KR20150120761A - Method for discriminating defect of polarizing plate - Google Patents

Abstract

The present invention relates to a method for discriminating a defect of an optical film and, more particularly, to a method for discriminating a defect of an optical film, capable of remarkably increasing the production yield of the optical film and reducing manufacturing costs by rightly discriminating a part which is not an actual defect and is previously discriminated as the defect by including the steps of: (S1) checking a foreign material by inspecting the optical film with protection films stacked on both sides thereof; (S2) classifying the foreign materials into the defect and the foreign material without the defect by separating the protection films of both sides of the optical film including the foreign materials; (S3) obtaining a classification standard to classify the foreign materials into the defect and the foreign material without the defect by obtaining information about a relation between an intensity and one or more values selected among a group composed of a thickness and an area according to a mathematical formula 2 and density according to a mathematical formula 1 of the defect and the foreign material without the defect; and (S4) excluding the foreign material which is discriminated as the foreign material without the defect from the defect in the foreign materials of the optical film according to the obtained information.

Description

METHOD FOR DISCRIMINATION DEFECT OF POLARIZING PLATE [0002]

The present invention relates to a method for discriminating defects of an optical film. More particularly, the present invention relates to a defect detection method capable of reducing a defect of a good product with respect to a polarizing plate.

Various image display devices such as a liquid crystal display, an organic light emitting display, a field emission display (FED), and a plasma display panel (PDP) have recently been widely developed and used.

Meanwhile, since the image display device has various defects in the manufacturing process before being shipped to the market, it is subjected to various inspection processes. Of these, one of the most used parts in the image display device is a polarizing film, And thus defects of the optical film are one of the main causes of the defect of the image display device. In order to detect the defects of the optical film, it is firstly determined whether or not the defects are defective and then an accurate determination is made. After that, if it is determined that defects are defects, repair or disposal according to defects, This is an important part.

The production of the optical film usually uses a line process for industrial mass production. Therefore, the detection of defects consists of continuously photographing the optical film at a specific position of the line and determining the defect at the photographed portion.

In the defect discrimination, it has been important in the past to detect various defects without fail. In this regard, Korean Patent Publication No. 2010-24753 discloses a method of distinguishing a line-shaped foreign object by comparing the area of the foreign object with the closed curve including the foreign object.

However, recently, as the cost of a component is increased due to the tendency of an optical film to become larger, a more accurate defect discrimination method is required. Therefore, a method of accurately discriminating a defect still needs to be done.

Korean Patent Publication No. 2010-24753

An object of the present invention is to provide a method for accurately discriminating defects and non-defects of an optical film.

It is an object of the present invention to provide a method of discriminating a defect in an optical film which is not actually a defect but which has been determined to be a defect in the related art.

An object of the present invention is to provide a defect discrimination apparatus for an optical film that discriminates those which are not actually defects but which have been judged to be defects as defects.

1. (S1) Inspecting an optical film on both sides of which a protective film is laminated to confirm whether or not the optical film is free of foreign matter;

(S2) peeling off the protective film on both surfaces of the optical film including the foreign object, and classifying the foreign object into a defect with foreign material;

(S3) obtaining information on the relationship between the positive physical property and the defect with respect to intensity and at least one value selected from the group consisting of density according to the following formula (1), thickness and area according to the following equation (2) Obtaining a criterion that classifies the character foreign matter and the defect; And

(S4) a step of removing foreign matter, which is determined to be a positive foreign matter, from the defect in the foreign substance of the optical film in accordance with the obtained information,

[Equation 1]

Density of the foreign object = area of the foreign object / area of the circle with the long axis of the foreign object as the diameter

 &Quot; (2) "

Thickness of foreign object = area of foreign object / length of foreign object.

2. The method of claim 1, wherein the step (S3) includes a step (S3-1) of obtaining a primary classification reference for sorting both positive and negative foreign matter and defects according to the relationship between the intensity and density of each foreign matter. Defect detection method.

3. The method according to claim 2, wherein the step (S3) is a step of obtaining a second classification standard in which foreign matter classified as a defect according to the first classification standard is classified again into a binary foreign matter and a defect according to the relationship between the strength and thickness of each foreign object Further comprising the step (S3-2).

4. In step 3, the step (S3) is a step of obtaining a tertiary classification standard in which foreign matter classified as a defect according to the secondary classification standard is classified again into a binary foreign matter and a defect according to the relationship between the strength and area of each foreign object Further comprising the step (S3-3).

5. The method according to claim 4, wherein the step (S3) is a step of obtaining a fourth classification standard in which foreign matter classified as a defect according to the third classification standard is classified again as a foreign matter and defect according to the relationship between the strength and area of each foreign object The method of claim 1, further comprising the step (S3-4).

6. The method of claim 5, wherein in step (S3), the foreign matter classified as a bifurcated foreign matter according to the primary, secondary, and tertiary classification criteria is re-classified according to the relationship between the strength and density of each foreign object, And a step (S3-5) of obtaining a fifth-order classification criterion for classifying the defects as defects.

7. The method of claim 6, wherein in step (S3), the foreign matter classified as a defect according to the fifth classification standard is further classified as a foreign matter and defect according to the relationship between the strength and density of each foreign matter. (S3-6) of obtaining a defect of the optical film.

