JP7471533B2 - Appearance inspection device and appearance inspection method - Google Patents

Description

The present disclosure relates to an appearance inspection device and an appearance inspection method.

A defect inspection method has been proposed that includes a scanning unit that scans a sample in a horizontal plane, an illumination device that irradiates the sample with light in a linear manner, an imaging device that adjusts an aperture so as not to detect specularly reflected light and detects scattered light, and an image processing unit that compares and processes the images to determine possible defects (see, for example, Patent Document 1).

JP 2009-53132 A

Patent document 1 discloses a configuration for inspecting an object by using a linear light source to detect only scattered light, but the configuration disclosed in Patent document 1 does not necessarily improve the inspection accuracy of the object.

The object of the present disclosure is to provide an appearance inspection device or an appearance inspection method capable of improving the inspection accuracy of the object being inspected.

The appearance inspection apparatus of the present disclosure is
A visual inspection apparatus for inspecting the visual appearance of a surface of an object to be inspected, the surface shape of which is uniform in a cross section perpendicular to a stretching direction, comprising:
A light that illuminates the object to be inspected;
A lighting control unit that controls the lighting;
an imaging device for imaging the object to be inspected;
an image acquisition unit that acquires an image of the object to be inspected from the imaging device;
a quality determination unit that performs image processing on the image, determines whether the appearance of the object to be inspected is good or bad, and outputs a quality determination result;
an area where the illumination is emitted is determined to be an area where a chief ray incident on each pixel of the imaging device and specularly reflected on the object under test intersects with the chief ray incident on each pixel of the imaging device and specularly reflected on the object under test, or is determined to be an area other than an area where a chief ray incident on each pixel of the imaging device and specularly reflected on the object under test intersects with the chief ray;
The illumination light that illuminates the object under inspection is irradiated in a non-linear shape based on the surface shape of a cross section of the object under inspection perpendicular to the extension direction .
The appearance inspection method of the present disclosure includes:
A visual inspection method for inspecting the visual appearance of a surface of an object to be inspected, the surface shape of which is uniform in cross section perpendicular to a stretching direction, comprising the steps of:
illuminating the object under test with illumination;
capturing an image of the object to be inspected by an imaging device;
acquiring an image of the object to be inspected;
performing image processing on the image;
A step of determining whether the appearance of the object to be inspected is good or bad;
and outputting a pass/fail judgment result.
The illumination light emitting area is determined to be an area intersecting with a principal ray that is specularly reflected on the inspection object and enters each pixel of the imaging device, or
Alternatively, the area is determined to be outside an area intersecting a principal ray that is specularly reflected on the test object and incident on each pixel of the imaging device,
The illumination light that illuminates the object under inspection is irradiated in a non-linear shape based on the surface shape of a cross section of the object under inspection perpendicular to the extension direction .

According to the present disclosure, it is possible to provide an appearance inspection device or an appearance inspection method that can improve the inspection accuracy of the object being inspected.

1 is a diagram illustrating a schematic configuration of a visual inspection apparatus according to a first embodiment. FIG. 2 illustrates an example of a hardware configuration of a control unit. FIG. 13 is a diagram illustrating another example of a hardware configuration of the control unit. 1 is a flowchart showing an example of a visual inspection method for inspecting an object to be inspected. FIG. 2 is a diagram showing a state in which a normal portion of the surface of an object to be inspected is imaged. FIG. 13 is a diagram showing a state in which an abnormal portion on the surface of an object to be inspected is being imaged. FIG. 13 is a diagram showing a state in which a normal portion of the surface of an object to be inspected is imaged in a visual inspection device serving as a comparative example. FIG. 13 is a diagram showing a state in which an abnormal portion on the surface of an object to be inspected is imaged in a visual inspection device as a comparative example. FIG. 13 is a diagram illustrating a schematic configuration of a visual inspection apparatus as a modified example. FIG. 11 is a diagram illustrating a schematic configuration of a visual inspection apparatus according to a second embodiment. FIG. 2 is a diagram showing a state in which a normal portion of the surface of an object to be inspected is imaged. FIG. 13 is a diagram showing a state in which an abnormal portion on the surface of an object to be inspected is being imaged. FIG. 13 is a diagram illustrating a schematic configuration of a visual inspection apparatus according to a third embodiment. FIG. 13 is a diagram illustrating a schematic configuration of a visual inspection apparatus according to a fourth embodiment. FIG. 13 is a diagram illustrating a schematic configuration of a visual inspection apparatus serving as a first modification of the fourth embodiment. FIG. 13 is a diagram illustrating a schematic configuration of a visual inspection apparatus according to a second modification of the fourth embodiment. FIG. 13 is a diagram illustrating a schematic configuration of a visual inspection apparatus serving as a third modification of the fourth embodiment.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.
Embodiment 1.
The configuration of a visual inspection device 1 according to the first embodiment will be described.
FIG. 1 is a diagram illustrating a schematic configuration of a visual inspection apparatus 1 according to the first embodiment.
The appearance inspection apparatus 1 has a lighting unit 100, an illumination control unit 200, an imaging device 300, an image acquisition unit 400, and a quality determination unit 500. The appearance inspection apparatus 1 inspects the appearance of the surface of an object under inspection 600. The appearance inspection apparatus 1 can diagnose abnormalities related to the appearance of the surface of the object under inspection 600. In other words, the appearance inspection apparatus 1 can diagnose abnormalities related to the shape or state of the surface of the object under inspection 600.

