WO2009022549A1 - Method for inspecting optical film - Google Patents

Method for inspecting optical film Download PDF

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Publication number
WO2009022549A1
WO2009022549A1 PCT/JP2008/063821 JP2008063821W WO2009022549A1 WO 2009022549 A1 WO2009022549 A1 WO 2009022549A1 JP 2008063821 W JP2008063821 W JP 2008063821W WO 2009022549 A1 WO2009022549 A1 WO 2009022549A1
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WO
WIPO (PCT)
Prior art keywords
liquid crystal
film
optical film
polarizing plate
defect
Prior art date
Application number
PCT/JP2008/063821
Other languages
French (fr)
Japanese (ja)
Inventor
Tetsuya Uesaka
Original Assignee
Nippon Oil Corporation
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Publication date
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Publication of WO2009022549A1 publication Critical patent/WO2009022549A1/en

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M11/00—Testing of optical apparatus; Testing structures by optical methods not otherwise provided for
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/95—Investigating the presence of flaws or contamination characterised by the material or shape of the object to be examined
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G02B5/3016—Polarising elements involving passive liquid crystal elements
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/95—Investigating the presence of flaws or contamination characterised by the material or shape of the object to be examined
    • G01N2021/9513—Liquid crystal panels

Definitions

  • the present invention relates to a method for detecting an optical film including a liquid crystal film in which liquid crystal is subjected to hybrid nematic alignment.
  • TFT Thinematic liquid crystal displays
  • liquid crystal film By using the liquid crystal film, a wide viewing angle liquid crystal display has been realized (see, for example, Patent Documents 1 and 2).
  • the optical film including such a hybrid alignment liquid crystal film if there are defects in the film plane, the display characteristics of the TFT liquid crystal display are adversely affected. For this reason, it is necessary to inspect optical films for defects and to eliminate optical films with many defects in advance.
  • Patent Document 3 as a method for inspecting a hybrid nematic alignment liquid crystal film, a method using a defect inspection element in which the alignment axes of a hybrid alignment liquid crystal film are arranged substantially orthogonally is proposed.
  • a defect inspection element in which the alignment axes of a hybrid alignment liquid crystal film are arranged substantially orthogonally is proposed.
  • it is difficult to detect for example, the appearance of the defect portion when viewed from the front or oblique direction changes from a bright spot to a black spot.
  • Patent Document 1 Japanese Patent Laid-Open No. 10-186 356
  • Patent Document 2 JP-A-2005-62673
  • Patent Document 3 JP 2006-3 1 74 A
  • the present invention has been made in view of the above circumstances, and an object of the present invention is to provide an optical film inspection method capable of accurately inspecting defects in an optical film including a hybrid nematic alignment liquid crystal film. ' As a result of intensive studies to solve the above problems, the present inventors have completed the present invention.
  • the first of the present invention is a method for detecting 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.
  • a defect detecting element comprising a second liquid crystal film having a liquid crystal in a hybrid nematic orientation and a second polarizing plate on a side opposite to the light source with respect to the optical film, wherein the second liquid crystal film side is the optical film side
  • An inspection method for an optical film wherein the optical film is inspected by disposing the defect inspection element to be inclined with respect to the optical film.
  • the defect inspection element is disposed such that an alignment axis of the first liquid crystal film and an alignment axis of the second liquid crystal film are substantially orthogonal to each other.
  • a method for detecting an optical film including a first liquid crystal film in which liquid crystal is subjected to hybrid nematic alignment, wherein the optical film is irradiated with light from a light source through a first polarizing plate, Defect inspection by sequentially laminating a second liquid crystal film with a liquid crystal in a hybrid nematic orientation, a first retardation film composed of a uniaxially stretched film, and a second polarizing plate on the opposite side of the light source with respect to the optical film And the second liquid crystal film side is adjacent to the optical film side, the slow axis of the first retardation film and the absorption axis of the second polarizing plate are substantially orthogonal, and An optical film inspection method comprising: inspecting the optical film by inclining the defect inspection element with respect to the optical film.
  • the defect inspection element is disposed so that an alignment axis of the first liquid crystal film and an alignment axis of the second liquid crystal film are substantially orthogonal to each other. 4. The method for inspecting an optical film according to the third item.
  • 5th of this invention is an inspection method of the optical film containing the 1st liquid crystal film which made the liquid crystal the hybrid nematic alignment, Comprising: Light is irradiated with respect to the said optical film from a light source through a 1st polarizing plate, The said optical On the opposite side of the film from the light source, a second liquid crystal film in which liquid crystal is hybrid nematically aligned, a third liquid crystal film in which liquid crystal is homeotropically aligned, and a first retardation film comprising a uniaxially stretched film.
  • a defect detecting element formed by sequentially laminating a film and a second polarizing plate is disposed so that the second liquid crystal film side is adjacent to the optical film side, and the slow axis of the first retardation film (2) Inspection of an optical film, characterized in that the absorption axis of the polarizing plate is disposed so as to be substantially orthogonal, and the defect inspection element is inclined with respect to the optical film, and the optical film is inspected.
  • the defect inspection element is arranged such that the alignment axis of the first liquid crystal film and the alignment axis of the second liquid crystal film are substantially orthogonal to each other.
  • a seventh aspect of the present invention is the inspection method according to any one of the first to sixth aspects of the present invention, wherein the liquid crystal is composed of rod-like liquid crystal molecules.
  • An eighth aspect of the present invention is the inspection method according to any one of the sixth to sixth aspects of the present invention, wherein the liquid crystal is composed of discotic liquid crystal molecules.
  • FIG. 1 is a diagram showing an example of an optical film used in the optical film inspection method of the present invention.
  • the optical film 1 includes, as the first liquid crystal film, a hybrid alignment liquid crystal layer 2 in which the liquid crystal is changed in the film thickness direction (arrow A direction) and the liquid crystal is hybrid nematically aligned.
  • the hybrid nematic alignment refers to an alignment in which the horizontal alignment and the vertical alignment of the nematic liquid crystal are combined.
  • the alignment of the nematic liquid crystal molecule 3 is one of the hybrid nematic alignment liquid crystal layer 2.
  • Surface 2a has horizontal orientation
  • surface 2b opposite to surface 2a has vertical orientation
  • surface 2b opposite to surface 2a
  • the horizontal orientation An orientation that gradually changes its orientation to a vertical orientation.
  • the projection component of the liquid crystal molecule director and director on the 2b plane is The direction in which the formed angle is an acute angle and parallel to the projection component is defined as the tilt direction of the hybrid nematic liquid crystal layer.
  • the tilt direction of the hybrid nematic alignment liquid crystal layer 2 is 1 1.
  • the structure shown in Fig. 1 may be such that the surface 2a side is vertically aligned and the surface 2b side is horizontally aligned, and the hybrid nematic alignment is opposite to that shown in Fig. 1.
  • the tilt direction is defined in the same direction.
  • the direction in which the liquid crystal molecules tilt is reversed, it is also necessary to consider the direction in which the defect detection element described later is tilted.
  • the optical film 1 only needs to include the hybrid nematic alignment liquid crystal layer 2. Therefore, in addition to the hybrid nematic alignment liquid crystal layer 2, another film may be included.
  • Other films typically include a support substrate 4 that supports a hybrid nematic alignment liquid crystal layer 2 as shown in FIG.
  • the supporting substrate 4 is not particularly limited as long as the supporting substrate 4 can support the hybrid nematic alignment liquid crystal layer 2 and is isotropic in the plane orthogonal to the thickness direction. Is preferably an optically isotropic substrate.
  • the thickness of the support substrate 4 is preferably 1 to 100 ⁇ m, and particularly preferably 5 to 50 ⁇ .
  • the Re value is preferably 20 nm or less, more preferably 1 O nm or less, particularly 5 nm or less is preferable.
  • the R th value is preferably in the range of 0 to 200 nm, more preferably in the range of 0 to 100 nm, particularly preferably in the range of 0 to 50 nm.
  • the defect of the optical film 1 specifically means an alignment defect of the liquid crystal layer in the hybrid nematic alignment liquid crystal layer 2 included in the optical film 1.
  • FIG. 2 is a diagram showing an example of an inspection optical system for a long optical film.
  • A is a figure which shows the case where the inspection optical system of a long optical film is seen from the side
  • (b)-(d) is a figure which shows the case where it is seen from the upper surface. That is, (b) is a diagram showing a case where the defect inspection element 9 is tilted counterclockwise with respect to a long optical film, and (c) is a diagram showing a case where the defect inspection element 9 is tilted clockwise.
  • D is a view when they are arranged in parallel without being inclined.
  • Figure 3 shows the alignment axis 1 1 of the hybrid nematic alignment liquid crystal layer 2 included in the optical film 1, the absorption axis 5 1 of the polarizing plate 5, the alignment axis 7 1 of the hybrid nematic alignment liquid crystal film 7, and the absorption axis of the polarizing plate 8.
  • 8 is a diagram illustrating an example of an arrangement relationship of 81.
  • a backlight 6 is disposed opposite to the optical film 1
  • a polarizing plate (first polarizing plate) 5 is disposed between the backlight 6 and the optical film 1.
  • the absorption axis 5 1 of the polarizing plate 5 has an angle of 45 ° with respect to the alignment axis 11 of the hybrid nematic liquid crystal layer 2 included in the optical film 1. adjust.
  • the pack light 6 is turned on, and the optical film 1 is inspected by using the defect inspection element 9 on the side opposite to the backlight 6 with respect to the optical film 1, and the hybrid nematic orientation included in the optical film 1 is obtained. Detect defects in liquid crystal layer 2.
  • the defect inspection element 9 will be described in detail.
  • the defect inspection element 9 is formed by laminating a polarizing plate 8 and a hybrid nematic alignment liquid crystal film (second liquid crystal film) 7.
  • the hybrid nematic alignment liquid crystal film 7 is a liquid crystal film in which the liquid crystal is hybrid nematic nematically aligned by changing the tilt of the liquid crystal in the film thickness direction (the arrow A direction in FIG. 1).
  • the defect inspection element 9 configured as described above is disposed opposite to the optical film 1.
  • the hybrid nematic alignment liquid crystal film 7 is directed to the optical film 1 side
  • the polarizing plate 8 is directed to the side opposite to the optical film 1
  • the polarizing plate 5 and the polarizing plate 8 are arranged in a crossed Nicol arrangement.
  • the alignment axis 71 of the hybrid nematic alignment liquid crystal film 7 can be made orthogonal to the alignment axis 11 of the hybrid nematic alignment liquid crystal layer 2 included in the optical film 1, as shown in FIG. And it is possible to make it easy to see the defects.
  • defect inspection element 9 is observed so as to be inclined obliquely with respect to the roll length direction of the optical film 1.
  • Table 1 summarizes the appearance and visibility of the defect when observed under the conditions of Fig. 2 (b) to (d).
  • the defect inspection element 9 is tilted counterclockwise with respect to a long optical film as shown in Fig. 2 (b)
  • the defective part becomes bright and the defect-free part becomes black.
