JPH05209733A - Surface-state inspecting apparatus - Google Patents

Abstract

PURPOSE:To make it possible to achieve pickup of an image without distorsion at an irregular part and compact configuration by arranging an image pickup means, which is oriented in the direction approximately orthogonal to a surface under inspection, and providing a bright light source and a dark light source at the right and left of the image pickup means. CONSTITUTION:When there is a protruding defect on a surface under inspection 10, the light having the large luminance, which is emitted from a bright light source 6, is regularly reflected and cast to an image pickup means 4, and the light having the small luminance from a dark light source 8 is regularly reflected and cast to the means 4. When a recessed defect is present in the surface under inspection 10, the light having the small luminance, which is emitted from the dark light source 8, is regularly reflected and cast into the means 4, and the light having the large luminance from the bright light source 6 is regularly reflected and cast to the means 4. The image of the surface under inspection is sent to an image processing means 36 from the means 4. The means 36 performs the defect inspection, i.e., the detection of the presence or absence of a defect and the detection of the position of the defect, based on the received image data. An irregularity judging means 38 judges whether the defect is a recessed defect or a protruding defect.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface state inspection apparatus for detecting a deformed portion such as a surface defect on a surface to be inspected and discriminating whether the deformed portion is concave or convex.

[0002]

2. Description of the Related Art Conventionally, a surface to be inspected is irradiated with light, and the surface state of the surface to be inspected, that is, an irregular portion on the surface to be inspected is inspected based on the reflected light from the surface to be inspected. It is known how to do it. For example, in Japanese Patent Laid-Open No. 62-233710, the surface to be inspected is irradiated with light, the reflected light from the surface to be inspected is projected on a screen, and the surface defect of the surface to be inspected is determined from the sharpness of the projected image. A technique for automatically detecting is disclosed.

Further, as one of the above-mentioned surface condition inspection methods, the surface to be inspected is irradiated with bright and dark light having a brightness gradient in which the brightness gradually changes in one direction, that is, reflection from the surface to be inspected. The light is received to image the surface to be inspected, and the surface defect of the surface to be inspected is detected based on the brightness change in the image of the surface to be inspected, and the defect is convex or convex and concave or concave. Since the pattern of the brightness change in the defect corresponding area on the surface image to be inspected is different from the case of the defect, a method of discriminating whether the defect is a convex defect or a concave defect by focusing on the pattern of the brightness change Are considered (for example, Japanese Patent Application No. 3-134092, Japanese Patent Application No. 3-225038
issue).

[0004]

By the way, in the inspection of the surface defect using the above-mentioned bright and dark light, the light and dark light are obliquely incident on the surface to be inspected, and the light is specularly reflected obliquely from the surface to be inspected. Since the image pickup means for receiving light is also arranged obliquely with respect to the surface to be inspected, there is a problem that the image of the defective portion picked up by the image pickup means is distorted, and as a result the inspection accuracy is lowered. ..

Further, in the apparatus for inspecting surface defects by irradiating the surface to be inspected with the above-mentioned bright and dark light, it is necessary to use, as the light irradiating means, one having the above-mentioned brightness gradient in which the brightness gradually changes. However, such a light irradiating means is inevitably large in size, that is, since the brightness has to be gradually changed, it is not possible to form a gradually changing brightness gradient only with a bright light source and a dark light source, no matter how simple. It is difficult, at least another intermediate light source is required, and there is a problem that the light irradiation means becomes large.

In view of the above circumstances, an object of the present invention is to determine whether a deformed portion such as a surface defect on the surface to be inspected has a concave shape or a convex shape by irradiating the surface to be inspected with light. In order to provide a surface condition inspection apparatus capable of capturing an image without distortion of a deformed portion and enabling downsizing of the apparatus.

[0007]

In order to achieve the above object, a surface condition inspection apparatus according to the present invention detects a deformed portion on a surface to be inspected and determines whether the deformed portion has a concave shape or a convex shape. A surface state inspection device for determining whether a surface to be inspected is arranged in a direction substantially perpendicular to the surface to be inspected, and the left and right sides of the image capturing means with the imaging means sandwiched therebetween. And a dark light source that emits dark light having a brightness smaller than the brightness of the bright light of the bright light source, and a bright light source that emits a bright light with high brightness that illuminates the imaging area by the imaging means on the surface to be inspected, And a concave-convex discriminating means for discriminating whether the deformed portion has a concave shape or a convex shape based on a luminance change state in the image of the surface to be inspected picked up by the image pickup means.

