JP3410675B2 - Flaw direction discrimination system - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flaw-orientation discriminating system for accurately discriminating the orientation of flaws in a flaw-like portion extending at small intervals on the surface of an article to be inspected, such as the orientation of buffs on the surface of a rubber roller. Regarding

[0002]

2. Description of the Related Art For example, as shown in FIG. 4A, a rubber roller A used for precision office equipment such as a copying machine or a facsimile machine for feeding a paper generally has a main purpose of finishing to a predetermined dimensional accuracy. Has been buffed as. Therefore, on the roller surface, a plurality of flaw-shaped buff scratches B (marked portions) extending in the axial direction J at small intervals are formed.

As shown in an exaggerated cross section of FIG. 4 (B), the buff scratch B has an edge E1 on one side with an acute angle as compared with an edge E2 on the other side, as if the V shape is inclined. Make a serrated recess. Therefore, in the rubber roller A, depending on the direction F in which the edge E1 stands, that is, the direction of the buffed eye,
The frictional force with the paper is greatly different, which significantly affects the paper feeding performance. Therefore, it is extremely important to accurately inspect and determine the orientation of the buffed eye in order to guarantee product quality.

Conventionally, as a means for inspecting the direction of the buff eye, it is used that the shadow b of the buff scratch B is likely to appear depending on the direction of the illumination when illuminating the rubber roller A, as shown in FIG. 4B. There is. As shown in FIG. 5, this image shows an image of the roller surface when illuminated from a direction f1 in which a shadow b is likely to appear, and an image of a roller surface when illuminated from a direction f2 (direction in which it is difficult to emit) that is symmetrical to f1. The image is photographed, binarized, and the total area of the shadow b reflected on each of the binarized images c1 and c2 is compared to determine the direction of the buff eye.

[0005]

However, in the above-mentioned means, the appearance of the shadow (the size of the shadow area) is directly on the roller surface due to the change of the light quantity due to the deterioration of the light source or the change of the light quantity due to the artificial factor. The area of the shadow on the binarized image may change irregularly due to the change of the light amount and the threshold value of the binarization.

Therefore, it is difficult to maintain the determination accuracy, it is unstable, and the reliability of the determination is poor.

Therefore, in the present invention, the area of the shadow in the binarized image is not calculated and compared, but the image pitch between the shadows (image lines) in the binarized image is counted and the preset pitch length is set. Based on the fact that the frequency of the image pitch (pitch frequency) that falls within the section of (1) is calculated and the frequency of this pitch is compared, the direction of the flaws of the flaw-like part such as a subtle buff scratch that is difficult for the human eye to distinguish is determined. The object of the present invention is to provide a flaw-orientation determination system that can perform reliable and stable determination and that can operate while detecting normality / abnormality of the system itself.

[0008]

In order to achieve the above-mentioned object, the invention of claim 1 of the present application is a flaw direction for determining the direction of flaws of a flaw-like portion extending at a small interval on the surface of an article to be inspected. In the discrimination system, a first illuminator that illuminates an article to be inspected to form a first illuminating surface such that the shadow of the flaw clearly appears, and the illuminating of the first illuminator are the surface. A second illuminator that illuminates from a different direction that is substantially symmetrical with respect to the vertical line with respect to the first illuminating surface and forms a second illuminating surface that does not overlap with the first illuminating surface; A camera that captures an image of a surface and obtains an image, a binarized image obtained by binarizing the image by capturing image data , measuring the image pitch by scanning the binarized image , and measuring the image pitch.
Scan count means for dividing the pitch into intervals defined by the pitch to obtain the pitch frequency within the interval, the pitch frequency from the first illumination surface and the pitch frequency from the second illumination surface. And a discriminating means for inspecting the direction of the flaw based on the difference between the pitch frequencies.

[0009] In the second aspect of the present invention, the scanning counting means, the image pitch by the scanning of the binary image, pip
The pitch frequency of counting the frequency in each section that the section into a plurality of sections determined by Chi and counting, with sell interval pitch frequency data, said determination means, the first said section from the illumination surface of the -The total pitch frequency of the predetermined section of the pitch frequency data, the section from the second illumination surface-The total pitch frequency of the predetermined section of the pitch frequency data, and the difference between them are calculated, and the difference between the total pitch frequencies is used as a defect. It is characterized by testing the orientation of.

Further, in the invention of claim 3, the discrimination means facilitates the discrimination by classifying the pitch frequency of the section or the total pitch frequency into a small number range according to the magnitude of the number. There is.

