JP2001349839A - Inspection method for polarizing film defect - Google Patents
Inspection method for polarizing film defectInfo
- Publication number
- JP2001349839A JP2001349839A JP2000170301A JP2000170301A JP2001349839A JP 2001349839 A JP2001349839 A JP 2001349839A JP 2000170301 A JP2000170301 A JP 2000170301A JP 2000170301 A JP2000170301 A JP 2000170301A JP 2001349839 A JP2001349839 A JP 2001349839A
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- Japan
- Prior art keywords
- polarizing film
- polarizing
- light
- polarization
- defect
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Liquid Crystal (AREA)
- Investigating Materials By The Use Of Optical Means Adapted For Particular Applications (AREA)
- Polarising Elements (AREA)
Abstract
Description
【0001】[0001]
【発明の属する技術分野】本発明は、液晶表示素子や偏
光フィルタなどに用いられる偏光フィルム偏光フィルム
の欠陥検査方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting defects of a polarizing film used for a liquid crystal display device or a polarizing filter.
【0002】[0002]
【従来の技術】従来から、液晶表示素子や光学的な偏光
フィルタなどには、合成樹脂フィルムを延伸して製造す
る偏光フィルムが用いられている。図5は液晶表示の原
理を示し、図6は偏光フィルタの原理を示す。2. Description of the Related Art Conventionally, a polarizing film manufactured by stretching a synthetic resin film has been used for a liquid crystal display device or an optical polarizing filter. FIG. 5 shows the principle of a liquid crystal display, and FIG. 6 shows the principle of a polarizing filter.
【0003】図5は、(a)で光を透過する状態、
(b)で光を遮断する状態を示す。2枚の偏光板1,2
は、入射光のうちで選択的に偏光成分を透過させる偏光
軸方向a,bが互いに直交するように、間隔をあけて配
置される。偏光板1,2間には、2枚の透明電極3,4
が間隔をあけて配置される。透明電極3,4間には、液
晶層5が充填される。透明電極3,4で相互に対向して
液晶層5に接する表面には、配向膜6,7がそれぞれ形
成されている。配向膜6,7は、直交する方向に配向性
が付与されている。FIG. 5A shows a state in which light is transmitted in FIG.
(B) shows a state in which light is blocked. Two polarizing plates 1 and 2
Are arranged at intervals so that the polarization axis directions a and b for selectively transmitting the polarization component of the incident light are orthogonal to each other. Between the polarizing plates 1 and 2, two transparent electrodes 3 and 4
Are spaced apart. A liquid crystal layer 5 is filled between the transparent electrodes 3 and 4. Alignment films 6 and 7 are formed on the surfaces of the transparent electrodes 3 and 4 that face each other and are in contact with the liquid crystal layer 5, respectively. The alignment films 6 and 7 are provided with an orientation in a direction orthogonal to the direction.
【0004】図5(a)に示す状態では、透明電極3,
4間には電圧が印加されておらず、液晶層5中の液晶分
子8は、配向膜6,7の表面で配向性が付与されている
方向にそれぞれ並ぶ。液晶層5の両側では液晶分子8が
並ぶ方向が直交するので、液層層5の厚さ方向の全体で
は、液晶分子8の方向が連続的に変化する。このため、
偏光板1で偏光軸方向aと偏光方向が一致する偏光成分
が選択されても、液晶層5を通過する間に90°偏光方
向が変わり、偏光板2の偏光軸方向bにも一致して、偏
光板2を通過することができる。[0004] In the state shown in FIG.
No voltage is applied between the liquid crystal layers 4, and the liquid crystal molecules 8 in the liquid crystal layer 5 are arranged in the direction in which the alignment is provided on the surfaces of the alignment films 6 and 7, respectively. Since the directions in which the liquid crystal molecules 8 are arranged on both sides of the liquid crystal layer 5 are orthogonal to each other, the direction of the liquid crystal molecules 8 continuously changes in the entire thickness direction of the liquid layer 5. For this reason,
Even if a polarization component whose polarization direction coincides with the polarization axis direction a is selected in the polarization plate 1, the polarization direction changes by 90 ° while passing through the liquid crystal layer 5 and coincides with the polarization axis direction b of the polarization plate 2. , Through the polarizing plate 2.
【0005】図5(b)に示す状態では、透明電極3,
4間に電圧が印加され、液晶層5中の液晶分子8は、透
明電極3,4間に形成される電界の方向に並ぶ。光が液
晶層5中を通過しても偏光方向は変化しない。このた
め、偏光板1で偏光軸方向aと偏光方向が一致する偏光
成分が選択ると、液晶層5を通過しても偏光方向は変わ
らず、偏光板2の偏光軸方向bとは直交している状態の
ままであるので、偏光板2を通過することができない。[0005] In the state shown in FIG.
A voltage is applied between the transparent electrodes 4 and the liquid crystal molecules 8 in the liquid crystal layer 5 are arranged in the direction of the electric field formed between the transparent electrodes 3 and 4. Even if light passes through the liquid crystal layer 5, the polarization direction does not change. Therefore, when a polarization component whose polarization direction coincides with the polarization axis direction a is selected in the polarizing plate 1, the polarization direction does not change even after passing through the liquid crystal layer 5, and is orthogonal to the polarization axis direction b of the polarizing plate 2. Therefore, the light cannot pass through the polarizing plate 2.
