JP2002039952A - Apparatus and method for inspecting defect - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for detecting defect in which the image processing load for identifying a defect can be lessened without complicating the arrangement of the apparatus. SOLUTION: A film or sheet object 1 to be inspected is irradiated by a linear illuminator 12A from one side thereof. A line camera 11 receives transmitted light on the other side and picks up the image of the object 1. The object 1 is irradiated with light from the illuminator 12A while suppressing a light component advancing on the optical axis of the line camera 11 toward the object 1. An image processor 14 detects a colored foreign matter of the object 1 as a dark point and detects a colorless foreign matter as a bright point. Consequently, a colored foreign matter and a colorless foreign matter are detected while being discriminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a defect inspection apparatus for inspecting a defect such as a color or colorless foreign matter (fish eye) present on an inspection object such as a film or a sheet, and more particularly, to illuminating the inspection object. The present invention relates to a defect inspection apparatus that picks up an image and detects a defect existing on the inspection target from the image.

[0002]

2. Description of the Related Art Conventionally, various films and sheets made of vinyl chloride or the like have been commercialized. It is known that colored or colorless foreign matter may be mixed in these films or sheets during the manufacturing process, and that a defect called fisheye is formed. Colored foreign matter that forms this type of defect is mainly composed of carbide, and colorless foreign matter is a non-gelled resin or the like. Since defects of this kind affect the quality of products, defect inspection is performed by a defect inspection device at the final stage of the manufacturing process.

In managing the quality of films and sheets, it is necessary to detect both colorless foreign matters and colored foreign matters that form defects. Here, the degree of influence on quality differs between the colored foreign matter and the colorless foreign matter depending on the use of the product. For example, in applications such as decoration,
It suffices to detect only a defect that has a high degree of appeal to human vision. Generally, colored foreign matter is easily visible to human eyes by reflection and transmission, and colorless foreign matter is relatively hard to see in many cases. As described above, since the magnitude of the influence on the quality varies depending on the type of the foreign matter, it is usual that the defect detection condition and the quality determination condition are separately set according to the type of the foreign matter. Therefore, when a defect is inspected by detecting this kind of foreign matter, it is necessary to identify the type of foreign matter, and such a function is required for the defect inspection apparatus.

As a first prior art for inspecting this kind of defect, there is an apparatus disclosed in Japanese Patent Application Laid-Open No. 6-242022. This device comprises a linear transmission illumination device,
A position shifted in parallel from a plane including the light emitting portion and the light emitting direction of the linear transmission illumination device, and disposed at a position that does not receive transmitted light from a normal portion of the film-shaped inspection object that moves in a direction perpendicular to this surface. A line sensor and an image processing device that inputs a fisheye image on a film-like inspection object with the line sensor and distinguishes between a granular bright defect image and a crescent-shaped dark defect image. In short, the device according to the first conventional example detects two types of defects as bright spots using scattered transmission illumination, and determines whether a colored foreign substance is present depending on whether the shape of the bright spot is granular or crescent-shaped. And a colorless foreign substance.

As a second prior art, Japanese Patent Laid-Open No.
There is an apparatus disclosed in Japanese Patent No. 242023. This device is provided with a linear transmission illumination device, and a light receiving portion substantially arranged on a plane including the linear transmission illumination light emitting portion and the light emitting direction, and the resolution is set to 1/3 or less of the minimum measured object. The line sensor and the fisheye image on the moving film are input, the defect image divided into two in the moving direction and the isolated defect image are measured, the former is determined as gel, and the latter is detected as foreign matter. And an image processing apparatus that determines In short, the device according to the second conventional example detects two kinds of defects as dark spots using regular transmission illumination, and determines whether the shape is divided into two or isolated, and determines whether a colored foreign matter exists. The colorless foreign matter is identified. Then, this identification is performed in the image processing apparatus by expansion processing in the moving direction by a connectivity processing method of a one-pass method.

Further, as a third conventional technique, a technique using two series of optical systems, an optical system for irradiating diffused light and an optical system for irradiating light with high directivity, is known. According to this technique, the inspection target is irradiated with diffused light by the first-system optical system, and only the colored foreign matter is detected. Then, the inspection target is irradiated with light having high directivity by the optical system of the second system, and both colored foreign matter and colorless foreign matter are detected. Therefore, a defect detected by both systems can be identified as a colored foreign matter, and a defect detected only by the optical system of the second system can be identified as a colorless foreign matter.

FIG. 11 shows a general configuration of an optical system according to the third prior art. As shown in FIG. 1, a light source 12 is disposed on the lower surface side of the inspection object 10.
A slit plate 21 is arranged between 2 and the inspection object 10. The light emitted from the light source 12 is processed into a slit shape by the slit plate 21 and is irradiated on the lower surface side of the inspection object 10 conveyed at a constant speed. A line camera 11 is arranged on the upper surface side of the inspection target 10, receives transmitted light of the inspection target 10, and images the inspection target. As the light source 12, a fluorescent lamp is generally used.

In the optical system shown in FIG.
If the distance b between 0 and the center of the light source 12 is set to be long, for example, 200 mm or more, the inspection object 10 is irradiated with highly directional light, and this light is scattered at the defective portion. Both defects are detected as dark spots. Further, the distance b is set to, for example, 50 m by removing the slit plate 21.
When the distance is set as short as about m or less, the inspection object 10 is irradiated with diffused light, and mainly colored foreign matters are detected as dark spots. However, in this case, it is difficult to detect a colorless foreign substance. Therefore, if a series for detecting a colored foreign substance using diffused light and a series for detecting both a colored foreign substance and a colorless foreign substance using highly directional light can be used, the colored foreign substance and the colorless foreign substance can be distinguished.

In FIG. 11, the distance b between the inspection object 10 and the light source 12 and the slit width of the slit plate 21 are appropriately adjusted to change the sensitivity to colorless foreign matters, so that only one series of optical systems is used. Although it is possible to distinguish and detect a colored foreign substance and a colorless foreign substance, it is difficult to detect both a colored foreign substance and a colorless foreign substance under different detection conditions.

