JP7087533B2 - Surface condition inspection device and surface condition inspection method - Google Patents

Description

The present invention relates to a surface condition inspection apparatus and a surface condition inspection method.

A device for detecting the surface state of an object by irradiating an object such as a metal plate or a tire with light of a plurality of colors and individually recognizing the brightness or intensity of the reflected light is known.

For example, in Patent Document 1, light having a different wavelength is irradiated from two light sources to a metal body to be inspected, and the reflected light is received by a light receiving camera prepared for each wavelength to detect the brightness. The surface state of the object to be inspected, which is a metal body, is detected by utilizing the fact that the unevenness of the object to be inspected causes a difference in brightness between the two wavelengths of light. In Patent Document 2, light having different wavelengths is irradiated to the surface of the sidewall portion of the tire from two light sources, and the intensity of the reflected light is detected. The surface state of the metal object to be inspected is detected by utilizing the fact that the intensity of light of two wavelengths is different due to the unevenness of the object to be inspected.

Japanese Patent No. 6061059 Japanese Unexamined Patent Publication No. 2010-249700

However, in order to irradiate an object to be inspected with two lights having different wavelengths, collect the reflected light with a camera different for each wavelength, acquire intensity or luminance data, and perform arithmetic analysis, an expensive and complicated device is required. You will need it. In particular, when a long object such as a cable is to be inspected, it is often necessary to inspect not only in the longitudinal direction but also in the circumferential direction, and the device is often more expensive than a flat plate.

For example, Patent Document 1 presents an example of reducing the cost by using a monochrome line sensor camera instead of a color line sensor camera, but a receiver is required for each wavelength.

For example, Patent Document 2 presents an example in which light of different wavelengths is irradiated from the same direction and the reflected light is received by a line sensor camera. Since the only data that can be used is the distance from the light source to the inspection position of the object to be inspected, the intensity data is taken for each wavelength and the surface state is estimated from the relative relationship. Since the intensity data of each wavelength has variations, the data processing becomes more complicated when there are two obtained data than in the case of one.

An object of the present disclosure is to provide an apparatus for inspecting a surface condition using a cheaper device based on a simple operation principle.

According to one aspect of this embodiment
A first light source that irradiates the inspection area on the surface of the object to be inspected with light of the first hue, and
A second light source that irradiates the inspection area with light having a second hue different from that of the first hue.
A color camera that receives the reflected light from the surface of the object to be inspected, and
It is equipped with an analyzer that analyzes the hue distribution of the reflected light from the inspection area by using the received light signal output from the color camera as an input.
Provided is a surface condition inspection apparatus in which the irradiation direction of the first light and the irradiation direction of the second light are different.

According to the present disclosure, it is possible to provide an apparatus for inspecting a surface condition by using a cheaper device by a simple operation principle.

FIG. 1 is a diagram illustrating a basic configuration of the inspection device of the present application. FIG. 2A is a diagram illustrating a detection principle of the inspection device of the present application. FIG. 2B is a diagram illustrating a detection principle of the inspection device of the present application. FIG. 2C is a diagram illustrating the detection principle of the inspection device of the present application. FIG. 3 is a diagram schematically depicting the color wheel. FIG. 4 is a diagram illustrating the relationship between hue and abnormality detection in the inspection device of the present application. FIG. 5 is a diagram showing an example of arrangement of a light source and a color camera when a linear body is an object to be inspected. FIG. 6 is a diagram showing an arrangement example of a color camera in the arrangement example of FIG. FIG. 7 is a diagram illustrating an irradiation range of light from a light source in the arrangement example of FIG. FIG. 8 is a flow chart illustrating a typical detection logic of the inspection device of the present application. FIG. 9 is a diagram schematically showing how an abnormal portion is detected by the inspection device of the present application. FIG. 10A is a diagram showing an example of arrangement of a light source and a light receiver of an existing inspection device when a linear body is used as an object to be inspected. FIG. 10B is a diagram showing an arrangement example of a light source and a light receiver of an existing inspection device when a linear body is used as an object to be inspected. FIG. 11 is a diagram in which an inspected object having a defective unevenness portion and a good unevenness portion is inspected by (a) an existing inspection device and (b) the inspection device of the present application, and the results are summarized by the height of the unevenness. FIG. 12 is an experimental example in which surface irregularities were detected using an existing inspection device and the inspection device of the present application, and the results are summarized by the height and length of the irregularities.

