JP2020134174A - Inspection device - Google Patents

Abstract

To provide a novel inspection device capable of suppressing background reflections even when a plurality of light sources are used.SOLUTION: There is provided an inspection device for inspecting appearance of an object, the inspection device comprising: an imaging part for imaging the object by an imaging surface with a prescribed field angle; a first illumination part for illuminating a surface of the object by a first illumination light whose incidence angle is equal to or smaller than a field angle, namely a minimum diagonal incidence angle is equal to or greater than a diagonal incidence angle corresponding to the field angle; and a second illumination part for illuminating a surface of the object by a second illumination light whose maximum diagonal incidence angle is smaller than the diagonal incidence angle and the minimum diagonal incidence angle of the first illumination light. Each of the first illumination part and the second illumination part is arranged on one/the other side out of both sides sandwiching a virtual auxiliary line which passes an external end part of the imaging surface and having a similar diagonal incidence angle to the diagonal incidence angle corresponding to the field angle. A bright field image of the object from the first illumination light and a dark field image of the object from the second illumination light are used for inspecting the appearance.SELECTED DRAWING: Figure 1

Description

The present invention relates to an inspection device that inspects an object from image data obtained by irradiating the object with light.

Instead of visual inspection, an inspection device is being introduced in which an inspection object is illuminated and imaged, and inspection is performed from image data.
In particular, when inspecting coins and banknotes, there are many things to check such as scratches and color on the surface, and the scratches and characteristic parts that must be detected are small, so the illuminance of the lighting is within the irradiation range. It is required to keep the amount of light constant and to secure a sufficient amount of light.
However, in the so-called epi-illumination method in which the inspection object is illuminated from the conventional imaging device side using a half mirror or the like, the amount of light from the light source is dimmed by the half mirror and the size of the device itself is reduced. There were problems such as difficulty in converting.
On the other hand, a method of uniformly illuminating using a plurality of light sources having different incident angles is also known (see, for example, Patent Documents 1 to 6). However, in such a configuration, there is a problem that light from a plurality of places is reflected on the imaging surface as stray light.

The present invention has been made based on the above problems, and an object of the present invention is to provide a novel inspection device that suppresses glare even when a plurality of light sources are used.

The inspection device according to the present invention is an inspection device that inspects the appearance of an object, and includes an imaging unit that images the object on an imaging surface having a predetermined viewing angle, and an incident angle equal to or less than the viewing angle, that is, minimum oblique incident. The first illumination unit that illuminates the surface of the object with the first illumination light whose angle is equal to or greater than the oblique incident angle corresponding to the viewing angle, and the maximum oblique incident angle is the oblique incident angle and the minimum oblique of the first illumination light. It has a second illuminating unit that illuminates the surface of the object with a second illuminating light smaller than the incident angle, and the first illuminating unit and the second illuminating unit pass through the outer end portion of the imaging surface and said. A bright-field image of the object obtained from the first illumination light and a second illumination, which are arranged on both sides of a virtual auxiliary line having an oblique incident angle similar to the oblique incident angle corresponding to the viewing angle. It is characterized in that the appearance is inspected using a dark field image of the object obtained from light.

According to the inspection apparatus of the present invention, even when a plurality of light sources are used, reflection is suppressed and the influence of stray light is reduced.

It is a figure which shows an example of the inspection apparatus as embodiment of this invention. It is a figure which shows an example of lighting by high-angle lighting. It is a figure which shows an example of lighting by low-angle lighting. It is sectional drawing which shows an example of the inspection apparatus of this invention. It is a figure which shows an example of the path of the 1st irradiation light of the inspection apparatus shown in FIG. It is a figure which shows an example of the path of the 2nd irradiation light of the inspection apparatus shown in FIG. It is a figure which shows the example of the arrangement of the 1st diffusion part of an inspection apparatus. It is a figure which shows the positional relationship between each oblique incident angle of an inspection apparatus, and the 1st diffusion plate. It is a figure which shows the specific example of the arrangement of the 2nd diffusion part of an inspection apparatus. It is a figure which shows the specific numerical example of the arrangement of an inspection apparatus. It is a figure which shows the other embodiment of the arrangement of the inspection apparatus.