【0006】以上のような液晶表示は、ねじりネマチッ
ク型からTN型と呼ばれ、またノーマリホワイトモード
と呼ばれ、多種類の液晶表示でも最も代表的なものの一
つである。他の方式の液晶表示でも、偏光を利用するこ
とが多く、偏光板1,2は、Liquid Crystal Device か
らLCDと略称される液晶表示素子を用いる液晶ディス
プレイには不可欠の構成材料である。今日、LCDは、
OA機器、車載計器、液晶テレビ、液晶プロジェクタ等
に幅広く使用されている。The liquid crystal display as described above is called a TN type from a twisted nematic type and is called a normally white mode, and is one of the most typical types of liquid crystal displays. Even in other types of liquid crystal displays, polarized light is often used, and the polarizing plates 1 and 2 are indispensable constituent materials for a liquid crystal display using a liquid crystal display element abbreviated as LCD from Liquid Crystal Device. Today, LCDs
It is widely used in OA equipment, in-vehicle instruments, liquid crystal televisions, liquid crystal projectors, and the like.
【0007】図6は、2枚の偏光フィルタ9a,9bを
用いて、(a)に示すように光を透過させたり、(b)
に示すように光を遮断したりする状態を示す。(a)で
は2枚の偏光フィルタ9a,9bの偏光軸方向a,bが
平行であり、(b)では2枚の偏光フィルタ9a,9b
の偏光軸方向a,bが直交している。(b)に示すよう
に偏光軸方向a,bが直交する状態は、クロスニコルと
呼ばれる。偏光フィルタ9a,9bは、図6に示すよう
な光学的特性を利用しうる分野で、単体あるいは組合せ
て使用される。FIG. 6 shows that two polarizing filters 9a and 9b are used to transmit light as shown in FIG.
The state in which light is blocked as shown in FIG. In (a), the polarization axis directions a and b of the two polarizing filters 9a and 9b are parallel, and in (b) two polarizing filters 9a and 9b.
Are perpendicular to each other. The state where the polarization axis directions a and b are orthogonal to each other as shown in (b) is called crossed Nicols. The polarizing filters 9a and 9b are used alone or in combination in a field where optical characteristics as shown in FIG. 6 can be used.
【0008】図7は、図5に示す液晶表示で、偏光板
1,2として使用される偏光フィルム10の概略的な構
成の一例を示す。光学的な偏光特性は、PVA(ポリビ
ニルアルコール:PolyVinyl Alcohol )層11に付与さ
れている。PVA層11の両側には補強用のTAC(シ
アヌル酸トリアリル:TriAllyl Cyanurate)層12,1
3が接合され、全体でポラライザ(PL:偏光子)を構
成している。PLとしては、このような3層構造ばかり
ではなく、5層構造なども用いられる。図6に示す偏光
フィルタ9a,9bは、PLの状態で使用する。PLの
一方表面には保護用のプロテクトフィルム14が接合さ
れる。PLの他方表面には、粘着剤15が貼付けられ、
セパレートフィルム16で覆われている。図5の透明電
極3,4の表面には、セパレートフィルム16を剥がし
て、粘着剤15によって貼付けることができる。FIG. 7 shows an example of a schematic configuration of a polarizing film 10 used as the polarizing plates 1 and 2 in the liquid crystal display shown in FIG. Optical polarization characteristics are given to a PVA (PolyVinyl Alcohol) layer 11. On both sides of the PVA layer 11, TAC (Triallyl Cyanurate) layers 12, 1 for reinforcement are used.
3 are joined to form a polarizer (PL: polarizer) as a whole. As the PL, not only such a three-layer structure but also a five-layer structure is used. The polarization filters 9a and 9b shown in FIG. 6 are used in the state of PL. A protection film 14 for protection is bonded to one surface of the PL. An adhesive 15 is attached to the other surface of the PL,
It is covered with a separate film 16. The separate film 16 can be peeled off from the surfaces of the transparent electrodes 3 and 4 in FIG.
【0009】図5に示すような液晶表示に偏光板1,2
として用いる偏光フィルム10では、光の透過を阻害す
るような異物付着などの欠陥が存在していないことが必
要である。欠陥が存在していると、その部分では液晶層
5の液晶分子8を電界で制御しても、全体としての光の
状態を変えることができなくなり、画像表示の一部が欠
けて表示品質が劣化するからである。このため、偏光フ
ィルム10の製造工程では、欠陥の検査が厳重に行われ
ている。The polarizing plates 1 and 2 are arranged on a liquid crystal display as shown in FIG.
It is necessary that the polarizing film 10 to be used as above does not have a defect such as adhesion of a foreign substance that inhibits light transmission. If there is a defect, even if the liquid crystal molecules 8 of the liquid crystal layer 5 are controlled by an electric field, the state of the light cannot be changed as a whole, and a part of the image display will be lost and the display quality will be reduced. This is because it deteriorates. For this reason, in the manufacturing process of the polarizing film 10, inspection for defects is strictly performed.
