JP2005291878A - Inspection method of optical film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inspection method of an optical film, capable of inspecting a defect precisely by preventing sufficiently reflection of light onto the optical film. <P>SOLUTION: In this inspection method of the optical film 1, the optical film 1 including a liquid crystal film 2 is irradiated with light from an light source 20 through a polarizing plate 18a; a polarizing plate 18b is arranged on the opposite side to the light source 20, with respect to the optical film 1; and the defect of the liquid crystal film 2 included in the optical film 1 is inspected through the polarizing plate 18b, wearing dark-blue clean clothes 23. According to the method, even if the clean clothes 23 are irradiated with the light emitted from the light source 20, reflection of the light is fully prevented. Hereby, the reflection of the figure of an inspector M caused by reflected light is prevented sufficiently, and decline in contrast between a defective part and a nondefective part is fully prevented on the optical film 1. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a method for inspecting an optical film including a liquid crystal film.

  In a liquid crystal display, an optical film including a liquid crystal film is often used because it is easy to manufacture and increase the area. An optical film including such a liquid crystal film adversely affects the display of the liquid crystal display when a defect exists in the liquid crystal film. For this reason, it is important to inspect the optical film including the liquid crystal film for defects and to eliminate the optical film having many defects in advance.

  However, a defect inspection method for an optical film including a liquid crystal film is not known as far as the present inventors know.

  On the other hand, the present inventors have so far performed inspection of defects in the optical film as follows. That is, the light emitted from the backlight is irradiated on the optical film through the polarizing plate, and the optical film is observed through another polarizing plate. At this time, the inspector wore clean clothes, and the color of the clean clothes was white.

  However, the inspection method for optical films as described above has the following problems.

  That is, in the above-described optical film inspection method by the present inventors, since the color of the clean clothes is white, the light emitted from the backlight is easily reflected by the clean clothes, and the reflected light gives the appearance of the inspector. In the optical film, the contrast between the defective portion and the non-defective portion is lowered. As a result, the visibility of defects in the liquid crystal film included in the optical film cannot be said to be good, and the defects may be overlooked, and the defect inspection may not be performed accurately.

  The present invention has been made in view of the above circumstances, and provides an optical film inspection method that can sufficiently prevent reflection of light on an optical film and accurately inspect defects. Objective.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by the following invention, and have completed the present invention.

  That is, this invention irradiates light through a 1st polarizing plate with respect to the optical film containing a liquid crystal film, and for the defect inspection which has a 2nd polarizing plate on the opposite side to the said light source with respect to the said optical film. An element is disposed, a clean clothes having a reflectance of 50% or less with respect to visible light is worn, and a defect in the liquid crystal film included in the optical film is inspected through a second polarizing plate. It is an inspection method of an optical film.

  According to this inspection method, even if the light emitted from the light source is applied to the clean clothes, the reflection of the light is sufficiently prevented because the clean clothes are amber. For this reason, the appearance of the inspector due to the reflected light is sufficiently prevented, and a decrease in contrast between the defective portion and the non-defective portion is sufficiently prevented in the optical film.

  Moreover, this invention irradiates light through the 1st polarizing plate from the light source with respect to the optical film containing a liquid crystal film, and is for defect inspection which has a 2nd polarizing plate on the opposite side to the said light source with respect to the said optical film. An element is disposed, and a light having a reflectance of 50% or less with respect to visible light is used to surround the surface opposite to the light source with respect to the optical film, thereby blocking light on the surface, An inspection method for an optical film, comprising: inspecting a defect in the liquid crystal film included in the optical film through two polarizing plates.

  According to this inspection method, even if the light emitted from the light source is irradiated on the inner surface of the curtain, the curtain is amber, so that reflection of light is sufficiently prevented. In addition, the light irradiated from the outside of the curtain is blocked. For this reason, in an optical film, the fall of the contrast of the defect part by a reflected light and a defect free part is fully prevented.

