and the generation frequency of the oscillator 1c is selected or scanned according to a control signal from the MPU 5. To be done. The above burst signal is periodically generated corresponding to the oscillation frequency of the oscillator 1c, and the probe 14 is driven by this. In FIG. 2, the echo reception signal in an ideal burst state is shown for convenience of explanation. However, in reality, the amplitudes of the defect wave F and the bottom wave B are the material and thickness of the object 9 and the defect. The attenuation rate varies depending on the depth of the signal and the frequency of the burst signal used, and the waveform may be slightly distorted.

Here, the probe 14 is a wideband probe with enhanced damping, and its band is, for example, in the range of 500 KHz to 20 MHz. Subject 1
In 4 such as a plastic molded part, the speed of sound propagating inside changes according to the measured frequency.

The A / D conversion circuit 2 detects an envelope detection signal (RF signal of an echo reception signal for a defect wave F, a bottom wave B, etc. obtained from the flaw detector section 1 in response to a control signal from the MPU 5. The obtained video signal, but the RF signal may remain unchanged depending on the sampling frequency), is sampled at a high frequency of, for example, about 20 MHz to 30 MHz, and these analog outputs are converted into digital values and stored in the waveform data memory 3. Send out sequentially.

The waveform data memory 3 has a storage capacity for storing a predetermined number of measurement data which is n times (n is an integer of 2 or more) the measurement data displayed on the display screen, for example, about 4000 points. However, the data sampled by the A / D conversion circuit 2 is stored while sequentially updating (incrementing) its address. Then, when the number of data sampled by the A / D conversion circuit 2 is stored up to a predetermined final address, a sampling end signal is sent to the MPU 5.

As a result, the waveform data memory 3 has at least twice the number of measurement data displayed as an image (for example, if the number of measurement data is 200, the number of 4000 points is 20).
The measurement data of a predetermined sampling number of (double) is sequentially stored as a digital value corresponding to each address. Moreover, at this time, the measurement data at each address is stored as a function of time in units of the sampling cycle of the A / D conversion circuit 2.

Upon receiving the sampling end signal from the waveform data memory 3, the MPU 5 stops the sampling process of the A / D conversion circuit 2 and collects the measurement data from the waveform data memory 3 via the bus 11 according to the measurement conditions. Display data of the A scope image is generated. The generated display data is stored in the image memory area of the RAM 6 (the image memory unit 61 described later), which is the LCD display device (LCD) 8.
The A-scope image corresponding to the display data that has been transferred to and generated by the LCD display device 8 is displayed. In addition, at the time of measurement for inspecting the subject 14, the MPU 5 compares the measurement data of the waveform data memory 3 with a reference value to set a threshold for the measurement data to set the defect wave F, the bottom surface. The position of wave B is detected. Then, the display data is generated by calculating the distance from the surface to the defect (time value) or the distance from the surface to the bottom surface (time value). The generated display data is stored in an image memory area (an image memory unit 61 described later) of the RAM 6 and is transferred to an LCD display device (LCD) 8 to generate an image according to the display data generated by the LCD display device 8. The measured value is displayed.

Reference numeral 4 denotes an operation panel having a gain dial, a cursor dial, a display position designating knob, a sheet key, etc., which is connected to the bus 11. MPU5
Receives a set value set by a dial and various key input signals from this circuit via the bus 11. When the gain setting value (adjustment value) for the receiver of the receiving unit 1b is input by the gain dial, the MPU 5 causes the receiving unit 1b to
Gain of b receiver (high frequency amplifier)
Is controlled, and the gain of the receiver is set so that the gain corresponds to the gain setting value input by the gain dial.

Reference numeral 6 denotes a RAM, which is connected to the bus 11 and is designated by digital display data of the echo reception signal which has been A / D converted, various application processing programs loaded from the outside, and an input key. Various information such as a flag indicating the flaw detection mode and various data are stored. The RAM 6 is provided with a sampling condition parameter storage area 62 and a frequency-sound velocity characteristic storage area 63.

Reference numeral 7 denotes a ROM, which includes an A scope image calculation processing program 71 executed by the MPU 5, a frequency-sound velocity measurement program 72, a measurement frequency detection / measurement program 73, a display processing program 74, and the like.
Various basic programs are stored. Note that these programs may be loaded into the storage area of the ROM 6 from the outside. The LCD display device 8 displays various measurement values in addition to the A-scope image and the like, and internally has a video memory interface and a video memory, and a video memory controller that reads out information from the video memory and generates a video signal,
It has a liquid crystal drive circuit and a liquid crystal display of a dot matrix of 256 × 512 dots or 400 × 640 dots, for example, and is connected to the bus 11 via a video memory interface.