【0010】[0010]
【発明が解決しようとする課題】図7に示すような偏光
フィルム10の検査は、表面を拡大して観察することに
よって行われる。しかしながら、偏光フィルム10は、
複数層を積層して形成されており、層間に微小な異物が
紛れ込むことがあり得る。表面を拡大して観察しても、
内部の微小な異物などの欠陥を検出することは非常に困
難である。微小な異物は、光を遮断するよりも回析させ
て偏光方向を変化させることもある。微小な異物による
遮光で、本来明るい画像中に微小な黒点が表示される場
合よりも、微小な異物による回析で、本来暗い画像中に
微小な輝点や白点が表示される場合の方が目立ちやす
い。したがって、偏光フィルム10内部の微小な欠陥を
検出しやすい検査方法の確立が強く要望されている。The inspection of the polarizing film 10 as shown in FIG. 7 is performed by observing the surface enlarged. However, the polarizing film 10
It is formed by laminating a plurality of layers, and a minute foreign matter may enter between the layers. Even if the surface is magnified and observed,
It is very difficult to detect defects such as minute foreign matter inside. A minute foreign substance may change the polarization direction by diffracting light rather than blocking it. A case in which minute luminescent spots or white points are displayed in an originally dark image due to diffraction by minute foreign objects, rather than a case where minute black points are displayed in an originally bright image due to shading by a minute foreign object. Is noticeable. Therefore, there is a strong demand for establishing an inspection method that can easily detect minute defects inside the polarizing film 10.
【0011】本発明の目的は、内部の微小な欠陥を容易
に検出することができる偏光フィルムの検査方法を提供
することである。An object of the present invention is to provide a method for inspecting a polarizing film, which can easily detect minute internal defects.
【0012】[0012]
【課題を解決するための手段】本発明は、入射される光
のうち予め定める偏光軸方向の偏光成分のみを選択的に
透過させる偏光フィルムに、光源からの光を透過させ、
該偏光フィルムを透過した光を、該偏光軸とほぼ直交す
る方向の偏光軸を有するように配置される偏光板に導
き、該偏光板を透過した光を観察して、全体的な視野と
明るさの異なる部分が存在するとき、該視野よりも明る
ければ該偏光フィルムの偏光特性を示す部分よりも観察
側に存在する欠陥であり、該視野よりも暗ければ該偏光
フィルムの偏光特性を示す部分よりも光源側に存在する
欠陥であると判断することを特徴とする偏光フィルムの
欠陥検査方法である。According to the present invention, a light from a light source is transmitted through a polarizing film which selectively transmits only a polarized light component in a predetermined polarization axis direction among incident light,
The light transmitted through the polarizing film is guided to a polarizing plate disposed so as to have a polarizing axis in a direction substantially orthogonal to the polarizing axis. When there is a different portion, if it is brighter than the visual field, it is a defect present on the observation side than the part showing the polarization characteristics of the polarizing film, and if it is darker than the visual field, it shows the polarizing characteristics of the polarizing film. A defect inspection method for a polarizing film, characterized in that it is determined that the defect is located closer to the light source than the portion.
【0013】本発明に従えば、光源からの光を偏光フィ
ルムに透過させることによって、偏光フィルムの偏光軸
方向の偏光成分が選択される。選択された偏光成分は、
偏光軸方向がほぼ直交する偏光板を透過するので、大部
分が阻止され、観察すると全体的には暗い視野になる。
偏光フィルムの偏光特性を示す部分よりも観察側に欠陥
が存在すれば、欠陥の部分で偏光方向が変わり、偏光板
を通過する割合が増えて、全体的な視野よりも明るく見
えるようになる。偏光フィルムの偏光特性を示す部分よ
りも光源側に欠陥が存在すれば、欠陥の部分で光量が減
少し、偏光板を通過する割合がさらに減少して、全体的
な視野よりも暗く見えるようになる。したがって、積層
構造の偏光フィルムでは、内部の偏光特性を示す層の観
察側または光源側に存在する微小な欠陥を容易に検出す
ることができる。According to the present invention, the polarization component in the direction of the polarization axis of the polarizing film is selected by transmitting the light from the light source through the polarizing film. The selected polarization component is
Since the light passes through a polarizing plate whose polarization axis directions are substantially orthogonal to each other, most of the light is blocked, and the observation results in a dark field as a whole.
If there is a defect on the observation side relative to the portion of the polarizing film exhibiting the polarization characteristics, the polarization direction changes at the defect portion, and the ratio of passing through the polarizing plate increases, so that the overall visual field becomes brighter. If there is a defect on the light source side than the part showing the polarization characteristics of the polarizing film, the amount of light decreases at the defect part, the ratio of passing through the polarizing plate further decreases, so that it looks darker than the entire field of view. Become. Therefore, in the polarizing film having the laminated structure, minute defects existing on the observation side or the light source side of the layer exhibiting the internal polarization characteristics can be easily detected.
