JPH04148854A - Surface-defect detecting apparatus - Google Patents

Abstract

PURPOSE:To prevent image blurring by providing a constitution wherein a scanner controller, a scanner and a tracking mirror are made to follow and vibrated in response to a conveying speed when the luminance signals of the normal part and the defective part of a test specimen are detected, and the image is picked up under the relatively stationary state. CONSTITUTION:When there is the defect of irregular flaws on the surface of a test specimen 1 in conveyance, the luminance signals of the normal part and the defective part are detected with an image sensing device 3. The defect is judged and detected with a defect judging circuit 10 based on the output signal after image processing in an image processing circuit 9. Namely, the output luminance signal level from the circuit 9 is compared with a reference luminance signal level. The presence or absence of the defect is judged based on the magnitude of the level. At this time, when the conveying speed of the test specimen 1 is 1,000 mm/second, the image blurring of 1,000 X 1/60 17 mm at the field time of 1/60 second is generated in the device 3. Therefore, a tracking mirror 8 is made to follow and vibrated, and the relative speed with respect to the test specimen 1 is made to be 0. Then, the image of the defective part can be picked up without the image blurring. Thus, the detection of the defective part and the measurement of the size can be accurately performed.

Description

Detailed Description of the Invention [Field of Industrial Application] This invention is a surface defect detection device that continuously detects defects on the surface of pipes and bars. This invention relates to a surface defect detection device that detects defects by using the brightness fu (i-j ``J or 5'').

[Conventional technology]

FIG. 6 is a block diagram showing a conventional surface defect detection device. In Figure 6, (1) is the pipe that is the material to be tested, (2
) is the transport direction of the pipe (1), which is the material to be inspected, (3) is an imaging device that detects the brightness value of the defective part of the material to be inspected (1),
(4) indicates a signal processing circuit that processes the output signal of the imaging device (3). Conventionally, when there is a defect such as a concave scratch (cracking scratch) or a convex scratch (scratching, etc.) on the surface of the pipe, the test material 1 = 4 (1,), the defective part of the test material (1) is a normal part. The imaging device (3) detects the luminance signals of the normal part and the defective part of the material to be inspected (1) by using the difference in the luminance signals, and the signal processing circuit (4) detects the luminance signals of the imaging device (3). ) was used to detect defective parts by signal processing the output. For example, when the brightness signal level of the output of the imaging device is higher than the reference brightness signal level, a defect is detected as having a defect, and if the defect is small, a defective part is detected as having no defect.
As a method to make it easier to distinguish between the luminance signals of the normal part and the defective part in 1), the material to be inspected (1) is magnetized and a magnetic powder liquid with a high luminance signal is applied to concentrate the magnetic particles in the defective part. A method of increasing the brightness signal of a defective part is often used.

[Problems to be Solved by the Invention] Conventional surface defect detection equipment does not require a mechanical scanning device as an imaging device, which improves reliability.
In addition, in order to visually capture the surface condition of the material to be inspected, an image pickup tube or a CCD camera that can detect surface defects over the entire area of the material to be inspected is often used. As an example of the CCI camera described in -1-, when the field time is 1/60 sec, it is necessary to receive the defect signal for i-/60 sec. The conveyance speed of the material to be inspected is normally 60 m/min, and in field tie 18] -/ 60 sec, it is 60 m/min.
m1nxt/605ec=17 nun movement causes image blur. The present invention has been made to solve this problem, and an object of the present invention is to prevent image blur by providing a tracking mirror that follows the speed of a specimen to be inspected.

[Means to solve the problem]

The surface defect detection device according to the present invention has a brightness of 1 in normal and defective areas of a test material, and is equipped with an imaging device that detects a bow, a scanner controller that vibrates in accordance with the speed of the test material, and a tracking mirror. be.

[Effect]

The surface flaw detection apparatus according to the present invention detects brightness signals of a normal part and a defective part of a material to be inspected using an imaging device.

Image blur is prevented by causing the scanner controller, scanner, and trunking mirror to vibrate in accordance with the conveyance speed of the material to be inspected, and taking an image of the material to be inspected in a relatively stationary state.