The lighting 100 has a light source that emits light such as visible light, infrared light, and ultraviolet light. The lighting 100 illuminates the test object 600. In this embodiment, the lighting 100 has a light-emitting region 110. The light-emitting region 110 is also referred to as the "light-emitting region."

The lighting control unit 200 controls the lighting 100. In other words, the lighting control unit 200 is a device that controls the turning on and off of the lighting 100. Therefore, the lighting 100 emits light by being controlled by the lighting control unit 200.

The imaging device 300 captures an image of the object 600 to be inspected. For example, the imaging device 300 captures an image of the object 600 to be inspected while it is being transported. The imaging device 300 is, for example, a line camera. The imaging device 300 may be a device that uses an area camera to acquire an image using only pixels corresponding to a specific row.

The image acquisition unit 400 acquires an image of the inspected object 600 from the imaging device 300. For example, the image acquisition unit 400 controls the imaging device 300 to acquire an image of the inspected object 600. The image acquisition unit 400 can send the image of the inspected object 600 to the pass/fail judgment unit 500.

The quality determination unit 500 acquires an image of the inspected object 600 from the image acquisition unit 400. The quality determination unit 500 performs image processing on the image of the inspected object 600, determines whether the appearance of the inspected object 600 is good or bad, and outputs a quality determination result.

The object 600 to be inspected has a curved surface. The object 600 to be inspected has the same surface shape in a specific direction and is formed by multiple normal directions. The object 600 to be inspected is, for example, a handrail for an escalator, a guide rail for an elevator, a rail for a railway, a trolley, etc. In the visual inspection device 1, the object 600 to be inspected is inspected while being transported in a direction perpendicular to a cross section having the same surface shape.

The light-emitting region 110 of the illumination 100 is a region from which light is emitted from the illumination 100 toward the object under test 600. The light-emitting region 110 of the illumination 100 is determined based on the surface condition of the object under test 600 so that the imaging device 300 detects either specular reflected light or diffuse reflected light. In this embodiment, the light-emitting region 110 of the illumination 100 is determined based on the surface condition of the object under test 600 so that the imaging device 300 detects specular reflected light.

The surface condition of the test object 600 refers to, for example, the shape, such as unevenness.

That is, in this embodiment, the light-emitting region 110 of the illumination 100 is a region determined based on the surface state of the test object 600 so that the imaging device 300 detects specular reflected light and does not detect diffuse reflected light. In the example shown in FIG. 1, the light-emitting region 110 of the illumination 100 is a region where the illumination 100 intersects with the chief ray 700 that enters the pixel of the imaging device 300 when reflected by specular reflection on the test object 600. On the other hand, in the example shown in FIG. 1, the region where the illumination 100 does not intersect with the chief ray 700 that enters the pixel of the imaging device 300 when reflected by specular reflection on the test object 600 is a non-light-emitting region of the illumination 100. That is, in the example shown in FIG. 1, the imaging device 300 detects specular reflected light and does not detect diffuse reflected light.

The chief ray 700 is a ray that passes through the center of the aperture of the imaging device 300. In other words, the chief ray 700 is a ray that passes through the center of the entrance pupil of the imaging device 300. Since the chief ray 700 is light, when it enters the object under test 600, it is reflected by the object under test 600.

The lighting 100 may have a light-blocking material that blocks light from the lighting 100 (specifically, the light source). The light-blocking material is, for example, a metal material. For example, the light-blocking material is provided in an area of the lighting 100 other than the light-emitting area 110. In other words, the light-blocking material is provided in the non-light-emitting area of the lighting 100. As a result, the light-emitting area 110 of the lighting 100 is formed.

The luminous region 110 may be determined, for example, by experiment, simulation, or both. An example of a method for determining the luminous region 110 is described below.

An example of a method for determining the light-emitting region 110 through an experiment will be described. Consider dividing the light-emitting surface of the lighting 100 into N×M regions. Here, N and M are natural numbers. Next, an image of the test object 600 is acquired under conditions in which only each region of the N×M regions is illuminated. In this case, if there is a region with high brightness in the acquired image, that region is determined to be the light-emitting region 110 as it intersects with the chief ray 700. On the other hand, if the entire acquired image has low brightness, that region is excluded from the light-emitting region 110 as it does not intersect with the chief ray 700. By performing the above procedure for all N×M regions, the light-emitting region 110 in the lighting 100 can be determined.

When the light-emitting area 110 is determined by a simulation method, the light-emitting area 110 of the illumination 100 is determined, for example, by a ray tracing method. An example of a method for determining the light-emitting area 110 by simulation will be described. First, the chief ray 700 incident on the pixel of the imaging device 300 is calculated by a method such as the ray tracing method. The portion where the calculated chief ray 700 and the illumination 100 intersect is set as the light-emitting area 110.

In order to improve accuracy, the configuration may be such that shape information of the inspected object 600 is acquired. The configuration may also be such that information regarding the positional relationship between the illumination 100, the imaging device 300, and the inspected object 600 is acquired. The configuration may also be such that design information of the optical system, such as the lens design of the imaging device 300, is acquired.

An example of a method that uses both experiment and simulation will be described. In this method, the luminous region 110 is first determined by simulation. Next, an image of the inspected object 600 is acquired using the determined luminous region 110. In this case, if there are pixels for which specular reflected light has not been acquired due to differences between the calculated conditions and the actual conditions, the luminous region 110 is adjusted. By using the above procedure, the luminous region 110 can be determined with high accuracy.

