Article inspection device and article inspection method

Abstract

To provide an article inspection device in which detection accuracy of defects in a transparent portion of an article improves, and to provide an article inspection method.SOLUTION: An article inspection device 10 includes an illumination part 20, a camera 30, a shielding member 40, an image controlling part 51 and an inspection processing part 60. The camera 30 is arranged on the position opposite the illumination part 20 with respect to an article 12. The shielding member 40 arranged between the illumination part 20 and the article 12 has a constitution in which a shielding part and a light transmission part are arrayed in a two dimensional shape in which they are alternately arranged in the first direction and the second direction crossing with each other. The image controlling part 51 allows the camera 30 to capture an image of transmission light that has transmitted a transparent portion of the article 12. The inspection processing part 60 performs at least one inspection out of a first inspection for inspecting presence / absence of a defect which is higher in luminance than a dark part in the dark part which is an image region of the shielding part and a second inspection for inspecting presence / absence of a defect which is lower in luminance than a bright part in the bright part which is an image region of the light transmission part, based on a plurality of types of inspection images IS1, IS2 acquired from the camera 30.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to an article inspection apparatus and an article inspection method for inspecting an article having a transparent portion through which light can pass. [Background technology]

[0002] For example, Patent Document 1 discloses an imaging device equipped with a camera that receives light transmitted from a light source through a transparent container to capture a transmission image of the transparent container. The image captured by this imaging device is used to detect foreign objects in the liquid filled in the transparent container.

[0003] Furthermore, Patent Documents 2 and 3 disclose an object inspection device in which a light-shielding member having multiple slits arranged in one direction to form a light-dark pattern is placed between an illumination unit and the object, and a camera captures an image of the transmitted light that passes through the object through the light-dark pattern.

[0004] The article inspection device described in Patent Document 2 is equipped with a pattern irradiation means on the back side of a translucent workpiece, which is composed of a light-dark pattern forming shade (an example of a light-shielding member) in which light-transmitting and light-shielding parts are continuous in one direction, and an illumination light source. The light-dark pattern irradiated by the irradiation means is photographed through the workpiece by an imaging means (camera) facing the irradiation means with the workpiece in between. Surface defects (an example of a defect) of the workpiece are detected based on changes (bright spots) in the amount of emitted light (brightness) in the photographed image. The light diffusing means guides the light that has passed through the translucent part to the light-shielding part side as diffused light, and the amount of emitted light in the dark part of the workpiece increases, promoting the emergence of defects in the dark part as bright spots.

[0005] The article inspection device described in Patent Document 3 includes an illumination unit that illuminates with transmitted light, an imaging unit (camera) that receives the transmitted light and images a product (an example of an article), and a slit plate (an example of a light-shielding member) that forms light and dark stripes on the product, with light and dark areas being repeated alternately. The slit plate is configured with alternating light-transmitting and light-shielding sections. The article detection device converts the captured image into a multi-tone grayscale image, detects the boundaries of each particle of the transparent fine particle material that appears in intermediate tones within the inspection area as changing points of light and dark, and judges the coating state of the transparent fine particle material based on the number of changing points. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2002-267613 A [Patent Document 2] JP 2020-91132 A [Patent Document 3] JP 2010-204051 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the object inspection devices described in Patent Documents 2 and 3, a light-dark pattern forming shade or slit plate is used to form a light-dark pattern in which dark and bright areas are arranged in one direction, so there is a bias in the direction of light from the light-transmitting area or slit to the light-shielding area (dark area). Therefore, even if a defect appears bright in a dark area, the difference in brightness from the dark area may be small. For example, in the case of defects such as scratches, the direction in which the scratches are formed and the angle and shape of the surface on which the scratches are formed have characteristics that make it easy for light to refract in a specific direction, so even if light is received from a biased direction, the direction in which the light is refracted by the scratches may not be the direction of the camera. In this case, the brightness of the defect is unlikely to be high. In order to detect this type of defect, it is necessary to reduce the brightness threshold value used to determine the defect, but doing so makes it easy to erroneously detect the defect. Therefore, there is a problem in that it is necessary to take in more light from a direction parallel to the longitudinal direction of the light-transmitting area or slit into the part of the defect located in the dark area, thereby reducing the bias in the direction of the light incident on the defect. Although there are defects that result in low luminance (darkness), the object inspection devices described in Patent Documents 2 and 3 do not target these types of defects. [Means for solving the problem]

[0008] The means for solving the above problems and their effects will be described below. The object inspection device that solves the above problem is an object inspection device that inspects an object by imaging the object having at least a part of a transparent portion through which light can pass, and includes an illumination unit that illuminates the object arranged at an imaging position, a camera arranged at a position opposite the illumination unit with respect to the object, a light-shielding member that is arranged between the illumination unit and the object and has light-shielding portions and light-transmitting portions arranged two-dimensionally by alternating in a first direction and a second direction that intersect with each other, an imaging control unit that acquires multiple types of inspection images by having the camera capture an image of transmitted light that has passed through the transparent portion of the object, and an inspection processing unit that inspects the object for defects based on the multiple types of inspection images, and the inspection processing unit performs at least one of a first inspection that inspects the dark portions that are an image area of ​​the light-shielding portion for defects that are brighter than the dark portions, and a second inspection that inspects the bright portions that are an image area of ​​the light-transmitting portion for defects that are brighter than the bright portions, based on the multiple types of inspection images.

[0009] According to this configuration, the part of the article with the light-shielding part as the background does not receive incident light from behind, but the brightness of the defect located in the part with the light-shielding part as the background is likely to be higher than that of the light-shielding part background image (dark part) due to the refraction of light incident obliquely from the transparent part adjacent to the periphery of the light-shielding part. Since the light-shielding part and the light-transmitting part are arranged two-dimensionally, the part of the article with the light-shielding part (dark part) as the background is incident with light obliquely from three or more light-transmitting parts (bright parts) adjacent to the light-shielding part. Therefore, the brightness of the defect located in the part with the dark part as the background is likely to be higher on average than that of a conventional article inspection device using a one-dimensional light-shielding member in which the light-shielding part and the light-transmitting part are arranged in only one direction. Similarly, in the part of the article with the light-transmitting part as the background, the light-shielding part adjacent to the periphery of the light-transmitting part is reflected due to the refraction of light at the defect located in the part with the transparent part as the background, and the brightness of the defect is likely to be lower than that of the light-transmitting part background image (bright part). Since the light-shielding portions and light-transmitting portions are arranged two-dimensionally, dark light is obliquely incident on a portion of the article against a light-transmitting portion (bright portion) from three or more light-shielding portions adjacent to that light-transmitting portion. Therefore, compared to a conventional article inspection device that uses a one-dimensional light-shielding member in which the light-shielding portions and light-transmitting portions are aligned in only one direction, the brightness of defects located against a bright portion is likely to be lower on average. Therefore, when at least one of the first inspection and the second inspection is performed, the inspection accuracy for defects is improved compared to a conventional article inspection device.

[0010] In the above-mentioned item inspection device, the lighting unit illuminates the item with monochromatic blue light, the camera is an RGB color camera that captures an image of transmitted light that has passed through the transparent portion of the item to obtain a color image, the multiple types of inspection images include a first inspection image used in the first inspection and a second inspection image used in the second inspection, and the imaging control unit may color-separate the color image to obtain a B image or a G image as the first inspection image, and obtain one of the G image and R image that is different from the first inspection image as the second inspection image.

[0011] In the above-mentioned item inspection device, the inspection processing unit may detect high brightness parts in the dark areas that are equal to or greater than a first threshold value as the defects based on the first inspection image, and detect low brightness parts in the bright areas that are less than a second threshold value as the defects based on the second inspection image.

[0012] In the above-mentioned item inspection device, the imaging control unit may acquire multiple types of inspection images by performing multiple imaging under imaging conditions in which the phases of the dark and bright areas of the item are different, and the inspection processing unit may inspect the presence or absence of defects based on each of the dark areas or each of the bright areas of the multiple types of inspection images.

[0013] The above-mentioned product inspection device may further include an image processing unit that combines the dark areas of the multiple types of inspection images into one to generate a dark area composite image, or that combines the bright areas of the multiple types of inspection images into one to generate a bright area composite image, and the inspection processing unit may inspect the presence or absence of the defects based on the dark area composite image or the bright area composite image.

[0014] In the above-mentioned item inspection device, a relative movement mechanism is provided that moves the item and the light-shielding member relatively in a direction that changes the phase of the dark and bright areas relative to the item, and the imaging control unit may cause the camera to image the item two or more times at timings where the phase is different.

