KR20220117060A - Defect inspection apparatus - Google Patents

Abstract

The present invention relates to a defect inspection device, comprising: a light source unit for irradiating parallel light to an object to be tested; and a photographing unit for acquiring an image by receiving the light reflected from the object to be tested. An objective of the present invention is to provide the defect inspection device having excellent accuracy.

Description

Defect Inspection Device {DEFECT INSPECTION APPARATUS}

The present invention relates to a defect inspection apparatus, and more particularly, to a defect inspection apparatus through collection of light reflected from an object with excellent precision for detecting concavo-convex defects.

Conventional visual inspection methods are automatically performed by a mechanical device through an automated facility. As an automated inspection device, the optical system inspection device is used for detecting surface defects of a material having a flat surface.

For example, glass and various optical films included as parts of an image display device are required to have smooth and flat surfaces in order to improve the image output quality of the image display device. In particular, in the case of optical films used in an image display device as a surface protection film, a polarizer, a retardation film, etc., the surface needs to be extremely flat.

However, defects such as scratches, foreign substances, bubbles, irregularities, tears, warping or folding may occur on the surface of glass and optical films during manufacturing or handling.

In order to improve the image quality of an image display device, it is necessary to detect such defects with high sensitivity. For example, Korean Patent No. 10-1762165 discloses a technology related to an appearance inspection apparatus using diffused light as a light source. However, the appearance inspection apparatus disclosed in the above patent document has a limit in securing a more accurate defect detection power.

Accordingly, there is a need for a defect inspection apparatus capable of improving the detection accuracy of defects.

Korean Patent Publication No. 10-1762165

An object of the present invention is to provide a defect inspection apparatus having excellent precision.

The present invention, a light source for irradiating parallel light to the object to be examined; and a photographing unit configured to acquire an image by receiving light reflected from the inspection object.

The defect inspection apparatus according to the present invention uses parallel light as a light source to increase the degree of refracting and scattering of light in the defect area by changing the light divergence path, thereby providing more accurate defect detection power for defects accompanied by concave-convex defects without changing the angle. can be obtained

Accordingly, it has the effect of further improving the quality of the product compared to the conventional defect inspection apparatus using diffused light as a light source.

1 is a perspective view schematically showing a defect inspection apparatus according to an embodiment of the present invention.
2 is a front view schematically showing a defect inspection apparatus according to an embodiment of the present invention.
3 is a diagram illustrating a detection intensity of a defective portion derived from an image obtained by using the defect inspection apparatus according to an embodiment of the present invention and the defect inspection apparatus according to a comparative example.

The present invention provides a defect inspection apparatus which exhibits high precision in detecting defects such as concavo-convex defects and has excellent detection performance.

Specifically, the present invention, a light source for irradiating parallel light to the object to be inspected; and a photographing unit configured to acquire an image by receiving light reflected from the inspection object.

According to the defect inspection apparatus according to the present invention, by using parallel light as a light source, it is possible to secure more accurate defect detection power by increasing the degree of refraction and scattering of the light in the defect part by changing the light divergence path, It can exhibit the effect of further improving the quality of the product compared to the conventional defect inspection apparatus.

"Defect" in the present invention includes any defects that occur during the manufacturing process or pre-production, post-processing, and/or distribution process of the inspection object to be inspected, for example, scratches, foreign substances, bubbles, irregularities , tearing, warping, or folding. Accordingly, when the inspection object is observed, the color may include an atypical defect in which a color such as brightness is non-uniformly observed. For example, an area including the defect may have a higher or lower brightness than a peripheral part.

The defect inspection apparatus according to the present invention can be more suitably used for detecting defects accompanied by irregularities among the defects.

Meanwhile, herein, the machine direction MD may be defined as a movement direction of the object, and a direction perpendicular to the machine direction MD may be defined as a transverse direction (TD).

Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings. However, the following drawings attached to the present specification illustrate preferred embodiments of the present invention, and serve to further understand the technical spirit of the present invention together with the above-described content of the present invention, so the present invention is described in such drawings It should not be construed as being limited only to the matters.

