WO2022230657A1 - Planar lighting device, image display device, and optical film - Google Patents

Planar lighting device, image display device, and optical film Download PDF

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Publication number
WO2022230657A1
WO2022230657A1 PCT/JP2022/017575 JP2022017575W WO2022230657A1 WO 2022230657 A1 WO2022230657 A1 WO 2022230657A1 JP 2022017575 W JP2022017575 W JP 2022017575W WO 2022230657 A1 WO2022230657 A1 WO 2022230657A1
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Prior art keywords
light
layer
anisotropic
incident
light transmission
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PCT/JP2022/017575
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French (fr)
Japanese (ja)
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史岳 三戸部
晋也 渡邉
直弥 西村
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富士フイルム株式会社
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Priority to JP2023517423A priority Critical patent/JPWO2022230657A1/ja
Publication of WO2022230657A1 publication Critical patent/WO2022230657A1/en

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21S—NON-PORTABLE LIGHTING DEVICES; SYSTEMS THEREOF; VEHICLE LIGHTING DEVICES SPECIALLY ADAPTED FOR VEHICLE EXTERIORS
    • F21S2/00—Systems of lighting devices, not provided for in main groups F21S4/00 - F21S10/00 or F21S19/00, e.g. of modular construction
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
    • F21V9/00—Elements for modifying spectral properties, polarisation or intensity of the light emitted, e.g. filters
    • F21V9/08—Elements for modifying spectral properties, polarisation or intensity of the light emitted, e.g. filters for producing coloured light, e.g. monochromatic; for reducing intensity of light
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
    • F21V9/00—Elements for modifying spectral properties, polarisation or intensity of the light emitted, e.g. filters
    • F21V9/40—Elements for modifying spectral properties, polarisation or intensity of the light emitted, e.g. filters with provision for controlling spectral properties, e.g. colour, or intensity
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21Y—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES F21K, F21L, F21S and F21V, RELATING TO THE FORM OR THE KIND OF THE LIGHT SOURCES OR OF THE COLOUR OF THE LIGHT EMITTED
    • F21Y2103/00—Elongate light sources, e.g. fluorescent tubes
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21Y—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES F21K, F21L, F21S and F21V, RELATING TO THE FORM OR THE KIND OF THE LIGHT SOURCES OR OF THE COLOUR OF THE LIGHT EMITTED
    • F21Y2115/00—Light-generating elements of semiconductor light sources
    • F21Y2115/10—Light-emitting diodes [LED]
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21Y—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES F21K, F21L, F21S and F21V, RELATING TO THE FORM OR THE KIND OF THE LIGHT SOURCES OR OF THE COLOUR OF THE LIGHT EMITTED
    • F21Y2115/00—Light-generating elements of semiconductor light sources
    • F21Y2115/10—Light-emitting diodes [LED]
    • F21Y2115/15—Organic light-emitting diodes [OLED]

Definitions

  • the present invention relates to a planar illumination device, an image display device using this planar illumination device, and an optical film suitable for this planar illumination device.
  • the liquid crystal display device preferably has high luminance when observed from the front direction. Further, depending on the application of the liquid crystal display device, it is often preferable that the visibility is low when viewed from an oblique direction. Furthermore, in the case where the width of the viewing angle is switchable, when the viewing angle is narrowed, the visibility especially from oblique directions is required to be low.
  • the backlight device that constitutes the liquid crystal display device has a high front luminance, that is, the luminance of light emitted in the front direction, and more light that enters the liquid crystal panel from the front direction than light that enters the liquid crystal panel from an oblique direction. Excellent light source is required.
  • Patent Document 1 discloses a two-color liquid crystal having molecules with different light absorptances in the long-axis direction and the short-axis direction, between a backlight device (backlight unit) and a liquid crystal panel.
  • a liquid crystal display device is described that includes an optical film containing a sexual dye.
  • the dichroic dye in the optical film is oriented such that the long axis direction, in which the light absorption rate is relatively high, is perpendicular to the surface of the optical film (film plane).
  • the liquid crystal display device described in Patent Document 1 has an optical film having a dichroic dye whose long axis direction is oriented perpendicular to the surface of the film.
  • This optical film transmits light incident from the front as it is.
  • light incident from an oblique direction is absorbed by the dichroic dye oriented so that the major axis direction, which has a high light absorption rate, coincides with the thickness direction.
  • An object of the present invention is to solve the problems of the prior art, and to provide a planar illumination device used for a backlight device or the like of a liquid crystal display device, which has high front luminance and parallel light source properties.
  • An object of the present invention is to provide a planar illumination device excellent in optical properties, an image display device using the planar illumination device, and an optical film suitable for the planar illumination device.
  • Requirement 2 A0 absorbance when light with a wavelength of 550 nm is incident from the normal direction of the anisotropic light transmission layer, light with a wavelength of 550 nm from the direction of a polar angle of 50 ° with respect to the normal line of the anisotropic light transmission layer
  • A50 is the absorbance at the time of incidence, the relationship of A0 ⁇ 0.05 and the relationship of A50 ⁇ 0.05 are satisfied.
  • R0 is the reflectance when light with a wavelength of 550 nm is incident from the normal direction of the anisotropic light transmission layer;
  • R50 the reflectance at the time of incident light
  • a light absorption anisotropic layer having a transmittance central axis perpendicular to the surface of the layer;
  • An optical film having a light transmission anisotropic layer that satisfies requirements 1 and 2 below.
  • Requirement 1 The transmittance when light with a wavelength of 550 nm is incident from the normal direction of the anisotropic light transmission layer is T0, and the wavelength of 550 nm It satisfies the relationship of T0>T50 and the relationship of T50 ⁇ 70%, where T50 is the transmittance when light is incident.
  • Requirement 2 A0 absorbance when light with a wavelength of 550 nm is incident from the normal direction of the anisotropic light transmission layer, light with a wavelength of 550 nm from the direction of a polar angle of 50 ° with respect to the normal line of the anisotropic light transmission layer
  • A50 is the absorbance at the time of incidence
  • the relationship of A0 ⁇ 0.05 and the relationship of A50 ⁇ 0.05 are satisfied.
  • the structure according to [8] which has a polarization control layer between the anisotropic light transmission layer and the anisotropic light absorption layer that rotates the polarization direction of incident linearly polarized light within a range of 80 to 100°. optical film.
  • planar illumination device having high front luminance and excellent parallel light source properties, an image display device capable of displaying high-quality images using the planar illumination device, and the planar illumination device Optical films suitable for devices are provided.
  • FIG. 1 is a diagram conceptually showing an example in which the planar illumination device of the present invention is used in a backlight device.
  • FIG. 2 is a diagram conceptually showing another example in which the planar lighting device of the present invention is used in a backlight device.
  • FIG. 3 is a diagram conceptually showing the reflectance of light by a general layer.
  • FIG. 4 is a diagram conceptually showing the light reflectance of the anisotropic light transmission layer.
  • FIG. 5 is a diagram conceptually showing another example of the light transmission anisotropic layer.
  • planar lighting device, image display device and optical film of the present invention will be described in detail below.
  • the following description is based on representative embodiments of the invention, but the invention is not limited to such embodiments.
  • all of the drawings shown below are conceptual diagrams for explaining the present invention. Therefore, in each drawing, the shape, size, thickness, and positional relationship such as arrangement position and spacing of each member do not necessarily match the actual device.
  • a numerical range represented by "-" means a range including the numerical values before and after "-" as lower and upper limits.
  • the backlight device 10 that is, the planar lighting device of the present invention
  • the backlight device 10 may optionally include a dye compound on the light emitting side of the light transmission anisotropic layer 18 in order to make the emitted light color neutral. and the like may be provided.
  • the light source 14 in the backlight device 10 various known light sources (light emitting elements) used in so-called direct type backlight devices can be used.
  • the light source 14 include an LED (Light Emitting Diode), an organic EL (Electro Luminescence), a fluorescent lamp, and the like.
  • the light source 14 of the backlight device 10 is composed of a light-emitting element and a wavelength conversion material (fluorescent material), such as a combination of a blue LED and a quantum dot layer that emits fluorescence of red light and green light when blue light is incident. Combinations with layers are also available.
  • the light source 14 may be a white light source, or may emit white light as a whole by combining a red light source, a green light source, and a blue light source.
  • the light source 14 is two-dimensionally arranged on the reflective layer 12 (light reflecting surface).
  • the arrangement of the light source 14 may be the same as that of a general direct type backlight device used in a liquid crystal display device. Therefore, the arrangement of the light sources 14 may be regular or irregular, but is usually regular. Also, the arrangement density of the light sources 14 may be uniform in the surface direction of the reflective layer 12, or may vary.
  • a light diffusion layer 16 is arranged downstream of the light source 14 .
  • the downstream side is the downstream side in the traveling direction of light emitted from the light source 14 and extending from the light diffusion layer 16 to the light absorption anisotropic layer 20 .
  • various known materials used in backlight devices for liquid crystal display devices can be used. Examples include frosted glass, transparent plates that have undergone surface roughening such as sandblasting, and resin base films such as polystyrene, polycarbonate, acrylic resin, and methyl methacrylate/styrene copolymer, with silicone and acrylic base films.
  • a light diffusion plate (light diffusion film, light diffusion sheet) such as a film in which diffusion beads are diffused is exemplified.
  • a prism sheet can also be used as the light diffusion layer 16 .
  • a prism sheet is used as the light diffusing layer 16
  • one prism sheet may be used, but it is preferable to use two prism sheets whose ridge lines are perpendicular to each other.
  • the light diffusion layer 16 can also be a combination of one or more of the light diffusion plates described above and a prism sheet.
  • the light transmission anisotropic layer 18 satisfies this requirement 1, and furthermore, as requirement 2, the absorbance when light with a wavelength of 550 nm is incident from the normal direction is A0, and the polar angle with respect to the normal is The relationship A0 ⁇ 0.05 and the relationship A50 ⁇ 0.05 are satisfied, where A50 is the absorbance when light with a wavelength of 550 nm is incident from the direction of 50°.
  • the anisotropic light transmission layer 18 preferably satisfies the requirements 1 and 2 described above, and reflects obliquely incident light with high reflectance.
  • the anisotropic light transmission layer 18 has a reflectance of R0 when light with a wavelength of 550 nm is incident from the normal direction, and a wavelength of 550 nm from a direction with a polar angle of 50° to the normal.
  • R50 is the reflectance at the time of incident light
  • the relationship of R0 ⁇ R50 and the relationship of R50>30% are satisfied.
  • another example of the light transmission anisotropic layer diffuses the light that is incident obliquely rather than reflecting it.
  • the anisotropic light transmission layer 18 does not absorb or reflect light incident in the normal direction, that is, from the front, but transmits the light with high transmittance.
  • the anisotropic light transmission layer 18 does not transmit or absorb light incident from an oblique direction, such as a direction with a polar angle of 50° with respect to the normal line. As such, it reflects with high reflectance.
  • the backlight device 10, i.e., the planar lighting device of the present invention has such an anisotropic light transmission layer 18 and an anisotropic light absorption layer 20, which will be described later. It realizes a planar lighting device with excellent performance. This point will be described in detail later.
  • the anisotropic light transmission layer 18 has a transmittance T50 of less than 70% for light with a wavelength of 550 nm incident from a direction with a polar angle of 50° with respect to the normal. If the transmittance T50 is 70% or more, problems arise in that sufficient front luminance and parallel light source properties cannot be obtained.
  • the transmittance T50 is preferably as low as possible.
  • the transmittance T50 is preferably less than 50%, more preferably less than 35%.
  • the absorbance A0 when light with a wavelength of 550 nm is incident from the normal direction, and the absorbance A50 when light with a wavelength of 550 nm is incident from the direction of a 50° polar angle with respect to the normal. are both less than 0.05. If the absorbance A0 and the absorbance A50 are 0.05 or more, the efficiency of light utilization is low and sufficient front luminance cannot be obtained.
  • Absorbance A0 and absorbance A50 are preferably as low as possible.
  • Absorbance A0 and absorbance A50 are preferably less than 0.02, more preferably less than 0.01.
  • the light transmission anisotropic layer 18 in the illustrated example preferably has a reflectance R0 for light with a wavelength of 550 nm incident from the normal direction,
  • the reflectance R50 satisfies R0 ⁇ R50 and R50>30%.
  • a reflectance R50 of more than 30% is preferable in that front luminance can be improved and parallel light source properties can be improved.
  • the reflectance R50 is preferably as high as possible, more preferably over 50%, and even more preferably over 65%.
  • the reflectance R0 is preferably as low as possible.
  • the reflectance R0 is preferably less than 10%, more preferably less than 7%, even more preferably less than 4%.
  • a reflectance R0 of less than 10% is preferable in that the front luminance can be improved and parallel light source properties can be improved.
  • An anisotropic light absorption layer 20 is arranged downstream of the anisotropic light transmission layer 18 .
  • the light absorption anisotropic layer 20 is a layer whose transmittance center axis is perpendicular to the surface of the layer.
  • the transmittance center axis is perpendicular to the surface of the layer means not only the complete perpendicularity to the surface of the layer, but also the direction perpendicular to the surface of the layer. including the angular range of .
  • the optical film of the present invention includes the anisotropic light transmission layer 18 and the anisotropic light absorption layer 20 described above.
  • the transmittance central axis is the direction in which the transmittance is highest when the transmittance is measured in various directions from the surface of the layer by changing the polar angle and azimuth angle. Therefore, the light absorption anisotropic layer 20 whose transmittance center axis is perpendicular to the surface of the layer transmits the light incident from the normal direction, that is, from the front as it is, and is inclined to the normal, that is, obliquely. Light incident from any direction is absorbed.
  • the dichroic substance is not particularly limited, and includes visible light absorbing substances (dichroic dyes), luminescent substances (fluorescent substances, phosphorescent substances), ultraviolet absorbing substances, infrared absorbing substances, nonlinear optical substances, carbon nanotubes, and inorganic Substances (for example, quantum rods) and the like can be mentioned, and conventionally known dichroic substances (dichroic dyes) can be used.
  • two or more dichroic substances may be used together.
  • at least one dichroic substance having a maximum absorption wavelength in the wavelength range of 370 to 550 nm and a maximum absorption wavelength in the wavelength range of 500 to 700 nm are used. It is preferable to use together with at least one kind of dichroic substance having.
  • the method of forming the light absorption anisotropic layer 20 is not particularly limited, but from the viewpoint of aligning the dichroic substance with a high degree of orientation, it is formed using a liquid crystal composition containing a liquid crystal compound together with the dichroic substance described above. methods are preferred.
  • the liquid crystal compound is a liquid crystal compound that does not exhibit dichroism.
  • the liquid crystal compound both a low-molecular-weight liquid crystal compound and a high-molecular-weight liquid crystal compound can be used, but a high-molecular-weight liquid crystal compound is more preferable in order to obtain a high degree of alignment.
  • the term "low-molecular-weight liquid crystal compound” refers to a liquid crystal compound having no repeating unit in its chemical structure.
  • polymeric liquid crystal compound refers to a liquid crystal compound having a repeating unit in its chemical structure.
  • Low-molecular-weight liquid crystal compounds include, for example, liquid crystal compounds described in JP-A-2013-228706.
  • polymer liquid crystal compounds include thermotropic liquid crystal polymers described in JP-A-2011-237513.
  • the polymer liquid crystal compound may have a crosslinkable group (for example, an acryloyl group and a methacryloyl group) at its terminal.
  • a liquid crystal compound may be used individually by 1 type, and may use 2 or more types together.
  • the liquid crystal compound preferably contains a polymer liquid crystal compound from the viewpoint that the degree of orientation of the light absorption anisotropic layer 20 is more excellent.
  • the liquid crystal composition may contain a solvent, a polymerization initiator, an interface improver, an alignment agent, and components other than these.
  • the liquid crystal composition is first applied to an alignment film to which the liquid crystal compound is oriented.
  • the liquid crystal composition is heated and/or cooled, or the heating and cooling are repeated to align the liquid crystal compound in the thickness direction. Due to this orientation of the liquid crystal compound, the dichroic substance is similarly oriented in the thickness direction.
  • the liquid crystal layer is cured by irradiating with ultraviolet rays or the like, thereby forming the light absorption anisotropic layer 20 in which the dichroic substance is oriented in the thickness direction.
  • the planar illumination device of the present invention will be described in more detail by describing the operation of the backlight device 10 with reference to FIG.
  • the incidence of light in the normal direction that is, from the front
  • frontal incidence incidence of light from a direction having an angle with respect to the normal
  • oblique incidence incidence of light from a direction having an angle with respect to the normal
  • the light (dashed line) emitted by the light source 14 is first diffused by the light diffusion layer 16 and then enters the light transmission anisotropic layer 18 .
  • the anisotropic light-transmitting layer 18 transmits light incident from the front as it is, and reflects light incident at an oblique angle. Therefore, of the light diffused by the light diffusion layer 16 , the light incident on the anisotropic light transmission layer 18 is transmitted as it is and enters the anisotropic light absorption layer 20 .
  • the light-absorbing anisotropic layer 20 transmits front incident light as it is, and absorbs obliquely incident light. Therefore, the light that is frontally incident on and transmitted through the anisotropic light transmission layer 18 is also frontally incident on the anisotropic light absorption layer 20. Pass through as is.
  • the planar illumination device of the present invention When the planar illumination device of the present invention is used as a backlight device for a liquid crystal display device, the light transmitted through the light absorption anisotropic layer 20 is emitted from the light absorption anisotropic layer 20, such as a liquid crystal, arranged downstream of the light absorption anisotropic layer 20.
  • the panel is also front-incident.
  • the light incident on the anisotropic light transmission layer 18 from the front is transmitted as it is and enters the anisotropic light absorption layer 20 from the front. Frontal incidence on the panel.
  • the light obliquely incident on the light transmission anisotropic layer 18 is reflected by the light transmission anisotropic layer 18, diffused by the light diffusion layer 16, reflected by the reflection layer 12, and reflected by the light diffusion layer It is diffused at 16 and reenters the light transmission anisotropic layer 18 as before.
  • the light obliquely incident on the light transmission anisotropic layer 18 is reflected by the light absorption anisotropic layer 20, diffused by the light diffusion layer 16, Reflection by the reflective layer 12 and diffusion by the light diffusion layer 16 are repeated.
  • the light reaches a state of frontal incidence on the light transmission anisotropic layer 18, the light passes through the light transmission anisotropic layer 18, and then passes through the light absorption anisotropic layer 20 frontally. After being incident and transmitted, the light enters the liquid crystal panel from the front.
  • the light transmission anisotropic layer 18 transmits front incident light and reflects obliquely incident light, and the front incident light is transmitted and obliquely incident light is absorbed.
  • the emitted light can be focused in the front direction.
  • the obliquely incident light is reflected by the light transmission anisotropic layer 18 and the obliquely incident light is absorbed by the light absorption anisotropic layer 20, so that the light is emitted in the front direction.
  • the amount of light emitted obliquely can be greatly reduced.
  • the front luminance that is, the luminance of the light emitted in the front direction is high, and the amount of light emitted in the front direction is large compared to the light emitted in the oblique direction.
  • An excellent planar lighting device can be realized.
  • FIG. 2 shows another example in which the planar illumination device of the present invention is used as a backlight device.