The A-scope image calculation processing program 71 is started by the MPU 5 which has received the measurement data collection from the waveform data memory 3 at the start of the measurement. Further, this program accesses the address of the waveform data memory 3 according to the conditions stored in the storage area 62 such as the sampling condition parameters to generate the display data,
A process of storing it in the image memory unit 61 is performed. Then, the display processing program 74 is activated.

The information stored in the sampling condition parameter storage area 62 is a parameter for sequentially increasing the frequency to collect the measurement data, a parameter for collecting the measurement data at a specific frequency, and the like. Further, a condition to determine the order in which the measurement data of the waveform data memory 3 stored at the start address and the final address for reading the measurement data of the waveform data memory 3 and the addresses between them are collected, for example, Parameter information such as whether to collect every few addresses, how many average values are collected from the collected data to be used as display data, and the highest value of multiple measurement data to be used as display data is also stored. There is.

The frequency-sound velocity measurement program 72 is started by the MPU 5 when the function key for frequency selection measurement is input from the operation panel 4, and the MPU 5 executes this program to first collect a sampling condition parameter storage area. 62, from which a parameter for sequentially increasing the frequency and collecting measurement data is read, and a control signal for increasing or decreasing the frequency is sequentially sent to the burst signal generation drive circuit 1a every time the measurement is updated. Drive this. Thereby, the burst signal generation drive circuit 1a
In the range of 500 KHz to 20 MHz, which is the band of the probe 14, the oscillator 1c is controlled to 5
In the range of 00 KHz to 2 MHz, the frequency increases stepwise every time the measurement is repeated in units of 250 KHz, and the frequency increases to 2 MHz.
In the range from 10MHz to 10MHz, the frequency increases stepwise in units of 1MHz, and in the range from 10MHz to 20MHz, 2
Control is performed in which the frequency is increased stepwise in units of MHz. Then, the time of the bottom wave B of the subject 9 is calculated for each frequency at each measurement time point, and the sound velocity at that time is calculated from the thickness of the subject 9 in correspondence with the measured frequency, and the calculated sound velocity is calculated. The maximum amplitude value of the bottom wave B at that time is tabulated and stored in the frequency-sound velocity characteristic storage area 63 for each measurement frequency. Further, after the tabulation, the measurement frequency detection / measurement program 73 is activated.

The measurement frequency detection / measurement program 73 is M
When executed by the PU 5, the MPU 5 refers to the measured value (echo level) of the bottom surface wave B that exceeds the predetermined threshold level from the frequency-sound velocity characteristic storage area 63 from the higher measurement frequency to the lower measurement frequency. To go. As a result, the maximum frequency of the bottom wave B that exceeds the threshold can be detected. Next, the subject 14
The control signal corresponding to the frequency detected by entering the measurement state of is obtained by referring to the storage area 62 such as the sampling condition parameter,
This control signal is sent to the burst signal generation drive circuit 1a. The burst signal generation drive circuit 1a sends the burst signal shown in FIG. 2 having the maximum frequency detected according to the control signal corresponding to the detected frequency to the probe 14 to receive the echo reception signal. As a result, measurement data having an optimum frequency with high resolution is obtained and stored in the waveform data memory 3.

The obtained measurement data are A scope image and B scope image.
Reference is made in accordance with the measurement mode of the scope image, C scope image, etc., and as a result, the time value data and the amplitude value of the defect wave F or the bottom wave B are temporarily stored in the RAM 6, and then the measurement is performed based on these data. Display data corresponding to the mode is generated and stored in the image memory unit 61, and a predetermined image is displayed. Although not shown in the block diagram, when a manual scan or a scanner scan is performed in accordance with the measurement mode, the measurement position data is externally given to the MPU 5, and the measurement position data corresponds to the measurement data collected in the RAM 6. Memorized in. Then, according to this position data, the previous display data is stored in the address corresponding to the measurement position in the image memory unit 61.