  • the defect is easy to see, if it is tilted clockwise in Fig. 2 (c) or placed in parallel as shown in (d), the defect part will be inverted from the black spot, making it difficult to see I understand that.
  • the thickness of the hybrid alignment liquid crystal layer 2 is uneven, that is, when there is a defect-free portion 2 X having a thickness d 2 and a defect portion 2 Y having a thickness d 1 as shown in FIG.
  • the light emitted from the cryte 6 passes through the polarizing plate 5 and the optical film 1, there is a difference in the phase difference between the non-defect portion 2X and the defect portion 2Y.
  • what is embedded in the defective portion 2 Y and indicated by reference numeral 10 is dust or the like mixed during the manufacture of the hybrid nematic alignment liquid crystal layer 2.
  • the alignment axis 11 of the hybrid nematic alignment liquid crystal layer 2 and the alignment axis 71 of the hybrid nematic alignment liquid crystal film 7 are arranged substantially orthogonally as described above. Therefore, when the thicknesses of the hybrid nematic alignment liquid crystal layer 2 and the hybrid nematic alignment liquid crystal film 7 are equal, the birefringence of the hybrid nematic alignment liquid crystal layer 2 and the birefringence of the hybrid nematic alignment liquid crystal film 7 cancel each other. Therefore, the phase difference is canceled out, that is, zero.
  • the defect-free part 2 ⁇ becomes darkest when the defect inspection elements are arranged in parallel, and remains black when tilted as shown in Fig. 2 (b), but when tilted as shown in Fig. 2 (c) ⁇
  • the term “substantially orthogonal” usually means 90 ° ⁇ 15 °, preferably 90 °, 10 °, more preferably 90 ° ⁇ 5 °.
  • the defect part 2 Y has a larger phase difference than the defect-free part 2 X, so when tilted as shown in Fig. 2 (c), the phase difference of the hybrid nematic alignment liquid crystal film 7 in the defect inspection element On the other hand, it is blackened because it cancels out, but when tilted as shown in Fig. 2 (b), the phase difference of the hybrid nematic alignment liquid crystal film 7 becomes small. Therefore, the phase difference from the defective part 2 Y is much larger than the phase difference from the defect-free part 2 Y, and the defect-free part 2 X remains black, whereas the defect part 2 It will appear as a bright spot. Therefore, it becomes possible to improve the visibility of the defective portion 2, and it is possible to accurately inspect defects caused by thickness unevenness.
  • FIGS. 5 to 6 the same or equivalent components as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted.
  • the inspection method of this embodiment is different from that of the first embodiment in that the defect inspection element 13 is configured as follows.
  • the defect inspection element 13 will be described in detail.
  • FIG. 5 (a) is a diagram showing the inspection optical system of a long optical film as seen from the side
  • Fig. 5 (b) is a diagram showing it as seen from the top.
  • FIG. 5 is a diagram showing a case where the defect inspection element 13 is tilted counterclockwise with respect to the optical film of the scale.
  • Figure 6 shows a hybrid nematic alignment of the alignment axis 1 1 of the hybrid nematic alignment liquid crystal layer 2 included in the optical film 1, the absorption axis 5 1 of the polarizing plate 5, and the defect detection element 1 3
  • FIG. 5 is a diagram showing the inspection optical system of a long optical film as seen from the side
  • Fig. 5 (b) is a diagram showing it as seen from the top.
  • FIG. 5 is a diagram showing a case where the defect inspection element 13 is tilted counterclockwise with respect to the optical film of the scale.
  • Figure 6 shows a hybrid nematic alignment of the alignment axis 1 1 of the hybrid nematic
  • the first retardation film 12 can be appropriately selected from a film obtained by uniaxially stretching a plastic film. JSR), ZEONOR (manufactured by ZEON CORPORATION), etc. are used. A uniaxially stretched film is obtained by stretching the above film in one direction within a plane orthogonal to the thickness direction. As the retardation of the uniaxially stretched film, 2700 nm was used.
  • the defect inspection element 13 is formed by laminating a polarizing plate 8, a uniaxially stretched film 12, and a hybrid alignment liquid crystal film (second liquid crystal film) 7.
  • the hybrid nematic alignment liquid crystal film 7 is the same as the optical film 1, and as shown in FIG.
  • the second liquid crystal film) is laminated on the polarizing plate 8 so that the orientation axis 7 1 force of 7 is 45 ° with respect to the absorption axis 8 1 of the polarizing plate 8.
  • the slow axis 1 2 1 of the uniaxially stretched film 12 and the absorption axis 8 1 of the polarizing plate 8 are laminated so as to be substantially orthogonal.
  • defect inspection element 13 is observed so as to be inclined obliquely with respect to the roll length direction of the optical film 1 as shown in FIG. 5 (b).
  • Table 2 shows a comparison of the appearance of the defect and the visibility when observed under the conditions of Fig. 2 (b) and Fig. 5 (b). Compared to the case of Fig. 2 (b) of the first embodiment, the bright spot of the defective part looks the same, but the black of the defect-free part is darker, and the defect is more visible. It was confirmed that there was an improvement. Table 2
  • polarizing plates are known to leak light because they are not perpendicular when tilted at an angle, but here, the viewing angle characteristics of the polarizing plate itself are improved by adding a uniaxially stretched film. This is because visibility was improved.
  • the inspection method of this embodiment differs from that of the first embodiment in that the defect inspection element 15 is configured as follows.
  • the defect inspection element 15 will be described in detail.
  • FIG. 7 (a) is a diagram showing the inspection optical system of a long optical film as seen from the side
  • Fig. 7 (b) is a diagram showing it as seen from the top.
  • FIG. 5 is a view showing a case where the defect inspection element 15 is tilted counterclockwise with respect to the optical film of FIG.
  • Fig. 8 shows the orientation axis of the hybrid nematic alignment liquid crystal layer 2 included in the optical film 1, the absorption axis 51 of the polarizing plate 5, and the alignment axis of the hybrid nematic alignment liquid crystal film 7 (second liquid crystal film) 71
  • FIG. 5 is a view showing a case where the defect inspection element 15 is tilted counterclockwise with respect to the optical film of FIG.
  • Fig. 8 shows the orientation axis of the hybrid nematic alignment liquid crystal layer 2 included in the optical film 1, the absorption axis 51 of the polarizing plate 5, and the alignment axis of the hybrid nematic alignment liquid crystal film 7 (second liquid crystal film
  • FIG. 3 is a diagram showing an example of the arrangement relationship of a slow axis 1 2 1 of a uniaxially stretched film 1 2, a homeotropic alignment liquid crystal film (third liquid crystal film) 14 and an absorption axis 8 1 of a polarizing plate 8.
  • the retardation value of the uniaxially stretched film 12 was l l O nm.
  • the homeotopic orientation liquid crystal film refers to a film in which the alignment of nematic liquid crystal molecules is vertically aligned, and can be produced, for example, by the method described in JP-A-2006-22770.
  • the phase difference of the homeotropic alignment liquid crystal film is as follows.
  • the defect detection element 15 is composed of a polarizing plate 8, a uniaxially stretched film 12, a home-orientated pick-aligned liquid crystal film (third liquid crystal film) 14, and a hybrid nematic aligned liquid crystal film (second Liquid crystal film) 7 is laminated.
  • the hybrid nematic alignment liquid crystal film 7 is the same as the optical nematic alignment liquid crystal film 7 as shown in FIG. Are aligned on the polarizing plate 8 so that the orientation axis 7 1 is 45 ° with respect to the absorption axis 8 1 of the polarizing plate 8.
  • the slow axis 121 of the uniaxially stretched film 12 and the absorption axis 81 of the polarizing plate 8 are laminated so as to be substantially orthogonal.
  • the defect inspection element 15 is observed so as to be inclined obliquely with respect to the roll length direction of the optical film 1 as shown in FIG. 7 (b).
  • Table 3 shows a comparison of the appearance and visibility of the defect when observed under the conditions of Fig. 2 (b) and Fig. 7 (b). Compared to the case of Fig. 2 (b) of the first embodiment, the bright spot of the defective part looks the same, but the black of the defect-free part is darker, and the defect is more visible. It was confirmed that there was an improvement. Table 3
  • polarizing plates are known to leak light because they are not orthogonal when tilted obliquely.
  • the polarizing plate itself can be obtained by adding a uniaxial film and a home-to-mouth pick alignment liquid crystal film. This is because the visibility was improved by improving the viewing angle characteristics.
  • the slow axis of the uniaxially stretched film is used to make the phase difference obtained when light passes through the hybrid nematic liquid crystal layer 2 and the hybrid nematic liquid crystal film 7 zero.
  • the angle formed by the absorption axis of the polarizing plate 8 and the angle formed by the slow axis of the uniaxially stretched film with respect to the transmission axis of the polarizing plate 8 are the values shown in the above embodiments. For the purpose of reducing the above, these angles may be shifted within a range of ⁇ 15 ° with respect to the values shown in the above embodiments.
  • the retardation value of the uniaxially stretched film is in the range of 50 to 500 nm, more preferably in the range of 70 to 400 nm, and more preferably in the range of 90 to 300 nm. If it is out of this range, the visibility of defect inspection may be significantly deteriorated.
  • the R th value of homeomorphic alignment liquid crystal Finolem is in the range of 150 nm to 1300 nm, more preferably 1 25 0 to 1 100 nm, more preferably 1 2 2 The range of 0 1 5 0 nm, and the Re value of the homeotopically picked liquid crystal film is
  • 0 to 20 nm more preferably 0 to 10 nm, particularly preferably about 0 nm.
  • the present invention is not limited to the embodiment described above.
  • the first and second polarizing plates are rotated approximately 90 degrees while maintaining substantially orthogonal to the first embodiment, it becomes possible to improve the visibility of the defective portion in the same manner, and the thickness unevenness It is possible to accurately detect defects caused by the above.
  • the direction of tilting of the defect detection element is such that when the defective portion has a larger film thickness (a larger phase difference) than the non-defect portion, the position of the high-pressure nematic liquid crystal film of the defect detection element is increased. It is better to incline in the direction of decreasing the phase difference. If the film thickness of the defective part is smaller than the defect-free part (the phase difference is small), the phase difference of the hybrid nematic liquid crystal film of the defect inspection element is large. It is better to tilt in the direction.
  • the defect may be found by capturing the transmitted light transmitted from the defect inspection element by the method according to the present invention with an optical sensor, forming a corresponding image, and analyzing the image. According to this method, electronic processing is possible, and it is possible to automatically mark a defective part.
  • the liquid crystal molecules used in the hybrid nematic liquid crystal film are not limited to rod-like liquid crystal molecules, but may be disk-like liquid crystal molecules.
  • a visibility effect can be obtained by similarly tilting using a defect inspection element including the same discotic hybrid nematic liquid crystal film.
  • the tilt angle for inspecting the defect inspection element by tilting it with respect to the optical film is preferably 5 to 70 °, more preferably 10 to 50 °. .
  • FIG. 1 is a diagram showing an example of the configuration of an optical film used in the optical film inspection method of the present invention.
