WO2024004729A1

WO2024004729A1 - Inspection system

Info

Publication number: WO2024004729A1
Application number: PCT/JP2023/022544
Authority: WO
Inventors: 一馬原口; 泰資田中; 翔馬高橋; 和宏山田; 康弘田中; 匠羽根田; 秋希良藤井
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2022-07-01
Filing date: 2023-06-19
Publication date: 2024-01-04

Abstract

Provided is an inspection system suppressed from increasing in size. An inspection system (200) comprises: a lighting device (30); and a camera (90). The lighting device (30) has a planar light source (10) and a color filter (20). The color filter (20) is disposed at or near the incident-side focus position (P1) of a first lens (50) with respect to inspection light. The camera (90) has a diaphragm (60) and an image sensor. The inspection light emitted from the planar light source (10) is transmitted through the color filter (20) and a half mirror (40), and enters a first surface (50a) of the first lens (50). Reflected light, which is the inspection light having been reflected on the surface of an article (300), enters the second surface (50b) of the first lens (50), is then reflected on the half mirror (40), passes through the diaphragm (60), and enters the image sensor.

Description

inspection system

The present disclosure relates to an inspection system used for visual inspection of articles.

Conventionally, configurations disclosed in Patent Documents 1 to 3 are known as illumination devices used for visual inspection of articles.

In the conventional configurations disclosed in Patent Documents 1 to 3, a light shielding filter is placed between the surface light source and the lens. Moreover, this light-blocking filter is arranged at the focal position on the incident side of the lens. By configuring the illumination device in this manner, each point on the surface of the article is irradiated with inspection light having the same illumination solid angle. This allows the illumination conditions to be the same at each point on the surface of the article. Further, as disclosed in Patent Document 2, by combining a light blocking filter and a color filter, the color distribution of reflected light can be changed depending on the direction (inclination) of the surface of the article. As a result, in an inspection system equipped with an illumination device, the direction of the surface of the article, surface irregularities, scratches, etc. can be detected with high precision.

Japanese Patent No. 5866573 Japanese Patent No. 5866586 Japanese Patent No. 6451821

In the conventional configurations disclosed in Patent Documents 1 to 3, the detection angle range of the direction on the surface of the article is determined according to the maximum value of the illumination solid angle described above.

Incidentally, in the conventional configuration, a half mirror is provided between the article and a lens that focuses the inspection light toward the article. The half mirror splits the inspection light reflected from the surface of the article and makes it incident on the camera. By arranging the half mirror at this position, the optical path of the inspection light that passes through the lens and irradiates the article becomes longer.

However, if the optical path of the inspection light after passing through the lens becomes longer, the size of the inspection system will increase. Furthermore, as the optical path becomes longer, the maximum value of the illumination solid angle becomes smaller. Therefore, it is necessary to use a lens with a large diameter. Furthermore, the size of the inspection system increases.

The present disclosure has been made in view of this point, and its purpose is to provide an inspection system in which increase in system size is suppressed.

In order to achieve the above object, an inspection system according to the present disclosure includes an illumination device that irradiates an article with inspection light, and an imaging device that captures an image of the article irradiated with the inspection light. The illumination device includes a surface light source that emits the inspection light. The inspection light is given a predetermined color distribution within a plane intersecting the traveling direction of the inspection light. The imaging device includes an aperture and an image sensor that receives light that has passed through the aperture. A half mirror and a first lens are arranged on the optical path of the inspection light traveling from the surface light source toward the article. The first lens has a first surface that is an incident surface for the inspection light, and a second surface that is an incident surface for reflected light obtained by reflecting the inspection light on the article and that faces the first surface. have The inspection light emitted from the surface light source enters the first surface of the first lens, passes through the first lens, and then is irradiated onto the article. The reflected light enters the second surface of the first lens, passes through the first lens, and then enters the imaging device.

According to the inspection system of the present disclosure, it is possible to estimate the direction of the surface of an article while suppressing an increase in the size of the system.

1 is a schematic configuration diagram of an inspection system according to Embodiment 1. FIG. FIG. 3 is a schematic plan view of a color filter. FIG. 2 is a schematic diagram showing the internal configuration of a camera. FIG. 1B is an enlarged view of a portion surrounded by a broken line in FIG. 1A. It is a schematic diagram which shows the irradiation solid angle of the inspection light irradiated to an article. FIG. 3 is a schematic diagram showing the state of reflected light when the surface of the article is tilted. FIG. 7 is a schematic diagram showing the state of reflected light when the surface of the article has a different inclination. FIG. 2 is a schematic configuration diagram of an inspection system according to a comparative example. 7 is a schematic diagram of a first lens according to modification example 1. FIG. 7 is a schematic configuration diagram of an inspection system according to a second modification. FIG. 7 is a schematic plan view of a surface light source according to modification example 2. FIG. FIG. 2 is a schematic configuration diagram of an inspection system according to a second embodiment.

