JP2007271510A - Visual inspection method and visual inspection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a visual inspection method and device capable of identifying at high speed surface state of an inspection object part as whether being "color irregularity" or "fault spot accompanied by unevenness, such as flaws" caused by surface processing, or "both of them" or "non-defective free of either". <P>SOLUTION: By sequentially picking up regular reflection images and irregular reflection images of the inspection object part 40 by one image pickup means 20 and determining presence of the fault spot in each image, it is possible to determine whether the inspection object part be "non-defective", "color irregularity", "fault spot accompanied by unevenness, such as flaws" or "color irregularity and fault spot, such as flaws". <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an appearance inspection method and an appearance inspection apparatus for performing an appearance inspection of a part to be inspected such as a link plate or a connecting pin at a site of a manufacturing factory such as a chain. The present invention relates to an appearance inspection method and an appearance inspection apparatus for irradiating an inspection part with light and inspecting the surface state of the part to be inspected by a reflection image thereof.

  In a method for inspecting the appearance of a component to be inspected using image processing, a method using regular reflection light observation is known as a general inspection method. This is because, when a camera and a lighting device are installed so that the light regularly reflected on the normal surface of the part to be inspected can be imaged by the camera, the surface is irregularly reflected due to irregularities on the surface where there are defective parts such as scratches. For this reason, in the captured image, there is a contrast between the normal surface and the defective portion. That is, in a defective part such as a scratch, the brightness is low (darker) compared to a normal surface. As a result, defective portions such as scratches were detected, and an appearance inspection was performed based on a predetermined criterion (hereinafter referred to as “Cited Invention 1”).

  In addition, an appearance inspection is also known in which a line sensor is used to perform specular reflection light observation and irregular reflection light observation, and an optical method is used to inspect defective portions such as color unevenness and scratches from the obtained two images ( Hereinafter referred to as “Cited Invention 2”). (For example, refer to Patent Document 1).

JP 2002-71576 A

  However, in the appearance inspection method according to Cited Invention 1, when the part to be inspected is a metal such as steel and has been subjected to a surface treatment such as heat treatment or nitrocarburizing treatment, In addition, color unevenness (dark pattern) may occur on the surface of the part to be inspected depending on the processing condition of the surface treatment. When selecting the inspected part with uneven color and the inspected part having a defective portion with irregularities such as scratches, in the above-mentioned specular reflection observation, the part to be inspected is the same as a human being sees. Since the image is displayed, if there is uneven color on the surface of the part to be inspected, the captured image will have low brightness (darkness) even in the part with uneven color, and the defective part with unevenness such as scratches and the defective part due to uneven color Cannot be distinguished.

  Further, in the case where the color unevenness is clearly different from the defective portion having unevenness such as scratches, a method of distinguishing the defective portion having unevenness such as color unevenness and scratches by performing color image processing can be considered. However, in order to perform color image processing, a device such as a camera as an imaging unit becomes very expensive, and the amount of information processing increases, so that practical application is difficult. Furthermore, when the color unevenness is a color similar to a defective portion having irregularities such as scratches, it is difficult to identify even if color image processing is performed.

  On the other hand, in the appearance inspection method according to Cited Invention 2, since the inspection is performed by scanning the surface to be inspected in a line shape by using a line sensor to obtain the reflected light, the time required for the inspection is long. In addition, since the regular reflection image and the irregular reflection image are not compared, it is impossible to distinguish the color unevenness and the defective portion having irregularities such as scratches.

  Therefore, the object of the present invention is “uneven color” generated as a result of the surface treatment of the surface state of the part to be inspected, “defect spot with irregularities such as scratches”, or “both” It is an object of the present invention to provide an appearance inspection method and an appearance inspection apparatus capable of identifying at high speed whether the product is “non-defective product”.