【0014】さらに、本発明は、入射される光のうち予
め定める偏光軸方向の偏光成分のみを選択的に透過させ
る偏光フィルムに、該偏光軸とほぼ直交する方向の偏光
軸を有するように構成される光源からの光を透過させ、
該偏光フィルムを透過した光を観察して、全体的な視野
と明るさの異なる部分が存在するとき、該視野よりも暗
ければ該偏光フィルムの偏光特性を示す部分よりも観察
側に存在する欠陥であり、該視野よりも明るければ該偏
光フィルムの偏光特性を示す部分よりも光源側に存在す
る欠陥であると判断することを特徴とする偏光フィルム
の欠陥検査方法である。Further, according to the present invention, a polarizing film which selectively transmits only a polarized light component in a predetermined polarization axis direction of incident light has a polarization axis in a direction substantially orthogonal to the polarization axis. Through the light from the light source
Observing the light transmitted through the polarizing film, when there is a part having a different overall brightness from the visual field, if it is darker than the visual field, it is present on the observation side than the part showing the polarizing characteristics of the polarizing film. A defect inspection method for a polarizing film, wherein the defect is determined to be a defect that is present on the light source side of a portion showing the polarization characteristics of the polarizing film if the defect is brighter than the visual field.
【0015】本発明に従えば、入射される光のうち予め
定める偏光軸方向の偏光成分のみを選択的に透過させる
偏光フィルムに、該偏光軸とほぼ直交する方向の偏光軸
を有するように構成される光源からの光を透過させて
も、大部分が阻止され、透過光を観察すると全体的には
暗い視野になる。偏光フィルムの偏光特性を示す部分よ
りも光源側に欠陥が存在すれば、欠陥の部分で偏光方向
が変わり、偏光フィルムを通過する割合が増えて、全体
的な視野よりも明るく見えるようになる。偏光フィルム
の偏光特性を示す部分よりも観察側に欠陥が存在すれ
ば、欠陥の部分で光量が減少し、偏光フィルムを通過す
る割合がさらに減少して、全体的な視野よりも暗く見え
るようになる。したがって、積層構造の偏光フィルムで
は、内部の偏光特性を示す層の光源側または観察側に存
在する微小な欠陥を容易に検出することができる。According to the present invention, the polarizing film for selectively transmitting only the polarized light component in the direction of the predetermined polarization axis of the incident light has a polarization axis in a direction substantially orthogonal to the polarization axis. Even if light from a light source is transmitted, most of the light is blocked, and when the transmitted light is observed, an overall dark field is obtained. If there is a defect on the light source side relative to the portion showing the polarization characteristics of the polarizing film, the polarization direction changes at the defect portion, the ratio of passing through the polarizing film increases, and the entire field of view looks brighter. If there is a defect on the observation side rather than the part showing the polarization characteristics of the polarizing film, the amount of light decreases at the defect part, the rate of passing through the polarizing film further decreases, so that it looks darker than the overall field of view. Become. Therefore, in the polarizing film having the laminated structure, a minute defect existing on the light source side or the observation side of the layer exhibiting the internal polarization characteristics can be easily detected.
【0016】また本発明で、前記偏光フィルムは、偏光
性の光学特性を有する層の両表面に、透明な保護層をそ
れぞれ貼合せて形成されており、前記欠陥は、該貼合せ
部に存在する異物を含むことを特徴とする。In the present invention, the polarizing film is formed by laminating a transparent protective layer on both surfaces of a layer having a polarizing optical characteristic, and the defect exists in the laminating part. It is characterized in that it contains a foreign substance that does.
【0017】本発明に従えば、偏光性の光学特性を有す
る層の両表面に、透明な保護層をそれぞれ貼合せて形成
される偏光フィルムで、貼合せ部に存在する異物を、容
易に検出することができる。このような異物は、偏光フ
ィルムとしては内部に存在し、外観の検査では判りにく
いけれども、本発明では存在する方向も含めて、容易に
検出することができる。According to the present invention, a polarizing film formed by laminating a transparent protective layer on both surfaces of a layer having a polarizing optical characteristic can easily detect a foreign substance present in a lamination portion. can do. Such a foreign substance is present inside the polarizing film and is difficult to understand by inspection of the appearance, but can be easily detected in the present invention, including the direction in which it exists.
【0018】[0018]
【発明の実施の形態】図1は、本発明の実施の一形態と
しての偏光フィルムの欠陥検査方法を概略的に示す。欠
陥検査の対象となる偏光フィルム20は、大略的に水平
な状態で、下方の光源21からの光を透過する。偏光フ
ィルム20を透過した光は、偏光板22または偏光板2
3を介して観察する。偏光フィルム20は、図7に示す
偏光フィルム10と基本的に同等の構成を有し、内部の
偏光層24が光学的な偏光特性を有する。偏光層24の
偏光特性は、偏光軸24aの方向の偏光成分を選択的に
透過するように形成されている。したがって、光源21
からの光が等方性であっても、偏光フィルム20に透過
させることによって、偏光フィルム20の偏光軸24a
方向の偏光成分が選択される。FIG. 1 schematically shows a polarizing film defect inspection method as one embodiment of the present invention. The polarizing film 20 to be subjected to the defect inspection transmits light from the lower light source 21 in a substantially horizontal state. The light transmitted through the polarizing film 20 is reflected by the polarizing plate 22 or the polarizing plate 2.