FIG. 2 is a diagram showing an example of a hardware configuration of the control unit 42. As shown in FIG.
FIG. 3 is a diagram showing another example of the hardware configuration of the control unit 42. In FIG.

The lighting control unit 200, the image acquisition unit 400, and the pass/fail judgment unit 500 are, for example, configured by the control unit 42. In this case, the control unit 42 is, for example, configured by at least one processor 42a and at least one memory 42b. The processor 42a is, for example, a CPU (Central Processing Unit) that executes a program stored in the memory 42b. In this case, the functions of the lighting control unit 200, the image acquisition unit 400, and the pass/fail judgment unit 500 are realized by software, firmware, or a combination of software and firmware. The software and firmware can be stored in the memory 42b as a program. With this configuration, the program for realizing the function of the control unit 42 is executed by the computer.

Memory 42b is a computer-readable recording medium, for example, a volatile memory such as RAM (Random Access Memory) and ROM (Read Only Memory), a non-volatile memory, or a combination of volatile and non-volatile memory.

The control unit 42 may have multiple processors 42a and multiple memories 42b. In this case, the functions of the lighting control unit 200, the image acquisition unit 400, and the quality determination unit 500 are realized by these multiple processors 42a and multiple memories 42b.

The control unit 42 may be configured with a processing circuit 42c as dedicated hardware such as a single circuit or a composite circuit. The processing circuit 42c is, for example, a system LSI. In this case, the functions of the lighting control unit 200, the image acquisition unit 400, and the pass/fail determination unit 500 are realized by the processing circuit 42c.

The operation of the visual inspection device 1 and the visual inspection method for inspecting the object under inspection 600 will be described below.
FIG. 4 is a flow chart showing an example of a visual inspection method for inspecting the object under inspection 600.
In the example shown in Fig. 4, the appearance inspection method for inspecting the appearance of the surface of the inspected object 600 includes step S1 of illuminating the inspected object 600 with the illumination 100, step S2 of imaging the inspected object 600 with the imaging device 300, step S3 of acquiring an image of the inspected object 600, step S4 of performing image processing on the image acquired in step S3, step S5 of judging the quality of the appearance of the inspected object 600, and step S6 of outputting the quality judgment result. In this appearance inspection method, the area 110 emitted by the illumination 100 is determined based on the state of the surface of the inspected object 600 so that the imaging device 300 detects either specular reflected light or diffuse reflected light. In this embodiment, the area 110 emitted by the illumination 100 is determined based on the state of the surface of the inspected object 600 so that the imaging device 300 detects only specular reflected light.

The object to be inspected 600 is, for example, a cylindrical extrusion molded product. That is, the object to be inspected is a cylindrical extrusion molded product. When inspecting the object to be inspected 600, the extrusion molded product is transported, for example, in a direction perpendicular to a cross section having the same surface shape. Note that the object to be inspected 600 is not limited to a cylindrical shape, and may be an elliptical shape as long as it has the same surface shape in one direction, or the surface of the object to be inspected may simply be a curved or flat surface.

In step S1, the lighting 100 emits light by being controlled by the lighting control unit 200. The light-emitting area 110 is the area where the chief ray 700 incident on the pixel of the imaging device 300 and the lighting 100 intersect.

In step S2, the imaging device 300 is controlled by the image acquisition unit 400 to image the object to be inspected 600.

In step S3, the image acquisition unit 400 acquires an image captured by the imaging device 300.

Fig. 5 is a diagram showing a state in which an image of a normal portion of the surface of the inspection object 600 is being captured. In the example shown in Fig. 5, the entire surface of the inspection object 600 is a normal portion.
A normal portion means a portion that is manufactured as designed and has no abnormalities. In the example shown in Fig. 5, all of the chief rays 700 incident on the pixels of the imaging device 300 intersect with the light-emitting region 110. Therefore, specular reflected light is detected in all pixels of the imaging device 300, and the brightness is high.

6 is a diagram showing a state in which an image of an abnormal portion 601 on the surface of an object to be inspected 600 is being captured. In the example shown in FIG. 6, the abnormal portion 601 exists on a part of the surface of the object to be inspected 600.
The abnormal portion 601 refers to a portion that is not manufactured according to design and has irregularities or the like. In the abnormal portion 601, light rays are reflected in a direction different from that when they are incident on a normal portion, so the chief ray that is incident on the abnormal portion 601 and reaches the imaging device 300 is the chief ray 701 that does not intersect with the light-emitting region 110. Therefore, the specular reflected light is not detected in the pixels of the imaging device 300 that image the abnormal portion 601, and the luminance is low. In other words, the luminance detected by the imaging device 300 is high in normal portions and low in abnormal portions.

A comparative example will be described below.
FIG. 7 is a diagram showing a state in which a normal portion of the surface of an object to be inspected 600 is imaged in a visual inspection apparatus serving as a comparative example.
In the illumination 100 of the visual inspection apparatus as the comparative example, the entire surface facing the inspected object 600 is the light-emitting region 111. Since all of the chief rays 700 incident on the pixels of the imaging device 300 intersect with the illumination 100, specular reflected light is detected in all pixels of the imaging device 300, and the luminance becomes high.

FIG. 8 is a diagram showing a state in which an abnormal portion 601 on the surface of an object to be inspected 600 is imaged in a visual inspection apparatus as a comparative example.
Since the chief rays, including the chief ray 701 that is incident on the abnormal portion and has a reflection direction different from that in the normal portion, intersect with the illumination 100, specular reflected light is detected in all pixels of the image capture device 300, and the luminance increases. That is, in the comparative example, the luminance detected by the image capture device 300 is high even in the abnormal portion, and no difference occurs between the normal portion and the abnormal portion.