  An appearance inspection method according to claim 1 irradiates light to a part to be inspected, and in the appearance inspection method for inspecting a surface state of the part to be inspected by a reflection image thereof, irradiates light to a normal part of the part to be inspected. When the specularly reflected light illumination means and the imaging means are installed so that the specularly reflected light is incident on the imaging means, the irregularly reflected light is incident on the imaging means when the defective part of the part to be inspected is irradiated with light. In the specular reflection image acquired by the imaging unit with the specular reflection light, the brightness is less than a predetermined specular reflection threshold SN (darker than the ground brightness). The spot that is reflected) is a specular reflection failure spot, and the spot whose brightness is equal to or greater than a given diffuse reflection threshold SR in the diffuse reflection image acquired by the imaging means by the diffusely reflected light (becomes bright against the darkness of the ground) Where there is irregular reflection If the regular reflection image does not include the regular reflection defect portion, the part to be inspected is determined as “good”, and the regular reflection image includes the regular reflection defect portion, and When the irregular reflection image does not include the irregular reflection defective portion, the part to be inspected is determined to be “color irregularity product”, and the regular reflection defective portion and the irregular reflection defective portion are included in the regular reflection image and the irregular reflection image, respectively. If the position is different in some cases, the part to be inspected is determined to be “color irregularity product and defective part such as a scratch”, and each of the regular reflection image and the irregular reflection image includes the regular reflection image. In the case where there is a defective reflection portion and the irregular reflection defective portion, and the position is the same position, the part to be inspected solves the above problem by determining that there is a defective portion such as a scratch. . In this method, as is apparent from the above description, one imaging means (camera) and two illumination means (for regular reflection light and irregular reflection light) are used.

  The appearance inspection apparatus according to claim 2 irradiates light to a part to be inspected, and in the appearance inspection apparatus that inspects the surface state of the part to be inspected by a reflection image thereof, irradiates light to a normal part of the part to be inspected. When the specularly reflected light is incident on the “imaging means”, the “illuminating means for specular reflection light” and the imaging means are installed, and the irregularly reflected light is captured when the defective part of the part to be inspected is irradiated with light. “Irradiating means for irregularly reflected light” is installed so as to be incident on the means, and in the specular reflection image acquired by the imaging means by the specular reflection light, a portion having a lightness equal to or less than a predetermined specular reflection threshold SN is defective in specular reflection And a “defect location determination unit” that makes a location where the brightness is a given irregular reflection threshold SR or more in the irregular reflection image acquired by the imaging unit by the irregular reflection light, and the irregular reflection defect location, Inside the regular reflection failure If there is no place, the part to be inspected is determined as “non-defective”, and when there is the specular reflection defective portion in the regular reflection image, and when the irregular reflection defective portion is not present in the irregular reflection image, If the part to be inspected is determined to be “color uneven product” and the position of the specular reflection image and the irregular reflection image are different from each other when the specular reflection defect location and the irregular reflection defect location are present, Is determined to be "color irregularity product and there are defective spots such as scratches", and in the regular reflection image and the irregular reflection image, there are the regular reflection defective spot and the irregular reflection defective spot, respectively. When the positions are the same, the part to be inspected has “defect cause identifying means” for determining that “there is a defective portion such as a scratch”, thereby solving the above-described problem.

  An appearance inspection method according to claim 3 is an appearance inspection method for irradiating light to a part to be inspected and inspecting a surface state of the part to be inspected by a reflection image thereof. Illumination means, imaging means for specular reflection light installed at a position where regular reflection light is incident when the illumination means is turned on, and a position where irregular reflection light is incident (position where the regular reflection light is not incident) An irregularly reflected light imaging means installed, and the irregular reflection image obtained by the irregularly reflected light imaging means and the regular reflection image obtained by the regular reflected light imaging means, using a given correction coefficient; Then, the size of one of the irregular reflection image and the regular reflection image is corrected to the size of the other image. As a result, the brightness of the regular reflection image with respect to the obtained regular reflection image and irregular reflection image is corrected. Is located below the given specular reflection threshold SN (brightness of the ground On the other hand, a spot that appears dark is defined as a specular reflection failure spot, and a spot whose brightness is greater than or equal to a given diffuse reflection threshold SR in the diffuse reflection image (a spot that appears bright relative to the darkness of the ground) If the regular reflection image does not include the regular reflection defect location, the part to be inspected is determined to be “non-defective”, and the regular reflection image includes the regular reflection failure location. When the irregular reflection image does not include the irregular reflection defective portion, the part to be inspected is determined to be “color irregularity product”, and the regular reflection defective portion and the irregular reflection image respectively in the regular reflection image and the irregular reflection image. If there is a irregular reflection defective part and the position is different, the part to be inspected is determined to be “color irregularity product and defective part such as a scratch”, and among the regular reflection image and the irregular reflection image Each of the specular reflection defects and the If the location if there is reflection defective portion is the same position, the inspection part, by determining that "there is a defective portion such as a scratch", is intended to solve the foregoing problems. In this method, as is apparent from the above description, two imaging means (for regular reflection light and irregular reflection light) and one illumination means are used.