Hereinafter, embodiments of the present disclosure will be described based on the drawings. Note that the following description of preferred embodiments is essentially just an example, and is not intended to limit the present disclosure, its applications, or its uses.

(Embodiment 1)
[Configuration and operation of inspection system]
FIG. 1A shows a schematic configuration diagram of an inspection system 200 according to this embodiment, and FIG. 1B shows a schematic plan view of a color filter 20 included in a lighting device 30 included in the inspection system 200. FIG. 1C schematically shows the internal configuration of the camera 90 included in the inspection system 200. FIG. 1D shows an enlarged view of the portion surrounded by the dashed line in FIG. 1A. FIG. 2 schematically shows the solid angle of irradiation of the inspection light irradiated onto the article 300. FIG. 3A schematically shows the state of reflected light when the surface of article 300 has an inclination, and FIG. 3B schematically shows the state of reflected light when the surface of article 300 has another inclination. In the following description, the optical axis direction of the inspection light may be referred to as the Z direction, and the direction in which the reflected light goes from the half mirror 40 to the camera 90 may be referred to as the X direction. A direction that intersects both the X direction and the Z direction is sometimes called the Y direction. Note that for convenience of explanation, illustration of the second housing 91 is omitted in FIG. 1C.

As shown in FIG. 1A, the inspection system 200 includes an illumination device 30, a half mirror 40, a first lens 50, a camera (imaging device) 90, a first housing 100, and a support stand 110. There is. The illumination device 30, the half mirror 40, and the first lens 50 are arranged inside the first housing 100. Note that all or part of the camera 90, for example up to the aperture 60, may be arranged inside the first housing 100.

As will be described in detail later, in the inspection system 200, an article 300 placed on a support stand 110 is irradiated with inspection light from the illumination device 30, and the reflected light reflected by the article 300 and further reflected by the half mirror 40 is detected. is imaged by the camera 90. The appearance of the article 300 is inspected based on the image captured by the camera 90.

The illumination device 30 includes a surface light source 10 and a color filter 20, and the surface light source 10 emits white planar light as inspection light.

As shown in FIG. 1A, the color filter 20 is arranged integrally with the surface light source 10. As shown in FIG. 1B, the color filter 20 includes a red filter (R filter) that transmits red light, a green filter (G filter) that transmits green light, and a blue filter (G filter) that transmits blue light. B filter)) are arranged planarly and periodically.

Note that in this specification, red light includes a wavelength of 650 nm and has a wavelength width of approximately several tens of nm to 100 nm. Green light includes a wavelength of 500 nm and has a wavelength width of approximately several tens of nm to 100 nm. Blue light includes a wavelength of 450 nm and has a wavelength width of approximately several tens of nm to 100 nm.

Note that in this embodiment, the color filter 20 is integrated with the surface light source 10, but the two may be spatially separated. In both that case and the case shown in this embodiment, the color filter 20 is located at the incident side focal position of the first surface 50a of the first lens 50 (hereinafter sometimes referred to as the first focal position P1), or It is arranged near the first focal position P1. By doing so, the inspection light emitted from the surface light source 10 and transmitted through the color filter 20 passes through the first lens 50 and then passes through the R filter, the G filter, and the B filter in a direction intersecting the traveling direction of the inspection light. Planar light has a color distribution depending on the planar arrangement of the filter. Note that the arrangement of the R filter, G filter, and B filter in the color filter 20 is not particularly limited to the example shown in FIG. 1B. Moreover, the color filter 20 may have a color filter with a color scheme other than the R filter, the G filter, and the B filter.

Note that, as shown in FIG. 1A, the distance from the first lens 50 to the first focal position P1, that is, the incident-side focal length of the first lens 50 with respect to the inspection light is f1.

The half mirror 40 is placed in the optical path of the inspection light that passes through the color filter 20 and heads toward the first lens 50. Further, the half mirror 40 is disposed in the optical path of the reflected light reflected by the article 300 after passing through the first lens 50.

The half mirror 40 further transmits the inspection light that has passed through the color filter 20, while reflecting the reflected light reflected by the article 300 toward the camera 90. In other words, the half mirror 40 irradiates the inspection light onto the article 300 and causes the reflected light from the article 300 to enter the camera 90 . Further, it is preferable that an anti-reflection structure for the inspection light is formed on the inspection light incident surface of the half mirror 40. The antireflection structure is, for example, a laminated structure in which dielectric films having different refractive indexes are alternately laminated. However, the structure is not particularly limited to this, and other structures may be adopted as appropriate.

