JP2006003174A - Method for inspecting optical film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for inspecting an optical film to accurately inspect its defects owing to thickness nonuniformity. <P>SOLUTION: This method is for inspecting an optical film 1 including a liquid crystal film 2 made by hybrid-nematically orienting liquid crystal. The optical film 1 is illuminated with light from a light source 20 through a polarization plate 18a to inspect an element 29. The element 29 is made by layering a liquid crystal film 31 and a polarization plate 18b, with the crystal film 31 made by hybrid-nematically orienting liquid crystal. The element 29 is disposed so that the crystal film 31 is directed to the optical film 1 side and that an orientation axis 43 of the crystal film 31 is non-parallel to an orientation axis 42 of the crystal film 2. In this event, a non-defective portion and a defective portion can be made to differ from each other in phase difference when the light from the light source 20 passes through the polarization plate 18a and the optical film 1, and contrast can be given between the non-defective portion and the defective portion. <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 which liquid crystal is hybrid nematically aligned.

  In a TFT (Thin Film Transistor) liquid crystal display, a liquid crystal film in which liquid crystal is hybrid nematically oriented, a so-called NH film, is used to improve the display characteristics. An optical film including such an NH film adversely affects the display characteristics of the TFT liquid crystal display when a defect exists in the NH film. For this reason, it is necessary to inspect the optical film including the NH film for defects and to eliminate the optical film having many defects in advance.

  However, a defect inspection method for an optical film including an NH 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 transmission axis of the polarizing plate on the backlight side and the alignment axis (projection component of the alignment vector of the liquid crystal on the polarizing plate surface) of the NH film were made parallel to the optical film.

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

  That is, in the above optical film inspection method by the present inventors, when the optical film is sandwiched between two polarizing plates in a crossed Nicol state and light is irradiated through the polarizing plate from the opposite side of the optical film, the liquid crystal is misaligned. Although the resulting defect can be visually recognized as a bright spot, the defect due to the thickness unevenness due to dust mixed in the NH film is hardly visible. For this reason, there is a possibility that a defect due to thickness unevenness may be overlooked and the defect inspection cannot be performed accurately.

  This invention is made | formed in view of the said situation, and it aims at providing the inspection method of the optical film which can test | inspect correctly the defect resulting from thickness nonuniformity.

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

  That is, the present invention is an inspection method of an optical film including a first liquid crystal film in which liquid crystals are hybrid nematically aligned. The optical film is irradiated with light from a light source through a first polarizing plate, and the optical film is irradiated. A defect inspection element in which a second liquid crystal film in which liquid crystal is hybrid nematically aligned and a second polarizing plate is laminated on the side opposite to the light source so that the second liquid crystal film faces the optical film side and The optical film inspection method is characterized by inspecting the optical film by arranging the second liquid crystal film so that an alignment axis of the second liquid crystal film is not parallel to the alignment axis of the first liquid crystal film.

  According to this inspection method, when the first liquid crystal film has a thickness unevenness, when the light emitted from the light source passes through the first polarizing plate and the optical film, the defect-free portion and the defect-free portion have different thicknesses. It becomes possible to make a difference in the phase difference between the defect portion and the contrast between the defect-free portion and the defect portion. Therefore, it becomes possible to improve the visibility of a defective part.

  The present invention is also a method for inspecting an optical film including a first liquid crystal film in which liquid crystal is hybrid nematically aligned. The optical film is irradiated with light from a light source through a first polarizing plate. The second liquid crystal film in which liquid crystal is hybrid nematically aligned on the side opposite to the light source, and the phase difference obtained when light passes through the first liquid crystal film and the second liquid crystal film can be reduced. A defect inspection element formed by sequentially laminating a retardation reducing element and a second polarizing plate is disposed so that the second liquid crystal film faces the optical film and the alignment axis of the second liquid crystal film is the first. An inspection method for an optical film, wherein the optical film is inspected by being arranged so as to be parallel or antiparallel to an alignment axis of the liquid crystal film.

  According to this inspection method, when the first liquid crystal film has a thickness unevenness, when the light emitted from the light source passes through the first polarizing plate and the optical film, the defect-free portion and the defect-free portion have different thicknesses. It is possible to make a difference in the phase difference between the defective part. In addition, since the phase difference reducing element is included in the defect inspection element, it is possible to reduce the phase difference obtained when light passes through the first liquid crystal film and the second liquid crystal film. It is possible to produce contrast between the two. Therefore, it becomes possible to improve the visibility of a defective part. In addition, according to the inspection method of the present invention, since the symmetry between the alignment axis of the first liquid crystal film and the alignment axis of the second liquid crystal film is high, the alignment axes are asymmetric between the first liquid crystal film and the second liquid crystal film. Compared with the case where it is, it can improve a display characteristic more.

  The present invention is also a method for inspecting an optical film including a first liquid crystal film in which liquid crystal is hybrid nematically aligned, and the optical film is irradiated with light from a light source through a first polarizing plate and a first retardation reducing element. Then, light passes through the second liquid crystal film in which the liquid crystal is hybrid nematically oriented on the side opposite to the light source with respect to the optical film, the first retardation reducing element, the first liquid crystal film, and the second liquid crystal film. A defect inspection element formed by sequentially laminating a second phase difference reducing element capable of reducing a phase difference obtained when transmitting together with the first phase difference reducing element, and a second polarizing plate, 2 The liquid crystal film is arranged so that it faces the optical film side, and the alignment axis of the second liquid crystal film is parallel or anti-parallel to the alignment axis of the first liquid crystal film. An inspection method of an optical film characterized in that checking the serial optical film.

  According to this inspection method, when the first liquid crystal film is uneven in thickness, when light emitted from the light source passes through the first polarizing plate, the first retardation reducing element, and the optical film, the defect-free portion and the defect-free portion are obtained. It is possible to make a difference in phase difference between a portion and a defective portion having a different thickness. Further, the second phase difference reducing element and the first phase difference reducing element included in the defect inspection element can reduce the phase difference obtained when light passes through the first liquid crystal film and the second liquid crystal film. Become. For this reason, it becomes possible to produce contrast between a defect-free part and a defective part. Therefore, it becomes possible to improve the visibility of a defective part. In addition, according to the inspection method of the present invention, since the symmetry between the alignment axis of the first liquid crystal film and the alignment axis of the second liquid crystal film is high, the alignment axes are asymmetric between the first liquid crystal film and the second liquid crystal film. Compared with the case where it is, it can improve a display characteristic more.

  According to the optical film inspection method of the present invention, it is possible to accurately inspect defects caused by thickness unevenness.

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

(First embodiment)
First, a first embodiment of an optical film inspection method according to the present invention will be described.

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

  FIG. 1 is a diagram showing an example of an optical film used in the optical film inspection method of the present invention. As shown in FIG. 1, the optical film 1 is a first liquid crystal film, a liquid crystal film (hereinafter referred to as “NH film”) in which the liquid crystal is hybrid nematically aligned by changing the tilt of the liquid crystal in the film thickness direction (arrow A direction). 2). Here, the hybrid nematic alignment means an alignment in which the horizontal alignment and the vertical alignment of the nematic liquid crystal are combined. For example, the alignment of the nematic liquid crystal is the horizontal alignment on the one surface 40a side of the NH film 2, and the one surface 40a The surface 40b side opposite to the vertical alignment is vertical alignment, and in the meantime, the alignment gradually changes from horizontal alignment to vertical alignment along the direction from the surface 40a to the surface 40b.

  The optical film 1 only needs to include the NH film 2, and thus may include other films in addition to the NH film 2. Other films typically include a support substrate 3 that supports the NH film 2 as shown in FIG. The support substrate 3 is not particularly limited as long as it can support the NH film 2 and exhibits isotropic properties in a plane orthogonal to the thickness direction. Acetyl cellulose) film is used.

  Such defects of the optical film 1 are inspected as follows. In addition, the defect of the optical film 1 specifically means a defect of liquid crystal in the NH film 2 included in the optical film 1.

  FIG. 2 is a side view showing an example of an inspection optical system for an optical film in the present embodiment. FIG. 3 is a diagram illustrating an example of an arrangement relationship between the orientation axis of the NH film 2 included in the optical film 1, the transmission axis of the polarizing plate 18a described later, the orientation axis of the NH film 31, and the transmission axis of the polarizing plate 18b. (A) shows the transmission axis of the polarizing plate 18a, (b) shows the orientation axis of the NH film 2, (c) shows the orientation axis of the NH film 31, and (d) shows the transmission axis of the polarizing plate 18b.

  In the defect inspection of the optical film 1, first, the backlight 20 is disposed opposite to the optical film 1, and a polarizing plate (first polarizing plate) 18 a is disposed between the backlight 20 and the optical film 1. As shown in FIGS. 3A and 3B, in this embodiment, the transmission axis 41 of the polarizing plate 18 a is at an angle of 45 ° with respect to the orientation axis 42 of the NH film 2 included in the optical film 1. Adjust as follows. Here, the orientation axis 42 of the NH film 2 refers to a projection component on the surface of the polarizing plate 18a of the orientation vector of the liquid crystal horizontally oriented near the surface of the NH film 2.