[0015] An article inspection method that solves the above-mentioned problems is an article inspection method for imaging and inspecting an article having at least a portion thereof transparent part through which light can pass, the method comprising: an illumination unit that illuminates the article arranged at an imaging position; a camera arranged at a position opposite the illumination unit with respect to the article; and a light-shielding member that is arranged between the illumination unit and the article and has light-shielding parts and light-transmitting parts arranged two-dimensionally by alternating in a first direction and a second direction that intersect with each other, the method comprising: acquiring a plurality of types of inspection images by having the camera capture an image of transmitted light that has passed through the transparent parts of the article; and performing at least one of a first inspection that inspects dark parts that are an image area of ​​the light-shielding part for the presence or absence of defects that are brighter than the dark parts, and a second inspection that inspects bright parts that are an image area of ​​the light-transmitting part for the presence or absence of defects that are brighter than the bright parts, based on the plurality of types of inspection images. Effect of the Invention

[0016] The present invention improves the accuracy of inspection for detecting defects in transparent portions of articles. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a schematic side view showing an article imaging device according to the first embodiment. [Diagram 2] FIG. 2 is a schematic front view showing the light blocking member. [Diagram 3] FIG. 3 is a schematic cross-sectional view showing how light is refracted at a defect in an article through a light-shielding member. [Figure 4] FIG. 4 is a schematic front view showing the light-shielding member and an article. [Diagram 5] FIG. 5 is a block diagram showing the electrical configuration of the article inspection device. [Figure 6] FIG. 6 is a schematic plan view showing an article imaging system. [Figure 7] FIG. 7(a) is a schematic diagram showing a first captured image, and FIG. 7(b) is a schematic diagram showing a second captured image. [Figure 8]FIG. 8(a) is a schematic diagram showing a dark area composite image, and FIG. 8(b) is a schematic diagram showing a bright area composite image. [Figure 9] FIG. 9 is a diagram showing the configuration of a camera in the second embodiment, and a graph showing the relationship between the light receiving wavelength and the relative sensitivity of the image sensor. [Figure 10] FIG. 10 is a graph showing the RGB sensitivity characteristics of the camera and the emission spectrum of the lighting unit. [Figure 11] 11(a) and 11(b) are captured images of a comparative example. [Figure 12] 12(a) and 12(b) are images captured in the embodiment. [Figure 13] 13(a) and 13(b) are schematic front views showing a light-shielding member and an article according to a modified example. [Figure 14] 14(a) and 14(b) are schematic front views showing a light blocking member in a modified example different from that in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] (First embodiment) Hereinafter, the article imaging device and the article inspection device will be described with reference to the drawings. The article inspection device 10 of this embodiment includes an article imaging device 11 shown in Fig. 1 that images an article 12 having at least a part of a transparent portion through which light can pass. The article inspection device 10 inspects the article 12 for defects based on the image of the article 12 acquired by the article imaging device 11.

[0019] <Basic configuration of the article imaging device 11> First, the configuration of the article imaging device 11 will be described with reference to FIG. 1. As shown in FIG. 1, the article imaging device 11 includes an illumination unit 20, a camera 30, and a light blocking member 40. The article imaging device 11 acquires an image (inspection image) used for inspecting the article 12 by using the camera 30 to image the article 12. In this embodiment, an example of a transparent article 12 in which the entire article 12 is transparent will be described, but the article 12 may have a transparent portion in part. In the example shown in FIG. 1, the article 12 is a transparent container. The transparent container is, for example, a plastic bottle or a glass container. When the article 12 is a bottle or the like, it has a cylindrical body portion 12A and a mouth portion 12B. The article 12 has, for example, a shape having an axis AL, but may have a shape not having an axis AL.

[0020] During inspection, the article 12 is placed at the imaging position SP. The article 12 is placed in a position in which the axis AL is parallel to the vertical direction Z. The article imaging device 11 may include a placement unit 13 on which the article 12 at the imaging position SP is placed. The placement unit 13 may be a placement table on which an operator places the article 12, or may be a relative movement mechanism 14 that moves the article 12 relatively in a direction intersecting with the optical axis C of the camera 30. The article 12 may also be placed on the placement unit 13 by an articulated robot.

[0021] The illumination unit 20 illuminates the article 12 placed at the imaging position SP. The illumination unit 20 may be, for example, a surface light emitter. The illumination unit 20 is placed such that its light emitting surface faces the article 12 at the imaging position SP.

[0022] The camera 30 is disposed at a position opposite to the illumination unit 20 with respect to the article 12. The camera 30 captures an image Img of transmitted light that is illumination light from the illumination unit 20 transmitted through the article 12. That is, the article imaging device 11 employs a light transmission method.

[0023] The light blocking member 40 is disposed between the illumination unit 20 and the object 12. As an example, the light blocking member 40 is a flat light blocking plate. The light blocking member 40 has light blocking portions 41 and light transmitting portions 42 arranged alternately in a predetermined direction. The light blocking portions 41 and light transmitting portions 42 are arranged two-dimensionally along the surface of the light blocking member 40. A detailed configuration of the two-dimensional arrangement of the light blocking portions 41 and light transmitting portions 42 in the light blocking member 40 will be described later.

[0024] The light-shielding portions 41 arranged two-dimensionally on the light-shielding member 40 block the light from the illumination unit 20. The light-transmitting portions 42 arranged two-dimensionally on the light-shielding member 40 transmit the light from the illumination unit 20. The camera 30 captures an image Img of transmitted light that is the light from the illumination unit 20 that has been blocked by the light-shielding portions 41 and transmitted through the light-transmitting portions 42 and that has transmitted through the object 12.

[0025] <Configuration of light blocking member 40> Next, the configuration of the light blocking member 40 will be described with reference to Fig. 2. In the light blocking member 40, a surface perpendicular to the optical axis C of the camera 30 is defined as a light blocking surface. The light blocking portions 41 and the light transmitting portions 42 are arranged in m rows and n columns on the light blocking surface. The light blocking member 40 has the light blocking portions 41 and the light transmitting portions 42 arranged two-dimensionally vertically and horizontally.

[0026] The light shielding member 40 is configured to be arranged two-dimensionally in which the light shielding portions 41 and the light transmitting portions 42 are alternately positioned in a first direction D1 and a second direction D2 that intersect with each other. In the example shown in FIG. 2, the row direction is the first direction D1, and the column direction is the second direction D2. The light shielding portions 41 and the light transmitting portions 42 are arranged two-dimensionally, alternately aligned in a row in the first direction D1 and alternately aligned in a row in the second direction D2. The light shielding portions 41 and the light transmitting portions 42 are arranged in the first direction D1 at a first pitch P1 and arranged in the second direction D2 at a second pitch P2. The first direction D1 is a direction that coincides with the moving direction MD. The light shielding member 40 is arranged, for example, in a direction in which the first direction D1 coincides with the moving direction MD. The light shielding portions 41 and the light transmitting portions 42 shown in FIG. 2 are an example in which they have the same shape and approximately the same size, and their shapes are quadrangular (for example, square). Moreover, the light transmitting portion 42 may be an opening or may be made of a transparent material.

[0027] When one light-shielding portion 41 is focused on, four light-transmitting portions 42 are located at four positions adjacent to the focused light-shielding portion 41 in four directions. That is, one light-shielding portion 41 is surrounded by four light-transmitting portions 42 on all four sides. When one light-transmitting portion 42 is focused on, four light-shielding portions 41 are located at four positions adjacent to the focused light-transmitting portion 42 in four directions. That is, one light-transmitting portion 42 is surrounded by four light-shielding portions 41 on all four sides. Note that the light-shielding portion 41 and the light-transmitting portion 42 may be polygonal other than a quadrangle, or different polygons may be mixed, or may be a shape other than a polygon. For example, in the case of a triangle, one light-shielding portion 41 may be surrounded by three light-transmitting portions 42 on three sides, and one light-transmitting portion 42 may be surrounded by three light-shielding portions 41 on three sides, in a two-dimensional arrangement. In this manner, by arranging the light-shielding portions 41 and the light-transmitting portions 42 two-dimensionally, one of the light-shielding portions 41 and the light-transmitting portions 42 is surrounded by three or more of the other from three or more directions.

[0028] <Principle of defect detection improvement by light shielding member 40> Next, the principle of how defect detection accuracy is improved by using the light-shielding member 40 of this embodiment will be described with reference to Fig. 3. Note that Fig. 3 is a schematic diagram for explaining the principle, and the positional relationship between the illumination unit 20, the light-shielding member 40, and the article 12 differs from the actual one.

[0029] 3, there are concave defects K1 and K2, such as scratches, in the inspection target area of ​​the article 12. The defect K1 is located at a position corresponding to the light-shielding portion 41. The defect K2 is located at a position corresponding to the light-transmitting portion 42. Here, the principle of the increase in luminance of the defect K1 against the background of the light-shielding portion 41 and the principle of the decrease in luminance of the defect K2 against the background of the light-transmitting portion 42 will be described.

[0030] In FIG. 3, light L1 from the illumination unit 20 that passes through the light-transmitting portion 42 is indicated by a dashed line. Light L2 (such as reflected light) from the light-shielding portion 41 is indicated by a dashed line. Bright light L1 that passes through the light-transmitting portion 42 from the illumination unit 20 is incident on the article 12. Dark light L2 from the light-shielding portion 41 is incident on the article 12. The light L1 and L2 that are incident almost perpendicularly to the surface of the article 12 travel straight without being refracted much. A two-dimensional light and dark pattern corresponding to the two-dimensional arrangement of the light-shielding portion 41 and the light-transmitting portion 42 is captured in the image captured by the camera 30.

[0031] In the areas where defects K1 and K2 are present, light L1 and L2 are refracted according to the angle of the surface on which the light enters among the inner surfaces of defects K1 and K2. In FIG. 3, in defect K1 against the light-shielding portion 41, bright light L1 entering from the light-transmitting portion 42 is refracted by the defect K1 and directed toward the camera 30. Also, dark light L2 from the light-shielding portion 41 is refracted by the defect K1 in a direction not directed toward the camera 30. The light L1 and L2 shown in FIG. 3 enter defect K1 in a direction perpendicular to the paper surface of FIG. 3 as well. For this reason, the brightness of defect K1 against the light-shielding portion 41 is likely to increase. Therefore, bright defect K1 stands out against a dark background.

