JP4278246B2 - Inspection method of optical transparent film - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for inspecting an optical transparent film in which an optical transparent film on which a release film is laminated is irradiated with illumination light from the side opposite to the release film, and the optical transparent film surface on the opposite side is observed.
[0002]
[Prior art]
An example of the optically transparent film is a linear polarizing plate.
[0003]
This linear polarizing plate absorbs polarized light having a vibration plane parallel to the absorption axis direction, and has an optical function of transmitting polarized light having a vibration plane parallel to the direction orthogonal to the absorption axis (transmission axis). For example, it is widely used as one of optical elements constituting a liquid crystal display device.
[0004]
And this linearly polarizing plate is manufactured in a state in which an adhesive layer is provided in advance on one surface (hereinafter referred to as “back surface”) in order to facilitate bonding to a liquid crystal display device. In order to prevent foreign substances such as dust from adhering to the pressure-sensitive adhesive layer, a release film, which is an example of a release film, is often stuck on the pressure-sensitive adhesive layer.
[0005]
By the way, defects such as foreign matter adhering to the other surface (hereinafter referred to as “surface”) of the linearly polarizing plate, and defects such as scratches, pinholes, and unevenness deteriorate the image quality of the liquid crystal display device. Therefore, when manufacturing a liquid crystal display device, it is important to inspect the surface for defects.
[0006]
Conventionally, as a means for inspecting defects such as foreign matters adhering to the surface and defects such as scratches, pinholes and unevenness on the surface, illumination light is irradiated from the side opposite to the release film, and the surface is exposed to an operator. There was a means to observe directly.
[0007]
However, in the linear polarizing plate, light (polarized light having a vibration plane parallel to the direction orthogonal to the absorption axis (transmission axis)) is transmitted from the outer side of the release film to the surface side opposite to the release film. Therefore, when the linear polarizing plate with the release film attached to the back surface is observed with the above-mentioned conventional means, the defect on the release film side can be seen from the outer side of the surface, and the defect is distinguished from the surface defect. It was difficult.
[0008]
Further, the surface of the linear polarizing plate may be subjected to an anti-reflection coating treatment. For example, in order to detect a defect such as a foreign object on the surface or a portion where the surface anti-reflection coating layer is missing, However, such a non-reflective coating layer has a surface reflectance of, for example, 1% or less, preferably 0.5% or less. Weakens.
[0009]
Therefore, when light from the back side is transmitted to the front side, it is not easy to detect a defect such as a foreign object or a portion where the surface non-reflective coating layer is missing, and the diameter is particularly about 20 to 30 μm. Defects and linear scratches having a width of about 2 to 3 μm or less even when the length was about 20 to 30 μm or more could hardly be detected.
[0012]
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and the purpose thereof is a defect such as a foreign matter adhering to the surface of the optical transparent film opposite to the release film, a scratch, a pinhole, unevenness, etc. on the surface of the optical transparent film. It is to be able to accurately inspect for defects.
[0013]
[Means for Solving the Problems]
The structure, operation, and effect of the invention according to claim 1 are as follows.
[0014]
[Constitution]
In the inspection method of the optical transparent film described at the beginning, the outer surface of the release film is prevented from being exposed to light from the outer side of the outer surface, and the color of the illumination light, and the color of the release film, The illumination light is irradiated onto the optical transparent film in a state where the colors are set to colors complementary to each other, and the optical transparent film surface is observed.
[0015]
[Action]
[A] Since the light is prevented from hitting the outer surface of the release film laminated on the optical transparent film from the outer side of the outer surface, the light is optically transparent on the opposite side of the release film from the outer side of the release film side. Transmission to the outer side of the film surface (hereinafter referred to as “the surface of the optically transparent film”) can be prevented.
[0016]
[B] Since the optical transparent film is irradiated with illumination light from the side opposite to the release film, the surface of the optical transparent film can be observed by observing the reflected light from the surface side of the optical transparent film. .
[0017]
[C] In this case, since the color of the illumination light and the color of the release film are set to colors that are complementary to each other, when the illumination light hits the release film, the release film is optical It looks black from the outside of the surface of the transparent film.
[0018]
In addition, since it prevents that the light hits the outer surface of the peeling film laminated | stacked on the optical transparent film from said outer side like said [i], the light of a color different from the said illumination light is given to a peeling film. It is possible to prevent hitting, and it is possible to prevent the release film from appearing black as in the above [c] due to the different color light hitting the release film.
[0019]
[D] In other words, as in [A] above, light can be prevented from being transmitted from the outer side of the release film to the outer side of the surface of the optical transparent film. When the illumination light hits the release film, the release film looks black from the outside of the surface of the optical transparent film, so that defects such as foreign matter adhered to the release film side, scratches / pinholes on the release film side, etc. -Defects, such as nonuniformity, are not visible from the outer side of the surface of an optical transparent film, and only the surface side defect can be observed about the said defect.