  According to a fourth aspect of the present invention, in the appearance inspection apparatus that irradiates light to the part to be inspected and inspects the surface state of the part to be inspected by a reflection image thereof, one unit that irradiates the part to be inspected with light. “Illuminating means”, “imaging means for specularly reflected light” installed at a position where specularly reflected light is incident when the illuminating means is turned on, and “diffusely reflected light” installed at a position where irregularly reflected light is incident The regular reflection image obtained by the regular reflection light imaging means and the irregular reflection image obtained by the irregular reflection light imaging means using a given correction coefficient. An “image size correcting unit” that corrects the size of one of the image and the irregular reflection image to the size of the other image. As a result, the regular reflection image is obtained with respect to the obtained regular reflection image and irregular reflection image. Locations where the brightness is less than the given specular reflection threshold SN A part having a regular reflection failure, and having a part having a lightness of a given diffuse reflection threshold SR or more in the irregular reflection image as a irregular reflection defective part, has a “defective part determination unit”, and the regular reflection defect is included in the regular reflection image. If there is no location, the part to be inspected is determined as “non-defective”, and if there is the regular reflection failure location in the regular reflection image, and if there is no irregular reflection failure location in the irregular reflection image, If the part to be inspected is determined to be “color uneven product” and the position of the specular reflection image and the irregular reflection image are different from each other when the specular reflection defect location and the irregular reflection defect location are present, Is determined to be "color irregularity product and there are defective spots such as scratches", and in the regular reflection image and the irregular reflection image, there are the regular reflection defective spot and the irregular reflection defective spot, respectively. The same position If the inspection part, by having a determining that "there is a defective portion such as a scratch," "failure cause determining means" is intended to solve the foregoing problems.

  According to the appearance inspection method according to claim 1 and the appearance inspection apparatus according to claim 2, the regular reflection image and the irregular reflection image of the part to be inspected are sequentially picked up by one image pickup means, and the presence or absence of a defective portion in each image is detected. Whether the part to be inspected is a “non-defective product”, a “color uneven product”, “a defective part such as a scratch”, “a color uneven product, and a scratch, etc. It is possible to determine whether or not there is a defective portion.

  According to the appearance inspection method according to claim 3 and the appearance inspection apparatus according to claim 4, the specular reflection image and the irregular reflection image of the part to be inspected are simultaneously picked up by two image pickup means, and the presence or absence of a defective portion in each image is detected. Whether the part to be inspected is a “non-defective product”, a “color uneven product”, “a defective part such as a scratch”, “a color uneven product, and a scratch, etc. It is possible to determine at high speed whether there is a defective portion.

  Hereinafter, an appearance inspection method and an appearance inspection apparatus according to the present invention will be described in detail with reference to the drawings. The first embodiment corresponds to the inventions according to claims 1 and 2, and the second embodiment corresponds to the inventions according to claims 3 and 4. The appearance inspection apparatus according to claim 2 embodies the appearance inspection method according to claim 1, and the appearance inspection apparatus according to claim 4 embodies the appearance inspection method according to claim 3. Therefore, the following description will focus on the visual inspection method.

  FIG. 1 shows an apparatus configuration when performing the appearance inspection method of the first embodiment. The apparatus denoted by reference numeral 10 is an illumination means for specular reflection light arranged so that specular reflection light is incident on the image pickup means 20 when light is irradiated on a normal part of the component 40 to be inspected. Here, for example, a commercially available industrial black-and-white video camera is preferably used as the imaging unit 20. Of the irradiation light emitted from the illumination device 10 for specular reflection light, only the light that is regularly reflected on the surface of the component 40 to be inspected is incident on the image pickup device 20, so that the image obtained from the image pickup device 20 has a color on the component under inspection. If there are no defects such as unevenness or scratches, the whole image appears bright. On the other hand, when there is a defective portion 42 such as a scratch on the component to be inspected 40, the irradiation light irradiated from the specular reflection light illumination means 10 is diffusely reflected without being regularly reflected at the defective portion, and does not enter the imaging means 20. , That part looks dark. Also, when there is color unevenness 44, the reflectance at that portion decreases, so that portion appears dark. As a result, the specular reflection image obtained is an image as shown in FIG.