As a conceptual diagram of the first embodiment of the present invention, FIG. 1 shows an inspection device 100 including an image pickup device 10.
In the following description, the optical axis direction of the lens of the image pickup apparatus 10 is the Z direction, and of the directions perpendicular to the Z axis, the horizontal direction of the paper surface shown in FIG. 1 is the Y direction, and the direction perpendicular to the Z direction and the Y direction. Is the X direction.

The inspection device 100 includes an imaging device 10 as an imaging unit that images the work M, which is an inspection object, from the Z direction at a predetermined viewing angle θ ₁ , and a high angle that illuminates the irradiation surface P of the work M with the first illumination light L1. It has a first illumination unit 11 as illumination and a second illumination unit 12 as low-angle illumination that illuminates the irradiation surface P with the second illumination light L2.
The inspection device 100 also has an image recognition unit 20 that inspects the appearance of the work M based on the image data 50 obtained from the image pickup device 10.
The image recognition unit 20 uses the bright-field image of the work M obtained from the first illumination light L1 and the dark-field image of the work M obtained from the second illumination light L2 as the image data 50 of the work M. It has a function as an inspection unit that inspects the appearance.
Further, in the present embodiment, as shown in FIG. 4, a cover glass 30 is provided which is arranged on the imaging surface W and on which the work W is placed so that the imaging surface W can be photographed from below.

The image pickup apparatus 10 is a camera mounted in the −Z direction of the work M, and is an image pickup unit for photographing the work M from the −Z direction side to acquire image data 50.
As schematically shown in FIG. 1, the image pickup apparatus 10 photographs the image pickup surface W in a field of view with a viewing angle θ ₁ in the YZ plane. Further, the viewing angle θ ₁ is shown in FIG. 1 as an angle θ ₂ = 90 ° −θ ₁ as viewed from the imaging surface W. In this way, the angle between the incident direction of the light beam and the boundary surface is expressed as the "oblique incident angle".
Further, as will be described later, the intersection O of the lines indicating the viewing angle θ ₁ is a reference point and is shown as the position of the entrance pupil of the imaging device 10.

First, high-angle illumination by the first illumination unit 11 will be described with reference to FIG. In FIG. 2, for simplification of the description, a case where there is no cover glass 30 between the work M and the image pickup apparatus 10 and the influence of refraction, scattering, etc. can be ignored will be described.
In the auxiliary line O 'is that shown by the dashed line 2, the area where specular reflection light enters the view angle theta ₁ is an auxiliary line indicating schematically, similar to the oblique incident angle theta ₂ of the "viewing angle theta ₁ An auxiliary line having an oblique incident angle and passing through the outer end portion Q of the imaging surface W ”. The first illumination unit 11 is arranged on the −Z side of the auxiliary line O'.

The first illumination unit 11 irradiates the first illumination light L1, which is diffusive light, toward the irradiation surface P.
Of the irradiated first illumination light L1, the light beam that is specularly reflected by hitting the irradiation surface P is incident on the image pickup apparatus 10 as shown by the alternate long and short dash line in FIG.
In this case, the first illumination unit 11, regular reflection light of such first illumination light L1 is arranged to enter the viewing angle θ _1. In other words, the minimum oblique incident angle of the first illumination light L1: When the theta _4, the first illumination light L1 by the arrangement becomes θ ₂ ≦ θ ₄ is to fit the viewing angle theta ₁ of the image pickup apparatus 10 as a direct reflected light Incident in.

When the work M is arranged on the imaging surface W, the first illumination light L1 is irradiated on the work M and the specular reflection component is incident on the imaging device 10. The color, shape, size, etc. of the work M can be measured from such a normal reflection component.
The illumination using the first illumination light L1 is called "high angle illumination", and the image taken by the image pickup apparatus 10 by the high angle illumination is called "bright field image".