[0010]

SUMMARY OF THE INVENTION The above-described first and second embodiments
According to the apparatus according to the related art, in order to distinguish between a colored foreign matter and a colorless foreign matter based on the shape of a light spot or a dark spot formed by a defective portion, a defect image is once taken into an image processing device, and a defect detection process is performed. In parallel, it is necessary to identify the shape of the defective part (image recognition) from the two-dimensional image data,
There is a problem that processing in the image processing apparatus becomes complicated. In addition, according to the method according to the third related art described above, it is necessary to use two systems of optical systems in order to distinguish a colored foreign substance from a colorless foreign substance, so that the system configuration becomes complicated. There is a problem that data from different cameras must be collated to identify a defect. The present invention has been made in view of the above circumstances,
It is an object of the present invention to provide a defect inspection apparatus capable of reducing the load on image processing for identifying the type of defect without complicating the configuration of the apparatus.

[0011]

In order to solve the above-mentioned problems, the present invention has the following arrangement. That is, the defect inspection apparatus according to the present invention is a defect inspection apparatus that detects a defect existing in a film-shaped or sheet-shaped inspection target (for example, an element corresponding to an inspection target 1 described later),
Illuminating means for illuminating the inspection target from one surface side of the inspection target so that the optical image of the defect forms a bright point or a dark point according to the type of the defect based on the brightness of the formation of the inspection target (For example, lighting devices 12A, 12
B, 12C, 12D, and 12E), and
An imaging unit (for example, a component corresponding to a line camera 11 described later) that is provided on the other surface side of the inspection target and receives and captures an optical image of the defect formed by transmitted light of the inspection target; A defect detection unit (for example, a component corresponding to a host computer 13 and an image processing device 14 to be described later) for detecting the defect as a bright point or a dark point based on an image captured by the imaging unit. I do.

According to the present invention, a defect is detected as a bright spot or a dark spot depending on its type. At this time, the bright point and the dark point are distinguished based on the brightness of the formation to be inspected. That is, if the light image of the defective portion is brighter than the formation to be inspected, a bright point is formed, and if it is darker than the formation to be inspected, a dark point is formed. The formation of a bright spot or a dark spot is performed using, for example, refracted light at a defective portion and diffused light from another normal portion (formation portion).

Here, when the defect is caused by a colorless foreign matter, light from the illumination means is refracted (including diffusion and scattering) at the defect part, and refracted light toward the imaging means is generated. As a result, the defective portion becomes brighter than the formation portion, and a bright spot is formed. Also, if the defect is due to colored foreign matter,
As a result of the light from the illuminating means being absorbed by the defect, the defect becomes darker than the formation and a dark spot is formed. The light spot or dark spot thus formed is detected by the defect detecting means, and the defect is detected as a light spot or a dark spot. Here, whether a defect is detected as a bright point or a dark point is determined according to the type of the defect as described above. Therefore, the type of the defect (colorless foreign matter or colored Foreign matter) can be identified.

Further, the defect inspection apparatus according to the present invention comprises:
For example, the illumination unit may illuminate the inspection target while suppressing light emission toward the inspection target along the optical axis of the imaging unit (for example, illumination devices 12A and 1 described below).
2B).

According to this configuration, the light incident on the imaging position on the inspection object is dominantly incident from a direction other than the optical axis of the imaging means. Further, by suppressing light traveling toward the inspection target along the optical axis of the imaging unit, the brightness of the formation of the inspection target is set between a bright point and a dark point. Here, when the defect due to the colorless foreign matter is at the photographing position, the light incident on the defective portion is refracted, and a light component traveling from the defective portion to the imaging means is generated. As a result, the defective portion becomes relatively brighter than the surrounding formation, and a bright spot is formed.
When a defect due to a colored foreign matter is present at the photographing position, light incident on the defective portion is absorbed by the foreign matter. As a result, the defective portion becomes relatively darker than the surrounding formation portion, and a dark spot is formed.

After all, a bright spot or a dark spot is formed depending on the type of the defect. In short, the present invention provides a method of appropriately controlling the amount of light emitted toward an imaging position and illuminating the light, so that the brightness of the formation to be inspected is set between a bright point and a dark point, and the type of defect is adjusted according to the type of defect. A bright point or a dark point is formed depending on the intensity of the refracted light generated by the light. Therefore, for example, it is possible to detect a defect existing in an inspection target having a relatively high light transmittance.

Further, in the defect inspection apparatus according to the present invention, for example, the illuminating means may be configured such that the brightness of the formation of the object to be inspected is within a range between the bright point and the dark point. The method is characterized in that the inspection target is illuminated along with the light traveling toward the inspection target along the optical axis (for example, components corresponding to the functions of lighting devices 12C, 12D, and 12E described later).

According to this configuration, the light incident on the object to be inspected is dominantly incident from a direction other than the optical axis direction of the imaging means. Further, by generating light heading along the optical axis of the imaging means toward the imaging position on the inspection target, and illuminating the inspection target along with this light component, the brightness of the formation of the inspection target is changed to a bright point and a dark point. Set between Here, when the defect due to the colorless foreign matter is at the photographing position, the light incident on the defective portion is refracted, and a light component traveling from the defective portion to the imaging means is generated. As a result, the defective portion becomes relatively brighter than the surrounding formation, and a bright spot is formed. Further, when a defect due to a colored foreign matter is present at the photographing position, light incident on the defective portion is absorbed by the colored foreign matter. As a result, the defective portion becomes relatively darker than the surrounding formation portion, and a dark spot is formed. Eventually, a bright spot or a dark spot is formed depending on the type of defect.

In short, the present invention sets the brightness of the formation of the inspection object between the bright point and the dark point by appropriately generating the amount of light emitted toward the inspection object along the optical axis of the imaging means. A bright spot or a dark spot is formed based on the intensity of refracted light generated depending on the type of defect.
Therefore, for example, it is possible to detect a defect existing in an inspection target having a relatively low light transmittance.

Still further, in the defect inspection apparatus according to the present invention, the illumination means may include, for example, a light source (for example, a component corresponding to a light source 12A-1 to be described later) disposed on an optical axis of the imaging means, A light-shielding unit (e.g., a light-shielding tape 12A-2 described later) that is disposed between the imaging position and the light source and that shields light emitted from the light source toward the inspection object along the optical axis of the imaging unit. Corresponding components).