  Then, as shown in FIG. 2, the backlight 20 is turned on, and the optical film 1 is looked into using the defect inspection element 29 on the side opposite to the backlight 20 with respect to the optical film 1. The NH film 2 is inspected for defects.

  Here, the defect inspection element 29 will be described in detail.

  As shown in FIG. 2, the defect inspection element 29 is formed by laminating a polarizing plate 18 b and an NH film (second liquid crystal film) 31. The NH film 31 is a liquid crystal film in which the liquid crystal is hybrid nematically aligned by changing the tilt of the liquid crystal in the film thickness direction (the direction of arrow A in FIG. 1).

  In the defect inspection element 29 of the present embodiment, the NH film 31 is the same as the NH film 2 in material and thickness, and the orientation of the NH film 31 is as shown in FIGS. The axis 43 is laminated on the polarizing plate 18b so as to be 45 ° with respect to the transmission axis 44 of the polarizing plate 18b.

  In the defect inspection, first, the defect inspection element 29 configured as described above is disposed opposite to the optical film 1. At this time, the NH film 31 is directed to the optical film 1 side, the polarizing plate 18b is directed to the side opposite to the optical film 1, and the polarizing plate 18b and the polarizing plate 18a are arranged in a crossed Nicols arrangement. Thereby, the orientation axis 43 of the NH film 31 can be orthogonal to the orientation axis 42 of the NH film 2 included in the optical film 1 as shown in FIGS.

  Thus, when the defect inspection element 29 is arranged with respect to the optical film 1, the transmission axis 41 of the polarizing plate 18a and the orientation axis 42 of the NH film 2 become non-parallel. Therefore, when the NH film 2 is uneven in thickness, that is, as shown in FIG. 4, when there is a defect-free portion 2a having a thickness d2 and a defect portion 2b having a thickness d1, the light is emitted from the backlight 20. When light passes through the polarizing plate 18a and the optical film 1, a difference is caused in the phase difference generated between the direction of the transmission axis 41 of the polarizing plate 18a and the direction perpendicular thereto in each of the defect-free portion 2a and the defective portion 2b. It becomes possible. In FIG. 4, what is embedded in the defective portion 2 b and indicated by reference numeral 45 is dust or the like mixed during the manufacture of the NH film 2.

  More specifically, in the defect-free portion 2a, the phase difference δ2 is δ2 = Δn · d2, whereas in the defective portion 2b, the phase difference δ1 is δ1 = Δn · d1. Here, since d1> d2, δ2 <δ1.

  For this reason, it becomes possible to produce contrast between the defect-free portion 2a and the defect portion 2b. Here, the orientation axis 42 of the NH film 2 and the orientation axis 43 of the NH film 31 are orthogonal to each other as described above. For this reason, when the NH film 2 and the NH film 31 have the same thickness, the birefringence of the NH film 2 and the birefringence of the NH film 31 cancel each other, so that the phase difference is canceled, that is, zero. The polarizing plate 18a and the polarizing plate 18b are in a crossed Nicols arrangement. Therefore, the defect-free portion 2a becomes completely dark and the defect portion 2b appears as a bright spot. Therefore, it becomes possible to improve the visibility of the defective portion 2a, and it is possible to accurately inspect the defect caused by the thickness unevenness.

  When a defect is found as described above, marking is performed using a marker, the marking ink is dried with a drying device, and the defect inspection is completed.

(Second Embodiment)
Next, 2nd Embodiment of the inspection method of the optical film which concerns on this invention is described using FIGS. 5 to 8, the same or equivalent components as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 5 is a side view showing an example of an optical film inspection optical system in the second embodiment of the optical film inspection method according to the present invention. FIG. 6 shows the positional relationship between the orientation axis of the NH film 2 included in the optical film 1, the transmission axis of the polarizing plate 18a, the orientation axis of the NH film 31, the orientation axes of the uniaxial films 34 and 35, and the transmission axis of the polarizing plate 18b. (A) is the transmission axis of the polarizing plate 18a, (b) is the orientation axis of the NH film 2, (c) is the orientation axis of the NH film 31, and (d) and (e) are uniaxial films. (F) indicates the transmission axis of the polarizing plate 18b.

  The inspection method of the present embodiment is different from the first embodiment in that the defect inspection element 33 is configured as follows.

  That is, as shown in FIG. 5, the defect inspection element 33 of the present embodiment has the defect of the first embodiment in that it includes two uniaxial films 34 and 35 between the NH film 31 and the polarizing plate 18b. Different from the testing element 29. The uniaxial films 34 and 35 function as retardation reducing elements that can reduce the retardation obtained when light passes through the NH film 2 and the NH film 31. The uniaxial films 34 and 35 have birefringence in a plane orthogonal to the thickness direction. As such uniaxial films 34 and 35, for example, a PC film, a TAC film, Arton (manufactured by JSR), ZEONOR (manufactured by Nippon Zeon), and the like are used. A uniaxial film is obtained by stretching the film in one direction within a plane orthogonal to the thickness direction.

  Here, from the viewpoint of improving the visibility of defects caused by thickness unevenness, the two uniaxial films 34 and 35 have a phase difference obtained when light passes through the NH film 2 and the NH film 31. It is preferable that it can be made zero. In order to make the phase difference zero, as shown in FIGS. 6E and 6F, the orientation axis of the uniaxial film 35 makes an angle of 90 ° with respect to the transmission axis 44 of the polarizing plate 18b. 6 (d) and 6 (f), the orientation axis of the uniaxial film 34 is arranged so as to form an angle of 45 ° with respect to the transmission axis 44 of the polarizing plate 18b.

  In addition, the defect inspection element 33 of the present embodiment is arranged in such a manner that the defect inspection element 33 is disposed opposite to the optical film 1 so that the polarizing plate 18b and the polarizing plate 18a are arranged in a crossed Nicol arrangement as shown in FIG. As shown in b) and (c), it differs from the defect inspection element 29 of the first embodiment in that the orientation axis 43 of the NH film 31 is antiparallel to the orientation axis 42 of the NH film 2. For this purpose, for example, as shown in FIGS. 6C and 6F, in the defect inspection element 33, the orientation axis 43 of the NH film 31 is 45 ° with respect to the transmission axis 44 of the polarizing plate 18b. Placed in.

  Here, the orientation of the orientation axis of the NH film is determined as to whether the liquid crystal molecules are standing on either side of the liquid crystal molecules when the liquid crystal molecule group in the thickness direction is viewed with respect to the horizontal alignment state of the liquid crystal molecules. Judge. Therefore, for example, in FIG. 7, since the lower end portion of the liquid crystal molecules rises in the NH film 31, the alignment axis 43 of the NH film 31 faces downward, and in the NH film 2, the upper end portion of the liquid crystal molecules rises. It will be upward. When the orientation axes are in opposite directions, the orientation axis 43 of the NH film 31 and the orientation axis 42 of the NH film 2 are said to be antiparallel. In FIG. 8, in the NH film 31, the upper end of the liquid crystal molecules rises, so the orientation axis 43 of the NH film 31 faces upward. In the NH film 2, the upper end of the liquid crystal molecules rises. The orientation axis 42 of the film 2 is upward. When the orientation axes are in the same direction, the orientation axis 43 of the NH film 31 and the orientation axis 42 of the NH film 2 are said to be parallel.

  When inspecting a defect in the optical film 1 using such a defect inspection element 33, first, the defect inspection element 33 is disposed opposite to the optical film 1. At this time, the NH film 31 is directed to the optical film 1 side, the polarizing plate 18b is directed to the side opposite to the optical film 1, and the polarizing plate 18b and the polarizing plate 18a are arranged in a crossed Nicol arrangement. Thereby, the orientation axis 43 of the NH film 31 can be made antiparallel to the orientation axis 42 of the NH film 2 included in the optical film 1.

  When the defect inspection element 33 is thus arranged with respect to the optical film 1, since the transmission axis 41 of the polarizing plate 18a and the orientation axis 42 of the NH film 2 are non-parallel, as in the inspection method of the first embodiment, A contrast can be generated between the defect-free portion and the defect portion. Here, the orientation axis 42 of the NH film 2 and the orientation axis 43 of the NH film 31 are antiparallel. For this reason, even if the thicknesses of the NH film 2 and the NH film 31 are equal, the phase difference is not canceled, i.e., does not become zero. However, the uniaxial films 34 and 35 cancel out the phase difference that was not canceled out by the NH film 2 and the NH film 31 alone. The polarizing plate 18a and the polarizing plate 18b are in a crossed Nicols arrangement. Therefore, the defect-free portion becomes dark and the defect portion appears as a bright spot. Therefore, it becomes possible to improve the visibility of a defective part, and the inspection of the defect resulting from thickness nonuniformity can be performed exactly. In addition, in the inspection method of this embodiment, the orientation axis 42 of the NH film 2 and the orientation axis 43 of the NH film 31 are antiparallel, and the orientation axis 42 of the NH film 2 and the orientation axis 43 of the NH film 31 are. And the symmetry is high. For this reason, according to the inspection method of the present embodiment, the display characteristics can be further improved as compared with the case where the alignment axis is asymmetric between the NH film 2 and the NH film 31.