  Furthermore, this invention irradiates light through a 1st polarizing plate with respect to the optical film containing a liquid crystal film, and for a defect inspection which has a 2nd polarizing plate on the opposite side to the said light source with respect to the said optical film. In the liquid crystal film included in the optical film through the second polarizing plate, an element is arranged, and the defect inspection element is formed by using a second polarizing plate as a viewing window formed in the light-shielding member. An inspection method for an optical film characterized by inspecting a defect.

  According to this inspection method, even when light emitted from the light source is irradiated on the face of the inspector, reflection of reflected light onto the optical film is sufficiently prevented by the light shielding member of the defect inspection element. For this reason, in an optical film, the fall of the contrast of the defect part by a reflected light and a defect free part is fully prevented. In addition, by configuring the viewing window formed in the light-shielding member with the second polarizing plate, it is possible to narrow the field of view and concentrate on the inspection.

  In the above inspection method, when a defect in the liquid crystal film is inspected by wearing clean clothes having a reflectance of 50% or less with respect to visible light, or as a defect inspection element, a viewing window formed on the light-shielding member When using the one composed of the second polarizing plate, by surrounding a surface opposite to the light source with respect to the optical film using a curtain having a reflectance of 50% or less with respect to visible light, It is preferable to block light on the surface.

  According to this inspection method, a defect in a liquid crystal film is inspected by wearing clean clothes having a reflectance of 50% or less with respect to visible light, and a defect inspection element is formed on a light-shielding member. Compared with the case where each of the windows is composed of the second polarizing plate, the contrast between the defect portion and the defect-free portion due to the reflected light is more sufficiently prevented.

  In the above inspection method, when a defect in the liquid crystal film is inspected by wearing clean clothes having a reflectance of 50% or less for visible light, a curtain having a reflectance of 50% or less for visible light is used. When using the optical film to surround the surface opposite to the light source to block the light on the surface, or when using these together, the peek formed on the light-shielding member as a defect inspection element It is preferable to use a window composed of a second polarizing plate.

  In this case, the inspection of defects in the liquid crystal film is performed by wearing clean clothes having a reflectance of 50% or less with respect to visible light, and the curtain with a reflectance of 50% or less with respect to visible light. Compared to the case where the optical film is surrounded by the surface opposite to the light source to block the light to the surface, or the combination of these is performed alone, the defect portion and the non-defect caused by the reflected light are compared. A decrease in contrast with the portion is more sufficiently prevented.

  According to the method for inspecting an optical film of the present invention, reflection of light onto the optical film can be sufficiently prevented, and inspection of defects can be accurately performed.

  Hereinafter, embodiments of the optical film inspection method of the present invention will be described in detail with reference to the accompanying drawings.

  First, an optical film to be inspected in the inspection method of the present invention will be described with reference to FIG.

  As shown in FIG. 1, the optical film 1 includes a liquid crystal film 2. As the liquid crystal film 2, for example, a twist alignment liquid crystal film in which the alignment axis is twisted along the thickness direction can be used.

  The optical film 1 only needs to include the liquid crystal film 2, and therefore may include other films in addition to the liquid crystal film 2. As shown in FIG. 1, the other film usually has a laminate 8 composed of the liquid crystal film 2, the overcoat layer 4 and the undercoat layer 6 in addition to the overcoat layer 4 and the undercoat layer 6 sandwiching the liquid crystal film 2. There is a film 10 to be bonded. Examples of such a film 10 include TAC and PET, but polymethyl methacrylate, polystyrene, polycarbonate, polyethersulfone, polyphenylene sulfide, polyarylate, polyethylene sulfide, amorphous polyethylene, and the like can also be used.

  On the other hand, in the inspection method of the present invention, the peelable film 14 is peeled from the optical film 12 with the peelable film shown in FIG. In the optical film 12 with a peelable film, the peelable film 14 is bonded to the optical film 1 directly or via an adhesive 16 such as an acrylic resin to protect the surface of the optical film 1 during transportation. ing. In general, PET is used as the peelable film 14. In addition to PET, for example, polymethyl methacrylate, polystyrene, polycarbonate, polyethersulfone, polyphenylene sulfide, polyarylate, polyethylene sulfide, amorphous polyethylene, triacetyl cellulose, etc. may be used. Can do.