[0032] Furthermore, in the defect K2 with the transparent portion 42 as the background, the bright light L1 entering from the transparent portion 42 is refracted at the defect K2 and refracted in a direction not directed toward the camera 30. Furthermore, the dark light L2 from the light-shielding portion 41 is refracted at the defect K2 and directed toward the camera 30. The refraction of the dark light L2 at the defect K2 makes the light-shielding portion 41 prone to being reflected. The incidence of the lights L1 and L2 shown in FIG. 3 on the defect K2 also occurs in a direction perpendicular to the paper surface of FIG. 3. Due to this type of reflection of the light-shielding portion 41, the brightness of the defect K2 with the transparent portion 42 as the background tends to be low. Therefore, the dark defect K2 stands out against a bright background.

[0033] The direction of light refraction at the defects K1 and K2 is determined depending on the incident direction of the light and the angle of the surface of the defects K1 and K2 into which the light is incident. Therefore, defects include bright defects K1 with high luminance and dark defects K2 with low luminance depending on the formation direction of scratches, etc., the surface shape, etc. In an example in which the article 12 of this embodiment is a transparent container, the bright defects K1 tend to be more numerous than the dark defects K2.

[0034] <Defects K1 and K2 in the light-shielding member 40 and the article 12> Next, with reference to Fig. 4, the principle by which defects K1 and K2 become noticeable by using the light-shielding member 40 of this embodiment will be described. Fig. 4 shows the light-shielding member 40 and the object 12 as seen by the camera 30. The object 12 is entirely transparent, so the two-dimensional light and dark pattern of the light-shielding member 40 can be seen through the object 12. The camera 30 captures an image of the transparent object 12 and the two-dimensional light and dark pattern of the light-shielding member 40 in the background by transmitting through the object 12.

[0035] Here, the example article 12 shown in FIG. 4 has a bright defect K1 that increases the luminance and a dark defect K2 that decreases the luminance. As shown in Fig. 4, bright light L1, indicated by dashed lines in Fig. 4, enters the part of the article 12 corresponding to the light-shielding portion 41 from the light-transmitting portions 42 on all four sides. For this reason, the defect K1 with the light-shielding portions 41 as the background tends to have high brightness. Also, dark light L2, indicated by dashed lines in Fig. 4, enters the part of the article 12 corresponding to the light-transmitting portion 42 from the light-shielding portions 41 on all four sides. For example, when this type of dark light L2 is refracted by the defect K2, the light-shielding portion 41 tends to be reflected. For this reason, the defect K2 with the light-transmitting portions 42 as the background tends to have low brightness.

[0036] In this manner, the light L1, L2 enters the defects K1, K2 in this embodiment from three or more directions (for example, four directions) adjacent to the background portion. Therefore, compared with the one-dimensional arrangement of light and dark patterns in the conventional technology in which light and dark are alternately arranged in one direction, the use of the light-shielding member 40 capable of forming the two-dimensional arrangement of light and dark patterns in this embodiment makes it easier to make the defect K1 brighter and the defect K2 darker.

[0037] Furthermore, in the case of defects K1 and K2 such as scratches, it is not possible to determine the direction in which they extend. Defects K1 and K2 such as scratches may extend in various directions, and the direction of extension may change along the way. In the conventional technology in which a one-dimensional light and dark pattern is formed, when a scratch extending in its longitudinal direction is entirely located in a slit-shaped elongated bright portion, if the background and the scratch are both high brightness (bright) or low brightness (dark) in combination, the entire scratch is difficult to notice. In this case, scratches are likely to go undetected.

[0038] In contrast, in this embodiment in which the light-shielding portions 41 and the light-transmitting portions 42 are arranged in a two-dimensional array, a two-dimensional light and dark pattern can be formed. Therefore, scratches extending in the first direction D1 and scratches extending in the second direction D2 frequently include a portion where the background and the scratch are a combination of high luminance (bright) and low luminance (dark). If the background and the scratch include even a part where the background and the scratch are a combination of high luminance and low luminance, the scratch will be noticeable at least in that portion.

[0039] <Total number of light-shielding portions 41 and light-transmitting portions 42> The total number of light-shielding portions 41 and light-transmitting portions 42 included in the inspection target area of ​​the article 12 may be set to a value within a predetermined range. It is preferable that at least a part of the bright defect K1 with high luminance is located on a dark background with low luminance. It is also preferable that at least a part of the dark defect K2 with low luminance is located on a bright background with high luminance. If the size of each light-transmitting portion 42 is too large, the frequency that the entire bright defect K1 is included in the bright background of one light-transmitting portion 42 increases. In this case, the bright defect K1 is not noticeable. If the size of each light-shielding portion 41 is too large, the frequency that the entire dark defect K2 is included in the dark background of one light-shielding portion 41 increases. In this case, the dark defect K2 is not noticeable.

[0040] Conversely, if the size of each of the light-shielding portions 41 and light-transmitting portions 42 is too small, the defects K1 and K2 are divided into small pieces, reducing the contrast between the light and dark areas, or creating unnecessary light and dark areas due to light diffraction, etc. These can make the defects K1 and K2 less noticeable or can lead to erroneous detection.

[0041] In this embodiment, the total number of light-shielding portions 41 and light-transmitting portions 42 included in the inspection target area of ​​the article 12 is set to a value of 10 or more and 200 or less, as an example. The total number is a value counted on the image captured by the camera 30. The total number referred to here is indicated by a value obtained by dividing the area of ​​the inspection target area of ​​the article 12 by the sum (sum area) of the area of ​​one light-shielding portion 41 and the area of ​​one light-transmitting portion 42. When the light-shielding portions 41 and the light-transmitting portions 42 each have a plurality of sizes, the sum area may be the most frequent value. The total number of light-shielding portions 41 and light-transmitting portions 42 included in the inspection target area may be less than 10 or more than 200.

[0042] <Electrical configuration of the article inspection device 10> Next, the electrical configuration of the article inspection device 10 will be described with reference to FIG. As shown in FIG. 5, the article inspection device 10 includes an article imaging device 11 and an inspection processing unit 60. The article imaging device 11 includes an illumination unit 20, a camera 30, and a light blocking member 40, which are also shown in FIG. 1. The illumination unit 20 has, for example, a plurality of light emitting units 21. The light emitting unit 21 is, for example, composed of a light emitting LED. The article imaging device 11 further includes a control unit 50. The control unit 50 includes an imaging control unit 51 and an image processing unit 53. The article imaging device 11 also includes a sensor 15 that detects the article 12 at the imaging position SP. Furthermore, the article imaging device 11 may include the aforementioned placement unit 13 on which the article 12 at the imaging position SP is placed. The placement unit 13 may be a relative movement mechanism 14.

[0043] The imaging control unit 51 controls the illumination unit 20 and the camera 30. The imaging control unit 51 controls the illumination unit 20 to emit light and the camera 30 to capture images based on a detection signal from the sensor 15 that detects the item 12 just before it reaches the imaging position SP or the item 12 that has reached the imaging position SP. The imaging control unit 51 causes the illumination unit 20 to emit light to illuminate the item 12 at the imaging position SP. The imaging control unit 51 causes the camera 30 to capture an image Img of transmitted light that has passed through a transparent portion of the item 12. Through this imaging, the camera 30 acquires multiple types of inspection images for one item 12. In order to acquire multiple types of inspection images, the camera 30 may capture images of one item 12 multiple times.

[0044] The camera 30 includes a lens 31, an infrared cut filter 32, and an image sensor 33, which are arranged inside a lens barrel 30a. An image Img collected by the lens 31 is formed on the image sensor 33 after infrared light is removed by the infrared cut filter 32. The image sensor 33 outputs an image signal S1 including the captured image. Note that the camera can be used with or without the infrared cut filter 32. Therefore, the infrared cut filter 32 may not be necessary.

[0045] The imaging control unit 51 includes a signal processing unit 52 that receives an imaging signal S1 from the camera 30. The signal processing unit 52 performs signal processing on the imaging signal S1 received from the camera 30. When the signal processing unit 52 receives a black-and-white imaging signal S1 from the camera 30, which is a black-and-white camera, the signal processing unit 52 performs normalization, brightness adjustment using nonlinear processing such as gamma correction, and contour enhancement processing on the black-and-white imaging signal S1 as necessary. The signal processing unit 52 converts the processed imaging signal S1 into an image signal S2 including a one-band black-and-white image. The signal processing unit 52 outputs the image signal S2 to the image processing unit 53.

[0046] Furthermore, when the signal processing unit 52 is configured to receive an RGB color image signal S1 from the camera 30, which is a color camera, the signal processing unit 52 performs, as necessary, normalization processing, color separation processing for separating the image signal S1 into image signals R, G, and B bands each, brightness adjustment using nonlinear processing such as gamma correction, contour emphasis processing, etc. The signal processing unit 52 outputs image signals S2 each including an RGB color image, an R image, a G image, and a B image to the image processing unit 53.

[0047] The camera 30 may obtain a plurality of types of inspection images by capturing images a plurality of times. In this embodiment, the camera 30 captures images a plurality of times, for example, to obtain two types of inspection images. The camera 30 may capture images a plurality of times under different capturing conditions. When the camera 30 captures images a plurality of times (for example, twice), a plurality of types of imaging signals S1 are input from the camera 30 to the signal processing unit 52. The signal processing unit 52 outputs a plurality of types of image signals S2 by performing a predetermined process on the plurality of types of imaging signals S1. Note that images based on the plurality of types of image signals S2 may be the plurality of types of inspection images.