The first lens 50 has a first surface 50a that is an incident surface for the inspection light, and a second surface 50b that is an incident surface for reflected light from the inspection light reflected by the article 300 and that faces the first surface 50a. have.

Note that the first lens 50 is a plano-convex lens, and if the radius of curvature of the first surface 50a of the first lens 50 is R1, and the radius of curvature of the second surface 50b is R2, then
R1<R2...(1)
satisfies the relationship. However, the first lens 50 of this embodiment only needs to satisfy the relationship shown in equation (2).

R1≦R2...(2)
In other words, if the power on the first surface 50a side of the first lens 50 is C1, and the power on the second surface 50b side is C2, then
|C1|≧|C2| ...(3)
satisfies the relationship. Note that the lens power C generally satisfies the relationship shown in equation (4).

|C|=|n−n0|/R...(4)
Here, n is the refractive index of the substance constituting the first lens 50, n0 is the refractive index of the internal atmosphere of the first housing 100, and R is the radius of curvature of the light exit surface of the first lens 50. In the first lens 50, the exit surface of the inspection light is the first surface 50a, and the exit surface of the reflected light is the second surface 50b.

The first lens 50 focuses the inspection light emitted from the surface light source 10 and transmitted through the color filter 20 toward the article 300. Further, the inspection light is given a predetermined irradiation solid angle IS (see FIG. 2) by passing through the first lens 50. I will discuss this further.

As shown in FIG. 1A, when the surface light source 10, the color filter 20, and the first lens 50 are arranged, the focal position is on the optical axis of the inspection light and on the exit side of the first lens 50 with respect to the inspection light. The irradiation solid angle IS at the point P3 is uniquely determined by the diameter of the optical path of the inspection light in the color filter 20 and the exit-side focal length f of the first lens 50 for the inspection light. Note that the "irradiation solid angle" referred to here refers to an arbitrarily shaped cone that has a predetermined point on the optical path of the inspection light as its apex and indicates the range in which light is irradiated to the predetermined point (for example, as shown in Fig. (see 2). When the diameter of the above-mentioned optical path is r, the plane half angle θ of the irradiation solid angle IS satisfies the relationship shown in equation (5).

θ=tan ^-1 (r/2f)...(5)
Furthermore, even if the position is away from the optical axis of the inspection light, the irradiation solid angle IS at the position away from the center of the first lens 50 by the emission side focal position of the first lens 50 with respect to the inspection light is the irradiation solid angle IS at the point P3. It has the same shape and size as the solid angle IS. Further, the irradiation solid angle IS at a position farther from the exit-side focal position of the first lens 50 for the inspection light also has the same shape and the same size as the irradiation solid angle IS at the point P3. Therefore, as shown in FIG. 2, the inspection light is irradiated so as to have the same irradiation solid angle IS at each point on the surface of the article 300. That is, the inspection light is irradiated to each point on the surface of the article 300 as parallel light having the same irradiation solid angle IS. As a result, at any point on the surface of the article 300, the illumination conditions are the same regardless of the distance from the surface light source 10. In other words, the color filter 20 and the first lens 50 constitute an image-side telecentric optical system for the inspection light.

Further, the light reflected by the article 300 enters the second surface 50b of the first lens 50, is focused by the first lens 50, is reflected by the half mirror 40, and enters the camera 90.

As shown in FIGS. 1A and 1C, the camera 90 includes an aperture 60, an objective lens 71, an imaging lens 72, an eyepiece 73, an image sensor (imaging element) 80, and a second housing 91. At least the imaging lens 72, the eyepiece lens 73, and the image sensor 80 are arranged inside the second housing 91 while maintaining a predetermined arrangement relationship with each other. In the following description, when the objective lens 71, the imaging lens 72, and the eyepiece lens 73 are described without distinction, they may be referred to as the second lens 70. Note that the image captured by the camera 90 is a color image. Therefore, the image sensor 80 is a known CMOS (Complementary Metal Oxide Semiconductor) image sensor equipped with a color filter. Further, the camera 90 may include a processor that processes the output signal of the CMOS image sensor to generate an image.

Further, the diaphragm 60 is arranged so that the camera 90 is positioned at or near the second focal position P2 of the first lens 50 for the reflected light (hereinafter sometimes referred to as the second focal position P2). is located. Note that, as shown in FIG. 1A, the distance from the first lens 50 to the second focal position P2, that is, the focal length on the emission side of the first lens 50 with respect to the reflected light is f2.