  • the backlight device 30 shown in FIG. 2 has the same configuration as the backlight device 10 shown in FIG. , Mainly performed on different parts.
  • the backlight device 30 shown in FIG. 2 has a polarization control layer 26 between the anisotropic light transmission layer 18 and the anisotropic light absorption layer 20 . That is, the optical film of the present invention described above may have the polarization control layer 26 between the anisotropic light transmission layer 18 and the anisotropic light absorption layer 20 .
  • the anisotropic light transmission layer 18, the polarization control layer 26 and the anisotropic light absorption layer 20 may all be laminated, or two layers may be laminated. or all may be spaced apart. Also, the light diffusion layer 16 may be laminated on the light transmission anisotropic layer 18 or may be separated therefrom.
  • the polarization control layer 26 rotates the polarization direction of incident linearly polarized light within the range of 80 to 100 degrees. Since the backlight device 30, that is, the planar lighting device of the present invention has such a polarization control layer 26, parallel light source properties can be further improved.
  • P-polarized light is linearly polarized light whose polarization direction is orthogonal to the surface of the anisotropic light absorption layer 20, that is, the surface of the anisotropic light transmission layer 18, and S-polarized light is light whose polarization direction is light. It is linearly polarized light parallel to the surface of the anisotropic absorption layer 20 , that is, the surface of the anisotropic light transmission layer 18 .
  • the anisotropic light absorption layer 20 absorbs obliquely incident light, but as with ordinary layers, the absorptance of the anisotropic light absorption layer 20 is higher for S-polarized light than for P-polarized light. is lower. Therefore, when the light incident on the anisotropic light absorption layer 20 contains more S-polarized components than P-polarized components, the absorption rate of obliquely incident light by the anisotropic light absorption layer 20 decreases. As a result, there is a possibility that the proportion of light that passes through the anisotropic light absorption layer 20 without being absorbed may increase even though the light is obliquely incident on the anisotropic light absorption layer 20 .
  • the backlight device 30 that is, the planar lighting device of the present invention
  • the polarization direction of the incident linearly polarized light is has a polarization control layer 26 that rotates in the range of 80-100°. That is, as a preferred embodiment, the backlight device 30 has a polarization control layer 26 between the anisotropic light transmission layer 18 and the anisotropic light absorption layer 20 that converts S-polarized light into P-polarized light.
  • the light transmitted through the anisotropic light transmission layer 18 has more S-polarized components than P-polarized components. Therefore, by providing the polarization control layer 26 between the anisotropic light transmission layer 18 and the anisotropic light absorption layer 20, the light transmitted through the polarization control layer 26 and incident on the anisotropic light absorption layer 20 is has more P-polarized components than S-polarized components. Therefore, by providing the polarization control layer 26 between the anisotropic light transmission layer 18 and the anisotropic light absorption layer 20, the absorption rate of obliquely incident light by the anisotropic light absorption layer 20 is improved. can.
  • the transmittance of light obliquely incident on the light absorption anisotropic layer 20 can be further reduced.
  • the presence of the polarization control layer 26 increases the ratio of the light emitted in the front direction to the light emitted in the oblique direction in the light emitted from the light absorption anisotropic layer 20, that is, the backlight device 30.
  • the parallel light source property can be further improved.
  • the polarization control layer 26 is not limited, and various known materials (optical elements) can be used as long as they can rotate the polarization direction of incident linearly polarized light within the range of 80 to 100 degrees.
  • An example of the polarization control layer 26 is a layer containing a liquid crystal compound twisted along a helical axis extending along the thickness direction. That is, the polarization control layer 26 is exemplified by a layer (optical rotatory layer, optical rotatory film) containing a liquid crystal compound helically twisted in the thickness direction.
  • the twist angle of the liquid crystal compound is not limited, and the polarization direction of the linearly polarized light is 80 to 100° depending on the type of the liquid crystal compound.
  • a torsion angle that can be rotated within the range of can be appropriately set.
  • the twist angle of the liquid crystal compound can be adjusted by the type and amount of the chiral agent.
  • the ⁇ n, film thickness d, and ⁇ nd of the liquid crystal compound are not limited, and the polarization direction of linearly polarized light is 80 to 100°. can be set as appropriate so that it can be rotated within the range of .
  • a half-wave plate can also be used as the polarization control layer 26 .
  • the half-wave plate has a phase difference of about half the wavelength at any wavelength of visible light. , is available.
  • a half-wave plate having a phase difference of 220 to 330 nm at a wavelength of 550 nm is preferably exemplified, and a half-wave plate having a phase difference of 247 to 302 nm is more preferably exemplified. be.
  • the anisotropic light transmission layer 18 transmits front incident light and reflects obliquely incident light.
  • the light transmission anisotropic layer is not limited to this. That is, in the planar illumination device of the present invention, Requirement 1 that the transmittance T0 and the transmittance T50 are T0>T50 and T50 ⁇ 70%, and that both the absorbance T0 and the absorbance T50 are less than 0.05. As long as it satisfies Requirement 2, various known materials can be used.
  • the light emitted from the anisotropic light-absorbing layer 20, that is, the planar lighting device, in the front direction is increased, and the light emitted in the oblique direction is decreased. can.
  • this light transmission anisotropic layer 34 it is possible to realize a planar illumination device with high front luminance and excellent parallel light source properties.
  • At least one compound having a plurality of aromatic rings and one polymerizable carbon-carbon double bond in the molecule which is a compound containing an aromatic hydroxyl group and the content of this compound is 0.1 to 30 parts by weight with respect to 100 parts by weight of the film composition, is irradiated with ultraviolet rays from a specific direction.
  • a light transmission anisotropic layer (light control film) that selectively scatters incident light within a specific range of angles obtained by curing this composition can also be used.
  • a commercially available product such as a vision control film manufactured by Sumitomo Chemical Co., Ltd. can be used as the light transmission anisotropic layer 34 that transmits front incident light and diffuses obliquely incident light.
  • the image display device of the present invention is an image display device having such a planar illumination device of the present invention.
  • various known image display devices can be used as long as they use a planar illumination device.
  • a preferred example is a liquid crystal display (LCD) having a known liquid crystal panel.
  • the planar illumination device of the present invention has high front luminance and excellent parallel light source properties. Therefore, the image display device of the present invention using such a planar illumination device of the present invention can display a high-quality image with high front display luminance, and can reduce visibility when observed from an oblique direction. It has excellent visual field controllability.
  • planar illumination device the image display device and the optical film of the present invention have been described in detail above, the present invention is not limited to the above examples, and various improvements and improvements can be made without departing from the scope of the present invention. Of course, changes may be made.
  • the following composition for forming an anisotropic light absorption layer was continuously applied with a wire bar, heated at 120° C. for 60 seconds, and then cooled to room temperature (23° C.). Then, it was heated at 80° C. for 60 seconds and cooled again to room temperature. After that, an LED lamp (center wavelength 365 nm) was used to irradiate ultraviolet rays for 2 seconds under irradiation conditions of an illuminance of 200 mW/cm 2 to form a light absorption anisotropic layer on the alignment film.
  • the film thickness of the light absorption anisotropic layer was 3.5 ⁇ m.
  • Composition of Composition for Forming Light Absorption Anisotropic Layer Dichroic substance D-1 0.63 parts by mass Dichroic substance D-2 0.17 parts by mass Dichroic substance D-3 1.13 parts by mass Polymer liquid crystal compound P-1 8.18 Parts by mass IRGACUREOXE-02 (manufactured by BASF) 0.16 parts by mass Compound E-1 0.12 parts by mass Compound E-2 0.12 parts by mass Surfactant F-1 0.005 parts by mass Cyclo Pentanone 85.00 parts by mass Benzyl alcohol 4.50 parts by mass ⁇
  • the direction of the transmittance center axis was measured by measuring the transmittance while changing the polar angle and azimuth angle using AxoScan OPMF-1 (manufactured by Optoscience). As a result, the transmittance central axis was perpendicular to the surface of the layer.
  • the produced laminate was heated by a roll group set at a temperature of 60° C., stretched 3.7 times by rolls set at a temperature of 85° C., and cooled. After cooling, after heating with hot air at a temperature of 90°C, the film was stretched 3.2 times in the direction perpendicular to the previously stretched direction at a temperature of 95°C. After stretching, heat treatment was performed with hot air at 240°C. Following the heat treatment, a 2% relaxation treatment was performed at 240° C. to form a light transmission anisotropic layer comprising an optical multilayer film.
  • Transmittance T0 was measured using an automatic polarizing film measuring device (manufactured by JASCO Corporation, VAP-7070) with an integrating sphere placed on the light receiving side and measuring transmittance T0 at a wavelength of 550 nm. Subsequently, using a goniophotometer, light is irradiated in a polar angle of 50° with respect to the normal direction of the surface, and the angle on the light receiving side is changed in the range of -80° to 80° in increments of 5°. , the light intensity of the transmitted light was measured. The transmittance T50 was obtained by accumulating the light intensity for each light receiving angle and normalizing it by the total light amount without the measurement sample. As the goniophotometer, "Three-dimensional goniospectrophotometry system GCMS-3B" manufactured by Murakami Color Research Laboratory was used. Also, the angle on the light receiving side is the polar angle with respect to the normal.
  • Reflectance R0 was measured by roughening the surface opposite to the incident surface with sandpaper and then treating it with black ink to eliminate back reflection. ) was used to measure the integrated reflectance at a wavelength of 550 nm. Subsequently, using a goniophotometer, light was irradiated at a polar angle of 50° with respect to the normal direction of the surface, and the angle on the light receiving side was changed in the range of -80° to 35° in increments of 5°. , the light intensity of the reflected light was measured. The reflectance R50 was obtained by accumulating the light intensity for each of these light receiving angles and normalizing it by the total light amount when a mirror was arranged as a measurement sample. As the goniophotometer, "Three-dimensional goniospectrophotometry system GCMS-3B" manufactured by Murakami Color Research Laboratory was used. Also, the angle on the light receiving side is the polar angle with respect to the normal.
  • absorbance A0 was obtained from the measured transmittance T0 and reflectance R0 using the following formula.
  • A0 -LOG10(T0+R0)
  • the absorbance A50 was obtained from the measured transmittance T50 and reflectance R50 using the following formula.
  • A50 -LOG10(T50+R50)
  • IPS mode liquid crystal display device was disassembled, and a liquid crystal panel (liquid crystal cell) was taken out.
  • liquid crystal display device "iPad Air (registered trademark) Wi-Fi model 16 GB” manufactured by APPLE was used.
  • the optical film 1 was arranged on the diffusion sheet in the liquid crystal display device from which the liquid crystal panel was taken out so that the light transmission anisotropic layer was on the diffusion sheet side, thereby producing the backlight device A1.
  • Example 2 ⁇ Formation of color adjustment layer> On the light absorption anisotropic layer of the optical film 1 produced in Example 1, the following composition for forming a color adjustment layer was continuously applied with a wire bar to form a coating film. Next, the layered product with the coating film formed thereon was dried with hot air at 60° C. for 60 seconds and then with hot air at 100° C. for 120 seconds to form a color tone adjusting layer, thereby producing an optical film 2 .
  • the film thickness of the tint adjusting layer was 0.5 ⁇ m.
  • a backlight device A2 was fabricated in the same manner as in Example 1, except that the optical film 2 was used instead of the optical film 1 in the fabrication of the backlight device A1 of Example 1.
  • Example 3 ⁇ Production of transfer film> A peelable support was prepared by subjecting the surface of a 75 ⁇ m PET film (manufactured by Fuji Film) to a rubbing treatment.
  • the following optically active layer coating solution was applied using a bar coater to a film thickness of 3 ⁇ m to form a coating film. Then, the coating film surface temperature was set to 60° C. and heat aging was performed for 90 seconds. Thereafter, the coating film was irradiated with ultraviolet rays of 300 mJ/cm 2 at 100° C. to fix the orientation of the liquid crystal compound and form an optically active layer.
  • a transfer film including a peelable support and an optical rotation layer as a polarization control layer was produced.
  • the liquid crystal compound had a ⁇ n of 0.16, a film thickness d of 3000 nm, and a ⁇ nd of 480.
  • the optically active layer contained a liquid crystal compound that was twisted along the helical axis extending along the thickness direction.
  • a transfer film containing an optical rotation layer was placed between the two polarizing plates, and the two polarizing plates were rotated in the in-plane direction so that the light passing through the two polarizing plates was the darkest.
  • the optical rotation layer was an optical rotation layer that rotates the polarization direction of linearly polarized light by 90°.
  • Example 2 In the preparation of the optical film 2 in Example 2, prior to bonding the anisotropic light absorption layer and the anisotropic light transmission layer, a commercially available adhesive (SK2057 manufactured by Soken Kagaku Co., Ltd.) was used to apply an anisotropic light absorption layer. A transfer film was attached to the anisotropic layer. The transfer film was attached so that the optical rotation layer was on the light absorption anisotropic layer side. The peelable support was then peeled off. After peeling off the peelable support, the optical rotatory layer remained attached to the light absorption anisotropic layer side.
  • a commercially available adhesive (SK2057 manufactured by Soken Kagaku Co., Ltd.) was used to apply an anisotropic light absorption layer. A transfer film was attached to the anisotropic layer. The transfer film was attached so that the optical rotation layer was on the light absorption anisotropic layer side. The peelable support was then peeled off. After peeling off the peelable support, the optical rotatory layer
  • a backlight device A4 was fabricated in the same manner as in Example 2 except that the optical film 4 was used instead of the optical film 2 in the fabrication of the backlight device A2 of Example 2.
  • Example 3 backlight device A3
  • Example 4 backlight device A3 having an optical rotatory layer as a polarization control layer and a half-wave plate between the anisotropic light transmission layer and the anisotropic light absorption layer
  • the light device A4 has excellent parallel light source properties. From the above results, the effect of the present invention is clear.

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Abstract

The present invention addresses the problem of providing a planar lighting device that has excellent frontal brightness and parallel light source characteristics, an image display device that uses the planar lighting device, and an optical film for use in the planar lighting device. The present invention has, in order, a light-absorbing anisotropic layer for which a transmittance center axis is orthogonal to the surface of the layer, a light-transmitting anisotropic layer, a light-diffusing layer, a light source, and a reflection layer. When T0 is the transmittance and A0 is the absorbance when light of a wavelength of 550 nm is incident from the normal line direction to the light-transmitting anisotropic layer and T50 is the transmittance and A50 is the absorbance when light of a wavelength of 550 nm is incident from the direction at a polar angle of 50° to a normal line to the light-transmitting anisotropic layer, T0>T50, T50<70%, A0<0.05, and A50<0.05.

Description

面状照明装置、画像表示装置および光学フィルムPlanar illumination device, image display device and optical film
　本発明は、面状照明装置、この面状照明装置を用いる画像表示装置、および、この面状照明装置に好適な光学フィルムに関する。 The present invention relates to a planar illumination device, an image display device using this planar illumination device, and an optical film suitable for this planar illumination device.
　タブレットＰＣ（Personal Computer）およびスマートフォンなどのディスプレイ、テレビジョンおよびモニタ等の画像表示装置、車載用のディスプレイ等の各種のディスプレイに、液晶表示装置が利用されている。
　液晶表示装置は、ＴＦＴ（Thin Film Transistor）アレイが形成された基板を含む２枚の基板の間に液晶材料を封じ込めた液晶パネルと、画像を表示するための光（バックライト）を液晶パネルに照射する面状照明装置であるバックライト装置とを有する。 2. Description of the Related Art Liquid crystal display devices are used in various displays such as displays for tablet PCs (Personal Computers) and smartphones, image display devices such as televisions and monitors, and in-vehicle displays.
A liquid crystal display device consists of a liquid crystal panel in which a liquid crystal material is enclosed between two substrates including a substrate on which a TFT (Thin Film Transistor) array is formed, and light (backlight) for displaying images is sent to the liquid crystal panel. and a backlight device, which is a planar lighting device that emits light.
　液晶表示装置には、良好な視認性を得るために、正面方向から観察した際の輝度が高いのが好ましい。
　また、液晶表示装置の用途によっては、斜め方向から覗き見をされた際に、視認性が低いのが好ましい場合が多い。さらに、視野角の広さが切替可能である場合には、狭視野角化した際には、特に斜め方向からの視認性は低いことが要求される。 In order to obtain good visibility, the liquid crystal display device preferably has high luminance when observed from the front direction.
Further, depending on the application of the liquid crystal display device, it is often preferable that the visibility is low when viewed from an oblique direction. Furthermore, in the case where the width of the viewing angle is switchable, when the viewing angle is narrowed, the visibility especially from oblique directions is required to be low.
　そのため、液晶表示装置では、液晶パネルに正面すなわち法線方向から高輝度の光を入射でき、かつ、斜め方向すなわち法線に対して角度を有する方向から液晶パネルに入射する光が少ないのが好ましい。
　従って、液晶表示装置を構成するバックライト装置には、正面輝度すなわち正面に出射する光の輝度が高く、かつ、液晶パネルに斜め方向から入射する光よりも、正面から入射する光が多い、平行光源性に優れることが要求される。 Therefore, in the liquid crystal display device, it is preferable that high-intensity light can be incident on the liquid crystal panel from the front, that is, in the normal direction, and less light is incident on the liquid crystal panel from an oblique direction, that is, a direction having an angle with respect to the normal. .
Therefore, the backlight device that constitutes the liquid crystal display device has a high front luminance, that is, the luminance of light emitted in the front direction, and more light that enters the liquid crystal panel from the front direction than light that enters the liquid crystal panel from an oblique direction. Excellent light source is required.
　この目的を達成するために、例えば、特許文献１には、バックライト装置（バックライトユニット）と液晶パネルとの間に、長軸方向と短軸方向とで分子の光吸収率が異なる二色性色素を含む光学フィルムを備える液晶表示装置が記載されている。この液晶表示装置において、光学フィルムの二色性色素は、光吸収率が相対的に高い長軸方向が、光学フィルムの表面（フィルム面）に対して垂直に配向している。 In order to achieve this purpose, for example, Patent Document 1 discloses a two-color liquid crystal having molecules with different light absorptances in the long-axis direction and the short-axis direction, between a backlight device (backlight unit) and a liquid crystal panel. A liquid crystal display device is described that includes an optical film containing a sexual dye. In this liquid crystal display device, the dichroic dye in the optical film is oriented such that the long axis direction, in which the light absorption rate is relatively high, is perpendicular to the surface of the optical film (film plane).
特開２０１８－３６２９５号公報JP 2018-36295 A
　上述のように、特許文献１に記載される液晶表示装置は、長軸方向がフィルムの表面に対して垂直に配向された二色性色素を有する光学フィルムを有する。
　この光学フィルムは、正面方向から入射した光は、そのまま透過する。これに対して、この光学フィルムでは、斜め方向から入射した光は、光吸収率が高い長軸方向を厚さ方向と一致して配向された二色性色素が吸収する。 As described above, the liquid crystal display device described in Patent Document 1 has an optical film having a dichroic dye whose long axis direction is oriented perpendicular to the surface of the film.
This optical film transmits light incident from the front as it is. On the other hand, in this optical film, light incident from an oblique direction is absorbed by the dichroic dye oriented so that the major axis direction, which has a high light absorption rate, coincides with the thickness direction.