Further, in the invention of claim 4, the discriminating means stores in advance the section / pitch frequency data of the standard inspected article, and compares it with the section / pitch frequency data obtained from the first illumination surface. It is characterized by making a distinction.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, a flaw direction discriminating system 1 (hereinafter referred to as system 1) of the present invention discriminates a flaw direction on a surface of an article W to be inspected. First and second illuminators 2L and 2R that illuminate from two directions that are substantially symmetrical with respect to X, and first and second illuminators that are illuminated by the first and second illuminators 2L and 2R. A camera 4 that captures images of the surfaces 3L and 3R and obtains respective images, and obtains binarized images 5L and 5R by capturing each image data, and scans the image lines 6 in each of the binarized images 5L and 5R. , A scanning counting means 7 for counting the image pitch P between 6 and 6 and obtaining the frequency (pitch frequency) of the image pitch P falling within the section G having a preset pitch length; Pitch frequency K from 3R
A discriminating means 9 for calculating a difference between L and KR and testing the direction of the flaw from the difference (KL-KR).

In this example, as shown in FIGS. 4 (A) and 4 (B), the system 1 causes a buff flaw B generated on the surface of a rubber roller A for paper feeding used in precision office equipment. An example will be described in which it is used to determine the direction of a flaw in a certain flaw-shaped portion B, that is, the direction of a buff. This flaw B is
It has a flaw shape extending in the axial direction J with a small interval, and its cross section has a sawtooth shape in which the edge E1 on one side is an acute angle as compared with the edge E2 on the other side as the V shape is inclined.

Although the rubber roller A itself can be used as the article W to be inspected, in FIG. 1, a buff-processed rubber tube that forms the surface of the rubber roller A by being attached to the core metal A1. The case where A2 is the inspected article W is illustrated.

Next, the first and the second used in the system 1
In this example, as the illuminators 2L and 2R, the illuminators 2L and 2R can be stably illuminated without flicker and the amount of light can be freely adjusted, for example, L
The ED lamp can be preferably used, but various types can be used depending on the type and size of the article W to be inspected.
It should be noted that a two-pole discharge type such as a fluorescent lamp, a sodium lamp, a neon lamp, etc. is not preferable because there is a flickering flickering depending on the frequency, which may adversely affect the captured image.

The first illuminator 2L is installed at an optimum optical axis angle α so that the shadow b of a flaw can clearly appear, and illuminates the article W to be inspected to make the first illumination. Surface 3
Form L. The second illuminator 2R is installed at a position where it can illuminate from a direction substantially symmetrical to the illumination of the first illuminator L with respect to the vertical line X standing at the center of the first illuminating surface 3L. The second illumination surface 3R is formed. The first and second illumination surfaces 3L and 3R are formed so as not to overlap each other, for example, with a distance in the axial direction J.

The first and second illumination surfaces 3L and 3R are also provided.
Are captured by the camera 4. As the camera 4, for example, a black and white CCD camera can be preferably adopted, and is substantially located on the vertical line X. In this example, the first and second illumination surfaces 3L, 3R are photographed at one time to obtain an image. The case is illustrated. It should be noted that the first and second illumination surfaces 3 using the two cameras 4
L and 3R can be individually photographed, and further, one camera 4 can be moved to individually photograph the first and second illumination surfaces 3L and 3R.

Next, in the scanning counting means 7, the camera 4
The image data taken in from is converted into black and white binarized signals by a well-known binarization process to obtain binarized images 5L and 5R, and these binarized images 5L and 5R (collectively referred to as 2
By scanning the binarized image 5), the image pitch P between the image lines 6 in each binarized image 5 is measured. In the binarized image 5, as shown in FIG. 2, image lines 6 ... Which are obtained by binarizing the image of the shadow b generated by the flaw B and other scratches are shown at small intervals. The image pitch P (pitch length) between the image lines 6 is converted into, for example, the number of pixels and measured.

In this measurement, first, a scanning region Y sampled from the binarized image 5 is scanned along a plurality of (N) scanning lines L extending in a direction perpendicular to the axial direction J, and each scanning region L is scanned. The image pitch P between the image lines 6 on the scanning line L is measured, and all the measured values are stored as image pitch data.

Further, as shown in Table 1, the pitch length is, for example, as follows: section G1 = pitch length 1 to 3, section G2 = pitch length 4 to 6, ... Section Gn = pitch length 3n−2 to 3n, a plurality of (n = 10 in this example) sections G1 to
It is divided into Gn in advance. Then, the image pitch data is distributed to each of the sections G1 to Gn, the pitch frequency for each section, which is the frequency of the image pitch P in each of the sections G1 to Gn, is measured, and the section / pitch frequency data that is the data is obtained.

[0021]

[Table 1]

Here, the reason why the pitch length is divided into the sections G1 to Gn is that the image pitch P varies to some extent. By dividing into a plurality of sections, the characteristic of the frequency distribution appears more clearly. .

Next, in the discrimination means 9, the binarized image 5
The difference KL-KR between the pitch frequency KL from L and the pitch frequency KR from the binarized image 5R is calculated, and this difference KL-
The direction of the flaws is checked based on KR.