  • FIG. 2 is a diagram showing an example of the optical film inspection optical system in the first embodiment of the optical film inspection method of the present invention, where (a) is a side view, and (b) to (d) are upper sides. It is a figure which shows the case where it sees.
  • FIG. 3 is a diagram showing an example of the relationship between the absorption axes of the defect inspection element, the optical film 1, and the first polarizing plate of the first embodiment.
  • FIG. 4 is a cross-sectional view showing an optical film having uneven thickness on the first liquid crystal film.
  • FIG. 5 is a diagram showing an example of an optical film inspection optical system in the second embodiment of the optical film inspection method of the present invention, where (a) is a side view and (b) is a view from above.
  • FIG. 5 is a diagram showing an example of an optical film inspection optical system in the second embodiment of the optical film inspection method of the present invention, where (a) is a side view and (b) is a view from above.
  • FIG. 6 is a diagram showing an example of the relationship between the absorption axes of the defect inspection element, the optical film 1, and the first polarizing plate of the second embodiment.
  • FIG. 7 is a diagram showing an example of an optical film inspection optical system in the third embodiment of the optical film inspection method of the present invention, where (a) is a side view, and (b) is a view from above.
  • FIG. 7 is a diagram showing an example of an optical film inspection optical system in the third embodiment of the optical film inspection method of the present invention, where (a) is a side view, and (b) is a view from above.
  • FIG. 8 is a diagram showing an example of the relationship between the absorption axes of the defect inspection element, the optical film 1, and the first polarizing plate of the third embodiment. '
  • the optical film inspection method of the present invention can accurately detect defects in an optical film containing a hybrid nematic alignment liquid crystal film, the industrial value is high.

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Abstract

Provided is a method for correctly inspecting defects of an optical film which includes a first liquid crystal film wherein a liquid crystal is aligned in hybrid nematic orientation. A defect inspecting element irradiates an optical film with light through a first polarization plate from a light source, and is composed of a second liquid crystal film and a second polarization plate. In the second liquid crystal film, liquid crystal is aligned in hybrid nematic orientation to the opposite side to the light source with respect to the optical film. The defect inspecting element is arranged so that the second liquid crystal film side is adjacent to the optical film side. The optical film is inspected by tilting the defect inspecting element from the optical film.

Description

光学フィルムの検査方法  Optical film inspection method
[技術分野] [Technical field]
本発明は、 液晶をハイプリッドネマチック配向させた液晶フィルムを含む光学 フィルムの検查方法に関する。 明  The present invention relates to a method for detecting an optical film including a liquid crystal film in which liquid crystal is subjected to hybrid nematic alignment. Light
[背景技術]  [Background]
TFT (Thin Film Transistor) 液晶ディスプレイにおいては、 その表示特性 改善のために、 棒状液晶あるいは円盤状液晶をハイプリッドネマチック配向させ 書  In TFT (Thin Film Transistor) liquid crystal displays, in order to improve the display characteristics, a rod-shaped liquid crystal or a disk-shaped liquid crystal is aligned in a hybrid nematic orientation.
た液晶フィルムを用いることにより、 広視野角な液晶デイスプレイが実現されて いる （例えば、 特許文献 1および 2参照。 ） 。 このようなハイブリッド配向液晶 フィルムを含む光学フィルムは、 フィルム面内に欠陥が存在すると、 TFT液晶 ディスプレイの表示特性に悪影響を与える。 このため、 光学フィルムについて欠 陥の検査を行い、 欠陥が多い光学フィルムについては事前に排除しておくことが 必要である。 By using the liquid crystal film, a wide viewing angle liquid crystal display has been realized (see, for example, Patent Documents 1 and 2). In the optical film including such a hybrid alignment liquid crystal film, if there are defects in the film plane, the display characteristics of the TFT liquid crystal display are adversely affected. For this reason, it is necessary to inspect optical films for defects and to eliminate optical films with many defects in advance.
特許文献 3によれば、 ハイプリッドネマチック配向液晶フィルムの検査方法と して、 ハイプリッド配向液晶フィルムの配向軸を略直交に配置した欠陥検査用素 子を用いる方法が提案されている。 しかしながら、 欠陥の種類によっては、 正面 あるいは斜め方向から見た場合の欠陥部分の見え方が、 輝点から黒点に変化した りするなど検出しづらいという課題があった。  According to Patent Document 3, as a method for inspecting a hybrid nematic alignment liquid crystal film, a method using a defect inspection element in which the alignment axes of a hybrid alignment liquid crystal film are arranged substantially orthogonally is proposed. However, depending on the type of defect, there is a problem that it is difficult to detect, for example, the appearance of the defect portion when viewed from the front or oblique direction changes from a bright spot to a black spot.
( 1 ) 特許文献 1 ：特開平 1 0— 1 86 356号公報  (1) Patent Document 1: Japanese Patent Laid-Open No. 10-186 356
( 2 ) 特許文献 2 ：特開 2005— 626 73号公報  (2) Patent Document 2: JP-A-2005-62673
( 3 ) 特許文献 3 ：特開 2006— 3 1 74号公報  (3) Patent Document 3: JP 2006-3 1 74 A
[発明の開示] [Disclosure of the Invention]
本発明は、 上記事情に鑑みてなされたものであり、 ハイブリッドネマチック配 向液晶フィルムを含む光学フィルムの欠陥の検査を的確に行うことができる光学 フィルムの検査方法を提供することを目的とする。 ' 本発明者らは、 上記課題を解決するため鋭意研究を重ねた結果、 本発明を完成 するに至った。 The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an optical film inspection method capable of accurately inspecting defects in an optical film including a hybrid nematic alignment liquid crystal film. ' As a result of intensive studies to solve the above problems, the present inventors have completed the present invention.
即ち、 本発明の第 1は、 液晶をハイブリッドネマチック配向させた第 1液晶フ イルムを含む光学フィルムの検查方法であって、 前記光学フィルムに対し、 光源 から第 1偏光板を通して光を照射し、 前記光学フィルムに対して前記光源と反対 側に、 液晶をハイブリッドネマチック配向させた第 2液晶フイルムと第 2偏光板 とからなる欠陥検查用素子を、 前記第 2液晶フィルム側が前記光学フィルム側に 隣接するように配置し、 且つ前記欠陥検査用素子を、 前記光学フィルムに対し傾 斜させて、 前記光学フィルムを検査することを特徴とする光学フィルムの検查方 法、 である。  That is, the first of the present invention is a method for detecting 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. A defect detecting element comprising a second liquid crystal film having a liquid crystal in a hybrid nematic orientation and a second polarizing plate on a side opposite to the light source with respect to the optical film, wherein the second liquid crystal film side is the optical film side An inspection method for an optical film, wherein the optical film is inspected by disposing the defect inspection element to be inclined with respect to the optical film.
本発明の第 2は、 前記第 1液晶フィルムの配向軸と前記第 2液晶フィルムの配 向軸とが略直交するように前記欠陥検查用素子を配置することを特徴とする本発 明の第 1に記載の光学フィルムの検査方法、 である。  According to a second aspect of the present invention, the defect inspection element is disposed such that an alignment axis of the first liquid crystal film and an alignment axis of the second liquid crystal film are substantially orthogonal to each other. The optical film inspection method according to claim 1,
本発明の第 3は、 液晶をハイプリッドネマチック配向させた第 1液晶フィルム を含む光学フィルムの検查方法であって、 前記光学フィルムに対し、 光源から第 1偏光板を通して光を照射し、 前記光学フィルムに対して前記光源と反対側に、 液晶をハイプリッドネマチック配向させた第 2液晶フィルム、 1軸延伸フィルム からなる第 1位相差フィルム、 第 2偏光板とを順次積層してなる欠陥検査用素子 を、 前記第 2液晶フィルム側が前記光学フィルム側に隣接するように配置し、 第 1位相差フィルムの遅相軸と第 2偏光板の吸収軸が略直交となるように配置し、 且つ前記欠陥検査用素子を、 前記光学フィルムに対し傾斜させて、 前記光学フィ ルムを検查することを特徴とする光学フィルムの検查方法、 である。  According to a third aspect of the present invention, there is provided a method for detecting an optical film including a first liquid crystal film in which liquid crystal is subjected to hybrid nematic alignment, wherein the optical film is irradiated with light from a light source through a first polarizing plate, Defect inspection by sequentially laminating a second liquid crystal film with a liquid crystal in a hybrid nematic orientation, a first retardation film composed of a uniaxially stretched film, and a second polarizing plate on the opposite side of the light source with respect to the optical film And the second liquid crystal film side is adjacent to the optical film side, the slow axis of the first retardation film and the absorption axis of the second polarizing plate are substantially orthogonal, and An optical film inspection method comprising: inspecting the optical film by inclining the defect inspection element with respect to the optical film.
本発明の第 4は、 前記第 1液晶フィルムの配向軸と前記第 2液晶フィルムの配 向軸とが略直交するように前記欠陥検查用素子を配置することを特徴とする本発 明の第 3に記載の光学フィルムの検査方法、 である。  According to a fourth aspect of the present invention, the defect inspection element is disposed so that an alignment axis of the first liquid crystal film and an alignment axis of the second liquid crystal film are substantially orthogonal to each other. 4. The method for inspecting an optical film according to the third item.
本発明の第 5は、 液晶をハイプリッドネマチック配向させた第 1液晶フィルム を含む光学フィルムの検査方法であって、 前記光学フィルムに対し、 光源から第 1偏光板を通して光を照射し、 前記光学フィルムに対して前記光源と反対側に、 液晶をハイブリッドネマチック配向させた第 2液晶フィルム、 液晶をホメオト口 ピック配向させた第 3液晶フィルム、 1軸延伸フィルムからなる第 1位相差フィ ルム、 第 2偏光板とを順次積層してなる欠陥検查用素子を、 前記第 2液晶フィル ム側が前記光学フィルム側に隣接するように配置し、 第 1位相差フィルムの遅相 軸と第 2偏光板の吸収軸が略直交となるように配置し、 且つ前記欠陥検査用素子 を、 前記光学フィルムに対し傾斜させて、 前記光学フィルムを検查することを特 徴とする光学フィルムの検査方法、 である。 5th of this invention is an inspection method of the optical film containing the 1st liquid crystal film which made the liquid crystal the hybrid nematic alignment, Comprising: Light is irradiated with respect to the said optical film from a light source through a 1st polarizing plate, The said optical On the opposite side of the film from the light source, a second liquid crystal film in which liquid crystal is hybrid nematically aligned, a third liquid crystal film in which liquid crystal is homeotropically aligned, and a first retardation film comprising a uniaxially stretched film. A defect detecting element formed by sequentially laminating a film and a second polarizing plate is disposed so that the second liquid crystal film side is adjacent to the optical film side, and the slow axis of the first retardation film (2) Inspection of an optical film, characterized in that the absorption axis of the polarizing plate is disposed so as to be substantially orthogonal, and the defect inspection element is inclined with respect to the optical film, and the optical film is inspected. Method.