  Further, since the irregularly reflected light illuminating means 30 is installed at a position where the specularly reflected light does not enter the imaging means 20, when the part under test 40 is a non-defective product, the whole appears dark. On the other hand, when there is a defective portion 42 such as a scratch on the component to be inspected 40, irregular reflection occurs at that portion and part of the irregularly reflected light is incident on the imaging means 20. Therefore, the irregular reflection image obtained by the imaging means 20 is shown in FIG. As shown in 2 (b), the defective portion 42 appears bright. In addition, the reflection angle does not change at a place where the color unevenness 44 exists, and thus does not appear in the irregular reflection image.

  Hereinafter, the appearance inspection method according to the first embodiment will be described in detail based on the flowchart shown in FIG. In the following description, S1, S2,... Shown in parentheses mean the steps shown in the flowchart of FIG. The imaging means is simply described as “camera” in the flowchart.

  When the component to be inspected is supplied (S1), the power of the regular reflection light illumination means is turned on, and the power of the irregular reflection light illumination means is turned off (S2). Then, a regular reflection image is acquired by the imaging means (S3). Next, the power source of the regular reflection light illumination unit is turned off, and the power source of the irregular reflection light illumination unit is turned on (S4). Then, an irregular reflection image is acquired by the imaging means (S5).

  Next, it is determined whether or not there is a portion that is equal to or less than the regular reflection threshold SN in the regular reflection image (S6) or whether there is a portion that is equal to or greater than the irregular reflection threshold SR in the irregular reflection image (S8). Here, the method of determining the regular reflection threshold SN and the irregular reflection threshold SR is, for example, when the brightness gradation is 256 gradations, 64 gradations (one-fourth from the bottom) is SN, and 192 gradations (upper) Can be set to SR. However, since the determination of SN and SR greatly affects the final determination result, the shape of the specular reflection image captured as a dark portion and the shape of an irregular reflection image captured as a bright portion after capturing the same defective portion in advance are determined. It is preferable to adjust by trial and error so as to be as equal as possible.

  In addition, by using a reference part, the dynamic range is determined by determining 256 gradations when the brightness is the highest (maximum density value) and 1 gradation when the brightness is the lowest (minimum density value). Can be increased, and the discrimination accuracy can be improved.

  In S6, when there is no portion equal to or less than the regular reflection threshold SN, the part to be inspected is determined as “good” and discharged (S7). In addition, when there is a portion that is equal to or less than the regular reflection threshold SN and there is no portion that is equal to or greater than the irregular reflection threshold SR, the part to be inspected is determined to be “color uneven product” and discharged (S9).

  Furthermore, when there are locations that are less than or equal to the regular reflection threshold SN in the regular reflection image (S6) and there are locations that are greater than or equal to the irregular reflection threshold SR in the irregular reflection image (S8), it is determined that both images are defective. It is determined whether the location is the same position (S10). As a result, if it is not only at the same position, the part to be inspected is judged to be “color uneven product and defective part such as a scratch” and discharged (S11). On the other hand, if only the same position is determined to be defective in both images, it is determined that “there is only a defective portion such as a flaw” and the component to be inspected is ejected (S12). By repeating the above flow, the quality of the part to be inspected is objectively determined regardless of the manual operation.

  Next, an appearance inspection method in which the inspection speed is increased by using two imaging means for regular reflection light and irregular reflection light with one illumination means will be described.

  FIG. 4 shows an apparatus configuration when performing the appearance inspection method of the second embodiment. The device denoted by reference numeral 110 is an illumination device that irradiates the component to be inspected 140. Then, the specularly reflected light imaging means 120 (hereinafter referred to as “camera 1”) is arranged at a position where the specularly reflected light that is specularly reflected by the surface of the component to be inspected 140, and a position where the irregularly reflected irregularly reflected light is incident (that is, the camera 1). The irregularly reflected light imaging means 130 (hereinafter referred to as “camera 2”) is disposed at a position where the regular reflected light is not incident.