(Third embodiment)
Next, a third embodiment of the optical film inspection method according to the present invention will be described with reference to FIG. In FIG. 9, the same or equivalent components as those in the first and second embodiments are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 9 is a diagram showing an arrangement relationship at the time of defect inspection between the orientation axes of the NH film, the transmission axis of the polarizing plate, and the orientation axes of the uniaxial film and the biaxial film. In FIG. 9, the polarizing plate or the film is sequentially arranged at a position farther from the light source as it goes from the left side (the polarizing plate 18 a side) to the right side (the polarizing plate 18 b side).

  The inspection method of this embodiment is different from that of the first embodiment in that the defect inspection element 60 is configured as follows.

  That is, as shown in FIG. 9, the defect inspection element 60 of the present embodiment is the first in that it includes one biaxial film 56 and one uniaxial film 35 between the NH film 31 and the polarizing plate 18 b. Different from the defect inspection element 29 of the embodiment. The uniaxial film 35 and the biaxial film 56, together with the uniaxial film 52 and the biaxial film 53, can reduce the phase difference obtained when light passes through the NH film 2 and the NH film 31. It functions as an element. The uniaxial film 35 and the biaxial film 56 have birefringence in a plane orthogonal to the thickness direction.

  In addition, the defect inspection element 60 of the present embodiment is configured so that the defect inspection element 60 is disposed opposite to the optical film 1 and the optical film 1 so that the polarizing plate 18a and the polarizing plate 18b are arranged in a crossed Nicol arrangement. As shown in FIG. 9, it differs from the defect inspection element 29 of the first embodiment in that the orientation axis of the NH film 2 is antiparallel to the orientation axis of the NH film 31.

  In the inspection of the optical film 1 using the defect inspection element 60, the uniaxial film 52 and the biaxial film 53 are sequentially disposed between the polarizing plate 18a and the NH film 2 from the polarizing plate 18a side. Here, the uniaxial film 52 and the biaxial film 53 have birefringence in a plane orthogonal to the thickness direction. And the optical film 1 is test | inspected like the 2nd Embodiment using the said element 60 for defect inspection.

  Here, the two uniaxial films 52 and 35 and the two biaxial films 53 and 56 are light-emitted on the NH film 2 and the NH film 31 from the viewpoint of improving the visibility of defects caused by thickness unevenness. It is preferable that the phase difference obtained when transmitting can be made zero. In order to make the phase difference zero, as shown in FIG. 9, the orientation of the uniaxial film 35 is such that the orientation axis of the uniaxial film 52 forms an angle of 20 degrees with respect to the transmission axis of the polarizing plate 18a. The axis is arranged so as to form an angle of 70 degrees with respect to the transmission axis of the polarizing plate 18b. The orientation axis of the biaxial film 53 makes an angle of 20 degrees with respect to the transmission axis of the polarizing plate 18a, and the orientation axis of the biaxial film 56 makes an angle of 70 degrees with respect to the transmission axis of the polarizing plate 18b. It is arranged to make. In the present specification, the orientation axis of the biaxial film refers to an axis along a direction in which the refractive index is larger among two directions orthogonal to each other in a plane orthogonal to the thickness direction.

  Examples of the retardation reducing element such as the uniaxial film and the biaxial film as described above include PC film, TAC film, Arton (manufactured by JSR), ZEONOR (manufactured by ZEON Corporation), and the like. The uniaxial film is obtained by stretching the film in one direction in a plane orthogonal to the thickness direction, and the biaxial film is a biaxial film in which the film is orthogonal in the plane orthogonal to the thickness direction. It is obtained by stretching in the direction.

(Fourth embodiment)
Next, 4th Embodiment of the inspection method of the optical film which concerns on this invention is described using FIG. In FIG. 10, the same or equivalent components as those in the first and second embodiments are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 10 is a diagram showing an arrangement relationship during defect inspection between the orientation axes of the NH film, the transmission axis of the polarizing plate, and the orientation axes of the uniaxial film and the biaxial film. In addition, in FIG. 10, a polarizing plate or a film is arrange | positioned in the position far from a light source one by one as it goes to the right side from the left side.

  The inspection method of the present embodiment is different from the first embodiment in that the defect inspection element 61 is configured as follows.

  That is, as shown in FIG. 10, the defect inspection element 61 according to the present embodiment has a single biaxial film 56 between the NH film 31 and the polarizing plate 18b. Different from the element 29. The biaxial film 56 functions as a retardation reducing element capable of reducing the retardation obtained when light passes through the NH film 2 and the NH film 31 together with the uniaxial film 52 and the biaxial film 53. It is. The biaxial film 56 has birefringence in a plane orthogonal to the thickness direction.

  Further, the defect inspection element 61 of the present embodiment is arranged so that the defect inspection element 61 is opposed to the optical film 1 and the optical film 1 so that the polarizing plate 18a and the polarizing plate 18b form an angle of 100 degrees. In this case, as shown in FIG. 10, it differs from the defect inspection element 29 of the first embodiment in that the orientation axis of the NH film 2 is antiparallel to the orientation axis of the NH film 31.

  In the inspection of the optical film 1 using the defect inspection element 61, the uniaxial film 52 and the biaxial film 53 are sequentially disposed between the polarizing plate 18a and the NH film 2 from the polarizing plate 18a side. Here, the uniaxial film 52 and the biaxial film 53 have birefringence in a plane orthogonal to the thickness direction. Then, the optical film 1 is inspected using the defect inspection element 61 in the same manner as in the second embodiment.

  Here, the two uniaxial films 52 and the two biaxial films 53 and 56 transmit light through the NH film 2 and the NH film 31 from the viewpoint of improving the visibility of defects caused by thickness unevenness. It is preferable that the phase difference sometimes obtained can be made zero. In order to make the phase difference zero, as shown in FIG. 10, the orientation axis of the uniaxial film 52 is arranged to form an angle of 101 degrees with respect to the transmission axis of the polarizing plate 18a. The orientation axis of the biaxial film 53 makes an angle of 110 degrees with respect to the transmission axis of the polarizing plate 18a, and the orientation axis of the biaxial film 56 makes an angle of 10 degrees with respect to the transmission axis of the polarizing plate 18b. It is arranged to make.

  As the retardation reducing elements such as the uniaxial film and the biaxial film as described above, the same elements as those in the third embodiment are used.

(Fifth embodiment)
Next, 5th Embodiment of the inspection method of the optical film which concerns on this invention is described using FIG. In FIG. 11, the same or equivalent components as those in the first and second embodiments are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 11 is a diagram showing an arrangement relationship at the time of defect inspection between the orientation axes of the NH film, the transmission axis of the polarizing plate, and the orientation axes of the uniaxial film and the biaxial film. In addition, in FIG. 11, a polarizing plate or a film is arrange | positioned in the position far from a light source one by one as it goes to the right side from the left side.

  The inspection method of this embodiment is different from that of the first embodiment in that the defect inspection element 62 is configured as follows.

  That is, as shown in FIG. 11, the defect inspection element 62 of the present embodiment has the biaxial film 56 and the uniaxial film 35 between the NH film 31 and the polarizing plate 18b. Different from the testing element 29. The uniaxial film 35 and the biaxial film 56, together with the uniaxial film 52 and the biaxial film 53, can reduce the phase difference obtained when light passes through the NH film 2 and the NH film 31. It functions as an element. The uniaxial film 35 and the biaxial film 56 have birefringence in a plane orthogonal to the thickness direction.

  In the defect inspection element 62 of the present embodiment, the defect inspection element 62 is disposed opposite to the optical film 1 of the optical film 1 so that the polarizing plate 18a and the polarizing plate 18b are arranged in a crossed Nicol arrangement. In addition, as shown in FIG. 11, it differs from the defect inspection element 29 of the first embodiment in that the orientation axis of the NH film 2 is antiparallel to the orientation axis of the NH film 31.

  Here, the two uniaxial films 52 and 35 and the two biaxial films 53 and 56 are light-emitted on the NH film 2 and the NH film 31 from the viewpoint of improving the visibility of defects caused by thickness unevenness. It is preferable that the phase difference obtained when transmitting can be made zero. In order to make the phase difference zero, as shown in FIG. 11, the orientation of the uniaxial film 35 is such that the orientation axis of the uniaxial film 52 forms an angle of 5 degrees with respect to the transmission axis of the polarizing plate 18a. The axis is arranged so as to form an angle of 95 degrees with respect to the transmission axis of the polarizing plate 18b. The orientation axis of the biaxial film 53 makes an angle of 5 degrees with respect to the transmission axis of the polarizing plate 18a, and the orientation axis of the biaxial film 56 makes an angle of 95 degrees with respect to the transmission axis of the polarizing plate 18b. It is arranged to make.

  In the inspection of the optical film 1 using the defect inspection element 62, the uniaxial film 52 and the biaxial film 53 are sequentially disposed between the polarizing plate 18a and the NH film 2 from the polarizing plate 18a side. Here, the uniaxial film 52 and the biaxial film 53 have birefringence in a plane orthogonal to the thickness direction. Then, the optical film 1 is inspected using the defect inspection element 62 in the same manner as in the second embodiment.