　そのため、この液晶表示装置では、相対的に、液晶パネルに斜め方向から入射する光に比して、正面方向から入射する光が多くなる。
　その結果、特許文献１に記載される液晶表示装置によれば、ＩＰＳ（In-Plane Switching）方式およびＦＦＳ（Fringe Field Switching）方式等の横電界方式の液晶パネルを用いる液晶表示装置において、斜め方向（広角）から液晶パネルに入射する光を低減して、コントラスト比を向上できる。 Therefore, in this liquid crystal display device, the amount of light incident on the liquid crystal panel from the front direction is relatively greater than the amount of light incident on the liquid crystal panel from oblique directions.
As a result, according to the liquid crystal display device described in Patent Document 1, in a liquid crystal display device using a lateral electric field type liquid crystal panel such as an IPS (In-Plane Switching) method and an FFS (Fringe Field Switching) method, the oblique direction The contrast ratio can be improved by reducing the light incident on the liquid crystal panel from (wide angle).
　しかしながら、液晶表示装置の画質に対する要求は、より高くなっており、さらに正面輝度が高く、かつ、平行光源性にも優れるバックライト装置の出現が望まれている。 However, the demand for the image quality of liquid crystal display devices is becoming higher, and the emergence of backlight devices with high front luminance and excellent parallel light source properties is desired.
　本発明の目的は、このような従来技術の問題点を解決することにあり、液晶表示装置のバックライト装置等に用いられる面状照明装置であって、正面輝度が高く、かつ、平行光源性にも優れる面状照明装置、この面状照明装置を用いる画像表示装置、および、この面状照明装置に好適な光学フィルムを提供することにある。 SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the prior art, and to provide a planar illumination device used for a backlight device or the like of a liquid crystal display device, which has high front luminance and parallel light source properties. An object of the present invention is to provide a planar illumination device excellent in optical properties, an image display device using the planar illumination device, and an optical film suitable for the planar illumination device.
　このような目的を達成するために、本発明は、以下の構成を有する。
　［１］　光吸収異方性層と、光透過異方性層と、光拡散層と、光源と、反射層とを、この順番で有し、
　光吸収異方性層は、透過率中心軸が層の表面に対して垂直であり、
　光透過異方性層が、下記の要件１および要件２を満たす、面状照明装置。
　要件１：光透過異方性層の法線方向から波長５５０ｎｍの光を入射した際における透過率をＴ０、光透過異方性層の法線に対して極角５０°の方向から波長５５０ｎｍの光を入射した際における透過率をＴ５０とした際に、Ｔ０＞Ｔ５０の関係、および、Ｔ５０＜７０％の関係を満たす。
　要件２：光透過異方性層の法線方向から波長５５０ｎｍの光を入射した際における吸光度をＡ０、光透過異方性層の法線に対して極角５０°の方向から波長５５０ｎｍの光を入射した際における吸光度をＡ５０とした際に、Ａ０＜０．０５の関係、および、Ａ５０＜０．０５の関係を満たす。
　［２］　光透過異方性層の法線方向から波長５５０ｎｍの光を入射した際における反射率をＲ０、光透過異方性層の法線に対して極角５０°の方向から波長５５０ｎｍの光を入射した際における反射率をＲ５０とした際に、
　光透過異方性層が、Ｒ０＜Ｒ５０の関係、および、Ｒ５０＞３０％の関係を満たす、［１］に記載の面状照明装置。
　［３］　光透過異方性層が、異なる複数の層が５０層以上積層された多層膜である、［１］または［２］に記載の面状照明装置。
　［４］　光透過異方性層と光吸収異方性層との間に、入射した直線偏光の偏光方向を８０～１００°の範囲で回転させる偏光制御層を有する、［１］～［３］のいずれかに記載の面状照明装置。
　［５］　偏光制御層が、厚さ方向に沿って伸びる螺旋軸に沿って捩れ配向した液晶化合物を含む層である、［４］に記載の面状照明装置。
　［６］　偏光制御層が、１／２波長板である、［４］に記載の面状照明装置。
　［７］　［１］～［６］のいずれかに記載の面状照明装置を有する画像表示装置。
　［８］　層の表面に対して垂直な透過率中心軸を有する光吸収異方性層と、
　下記の要件１および要件２を満たす光透過異方性層と、を有する光学フィルム。
　要件１：光透過異方性層の法線方向から波長５５０ｎｍの光を入射した際における透過率をＴ０、光透過異方性層の法線に対して極角５０°の方向から波長５５０ｎｍの光を入射した際における透過率をＴ５０とした際に、Ｔ０＞Ｔ５０の関係、および、Ｔ５０＜７０％の関係を満たす。
　要件２：光透過異方性層の法線方向から波長５５０ｎｍの光を入射した際における吸光度をＡ０、光透過異方性層の法線に対して極角５０°の方向から波長５５０ｎｍの光を入射した際における吸光度をＡ５０とした際に、Ａ０＜０．０５の関係、および、Ａ５０＜０．０５の関係を満たす。
　［９］　光透過異方性層と光吸収異方性層との間に、入射した直線偏光の偏光方向を８０～１００°の範囲で回転させる偏光制御層を有する、［８］に記載の光学フィルム。 In order to achieve such an object, the present invention has the following configurations.
[1] having an anisotropic light absorption layer, an anisotropic light transmission layer, a light diffusion layer, a light source, and a reflective layer in this order;
The light absorption anisotropic layer has a transmittance center axis perpendicular to the surface of the layer,
A planar lighting device, wherein the light transmission anisotropic layer satisfies requirements 1 and 2 below.
Requirement 1: The transmittance when light with a wavelength of 550 nm is incident from the normal direction of the anisotropic light transmission layer is T0, and the wavelength of 550 nm It satisfies the relationship of T0>T50 and the relationship of T50<70%, where T50 is the transmittance when light is incident.
Requirement 2: A0 absorbance when light with a wavelength of 550 nm is incident from the normal direction of the anisotropic light transmission layer, light with a wavelength of 550 nm from the direction of a polar angle of 50 ° with respect to the normal line of the anisotropic light transmission layer When A50 is the absorbance at the time of incidence, the relationship of A0<0.05 and the relationship of A50<0.05 are satisfied.
[2] R0 is the reflectance when light with a wavelength of 550 nm is incident from the normal direction of the anisotropic light transmission layer; When the reflectance at the time of incident light is R50,
The planar lighting device according to [1], wherein the anisotropic light transmission layer satisfies the relationship of R0<R50 and the relationship of R50>30%.
[3] The planar lighting device according to [1] or [2], wherein the anisotropic light transmission layer is a multilayer film in which 50 or more different layers are laminated.
[4] [1] to [3] having a polarization control layer between the anisotropic light transmission layer and the anisotropic light absorption layer that rotates the polarization direction of incident linearly polarized light within the range of 80 to 100° ] The planar illumination device according to any one of
[5] The planar illumination device according to [4], wherein the polarization control layer is a layer containing a liquid crystal compound twisted along a helical axis extending along the thickness direction.
[6] The planar illumination device of [4], wherein the polarization control layer is a half-wave plate.
[7] An image display device comprising the planar lighting device according to any one of [1] to [6].
[8] a light absorption anisotropic layer having a transmittance central axis perpendicular to the surface of the layer;
An optical film having a light transmission anisotropic layer that satisfies requirements 1 and 2 below.
Requirement 1: The transmittance when light with a wavelength of 550 nm is incident from the normal direction of the anisotropic light transmission layer is T0, and the wavelength of 550 nm It satisfies the relationship of T0>T50 and the relationship of T50<70%, where T50 is the transmittance when light is incident.
Requirement 2: A0 absorbance when light with a wavelength of 550 nm is incident from the normal direction of the anisotropic light transmission layer, light with a wavelength of 550 nm from the direction of a polar angle of 50 ° with respect to the normal line of the anisotropic light transmission layer When A50 is the absorbance at the time of incidence, the relationship of A0<0.05 and the relationship of A50<0.05 are satisfied.
[9] The structure according to [8], which has a polarization control layer between the anisotropic light transmission layer and the anisotropic light absorption layer that rotates the polarization direction of incident linearly polarized light within a range of 80 to 100°. optical film.
　本発明によれば、正面輝度が高く、かつ、平行光源性にも優れる面状照明装置、この面状照明装置を用いる、高画質な画像表示が可能な画像表示装置、および、この面状照明装置に好適な光学フィルムが提供される。 According to the present invention, a planar illumination device having high front luminance and excellent parallel light source properties, an image display device capable of displaying high-quality images using the planar illumination device, and the planar illumination device Optical films suitable for devices are provided.
図１は、本発明の面状照明装置をバックライト装置に利用した一例を概念的に示す図である。FIG. 1 is a diagram conceptually showing an example in which the planar illumination device of the present invention is used in a backlight device. 図２は、本発明の面状照明装置をバックライト装置に利用した別の例を概念的に示す図である。FIG. 2 is a diagram conceptually showing another example in which the planar lighting device of the present invention is used in a backlight device. 図３は、一般的な層による光の反射率を概念的に示す図である。FIG. 3 is a diagram conceptually showing the reflectance of light by a general layer. 図４は、光透過異方性層による光の反射率を概念的に示す図である。FIG. 4 is a diagram conceptually showing the light reflectance of the anisotropic light transmission layer. 図５は、光透過異方性層の別の例を概念的に示す図である。FIG. 5 is a diagram conceptually showing another example of the light transmission anisotropic layer.
　以下、本発明の面状照明装置、画像表示装置および光学フィルムについて、詳細に説明する。
　以下の説明は、本発明の代表的な実施態様に基づいてなされるものであるが、本発明は、このような実施態様に限定されるものではない。
　また、以下に示す図は、いずれも、本発明を説明するための概念的な図である。従って、各図において、各部材の形状、大きさ、厚さ、ならびに、配置位置および間隔などの位置関係等は、必ずしも実際の装置とは一致しない。
　なお、本明細書において、「～」を用いて表される数値範囲は、「～」の前後に記載される数値を下限値および上限値として含む範囲を意味する。 The planar lighting device, image display device and optical film of the present invention will be described in detail below.
The following description is based on representative embodiments of the invention, but the invention is not limited to such embodiments.
Also, all of the drawings shown below are conceptual diagrams for explaining the present invention. Therefore, in each drawing, the shape, size, thickness, and positional relationship such as arrangement position and spacing of each member do not necessarily match the actual device.
In this specification, a numerical range represented by "-" means a range including the numerical values before and after "-" as lower and upper limits.
　図１に、本発明の面状照明装置を液晶表示装置等のバックライト装置に利用した一例を概念的に示す。
　なお、本発明の面状照明装置は、液晶表示装置等のバックライト装置に制限はされず、各種の照明用途に利用可能である。例えば、本発明の面状照明装置は、天井および壁等に貼着または埋め込まれる屋内照明、屋外の環境照明、各種の検査用照明、シャーカステン、ならびに、ライトテーブルなど、面状の照明（面照明）を行う各種の用途に利用可能である。ここで、本発明の面状照明装置は、後述するように、正面輝度が高く、かつ、平行光源性にも優れるので、図示例のような、液晶表示装置等のバックライト装置には、特に好適に利用される。
　図１に示すバックライト装置１０は、本発明の面状照明装置を利用するもので、反射層１２と、光源１４と、光拡散層１６と、光透過異方性層１８と、光吸収異方性層２０とを有する。
　バックライト装置１０からの光出射側、すなわち、図中上方には、例えば液晶表示装置を構成する液晶パネルが配置される。また、光源１４は、反射層１２の図中上面に、二次元的に配列される。従って、バックライト装置１０は、光出射側から、光吸収異方性層２０、光透過異方性層１８、光拡散層１６、光源１４および反射層１２が、この順番で配列される。 FIG. 1 conceptually shows an example in which the planar illumination device of the present invention is applied to a backlight device such as a liquid crystal display device.
The planar illumination device of the present invention is not limited to backlight devices such as liquid crystal display devices, and can be used for various lighting applications. For example, the planar lighting device of the present invention can be used for indoor lighting attached or embedded in ceilings, walls, etc., outdoor environmental lighting, various inspection lighting, Schaukasten, light tables, and planar lighting (flat lighting). ) can be used for various purposes. Here, as will be described later, the planar illumination device of the present invention has high front luminance and excellent parallel light source properties. It is preferably used.
The backlight device 10 shown in FIG. 1 utilizes the planar lighting device of the present invention, and includes a reflective layer 12, a light source 14, a light diffusion layer 16, an anisotropic light transmission layer 18, and a light absorption different layer. and an anisotropic layer 20 .
A liquid crystal panel constituting, for example, a liquid crystal display device is arranged on the light emitting side from the backlight device 10, that is, on the upper side in the figure. The light sources 14 are two-dimensionally arranged on the upper surface of the reflective layer 12 in the figure. Therefore, in the backlight device 10, the anisotropic light absorption layer 20, the anisotropic light transmission layer 18, the light diffusion layer 16, the light source 14, and the reflection layer 12 are arranged in this order from the light emission side.
　なお、バックライト装置１０すなわち本発明の面状照明装置は、必要に応じて、光源１４から光吸収異方性層２０までに至る各層（各部材）の間に、後述する偏光制御層２６以外の層（部材）を有してもよい。
　また、バックライト装置１０すなわち本発明の面状照明装置は、必要に応じて、光透過異方性層１８よりも光出射側に、出射する光の色味をニュートラルにするために、色素化合物等を含有する色味調整層を設けてもよい。 In the backlight device 10, that is, the planar lighting device of the present invention, if necessary, between the layers (each member) from the light source 14 to the light absorption anisotropic layer 20, other than the polarization control layer 26 described later, You may have a layer (member) of
In addition, the backlight device 10, that is, the planar lighting device of the present invention, may optionally include a dye compound on the light emitting side of the light transmission anisotropic layer 18 in order to make the emitted light color neutral. and the like may be provided.
　バックライト装置１０すなわち本発明の面状照明装置（光学フィルム）において、光透過異方性層１８と光吸収異方性層２０とは、積層されてもよく、あるいは、離間していてもよい。また、光拡散層１６も、光透過異方性層１８に積層されても、離間していてもよい。
　すなわち、本発明の面状照明装置において、光拡散層１６から光吸収異方性層２０に至る各層（各部材）の積層状態には、制限はなく、任意の構成が、各種、利用可能である。しかしながら、バックライト装置１０等の薄型化を図れる等の点で、積層が可能な部材は、光学特性に影響を与えない範囲で積層するのが好ましい。
　なお、積層した層は、ＯＣＡ（Optical Clear Adhesive）等で貼着してもよく、枠体、治具およびクリップ等を用いて一体化してもよい。
　以上の点に関しては、後述する偏光制御層２６を有する構成も同様である。 In the backlight device 10, that is, the planar lighting device (optical film) of the present invention, the anisotropic light transmission layer 18 and the anisotropic light absorption layer 20 may be laminated or separated. . Also, the light diffusion layer 16 may be laminated on the light transmission anisotropic layer 18 or may be separated therefrom.
In other words, in the planar illumination device of the present invention, there is no limitation on the lamination state of each layer (each member) from the light diffusion layer 16 to the light absorption anisotropic layer 20, and various arbitrary configurations can be used. be. However, in order to reduce the thickness of the backlight device 10, etc., it is preferable to laminate members that can be laminated within a range that does not affect optical characteristics.
The laminated layers may be adhered with OCA (Optical Clear Adhesive) or the like, or may be integrated using a frame, a jig, a clip, or the like.
The above points are the same for the configuration having the polarization control layer 26, which will be described later.
　バックライト装置１０において、光源１４は、いわゆる直下型のバックライト装置で利用されている公知の光源（発光素子）が、各種、利用可能である。
　光源１４としては、ＬＥＤ（Light Emitting Diode）、有機ＥＬ（Electro Luminescence）、および、蛍光灯等が例示される。
　また、バックライト装置１０の光源１４としては、青色ＬＥＤと、青色光の入射によって赤色光および緑色光の蛍光を発する量子ドット層との組み合わせなど、発光素子と波長変換材料（蛍光材料）からなる層との組み合わせも、利用可能である。
　光源１４は、白色光源でもよく、あるいは、赤色光源、緑色光源および青色光源を組み合わせることで、全体として白色光を出射するものであってもよい。 As the light source 14 in the backlight device 10, various known light sources (light emitting elements) used in so-called direct type backlight devices can be used.
Examples of the light source 14 include an LED (Light Emitting Diode), an organic EL (Electro Luminescence), a fluorescent lamp, and the like.
In addition, the light source 14 of the backlight device 10 is composed of a light-emitting element and a wavelength conversion material (fluorescent material), such as a combination of a blue LED and a quantum dot layer that emits fluorescence of red light and green light when blue light is incident. Combinations with layers are also available.
The light source 14 may be a white light source, or may emit white light as a whole by combining a red light source, a green light source, and a blue light source.
　図示例のバックライト装置１０において、光源１４は、反射層１２の上（光反射面）に、二次元的に配置される。
　光源１４の配置は、液晶表示装置に用いられる一般的な直下型のバックライト装置と同様でよい。従って、光源１４の配置は、規則的でも、不規則でもよいが、通常は、規則的である。また、光源１４の配置密度は、反射層１２の面方向に、均一でも、配置密度の変動があってもよい。 In the illustrated backlight device 10 , the light source 14 is two-dimensionally arranged on the reflective layer 12 (light reflecting surface).
The arrangement of the light source 14 may be the same as that of a general direct type backlight device used in a liquid crystal display device. Therefore, the arrangement of the light sources 14 may be regular or irregular, but is usually regular. Also, the arrangement density of the light sources 14 may be uniform in the surface direction of the reflective layer 12, or may vary.
　反射層１２も、液晶表示装置等に用いられるバックライト装置で用いられる公知のものが、各種、利用可能である。一例として、アルミニウム板などの金属板、および、アルミニウムの蒸着層などの反射層を形成した板材等が例示される。
　また、反射層１２の反射特性は、鏡面反射性でも、拡散反射性でもよい。 As the reflective layer 12, various known materials used in backlight devices used in liquid crystal display devices and the like can be used. Examples include a metal plate such as an aluminum plate, and a plate material on which a reflective layer such as an aluminum deposition layer is formed.
Moreover, the reflection characteristics of the reflective layer 12 may be either specular reflection or diffuse reflection.
　なお、バックライト装置すなわち本発明の面状照明装置は、直下型に制限はされない。すなわち、本発明の面状照明装置において、光源は、導光板と、導光板の端面から光を入射する、線状の発光素子、または、導光板の端面の方向に配列した点状の発光素子とを用いる、いわゆるエッジライト型（サイドライト型）の光源も、利用可能である。
　本発明の面状照明装置において、エッジライト型の光源を用いる場合には、導光板の光出射面とは逆側に、反射層を設ける。この際において、反射層は、導光板に当接しても、導光板と離間してもよい。また、光源も、上述した光源１４と同様、公知の各種の物が利用可能である。 The backlight device, that is, the planar lighting device of the present invention is not limited to the direct type. That is, in the planar illumination device of the present invention, the light source includes a light guide plate and linear light emitting elements that receive light from the end face of the light guide plate, or dotted light emitting devices arranged in the direction of the end face of the light guide plate. A so-called edge-light type (side-light type) light source is also available.