  As shown in FIG. 4, when one part to be inspected is imaged using two cameras, that is, the camera 1 and the camera 2, the angle between the part to be inspected and the two cameras is different for each camera. When the regular reflection image and the irregular reflection image are compared, as shown by X in FIG. 5, the irregular reflection image captured by the camera 2 having a larger angle formed by the part to be inspected and the line of sight of the camera is captured by the camera 1. The image is taken slightly longer than the reflected image.

  However, as shown in FIG. 6, the angles formed between the parts to be inspected and the camera's line of sight are the angles θ1 and θ2, respectively, and the two cameras have the same vertical from the center of the parts to be inspected. It is installed at a distance r (radius) on the circumference of the surface. If the size of the article to be inspected (the length in the horizontal direction on the paper surface) is d, it is possible to correct one image to the size of the other image using these known values θ1, θ2, r, and d. Is possible. A method for deriving the correction coefficients m1, n1, m2, and n2 at that time will be described with reference to FIGS.

  The specular reflection image and the irregular reflection image captured by the camera 1 and the camera 2, respectively, are distorted images because the camera 1 and the camera 2 are angled with respect to the component to be inspected. That is, as shown in FIG. 7 for the specularly reflected light camera 1 and FIG. 8 for the irregularly reflected light camera 2, the caption “Image captured by the camera” in the figure is actually attached. The image you see through the camera. That is, in the case of the two cameras in terms of the paper surface from the center of the lens, the distortion differs between the right side and the left side with respect to the line connecting the camera and the center of the part to be inspected. In FIG. 7, m1 and n1, and in FIG. 8, both m2 and n2 correspond to d / 2 of the component to be inspected.

In FIG. 7, in order to obtain m1 and n1 from known values θ1, r, and d, they can be derived based on a calculation formula including the following trigonometric functions.
h1 = r · sin θ1 (1)
s1 = r · cos θ1−d / 2 (2)
φ1 = tan ⁻¹ (h1 / s1) (3)
δ1 = tan ⁻¹ (h1 / (d + s1)) (4)
α1 = π / 2 + θ1-φ1 (5)
γ1 = φ1−δ1 (6)
β1 = π−α1−γ1 = θ1 + φ1−γ1 (7)
W1 = (d / 2) · cos θ1 (8)
t1 = r−w1 (9)
m1 = (d / 2) · sin θ1 (10)
n1 = t1 / tanβ1 (11)

Similarly, in FIG. 8, in order to obtain m2 and n2 from known values θ2, r, and d, they can be derived on the basis of a calculation formula including the following trigonometric functions.
h2 = r · sin θ2 (12)
s2 = r · cos θ2−d / 2 (13)
φ2 = tan ⁻¹ (h2 / s2) (14)
δ2 = tan ⁻¹ (h2 / (d + s2)) (15)
α2 = π / 2 + θ2−φ2 (16)
γ2 = φ2−δ2 (17)
β2 = π−α2−γ2 = θ2 + φ2−γ2 (18)
W2 = (d / 2) · cos θ2 (19)
t2 = r−w2 (20)
n2 = t2 / tanβ2 (21)
m2 = (d / 2) · sin θ2 (22)

In order to convert the captured image captured by the camera 1 into a size equivalent to the captured image of the camera 2 using m1, m2, n1, and n2 obtained in this way, the right side captured by the camera 1 is used. XR any point, left any point of the XL, if the point of the corrected left and right XR, and XL,
XR = (m2 / m1) · XR
XL = (n2 / n1) · XL
Can be expressed as As shown in FIG. 9B, when the position of a specular reflection image having a defective portion such as color unevenness or a flaw detected by the camera 1 is converted by the above correction equation as shown in FIG. 9A. The size is equivalent to the irregular reflection image captured by the camera 2 shown in FIG.

  The steps of determining the correction coefficients m1, n1, m2, and n2 as described above and performing the corrected regular reflection image and the irregular reflection image based on the correction coefficients are from S1 of the flowchart shown in FIG. This corresponds to S5. After that, according to S6 to S12 of the flowchart, “non-defective product”, “color uneven product”, “color uneven product and defective part due to scratches”, “only defective part such as scratches” There are four types. In addition, since the process of S6 to s12 is the same as what was demonstrated in Example 1, it abbreviate | omits about detailed description. In this example, the image of the camera 1 is corrected and matched with the image of the camera 2. However, the image of the camera 2 may be corrected and matched with the image of the camera 1.