  FIG. 2 is a process diagram showing a flow until the optical film 1 is peeled off from the peelable film 14 and inspected for defects.

  As shown in FIG. 2, the peelable film-attached optical film 12 is wound around a roll 16A to form a roll, and the peelable film-attached optical film 12 is a roll 16B, 16C, 16D, 16E, 16F, 16G. , 16H, and after being passed through the roll 16D and before reaching the roll 16E, the peelable film 14 is peeled off. At this time, the peelable film 14 is peeled by pulling in a direction that forms a predetermined angle with the pulling direction of the optical film 1.

  The optical film 1 exposed by peeling the peelable film 14 with the roll 16D is inspected, for example, between the roll 16E and the roll 16F. Specifically, liquid crystal defects in the liquid crystal film 2 included in the optical film 1 are inspected.

  For example, the defect inspection of the liquid crystal is performed as follows. That is, as shown in FIG. 3, the backlight 20 is disposed opposite to the optical film 1, and the polarizing plate (first polarizing plate) 18 a is disposed between the backlight 20 and the optical film 1. Here, as shown in FIG. 4, the polarizing plate 18a is circular, and is rotatably supported using three pulleys 29a to 29c. The polarizing plate 18a is rotatably supported so that the transmission axis 41 of the polarizing plate 18a can be freely adjusted according to the alignment axis on the backlight 20 side of the liquid crystal film 2 included in the optical film 1. is there. The transmission axis 41 of the polarizing plate 18a is usually adjusted to be at an angle of 45 ° with respect to the alignment axis on the backlight 20 side of the liquid crystal film 2 included in the optical film 1. Here, when the light emission surface of the backlight 20 is larger than the polarizing plate 18a, it becomes difficult to see the defect in the liquid crystal film 2 contained in the optical film 1 by the light emitted from the periphery of the polarizing plate 18a. Therefore, it is preferable that a light shielding member 31 surrounding the polarizing plate 18 a is provided between the backlight 20 and the optical film 1. Then, the backlight 20 is turned on, the optical film 1 is looked through the polarizing plate 18b of the defect inspection element 29 on the side opposite to the backlight 20 with respect to the optical film 1, and the liquid crystal film 2 included in the optical film 1 Inspect for liquid crystal defects.

  At this time, the inspector M inspects the defect in the liquid crystal film 2 by wearing the dark blue clean clothes 23 as clean clothes having a reflectance with respect to visible light of 50% or less. The clean clothes 23 are composed of an upper garment 23a and a lower garment 23b. Further, the light entering the marking surface 1a of the optical film 1 is blocked by surrounding the marking surface 1a on the near side of the optical film 1 with the amber curtain 25 as a curtain having a reflectance with respect to visible light of 50% or less. . Further, as shown in FIG. 5, a defect inspection element 29 in which the viewing window of the light shielding member 27 is configured by a polarizing plate 18 b is used, and the polarizing plate 18 b is a liquid crystal with respect to the polarizing plate 18 a and the optical film 1. When there is no defect in the liquid crystal in the film 2, the film 2 is arranged so that the intensity of light transmitted through the polarizing plate 18b is minimized. Then, when there is a defect in the liquid crystal, the defect portion appears as a bright spot, so that the defect can be inspected. The upper garment 23a and the lower garment 23b may be integrated.

  By inspecting the defects in the liquid crystal film 2 as described above, even when the light emitted from the backlight 20 is irradiated to the clean clothes 23, the clean clothes 23 are amber, so that reflection of light is sufficiently prevented. The For this reason, the appearance of the inspector M due to the reflected light is sufficiently prevented. Further, even when light emitted from the backlight 20 is irradiated onto the inner surface 25a of the curtain 25, the reflection of the light is sufficiently prevented because the curtain 25 is amber. In addition, since the curtain 25 is amber, light emitted from the outside of the curtain 25 can be blocked. Furthermore, even if the light emitted from the backlight 20 is irradiated on the face of the inspector M, the light shielding member 27 sufficiently prevents the reflected light from being reflected on the optical film 1.