In the planar illumination device of the present invention, when an edge light type light source is used, a reflective layer is provided on the opposite side of the light guide plate to the light exit surface. At this time, the reflective layer may be in contact with the light guide plate or may be separated from the light guide plate. Also, as for the light source, as with the light source 14 described above, various known ones can be used.
　光源１４の下流側には、光拡散層１６が配置される。なお、本発明において、下流側とは、光源１４が出射し、光拡散層１６から光吸収異方性層２０に至る光の進行方向における下流側である。
　光拡散層１６も、液晶表示装置のバックライト装置で用いられる公知のものが、各種、利用可能である。
　一例として、くもりガラス、サンドブラスト処理等の粗面化処理を施した透明板、ならびに、ポリスチレン、ポリカーボネート、アクリル樹脂およびメチルメタクリレート・スチレン共重合などの樹脂製のベースフィルムに、シリコーン系およびアクリル系などの拡散ビーズを拡散させたフィルム等の光拡散板（光拡散フィルム、光拡散シート）が例示される。 A light diffusion layer 16 is arranged downstream of the light source 14 . In the present invention, the downstream side is the downstream side in the traveling direction of light emitted from the light source 14 and extending from the light diffusion layer 16 to the light absorption anisotropic layer 20 .
For the light diffusion layer 16, various known materials used in backlight devices for liquid crystal display devices can be used.
Examples include frosted glass, transparent plates that have undergone surface roughening such as sandblasting, and resin base films such as polystyrene, polycarbonate, acrylic resin, and methyl methacrylate/styrene copolymer, with silicone and acrylic base films. A light diffusion plate (light diffusion film, light diffusion sheet) such as a film in which diffusion beads are diffused is exemplified.
　また、光拡散層１６としては、プリズムシートも利用可能である。光拡散層１６としてプリズムシートを用いる際には、１枚でもよいが、稜線を直交して配置した２枚のプリズムシートを用いるのが好ましい。
　さらに、光拡散層１６は、上述した光拡散板の１以上と、プリズムシートとの組み合わせも、利用可能である。 A prism sheet can also be used as the light diffusion layer 16 . When a prism sheet is used as the light diffusing layer 16, one prism sheet may be used, but it is preferable to use two prism sheets whose ridge lines are perpendicular to each other.
Furthermore, the light diffusion layer 16 can also be a combination of one or more of the light diffusion plates described above and a prism sheet.
　光拡散層１６の下流には、光透過異方性層１８が配置される。
　バックライト装置１０すなわち本発明の面状照明装置において、光透過異方性層１８は、光の透過に異方性を有するものである。具体的には、光透過異方性層１８は、正面から入射した光、すなわち、光透過異方性層１８の法線方向から入射した光は、そのまま透過させる。これに対して、斜め方向から入射した光、すなわち、光透過異方性層１８の法線に対して角度を有して入射した光は、そのまま透過させずに、例えば、反射または拡散する。
　なお、法線方向とは、層（フィルム、シート状物、板状物）の表面に対して直交する方向である。また、法線とは、層の表面と直交する線である。
　また、光透過異方性層１８は、入射した光の吸収率が、非常に低い。 A light transmission anisotropic layer 18 is arranged downstream of the light diffusion layer 16 .
In the backlight device 10, that is, the planar illumination device of the present invention, the light transmission anisotropic layer 18 has anisotropy in light transmission. Specifically, the anisotropic light transmission layer 18 transmits light incident from the front, that is, light incident from the normal direction of the anisotropic light transmission layer 18 as it is. On the other hand, light incident from an oblique direction, that is, light incident at an angle with respect to the normal to the light transmission anisotropic layer 18 is not transmitted as it is, but is reflected or diffused, for example.
The normal direction is a direction orthogonal to the surface of a layer (film, sheet-like object, plate-like object). A normal line is a line perpendicular to the surface of the layer.
In addition, the light transmission anisotropic layer 18 has a very low absorption rate of incident light.
　具体的には、バックライト装置１０すなわち本発明の面状照明装置において、光透過異方性層１８は、要件１として、法線方向から波長５５０ｎｍの光を入射した際における透過率をＴ０、法線に対して極角５０°の方向から波長５５０ｎｍの光を入射した際における透過率をＴ５０とした際に、Ｔ０＞Ｔ５０の関係、および、Ｔ５０＜７０％の関係を満たす。
　また、光透過異方性層１８は、この要件１を満たした上で、さらに、要件２として、法線方向から波長５５０ｎｍの光を入射した際における吸光度をＡ０、法線に対して極角５０°の方向から波長５５０ｎｍの光を入射した際における吸光度をＡ５０とした際に、Ａ０＜０．０５の関係、および、Ａ５０＜０．０５の関係を満たす。 Specifically, in the backlight device 10, that is, the planar lighting device of the present invention, the light transmission anisotropic layer 18 has, as Requirement 1, a transmittance of T0 when light with a wavelength of 550 nm is incident from the normal direction. When the transmittance of light having a wavelength of 550 nm is incident from the direction of a polar angle of 50° with respect to the normal, T50, the relationship of T0>T50 and the relationship of T50<70% are satisfied.
In addition, the light transmission anisotropic layer 18 satisfies this requirement 1, and furthermore, as requirement 2, the absorbance when light with a wavelength of 550 nm is incident from the normal direction is A0, and the polar angle with respect to the normal is The relationship A0<0.05 and the relationship A50<0.05 are satisfied, where A50 is the absorbance when light with a wavelength of 550 nm is incident from the direction of 50°.
　図示例のバックライト装置１０において、光透過異方性層１８は、好ましい態様として、上述した要件１および要件２を満たした上で、斜め方向から入射した光を、高い反射率で反射する。具体的には、光透過異方性層１８は、好ましい態様として、法線方向から波長５５０ｎｍの光を入射した際における反射率をＲ０、法線に対して極角５０°の方向から波長５５０ｎｍの光を入射した際における反射率をＲ５０とした際に、Ｒ０＜Ｒ５０の関係、および、Ｒ５０＞３０％の関係を満たす。
　なお、後に詳述するが、本発明の面状照明装置において、光透過異方性層の別の例は、斜め方向から入射した光を、反射するのではなく、拡散する。 In the illustrated backlight device 10, the anisotropic light transmission layer 18 preferably satisfies the requirements 1 and 2 described above, and reflects obliquely incident light with high reflectance. Specifically, as a preferred embodiment, the anisotropic light transmission layer 18 has a reflectance of R0 when light with a wavelength of 550 nm is incident from the normal direction, and a wavelength of 550 nm from a direction with a polar angle of 50° to the normal. When R50 is the reflectance at the time of incident light, the relationship of R0<R50 and the relationship of R50>30% are satisfied.
As will be described in detail later, in the planar illumination device of the present invention, another example of the light transmission anisotropic layer diffuses the light that is incident obliquely rather than reflecting it.
　本発明において、光透過異方性層１８の透過率、反射率および吸光度は、ゴニオフォトメーター、偏光フィルム測定装置、および、分光光度計等を用いて、公知の方法で測定すればよい。光透過異方性層１８の透過率、反射率および吸光度の測定方法としては、一例として、後述する実施例で示す方法が例示される。 In the present invention, the transmittance, reflectance and absorbance of the light transmission anisotropic layer 18 may be measured by known methods using a goniophotometer, a polarizing film measuring device, a spectrophotometer and the like. As an example of a method for measuring the transmittance, reflectance and absorbance of the anisotropic light transmission layer 18, the methods described later in Examples are exemplified.
　すなわち、図示例のバックライト装置１０において、光透過異方性層１８は、法線方向すなわち正面から入射した光は、吸収せず、かつ、反射せずに、高い透過率で透過する。これに対して、光透過異方性層１８は、法線に対して極角５０°の方向のように、斜め方向から入射した光は、透過せず、かつ、吸収せずに、好ましい態様として、高い反射率で反射する。
　バックライト装置１０すなわち本発明の面状照明装置は、このような光透過異方性層１８と、後述する光吸収異方性層２０とを有することにより、正面輝度が高く、かつ、平行光源性に優れる面状照明装置を実現している。この点に関しては、後に詳述する。 That is, in the illustrated backlight device 10, the anisotropic light transmission layer 18 does not absorb or reflect light incident in the normal direction, that is, from the front, but transmits the light with high transmittance. On the other hand, the anisotropic light transmission layer 18 does not transmit or absorb light incident from an oblique direction, such as a direction with a polar angle of 50° with respect to the normal line. As such, it reflects with high reflectance.
The backlight device 10, i.e., the planar lighting device of the present invention, has such an anisotropic light transmission layer 18 and an anisotropic light absorption layer 20, which will be described later. It realizes a planar lighting device with excellent performance. This point will be described in detail later.
　光透過異方性層１８において、法線方向から入射した波長５５０ｎｍの光の透過率Ｔ０は、法線に対して極角５０°の方向から入射した波長５５０ｎｍの光の透過率Ｔ５０よりも高い。透過率Ｔ０が透過率Ｔ５０以下では、十分な正面輝度および平行光源性を得られない等の点で不都合を生じる。
　透過率Ｔ０は、透過率Ｔ５０よりも高ければよいが、高いほど好ましい。透過率Ｔ０は、１０％以上が好ましく、２５％以上がより好ましく、４０％以上がさらに好ましい。
　透過率Ｔ０を、１０％以上とすることにより、正面輝度を向上できる、平行光源性を向上できる等の点で好ましい。 In the anisotropic light transmission layer 18, the transmittance T0 of light with a wavelength of 550 nm that is incident from the normal direction is higher than the transmittance T50 of light with a wavelength of 550 nm that is incident from the direction of a 50° polar angle with respect to the normal. . If the transmittance T0 is equal to or less than the transmittance T50, problems arise in that sufficient front luminance and parallel light source properties cannot be obtained.
The transmittance T0 should be higher than the transmittance T50, but the higher the better. The transmittance T0 is preferably 10% or more, more preferably 25% or more, and even more preferably 40% or more.
A transmittance T0 of 10% or more is preferable in that the front luminance can be improved and the parallel light source property can be improved.
　光透過異方性層１８において、法線に対して極角５０°の方向から入射した波長５５０ｎｍの光の透過率Ｔ５０は、７０％未満である。
　透過率Ｔ５０が７０％以上では、十分な正面輝度および平行光源性を得られない等の点で不都合を生じる。
　透過率Ｔ５０は、低いほど好ましい。透過率Ｔ５０は、５０％未満が好ましく、３５％未満がより好ましい。 The anisotropic light transmission layer 18 has a transmittance T50 of less than 70% for light with a wavelength of 550 nm incident from a direction with a polar angle of 50° with respect to the normal.
If the transmittance T50 is 70% or more, problems arise in that sufficient front luminance and parallel light source properties cannot be obtained.
The transmittance T50 is preferably as low as possible. The transmittance T50 is preferably less than 50%, more preferably less than 35%.
　光透過異方性層１８において、法線方向から波長５５０ｎｍの光を入射した際における吸光度Ａ０、および、法線に対して極角５０°の方向から波長５５０ｎｍの光を入射した際における吸光度Ａ５０は、共に、０．０５未満である。
　吸光度Ａ０および吸光度Ａ５０が０．０５以上では、光の利用効率が低く十分な正面輝度が得られない等の点で不都合を生じる。
　吸光度Ａ０および吸光度Ａ５０は、低いほど好ましい。吸光度Ａ０および吸光度Ａ５０は、０．０２未満が好ましく、０．０１未満がより好ましい。 In the anisotropic light transmission layer 18, the absorbance A0 when light with a wavelength of 550 nm is incident from the normal direction, and the absorbance A50 when light with a wavelength of 550 nm is incident from the direction of a 50° polar angle with respect to the normal. are both less than 0.05.
If the absorbance A0 and the absorbance A50 are 0.05 or more, the efficiency of light utilization is low and sufficient front luminance cannot be obtained.
Absorbance A0 and absorbance A50 are preferably as low as possible. Absorbance A0 and absorbance A50 are preferably less than 0.02, more preferably less than 0.01.
　図示例の光透過異方性層１８は、好ましい態様として、法線方向から入射した波長５５０ｎｍの光の反射率Ｒ０、法線に対して極角５０°の方向から入射した波長５５０ｎｍの光の反射率Ｒ５０が、Ｒ０＜Ｒ５０、および、Ｒ５０＞３０％を満たす。
　反射率Ｒ０を反射率Ｒ５０よりも低くすることにより、正面輝度を向上できる、平行光源性を向上できる等の点で好ましい。 The light transmission anisotropic layer 18 in the illustrated example preferably has a reflectance R0 for light with a wavelength of 550 nm incident from the normal direction, The reflectance R50 satisfies R0<R50 and R50>30%.
By making the reflectance R0 lower than the reflectance R50, it is preferable in that the front luminance can be improved, the parallel light source property can be improved, and the like.
　反射率Ｒ５０を３０％超とすることにより、正面輝度を向上できる、平行光源性を向上できる等の点で好ましい。反射率Ｒ５０は、高いほど好ましく、５０％超がより好ましく、６５％超がさらに好ましい。
　他方、反射率Ｒ０は、低いほど好ましい。反射率Ｒ０は、１０％未満が好ましく、７％未満がより好ましく、４％未満がさらに好ましい。
　反射率Ｒ０を、１０％未満とすることにより、正面輝度を向上できる、平行光源性を向上できる等の点で好ましい。 A reflectance R50 of more than 30% is preferable in that front luminance can be improved and parallel light source properties can be improved. The reflectance R50 is preferably as high as possible, more preferably over 50%, and even more preferably over 65%.
On the other hand, the reflectance R0 is preferably as low as possible. The reflectance R0 is preferably less than 10%, more preferably less than 7%, even more preferably less than 4%.
A reflectance R0 of less than 10% is preferable in that the front luminance can be improved and parallel light source properties can be improved.
　このような光透過異方性層は、透過率Ｔ０が透過率Ｔ５０よりも大きく、かつ、透過率Ｔ５０が７０％未満であり、さらに、吸光度Ａ０および吸光度Ａ５０が０．０５未満であれば、公知の各種の物が利用可能である。
　一例として、国際公開第２００９／１９８６３５号に記載される、異なる複数の熱可塑性樹脂が５０層以上積層されており、法線方向から入射する光の透過率が５０％以上で、法線に対して２０°、４０°および７０°の角度で入射したときの、それぞれのＰ波の反射率［％］をＲ２０、Ｒ４０およびＲ７０とした際に、Ｒ２０≦Ｒ４０＜Ｒ７０の関係を満たし、かつ、反射率Ｒ７０が３０％以上であり、法線に対して７０°の角度で入射したときのＰ波の反射光の彩度が２０以下である、積層フィルムが例示される。なお、法線および法線方向とは、いずれも、フィルム面の法線および法線方向である。 In such an anisotropic light transmission layer, if the transmittance T0 is greater than the transmittance T50 and the transmittance T50 is less than 70%, and the absorbance A0 and the absorbance A50 are less than 0.05, Various known products are available.
As an example, a plurality of different thermoplastic resins described in International Publication No. 2009/198635 are laminated with 50 or more layers, and the transmittance of light incident from the normal direction is 50% or more, R20, R40, and R70 are the reflectances [%] of the P waves when incident at angles of 20°, 40°, and 70°, respectively, satisfying the relationship R20≦R40<R70, and A laminate film having a reflectance R70 of 30% or more and a chroma of 20 or less of the reflected light of the P wave when incident at an angle of 70° with respect to the normal is exemplified. The normal and the normal direction are both the normal and the normal direction of the film surface.
　光透過異方性層１８の下流には、光吸収異方性層２０が配置される。
　光吸収異方性層２０は、透過率中心軸が層の表面に対して垂直な層である。なお、本発明において、『透過率中心軸が層の表面に対して垂直』とは、層の表面に対して完全な垂直のみならず、層の表面に垂直な方向に対して、±５°の角度範囲を含む。
　本発明の光学フィルムは、上述した光透過異方性層１８と、この光吸収異方性層２０とを含むものである。 An anisotropic light absorption layer 20 is arranged downstream of the anisotropic light transmission layer 18 .
The light absorption anisotropic layer 20 is a layer whose transmittance center axis is perpendicular to the surface of the layer. In addition, in the present invention, "the transmittance center axis is perpendicular to the surface of the layer" means not only the complete perpendicularity to the surface of the layer, but also the direction perpendicular to the surface of the layer. including the angular range of .
The optical film of the present invention includes the anisotropic light transmission layer 18 and the anisotropic light absorption layer 20 described above.
　本発明において、透過率中心軸とは、極角および方位角を、種々、変更して、層の表面から様々な方向に透過率を測定して、透過率が最も高かった方向である。
　従って、透過率中心軸が層の表面に対して垂直な光吸収異方性層２０は、法線方向すなわち正面から入射した光は、そのまま透過して、法線に対して傾斜する方法すなわち斜め方向から入射した光は、吸収する。 In the present invention, the transmittance central axis is the direction in which the transmittance is highest when the transmittance is measured in various directions from the surface of the layer by changing the polar angle and azimuth angle.
Therefore, the light absorption anisotropic layer 20 whose transmittance center axis is perpendicular to the surface of the layer transmits the light incident from the normal direction, that is, from the front as it is, and is inclined to the normal, that is, obliquely. Light incident from any direction is absorbed.
　光吸収異方性層２０は、透過率中心軸が層の表面に対して垂直な層が、各種、利用可能である。
　一例として、二色性物質を、層の表面に対して垂直（垂直±５°の範囲）に配向した層が例示される。 As the light absorption anisotropic layer 20, various layers whose transmittance central axis is perpendicular to the surface of the layer can be used.
An example is a layer in which a dichroic substance is oriented perpendicularly (within a range of ±5° perpendicularly) to the surface of the layer.
　本発明において、二色性物質とは、方向によって吸光度が異なる色素を意味する。二色性物質は、液晶性を示してもよいし、液晶性を示さなくてもよい。 In the present invention, a dichroic substance means a dye with different absorbance depending on the direction. The dichroic substance may or may not exhibit liquid crystallinity.