[0048] In this embodiment, the image processing unit 53 performs a predetermined image processing on the multiple types of image signals S2 to generate multiple types (for example, two types) of inspection images IS1, IS2 (inspection image data). More specifically, the image processing unit 53 performs a synthesis process on two types of images based on the two types of image signals S2 as necessary. For example, the image processing unit 53 performs a synthesis process in which only a part of the image area required for defect inspection is extracted from each of the two types of images and the extracted image areas are synthesized into one. The image processing unit 53 of this embodiment generates a first inspection image IS1 for inspecting the presence or absence of defect K1 and a second inspection image IS2 for inspecting the presence or absence of defect K2. The image processing unit 53 outputs the generated two types of inspection images IS1, IS2 to the inspection processing unit 60. In addition to the synthesis process, the image processing unit 53 may also perform a trimming process or the like in which an article image area, which is an area of ​​an article, or an inspection target area, which is a part of the article image area, is cut out from the image. Details of the two types of inspection images IS1, IS2 and the imaging conditions for acquiring them will be described later.

[0049] The inspection processing unit 60 inspects the presence or absence of defects in the article 12 based on the two types of inspection images IS1 and IS2. The inspection processing unit 60 performs a first inspection to inspect the presence or absence of a defect K1 having a higher brightness than the dark portion 41I, which is an image region of the light-shielding portion 41, based on the two types of inspection images IS1 and IS2, and a second inspection to inspect the presence or absence of a defect K2 having a lower brightness than the bright portion 42I, which is an image region of the light-transmitting portion 42. In this embodiment, the inspection processing unit 60 includes a first inspection processing unit 61 and a second inspection processing unit 62. The first inspection processing unit 61 performs a first inspection to inspect the presence or absence of the defect K1 based on the first inspection image IS1. The second inspection processing unit 62 performs a second inspection to inspect the presence or absence of the defect K2 based on the second inspection image IS2. The inspection processing unit 60 outputs the inspection image and information regarding the presence or absence of defects to the display unit 65 as an inspection result.

[0050] <Configuration of imaging system 100> Next, referring to FIG. 6, an imaging system 100 including an article imaging device 11 will be described. The article imaging device 11 shown in FIG. 1 is not limited to being used alone, and may constitute an imaging system 100. The imaging system 100 includes a plurality of article imaging devices 11 for inspecting the entire circumference of an article 12, for example. The imaging system 100 includes a conveying unit 70 that conveys the article 12 in a moving direction MD. The conveying unit 70 constitutes an example of a relative movement mechanism 14 that moves the article 12 relative to the camera 30 and the light blocking member 40. The conveying unit 70 includes an endless conveyor 71, rollers 72 and 73 around which the conveyor 71 is wound, and a motor 74 that is a driving source that rotates and drives the driving roller 73. The motor 74 is driven and controlled by, for example, the control unit 50.

[0051] The imaging system 100 includes N sets (where N is a natural number of 2 or more) of article imaging devices 11 that image an article 12 transported by a conveyor 71 in a moving direction MD from N different directions. In the example shown in Fig. 6, N=4, and the imaging system 100 includes four sets of article imaging devices 11. The four sets of article imaging devices 11 are a first article imaging device 11A, a second article imaging device 11B, a third article imaging device 11C, and a fourth article imaging device 11D. Note that the value N in the imaging system 100 is not limited to 4, and may be 2, 3, 5, 6 or more.

[0052] The first article imaging device 11A and the second article imaging device 11B image the article 12 when it is at the first imaging position SP1. The third article imaging device 11C and the fourth article imaging device 11D image the article 12 when it is at the second imaging position SP2 located downstream of the first imaging position SP1 in the moving direction MD. When the sensor 15 detects the article 12 just before or when it reaches the first imaging position SP1, the first illumination unit 20A and the second illumination unit 20B illuminate the article 12, and the first camera 30A and the second camera 30B image the article 12 at the first imaging position SP1. The light emission control of the third illumination unit 20C and the fourth illumination unit 20D and the imaging control of the third camera 30C and the fourth camera 30D when the article 12 is imaged at the second imaging position SP2 are also performed similarly based on the detection signal of the sensor 15.

[0053] Under the control of the imaging control unit 51 (see FIG. 5), each of the cameras 30A-30D captures an image of the transmitted light of the article 12 twice with the corresponding light shielding member 40A-40D in the background. The timing for determining the second imaging from the first imaging may be when a time determined by the relative movement speed and the half cycle of the phase has elapsed, or when the driving source is a motor 74, when the count value of the pulse edge of the detection pulse from a rotary encoder (not shown) that detects the rotation of the motor 74 reaches a value corresponding to the half cycle of the phase. Each of the cameras 30A-30D captures multiple types (e.g., two types) of inspection images of the article 12 from four directions. In this way, multiple types of inspection images (e.g., four images) of the entire circumference of the article 12 are acquired.

[0054] The relative movement mechanism 14 may be any mechanism capable of relatively moving the article 12 and the light blocking member 40. The relative movement mechanism 14 may be configured to relatively move at least one of the article 12 and the light blocking member 40 in a direction intersecting the optical axes C1 to C4 of the cameras 30A to 30D. The movement direction MD of the relatively moving article 12 is, for example, a direction intersecting the optical axes C1 to C4 of the cameras 30A to 30D and perpendicular to the axis AL of the article 12. The relative movement mechanism 14 is not limited to the conveying section 70, and may be a rotation mechanism that rotates the article 12. The article 12 that rotates by the rotation mechanism may be imaged N times by one camera 30 to obtain captured images of the entire circumference. The conveying section 70 may be a conveying section 70 with a rotation mechanism that conveys the article 12 in the movement direction MD while rotating the article 12. The conveying unit 70 may also be of a rotary type that rotates and revolves the article 12 while suctioning or gripping the mouth 12B of the article 12.

[0055] <Two imaging timings> Next, with reference to Fig. 7, the imaging timing when the control unit 50 captures an image of one item 12 twice, and two types of captured images acquired in the two captures will be described. Figs. 7(a) and (b) show two captured images Img1 and Img2 acquired by the camera 30 in two captures. Fig. 7(a) shows the first captured image Img1, and Fig. 7(b) shows the second captured image Img2. Note that the item 12, the light shielding member 40, and the defects K1 and K2 in the images are indicated as item 12I, the light shielding member 40I, and the defects K1I and K2I, with "I" added after the reference numerals.

[0056] The control unit 50 (see FIG. 5) causes the camera 30 to capture the article 12 twice while the light blocking member 40 and the article 12 are moving relatively in the moving direction MD by the relative moving mechanism 14. The first image capturing timing is the timing when the article 12 is at the image capturing position SP. The first image capturing timing is a timing when the first captured image Img1 (hereinafter also simply referred to as the "first image Img1") shown in FIG. 7(a) is acquired. The second image capturing timing is a timing when the article 12I moves in the moving direction MD by half the pitch P1 (=P1 / 2) relative to the light blocking member 40I from the first image capturing timing. The second image capturing timing is a timing when the second captured image Img2 (hereinafter also simply referred to as the "second image Img2") shown in FIG. 7(b) is acquired.

[0057] As shown in Fig. 7(a) and (b), in the captured images Img1 and Img2, dark areas 41I due to the light-shielding portion 41 and light areas 42I due to the light-transmitting portion 42 are periodically arranged in the moving direction MD, with a distance on the image corresponding to the pitch P1 being one period. The positional relationship in the moving direction MD of the article 12I relative to the light-shielding member 40I is indicated by the phase of a light-dark pattern in which the dark areas 41I and the light areas 42I are periodically repeated in the moving direction MD. Compared to the phase of the article 12I in the first captured image Img1 shown in Fig. 7(a), the phase of the article 12I in the second captured image Img2 shown in Fig. 7(b) advances in the moving direction MD by half a period (180°).

[0058] The first captured image Img1 shown in Fig. 7(a) and the second captured image Img2 shown in Fig. 7(b) have a phase difference of half a period, so that the positions of the dark portion 41I and the bright portion 42I, which are the background of the article 12I, are swapped with respect to the article 12I. When the relative movement mechanism 14 is a rotation mechanism, the camera 30 may capture the article 12 twice before and after the side peripheral surface of the article 12I shifts by half a period in phase in the moving direction MD with respect to the light blocking member 40I during the process of the article 12 rotating about the axis line AL. Then, two images each are captured N times (e.g., four times) every time the article 12 rotates by 360° / N.

[0059] In the two captured images Img1, Img2 acquired by two captures, the positions of the bright and dark areas in the article 12I may be interchanged. Therefore, the amount of relative movement of the article 12 with respect to the light blocking member 40 may be an odd multiple of half the pitch P1 / 2. For example, the amount of relative movement may be three or five times P1 / 2. In short, it is sufficient that the phases of the bright and dark areas in the images differ by half a period (180°).

[0060] <About multiple types of test images> The two types of captured images Img1 and Img2 shown in Figures 7(a) and (b) may be used as the two types of inspection images IS1 and IS2. When inspecting a high-luminance, bright defect K1, both the dark portion 41I in the first inspection image IS1 and the dark portion 41I in the second inspection image IS2 are inspected. When inspecting a low-luminance, dark defect K2, both the bright portion 42I in the first inspection image IS1 and the bright portion 42I in the second inspection image IS2 are inspected. In this case, two types of inspection images IS1 and IS2 are used for inspecting the defects K1 and K2, respectively, so a total of four inspection processes are required.