Next, the low-angle illumination by the second illumination unit 12 will be described with reference to FIG. As in FIG. 2, the cover glass 30 is omitted for simplification of the description.
The auxiliary line shown by the alternate long and short dash line in FIG. 3 is an auxiliary line schematically showing the region where the specular reflected light enters within the viewing angle θ ₁ as in FIG. 2, and the second illumination is on the + Z side of the auxiliary line. The part 12 is arranged. That is, the first illumination unit 11 and the second illumination unit 12 have an oblique incident angle similar to the oblique incident angle θ ₂ of the viewing angle θ ₁ , and the auxiliary line O'passing through the outer end portion Q of the imaging surface W. It is placed on both sides of the.
In FIG. 3, it is shown as the maximum oblique incident angle of the second illumination light L2: θ ₃ .

The second illumination unit 12 irradiates the second illumination light L2, which is diffusive light, toward the irradiation surface P.
The maximum oblique incident angle θ ₃ of the irradiated second illumination light L2 is set so as to satisfy θ ₂ > θ ₃ . Therefore, the specularly reflected light (directly reflected light) of the second illumination light L2 does not enter the viewing angle of the imaging device 10, but when the work M is arranged on the imaging surface W, it is on the surface of the work M. When there are scratches or irregularities, diffuse reflection occurs due to the edge portion or the inclination of the scratch, and a part of the diffusely reflected light is incident on the image pickup apparatus 10.
That is, only the edge portion of the work M is detected by the image pickup apparatus 10, and an image of such an edge portion can be obtained.
The illumination using the scattered light of the second illumination light L2 is called "low angle illumination", and the image taken by the image pickup apparatus 10 by the low angle illumination is called "dark field image".

By arranging the second illumination unit 12 in this way, of the second illumination light L2 emitted from the second illumination unit 12 to the image pickup surface W, the specularly reflected light does not enter the image pickup apparatus 10 and the work M A part of the light that is scattered or reflected by the light is incident on the image pickup apparatus 10.

As described with reference to FIGS. 2 and 3, the image pickup apparatus 10 has a brightfield image 51 obtained by the reflected light of the first illumination light L1 and a darkfield image 52 obtained by the reflected light of the second illumination light L2. And, the image data 50 including the image data 50 is acquired.
Therefore, the image pickup apparatus 10 captures the specularly reflected light of the first illumination light L1 as the bright field image 51 and the diffused light of the second illumination light L2 as the dark field image 52.
In the present embodiment, the case where the bright-field image 51 and the dark-field image 52 are individually photographed will be described, but the present invention is not limited to such a configuration. Further, in the present embodiment, the imaging surface W of the imaging device 10 and the irradiation surface P which is the high-angle imaging surface will be described as being in substantially the same range (W≈P), but the imaging surface W and the irradiation surface will be described. It does not matter if it is different from P.

FIG. 4 shows a cross-sectional view of the inspection device 100 as a specific embodiment of the present embodiment.
As shown in FIG. 4, the first illumination unit 11 includes an LED light 13 that functions as a light source, and a first diffusion plate 15 that is a first diffusion unit.
The LED light 13 and the first diffusion plate 15 are formed in a circumferential shape so as to surround the periphery of the image pickup apparatus 10, respectively, and the first diffusion plate 15 is formed from the end portion in the ± Y direction toward the center portion. It is arranged so as to incline in the −Z direction.
That is, the first diffusion plate 15 has the shape of a truncated cone with the bottom surface and the upper surface removed.
The light emitted from the LED light 13 along the Z direction is diffused in directivity by the first diffuser plate 15 and is irradiated to the irradiation surface P as the first illumination light L1 so that the illuminance becomes uniform. ..