As described above, the measurement of the frequency-sound velocity characteristic in the embodiment does not have to be performed each time the object is measured, and for the same kind of object, the data measured once is used for the next object measurement. The sample may be measured. Also,
As for the measurement value of the measurement frequency-sound velocity, the optimum measurement frequency and sound velocity at the standard temperature are obtained in advance for an object of the same material such as an electronic component, and this is stored in the memory and used. Good. Further, in the embodiment, the frequency-sound velocity characteristic is measured by increasing the frequency, but this is measured by gradually decreasing the frequency, and even if the frequency-sound velocity characteristic data is obtained. Good. Further, in the next stage of detecting the measurement frequency, conversely, the frequency at which the echo of the bottom surface wave becomes equal to or higher than a predetermined level may be detected from the low frequency. In this case, the frequency is
The lower frequencies are detected first, and the lower frequencies are selected, but the higher frequencies are preferable as the frequencies to be detected. However, it does not necessarily have to be the highest frequency of them.

In the embodiment, the waveform data memory is an A / D
Although it is inserted between the conversion circuit and the MPU, if the processing speed of the MPU is high, the data of the A / D conversion circuit will be MP
It is also possible for U to receive the data once and transfer it to the waveform data memory or RAM to collect the measurement data. In addition, in the embodiment, the measurement data of the flaw detector is A / D.
Although converted and stored in the waveform data memory, a time measuring circuit is provided in the flaw detector unit to measure a time value with the bottom surface wave B and a time value up to the defect wave F, and the MPU outputs the measured value. It may be obtained and stored in the RAM, and a process of displaying the measurement image may be performed. In the above embodiments, the direct method in which the probe is directly applied to the sample for measurement has been described, but the present invention can be directly applied to the water immersion method. In this case, the measurement of the sound velocity of the sample based on the reception time of the bottom echo may be replaced with a conventional method based on the time difference from the surface echo to the bottom echo.

[0025]

As can be understood from the above description, according to the present invention, a burst signal generation drive circuit whose generation frequency can be controlled from the outside is provided, and a wide band probe is driven by the burst signal to the subject. The optimum frequency and sound velocity for measurement are searched for, and the broadband signal is driven again by the burst signal of the obtained measurement frequency to collect the echo from the subject. Acoustic wave measurement can be performed, which eliminates the need to replace the probe, and enables highly accurate and efficient ultrasonic wave measurement for a subject whose sound velocity changes with frequency.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of an ultrasonic measurement device to which the present invention is applied.

FIG. 2 is an explanatory diagram of a transmission wave and a surface echo when driven by a burst signal.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Ultrasonic flaw detector part, 2 ... A / D conversion circuit, 3 ... Waveform data memory, 4 ... Operation panel, 5 ... Microprocessor (MPU), 6 ... RAM, 7 ... ROM, 8 ... Liquid crystal display device (LCD) Display device), 9 ... Subject, 10 ... Ultrasonic measuring device, 61 ... Image memory unit, 62 ... Storing condition parameter storage area, 63 ... Frequency-sonic velocity storage area, 71 ... A scope image calculation processing program, 72 ... Frequency-sound velocity measurement program, 73 ... Measurement frequency detection / measurement program, 74 ... Display processing program.

Claims (2)

[Claims] 1. A wideband ultrasonic probe, a burst signal generation drive circuit for generating a burst signal whose frequency changes according to a control signal, and driving the ultrasonic probe, and a wideband ultrasonic probe in a wideband range. The control signal for sequentially changing the frequency is generated to calculate the sound velocity in the subject from the received signal of the bottom surface echo of the subject, and the sound velocity and the echo level of the bottom surface echo are stored in correspondence with the generation frequency and the echo is generated. The frequency at which a predetermined bottom surface echo level is obtained with reference to the level is detected, the control signal corresponding to this frequency is generated to drive the ultrasonic probe, and the speed of sound corresponding to the detected frequency is detected. And a control circuit that obtains a measurement value for the subject according to the above. 2. A control signal for sequentially changing a frequency in a wide band range is generated to calculate a sound velocity in the subject from a received signal of a bottom echo of the subject, and this sound velocity and an echo level of the bottom echo are generated. Data stored in association with the frequency and detecting the frequency at which a predetermined bottom surface echo level is obtained by referring to the echo level and the detected frequency, the corresponding sound velocity, and the data in which the subject is associated Generated, the generated data is stored in a memory, the generated data of the memory is referred to, the measurement frequency is determined for the same type of subject as the subject, and the ultrasonic measurement of the same type of subject is performed. The ultrasonic measurement apparatus according to claim 1, wherein the ultrasonic measurement is performed.