[0020]
[E] By the way, an optically transparent film such as a linearly polarizing plate may be subjected to a surface non-reflective coating treatment.
[0021]
In order to detect defects such as scratches on the surface of such an optical transparent film and parts where the surface non-reflective coating layer is missing, it is considered that it is sufficient to detect reflected light from the surface of the optical transparent film. Even in this case, the above action [d] makes it possible to detect only the reflected light from the surface side of the optical transparent film, making it easier to detect defects such as foreign matter and scratches on the surface non-reflective coating layer. Is almost impossible to detect, and has a diameter of about 20 to 30 μm, such as a foreign matter or a flaw, or a linear shape with a width of about 2 to 3 μm or less even if the length is about 20 to 30 μm or more. It becomes possible to easily visually inspect the scratches.
[0022]
[F] Since the release film is in a colored state, it is possible to quickly and accurately discriminate between the front surface and the back surface of the optical transparent film just by looking at the optical transparent film.
[0023]
[G] As a method for inspecting the surface of the optical transparent film, a black light-shielding film is stuck on the release film, or the black light-shielding film is stuck on the pressure-sensitive adhesive layer as a release film. An inspection method for observing is also conceivable. According to this method, when trying to inspect defects on the back surface side with transmitted light from the outside of the peeling film, or when inspecting the transmittance of the optical transparent film, etc. Although there is a problem that the film must be peeled off and inspected, according to the configuration of claim 1, since the release film is not set to black, the above-described problems can be avoided, Transmission inspection of optical transparent film (for example, inspection of transmittance of optical transparent film and inspection of defects inside optical transparent film) with release film laminated on optical transparent film It can be carried out.
[0024]
[effect]
Therefore, the above actions [A] to [E] can accurately detect defects such as foreign matter adhering to the surface of the optical transparent film opposite to the release film, and defects such as scratches, pinholes and unevenness on the surface of the optical transparent film. The above-mentioned action [f] can improve the efficiency of work when the optical transparent film is attached to a symmetrical object such as a glass of a liquid crystal display device, for example. The inspection by the transmitted light of the optical transparent film can be easily performed.
[0025]
The structure, operation, and effect of the invention according to claim 2 are as follows.
[0026]
[Constitution]
In the configuration of the invention according to claim 1, the optical transparent film surface is observed by irradiating the optical transparent film with the illumination light in a dark room.
[0027]
[Action]
In addition to having the same effect as that of the configuration of claim 1, the optical transparent film is irradiated with illumination light in the dark room and the optical transparent film surface is observed. It is possible to reliably prevent the light from hitting from the outside side.
[0028]
[effect]
Therefore, in addition to being able to achieve the same effect as the effect of the configuration of claim 1, defects such as foreign matter adhering to the optical transparent film surface opposite to the release film, scratches on the optical transparent film surface, Defects such as pinholes and unevenness can be inspected more accurately.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0030]
[First Embodiment]
FIG. 1 shows a state in which defects such as foreign matters attached to the surface F2 of the polarizing film 1 and defects such as scratches, pinholes and unevenness on the surface F2 are inspected in the dark room 7.
[0031]
The polarizing film 1 corresponds to an optically transparent film and is also called a linearly polarizing plate. The polarizing film 1 is configured as a laminated film in which a polarizing film 5 is sandwiched between a pair of TAC films 2 (triacetyl cellulose film), and one TAC. A non-reflective coating layer is provided on the surface of the film 2 (that is, the surface of the polarizing film 1) so that the reflectance of the surface of the polarizing film 1 is, for example, 1% or less (preferably 0.5% or less).
[0032]
And the adhesive layer 8 is provided in the surface on the opposite side to the polarizing film 5 of the other TAC film 2, and the red release film 9 (equivalent to a peeling film) is stuck and laminated | stacked on this adhesive layer 8. is there.
[0033]
In the dark room 7, a green lamp 3 as a light source for the surface F2 of the polarizing film 1 and a support base 6 for supporting the polarizing film 1 are arranged.
[0034]
The defects on the surface F2 side of the polarizing film 1 are inspected as follows.
[0035]
The polarizing film 1 is placed at a predetermined position of the support base 6 in the dark room 7 with the release film 9 side down.
[0036]
The green lamp 3 in the dark room 7 irradiates the surface F2 of the polarizing film 1 with green illumination light. By placing the polarizing film 1 on the support base 6, the outer surface of the release film 9 is placed on the outer surface. It will be in the state which prevented light from hitting from the outside.
[0037]
Thereby, it is possible to prevent light from being transmitted from the outer side of the release film 9 to the surface F2 side of the polarizing film 1.