The second illumination unit 12 includes an LED light 14 that functions as a light source, a second diffusion plate 16 that is a second diffusion unit, and a light guide element 17 that serves as a light guide path.
The light emitted from the LED light 14 along the Z direction is diffused in directivity by the second diffuser plate 16 and is irradiated to the irradiation surface P as the second illumination light L2 so that the illuminance becomes uniform. ..
The second diffusing plate 16 is an anisotropic diffusing plate that has diffusivity in the XY plane and has low diffusivity or does not cause diffusion in the plane including the Z axis. That is, the second irradiation light L2 emitted from the second diffusion plate 16 is difficult to be diffused with respect to the oblique incident angle, and the substantially circular imaging surface is irradiated so that the illuminance is uniform.
In the present embodiment, the LED lights 13 and 14 are used as the light source, but the present invention is not limited to this configuration, and various other light sources can be used.

In FIGS. 5 and 6, for each of the light rays emitted from the first illumination unit 11 and the second illumination unit 12, the maximum oblique incident angle of the second illumination light L2: θ ₃ and the minimum oblique incident of the first illumination light L1. It is shown as an angle θ ₄ . For simplification of the description, FIG. 5 shows the first illumination unit 11, and FIG. 6 shows the second illumination unit 12.

As is clear from FIG. 5, the minimum oblique incident angle of the first illumination light L1: When theta _4, the first illumination light L1 by θ ₂ ≦ θ ₄ is fit into the viewing angle theta of the imaging device 10 as a direct reflected light Incident.
In the present embodiment, the first diffusion plate 15 is arranged at an angle with respect to the irradiation surface P, so that the first diffusion plate 15 is not tentatively arranged at an angle as shown by the broken line in FIG. While reducing the size of the first diffusion plate 15 compared to the case where it is arranged parallel to the irradiation surface P), the minimum oblique incident angle θ ₄ is increased so that the conditional expression of θ ₂ ≤ θ ₄ is maintained. Is located in. By arranging the first diffusion plate 15 diagonally in this way, it is possible to secure the illumination range and reduce the size at the same time.

As shown in FIG. 6, the maximum oblique incident angle θ ₃ of the second illumination light L2 is set so as to satisfy θ ₂ > θ ₃ . Therefore, as already described, the specularly reflected light (directly reflected light) of the second illumination light L2, which is low-angle illumination, does not enter the viewing angle of the image pickup apparatus 10, but the work M is placed on the image pickup surface W. When the work M is arranged, if the surface of the work M has scratches or irregularities, diffuse reflection occurs due to the edge portion or the inclination of the scratches, and a part of the diffusely reflected light is incident on the image pickup apparatus 10.
That is, only the edge portion of the work M is detected by the image pickup apparatus 10, and a dark field image 52 for such an edge portion can be obtained.

By the way, in the case of taking a picture by low-angle illumination using the second illumination light L2 in addition to the high-angle illumination using the first illumination light L1 as described above, as shown in FIG. 7A, the second illumination is performed. It has been newly clarified that when the direct reflected light of the second illumination light L2 hits the 1 diffuser plate 15, a reflection phenomenon occurs in which the light is redistributed and enters the image pickup apparatus 10 as stray light.
In particular, as shown in the present embodiment, when the viewing angle θ ₁ of the imaging device 10 is within a predetermined range (for example, 30 ° ≤ θ ₁ ≤ 60 °) and when the viewing angle is wider, the first diffusion Since the distance between the plate 15 and the imaging surface W becomes short, there is a concern that the second illumination light L2 from the second illumination unit 12 may be diffused by the first diffusion plate 15.
That is, if the first diffuser plate 15 is simply a deep truncated cone as shown in FIG. 7 (a), the second illumination light L2 will be emitted in the low-angle side shooting using the second illumination unit 12 shown in the lower row. There is a risk that it will be diffused by the first diffuser plate 15 and become stray light.
On the other hand, when the first diffusion plate 15 is arranged parallel to the irradiation surface P as shown in FIG. 7 (c), the reflection is reflected because the distance between the first diffusion plate 15 and the second diffusion plate 16 is sufficiently widened. However, it is difficult to secure a sufficient illumination range when shooting with high-angle illumination using the first illumination unit 11.
In this embodiment, as shown in FIGS. 7 (b) and 8 in order to secure a sufficient amount of light while suppressing such a reflection phenomenon, the imaging surface is taken from the lower limit position of the first diffusion plate 15. Conditional expression (1) is satisfied when the interval to W: H and the diameter of the imaging surface W: W.
Further, as shown in FIG. 7 (c), when the first diffusion plate 15 is arranged parallel to the imaging surface W, there is a concern that the size of the inspection device 100 may increase, but FIG. 7 (b) shows. By arranging the first diffusion plate 15 diagonally as described above, the first diffusion plate 15 can be arranged compactly while maintaining the oblique incident angle, which contributes to the miniaturization of the inspection device 100. Further, since it is possible to suppress the optical path from being obstructed by the arrangement of the columns, walls, etc. for supporting the first lighting unit 11 and the second lighting unit 12, the degree of freedom of space is improved.