According to this configuration, the light traveling toward the inspection object along the optical axis of the photographing means is shielded, and light is incident on the inspection object from a direction other than the optical axis of the imaging means, and a part of the light is diffused. . Therefore, even if the inspection target is a material having a large light transmittance, the brightness of the formation of the inspection target can be set to an appropriate brightness between the bright point and the dark point, and the brightness of the formation portion can be reduced. It is possible to form a light point and a dark point as a reference.

Still further, in the defect inspection apparatus according to the present invention, the illuminating means may include, for example, two light sources (for example, two light sources arranged in the vicinity of the optical axis of the imaging means via a gap located on the optical axis). (Equivalent to light sources 12B-1 and 12B-2 to be described later).

According to this configuration, there is no light traveling toward the inspection object along the optical axis of the photographing means, and light is incident on the inspection object from a direction other than the optical axis of the imaging means and is partially diffused. You. Therefore, even if the inspection target is a material having a large light transmittance, the brightness of the formation of the inspection target can be set to an appropriate brightness between the bright point and the dark point, and the brightness of the formation portion can be reduced. It is possible to form a light point and a dark point as a reference.

Further, in the defect inspection apparatus according to the present invention, for example, the illuminating means may include a first light source (for example, a light source 12 to be described later) disposed near an optical axis of the imaging means.
C-1), disposed between the first light source and the test object, and diffusing light emitted from the first light source to perform the test along the optical axis of the imaging unit. A light diffusing plate (for example, a component corresponding to a light diffusing plate 12C-3 described later) that forms a light component heading for the object, and a light diffusing plate that is arranged near an optical axis of the image pickup means and illuminates an image pickup position on the inspection object. And a second light source (e.g., a component corresponding to a light source 12C-2 described later).

According to this configuration, the light emitted from the first light source is diffused by the light diffusion plate and irradiated to the imaging position, so that light is generated along the optical axis of the imaging means toward the inspection object. The required amount is ensured, and even if the light transmittance of the inspection target is low, the brightness of the formation of the inspection target is maintained between the bright point and the dark point. Here, when the defect is caused by a colorless foreign matter, light from the second light source is incident on the defective portion, is refracted by the defective portion, and travels toward the image pickup means to form a bright spot. If the defect is caused by a colored foreign substance, the second
The light incident on the defect from the light source is absorbed to form a dark spot. Therefore, even if the inspection target is a material having a low light transmittance, it is possible to increase the brightness of the formation of the inspection target between the bright point and the dark point, and to detect a defect as a bright point or a dark point. Becomes possible.

Further, in the defect inspection apparatus according to the present invention, for example, the illuminating means is disposed near the optical axis of the imaging means and illuminates the inspection object (for example, light sources 12D-1 and 12D-1 to be described later). 12D-2), and a light diffusion plate arranged on the optical axis to diffuse light emitted from the light source to form a light component toward the inspection object along the optical axis of the imaging unit. (For example, a component corresponding to a light diffusion plate 12D-3 described later).

According to this structure, the light emitted from the light source of the illuminating means is diffused by the light diffusing plate and is radiated to the imaging position, so that the generation of light heading for the inspection object along the optical axis of the imaging means. Only the required amount is secured, and the brightness of the formation to be inspected is kept between the light point and the dark point. Here, when the defect is caused by a colorless foreign matter, light from the light source of the illumination means enters the defect part, is refracted by the defect part, and travels toward the image pickup means to form a bright spot. When the defect is caused by a colored foreign matter, light incident on the defect from the light source is absorbed, and a dark spot is formed. Therefore, even if the inspection target is a material having a low light transmittance, it is possible to increase the brightness of the formation of the inspection target to between the bright point and the dark point,
Defects can be detected as bright spots or dark spots.

Further, in the defect inspection apparatus according to the present invention, for example, the illuminating means is disposed near the optical axis of the imaging means and illuminates the inspection object (for example, a light source 12E-1, 12E-2), disposed on the optical axis on the opposite side of the light source from the inspection target, and scatters and reflects the light emitted from the light source along the optical axis. A scattering reflection plate (for example, a light reflection plate 12E-
3).

According to this configuration, the light emitted from the light source is scattered and reflected by the light reflecting plate and is irradiated to the imaging position, so that the amount of light directed toward the inspection object along the optical axis of the imaging means is reduced. , And the brightness of the formation to be inspected is kept between the light point and the dark point. Here, when the defect is caused by a colorless foreign matter, light from the light source of the illumination means enters the defect part, is refracted by the defect part, and travels toward the image pickup means to form a bright spot. When the defect is caused by a colored foreign matter, light incident on the defect from the light source is absorbed, and a dark spot is formed. Therefore, even if the inspection target is a material having a low light transmittance, it is possible to increase the brightness of the formation of the inspection target between the bright point and the dark point, and to detect a defect as a bright point or a dark point. Becomes possible.

A defect judging means for judging the type of the defect based on whether the defect detected by the defect detecting means is a bright point or a dark point (for example, an element corresponding to a function of the host computer 13 described later) ) May be further provided.

According to the defect inspection method of the present invention, there is provided an illumination device for illuminating a film or sheet to be inspected from one surface side, and a line provided on the other surface side of the inspection object to receive transmitted light of the inspection object. In a defect inspection method for detecting a defect present in the inspection object by a camera and a line image processing device for processing a signal from the line camera, an optical image of the defect based on the brightness of the formation of the inspection object is used as a reference. Illuminates the inspection object with the illumination device by suppressing the amount of light on the optical axis of the line camera so that a light spot or a dark spot is formed depending on the type of the defect, and the defect is a light point or It is characterized in that it is detected as a dark spot. The type of the defect may be identified based on whether the defect is detected as a bright spot or a dark spot.

In short, the present invention keeps the brightness level of the formation to be inspected at an appropriate level, and uses both light point detection and dark point detection. This makes it possible to distinguish between a colored foreign substance and a colorless foreign substance without making a determination by image processing, while adopting a simple system configuration, and it is possible to detect each foreign substance under different conditions.