本発明の第 6は、 前記第 1液晶フィルムの配向軸と前記第 2液晶フィルムの配 向軸とが略直交するように前記欠陥検査用素子を配置することを特徴とする本発 明の第 5に記載の光学フィルムの検査方法、 である。  According to a sixth aspect of the present invention, the defect inspection element is arranged such that the alignment axis of the first liquid crystal film and the alignment axis of the second liquid crystal film are substantially orthogonal to each other. The optical film inspection method according to 5, wherein
本発明の第 7は、 液晶が棒状液晶分子からなることを特徴とする本発明の第 1 〜 6のいずれかに記載の検査方法、 である。  A seventh aspect of the present invention is the inspection method according to any one of the first to sixth aspects of the present invention, wherein the liquid crystal is composed of rod-like liquid crystal molecules.
本発明の第 8は、 液晶が円盤状液晶分子からなることを特徴とする本発明の第 ：!〜 6のいずれかに記載の検查方法、 である。  An eighth aspect of the present invention is the inspection method according to any one of the sixth to sixth aspects of the present invention, wherein the liquid crystal is composed of discotic liquid crystal molecules.
[発明の効果] [The invention's effect]
本発明の光学フィルムの検査方法によれば、 ハイブリッドネマチック配向液晶 フィルムを含む光学フィルムの欠陥の検査を的確に行うことができる。  According to the method for inspecting an optical film of the present invention, it is possible to accurately inspect defects in an optical film including a hybrid nematic alignment liquid crystal film.
[発明を実施するための最良の形態] [Best Mode for Carrying Out the Invention]
以下、 添付図面とともに、 本発明の光学フィルムの検査方法の実施形態につい て詳細に説明する。  Hereinafter, embodiments of the optical film inspection method of the present invention will be described in detail with reference to the accompanying drawings.
(第 1実施形態）  (First embodiment)
まず本発明に係る光学フィルムの検查方法の第 1実施形態について説明する。 はじめに、 本発明の光学フィルムの検査方法において検査対象となる光学フィ ルムについて図 1を参照して説明する。  First, a first embodiment of the 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.
図 1は、 本発明の光学フィルムの検査方法に用いられる光学フィルムの一例を 示す図である。図 1に示すように、光学フィルム 1は、第 1液晶フィルムとして、 液晶の傾きを膜厚方向 （矢印 A方向） に変化させて液晶をハイブリッドネマチッ ク配向させたハイブリッド配向液晶層 2を含む。 ここで、 ハイブリッドネマチッ ク配向とは、 ネマチック液晶の水平配向と垂直配向とが複合した配向を言い、 例 えばネマチック液晶分子 3の配向が、 ハイプリッドネマチック配向液晶層 2の一 面 2 a側では水平配向となっており、 面 2 aと反対の面 2 b側では垂直配向とな つており、 その間では、 面 2 aから面 2 bに向かう方向に沿って、 水平配向から 垂直配向に徐々にその配向を変化させるような配向を言う。 ハイプリッドネマチ ック配向液晶層 2の 2 a面 （水平配向） から液晶層を通して 2 b面 （垂直配向） を見た場合、 液晶分子ダイレクターとダイレクターの 2 b面への投影成分がなす 角度が鋭角となる方向で、 かつ投影成分と平行な方向をハイプリッドネマチック 液晶層のチルト方向と定義する。 図 1では、 ハイブリッドネマチック配向液晶層 2のチルト方向 1 1とする。 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 includes, as the first liquid crystal film, a hybrid alignment liquid crystal layer 2 in which the liquid crystal is changed in the film thickness direction (arrow A direction) and the liquid crystal is hybrid nematically aligned. . Here, the hybrid nematic alignment refers to 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 molecule 3 is one of the hybrid nematic alignment liquid crystal layer 2. Surface 2a has horizontal orientation, surface 2b opposite to surface 2a has vertical orientation, and in the meantime, from surface 2a to surface 2b, the horizontal orientation An orientation that gradually changes its orientation to a vertical orientation. When the 2b plane (vertical alignment) of the hybrid nematic alignment liquid crystal layer 2 is viewed from the 2a plane (horizontal alignment) through the liquid crystal layer, the projection component of the liquid crystal molecule director and director on the 2b plane is The direction in which the formed angle is an acute angle and parallel to the projection component is defined as the tilt direction of the hybrid nematic liquid crystal layer. In FIG. 1, the tilt direction of the hybrid nematic alignment liquid crystal layer 2 is 1 1.
なお図 1に示す面 2 a側が垂直配向、 面 2 b側が水平配向とし、 ハイブリッド ネマチック配向が図 1と逆となるような構造でもよいが、 この場合は、 チルト方 向の定義では同じ方向になるが、 液晶分子の傾く方向が逆になるため、 後述する 欠陥検查用素子の傾ける方向も考慮が必要となる。  The structure shown in Fig. 1 may be such that the surface 2a side is vertically aligned and the surface 2b side is horizontally aligned, and the hybrid nematic alignment is opposite to that shown in Fig. 1. However, in this case, the tilt direction is defined in the same direction. However, since the direction in which the liquid crystal molecules tilt is reversed, it is also necessary to consider the direction in which the defect detection element described later is tilted.
光学フィルム 1は、 ハイブリッドネマチック配向液晶層 2を含むものであれば よく、 従って、 ハイブリッドネマチック配向液晶層 2のほかに、 他のフィルムを 含んでいてもよい。 他のフィルムには通常、 図 1に示すように、 ハイブリッドネ マチック配向液晶層 2を支持する支持基板 4などがある。 かかる支持基板 4はハ イブリッドネマチック配向液晶層 2を支持し得るものであり、 且つ厚さ方向に直 交する面内において等方性を示すものであれば特に限定されないが、 かかる支持 基板 4としては光学的に等方な基板が好ましく、 例えばフジタック (富士フィル ム社製品） ゃコニカタック （コニ力ミノルタォプト社製品） などのトリァセチル セルロース ( T A C ) フィルム、 アートンフィルム ( J S R社製品) ゃゼォノア フイノレム、 ゼォネックスフイルム （日本ゼオン社製品） などのシクロォレフイン 系ポリマー、 T P Xフィルム （三井化学社製品）、 アタリプレンフィルム （三菱レ 一ヨン社製品） が挙げられるが、 楕円偏光板とした場合の平面性、 耐熱性や耐湿 性などからトリァセチルセルロース、 シクロォレフィン系ポリマーが好ましい。 支持基板 4の厚さは、 一般には、 1〜 1 0 0 ^ mが好ましく、 特に 5〜 5 0 μ ιη とするのが好ましい。 支持基板 4の面内方向の屈折率を n x、 n y、 厚さ方向の 屈折率を n z、 支持基板 4の厚さを dとした場合、 面内方向の位相差値を R e = ( n - n y ) X d、 厚さ方向の位相差値を R t h = { ( n x + n y ) / 2 - n z } X dと定義するとき、 R e値は 2 0 n m以下が好ましく、 より好ましくは 1 O n m以下、 特に 5 n m以下とするのが好ましい。 R t h値は 0〜 2 0 0 n mの 範囲が好ましく、 より好ましくは 0〜 1 0 0 n m、 特に好ましくは 0〜 5 0 n m の範囲である。 The optical film 1 only needs to include the hybrid nematic alignment liquid crystal layer 2. Therefore, in addition to the hybrid nematic alignment liquid crystal layer 2, another film may be included. Other films typically include a support substrate 4 that supports a hybrid nematic alignment liquid crystal layer 2 as shown in FIG. The supporting substrate 4 is not particularly limited as long as the supporting substrate 4 can support the hybrid nematic alignment liquid crystal layer 2 and is isotropic in the plane orthogonal to the thickness direction. Is preferably an optically isotropic substrate. For example, Fujitac (produced by Fuji Film), Konica Katak (produced by Konica Minoltaput), triacetyl cellulose (TAC) film, Arton Film (produced by JSR), ZEONOR FINOLEM, Examples include cycloolefin polymers such as ZEONEX film (product of ZEON Corporation), TPX film (product of Mitsui Chemicals), and attaliprene film (product of Mitsubishi Rayon Co., Ltd.). Triacetyl cellulose and cycloolefin polymers are preferred because of their heat resistance and moisture resistance. Good. In general, the thickness of the support substrate 4 is preferably 1 to 100 ^ m, and particularly preferably 5 to 50 μιη. When the refractive index in the in-plane direction of the support substrate 4 is nx, ny, the refractive index in the thickness direction is nz , and the thickness of the support substrate 4 is d, the retardation value in the in-plane direction is R e = (n- ny) X d, when the retardation value in the thickness direction is defined as R th = {(nx + ny) / 2-nz} X d, the Re value is preferably 20 nm or less, more preferably 1 O nm or less, particularly 5 nm or less is preferable. The R th value is preferably in the range of 0 to 200 nm, more preferably in the range of 0 to 100 nm, particularly preferably in the range of 0 to 50 nm.
このような光学フィルム 1の欠陥は以下のように検査される。 なお、 光学フィ ルム 1の欠陥とは、 具体的には、 光学フィルム 1に含まれるハイブリッドネマチ ック配向液晶層 2における液晶層の配向欠陥を意味する。  Such defects of the optical film 1 are inspected as follows. The defect of the optical film 1 specifically means an alignment defect of the liquid crystal layer in the hybrid nematic alignment liquid crystal layer 2 included in the optical film 1.
図 2は、 長尺の光学フィルムの検查光学系の一例を示す図である。 （a ) は長 尺の光学フィルムの検查光学系を側面から見た場合を示す図であり、 （b )〜（d ) はそれを上面から見た場合を示す図である。 すなわち、 （b ) は長尺の光学フィ ルムに対し、欠陥検査用素子 9を反時計回りに傾けた場合を示す図であり、 （c ) は、 時計回りに傾けた場合を示す図であり、 （d ) は傾けないまま平行に対向配 置した場合の図である。  FIG. 2 is a diagram showing an example of an inspection optical system for a long optical film. (A) is a figure which shows the case where the inspection optical system of a long optical film is seen from the side, (b)-(d) is a figure which shows the case where it is seen from the upper surface. That is, (b) is a diagram showing a case where the defect inspection element 9 is tilted counterclockwise with respect to a long optical film, and (c) is a diagram showing a case where the defect inspection element 9 is tilted clockwise. , (D) is a view when they are arranged in parallel without being inclined.
図 3は、 光学フィルム 1に含まれるハイブリッドネマチック配向液晶層 2の配 向軸 1 1、 偏光板 5の吸収軸 5 1、 ハイブリッドネマチック配向液晶フィルム 7 の配向軸 7 1及び偏光板 8の吸収軸 8 1の配置関係の一例を示す図である。  Figure 3 shows the alignment axis 1 1 of the hybrid nematic alignment liquid crystal layer 2 included in the optical film 1, the absorption axis 5 1 of the polarizing plate 5, the alignment axis 7 1 of the hybrid nematic alignment liquid crystal film 7, and the absorption axis of the polarizing plate 8. 8 is a diagram illustrating an example of an arrangement relationship of 81. FIG.