As shown in FIG. 1C, an objective lens 71 is placed on the opposite side of the image sensor 80 along the X direction with the aperture 60 in between. Furthermore, as is clear from FIGS. 1A and 1C, the objective lens 71 is disposed between the half mirror 40 and the aperture 60. Further, an imaging lens 72 and an eyepiece lens 73 are arranged between the aperture 60 and the image sensor 80. Note that the eyepiece lens 73 is arranged closer to the image sensor 80 than the imaging lens 72 is. The reflected light transmitted through the first lens 50 and reflected by the half mirror 40 passes through the aperture 60. Further, the light passes through the plurality of second lenses 70 and is received by the imaging surface of the image sensor 80.

In other words, the first lens 50 is an illumination lens that irradiates the article 300 with inspection light. Furthermore, the first lens 50 is combined with a plurality of second lenses 70 to constitute an imaging lens. This imaging lens captures an image of the article 300 generated based on the reflected light.

Furthermore, the first lens 50 and the plurality of second lenses 70 constitute an object-side telecentric optical system for reflected light.

The support stand 110 has a flat surface, and the article 300 is placed on the surface.

Next, the operating principle of the inspection system 200 will be explained.

As shown in FIG. 1A, the inspection light enters the first lens 50 with its optical axis generally along the Z direction, and is further irradiated onto the article 300. When the surface of the article 300 is flat and parallel to the surface of the support base 110, the reflected light reflected from the surface of the article 300 becomes white light. For example, the reflected light from area S1 on the surface of article 300 shown in FIG. 1D is incident on camera 90 as white light.

On the other hand, the color filter 20 has a color distribution within the plane of incidence of the inspection light. As a result, the optical axis of the test light that has passed through the R filter of the color filter 20 is slightly different in direction from the optical axis of the test light that has passed through the B filter. Further, as described above, the irradiation solid angle IS is the same at each point on the surface of the article 300. Therefore, when the surface of the article 300 is tilted, the color of the reflected light changes in accordance with the difference in the direction of the optical axis of the inspection light.

As shown in FIG. 3A, when the surface of the article 300 is tilted to the left in the paper, the inspection light that has passed through the B filter is reflected toward the imaging surface of the camera 90. On the other hand, a portion of the inspection light that has passed through the R filter is reflected away from the imaging surface of the camera 90. As a result, the image of the article 300 captured by the camera 90 has a bluish color. For example, a region S2 on the surface of the article 300 shown in FIG. 1D is imaged by the camera 90 as a bluish region.

Furthermore, as shown in FIG. 3B, when the surface of the article 300 is tilted to the right in the paper, the inspection light that has passed through the R filter is reflected toward the imaging surface of the camera 90. On the other hand, a portion of the inspection light that has passed through the B filter is reflected away from the imaging surface of the camera 90. As a result, the image of the article 300 captured by the camera 90 has a reddish color. For example, a region S3 on the surface of the article 300 shown in FIG. 1D is imaged by the camera 90 as a reddish colored region.

As explained above, according to the inspection system 200 shown in FIG. 1A, by appropriately setting the color distribution of the color filter 20, each color in the image captured by the camera 90, for example, red light, green light, and blue light, can be detected. (Hereinafter, these may be collectively referred to as RGB.) The direction (tilt) of the surface of the article 300 can be estimated from the intensity and the like. In other words, when the surface of the article 300 is composed of a plurality of surfaces whose directions are mutually determined, the direction of each surface can be estimated. Utilizing this fact, the appearance of the article 300 can be inspected. For example, it is possible to inspect the surface unevenness, presence of scratches, etc. of the article 300, which is difficult to identify only by irradiation with white light.

[Effects etc.]
As described above, the inspection system 200 according to the present embodiment includes the illumination device 30 that irradiates the article 300 with inspection light, and the camera (imaging device) 90 that images the article 300 irradiated with the inspection light. ing.

The inspection system 200 is configured to inspect the appearance of the article 300 based on the image of the article 300 captured by the camera 90. Furthermore, the inspection system 200 is configured to inspect whether or not scratches or irregularities are formed on the surface of the article 300 based on the image.

The lighting device 30 includes a surface light source 10 and a color filter 20. The surface light source 10 emits white inspection light, and the color filter 20 imparts a predetermined color distribution to the inspection light within a plane intersecting the traveling direction of the inspection light.

The color filter 20 is arranged at or near the first focal position P1, which is the incident-side focal position of the first lens 50 for the inspection light.

The camera (imaging device) 90 includes an aperture 60 and an image sensor (imaging device) 80 that receives reflected light that has passed through the aperture 60.