Observe through 3. The polarizing film 20 has basically the same configuration as the polarizing film 10 shown in FIG. 7, and the inside polarizing layer 24 has optical polarization characteristics. The polarization characteristics of the polarization layer 24 are formed so as to selectively transmit the polarization component in the direction of the polarization axis 24a. Therefore, the light source 21
Is transmitted through the polarizing film 20 even when the light from the polarizing film 20 is isotropic.
The polarization component of the direction is selected.
【0019】偏光フィルム20の上方には、偏光軸方向
が偏光フィルム20と90°異なる偏光板22または8
0°異なる偏光板23が配置される。偏光フィルム20
で選択された偏光成分は、偏光軸方向がほぼ直交する偏
光板22,23を通過するので、大部分が阻止され、観
察すると暗い視野になる。偏光フィルム20の偏光特性
を示す部分である偏光層24よりも光源21側に欠陥で
ある下の異物25が存在すれば、下の異物25の部分で
光量が減少し、偏光板22,23を通過する割合がさら
に減少して暗く見えるようになる。偏光フィルム20の
偏光特性を示す部分である偏光層24よりも観察側に欠
陥である上の異物26が存在すれば、上の異物26の部
分で偏光方向が変わり、偏光板22,23を通過する割
合が増えて明るく見えるようになる。Above the polarizing film 20, a polarizing plate 22 or 8 whose polarizing axis direction differs from that of the polarizing film 20 by 90 °.
Polarizing plates 23 different by 0 ° are arranged. Polarizing film 20
Since the polarized light component selected in (1) passes through the polarizing plates 22 and 23 whose polarization axis directions are substantially orthogonal to each other, most of the polarized light component is blocked, and a dark field is observed when observed. If there is a lower foreign matter 25 which is a defect on the light source 21 side of the polarizing layer 24 which is a part showing the polarization characteristics of the polarizing film 20, the amount of light is reduced at the lower foreign matter 25 part, and the polarizing plates 22 and 23 are removed. The passing rate is further reduced so that it appears dark. If there is a foreign matter 26 which is a defect on the observation side of the polarizing layer 24 which is a part showing the polarization characteristics of the polarizing film 20, the polarization direction changes at the foreign matter 26 above and passes through the polarizing plates 22 and 23. The rate at which they do so increases, making them appear brighter.
【0020】図2は、図1の偏光板22,23を通して
見る下の異物25および上の異物26の像を示す。図2
(a)は偏光板22を通過した像を示し、図2(b)は
偏光板23を通過した像を示す。上の異物26は全体的
な視野27に比べて明るく見え、下の異物25は全体的
な視野27に比べて暗く見える。ただし、図2(a)で
は、視野27がかなり暗いので、明るい上の異物26は
極めて明瞭に検出することができるけれども、下の異物
25はあまり明瞭には検出することができない可能性が
ある。図2(b)では、視野27が少し明るくなるの
で、下の異物25によって暗くなる部分を、より明瞭に
検出することができる。FIG. 2 shows an image of the lower foreign substance 25 and the upper foreign substance 26 viewed through the polarizing plates 22 and 23 of FIG. FIG.
2A shows an image that has passed through the polarizing plate 22, and FIG. 2B shows an image that has passed through the polarizing plate 23. The upper foreign matter 26 looks brighter than the overall visual field 27, and the lower foreign matter 25 looks darker than the overall visual field 27. However, in FIG. 2A, since the visual field 27 is quite dark, the bright foreign matter 26 can be detected very clearly, but the lower foreign matter 25 may not be detected very clearly. . In FIG. 2B, since the field of view 27 is slightly brighter, the portion darkened by the foreign matter 25 below can be more clearly detected.
【0021】なお、図2(b)で視野27の明るさは、
偏光板23の偏光軸が偏光フィルム20の偏光軸24a
となす角度に応じて変化する。したがって、角度の80
°はあくまでも一例であり、90°に近い範囲で、下の
異物25も上の異物26もともに検出可能な明るさとな
るように、調整すればよい。The brightness of the visual field 27 in FIG.
The polarizing axis of the polarizing plate 23 is the polarizing axis 24a of the polarizing film 20.
It changes according to the angle formed. Therefore, an angle of 80
° is merely an example, and adjustment may be made so that both the lower foreign substance 25 and the upper foreign substance 26 have a detectable brightness within a range close to 90 °.