光学フィルム 1の欠陥検查にあたっては、 まず光学フィルム 1にバックライト 6を対向配置し、 バックライト 6と光学フィルム 1 との間に、 偏光板 （第 1偏光 板） 5を配置する。 図 3に示すように、 本実施形態では、 偏光板 5の吸収軸 5 1 は、 光学フィルム 1に含まれるハイブリッドネマチック液晶層 2の配向軸 1 1に 対して 4 5 ° の角度となるように調整する。  In order to detect defects in the optical film 1, first, a backlight 6 is disposed opposite to the optical film 1, and a polarizing plate (first polarizing plate) 5 is disposed between the backlight 6 and the optical film 1. As shown in FIG. 3, in the present embodiment, the absorption axis 5 1 of the polarizing plate 5 has an angle of 45 ° with respect to the alignment axis 11 of the hybrid nematic liquid crystal layer 2 included in the optical film 1. adjust.
そして、 パックライト 6を点灯し、 光学フィルム 1に対してバックライ ト 6と 反対側で、 欠陥検査用素子 9を用いて光学フィルム 1を司見き込み、 光学フィルム 1に含まれるハイプリッドネマチック配向液晶層 2における欠陥を検查する。 ここで、 欠陥検査用素子 9について詳細に説明する。  Then, the pack light 6 is turned on, and the optical film 1 is inspected by using the defect inspection element 9 on the side opposite to the backlight 6 with respect to the optical film 1, and the hybrid nematic orientation included in the optical film 1 is obtained. Detect defects in liquid crystal layer 2. Here, the defect inspection element 9 will be described in detail.
図 2に示すように、 欠陥検査用素子 9は、 偏光板 8と、 ハイブリッドネマチッ ク配向液晶フィルム （第 2液晶フィルム） 7とを積層したものである。 ハイプリ ッドネマチック配向液晶フィルム 7は、 光学フィルム 1と同様、 液晶の傾きを膜 厚方向 （図 1の矢印 A方向） に変化させて液晶をハイブリッドネマチックネマチ ック配向させた液晶フィルムである。  As shown in FIG. 2, the defect inspection element 9 is formed by laminating a polarizing plate 8 and a hybrid nematic alignment liquid crystal film (second liquid crystal film) 7. Similar to the optical film 1, the hybrid nematic alignment liquid crystal film 7 is a liquid crystal film in which the liquid crystal is hybrid nematic nematically aligned by changing the tilt of the liquid crystal in the film thickness direction (the arrow A direction in FIG. 1).
本実施形態の欠陥検査用素子 9では、 ハイプリッドネマチック配向液晶フィル ム 7として、 ハイプリッドネマチック配向液晶層 2と支持基板 4からなる光学フ イルム 1と材料及び厚さが同一のものを用いることができる。 また、 図 3に示す ように、 ハイブリッドネマチック配向液晶フィルム 7の配向軸 7 1 、 偏光板 8 の吸収軸 8 1に対して 4 5 ° となるように偏光板 8に積層されている。 In the defect inspection element 9 of this embodiment, the hybrid nematic alignment liquid crystal film As the film 7, the same material and thickness can be used as the optical film 1 composed of the hybrid nematic alignment liquid crystal layer 2 and the support substrate 4. Further, as shown in FIG. 3, it is laminated on the polarizing plate 8 so as to be 45 ° with respect to the alignment axis 7 1 of the hybrid nematic alignment liquid crystal film 7 and the absorption axis 8 1 of the polarizing plate 8.
欠陥検査の際は、 まず上記のように構成される欠陥検査用素子 9を光学フィル ム 1に対向配置する。 このとき、 ハイブリッドネマチック配向液晶フィルム 7を 光学フィルム 1側に向け、 偏光板 8を光学フィルム 1と反対側に向けると共に、 偏光板 5と偏光板 8がクロスニコル配置となるようにする。 これにより、 ハイブ リツドネマチック配向液晶フィルム 7の配向軸 7 1を、 図 3に示すように、 光学 フィルム 1に含まれるハイブリッドネマチック配向液晶層 2の配向軸 1 1と直交 させることが可能となり、 かつ欠点を見やすくさせることが出来る。  When performing defect inspection, first, the defect inspection element 9 configured as described above is disposed opposite to the optical film 1. At this time, the hybrid nematic alignment liquid crystal film 7 is directed to the optical film 1 side, the polarizing plate 8 is directed to the side opposite to the optical film 1, and the polarizing plate 5 and the polarizing plate 8 are arranged in a crossed Nicol arrangement. As a result, the alignment axis 71 of the hybrid nematic alignment liquid crystal film 7 can be made orthogonal to the alignment axis 11 of the hybrid nematic alignment liquid crystal layer 2 included in the optical film 1, as shown in FIG. And it is possible to make it easy to see the defects.
更に、 欠陥検査用素子 9を光学フィルム 1のロール長尺方向に対し、 斜めに傾 けるようにして観察する。  Further, the defect inspection element 9 is observed so as to be inclined obliquely with respect to the roll length direction of the optical film 1.
表 1は、 図 2 ( b ) 〜 （d ) の条件で、 観察した場合の欠陥部分の見え方と視 認性をまとめる。 表 1に示すとおり、 図 2 ( b ) のように長尺の光学フィルムに 対し、 欠陥検査用素子 9を反時計回りに傾けた場合は、 欠陥部分が輝点/無欠陥 部分が黒くなるため、 欠陥が見やすいのに対し、 図 2 ( c ) の時計回りに傾けた 場合や、 （d ) のように平行に対向配置した場合は、 欠陥部分が黒点と反転して しまうため、 見えにくくなることがわかる。  Table 1 summarizes the appearance and visibility of the defect when observed under the conditions of Fig. 2 (b) to (d). As shown in Table 1, when the defect inspection element 9 is tilted counterclockwise with respect to a long optical film as shown in Fig. 2 (b), the defective part becomes bright and the defect-free part becomes black. Although the defect is easy to see, if it is tilted clockwise in Fig. 2 (c) or placed in parallel as shown in (d), the defect part will be inverted from the black spot, making it difficult to see I understand that.
これは、 欠陥検查用素子に用いるハイプリッドネマチック配向液晶フィルムの 構造と光学フィルム 1内のハイプリッドネマチック配向液晶層 2の欠陥部分/無 欠陥部分の位相差に起因する。 表 1  This is due to the structure of the hybrid nematic alignment liquid crystal film used for the defect detection element and the phase difference between the defective portion / non-defect portion of the hybrid nematic alignment liquid crystal layer 2 in the optical film 1. table 1
Figure imgf000008_0001
以下に見え方の違いの原因を詳細に説明する。
Figure imgf000008_0001
The cause of the difference in appearance will be described in detail below.
図 2 (b) のように反時計回りに傾けた場合、 棒状液晶分子の先端方向から見 るため欠陥検查用素子を通過するときの位相差は小さくなるのに対し、図 2 (c) のように時計回りに傾けた場合は、 棒状液晶分子の棒方向 （腹側） から見ること になるため、 欠陥検査用素子を通過するときの位相差がより大きくなる。  When tilted counterclockwise as shown in Fig. 2 (b), the phase difference when passing through the defect detection element is small because it is viewed from the tip of the rod-like liquid crystal molecules, whereas Fig. 2 (c) When tilted clockwise as shown above, the phase difference when passing through the defect inspection element becomes larger because the liquid crystal molecules are viewed from the rod direction (abdominal side).
一方、 ハイブリッド配向液晶層 2に厚さムラがある場合、 即ち図 4に示すよう に、 厚さ d 2の無欠陥部分 2 Xと、 厚さ d 1の欠陥部分 2 Yとがある場合、 バッ クライト 6から発せられる光が偏光板 5及び光学フィルム 1を透過すると、 無欠 陥部分 2Xと欠陥部分 2 Yのそれぞれにおいて、 位相差に差がおきる。 なお、 図 4において、 欠陥部分 2 Yに埋設され符号 10で示されているのは、 ハイブリツ ドネマチック配向液晶層 2の製造時に混入したごみ等である。  On the other hand, when the thickness of the hybrid alignment liquid crystal layer 2 is uneven, that is, when there is a defect-free portion 2 X having a thickness d 2 and a defect portion 2 Y having a thickness d 1 as shown in FIG. When the light emitted from the cryte 6 passes through the polarizing plate 5 and the optical film 1, there is a difference in the phase difference between the non-defect portion 2X and the defect portion 2Y. In FIG. 4, what is embedded in the defective portion 2 Y and indicated by reference numeral 10 is dust or the like mixed during the manufacture of the hybrid nematic alignment liquid crystal layer 2.
より詳しく説明すると、 無欠陥部分 2 Xでは、 位相差 δ 2は S 2 = A n ' d 2 となるのに対し、 欠陥部分 2 Yでは、 位相差 δ 1は δ 1 =Δη · (11となる。 こ こで、 d l〉 d 2であるから、 δ 2< δ 1となる。  More specifically, in the defect-free part 2 X, the phase difference δ 2 is S 2 = A n 'd 2, whereas in the defect part 2 Y, the phase difference δ 1 is δ 1 = Δη Here, since dl> d2, δ2 <δ1.
このため、 無欠陥部分 2 Xと欠陥部分 2 Υとの間にコントラストを生じさせる ことが可能となる。 ここで、 ハイブリッドネマチック配向液晶層 2の配向軸 1 1 とハイプリッドネマチック配向液晶フィルム 7の配向軸 71とは、 上述したよう に略直交して配置させる。 このため、 ハイブリッドネマチック配向液晶層 2とハ イブリッドネマチック配向液晶フィルム 7の厚さが等しい場合には、 ハイブリッ ドネマチック配向液晶層 2の複屈折とハイプリッドネマチック配向液晶フィルム 7の複屈折が相殺し合うため、 位相差は打ち消される、 即ちゼロとなる。 無欠陥 部分 2Χは、 欠陥検査素子を平行に配置した場合が最も暗くなり、 図 2 (b) の ように傾けると黒のままであるが、 図 2 (c) のように傾けると、 欠陥検查素子 内のハイプリッドネマチック配向液晶フィルム 7の位相差が大きくなる分、 光漏 れが生じ白くなる。 なお、 本発明においていう略直交とは、 通常 90° ± 1 5° を意味し、好ましくは 90° 士 10° 、より好ましくは 90° ±5° を意味する。 For this reason, a contrast can be generated between the defect-free portion 2 X and the defect portion 2 2. Here, the alignment axis 11 of the hybrid nematic alignment liquid crystal layer 2 and the alignment axis 71 of the hybrid nematic alignment liquid crystal film 7 are arranged substantially orthogonally as described above. Therefore, when the thicknesses of the hybrid nematic alignment liquid crystal layer 2 and the hybrid nematic alignment liquid crystal film 7 are equal, the birefringence of the hybrid nematic alignment liquid crystal layer 2 and the birefringence of the hybrid nematic alignment liquid crystal film 7 cancel each other. Therefore, the phase difference is canceled out, that is, zero. The defect-free part 2Χ becomes darkest when the defect inspection elements are arranged in parallel, and remains black when tilted as shown in Fig. 2 (b), but when tilted as shown in Fig. 2 (c)分 As the phase difference of the hybrid nematic alignment liquid crystal film 7 in the device increases, light leakage occurs and whitens. In the present invention, the term “substantially orthogonal” usually means 90 ° ± 15 °, preferably 90 °, 10 °, more preferably 90 ° ± 5 °.