　二色性物質は、特に限定されず、可視光吸収物質（二色性色素）、発光物質（蛍光物質、燐光物質）、紫外線吸収物質、赤外線吸収物質、非線形光学物質、カーボンナノチューブ、および、無機物質（例えば量子ロッド）などが挙げられ、従来公知の二色性物質（二色性色素）を使用することができる。
　具体的には、例えば、特開２０１３－２２８７０６号公報の［００６７］～［００７１］段落、特開２０１３－２２７５３２号公報の［０００８］～［００２６］段落、特開２０１３－２０９３６７号公報の［０００８］～［００１５］段落、特開２０１３－１４８８３号公報の［００４５］～［００５８］段落、特開２０１３－１０９０９０号公報の［００１２］～［００２９］段落、特開２０１３－１０１３２８号公報の［０００９］～［００１７］段落、特開２０１３－３７３５３号公報の［００５１］～［００６５］段落、特開２０１２－６３３８７号公報の［００４９］～［００７３］段落、特開平１１－３０５０３６号公報の［００１６］～［００１８］段落、特開２００１－１３３６３０号公報の［０００９］～［００１１］段落、特開２０１１－２１５３３７号公報の［００３０］～［０１６９］、特開２０１０－１０６２４２号公報の［００２１］～［００７５］段落、特開２０１０－２１５８４６号公報の［００１１］～［００２５］段落、特開２０１１－０４８３１１号公報の［００１７］～［００６９］段落、特開２０１１－２１３６１０号公報の［００１３］～［０１３３］段落、特開２０１１－２３７５１３号公報の［００７４］～［０２４６］段落、特開２０１６－００６５０２号公報の［０００５］～［００５１］段落、特開２０１８-０５３１６７号公報［００１４］～［００３２］段落、特開２０２０－１１７１６号公報の［００１４］～［００３３］段落、国際公開第２０１６／０６０１７３号公報の［０００５］～［００４１］段落、国際公開第２０１６／１３６５６１号公報の［０００８］～［００６２］段落、国際公開第２０１７／１５４８３５号の［００１４］～［００３３］段落、国際公開第２０１７／１５４６９５号の［００１４］～［００３３］段落、国際公開第２０１７／１９５８３３号の［００１３］～［００３７］段落、国際公開第２０１８／１６４２５２号の［００１４］～［００３４］段落、国際公開第２０１８／１８６５０３号の［００２１］～［００３０］段落、国際公開第２０１９／１８９３４５号の［００４３］～［００６３］段落、国際公開第２０１９／２２５４６８号の［００４３］～［００８５］段落、国際公開第２０２０／００４１０６号の［００５０］～［００７４］段落、および、国際公開第２０２１／０４４８４３号の［００１５］～［００３８］段落などに記載されたものが挙げられる。 The dichroic substance is not particularly limited, and includes visible light absorbing substances (dichroic dyes), luminescent substances (fluorescent substances, phosphorescent substances), ultraviolet absorbing substances, infrared absorbing substances, nonlinear optical substances, carbon nanotubes, and inorganic Substances (for example, quantum rods) and the like can be mentioned, and conventionally known dichroic substances (dichroic dyes) can be used.
Specifically, for example, [ 0008] to [0015] paragraphs, [0045] to [0058] paragraphs of JP-A-2013-14883, [0012]-[0029] paragraphs of JP-A-2013-109090, JP-A-2013-101328 [0009] to [0017] paragraphs, [0051] to [0065] paragraphs of JP-A-2013-37353, [0049] to [0073] paragraphs of JP-A-2012-63387, JP-A-11-305036 [0016] to [0018] paragraphs, [0009] to [0011] paragraphs of JP-A-2001-133630, [0030]-[0169] of JP-A-2011-215337, JP-A-2010-106242 [0021] ~ [0075] paragraph, JP 2010-215846 [0011] ~ [0025] paragraph, JP 2011-048311 [0017] ~ [0069] paragraph, JP 2011-213610 [0013] to [0133] paragraphs of the publication, [0074] to [0246] paragraphs of JP-A-2011-237513, [0005] to [0051] paragraphs of JP-A-2016-006502, JP-A-2018-053167 [0014] to [0032] paragraphs, [0014] to [0033] paragraphs of JP-A-2020-11716, [0005] to [0041] paragraphs of International Publication No. 2016/060173, International Publication No. 2016 / 136561 [0008] to [0062] paragraphs, WO 2017/154835 [0014] to [0033] paragraphs, WO 2017/154695 [0014] to [0033] paragraphs, international publication [0013] to [0037] paragraphs of No. 2017/195833, [0014] to [0034] paragraphs of WO 2018/164252, [0021] to [0030] paragraphs of WO 2018/186503, International [0043] to [0063] paragraphs of Publication No. 2019/189345, [0043] to [0085] paragraphs of WO2019/225468, [0050] to [0074] paragraphs of WO2020/004106, and [0015 of WO2021/044843 ] to [0038] paragraphs.
　本発明においては、２種以上の二色性物質を併用してもよい。一例として、光吸収異方性層２０を黒色に近づける観点から、波長３７０～５５０ｎｍの範囲に極大吸収波長を有する少なくとも１種の二色性物質と、波長５００～７００ｎｍの範囲に極大吸収波長を有する少なくとも１種の二色性物質とを併用することが好ましい。 In the present invention, two or more dichroic substances may be used together. As an example, from the viewpoint of making the light absorption anisotropic layer 20 closer to black, at least one dichroic substance having a maximum absorption wavelength in the wavelength range of 370 to 550 nm and a maximum absorption wavelength in the wavelength range of 500 to 700 nm are used. It is preferable to use together with at least one kind of dichroic substance having.
　光吸収異方性層２０の形成方法は特に限定されないが、二色性物質を高い配向度で配向させる観点から、上述した二色性物質とともに液晶化合物を含有する液晶組成物を用いて形成する方法が好適に挙げられる。
　本発明においては、液晶化合物は、二色性を示さない液晶化合物である。
　液晶化合物としては、低分子液晶化合物および高分子液晶化合物のいずれも用いることができるが、高配向度を得るうえで、高分子液晶化合物がより好ましい。ここで、「低分子液晶化合物」とは、化学構造中に繰り返し単位を有さない液晶化合物のことをいう。また、「高分子液晶化合物」とは、化学構造中に繰り返し単位を有する液晶化合物のことをいう。
　低分子液晶化合物としては、例えば、特開２０１３－２２８７０６号公報に記載されている液晶化合物が挙げられる。
　高分子液晶化合物としては、例えば、特開２０１１－２３７５１３号公報に記載されているサーモトロピック液晶性高分子が挙げられる。また、高分子液晶化合物は、末端に架橋性基（例えば、アクリロイル基およびメタクリロイル基）を有していてもよい。
　液晶化合物は、１種単独で使用してもよいし、２種以上を併用してもよい。
　液晶化合物は、光吸収異方性層２０の配向度がより優れる点から、高分子液晶化合物を含むことが好ましい。
　また、液晶組成物は、溶媒、重合開始剤、界面改良剤、配向剤、および、これら以外の成分を含有していてもよい。 The method of forming the light absorption anisotropic layer 20 is not particularly limited, but from the viewpoint of aligning the dichroic substance with a high degree of orientation, it is formed using a liquid crystal composition containing a liquid crystal compound together with the dichroic substance described above. methods are preferred.
In the present invention, the liquid crystal compound is a liquid crystal compound that does not exhibit dichroism.
As the liquid crystal compound, both a low-molecular-weight liquid crystal compound and a high-molecular-weight liquid crystal compound can be used, but a high-molecular-weight liquid crystal compound is more preferable in order to obtain a high degree of alignment. Here, the term "low-molecular-weight liquid crystal compound" refers to a liquid crystal compound having no repeating unit in its chemical structure. Further, the term "polymeric liquid crystal compound" refers to a liquid crystal compound having a repeating unit in its chemical structure.
Low-molecular-weight liquid crystal compounds include, for example, liquid crystal compounds described in JP-A-2013-228706.
Examples of polymer liquid crystal compounds include thermotropic liquid crystal polymers described in JP-A-2011-237513. In addition, the polymer liquid crystal compound may have a crosslinkable group (for example, an acryloyl group and a methacryloyl group) at its terminal.
A liquid crystal compound may be used individually by 1 type, and may use 2 or more types together.
The liquid crystal compound preferably contains a polymer liquid crystal compound from the viewpoint that the degree of orientation of the light absorption anisotropic layer 20 is more excellent.
Moreover, the liquid crystal composition may contain a solvent, a polymerization initiator, an interface improver, an alignment agent, and components other than these.
　光吸収異方性層２０は、例えば、このような液晶組成物を用いる光吸収異方性層２０の形成では、まず、液晶組成物を液晶化合物の配向性を付与した配向膜に塗布する。次いで、液晶組成物の加熱および／または冷却を行い、あるいは、加熱および冷却を繰り返すことで、液晶化合物を厚さ方向に配向する。この液晶化合物の配向によって、二色性物質も、同様に、厚さ方向に配向する。
　その後、必要に応じて、紫外線の照射等を行って、液晶層生物を硬化することにより、二色性物質を厚さ方向に配向した光吸収異方性層２０を形成できる。 For the anisotropic light absorption layer 20, for example, in the formation of the anisotropic light absorption layer 20 using such a liquid crystal composition, the liquid crystal composition is first applied to an alignment film to which the liquid crystal compound is oriented. Next, the liquid crystal composition is heated and/or cooled, or the heating and cooling are repeated to align the liquid crystal compound in the thickness direction. Due to this orientation of the liquid crystal compound, the dichroic substance is similarly oriented in the thickness direction.
After that, if necessary, the liquid crystal layer is cured by irradiating with ultraviolet rays or the like, thereby forming the light absorption anisotropic layer 20 in which the dichroic substance is oriented in the thickness direction.
　以下、図１を参照して、バックライト装置１０の作用を説明することにより、本発明の面状照明装置について、より詳細に説明する。
　以下の説明では、便宜的に、法線方向すなわち正面からの光の入射を『正面入射』ともいう。また、法線に対して角度を有する方向すなわち斜め方向からの光の入射を『斜め入射』ともいう。 Hereinafter, the planar illumination device of the present invention will be described in more detail by describing the operation of the backlight device 10 with reference to FIG.
In the following description, for the sake of convenience, the incidence of light in the normal direction, that is, from the front is also referred to as "frontal incidence." In addition, incidence of light from a direction having an angle with respect to the normal, that is, from an oblique direction is also referred to as "oblique incidence".
　光源１４が出射した光（破線）は、まず、光拡散層１６によって拡散されて、次いで、光透過異方性層１８に入射する。 The light (dashed line) emitted by the light source 14 is first diffused by the light diffusion layer 16 and then enters the light transmission anisotropic layer 18 .
　上述のように、光透過異方性層１８は、正面入射した光は、そのまま透過し、斜め入射した光は、反射する。従って、光拡散層１６によって拡散された光のうち、光透過異方性層１８に正面入射した光は、そのまま透過して、光吸収異方性層２０に入射する。
　上述のように、光吸収異方性層２０は、正面入射した光は、そのまま透過し、斜め入射した光は吸収する。従って、光透過異方性層１８に正面入射して透過した光は、光吸収異方性層２０にも正面入射するので、多くの光が光吸収異方性層２０で吸収されずに、そのまま透過する。
　本発明の面状照明装置を液晶表示装置のバックライト装置に利用した場合には、光吸収異方性層２０を透過した光は、光吸収異方性層２０の下流に配置される例えば液晶パネルにも、正面入射する。 As described above, the anisotropic light-transmitting layer 18 transmits light incident from the front as it is, and reflects light incident at an oblique angle. Therefore, of the light diffused by the light diffusion layer 16 , the light incident on the anisotropic light transmission layer 18 is transmitted as it is and enters the anisotropic light absorption layer 20 .
As described above, the light-absorbing anisotropic layer 20 transmits front incident light as it is, and absorbs obliquely incident light. Therefore, the light that is frontally incident on and transmitted through the anisotropic light transmission layer 18 is also frontally incident on the anisotropic light absorption layer 20. Pass through as is.
When the planar illumination device of the present invention is used as a backlight device for a liquid crystal display device, the light transmitted through the light absorption anisotropic layer 20 is emitted from the light absorption anisotropic layer 20, such as a liquid crystal, arranged downstream of the light absorption anisotropic layer 20. The panel is also front-incident.
　一方、光拡散層１６によって拡散された光のうち、光透過異方性層１８に斜め入射した光は、光透過異方性層１８によって反射され、光拡散層１６に入射して拡散される。
　光透過異方性層１８側から光拡散層１６に入射して拡散された光は、反射層１２によって反射され、さらに、光拡散層１６に入射して拡散されて、再度、光透過異方性層１８に入射する。
　ここで、光拡散層１６に入射した光は、光拡散層１６による拡散によって、様々な方向に進行する。従って、再度、光透過異方性層１８に再入射した光の一部の光は、光透過異方性層１８に正面入射する。先と同様、光透過異方性層１８に正面入射した光は、そのまま透過して、光吸収異方性層２０に正面入射し、光吸収異方性層２０も、そのまま透過して、液晶パネルに正面入射する。
　他方、光透過異方性層１８に斜め入射した光は、先と同様に、光透過異方性層１８によって反射され、光拡散層１６で拡散され、反射層１２で反射され、光拡散層１６で拡散されて、先と同様に光透過異方性層１８に再入射する。 On the other hand, out of the light diffused by the light diffusion layer 16, the light obliquely incident on the light transmission anisotropic layer 18 is reflected by the light transmission anisotropic layer 18, enters the light diffusion layer 16, and is diffused. .
The light that enters the light diffusion layer 16 from the light transmission anisotropic layer 18 side and is diffused is reflected by the reflection layer 12, further enters the light diffusion layer 16 and is diffused, and is again anisotropic light transmission. incident on the magnetic layer 18 .
Here, the light incident on the light diffusion layer 16 travels in various directions due to diffusion by the light diffusion layer 16 . Therefore, part of the light re-entering the anisotropic light transmission layer 18 again enters the anisotropic light transmission layer 18 from the front. As before, the light incident on the anisotropic light transmission layer 18 from the front is transmitted as it is and enters the anisotropic light absorption layer 20 from the front. Frontal incidence on the panel.
On the other hand, the light obliquely incident on the light transmission anisotropic layer 18 is reflected by the light transmission anisotropic layer 18, diffused by the light diffusion layer 16, reflected by the reflection layer 12, and reflected by the light diffusion layer It is diffused at 16 and reenters the light transmission anisotropic layer 18 as before.
　以上のように、バックライト装置１０すなわち本発明の面状照明装置において、光透過異方性層１８に斜め入射した光は、光吸収異方性層２０による反射、光拡散層１６による拡散、反射層１２による反射、および、光拡散層１６による拡散を繰り返す。光は、この繰り返しの中で、光透過異方性層１８に正面入射する状態になった際に、光透過異方性層１８を透過して、さらに、光吸収異方性層２０に正面入射して透過して、液晶パネルに正面入射する。
　すなわち、本発明の面状照明装置では、正面入射した光は透過して斜め入射した光を反射する光透過異方性層１８と、正面入射した光は透過して斜め入射した光を吸収する光吸収異方性層２０とを有することにより、出射光を正面方向に集光できる。また、本発明の面状照明装置では、光透過異方性層１８による斜め入射した光の反射、および、光吸収異方性層２０による斜め入射した光の吸収によって、正面方向に出射する光に対して、斜め方向に出射する光の量を大幅に低減できる。
　その結果、本発明によれば、正面輝度すなわち正面方向に出射する光の輝度が高く、かつ、斜め方向に出射する光に比して正面方向に出射する光の量が多い、平行光源性に優れる面状照明装置を実現できる。 As described above, in the backlight device 10, that is, the planar illumination device of the present invention, the light obliquely incident on the light transmission anisotropic layer 18 is reflected by the light absorption anisotropic layer 20, diffused by the light diffusion layer 16, Reflection by the reflective layer 12 and diffusion by the light diffusion layer 16 are repeated. In this repetition, when the light reaches a state of frontal incidence on the light transmission anisotropic layer 18, the light passes through the light transmission anisotropic layer 18, and then passes through the light absorption anisotropic layer 20 frontally. After being incident and transmitted, the light enters the liquid crystal panel from the front.
That is, in the planar illumination device of the present invention, the light transmission anisotropic layer 18 transmits front incident light and reflects obliquely incident light, and the front incident light is transmitted and obliquely incident light is absorbed. By having the light absorption anisotropic layer 20, the emitted light can be focused in the front direction. Further, in the planar illumination device of the present invention, the obliquely incident light is reflected by the light transmission anisotropic layer 18 and the obliquely incident light is absorbed by the light absorption anisotropic layer 20, so that the light is emitted in the front direction. In contrast, the amount of light emitted obliquely can be greatly reduced.
As a result, according to the present invention, the front luminance, that is, the luminance of the light emitted in the front direction is high, and the amount of light emitted in the front direction is large compared to the light emitted in the oblique direction. An excellent planar lighting device can be realized.
　図２に、本発明の面状照明装置をバックライト装置に利用した別の例を示す。
　なお、図２に示すバックライト装置３０は、偏光制御層２６を有する以外は、図１に示すバックライト装置１０と同じ構成を有するので、同じ部材には同じ符号を付し、以下の説明は、異なる部位を主に行う。 FIG. 2 shows another example in which the planar illumination device of the present invention is used as a backlight device.
The backlight device 30 shown in FIG. 2 has the same configuration as the backlight device 10 shown in FIG. , Mainly performed on different parts.
　図２に示すバックライト装置３０は、光透過異方性層１８と、光吸収異方性層２０との間に、偏光制御層２６を有する。すなわち、上述した本発明の光学フィルムは、光透過異方性層１８と、光吸収異方性層２０との間に、偏光制御層２６を有してもよい。
　なお、図２に示すバックライト装置３０において、光透過異方性層１８、偏光制御層２６および光吸収異方性層２０は、全てが積層されてもよく、あるいは、２層が積層されてもよく、あるいは、全てが離間していてもよい。また、光拡散層１６も、光透過異方性層１８に積層されてもよく、離間していてもよい。 The backlight device 30 shown in FIG. 2 has a polarization control layer 26 between the anisotropic light transmission layer 18 and the anisotropic light absorption layer 20 . That is, the optical film of the present invention described above may have the polarization control layer 26 between the anisotropic light transmission layer 18 and the anisotropic light absorption layer 20 .
In the backlight device 30 shown in FIG. 2, the anisotropic light transmission layer 18, the polarization control layer 26 and the anisotropic light absorption layer 20 may all be laminated, or two layers may be laminated. or all may be spaced apart. Also, the light diffusion layer 16 may be laminated on the light transmission anisotropic layer 18 or may be separated therefrom.
　偏光制御層２６は、入射した直線偏光の偏光方向を８０～１００°の範囲で回転させるものである。
　バックライト装置３０すなわち本発明の面状照明装置は、このような偏光制御層２６を有することにより、平行光源性を、より向上できる。 The polarization control layer 26 rotates the polarization direction of incident linearly polarized light within the range of 80 to 100 degrees.
Since the backlight device 30, that is, the planar lighting device of the present invention has such a polarization control layer 26, parallel light source properties can be further improved.
　一般的な層に直線偏光が入射した場合には、図３に概念的に示すように、反射率は、実線で示すＰ偏光よりも、破線で示すＳ偏光の方が高い。
　ところが、本発明者らの検討によれば、正面入射した光を透過して、斜め入射した光を反射する光透過異方性層１８は、一般的な層とは逆に、図４に概念的に示すように、反射されるのは実線で示すＰ偏光成分が多く、透過光は破線で示すＳ偏光成分が多い。
　なお、本発明において、Ｐ偏光とは、偏光方向が光吸収異方性層２０の表面すなわち光透過異方性層１８の表面と直交する直線偏光であり、Ｓ偏光とは、偏光方向が光吸収異方性層２０の表面すなわち光透過異方性層１８の表面と平行な直線偏光である。 When linearly polarized light is incident on a general layer, as conceptually shown in FIG. 3, the reflectance is higher for S-polarized light indicated by the dashed line than for P-polarized light indicated by the solid line.
However, according to the studies of the present inventors, the light transmission anisotropic layer 18, which transmits front incident light and reflects obliquely incident light, has the concept shown in FIG. As shown schematically, most of the reflected light is the P-polarized component indicated by the solid line, and most of the transmitted light is the S-polarized component indicated by the dashed line.
In the present invention, P-polarized light is linearly polarized light whose polarization direction is orthogonal to the surface of the anisotropic light absorption layer 20, that is, the surface of the anisotropic light transmission layer 18, and S-polarized light is light whose polarization direction is light. It is linearly polarized light parallel to the surface of the anisotropic absorption layer 20 , that is, the surface of the anisotropic light transmission layer 18 .