According to the condition equation (1) being satisfied in this way, the distance from the image pickup surface W to the image pickup device 10 and the distance from the lower limit position of the first diffusion plate 15 to the image pickup surface W are adjusted. Since it is possible to prevent the 2 illumination light L2 from hitting the first diffuser plate 15 and becoming stray light, it is possible to suppress the reflection while securing the amount of light and obtain the dark field image 52 with high accuracy.

Since the viewing angle θ ₁ of the imaging device 10 is constant, the diameter WL of the imaging surface W is a function of the distance: h from the imaging surface W to the reference point O, which is the entrance pupil of the imaging device 10.
Similarly, the minimum oblique incident angle: θ ₄ of the high-angle illumination depends on the arrangement of the first diffusion plate 15, but in the embodiment in which the first diffusion plate 15 is arranged so as to be inclined in the Z direction, it is shown as a broken line in FIG. As described above, the light beam emitted from the lowermost end toward the end portion of the irradiation surface P should have a minimum oblique incident angle: θ ₄ .
Since the irradiation surface P and the imaging surface W are substantially equal, if the distance from the irradiation surface P or the imaging surface W to the lower end of the first diffusion plate 15 is H: H, the specularly reflected light of the second illumination light L2 for low-angle illumination. The condition that does not hit the first diffusion plate 15 is that the angle formed by the line connecting the outer end Q of the field of view of the image pickup apparatus 10 and the outer end of the first diffusion portion 11 with the image pickup surface W: θα. , Formula (2) may be satisfied.

Further, as shown in FIG. 9, the first diffusion plate 15 has an angle formed with the irradiation surface P when the second illumination light L2 passes through the center of the irradiation surface P: θ _5, and is formed with the outer end of the field of view of the image pickup apparatus 10. Equation (3) is satisfied when the angle formed by the line connecting the outer end of the first diffusion plate 15 with the imaging surface W is θα.

It is more preferable that the mathematical formula (4) is satisfied.

Further, in the present embodiment, the mathematical formulas (1) and / or the mathematical formulas (3) are used so as to satisfy the mathematical formulas (1) and / or the mathematical formulas (3), and while increasing the diameter of the first diffusion plate 15. In order to be satisfied, the first diffusion plate 15 is arranged so as to surround the periphery of the image pickup apparatus 10 as a side surface shape of the truncated cone. In other words, the first diffusion plate 15 is arranged so as to be inclined with respect to the irradiation surface P.
That is, in this embodiment, the distance from the lower end of the first diffusion plate 15 to the imaging surface W: and H, when the width of the imaging surface W in the viewing angle theta ₁ was W _L, satisfying conditional expression (2) To do.
According to such a configuration, the size of the diffuser plate on the high angle side can be sufficiently secured, and as shown in FIG. 7B, the diffuser on the high angle side is diffused in the dark field image 52 on the low angle side without reducing the amount of light. The phenomenon that the board is reflected can also be suppressed.
With such a configuration, the influence of stray light is reduced by suppressing mutual reflection between the dark field and the bright field.