[Explanation of Embodiments of the present disclosure]
First, embodiments of the present disclosure will be listed and described.

(1) The surface condition inspection apparatus according to one aspect of the present disclosure includes a first light source that irradiates an inspection area on the surface of an object to be inspected with light of the first hue, and a second hue different from the first hue. A second light source that irradiates the inspection area with the light of the above, a color camera that receives the reflected light from the surface of the object to be inspected, and a light receiving signal output from the color camera as inputs from the inspection area. It is a surface condition inspection device including an analyzer for analyzing the hue distribution of the reflected light, in which the irradiation direction of the first light and the irradiation direction of the second light are different.

Even if an industrial product is manufactured as a uniform surface, the surface is not uniform and the surface shape differs from place to place. It is required to discriminate and eliminate surface conditions that are recognized as poor appearance such as scratches and irregularities. When the inventors of the present invention irradiate the object to be inspected with light of different hues from two light sources arranged at different positions at the same time, the reflected light differs depending on the surface condition which is the difference in the shape of the surface of the object to be inspected. I found that it would be a hue. Then, the reflected light is received by the color camera, and the surface condition inspection device is completed to detect the surface condition based on the received light signal output from the color camera.

When an object to be inspected with a uniform surface condition is irradiated with light of different hues from two light sources, the object to be inspected has constant reflection at any location, and reflected light having a certain intermediate hue is obtained. Be done.

On the other hand, in an inspected object having protrusions or concave portions due to scratches or swelling on the surface, the reflection of light emitted from each light source changes depending on the surface condition of the inspected object. Especially in the shaded area, the reflection disappears, and the reflected light having a hue different from that in the case of the object to be inspected having a uniform surface state can be obtained. When the above two light sources are arranged so as to irradiate the object to be inspected from different directions, the hue of one of the irradiated lights may be weakened or strengthened depending on the surface condition of the inspected object, so that the hue of the reflected light is changed. Instead of a constant neutral hue, a hue of a light source or a hue close to that hue can be obtained.

Here, the first hue group in which the first hue and the hue close to the hue are combined, the second hue group in which the second hue and the hue close to the hue are combined, the first hue group and the second hue are combined. We define three hue groups of intermediate hue groups in the middle of the group. Then, when the hue of the reflected light of the inspected object is in the first hue group or the second hue group, it is presumed that the surface condition of the inspected object is abnormal. On the other hand, when it is in the intermediate hue group, it is presumed that there is no abnormality in the inspected object. Here, the abnormality means unevenness mainly caused by scratches or blisters on the surface, and is judged to be defective as the product. Using a sample whose surface unevenness is known, the first hue group, the second hue group, and the intermediate hue group are registered in the device in advance, and the reflected light is the first hue group or the second hue group. If it is determined that there is no abnormality in the case of an abnormality and no abnormality in the case of an intermediate hue group and the output is made, an inspection device for determining the surface condition can be obtained.

(2) The analyzer detects the hue of each pixel of the image corresponding to the inspection region, and when there is a region in which the pixels of the first hue or the pixels of the second hue are continuous. , The surface condition inspection device may be configured to determine that unevenness is present.

By determining the hue for each pixel, it is possible to detect very fine changes in the surface state. However, too detailed analysis is susceptible to noise. In addition, the size of unevenness is often included in the criteria for judging abnormalities in the target product. Therefore, by determining the hue change as the size of the region, it is possible to detect only a predetermined defect while eliminating noise, and the accuracy of the inspection device can be further improved.

(3) The object to be inspected has a surface extending in one axial direction, the axial direction is the Z direction, and the center of the inspection region is the origin in the X direction, the X direction, and the Z direction in the normal direction of the surface. When the direction orthogonal to is the Y direction, the first light source and the second light source are in the XZ plane, respectively, and the first light source is in the region where Z is positive, and the second light source is the second light source. The light source may be the surface condition inspection apparatus according to which Z is arranged in a negative region and the color camera is arranged on an XY plane.

By placing the two light sources in opposite directions with the color camera as a detector in between, a significant difference in the degree of reflection on the surface to be inspected is likely to occur, and the accuracy of detection is improved.