　上述のように、光吸収異方性層２０は、斜め入射した光を吸収するものであるが、通常の層と同様、光吸収異方性層２０による吸収率は、Ｐ偏光よりもＳ偏光の方が低い。
　従って、光吸収異方性層２０に入射した光において、Ｐ偏光成分よりもＳ偏光成分が多い場合には、光吸収異方性層２０による斜め入射した光の吸収率が低くなってしまう。その結果、光吸収異方性層２０に斜め入射したにも関わらず、光吸収異方性層２０で吸収されずに透過する光の割合が増えてしまう可能性がある。 As described above, the anisotropic light absorption layer 20 absorbs obliquely incident light, but as with ordinary layers, the absorptance of the anisotropic light absorption layer 20 is higher for S-polarized light than for P-polarized light. is lower.
Therefore, when the light incident on the anisotropic light absorption layer 20 contains more S-polarized components than P-polarized components, the absorption rate of obliquely incident light by the anisotropic light absorption layer 20 decreases. As a result, there is a possibility that the proportion of light that passes through the anisotropic light absorption layer 20 without being absorbed may increase even though the light is obliquely incident on the anisotropic light absorption layer 20 .
　これに対して、バックライト装置３０すなわち本発明の面状照明装置では、好ましい態様として、光透過異方性層１８と光吸収異方性層２０との間に、入射した直線偏光の偏光方向を８０～１００°の範囲で回転させる偏光制御層２６を有する。
　すなわち、バックライト装置３０は、好ましい態様として、光透過異方性層１８と光吸収異方性層２０との間に、Ｓ偏光をＰ偏光に変換する偏光制御層２６を有する。 On the other hand, in the backlight device 30, that is, the planar lighting device of the present invention, as a preferred embodiment, between the anisotropic light transmission layer 18 and the anisotropic light absorption layer 20, the polarization direction of the incident linearly polarized light is has a polarization control layer 26 that rotates in the range of 80-100°.
That is, as a preferred embodiment, the backlight device 30 has a polarization control layer 26 between the anisotropic light transmission layer 18 and the anisotropic light absorption layer 20 that converts S-polarized light into P-polarized light.
　上述のように、光透過異方性層１８を透過した光は、Ｐ偏光成分よりもＳ偏光成分の方が多い。従って、光透過異方性層１８と光吸収異方性層２０との間に、偏光制御層２６を有することにより、偏光制御層２６を透過して光吸収異方性層２０に入射した光は、Ｓ偏光成分よりもＰ偏光成分の方が多くなる。
　そのため、光透過異方性層１８と光吸収異方性層２０との間に、偏光制御層２６を有することにより、光吸収異方性層２０による、斜め入射した光の吸収率を、向上できる。すなわち、光吸収異方性層２０に斜め入射した光の透過率を、より低減できる。
　その結果、偏光制御層２６を有することにより、光吸収異方性層２０すなわちバックライト装置３０から出射する光における、斜め方向に出射する光に対する正面方向に出射する光の割合をより多くして、平行光源性を、より向上できる。 As described above, the light transmitted through the anisotropic light transmission layer 18 has more S-polarized components than P-polarized components. Therefore, by providing the polarization control layer 26 between the anisotropic light transmission layer 18 and the anisotropic light absorption layer 20, the light transmitted through the polarization control layer 26 and incident on the anisotropic light absorption layer 20 is has more P-polarized components than S-polarized components.
Therefore, by providing the polarization control layer 26 between the anisotropic light transmission layer 18 and the anisotropic light absorption layer 20, the absorption rate of obliquely incident light by the anisotropic light absorption layer 20 is improved. can. That is, the transmittance of light obliquely incident on the light absorption anisotropic layer 20 can be further reduced.
As a result, the presence of the polarization control layer 26 increases the ratio of the light emitted in the front direction to the light emitted in the oblique direction in the light emitted from the light absorption anisotropic layer 20, that is, the backlight device 30. , the parallel light source property can be further improved.
　偏光制御層２６には制限はなく、入射した直線偏光の偏光方向を８０～１００°の範囲で回転できるものであれば、公知の各種の物（光学素子）が利用可能である。
　偏光制御層２６としては、一例として、厚さ方向に沿って伸びる螺旋軸に沿って捩れ配向した液晶化合物を含む層が例示される。すなわち、偏光制御層２６としては、厚さ方向に螺旋状に捩れ配向した液晶化合物を含む層（旋光層、旋光フィルム）が例示される。 The polarization control layer 26 is not limited, and various known materials (optical elements) can be used as long as they can rotate the polarization direction of incident linearly polarized light within the range of 80 to 100 degrees.
An example of the polarization control layer 26 is a layer containing a liquid crystal compound twisted along a helical axis extending along the thickness direction. That is, the polarization control layer 26 is exemplified by a layer (optical rotatory layer, optical rotatory film) containing a liquid crystal compound helically twisted in the thickness direction.
　このような偏光制御層２６は、一例として、棒状ネマチック液晶化合物等の重合性液晶化合物と、キラル剤とを含む液晶組成物を用いて、形成できる。キラル剤（カイラル剤）は、液晶化合物の螺旋構造を誘起する機能を有する公知のキラル剤を用いればよい。
　具体的には、配向制御力を有する配向膜の表面に、重合性液晶化合物およびキラル剤等含む液晶組成物を塗布する。次いで、加熱することによって、液晶組成物を乾燥すると共に、液晶化合物を螺旋配向する。その後、例えば紫外線を照射することによって、液晶組成物を硬化することによって、液晶化合物を厚さ方向に螺旋状に配向した偏光制御層２６を作製できる。 Such a polarization control layer 26 can be formed, for example, using a liquid crystal composition containing a polymerizable liquid crystal compound such as a rod-like nematic liquid crystal compound and a chiral agent. As a chiral agent (chiral agent), a known chiral agent having a function of inducing a helical structure of a liquid crystal compound may be used.
Specifically, a liquid crystal composition containing a polymerizable liquid crystal compound, a chiral agent, and the like is applied to the surface of an alignment film having alignment control power. Then, by heating, the liquid crystal composition is dried and the liquid crystal compound is helically aligned. After that, the liquid crystal composition is cured by irradiating ultraviolet rays, for example, so that the polarization control layer 26 in which the liquid crystal compound is helically aligned in the thickness direction can be produced.
　液晶化合物を厚さ方向に螺旋状に捩れ配向した偏光制御層２６において、液晶化合物の捩れ角には、制限はなく、液晶化合物の種類等に応じて、直線偏光の偏光方向を８０～１００°の範囲で回転できる捩れ角を、適宜、設定すればよい。
　液晶化合物の捩れ角は、キラル剤の種類および添加量によって調節できる。
　また、液晶化合物を厚さ方向に螺旋状に捩れ配向した偏光制御層２６において、液晶化合物のΔｎ、膜厚ｄ、および、Δｎｄには、制限はなく、直線偏光の偏光方向を８０～１００°の範囲で回転できるように、適宜、設定すればよい。 In the polarization control layer 26 in which the liquid crystal compound is helically twisted in the thickness direction, the twist angle of the liquid crystal compound is not limited, and the polarization direction of the linearly polarized light is 80 to 100° depending on the type of the liquid crystal compound. A torsion angle that can be rotated within the range of can be appropriately set.
The twist angle of the liquid crystal compound can be adjusted by the type and amount of the chiral agent.
In the polarization control layer 26 in which the liquid crystal compound is helically twisted in the thickness direction, the Δn, film thickness d, and Δnd of the liquid crystal compound are not limited, and the polarization direction of linearly polarized light is 80 to 100°. can be set as appropriate so that it can be rotated within the range of .
　偏光制御層２６としては、１／２波長板も利用可能である。
　１／２波長板は、可視光のいずれかの波長において約１／２波長となる位相差を有する、公知の１／２波長板（λ／２板、λ／２位相差板）が、各種、利用可能である。
　１／２波長板としては、例えば、波長５５０ｎｍにおいて、２２０～３３０ｎｍの位相差を有する１／２波長板が好ましく例示され、２４７～３０２ｎｍの位相差を有する１／２波長板がより好ましく例示される。 A half-wave plate can also be used as the polarization control layer 26 .
The half-wave plate has a phase difference of about half the wavelength at any wavelength of visible light. , is available.
As the half-wave plate, for example, a half-wave plate having a phase difference of 220 to 330 nm at a wavelength of 550 nm is preferably exemplified, and a half-wave plate having a phase difference of 247 to 302 nm is more preferably exemplified. be.
　本発明の面状照明装置を用いる、図１および図２に示すバックライト装置においては、光透過異方性層１８は、正面入射した光を透過して、斜め入射した光を反射するものである。しかしながら、本発明の面状照明装置において、光透過異方性層は、これに制限はされない。
　すなわち、本発明の面状照明装置においては、透過率Ｔ０および透過率Ｔ５０が、Ｔ０＞Ｔ５０およびＴ５０＜７０％という要件１、および、吸光度Ｔ０および吸光度Ｔ５０が、共に０．０５未満であるという要件２を満たすものであれば、公知の各種のものが利用可能である。 In the backlight device shown in FIGS. 1 and 2 using the planar lighting device of the present invention, the anisotropic light transmission layer 18 transmits front incident light and reflects obliquely incident light. be. However, in the planar illumination device of the present invention, the light transmission anisotropic layer is not limited to this.
That is, in the planar illumination device of the present invention, Requirement 1 that the transmittance T0 and the transmittance T50 are T0>T50 and T50<70%, and that both the absorbance T0 and the absorbance T50 are less than 0.05. As long as it satisfies Requirement 2, various known materials can be used.
　一例として、図５に概念的に示すような、正面入射した光はそのまま透過し、斜め入射した光を拡散する光透過異方性層３４が例示される。
　この光透過異方性層３４によれば、そのまま透過する正面入射した光に加え、斜め入射して拡散されることによって、進行方向が正面方向になり、光吸収異方性層２０に正面入射し、透過する光も発生する。
　さらに、斜め入射した光の一部は、拡散されることによって、より法線に対して角度が大きくなる。すなわち、拡散光の一部は、斜め入射の角度が、より深くなる。このような斜め入射の角度が深い光は、光吸収異方性層２０における光路が長くなるので、光吸収異方性層２０による吸収率が、より高くなる。その結果、光吸収異方性層２０から、斜め方向に出射される光を、大幅に低減できる。 As an example, a light transmission anisotropic layer 34 that transmits front incident light as it is and diffuses obliquely incident light, as conceptually shown in FIG. 5, is exemplified.
According to this light transmission anisotropic layer 34 , in addition to the front incident light that is transmitted as it is, the traveling direction becomes the front direction by being obliquely incident and diffused, and the light is front incident on the light absorption anisotropic layer 20 . and light that passes through is also generated.
In addition, part of the obliquely incident light is diffused to form a larger angle with respect to the normal line. That is, part of the diffused light has a deeper angle of oblique incidence. Light with such a deep oblique incident angle has a longer optical path in the anisotropic light absorption layer 20, so that the absorption rate of the anisotropic light absorption layer 20 becomes higher. As a result, the light emitted obliquely from the light absorption anisotropic layer 20 can be greatly reduced.
　従って、このような光透過異方性層３４を用いることによって、光吸収異方性層２０すなわち面状照明装置から正面方向に出射する光を増加し、かつ、斜め方向に出射する光を減少できる。
　その結果、この光透過異方性層３４を用いることにより、正面輝度が高く、かつ、平行光源性に優れる面状照明装置を実現できる。 Therefore, by using such an anisotropic light-transmitting layer 34, the light emitted from the anisotropic light-absorbing layer 20, that is, the planar lighting device, in the front direction is increased, and the light emitted in the oblique direction is decreased. can.
As a result, by using this light transmission anisotropic layer 34, it is possible to realize a planar illumination device with high front luminance and excellent parallel light source properties.
　このような、正面入射した光を透過し、斜め入射した光を拡散する光透過異方性層３４は、公知のものが、各種、利用可能である。
　一例として、特開２００９－１５７２５１号公報に記載される、それぞれ分子内に重合性炭素－炭素結合を有し、かつ、単独重合して得られる単独重合体の屈折率に差がある少なくとも２種類の光重合可能なモノマーまたはオリゴマーを含有する光硬化性樹脂組成物を用いる光透過異方性層（光制御膜）が例示される。この光透過異方性層は、光硬化性樹脂組成物を膜状に形成し、線状光源と、線状光源からの光を反射して平行光として組成物膜に照射する反射部材とを用い、組成物膜と、線状光源および反射部材とを、洗浄光源の軸方向と移動方向とが交差するように相対的に移動することにより、線状光源からの光を照射して組成物膜を硬化することで、形成できる。
　また、別の例として、特開２０１１－１８６４９４号公報に記載される、重合性炭素－炭素二重結合を有する化合物を、複数種、含み、かつ、少なくとも１種の化合物が、複数の芳香環と１つの重合性炭素－炭素二重結合とを分子内に有する化合物であり、複数の芳香環と１つの重合性炭素－炭素二重結合とを分子内に有する化合物の少なくとも１種の化合物が、芳香族性水酸基を含有する化合物であり、膜状組成物１００重量部に対する、この化合物の含有量が、０．１～３０重量部である膜状組成物に、特定方向から紫外線を照射して、この組成物を硬化させて得られる、特定角度範囲の入射光のみを選択的に散乱する光透過異方性層（光制御膜）も利用可能である。
　さらに、正面入射した光を透過し、斜め入射した光を拡散する光透過異方性層３４は、住友化学社製のビジョンコントロールフィルムなど、市販品も利用可能である。 As the light transmission anisotropic layer 34 that transmits front incident light and diffuses obliquely incident light, various known ones can be used.
As an example, at least two types each having a polymerizable carbon-carbon bond in the molecule and having a difference in the refractive index of the homopolymer obtained by homopolymerization are described in JP-A-2009-157251. An anisotropic light transmission layer (light control film) using a photocurable resin composition containing a photopolymerizable monomer or oligomer of is exemplified. The anisotropic light transmission layer is formed by forming a photocurable resin composition into a film, and includes a linear light source and a reflecting member that reflects the light from the linear light source and irradiates the composition film with parallel light. The composition film, the linear light source and the reflecting member are moved relative to each other so that the axial direction of the cleaning light source intersects with the direction of movement of the cleaning light source, thereby irradiating the composition with light from the linear light source. It can be formed by curing the film.
Further, as another example, a compound having a polymerizable carbon-carbon double bond described in JP-A-2011-186494 includes a plurality of types, and at least one type of compound contains a plurality of aromatic rings. and one polymerizable carbon-carbon double bond in the molecule, at least one compound having a plurality of aromatic rings and one polymerizable carbon-carbon double bond in the molecule , which is a compound containing an aromatic hydroxyl group and the content of this compound is 0.1 to 30 parts by weight with respect to 100 parts by weight of the film composition, is irradiated with ultraviolet rays from a specific direction. In addition, a light transmission anisotropic layer (light control film) that selectively scatters incident light within a specific range of angles obtained by curing this composition can also be used.
Furthermore, as the light transmission anisotropic layer 34 that transmits front incident light and diffuses obliquely incident light, a commercially available product such as a vision control film manufactured by Sumitomo Chemical Co., Ltd. can be used.
　本発明の画像表示装置は、このような本発明の面状照明装置を有する画像表示装置である。
　本発明の画像表示装置は、面状照明装置を用いるものであれば、公知の各種の画像表示装置が利用可能である。好ましい一例として、公知の液晶パネルを有する、液晶表示装置（ＬＣＤ（Liquid Crystal Display））が例示される。上述のように、本発明の面状照明装置は、正面輝度が高く、かつ、平行光源性に優れる。従って、このような本発明の面状照明装置を用いる本発明の画像表示装置は、正面の表示輝度が高い高画質の画像を表示でき、かつ、斜め方向から観察した際の視認性を低減できる視野制御性に優れたものである。 The image display device of the present invention is an image display device having such a planar illumination device of the present invention.
As the image display device of the present invention, various known image display devices can be used as long as they use a planar illumination device. A preferred example is a liquid crystal display (LCD) having a known liquid crystal panel. As described above, the planar illumination device of the present invention has high front luminance and excellent parallel light source properties. Therefore, the image display device of the present invention using such a planar illumination device of the present invention can display a high-quality image with high front display luminance, and can reduce visibility when observed from an oblique direction. It has excellent visual field controllability.
　以上、本発明の面状照明装置、画像表示装置および光学フィルムについて詳細に説明したが、本発明は、上述の例に制限はされず、本発明の要旨を逸脱しない範囲において、各種の改良および変更を行ってもよいのは、もちろんである。 Although the planar illumination device, the image display device and the optical film of the present invention have been described in detail above, the present invention is not limited to the above examples, and various improvements and improvements can be made without departing from the scope of the present invention. Of course, changes may be made.
　以下に実施例を挙げて本発明の特徴をさらに具体的に説明する。以下の実施例に示す材料、試薬、使用量、物質量、割合、処理内容、および、処理手順等は、本発明の趣旨を逸脱しない限り適宜変更することができる。したがって、本発明の範囲は以下に示す具体例により限定的に解釈されるべきものではない。 The features of the present invention will be described more specifically below with reference to examples. The materials, reagents, amounts used, amounts of substances, ratios, treatment details, treatment procedures, etc. shown in the following examples can be changed as appropriate without departing from the gist of the present invention. Therefore, the scope of the present invention should not be construed to be limited by the specific examples shown below.
［実施例１］
　＜配向膜の形成＞
　厚さ４０μｍのセルロースアシレートフィルム（ＴＡＣ基材；富士フイルム社製、ＴＧ４０）の表面をアルカリ液で鹸化し、その上に下記の配向膜形成用組成物をワイヤーバーで塗布した。
　塗膜が形成された支持体を、６０℃の温風で６０秒間、さらに、１００℃の温風で１２０秒間乾燥して配向膜を形成し、配向膜付きＴＡＣフィルムを得た。
　配向膜の膜厚は１μｍであった。 [Example 1]
<Formation of Alignment Film>
The surface of a 40 μm-thick cellulose acylate film (TAC substrate; TG40 manufactured by Fuji Film Co., Ltd.) was saponified with an alkaline solution, and the following alignment film-forming composition was applied thereon with a wire bar.
The support on which the coating film was formed was dried with hot air at 60° C. for 60 seconds and then with hot air at 100° C. for 120 seconds to form an orientation film, thereby obtaining an orientation film-attached TAC film.
The film thickness of the alignment film was 1 μm.