8. The method of claim 7, wherein the step (S3) further comprises classifying the foreign object classified as a bifurcated foreign object according to the sixth classification standard into a bifurcated foreign object and a defect according to the relationship between the length and width of each foreign object. (S3-7) of obtaining a difference classification criterion.

9. The method of claim 8, wherein the step (S3) further comprises classifying the foreign object classified as a bifurcated foreign object into two kinds of foreign objects and defects according to the relationship between the length and width of each foreign object. (S3-8) of obtaining a difference classification criterion.

10. The method of claim 9, wherein in step (S3), the foreign matter classified as a defect in accordance with the 8th order classification criteria has a width greater than a predetermined width value as a defect and a length greater than a predetermined length value as a defect (Step S3-9) of obtaining a ninth order classification criterion for classifying the defect as a defect.

11. The method of claim 10, wherein in step (S3-9), the foreign matter classified as a defect in accordance with the 6th and 7th order classification criteria is determined such that the transverse length exceeds the predetermined transverse length value as a defect, And a defect is further classified as a defect in the case of exceeding the value of the vertical length.

12. The method of claim 1, wherein, in the step (S4), the double-personal foreign matter is a foreign object which is not a cluster type defect, and the cluster type defect has two or more foreign objects in a circle having a radius of 5 mm And the set of foreign objects including the center foreign object.

13. The method for discriminating defects of an optical film according to claim 1, wherein foreign matters selected from both the light transmission inspection and the cross-Nicol inspection in step (S4) are excluded from defects satisfying the following formula (3)

&Quot; (3) "

(Selected area in cross-Nicol test / area selected in light transmission test) ≥ 8.

14. A light source for irradiating light on one surface of an optical film having a protective film laminated on both surfaces thereof;

A photographing device for photographing a light irradiated portion of the optical film;

A foreign object sorting unit for sorting foreign objects in the image photographed by the photographing apparatus;

A protective film peeling unit for peeling the protective film on both surfaces of the optical film;

Information on the relationship between the intensity of at least one selected from the group consisting of the density according to the following formula (1), the thickness according to the following formula (2), and the area and the intensity after the protective film is removed from the protective film An information obtaining unit to obtain; And

And a judging section for classifying the foreign object of the optical film in which the protective film is laminated on both sides according to the information obtained by the information obtaining section, into a bipolar foreign matter and a defect.

[Equation 1]

Density of the foreign object = area of the foreign object / area of the circle with the long axis of the foreign object as the diameter

 &Quot; (2) "

Thickness of foreign object = area of foreign object / length of foreign object.

15. The defect discrimination apparatus for an optical film according to 14 above, wherein the information obtaining section obtains a primary classification reference for classifying the binary foreign objects and defects according to the relationship between the intensity and the density of each foreign object.

16. The method of claim 15, wherein the information obtaining unit further obtains a secondary classification criterion for classifying a foreign object classified as a defect according to a primary classification standard as a foreign object and defect according to a relationship between the strength and thickness of each foreign object, A defect discrimination device for an optical film.

17. The information obtaining unit of claim 16, wherein the information obtaining unit obtains a third classification standard for classifying the foreign objects classified as defects according to the secondary classification standard into two kinds of foreign objects and defects according to the relationship between the intensity and area of each foreign object, A defect discrimination device for an optical film.

18. The information obtaining unit of claim 17, wherein the information obtaining unit further obtains a fourth classification standard for classifying the foreign objects classified as defects according to the third classification standard as the foreign objects and defects according to the relationship between the strength and the area of each foreign object, A defect discrimination device for an optical film.

19. In item 18 above, said information obtaining unit is further provided with a step of detecting the foreign matter classified as a bona fide foreign matter in accordance with the above-mentioned primary, secondary, and tertiary classification criteria, To obtain a fifth-order classification standard.

20. The information obtaining unit of claim 19, wherein the information obtaining unit further obtains a sixth classification standard for classifying the foreign objects classified as defects according to the fifth classification standard as defective foreign objects and defects according to the relationship between the strength and density of each foreign object , Defect discrimination device for optical film.

21. The method of claim 20, wherein the information obtaining unit recovers the foreign object classified as a bifurcated foreign object according to the sixth classification standard by a seventh order A defect discrimination apparatus for an optical film, which further obtains a reference.

22. In the above 21, the information obtaining unit obtains the 8th order classification of the foreign matter classified as the two-kind foreign matter according to the 7th order classification, again as the double foreign matter and the defect according to the relationship between the length and width of each foreign object A defect discrimination apparatus for an optical film, which further obtains a reference.

23. The apparatus of claim 22, wherein the information obtaining unit determines that the foreign object classified as a defect in accordance with the 8th order classification criteria is a defect whose length is greater than a predetermined width value as a defect and whose height is more than a predetermined value Further obtaining a ninth order classification standard for classifying defects.

24. The method of claim 23, wherein the information obtaining unit is configured to determine that the foreign matter classified as a defect in accordance with the sixth and seventh classification criteria has a width greater than a predetermined width value as a defect and a length greater than a predetermined length value The defect is further classified into a defect.

25. The optical disc of claim 14, wherein the judging unit classifies the set of foreign objects including a center foreign object as a defect, if two or more foreign objects exist in a circle having a radius of 5 mm around any foreign object, Discrimination device.

