JP2010112846A - Method and apparatus for adjusting surface inspecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for adjusting a surface inspecting device capable of accurately adjusting the inspection threshold value of the surface inspecting device and the installation angle of a camera in a short time, and an apparatus for adjusting the surface inspecting device. <P>SOLUTION: The method for adjusting the surface inspecting device has the step 10 for imaging the surface or/and back of an inspection target by the camera and preserving the whole width and whole length image of the inspection target, the step 12 for determining whether the flaw of the inspection target can be confirmed from the preserved image, the step 14 for determining whether the difference between the gray values of both of the confirmed flaw part and a material part is large, the step 15 for adjusting a camera angle in a case that the difference between the gray values is small in the step 14 and the step 16 for adjusting the inspection threshold value in a case that the difference between the gray values is large in the step 14. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method and an apparatus for adjusting a surface inspection apparatus for adjusting a surface inspection apparatus for automatically detecting defects on a surface defect inspection object, for example, a steel sheet surface in a steel sheet production line.

  FIG. 3 is a diagram for explaining the principle of defect detection in the surface inspection apparatus. In the figure, 1 is a steel plate, 2 is a light source, 3 is a camera, 4 is an optical band portion, and 5 is a defect portion. FIGS. 3A and 3B respectively show detection states when there is no defect and when there is a defect, the upper side shows a side view, and the lower side shows a top view.

  The detection unit of the surface inspection apparatus includes a light source 2 that emits light and a camera 3 that is an imaging apparatus. The parallel light from the light source 2 is irradiated on the surface of the steel plate 1, and the light band portion 4 generated on the surface of the steel plate is used as the camera field of view. The camera 3 receives reflected light from the steel plate surface (for example, with a CCD element in a CCD camera) and measures the amount of received light. When there is no defect as shown in FIG. 3A, most of the reflected light can be received, but when there is a defect as shown in FIG. 3B, the reflected light is scattered by the defective portion 5. The amount of light received by the camera 3 is reduced. That is, it becomes a dark image. The principle of defect detection in the surface inspection apparatus is to detect the presence / absence of defects based on the amount of received light.

  In a calculation unit (not shown) of the surface inspection apparatus, the received light amount measured by the camera 3 is converted into a gray value in 0 to 255 steps and then internally processed. Although there are various internal processes in the subsequent surface inspection apparatus, an example thereof will be shown.

  FIG. 4 is a diagram showing an example of internal processing of the camera raw waveform. In the camera raw waveform, the amount of incident light is different between the center and both ends of the camera field of view as shown in the figure due to lens aberration. For this reason, correction for lens aberration is often applied. Then, based on the corrected waveform, a process for determining the presence or absence of a defect is performed.

  Since reflected light changes depending on the presence or absence of defects, the presence or absence of defects on the steel sheet surface can be determined from the difference in brightness. In other words, if there are wrinkles on the surface of the steel sheet, the amount of reflected light is different from normal parts (normal surface parts without defects such as wrinkles, hereinafter referred to as formation parts), and a defect-specific light-dark difference occurs, which means defects. Can be judged. In surface inspection equipment that automatically detects defects, there is a method to set an inspection threshold that takes into account variations in the waveform of the formation, and to recognize a waveform portion that exceeds the lower or upper inspection threshold as a defect. It is common. Also, the detected defect image is stored and can be used for guidance, confirmation of inspection results at a later date, and the like.

There have been many known techniques for automatically inspecting defects on the surface to be inspected, including the steel plate surface, and internal processing. For example, the techniques disclosed in Patent Documents 1 and 2 can be cited.
JP 2007-333732 A JP 2008-116405 A

  Although the inspection threshold value of the surface inspection apparatus is arbitrarily set, if the setting is made strict, small defects can be detected, but on the other hand, a large number of formation portions are detected, resulting in a disadvantage of overdetection. On the other hand, if the threshold value is set to be loose, there is a problem that the possibility that a defect cannot be detected (missed) increases. As described above, the setting of the inspection threshold requires a great amount of time for adjustment by trial and error, which is determined based on the presence / absence of detection of a defect to be detected and overdetection.