[0061] <Image synthesis processing> Next, the image processing performed by the image processing unit 53 will be described with reference to FIG. 8. The image processing unit 53 generates a dark area composite image Img11 by combining both dark areas 41I into one from two types of captured images Img1 and Img2 shown in FIG. 7(a) and (b), and a bright area composite image Img12 by combining both bright areas 42I into one. In detail, the image processing unit 53 generates the dark area composite image Img11 shown in FIG. 8(a) by combining both dark areas 41I included in the two types of captured images Img1 and Img2 into one. The dark area composite image Img11 is an image in which the entire area inside the article 12I is the dark area 41I. Note that FIG. 8(a) shows an image in which only the area of ​​the article 12I is cut out, but the dark area composite image Img11 may be an image in which the entire area outside the article 12I is also the dark area 41I.

[0062] The image processing unit 53 also generates a bright portion composite image Img12 shown in Fig. 8(b) by combining both bright portions 42I included in the two captured images Img1 and Img2 into one. The bright portion composite image Img12 is an image in which the entire area inside the article 12I is made into the bright portion 42I. Note that, while Fig. 8(b) shows an image in which only the area of ​​the article 12I is cut out, the bright portion composite image Img12 may also be an image in which the entire area outside the article 12I is made into the bright portion 42I.

[0063] In the first inspection image IS1 shown in Fig. 8(a), the entire bright defect K1I is located on the background of the dark area 41I. In the second inspection image IS2 shown in Fig. 8(b), the entire dark defect K2I is located on the background of the bright area 42I.

[0064] The inspection processing unit 60 uses these two types of inspection images IS1 and IS2 to inspect for the presence or absence of defects K1 and K2. The inspection processing unit 60 detects a high luminance portion equal to or greater than a first threshold in the dark portion 41I based on the dark portion composite image Img11 as defect K1. The inspection processing unit 60 also detects a low luminance portion equal to or less than a second threshold in the bright portion 42I based on the bright portion composite image Img12 as defect K2.

[0065] <Operation of the First Embodiment> Next, the operation of the article inspection device 10 will be described. As shown in Fig. 6, the transparent article 12, which is the subject, is transported in the moving direction MD by the conveyor 71 of the transport unit 70. The control unit 50 controls the illumination unit 20 and the camera 30 at a timing when the article 12 can be imaged at the two imaging positions SP1 and SP2 based on a detection signal from the sensor 15. The four cameras 30A-30D image the article 12 from four directions, thereby acquiring images of the entire circumference of the article 12. Therefore, the entire circumference of the article 12 is subject to inspection. Since the image processing and inspection processing using the images acquired by each camera 30A-30D by imaging the article 12 are basically the same, the processing contents for the image acquired by one camera 30 will be described here.

[0066] By controlling the illumination unit 20 by the imaging control unit 51, the article 12 is irradiated with, for example, white light from the illumination unit 20. The camera 30 captures an image Img of transmitted light that has passed through the light-transmitting portion 42 of the light-shielding member 40 and the article 12. At this time, the camera 30 captures an image of the article 12 twice at a time interval of half the light-dark cycle.

[0067] The camera 30 captures a first image Img1 shown in Fig. 7(a) and a second image Img2 shown in Fig. 7(b). The two images Img1 and Img2 have a relationship in which the positions of the dark areas 41I and the light areas 42I within the area of ​​the article 12I are swapped.

[0068] The two types of images Img1 and Img2 may be used as inspection images IS1 and IS2 to inspect the presence or absence of defects K1 and K2. In this case, the inspection processing unit 60 detects the dark parts 41I of each of the two types of images Img1 and Img2 as inspection areas and detects parts with a brightness equal to or greater than a first threshold as defect K1. The inspection processing unit 60 also detects the bright parts 42I of each of the two types of images Img1 and Img2 as inspection areas and detects parts with a brightness less than a second threshold as defect K2.

[0069] In this embodiment, the image processing unit 53 may generate new inspection images IS1 and IS2 shown in Fig. 8(a) and (b) by synthesizing two types of captured images Img1 and Img2. The image processing unit 53 generates a dark area composite image Img11 shown in Fig. 8(a) by synthesizing both dark areas 41I included in each of the two types of captured images Img1 and Img2 into one. The image processing unit 53 also generates a bright area composite image Img12 shown in Fig. 8(b) by synthesizing both bright areas 42I included in each of the two types of captured images Img1 and Img2 into one. The image processing unit 53 or the inspection processing unit 60 generates an image in which only the inspection target area (for example, the area of ​​the article 12I) is cut out, as shown in Fig. 8(a) and (b).

[0070] The inspection processing unit 60 sets the dark composite image Img11 shown in Fig. 8(a) as a first inspection image IS1, and detects a high brightness portion equal to or greater than a first threshold within the inspection target area of ​​the article 12I as a defect K1. The inspection processing unit 60 also sets the bright composite image Img12 shown in Fig. 8(b) as a second inspection image IS2, and detects a low brightness portion less than a second threshold within the inspection target area of ​​the article 12I as a defect K2.

[0071] In this manner, the inspection processing unit 60 inspects the presence or absence of defects K1, K2 over the entire circumference of the article 12 using the inspection images IS1, IS2 based on the imaging signals S1 from the cameras 30A-30D shown in Fig. 6. If the article 12 is defective, the control unit 50 drives a discharge device (not shown) to remove the defective article 12 from the conveyor 71.

[0072] <Effects of the embodiment> According to the first embodiment described above in detail, the following effects can be obtained. (1-1) The article inspection device 10 captures and inspects an article 12 having at least a part of a transparent portion through which light can pass. The article inspection device 10 includes an illumination unit 20, a camera 30, a light-shielding member 40, an imaging control unit 51, and an inspection processing unit 60. The illumination unit 20 illuminates the article 12 arranged at an imaging position SP. The camera 30 is arranged at a position opposite the illumination unit 20 with respect to the article 12. The light-shielding member 40 is arranged between the illumination unit 20 and the article 12, and is arranged alternately in a first direction D1 and a second direction D2 that intersect with each other, so that the light-shielding portions 41 and the light-transmitting portions 42 are arranged two-dimensionally. The imaging control unit 51 causes the camera 30 to capture an image of transmitted light that has passed through the transparent portion of the article 12, thereby acquiring a plurality of types of inspection images IS1, IS2. The inspection processing unit 60 inspects the presence or absence of defects in the article 12 based on the plurality of types of inspection images IS1, IS2. The inspection processing unit 60 performs at least one of a first inspection, which inspects the dark areas, which are the image area of ​​the light-shielding portion 41, for defects that are brighter than the dark areas, and a second inspection, which inspects the bright areas, which are the image area of ​​the light-transmitting portion 42, for defects that are brighter than the bright areas, based on multiple types of inspection images IS1 and IS2.

[0073] According to this configuration, since the light-shielding portion 41 and the light-transmitting portion 42 are arranged two-dimensionally, the light L1 from the light-shielding portion 41 and the adjacent light-transmitting portion 42 is incident from three or more directions on the portion of the article 12 with the light-shielding portion 41 (dark portion) as the background. Therefore, the luminance of the defect K1 located in the portion with the dark portion as the background is likely to increase. Similarly, dark light L2 from the light-shielding portion 41 adjacent to the light-transmitting portion 42 is incident from three or more directions on the portion of the article 12 with the light-transmitting portion 42 (bright portion) as the background. Therefore, the luminance of the defect K2 located in the portion with the bright portion as the background is likely to decrease. Therefore, the inspection accuracy of the defect K1 or the defect K2 is improved compared to a conventional article inspection device using a light-shielding member having a one-dimensional light-dark pattern in which the light-shielding portion and the light-transmitting portion (e.g., slits) are arranged in only one direction.

[0074] (1-2) The inspection processing unit 60 detects a high brightness portion equal to or greater than a first threshold in the dark portion 41I based on the first inspection image IS1 as defect K1. The inspection processing unit 60 detects a low brightness portion less than a second threshold in the bright portion 42I based on the second inspection image IS2 as defect K2. With this configuration, it is possible to detect both defect K1, which is imaged bright, and defect K2, which is imaged dark. This improves the inspection accuracy for defects.

[0075] (1-3) The imaging control unit 51 causes the camera 30 to perform imaging two or more times under imaging conditions in which the phases of the light-shielding portion 41 and the light-transmitting portion 42 for the article 12 are different. The multiple types of inspection images IS1 and IS2 acquired from the camera 30 are images in which the phases of the dark portion 41I and the light portion 42I for the article 12I in the images are different. The inspection processing unit 60 inspects the presence or absence of defects on the article 12 based on the multiple types of inspection images IS1 and IS2. According to this configuration, by using multiple types of inspection images IS1 and IS2 in which the phases of the dark portion 41I and the light portion 42I for the article 12I are different for inspection, the defect K1 can be inspected against a wider dark portion 41I as a background, or the defect K2 can be inspected against a wider light portion 42I as a background. Therefore, compared to inspection based on an inspection image of only one phase, the background that can be inspected is wider, and the detection omission of defects is reduced, thereby improving the inspection accuracy of defects.

