JP2931145B2 - Ultrasonic flaw detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of sampling a signal reflected and received from a defect in a test material and further quantizing the signal.
The present invention relates to an ultrasonic flaw detector for digitally displaying a quantized signal in a mode, and more particularly to improvement of a quantized signal.

[0002]

2. Description of the Related Art FIG. 7 is an explanatory view showing an example of conventional sampling, and FIG. 8 is an example of a conventional digital display of a quantized signal. A sample signal is an analog signal reflected from a defect and received. , Is a quantized signal indicating the digital value of the sampled analog signal, and is an envelope obtained by connecting the maximum value of the quantized signal. Ultrasonic waves are radiated toward a test material (not shown), and analog signals reflected from a defect inside the sample are sampled by a clock sampling signal synchronized with the ultrasonic wave radiation.

[0003] The sampled sample values are then quantized and converted to digital to obtain a quantized signal of a level corresponding to the analog amount. FIG. 8 shows a digital representation of the quantized signal. In the ultrasonic wave propagation direction, that is, in vertical flaw detection, a quantized signal sampled for a defect in the depth direction of the test material is displayed, and the maximum value of the quantized signal is displayed. Are connected to each other to form an envelope.

[0004]

In the conventional ultrasonic flaw detector as described above, an analog signal reflected from a defect in the test material by radiating ultrasonic waves toward the test material is synchronized with the ultrasonic radiation. The sampled data is sampled at fixed time intervals, and the sampled value is digitally converted to a quantized signal. The sample value is determined by the level of the analog signal at the sampling position, and the maximum value of the analog signal may be different from the sample value, so that a correct value of the defect in the test material cannot be always obtained.

When the level fluctuation of the analog signal is remarkable and occurs in a time shorter than the sampling period, sampling and quantization of the analog signal cannot be performed properly. Therefore, the information of the analog signal is not sufficiently contained in the quantized signal. Since they are not included, the size of the defect cannot be displayed correctly, and of course, the minute defect is omitted from the display and the defect cannot be detected correctly.

In order to correctly associate a quantized signal and an envelope with an analog signal in order to correctly detect a defect including a minute defect, sampling is performed at a time interval corresponding to a frequency equal to or more than twice the highest frequency component of the analog signal. Have to do it. If the sampling frequency is increased and the sampling period is shortened, the frequency of analog signal quantization increases, and the cost increases because a high-speed A / D conversion circuit must be used.

In equivalent sampling in which sampling and quantization of the same analog signal are repeated a plurality of times, the maximum value of the signal can be obtained using a low-speed A / D conversion circuit, but signal conversion takes time. However, there is a problem that it cannot be used for a scanning flaw detector or a defect detection of a signal having a remarkable level fluctuation.

The present invention has been made in order to solve such a problem, and the maximum value of an analog signal reflected from a defect can be maintained without shortening the sampling period and using a high-cost device. It is an object of the present invention to provide a small, light, and low-cost ultrasonic flaw detector capable of correctly detecting the maximum value of an analog signal, that is, the size of a defect in a test material from a digitally displayed quantized signal.

[0009]

An ultrasonic flaw detector according to the present invention performs a peak detection circuit for detecting a maximum value of an analog signal at each sampling period, and performs quantization of the maximum value at each sampling period. An A / D conversion circuit and a clock circuit for individually giving an operation command to the peak detection circuit via the A / D conversion circuit and the delay circuit are provided.

[0010]

According to the present invention, an analog signal emitted from an ultrasonic wave toward a test material and reflected from a defect inside the sample is sampled by a clock synchronized with the emission of the ultrasonic wave via a receiving circuit. The analog signal from the receiving circuit is temporarily stored in a capacitor or the like, and its maximum value is detected at each sampling cycle. The detected signal is converted into a digital signal by quantization and becomes a quantized signal.

When the quantization operation is completed, the electric charge accumulated in the capacitor is discharged according to a command, and is ready for sampling and quantization of an analog signal in the next sampling cycle. The above operations are sequentially performed to form a quantized signal for one screen of the A-mode display, and a digital display is performed on the display. Since the display waveform of the display always indicates the maximum value of the defects in the test material, the size of the defects can be correctly detected.

If the position of the maximum value of the digitally displayed quantized signal, for example, the tip of a bar graph, is connected to each other, an envelope is obtained approximately and the echo can be easily identified. Therefore, the envelope detection circuit can be omitted. In addition, since the digital display can display a stationary waveform, defect detection and evaluation thereof can be performed more easily, and the apparatus can be reduced in size, weight, and cost.

[0013]

An embodiment of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a block diagram showing an embodiment of the present invention, 1 is a clock circuit, 5 is a receiving circuit for receiving a time-series analog signal, and 6 is a peak detecting circuit for detecting the maximum value of the analog signal for each sampling period. , 7 are delay circuits, and 8 is an A / D conversion circuit.

In the ultrasonic flaw detector configured as described above, the time-series analog signal reflected from the defect in the test material by the ultrasonic wave radiated in synchronization with the clock from the clock circuit 1 is received. The signal is applied to a peak detection circuit 6 via a circuit 5. The analog signal is temporarily stored in the capacitor C, and its charged potential is equal to the maximum value of the analog signal, and the value is held for a certain period of time. The A / D conversion circuit 8 operates in response to a clock command from the clock circuit 1 and performs quantization of the signal from the peak detection circuit 6.

On the other hand, the clock from the clock circuit 1 is applied to a peak detection circuit 6 via a delay circuit 7, and after the operation of the A / D conversion circuit 8 is completed, a switch using a semiconductor such as a transistor having a small on-resistance and a high operation speed is used. Give a command to S. By the operation of the switch S, the electric charge accumulated in the capacitor C is rapidly discharged, and preparation for the next analog signal sampling is made. As described above, the analog signal is sampled and quantized at its maximum value by a clock command using a simple circuit at low cost.