  Furthermore, it is not necessary to actually represent the corrected data as an image. For example, at the stage where the defective portion is identified, information specific to the defective portion, for example, the position of the center of gravity of the defective portion is corrected for distance, and the uncorrected camera A method of determining a defective portion with an image may be taken.

  In the above-described embodiment, a metal such as steel is exemplified as the part to be inspected. However, it can be applied to a part made of glass or plastic as long as it reflects light.

  According to the appearance inspection method of the present invention, by capturing regular reflection and irregular reflection on the surface of the article to be inspected without particularly requiring an expensive camera, illumination device, deflection filter, or the like, It is possible to identify "color uneven products", "defective products with irregularities such as scratches", etc., and as a result, it is possible to quickly reprocess the found defective products, and its industrial applicability Is extremely expensive.

It is drawing which showed the apparatus structure of the external appearance inspection method in Example 1 of this invention. It is the image imaged with the imaging means in Example 1 of this invention, Comprising: (a) is a regular reflection image, (b) is an irregular reflection image. It is a flowchart of the external appearance inspection method in Example 1 of this invention. It is drawing which showed the apparatus structure of the external appearance inspection method in Example 2 of this invention. In Example 2 of this invention, it is the image imaged with the imaging means, Comprising: The left is a regular reflection image and the right is an irregular reflection image. It is the figure which showed the positional relationship of the camera and to-be-inspected part in Example 2 of this invention. It is drawing which calculates | requires the conversion formula of the regular reflection image in Example 2 of this invention. It is drawing which calculates | requires the conversion type | formula of the irregular reflection image in Example 2 of this invention. It is a figure explaining the process in which the size of the regular reflection image in Example 2 of this invention is converted into the size of an irregular reflection image, (a) is a regular reflection image before conversion, (b) is regular reflection after conversion. (C) is an irregular reflection image. It is a flowchart of the external appearance inspection method in Example 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Illumination means 20 for specular reflection light ... Imaging means 30 ... Illumination means 40 for irregular reflection light ... Parts 42 to be inspected ... Defect 44 such as a flaw ... Color unevenness 110 ... Illuminating means 120: specularly reflected light imaging means 130 ... diffusely reflected light imaging means 140 ... inspected part 142 ... defective part 144 such as scratches ... color unevenness

Claims (4)