[Examples] Examples of the present invention will be described below with reference to FIGS. 1 to 5. In the figure, (1) to (3) are exactly the same as the conventional device described above. (5) is a speed detector that detects the speed of the material to be inspected; (6) is a tracking mirror based on the output of the speed detector (5); (8) is a sugana controller that controls the following vibration speed; (7) is a scanner that vibrates to follow the tracking mirror (8), (8) is a tracking mirror that vibrates to follow the output of the scanner,
(9) is an image processing circuit that performs image processing on the output of the imaging device (3), (1,0) is a defect determination circuit that determines defects on the output of the image processing circuit (9), (1,D is an image processing circuit ( 9
), and (], 2) respectively indicate an image integration circuit that integrates the output of the image processing circuit (9). Test material being transported in Figure 1 (1)
If there are defects such as concave scratches (cracks) or convex scratches (scratches, etc.) on the surface, the imaging device @(3) takes advantage of the fact that the brightness signal in the defective area is different from that in the normal area. The brightness signals of the normal and defective parts of the material (1) are detected and inspected by the image processing circuit (9).]
Image processing is performed on the brightness signals of the normal and defective areas in (1), and the output signal of the image processing circuit (9) is judged to be defective in the defect determination circuit (10).3, for example, an image processing circuit (
When the luminance signal level of the output of step 9) is larger than the reference luminance signal level, a defect is detected as a defect angle, and when it is smaller, there is no defect. In addition, 11 of Test material (1): As a method to further differentiate the difference in brightness signals between normal parts and defective parts, the test material is magnetized and a magnetic powder liquid with a high brightness signal is applied to the defective part. A method of increasing the brightness signal of a defective area by concentrating magnetic particles is often used. However, when the conveyance speed of the material to be inspected (1) is high, the imaging device (3) has a field time of 1, for example.
/60 sec, and the conveying speed is 1-000 mm
/ sec, 1000mm/sX 1/6
An image blur of 0 sec"-17 mm will occur. Therefore, if the tracking mirror (8) is vibrated in accordance with the speed of the material to be inspected and the relative speed with respect to the material to be inspected (1) is set to 0, the object to be inspected (
It is possible to capture an image of the defective portion of the material to be inspected (1) without causing the image blurring described in 1). By the way, the material to be tested (1
) is stationary, the tracking mirror (8) is 45
The defect signal of the defective portion of the material to be inspected (1) is reflected by the trunking mirror (8) and input to the imaging device (3). Test material speed is 60m/m = 10
00 mm/s, the imaging device (3) and the specimen material (
1), and the distance from the object to the test object A is i o Oc, 1 mm.
If the YJ effective field for 4(1) is 200 mm, then
The tracking mirror (8) is made to follow the subject 4-A (1) while it moves for 100 mm.

If the tracking mirror (8) is reversely lowered while proceeding to the next 100 marks of the test material + A (1), the entire surface of the test material (1) will be continuously covered without falling through even if the test material (1) is transported at high speed. It is possible to follow the four images and continuously capture images of the entire surface without causing image blur.

FIG. 2 is a diagram showing the output waveform of the scanner controller (6), which outputs a drive signal e to the scanner (7) in response to the speed of the specimen conveyance speed detector (5). Shows the waveform. The drive signal e is a triangular wave with a constant period (T), and the conveyance speed detector (
Based on the speed of 5), repeat 10 ascent and F descent. The drive signal e causes the L elapsed tracking mirror (8) to rotate forward and reverse when descending. The period T of the drive signal is determined by the ratio between the effective field of view (-, constant distance) of the imaging device and the conveyance speed. That is, T
- Scanner controller (
6) outputs a drive signal to the scanner (7). The scanner (7) receives the drive signal e from the scanner controller (6) and vibrates the tracking mirror (8) in the forward and reverse directions (it is a drive device). Therefore, the time required to reverse the trunking mirror (8) is The time required to follow the transport speed of the tracking mirror (8) or the material to be inspected (1), i.e. +f('ti The image processing time becomes longer and the image stabilizes, allowing the entire surface to be imaged without image blurring.The image processing circuit (
By inputting the output of step 9) into the display monitor (11), it is possible to visualize the surface condition of the test material (1) so that it can be visually confirmed.