The first and second examples of the discriminating means 9 will be specifically described with reference to Table 1. In the first example of the determination means 9, first, of the sections G1 to Gn, for example, predetermined sections G4 to Gn.
n is set as the discrimination section. And the binarized image 5
In L and R, all pitch frequencies KL (30 + 60 + 76 + 109 + 48 +) in the discrimination sections G4 to Gn, respectively.
48 + 18 = 389) and total pitch frequency KR (40 + 3)
6 + 38 + 58 + 27 + 6 + 12 = 217),
This difference KL-KR (= + 172) is calculated.

Then, the direction of the flaw is discriminated by the "absolute value" and the "positive / negative (+-)" of the difference KL-KR. "Positive" is a parameter for judging the direction of the flaw,
"Absolute value" is a parameter of the reliability. Therefore,
For example, when the "absolute value" is 50 or more, it is possible to determine, and when it is less than that, it is not possible to determine. In Table 1, the difference KL-KR (= + 17
2), and the direction of the flaw is determined to be “positive”.

Here, the first sections G1 to G3 other than the judgment sections G4 to Gn are likely to be noise at the time of measurement, and therefore, in order to make the judgment more accurate, this section is a judgment section. Are excluded from. In addition, as a method of taking the discrimination section, a section having the maximum pitch frequency (sometimes referred to as a maximum frequency section), and in Table 1 centering on G7,
A plurality of sections G6 to G8, sections G5 to G9, etc. can be adopted as the sections for determination.

In the second example of the discriminating means 9, only one section is specified as the discriminating section, and the difference between the pitch frequencies KL and KR in this one discriminating section is calculated and judged. As the determination section, it is preferable to adopt the maximum frequency section G7, and in Table 1, the difference KL-KR (109
−58 = + 51), and the direction of the flaw is determined to be “positive”. At this time as well, “positive / negative” is a parameter for determining the direction of a flaw, and “absolute value” is a parameter for its reliability.

In this example, as shown in Table 1, the scan counting means 7 exemplifies a case where pitch frequency data is obtained in all the sections G1 to Gn. The pitch frequency may be counted only by the above, which can improve the operation processing speed.

Further, in the discrimination means 9 of the first and second examples, the values KL and KR of the pitch frequencies (or the total pitch frequencies) counted in the discrimination section are directly calculated to make the determination. , The value of the pitch frequency (or the total pitch frequency) K
By classifying L and KR into a small number range according to the size of the number, the discrimination can be facilitated, and a large number of articles W to be inspected
Can be processed quickly. This example (third example)
For example, Table 2 will be described.

[0030]

[Table 2]

In Table 2, nine inspected articles W (No. 1)
~ No. 9) shows each determination result, and in each inspected article W, for example, the pitch frequencies KL and KR in the maximum frequency section (determination section) are set to be “large”,
Judgment is made by ranking into three ranges of "medium" and "low". Also in the difference KL-KR, the "absolute value (reliability)" is set to "large", "medium",
It is divided into three ranges, "low". (1) when there is a difference between the same ranges;-"small" when (high-high), (medium-medium), (low-low); (2) when there is a difference between adjacent ranges; -"High-medium", (medium-low), (medium-high), "low-medium" in case of "medium"; (3) otherwise ;-( high-low) , (Less-more) means "more";

In this example, when the "absolute value (reliability)" is "small", the judgment cannot be made, when it is "medium", the reliability is insufficient, and when it is "large", the direction of the flaw is judged. ing. However, it is also possible to make a distinction when it is "medium".

On the other hand, according to the study by the present inventor, the buff flaw has a peculiar depth and pitch arrangement depending on the buffing condition such as the type of baffle and the number of rotations. Therefore, FIG. As shown in B), it was found that the frequency distribution of the image pitch P also has characteristics. FIG. 3 (A),
(B) is a frequency distribution curve obtained by counting the section / pitch frequency data of the buff scratches in the sample for each lot at that time by performing the buff processing under different conditions, using the scanning counting means 7.

In the figure, the pitch length is divided into intervals of 5 pixels (corresponding to 0.25 mm in this example) G1-G6.
(In this way, according to the present invention, the interval is determined by the pitch.
It is confirmed that the frequency distribution characteristics differ from lot to lot, that is, from sample to sample, by counting the intervals and pitch frequencies. That is, although the section G3 is the maximum frequency section, the pitch frequency K in the sections G2 and G4 is K.
The ratio K4 / K2 of 2 and K4 has a large characteristic, and as the ratio K4 / K2 increases (the sample number increases), the buff roughness becomes rough.