In steps S4 to S6, the pass/fail judgment unit 500 performs image processing on the image received from the image acquisition unit 400, judges whether the appearance of the inspected object 600 is pass/fail, and outputs the pass/fail judgment result.

In this embodiment, as described in Figures 5 and 6, a difference in brightness occurs between the image corresponding to the normal part and the image corresponding to the abnormal part. The pass/fail determination unit 500 uses an image processing algorithm such as a differential filter to compare surrounding pixels and determine whether a change in brightness has occurred, and can determine that the part where a change has occurred is abnormal.

In the comparative example shown in Figures 7 and 8, since there is no change in brightness between normal and abnormal parts, the pass/fail judgment unit 500 cannot judge whether the image is normal or abnormal.

Next, advantages of the visual inspection device 1 according to the first embodiment will be described.
According to this embodiment, the region 110 where the illumination 100 emits light is determined based on the surface state of the inspected object 600 so that the imaging device 300 detects only specularly reflected light. Therefore, in the image captured by the imaging device 300, normal parts have high brightness and abnormal parts have low brightness, resulting in a difference in brightness between the normal parts and the abnormal parts. As a result, the accuracy of the pass/fail judgment by the pass/fail judgment section 500 is improved, and the inspection accuracy of the inspected object 600 can be improved.

When the lighting 100 has a light-blocking material that blocks light from the lighting 100 (specifically, the light source), the light-emitting area 110 can be easily formed. For example, a light-blocking material may be attached to a ready-made lighting. In this case, the cost of the lighting 100 can be reduced.

Furthermore, when determining the light-emitting area 110 by simulation, the accuracy of the simulation can be improved and the inspection accuracy can be enhanced by adding a configuration for acquiring shape information of the object 600 to be inspected, a configuration for acquiring information regarding the positional relationship between the illumination 100, the imaging device 300, and the object 600 to be inspected, and a configuration for acquiring design information of the optical system, such as the lens design of the imaging device 300.

The light-emitting region 110 may be determined taking into account the manufacturing tolerance of the inspected object 600. This makes it possible to determine the light-emitting region 110 so that the chief ray 700 intersects with the light-emitting region 110 even if the position of the chief ray 700 varies due to the manufacturing tolerance of the inspected object 600. Therefore, even if there is a manufacturing tolerance on the surface of the inspected object 600, the brightness of the image does not change, and false detections can be reduced.

The lighting 100 may have a linear light source. This allows for lower costs for the lighting, since there are fewer light-emitting elements compared to planar lighting.

<Modification of the First Embodiment>
FIG. 9 is a diagram showing a schematic configuration of a visual inspection apparatus 1A as a modified example.
The appearance inspection apparatus 1A as a modified example differs from the appearance inspection apparatus 1 shown in FIG. 1 in that it further includes a fixing member 800. The fixing member 800 fixes the positional relationship between the illumination 100, the imaging device 300, and the object under inspection 600. As a result, the fixing member 800 can set the positional relationship between the imaging device 300, the illumination 100, and the object under inspection 600 to a preset condition. In the example shown in FIG. 9, the fixing member 800 fixes the illumination 100 and the imaging device 300. Furthermore, the fixing member 800 has a portion that contacts the object under inspection 600 at a predetermined position. As a result, the positional relationship between the imaging device 300, the illumination 100, and the object under inspection 600 can be set to a preset positional relationship.

For the portion of the fixing member 800 that comes into contact with the object under test 600, rollers or bearings may be used so as not to damage the object under test 600. The fixing member 800 may be fixed to a structure surrounding the object under test 600, and the positional relationship between the imaging device 300, the illumination 100, and the object under test 600 may be set to a predetermined condition. With this configuration, the positional relationship between the illumination 100, the imaging device 300, and the object under test 600 can be easily adjusted to a predetermined condition, and the labor costs associated with the position adjustment can be reduced.

The appearance inspection device 1A may further include a darkroom (not shown) that blocks external light. In this case, the lighting 100, the imaging device 300, and the object under inspection 600 are covered by the darkroom. With this configuration, the imaging device 300 does not detect unnecessary external light, so that the inspection accuracy can be further improved. In addition, to configure the darkroom, the entire room may be light-shielded, a dark box may be used, or the lighting 100, the imaging device 300, and the object under inspection 600 may be light-shielded by covering them with light-shielding curtains or screens.

Embodiment 2.
The configuration of a visual inspection device 2 according to the second embodiment will be described.
FIG. 10 is a diagram illustrating a schematic configuration of a visual inspection apparatus 2 according to the second embodiment.
The appearance inspection apparatus 2 has an illumination 101, an illumination control unit 201, an imaging device 300, an image acquisition unit 400, and a pass/fail determination unit 501. In the appearance inspection apparatus 2 according to the second embodiment, the illumination 101 is different from the illumination 100 of the appearance inspection apparatus 1 according to the first embodiment. Specifically, the position of the light-emitting area 112 of the illumination 101 is different from the light-emitting area 110 of the illumination 100 of the appearance inspection apparatus 1 according to the first embodiment.

The lighting 101 has a light source that emits light such as visible light, infrared light, and ultraviolet light. The lighting 101 illuminates the inspected object 600. In this embodiment, the lighting 101 has a light-emitting region 112. The light-emitting region 112 is also referred to as a "light-emitting region."