(4) The object to be inspected has a cylindrical surface having a central axis in the Z direction.
The first light source and the second light source are light sources that irradiate light in the axial direction of the annulus in an annular shape, and are arranged so as to be centered on the Z axis on different planes parallel to the XY plane. Has been
It may be a surface condition inspection device in which a plurality of the color cameras are arranged on an XY plane so as to surround the cylindrical surface.

When the object to be inspected has a linear or rod-like shape such as a cable or a rod, the surface to be inspected exists over the entire circumference around the longitudinal direction. In order to inspect the entire circumference evenly at the same time, it is advisable to illuminate the entire circumference at the same time with an annular light source and arrange multiple color cameras to detect the reflected light from the surface at the same time.

(5) It has a plurality of the first light sources, the plurality of the first light sources are concentrically arranged on the same plane, has a plurality of the second light sources, and has a plurality of the second light sources. The light sources may be surface condition inspection devices concentrically arranged on the same plane.

By using a plurality of light sources in this way, the uniform irradiation range can be increased, so that the efficiency of inspection can be improved.

(6) Further, in one aspect of the present disclosure, the light of the first hue and the light of the second hue different from the first hue are applied to the inspection area on the surface of the object to be inspected from the inspection area. Provided is a surface condition inspection method in which the hue of the reflected light of the above is detected for each pixel in which the inspection region is subdivided, and the unevenness of the surface of the object to be inspected is detected from the plane distribution of the hue in the inspection region.

(7) The object to be inspected has a cylindrical surface extending with the Z axis as the central axis.
When the direction of the Z axis is the Z direction, and any one direction within the normal of the inspection area is the X direction, and the direction orthogonal to the X direction and the Z direction is the Y direction.
The light of the first hue and the light of the second hue are in the XZ plane from the region where Z is positive for the first light source and the region where Z is negative for the second light source, respectively. Irradiates the surface from
The reflected light may be a surface condition inspection method detected on an XY plane.

[Details of Embodiments of the present disclosure]
A specific example of the surface condition inspection apparatus according to the embodiment of the present disclosure (hereinafter referred to as “the present embodiment”) will be described below with reference to the drawings. In the following description, the same or corresponding elements are designated by the same reference numerals, and the same description is not repeated for them. It should be noted that the present invention is not limited to these examples, and is indicated by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

As shown in FIG. 1, the basic configuration of the surface condition inspection device according to the present embodiment includes a first light source 10, a second light source 20, a color camera 30, an analyzer 40, and an output device 50. The first light source 10 irradiates the light 11 of the first hue toward the surface 61 of the object 60 to be inspected. The second light source 20 irradiates the light 21 of the second hue toward the surface 61 of the object 60 to be inspected. Normal reflected light 73 or abnormal reflected light 71 and 72 are generated as reflected light from the surface 61 irradiated with both the light 11 of the first hue and the light 21 of the second hue, and the color camera 30 reflects the light. Receives light. In this example, the case where the convex portion 62, which is a bulging portion of the surface, is present on the surface 61 of the object to be inspected 60 is illustrated.

Here, the hue inspection of the analyzer 40 in the inspection apparatus will be described once. FIG. 3 is a diagram schematically depicting the color wheel.
As shown in FIG. 3, the hue forms a hue circle based on the three primary colors of light, red (R), green (G), and blue (B). The analyzer used in the present invention is one that can set the color wheel evenly divided. Further, among the divided hues, the one that can set the hue group of the specified region as abnormal and the non-designated region as normal is used.

FIG. 4 is a diagram illustrating the relationship between hue and abnormality detection in the inspection device of the present application, and shows a part of the hue circle of FIG. Since the present invention uses two hue light sources, as shown in FIG. 4, the first hue 101, the abnormal hue 103 close to the first hue (both are collectively referred to as the first hue group), and the second. It can be divided into a hue 102, an abnormal hue 104 close to the second hue (combined to form a second hue group), and a normal hue 105 (intermediate hue group) which is an intermediate hue. Using a sample whose surface state is known in advance, the range of the first hue group, the second hue group, and the intermediate hue group is preset in the analyzer. Hue inspection can be performed by determining that the reflected light corresponding to the hues of the first hue group and the second hue group is abnormal and setting the analyzer so that the light is output to the output device 50.