  FIG. 5 is a diagram illustrating an example of a difference in images obtained depending on the installation angle of the camera. In FIG. 5 (a), light is projected from a light source at an incident angle of 10 ° onto a defective portion existing on the steel plate, and the camera 1 is positioned at a regular reflection position of 10 ° and the camera 2 is positioned at an irregular reflection position of 50 °. It shows a state that is installed. 5B and 5C show images captured by the camera 1 and the camera 2, respectively. In the camera 1 installed at the regular reflection position of 10 °, the defective part can be confirmed as shown in FIG. 5B, but in FIG. 5C, it is difficult to confirm the defective part.

  Thus, depending on the installation angle of the camera, no defect is visible at all (no difference from the formation portion), and automatic detection is impossible. Furthermore, if a defect cannot be detected, it cannot be determined whether the above-described inspection threshold is bad or the camera angle is bad, and the inspection threshold and the camera angle are changed by trial and error. It is also a factor.

  In view of these problems of the conventional technology, the present invention provides a method and an apparatus for adjusting a surface inspection apparatus capable of accurately and quickly adjusting an inspection threshold value and a camera installation angle of the surface inspection apparatus. This is the issue.

  The invention according to claim 1 of the present invention is a method for adjusting a surface inspection apparatus that adjusts a surface inspection apparatus that automatically detects defects of an inspection object, and images a front surface and / or back surface of the inspection object with a camera. Step 10 for storing the full-width full length image, Step 12 for determining whether or not the defect can be confirmed from the stored image, and if the defect can be confirmed in Step 12, Step 14 for determining whether or not the gray value difference of the image of the formation portion is large, Step 15 for adjusting the camera angle when the gray value difference is small in Step 14, and Gray value difference in Step 14 Is a step 16 for adjusting the threshold value, the adjustment method for the surface inspection apparatus is characterized in that

  Further, the invention according to claim 2 of the present invention is the method for adjusting a surface inspection apparatus according to claim 1, wherein the inspection object is a steel plate and is detected when the defect cannot be confirmed in step 12. This is a method for adjusting a surface inspection apparatus, characterized in that the system is reviewed.

  According to a third aspect of the present invention, there is provided an adjustment device for a surface inspection apparatus for adjusting a surface inspection apparatus for automatically detecting defects of the inspection object, wherein the front or / and back surface of the inspection object is detected by a camera. An image storage device that captures and stores the full-width full-length image, and whether or not the defect can be confirmed from the image stored in the image storage device, and if the defect can be confirmed, It is determined whether or not the gray value difference of the image of the formation portion is large. When the gray value difference is small, the camera angle adjustment is performed. When the gray value difference is large, the threshold value adjustment is performed. An adjustment device for a surface inspection device, comprising: a determination device for determining.

  Furthermore, the invention according to claim 4 of the present invention is the adjustment device for the surface inspection apparatus according to claim 3, wherein the inspection object is a steel plate, and when the defect confirmation is impossible by the determination device, An adjustment device for a surface inspection apparatus, wherein the detection system is reviewed.

  In the present invention, the front or / and back surface of the inspection object is imaged with a camera, the full-width full-length image is stored, it is determined whether the defect can be confirmed from the stored image, and if the defect can be confirmed. It is determined whether the gray value difference between the image of the confirmed defective portion and the formation portion is large. When the gray value difference is small, the camera angle adjustment is performed.When the gray value difference is large, the threshold value is adjusted. Since it is determined that the value adjustment is to be performed, it is possible to accurately and quickly adjust the cause when the defect is overlooked and the adjustment of the surface inspection apparatus.

  FIG. 2 is a diagram illustrating a configuration example of the adjusting device of the surface inspection apparatus. In the figure, 1 is a steel plate, 3 is a camera, 6 is a distributor, 7 is a surface inspection device main body, 8 is an image storage device, and 9 is a determination device.

  The surface inspection apparatus main body 7 excluding the light projecting unit and the detection unit has a defect detection function for automatically detecting a defect and a defect image storage function for storing only an image of the detected defect. A signal from the camera 3 that images the front and back surfaces of the steel plate 1 is branched by the distributor 6 and sent to the surface inspection device body 7 and the image storage device 8. The image storage device 8 has a full width full length image storage function that unconditionally stores all the camera signals sent, that is, full width full length images of the front and back surfaces of the steel plate 1.

  Further, a tracking signal from a PLG or the like is sent to the surface inspection apparatus main body 7 and the image storage apparatus 8 so that the longitudinal position of the inspection surface can be specified. Further, the determination device 9 determines what adjustment method should be adopted.