  As the retardation reducing elements such as the uniaxial film and the biaxial film as described above, the same elements as those in the third embodiment are used.

(Sixth embodiment)
Next, a sixth embodiment of the optical film inspection method according to the present invention will be described with reference to FIG. In FIG. 12, the same or equivalent components as those in the first and second embodiments are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 12 is a diagram showing an arrangement relationship at the time of defect inspection between the orientation axes of the NH film, the transmission axis of the polarizing plate, and the orientation axes of the uniaxial film and the biaxial film. In FIG. 12, the polarizing plate or film is sequentially arranged at a position farther from the light source as it goes from the left side to the right side.

  The inspection method of this embodiment is different from that of the first embodiment in that the defect inspection element 63 is configured as follows.

  That is, as shown in FIG. 12, the defect inspection element 63 according to the present embodiment has the biaxial film 56 and the uniaxial film 35 between the NH film 31 and the polarizing plate 18b. Different from the testing element 29. The uniaxial film 35 and the biaxial film 56, together with the uniaxial film 52 and the biaxial film 53, can reduce the phase difference obtained when light passes through the NH film 2 and the NH film 31. It functions as an element. The uniaxial film 35 and the biaxial film 56 have birefringence in a plane orthogonal to the thickness direction.

  Further, the defect inspection element 63 of the present embodiment is arranged so that the defect inspection element 63 is opposed to the optical film 1 and the optical film 1 so that the polarizing plate 18a and the polarizing plate 18b form an angle of 95 degrees. In this case, as shown in FIG. 12, the NH film 2 is different from the defect inspection element 29 in that the orientation axis of the NH film 2 is antiparallel to the orientation axis of the NH film 31.

  Here, the two uniaxial films 52 and 35 and the two biaxial films 53 and 56 are light-emitted on the NH film 2 and the NH film 31 from the viewpoint of improving the visibility of defects caused by thickness unevenness. It is preferable that the phase difference obtained when transmitting can be made zero. In order to make the phase difference zero, as shown in FIG. 12, the orientation of the uniaxial film 35 is such that the orientation axis of the uniaxial film 52 forms an angle of 10 degrees with respect to the transmission axis of the polarizing plate 18a. The axis is arranged to form an angle of 110 degrees with respect to the transmission axis of the polarizing plate 18b. The orientation axis of the biaxial film 53 forms an angle of 10 degrees with respect to the transmission axis of the polarizing plate 18a, and the orientation axis of the biaxial film 56 forms an angle of 110 degrees with respect to the transmission axis of the polarizing plate 18b. It is arranged to make.

  In the inspection of the optical film 1 using the defect inspection element 63, the uniaxial film 52 and the biaxial film 53 are sequentially disposed between the polarizing plate 18a and the NH film 2 from the polarizing plate 18a side. Here, the uniaxial film 52 and the biaxial film 53 have birefringence in a plane orthogonal to the thickness direction. Then, the optical film 1 is inspected using the defect inspection element 63 in the same manner as in the second embodiment.

  As the retardation reducing elements such as the uniaxial film and the biaxial film as described above, the same elements as those in the third embodiment are used.

(Seventh embodiment)
Next, a seventh embodiment of the optical film inspection method according to the present invention will be described with reference to FIG. In FIG. 13, the same or equivalent components as those in the first and second embodiments are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 13 is a diagram showing an arrangement relationship at the time of defect inspection between the orientation axes of the NH film, the transmission axis of the polarizing plate, and the orientation axes of the uniaxial film and the biaxial film. In FIG. 13, the polarizing plate or film is sequentially arranged at a position farther from the light source as it goes from the left side to the right side.

  The inspection method of the present embodiment is different from the first embodiment in that the defect inspection element 64 is configured as follows.

  That is, as shown in FIG. 13, the defect inspection element 64 according to the present embodiment has the biaxial film 56 and the uniaxial film 35 between the NH film 31 and the polarizing plate 18b. Different from the testing element 29. The uniaxial film 35 and the biaxial film 56, together with the uniaxial film 52 and the biaxial film 53, can reduce the phase difference obtained when light passes through the NH film 2 and the NH film 31. It functions as an element. The uniaxial film 35 and the biaxial film 56 have birefringence in a plane orthogonal to the thickness direction.

  Further, the defect inspection element 64 of the present embodiment is arranged so that the defect inspection element 64 faces the optical film 1 of the optical film 1 and the polarizing plate 18a and the polarizing plate 18b form an angle of 95 degrees. In this case, as shown in FIG. 13, the NH film 2 is different from the defect inspection element 29 in that the orientation axis of the NH film 2 is antiparallel to the orientation axis of the NH film 31.

  Here, the two uniaxial films 52 and 35 and the two biaxial films 53 and 56 are light-emitted on the NH film 2 and the NH film 31 from the viewpoint of improving the visibility of defects caused by thickness unevenness. It is preferable that the phase difference obtained when transmitting can be made zero. In order to make the phase difference zero, as shown in FIG. 13, the orientation of the uniaxial film 35 is such that the orientation axis of the uniaxial film 52 forms an angle of 10 degrees with respect to the transmission axis of the polarizing plate 18a. The axis is arranged to form an angle of 110 degrees with respect to the transmission axis of the polarizing plate 18b. The orientation axis of the biaxial film 53 forms an angle of 10 degrees with respect to the transmission axis of the polarizing plate 18a, and the orientation axis of the biaxial film 56 forms an angle of 110 degrees with respect to the transmission axis of the polarizing plate 18b. It is arranged to make.

  In the inspection of the optical film 1 using the defect inspection element 64, the uniaxial film 52 and the biaxial film 53 are sequentially disposed between the polarizing plate 18a and the NH film 2 from the polarizing plate 18a side. Here, the uniaxial film 52 and the biaxial film 53 have birefringence in a plane orthogonal to the thickness direction. Then, the optical film 1 is inspected using the defect inspection element 64 in the same manner as in the second embodiment.

  As the retardation reducing elements such as the uniaxial film and the biaxial film as described above, the same elements as those in the third embodiment are used.

(Eighth embodiment)
Next, 8th Embodiment of the inspection method of the optical film which concerns on this invention is described using FIG. In FIG. 14, the same or equivalent components as those in the first and second embodiments are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 14 is a diagram showing an arrangement relationship during defect inspection between the orientation axes of the NH film, the transmission axis of the polarizing plate, and the orientation axes of the uniaxial film and the biaxial film. In FIG. 14, the polarizing plate or film is sequentially arranged at a position farther from the light source as it goes from the left side to the right side.

  The inspection method of the present embodiment is different from the first embodiment in that the defect inspection element 65 is configured as follows.

  That is, as shown in FIG. 14, the defect inspection element 65 of the present embodiment has the biaxial film 56 and the uniaxial film 35 between the NH film 31 and the polarizing plate 18b. Different from the testing element 29. The uniaxial film 35 and the biaxial film 56, together with the uniaxial film 52 and the biaxial film 53, can reduce the phase difference obtained when light passes through the NH film 2 and the NH film 31. It functions as an element. The uniaxial film 35 and the biaxial film 56 have birefringence in a plane orthogonal to the thickness direction.

  Further, the defect inspection element 65 of the present embodiment is a case where the defect inspection element 65 is disposed opposite to the optical film 1 and the optical film 1 so that the polarizing plate 18a and the polarizing plate 18b are arranged in a crossed Nicol arrangement. In addition, as shown in FIG. 14, it differs from the defect inspection element 29 of the first embodiment in that the orientation axis of the NH film 2 is antiparallel to the orientation axis of the NH film 31.

  Here, the two uniaxial films 52 and 35 and the two biaxial films 53 and 56 are light-emitted on the NH film 2 and the NH film 31 from the viewpoint of improving the visibility of defects caused by thickness unevenness. It is preferable that the phase difference obtained when transmitting can be made zero. In order to make the phase difference zero, as shown in FIG. 14, the orientation of the uniaxial film 35 is such that the orientation axis of the uniaxial film 52 forms an angle of 125 degrees with respect to the transmission axis of the polarizing plate 18a. The axis is arranged so as to form an angle of 70 degrees with respect to the transmission axis of the polarizing plate 18b. The orientation axis of the biaxial film 53 makes an angle of 125 degrees with respect to the transmission axis of the polarizing plate 18a, and the orientation axis of the biaxial film 56 makes an angle of 65 degrees with respect to the transmission axis of the polarizing plate 18b. It is arranged to make.

  In the inspection of the optical film 1 using the defect inspection element 65, the uniaxial film 52 and the biaxial film 53 are sequentially disposed between the polarizing plate 18a and the NH film 2 from the polarizing plate 18a side. Here, the uniaxial film 52 and the biaxial film 53 have birefringence in a plane orthogonal to the thickness direction. Then, the optical film 1 is inspected using the defect inspection element 65 in the same manner as in the second embodiment.

  As the retardation reducing elements such as the uniaxial film and the biaxial film as described above, the same elements as those in the third embodiment are used.