The processing of the surface condition inspection apparatus will be described with reference to FIG.
When the irradiation light 11 having the first hue and the irradiation light 21 having the second hue different from the irradiation light 11 are simultaneously irradiated on the surface 61 of the object 60 to be inspected, the reflected light is normal having an intermediate hue group. The reflected light 73, or the abnormal reflected light 71, 72 having the hue of the first hue group or the second hue group is generated. The reflected light is imaged by the color camera 30. The captured pixel-by-pixel data is input to the analyzer 40. The analyzer 40 is a device including a function capable of discriminating the hue for each pixel, and outputs information including a result of determining whether the surface condition is good or bad and an abnormality being determined to the output device 50. The output device 50 is an arbitrary output device such as an alarm panel provided with a lamp or the like, a display device such as a liquid crystal monitor, or a voice output device such as a buzzer, and conveys an inspection result to an operator or the like.

The analyzer 40 is a dedicated device or a device including a pre-programmed computer, and detects the hue of each pixel of the image corresponding to the inspection area. Further, when there is a region where the pixels of the first hue group are continuous or a region where the pixels of the second hue group are continuous, it may be configured to determine that the unevenness is present.

Hereinafter, the relationship between the unevenness of the surface and the hue of the reflected light will be described with reference to FIGS. 2A to 2C. Each figure has a different surface condition of the object to be inspected 60, and other configurations are the same as those in FIG.
In the object to be inspected 60 shown in FIG. 2A, the surface 61 has no irregularities. In this case, all parts of the surface 61 irradiated with light are in the same reflected state, and only the normally reflected light 73 having a hue of the intermediate hue group is imaged by the color camera. Since the captured image is composed of the normal reflected light 73, the analyzer 40 determines that the image is normal.

The object to be inspected 60 shown in FIG. 2B has a convex portion 62 on the surface 61. In this case, the irradiation light of the first hue is reflected on the right side of the convex portion 62, but is shaded on the left side and is not reflected. Similarly, the second irradiation light is shaded on the right side of the convex portion 62 and is not reflected, but is reflected on the left side. As a result, the reflected light on the right side of the convex portion 62 becomes the abnormal reflected light 71 having the hue of the first hue group, and the reflected light on the left side becomes the abnormal reflected light 72 having the hue of the second hue group. Since not only the normally reflected light 73 but also the abnormally reflected lights 71 and 72 are imaged by the color camera, the analyzer 40 determines that the abnormality is present, and the abnormality output is output to the main device 50.

The inspected object 60 shown in FIG. 2C has a recess 63 on the surface 61. In this case, the irradiation light of the first hue is reflected on the left side of the recess 63, but is shaded on the right side and is not reflected. Similarly, the second irradiation light is shaded on the left side of the recess 63 and is not reflected, but is reflected on the right side. As a result, the reflected light on the right side of the recess 63 becomes the abnormal reflected light 72 having the hue of the second hue group, and the reflected light on the left side becomes the abnormal reflected light 71 having the hue of the first hue group. Since not only the normally reflected light 73 but also the abnormally reflected lights 71 and 72 are imaged by the color camera, the analyzer 40 outputs an abnormality to the main device 50.

Since the determination of hue abnormality is performed for each pixel, it may be determined that even small dust and harmless minute irregularities are abnormal just by determining whether the hue is normal or abnormal for each pixel. It is also susceptible to electrical and optical noise. In order to exclude such minute harmless ones from the anomaly, a process of calculating the continuous area of the anomalous pixels and performing anomalous output only for the ones having an area equal to or larger than a preset threshold value may be added.

FIG. 9 is a diagram schematically showing how an abnormal portion is detected when two pixels are set as the threshold value of continuous pixels. The imaged regions of the object to be inspected are shown as a1, a2, b1, and b2. The small square areas in the areas a1 and a2 represent the pixels for which an abnormality is determined in the hue determination. In the hue determination for each pixel, it is determined that all are abnormal. The result of re-determining the area a1 based on the threshold value as the continuous area is the area b1, and the result of re-determining the area a2 is the area b2. In this example, the threshold value is set to be continuous when there are two consecutive pixels. An abnormality is output in the region b1 because a continuous region remains, but an abnormality is not output in the region b2 because the hue abnormality has been resolved. By determining the threshold value of continuous pixels, it becomes possible to eliminate minute harmless objects, and it becomes possible to make a practical inspection device. The threshold value of continuous pixels is not limited to two pixels, and may be appropriately adjusted in actual operation. Further, depending on the characteristics of the object to be inspected, in addition to the number of continuous pixels, a continuous form such as continuous in a linear shape or continuous in a circular shape can be set as a criterion for determining an abnormality.