[0008]

In the surface condition inspection apparatus constructed as described above, the image pickup means is arranged in a direction substantially perpendicular to the surface to be inspected, and the bright light source and the dark light source are arranged on the left and right sides of the image pickup means. Since the light source is arranged, as described in detail below, when the irregular portion such as a surface defect has a convex shape, half of the area corresponding to the irregular portion in the surface image to be inspected on the bright light source side is Along with the high brightness corresponding to the bright light source, the half on the dark light source side has a small brightness corresponding to the dark light source, and when the irregular portion has a concave shape, the brightness of the area corresponding to the irregular portion in the surface image to be inspected is increased. Half of the light source side has a small brightness corresponding to a dark light source, and half of the dark light source side has a large brightness corresponding to a bright light source. Therefore, it is possible to discriminate between the concave shape and the convex shape by detecting the arrangement of such large luminance and small luminance.

Further, in the above-mentioned surface condition inspection device,
Since the image pickup means is arranged in a direction substantially perpendicular to the surface to be inspected, the image of the deformed portion imaged by the image pickup means is free from distortion, and as a result, the accuracy of inspection is improved. ..

Further, in the above-mentioned surface condition inspection apparatus, it is sufficient to simply use the bright light source and the dark light source as the light irradiating means, and the light irradiating means for irradiating the light and dark light having the above-mentioned brightness gradient in which the brightness gradually changes. As compared with the case of using, the intermediate light source that emits light of at least intermediate brightness as described above is unnecessary, and the spectral irradiation means can be downsized.

[0011]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a front view showing an embodiment of a surface condition inspection apparatus according to the present invention, and FIG. 2 is a bottom view of the surface condition inspection apparatus shown in FIG.

The surface state inspection device 2 shown in the figure is for inspecting a surface defect which is an example of a deformed portion on the surface to be inspected.
The image pickup means 4 includes a CCD camera, a bright light source 6 and a dark light source 8, and an image processing means 36 for processing image data of the image picked up by the image pickup means 4. The image pickup means 4 is for picking up an image of the surface 10 to be inspected and is arranged in a direction substantially perpendicular to the surface 10 to be inspected, that is, the central axis p in the image pickup direction of the image pickup means 4 is to be inspected. surface
It is arranged so as to be substantially perpendicular to 10. The bright light source 6 is a light source that emits light of large brightness, the dark light source 8 is a light source that emits light of brightness smaller than that of the light of the bright light source 6, and they sandwich the imaging means 4. In order to illuminate the imaging area of the surface to be inspected by the imaging means 4 on the surface 10 to be inspected, for example, the optical axes q facing the light irradiation directions of the respective light sources 6 and 8. , R are arranged on the surface 10 to be inspected so as to intersect with the central axis p, and the central axis p and the optical axes q, r are arranged.
The angles θ ₁ and θ ₂ formed by and are arranged to be the same. Further, the bright light source 6 and the dark light source 8 are respectively shown in FIG.
As shown in FIG. 3, the light source is composed of an elongated linear light source, and they are arranged in parallel with the image pickup means 4 interposed therebetween.

FIG. 3 is a diagram showing an image pickup state by the image pickup means 4 when a convex defect is present on the surface 10 to be inspected, and FIG. 4 is a diagram showing an image of the surface to be inspected imaged in the state shown in FIG. As shown in the figure, when the convex defect 12 is present on the surface 10 to be inspected,
The bright light source side surface (the left side surface in the figure) 12a of the convex defect 12
The light of high brightness emitted from the bright light source 6 is specularly reflected by the light source 6 and enters the image pickup means 4, and is emitted from the dark light source 8 by the surface 12b of the convex defect 12 on the dark light source side (the surface on the right side in the figure). The light with small brightness is specularly reflected and enters the image pickup means 4.

Therefore, the surface image to be inspected in that case is as shown in FIG.
As shown in FIG. 4, in a predetermined area on the side where the bright light source 6 is located in the surface image 16 to be inspected (on the left side in the figure), the light with high brightness from the bright light source 6 is directly removed from the surface of the surface to be inspected where no defect exists. A bright light source corresponding region 18 having high brightness formed by being reflected and incident on the image pickup means 4 is formed, and in a predetermined region on the side (right side in the drawing) where the dark light source 8 is located in the surface image 16 to be inspected. Is
A dark-light-source-corresponding region 20 having a low brightness is formed by the light having a small brightness from the dark light source 8 being specularly reflected from the surface of the surface to be inspected where there is no defect and incident on the image pickup means 4.
Except for those areas 18 and 20, basically, non-reflective areas where specular reflection light from any light source does not enter (accurately diffuse reflection light enters but extremely small light quantity) are 22a, 22b, and 22c. In the inspection area sandwiched between the areas 18 corresponding to both light sources (the above-mentioned non-reflection area 22b), the light which is specularly reflected from the above-mentioned convex defect 12 is incident on the image pickup means 4 and corresponds to the convex defect. As can be easily understood from the above description of the light in which the region 24 is formed and which is specularly reflected from the convex defect 12, the half on the bright light source side (the left side in the drawing) in the convex defect corresponding region 24 is the bright light source. Large brightness area corresponding to the brightness of
Therefore, half of the dark light source side (right side in the figure) is a small brightness area 28 corresponding to the brightness of the dark light source.