[0033]

Next, an embodiment of the present invention will be described. <First Embodiment> FIG. 1 shows an overall configuration of a defect inspection apparatus according to a first embodiment of the present invention. This defect inspection apparatus is intended for inspecting a film or a sheet having a certain high light transmittance, and as shown in FIG. 1, a film- or sheet-like inspection object 1 is inspected from a lower surface side (one surface side). A lighting device 12A that illuminates, a line camera 11 that receives light transmitted through the inspection target 1 and captures an image of the inspection target 1 from the upper surface side (the other surface side), and a signal level from the line camera 11 indicating a normal part (defect). The image processing device 14 extracts a portion having a difference of not less than a predetermined value from the signal level of the point of interest as a defective portion, as compared with the signal level of the portion where no is present).
And a host computer 13 that processes and outputs information related to the defective portion detected by the image processing device 14.

Here, the inspection object 1 is a film or a sheet made of, for example, vinyl chloride, PET, PP, acrylic, or nylon, and is conveyed at a constant speed so as to pass near above the lighting device 12A. . Inspection object 1
The film or sheet may have been subjected to processing such as adhesive for bonding, coating or vapor deposition for enhancing barrier properties, and it transmits a small amount of light from transparent to translucent. Any material having properties may be used.

The line camera 11 is for taking an image of the inspection object 1 conveyed at a constant speed from the upper side.
An imaging device (not shown) arranged in a line is provided, and the imaging position is fixed by focusing on the inspection object 1 to be transported. The line camera 11 includes a line CCD (C
Harge Coupled Device) cameras are typical, but a MOS type camera, a camera in which photodiodes are arranged in a line, or the like can also be used. Line camera 1
The lens 1 is provided with a lens or the like for forming a light image of the inspection target 1 as an imaging target on the imaging device.

The illumination device 12A includes a linear light source 12A-1 such as a high frequency lighting fluorescent lamp, and is arranged so as to extend in the width direction of the inspection target 1 and illuminate the inspection target 1. In addition, a light source using a combination of a halogen lamp or the like and a linear optical fiber light guide or a light source using a combination of a halogen lamp or the like and a long rod may be used as the light source. Hereinafter, the lighting device 12 </ b> A
A description will be given assuming that a high frequency lighting fluorescent lamp is provided as A-1.

FIG. 2 shows a line camera 11 and a lighting device 12.
2 shows a configuration of an optical system including the optical system A. As shown in the figure, the light source 12A-1 of the illumination device 12A is arranged on the optical axis J of the line camera 11. Here, the line camera 11
Is the optical axis J of the line camera 1 from the light source of the illumination device 12A.
1 represents the optical path of light incident straight on
This is a line connecting the line camera 11 and the center of the light source 12A-1. In the example shown in FIG. 1, since the light source 12A-1 is a linear fluorescent lamp, the optical axis J forms a fan-shaped (triangular) surface having the line camera 11 as the vertex as shown in FIG. .

A light-shielding tape 12A-2 is attached to the linear light source 12A-1 along the longitudinal direction, and the light source 12A-1 is moved from the light source 12A-1 to the inspection object 1 on the optical axis J of the line camera 11. It is configured to block light components emitted toward the light source. Therefore, this lighting device 12A
The inspection target 1 is illuminated in a state where the amount of light emitted toward the line camera 11 along the optical axis J of the line camera 11 is suppressed.

In this example, the tape 12A for shielding light is used.
-2 is attached to the light source 12A-1, but the invention is not limited thereto, and a light shielding member may be arranged at an appropriate position between the light source and the inspection target. Even when a long rod is used as the light source, the same light shielding method as that of the high frequency lighting fluorescent lamp is possible.

The principle of the defect inspection apparatus according to the first embodiment will be described below with reference to FIGS. According to the illumination device 12A according to the first embodiment, light emitted from the light source 12A-1 toward the inspection target 1 on the optical axis J of the line camera 11 is shielded, and is not covered with the light shielding tape 31. Light from a light source enters an imaging position existing on an optical axis J. As a result, as shown in FIGS. 3A and 3B, light L0 incident on the inspection target 1 from a direction other than the optical axis J of the line camera 11 becomes dominant.

Here, as shown in FIG. 5A, when light L0 emitted from the illumination device 12A enters the normal part of the inspection object 1, most of the light L0 is transmitted to become transmitted light L1, and Light L that is partially diffused and travels to line camera 11
It becomes 2. The light L2 diffused in the normal portion gives the brightness of the formation of the inspection target 1.

Next, the inspection object 1 is transported, and FIG.
As shown in (1), when a defective portion due to the colorless foreign matter Dm comes to the imaging position, the light L0 from the illuminating device 12A is scattered by the defective portion into lights L11, L12, and L13, and the line camera 1
A relatively large light L12 is generated as the light component heading for 1. As a result, the defective portion becomes brighter than the formation portion, and a bright spot is formed. That is, a defect due to the colorless foreign matter Dm forms a bright spot.

Next, with reference to FIG. 4, the light component traveling from the defective portion to the line camera 11 will be compared between a case where the defect is caused by a colorless foreign matter and a case where the defect is caused by a colored foreign matter. First, as shown in FIG. 3A, when the defect is caused by the colored foreign matter Dy,
Most of the light L0 incident on the defect from the illumination device 12A is absorbed by the colored foreign matter Dy. For this reason, the light component L12 (Dm) traveling from the defective portion to the line camera 11 decreases, and the brightness of the defective portion decreases more than that of the formation portion. That is,
Defects due to colored foreign matter form dark spots. On the other hand, as shown in FIG. 3B, when the defect is caused by the above-described colorless foreign matter Dm, most of the light L0 from the illumination device 12A is refracted (diffused or scattered) at the defect portion, and the light component L12 is reduced. As a result, the bright spot is formed as described above.

As shown in FIG. 4A, in the case of a defect caused by the colored foreign matter Dy, optical distortion occurs around the colored foreign matter Dy, and thus scattered light may be generated at the distorted portion. . In this case, the area around the dark point becomes bright, and a dark point with a bright point is formed around the dark point. However, even in such a case, since the colored foreign matter Dy absorbs much of the light incident on the defective portion, a dark spot always exists, and the dark spot is detected as a cluster with a bright spot surrounding the dark spot. After all,
Defects due to colorless foreign matter form bright spots, while defects due to colored foreign matter form dark spots.

FIG. 5A shows that the colored foreign matter is
FIG. 4 shows how the brightness changes when the light source crosses the first imaging positions P1 to P3 (see FIG. 1). In the example shown in this figure, light is absorbed by the colored foreign matter portion, and the light is refracted by the distorted portion around the colored foreign material toward the line camera 11, so that a bright point is formed around the dark spot. On the other hand, in the case of a colorless foreign matter, as shown in FIG. 5B, the light is scattered by the colorless foreign matter and its surrounding distorted portion and goes to the line camera 11 without being absorbed by the foreign matter. Is formed.