26. The apparatus of claim 14, further comprising a polarization filter disposed in a cross-Nicol state between the light source and the imaging device,

Wherein the judging unit excludes, from defects, foreign objects satisfying the following formula (3) among foreign objects selected in both the light transmission inspection and the cross-Nicol inspection:

&Quot; (3) "

(Selected area in cross-Nicol test / area selected in light transmission test) ≥ 8.

The defect determination method of the optical film of the present invention is not actually a defect, but it is possible to remarkably increase the production yield of the optical film by properly determining what has been judged as a defect in the related art.

In addition, the defect determination method of the optical film of the present invention can significantly reduce the manufacturing cost and can prevent waste of resources.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram schematically illustrating an example of a cluster type defect. FIG.
2 is a view schematically showing an example of a bright spot defect.
FIG. 3 is a schematic view showing an example of a threading defect.
FIG. 4 is a schematic view showing an example of a star object corresponding to a bipartite foreign object.
5 is a view schematically showing an example of a scratch foreign matter corresponding to a bipolar foreign matter.
6 is a diagram schematically illustrating an example of a cluster type defect.
FIG. 7 is a schematic flowchart of a defect determination method of an optical film according to an embodiment of the present invention.

The present invention relates to (S1) an optical film having a protective film laminated on both sides thereof to inspect whether an optical film is present or not; (S2) peeling off the protective film on both surfaces of the optical film including the foreign object, and classifying the foreign object into a defect with foreign material; (S3) obtaining information on the relationship between the positive physical property and the defect with respect to intensity and at least one value selected from the group consisting of density according to the following formula (1), thickness and area according to the following equation (2) Obtaining a criterion that classifies the character foreign matter and the defect; And (S4) removing the foreign matter, which is determined to be a positive foreign matter in the foreign substance of the optical film, from the defect in accordance with the obtained information, thereby making it possible to correctly judge those which are not actually defects but which have been judged as conventional defects, To a defect discriminating method of an optical film which can remarkably increase and significantly reduce the number of defects.

Hereinafter, a defect determination method of an optical film according to an embodiment of the present invention will be described in detail.

First, it is checked whether or not the optical film on which the protective film is laminated on both sides (S1) contains foreign matter.

As used herein, the term "foreign matter " refers to a portion deviating from the average uniformity of the optical film.

The confirmation of the presence of the foreign object can be made by photographing the optical film at the top of the optical film to obtain an image, and obtaining an image of an area including a part (foreign part) deviating from the average uniformity of the predetermined optical film in the obtained image Processing software, or the like.

In this embodiment, a polarizing plate is used as the optical film. In the inspection image, the other polarizing plate perpendicular to the polarization direction of the polarizing plate to be inspected is placed on the upper side of the film to be inspected, It is obtained by photographing light passing through. If the polarizing plate to be inspected is good, there is no light passing through the two polarizing plates whose polarization directions are perpendicular to each other, so that a black image is obtained. However, if foreign matter exists on the polarizing plate to be inspected, Light is leaked out to obtain an image in which a bright part (that is, a foreign part) exists.

Further, the inspection image may be obtained by placing the light source under the optical film, which is the sample to be inspected, without taking a separate polarizing plate, and photographing light passing through the sample. In such a case, if the optical film to be inspected is a good product, light is transmitted to obtain a transparent image, but if a foreign substance exists in the optical film to be inspected, an image in which a dark part (foreign part) .

Thereafter, (S2) the protective film on both surfaces of the optical film including the foreign object is peeled off, and the foreign object is classified as defective with a positive foreign matter.

When an optical film is industrially manufactured, a protective film or the like is produced together with both sides of the optical film for convenience of storage and transportation of the optical film. In the defect determination process, the optical film with the protective film attached is inspected So that damage to the protective film, foreign matter inside the protective film, or foreign matter between the optical film and the protective film can be detected as well as the foreign matter of the optical film. However, the damage of the protective film, the foreign matter inside thereof, or the foreign matter between the optical film and the protective film is not a practical defect because the optical film is removed together with the protective film when the optical film is introduced into the image display apparatus.

That is, the foreign matter of the optical film corresponds to a defect, and the foreign matter of the protective film and the foreign matter between the protective film and the optical film correspond to a bona fide foreign matter.

Examples of such defects are shown in Figs. 1 to 3, and Figs. 4 and 5 illustrate examples of double-object foreign objects.

Fig. 1 is a cluster type defect, Fig. 2 is a defocus defect, and Fig. 3 is a defect which can be referred to as a defect defect, which corresponds to a defect of the optical film. FIG. 4 is a star, and FIG. 5 is a foreign object which can be referred to as a scratch, which is a foreign object between the protective film or the protective film and the optical film.

However, in the past, there has been no method for discriminating defects related to such a protective film. Therefore, the defective product is often misjudged as a defective product. In order to confirm this, the protective film has to be peeled and inspected. Such a problem may lead to an increase in the manufacturing cost, and in particular, in recent years, optical films have also become larger due to the trend of larger image display devices, and such problems may become more serious.

Accordingly, the present invention separates the foreign objects and defects by separating the protective film only for a part of the foreign objects, obtains information on the relationship between the density and the thickness, The criteria for classifying defects can be set.

The separation of the two-kind foreign matter and the defect can be carried out again after the separation of the protective film and then the above-described foreign matter sorting process. Specifically, in the case of defects, even if the protective film is peeled off, it can be directly detected as foreign matter. However, in the case of a double-ply foreign matter, it is not a defect of the optical film itself but a foreign matter or defect of the protective film. No object is selected.