—方、 欠陥部分 2 Yは、 無欠陥部分 2 Xよりも位相差が大きいため、 図 2 (c) のように傾けた場合、 欠陥検査素子内のハイブリッドネマチック配向液晶フィル ム 7の位相差と打ち消されるため、 逆に黒くなるのに対し、 図 2 (b) のように 傾けた場合は、 ハイブリッドネマチック配向液晶フィルム 7の位相差が小さくな るため、 欠陥部分 2 Yとの位相差のずれが無欠陥部分 2 Yとの位相差のずれより も更に大きくなり、 無欠陥部分 2 Xが黒いままであるのに対し、 欠陥部分 2 Υは 輝点として現れることとなる。 よって、 欠陥部分 2 Υの視認性を向上させること が可能となり、 厚さムラに起因する欠陥の検査を的確に行うことができる。 -On the other hand, the defect part 2 Y has a larger phase difference than the defect-free part 2 X, so when tilted as shown in Fig. 2 (c), the phase difference of the hybrid nematic alignment liquid crystal film 7 in the defect inspection element On the other hand, it is blackened because it cancels out, but when tilted as shown in Fig. 2 (b), the phase difference of the hybrid nematic alignment liquid crystal film 7 becomes small. Therefore, the phase difference from the defective part 2 Y is much larger than the phase difference from the defect-free part 2 Y, and the defect-free part 2 X remains black, whereas the defect part 2 It will appear as a bright spot. Therefore, it becomes possible to improve the visibility of the defective portion 2, and it is possible to accurately inspect defects caused by thickness unevenness.
上記の結果より、 欠陥検查用捕償素子のハイプリッドネマチック配向液晶フィ ルム 7の棒状液晶分子の先端側から見るように傾けることにより、 より欠陥部分 の視認性を高めることが可能となる。  From the above results, it is possible to further improve the visibility of the defect portion by tilting the tip-side liquid crystal molecule 7 of the hybrid nematic alignment liquid crystal film 7 of the defect detection compensator as viewed from the tip side.
(第 2実施形態） (Second embodiment)
次に、 本発明に係る光学フィルムの検査方法の第 2実施形態について図 5〜図 6を用いて説明する。 図 5〜図 6において、 第 1実施形態と同一又は同等の構成 要素については同一符号を付し、 重複する説明を省略する。  Next, a second embodiment of the optical film inspection method according to the present invention will be described with reference to FIGS. 5 to 6, the same or equivalent components as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted.
本実施形態の検査方法は、 欠陥検査用素子 1 3が以下のように構成されている 点で第 1実施形態と異なる。 欠陥検査用素子 1 3について詳細に説明する。  The inspection method of this embodiment is different from that of the first embodiment in that the defect inspection element 13 is configured as follows. The defect inspection element 13 will be described in detail.
図 5 ( a ) は、 長尺の光学フィルムの検查光学系を側面から見た場合を示す図 であり、 図 5 ( b ) は、 それを上面から見た場合を示す図であり、 長尺の光学フ イルムに対し、 欠陥検查用素子 1 3を反時計回りに傾けた場合を示す図である。 図 6は、 光学フィルム 1に含まれるハイプリッドネマチック配向液晶層 2の配 向軸 1 1、 偏光板 5の吸収軸 5 1、 欠陥検查用素子 1 3のハイブリッドネマチッ ク配向させた第 2液晶フィルム 7の配向軸 7 1、 1軸延伸フィルムである第 1位 相差フィルム 1 2の遅相軸 1 2 1及ぴ偏光板 8の吸収軸 8 1の配置関係の一例を 示す図である。 第 1位相差フィルム 1 2としては、 プラスチックフィルムを 1軸 延伸して得られるフィルムから適宜選定することができるが、 例えばポリカーボ ネートフイノレム、 トリァセチノレセノレロース （T A C ) フイノレム、 ノノレボノレネン系 からなるアートン （ J S R社製） 、 ゼォノア （日本ゼオン社製） などが用いられ る。 1軸延伸フィルムは、 上記フィルムを、 厚さ方向に直交する面内の一方向に 延伸することにより得られる。 1軸延伸フィルムの位相差としては 2 7 0 n mを 用いた。  Fig. 5 (a) is a diagram showing the inspection optical system of a long optical film as seen from the side, and Fig. 5 (b) is a diagram showing it as seen from the top. FIG. 5 is a diagram showing a case where the defect inspection element 13 is tilted counterclockwise with respect to the optical film of the scale. Figure 6 shows a hybrid nematic alignment of the alignment axis 1 1 of the hybrid nematic alignment liquid crystal layer 2 included in the optical film 1, the absorption axis 5 1 of the polarizing plate 5, and the defect detection element 1 3 FIG. 3 is a diagram showing an example of the arrangement relationship between an orientation axis 71 of the liquid crystal film 7 and a slow axis 12 1 of the first retardation film 12 which is a uniaxially stretched film and an absorption axis 81 of the polarizing plate 8. The first retardation film 12 can be appropriately selected from a film obtained by uniaxially stretching a plastic film. JSR), ZEONOR (manufactured by ZEON CORPORATION), etc. are used. A uniaxially stretched film is obtained by stretching the above film in one direction within a plane orthogonal to the thickness direction. As the retardation of the uniaxially stretched film, 2700 nm was used.
図 5に示すように、欠陥検査用素子 1 3は、偏光板 8、 1軸延伸フィルム 1 2、 ハイプリッド配向液晶フィルム（第 2液晶フィルム） 7とを積層したものである。 本実施形態の欠陥検査用素子 1 3では、 第 1実施形態と同様、 ハイプリッドネ マチック配向液晶フィルム 7として、 光学フィルム 1と同一のものを用い、 図 6 に示すように、 ハイブリッドネマチック配向液晶フィルム （第 2液晶フィルム） 7の配向軸 7 1力、 偏光板 8の吸収軸 8 1に対して 4 5 ° となるように偏光板 8 に積層されている。 また、 1軸延伸フィルム 1 2の遅相軸 1 2 1と偏光板 8の吸 収軸 8 1は略直交となるように積層されている。 As shown in FIG. 5, the defect inspection element 13 is formed by laminating a polarizing plate 8, a uniaxially stretched film 12, and a hybrid alignment liquid crystal film (second liquid crystal film) 7. In the defect inspection element 13 of the present embodiment, as in the first embodiment, the hybrid nematic alignment liquid crystal film 7 is the same as the optical film 1, and as shown in FIG. The second liquid crystal film) is laminated on the polarizing plate 8 so that the orientation axis 7 1 force of 7 is 45 ° with respect to the absorption axis 8 1 of the polarizing plate 8. The slow axis 1 2 1 of the uniaxially stretched film 12 and the absorption axis 8 1 of the polarizing plate 8 are laminated so as to be substantially orthogonal.
更に、 欠陥検查用素子 1 3を、 図 5 ( b ) のように光学フィルム 1のロール長 尺方向に対し、 斜めに傾けるようにして観察する。  Further, the defect inspection element 13 is observed so as to be inclined obliquely with respect to the roll length direction of the optical film 1 as shown in FIG. 5 (b).
表 2は、 図 2 ( b ) 、 図 5 ( b ) の条件で、 観察した場合の欠陥部分の見え方 と視認性の比較を示す。 第 1実施形態の図 2 ( b ) の場合と比較し、 欠陥部分の 輝点は同様の見え方であつたが、 無欠陥部分の黒がより暗くなつており、 より欠 陥の視認性が向上していることが確認できた。 表 2  Table 2 shows a comparison of the appearance of the defect and the visibility when observed under the conditions of Fig. 2 (b) and Fig. 5 (b). Compared to the case of Fig. 2 (b) of the first embodiment, the bright spot of the defective part looks the same, but the black of the defect-free part is darker, and the defect is more visible. It was confirmed that there was an improvement. Table 2
Figure imgf000011_0001
Figure imgf000011_0001
すなわち、 第 1実施形態に更に 1軸延伸フィルムを追加することにより更に欠 陥の視認性を向上することが可能となる。 一般に、 偏光板は、 斜めに傾けた場合 に直交から外れるため光漏れが生じることが知られているが、 ここでは、 1軸延 伸フィルムを追加することにより偏光板自体の視野角特性を向上することにより 視認性を向上できたためである。 That is, it is possible to further improve the visibility of the defect by adding a uniaxially stretched film to the first embodiment. In general, polarizing plates are known to leak light because they are not perpendicular when tilted at an angle, but here, the viewing angle characteristics of the polarizing plate itself are improved by adding a uniaxially stretched film. This is because visibility was improved.
上記のような 1軸フィルムに限られず、 直交する 2方向に 2軸延伸した 2軸延 伸フィルムでも同様の視認性向上は可能である。  The same visibility improvement is possible not only with the uniaxial film as described above but also with a biaxially stretched film that is biaxially stretched in two orthogonal directions.
(第 3実施形態） (Third embodiment)
次に、 本発明に係る光学フィルムの検査方法の第 3実施形態について図 7〜図 2008/063821 Next, a third embodiment of the optical film inspection method according to the present invention will be described with reference to FIGS. 2008/063821
8を用いて説明する。 図 7〜図 8において、 第 1実施形態と同一又は同等の構成 要素については同一符号を付し、 重複する説明を省略する。 8 will be used for explanation. 7 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.
本実施形態の検査方法は、 欠陥検査用素子 1 5が以下のように構成されている 点で第 1実施形態と異なる。 欠陥検査用素子 1 5について詳細に説明する。  The inspection method of this embodiment differs from that of the first embodiment in that the defect inspection element 15 is configured as follows. The defect inspection element 15 will be described in detail.
