JP2003344302A - Method and equipment for inspecting polarization film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and equipment for detecting a defect, especially a bubble, of a polarization film of a multilayer structure moving continuously, with high accuracy without the effect of a waving phenomenon in the widthwise direction accompanying the movement of the film, vibration (fluttering) of the film during carriage, or the like. <P>SOLUTION: The inspection equipment having two sets of inspecting sections provided with a light source section and a detecting section disposed, respectively, on the surface side and the back side of the polarization film moving continuously, and a carry roll abutting/supporting the back side of the film is used. Ether one of the light source section and the light receiving section of the detecting section is provided with a polarization member having a transmission axis making cross Nicol with the absorption axis of the polarization film, and at the inspecting section, the polarization film supported by the carry roll while abutting is irradiated with light from the light source at the light source section and its reflected light is detected. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for inspecting a defect of a polarizing film, in particular, a bubble defect existing on the surface of the polarizing film or inside thereof, that is, at the interface between the laminated materials of the polarizing film.

[0002]

2. Description of the Related Art Polarizing films are attached to both sides of a liquid crystal cell and used as a part of a liquid crystal display panel.
FIG. 1 is a sectional view showing an example of the structure of the liquid crystal display panel. The liquid crystal display panel 20 has a structure in which the polarizing film 1 is attached to both surfaces of a liquid crystal cell 21.

The liquid crystal display has the advantage that it can be made smaller and thinner, and at the same time it consumes less power. Therefore, small video cameras, mobile phones, car navigation systems,
It is widely used in personal computers.

The structure of the polarizing film used for manufacturing such a liquid crystal display panel varies depending on the application, but for example, an adhesive layer and a protective film laminated on the adhesive layer on one side or both sides of the polarizer film itself. Has a laminated structure.

In such a polarizing film, if air bubbles are present on the surface or inside thereof, that is, inside the polarizer film, the adhesive layer, the constituent material of the protective film, and the laminating interface, it causes image defects and deterioration of image quality. It is necessary to inspect such defects at the manufacturing stage of the polarizing film.

As an inspection method for detecting bubbles in a polarizing film, a method of irradiating one surface of the polarizing film with light so as to obliquely strike the film and observing the reflected light to inspect it, the polarizing film An inspection method is known in which one side of the film is irradiated with light and the light transmitted from the opposite side of the film is observed.

[0007]

However, there are many air bubbles that cannot be detected by the method of irradiating light on one surface of the polarizing film and observing the light transmitted through the film from the opposite surface. Further, at the inspection position, the light source unit should be provided on one side of the polarizing film and the detection unit should be provided on the opposite side. Then, since the film is not restrained during that time, a waviness phenomenon in the width direction, a vibration (fluttering) during conveyance, and the like occur, and the accuracy of the image of the inspection unit deteriorates. Particularly in recent years, the image quality of liquid crystal displays has improved and bright and clear images have been formed. Therefore, a small defect which has not been a problem in the past is also regarded as a defect of the display. Further, this method has a problem that it is easy to distinguish a foreign substance and bubbles around it, so-called bubbles with nuclei, but it is difficult to detect bubbles without foreign substances, so-called bubbles without nuclei. Therefore, even in the inspection of the polarizing film, it is required to have an accuracy of detecting a small defect, and the above-mentioned inspection method cannot meet such a request.

On the other hand, in the method of irradiating light on one surface of the polarizing film so that the film obliquely strikes the film and observing the reflected light to inspect, the nucleation-free bubbles have no brightness. Because it is different from the surroundings, it can be detected more clearly, and in the inspection part of the polarizing film that is continuously manufactured, a plate-like body is provided with a large number of holes to make an inspection substrate, which is slidably sucked from the back side. It is possible to improve the inspection accuracy by suppressing the flapping and waviness of the film.

However, in this method, when a slight gap is generated between the inspection substrate and the polarizing film, the vacuum suction is released on the entire surface, and the film is flapping and corrugated, and the inspection accuracy is deteriorated. Further, there is a problem that the film surface is scratched due to the sliding of the polarizing film and the inspection substrate. Further, there is also a problem that it is difficult to change the width of vacuum adsorption due to the polarization of the polarizing film to be manufactured.

It is an object of the present invention that defects in a polarizing film having a laminated structure in which a continuously moving polarizer film, an adhesive layer, and a protective film are laminated, in particular, bubble defects, are wavy in the width direction as the film moves. An object of the present invention is to provide an inspection method and an inspection device that detect with high accuracy without being affected by a phenomenon, vibration (fluttering) during transportation, and the like.