The terminology used herein is for the purpose of describing the embodiments, and is not intended to limit the present invention. In this specification, the singular also includes the plural unless specifically stated otherwise in the phrase.

As used herein, includes and/or comprising refers to the presence or addition of one or more other components, steps, operations and/or elements other than the recited elements, steps, operations and/or elements. It is used in the sense of not being excluded. The same reference numerals refer to the same components throughout the specification, and components shown in the drawings may be exaggerated, reduced, or omitted for a smooth description.

Spatially relative terms "beneath", "lower", "above", "upper", etc., as shown in the drawings, refer to one element or component and another. It can be used to easily describe the correlation with elements or components. The spatially relative terms should be understood as terms including different orientations of the device during use or operation in addition to the orientation shown in the drawings. For example, when a configuration shown in the drawings is reversed, a configuration described as “beneath” or “beneath” of another configuration may be placed “above” another element. Accordingly, the exemplary term “below” may include both directions below and above. Each configuration may also be oriented in different directions, and thus spatially relative terms may be interpreted according to the orientation.

<Defect Inspection Device>

1 and 2 are schematic views showing a defect inspection apparatus according to an embodiment of the present invention, Figure 1 is a perspective view schematically showing a defect inspection apparatus according to an embodiment of the present invention, Figure 2 is the present invention is a front view schematically showing a defect inspection apparatus according to an embodiment.

Referring to FIG. 1 , the defect inspection apparatus of the present invention includes a light source unit 100 and a photographing unit 200 .

Hereinafter, each component of the defect inspection apparatus of the present invention will be described.

light source

The light source unit 100 irradiates light to visualize the defects 11 existing in the inspection object 10 , and may be provided on one surface of the inspection object 10 .

The conventional defect inspection apparatus uses diffused light as a light source to consider the angle formation between the light source and the imaging device, so there is a problem in that the installation space is relatively limited.

The defect inspection apparatus according to the present invention includes the light source unit 100 for which the light source unit 100 irradiates parallel light, and can secure a large illuminance without diffusing the light, so that the light of the defect unit is refracted and scattered without changing the angle. By increasing the effect, it is possible to secure more accurate defect detection power compared to the conventional defect inspection apparatus.

1 and 2 are schematic views showing a defect inspection apparatus according to an embodiment of the present invention. More specifically, FIG. 1 is a perspective view of a case in which the defect 11 does not exist in the object 10 to be inspected in some embodiments. 2 is a front view of a case in which a defect 11 exists in the object 10 to be inspected in some embodiments.

Referring to FIG. 1 , when there is no defect in the object 10 to be inspected, the parallel light irradiated through the light source unit 100 is not diffracted, scattered or refracted but is incident on the photographing unit 200, so an image without a difference in brightness is obtained. can be obtained

Referring to FIG. 2 , the parallel light irradiated through the light source unit 100 arrives at the object 10 , and among them, the light reaching the defect 11 is diffracted, scattered, or refracted at the defect site. The progress path is changed. Since the light whose path has been changed as described above is not incident on the photographing unit 200 , the corresponding defect portion appears dark, and the defect 11 on the object 10 to be inspected can be detected using the difference in brightness.

The light source unit 100 of the present invention is characterized in that the parallel light is irradiated, and the parallel light may be disposed so that the parallel light is incident obliquely (obliquely) to the object 10 to be inspected.

When the parallel light is irradiated to the object to be inspected 10, the portion without the defect 11 reflects the parallel light, but the portion with the defect 11 causes refraction of the emitted light, and the scattered light may be reflected. have.

In the defect inspection apparatus according to the present invention, the light source unit 100 uses the parallel light as a light source, and the refraction of light is large in the region where the defect 100 exists, compared to using the diffused light as a light source, and there is no defect. It is possible to increase the brightness contrast between the region and the region in which the defect exists, thereby increasing the visibility of the defect, thereby further improving the defect detection power.

The light source of the light source unit 100 is not particularly limited as long as it serves to visualize defects and emits parallel light, but preferably an LED light source may be used.