A half mirror 40 and a first lens 50 are arranged on the optical path of the inspection light from the surface light source 10 toward the article 300. The first lens 50 has a first surface 50a that is an entrance surface for inspection light, and a second surface 50b that is an entrance surface for reflected light and that faces the first surface 50a.

The inspection light emitted from the surface light source 10 passes through the color filter 20 and the half mirror 40 and enters the first surface 50a of the first lens 50. Furthermore, the inspection light is irradiated onto the article 300 after passing through the first lens 50 .

The reflected light from the inspection light reflected on the surface of the article 300 enters the second surface 50b of the first lens 50, passes through the first lens 50, is reflected by the half mirror 40, and enters the camera 90.

According to the present embodiment, by adjusting the arrangement of the color filters 20, parallel light having different RGB intensities in each direction can be generated and irradiated onto the article 300 as the inspection light. As a result, the direction (inclination) of the surface of the article 300 can be estimated with high accuracy based on the calibration result of the RGB intensity in the image of the article 300, and the appearance of the article 300 can be inspected. This makes it possible to inspect, for example, the presence or absence of surface irregularities or scratches on the surface of the article 300, which is difficult to identify only by irradiation with white light. Note that when the surface of the article 300 is composed of a plurality of surfaces whose directions are determined from each other, the detection range of each surface is the maximum angle formed by the central axis of the irradiation solid angle IS and the central axis of the first lens 50. It corresponds to the plane half angle θ.

Furthermore, according to the present embodiment, it is possible to suppress the size of the inspection system 200, particularly the size of the first lens 50, from increasing. This will be explained further.

FIG. 4 shows a schematic configuration diagram of an inspection system 200X according to a comparative example. The inspection system 200 of the comparative example shown in FIG. 4 differs from the inspection system 200 of the present embodiment shown in FIG. 1A in that a half mirror 40 is disposed between the first lens 51 and the article 300. Note that the first lens 51 shown in FIG. 4 is a normal biconvex lens. Further, the radius of curvature of each of the incident surface and the exit surface of the inspection light in the first lens 51 is the same value.

Furthermore, in the configuration shown in FIG. 4, the camera 90 is not provided with an aperture corresponding to the aperture 60 of this embodiment. Note that a normal in-lens diaphragm mechanism may be provided inside the camera 90, but the reflected light does not pass through the first lens 51, unlike the configurations shown in FIGS. 1A to 1D. In other words, the in-lens diaphragm mechanism is not provided at the second focal point position P2.

In the configuration shown in FIG. 4, compared to the configuration shown in FIG. 1, the optical path of the inspection light from passing through the first lens 51 to irradiating the surface of the article 300 is longer. Therefore, when the inspection light is focused on the surface of the article 300 using lenses of the same diameter, the irradiation range of the inspection light, in other words, the imaging range of the surface of the article 300 is smaller than that of the configuration shown in FIG. The configuration shown in FIG. 4 is narrower. In the configuration shown in FIG. 4, in order to widen the imaging range, it is necessary to irradiate the surface of the article 300 with inspection light using a lens with a large diameter. This, combined with the longer optical path of the inspection light, results in an increase in the size of the inspection system 200 compared to the configuration shown in FIG.

On the other hand, according to the present embodiment, the first lens 50 is disposed in the optical path of the inspection light and between the half mirror 40 and the article 300. As a result, the inspection light can be irradiated onto the necessary imaging range of the article 300 without increasing the diameter of the first lens 50 very much. Further, since the optical path of the inspection light can be shortened and the diameter of the first lens 50 can be prevented from increasing, the size of the inspection system 200 can be prevented from increasing.

Further, the aperture 60 of the camera 90 is arranged at or near the second focal position P2, which is the exit-side focal position of the first lens 50 for reflected light.

By arranging the diaphragm 60 at the above-mentioned position, the reflected light from the inspection light reflected on the surface of the article 300 can be made into parallel light and incident on the imaging surface of the camera 90. Note that in the configuration shown in FIG. 1A, an example is shown in which the camera 90 is separately provided with the diaphragm 60, but a normal in-lens diaphragm mechanism may be used instead. In that case, the in-lens diaphragm mechanism is arranged at or near the second focal position P2.

The camera 90 further includes a plurality of second lenses 70, specifically, an objective lens 71, an imaging lens 72, and an eyepiece lens 73. An objective lens 71 is arranged between the half mirror 40 and the aperture 60. An imaging lens 72 and an eyepiece lens 73 are arranged between the aperture 60 and the image sensor 80. The light reflected by the half mirror 40 passes through the aperture 60 and the plurality of second lenses 70, and is received by the image sensor 80.