In addition, the separated foreign matter may be classified as defects by taking a peeled protective film.

(S3) the density of the foreign matter and defect according to the following formula (1), the thickness and the area according to the following formula (2), and the strength and Obtains information on the relationship, and obtains a criterion for classifying the foreign object into two kinds of foreign objects and defects.

[Equation 1]

Density of the foreign object = area of the foreign object / area of the circle with the long axis of the foreign object as the diameter

&Quot; (2) "

Thickness of foreign object = area of foreign object / length of foreign object.

The area of the foreign object is an area of a portion corresponding to the foreign object on the optical film. For example, if the foreign object is discriminated from the image of the optical film, the unit may be a pixel.

The area of the circle whose diameter is the major axis of the foreign object means the area of the circle whose diameter is the longest line segment connecting two points on the foreign object, and similarly, the unit may be a pixel.

Hereinafter, the unit of the area and the length may all be pixels, but the present invention is not limited thereto.

The intensity of a foreign object means a difference in brightness from a normal region, not a foreign object. The larger the difference in brightness, the greater the intensity.

According to a more specific embodiment (S3-1), a primary classification standard for classifying foreign matter and defects according to their strength and density relationship can be obtained.

Examples of obtaining a classification criterion are shown in the graph on both positive and negative foreign objects and defects, and a case where a straight line separating defective foreign objects from foreign objects is drawn on the graph will be described in detail, but the present invention is not limited thereto.

According to the present invention, the x-axis of the binary foreign objects and the defects are denoted by the densities of the formula (1) and the y-axis are the intensity 1-1, and the foreign matter cluster and the defect community are distinguished The first straight line can be drawn.

A foreign object whose strength value is equal to or larger than the y value of the first straight line at the same x in the above-mentioned graph 1-1 is defective and the foreign object whose strength value is smaller than the y value of the first straight line at the same x can be classified as a positive foreign matter .

The first straight line corresponds to the primary classification reference. After obtaining the primary classification standard, on the optical film produced in the same line, the selected foreign matter is shown on the 2-1 graph in which the x-axis is dense and the y-axis is the intensity, without peeling off the protective film thereafter, 2-1 Drawing a first straight line on the graph, a foreign object whose intensity value is equal to or larger than the y value of the first straight line at x is defective, and the foreign object is classified as a positive foreign object.

In order to further improve the reliability of the optical film of the present invention, it is also possible to reclassify foreign matter classified as a bona fide foreign matter according to the above-mentioned primary classification standard into bona fide foreign matters and defects, It can be reclassified as both qualitative foreign objects and defects.

Specifically, a second classification criterion is obtained in which the foreign matter classified as a defect according to the primary classification standard obtained in the above step (S3-1) is classified again into a binary foreign matter and a defect according to the relationship between the strength and thickness of each foreign matter S3-2).

According to this, a foreign object classified as a defect according to the primary classification standard is shown in a 1-2 graph in which the x axis is the thickness and the y axis is the intensity.

The defect classified by the primary classification, but among them, there may be a foreign object classified as a bona fide foreign object in the step (S2). Therefore, the foreign object and the defect may be shown on the 1-2 graph. Then, a second straight line is drawn on the 1-2 graph to divide the double foreign object and the defect.

A foreign object having a strength value equal to or higher than the y value of the second straight line at the same x in the 1-2 graph is defective and the foreign object is classified as a positive foreign object.

The second straight line is a secondary classification reference, and the foreign matter classified as a defect by the primary classification standard is shown on the 2-2 graph in which the x-axis is the thickness and the y-axis is the intensity, A foreign matter having a strength value equal to or larger than the y value of the second straight line at the same x is defected, and a foreign matter having no strength value is classified as a positive foreign matter.

Further, the method further includes a step (S3-3) of obtaining a tertiary classification criterion in which the foreign matter classified as a defect according to the secondary classification standard is classified again as a foreign matter and defect according to the relationship between the strength and the area of each foreign matter .

The third line is a graph in which the x-axis is an area of the foreign object classified as a defect according to the secondary classification standard and the y-axis is an intensity of the foreign object. I draw.

A foreign matter having an intensity value equal to or higher than the y value of the third straight line at the same x in the above-mentioned first to third graphs is defective, and the foreign matter is not classified as a positive foreign matter.

The third straight line is a tertiary classification reference and the foreign matter classified as a defect by the secondary classification standard is shown on the 2-3 graph with the x axis as the area and the y axis as the intensity, A foreign matter having a strength value equal to or larger than the y value of the third straight line at the same x is defective or a foreign object is classified as a positive foreign matter.

Further, the method further includes a step (S3-4) of obtaining a fourth classification standard for classifying the foreign matter classified as the defect according to the third classification standard as a defect of foreign matter based on the relationship between the strength and the area of each foreign object .

The foreign matter classified as the defect according to the above-mentioned third classification standard is shown in the 1-4 graph in which the x axis is the area and the y axis is the intensity. On the 1-4 graph, the fourth straight line I draw.

Foreign matter whose intensity value is larger than the y value of the fourth straight line at the same x on the above-mentioned first to fourth graphs is defective, and foreign matter which is not so defective can be classified as a positive foreign matter.