FIG. 3 is a diagram showing an embodiment of the present invention. In FIG. 3, the output image of the image processing circuit (9) has many noise components, so the S/N ratio is low and defects cannot be detected in many cases. Therefore, in order to change the S/N in the opposite direction, the output of the image processing circuit (9) is input to the image integration circuit (12) and is integrated for one image. The signal is input to a defect determination circuit (10), making it possible to detect defects even with a defect signal having a low S/N ratio.

FIG. 4 shows a brightness signal (S) and a noise signal (N) of a defective portion in one horizontal line in the 11] direction of the specimen as an example of the output image of the image processing circuit (9). Generally, the luminance signal (S
) and the noise signal (N) is below S/N or S/N #2, it is said that automatic detection of defective parts of the material to be inspected (1) is impossible. Therefore, set S/N″-2 to -I-< S/N
Is there a need to improve?

Figure 5 shows the output of the image processing circuit (9) and the image integration circuit (1).
An example of the output of image integration in 2) is shown. It is generally said that if you integrate N screens, the S/N will improve by /'-N times,
When the conveyance speed of the test material (1) is 1000 mm/scC, the test material (1) is 1. 1 fee 1-00 while proceeding with O0 plate
mm ~ Ludo time is 1. /1000mm at 60sec/
see /1- / 60sec = 6. That is, 6 static 11-images are obtained [3 internal area integrals are possible, , r
S/N is improved by 6-2.4 times. Therefore, on one screen, S
,/N=1. , , 5, by integrating 6 images, S/N = 1.5X (6-3,7).

〔Effect of the invention〕

Since this invention is configured as described above, it is possible to eliminate image blurring caused by the field time of the imaging device even when the material to be inspected is being conveyed at high speed, and it is possible to accurately capture the image with iE, thus making it possible to detect defects in "correction". What you do is i”iJ ability.

Furthermore, by eliminating image blur, it is possible to accurately detect defects and accurately measure the dimensions of defects. Furthermore, the present invention provides an image hlj that integrates the output of the image processing circuit.
Since 1 times are provided, the S/N of the defect signal is increased by 1, and even a defect signal with a lower S/N can be detected.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a surface defect detection device of the present invention, FIG. 2 is a diagram showing output waveforms of the scanner controller of the present invention, and FIG. 3 is a block diagram of a surface defect detection device of another embodiment of the present invention. , FIG. 71 is a diagram showing an example of an output image of the image processing circuit of the present invention. FIG. 5 is a diagram showing an example of image integration by the image integrating circuit of the present invention. FIG. 6 is a block diagram of a conventional surface defect detection device. be. In the figure, (1) is subject+A',
(2) is the transport direction of the test object +4 (1), (3) is the imaging device, (4) is the signal processing circuit, (5) is the test material transport speed detector, (6) is the scanner controller, (7 ) is the scanner, (8) is the tracking mirror, (9) is the image processing circuit, (1()) is the defect determination circuit, (1,1,) is the display monitor, (1,2) is the 1j-1ij image integration It is a circuit. The middle part of the figure or the corresponding part is indicated by the same reference numeral 1,

Claims (2)

[Claims] (1) In a surface defect detection device that continuously detects flaws on the surface of a test material such as a pipe or bar, an imaging device that detects a brightness signal of a defective part of the test material and an imaging device installed near the test material. a tracking mirror that inputs a luminance signal from the material to the imaging device; an image processing circuit that performs image processing on the luminance signal of the material to be inspected, which is an output signal of the imaging device; and a defect that determines the output of the image processing circuit as defective. a determination circuit, a display monitor that displays the output of the image processing circuit, a speed detector that detects the speed of the test material, and receives the output of the speed detector;
A surface defect detection device comprising: a scanner controller that outputs a vibration speed that follows the speed of a material to be inspected; and a scanner that causes the tracking mirror to vibrate in accordance with the output from the scanner controller. (2) The surface defect detection apparatus according to claim 1, further comprising an image integration circuit that integrates the output of the image processing circuit and provides the output to a defect determination circuit.