  When the inspection of the defect in the optical film 1 is performed as described above, the optical film 1 can sufficiently prevent the decrease in contrast between the defect portion and the defect-free portion due to the reflected light, and the defect inspection can be accurately performed. It can be carried out. In addition, if the polarizing plate 18b is used as a viewing window, the field of view can be narrowed down and the inspection can be concentrated.

  When a defect is found as described above, marking is performed using the marker 17 and the marking ink is dried by the drying device 19 as shown in FIG.

The present invention is not limited to the embodiment described above. For example, in the above-described embodiment, (1) the inspector M performs the inspection of the defect in the liquid crystal film 2 by wearing the amber clean clothes 23, and (2) the front side of the optical film 1 using the amber curtain 25. The light entering the marking surface 1a of the optical film 1 is blocked by surrounding the marking surface 1a, and (3) a viewing window formed on the light-shielding member 27 as the defect inspection element 29 is configured by the polarizing plate 18b. What is necessary is just to perform any one of said (1)-(3) for the inspection method of this invention. Even in that case, it is possible to sufficiently prevent the reflection of light on the optical film 1 and accurately inspect the defect.
Moreover, in the said embodiment, although the amber thing is used as a clean clothes and a curtain from which the reflectance with respect to visible light will be 50% or less, the reflectance with respect to visible light is 50 as such a clean clothes and curtain. % Or less. Therefore, as the color of the clean clothes and curtains used in the inspection method of the present invention, black, purple, blue, green, etc. can be used in addition to the amber color.

It is a schematic side view which shows an example of the optical film with a peelable film used for the inspection method of the optical film of this invention. It is process drawing which shows the flow until the optical film used for the inspection method of the optical film of this invention peels a peelable film and carries out a defect inspection. It is a partially notched side view which shows a mode that the defect inspection in the liquid crystal film contained in an optical film is performed. It is a front view which shows the element for a defect inspection provided with the polarizing plate used for the inspection method of the optical film of this invention. It is a front view which shows the polarizing plate and light source which are used in the inspection method of the optical film of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Optical film, 2 ... Liquid crystal film, 18a ... Polarizing plate (1st polarizing plate), 18b ... Polarizing plate (2nd polarizing plate), 20 ... Backlight (light source), 23 ... Clean clothes, 25 ... Curtain , 27 ... light-shielding member, 29 ... element for defect inspection.

Claims (5)

The optical film including the liquid crystal film is irradiated with light from the light source through the first polarizing plate,
Arranging a defect inspection element having a second polarizing plate on the side opposite to the light source with respect to the optical film,
Wearing clean clothes with a reflectance of 50% or less with respect to visible light, and inspecting the defects in the liquid crystal film contained in the optical film through the second polarizing plate,
An inspection method for an optical film. The optical film including the liquid crystal film is irradiated with light from the light source through the first polarizing plate,
Arranging a defect inspection element having a second polarizing plate on the side opposite to the light source with respect to the optical film,
Using a curtain having a reflectance of 50% or less with respect to visible light, surrounding the surface on the side opposite to the light source with respect to the optical film blocks light to the surface, and the second polarized light Inspect for defects in the liquid crystal film contained in the optical film through a plate,
An inspection method for an optical film. The optical film including the liquid crystal film is irradiated with light from the light source through the first polarizing plate,
Arranging a defect inspection element having a second polarizing plate on the side opposite to the light source with respect to the optical film,
As the defect inspection element, an inspection window formed in the light-shielding member is configured by the second polarizing plate, and the defect in the liquid crystal film included in the optical film is inspected through the second polarizing plate. To
An inspection method for an optical film.   The light on the surface is blocked by surrounding the surface opposite to the light source with respect to the optical film using a curtain having a reflectance of 50% or less with respect to visible light. The inspection method of the optical film of 1 or 3.   5. The optical film inspection method according to claim 1, wherein the defect inspection element includes a viewing window formed in a light-shielding member formed of the second polarizing plate.

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