In such a configuration, a method of acquiring the image data 50 of the work M and inspecting the appearance of the work M will be described.

First, the inspection device 100 performs high-angle illumination using the first illumination unit 11, and photographs the irradiation surface P, which is one surface of the work M, using the image pickup device 10.
The shooting with such high-angle illumination is acquired by the image pickup apparatus 10 as a bright field image 51, and is excellent in measuring the color, shape, size, and the like of the work M.
Next, the inspection device 100 performs low-angle illumination using the second illumination unit 12 and photographs the irradiation surface P.
In shooting with such low-angle illumination, when the surface of the work M is flat, the reflection angle is the second incident angle θ ₂ , so that no reflected light should be incident on the image pickup apparatus 10. However, when the surface of the work M has scratches or irregularities, diffused reflection occurs due to the edge portion or the inclination of the scratches, and a part of the diffusely reflected light is incident on the image pickup apparatus 10.

That is, when the work M is photographed by low-angle illumination, if the surface of the work M is flat, only the edge portion of the appearance of the work M can be seen, but if there is a pattern or scratch on the surface, such a pattern or Since diffuse reflection can occur depending on the scratch, the image is taken by the image pickup apparatus 10.
That is, in low-angle illumination, the image pickup apparatus 10 functions as an unevenness detecting means. Further, the low-angle illumination is acquired by the image pickup apparatus 10 as a dark field image 52.

The image pickup apparatus 10 transmits the obtained bright-field image 51 and dark-field image 52 to the image recognition unit 20, and the image recognition unit 20 uses the bright-field image 51 and the dark-field image 52 of the work M. Inspect the appearance.

By this method, the inspection device 100 accurately obtains the appearance of the work M by using both the imaging using the high-angle illumination for detecting the color and the shape and the imaging using the low-angle illumination for detecting the pattern and scratches. inspect. In other words, the appearance of the work M is inspected using the image data 50 including the bright-field image 51 and the dark-field image 52.

By the way, in such low-angle illumination, there is a problem that the amount of light is small because most of the second illumination light L2 emitted from the second illumination unit 12 does not go to the image pickup apparatus 10.
When attempting to capture the reflected light from the low-angle illumination with such a small amount of light, the light that happens to hit the first diffuser plate 15 among the second illumination light L2 is diffused by the first diffuser plate 15 and the image pickup apparatus 10 It became clear that it would enter as stray light.

Therefore, in the present embodiment, even if the light emitted from the second illumination unit 12 irradiates the first diffuser plate 15, as described above, in order to secure the amount of light during shooting with high-angle illumination. When the second illumination light L2 passes through the center of the irradiation surface P, the angle formed with the irradiation surface P is set to θ _5, and a line connecting the outer end Q of the field of view of the image pickup apparatus 10 and the outer end of the first diffusion plate 15 is formed. When the angle formed with the irradiation surface P: θα, the arrangement is made so as to satisfy the equation (3).

By adjusting the positional relationship between the first illumination unit 11 and the second illumination unit 12 in this way, the reflection between the dark field and the bright field is suppressed and the influence of stray light is reduced.

That is, the inspection device 100 in the present embodiment is an inspection device that inspects the appearance of the work M, and has an imaging device 10 that images the work M at a predetermined viewing angle θ ₁ and an imaging device 10 having a viewing angle θ ₁ or less, that is, an incident angle. The first illumination unit 11 that illuminates the irradiation surface P with the first illumination light L1 having a maximum oblique incident angle θ ₄ having an oblique incident angle θ ₂ or more created on the irradiation surface, and a viewing angle θ _{1, that} is, an oblique incident angle θ ₂ and a maximum oblique incident angle θ _2. The appearance is inspected based on the second illumination unit 12 that illuminates the irradiation surface P with the second illumination light L2 having the minimum oblique incident angle θ ₃ smaller than the incident angle θ _4, and the image data 50 obtained from the imaging device 10. It has an image recognition unit 20 to perform the operation.
Further, the image recognition unit 20 uses the bright field image 51 of the work M obtained from the first illumination light L1 and the dark field image 52 of the work M obtained from the second illumination light L2 as the image data 50. Inspect the appearance.
According to such a configuration, it is possible to suppress the reflection of each other in the dark field and the bright field and reduce the influence of stray light.