In other words, the first lens 50 and the plurality of second lenses 70 constitute an imaging lens that captures an image of the article 300 generated based on reflected light. More specifically, the first lens 50 and the plurality of second lenses 70 constitute an object-side telecentric optical system for reflected light.

In this way, the reflected light is made into parallel light and incident on the imaging surface of the camera 90, that is, the imaging surface of the image sensor 80, and the optical system forming the imaging lens is a telecentric optical system. With this, even if the position of the article 300 with respect to the support base 110 is shifted in the X direction or the Y direction, the same imaging result can be obtained.

In order to obtain similar imaging results with the configuration shown in FIG. 4, it is necessary to mount an expensive telecentric lens on the camera 90. On the other hand, according to this embodiment, the camera 90 equipped with a normal lens set can be used, and the cost of the inspection system 200 can be suppressed from increasing.

Further, as described above, the first lens 50 constitutes a part of the imaging lens, and also constitutes an illumination lens that irradiates the article 300 with inspection light.

In this way, since the first lens 50 serves as both the imaging lens and a part of the illumination lens, it is possible to reduce the size of the illumination optical system and the imaging optical system in the inspection system 200, and to install these. Cost can be reduced.

When the illumination optical system and the imaging optical system are configured with separate lenses, if an attempt is made to widen the imaging range of the article 300 by increasing the irradiation angle of the inspection light, the diameter of the imaging lens will increase. . For example, if you try to obtain the same imaging range by setting the maximum value of the plane half angle θ, which is the maximum angle between the central axis of the irradiation solid angle IS and the central axis of the first lens 50, to be 20 degrees, An illumination lens having a diameter (144 mm) three times or more larger than the diameter of the lens 50 (32 mm) is required. Moreover, if an attempt is made to increase the maximum value of the plane half angle θ, the distance LWD between the second surface 50b of the first lens 50 and the article 300 cannot be ensured. When the LWD becomes short, the effective field of view of the image of the article 300 captured by the camera 90 becomes narrow. For example, if the diameter of the imaging lens is 100 mm and the maximum value of the plane half angle θ is 20 degrees, even if the irradiation direction of the inspection light is bent by 90 degrees with the half mirror 40, the LWD can only be secured to about 30 mm.

On the other hand, according to the present embodiment, since the first lens 50 serves both as an imaging lens and a part of an illumination lens, a long LWD can be ensured, and the effective field of view of the image of the article 300 captured by the camera 90 can be taken widely.

When the radius of curvature of the first surface 50a of the first lens 50 is R1, and the radius of curvature of the second surface 50b is R2,
(1/R1)≧(1/R2)...(6)
It is preferable to satisfy the following relationship.

By optically designing the first lens 50 in this manner, the uniformity of the illuminance distribution of the inspection light irradiated onto the article 300 can be increased. In addition, when (1/R1)<(1/R2), it is estimated that the reason that the uniformity of the illuminance distribution of the inspection light decreases is due to the effect of increasing the curvature of field on the exit side of the first lens 50. be done.

The color filter includes an R filter that transmits red light, a G filter that transmits green light, and a B filter that transmits blue light, which are arranged in a plane.

By doing so, it is possible to calibrate the RGB intensity in the image captured by the camera 90. Furthermore, the direction of the surface of the article 300 can be estimated based on the result. This allows the appearance of the article 300 to be inspected even when the surface of the article 300 is not flat. Furthermore, by changing the direction of the surface of the article 300, the color component of the reflected light captured by the camera 90 changes. Therefore, for example, the same inspection system 200 can perform visual inspection on a plurality of articles 300 whose reflectances have different wavelength dependencies.

Note that the color filter 20 may be a liquid crystal filter, and the surface light source 10 and the liquid crystal filter may be integrated to form a liquid crystal display. In this case, the integrated liquid crystal display is placed in the position of the color filter 20 in FIG. 1A. Note that the surface light source 10 may include a line light source that emits white light and a light diffusing plate.

<Modification 1>
FIG. 5 shows a schematic diagram of the first lens 52 according to the first modification. For convenience of explanation, in FIG. 5 and the subsequent drawings, the same parts as in Embodiment 1 are designated by the same reference numerals, and detailed description thereof will be omitted.

As long as the relationship shown in equation (3) is satisfied, the first lens 50 does not need to be a plano-convex lens. For example, as shown in FIG. 5, a first lens 52 that is an achromatic lens may be used. The first lens 52 is a combination of a biconvex lens having a first surface 52a that is an entrance surface of the inspection light, and a concave lens having a second surface 52b that is an exit surface of the inspection light. Biconvex lenses are made of a material with low dispersion, and concave lenses are made of a material with high dispersion.