The present invention also provides an inspection method and an inspection apparatus capable of detecting defects with high accuracy even when the width of the polarizing film to be manufactured is changed without damaging the film surface. It is in.

[0012]

DISCLOSURE OF THE INVENTION The present invention is an inspection method for detecting defects in a continuously moving polarizing film on the basis of reflected light.
A first inspection section including a light source section, a first detection section, and a first transport roll that abuts and supports the back side of the film, and a second light source section and a second detection section arranged on the back side of the film. An inspection apparatus having a second inspection unit provided with a second transport roll that abuts and supports the front side of the film is used, and any one of the first light source unit and the light receiving unit of the first detection unit is used, Further, a polarizing member having a transmission axis forming a crossed Nicols with the absorption axis of the polarizing film to be inspected is provided in any of the second light source section and the light receiving section of the second detection section, and in the first inspection section. The polarizing film, which is abutted and supported by the first transport roll, is irradiated by the light source of the first light source unit, the reflected light is detected by the first detection unit, and the second light source is detected by the second inspection unit. Support of the second transport roll by the light source of the section By irradiating a polarizing film which is characterized by detecting the reflected light by the second detector.

According to the structure of the present invention, even when the inspection device is operated between a plurality of means for gripping and transporting the polarizing film, the inspection device is provided with the transport roll, so that the film at the inspection position of the film Accurate detection of defects is possible without causing waviness and flapping.

Further, since the inspection is carried out at the portion where the polarizing film to be inspected is in contact with the transport roll, the defect can be detected with high accuracy even if the polarizing film is thin and easily distorted.

Further, either the first light source section or the light receiving section of the first detection section, and the second light source section or the light receiving section of the second detection section, the absorption axis of the polarizing film to be inspected and the crossed Nicols. By providing a polarizing member having a transmission axis that makes it possible to reduce or block the light that reaches the detector from the opposite surface of the polarizing film to be inspected, and the dust on the surface of the transport roll, scratches, etc. are treated as product defects. Detection is prevented.

In order to prevent the influence of scattered light (stray light) from other than the light source, the inspection method of the present invention is basically preferably performed in a dark room. From the viewpoint of reducing the influence of unnecessary scattered light, it is desirable that at least the surface of the transport roll be black.

The polarizing member used in the inspection apparatus of the present invention can be used without particular limitation as long as it can obtain linearly polarized light. Specifically, a polarizing filter, a polarizing film, a polarizing lens, a polarizing member. In the present invention in which a child, an analyzer and the like are exemplified, it is preferable to mark the defect position of the polarizing film based on the information indicating the defect obtained by the first detection unit and the second detection unit.

According to the above construction, in the step of removing the defective portion from the inspected polarizing film, the detected defective portion can be removed before it becomes a display. The marked portion may be excluded when punching the polarizing film into a predetermined size, or may be removed as a minimum unit section.

Another aspect of the present invention is a polarizing film inspection apparatus for detecting a defect in a continuously moving polarizing film based on reflected light, the first light source section and the first light source section disposed on the front surface side of the film. No. 1 detection section and a first inspection section having a first transport roll that abuts and supports the back side of the film, and a second light source section and a second detection section arranged on the back side of the film and the front surface of the film A second inspection unit having a second transport roll that abuts and supports the side, and any one of the first light source unit and the light receiving unit of the first detection unit, and the second light source unit and the second detection unit. A polarizing member having a transmission axis forming a crossed Nicols with the absorption axis of the polarizing film to be inspected is provided in any one of the light receiving sections of the first light source section in the first inspection section. Polarization film abutted and supported by one transport roll Wherein the reflected light by irradiating a beam first
The polarizing film, which is detected by the detection unit, is contacted and supported by the second transport roll by the light source of the second light source unit in the second inspection unit, and the reflected light is irradiated by the second detection unit. It is characterized in that it is configured to detect.

Even when the inspection device is operated between a plurality of means for gripping and conveying the polarizing film by using the inspection device having the above-mentioned structure, the inspection device is provided with the conveyance rolls so that the inspection position of the film can be improved. Accurate detection of defects is possible without waviness or flapping of the film.

Further, since the inspection is carried out at the portion where the polarizing film to be inspected is in contact with the transport roll, even if the polarizing film is thin and easily distorted, the defect can be detected with high accuracy.