Further, in the present embodiment, the first illumination unit 11 includes a first diffusion plate 15 for adjusting the illuminance of the first illumination light L1 so as to be uniform on the irradiation surface P, and the second illumination unit 12 includes the first diffusion plate 15. A second diffuser plate 16 for adjusting the illuminance of the second illumination light L2 so as to be uniform on the irradiation surface P is included.
With this configuration, the illuminance of the light on the irradiation surface P becomes uniform, so that the appearance of the work M can be inspected more accurately.

Further, in the present embodiment, the first diffusion plate 15 is inclined with respect to the irradiation surface P.
With such a configuration, the length of the first diffuser plate 15 can be increased, and the specularly reflected light is incident on the photographing optical system of the image pickup apparatus 10 within the viewing angle of the first illumination light L1 with respect to the irradiation surface P. As a result, the amount of light can be sufficiently secured, so that the amount of light can be easily secured especially in high-angle lighting.

Further, in the present embodiment, the angle formed by the optical axis center of the second illumination light L2 with the irradiation surface P when passing through the center of the irradiation surface P is set to θ _5, and the outer end portion Q of the field of view of the image pickup apparatus 10 and the first diffusion plate are set. Equation (3) is satisfied when the angle formed by the line connecting the outer end of 15 with the irradiation surface P: θα.

Further, in the present embodiment, the second diffusion plate 16 is an anisotropic diffusion plate that has diffusivity in the XY plane and has low diffusivity or does not cause diffusion in the plane including the Z axis. That is, the second irradiation light L2 emitted from the second diffusion plate 16 is difficult to be diffused with respect to the oblique incident angle, and the substantially circular imaging surface is irradiated so that the illuminance is uniform.
With this configuration, the second illumination light L2 irradiated to the work M is uniform in the circumferential direction, but the incident angle is unlikely to be large, so that the function of detecting patterns and scratches in low-angle illumination is not impaired. The amount of light emitted can be made uniform.

A specific numerical example having the above configuration is shown in the following numerical example 1.
The present invention is not limited to such numerical examples, and any numerical range may be taken in the contents described in the claims.

(Numerical Example 1)
As shown in FIG. 10, in the numerical embodiment 1, the distance between the image pickup device 10 and the irradiation surface P is 21 mm, the camera diameter of the image pickup device 10 is φ10 mm, and the outer diameter of the first diffusion plate 15 is φ52 mm. 1 The inclination angle between the diffusion plate 15 and the irradiation surface P is 24 °.
At this time, the imaging range of the bright field image 51 by high-angle illumination is φ32 mm, and the angle θα formed by the line connecting the outer end of the irradiation surface P and the outer end of the first diffusion portion 11 with the irradiation surface P is 18 ° or more. Is. Further, in the present numerical embodiment, in order to improve shading and light intensity as the second diffuser plate 16, an anisotropic diffuser plate having a half-value full angle of 60 ° in the circumferential direction and a half-value full angle of 1 ° in the center direction of the imaging surface W is provided. I'm using it.

Further, as long as the mathematical formula (1) is satisfied, the first illumination unit 11 and the second illumination unit 12 may be arranged in the vicinity on the extension line of the auxiliary line O'.
Specifically, as shown in FIG. 11, the first illumination unit 11 and the second illumination unit 12 may be configured to be in contact with each other on the virtual auxiliary line O'.
In such a configuration, ideally, θ ₂ = θ ₃ = θ ₄ .