【0022】図3は、本発明の実施の他の形態としての
偏光フィルムの欠陥検査方法を概略的に示す。本実施形
態で、図1の実施形態に対応する部分には同一の参照符
を付し、重複する説明を省略する。欠陥検査の対象とな
る偏光フィルム20は、大略的に水平な状態で、下方の
光源21から偏光板22を通った光が入射する。光源2
1は等方性であっても、偏光板22を透過した光は、偏
光板22の偏光軸方向の偏光成分が選択され、実質的に
偏光性の光源からの光が入射されることになる。偏光板
22の偏光軸の方向と、偏光フィルム20の偏光軸24
aの方向とは、ほぼ直交するようにしておく。FIG. 3 schematically shows a defect inspection method for a polarizing film as another embodiment of the present invention. In the present embodiment, portions corresponding to the embodiment of FIG. 1 are denoted by the same reference numerals, and redundant description will be omitted. Light passing through a polarizing plate 22 from a lower light source 21 is incident on the polarizing film 20 to be inspected in a substantially horizontal state. Light source 2
Although 1 is isotropic, as for the light transmitted through the polarizing plate 22, a polarization component in the direction of the polarization axis of the polarizing plate 22 is selected, and light from a substantially polarizing light source is incident. . The direction of the polarization axis of the polarizing plate 22 and the polarization axis 24 of the polarizing film 20
The direction of a is set so as to be substantially orthogonal.
【0023】偏光フィルム20の下方には、偏光軸方向
がほぼ直交する偏光成分の光が入射するので、大部分が
阻止され、偏光フィルム20の上方で観察すると暗い視
野になる。偏光フィルム20の偏光特性を示す部分であ
る偏光層24よりも、偏光性の光源である偏光板22側
に、欠陥である下の異物25が存在すれば、下の異物2
5の部分で偏光成分の偏光軸の方向が変化し、偏光フィ
ルム20を通過する割合が増えて明るく見えるようにな
る。偏光フィルム20の偏光特性を示す部分である偏光
層24よりも観察側に欠陥である上の異物26が存在す
れば、上の異物26の部分で光量がさらに減少して暗く
見えるようになる。Since light having a polarization component whose polarization axis direction is substantially orthogonal to the polarizing film 20 is incident on the lower part of the polarizing film 20, most of the light is blocked. If the lower foreign matter 25 which is a defect is present on the side of the polarizing plate 22 which is a polarizing light source than the polarizing layer 24 which is a part showing the polarization characteristics of the polarizing film 20, the lower foreign matter 2
At part 5, the direction of the polarization axis of the polarization component changes, and the ratio of passing through the polarizing film 20 increases, so that the image looks bright. If there is a foreign matter 26 which is a defect on the observation side of the polarizing layer 24, which is a part showing the polarization characteristics of the polarizing film 20, the amount of light is further reduced at the foreign matter 26 above and the part looks dark.
【0024】図4は、図3の偏光フィルム20を通して
見る下の異物25および上の異物26の像を示す。下の
異物25は全体的な視野27に比べて明るく見え、上の
異物26は全体的な視野27に比べて暗く見える。偏光
板22と偏光フィルム20との間の偏光軸の角度を90
°にすれば、視野27がかなり暗くなるので、明るい下
の異物25は極めて明瞭に検出することができるけれど
も、上の異物26はあまり明瞭には検出することができ
ない可能性がある。偏光軸の角度を90°からずらせ
ば、視野27が少し明るくなるので、上の異物26によ
って暗くなる部分を、より明瞭に検出することができ
る。すなわち、本実施形態でも、図4の視野27の明る
さは、偏光板22の偏光軸が偏光フィルム20の偏光軸
24aとなす角度に応じて変化する。したがって、偏光
軸間の角度を調整すれば、積層構造の偏光フィルム20
では、内部の偏光特性を示す偏光層24の観察側または
光源側に存在する微小な欠陥を容易に検出することがで
きる。FIG. 4 shows an image of the lower foreign substance 25 and the upper foreign substance 26 viewed through the polarizing film 20 of FIG. The lower foreign matter 25 looks brighter than the overall visual field 27, and the upper foreign matter 26 looks darker than the overall visual field 27. The angle of the polarization axis between the polarizing plate 22 and the polarizing film 20 is set to 90.
In this case, since the visual field 27 becomes considerably darker, the bright lower foreign matter 25 can be detected very clearly, but the upper foreign matter 26 may not be detected very clearly. If the angle of the polarization axis is shifted from 90 °, the field of view 27 becomes slightly brighter, so that the portion darkened by the foreign matter 26 above can be more clearly detected. That is, also in the present embodiment, the brightness of the visual field 27 in FIG. 4 changes according to the angle between the polarization axis of the polarizing plate 22 and the polarization axis 24 a of the polarizing film 20. Therefore, by adjusting the angle between the polarization axes, the polarizing film 20 having a laminated structure can be obtained.
Thus, a minute defect existing on the observation side or the light source side of the polarizing layer 24 exhibiting the internal polarization characteristics can be easily detected.
【0025】なお、図1および図3の実施形態では、偏
光フィルム20を大略的に水平に下状態で、下方から上
方に光を透過させているけれども、検査時の光の方向が
下から上に限定されないことはもちろんである。また、
観察は人が肉眼で行うばかりではなく、カメラなどで撮
像した画像信号に基づく画像処理で自動的に検出させる
ことができる。In the embodiment shown in FIGS. 1 and 3, light is transmitted upward from the bottom while the polarizing film 20 is in a substantially horizontal state, but the direction of light at the time of inspection is from the bottom to the top. Of course, it is not limited to. Also,
Observation can not only be performed by the naked eye but also automatically detected by image processing based on an image signal captured by a camera or the like.