As described above, in the buffing process, the frequency distribution of the image pitch P is characteristic for each lot. Therefore, the standard inspected article W is selected for each lot, the section / pitch frequency data (may be referred to as standard frequency data) is stored in advance, and the standard frequency data and the inspected article W to be judged are
By comparing the section / pitch frequency data obtained from each of the binarized images 5L and 5R of the above, it is determined whether the article W to be inspected is a lot article and whether the system 1 has no abnormality. Can be judged.

Specifically, only one of the section / pitch frequency data obtained from the binarized image 5L or the section / pitch frequency data obtained from the binarized image 5R matches the characteristic of the standard frequency data. Only in this case, the article W to be inspected is recognized as a lot article and there is no system abnormality, and the discrimination means 9 discriminates. Therefore, a discrimination error can be prevented and the reliability can be maintained high.

The system abnormality means that the photographing conditions such as the installation positions of the first and second illuminators 3L and 3R, the optical axis angle, and the light quantity of the article W to be inspected change during the inspection work. Means

The condition that the characteristics match is not particularly specified, but, for example, (1) the maximum frequency section matches; (2) the frequency of the maximum frequency section and the frequency of the section adjacent to this maximum frequency section. And (3) the ratios between the frequencies of adjacent sections are similar; (4) the total frequency and the total frequency in the first sections G1 to G3 where the possibility of noise is high. And the like are similar, and these can be set in combination.

Further, in the present invention, as described above, since the frequency distribution of the image pitch P has a characteristic due to the buff processing,
By adopting the section G in which this characteristic remarkably appears as the section for discrimination, the reliability and accuracy of the discrimination are guaranteed particularly high.

The present invention can be applied to the determination of the direction of a delicate flaw-like flaw which is difficult to discriminate with human eyes, in addition to the determination of the orientation of the buff eye caused by the buff processing.

[0041]

Since the present invention is constructed as described above,
It is possible to reliably and stably determine the direction of a flaw in a flawed portion such as a subtle buff that is difficult for the human eye to distinguish, and to operate while detecting whether the system itself is normal or abnormal.

[Brief description of drawings]

FIG. 1 is a side view showing an embodiment of the present invention.

FIG. 2 is a diagram illustrating an image pitch.

FIG. 3 is a diagram showing a frequency distribution of image pitch P for each lot in (A) and (B) buff processing.

FIG. 4A is a perspective view showing a buff flaw generated on the surface of a rubber roller A, and FIG. 4B is a sectional view showing the buff flaw exaggeratedly.

FIG. 5 is a diagram illustrating a conventional technique.

[Explanation of symbols]

3L First illumination surface 3R Second illumination surface 4L first illuminator 4R Second illuminator 4 cameras 5L, 5R binary image 6 image lines 7 Scan counting means 9 discrimination means B flaw b Shadow of a flaw G1-Gn section KL, KR pitch frequency P image pitch W Inspected item X vertical line

Claims (4)

(57) [Claims] 1. A flaw direction discriminating system for discriminating the direction of a flaw in a flaw-like portion extending at a small interval on the surface of the article, wherein the shadow of the flaw clearly appears. The first illumination surface that illuminates the first illumination surface and the illumination of the first illumination element illuminates from different directions that are substantially symmetrical with respect to a vertical line with respect to the surface. A second illuminator that forms a second illuminating surface that does not overlap with, a camera that captures an image by capturing the first illuminating surface and the second illuminating surface, and the image is captured and the image is binarized. with sell binarized image, the image Pi by scanning the binary image
Switch and measure the measured image pitch
Scanning counting means for obtaining a pitch frequency within the section by dividing the section into sections determined by, and calculating a difference between the pitch frequency from the first illumination surface and the pitch frequency from the second illumination surface, A flaw direction discriminating system comprising: a discriminating means for examining the direction of a flaw based on the difference in pitch frequency. 2. The scanning counting means comprises a plurality of sections in which the image pitch obtained by scanning a binarized image is determined by the pitch.
The pitch frequency obtained by counting the frequency within each section divided into
And counting, with sell interval pitch frequency data, said determination means, the first full pitch frequency of a predetermined section of the section pitch frequency data from the illumination surface, interval pitch from the second illumination plane 2. The flaw direction discriminating system according to claim 1, wherein all pitch frequencies in the predetermined section of the frequency data and the difference between them are calculated, and the direction of the flaws is tested from the difference between all the pitch frequencies. 3. The discriminating means, the pitch frequency of the section,
3. The flaw-oriented discrimination system according to claim 1, wherein the discrimination is facilitated by ranking the total pitch frequencies into a small number range according to the magnitude of the number. 4. The discriminating means is a section of a standard inspected article.
4. The system for discriminating a flaw direction according to claim 1, wherein the pitch frequency data is stored in advance and is discriminated in comparison with the section / pitch frequency data obtained from the first illumination surface. .