FIG. 5 is a view showing an image pickup state by the image pickup means 4 when a concave defect 14 is present on the surface 10 to be inspected, and FIG. 6 is shown in FIG.
It is a figure which shows the to-be-inspected surface image imaged in the state shown in FIG. As shown in the figure, when a concave defect 14 exists on the surface 10 to be inspected, the surface of the concave defect 14 on the bright light source side (the surface on the left side in the figure)
Light having a small brightness emitted from the dark light source 8 by 14a is specularly reflected and enters the image pickup means 4, and is illuminated by the bright light source 6 by the dark light source side surface (the right surface in the figure) 14b of the concave defect 14. The light having a large brightness is specularly reflected and enters the image pickup means 4.

Therefore, the surface image to be inspected in that case is as shown in FIG.
As shown in FIG. 3, in the predetermined area on the side where the bright light source 6 is located (left side in the figure) in the surface image 16 to be inspected, the light of high brightness from the bright light source 6 is specularly reflected from the portion of the surface to be inspected where there is no defect. Then, a bright light source corresponding region 18 having a high brightness formed by being incident on the image pickup means 4 is formed, and a predetermined region on the side (right side in the figure) where the dark light source 8 is located in the surface image 16 to be inspected is formed. A dark light source corresponding region 20 having a low brightness is formed by the specular reflection of the light with low brightness from the dark light source 8 from the portion of the surface to be inspected where there is no defect and the incidence to the image pickup means 4, and these regions 18 are formed. , 20 are non-reflective areas where specularly reflected light from any light source does not enter (accurately diffused reflected light enters but extremely small light quantity) 22a, 22b, 2c, and areas corresponding to both light sources described above. The inspection area sandwiched between 18 and 20 (above non-reflection area 22b) is described above. It is easily understood from the description of the light specularly reflected from the concave defect 14 described above that the concave defect corresponding region 30 formed by the light specularly reflected from the concave defect 14 being incident on the image pickup means 4 is formed. As described above, half of the concave defect corresponding area 30 on the bright light source side (left side in the figure) is the brightness small area 32 corresponding to the brightness of the dark light source, and half on the dark light source side (right side in the figure) is the brightness of the bright light source. It becomes the corresponding brightness large area 28.

The surface image 16 to be inspected as described above is inputted from the image pickup means 4 to the image processing means 36 (see FIG. 1), and the image processing means 36 carries out a defect inspection based on the inputted image data, that is, whether or not there is a defect. The detection, the detection of the defect position, and the determination of whether the defect is a concave defect or a convex defect are performed.

That is, the image processing means 36 main-scans the input surface image 16 to be inspected along the X ₁ direction (direction corresponding to the X ₁ direction in FIG. 2) and at the same time Y ₁ perpendicular to the X ₁ direction.
Full scanning is performed by performing sub-scanning along the direction. In this case, main scanning lines (pixel rows) that do not pass through the defect corresponding areas 24 and 30 in the inspected surface image 16 shown in FIGS.
As shown in FIG. 7, the brightness (image signal level) at L ₁ is from the left toward the X ₁ direction, the minimum brightness in the non-reflection area 22a, the large brightness in the bright light source corresponding area 18, and the minimum brightness in the non-reflection area 22b. Bright and dark light source compatible area 20 has low brightness and no reflection area
The minimum brightness is obtained at 22c. That is, the non-reflection area between the bright light source corresponding area 18 and the dark light source corresponding area 20, that is, the inspection area 22b.
In the case of, there is no defect, so that the brightness remains uniform and minimal.

On the other hand, as shown in FIG. 8, the luminance on the main scanning line L ₂ passing through the convex defect corresponding region 24 in FIG. 4 shows that the convex defect corresponding region 24 exists in the inspection region 22b. In the area 24, the left half has high brightness similar to the bright light source corresponding area 18, and the right half has low brightness similar to the dark light source corresponding area 20.