It is preferable to provide marking means for marking the defect position of the polarizing film based on the information indicating the defect obtained by the second detecting unit and the second detecting unit.

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings. 2 and 3, the cross section of an example of a polarizing film having a laminated structure is enlarged and a bubble defect to be detected is shown as a model. FIG. 2 shows a polarizing film 1 having a five-layer structure including a protective film 13, an adhesive layer 21, a polarizer film 12, an adhesive layer 16, and a protective film 13.
Is an example of. In this film, the air bubble defects of the polarizing film 1 which are defects of the display which is the final product are a, b, c and d.

FIG. 3 shows a polarizer film 12 and an adhesive layer 1
6 is an example of the polarizing film 1 having a three-layer laminated structure including the protective film 13 and the protective film 13. In this film, e and f are bubble defects that can be detected.

A known polarizer film is used as a polarizer film which is a constituent member of the polarization film. Specifically, iodine with a high degree of polymerization of polyvinyl alcohol,
A film in which a dichroic dye such as a dichroic dye is adsorbed and oriented is generally used.

Triacetyl cellulose (TAC) is generally used as the protective film. As the adhesive, a water-soluble resin such as polyvinyl alcohol having a low degree of polymerization is generally used.

In FIG. 4, the light source section E1, the detecting section D1 and the carrying roll 21 which abut on and support the lower surface side of the film 1 arranged on the upper surface side of the polarizing film 1 which is continuously supplied and carried in the direction of the arrow. The first inspection unit T1 and the light source unit E2 and the detection unit D arranged on the lower surface side of the polarizing film 1.
2 shows an example of the configuration of an inspecting apparatus including the second inspecting section T2 including the transport roll 22 that abuts and supports from the upper surface side of the film 1.

The polarizing film 1 to be inspected contacts the first transport roll 21 in the range of w1 and the second transport roll 22 in the range of w2. The light source unit E1 irradiates the upper surface of the polarizing film in the contact area w1 between the polarizing film 1 and the first transport roll 21, and the reflected light is received by the detecting unit D1. Further, the light source section E2 illuminates the lower surface of the polarizing film in the contact area w2 between the polarizing film 1 and the second transport roll 22, and the detection section D2 receives the reflected light. The light source sections E1 and E2 may be provided with appropriate slits 4 to irradiate only necessary inspection portions of the polarizing film.

A light source 3 is provided in each of the light source sections E1 and E2, and a detector 6 is provided in each of the detection sections D1 and D2. As the light source 3, a readily available light source such as a fluorescent lamp can be used, and if a type having a wide light emitting portion is used, even if there is some unevenness on the film surface, the influence on the inspection result can be reduced. it can. The angle θ formed by the light source and the plane perpendicular to the tangent line of the polarizing film 1 is preferably 30 to 45 degrees.

By setting θ within the above range, it is possible to detect defects with high accuracy even when the same light source unit and detection unit are used. The detection units D1 and D2 may be configured by using a CCD as the detector 6, for example, and detecting means for detecting the reflection of light due to air bubbles as a change in brightness based on the light information from the CCD. Often,
You may use the detection means which forms an image from the information of the light from CCD, and detects a bubble and a foreign material by image processing.
If necessary, a plurality of CCDs may be provided side by side in the width direction of the film so that the entire area in the width direction can be inspected.

The first conveying roll 21 and the second conveying roll 22 of the inspection device are driven rolls. If the diameter of the conveying roll is too small, the bending will occur and the inspection accuracy will decrease, and if the outer diameter of the conveying roll is too large. It becomes difficult to follow the movement of the film. The outer diameter of the transport rolls 21 and 22 is about 100-
It is preferably in the range of 200 mm.

FIG. 5 is an enlarged model view of the inspection method of the present invention. Here, an example of inspecting a polarizing film having a five-layer structure (the adhesive layer is omitted and shown as three layers in the drawing) having the configuration of FIG. 2 in the first inspection unit of FIG. showed that. Also in the second inspection section,
Do exactly the same test. The light sent from the light source unit E1 irradiates the polarizing film 1 at the S position which is the inspection position,
The reflected light from the S position is received by the detector D1. Since the polarizer film 12 forming the laminated polarizing film 1 is formed in crossed Nicols with the polarizing member 4 of the detection unit D1, the illumination light reaching the surface of the transport roll 21 does not reach the detection unit. Therefore, the bubble p1 (the bubbles a and b in FIG. 2) is detected, but the foreign matter on the surface of the transport roll is not detected. The bubble p3 (bubbles c and d in FIG. 2) is detected by the second detector.