In the appearance inspection method of irradiating the part to be inspected with light and inspecting the surface state of the part to be inspected by its reflection image,
The specular reflection light illumination unit and the imaging unit are installed so that the specular reflection light is incident on the imaging unit when light is emitted to the normal part of the component to be inspected.
When irradiating light to a defective part of the part to be inspected, an illuminating means for irregularly reflected light is installed so that irregularly reflected light enters the imaging means,
In the regular reflection image acquired by the imaging means by the regular reflection light, a spot whose brightness is a given regular reflection threshold SN or less is a regular reflection failure spot,
In the irregular reflection image acquired by the imaging means by the irregular reflection light, a location where the brightness is a given irregular reflection threshold SR or more is an irregular reflection defective location,
If the specular reflection image does not have the specular reflection defect, the part to be inspected is determined to be “good”,
If the regular reflection image includes the irregular reflection defective portion and the irregular reflection image does not include the irregular reflection defective portion, the part to be inspected is determined to be a “color uneven product”;
When the specular reflection image and the irregular reflection image have the specular reflection defect portion and the irregular reflection defect portion, respectively, and the positions thereof are different, the inspected part is “color irregularity product and scratches etc. It is judged that there is a defective part of
In the case where there are the regular reflection defect location and the irregular reflection defect location in the regular reflection image and the irregular reflection image, respectively, and when the position is the same position, the part to be inspected is "there is a defect location such as a scratch" An appearance inspection method characterized by judging. In the appearance inspection apparatus that irradiates the part to be inspected with light and inspects the surface state of the part to be inspected by its reflection image,
The “illuminating means for specular reflection light” and the imaging means are installed so that the specularly reflected light is incident on the “imaging means” when the normal part of the part to be inspected is irradiated with light,
"Irradiating means for irregularly reflected light" is installed so that irregularly reflected light is incident on the imaging means when irradiating light on a defective part of the part to be inspected,
Of the specular reflection image acquired by the imaging means by the specular reflection light, a part having a lightness equal to or less than a given specular reflection threshold SN in the specular reflection image acquired by the imaging means is used as a specular reflection defective part. And having a “defective part discriminating means” in which a part having a lightness equal to or greater than a given irregular reflection threshold SR is used as an irregular reflection defective part,
If the regular reflection image does not include the regular reflection defect portion, the part to be inspected is determined as “non-defective”, the regular reflection image includes the regular reflection defect portion, and the irregular reflection image. When the irregular reflection defective portion is not present in the case, the part to be inspected is determined to be “color uneven product”, and the regular reflection defective portion and the irregular reflection defective portion are present in the regular reflection image and the irregular reflection image, respectively. If the position is different, the part to be inspected is determined to be “color irregularity product and defective part such as a scratch”, and the regular reflection defect is included in each of the regular reflection image and the irregular reflection image. If the location and the irregular reflection defective location are the same position, the part to be inspected has “defect cause identifying means” for determining that “there is a defective location such as a scratch” Inspection device. In the appearance inspection method of irradiating the part to be inspected with light and inspecting the surface state of the part to be inspected by its reflection image,
One illumination unit that irradiates light to the component to be inspected, an imaging unit for regular reflection light that is installed at a position where regular reflection light is incident when the illumination unit is turned on, and irregular reflection light is incident Having an imaging means for diffusely reflected light installed at a position;
The specular reflection image obtained by the specular reflection light imaging means and the irregular reflection image obtained by the irregular reflection light imaging means, using a given correction coefficient, one of the specular reflection image and the irregular reflection image. The size of the image is corrected to the size of the other image, and as a result, the obtained regular reflection image and irregular reflection image are
In the regular reflection image, a spot whose brightness is not more than a given regular reflection threshold SN is a regular reflection failure spot,
In the irregular reflection image, a portion having a lightness equal to or higher than a given irregular reflection threshold SR is defined as an irregular reflection defective portion,
If the specular reflection image does not have the specular reflection defect, the part to be inspected is determined to be “good”,
If the regular reflection image includes the irregular reflection defective portion and the irregular reflection image does not include the irregular reflection defective portion, the part to be inspected is determined to be a “color uneven product”;
When the specular reflection image and the irregular reflection image have the specular reflection defect portion and the irregular reflection defect portion, respectively, and the positions thereof are different, the inspected part is “color irregularity product and scratches etc. It is judged that there is a defective part of
In the case where there are the regular reflection defect location and the irregular reflection defect location in the regular reflection image and the irregular reflection image, respectively, and when the position is the same position, the part to be inspected is "there is a defect location such as a scratch" An appearance inspection method characterized by judging. In the appearance inspection apparatus that irradiates the part to be inspected with light and inspects the surface state of the part to be inspected by its reflection image,
One “illuminating means” for irradiating light to the component to be inspected, “imaging means for specularly reflected light” installed at a position where regular reflected light is incident when the illuminating means is turned on, and irregular reflection “Imaging means for diffusely reflected light” installed at a position where light enters,
The specular reflection image obtained by the specular reflection light imaging means and the irregular reflection image obtained by the irregular reflection light imaging means, using a given correction coefficient, one of the specular reflection image and the irregular reflection image. “Image size correction means” for correcting the size of the image to the size of the other image,
As a result, with respect to the obtained regular reflection image and irregular reflection image, the regular reflection image has a portion whose lightness is not more than a given regular reflection threshold SN as a regular reflection failure portion, and the lightness in the irregular reflection image is Having a “defect location determination means” that makes a location where the irregular reflection threshold SR or more is an irregular reflection defect location;
If the regular reflection image does not include the regular reflection defect portion, the part to be inspected is determined as “non-defective”, the regular reflection image includes the regular reflection defect portion, and the irregular reflection image. When the irregular reflection defective portion is not present in the case, the part to be inspected is determined to be “color uneven product”, and the regular reflection defective portion and the irregular reflection defective portion are present in the regular reflection image and the irregular reflection image, respectively. If the position is different, the part to be inspected is determined to be “color irregularity product and defective part such as a scratch”, and the regular reflection defect is included in each of the regular reflection image and the irregular reflection image. If there is a spot and the irregular reflection defective part, and the position is the same position, the part to be inspected has “defect cause determining means” for determining that “there is a defective part such as a scratch” Inspection device.

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