―――――――――――――――――――――――――――――――――
配向膜形成用組成物
―――――――――――――――――――――――――――――――――
・変性ポリビニルアルコールＰＶＡ－１　　　　　　　　３．８０質量部
・ＩＲＧＡＣＵＲＥ２９５９　　　　　　　　　　　　　０．２０質量部
・水　　　　　　　　　　　　　　　　　　　　　　　　　　７０質量部
・メタノール　　　　　　　　　　　　　　　　　　　　　　３０質量部
――――――――――――――――――――――――――――――――― ―――――――――――――――――――――――――――――――――
Alignment film-forming composition――――――――――――――――――――――――――――――――
・Modified polyvinyl alcohol PVA-1 3.80 parts by mass ・IRGACURE 2959 0.20 parts by mass ・Water 70 parts by mass ・Methanol 30 parts by mass ―――――――――――――――――――――― ――――――――――――
　変性ポリビニルアルコールＰＶＡ－１
Figure JPOXMLDOC01-appb-C000001
 Modified polyvinyl alcohol PVA-1
Figure JPOXMLDOC01-appb-C000001
　＜光吸収異方性層の形成＞
　得られた配向膜上に、下記の光吸収異方性層形成用組成物をワイヤーバーで連続的に塗布し、１２０℃で６０秒間加熱した後、室温（２３℃）になるまで冷却した。
　次いで、８０℃で６０秒間加熱し、再び室温になるまで冷却した。
　その後、ＬＥＤ灯（中心波長３６５ｎｍ）を用いて、照度２００ｍＷ／ｃｍ2の照射条件で、紫外線を２秒間照射することにより、配向膜の上に光吸収異方性層を形成した。
　光吸収異方性層の膜厚は３．５μｍであった。 <Formation of light absorption anisotropic layer>
On the resulting alignment film, the following composition for forming an anisotropic light absorption layer was continuously applied with a wire bar, heated at 120° C. for 60 seconds, and then cooled to room temperature (23° C.).
Then, it was heated at 80° C. for 60 seconds and cooled again to room temperature.
After that, an LED lamp (center wavelength 365 nm) was used to irradiate ultraviolet rays for 2 seconds under irradiation conditions of an illuminance of 200 mW/cm 2 to form a light absorption anisotropic layer on the alignment film.
The film thickness of the light absorption anisotropic layer was 3.5 μm.
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光吸収異方性層形成用組成物の組成
―――――――――――――――――――――――――――――――――
・二色性物質Ｄ－１　　　　　　　　　　　　　　　　　０．６３質量部
・二色性物質Ｄ－２　　　　　　　　　　　　　　　　　０．１７質量部
・二色性物質Ｄ－３　　　　　　　　　　　　　　　　　１．１３質量部
・高分子液晶化合物Ｐ－１　　　　　　　　　　　　　　８．１８質量部
・ＩＲＧＡＣＵＲＥＯＸＥ－０２（ＢＡＳＦ社製）　　　０．１６質量部
・化合物Ｅ－１　　　　　　　　　　　　　　　　　　　０．１２質量部
・化合物Ｅ－２　　　　　　　　　　　　　　　　　　　０．１２質量部
・界面活性剤Ｆ－１　　　　　　　　　　　　　　　　０．００５質量部
・シクロペンタノン　　　　　　　　　　　　　　　　８５．００質量部
・ベンジルアルコール　　　　　　　　　　　　　　　　４．５０質量部
――――――――――――――――――――――――――――――――― ―――――――――――――――――――――――――――――――――
Composition of Composition for Forming Light Absorption Anisotropic Layer ――――――――――――――――――――――――――――――――――
Dichroic substance D-1 0.63 parts by mass Dichroic substance D-2 0.17 parts by mass Dichroic substance D-3 1.13 parts by mass Polymer liquid crystal compound P-1 8.18 Parts by mass IRGACUREOXE-02 (manufactured by BASF) 0.16 parts by mass Compound E-1 0.12 parts by mass Compound E-2 0.12 parts by mass Surfactant F-1 0.005 parts by mass Cyclo Pentanone 85.00 parts by mass Benzyl alcohol 4.50 parts by mass ――――――――――――――――――――――――――――――――――
　二色性物質Ｄ－１
Figure JPOXMLDOC01-appb-C000002
　二色性物質Ｄ－２
Figure JPOXMLDOC01-appb-C000003
　二色性物質Ｄ－３
Figure JPOXMLDOC01-appb-C000004
 Dichroic substance D-1
Figure JPOXMLDOC01-appb-C000002
Dichroic substance D-2
Figure JPOXMLDOC01-appb-C000003
Dichroic substance D-3
Figure JPOXMLDOC01-appb-C000004
　高分子液晶化合物Ｐ－１
Figure JPOXMLDOC01-appb-C000005
 Polymer liquid crystal compound P-1
Figure JPOXMLDOC01-appb-C000005
　化合物Ｅ－１
Figure JPOXMLDOC01-appb-C000006
　化合物Ｅ－２
Figure JPOXMLDOC01-appb-C000007
 Compound E-1
Figure JPOXMLDOC01-appb-C000006
Compound E-2
Figure JPOXMLDOC01-appb-C000007
　界面活性剤Ｆ－１
Figure JPOXMLDOC01-appb-C000008
 Surfactant F-1
Figure JPOXMLDOC01-appb-C000008
　作製した光吸収異方性層について、ＡｘｏＳｃａｎ　ＯＰＭＦ－１（オプトサイエンス社製）を用いて、極角および方位角を振りながら透過率を測定することで、透過率中心軸の方向を測定した。
　その結果、透過率中心軸は、層の表面に対して垂直であった。 For the prepared light absorption anisotropic layer, the direction of the transmittance center axis was measured by measuring the transmittance while changing the polar angle and azimuth angle using AxoScan OPMF-1 (manufactured by Optoscience).
As a result, the transmittance central axis was perpendicular to the surface of the layer.
　＜光透過異方性層の作製＞
　屈折率が１．５７、融点が２２０°、ガラス転移温度が８０℃の共重合ＰＥＴと、融点を持たない非晶性の平均屈折率が１．６３、ガラス転移温度が８０℃の共重合ＰＥＮとを用意した。共重合ＰＥＴおよび共重合ＰＥＮを、２台の単軸押出機に、それぞれ投入し、２９０℃の温度で溶融させて、混錬した。
　続いて、混錬した共重合ＰＥＴおよび混錬した共重合ＰＥＮを、それぞれ計量しながら、スリット数８０１個の積層装置で合流させて、厚さ方向に交互に８０１層積層させた積層体を作製した。 <Preparation of light transmission anisotropic layer>
A copolymerized PET having a refractive index of 1.57, a melting point of 220° and a glass transition temperature of 80°C, and an amorphous copolymerized PEN having an average refractive index of 1.63 and a glass transition temperature of 80°C. and prepared. Copolymerized PET and copolymerized PEN were charged into two single-screw extruders, melted at a temperature of 290° C., and kneaded.
Subsequently, the kneaded copolymer PET and the kneaded copolymer PEN are weighed and combined in a lamination device with 801 slits to produce a laminate in which 801 layers are alternately laminated in the thickness direction. did.
　作製した積層体を６０℃の温度に設定したロール群で加熱した後、８５℃の温度に設定されたロールで３．７倍に延伸し、冷却した。
　冷却後、９０℃の温度の熱風で加熱後、９５℃の温度で、先に延伸した方向に対して垂直方向に３．２倍延伸した。
　延伸後、そのまま２４０℃の熱風で熱処理を行った。熱処理に続いて、２４０℃で２％の弛緩処理を行い、光学多層フィルムからなる光透過異方性層を形成した。 The produced laminate was heated by a roll group set at a temperature of 60° C., stretched 3.7 times by rolls set at a temperature of 85° C., and cooled.
After cooling, after heating with hot air at a temperature of 90°C, the film was stretched 3.2 times in the direction perpendicular to the previously stretched direction at a temperature of 95°C.
After stretching, heat treatment was performed with hot air at 240°C. Following the heat treatment, a 2% relaxation treatment was performed at 240° C. to form a light transmission anisotropic layer comprising an optical multilayer film.
　形成した光透過異方性層について、以下に示す測定方法によって、法線方向から波長５５０ｎｍの光を入射した際における透過率Ｔ０、および、法線に対して極角５０°の方向から波長５５０ｎｍの光を入射した際における透過率Ｔ５０、
　法線方向から波長５５０ｎｍの光を入射した際における吸光度Ａ０、および、法線に対して極角５０°の方向から波長５５０ｎｍの光を入射した際における吸光度Ａ５０、ならびに、
　法線方向から波長５５０ｎｍの光を入射した際における反射率Ｒ０、および、法線に対して極角５０°の方向から波長５５０ｎｍの光を入射した際における反射率Ｒ５０、を測定した。
　その結果、形成した光透過異方性層は、Ｔ０＞Ｔ５０およびＴ５０＜７０％、Ａ０＜０．０５およびＡ５０＜０．０５、ならびに、Ｒ０＜Ｒ５０およびＲ５０＞３０％を、全て満たすことを確認した。 Regarding the formed light transmission anisotropic layer, the transmittance T0 when light with a wavelength of 550 nm is incident from the normal direction and the wavelength of 550 nm from the direction of the polar angle of 50 ° with respect to the normal by the measurement method shown below Transmittance T50 when incident light of
Absorbance A0 when light with a wavelength of 550 nm is incident from the normal direction, and absorbance A50 when light with a wavelength of 550 nm is incident from the direction of a polar angle of 50 ° with respect to the normal, and
A reflectance R0 when light with a wavelength of 550 nm was incident from the normal direction, and a reflectance R50 when light with a wavelength of 550 nm was incident from the direction of a polar angle of 50° with respect to the normal were measured.
As a result, the anisotropic light transmission layer formed satisfies all of T0>T50 and T50<70%, A0<0.05 and A50<0.05, and R0<R50 and R50>30%. confirmed.
（１）透過率の測定
　透過率Ｔ０は、自動偏光フィルム測定装置（日本分光社製、ＶＡＰ－７０７０）を用いて、受光側に積分球を配置し、波長５５０ｎｍの透過率Ｔ０を測定した。
　続いて、ゴニオフォトメーターを用いて、表面の法線方向に対して極角５０°方向に光を照射し、受光側の角度を５°刻みで－８０°～８０°の範囲で変更して、透過光の光強度を測定した。これらの受光角度毎の光強度を積算し、測定サンプルなしの全光量で規格化することで、透過率Ｔ５０を求めた。なお、ゴニオフォトメーターは、村上色彩技術研究所製の『三次元変角分光測色システム　ＧＣＭＳ－３Ｂ』を用いた。また、受光側の角度は、法線に対する極角である。 (1) Measurement of Transmittance Transmittance T0 was measured using an automatic polarizing film measuring device (manufactured by JASCO Corporation, VAP-7070) with an integrating sphere placed on the light receiving side and measuring transmittance T0 at a wavelength of 550 nm.
Subsequently, using a goniophotometer, light is irradiated in a polar angle of 50° with respect to the normal direction of the surface, and the angle on the light receiving side is changed in the range of -80° to 80° in increments of 5°. , the light intensity of the transmitted light was measured. The transmittance T50 was obtained by accumulating the light intensity for each light receiving angle and normalizing it by the total light amount without the measurement sample. As the goniophotometer, "Three-dimensional goniospectrophotometry system GCMS-3B" manufactured by Murakami Color Research Laboratory was used. Also, the angle on the light receiving side is the polar angle with respect to the normal.
（２）反射率の測定
　反射率Ｒ０は、入射面の反対側の表面をサンドペーパーで粗面化した後に黒色インクで処理し、裏面反射をなくした状態で、分光光度計（日本分光社製）を用いて、波長５５０ｎｍの積分反射率を測定することで求めた。
　続いて、ゴニオフォトメーターを用いて、表面の法線方向に対して極角５０°方向に光を照射し、受光側の角度を５°刻みで－８０°～３５°の範囲で変更して、反射光の光強度を測定した。これらの受光角度毎の光強度を積算し、測定サンプルとして鏡を配置した時の全光量で規格化することで、反射率Ｒ５０を求めた。なお、ゴニオフォトメーターは、村上色彩技術研究所製の『三次元変角分光測色システム　ＧＣＭＳ－３Ｂ』を用いた。また、受光側の角度は、法線に対する極角である。 (2) Measurement of reflectance Reflectance R0 was measured by roughening the surface opposite to the incident surface with sandpaper and then treating it with black ink to eliminate back reflection. ) was used to measure the integrated reflectance at a wavelength of 550 nm.
Subsequently, using a goniophotometer, light was irradiated at a polar angle of 50° with respect to the normal direction of the surface, and the angle on the light receiving side was changed in the range of -80° to 35° in increments of 5°. , the light intensity of the reflected light was measured. The reflectance R50 was obtained by accumulating the light intensity for each of these light receiving angles and normalizing it by the total light amount when a mirror was arranged as a measurement sample. As the goniophotometer, "Three-dimensional goniospectrophotometry system GCMS-3B" manufactured by Murakami Color Research Laboratory was used. Also, the angle on the light receiving side is the polar angle with respect to the normal.
（３）吸光度の測定
　吸光度Ａ０は、測定した透過率Ｔ０および反射率Ｒ０から、下記式を用いて求めた。
　　Ａ０＝－ＬＯＧ１０（Ｔ０＋Ｒ０）
　また、吸光度Ａ５０は、測定した透過率Ｔ５０および反射率Ｒ５０から、下記式を用いて求めた。
　　Ａ５０＝－ＬＯＧ１０（Ｔ５０＋Ｒ５０） (3) Measurement of Absorbance The absorbance A0 was obtained from the measured transmittance T0 and reflectance R0 using the following formula.
A0=-LOG10(T0+R0)
Also, the absorbance A50 was obtained from the measured transmittance T50 and reflectance R50 using the following formula.
A50=-LOG10(T50+R50)
　＜光学フィルム１の作製＞
　市販の粘着剤（綜研化学社製、ＳＫ２０５７）を用いて、光透過異方性層と光吸収異方性層とを貼り合わせて、光透過異方性層、光吸収異方性層、配向膜およびＴＡＣ基材を、この順で積層した光学フィルム１を作製した。 <Production of optical film 1>
Using a commercially available adhesive (manufactured by Soken Chemical Co., Ltd., SK2057), the anisotropic light transmission layer and the anisotropic light absorption layer are bonded together, and the anisotropic light transmission layer, the anisotropic light absorption layer, and the orientation An optical film 1 was prepared by laminating a film and a TAC substrate in this order.
　＜バックライト装置Ａ１の作製＞
　ＩＰＳモードの液晶表示装置を分解し、液晶パネル（液晶セル）を取り出した。なお、液晶表示装置は、ＡＰＰＬＥ社製の『ｉＰａｄ Ａｉｒ（登録商標）　Ｗｉ－Ｆｉモデル　１６ＧＢ』を用いた。
　液晶パネルを取り出した液晶表示装置に拡散シートの上に、光透過異方性層が拡散シート側になるように、光学フィルム１を配置し、バックライト装置Ａ１を作製した。 <Fabrication of backlight device A1>
An IPS mode liquid crystal display device was disassembled, and a liquid crystal panel (liquid crystal cell) was taken out. As the liquid crystal display device, "iPad Air (registered trademark) Wi-Fi model 16 GB" manufactured by APPLE was used.
The optical film 1 was arranged on the diffusion sheet in the liquid crystal display device from which the liquid crystal panel was taken out so that the light transmission anisotropic layer was on the diffusion sheet side, thereby producing the backlight device A1.
［実施例２］
　＜色味調整層の形成＞
　実施例１で作製した光学フィルム１の光吸収異方性層の上に、下記の色味調整層形成用組成物をワイヤーバーで連続的に塗布し、塗膜を形成した。
　次いで、塗膜が形成された積層体を６０℃の温風で６０秒間、さらに１００℃の温風で１２０秒間乾燥して、色味調整層を形成して、光学フィルム２を作製した。
　色味調整層の膜厚は０．５μｍであった。
―――――――――――――――――――――――――――――――――
色味調整層形成用組成物
―――――――――――――――――――――――――――――――――
・変性ポリビニルアルコールＰＶＡ－１　　　　　　　　３．８０質量部
・ＩＲＧＡＣＵＲＥ２９５９　　　　　　　　　　　　　０．２０質量部
・色素化合物Ｇ－１　　　　　　　　　　　　　　　　　０．０８質量部
・水　　　　　　　　　　　　　　　　　　　　　　　　　　７０質量部
・メタノール　　　　　　　　　　　　　　　　　　　　　　３０質量部
――――――――――――――――――――――――――――――――― [Example 2]
<Formation of color adjustment layer>
On the light absorption anisotropic layer of the optical film 1 produced in Example 1, the following composition for forming a color adjustment layer was continuously applied with a wire bar to form a coating film.
Next, the layered product with the coating film formed thereon was dried with hot air at 60° C. for 60 seconds and then with hot air at 100° C. for 120 seconds to form a color tone adjusting layer, thereby producing an optical film 2 .
The film thickness of the tint adjusting layer was 0.5 μm.
―――――――――――――――――――――――――――――――――
Color adjustment layer forming composition――――――――――――――――――――――――――――――――――
・Modified polyvinyl alcohol PVA-1 3.80 parts by mass ・IRGACURE 2959 0.20 parts by mass ・Dye compound G-1 0.08 parts by mass ・Water 70 parts by mass ・Methanol 30 parts by mass ―――――――――― ―――――――――――――――――――――――
　色素化合物Ｇ－１
Figure JPOXMLDOC01-appb-C000009
 Dye compound G-1
Figure JPOXMLDOC01-appb-C000009
　＜バックライト装置Ａ２の作製＞
　実施例１のバックライト装置Ａ１の作製において、光学フィルム１に代えて光学フィルム２を用いた以外は、実施例１と同様にしてバックライト装置Ａ２を作製した。 <Fabrication of backlight device A2>
A backlight device A2 was fabricated in the same manner as in Example 1, except that the optical film 2 was used instead of the optical film 1 in the fabrication of the backlight device A1 of Example 1.
［比較例１］
　＜バックライト装置Ｂ１の作製＞
　実施例１における光学フィルム１において、光透過異方性層を有さない以外は同様にして光学フィルムＢ１を作製した。
　実施例１のバックライト装置Ａ１の作製において、光学フィルム１に代えて光学フィルムＢ１を用いた以外は、実施例１と同様にしてバックライト装置Ｂ１を作製した。 [Comparative Example 1]
<Fabrication of backlight device B1>
An optical film B1 was prepared in the same manner as in the optical film 1 in Example 1, except that the anisotropic light transmission layer was not provided.
A backlight device B1 was fabricated in the same manner as in Example 1, except that the optical film B1 was used instead of the optical film 1 in the fabrication of the backlight device A1 of Example 1.
［実施例３］
　＜転写フィルムの作製＞
　７５μｍｍのＰＥＴフィルム（富士フイルム社製）の表面にラビング処理を施して、剥離性支持体を作製した。 [Example 3]
<Production of transfer film>
A peelable support was prepared by subjecting the surface of a 75 μm PET film (manufactured by Fuji Film) to a rubbing treatment.
　作製した剥離性支持体のラビング処理面上に、下記の旋光層用塗布液を膜厚３μｍになるようにバーコーターを用いて塗布して、塗膜を形成した。
　次いで、塗膜面温度を６０℃として９０秒間加熱熟成した。その後、１００℃で塗膜に３００ｍＪ/ｃｍ2の紫外線を照射することで、液晶化合物の配向を固定化して旋光層を形成した。これにより、剥離性支持体と、偏光制御層としての旋光層とを含む転写フィルムを作製した。
　なお、得られた旋光層において、液晶化合物のΔｎは０．１６、膜厚ｄは３０００ｎｍであり、Δｎｄは４８０であった。また、旋光層には、厚さ方向に沿って延びる螺旋軸に沿って捩れ配向した液晶化合物が含まれていた。ＡｘｏＳｃａｎ ＯＰＭＦ-１(オプトサイエンス社製)を用いた解析によって、確認したところ、螺旋状の液晶化合物の捩れ角は、９０°であった。
　２枚の偏光板の間に旋光層を含む転写フィルムを入れて、２枚の偏光板を通った光が一番暗くなるように、２枚の偏光板を面内方向に回転させた。この時の２枚の偏光板の透過軸が成す角度を測ることによって、偏光制御層である旋光層による、直線偏光の偏光方向の回転角を測定した。その結果、旋光層は、直線偏光の偏光方向を９０°回転する旋光層であった。 On the rubbing-treated surface of the produced peelable support, the following optically active layer coating solution was applied using a bar coater to a film thickness of 3 μm to form a coating film.