As described above, in the present invention, a light point or a dark point based on the brightness of a formation portion is formed using light in a direction other than the optical axis J of the line camera 11. For reference, a case where the inspection target is illuminated from the optical axis direction of the line camera 11 will be described. When the inspection target 1 is a transparent film, when the inspection target is illuminated from the optical axis direction of the line camera 11 as shown in FIG.
Since the light is transmitted to one side, the brightness of the formation becomes extremely high.

If the defect is caused by a colorless foreign matter, the light incident on the defect is scattered as shown in FIG. 4B, so that the defect is darker than the formation and the dark spot is reduced. It is formed. Although not shown, if the defect is caused by a colored foreign matter, light incident on the defective portion is absorbed by the defective portion, and a dark spot is similarly formed. That is, when the inspection target 1 is illuminated from the direction of the optical axis of the line camera 11, both the colorless foreign matter and the colored foreign matter form a bright point. Cannot be identified.

On the other hand, the present invention focuses on the fact that light incident on a defect from a direction other than the optical axis of the line camera 11 is scattered or absorbed by the defect depending on the type of defect. A bright point or a dark point is formed based on the brightness of formation. The principle of the defect inspection apparatus has been described above.

Next, the operation of the processing system that performs processing for detecting a defect from a light image of a bright point or a dark point formed based on the above principle will be described. Line camera 11
Receives a light image of a bright point or a dark point formed by a defect existing in the inspection object 1 and sends an image signal of the light image to the image processing device 14. The image processing device 14 compares a signal level of a normal part (that is, a part where no defect exists) with a part having a signal level difference of a certain level or more and extracts the part as a defect. As information on the signal level of the normal part, information on a past line (corresponding to a line-shaped imaging area illuminated by the illumination device 12A) input from the camera is used, or information on the same line is used. There is. A method of differentiating a signal to find a change point is a typical example of the latter.

The image processing device 14 has a function of determining whether the signal level of the image signal of the defective portion indicates a bright point or a dark point. That is, when the signal level of the defective portion indicates only a dark point and when the signal level indicates a dark point surrounded by bright points,
The type of defect is determined by using a predetermined determination condition for a dark point (colored foreign matter). When the signal level of the defective portion indicates only a bright point, the type of the defect is determined using a preset determination condition for the bright point (colorless foreign matter). This determination process can be performed by the host computer 13 for managing and operating the entire defect inspection apparatus. That is, when the image processing apparatus 14 does not perform the defect determination processing, the host computer 13 executes the above-described determination processing and outputs a defect detection signal indicating the result.

The defect inspection apparatus according to the first embodiment is more suitable for inspecting a translucent film than a transparent film having a high light transmittance. The reason is that in the case of a translucent film, the light from the illuminating device is diffused in the formation, so that the brightness of the formation is uniform and maintained at an appropriate level. This is because it becomes easy.
Of course, it cannot be applied to a transparent film, and it is possible to appropriately adjust each part by increasing the distance between the illumination device 12 and the inspection target 1 or reducing the light shielding width of the light shielding tape 31 on the light source. Is set appropriately, and the detection of a defect existing in the transparent film can be easily detected.

<Second Embodiment> Next, a second embodiment of the present invention will be described. The defect inspection apparatus according to the second embodiment targets a film or a sheet having a somewhat high light transmittance as a target to be inspected, similarly to the first embodiment. , A lighting device 12B shown in FIG. That is, this lighting device 12B
The two high-frequency lighting fluorescent lamps 12B-1 and 12B-2 are used as light sources.
B-2 are arranged close to each other with a gap provided therebetween, and are arranged on the lower surface side of the inspection target 1. The gap between these two high-frequency lighting fluorescent lamps (that is, the portion where no light is emitted) is adjusted so as to be located on the optical axis J of the line camera 11. When a linear optical fiber light guide is used as a light source, the two linear optical fiber light guides are arranged, for example, with an appropriate spacer interposed therebetween. The optical axis of the line camera 11 is adjusted on this spacer.

The illuminating device 12B is similar to the illuminating device 12A according to the first embodiment described above.
The inspection target 1 is illuminated in a state where light emission toward the imaging position on the inspection target 1 is suppressed on the optical axis of. As a result,
As shown in FIG. 3 described above, the light incident on the inspection target 1 on the optical axis J of the line camera 11 is mainly incident on the optical axis J from a direction other than the optical axis J. A light point or a dark point based on the height is formed, and a defect is detected as a light point or a dark point.

According to the second embodiment, since the position and brightness of the two light sources can be adjusted independently, the brightness and the brightness of the formation of the inspection object 1 are different from those of the first embodiment. It is possible to more appropriately set the relationship between the point and the scotoma.

Further, the defect inspection apparatus according to the second embodiment is more suitable for inspecting a translucent film than a transparent film having a high light transmittance for the same reason as in the first embodiment. Of course, it cannot be applied to a transparent film, and the brightness of the formation is adjusted by appropriately adjusting each part, for example, by increasing the distance between the illumination device 12 and the inspection target 1 or reducing the distance between the two rows of light sources. Is appropriately set, and detection of a defect existing in the transparent film can be easily detected.

<Third Embodiment> Next, a third embodiment of the present invention will be described. The defect inspection apparatus according to the third embodiment is intended for inspecting a film or a sheet having a relatively low light transmittance, and as shown in FIG. 8, the light sources 12C-1 and 12C such as high-frequency lighting fluorescent lamps. -2 and light source 1
An illumination device 12C having a light diffusion plate 12C-3 for diffusing outgoing light of 2C-1 and irradiating the inspection object 2 with the light is provided.

Here, the light source 12C-1 is disposed at a position deviated from the optical axis J of the line camera 11,
A light diffusion plate 12C-3 is arranged between 2C-1 and the inspection object 2. This light diffusion plate 12C-3 is
In order that C-1 does not directly illuminate the inspection object 2, it is disposed substantially parallel to the inspection object 2 so as to cover the light source 12C-1, and a part thereof is located on the optical axis J of the line camera 11. ing. The other light source 12C-2 has a role similar to that of the light sources 12B-1 and 12B-2 according to the second embodiment described above, and the inspection target 2C is viewed from a direction other than the optical axis J of the line camera 11. Is to illuminate. these,
The distance between the two light sources 12C-1 and 12C-2 and the inspection target 2 does not necessarily need to be the same.