As shown in FIG. 9, the luminance of the main scanning line L ₂ passing through the concave defect corresponding region 30 in FIG. 6 is such that the concave defect corresponding region 30 exists in the inspection region 22b.
In 30, the left half has a small brightness similar to the dark light source corresponding area 20,
The right half has the same high brightness as the bright light source corresponding region 18.

Therefore, the image processing means 36 scans the image of the surface to be inspected, examines the luminance on each scanning line, and confirms that the luminance of the inspection area 22b between the bright light source corresponding area 18 and the dark light source corresponding area 20 is equal. Similarly, if there is a minimum brightness, it is determined that there is no defect within that range, and if there is a brightness protruding portion having a brightness larger than the minimum brightness in the inspection area 22b, there is a defect at the position where the brightness protruding portion exists. To determine.

Further, in this case, the unevenness discriminating means 38 provided in the image processing means 36 examines the luminance of the luminance protruding portion, and when the bright light source corresponding region side has high luminance and the dark light source corresponding region side has low luminance. (See FIG. 8) it is determined that the defect is a convex defect, and when the defect is opposite (see FIG. 9), it is determined that the defect is a concave defect, thereby determining the unevenness.

In the above embodiment, the presence / absence of a defect, the position of the defect, and the unevenness of the defect are determined based on the brightness on the main scanning line. It is also possible to perform the calculation based on the luminance differential value or the luminance differential emphasis value (the sum of the luminance and the luminance differential value) on the main scanning line.

In the above-mentioned surface condition inspection apparatus, the image pickup means 4 is arranged in a direction substantially perpendicular to the surface 10 to be inspected as described above, and the bright light source 6 and the dark light source 8 are arranged on the left and right sides of the image pickup means 4. Therefore, when the defect is a convex defect 12, half of the defect corresponding region in the surface image to be inspected on the bright light source side has a large brightness corresponding to the bright light source 6 and the dark light source side. Half of the brightness is small corresponding to the dark light source 8, and when the defect is the concave defect 14, half of the defect corresponding region in the inspection surface image on the bright light source side has a small brightness corresponding to the dark light source 8. The half on the dark light source side has a large luminance corresponding to the bright light source 6. Therefore, it is possible to discriminate between the concave defect and the convex defect by detecting the arrangement of such large brightness and small brightness.

Further, in the above-mentioned surface condition inspection device,
Since the image pickup means 4 is arranged in a direction substantially perpendicular to the surface 10 to be inspected, the image of the defective portion picked up by the image pickup means becomes free of distortion, and as a result, the accuracy of inspection is improved. To do.

Further, in the above-mentioned surface condition inspection device, it is sufficient to simply use the bright light source 6 and the dark light source 8 as the light irradiating means, and the light for irradiating the light and dark light having the above-mentioned brightness gradient in which the brightness gradually changes. As compared with the case where the irradiation means is used, an intermediate light source that emits light of at least intermediate brightness is unnecessary, and the spectral irradiation means can be downsized.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of a surface state inspection device according to the present invention.

FIG. 2 is a bottom view of the embodiment shown in FIG.

FIG. 3 is a diagram showing an imaging state when a convex defect is present.

FIG. 4 is a diagram showing a captured image in the imaging state shown in FIG.

FIG. 5 is a diagram showing an imaging state when a concave defect is present.

FIG. 6 is a diagram showing a captured image in the imaging state shown in FIG.

FIG. 7 is a diagram showing the luminance on the line L _{1 in} FIGS.

FIG. 8 is a diagram showing luminance on a line L _{2 in} FIG.

9 is a diagram showing the luminance on the line L _{2 in} FIG.

[Explanation of symbols]

 4 image pickup means 6 bright light source 8 dark light source 10 surface to be inspected 36 image processing means 38 unevenness determination means

Claims (1)

[Claims] 1. A surface state inspection device for detecting a deformed portion on a surface to be inspected and determining whether the deformed portion has a concave shape or a convex shape, wherein the surface to be inspected is an image of the surface to be inspected. The image pickup means arranged in a direction substantially perpendicular to the image pickup means, and the image pickup means are arranged on the left and right sides of the image pickup means, and the image pickup area on the surface to be inspected by the image pickup means is irradiated. A bright light source that emits bright light having a large luminance, a dark light source that emits dark light having a luminance smaller than that of the bright light of the bright light source, and the irregular portion based on the luminance change state in the image of the surface to be inspected captured by the image capturing means. An apparatus for inspecting a surface state, comprising: a concave-convex discriminating means for discriminating whether the surface is concave or convex.