The lighting control unit 200, the imaging device 300, and the image acquisition unit 400 are the same as in embodiment 1.

The pass/fail judgment unit 501 acquires an image of the inspected object 600 from the image acquisition unit 400. The pass/fail judgment unit 501 performs image processing on the image of the inspected object 600, judges whether the appearance of the inspected object 600 is pass/fail, and outputs a pass/fail judgment result. In this embodiment, the light-emitting area 112 is different from the light-emitting area 110 in embodiment 1, so the content of the image processing does not necessarily match the content of the image processing in embodiment 1.

The light-emitting region 112 of the illumination 101 is a region where light is emitted from the illumination 101 toward the object under test 600. In this embodiment, the light-emitting region 112 of the illumination 101 is a region determined based on the surface state of the object under test 600 so that the imaging device 300 detects diffuse reflected light and does not detect specular reflected light. Specifically, the light-emitting region 112 of the illumination 101 is a region where the chief ray 700 that enters the pixel of the imaging device 300 when specularly reflected on the object under test 600 does not intersect with the illumination 101. On the other hand, in the example shown in FIG. 10, the region where the chief ray 700 that enters the pixel of the imaging device 300 when reflected by specular reflection on the object under test 600 and the illumination 100 intersect is a non-light-emitting region of the illumination 101. That is, in the example shown in FIG. 10, the imaging device 300 detects diffuse reflected light and does not detect specular reflected light.

The lighting 101 may have a light-blocking material that blocks light from the lighting 101 (specifically, the light source). The light-blocking material is, for example, a metal material. For example, the light-blocking material is provided in an area of the lighting 100 other than the light-emitting area 112. In other words, the light-blocking material is provided in a non-light-emitting area of the lighting 101. As a result, the light-emitting area 112 of the lighting 101 is formed.

The luminous region 112 may be determined, for example, by experiment, simulation, or both. An example of a method for determining the luminous region 112 is described below.

An example of a method for determining the light-emitting region 112 through an experiment is described below. The light-emitting surface of the illumination 101 is divided into N×M regions. Here, N and M are natural numbers. Next, an image of the test object 600 is acquired under conditions in which only each region of the N×M regions is illuminated. In this case, if the entire image has low brightness, that region is determined to be a light-emitting region 112, since it does not intersect with the chief ray 700. On the other hand, if there is a part of the acquired image where high brightness is obtained, that region is determined to intersect with the chief ray 700, and is excluded from the light-emitting region 112. By performing the above procedure for all N×M regions, the light-emitting region 112 in the illumination 101 can be determined.

An example of a method for determining the light-emitting region 112 by simulation will be described below. First, the chief ray 700 incident on the pixel of the imaging device 300 is calculated by a method such as a ray tracing method. The part where the calculated chief ray 700 and the illumination 101 do not intersect is determined as the light-emitting region 112.

In order to improve the accuracy of the luminous region 112, the appearance inspection device 2 may be configured to acquire shape information of the inspected object 600. The appearance inspection device 2 may be configured to acquire information regarding the positional relationship between the illumination 100, the imaging device 300, and the inspected object 600. The appearance inspection device 2 may be configured to acquire design information of the optical system, such as the lens design of the imaging device 300.

An example of a method that uses both experiment and simulation will be described. In this method, the emitting region 112 is first determined by simulation. Next, an image of the inspected object 600 is acquired using the determined emitting region 112. In this case, if there is a pixel that receives some specular reflected light due to a difference between the calculated conditions and the actual conditions, the emitting region 112 is adjusted. By the above procedure, the emitting region 112 can be determined with high accuracy.

The operation of the visual inspection device 2 and the visual inspection method for inspecting the object under inspection 600 will be described below.
4, the appearance inspection method for inspecting the appearance of the surface of the inspected object 600 includes step S1 of illuminating the inspected object 600 with the illumination 100, step S2 of imaging the inspected object 600 with the imaging device 300, step S3 of acquiring an image of the inspected object 600, step S4 of performing image processing on the image acquired in step S3, step S5 of judging the quality of the appearance of the inspected object 600, and step S6 of outputting the quality judgment result. In this embodiment, the light-emitting region 110 of the illumination 100 is determined based on the state of the surface of the inspected object 600 so that the imaging device 300 detects only diffuse reflected light.

The object 600 to be inspected is, for example, a cylindrical extrusion molded product. That is, the object to be inspected is a cylindrical extrusion molded product. When inspecting the object 600 to be inspected, the extrusion molded product is transported, for example, in a direction perpendicular to a cross section having the same surface shape.

In step S1, the illumination 101 emits light by being controlled by the illumination control unit 200. The illuminated area 112 is an area where the chief ray 700 incident on the pixel of the imaging device 300 does not intersect with the illumination 101.

In step S2, the imaging device 300 is controlled by the image acquisition unit 400 to image the object to be inspected 600.

In step S3, the image acquisition unit 400 acquires the image captured by the imaging device 300.

Fig. 11 is a diagram showing a state in which an image of a normal portion of the surface of the inspection object 600 is being captured. In the example shown in Fig. 11, the entire surface of the inspection object 600 is a normal portion.
A normal portion means a portion that is manufactured as designed and has no abnormalities. In the example shown in Fig. 11, none of the chief rays 700 incident on the pixels of the imaging device 300 intersect with the light-emitting region 112. Therefore, no specular reflected light is detected in any of the pixels of the imaging device 300, resulting in low brightness.