[0076] (1-4) The article inspection device 10 includes an image processor 53. The image processor 53 generates a dark composite image Img11 by synthesizing the dark areas 41I included in each of the multiple types of inspection images IS1 (Img1) and IS2 (Img2). Alternatively, the image processor 53 generates a bright composite image Img12 by synthesizing the bright areas 42I included in each of the multiple types of inspection images IS1 (Img1) and IS2 (Img2). The inspection processor 60 inspects the presence or absence of defects in the article 12 based on the dark composite image Img11 or the bright composite image Img12. According to this configuration, the defect K1 is inspected based on the dark composite image Img11, or the defect K2 is inspected based on the bright composite image Img12, so that the inspection omission of the defect K1 or the defect K2 can be reduced. In each inspection image before synthesis, one defect may be divided into each of the dark area 41I and the bright area 42I. Therefore, when each inspection image is inspected separately, detection omissions are likely to occur, and the inspection process to avoid such omissions becomes complicated. In contrast, in a composite image, a defect is not divided, so that omissions of defects can be reduced. Therefore, the inspection accuracy of defects is improved.

[0077] (1-5) The article inspection device 10 includes a relative movement mechanism 14 that moves the article 12 and the light blocking member 40 relative to each other in a direction that changes the phase of the dark portion 41I and the light portion 42I relative to the article 12I. The relative movement mechanism 14 moves the article 12 and the light blocking member 40 relative to each other in the first direction D1, for example, by causing the article 12 to perform one of the following operations: rotation, conveyance, or conveyance while rotating. In an example in which the relative movement mechanism 14 is the conveyance section 70, the article 12 is conveyed with the first direction D1 as the moving direction MD. According to this configuration, the relative movement of the article 12 and the light blocking member 40 changes the phase of the dark portion 41I and the light portion 42I relative to the article 12I as seen by the camera 30. The camera 30 captures the article 12 multiple times (two or more times) with different phases. Thus, multiple types of inspection images IS1, IS2 can be acquired simply by controlling the image capture timing of the camera 30.

[0078] (1-6) The article inspection method uses an illumination unit 20, a camera 30, a light blocking member 40, an imaging control unit 51, and an inspection processing unit 60. The article inspection method includes the following (A) and (B). (A) Obtaining a plurality of types of inspection images IS1, IS2 by having the camera 30 capture images of transmitted light that has passed through a transparent portion of the article 12. (B) Based on multiple types of inspection images IS1 and IS2, at least one of a first inspection is performed to inspect the dark portion 41I, which is an image area of ​​the light-shielding portion 41, for the presence or absence of a defect K1 that is brighter than the dark portion 41I, and a second inspection is performed to inspect the bright portion 42I, which is an image area of ​​the light-transmitting portion 42, for the presence or absence of a defect K2 that is brighter than the bright portion 42I. According to this article inspection method, the same effect as the effect (1) above can be obtained.

[0079] Second embodiment Next, a second embodiment will be described with reference to Figs. 9 to 12. In the second embodiment, the camera 30 is a color camera. Also, the illumination unit 20 is a monochromatic light source. Everything other than the camera 30 and the illumination unit 20 is the same as in the first embodiment. Hereinafter, image processing and inspection processing, etc., performed based on an image captured by the camera 30 of an object 12 illuminated using the illumination unit 20 of a monochromatic light source will be described.

[0080] 1, the camera 30 is, for example, an RGB color camera, and the illumination unit 20 is, for example, a blue light source that emits blue light. <Configuration of Camera 30> Next, the configuration and imaging characteristics of camera 30 will be described with reference to Fig. 9. Camera 30 shown in Fig. 9 is, for example, a general-purpose color camera that captures RGB color images. The general-purpose color camera includes lens 31 attached to lens barrel 30a, infrared cut filter 32 that blocks near-infrared light having a wavelength in the near-infrared wavelength region NIRA, and image sensor 33. Note that infrared cut filter 32 is not necessary.

[0081] 9 includes an R light receiving element 33R, a G light receiving element 33G, and a B light receiving element 33B. The R light receiving element 33R receives red light (R light) transmitted through the R filter 34R, and outputs an R imaging signal according to the amount of received light. The G light receiving element 33G receives green light (G light) transmitted through the G filter 34G, and outputs a G imaging signal according to the amount of received light. The B light receiving element 33B receives blue light (B light) transmitted through the B filter 34B, and outputs a B imaging signal according to the amount of received light. In the image sensor 33, the R light receiving element 33R, the G light receiving element 33G, and the B light receiving element 33B are arranged in a predetermined array.

[0082] The R light receiving element 33R, the G light receiving element 33G, and the B light receiving element 33B are sensitive to light in the respective wavelength bands shown in the graph on the right side of Fig. 9. In this graph, the horizontal axis represents wavelength and the vertical axis represents relative sensitivity. Near-infrared light is removed by the infrared cut filter 32.

[0083] Light with wavelengths of approximately 750 nm or more (mainly infrared light) is removed. Therefore, the relative outputs of the imaging signals output by the camera 30 are as follows: The R image signal has a relative output value of 0.1 or more mainly in the range of 570 to 700 nm. The G image signal has a relative output value of 0.1 or more mainly in the range of 470 to 700 nm. The B image signal has a relative output value of 0.1 or more mainly in the range of 380 to 550 nm.

[0084] The image sensor 33 has an RGB imaging characteristic having sensitivity only in the visible light region. That is, the R light receiving element 33R, the G light receiving element 33G, and the B light receiving element 33B are sensitive to light (visible light) in the visible light wavelength region VA shown in the graph on the right side of FIG. 9. The R light receiving element 33R has sensitivity to the band indicated by R in the graph, the G light receiving element 33G has sensitivity to the band indicated by G, and the B light receiving element 33B has sensitivity to the band indicated by B. Each of the light receiving elements 33R, 33G, and 33B receives light that has passed through each of the filters 34R, 34G, and 34B of the color filter 34, among the B light (blue light) that has passed through the light transmitting portion 42 of the light shielding member 40 (see FIG. 1, FIG. 2, etc.), according to its respective sensitivity. The image sensor 33 outputs an imaging signal S1 (see FIG. 5) in which imaging signals having R values, G values ​​and B values ​​corresponding to the amount of light received by each of the light receiving elements 33R, 33G and 33B are arranged serially in a predetermined order.

[0085] Moreover, the color filter 34 constituting the image sensor 33 may be a complementary color filter of Mg, Ye, and Cy instead of the RGB primary color filter. Furthermore, the RGB filter may be R, G1, G2, and B filters, and the color filter 34 may be a combination of a complementary color filter and a primary color filter. Furthermore, three or more types of filters may be combined.

[0086] The graph shown in Fig. 10 shows the RGB sensitivity characteristics of the camera 30. This graph also shows the emission spectrum LS of the illumination unit 20 that emits B light. The horizontal axis of the graph shows the wavelength, the vertical axis on the left side shows the relative output of the RGB light receiving elements, and the vertical axis on the right side shows the output power of the illumination unit 20 that emits B light. This graph shows the sensitivity characteristics of the R light receiving element 33R, G light receiving element 33G, and B light receiving element 33B of the image sensor 33 that constitutes the camera 30 when the illumination unit 20 is a monochromatic light source such as a blue LED that emits B light.

[0087] The wavelength of the B light is, for example, in the range of about 390 to 500 nm. The B light receiving element 33B has high sensitivity over almost the entire wavelength range of the B light. The G light receiving element 33G has high sensitivity in a partial range of 460 to 500 nm within the wavelength range of the B light. The R light receiving element 33R has low sensitivity in a partial range of about 390 to 430 nm within the wavelength range of the B light. The maximum relative output of the B light receiving element 33B is about 0.58 at about 460 nm. The maximum relative output of the G light receiving element 33G is about 0.64 at about 500 nm. The maximum relative output of the R light receiving element 33R is about 0.08 at about 400 nm.

[0088] When B light is received, the ratio of the amount of light received by the R light receiving element 33R, the G light receiving element 33G, and the B light receiving element 33B is approximately 1:7:16. Therefore, the R image, G image, and B image constituting the three-band RGB image obtained by capturing an image of the article 12 with the camera 30 become darker in that order. In other words, the B image is the brightest, the G image is next bright, and the R image is the darkest. The brightness ratio of the R image, G image, and B image is approximately 1:7:16. The R image is dark. The B image is bright. The G image has an intermediate brightness between the R and B images.

[0089] In this way, by using a color camera and a blue light source, it is possible to obtain multiple images with different brightness in one capture. Here, the G image is an image with a moderate brightness that is not as bright as the B image. Therefore, the G image is suitable for inspecting defect K1, whose brightness should be increased moderately. The R image is an image darker than the G image. Therefore, the R image is suitable for inspecting defect K2, whose brightness should be decreased moderately.

[0090] 11(a) and (b) are captured images Img101 and Img102 of comparative examples. Fig. 11(a) is an image Img101 captured without a light-shielding member. Fig. 11(b) is an image Img102 captured against a light-shielding member without a light-transmitting portion in the background. As shown in Figs. 11(a) and (b), defects such as scratches are not clear in either case, so the inspection accuracy is low.

[0091] 12(a) and (b) show inspection images IS1 and IS2 of this embodiment. FIG. 12(a) is a G image Img21 serving as the first inspection image IS1. FIG. 12(b) is an R image Img22 serving as the second inspection image IS2. The inspection processing unit 60 (see FIG. 5) uses the G image and the R image as the inspection images IS1 and IS2. As shown in FIG. 12(a), bright defects such as white scratches in the part against the dark background in the G image Img21 are clear. Also, as shown in FIG. 12(b), dark defects are easily noticeable in the part against the bright background in the R image Img22. Therefore, the inspection accuracy of bright and dark defects is improved.