[0038]
Then, the surface F2 of the polarizing film 1 is irradiated with green illumination light from the green lamp 3, and the reflected light is observed to observe the surface F2 of the polarizing film 1 (that is, the release film 9 is laminated). The polarizing film 1 is irradiated with illumination light from the side opposite to the release film 9 to observe the surface F2 of the polarizing film 1).
[0039]
Since the color (green) of the illumination light of the green lamp 3 and the color (red) of the release film 9 are complementary to each other, when the illumination light hits the release film 9, the release film 9 is It looks black from the outer side of the surface F2 of the polarizing film 1.
[0040]
As described above, it is possible to prevent light from being transmitted from the outer side of the release film 9 to the outer side of the surface F2 of the polarizing film 1, and when the illumination light hits the release film 9 Since the release film 9 appears black from the outer side of the surface of the polarizing film 1, defects such as foreign matter attached to the release film 9 side, scratches, pinholes, unevenness, etc. on the release film 9 side A defect is not visible from the outer side of the surface F2 of the polarizing film 1, and only the defect on the surface F2 side of the polarizing film 1 can be observed for the defect.
[0041]
Moreover, it becomes easy to detect defects such as scratches on the surface non-reflective coating layer.
[0042]
[Another embodiment of the first embodiment]
The present invention can be applied even when a retardation plate or the like is interposed between the polarizing film 1 and the release film 9.
[0043]
[Second Embodiment]
FIG. 2 shows a state in which defects such as foreign matters attached to the surface F2 of the polarizing film 1 and defects such as scratches, pinholes and unevenness on the surface F2 are inspected in the dark room 7.
[0044]
In addition, the surface F2 of the said polarizing film 1 means the polarizing film surface by the side to be test | inspected. Therefore, it may not correspond to the front polarizing film surface when bonded to glass or the like of a liquid crystal display device.
[0045]
The polarizing film 1 is configured as a laminated film in which a polarizing film 5 is sandwiched between a pair of TAC films 2 and a red protective film 10 (corresponding to a peeling film) is laminated on the back surface of one TAC film 2 so as to be peelable. It is.
[0046]
The structure in the dark room 7 is the same as the structure in the dark room 7 in the first embodiment.
[0047]
The surface F2 of the polarizing film 1 is inspected as follows.
[0048]
The polarizing film 1 is placed at a predetermined position of the support base 6 in the dark room 7 with the protective film 10 facing down.
[0049]
Then, the surface of the polarizing film 1 is observed in the same procedure as in the first embodiment (that is, the polarizing film 1 on which the protective film 10 is laminated is irradiated with illumination light from the side opposite to the protective film 10, and Observe the surface F2 of the polarizing film 1).
[0050]
In this case as well, as in the first embodiment, defects such as foreign matter attached to the protective film 10 side, and defects such as scratches, pinholes, and unevenness on the protective film 10 side are on the outer side of the surface F2. Therefore, only the defect on the surface F2 side can be observed.
[0051]
[Another embodiment of the first and second embodiments]
In the first and second embodiments, the polarizing film 1 is inspected in the dark room 7 in order to prevent light from hitting the outer surface of the protective film 10 or the release film 9 from the outer side of the outer surface. Instead of this, a means for applying a light-shielding plate to the release film 9 can be taken, and according to this means, the polarizing film 1 can be inspected without being in the dark room 7.
[0052]
You may make it irradiate the polarizing film 1 by making the light from a light source pass through a filter, making it green or another color.
[0053]
The color of the illumination light and the color of the protective film 10 or the release film 9 may be a color other than the above color as long as they have a complementary color relationship.
[0054]
The complementary color relationship generally refers to two colors that become white, gray, or black when mixed with each other, but the complementary color relationship in the present invention refers to two colors that become black when mixed with each other.
[0055]
The optical transparent film is not limited to the polarizing film, and may be another transparent film such as a retardation film.
[0056]
The release film is a film that is finally peeled off from the optical transparent film, and includes a release film that protects the pressure-sensitive adhesive layer and a protective film that protects the polarizing film surface as described above.
[Brief description of the drawings]
FIG. 1 is a diagram showing an inspection method for a linearly polarizing plate in the first embodiment. FIG. 2 is a diagram showing an inspection method for the linearly polarizing plate in a second embodiment.
DESCRIPTION OF SYMBOLS 1 Optical transparent film 7 Dark room 9 Release film 10 Release film F2 Optical transparent film surface

Claims (2)

The optical transparent film on which the release film is laminated is irradiated with illumination light from the opposite side of the release film, and the optical transparent film surface on the opposite side is observed.
The outer surface of the release film is prevented from being exposed to light from the outer side of the outer surface, and the color of the illumination light and the color of the release film are set to colors that are complementary to each other. In the state, the optical transparent film is irradiated with the illumination light and the optical transparent film surface is observed.   The optical transparent film inspection method according to claim 1, wherein the optical transparent film is irradiated with the illumination light in a dark room and the optical transparent film surface is observed.

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