Alternatively, the first lens 50 may be a biconvex lens. However, when the first lens 50 is a biconvex lens, it is preferable that |C1|>|C2|.

Further, when using the first lens 50 that satisfies the relationship shown in equation (3), the curvature of field can be reduced, but the spherical aberration becomes large. Therefore, the first lens 50 may be an aspherical lens to correct aberrations.

Note that when an achromatic lens is used as the first lens 50, the lens thickness is thicker than that of a plano-convex lens, and it is necessary to increase the diameter of the first lens 50 to obtain the same field of view. Furthermore, as the lens becomes thicker, vignetting is more likely to occur in the image of the article 300 captured by the image sensor 80.

<Modification 2>
FIG. 6 shows a schematic configuration diagram of an inspection system 200A according to modification 2, and FIG. 7 shows a schematic plan view of the surface light source 11 of the illumination device 30 included in the inspection system 200A.

The inspection system 200A shown in FIG. 6 differs from the inspection system 200 shown in FIG. 1A in that the color filter 20 is omitted and the surface light source 11 is placed in the position of the color filter 20 in FIG. 1A. . Further, as shown in FIG. 7, the surface light source 11 is different in that the surface light source 11 has a configuration in which LED (light emitting diode)

light sources

11R, 11G, and 11B are arranged in a mosaic shape. Note that the LED light source 11R emits red light. The LED light source 11G emits green light. The LED light source 11B emits blue light.

In this case, the color distribution of the inspection light emitted from the surface light source 11 is similar to the aspect shown in the first embodiment. In other words, a predetermined color distribution is provided within a plane intersecting the optical axis of the inspection light. In addition, in the surface light source 11, the arrangement relationship of the

LED light sources

11R, 11G, and 11B can be changed as appropriate. That is, in the surface light source 11, the arrangement relationship of the

LED light sources

11R, 11G, and 11B is not particularly limited to the example shown in FIG.

In the inspection system 200A of this modification, the surface light source 11 includes an LED light source 11R that is a red light source that emits red light, an LED light source 11G that is a green light source that emits green light, and a blue light source LED that emits blue light. The light source 11B is arranged and configured in a plane. Further, the surface light source 11 is disposed at or near the first focal position P1, which is the incident-side focal position of the first lens 50 for the inspection light. In other words, it can be said that the surface light source 11 and the first lens 50 constitute an image-side telecentric optical system for the inspection light.

According to this modification, the same effects as the configuration shown in Embodiment 1 can be achieved. That is, it is possible to calibrate the RGB intensity in the image captured by the camera 90. Furthermore, the direction of the surface of the article 300 can be estimated based on the result. This allows the appearance of the article 300 to be inspected even when the surface of the article 300 is not flat. Furthermore, by changing the direction of the surface of the article 300, the color components of the reflected light imaged by the camera 90 change. Appearance inspection can be performed.

(Embodiment 2)
FIG. 8 shows a schematic configuration diagram of an inspection system 200B according to the second embodiment, which differs from the inspection system 200 of the first embodiment shown in FIG. 1A in the following points.

First, the arrangement of the illumination device 30 and camera 90 is replaced with the configuration shown in FIG. 1A. Therefore, the inspection light emitted from the surface light source 10 passes through the color filter 20, is reflected by the half mirror 40, and enters the first surface 50a of the first lens 50. Furthermore, the inspection light is irradiated onto the article 300 after passing through the first lens 50 .

The reflected light from the inspection light reflected on the surface of the article 300 enters the second surface 50b of the first lens 50, passes through the first lens 50, and then passes through the half mirror 40 and enters the camera 90.

Also in this embodiment, the same effects as the configuration shown in Embodiment 1 can be achieved. That is, it is possible to calibrate the RGB intensity in the image captured by the camera 90. Furthermore, based on the results, the direction of the surface of the article 300 can be estimated. This allows the appearance of the article 300 to be inspected even if the surface of the article 300 is not flat. Furthermore, by changing the direction of the surface of the article 300, the color component of the reflected light imaged by the camera 90 changes. Appearance inspection can be performed.

In other words, the inspection system 200B of this embodiment has the following configuration. First, it includes an illumination device 30 that irradiates the article 300 with inspection light, and a camera (imaging device) 90 that images the article 300 irradiated with the inspection light.

The illumination device 30 includes a surface light source 10 and a color filter 20. The surface light source 10 emits white inspection light, and the color filter 20 imparts a predetermined color distribution to the inspection light within a plane intersecting the traveling direction of the inspection light.