Fig. 12 is a diagram showing a state in which an image of an abnormal portion 601 on the surface of an object to be inspected 600 is being captured. In the example shown in Fig. 12, the abnormal portion 601 exists on a part of the surface of the object to be inspected 600.
The abnormal portion 601 means a portion that is not manufactured according to design and has irregularities or the like. In the abnormal portion 601, light is reflected in a direction different from that when it is incident on a normal portion, so the chief ray that is incident on the abnormal portion 601 and reaches the imaging device 300 is the chief ray 701 that intersects with the light-emitting region 112. Therefore, in the pixels of the imaging device 300 that image the abnormal portion 601, diffuse reflected light is detected, and the brightness becomes high. In other words, the brightness detected by the imaging device 300 is low in normal portions and high in abnormal portions.

In steps S4 to S6, the pass/fail judgment unit 501 performs image processing on the image received from the image acquisition unit 400, judges whether the appearance of the inspected object 600 is pass/fail, and outputs the pass/fail judgment result.

In this embodiment, a difference in luminance occurs between an image corresponding to a normal portion and an image corresponding to an abnormal portion. The pass/fail determination unit 500 uses an image processing algorithm such as a differential filter to compare surrounding pixels and determine whether a change in luminance has occurred, and can determine that the portion where a change has occurred is abnormal.

Next, advantages of the visual inspection device 2 according to the second embodiment will be described.
According to this embodiment, the region 112 where the illumination 101 emits light is determined based on the surface state of the inspected object 600 so that the imaging device 300 detects only diffuse reflected light. Therefore, in the image captured by the imaging device 300, normal parts have low luminance and abnormal parts have high luminance, resulting in a difference in luminance between the normal parts and the abnormal parts. As a result, the accuracy of the pass/fail judgment by the pass/fail judgment section 500 is improved, and the inspection accuracy of the inspected object 600 can be improved.

When the lighting 101 has a light-shielding material that blocks light from the lighting 101 (specifically, the light source), the light-emitting area 112 can be easily formed. For example, a light-shielding material may be attached to a ready-made lighting. In this case, the cost of the lighting 101 can be reduced.

Furthermore, when determining the light-emitting area 112 by simulation, the accuracy of the simulation can be improved and the inspection accuracy can be enhanced by adding a configuration for acquiring shape information of the object 600 to be inspected, a configuration for acquiring information regarding the positional relationship between the illumination 101, the imaging device 300, and the object 600 to be inspected, and a configuration for acquiring design information of the optical system, such as the lens design of the imaging device 300.

The light-emitting region 112 may be determined taking into consideration the manufacturing tolerance of the inspected object 600. This makes it possible to determine the light-emitting region 112 so that the chief ray 700 does not intersect with the light-emitting region 112 even if the position of the chief ray 700 varies due to the manufacturing tolerance of the inspected object 600. Therefore, even if there is a manufacturing tolerance on the surface of the inspected object 600, there is no change in the brightness of the image, and false detections can be reduced.

As in the modified example of the first embodiment, the appearance inspection device 2 may further include a darkroom that blocks external light. In this case, the illumination 101, the imaging device 300, and the object under inspection 600 are covered by the darkroom. With this configuration, the imaging device 300 does not detect unnecessary external light, thereby further improving the inspection accuracy.

Embodiment 3.
The configuration of a visual inspection device 3 according to the third embodiment will be described.
FIG. 13 is a diagram illustrating a schematic configuration of a visual inspection apparatus 3 according to the third embodiment.
The appearance inspection device 3 is composed of a lighting unit 102 , a lighting control unit 202 , an imaging device 300 , an image acquisition unit 400 , and a quality determination unit 500 .

The lighting 102 has a plurality of light-emitting elements 102A. Each light-emitting element 102A can emit visible light, infrared light, or ultraviolet light. With this configuration, the lighting 102 illuminates the test object 600. In this embodiment, the lighting 102 has a light-emitting area 113. The light-emitting area 113 is also referred to as a "light-emitting area." The lighting 102 is, for example, a display.

The lighting control unit 202 is a device that controls the turning on and off of each light-emitting element 102A of the lighting 102. That is, each of the multiple light-emitting elements 102A is controlled by the lighting control unit 202. Therefore, the lighting 102 emits light by being controlled by the lighting control unit 202.

The imaging device 300, image acquisition unit 400, and quality determination unit 500 are the same as described in embodiment 1.

The light-emitting region 113 of the illumination 102 is a region from which light is emitted from the illumination 102 toward the test object 600. Specifically, the light-emitting region 113 of the illumination 102 is a region formed by the lit light-emitting elements 102A among the multiple light-emitting elements 102A.

The light-emitting element 102A to be lit is determined based on an image of the test object 600 resulting from the lighting of the multiple light-emitting elements 102A. As a result, similar to the first embodiment, the light-emitting region 113 is determined based on the surface condition of the test object 600 so that the imaging device 300 detects specular reflected light and does not detect diffuse reflected light.

The luminous region 113 may be determined, for example, by experiment, simulation, or both. An example of a method for determining the luminous region 110 is described below.