(Ninth embodiment)
Next, 9th Embodiment of the inspection method of the optical film which concerns on this invention is described using FIG. In FIG. 15, the same or equivalent components as those in the first and second embodiments are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 15 is a diagram showing an arrangement relationship at the time of defect inspection between the orientation axes of the NH film, the transmission axis of the polarizing plate, and the orientation axes of the uniaxial film and the biaxial film. In FIG. 15, the polarizing plate or film is sequentially arranged at a position farther from the light source as it goes from the left side to the right side.

  The inspection method of the present embodiment is different from the first embodiment in that the defect inspection element 66 is configured as follows.

  That is, as shown in FIG. 15, the defect inspection element 66 according to the present embodiment has the biaxial film 56 and the uniaxial film 35 between the NH film 31 and the polarizing plate 18b. Different from the testing element 29. The uniaxial film 35 and the biaxial film 56, together with the uniaxial film 52 and the biaxial film 53, can reduce the phase difference obtained when light passes through the NH film 2 and the NH film 31. It functions as an element. The uniaxial film 35 and the biaxial film 56 have birefringence in a plane orthogonal to the thickness direction.

  In addition, the defect inspection element 66 of the present embodiment is arranged when the defect inspection element 66 is disposed so as to face the optical film optical film 1 and the polarizing plate 18a and the polarizing plate 18b form an angle of 75 degrees. As shown in FIG. 15, the NH film 2 is different from the defect inspection element 29 in that the orientation axis of the NH film 2 is antiparallel to the orientation axis of the NH film 31.

  Here, the two uniaxial films 52 and 35 and the two biaxial films 53 and 56 are light-emitted on the NH film 2 and the NH film 31 from the viewpoint of improving the visibility of defects caused by thickness unevenness. It is preferable that the phase difference obtained when transmitting can be made zero. In order to make the phase difference zero, as shown in FIG. 15, the orientation of the uniaxial film 35 is such that the orientation axis of the uniaxial film 52 forms an angle of 25 degrees with respect to the transmission axis of the polarizing plate 18a. The axis is arranged so as to form an angle of 5 degrees with respect to the transmission axis of the polarizing plate 18b. The orientation axis of the biaxial film 53 makes an angle of 25 degrees with respect to the transmission axis of the polarizing plate 18a, and the orientation axis of the biaxial film 56 makes an angle of 5 degrees with respect to the transmission axis of the polarizing plate 18b. It is arranged to make.

  In the inspection of the optical film 1 using the defect inspection element 66, the uniaxial film 52 and the biaxial film 53 are sequentially disposed between the polarizing plate 18a and the NH film 2 from the polarizing plate 18a side. Here, the uniaxial film 52 and the biaxial film 53 have birefringence in a plane orthogonal to the thickness direction. Then, the optical film 1 is inspected using the defect inspection element 66 in the same manner as in the second embodiment.

  As the retardation reducing elements such as the uniaxial film and the biaxial film as described above, the same elements as those in the third embodiment are used.

(10th Embodiment)
Next, 10th Embodiment of the inspection method of the optical film which concerns on this invention is described using FIG. In FIG. 16, the same or equivalent components as those in the first and second embodiments are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 16 is a diagram showing an arrangement relationship at the time of defect inspection between the orientation axes of the NH film, the transmission axis of the polarizing plate, and the orientation axes of the uniaxial film and the biaxial film. In FIG. 16, the polarizing plate or film is sequentially arranged at a position farther from the light source as it goes from the left side to the right side.

  The inspection method of the present embodiment is different from the first embodiment in that the defect inspection element 67 is configured as follows.

  That is, as shown in FIG. 16, the defect inspection element 67 of the present embodiment has the biaxial film 56 and the uniaxial film 35 between the NH film 31 and the polarizing plate 18b. Different from the testing element 29. The uniaxial film 35 and the biaxial film 56, together with the uniaxial film 52 and the biaxial film 53, can reduce the phase difference obtained when light passes through the NH film 2 and the NH film 31. It functions as an element. The uniaxial film 35 and the biaxial film 56 have birefringence in a plane orthogonal to the thickness direction.

  Further, the defect inspection element 67 of the present embodiment is arranged when the defect inspection element 67 is disposed so as to face the optical film 1 and the polarizing plate 18a and the polarizing plate 18b are arranged at an angle of 70 degrees. FIG. 16 is different from the defect inspection element 29 of the first embodiment in that the orientation axis of the NH film 2 is antiparallel to the orientation axis of the NH film 31.

  Here, the two uniaxial films 52 and 35 and the two biaxial films 53 and 56 are light-emitted on the NH film 2 and the NH film 31 from the viewpoint of improving the visibility of defects caused by thickness unevenness. It is preferable that the phase difference obtained when transmitting can be made zero. In order to make the phase difference zero, as shown in FIG. 16, the orientation of the uniaxial film 35 is such that the orientation axis of the uniaxial film 52 forms an angle of 85 degrees with respect to the transmission axis of the polarizing plate 18a. The axis is arranged so as to form an angle of 95 degrees with respect to the transmission axis of the polarizing plate 18b. The orientation axis of the biaxial film 53 makes an angle of 85 degrees with respect to the transmission axis of the polarizing plate 18a, and the orientation axis of the biaxial film 56 makes an angle of 95 degrees with respect to the transmission axis of the polarizing plate 18b. It is arranged to make.

  In the inspection of the optical film 1 using the defect inspection element 67, the uniaxial film 52 and the biaxial film 53 are sequentially disposed between the polarizing plate 18a and the NH film 2 from the polarizing plate 18a side. Here, the uniaxial film 52 and the biaxial film 53 have birefringence in a plane orthogonal to the thickness direction. Then, the optical film 1 is inspected using the defect inspection element 67 in the same manner as in the second embodiment.

  As the retardation reducing elements such as the uniaxial film and the biaxial film as described above, the same elements as those in the third embodiment are used.

(Eleventh embodiment)
Next, an eleventh embodiment of the optical film inspection method according to the present invention will be described with reference to FIG. In FIG. 17, the same or equivalent components as those in the first and second embodiments are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 17 is a diagram showing an arrangement relationship at the time of defect inspection between the orientation axes of the NH film, the transmission axis of the polarizing plate, and the orientation axes of the uniaxial film and the biaxial film. In FIG. 17, the polarizing plate or film is sequentially arranged at a position farther from the light source as it goes from the left side to the right side.

  The inspection method of this embodiment is different from that of the first embodiment in that the defect inspection element 68 is configured as follows.

  That is, as shown in FIG. 17, the defect inspection element 68 according to the present embodiment has the biaxial film 56 and the uniaxial film 35 between the NH film 31 and the polarizing plate 18b. Different from the testing element 29. The uniaxial film 35 and the biaxial film 56, together with the uniaxial film 52 and the biaxial film 53, can reduce the phase difference obtained when light passes through the NH film 2 and the NH film 31. It functions as an element. The uniaxial film 35 and the biaxial film 56 have birefringence in a plane orthogonal to the thickness direction.

  In addition, the defect inspection element 68 of the present embodiment is arranged when the defect inspection element 68 is disposed so as to face the optical film 1 and the polarizing plate 18a and the polarizing plate 18b are arranged at an angle of 65 degrees. 17, the NH film 2 is different from the defect inspection element 29 in the first embodiment in that the orientation axis of the NH film 2 is antiparallel to the orientation axis of the NH film 31.

  Here, the two uniaxial films 52 and 35 and the two biaxial films 53 and 56 are light-emitted on the NH film 2 and the NH film 31 from the viewpoint of improving the visibility of defects caused by thickness unevenness. It is preferable that the phase difference obtained when transmitting can be made zero. In order to make the phase difference zero, as shown in FIG. 17, the orientation of the uniaxial film 35 is such that the orientation axis of the uniaxial film 52 forms an angle of 5 degrees with respect to the transmission axis of the polarizing plate 18a. The axis is arranged to form an angle of 35 degrees with respect to the transmission axis of the polarizing plate 18b. The orientation axis of the biaxial film 53 makes an angle of 5 degrees with respect to the transmission axis of the polarizing plate 18a, and the orientation axis of the biaxial film 56 makes an angle of 35 degrees with respect to the transmission axis of the polarizing plate 18b. It is arranged to make.

  In the inspection of the optical film 1 using the defect inspection element 68, the uniaxial film 52 and the biaxial film 53 are sequentially disposed between the polarizing plate 18a and the NH film 2 from the polarizing plate 18a side. Here, the uniaxial film 52 and the biaxial film 53 have birefringence in a plane orthogonal to the thickness direction. Then, the optical film 1 is inspected using the defect inspection element 68 in the same manner as in the second embodiment.

  As the retardation reducing elements such as the uniaxial film and the biaxial film as described above, the same elements as those in the third embodiment are used.

(Twelfth embodiment)
Next, a twelfth embodiment of the optical film inspection method according to the present invention will be described with reference to FIG. In FIG. 18, the same or equivalent components as those in the first and second embodiments are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 18 is a diagram showing an arrangement relationship at the time of defect inspection between the orientation axes of the NH film, the transmission axis of the polarizing plate, and the orientation axes of the uniaxial film and the biaxial film. In FIG. 18, the polarizing plate or the film is sequentially arranged at a position farther from the light source as it goes from the left side to the right side.