Defect marking can be performed by, for example, arranging a plurality of printing bodies in the lateral direction of the polarizing film at a constant pitch and printing by pressing a printing body corresponding to a section including a defective portion onto the film surface. To be

The inspection method of the present invention can be inspected even if a protective film, which is peeled off when the liquid crystal display panel is actually used, is laminated on the surface of the polarizing reflector.

As the inspection means of the present invention, it is also possible to adopt a configuration in which a plurality of light sources and detectors are arranged, or a configuration in which a single band-shaped or straight tubular light source and a plurality of detectors are combined. Further, as the detection unit, it is possible to employ either the case where the detectors are arranged as a line sensor or the case where they are arranged as an area sensor.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration example of a liquid crystal display panel using a polarizing film.

FIG. 2 is a cross-sectional view showing a configuration of a five-layer structure polarizing film to be inspected and an example of defects.

FIG. 3 is a cross-sectional view showing an example of the structure and defects of a polarizing film having a three-layer structure to be inspected.

FIG. 4 is a diagram showing a configuration example of an inspection apparatus of the present invention.

FIG. 5 is an enlarged view showing an inspection unit of the inspection apparatus of the present invention.

[Explanation of symbols]

1 Polarizing film 21 First Transport Roll 3 light sources 4 slits 5 Polarizing member 6 detector D detector E Light source section

Continued front page    F term (reference) 2F065 AA49 AA61 BB13 BB15 BB21                       CC02 FF44 GG03 GG16 HH12                       JJ02 JJ03 JJ05 JJ08 JJ25                       JJ26 LL28 MM03 UU03                 2G051 AA41 AB01 AB02 AB06 AB07                       BA01 BA20 CA03 CA04 CA07                       CB01 DA15                 2H049 BA02 BA26 BA27 BB33 BB43                       BB62 BC01 BC22                 2H091 FA08X FA08Z FB02 FC30                       LA12

Claims (4)

[Claims] 1. An inspection method for detecting defects in a continuously moving polarizing film based on reflected light, comprising: a first light source section, a first detection section, and a film disposed on the front surface side of the film. A first inspecting section having a first transport roll that abuts and supports the back side, and a second light source section and a second detecting section that are arranged on the back side of the film, and a second side that abuts and supports the front side of the film An inspection apparatus having a second inspection unit including two transport rolls is used, and any one of the first light source unit and the light receiving unit of the first detection unit, and the second light source unit and the second detection unit. A polarizing member having a transmission axis forming a crossed Nicols with the absorption axis of the polarizing film to be inspected is provided in any of the light receiving sections of the first light source section of the first light source section in the first inspection section. Polarization mirror that is supported by one transport roll The film is irradiated and the reflected light is detected by the first detector, and the second inspection unit irradiates the polarizing film abutted and supported by the second transport roll by the light source of the second light source. A method of inspecting a polarizing film, characterized in that the reflected light is detected by the second detecting section. 2. The method for inspecting a polarizing film according to claim 1, wherein the defect position of the polarizing film is marked on the basis of the information indicating the defect obtained by the second detecting unit and the second detecting unit. 3. An inspection apparatus for detecting defects in a continuously moving polarizing film based on reflected light, comprising a first light source section, a first detection section and a film arranged on the front surface side of the film. A first inspecting section having a first transport roll that abuts and supports the back side, and a second light source section and a second detecting section that are arranged on the back side of the film, and a second side that abuts and supports the front side of the film A second inspection section provided with two transport rolls, and any one of the first light source section and the light receiving section of the first detection section, and any one of the second light source section and the light receiving section of the second detection section. A polarizing member having an absorption axis of a polarizing film to be inspected and a transmission axis forming a crossed Nicol is provided, and in the first inspection unit, the light source of the first light source unit is brought into contact with and supported by the first transport roll. Irradiating the polarized film The polarizing film detected by the first detection unit and radiated by the light source of the second light source unit in the second inspection unit to be brought into contact with and supported by the second transport roll, and the reflected light thereof is second detected. An apparatus for inspecting a polarizing film, characterized in that it is configured to be detected by a section. 4. The marking means for marking the defect position of the polarizing film on the basis of the information indicating the defect obtained by the first detection unit and the second detection unit. Polarizing film inspection device.