[0092] According to the second embodiment, the following effects can be obtained. (2-1) The illumination unit 20 illuminates the article 12 with blue monochromatic light. The camera 30 is an RGB color camera, and captures an image Img of transmitted light that has passed through a transparent portion of the article 12 to obtain a color image. The multiple types of inspection images include a first inspection image IS1 used in a first inspection and a second inspection image IS2 used in a second inspection. The imaging control unit 51 separates the color images to obtain a B image or a G image as the first inspection image IS1, and obtains one of the G image and the R image that is different from the first inspection image IS1 as the second inspection image IS2. According to this configuration, the first inspection image IS1 and the second inspection image IS2 are one combination of a G image and an R image, a B image and a G image, or a B image and an R image. When the illumination light is blue light, the images become darker in the order of the B image, the G image, and the R image. Therefore, two types of inspection images IS1 and IS2 with different image brightness can be obtained in one imaging without imaging the article twice with different illumination brightness. In addition, even if capturing an image twice in order to change other imaging conditions than the image brightness, there is no need to change the brightness of the illumination, and therefore the imaging control required to acquire multiple types of inspection images can be simplified.

[0093] (2-2) In particular, in this embodiment, the G image and the R image are selected, which are different from the B image, which is an image of the same color as the B light, which is the emission color of the illumination unit 20. This allows the defects K1 and K2 to have appropriate brightness. For example, it is easy to avoid a situation in which the defect K1 against a dark background is excessively high brightness, or the degree to which the brightness of the defect K2 against a bright background is insufficient.

[0094] Third embodiment Next, a third embodiment will be described. The third embodiment is an example in which two images are captured in the same manner as in the first embodiment in the second embodiment. One of the object 12 and the light blocking member 40 is moved relative to the other by a relative movement mechanism 14 similar to that in FIG. 1. The camera 30, which is a color camera, captures images twice under imaging conditions in which the phases of light and dark in the background relative to the object 12 are different. By capturing images twice, two color images in which the phases of light and dark in the background relative to the object 12I are different are obtained as inspection images. The two color images are in a relationship in which the phases of light and dark in the object 12 differ by a half period.

[0095] The first color image acquired in the first imaging is color-separated to acquire a first inspection image IS1 (first G image) and a second inspection image IS2 (first R image) shown in Figures 12(a) and 12(b). In the second imaging, a third inspection image (second G image) and a fourth inspection image (second R image) (both not shown) are acquired, which have a light-dark phase for the object that differs by a half period from those in Figures 12(a) and 12(b).

[0096] The presence or absence of defects K1 and K2 may be inspected based on these four inspection images, or the image processing unit 53 may inspect for defects K1 and K2 based on an inspection image (G image) composed of two G images and an inspection image (R image) composed of two R images.

[0097] In the latter case, the image processing unit 53 generates a dark area composite image by combining a dark area in the 1G image (black area in FIG. 12(a)) with a dark area in the 2G image into one. Also, the image processing unit 53 generates a bright area composite image by combining a bright area in the 1R image (white area in FIG. 12(b)) with a bright area in the 2G image into one.

[0098] The inspection processing unit 60 inspects the article 12 for the presence or absence of a defect K1 based on the first inspection image IS1 (dark area composite image). The inspection processing unit 60 also inspects the article 12 for the presence or absence of a defect K2 based on the second inspection image IS2 (light area composite image).

[0099] According to the third embodiment, the following effects can be obtained. (3-1) Since inspection images with different image brightness can be obtained by capturing images once, four types of inspection images with different phases of dark and bright areas of the object 12I and different image brightness can be obtained by capturing images twice. Then, by combining the dark and bright areas of the two types of inspection images with different phases of dark and bright areas of the object 12I, defect K1 with a dark area as the background and defect K2 with a bright area as the background can be obtained over the entire area or a wide range. Therefore, compared to the configuration of the second embodiment, there are fewer missed defects, improving inspection accuracy.

[0100] (3-2) Inspect defects using the dark area composite image (G composite image) or the light area composite image (R composite image). This avoids inspecting the defects K1 and K2, which are divided by straddling the dark and light areas, individually, reducing the number of missed detections of the defects K1 and K2. This improves the inspection accuracy of the defects K1 and K2.

[0101] The embodiment is not limited to the above and may be modified in the following manner. The size and pitch of the light-shielding portion 41 and the light-transmitting portion 42 may be changed as appropriate. For example, as shown in FIG. 13(a), the size of the light-shielding portion 41 and the light-transmitting portion 42 may be made smaller than that of the first embodiment. In this case, as shown in FIG. 13(a), the number of light and dark portions within the area of ​​the article 12I will be greater than that of each of the above-mentioned embodiments. Also, the size of the light-shielding portion 41 and the light-transmitting portion 42 may be made smaller than that of FIG. 14(a), or conversely, made larger than that of the first embodiment.

[0102] As shown in Fig. 13(b), a light-shielding portion 43 may be formed along the boundary (contour) of the article 12 in the peripheral region of the boundary. Also, as shown in Fig. 13(b), a light-transmitting portion 44 may be formed in the peripheral region of the end face of the mouth 12B to which light is to be applied, extending along the end face of the mouth 12B.

[0103] As shown in FIG. 14(a), the light-shielding portion 41 and the light-transmitting portion 42 may have different sizes. In the example of FIG. 14(a), the size of the light-shielding portion 41 is larger than the size of the light-transmitting portion 42. In this configuration, the region (area) in which the bright defect K1 can be inspected is widened, so that the oversight of the high-luminance defect K1, which occurs more frequently, can be suppressed. In this case, only the bright defect K1 may be inspected by inspecting only the first inspection image IS1, and this is also effective in reducing the oversight of the defect K1. In addition, the combination of sizes may be reversed, and a two-dimensional light-shielding member 40 may be obtained by replacing the light-shielding portion 41 and the light-transmitting portion 42 in FIG. 14(a). In this case, the light-shielding member 40 may be maintained in a predetermined shape such as a plate shape by attaching a transparent member 45 made of a transparent film or glass that transmits visible light, or filling the opening of the light-transmitting portion 42 with a transparent member 45 made of a synthetic resin. 14(b), the shape of the light-shielding portion 41 and the shape of the light-transmitting portion 42 may be different. In FIG. 14(b), the shape of the light-transmitting portion 42 is an oval or ellipse, but the shape may be a polygon such as a triangle, a rhombus, a pentagon, or a hexagon. Furthermore, the light-shielding portion 41 and the light-transmitting portion 42 may be interchanged in FIG. 14(b) by applying a transparent member or filling the opening.

[0104] The light-shielding member may be a liquid crystal type light-shielding panel that can electrically replace the light-shielding portion and the light-transmitting portion by applying the principle of a liquid crystal panel. The liquid crystal type light-shielding panel includes, for example, a pair of alignment films sandwiching a liquid crystal layer, a pair of transparent electrodes (pixel electrodes), and a pair of polarizing filters. The type of the liquid crystal type light-shielding panel is not limited to the TN type, and may be the STN type, the IPS type, or the VA type. The liquid crystal type light-shielding panel may be, for example, a liquid crystal panel (liquid crystal display). The imaging control unit 51 electrically controls the liquid crystal type light-shielding panel to control the light-shielding portion and the light-transmitting portion to a two-dimensional array (FIGS. 2, 13, 14, etc.). When imaging the article 12, for example, twice during inspection, the imaging control unit 51 electrically replaces the light-shielding portion and the light-transmitting portion between the first imaging and the second imaging. This allows the article 12 to be imaged twice under different two-dimensional arrays in which the light-shielding portion and the light-transmitting portion are replaced. According to this configuration, the presence or absence of defects in the entire inspection target area of ​​the article 12 as seen from the camera 30 can be inspected without moving the article 12 and the liquid crystal type light-shielding panel relative to each other. The two-dimensional arrangement pattern of the light-shielding parts and the light-transmitting parts may be switched depending on the type or variety of the article 12. Furthermore, the liquid crystal type light-shielding panel and the article 12 may be moved relative to each other by the relative movement mechanism 14, so that two images may be taken without switching between the light-shielding parts and the light-transmitting parts. The illumination unit 20 may be a backlight of the liquid crystal panel. In a configuration using a liquid crystal type light-shielding panel that has only a light-shielding / light-transmitting switching function without a backlight, the illumination unit 20 of a surface emission type similar to that of the above embodiment may be used. The pixel size of the liquid crystal type light-shielding panel that can switch between the light-shielding parts and the light-transmitting parts may be larger than that of a liquid crystal display, and may be a liquid crystal type light-shielding panel whose pixel size is within a range of, for example, 10 to 300 square mm.

[0105] The light-transmitting portion 42 may have at least one of a shape, a size, and a position different between the front and back sides for the purpose of restricting the optical path through which light passes. A first inspection image IS1 for inspecting defect K1 and a second inspection image IS2 for inspecting defect K2 may be obtained by capturing images two or more times under different capturing conditions of the brightness (light emission intensity) of the illumination unit 20. This configuration also improves the inspection accuracy compared to conventional product inspection devices that perform inspection using only one type of inspection image captured under illumination light of one type of brightness.

[0106] In the second and third embodiments, the combination of the first inspection image IS1 and the second inspection image IS2 that the imaging control unit 51 obtains by color separating the color image may be a B image and a G image, or a B image and an R image.