Then, the coating film surface temperature was set to 60° C. and heat aging was performed for 90 seconds. Thereafter, the coating film was irradiated with ultraviolet rays of 300 mJ/cm 2 at 100° C. to fix the orientation of the liquid crystal compound and form an optically active layer. Thus, a transfer film including a peelable support and an optical rotation layer as a polarization control layer was produced.
In the obtained optical rotation layer, the liquid crystal compound had a Δn of 0.16, a film thickness d of 3000 nm, and a Δnd of 480. In addition, the optically active layer contained a liquid crystal compound that was twisted along the helical axis extending along the thickness direction. Analysis using AxoScan OPMF-1 (manufactured by Optoscience) confirmed that the twist angle of the helical liquid crystal compound was 90°.
A transfer film containing an optical rotation layer was placed between the two polarizing plates, and the two polarizing plates were rotated in the in-plane direction so that the light passing through the two polarizing plates was the darkest. By measuring the angle formed by the transmission axes of the two polarizing plates at this time, the rotation angle of the polarization direction of the linearly polarized light by the optical rotation layer, which is the polarization control layer, was measured. As a result, the optical rotation layer was an optical rotation layer that rotates the polarization direction of linearly polarized light by 90°.
―――――――――――――――――――――――――――――――――
旋光層用塗布液
―――――――――――――――――――――――――――――――――
・メチルエチルケトン　　　　　　　　　　　　　　　　　２３３質量部
・シクロヘキサノン　　　　　　　　　　　　　　　　　　　１２質量部
・棒状液晶化合物２０１　　　　　　　　　　　　　　　　　８３質量部
・棒状液晶化合物２０２　　　　　　　　　　　　　　　　　１５質量部
・棒状液晶化合物２０３　　　　　　　　　　　　　　　　　　２質量部
・多官能モノマーＡ－ＴＭＭＴ（新中村化学工業社製）　　　　１質量部
・ＩＲＧＡＣＵＲＥ８１９（ＢＡＳＦ社製）　　　　　　　　　４質量部
・界面活性剤１　　　　　　　　　　　　　　　　　　　０．０５質量部
・界面活性剤２　　　　　　　　　　　　　　　　　　　０．０１質量部
・カイラル剤　　　　　　　　　　　　　　　　　　　０．１１５質量部
――――――――――――――――――――――――――――――――― ―――――――――――――――――――――――――――――――――
Optical rotation layer coating solution――――――――――――――――――――――――――――――――――
・Methyl ethyl ketone 233 parts by mass ・Cyclohexanone 12 parts by mass ・Rod-shaped liquid crystal compound 201 83 parts by mass ・Rod-shaped liquid crystal compound 202 15 parts by mass ・Rod-shaped liquid crystal compound 203 2 parts by mass ・Polyfunctional monomer A-TMMT (manufactured by Shin-Nakamura Chemical Co., Ltd.) 1 Parts by mass IRGACURE819 (manufactured by BASF) 4 parts by mass Surfactant 1 0.05 parts by mass Surfactant 2 0.01 parts by mass Chiral agent 0.115 parts by mass ―――――――――― ―――――――――――――――――――――――
Figure JPOXMLDOC01-appb-C000010
Figure JPOXMLDOC01-appb-C000010
Figure JPOXMLDOC01-appb-C000011
Figure JPOXMLDOC01-appb-C000011
Figure JPOXMLDOC01-appb-C000012
Figure JPOXMLDOC01-appb-C000012
　実施例２における光学フィルム２の作製において、光吸収異方性層と光透過異方性層との貼着に先立ち、市販の粘着剤（綜研化学社製、ＳＫ２０５７）を用いて、光吸収異方性層に転写フィルムを貼り合わせた。なお、転写フィルムは、旋光層が光吸収異方性層側となるように貼り合わせた。次いで、剥離性支持体を剥離した。剥離性支持体を剥離した後、旋光層は光吸収異方性層側に貼合されたままであった。
　その後、市販の粘着剤（綜研化学社製、ＳＫ２０５７）を用いて、旋光層に光学フィルム１と同様に光透過異方性層を貼着した。さらに、光学フィルム２と同様に、光吸収異方性層に色味調整層を形成して、光学フィルム３を作製した。 In the preparation of the optical film 2 in Example 2, prior to bonding the anisotropic light absorption layer and the anisotropic light transmission layer, a commercially available adhesive (SK2057 manufactured by Soken Kagaku Co., Ltd.) was used to apply an anisotropic light absorption layer. A transfer film was attached to the anisotropic layer. The transfer film was attached so that the optical rotation layer was on the light absorption anisotropic layer side. The peelable support was then peeled off. After peeling off the peelable support, the optical rotatory layer remained attached to the light absorption anisotropic layer side.
After that, using a commercially available adhesive (SK2057 manufactured by Soken Kagaku Co., Ltd.), a light transmission anisotropic layer was adhered to the optical rotation layer in the same manner as the optical film 1. Furthermore, in the same manner as in the optical film 2, an optical film 3 was produced by forming a color adjustment layer on the light absorption anisotropic layer.
　＜バックライト装置Ａ３の作製＞
　実施例２のバックライト装置Ａ２の作製において、光学フィルム２に代えて光学フィルム３を用いた以外は、実施例２と同様にしてバックライト装置Ａ３を作製した。 <Fabrication of backlight device A3>
A backlight device A3 was fabricated in the same manner as in Example 2, except that the optical film 3 was used instead of the optical film 2 in the fabrication of the backlight device A2 of Example 2.
　＜光学フィルム４の作製＞
　実施例２における光学フィルム２の作製において、光吸収異方性層と光透過異方性層との貼着に先立ち、市販の粘着剤（綜研化学社製、ＳＫ２０５７）を用いて、光吸収異方性層に、１／２波長板を２枚重ねて貼合した。１／２波長板は、帝人社製の『ピュアエースＷＲ　Ｗ１４２（λ／２）』を用いた。
　その後、市販の粘着剤（綜研化学社製、ＳＫ２０５７）を用いて、１／２波長板（λ／２）に光学フィルム１と同様に光透過異方性層を貼着した。さらに、光学フィルム２と同様に、光吸収異方性層に色味調整層を形成して、光学フィルム４を作製した。 <Preparation of Optical Film 4>
In the preparation of the optical film 2 in Example 2, prior to bonding the anisotropic light absorption layer and the anisotropic light transmission layer, a commercially available adhesive (SK2057 manufactured by Soken Kagaku Co., Ltd.) was used to apply an anisotropic light absorption layer. Two half-wave plates were laminated on the anisotropic layer. As the half-wave plate, "Pure Ace WR W142 (λ/2)" manufactured by Teijin Limited was used.
After that, using a commercially available adhesive (SK2057 manufactured by Soken Kagaku Co., Ltd.), a light transmission anisotropic layer was adhered to a half-wave plate (λ/2) in the same manner as the optical film 1 . Furthermore, in the same manner as the optical film 2, an optical film 4 was produced by forming a color adjustment layer on the light absorption anisotropic layer.
　＜バックライト装置Ａ４の作製＞
　実施例２のバックライト装置Ａ２の作製において、光学フィルム２に代えて光学フィルム４を用いた以外は、実施例２と同様にしてバックライト装置Ａ４を作製した。 <Fabrication of backlight device A4>
A backlight device A4 was fabricated in the same manner as in Example 2 except that the optical film 4 was used instead of the optical film 2 in the fabrication of the backlight device A2 of Example 2.
［バックライト装置の性能評価］
　作製したバックライト装置について、以下のようにして、正面輝度、および、平行光源性を評価した。 [Performance evaluation of backlight device]
The produced backlight device was evaluated for front luminance and parallel light source properties as follows.
　＜正面輝度の評価＞
　作製したバックライト装置について、測定機を用いて、光出射面（バックライト面）内の法線方向の輝度Ｙ（０）を測定した。なお、測定機は、ＥＬＤＩＭ社製の『ＥＺ－Ｃｏｎｔｒａｓｔ　ＸＬ８８』を用いた。
　正面輝度を、下記の通り評価した。
　　Ａ：比較例であるバックライト装置Ｂ１のＹ（０）より大きい
　　Ｂ：比較例であるバックライト装置Ｂ１のＹ（０）以下 <Evaluation of front luminance>
For the manufactured backlight device, the luminance Y(0) in the normal direction within the light exit surface (backlight surface) was measured using a measuring instrument. As a measuring machine, "EZ-Contrast XL88" manufactured by ELDIM was used.
The front luminance was evaluated as follows.
A: Larger than Y(0) of backlight device B1 as a comparative example B: Y(0) or less of backlight device B1 as a comparative example
　＜平行光源性の評価＞
　作製したバックライト装置について、測定機を用いて、光出射面内の法線方向の輝度Ｙ（０）と光出射面内の法線方向から極角で５０°ずれた方向の輝度Ｙ（５０）を測定し、下記式を用いて、平行光源性の評価を行った。なお、測定機は、ＥＬＤＩＭ社製の『ＥＺ－Ｃｏｎｔｒａｓｔ　ＸＬ８８』を用いた。
　　　平行光源性評価＝Ｙ（０）／Ｙ（５０）
　平行光源性を、下記の通り評価した。
　　ＡＡ：比較例であるバックライト装置Ｂ１のＹ（０）／Ｙ（５０）の１．５倍より大きい
　　Ａ：比較例であるバックライト装置Ｂ１のＹ（０）／Ｙ（５０）より大きく、かつ、１．５倍以下
　　Ｂ：比較例であるバックライト装置Ｂ１のＹ（０）／Ｙ（５０）以下
　結果を、下記の表に示す。 <Evaluation of Parallel Light Source Properties>
With respect to the manufactured backlight device, the luminance Y(0) in the direction normal to the light exit surface and the luminance Y(50 ) was measured, and parallel light source property was evaluated using the following formula. As a measuring machine, "EZ-Contrast XL88" manufactured by ELDIM was used.
Parallel light source evaluation = Y (0) / Y (50)
Parallel light source property was evaluated as follows.
AA: greater than 1.5 times Y(0)/Y(50) of backlight device B1 as a comparative example A: greater than Y(0)/Y(50) of backlight device B1 as a comparative example, and 1.5 times or less B: Y(0)/Y(50) or less of backlight device B1 as a comparative example The results are shown in the table below.
Figure JPOXMLDOC01-appb-T000013
Figure JPOXMLDOC01-appb-T000013
　表に示されるように、光透過異方性層および光吸収異方性層を有する本発明の面状照明装置によるバックライト装置によれば、光透過異方性層を有さない従来のバックライト装置である比較例に比して、正面輝度および平行光源性に優れている。
　特に、光透過異方性層と光吸収異方性層との間に、偏光制御層である旋光層および１／２波長板を有する実施例３（バックライト装置Ａ３）および実施例４（バックライト装置Ａ４）は、優れた平行光源性を有している。
　以上の結果より、本発明の効果は明らかである。 As shown in the table, according to the backlight device using the planar lighting device of the present invention having the anisotropic light transmission layer and the anisotropic light absorption layer, the conventional backlight having no anisotropic light transmission layer was used. Compared to the comparative example which is a light device, it is superior in front luminance and parallel light source property.
In particular, Example 3 (backlight device A3) and Example 4 (backlight device A3) having an optical rotatory layer as a polarization control layer and a half-wave plate between the anisotropic light transmission layer and the anisotropic light absorption layer The light device A4) has excellent parallel light source properties.
From the above results, the effect of the present invention is clear.
　液晶表示装置等に好適に利用可能である。 It can be suitably used for liquid crystal display devices and the like.
　　１０，３０　バックライト装置
　　１２　反射層
　　１４　光源
　　１６　光拡散層
　　１８，３４　光透過異方性層
　　２０　光吸収異方性層
　　２６　偏光制御層 Reference Signs List 10, 30 backlight device 12 reflective layer 14 light source 16 light diffusion layer 18, 34 light transmission anisotropic layer 20 light absorption anisotropic layer 26 polarization control layer

Claims (9)

  1. 　光吸収異方性層と、光透過異方性層と、光拡散層と、光源と、反射層とを、この順番で有し、
    　前記光吸収異方性層は、透過率中心軸が層の表面に対して垂直であり、
    　前記光透過異方性層が、下記の要件１および要件２を満たす、面状照明装置。
    　要件１：前記光透過異方性層の法線方向から波長５５０ｎｍの光を入射した際における透過率をＴ０、前記光透過異方性層の法線に対して極角５０°の方向から波長５５０ｎｍの光を入射した際における透過率をＴ５０とした際に、Ｔ０＞Ｔ５０の関係、および、Ｔ５０＜７０％の関係を満たす。
    　要件２：前記光透過異方性層の法線方向から波長５５０ｎｍの光を入射した際における吸光度をＡ０、前記光透過異方性層の法線に対して極角５０°の方向から波長５５０ｎｍの光を入射した際における吸光度をＡ５０とした際に、Ａ０＜０．０５の関係、および、Ａ５０＜０．０５の関係を満たす。     Having an anisotropic light absorption layer, an anisotropic light transmission layer, a light diffusion layer, a light source, and a reflective layer in this order,
    The light absorption anisotropic layer has a transmittance center axis perpendicular to the surface of the layer,
    The planar lighting device, wherein the light transmission anisotropic layer satisfies requirements 1 and 2 below.
    Requirement 1: T0 transmittance when light with a wavelength of 550 nm is incident from the normal direction of the anisotropic light transmission layer, and the wavelength from the direction of the polar angle of 50 ° The relationship T0>T50 and the relationship T50<70% are satisfied, where T50 is the transmittance when light of 550 nm is incident.
    Requirement 2: A0 absorbance when light with a wavelength of 550 nm is incident from the normal direction of the anisotropic light transmission layer, and a wavelength of 550 nm from the direction of a polar angle of 50 ° with respect to the normal line of the anisotropic light transmission layer. When A50 is the absorbance at the time of incident light of , the relationship of A0<0.05 and the relationship of A50<0.05 are satisfied.
  2. 　前記光透過異方性層の法線方向から波長５５０ｎｍの光を入射した際における反射率をＲ０、前記光透過異方性層の法線に対して極角５０°の方向から波長５５０ｎｍの光を入射した際における反射率をＲ５０とした際に、
    　前記光透過異方性層が、Ｒ０＜Ｒ５０の関係、および、Ｒ５０＞３０％の関係を満たす、請求項１に記載の面状照明装置。     R0 is the reflectance when light with a wavelength of 550 nm is incident from the normal direction of the anisotropic light transmission layer, and light with a wavelength of 550 nm from a direction with a polar angle of 50 ° with respect to the normal line of the anisotropic light transmission layer. When the reflectance at the time of incident is R50,
    2. The planar illumination device according to claim 1, wherein the anisotropic light transmission layer satisfies the relationship of R0<R50 and the relationship of R50>30%.
  3. 　前記光透過異方性層が、異なる複数の層が５０層以上積層された多層膜である、請求項１または２に記載の面状照明装置。 The planar illumination device according to claim 1 or 2, wherein the light transmission anisotropic layer is a multilayer film in which 50 or more different layers are laminated.
  4. 　前記光透過異方性層と前記光吸収異方性層との間に、入射した直線偏光の偏光方向を８０～１００°の範囲で回転させる偏光制御層を有する、請求項１～３のいずれか１項に記載の面状照明装置。 4. The polarization control layer according to any one of claims 1 to 3, which rotates the polarization direction of incident linearly polarized light within a range of 80 to 100° between the anisotropic light transmission layer and the anisotropic light absorption layer. 2. The planar lighting device according to 1 or 2 above.
  5. 　前記偏光制御層が、厚さ方向に沿って伸びる螺旋軸に沿って捩れ配向した液晶化合物を含む層である、請求項４に記載の面状照明装置。 5. The planar illumination device according to claim 4, wherein the polarization control layer is a layer containing a liquid crystal compound twisted along a helical axis extending along the thickness direction.
  6. 　前記偏光制御層が、１／２波長板である、請求項４に記載の面状照明装置。 The planar illumination device according to claim 4, wherein the polarization control layer is a half-wave plate.
  7. 　請求項１～６のいずれか１項に記載の面状照明装置を有する画像表示装置。 An image display device comprising the planar illumination device according to any one of claims 1 to 6.
  8. 　層の表面に対して垂直な透過率中心軸を有する光吸収異方性層と、
    　下記の要件１および要件２を満たす光透過異方性層と、を有する光学フィルム。
    　要件１：前記光透過異方性層の法線方向から波長５５０ｎｍの光を入射した際における透過率をＴ０、前記光透過異方性層の法線に対して極角５０°の方向から波長５５０ｎｍの光を入射した際における透過率をＴ５０とした際に、Ｔ０＞Ｔ５０の関係、および、Ｔ５０＜７０％の関係を満たす。
    　要件２：前記光透過異方性層の法線方向から波長５５０ｎｍの光を入射した際における吸光度をＡ０、前記光透過異方性層の法線に対して極角５０°の方向から波長５５０ｎｍの光を入射した際における吸光度をＡ５０とした際に、Ａ０＜０．０５の関係、および、Ａ５０＜０．０５の関係を満たす。     a light absorption anisotropic layer having a transmittance center axis perpendicular to the surface of the layer;
    An optical film having a light transmission anisotropic layer that satisfies requirements 1 and 2 below.
    Requirement 1: T0 transmittance when light with a wavelength of 550 nm is incident from the normal direction of the anisotropic light transmission layer, and the wavelength from the direction of the polar angle of 50 ° The relationship T0>T50 and the relationship T50<70% are satisfied, where T50 is the transmittance when light of 550 nm is incident.
    Requirement 2: A0 absorbance when light with a wavelength of 550 nm is incident from the normal direction of the anisotropic light transmission layer, and a wavelength of 550 nm from the direction of a polar angle of 50 ° with respect to the normal line of the anisotropic light transmission layer. When A50 is the absorbance at the time of incident light of , the relationship of A0<0.05 and the relationship of A50<0.05 are satisfied.
  9. 　前記光透過異方性層と前記光吸収異方性層との間に、入射した直線偏光の偏光方向を８０～１００°の範囲で回転させる偏光制御層を有する、請求項８に記載の光学フィルム。 9. The optical system according to claim 8, comprising a polarization control layer between the anisotropic light transmission layer and the anisotropic light absorption layer that rotates the polarization direction of incident linearly polarized light within a range of 80 to 100 degrees. the film.
PCT/JP2022/017575 2021-04-26 2022-04-12 Planar lighting device, image display device, and optical film WO2022230657A1 (en)

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JP2010062112A (en) * 2008-09-08 2010-03-18 Toppan Printing Co Ltd Optical device, light uniformizing device, backlight unit, and display apparatus

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