The object to be inspected has a surface extending in the Z-axis direction, and the first light source and the second light source of the surface condition inspection device are each in the XX plane, and the first light source is Z positive. In the region, the second light source may be arranged in the region where Z is negative, and the color camera may be arranged on the XY plane.

In order to determine the surface abnormality of a plate or line having a surface extending in the Z-axis direction with a surface condition inspection device, the hue of the reflected light is determined by the first hue group, the second hue group, and the like. It is necessary to be able to reliably classify into the neutral hue group. The purpose can be achieved by arranging the light sources along the Z direction and setting the position of the inspected portion in the Z direction between the light sources.

When the object to be inspected has a cylindrical surface centered on the Z axis, the first light source and the second light source of the surface condition inspection device are Z on a plane parallel to the XY plane, respectively. The color cameras are arranged so as to form a ring centered on the axis, and a plurality of the color cameras may be arranged so as to surround the cylindrical surface on the XY plane.

Further, the surface condition inspection device has a plurality of first light sources, the plurality of first light sources are concentrically arranged on the same plane, and the surface condition inspection device has a plurality of second light sources and a plurality of second light sources. The two light sources may be concentrically arranged on the same plane.

In the following, the case where the object to be inspected has a cylindrical shape will be described. The explanation will be given using a linear body having a long linear shape such as a resin pipe or a rod. It should be noted that this is applicable as long as it is a long product having a cross section including a deformed cross section other than a circular cross section, and the object to which the description is applied is not limited to a cylindrical shape.

In the case of a linear body, simply arranging the two light sources and the color camera in the Z-axis direction produces a surface that is not exposed to the irradiation light. In order to perform an all-around inspection, it is necessary to arrange the light source and the color camera in a circumferential shape to eliminate the inspectable area.

When inspecting a striatum not only over the entire circumference but also over the entire length, the striatum is passed through a light source arranged in a cylindrical shape on an XY plane and a camera arranged in a cylindrical shape, and the striatum or an inspection device is used. Is preferably moved in the Z direction. In order to perform an efficient inspection, it is desired to increase the moving speed in the Z direction, and it is necessary to increase the imaging efficiency. As an inexpensive method, it is preferable to increase the area of one captured image, and it is preferable to increase the length in the Z direction according to the moving speed. Since it is important that the irradiation light is stable over the entire inspection area, it is preferable to increase the length in the Z direction that can be irradiated by using a plurality of light sources.

Hereinafter, examples of specific embodiments will be shown with reference to FIGS. 5, 6, and 7.

FIG. 5 is a diagram showing an example of arrangement of a light source and a color camera when a linear body is an object to be inspected. With reference to FIG. 5, annular light sources 81, 82, 83, 84 are arranged so as to surround the linear body 80, which is an object to be inspected. The annular light source 81 and the annular light source 82 are used as the first light source, and both emit light of the first hue toward the surface of the linear body 80. The annular light source 81 and the annular light source 82 have different annular radii, and are arranged so that the irradiation range of light on the striatum is different. The annular light source 83 and the annular light source 84 are used as a second light source, and both emit light having a second hue toward the surface of the linear body 80. The annular light source 83 and the annular light source 84 have different annular radii, and are arranged so that the irradiation range of light on the striatum is different.

The color camera 85 includes a lens 86 and is arranged between the annular light sources 81 and 82 and the annular light sources 83 and 84 so as to capture an image of the surface to be inspected. In the above description, the extending direction of the linear body 80 is the Z direction, and the plane orthogonal to the Z direction is the XY plane. Assuming that the color camera 85 is arranged in the XY plane where Z = 0, the annular light sources 81 and 82 are arranged in the plane in which Z is parallel to the positive XY, and the annular light sources 83 and 84 are arranged. Is arranged in a plane parallel to XY where Z is negative.