The inspection light emitted from the surface light source 10 passes through the color filter 20 and enters the first surface 50a of the first lens 50. Furthermore, the inspection light is irradiated onto the article 300 after passing through the first lens 50 .

The reflected light from the inspection light reflected on the surface of the article 300 enters the second surface 50b of the first lens 50, passes through the first lens 50, and then enters the camera 90.

Note that in the configuration shown in this embodiment, the reflected light passes through the half mirror 40 and enters the camera 90. Therefore, depending on the thickness of the half mirror 40, the image of the article 300 captured by the camera 90 may be blurred due to the influence of refraction inside the half mirror 40. need to be designed.

(Other embodiments)
It is also possible to create a new embodiment by appropriately combining each component shown in Embodiments 1 and 2 and Modifications 1 and 2. For example, the first lens 52 shown in Modification 1 may be applied to inspection system 200B shown in Embodiment 2. Similarly, the surface light source 11 shown in the second modification may be applied to the inspection system 200B shown in the second embodiment.

The inspection system of the present disclosure can estimate the direction of the surface of an article while suppressing an increase in the size of the system, and is therefore useful for use in visual inspection of articles.

10, 11 Surface light source 20 Color filter 30 Illumination device 40 Half mirror 50 First lens 50a First surface 50b Second surface 51 First lens 52 First lens

52a First surface

52b Second surface 60 Aperture 70 Second lens 71 Objective Lens 72 Imaging lens 73 Eyepiece 80 Image sensor (imaging device)
90 Camera (imaging device)
91 Second housing 100 First housing 110 Support stand 200 Inspection system 300 Article θ Planar half-angle LWD Distance

Claims

An inspection system comprising: an illumination device that irradiates an article with inspection light; and an imaging device that images the article irradiated with the inspection light;
The lighting device includes:
comprising a surface light source that emits the inspection light;
The inspection light is given a predetermined color distribution in a plane intersecting the traveling direction of the inspection light,
The imaging device includes an aperture and an image sensor that receives light that has passed through the aperture,
A half mirror and a first lens are arranged on the optical path of the inspection light heading from the surface light source toward the article,
The first lens has a first surface that is an incident surface for the inspection light, and a second surface that is an incident surface for reflected light obtained by reflecting the inspection light on the article and that faces the first surface. have,
The inspection light emitted from the surface light source enters the first surface of the first lens, passes through the first lens, and then is irradiated onto the article,
In an inspection system, the reflected light enters the second surface of the first lens, passes through the first lens, and then enters the imaging device.
The inspection system according to claim 1,
In the inspection system, the aperture of the imaging device is disposed at or near a second focal position that is an exit-side focal position of the first lens for the reflected light.
The inspection system according to claim 2,
The imaging device further includes a plurality of second lenses,
The plurality of second lenses are arranged between the half mirror and the diaphragm and between the diaphragm and the image sensor,
In the inspection system, the reflected light passes through the aperture, passes through the plurality of second lenses, and is received by the image sensor.
The inspection system according to claim 3,
The first lens constitutes an illumination lens that irradiates the article with the inspection light,
Furthermore, the inspection system is characterized in that the first lens and the plurality of second lenses constitute an imaging lens that captures an image of the article generated based on the reflected light.
The inspection system according to claim 4,
The first lens and the plurality of second lenses constitute an object-side telecentric optical system for the reflected light.
The inspection system according to claim 1,
When the power of the first surface of the first lens is C1, and the power of the second surface of the first lens is C2,
|C1|≧|C2|
An inspection system that satisfies the following relationships.
The inspection system according to claim 1,
The inspection system, wherein the first lens is a plano-convex lens or an achromatic lens.
The inspection system according to claim 1,
The surface light source emits the white inspection light,
The illumination device further includes a color filter that imparts a predetermined color distribution to the inspection light in a plane intersecting the traveling direction of the inspection light,
In the inspection system, the color filter is disposed at or near a first focal position that is an incident-side focal position of the first lens for the inspection light.
The inspection system according to claim 8,
The color filter is an inspection system in which a red filter that transmits red light, a green filter that transmits green light, and a blue filter that transmits blue light are arranged in a plane.
The inspection system according to claim 1,
The surface light source includes a red light source that emits red light, a green light source that emits green light, and a blue light source that emits blue light that are arranged in a plane,
The surface light source is an inspection system, wherein the surface light source is disposed at or near a first focal position that is an incident-side focal position of the first lens for the inspection light.
The inspection system according to claim 1,
An inspection system that inspects the appearance of the article based on an image of the article captured by the imaging device.
The inspection system according to claim 11,
An inspection system that inspects whether scratches or irregularities are formed on the surface of the article based on an image of the article.