[0107] The light blocking member 40 is not limited to a light blocking plate, but may be a light blocking film in which light blocking portions 41 and light transmitting portions 42 are arranged two-dimensionally and attached or formed on the surface of the illumination unit. In short, the light blocking plate may generate dark areas due to light blocking and bright areas due to light transmitting when the emitting illumination unit 20 is viewed through the light blocking member 40. The light blocking member 40 is not limited to a plate or film, but may be a sheet or film. For example, it may be a film attached to the surface of the light emitting surface of the illumination unit 20, a coating film applied to the surface of the light emitting surface, a vapor deposition film formed on the surface of the light emitting surface, a printed pattern formed on the surface of the light emitting surface, or the like.

[0108] In the first embodiment, the camera 30 may image the article 12 two or more times under imaging conditions with different brightness (light emission intensity) of the illumination unit 20. The brightness of the illumination required to give the defects K1 and K2 appropriate brightness differs for each of the defects K1 and K2. Therefore, the article 12 may be imaged under a first illumination to easily increase the brightness of the defect K1, and under a second illumination darker than the first illumination to easily decrease the brightness of the defect K2. Inspection using these two inspection images improves the detection accuracy of the defects K1 and K2.

[0109] The camera 30 may capture images two or more times under imaging conditions in which both the phase of the light and dark of the article 12 and the brightness of the illumination unit 20 are different. For example, in the first embodiment, the article 12 may be captured four times under four different imaging conditions that combine two imaging conditions with different phases and two imaging conditions with different illumination brightnesses. This may result in two types of first inspection images and two types of second inspection images being obtained.

[0110] In the first embodiment, both defects K1 and K2 are inspected, but only one of them may be inspected. For example, two types of inspection images IS1 and IS2 shown in Figures 7(a) and (b) may be used to inspect only the high-luminance defect K1. Also, two types of inspection images IS1 and IS2 may be used to inspect only the low-luminance defect K2.

[0111] In the first embodiment, only the high-brightness defect K1 may be inspected using the inspection image IS1 (Img11) shown in Fig. 8(a). Also, only the low-brightness defect K2 may be inspected using the inspection image IS2 (Img12) shown in Fig. 8(b). In these cases, each of the inspection images IS1 and IS2 is a single image, but is based on the two types of inspection images IS1 (Img1) and IS2 (Img2) shown in Fig. 7(a) and (b).

[0112] The object 12, which is the subject of the photograph, is not limited to a plastic bottle or a glass container, so long as it has a transparent or translucent part. The object 12 may be a container, for example, a laboratory container such as tableware, a cup, or a beaker. The object 12 is not limited to a container, and may be an everyday item, a glass product, a transparent synthetic resin product (such as an acrylic product), or a part. Furthermore, the object 12 may be an object that contains a transparent or translucent content in a transparent or translucent container or bag. The shape of the object 12 may be a shape that has an axis AL, or a shape that does not have an axis AL.

[0113] The article 12 is not limited to a transparent article having a transparent portion entirely, and may be partially transparent. At least a part of the transparent portion may be the inspection target. The transparent portion may be transparent or translucent as long as it has a visible light transmittance of a predetermined value or more.

[0114] In the above embodiment, the article imaging device 11 is applied to the article inspection device 10, but it may be used for purposes other than inspection. The article imaging device 11 may acquire images for the purpose of measurement, analysis, evaluation, representation, etc.

[0115] The camera 30 is not limited to a general-purpose camera, but may be a special camera such as a multiband camera or a high-speed camera. The illumination unit 20 may be a single coaxial illumination unit. The coaxial illumination unit is disposed at a position on an extension of the axis of the article 12 at the imaging position SP, and illuminates the article 12 from above or obliquely above, or from below or obliquely below.

[0116] The imaging system 100 shown in FIG. 6 may further include an illumination section 20 (second illumination section) made of a coaxial illumination unit, and a camera 30 (second camera) that images the top or bottom surface of the article 12. In this case, the coaxial illumination unit illuminates the article 12 from a position above or below the article 12. If the article 12 is a container, the camera 30 (second camera) images the top surface of the mouth 12B or the bottom surface of the container. The article inspection device 10 may inspect the mouth 12B or bottom surface of the container for defects in addition to the entire side surface of the container. [Explanation of symbols]

[0117] 10...article inspection device, 11...article imaging device, 11A...first article imaging device, 11B...second article imaging device, 11C...third article imaging device, 11D...fourth article imaging device, 12...article, 12A...body portion, 12B...mouth portion, 12I...article, 13...placement portion, 14...relative movement mechanism, 15...sensor, 20...illumination portion, 21...light-emitting portion, 30...camera, 30A...first camera, 30B...second camera, 30C...third camera, 30D...fourth camera, 30a...lens barrel, 31...lens, 3 2...infrared cut filter, 33...image sensor, 33R...R light receiving element, 33G...G light receiving element, 33B...B light receiving element, 34...color filter, 34R...R filter, 34G...G filter, 34B...B filter, 40...light shielding member, 40I...light shielding member, 41...light shielding portion, 41I...dark portion, 42...light transmitting portion, 42I...light portion, 43...light shielding portion, 44...light transmitting portion, 45...transparent member, 50...control portion, 51...imaging control portion, 52...signal processing portion, 53...image processing portion, 60... Inspection processing section, 61...first inspection processing section, 62...second inspection processing section, 65...display section, 70...transport section, 71...conveyor, 72, 73...rollers, 74...driving source, AL...axis, K1...defect, K2...defect, K1I...defect, K2I...defect, L1...bright light, L2...dark light, MD...movement direction, D1...first direction, D2...second direction, S1...imaging signal, S2...image signal, IS1...first inspection image, IS2...second inspection image, SP...imaging position, SP1...first imaging position, SP2 ...second imaging position, P1...first pitch (pitch), P2...second pitch, VA...visible light wavelength region, NIRA...near-infrared wavelength region, LS...emission spectrum of illumination light (B light), Img...image (transmitted image), Img1...first captured image (first image), Img2...second captured image (second image), Img11...dark area composite image, Img12...bright area composite image, Img21...G image, Img22...R image, Img101...captured image of comparative example, Img102...captured image of comparative example.

Claims

1. An object inspection device that captures and inspects an object having at least a portion of a transparent portion through which light can pass, An illumination unit that illuminates the object disposed at an imaging position; a camera disposed on an opposite side of the object from the illumination unit; a light-shielding member disposed between the illumination unit and the object, the light-shielding unit and the light-transmitting unit being arranged two-dimensionally by being alternately arranged in a first direction and a second direction intersecting each other; an imaging control unit that causes the camera to capture an image of transmitted light that has passed through the transparent portion of the article, thereby acquiring a plurality of types of inspection images; an inspection processing unit that inspects the article for defects based on a plurality of types of the inspection images; Equipped with The inspection processing unit is an object inspection device that performs at least one of a first inspection, which inspects for the presence or absence of defects that are brighter in dark areas, which are the image area of ​​the light-shielding part, than the dark areas, based on multiple types of inspection images, and a second inspection, which inspects for the presence or absence of defects that are brighter in bright areas, which are the image area of ​​the light-transmitting part, than the bright areas.

2. 2. The article inspection apparatus according to claim 1, The illumination unit illuminates the object with blue monochromatic light, The camera is an RGB color camera, and captures an image of transmitted light that has passed through the transparent portion of the article to obtain a color image; the plurality of types of inspection images include a first inspection image used in the first inspection and a second inspection image used in the second inspection, The imaging control unit of the product inspection device separates the color image into colors to obtain a B image or a G image as the first inspection image, and obtains one of the G image and the R image that is different from the first inspection image as the second inspection image.

3. 3. The article inspection apparatus according to claim 2, The inspection processing unit includes: detecting a high brightness portion in the dark portion that is equal to or greater than a first threshold value as the defect based on the first inspection image; An object inspection device that detects low brightness areas in the bright area that are less than a second threshold value as the defects based on the second inspection image.

4. 2. The article inspection apparatus according to claim 1, the imaging control unit acquires a plurality of types of the inspection images by imaging the object a plurality of times under imaging conditions in which the phases of the dark portion and the bright portion are different; The inspection processing unit is an item inspection device that inspects for the presence or absence of defects based on the dark areas or the bright areas of each of the multiple types of inspection images.

5. 5. The article inspection apparatus according to claim 4, an image processing unit that combines the dark areas of the respective types of inspection images into one to generate a dark area composite image, or combines the bright areas of the respective types of inspection images into one to generate a bright area composite image, The inspection processing unit is an object inspection device that inspects for the presence or absence of the defect based on the dark area composite image or the bright area composite image.

6. 5. The article inspection apparatus according to claim 4, a relative movement mechanism that moves the object and the light blocking member relative to each other in a direction that changes the phase of the dark portion and the light portion with respect to the object; The imaging control unit is an object inspection device that causes the camera to image the object two or more times at different phases.

7. 1. An article inspection method for imaging and inspecting an article having at least a portion of a transparent portion through which light can pass, comprising: An illumination unit that illuminates the object disposed at an imaging position; a camera disposed on an opposite side of the object from the illumination unit; A light-shielding member is provided between the illumination unit and the object, and has light-shielding portions and light-transmitting portions arranged two-dimensionally by being alternately arranged in a first direction and a second direction that intersect with each other, acquiring a plurality of types of inspection images by causing the camera to capture an image of transmitted light that has passed through the transparent portion of the article; performing at least one of a first inspection for inspecting the presence or absence of defects having higher brightness than a dark portion, which is an image region of the light-shielding portion, based on the plurality of types of inspection images, and a second inspection for inspecting the presence or absence of defects having lower brightness than a bright portion, which is an image region of the light-transmitting portion; 2. A method for inspecting an article, comprising:

Images