FIG. 6 is a diagram showing an arrangement example of the color camera in the arrangement example of FIG. 5 on an XY plane.
With reference to FIG. 6, the annular light sources 81 (83) and 82 (84) are arranged so as to surround the linear body 80 which is the object to be inspected. Similarly, the color camera 85 is arranged with the lens 86 inside so as to surround the linear body to be inspected. By arranging the light sources 81 (83), 82 (84) and the color camera 85 in an annular shape in this way, it is possible to irradiate the entire circumference of the object to be inspected and receive all the reflected light from the entire circumference. In this example, the number of light receiving cameras 86 installed is eight, but the number of light receiving cameras 86 may be changed depending on the inspection situation, and the number of installed light receiving cameras 86 is not particularly limited.

FIG. 7 is a diagram showing the irradiation range of light from the light source in the arrangement example of FIG. 5 on the XX plane. With reference to FIG. 7, W1 shows the field of view of the color camera 86 in the Z direction. It is possible to make the irradiation range of the irradiation light 811 of the first hue larger than that of W1, but it is not possible to irradiate with the same brightness over the entire Z direction. There is a difference in brightness between the center and the edge of the irradiation range. The same thing happens with the irradiation light 831. As a result, the reflected light from the end of the irradiation range becomes the hue of the first hue group or the hue of the second hue group even though the inspected object 80 has no abnormality such as unevenness, and the analyzer becomes an analyzer. May cause a malfunction that is determined to be abnormal. In order to prevent malfunction, it is preferable to provide an inspection range W2 for making an inspection determination within the visual field range W1.

In order to perform an efficient inspection, it is preferable that the inspection range W2 is close to the field of view range W1 of the color camera. Therefore, the light source of the first hue is doubled with the annular light sources 81 and 82 to widen the range in which the brightness of the irradiation light of the first hue is stable, and similarly, the light source of the second hue is the annular light source 83. It is doubled with 84 to widen the range in which the brightness of the irradiation light of the second hue is stable. Since the stable range of the brightness of the irradiation light of the first hue and the brightness of the irradiation light of the second hue is widened, the inspection range W2 becomes large and more practical inspection can be performed.

The linear body 80 is irradiated with light by the first light source 81 and the second light source 83 arranged in a cylindrical shape, and the color camera 85 is arranged in a cylindrical shape between the light sources so that the reflected light around the entire circumference is not leaked. It may be possible to receive light. Further, in order to support high-speed movement, a cylindrical first light source 82 is arranged on the inner circumference of the first light source 81 arranged in a cylindrical shape, and a cylinder is placed on the outer periphery of the second light source 83 arranged in a cylindrical shape. By arranging the second light source 84 in the shape of a cylinder, the distance at which the irradiation light in the Z direction is stable may be widened from W2 to W1. By arranging the light sources in a double cylindrical shape, the irradiation light is stable, the area that can be imaged by the camera is large, and stable inspection can be performed even if the movement in the Z direction becomes high speed.

(Example)
An example in which the surface condition of a cable coating having a diameter of 8 mm is inspected using this inspection device will be described.

Red and blue were selected as the hue of the light source. The analyzer was used in a commercially available image processing device capable of directly analyzing the hue under the condition that the hue circle was equally divided into 255 hues, and the abnormality determination of the abnormal hue was carried out. By using a commercially available light source of red and blue, which are relatively inexpensive and two of the three primary colors of light, the reflected light was divided into 86 hues including intermediate hues, and a highly accurate judgment was made. The camera and lens are a combination of commercially available products so that the field of view is 40 mm. In addition, two sets of red and blue lights arranged on the circumference were arranged in a double ring on the same plane. As a result, an inspection range of 30 mm, which is close to the field of view of the camera, was secured.

FIG. 8 is a flow chart illustrating a typical detection logic of the inspection device of the present application. The detection of the embodiment will be described with reference to FIG. The range including the inspection range of the object to be inspected is imaged with a color camera (S01), and the captured data is input to the analyzer (S02). In the analyzer, the hue was determined for each pixel in the imaging range (S03), and the binarization process (S04) was performed by the hue group in which whether or not the hue determined for each pixel was an abnormal hue was set in advance. Next, it was determined whether or not the number of pixels having continuous abnormal hues was equal to or greater than a preset threshold value (S05), and the region determined to be equal to or greater than the threshold value was output as an abnormality (S06).