  The inspection method of the present embodiment is different from the first embodiment in that the defect inspection element 69 is configured as follows.

  That is, as shown in FIG. 18, the defect inspection element 69 of the present embodiment includes one uniaxial film 34 and two biaxial films 55 and 56 between the NH film 3 and the polarizing plate 18b. This is different from the defect inspection element 29 of the first embodiment. The uniaxial film 34 and the biaxial films 55 and 56 function as retardation reducing elements capable of reducing the retardation obtained when light passes through the NH film 2 and the NH film 31. The uniaxial film 34 and the biaxial films 55 and 56 have birefringence in a plane orthogonal to the thickness direction.

  In addition, the defect inspection element 69 of the present embodiment is shown when the defect inspection element 69 is disposed opposite to the optical film optical film 1 so that the polarizing plate 18a and the polarizing plate 18b are arranged in a crossed Nicol arrangement. As shown in FIG. 18, it differs from the defect inspection element 29 of the first embodiment in that the orientation axis of the NH film 2 is antiparallel to the orientation axis of the NH film 31.

  Here, from the viewpoint of improving the visibility of defects caused by thickness unevenness, the single uniaxial film 34 and the two biaxial films 55 and 56 transmit light through the NH film 2 and the NH film 31. It is preferable that the phase difference sometimes obtained can be made zero. In order to make the phase difference zero, as shown in FIG. 18, the orientation of the biaxial film 55 is such that the orientation axis of the uniaxial film 34 forms an angle of 40 degrees with respect to the transmission axis of the polarizing plate 18b. The axis is arranged at an angle of 40 degrees with respect to the transmission axis of the polarizing plate 18b, and the orientation axis of the biaxial film 56 is arranged at an angle of 10 degrees with respect to the transmission axis of the polarizing plate 18b. .

  As the retardation reducing elements such as the uniaxial film and the biaxial film as described above, the same elements as those in the third embodiment are used.

(13th Embodiment)
Next, a thirteenth embodiment of the optical film inspection method according to the present invention will be described with reference to FIG. In FIG. 19, the same or equivalent components as those in the first and second embodiments are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 19 is a diagram showing an arrangement relationship at the time of defect inspection between the orientation axes of the NH film, the transmission axis of the polarizing plate, and the orientation axes of the uniaxial film and the biaxial film. In FIG. 19, the polarizing plate or the film is sequentially arranged at a position farther from the light source as it goes from the left side to the right side.

  The inspection method of the present embodiment is different from the first embodiment in that the defect inspection element 70 is configured as follows.

  That is, as shown in FIG. 19, the defect inspection element 70 according to the present embodiment has the two biaxial films 54 and 55 between the NH film 31 and the polarizing plate 18b. Different from the element 29 for use. The biaxial films 54 and 55 function as retardation reducing elements capable of reducing the retardation obtained when light passes through the NH film 2 and the NH film 31. The biaxial films 54 and 55 have birefringence in a plane orthogonal to the thickness direction.

  In addition, the defect inspection element 70 of the present embodiment is arranged when the defect inspection element 70 is disposed so as to face the optical film 1 and the polarizing plate 18a and the polarizing plate 18b are arranged in a crossed Nicol arrangement. As shown in FIG. 19, the NH film 2 is different from the defect inspection element 29 of the first embodiment in that the orientation axis of the NH film 2 is antiparallel to the orientation axis of the NH film 31.

  Here, from the viewpoint of improving the visibility of defects caused by thickness unevenness of the two biaxial films 54 and 55, the phase difference obtained when light passes through the NH film 2 and the NH film 31 is zero. It is preferable that it can be made. In order to make the phase difference zero, as shown in FIG. 19, the orientation of the biaxial film 55 is such that the orientation axis of the biaxial film 54 forms an angle of 125 degrees with respect to the transmission axis of the polarizing plate 18b. The axis is arranged so as to form an angle of 25 degrees with respect to the transmission axis of the polarizing plate 18b.

  As the retardation reducing elements such as the uniaxial film and the biaxial film as described above, the same elements as those in the third embodiment are used.

(14th Embodiment)
Next, a fourteenth embodiment of the optical film inspection method according to the present invention will be described with reference to FIG. In FIG. 20, the same or equivalent components as those in the first and second embodiments are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 20 is a diagram showing an arrangement relationship at the time of defect inspection between the orientation axes of the NH film, the transmission axis of the polarizing plate, and the orientation axes of the uniaxial film and the biaxial film. In FIG. 20, the polarizing plate or the film is sequentially arranged at a position farther from the light source as it goes from the left side to the right side.

  The inspection method of this embodiment is different from that of the first embodiment in that the defect inspection element 71 is configured as follows.

  That is, as shown in FIG. 20, the defect inspection element 71 of this embodiment includes one uniaxial film 34 and two biaxial films 55 and 56 between the NH film 31 and the polarizing plate 18b. This is different from the defect inspection element 29 of the first embodiment. The uniaxial film 34 and the biaxial films 55 and 56 function as retardation reducing elements capable of reducing the retardation obtained when light passes through the NH film 2 and the NH film 31. The uniaxial film 34 and the biaxial films 55 and 56 have birefringence in a plane orthogonal to the thickness direction.

  In addition, the defect inspection element 71 of the present embodiment is illustrated in the case where the defect inspection element 71 is disposed opposite to the optical film optical film 1 so that the polarizing plate 18a and the polarizing plate 18b are arranged in a crossed Nicol arrangement. As shown in FIG. 20, it differs from the defect inspection element 29 of the first embodiment in that the orientation axis of the NH film 2 is antiparallel to the orientation axis of the NH film 31.

  Here, from the viewpoint of improving the visibility of defects caused by thickness unevenness, the single uniaxial film 34 and the two biaxial films 55 and 56 transmit light through the NH film 2 and the NH film 31. It is preferable that the phase difference sometimes obtained can be made zero. In order to make the phase difference zero, as shown in FIG. 20, the orientation of the biaxial film 55 is such that the orientation axis of the uniaxial film 34 forms an angle of 40 degrees with respect to the transmission axis of the polarizing plate 18b. The axis is arranged at an angle of 30 degrees with respect to the transmission axis of the polarizing plate 18b, and the orientation axis of the biaxial film 56 is arranged at an angle of 15 degrees with respect to the transmission axis of the polarizing plate 18b. .

  As the retardation reducing elements such as the uniaxial film and the biaxial film as described above, the same elements as those in the third embodiment are used.

(Fifteenth embodiment)
Next, 15th Embodiment of the inspection method of the optical film which concerns on this invention is described using FIG. In FIG. 21, the same or equivalent components as those in the first and second embodiments are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 21 is a diagram showing an arrangement relationship at the time of defect inspection between the orientation axes of the NH film, the transmission axis of the polarizing plate, and the orientation axes of the uniaxial film and the biaxial film. In FIG. 21, the polarizing plate or film is sequentially arranged at a position farther from the light source as it goes from the left side to the right side.

  The inspection method of the present embodiment is different from the first embodiment in that the defect inspection element 72 is configured as follows.

  That is, as shown in FIG. 21, the defect inspection element 72 of the present embodiment has one uniaxial film 34 and two biaxial films 55 and 56 between the NH film 31 and the polarizing plate 18b. This is different from the defect inspection element 29 of the first embodiment. The uniaxial film 34 and the biaxial films 55 and 56 function as retardation reducing elements capable of reducing the retardation obtained when light passes through the NH film 2 and the NH film 31. The uniaxial film 34 and the biaxial films 55 and 56 have birefringence in a plane orthogonal to the thickness direction.

  In addition, the defect inspection element 72 of the present embodiment is arranged when the defect inspection element 72 is disposed opposite to the optical film optical film 1 so that the polarizing plate 18a and the polarizing plate 18b are arranged in a crossed Nicol arrangement. 21, the NH film 2 is different from the defect inspection element 29 in the first embodiment in that the orientation axis of the NH film 2 is antiparallel to the orientation axis of the NH film 31.

  Here, from the viewpoint of improving the visibility of defects caused by thickness unevenness, the single uniaxial film 34 and the two biaxial films 55 and 56 transmit light through the NH film 2 and the NH film 31. It is preferable that the phase difference sometimes obtained can be made zero. In order to make the phase difference zero, as shown in FIG. 21, the orientation of the biaxial film 55 is such that the orientation axis of the uniaxial film 34 forms an angle of 45 degrees with respect to the transmission axis of the polarizing plate 18b. The axis is arranged at an angle of 45 degrees with respect to the transmission axis of the polarizing plate 18b, and the orientation axis of the biaxial film 56 is arranged at an angle of 45 degrees with respect to the transmission axis of the polarizing plate 18b. .

  As the retardation reducing elements such as the uniaxial film and the biaxial film as described above, the same elements as those in the third embodiment are used.