  FIG. 1 is a diagram illustrating a processing procedure example of a method for adjusting a surface inspection apparatus. Hereinafter, description will be made with reference to the drawings.

  First, in Step 10, the front or / and back surface of the inspection object (steel plate) is imaged with a camera, and the full width full length image is stored in the image storage device 8. As described above, the surface inspection apparatus main body 7 automatically detects a defect and stores only the image of the detected defect, whereas the full-width full-length image is stored. It is necessary to be able to save.

  Then, a substantial processing procedure starts in “Generation of adjustment timing” in Step 11. Here, the occurrence of the adjustment timing is when the necessity for adjustment occurs. The case where the necessity for adjustment has occurred is specifically a case where an undetected defect has occurred, for example, when a defect is found in the visual inspection at the tail end of the steel plate to be inspected, This is the case, for example, when a complaint is made that the customer has a defect.

  Next, in Step 12, it is determined whether or not the defect can be confirmed from the stored image. That is, although the surface inspection apparatus main body 7 cannot automatically detect it as a defect, the image storage apparatus 8 that stores the full-width full-length image confirms the image of the corresponding portion to determine whether it is recognized as a defect.

  Here, if it is not recognized as a defect, it goes to Step 13 and determines that the detection system needs to be reviewed. This is a review of the detection system such as a lack of optical system resolution of the detection unit of the surface inspection apparatus, and it is determined in a short time that the adjustment by the trial and error described below is not performed.

  If the defect can be confirmed from the stored image in Step 12, the process proceeds to Step 14, and it is determined whether or not the gray value difference between the image of the defective part and the formation part is large. If the gray value difference is not large, it is determined that the camera angle is not appropriate as seen in FIG. 5, and the camera angle is adjusted in Step 15.

  When the gray value difference between the image of the defective portion and the formation portion is large, the threshold value is adjusted to an appropriate value in Step 16 and reflected in the surface inspection apparatus main body 7.

  So far, when automatic inspection has been performed with a surface inspection device and a defect is missed, the cause cannot be identified. Needed. By using the method and apparatus for adjusting a surface inspection apparatus according to the present invention described above, it becomes easy to identify the cause when a defect is overlooked, so that the adjustment time can be shortened.

It is a figure which shows the example of a process sequence of the adjustment method of a surface inspection apparatus. It is a figure which shows the structural example of the adjustment apparatus of a surface inspection apparatus. It is a figure explaining the defect detection principle in a surface inspection apparatus. It is a figure which shows the mode of the example of an internal process of a camera raw waveform. It is a figure which shows an example of the difference of the image obtained by the installation angle of a camera.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steel plate 2 Light source 3 Camera 4 Optical zone part 5 Defect part 6 Distributor 7 Surface inspection apparatus main body 8 Image storage apparatus 9 Judgment apparatus

Claims (4)

A method for adjusting a surface inspection apparatus for adjusting a surface inspection apparatus for automatically detecting defects in an inspection object,
Step 10 of imaging the front or / and back surface of the inspection object with a camera and storing the full width full length image;
Step 12 for determining whether or not the defect can be confirmed from the stored image;
If the defect can be confirmed in step 12, step 14 is performed to determine whether or not the gray value difference between the image of the confirmed defect portion and the formation portion is large;
If the gray value difference is small in step 14, step 15 for adjusting the camera angle;
And a step 16 for adjusting a threshold value when the gray value difference is large in the step 14. In the adjustment method of the surface inspection apparatus according to claim 1,
The inspection object is a steel plate,
A method for adjusting a surface inspection apparatus, comprising: reexamining a detection system when a defect cannot be confirmed in step 12. An adjustment device for a surface inspection device for adjusting a surface inspection device for automatically detecting defects of an inspection object,
An image storage device that images the front or / and back surface of the inspection object with a camera and stores the full-width full-length image;
A determination is made as to whether or not defects can be confirmed from the image stored in the image storage device;
When the defect can be confirmed, it is determined whether the gray value difference between the confirmed defect portion and the formation portion image is large,
An adjustment device for a surface inspection apparatus, comprising: a determination device that determines that camera angle adjustment is performed when the gray value difference is small, and threshold adjustment is performed when the gray value difference is large. . In the adjustment apparatus of the surface inspection apparatus of Claim 3,
The inspection object is a steel plate,
An adjustment device for a surface inspection apparatus, wherein the detection system is reviewed when the defect cannot be confirmed by the determination device.