図 7 (a) は、 長尺の光学フィルムの検査光学系を側面から見た場合を示す図 であり、 図 7 (b) は、 それを上面から見た場合を示す図であり、 長尺の光学フ イルムに対し、 欠陥検査用素子 1 5を反時計回りに傾けた場合を示す図である。 図 8は、 光学フィルム 1に含まれるハイプリッドネマチック配向液晶層 2の配 向軸 1 1、 偏光板 5の吸収軸 5 1、 ハイプリッドネマチック配向液晶フィルム 7 の配向軸 （第 2液晶フィルム） 71、 1軸延伸フィルム 1 2の遅相軸 1 2 1、 ホ メォトロピック配向液晶フィルム （第 3液晶フィルム） 14及び偏光板 8の吸収 軸 8 1の配置関係の一例を示す図である。 ここで、 1軸延伸フィルム 1 2の位相 差値は l l O nmとした。 ホメオト口ピック配向液晶フィルムとは、 ネマチック 液晶分子の配向が、 垂直配向したフィルムを言い、 例えば、 特開 2006— 22 0770号公報に記載の方法で作製できる。 ホメオト口ピック配向液晶フィルム の位相差としては、 面内方向の屈折率を n x、 n y、 厚さ方向の屈折率を n z、 フィルムの厚さを dとした場合、 厚さ方向の位相差値 R t h= { (n x + n y ) / 2 - n z } X d=— 200 nm、 面内方向の位相差値 R e = (n x - n y ) X d = 0 nmのものを用いた。  Fig. 7 (a) is a diagram showing the inspection optical system of a long optical film as seen from the side, and Fig. 7 (b) is a diagram showing it as seen from the top. FIG. 5 is a view showing a case where the defect inspection element 15 is tilted counterclockwise with respect to the optical film of FIG. Fig. 8 shows the orientation axis of the hybrid nematic alignment liquid crystal layer 2 included in the optical film 1, the absorption axis 51 of the polarizing plate 5, and the alignment axis of the hybrid nematic alignment liquid crystal film 7 (second liquid crystal film) 71 FIG. 3 is a diagram showing an example of the arrangement relationship of a slow axis 1 2 1 of a uniaxially stretched film 1 2, a homeotropic alignment liquid crystal film (third liquid crystal film) 14 and an absorption axis 8 1 of a polarizing plate 8. Here, the retardation value of the uniaxially stretched film 12 was l l O nm. The homeotopic orientation liquid crystal film refers to a film in which the alignment of nematic liquid crystal molecules is vertically aligned, and can be produced, for example, by the method described in JP-A-2006-22770. The phase difference of the homeotropic alignment liquid crystal film is as follows. When the refractive index in the in-plane direction is nx, ny, the refractive index in the thickness direction is nz, and the thickness of the film is d, the retardation value in the thickness direction R Th = {(nx + ny) / 2-nz} X d = —200 nm, in-plane direction retardation value Re = (nx−ny) X d = 0 nm was used.
図 7に示すように、欠陥検查用素子 1 5は、偏光板 8、 1軸延伸フィルム 1 2、 ホメオト口ピック配向液晶フィルム （第 3液晶フィルム） 14、 ハイブリッドネ マチック配向液晶フィルム （第 2液晶フィルム） 7を積層したものである。  As shown in Fig. 7, the defect detection element 15 is composed of a polarizing plate 8, a uniaxially stretched film 12, a home-orientated pick-aligned liquid crystal film (third liquid crystal film) 14, and a hybrid nematic aligned liquid crystal film (second Liquid crystal film) 7 is laminated.
本実施形態の欠陥検査用素子 1 5では、 第 1実施形態と同様、 ハイプリッドネ マチック配向液晶フィルム 7として、 光学フィルム 1と同一のものを用い、 図 8 に示すように、 ハイブリッドネマチック配向液晶フィルム 7の配向軸 7 1が、 偏 光板 8の吸収軸 8 1に対して 45° となるように偏光板 8に積層されている。 ま た、 1軸延伸フィルム 1 2の遅相軸 1 21と偏光板 8の吸収軸 8 1は略直交とな るように積層されている。  In the defect inspection element 15 of the present embodiment, as in the first embodiment, the hybrid nematic alignment liquid crystal film 7 is the same as the optical nematic alignment liquid crystal film 7 as shown in FIG. Are aligned on the polarizing plate 8 so that the orientation axis 7 1 is 45 ° with respect to the absorption axis 8 1 of the polarizing plate 8. The slow axis 121 of the uniaxially stretched film 12 and the absorption axis 81 of the polarizing plate 8 are laminated so as to be substantially orthogonal.
更に、 欠陥検查用素子 1 5を、 図 7 (b) のように光学フィルム 1のロール長 尺方向に対し、 斜めに傾けるようにして観察する。 8 063821 表 3は、 図 2 ( b ) 、 図 7 ( b ) の条件で、 観察した場合の欠陥部分の見え方 と視認性の比較を示す。 第 1実施形態の図 2 ( b ) の場合と比較し、 欠陥部分の 輝点は同様の見え方であつたが、 無欠陥部分の黒がより暗くなつており、 より欠 陥の視認性が向上していることが確認できた。 表 3 Further, the defect inspection element 15 is observed so as to be inclined obliquely with respect to the roll length direction of the optical film 1 as shown in FIG. 7 (b). 8 063821 Table 3 shows a comparison of the appearance and visibility of the defect when observed under the conditions of Fig. 2 (b) and Fig. 7 (b). Compared to the case of Fig. 2 (b) of the first embodiment, the bright spot of the defective part looks the same, but the black of the defect-free part is darker, and the defect is more visible. It was confirmed that there was an improvement. Table 3
Figure imgf000013_0001
Figure imgf000013_0001
すなわち、 第 1実施形態に更に 1軸延伸フィルムとホメオト口ピック配向液晶 フィルムを追加することにより更に欠陥の視認性を向上することが可能となる。 一般に、 偏光板は、 斜めに傾けた場合に直交から外れるため光漏れが生じること が知られているが、 ここでは、 1軸フィルムとホメオト口ピック配向液晶フィル ムを追加することにより偏光板自体の視野角特性を向上することにより視認性を 向上できたためである。 That is, it is possible to further improve the visibility of defects by adding a uniaxially stretched film and a homeotopically picked liquid crystal film to the first embodiment. In general, polarizing plates are known to leak light because they are not orthogonal when tilted obliquely. Here, however, the polarizing plate itself can be obtained by adding a uniaxial film and a home-to-mouth pick alignment liquid crystal film. This is because the visibility was improved by improving the viewing angle characteristics.
また、 上記第 1〜第 3実施形態においては、 ハイブリッドネマチック液晶層 2 及びハイプリッ ドネマチック液晶フィルム 7を光が透過するときに得られる位相 差をゼロにするために、 1軸延伸フィルムの遅相軸が偏光板 8の吸収軸に対して なす角度、 1軸延伸フィルムの遅相軸が偏光板 8の透過軸に対してなす角度が上 記各実施形態で示す値とされているが、 位相差を低減するという目的のためであ れば、 これらの角度は、 上記各実施形態に示す値に対して ± 1 5 ° の範囲でずれ ていても構わない。 1軸延伸フィルムの位相差値は、 5 0〜5 0 0 n mの範囲で あり、 より好ましくは 7 0〜 4 0 0 n m、 更に好ましくは 9 0〜 3 0 0 n mの範 囲である。 この範囲を外れた場合、 欠陥検査の視認性が著しく悪化する恐れがあ る。  In the first to third embodiments, the slow axis of the uniaxially stretched film is used to make the phase difference obtained when light passes through the hybrid nematic liquid crystal layer 2 and the hybrid nematic liquid crystal film 7 zero. The angle formed by the absorption axis of the polarizing plate 8 and the angle formed by the slow axis of the uniaxially stretched film with respect to the transmission axis of the polarizing plate 8 are the values shown in the above embodiments. For the purpose of reducing the above, these angles may be shifted within a range of ± 15 ° with respect to the values shown in the above embodiments. The retardation value of the uniaxially stretched film is in the range of 50 to 500 nm, more preferably in the range of 70 to 400 nm, and more preferably in the range of 90 to 300 nm. If it is out of this range, the visibility of defect inspection may be significantly deteriorated.
ホメオト口ピック配向液晶フイノレムの R t h値は、 一 5 0 n m〜一 3 0 0 n m の範囲であり、 より好ましくは一 2 5 0〜一 1 0 0 n m、 更に好ましくは一 2 2 0 1 5 0 n mの範囲であり、 ホメオト口ピック配向液晶フィルムの R e値は、The R th value of homeomorphic alignment liquid crystal Finolem is in the range of 150 nm to 1300 nm, more preferably 1 25 0 to 1 100 nm, more preferably 1 2 2 The range of 0 1 5 0 nm, and the Re value of the homeotopically picked liquid crystal film is
0〜2 0 n m、 より好ましくは 0〜 1 0 n m、 特にほぼ 0 n mであるのが好まし レ、。 0 to 20 nm, more preferably 0 to 10 nm, particularly preferably about 0 nm.
本発明は、 前述した実施形態に限定されるものではない。 例えば上記第 1実施 形態に対し、 第 1および第 2偏光板を略直交を保ったまま、 9 0度回転した場合 も同様に、 欠陥部分の視認性を向上させることが可能となり、 厚さムラに起因す る欠陥の検查を的確に行うことができる。  The present invention is not limited to the embodiment described above. For example, when the first and second polarizing plates are rotated approximately 90 degrees while maintaining substantially orthogonal to the first embodiment, it becomes possible to improve the visibility of the defective portion in the same manner, and the thickness unevenness It is possible to accurately detect defects caused by the above.
欠陥検查用素子の傾ける方向は、 前述した通り、 欠陥部分が無欠陥部分よりも 膜厚が大きくなる （位相差が大きくなる） 場合には、 欠陥検查用素子のハイプリ ッドネマチック液晶フィルムの位相差が小さくなる方向に傾けたほうがよく、 欠 陥部分が無欠陥部分よりも膜厚が小さくなる （位相差が小さくなる） 場合には、 欠陥検査用素子のハイブリッドネマチック液晶フィルムの位相差が大きくなる 方向に傾けたが方がよい。  As described above, the direction of tilting of the defect detection element is such that when the defective portion has a larger film thickness (a larger phase difference) than the non-defect portion, the position of the high-pressure nematic liquid crystal film of the defect detection element is increased. It is better to incline in the direction of decreasing the phase difference. If the film thickness of the defective part is smaller than the defect-free part (the phase difference is small), the phase difference of the hybrid nematic liquid crystal film of the defect inspection element is large. It is better to tilt in the direction.
欠陥検査用素子を傾けないまま平行に配置し、 検査員が斜め方向からみる方法 でも同様の視認性向上が可能となるが、 欠陥部分のマーキング等の作業性を考慮 した場合、 検査員が斜め方向から見て観察するよりも、 欠陥検査用素子を傾けた まま正面方向から観察したほうが好ましい。  It is possible to improve the same visibility by arranging the defect inspection elements in parallel without tilting, and the inspector sees it from an oblique direction, but the inspector is inclined when considering workability such as marking the defective part. It is preferable to observe from the front direction while tilting the defect inspection element, rather than observing from the direction.
また、 本発明による方法で欠陥検査用素子から透過される透過光を光センサで 捕捉し、 対応する画像を形成してこの画像を分析することにより欠陥を見出して もよい。 この方法によれば、 電子的処理が可能で、 欠陥部位に自動的にマーキン グすることもできる。  Further, the defect may be found by capturing the transmitted light transmitted from the defect inspection element by the method according to the present invention with an optical sensor, forming a corresponding image, and analyzing the image. According to this method, electronic processing is possible, and it is possible to automatically mark a defective part.
ハイプリッドネマチック液晶フィルムに用いられる液晶分子は、 棒状液晶分子 に限らず、 円盤状液晶分子であっても良い。 円盤状液晶分子からなるハイブリツ ドネマチック液晶フィルムを欠陥検査する場合は、 同一の円盤状ハイプリッドネ マチック液晶フィルムを含む欠陥検査用素子を用いて同様に傾斜させることで視 認性効果を得ることができる。  The liquid crystal molecules used in the hybrid nematic liquid crystal film are not limited to rod-like liquid crystal molecules, but may be disk-like liquid crystal molecules. When a hybrid nematic liquid crystal film composed of discotic liquid crystal molecules is inspected for defects, a visibility effect can be obtained by similarly tilting using a defect inspection element including the same discotic hybrid nematic liquid crystal film.