The fourth straight line is a fourth-order classification reference, and the foreign matter classified as a defect by the third classification reference is shown on the 2-4 graph showing the area on the x-axis and the y-axis as the intensity, A foreign matter larger than the y value of the fourth straight line at the same x value is defected, and the foreign matter having no strength value is classified as a positive foreign matter.

In addition, according to the first, second, third and fourth classification criteria, a foreign object classified as a bifurcated foreign object is classified into a bifurcated foreign object and a defect according to the relationship between the strength and density of each foreign object, (S3-5).

Since foreign matter classified as defective in the step (S2) may be included in the foreign matter classified as the binary foreign matter according to the first to fourth sorting criteria, it is possible to reduce the determination that the defective article is a good article by including the above step.

The foreign matter classified into two kinds of foreign objects according to the primary, secondary, and tertiary classification standards is shown on the 1-5 graph with the x axis as the density and the y axis as the intensity. Draw a fifth straight line separating character and defect.

A foreign matter whose intensity value is equal to or larger than the y value of the fifth straight line at the same x in the above-mentioned first to fifth graphs is defective, and foreign matter which is not defective can be classified as a positive foreign matter.

The fifth straight line is a fifth-order classification reference, and the foreign matter classified into the two-kind foreign matter by the first to fourth classification standards is shown on the 2-5 graph in which the x-axis is density and the y-axis is intensity, The fifth straight line is drawn on the 2-5 graph, and the foreign matter having a strength value equal to or larger than the y value of the fifth straight line at the same x is defective and the foreign matter is not classified as a positive foreign matter.

Further, the method further includes a step (S3-6) of obtaining a sixth sorting criterion in which the foreign matter classified as a defect according to the fifth sorting criterion is classified again as a double foreign matter and defect according to the relationship between the strength and density of each foreign matter .

1-6 graphs in which the x-axis is dense and the y-axis is the intensity of the foreign matter classified as the defect according to the fifth sorting criterion, and a sixth straight line I draw.

A foreign matter whose intensity value is equal to or larger than the y value of the sixth straight line at the same x in the above-mentioned 1-6 graph is defective, and the foreign matter is classified as a positive foreign matter.

The sixth straight line is a sixth-order classification reference, and a foreign matter classified as a defect by the fifth-order classification reference is shown on the 2-6 graph having the x-axis as density and the y-axis as intensity, , A foreign matter having a strength value equal to or larger than the y value of the sixth straight line at the same x is defective, and a foreign matter having no strength value can be classified as a positive foreign matter.

In addition, in step S3-7, a seventh sorting criterion for classifying a foreign object classified as a bifurcated foreign object according to the above-mentioned sixth classification standard into a bifurcated foreign matter and a defect according to the relationship between the length and width of each foreign object is obtained As shown in FIG.

1-7 graph showing a foreign object classified as a binary foreign material according to the sixth classification standard, wherein the x-axis is the transverse length of the foreign object and the y-axis is the transverse length of the foreign object. Draw a seventh straight line separating defects.

A foreign object whose vertical length value of the foreign object is larger than the y value of the seventh straight line at the same x is defected on the 1-7 graph, and the foreign object is classified as a positive foreign object.

The seventh straight line is a 7th-order classification reference, and similarly, the foreign matter classified by the 6th-order classification standard is displayed on the 2-7 graph with the x-axis being the transverse length of the foreign object and the y- A seventh straight line on the second-seventh graph is drawn and a foreign object having a vertical length value of the foreign object larger than the y value of the seventh straight line at the same x is defected and the foreign object is classified as a positive foreign object .

In addition, in step S3-8, an 8th-order classification criterion for classifying a foreign object classified as a bifurcated foreign object according to the 7th classification standard as a bifurcated foreign matter and a defect according to the relationship between the length and width of each foreign object is obtained As shown in FIG.

The graphs 1-8 showing the foreign objects classified as the bipartite foreign objects according to the seventh sorting standard have the x-axis as the transverse length of the foreign object and the y-axis as the transverse length of the foreign object. Draw an eighth line separating defects.

A foreign object whose vertical length of the foreign object is larger than the y value of the eighth straight line at the same x is defected on the above 1-8 graph, and foreign matter that does not is defective can be classified as a positive foreign object.

The eighth straight line is an 8th-order classification reference, and similarly, a foreign matter classified into a two-kind foreign matter by the seventh-order classification standard is displayed on the 2-8 graph with the x-axis being the transverse length of the foreign object and the y- 8th straight line on the second-eighth graph, foreign objects larger than the y value of the eighth straight line at the same x in the lengthwise direction of the foreign object can be classified as defective foreign objects.

In addition, if a foreign object classified as a defect in accordance with the 8th order classification standard has a transverse length exceeding a predetermined transverse length value as a defect and a transverse length exceeding a predetermined longitudinal length value as a defect, (S3-9).

In the case of foreign objects classified as defects according to the 8th classification standard, the binary foreign objects and defects have a distribution in which they are distinguished from each other based on a specific length value and a specific length value. Therefore, it is possible to distinguish between foreign matter and defect based on a specific value of the width and height.

The determined transverse length value and the lengthwise length value as the defects are a transverse length value and a longitudinal length value that distinguish between a bona fide foreign matter and a defect, and they are not particularly limited and may vary depending on whether a defect is detected with a certain degree of reliability. For example, in order to detect a defect with the highest level of reliability, the minimum width value of the defects may be a predetermined width value as a defect. Likewise, the minimum vertical length value of defects can be a predetermined vertical length value as a defect.