Illumination device 12C according to the third embodiment
The light component 12C-2 illuminates the inspection target 2 from a direction other than the optical axis J of the line camera 11, and a light component traveling from the defective portion to the line camera 11 on the optical axis J according to the presence or absence and the type of the defect. Generate. Here, when the light transmittance of the inspection target 2 is low, the formation becomes dark with only the light from the diagonal direction of the light source 12C-2, and the formation of the dark spot is possible even if the bright spot can be formed by the colorless foreign matter. It will be difficult. Therefore,
The light from the light source 12C-1 is diffused by the light diffusion plate 12C-3, and a part of the light is irradiated on the inspection object along the optical axis J of the line camera 11. That is, the inspection target 2 is illuminated with an appropriate amount of light component directed toward the inspection target along the optical axis J of the line camera 11. Thereby, inspection object 2
The brightness of the formation is increased between the bright point and the dark point, and a light point or a dark point based on the brightness of the formation is formed.

According to the defect detection apparatus of the third embodiment, by irradiating the imaging position with appropriate light from the optical axis direction of the line camera 11, the brightness of the formation of the inspection target 2 having a low light transmittance is improved. Is appropriately maintained, it is possible to detect a defect existing in the inspection target 2 as a bright spot or a dark spot.

According to the third embodiment, the light source 1
The brightness of the formation can be arbitrarily set by adjusting the brightness and position of 2C-1, and independently of this, the brightness of the light source 12C-2 can be adjusted to adjust the brightness and dark spot. Brightness can be adjusted. Therefore, it is possible to arbitrarily set the relationship between the brightness of the formation of the inspection object 2 and the three points of the bright point and the dark point.

<Fourth Embodiment> Next, a fourth embodiment of the present invention will be described. The defect inspection apparatus according to the fourth embodiment targets a film or a sheet having a low light transmittance as the inspection target 2 similarly to the third embodiment, and as shown in FIG. 1, 12D-2, and an illumination device 12D having a light diffusion plate 12D-3. Here, the light sources 12D-1 and 12D-2 are
Are arranged substantially symmetrically with respect to the optical axis J at a position deviated from the optical axis J. Further, on the optical axis J of the line camera 11 and between the light sources 12D-1 and 12D-2 and the inspection target 2, the optical axes J from the light sources 12D-1 and 12D-2 are provided.
A light diffusion plate 12D-3 for diffusing light from each light source and irradiating the inspection target 2 with the light from each light source is arranged at a position where the optical path of the light toward the imaging position of the inspection target 2 is not obstructed.

Illumination device 12D according to the fourth embodiment
Is a line camera 1 using light sources 12D-1 and 12D-2.
The inspection object 2 is illuminated from a direction other than the optical axis J, and a light component traveling from the defective portion to the line camera 11 on the optical axis J is generated in accordance with the presence or absence and the type of the defect. Here, when the light transmittance of the inspection target 2 is low, the formation becomes dark, and it is difficult to form a dark spot even though a bright spot can be formed.
Then, a part of the light from the light sources 12D-1 and 12D-2 is diffused by the light diffusion plate 12D-3,
The inspection target 2 is irradiated from the optical axis direction. As a result, the brightness of the formation of the inspection target 2 is increased between the bright point and the dark point, and a bright point or a dark point based on the brightness of the formation is formed.

According to the defect detecting apparatus according to the fourth embodiment, even if the light transmittance of the inspection object is low,
Since the brightness of the formation is maintained at an appropriate level, it is possible to detect a defect existing in the inspection target as a bright spot or a dark spot. In addition, the positions and brightness of the light sources 12D-1 and 12D-2 can be independently adjusted, and the relationship between the formation of the inspection target and the bright spot and the dark spot can be set more appropriately. . Further, since the two light sources are arranged substantially symmetrically with respect to the optical axis J and are illuminated from both directions, a bright point and a dark point can be stably formed, and the defect detection sensitivity is improved.

<Fifth Embodiment> Next, a fifth embodiment of the present invention will be described. The defect inspection apparatus according to the fifth embodiment targets a film or a sheet having a low light transmittance, as in the third and fourth embodiments, as shown in FIG. -1,12E-2
And an illumination device 12E having a scattering reflector 12E-3.

Here, the light sources 12E-1 and 12E-2 are
At a position deviated from the optical axis J of the line camera 11, the optical axis J
Are arranged substantially symmetrically with respect to each other, and light is emitted in all directions, such as a high-frequency lighting fluorescent lamp. Also, on the optical axis J of the line camera 11, the light sources 12E-1,1
A scattering reflector 12E-3 having an appropriate reflectance is disposed at a position opposite to the inspection target 2 with respect to 2E-2, with its reflection surface facing the light source and the inspection target.

Illumination device 12E according to the fifth embodiment
Illuminates the imaging position of the inspection target 2 from a direction other than the optical axis J of the line camera 11 by the light sources 12E-1 and 12E-2, and moves the line camera on the optical axis J in accordance with the presence or absence of a defect and its type. A light component directed to 11 is generated. Here, since the light transmittance of the inspection target 2 is low, the formation becomes dark.
Therefore, only light from the light sources 12E-1 and 12E-2 from oblique directions makes it possible to form a bright spot by a colorless foreign matter, but it is difficult to form a dark spot. Therefore, the light source 12E
Light from -1 and 12E-2 is scattered and reflected by the scattering reflector 12E-3, and is radiated to the inspection target 2 from the optical axis direction of the line camera 11. As a result, the brightness of the formation to be inspected is increased to between the bright point and the dark point, and a bright point or a dark point based on the brightness of the formation is formed.

According to the defect inspection apparatus of the fifth embodiment, the amount of light emitted from the light sources 12E-1 and 12E-2 to the imaging position is changed by adjusting the position of the scattering reflector 12E-3. Without this, it is possible to adjust only the brightness of the formation of the inspection target 2 independently. Further, as compared with the above-described fourth embodiment, since the light source can be arranged closer to the inspection target, it is possible to reduce the size of the apparatus.