なお、 本発明の各実施形態において、 欠陥検查用素子を光学フィルムに対し傾 斜させて検査する傾斜角度としては、 5〜7 0 ° が好ましく、 より好ましくは 1 0〜 5 0 ° である。 [図面の簡単な説明] In each embodiment of the present invention, the tilt angle for inspecting the defect inspection element by tilting it with respect to the optical film is preferably 5 to 70 °, more preferably 10 to 50 °. . [Brief description of drawings]
図 1は、 本発明の光学フィルムの検查方法に用いる光学フィルムの構成の一例 を示す図である。  FIG. 1 is a diagram showing an example of the configuration of an optical film used in the optical film inspection method of the present invention.
図 2は、 本発明の光学フィルムの検査方法の第 1実施形態における光学フィル ムの検査光学系の一例を示す図であり、 （a ) は側面図、 （b ) 〜（d )は上側か ら見た場合を示す図である。  FIG. 2 is a diagram showing an example of the optical film inspection optical system in the first embodiment of the optical film inspection method of the present invention, where (a) is a side view, and (b) to (d) are upper sides. It is a figure which shows the case where it sees.
図 3は、 第 1実施形態の欠陥検査用素子、 光学フィルム 1、 第 1偏光板の吸収 軸の関係の一例を示す図である。  FIG. 3 is a diagram showing an example of the relationship between the absorption axes of the defect inspection element, the optical film 1, and the first polarizing plate of the first embodiment.
図 4は、 第 1液晶フィルムに厚さムラのある光学フィルムを示す断面図である。 図 5は、 本発明の光学フィルムの検查方法の第 2実施形態における光学フィル ムの検査光学系の一例を示す図であり、 （a ) は側面図、 （b ) は上側から見た 場合を示す図である。  FIG. 4 is a cross-sectional view showing an optical film having uneven thickness on the first liquid crystal film. FIG. 5 is a diagram showing an example of an optical film inspection optical system in the second embodiment of the optical film inspection method of the present invention, where (a) is a side view and (b) is a view from above. FIG.
図 6は、 第 2実施形態の欠陥検査用素子、 光学フィルム 1、 第 1偏光板の吸収 軸の関係の一例を示す図である。  FIG. 6 is a diagram showing an example of the relationship between the absorption axes of the defect inspection element, the optical film 1, and the first polarizing plate of the second embodiment.
図 7は、 本発明の光学フィルムの検查方法の第 3実施形態における光学フィル ムの検査光学系の一例を示す図であり、 （a ) は側面図、 （b ) は上側から見た 場合を示す図である。  FIG. 7 is a diagram showing an example of an optical film inspection optical system in the third embodiment of the optical film inspection method of the present invention, where (a) is a side view, and (b) is a view from above. FIG.
図 8は、 第 3実施形態の欠陥検査用素子、 光学フィルム 1、 第 1偏光板の吸収 軸の関係の一例を示す図である。 '  FIG. 8 is a diagram showing an example of the relationship between the absorption axes of the defect inspection element, the optical film 1, and the first polarizing plate of the third embodiment. '
(符号の説明） (Explanation of symbols)
1 光学フィルム （第 1液晶フィルム）  1 Optical film (first liquid crystal film)
2 ハイブリッドネマチック配向液晶層  2 Hybrid nematic alignment liquid crystal layer
3 液晶分子  3 Liquid crystal molecules
4 支持基板  4 Support substrate
5 偏光板 （第 1偏光板）  5 Polarizing plate (first polarizing plate)
6 ノ ックライ ト  6 Knocklight
7 ハイブリツドネマチック配向液晶フィルム （第 2液晶フィルム）  7 Hybrid nematic alignment liquid crystal film (second liquid crystal film)
8 偏光板 （第 2偏光板）  8 Polarizer (second polarizer)
9、 1 3、 1 5 欠陥検査用素子 10 異物 9, 1 3, 1 5 Element for defect inspection 10 Foreign matter
1 1 ハイブリッドネマチック配向液晶層 2の配向軸  1 1 Hybrid nematic alignment liquid crystal layer 2 Alignment axis
12 1軸延伸フィルム （第 1位相差フィルム）  12 Uniaxially stretched film (first retardation film)
14 ホメオト口ピック配向液晶フィルム （第 3液晶フィルム）  14 Home-to-mouth pick alignment liquid crystal film (third liquid crystal film)
51 第 1偏光板 5の吸収軸  51 Absorption axis of first polarizing plate 5
71 ハイブリ ッ ドネマチック配向液晶フィルム 7の配向軸  71 Alignment axis of hybrid nematic alignment liquid crystal film 7
81 第 2偏光板 8の吸収軸  81 Absorption axis of second polarizing plate 8
121 1軸延伸フィルム 12の遅相軸  121 Slow axis of uniaxially stretched film 12
[産業上の利用可能性] [Industrial applicability]
本発明の光学フィルムの検查方法により、 ハイプリッドネマチック配向液晶フ イルムを含む光学フィルムの欠陥の検查を的確に行うことができるため産業的価 値が大きい。  Since the optical film inspection method of the present invention can accurately detect defects in an optical film containing a hybrid nematic alignment liquid crystal film, the industrial value is high.

Claims

請 求 の 範 囲 The scope of the claims
1 . 液晶をハイプリッドネマチック配向させた第 1液晶フィルムを含む光 学フィルムの検查方法であって、 前記光学フィルムに対し、 光源から第 1偏光板 を通して光を照射し、 前記光学フィルムに対して前記光源と反対側に、 液晶をハ ィブリッドネマチック配向させた第 2液晶フィルムと第 2偏光板とからなる欠陥 検査用素子を、 前記第 2液晶フィルム側が前記光学フィルム側に隣接するように 配置し、 且つ前記欠陥検査用素子を、 前記光学フィルムに対し傾斜させて、 前記 光学フィルムを検査することを特徴とする光学フィルムの検查方法。 1. A method of detecting an optical film including a first liquid crystal film in which liquid crystal is aligned in a hybrid nematic orientation, wherein the optical film is irradiated with light from a light source through a first polarizing plate, and the optical film is irradiated with light. A defect inspection element comprising a second liquid crystal film in which liquid crystal is hybrid nematically aligned and a second polarizing plate on the side opposite to the light source, so that the second liquid crystal film side is adjacent to the optical film side. An inspection method for an optical film, comprising: inspecting the optical film by disposing the defect inspection element with respect to the optical film.
2 . 前記第 1液晶フィルムの配向軸と前記第 2液晶フィルムの配向軸とが 略直交するように前記欠陥検査用素子を配置することを特徴とする請求項 1に記 載の光学フィルムの検查方法。 2. The inspection of the optical film 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 substantially orthogonal to each other.查 Method.
3 . 液晶をハイプリッ ドネマチック配向させた第 1液晶フィルムを含む光 学フィルムの検査方法であって、 前記光学フィルムに対し、 光源から第 1偏光板 を通して光を照射し、 前記光学フィルムに対して前記光源と反対側に、 液晶をハ イブリッドネマチック配向させた第 2液晶フィルム、 1軸延伸フィルムからなる 第 1位相差フィルム、 第 2偏光板とを順次積層してなる欠陥検査用素子を、 前記 第 2液晶フィルム側が前記光学フィルム側に隣接するように配置し、 第 1位相差 フィルムの遅相軸と第 2偏光板の吸収軸が略直交となるように配置し、 且つ前記 欠陥検査用素子を、 前記光学フィルムに対し傾斜させて、 前記光学フィルムを検 查することを特徴とする光学フィルムの検查方法。 3. A method for inspecting an optical film including a first liquid crystal film in which liquid crystal is aligned in a hybrid nematic orientation, wherein the optical film is irradiated with light from a light source through a first polarizing plate, and the optical film is A defect inspection element comprising a second liquid crystal film in which a liquid crystal is hybrid nematically oriented, a first retardation film composed of a uniaxially stretched film, and a second polarizing plate are sequentially laminated on the opposite side of the light source. (2) Arrange the liquid crystal film side adjacent to the optical film side, arrange the slow axis of the first retardation film and the absorption axis of the second polarizing plate to be substantially orthogonal, and An optical film inspection method comprising: inclining the optical film and detecting the optical film.
4 . 前記第 1液晶フィルムの配向軸と前記第 2液晶フィルムの配向軸とが 略直交するように前記欠陥検査用素子を配置することを特徴とする請求項 3に記 载の光学フィルムの検査方法。 4. The inspection of the optical film according to claim 3, 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 substantially orthogonal to each other. Method.
5 . 液晶をハイプリッドネマチック配向させた第 1液晶フィルムを含む光 学フィルムの検査方法であって、 前記光学フィルムに対し、 光源から第 1偏光板 を通して光を照射し、 前記光学フィルムに対して前記光源と反対側に、 液晶をハ イブリツドネマチック配向させた第 2液晶フィルム、 液晶をホメオト口ピック配 向させた第 3液晶フィルム、 1軸延伸フィルムからなる第 1位相差フィルム、 第 2偏光板とを順次積層してなる欠陥検查用素子を、 前記第 2液晶フィルム側が前 記光学フィルム側に隣接するように配置し、 第 1位相差フィルムの遅相軸と第 2 偏光板の吸収軸が略直交となるように配置し、 且つ前記欠陥検查用素子を、 前記 光学フィルムに対し傾斜させて、 前記光学フィルムを検査することを特徴とする 光学フィルムの検査方法。 5. A method for inspecting an optical film including a first liquid crystal film in which liquid crystal is aligned in a hybrid nematic orientation, wherein the first polarizing plate is applied to the optical film from a light source. A second liquid crystal film in which liquid crystal is hybrid nematically aligned, a third liquid crystal film in which liquid crystal is in a home-mouth-pick orientation, uniaxial stretching, on the opposite side of the light source to the optical film. A first phase difference film comprising a film, and a defect-detecting element formed by sequentially laminating a second polarizing plate, the second liquid crystal film side being adjacent to the optical film side, and the first phase difference Inspecting the optical film by arranging the film so that the slow axis of the film and the absorption axis of the second polarizing plate are substantially orthogonal to each other, and inclining the defect detection element with respect to the optical film. An optical film inspection method.
6 . 前記第 1液晶フィルムの配向軸と前記第 2液晶フィルムの配向軸とが 略直交するように前記欠陥検査用素子を配置することを特徴とする請求項 5に記 載の光学フィルムの検查方法。 6. The inspection of an optical film according to claim 5, 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 substantially orthogonal to each other.查 Method.
7 . 液晶が棒状液晶分子からなることを特徴とする請求項 1〜6のいずれ かに記載の検査方法。 7. The inspection method according to any one of claims 1 to 6, wherein the liquid crystal is composed of rod-like liquid crystal molecules.
8 . 液晶が円盤状液晶分子からなることを特徴とする請求項 1〜 6のいず れかに記載の検查方法。 8. The inspection method according to any one of claims 1 to 6, wherein the liquid crystal comprises discotic liquid crystal molecules.
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