The foreign matter classified as a defect according to the sixth and seventh classification criteria may be further classified as a defect if the width is greater than a predetermined width value as a defect and the length is greater than a predetermined length value determined as a defect have.

According to the sixth and seventh classification criteria, a foreign matter classified as a defect, a bipolar foreign body and a defect are distributed on the basis of a specific length value and a specific length value.

The determined transverse length value and longitudinal length value as the defects are a transverse length value and a longitudinal length value that distinguish between a bona fide foreign matter and a defect.

Thereafter, (S4), foreign matter determined as a positive foreign matter in the foreign substance of the optical film is excluded from the defect in accordance with the obtained information.

As described above, in the step (S3), it is possible to obtain a criterion for sorting both foreign objects and defects, thereby classifying the foreign object into two kinds of foreign objects and defects without peeling off the protective film of the optical film produced in the same line The foreign body can be excluded from defects.

In addition, the positive foreign matter is a foreign matter not a cluster type defect, and the cluster type defect can be classified as a defect beforehand according to the classification criteria.

The cluster type defect refers to a set of foreign objects including a center foreign object when two or more foreign objects exist in a circle having a radius of 5 mm centered on any one foreign object.

An example of cluster defects is shown in FIG. Referring to FIG. 6, the foreign objects 1, 2, and 3 exist inside a circle having a predetermined radius centering on the foreign object 2, so that there are two neighboring foreign objects, so that they belong to a cluster type defect.

Since the cluster type defect is very likely to be a defective product, it is possible to increase the promptness and reliability of the discriminating step of the two-character foreign matter by first discriminating it and not including it as an object of the discriminating step.

In addition, foreign matter satisfying the following formula (3) can be excluded from defects among the foreign objects selected in both the light transmission inspection and the cross-Nicol inspection.

&Quot; (3) "

(Selected area in cross-Nicol test / area selected in light transmission test) ≥ 8.

The foreign matter selected in both the light transmission inspection and the cross-Nicol inspection can be used not only for the foreign objects which are completely identical in the position detected in each inspection but also for the pixels of foreign objects detected in the light transmission inspection and the foreign pixels If the distance is less than 20 mm, it can be regarded as a foreign matter to be selected in both the light transmission test and the cross-Nicol test.

In the case of foreign matter satisfying the above Equation (3), likelihood of being a defective product is also very high. If it is discriminated first, it is possible to improve the promptness and reliability of the step of discriminating foreign objects.

FIG. 7 is a schematic flowchart of a method of determining defects of an optical film according to an embodiment of the present invention including all the steps.

FIG. 7 is a graph showing the binary foreign objects and defects, and a straight line separating the foreign objects from the defect is plotted on the graph,

In FIG. 7, YES is satisfied when each step is satisfied, NO is determined otherwise, and a step is progressed along the following arrow, and in each case, whether or not a bona fide foreign matter and a defect are discriminated is shown in each step.

In Fig. 7, A1 to A8 are the slopes of the classification reference straight lines determined at each step, B1 to B8 are y intercepts, C1 is a predetermined transverse length value as a defect, and C2 is a predetermined vertical length value as a defect.

Further, the present invention provides an apparatus for discriminating a defect of an optical film.

Hereinafter, a defect discrimination apparatus for an optical film according to an embodiment of the present invention will be described in detail.

The light source irradiates light on one side of an optical film on which protective films are laminated on both sides.

The light source may be any light source commonly used in the art, for example, a light emitting diode, a metal halide lamp, a fluorescent lamp, a halogen lamp, and the like, but is not limited thereto.

The photographing apparatus photographs the light irradiated region of the optical film.

The foreign object selecting unit selects foreign objects from the image photographed by the photographing device.

The defect discrimination apparatus for an optical film of the present invention may further comprise a polarizing filter arranged in a crossed Nicols state between the light source and the photographing apparatus as required, and a specific foreign matter discriminating method of the foreign matter discriminating section may be the same as the above- It can be done in a way.

The protective film peeling section peels the protective film on both sides of the optical film.

The information obtaining unit may determine the relationship between the intensity of at least one member selected from the group consisting of the density according to the following formula (1), the thickness and the area according to the following equation (2) Get information about.

Accordingly, a classification criterion for classifying both foreign objects and defects can be obtained, and the method for obtaining the specific classification criterion can be the same as the defect determination method described above.

The judging unit classifies the foreign matter of the optical film on which the protective film is laminated on both sides according to the information obtained by the information obtaining unit, as a bipolar foreign matter and a defect.

As described above, it is possible to obtain a criterion for classifying both foreign objects and defects in the information obtaining unit, and thus, it is possible to classify the foreign matter into defective foreign matter without separating the protective film of the optical film produced in the same line The foreign body which is judged to be a double foreign body can be excluded from the defect.

The judgment unit may classify the cluster type defects as defects before judging according to the classification criterion when sorting the foreign objects with foreign matter and defects.

In addition, the judgment unit may exclude a foreign object selected from both the light transmission inspection and the cross-Nicol inspection from defects satisfying the following expression (3).

&Quot; (3) "

(Selected area in cross-Nicol test / area selected in light transmission test) ≥ 8.

It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to be illustrative of the invention and are not intended to limit the scope of the claims. It will be apparent to those skilled in the art that such variations and modifications are within the scope of the appended claims.