Although the first to fifth embodiments of the present invention have been described above, the present invention is not limited to this embodiment, and the present invention is applicable even if there is a design change or the like without departing from the gist of the present invention. Included in the invention. For example, in each of the above-described embodiments, a high-frequency lighting fluorescent lamp is used as a light source. However, the present invention is not limited to this, and an appropriate light source may be used. Further, the concept of the present invention is not limited to the above-described embodiment, and both the bright spot and the dark spot based on the brightness of the formation to be inspected are set according to the type of the foreign matter forming the defect. Is included in the concept of the present invention as long as it can form.

[0069]

[Embodiment] Finally, an embodiment of the present invention will be described. <Example 1> In FIG. 2 described above, the inspection target 1 is a polyolefin-based transparent film having a film thickness of 50 μm.
It is. As a type, a transparent to translucent film, which is colorless and whose surface is processed and has a light transmittance of about 80 to 90%, is mainly used. The defects to be detected were colored foreign matters of 0.3 mmφ or more and colorless foreign substances of 1 mmφ or more.

The line camera 11 is a 2048-element line CCD camera. As the lens, a macro lens of f (focal length) = 50 mm is used. The resolution of the camera is 0.15 mm / pixel. Camera CC
The distance from the D element position to the surface of the inspection target (a distance corresponding to the distance a shown in FIG. 11) is about 650 mm. The lighting device 12A uses a high-frequency lighting fluorescent lamp as a light source, and a light-shielding tape having a width of about 2 mm is attached to an upper surface of the fluorescent lamp. Further, the distance from the fluorescent lamp to the inspection target (FIG. 11)
Is equivalent to 300 mm.

The image processing device 14 binarizes data input from the line camera 11. That is, the line data of the normal part is compared with the data sequentially input from the line camera 11, and a portion that is brighter than a certain ratio with respect to the line data of the normal part is defined as a bright point, A portion darker than the ratio is extracted as a dark point. That is, for example, the normal part is set to “0”,
Data in which a defective portion (a bright spot and a dark spot) is “1” is generated. Then, the data obtained by the binarization is analyzed for the relationship with the data obtained in the previous line, and the areas of the bright and dark points and the vertical and horizontal sizes are output. Based on the output data, the host computer 1
In No. 3, the defective portion caused by the colored foreign matter and the defective portion caused by the colorless foreign matter were identified, and the target defect could be detected accurately and easily.

<Example 2> An inspection object 1 is a film having a high degree of transparency which has not been subjected to surface processing and has a light transmittance of more than 90%. If the light transmittance of the inspection target is high and there is no regular transmission light component (light in the optical axis direction of the line camera 11), the formation portion becomes dark, and a defect cannot be captured as a dark spot. For this reason, the formation portion is set to an appropriate light amount using illumination to which a regular transmission component is added. In the embodiment, as shown in FIG. 8, the fluorescent lamp light sources are arranged in two rows at positions not serving as the regular transmission light source, and a light diffusion plate is installed on one of the fluorescent lamps so that light of the regular transmission component is emitted. I have. Except for these points, defect inspection was performed in the same manner as in Example 1. As a result, the target defect could be detected accurately and easily.

[0073]

According to the present invention, the following effects can be obtained. That is, the inspection object is illuminated from one side of the inspection object so that the optical image of the defect forms a bright point or a dark point according to the type of the defect based on the brightness of the formation of the inspection object, Since the light image of the defect formed by the transmitted light of the inspection object is received and imaged, and the defect is detected as a bright point or a dark point based on the captured image, the configuration of the apparatus is complicated. Thus, it is possible to obtain a defect inspection apparatus that can reduce a load on image processing for identifying a defect without performing the inspection.

Further, since the amount of light emitted toward the imaging position on the inspection object along the optical axis of the imaging means is suppressed to illuminate the inspection object, the brightness of the formation of the inspection object is used as a reference. The inspection object can be illuminated such that the light image of the defect forms a bright spot or a dark spot depending on the type of the defect.

Further, as the illuminating means, a light source disposed on the optical axis of the imaging means and a light-shielding portion for shielding light emitted from the light source toward the imaging position on the inspection object are provided. It is possible to illuminate by shielding the amount of light emitted toward the imaging position on the inspection object along the optical axis of the inspection object, so that the light image of the defect is determined based on the brightness of the formation of the inspection object based on the type of the defect. The test object can be illuminated so as to form a bright spot or a dark spot accordingly.
Therefore, when the light transmittance of the inspection target is relatively high, it is possible to appropriately set the brightness of the formation of the inspection target,
This makes it easier to detect a defect present in the inspection object.

Further, since two light sources are provided as the illuminating means and arranged with a gap on the optical axis of the imaging means, the light source is directed to the imaging position on the inspection object along the optical axis of the imaging means. The inspection can be performed such that illumination can be performed without light emission, so that the light image of the defect forms a bright spot or a dark spot depending on the type of the defect based on the brightness of the formation to be inspected. The object can be illuminated. Therefore, when the light transmittance of the inspection target is relatively high, the brightness of the formation of the inspection target can be appropriately set, and the defect existing in the inspection target can be easily detected.

Further, a first light source disposed near the optical axis of the image pickup means as an illuminating means, and a light diffuser for diffusing light emitted from the first light source to form a light component heading toward the image pickup position. Since the plate and the second light source arranged near the optical axis of the imaging means and illuminating the imaging position are provided, the light emission toward the imaging position on the inspection object along the optical axis of the imaging means can be reduced by an appropriate amount. It is possible to illuminate only with this. Therefore, even if the inspection object has a low light transmittance, the brightness of the formation can be appropriately set, and a bright point or a dark point can be formed.

Further, as the illuminating means, a light source arranged near the optical axis of the imaging means for illuminating the object to be inspected, and the light emitted from the light source being diffused to form a light component heading toward the imaging position on the inspection object. In the same manner, it is possible to illuminate the light emission along the optical axis of the imaging means toward the imaging position on the inspection target with an appropriate amount. Therefore, even if the inspection object has a low light transmittance, the brightness of the formation can be appropriately set, and a bright point or a dark point can be formed.