For comparison, an existing inspection device consisting of a light source and a light receiving sensor was used. The configuration of the device is shown schematically in FIGS. 10A and 10B. The existing inspection device will be described with reference to FIGS. 10A and 10B. FIG. 10A is a diagram illustrating an arrangement of the linear body 90, which is an inspection object, as seen from the side surface in the longitudinal direction. FIG. 10B is a diagram illustrating an arrangement of the existing inspection device as viewed from a direction orthogonal to the longitudinal direction of the linear body 90. The existing inspection device is composed of four white light sources 91 and four light receiving sensors 92. The four light sources 91 and the sensor 92, respectively, are arranged at equal angles around the linear body 90. In the existing inspection device, the difference in reflection caused by the difference in surface condition is regarded as a change in light intensity, and when the intensity is high, it is judged to be defective. However, in addition to unevenness, differences in reflection caused by differences in surface conditions such as surface stains and minute surface roughness can be easily captured as changes in light intensity, so it is detected as high-intensity reflections other than irregularities that should be considered defective. Easy to do.

(Detection test 1)
An inspection object with irregularities as defective parts was prepared, and the inspection results by the inspection device according to the present embodiment were compared with the inspection results by the existing inspection device. In the original inspection process, each device is used to detect only defective parts exceeding a predetermined threshold value from the measurement results, but in this comparative experiment, the detected data was recorded as an output as it is. FIG. 11 shows a graph in which the detection data is converted into the unevenness height from the comparison between the height of the uneven portion intentionally provided as a defective portion in advance and the detected data, and the detection frequency thereof is graphed. From the filled bar graph in FIG. 11, (a) shows the detection result by the apparatus of this embodiment, and (b) shows the detection result by the existing inspection apparatus. Since the frequency of detection data is very high, the frequency of unevenness provided as a defective portion cannot be seen on the graph. Therefore, in FIG. 11, among the detected data, only those corresponding to the unevenness as the intentionally provided defective portion are shown by a bar whose vertical axis is enlarged 2000 times and the hatching is changed.

From FIG. 11A, it can be seen that in the apparatus of the present embodiment, the unevenness as a defective portion and the other good portion can be detected separately. The good part is detected as corresponding to the unevenness having a height of less than 0.1 mm. Therefore, by setting the threshold value for determining a defect to a value corresponding to a height of 0.1 mm, unevenness having a height of 0.1 mm or more can be detected as a defect. That is, it can be seen that it is extremely rare to excessively detect a good portion as a defective portion. On the other hand, looking at the data of the existing inspection device in FIG. 11B, the numerical value detected by other factors becomes large even in the good part where there is no unevenness that is originally considered to be defective, so that it is about 0.4 mm. Below the height, the output due to the unevenness intentionally provided as a defective part is buried in the good part and cannot be distinguished. If the threshold value for determining defects is set to a height of about 0.4 mm, it is generally possible to discriminate more than that as a defective portion, but even so, up to a height of about 0.6 mm is excessively detected as a defective portion. I understand that. From the above, it has been confirmed that in the apparatus of the present embodiment, there is extremely little excessive detection in which an originally good portion is detected as a defective portion, and smaller unevenness can be detected as a defective portion, as compared with the conventional apparatus. Was done.

(Detection test 2)
As another detection test, FIG. 12 shows the result of preparing a defective portion intentionally provided by changing the height (maximum height difference) and the length (the length in the axial direction of the striatum) of the unevenness. In each of the apparatus of this embodiment and the existing inspection apparatus, a threshold value was set so that the good part could be distinguished, and detection was attempted. FIG. 12 shows an illustration showing whether or not the intentionally provided unevenness is detected as a defective portion. As described above, in the apparatus of the present embodiment, it was confirmed that defects can be detected even with small irregularities having a height of 0.2 mm or less.

The surface condition inspection apparatus and inspection method of the present application may be particularly advantageously applied to long products requiring surface inspection.