In an embodiment, the light source unit 100 may be characterized in that a plurality of light sources are arranged in a line shape. The line may mean a straight line, but is not limited thereto. In the case of the light source unit in which the plurality of light sources are arranged in a line shape, the optical axis of the light source unit 100 and the optical axis of the photographing unit 200 may coincide with the direction perpendicular to the inspection object 10 . Accordingly, it is preferable because the difference in brightness between the defective portion and the peripheral portion can be further improved by maximizing the amount of light reflected from the inspection object 10 and incident to the photographing unit 200 .

In an embodiment, the light source unit 100 may have a bar shape. The bar shape may have a length greater than or equal to the width of the test object 10 .

cinematographer

The photographing unit 200 is to acquire an image by photographing the inspection object 10 in which the defect is visualized by the parallel light irradiated from the light source unit 100 . The photographing unit 200 may be provided on one surface of the inspection object 10 , and preferably may be provided to face the light source unit 100 .

The photographing unit 200 is not particularly limited as long as it can obtain an image of the inspection object 150 in which the stain is visualized. For example, there may be a color line scan camera, a digital camera, and the like, and a color line scan camera is preferable in order to emphasize the contrast between the background area and the defect area.

test subject

The inspection object 10 may be a film that transmits a predetermined amount of light or an opaque substrate that does not transmit light, and in an embodiment, the inspection object 10 may be an opaque substrate.

The opaque substrate is not particularly limited as long as it is produced through a Roll To Roll process, and for example, a polarizing film, a pouch film, and the like may be mentioned.

The distance between the inspection object 10 and the light source unit 100 is not particularly limited as long as the defect can be visually recognized by the irradiated light, but is preferably 20 to 300 mm.

<How to check for defects>

The present invention includes an automatic defect inspection method using the defect inspection apparatus described above.

An automatic defect inspection method of the present invention includes: acquiring an image by irradiating parallel light from a light source to an object to be inspected; and deriving the detection intensity of the defect from the acquired image.

Hereinafter, a defect inspection method according to an embodiment of the present invention will be described, but the present invention is not limited thereto.

First, by irradiating light from a light source assembly including a light source such as a backlight unit (BLU), an LED light source, or a metal halide lamp to an object to be examined, defects of the object are visualized. The inspection object in which the defect is visualized by the irradiated light is photographed using a color line-scan camera or a digital camera.

Thereafter, the detection intensity of the defect is derived from the difference between the maximum brightness (gray scale) of the defective area and the average brightness of the adjacent area surrounding the defective area from the photographed image of the object to be inspected.

The components disclosed in the defect inspection method may exhibit all the characteristics described in the item <defect inspection apparatus> .

In addition, each step of the defect inspection method may be implemented by the components described in the item <defect inspection apparatus> .

Hereinafter, examples of the present invention will be specifically described. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, and only these embodiments allow the disclosure of the present invention to be complete, and common knowledge in the art to which the present invention pertains It is provided to fully inform those who have the scope of the invention, and the present invention is only defined by the scope of the claims.

<Examples and Comparative Examples>

Inspection objects having concavo-convex defects (defect numbers #1 to #3) were prepared. Using the defect inspection apparatus of the present application (Example, parallel light) and the conventional defect inspection apparatus (Comparative example, diffused light), respectively, light was irradiated at an angle of about 45° with respect to the normal direction of the inspection object. An examination image was obtained through a camera (Linea 16k, Dalsa Corporation) in which the irradiated light was disposed on the path of the light reflected by the examination object.

The defect intensity was derived from the obtained image and is shown in FIG. 3 . The defect intensity shown in FIG. 3 was calculated as the difference between the maximum brightness (gray scale) of the defect site and the average brightness of the adjacent region surrounding the defect site. The brightness is obtained from gray levels (0 to 255) obtained from an image sensor (CCD or CMOS).

Referring to FIG. 3 , in the case of the embodiment in which the parallel light is irradiated to the object to be inspected, the detection power for the concave-convex defect is higher than that of the comparative example, and thus it can be seen that the precision for detecting the defect is greatly improved.

10: test object
11: Defect
100: light source unit
200: shooting department

Claims (1)

a light source unit irradiating parallel light to the object to be examined; and
Defect inspection apparatus comprising a photographing unit for acquiring an image by receiving the light reflected from the inspection object.

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