Example

(1) Set classification criteria

An optical film with a protective film on both sides, which was produced by a roll to roll process, was inspected by the length shown in Table 1 below, and a total of 18,959 foreign objects were selected.

The protective film on both sides of the optical film was peeled off and the foreign materials were classified and classified as shown in Table 1 below.

Inspection length of optical film
(Meter) Number of foreign objects (pieces) association Luminescent spot Thread star scratch Sum 2,128 5 865 134 9,116 8,836 18,959

The strength, thickness, density, area, transverse length, and length information of the foreign objects were obtained, and the following classification criteria for separating them into two kinds of foreign objects and defects were obtained.

division inclination Y intercept First straight line -10000 380000 Second straight line 142 -475 Third straight line 10000 -830000 Fourth straight line 10000 -830000 Fifth straight line 0 21 Sixth straight line 0 38.5 Seventh straight 2 -17.01 Eighth straight line One -10.99

division value The predetermined width value One The predetermined length value One

The 18,959 foreign objects were classified again according to the classification criteria, and the defects were marked. The results are shown in Table 4 below.

flaw Bifurcated foreign matter association Luminescent spot Thread star scratch detection marking detection marking detection marking detection marking detection marking 5 5 (100%) 865 865
(100%) 137 137
(100%) 9,116 4,347
(47.7%) 8,836 8,370
(94.7%)

Conventionally, all of the foreign objects are marked as defects. However, as a result of reclassification according to the classification standard, 47.7% of the star objects are marked as defective and 94.7% of the scratch foreign objects are marked as defects.

That is, more than 50% of the stain was marked as defective, and more than 5% of the scratch marks were marked as defective.

(2) Application to optical films manufactured in the same line

A 1000-meter optical film produced in the same line as the optical film was examined by a roll-to-roll process, and 8,460 foreign objects were selected.

As a result of sorting the foreign materials according to the classification standard obtained in Example (1), 6176 foreign objects were marked as defects.

Then, in order to confirm whether or not the foreign object was classified according to the classification criteria, the protective film on both sides of the optical film was peeled off and the 8,460 foreign objects were classified as a false foreign matter and defect.

flaw Bifurcated foreign matter association Luminescent spot Thread star scratch detection marking detection marking detection detection marking detection marking detection 3 3
(100%) 381 381
(100%) 56 56
(100%) 4025 1942
(48.3%) 3995 3747
(93.8%)

Referring to Table 5, it can be seen that when the classification criteria obtained in the above-mentioned Example (1) are applied to the optical film produced in the same line, it is confirmed that the case where the foreign objects are marked with defects at a similar level is reduced.

Claims (26)