10 1st light source 11 1st irradiation light 20 2nd light source 21 2nd irradiation light 30 Color camera 40 Analyzer 50 Output device 60 Inspected object 61 Surface 62 Convex 63 Concave 71, 72 Abnormal reflected light 73 Normal Reflected light 101 1st hue 102 2nd hue,
103, 104 Abnormal hue 105 Normal hue 80 Linear body 81, 82, 83, 84 Circular light source 811, 821 First hue irradiation light 831, 841 Second hue irradiation light 85 Color camera 86 Lens W1 Viewing range W2 Inspection range 90 Linear body 91 Light source 92 Receiver

Claims (7)

A first light source that irradiates the inspection area on the surface of the object to be inspected with light of the first hue, and
A second light source that irradiates the inspection area with light having a second hue different from that of the first hue.
A color camera that receives the reflected light from the surface of the object to be inspected, and
It is equipped with an analyzer that analyzes the hue distribution of the reflected light from the inspection area by using the received light signal output from the color camera as an input.
The irradiation direction of the light of the first hue and the irradiation direction of the light of the second hue are different.
The analyzer
It is determined for each pixel whether the hue of the reflected light for each pixel of the color camera is included in any of the first hue group, the second hue group, and the intermediate hue group.
When the hue of the reflected light for each pixel of the color camera is included in the first hue group or the second hue group, it is determined as abnormal.
When the hue of the reflected light for each pixel of the color camera is included in the intermediate hue group, it is determined that there is no abnormality.
The first hue group is a hue group in which the first hue and a hue close to the first hue are combined.
The second hue group is a hue group in which the second hue and a hue close to the second hue are combined.
The intermediate hue group is a hue group located between the first hue group and the second hue group in the color wheel.
Surface condition inspection device. In the analyzer, when there is a region in which the pixels included in the first hue group are continuous by a preset number or more , or when the pixels included in the second hue group are continuous by a preset number or more. If there is an area that has been removed, it is determined that the inspection area has irregularities.
The surface condition inspection apparatus according to claim 1. The object to be inspected has a surface extending in one axial direction and has a surface extending in one axial direction.
When the axial direction is the Z direction and the direction orthogonal to the X direction, the X direction and the Z direction is the Y direction with the center of the inspection region as the origin and the normal direction of the surface.
The first light source and the second light source are arranged in the XZ plane, the first light source is arranged in a region where Z is positive, and the second light source is arranged in a region where Z is negative. The camera is located on the XY plane,
The surface condition inspection apparatus according to claim 1 or 2. The object to be inspected has a cylindrical surface having a central axis in the Z direction.
The first light source and the second light source are light sources that irradiate light in the axial direction of the annulus in an annular shape, and are arranged so as to be centered on the Z axis on different planes parallel to the XY plane. Has been
A plurality of the color cameras are arranged on an XY plane so as to surround the cylindrical surface.
The surface condition inspection apparatus according to claim 3. It has a plurality of the first light sources, and the plurality of the first light sources are concentrically arranged on the same plane.
It has a plurality of the second light sources, and the plurality of the second light sources are concentrically arranged on the same plane.
The surface condition inspection apparatus according to claim 4. The light of the first hue and the light of the second hue different from the first hue are irradiated with the light of the first hue and the irradiation direction of the light of the second hue different from each other. Irradiate the inspection area on the surface of the object to be inspected so that
The hue of the reflected light from the inspection area is detected for each pixel of the color camera that receives light, and is detected.
Whether the hue of the reflected light for each pixel is included in the first hue group, the second hue group, or the intermediate hue group is determined for each pixel.
When the hue of the reflected light for each pixel is included in the first hue group or the second hue group, it is determined to be abnormal.
When the hue of the reflected light for each pixel is included in the intermediate hue group, it is determined that there is no abnormality.
The first hue group is a hue group in which the first hue and a hue close to the first hue are combined.
The second hue group is a hue group in which the second hue and a hue close to the second hue are combined.
The intermediate hue group is a hue group located between the first hue group and the second hue group in the color wheel.
Surface condition inspection method. The object to be inspected has a cylindrical surface extending around the Z axis.
When the direction of the Z axis is the Z direction, and any one direction within the normal of the inspection area is the X direction, and the direction orthogonal to the X direction and the Z direction is the Y direction.
The light of the first hue and the light of the second hue are in the XZ plane from the region where Z is positive for the first light source and the region where Z is negative for the second light source, respectively. Irradiates the surface from
The reflected light is detected on the XY plane.
The surface condition inspection method according to claim 6.

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