An example of a method for determining the luminous region 113 through an experiment will be described. In this embodiment, it is possible to automate the method shown in the first embodiment. First, consider dividing the light-emitting surface of the illumination 102 into N×M regions. Here, N and M are natural numbers. Next, while switching the pixels to be illuminated in a predetermined pattern, an image of the test object 600 is acquired under conditions in which only each region of the N×M regions is illuminated. In this case, image processing is performed to check whether there is a region in the image acquired under each condition where high brightness is obtained. If there is a region where high brightness is obtained, the region is considered to cross the main ray 700 and is determined to be the luminous region 113. On the other hand, if it is confirmed by image processing that the entire acquired image has low brightness, the region is considered not to cross the main ray 700 and is excluded from the luminous region 113. By the above procedure, the luminous region 113 in the illumination 102 can be automatically determined.

Regarding the simulation method, the emitting area 113 can be determined in the manner described in embodiment 1.

The operation of the visual inspection device 3 will be described below.
The object 600 to be inspected is, for example, a cylindrical extrusion molded product. That is, the object to be inspected is a cylindrical extrusion molded product. When inspecting the object 600 to be inspected, the extrusion molded product is transported in a direction perpendicular to a cross section having the same surface shape.

The lighting 102 emits light by being controlled by the lighting control unit 202. The light-emitting area 113 is the area where the chief ray 700 incident on the pixel of the imaging device 300 and the lighting 102 intersect.

The imaging device 300 is controlled by the image acquisition unit 400 and captures an image of the object to be inspected 600.

The image acquisition unit 400 acquires the image captured by the imaging device 300.

As described in embodiment 1, the brightness detected by the imaging device 300 is high in normal areas and low in abnormal areas.

The pass/fail judgment unit 500 performs image processing on the image received from the image acquisition unit 400, judges whether the appearance of the inspected object 600 is good or bad, and outputs the pass/fail judgment result. As described in the first embodiment, the pass/fail judgment unit 500 judges whether the object is normal or abnormal using an image processing algorithm such as a differential filter, and outputs the pass/fail judgment result.

Next, advantages of the appearance inspection device 3 according to the third embodiment will be described.
The appearance inspection device 3 according to the third embodiment has the advantages described in the first embodiment.

Furthermore, according to the present embodiment, since a device capable of controlling the lighting of each light-emitting element 102A can be used as the lighting 102, custom lighting is not required. As a result, the cost of the appearance inspection device 3 can be reduced.

Furthermore, according to this embodiment, when determining the light-emitting region 113, images are acquired while changing the light-emitting elements 102A to be turned on, and it is possible to automatically determine whether each light-emitting element 102A contributes to specular reflection. Therefore, the light-emitting region 113 can be determined at low cost without performing simulations or experimental verification in which multiple light-emitting regions 113 are prepared.

In this embodiment, the light-emitting area 113 is an area determined to detect specular reflected light, but as in embodiment 2, the light-emitting area 113 may also be an area determined to detect diffuse reflected light without detecting specular reflected light.

Embodiment 4.
The configuration of a visual inspection device 4 according to the fourth embodiment will be described.
FIG. 14 is a diagram illustrating a schematic configuration of a visual inspection apparatus 4 according to the fourth embodiment.
The appearance inspection apparatus 4 includes an illumination 100 having a light-emitting region 110, an illumination control unit 200, an imaging device 300, an image acquisition unit 400, a quality determination unit 500, and a shape information acquisition unit 900. The appearance inspection apparatus 4 according to the fourth embodiment differs from the appearance inspection apparatus 1 according to the first embodiment in that it further includes the shape information acquisition unit 900. In the fourth embodiment, the light-emitting region 110 of the illumination 100 is an area determined based on information acquired by the shape information acquisition unit 900.

The shape information acquisition unit 900 acquires information regarding the shape of the surface of the inspected object 600. The area 110 emitted by the illumination 100 is determined based on the information acquired by the shape information acquisition unit 900. By acquiring information regarding the surface shape of the inspected object 600, it is possible to determine the area 110 emitted by the illumination 100 for detecting either specular reflected light or diffuse reflected light.

<First Modification of the Fourth Embodiment>
FIG. 15 is a diagram illustrating a schematic configuration of a visual inspection apparatus 5 according to a first modification of the fourth embodiment.
The appearance inspection apparatus 5 has an illumination 100 having a light-emitting area 110, an illumination control unit 200, an imaging device 300, an image acquisition unit 400, a quality determination unit 500, and a positional relationship information acquisition unit 1000. It differs from the appearance inspection apparatus 1 of the embodiment in that the positional relationship information acquisition unit 1000 is added. In the first modification of the fourth embodiment, the light-emitting area 110 of the illumination 100 is an area determined based on information acquired by the positional relationship information acquisition unit 1000.

The positional relationship information acquisition unit 1000 acquires information regarding the position of the inspected object 600. The light-emitting area 110 of the illumination 100 is determined based on the information acquired by the positional relationship information acquisition unit 1000. By acquiring information regarding the positional relationship between the illumination 100, the imaging device 300, and the inspected object 600, it is possible to determine the light-emitting area 110 of the illumination 100 for detecting either specularly reflected light or diffusely reflected light.

<Modification 2 of the fourth embodiment>
FIG. 16 is a diagram illustrating a schematic configuration of a visual inspection apparatus 6 according to a second modification of the fourth embodiment.
The appearance inspection apparatus 6 includes an illumination 100 having a light-emitting region 110, an illumination control unit 200, an imaging device 300, an image acquisition unit 400, a quality determination unit 500, and a manufacturing tolerance information acquisition unit 1100. The appearance inspection apparatus 6 differs from the appearance inspection apparatus 1 of the embodiment in that the manufacturing tolerance information acquisition unit 1100 is added. In the second modification of the fourth embodiment, the light-emitting region 110 of the illumination 100 is an area determined based on information acquired by the manufacturing tolerance information acquisition unit 1100.