【0026】また、図1の実施形態で、偏光板22を光
源21側に移動させれば、図3の実施形態に一致する。
したがって、一方の配置で暗くなって見にくい欠陥で
も、他方の配置では明るくなって見やすくなる。また、
明るくなる場合は、欠陥部分での偏光軸方向の変化によ
るので、遮光性がない透明な異物や欠陥であっても、容
易に検出することができる。Further, in the embodiment of FIG. 1, if the polarizing plate 22 is moved to the light source 21 side, it corresponds to the embodiment of FIG.
Therefore, a defect that is dark and difficult to see in one arrangement is bright and easy to see in the other arrangement. Also,
When the light becomes bright, it depends on the change in the direction of the polarization axis at the defect portion. Therefore, even a transparent foreign substance or defect having no light shielding property can be easily detected.
【0027】さらに、偏光フィルタ20の用途として、
液晶表示素子へ使用し、しかも液晶表示素子として画像
表示を行う表面側か裏面側かが判明していれば、使用状
態で目立つ側の欠陥で明るくなるような配置で検査を行
うこともできる。Further, as an application of the polarizing filter 20,
If it is used for a liquid crystal display element and the front side or the back side on which an image is to be displayed as a liquid crystal display element is known, the inspection can be performed in an arrangement in which a defect on the side conspicuous in use state makes the display brighter.
【0028】[0028]
【発明の効果】以上のように本発明によれば、光源から
の光を偏光フィルムと、偏光軸方向が偏光フィルムとほ
ぼ直交する偏光板とを透過させ、暗い視野の中の輝点や
白点として、偏光フィルムの偏光特性を示す部分よりも
観察側に存在する欠陥を、容易に検出することができ
る。偏光フィルムの偏光特性を示す部分よりも光源側に
存在する欠陥は、偏光板を通過する光の割合がさらに減
少して暗く見えるようになる。したがって、積層構造の
偏光フィルムでは、内部の偏光特性を示す層の観察側ま
たは光源側に存在する微小な欠陥を容易に検出すること
ができる。As described above, according to the present invention, light from a light source is transmitted through a polarizing film and a polarizing plate whose polarization axis direction is substantially perpendicular to the polarizing film, so that bright spots or white spots in a dark visual field can be obtained. As a point, it is possible to easily detect a defect present on the observation side with respect to the portion showing the polarization characteristics of the polarizing film. Defects that exist on the light source side of the polarizing film on the light source side with respect to the portion exhibiting the polarizing characteristics cause the ratio of light passing through the polarizing plate to be further reduced and appear dark. Therefore, in the polarizing film having the laminated structure, minute defects existing on the observation side or the light source side of the layer exhibiting the internal polarization characteristics can be easily detected.
【0029】さらに本発明によれば、偏光フィルムに、
その偏光軸とほぼ直交する方向の偏光軸を有するように
構成される光源からの光を透過させ、暗い視野の中の輝
点や白点として、偏光フィルムの偏光特性を示す部分よ
りも光源側に存在する欠陥を、容易に検出することがで
きる。偏光フィルムの偏光特性を示す部分よりも観察側
に存在する欠陥は、偏光板を通過する光の割合がさらに
減少して暗く見えるようになる。したがって、積層構造
の偏光フィルムでは、内部の偏光特性を示す層の観察側
または光源側に存在する微小な欠陥を容易に検出するこ
とができる。According to the present invention, the polarizing film further comprises
Transmits light from a light source configured to have a polarization axis in a direction substantially perpendicular to the polarization axis, and as a bright point or a white point in a dark visual field, closer to the light source than a portion showing the polarization characteristics of the polarizing film. Can be easily detected. Defects that are present on the viewing side of the polarizing film with respect to the portion exhibiting the polarizing characteristics cause the proportion of light passing through the polarizing plate to be further reduced and appear dark. Therefore, in the polarizing film having the laminated structure, minute defects existing on the observation side or the light source side of the layer exhibiting the internal polarization characteristics can be easily detected.
【0030】また本発明によれば、偏光性の光学特性を
有する層に、透明な保護層をそれぞれ貼合せて形成され
る偏光フィルムで、内部となる貼合せ部に存在する異物
を、存在する方向も含めて、容易に検出することができ
る。Further, according to the present invention, there is a polarizing film formed by laminating a transparent protective layer on a layer having a polarizing optical property, and a foreign substance present in a laminating portion inside the polarizing film is present. It can be easily detected, including the direction.
【図1】 本発明の実施の一形態としての偏光フィルム
の欠陥検査方法を、概略的に示す図である。FIG. 1 is a view schematically showing a polarizing film defect inspection method as one embodiment of the present invention.
【図2】図1の実施形態での異物の見え方を示す図であ
る。FIG. 2 is a diagram showing how a foreign substance looks in the embodiment of FIG. 1;
【図3】 本発明の実施の他の形態としての偏光フィル
ムの欠陥検査方法を、概略的に示す図である。FIG. 3 is a view schematically showing a defect inspection method for a polarizing film as another embodiment of the present invention.