FIG. 2 shows an example of the operation signal, which is the same as that of the conventional device, and is a reset signal for delaying the clock and giving an operation reset command to the peak detection circuit 6.
Indicates a timing signal for giving a command for ultrasonic emission in synchronization with a clock.

FIG. 3 shows an operation waveform showing an example of sampling, a time-series analog signal reflected from a defect in a test material, etc., is sampled by a clock, and the maximum value of the analog signal in the sampling period is detected. Is done. This maximum value is converted to a digital signal to be a quantized signal. After the quantization is completed, the maximum value detection operation is reset by a reset signal after a slight delay, the maximum value detection in the next sampling cycle is repeated, and the analog signal is sequentially sampled and quantized.

FIG. 4 shows an example of a digital display of a quantized signal. A sampled analog signal is then quantized and a digital display of the quantized signal is performed on a display. If the maximum values of the quantized signals are connected to each other, an envelope is approximately formed, and envelope detection is performed simultaneously.

FIG. 5 is a block diagram showing an example of the ultrasonic flaw detector, in which 1, 5, 6, 7, 8,.
, Are the same as those in the above embodiment, 2 is a timing circuit that generates a timing signal of ultrasonic emission in synchronization with a clock, 3 is a pulse circuit that operates by a timing signal, 4 is a probe, 9 is a line memory, and 10 is a line memory. Denotes an address generator, 11 denotes a frame memory for storing a signal from the line memory 9 to form an A-mode quantized signal, 12 denotes a drive circuit, and 13 denotes a digital display.

In the ultrasonic flaw detector configured as described above, the probe 4 that emits an ultrasonic pulse in synchronization with the clock from the clock circuit 1 also transmits a reflected signal from a defect in the test material. Receive the wave. The reflected signal passing through the receiving circuit 5 is a time-series analog signal, which is sampled and quantized in a peak detection circuit 6 and an A / D conversion circuit 8 which operate in response to a clock command, and the quantized signal is temporarily stored in a line memory. Written to 9.

The quantized signal read from the line memory 9 is sequentially stored at a predetermined position in the frame memory 11 in accordance with a command from the address generator 10 to form an A-mode quantized signal for one screen instead of an analog signal. You.

Next, the A-mode quantized signal is read from the frame memory 11 and, by the operation of the drive circuit 12, for a TV composed of 256.times.256 pixels having a panel size of 3 to 4 inches using an LCD such as a liquid crystal. Defects and the like in the test material are displayed on the digital display format display 13 in the A mode. Under the control of the frame memory 11, the display unit 13 can display a static waveform of the quantized signal.

FIG. 6 shows an example of the A-mode digital display. In the defect detection by the vertical flaw detection of the test material using the ultrasonic flaw detector, the transmission pulse T and the reflected light from the bottom surface of the test material each time the ultrasonic wave is radiated. The defect echo F reflected from the defect in the test material between the bottom echo B and the noise generated between them is displayed.

According to the present invention, the maximum value of the analog signal is detected at each sampling period, and the quantized signal which has been digitally converted is digitally displayed in the A mode. Detection can be performed correctly.
Further, the envelope detection of the quantized signal can be performed approximately without adding a circuit, and the echo can be easily identified. Furthermore, the probe 4 can be used for a scanning flaw detector that scans a test material or a defect detection when the level fluctuation of a received signal is remarkable.

[0025]

As described above, the present invention has a simple structure in which a peak detection circuit and an A / D conversion circuit which operate at each sampling period and a clock circuit which gives an operation command to these at different timings are provided. 1 instead of multiple times as in equivalent sampling in mode digital display
The maximum value of the defect can be detected and quantized in each transmission. That is, the size of the defect can be correctly evaluated. Envelope detection of the quantized signal can be performed approximately, and echo can be easily identified. Since the quantized signal can display a static waveform, the defect can be more easily evaluated. The device is advantageous in that it can be small, light, and low in cost.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 shows an example of an operation signal.

FIG. 3 is an operation waveform showing an example of sampling.

FIG. 4 shows an example of digital display of a quantized signal.

FIG. 5 is a block diagram showing an example of an ultrasonic flaw detector.

FIG. 6 shows an example of an A-mode digital display.

FIG. 7 is an explanatory diagram showing an example of a conventional sampling operation.

FIG. 8 shows an example of a conventional digital display of a quantized signal.

[Explanation of symbols]

 Reference Signs List 1 clock circuit 5 reception circuit 6 peak detection circuit 7 delay circuit 8 A / D conversion circuit

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takashi Inoue 2-16-46 Minami Kamata, Ota-ku, Tokyo Inside Tokimec Co., Ltd. (72) Inventor Koji Saito 2-16-46 Minami Kamata, Ota-ku, Tokyo (56) References JP-A-2-69653 (JP, A) JP-A-50-130489 (JP, A) JP-A-1-224660 (JP, A) Jpn. (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) G01N 29/00-29/28

Claims (1)

(57) [Claims] 1. An ultrasonic flaw detector which samples and quantizes a time-series ultrasonic analog signal reflected from a defect in a test material at discrete times and quantizes the analog signal to display the digital analog display in an A mode. A peak detection circuit for detecting the maximum value of the analog signal for each sampling period, an A / D conversion circuit for quantizing the maximum value for each sampling period,
An ultrasonic flaw detector comprising: a conversion circuit; and a clock circuit that individually issues an operation command to the peak detection circuit via a delay circuit.