(Sixteenth embodiment)
Next, a sixteenth embodiment of the optical film inspection method according to the present invention will be described with reference to FIG. In FIG. 22, the same or equivalent components as those in the first and second embodiments are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 22 is a diagram showing an arrangement relationship at the time of defect inspection between the orientation axes of the NH film, the transmission axis of the polarizing plate, and the orientation axes of the uniaxial film and the biaxial film. In FIG. 22, the polarizing plate or film is sequentially arranged at a position farther from the light source as it goes from the left side to the right side.

  The inspection method of this embodiment is different from that of the first embodiment in that the defect inspection element 73 is configured as follows.

  That is, as shown in FIG. 22, the defect inspection element 73 of the present embodiment has one uniaxial film 34 and two biaxial films 55 and 56 between the NH film 31 and the polarizing plate 18b. This is different from the defect inspection element 29 of the first embodiment. The uniaxial film 34 and the biaxial films 55 and 56 function as retardation reducing elements capable of reducing the retardation obtained when light passes through the NH film 2 and the NH film 31. The uniaxial film 34 and the biaxial films 55 and 56 have birefringence in a plane orthogonal to the thickness direction.

  Further, the defect inspection element 73 of the present embodiment is shown in the case where the defect inspection element 73 is disposed opposite to the optical film optical film 1 so that the polarizing plate 18a and the polarizing plate 18b are arranged in a crossed Nicol arrangement. 22, the NH film 2 is different from the defect inspection element 29 in that the orientation axis of the NH film 2 is antiparallel to the orientation axis of the NH film 31.

  Here, from the viewpoint of improving the visibility of defects caused by thickness unevenness, the single uniaxial film 34 and the two biaxial films 55 and 56 transmit light through the NH film 2 and the NH film 31. It is preferable that the phase difference sometimes obtained can be made zero. In order to make the phase difference zero, as shown in FIG. 22, the orientation of the biaxial film 55 is such that the orientation axis of the uniaxial film 34 forms an angle of 45 degrees with respect to the transmission axis of the polarizing plate 18b. The axis is disposed at an angle of 30 degrees with respect to the transmission axis of the polarizing plate 18b, and the orientation axis of the biaxial film 56 is disposed at an angle of 10 degrees with respect to the transmission axis of the polarizing plate 18b. .

  As the retardation reducing elements such as the uniaxial film and the biaxial film as described above, the same elements as those in the third embodiment are used.

(17th Embodiment)
Next, a seventeenth embodiment of the optical film inspection method according to the present invention will be described with reference to FIG. In FIG. 23, the same or equivalent components as those in the first and second embodiments are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 23 is a diagram showing an arrangement relationship during defect inspection between the orientation axes of the NH film, the transmission axis of the polarizing plate, and the orientation axes of the uniaxial film and the biaxial film. In FIG. 23, the polarizing plate or film is sequentially arranged at a position farther from the light source as it goes from the left side to the right side.

  The inspection method of the present embodiment is different from the first embodiment in that the defect inspection element 74 is configured as follows.

  That is, as shown in FIG. 23, the defect inspection element 74 of the present embodiment includes the two biaxial films 54 and 55 between the NH film 31 and the polarizing plate 18b. Different from the element 29 for use. The biaxial films 54 and 55 function as retardation reducing elements capable of reducing the retardation obtained when light passes through the NH film 2 and the NH film 31. The biaxial films 54 and 55 have birefringence in a plane orthogonal to the thickness direction.

  In addition, the defect inspection element 74 of the present embodiment is shown when the defect inspection element 74 is disposed opposite to the optical film optical film 1 so that the polarizing plate 18a and the polarizing plate 18b are arranged in a crossed Nicol arrangement. 23, the NH film 2 is different from the defect inspection element 29 of the first embodiment in that the orientation axis of the NH film 2 is antiparallel to the orientation axis of the NH film 31.

  Here, from the viewpoint of improving the visibility of defects caused by thickness unevenness of the two biaxial films 54 and 55, the phase difference obtained when light passes through the NH film 2 and the NH film 31 is zero. It is preferable that it can be made. In order to make the phase difference zero, as shown in FIG. 23, the orientation of the biaxial film 55 is such that the orientation axis of the biaxial film 54 forms an angle of 125 degrees with respect to the transmission axis of the polarizing plate 18b. The axis is arranged so as to form an angle of 25 degrees with respect to the transmission axis of the polarizing plate 18b.

  As the retardation reducing elements such as the uniaxial film and the biaxial film as described above, the same elements as those in the third embodiment are used.

(Eighteenth embodiment)
Next, an eighteenth embodiment of the optical film inspection method according to the present invention will be described with reference to FIG. In FIG. 24, the same or equivalent components as those in the first and second embodiments are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 24 is a diagram showing an arrangement relationship during defect inspection between the orientation axes of the NH film, the transmission axis of the polarizing plate, and the orientation axes of the uniaxial film and the biaxial film. In FIG. 24, the polarizing plate or film is sequentially arranged at a position farther from the light source as it goes from the left side to the right side.

  The inspection method of the present embodiment is different from the first embodiment in that the defect inspection element 75 is configured as follows.

  That is, as shown in FIG. 24, the defect inspection element 75 of the present embodiment includes one uniaxial film 34 and two biaxial films 55 and 56 between the NH film 31 and the polarizing plate 18b. This is different from the defect inspection element 29 of the first embodiment. The uniaxial film 34 and the biaxial films 55 and 56 function as retardation reducing elements capable of reducing the retardation obtained when light passes through the NH film 2 and the NH film 31. The uniaxial film 34 and the biaxial films 55 and 56 have birefringence in a plane orthogonal to the thickness direction.

  In addition, the defect inspection element 75 of the present embodiment is shown when the defect inspection element 75 is disposed opposite to the optical film optical film 1 so that the polarizing plate 18a and the polarizing plate 18b are arranged in a crossed Nicol arrangement. As shown in FIG. 24, it differs from the defect inspection element 29 of the first embodiment in that the orientation axis of the NH film 2 is antiparallel to the orientation axis of the NH film 31.

  Here, from the viewpoint of improving the visibility of defects caused by thickness unevenness, the single uniaxial film 34 and the two biaxial films 55 and 56 transmit light through the NH film 2 and the NH film 31. It is preferable that the phase difference sometimes obtained can be made zero. In order to make the phase difference zero, as shown in FIG. 24, the orientation of the biaxial film 55 is such that the orientation axis of the uniaxial film 34 forms an angle of 35 degrees with respect to the transmission axis of the polarizing plate 18b. The axis is arranged at an angle of 15 degrees with respect to the transmission axis of the polarizing plate 18b, and the orientation axis of the biaxial film 56 is arranged at an angle of 5 degrees with respect to the transmission axis of the polarizing plate 18b. .

  As the retardation reducing elements such as the uniaxial film and the biaxial film as described above, the same elements as those in the third embodiment are used.

(Nineteenth embodiment)
Next, a nineteenth embodiment of the optical film inspection method according to the present invention will be described with reference to FIG. In FIG. 25, the same or equivalent components as those in the first and second embodiments are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 25 is a diagram showing an arrangement relationship at the time of defect inspection between the orientation axes of the NH film, the transmission axis of the polarizing plate, and the orientation axes of the uniaxial film and the biaxial film. In FIG. 25, the polarizing plate or film is sequentially arranged at a position farther from the light source as it goes from the left side to the right side.

  The inspection method of the present embodiment is different from the first embodiment in that the defect inspection element 76 is configured as follows.

  That is, as shown in FIG. 25, the defect inspection element 76 of this embodiment includes one uniaxial film 34 and two biaxial films 55 and 56 between the NH film 31 and the polarizing plate 18b. This is different from the defect inspection element 29 of the first embodiment. The uniaxial film 34 and the biaxial films 55 and 56 function as retardation reducing elements capable of reducing the retardation obtained when light passes through the NH film 2 and the NH film 31. The uniaxial film 34 and the biaxial films 55 and 56 have birefringence in a plane orthogonal to the thickness direction.

  In addition, the defect inspection element 76 of the present embodiment is shown when the defect inspection element 76 is disposed opposite to the optical film optical film 1 so that the polarizing plate 18a and the polarizing plate 18b are arranged in a crossed Nicol arrangement. As shown in FIG. 25, it differs from the defect inspection element 29 of the first embodiment in that the orientation axis of the NH film 2 is antiparallel to the orientation axis of the NH film 31.

  Here, from the viewpoint of improving the visibility of defects caused by thickness unevenness, the single uniaxial film 34 and the two biaxial films 55 and 56 transmit light through the NH film 2 and the NH film 31. It is preferable that the phase difference sometimes obtained can be made zero. In order to make the phase difference zero, as shown in FIG. 25, the orientation of the biaxial film 55 is such that the orientation axis of the uniaxial film 34 forms an angle of 125 degrees with respect to the transmission axis of the polarizing plate 18b. The axis is arranged at an angle of 130 degrees with respect to the transmission axis of the polarizing plate 18b, and the orientation axis of the biaxial film 56 is arranged at an angle of 75 degrees with respect to the transmission axis of the polarizing plate 18b. .

  As the retardation reducing elements such as the uniaxial film and the biaxial film as described above, the same elements as those in the third embodiment are used.