【図4】図3の実施形態での異物の見え方を示す図であ
る。FIG. 4 is a diagram showing how a foreign matter looks in the embodiment of FIG. 3;
【図5】液晶表示の原理を示す図である。FIG. 5 is a diagram illustrating the principle of liquid crystal display.
【図6】偏光フィルタの使用法を示す図である。FIG. 6 is a diagram showing how to use a polarizing filter.
【図7】偏光フィルムの構成を示す図である。FIG. 7 is a diagram illustrating a configuration of a polarizing film.
20 偏光フィルタ 21 光源 22,23 偏光板 24 偏光層 24a 偏光軸 25 下の異物 26 上の異物 27 視野 Reference Signs List 20 polarizing filter 21 light source 22, 23 polarizing plate 24 polarizing layer 24a polarizing axis 25 foreign matter below 26 foreign matter above 27
───────────────────────────────────────────────────── フロントページの続き Fターム(参考) 2G051 AA90 AB06 AB20 AC21 CA04 CA11 CB02 CC07 EA16 EB01 2H049 BA02 BA26 BB03 BB33 BB43 BC01 BC03 BC22 2H088 FA13 FA18 FA24 FA30 HA18 MA16 2H091 FA08X FA08Z FB02 FB12 FC07 FC16 FC29 FC30 FD06 FD14 GA17 HA07 LA11 LA12 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2G051 AA90 AB06 AB20 AC21 CA04 CA11 CB02 CC07 EA16 EB01 2H049 BA02 BA26 BB03 BB33 BB43 BC01 BC03 BC22 2H088 FA13 FA18 FA24 FA30 HA18 MA16 2H091 FA08X FA08Z FC30 FC07 FC07 FC07 FC07 FC07 FC07 GA17 HA07 LA11 LA12
Claims (3)
向の偏光成分のみを選択的に透過させる偏光フィルム
に、光源からの光を透過させ、 該偏光フィルムを透過した光を、該偏光軸とほぼ直交す
る方向の偏光軸を有するように配置される偏光板に導
き、 該偏光板を透過した光を観察して、全体的な視野と明る
さの異なる部分が存在するとき、該視野よりも明るけれ
ば該偏光フィルムの偏光特性を示す部分よりも観察側に
存在する欠陥であり、該視野よりも暗ければ該偏光フィ
ルムの偏光特性を示す部分よりも光源側に存在する欠陥
であると判断することを特徴とする偏光フィルムの欠陥
検査方法。1. A polarizing film that selectively transmits only a polarization component in a predetermined polarization axis direction of incident light, transmits light from a light source, and transmits the light transmitted through the polarizing film to the polarization axis. To a polarizing plate arranged so as to have a polarization axis in a direction substantially orthogonal to, observing the light transmitted through the polarizing plate, when there is a portion different in brightness from the entire visual field, from the visual field If it is too bright, it is a defect present on the observation side than the part showing the polarization characteristics of the polarizing film, and if it is darker than the field of view, it is a defect present on the light source side than the part showing the polarization characteristics of the polarizing film. A defect inspection method for a polarizing film, characterized by making a judgment.
向の偏光成分のみを選択的に透過させる偏光フィルム
に、該偏光軸とほぼ直交する方向の偏光軸を有するよう
に構成される光源からの光を透過させ、 該偏光フィルムを透過した光を観察して、全体的な視野
と明るさの異なる部分が存在するとき、該視野よりも暗
ければ該偏光フィルムの偏光特性を示す部分よりも観察
側に存在する欠陥であり、該視野よりも明るければ該偏
光フィルムの偏光特性を示す部分よりも光源側に存在す
る欠陥であると判断することを特徴とする偏光フィルム
の欠陥検査方法。2. A light source configured to have a polarization axis in a direction substantially orthogonal to the polarization axis on a polarizing film that selectively transmits only a polarization component in a predetermined polarization axis direction of incident light. The light transmitted through the polarizing film is observed, and when there is a part having a different brightness from the entire visual field, if the part is darker than the visual field, the part showing the polarization characteristics of the polarizing film is displayed. A defect inspection method for a polarizing film, characterized in that the defect is present on the observation side, and if the light is brighter than the field of view, it is determined that the defect is present on the light source side rather than a portion showing the polarization characteristics of the polarizing film.
を有する層の両表面に、透明な保護層をそれぞれ貼合せ
て形成されており、 前記欠陥は、該貼合せ部に存在する異物を含むことを特
徴とする請求項1または2記載の偏光フィルムの欠陥検
査方法。3. The polarizing film is formed by laminating a transparent protective layer on both surfaces of a layer having a polarizing optical characteristic, and the defect removes a foreign substance present in the laminating part. The method for inspecting defects of a polarizing film according to claim 1, wherein the method comprises:
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JP2000170301A JP2001349839A (en) | 2000-06-07 | 2000-06-07 | Inspection method for polarizing film defect |
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JP2010534351A (en) * | 2008-01-07 | 2010-11-04 | エルジー・ケム・リミテッド | Non-uniformity inspection method for polarizing plate using image analysis, and automatic non-uniformity inspection system for polarizing plate using the same |
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