Although the preferred embodiment has been described in detail above, it is not limited to the above-described embodiment, and various modifications and substitutions are made to the above-described embodiment without departing from the scope of claims. Can be added.
For example, in the present embodiment, the image recognition unit 20 is provided as an inspection unit to inspect the appearance of the object to be measured by analyzing the image data, but the inspection may be performed visually.
Further, as the first diffusion plate, not only an inclined shape but also a flat shape may be used.

10 ... Imaging unit (imaging device)
11 ... 1st lighting unit 12 ... 2nd lighting unit 15 ... 1st diffusion unit (1st diffusion plate)
16 ... 2nd diffusion part (2nd diffusion plate)
20 ... Inspection unit (image recognition unit)
50 ... Image data 51 ... Bright field image 52 ... Dark field image 100 ... Inspection device O ... Entrance pupil O'... Auxiliary line θ ₁ ... Viewing angle θ ₂ ... Viewing angle θ ₁ is viewed from the imaging surface W Angle θ ₃ ... Second oblique incident angle (maximum oblique incident angle of the second illumination light L2)
θ ₄ … First oblique incident angle (minimum oblique incident angle of the first illumination light L1)
L1 ... First illumination light L2 ... Second illumination light θ ₅ ... Angle formed by the irradiation surface P when the second illumination light L2 passes through the center of the irradiation surface P.

JP-A-2018-066590 JP-A-2018-048895 JP-A-2017-040510 WO16135910 public announcement Japanese Unexamined Patent Publication No. 2015-094642 Japanese Patent No. 6121253

Claims (7)

An inspection device that inspects the appearance of an object.
An imaging unit that images the object on an imaging surface with a predetermined viewing angle,
A first illumination unit that illuminates the surface of the object with the first illumination light whose incident angle is equal to or less than the viewing angle, that is, the minimum oblique incident angle is equal to or greater than the oblique incident angle corresponding to the viewing angle.
A second illumination unit that illuminates the surface of the object with a second illumination light whose maximum oblique incident angle is smaller than the oblique incident angle and the minimum oblique incident angle of the first illumination light.
Have,
The first illumination unit and the second illumination unit pass through the outer end of the imaging surface and are on both sides of a virtual auxiliary line having an oblique incident angle similar to the oblique incident angle corresponding to the viewing angle. Placed,
An inspection apparatus characterized in that the appearance is inspected using a bright-field image of the object obtained from the first illumination light and a dark-field image of the object obtained from the second illumination light. .. The inspection device according to claim 1.
The first illumination unit includes a first diffusion unit for adjusting the illuminance of the first illumination light so as to be uniform on the surface of the object.
The second illuminating unit is an inspection device including a second diffusing unit for adjusting the illuminance of the second illuminating light so as to be uniform on the surface of the object. The inspection device according to claim 2.
The first diffusion unit is an inspection device characterized in that it is inclined with respect to the surface of the object. The inspection device according to claim 2 or 3.
The distance from the lower end of the first diffusion portion to the imaging surface: H.
When the distance from the entrance pupil of the imaging unit to the imaging surface: h,
Conditional expression (1)
H ≧ h / 2… (1)
An inspection device characterized by satisfying. The inspection device according to any one of claims 2 to 4.
When the center of the optical axis of the second illumination light passes through the center of the surface of the object, the angle formed with the surface of the object is set to θ _5, and the outer end of the field of view of the imaging unit and the outer end of the first diffusion unit are set. When the angle formed by the line connecting with and the surface of the object is θα,
θ ₅ > 1.5 θ α ... (3)
An inspection device characterized by satisfying. The inspection device according to any one of claims 2 to 5.
An inspection device characterized in that the second diffusion unit is an anisotropic diffusion plate. The inspection device according to any one of claims 1 to 6.
An inspection device characterized in that the first lighting unit and the second lighting unit are arranged in the vicinity on an extension line of the auxiliary line.

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