(S1) inspecting an optical film on both sides of which a protective film is laminated to confirm whether or not the optical film contains foreign matter;
(S2) peeling off the protective film on both surfaces of the optical film including the foreign object, and classifying the foreign object into a defect with foreign material;
(S3) obtaining information on the relationship between the positive physical property and the defect with respect to intensity and at least one value selected from the group consisting of density according to the following formula (1), thickness and area according to the following equation (2) Obtaining a criterion that classifies the character foreign matter and the defect; And
(S4) a step of removing foreign matter, which is determined to be a positive foreign matter, from the defect in the foreign substance of the optical film in accordance with the obtained information,
[Equation 1]
Density of the foreign object = area of the foreign object / area of the circle with the long axis of the foreign object as the diameter
&Quot; (2) "
Thickness of foreign object = area of foreign object / length of foreign object.
2. The method according to claim 1, wherein the step (S3) includes the step (S3-1) of obtaining a primary classification reference for sorting both positive and negative foreign objects and defects according to the relationship between the intensity and density of each foreign matter, Way.
[3] The method of claim 2, wherein the step (S3) includes: obtaining a secondary classification criterion for classifying a foreign object classified as a defect according to a primary classification standard into a foreign object and a defect according to the relationship between the strength and thickness of each foreign object S3-2). ≪ / RTI >
[3] The method of claim 3, wherein the step (S3) comprises: obtaining a third classification standard for classifying defects classified as defects according to a secondary classification standard into defective foreign objects and defects according to the relationship between strength and area of each foreign object S3-3). ≪ / RTI >
[4] The method of claim 4, wherein the step (S3) includes: obtaining a fourth classification standard for classifying defects classified as defects according to a tertiary classification standard into defective foreign objects and defects according to the relationship between strength and area of each foreign object (S3-4). ≪ / RTI >
[6] The method of claim 5, wherein the step (S3) further comprises the step of: separating the foreign matter classified as a bona fide foreign matter according to the primary, secondary, and tertiary classification criteria, Further comprising a step (S3-5) of obtaining a fifth-order classification criterion for classifying the optical film into defects.
[6] The method of claim 6, wherein the step (S3) includes: obtaining a sixth classification standard for classifying defects classified as defects according to the fifth classification standard into defective foreign objects and defects according to the relationship between strength and density of each foreign object (S3-6). ≪ / RTI >
[7] The method according to claim 7, wherein the step (S3) is a step of sorting a foreign object classified as a bifurcated foreign object according to the sixth classification standard into a foreign object and a defect according to a relationship between the length and width of each foreign object, And obtaining a reference (S3-7).
[8] The method according to claim 8, wherein the step (S3) further comprises the step of classifying the foreign objects classified as a bifurcated foreign object according to the 7th order classification into 8 kinds of foreign objects and defects according to the relationship between the length and width of each foreign object And obtaining a reference (S3-8).
[9] The method of claim 9, wherein the step (S3) includes the step of, if the length of the foreign object classified as a defect according to the eighth order classification exceeds a predetermined length value as a defect, Further comprising a step (S3-9) of obtaining a 9th-order classification criterion classified as a defect.
[11] The method of claim 10, wherein the step (S3-9) comprises: determining that the foreign matter classified as a defect according to the sixth and seventh order criteria has a width greater than a predetermined width value as a defect, And when the value is exceeded, the defect is further classified into a defect.
The method according to claim 1, wherein, in the step (S4), the double-object foreign matter is a foreign object other than a cluster type defect, and if the foreign matter exists in a circle having a radius of 5 mm around the foreign object, Wherein the foreign matter is a set of foreign matter including foreign matter.
2. The method of claim 1, wherein the foreign matter satisfying the following formula (3) is selected from defects in the foreign matter selected in both the light transmission inspection and the cross-Nicol inspection in the step (S4)
&Quot; (3) "
(Selected area in cross-Nicol test / area selected in light transmission test) ≥ 8.
A light source for irradiating light to one surface of an optical film on which protective films are stacked on both surfaces;
A photographing device for photographing a light irradiated portion of the optical film;
A foreign object sorting unit for sorting foreign objects in the image photographed by the photographing apparatus;
A protective film peeling unit for peeling the protective film on both surfaces of the optical film;
Information on the relationship between the intensity of at least one selected from the group consisting of the density according to the following formula (1), the thickness according to the following formula (2), and the area and the intensity after the protective film is removed from the protective film An information obtaining unit to obtain; And
And a judging section for classifying the foreign object of the optical film in which the protective film is laminated on both sides according to the information obtained by the information obtaining section, into a bipolar foreign matter and a defect.
[Equation 1]
Density of the foreign object = area of the foreign object / area of the circle with the long axis of the foreign object as the diameter
&Quot; (2) "
Thickness of foreign object = area of foreign object / length of foreign object.
15. The apparatus according to claim 14, wherein the information obtaining unit obtains a primary classification reference that classifies both positive and negative foreign objects and defects according to the relationship between intensity and density of each foreign object.
The information obtaining apparatus according to claim 15, wherein the information obtaining unit obtains a second classification standard for classifying a foreign object classified as a defect according to a primary classification standard into a foreign object and a defect according to the relationship between the intensity and thickness of each foreign object, .
The information obtaining apparatus according to claim 16, wherein the information obtaining unit further obtains a third classification standard for classifying the foreign objects classified as defects according to the secondary classification standard into defective foreign objects and foreign objects according to the relationship between the strength and area of each foreign object, .
The information obtaining unit according to claim 17, wherein the information obtaining unit further obtains a fourth classification standard for classifying the foreign objects classified as defects according to the third classification standard into defective foreign objects and defects according to the relationship between the strength and area of each foreign object, .
[Claim 18] The information obtaining unit of claim 18, wherein the information obtaining unit classifies the foreign objects classified as the bona fide foreign objects according to the first, second, third, and fourth classification criteria as the bona fide foreign matter and defect according to the relationship between the strength and density of each foreign object Wherein the optical system is further provided with a fifth-order classification standard.
The information obtaining unit according to claim 19, wherein the information obtaining unit obtains the sixth classification reference for further classifying the foreign matter classified as the defect according to the fifth classification reference as the defect of foreign matter and defect according to the relationship between the intensity and density of each foreign object, Film defects discrimination device.
[Claim 20] The information obtaining unit of claim 20, wherein the information obtaining unit recovers the seventh order classification based on the relationship between the length and width of each foreign object, Further obtaining a defect discrimination device for an optical film.
[Claim 21] The information obtaining unit according to claim 21, wherein the information obtaining unit obtains an 8th classification standard for classifying a foreign object classified as a bona fide foreign object according to the 7th classification standard as a bifurcated foreign object and a defect according to the relationship between the length and width of each foreign object Further obtaining a defect discrimination device for an optical film.
The information collecting apparatus according to claim 22, wherein the information obtaining unit determines that the foreign object classified as a defect according to the eighth order classification exceeds a predetermined width value as a defect of the width, and the defect is a defect when the height is more than a predetermined value The defect discrimination device of the optical film, which further obtains the ninth order classification classifying.
26. The image processing method according to claim 23, wherein the information obtaining unit detects the foreign matter classified as a defect in accordance with the sixth and seventh sorting criteria, when the width is greater than a predetermined width value as a defect and the length is greater than a predetermined length value as a defect The defect discrimination apparatus for an optical film further classified into defects.
[Claim 15] The apparatus of claim 14, wherein the judging unit classifies the set of foreign objects including a center foreign object as a defect when two or more foreign objects exist in a circle having a radius of 5 mm around any foreign object, .
15. The apparatus of claim 14, further comprising a polarizing filter disposed in a cross-Nicol state between the light source and the imaging device,
Wherein the judging unit excludes, from defects, foreign objects satisfying the following formula (3) among foreign objects selected in both the light transmission inspection and the cross-Nicol inspection:
&Quot; (3) "
(Selected area in cross-Nicol test / area selected in light transmission test) ≥ 8.

Images