  The present invention is not limited to the embodiment described above. For example, in the second embodiment, the defect inspection element 33 includes the uniaxial films 34 and 35 between the NH film 31 and the polarizing plate 18b. However, as shown in FIG. The uniaxial film 34 may be removed from the defect inspection element 33, and the removed uniaxial film 34 may be disposed between the polarizing plate 18a and the optical film 1. Even in this case, similarly to the second embodiment, it is possible to improve the visibility of the defective portion, and it is possible to accurately inspect the defect caused by the thickness unevenness. In addition, according to the inspection method of the optical film using the inspection optical system according to FIG. 26, as in the second embodiment, compared to the case where the orientation axis is asymmetric between the NH film 2 and the NH film 31, Display characteristics can be further improved. In the second embodiment, the uniaxial film 34 may be laminated on the optical film 34 side of the polarizing plate 18a. The uniaxial film 34 may be replaced with the uniaxial film 35.

  Moreover, in the said 2nd-19th embodiment, in order to make the phase difference obtained when light permeate | transmits NH film 2 and NH film 31, the orientation axis of a uniaxial film or a biaxial film is polarized light. The angle formed with respect to the transmission axis of the plate 18b and the angle formed by the orientation axis of the uniaxial film or biaxial film with respect to the transmission axis of the polarizing plate 18a are the values shown in the above embodiments, but the phase difference is For the purpose of reduction, these angles may be shifted within a range of ± 15 ° with respect to the values shown in the above embodiments.

It is a figure which shows an example of a structure of the optical film used for the inspection method of the optical film of this invention. It is a side view which shows an example of the inspection optical system of the optical film in one Embodiment of the inspection method of the optical film of this invention. It is a figure which shows an example of the relationship of the transmission axis of a 1st polarizing plate, the orientation axis of the 1st liquid crystal film contained in an optical film, the orientation axis of a 2nd liquid crystal film, and the transmission axis of a 2nd polarizing plate, (a) The transmission axis of the first polarizing plate, (b) shows the alignment axis of the first liquid crystal film, (c) shows the alignment axis of the second liquid crystal film, and (d) shows the transmission axis of the second polarizing plate. It is sectional drawing which shows the optical film with thickness nonuniformity in the 1st liquid crystal film. It is a side view which shows an example of the inspection optical system of the optical film in other embodiment of the inspection method of the optical film of this invention. An example of the relationship between the transmission axis of the first polarizing plate, the alignment axis of the first liquid crystal film included in the optical film, the alignment axis of the second liquid crystal film, the optical axis of the retardation reducing element, and the transmission axis of the second polarizing plate is shown. (A) is the transmission axis of the first polarizing plate, (b) is the alignment axis of the first liquid crystal film, (c) is the alignment axis of the second liquid crystal film, and (d) and (e) are phase difference reductions. The orientation axis of the element, (f), indicates the transmission axis of the second polarizing plate. It is a figure which shows notionally the internal structure of the 1st and 2nd liquid crystal film in case the orientation axis of a 1st liquid crystal film and the orientation axis of a 2nd liquid crystal film are antiparallel. It is a figure which shows notionally the internal structure of the 1st and 2nd liquid crystal film in case the orientation axis of a 1st liquid crystal film and the orientation axis of a 2nd liquid crystal film are parallel. It is a figure which shows the arrangement | positioning relationship at the time of the defect inspection of the orientation axis of NH film, the transmission axis of a polarizing plate, and the orientation axis of a phase difference reduction element. It is a figure which shows the arrangement | positioning relationship at the time of the defect inspection of the orientation axis of NH film, the transmission axis of a polarizing plate, and the orientation axis of a phase difference reduction element. It is a figure which shows the arrangement | positioning relationship at the time of the defect inspection of the orientation axis of NH film, the transmission axis of a polarizing plate, and the orientation axis of a phase difference reduction element. It is a figure which shows the arrangement | positioning relationship at the time of the defect inspection of the orientation axis of NH film, the transmission axis of a polarizing plate, and the orientation axis of a phase difference reduction element. It is a figure which shows the arrangement | positioning relationship at the time of the defect inspection of the orientation axis of NH film, the transmission axis of a polarizing plate, and the orientation axis of a phase difference reduction element. It is a figure which shows the arrangement | positioning relationship at the time of the defect inspection of the orientation axis of NH film, the transmission axis of a polarizing plate, and the orientation axis of a phase difference reduction element. It is a figure which shows the arrangement | positioning relationship at the time of the defect inspection of the orientation axis of NH film, the transmission axis of a polarizing plate, and the orientation axis of a phase difference reduction element. It is a figure which shows the arrangement | positioning relationship at the time of the defect inspection of the orientation axis of NH film, the transmission axis of a polarizing plate, and the orientation axis of a phase difference reduction element. It is a figure which shows the arrangement | positioning relationship at the time of the defect inspection of the orientation axis of NH film, the transmission axis of a polarizing plate, and the orientation axis of a phase difference reduction element. It is a figure which shows the arrangement | positioning relationship at the time of the defect inspection of the orientation axis of NH film, the transmission axis of a polarizing plate, and the orientation axis of a phase difference reduction element. It is a figure which shows the arrangement | positioning relationship at the time of the defect inspection of the orientation axis of NH film, the transmission axis of a polarizing plate, and the orientation axis of a phase difference reduction element. It is a figure which shows the arrangement | positioning relationship at the time of the defect inspection of the orientation axis of NH film, the transmission axis of a polarizing plate, and the orientation axis of a phase difference reduction element. It is a figure which shows the arrangement | positioning relationship at the time of the defect inspection of the orientation axis of NH film, the transmission axis of a polarizing plate, and the orientation axis of a phase difference reduction element. It is a figure which shows the arrangement | positioning relationship at the time of the defect inspection of the orientation axis of NH film, the transmission axis of a polarizing plate, and the orientation axis of a phase difference reduction element. It is a figure which shows the arrangement | positioning relationship at the time of the defect inspection of the orientation axis of NH film, the transmission axis of a polarizing plate, and the orientation axis of a phase difference reduction element. It is a figure which shows the arrangement | positioning relationship at the time of the defect inspection of the orientation axis of NH film, the transmission axis of a polarizing plate, and the orientation axis of a phase difference reduction element. It is a figure which shows the arrangement | positioning relationship at the time of the defect inspection of the orientation axis of NH film, the transmission axis of a polarizing plate, and the orientation axis of a phase difference reduction element. It is a side view which shows an example of the test | inspection optical system of the optical film in other embodiment of the test | inspection method of the optical film of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Optical film, 2 ... NH film (1st liquid crystal film), 18a ... Polarizing plate (1st polarizing plate), 18b ... Polarizing plate (2nd polarizing plate), 20 ... Back light (light source), 29, 33, 36, 60 to 76 ... element for defect inspection, 31 ... NH film (second liquid crystal film), 34, 35, 52, 53, 54 ... uniaxial film, 42, 43 ... orientation axis of NH film, 54, 55, 56: Biaxial film (phase difference reducing element).

Claims (4)

An inspection method for an optical film including a first liquid crystal film in which liquid crystal is hybrid nematically aligned,
Irradiating light from the light source through the first polarizing plate to the optical film,
A defect inspection element in which a second liquid crystal film in which liquid crystal is hybrid nematically aligned and a second polarizing plate is laminated on the side opposite to the light source with respect to the optical film, and the second liquid crystal film is disposed on the optical film side. And inspecting the optical film by arranging the second liquid crystal film so that the alignment axis of the second liquid crystal film is not parallel to the alignment axis of the first liquid crystal film.   2. The optical film inspection method according to claim 1, wherein the defect inspection element is arranged so that an alignment axis of the first liquid crystal film and an alignment axis of the second liquid crystal film are orthogonal to each other. An inspection method for an optical film including a first liquid crystal film in which liquid crystal is hybrid nematically aligned,
Irradiating light from the light source through the first polarizing plate to the optical film,
A second liquid crystal film in which liquid crystal is hybrid nematically oriented on the opposite side of the light source with respect to the optical film, and a retardation obtained when light passes through the first liquid crystal film and the second liquid crystal film. A defect inspection element formed by sequentially laminating a retardation reducing element and a second polarizing plate that can be aligned so that the second liquid crystal film faces the optical film and the second liquid crystal film is aligned. An inspection method for an optical film, wherein the optical film is inspected with an axis arranged parallel or antiparallel to the alignment axis of the first liquid crystal film. An inspection method for an optical film including a first liquid crystal film in which liquid crystal is hybrid nematically aligned,
The optical film is irradiated with light from a light source through the first polarizing plate and the first retardation reducing element,
Light is transmitted through the second liquid crystal film in which liquid crystal is hybrid nematically aligned with the optical film on the side opposite to the light source, the first retardation reducing element, the first liquid crystal film, and the second liquid crystal film. A defect inspection element formed by sequentially laminating a second phase difference reducing element capable of reducing the phase difference sometimes obtained together with the first phase difference reducing element and a second polarizing plate is provided as the second liquid crystal. The optical film is inspected with the film oriented toward the optical film and the second liquid crystal film oriented in parallel or antiparallel to the orientation axis of the first liquid crystal film. Inspection method for optical film.

Images