Further, as the illuminating means, a light source arranged near the optical axis of the imaging means for illuminating the inspection object, and a light scattered and reflected from the light source toward the imaging position on the inspection object. Since the light reflecting plate for forming the component is provided, similarly, it is possible to illuminate with an appropriate amount of light emitted toward the imaging position on the inspection object along the optical axis of the imaging means. Therefore, even if the inspection object has a low light transmittance, the brightness of the formation can be appropriately set, and a bright point or a dark point can be formed.

In short, according to the present invention, the brightness level of the formation to be inspected is kept at an appropriate level, and the light point detection and the dark point detection are used in combination. Without making a decision by image processing,
Colored foreign matter and colorless foreign matter can be distinguished, and detection can be performed under different conditions.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an overall configuration of a defect inspection apparatus according to a first embodiment of the present invention;

FIG. 2 is a diagram illustrating an optical system of the defect inspection apparatus according to the first embodiment of the present invention;

FIG. 3 is a diagram for explaining an operation principle (detection of a defect due to a colorless foreign substance) of the defect inspection apparatus according to the first embodiment of the present invention;

FIG. 4 is a diagram for explaining the operation principle (comparison of detection of colorless foreign matter and colored foreign matter) of the defect inspection apparatus according to the first embodiment of the present invention;

FIG. 5 is a diagram for explaining the operation principle of the defect inspection apparatus according to the first embodiment of the present invention (comparison between a bright spot and a dark spot due to colorless foreign matter and colored foreign matter).

FIG. 6 is a reference diagram for supplementarily explaining the operation principle of the defect inspection apparatus according to the first embodiment of the present invention.

FIG. 7 is a diagram illustrating an optical system of a defect inspection device according to a second embodiment of the present invention;

FIG. 8 is a diagram illustrating an optical system of a defect inspection device according to a third embodiment of the present invention;

FIG. 9 is a diagram illustrating an optical system of a defect inspection apparatus according to a fourth embodiment of the present invention.

FIG. 10 is a diagram showing an optical system of a defect inspection apparatus according to a fifth embodiment of the present invention.

FIG. 11 is a diagram illustrating an optical system of a defect inspection apparatus according to the related art.

[Explanation of symbols]

 1: inspection object (light transmittance is relatively high) 2: inspection object (light transmittance is relatively low) 11: line camera 12A, 12B, 12C, 12D, 12E: illumination device 12A-1: light source 12B -1, 12B-2: light source 12C-1, 12C-2: light source 12D-1, 12D-2: light source 12E-1, 12E-2: light source 12A-2, 12C-3: light diffusion plate 12E-3: Scattering reflector 13: Host computer 14: Line image processing device

 ────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kuniyasu Tanaka 2-1-1, Ushikawadori, Toyohashi-shi, Aichi F-term (reference) 2F065 AA49 AA60 AA61 BB22 BB23 CC02 DD02 DD06 FF04 GG03 GG11 JJ25 LL02 LL04 LL28 LL49 NN01 QQ04 QQ25 QQ31 RR08 2G051 AA41 AB02 AB06 BA01 BB01 BC01 CA03 CB02 DA06 EA12 EA16 EB01 5B057 AA01 BA02 BA11 BA15 DA03 DC22

Claims (10)

[Claims] 1. A defect inspection apparatus for detecting a defect existing in a film-like or sheet-like inspection object, wherein an optical image of the defect is based on the brightness of the formation of the inspection object according to the type of the defect. Illuminating means for illuminating the inspection target from one surface side of the inspection target so as to form a bright point or a dark point, and provided on the other surface side of the inspection target and formed by transmitted light of the inspection target. A defect, comprising: an imaging unit that receives an optical image of the defect and captures the image; and a defect detection unit that detects the defect as a bright point or a dark point based on the image captured by the imaging unit. Inspection equipment. 2. The defect inspection apparatus according to claim 1, wherein the illumination unit illuminates the inspection object while suppressing light emission toward the inspection object along an optical axis of the imaging unit. apparatus. 3. The illumination means, wherein light directed toward the inspection object along the optical axis of the imaging means within a range in which the brightness of the formation of the inspection object is located between the bright point and the dark point. 2. The defect inspection apparatus according to claim 1, wherein the inspection object is illuminated while the inspection is performed. 4. The illumination means, wherein: a light source disposed on an optical axis of the imaging means; and a light source disposed between the imaging position and the light source, wherein the light source is arranged along the optical axis of the imaging means. The defect inspection apparatus according to claim 1, further comprising: a light blocking unit configured to block light emitted toward an inspection target. 5. The illumination device according to claim 1, wherein the illumination unit includes two light sources arranged near the optical axis of the imaging unit via a gap located on the optical axis. A defect inspection device described in any of the above. 6. The illumination unit, wherein: a first light source disposed near an optical axis of the imaging unit; and a first light source disposed between the first light source and the inspection target. A light diffusion plate that diffuses outgoing light to form a light component heading toward the inspection object along the optical axis of the imaging unit; and an imaging position on the inspection object that is disposed near the optical axis of the imaging unit. The defect inspection apparatus according to claim 1, further comprising: a second light source that illuminates. 7. The light source is arranged near the optical axis of the image pickup unit to illuminate the inspection object. The light source is arranged on the optical axis, and diffuses outgoing light of the light source to perform the image pickup. The defect inspection apparatus according to claim 1, further comprising: a light diffusion plate that forms a light component directed toward the inspection object along an optical axis of the means. 8. The light source is arranged near the optical axis of the imaging unit and illuminates the inspection target, and is arranged on the optical axis on the opposite side of the light source from the inspection target. And a scattering reflector that scatters and reflects emitted light from the light source to form a light component directed toward the inspection object along the optical axis. Defect inspection equipment. 9. An illumination device for illuminating a film or sheet to be inspected from one surface side, a line camera provided on the other surface side of the inspection object to receive transmitted light of the inspection object, and a line camera And a line image processing device for processing a signal of the defect, wherein a defect image present in the inspection target is detected, wherein the light image of the defect is based on the brightness of the formation of the inspection target according to the type of the defect. Illuminating the inspection target with the illumination device while suppressing the amount of light on the optical axis of the line camera so as to form a bright spot or a dark spot, and detecting the defect as a bright spot or a dark spot. Characteristic defect detection method. 10. The defect detection method according to claim 9, wherein the type of the defect is identified based on whether the defect is detected as a light point or a dark point.