The manufacturing tolerance information acquisition unit 1100 acquires information regarding the manufacturing tolerance of the inspected object 600. The light-emitting area 110 of the illumination 100 is determined based on the information acquired by the manufacturing tolerance information acquisition unit 1100. By determining the light-emitting area 110 of the illumination 100 taking into account the manufacturing tolerance information of the inspected object 600, luminance changes caused by manufacturing tolerances are prevented, and false detections can be reduced.

<Modification 3 of the fourth embodiment>
FIG. 17 is a diagram illustrating a schematic configuration of a visual inspection apparatus 7 according to a third modification of the fourth embodiment.
The appearance inspection apparatus 7 has an illumination 100 having a light-emitting area 110, an illumination control unit 200, an imaging device 300, an image acquisition unit 400, a quality determination unit 500, and an imaging device information acquisition unit 1200. It differs from the appearance inspection apparatus 1 of the embodiment in that the imaging device information acquisition unit 1200 is added. In the third modification of the fourth embodiment, the light-emitting area 110 of the illumination is an area determined based on information acquired by the imaging device information acquisition unit 1200.

The imaging device information acquisition unit 1200 acquires information about the optical system of the imaging device 300. The light-emitting area 110 of the lighting 100 is determined based on the information acquired by the imaging device information acquisition unit 1200. By acquiring information about the optical system of the imaging device 300, it is possible to determine the light-emitting area 120 of the lighting 100 for detecting only either specular reflected light or reflected light excluding specular reflected light.

The features of each embodiment and variant described above can be combined with each other.

1, 2, 3, 4, 5, 6, 7 Appearance inspection apparatus, 100, 101 Lighting, 110, 112, 113 Light-emitting area, 200, 202 Lighting control unit, 300 Imaging device, 400 Image acquisition unit, 500, 501 Pass/fail judgment unit, 600 Inspected object, 700 Chief light ray, 900 Shape information acquisition unit, 1000 Positional relationship information acquisition unit, 1100 Manufacturing tolerance information acquisition unit, 1200 Imaging device information acquisition unit.

Claims (9)

A visual inspection apparatus for inspecting the visual appearance of a surface of an object to be inspected, the surface shape of which is uniform in a cross section perpendicular to a stretching direction, comprising:
A light that illuminates the object to be inspected;
A lighting control unit that controls the lighting;
an imaging device for imaging the object to be inspected;
an image acquisition unit that acquires an image of the object to be inspected from the imaging device;
a quality determination unit that performs image processing on the image, determines whether the appearance of the object to be inspected is good or bad, and outputs a quality determination result;
an area where the illumination is emitted is determined to be an area where a chief ray incident on each pixel of the imaging device and specularly reflected on the object under test intersects with the chief ray incident on each pixel of the imaging device and specularly reflected on the object under test, or is determined to be an area other than an area where a chief ray incident on each pixel of the imaging device and specularly reflected on the object under test intersects with the chief ray;
the illumination light illuminating the object to be inspected is irradiated in a non-linear shape based on a surface shape of a cross section perpendicular to the extension direction of the object to be inspected.
Visual inspection equipment. The visual inspection device according to claim 1, wherein the area where the illumination is emitted is an area determined so that the imaging device detects specular reflected light and does not detect diffuse reflected light. The visual inspection device according to claim 1, wherein the area where the illumination is emitted is an area determined so that the imaging device detects diffuse reflected light and does not detect specular reflected light. a shape information acquiring unit that acquires information about a shape of the surface of the object to be inspected,
4. The visual inspection apparatus according to claim 1, wherein the area where the illumination is emitted is an area determined based on the information acquired by the shape information acquisition unit. a positional relationship information acquiring unit for acquiring information regarding a position of the object to be inspected,
4. The visual inspection apparatus according to claim 1, wherein the area where the illumination is emitted is an area determined based on the information acquired by the positional relationship information acquisition unit. The lighting has a light blocking material that blocks light from the lighting,
The visual inspection device according to claim 1 , wherein the light blocking material is provided in an area of the illumination other than the area where the light is emitted. The illumination has a plurality of light-emitting elements,
Each of the plurality of light-emitting elements is controlled by the illumination control unit,
The visual inspection device according to claim 1 , wherein the region illuminated by the illumination is a region constituted by light-emitting elements among the plurality of light-emitting elements that are turned on. The visual inspection device according to claim 7, wherein the light-emitting elements to be lit are determined based on the image of the object to be inspected resulting from the lighting of the plurality of light-emitting elements. A visual inspection method for inspecting the visual appearance of a surface of an object to be inspected, the surface shape of which is uniform in cross section perpendicular to a stretching direction, comprising the steps of:
illuminating the object under test with illumination;
capturing an image of the object to be inspected by an imaging device;
acquiring an image of the object to be inspected;
performing image processing on the image;
A step of determining whether the appearance of the object to be inspected is good or bad;
and outputting a pass/fail judgment result.
The illumination light emitting area is determined to be an area intersecting with a principal ray that is specularly reflected on the inspection object and enters each pixel of the imaging device, or
Alternatively, the area is determined to be outside an area intersecting a principal ray that is specularly reflected on the test object and incident on each pixel of the imaging device,
the illumination light illuminating the object to be inspected is irradiated in a non-linear shape based on a surface shape of a cross section perpendicular to the extension direction of the object to be inspected .
Visual inspection method.

Images