WO2011004898A1 - Light diffusion film and liquid crystal display device comprising same - Google Patents

Light diffusion film and liquid crystal display device comprising same Download PDF

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Publication number
WO2011004898A1
WO2011004898A1 PCT/JP2010/061729 JP2010061729W WO2011004898A1 WO 2011004898 A1 WO2011004898 A1 WO 2011004898A1 JP 2010061729 W JP2010061729 W JP 2010061729W WO 2011004898 A1 WO2011004898 A1 WO 2011004898A1
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WO
WIPO (PCT)
Prior art keywords
light
film
liquid crystal
resin
crystal display
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PCT/JP2010/061729
Other languages
French (fr)
Japanese (ja)
Inventor
羽場康弘
山原基裕
Original Assignee
住友化学株式会社
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Application filed by 住友化学株式会社 filed Critical 住友化学株式会社
Priority to CN2010800299992A priority Critical patent/CN102472841A/en
Publication of WO2011004898A1 publication Critical patent/WO2011004898A1/en

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/02—Diffusing elements; Afocal elements
    • G02B5/0205—Diffusing elements; Afocal elements characterised by the diffusing properties
    • G02B5/0236—Diffusing elements; Afocal elements characterised by the diffusing properties the diffusion taking place within the volume of the element
    • G02B5/0242—Diffusing elements; Afocal elements characterised by the diffusing properties the diffusion taking place within the volume of the element by means of dispersed particles
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/02—Diffusing elements; Afocal elements
    • G02B5/0205—Diffusing elements; Afocal elements characterised by the diffusing properties
    • G02B5/021—Diffusing elements; Afocal elements characterised by the diffusing properties the diffusion taking place at the element's surface, e.g. by means of surface roughening or microprismatic structures
    • G02B5/0221—Diffusing elements; Afocal elements characterised by the diffusing properties the diffusion taking place at the element's surface, e.g. by means of surface roughening or microprismatic structures the surface having an irregular structure
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/04—Prisms
    • G02B5/045—Prism arrays
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0013—Means for improving the coupling-in of light from the light source into the light guide
    • G02B6/0023—Means for improving the coupling-in of light from the light source into the light guide provided by one optical element, or plurality thereof, placed between the light guide and the light source, or around the light source
    • G02B6/0025—Diffusing sheet or layer; Prismatic sheet or layer
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0033—Means for improving the coupling-out of light from the light guide
    • G02B6/005—Means for improving the coupling-out of light from the light guide provided by one optical element, or plurality thereof, placed on the light output side of the light guide
    • G02B6/0051—Diffusing sheet or layer
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0033—Means for improving the coupling-out of light from the light guide
    • G02B6/005—Means for improving the coupling-out of light from the light guide provided by one optical element, or plurality thereof, placed on the light output side of the light guide
    • G02B6/0053—Prismatic sheet or layer; Brightness enhancement element, sheet or layer
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/133504—Diffusing, scattering, diffracting elements
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/1336—Illuminating devices
    • G02F1/133602—Direct backlight
    • G02F1/133606—Direct backlight including a specially adapted diffusing, scattering or light controlling members
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/13356—Structural association of cells with optical devices, e.g. polarisers or reflectors characterised by the placement of the optical elements
    • G02F1/133562—Structural association of cells with optical devices, e.g. polarisers or reflectors characterised by the placement of the optical elements on the viewer side

Definitions

  • the present invention relates to a light diffusion film and a liquid crystal display device including the same.
  • liquid crystal display devices In recent years, the use of liquid crystal display devices is rapidly advancing and is used in mobile phones, personal computer monitors, televisions, liquid crystal projectors, and the like.
  • a liquid crystal display device operates a liquid crystal in a display mode such as a TN (Twisted Nematic) mode, a VA (Vertical Alignment) mode, an IPS (In-Plane Switching) mode, and electrically transmits light passing through the liquid crystal.
  • a display mode such as a TN (Twisted Nematic) mode, a VA (Vertical Alignment) mode, an IPS (In-Plane Switching) mode, and electrically transmits light passing through the liquid crystal.
  • TN Transmission Nematic
  • VA Very Alignment
  • IPS In-Plane Switching
  • the liquid crystal display device has a viewing angle dependency problem in that when the display screen is viewed from an oblique direction, the display characteristics deteriorate due to a decrease in contrast or a gradation inversion phenomenon in which the brightness is reversed in gradation display. .
  • a light diffusing film having a high haze light diffusing layer obtained by coating a resin containing fine particles on a transparent substrate and curing is used to widen the viewing angle (for example, JP2007-94369-A and JP2000-352607-A). ).
  • a light diffusing film has too high light diffusibility, so that the contrast of the display image is lowered.
  • a light diffusion film containing fine particles in the resin coating layer and having fine irregularities on the surface of the resin coating layer is also known (for example, JP2008-152268-A and JP2000-121809-A).
  • JP2008-152268-A and JP2000-121809-A have a low light diffusibility and cannot sufficiently widen the viewing angle.
  • An object of the present invention is to provide a light diffusion film having a high front contrast and a wide viewing angle without causing scintillation, and a display device equipped with the light diffusion film.
  • a light diffusing film comprising a base film, a translucent resin and a translucent fine particle dispersed in the translucent resin, and a light diffusing layer having a flat surface
  • the translucent fine particles have an average particle size of 0.5 ⁇ m or more and less than 20 ⁇ m
  • the content of the translucent fine particles is 25 parts by weight or more and 60 parts by weight or less with respect to 100 parts by weight of the translucent resin
  • the refractive index of the translucent fine particles is larger than the refractive index of the translucent resin
  • the difference between the refractive index of the translucent fine particles and the refractive index of the translucent resin is 0.04 or more and 0.2 or less
  • the light diffusion layer has a thickness of 1 to 3 times the average particle diameter of the light-transmitting fine particles.
  • the first polarizing plate and the second polarizing plate are liquid crystal display devices arranged such that their transmission axes have a crossed Nicols relationship, wherein the light diffusion film is [1] to [3 ]
  • the liquid crystal display device which is a light-diffusion film in any one of.
  • the light deflecting means includes two prism films each having a plurality of linear prism portions having ridge lines on the light emitting side at a predetermined interval on the light emitting surface side, and one prism film is the linear prism.
  • the other prism film is arranged such that the direction of the ridgeline of the linear prism is substantially parallel to the transmission axis of the first polarizing plate, and the direction of the ridgeline of the linear prism is the transmission axis of the second polarizing plate.
  • the liquid crystal display device according to [4] or [5] which is disposed so as to be substantially parallel to the surface.
  • the average particle diameter of the light-transmitting fine particles is a weight average particle diameter that can be stopped by Coulter Multisizer (manufactured by Beckman Coulter, Inc.) based on the Coulter principle (pore electrical resistance method).
  • the “light emitting side” is a side from which light incident from a light source such as a backlight is emitted when a light diffusion film or the like is installed in a liquid crystal display device (opposite side of the light source). It is the side close to. Conversely, the side on which light is incident from a light source such as a backlight may be referred to as the “light incident side”.
  • substantially parallel to the transmission axis of the first polarizing plate means an angle with respect to the transmission axis when parallel to the transmission axis of the first polarizing plate and within a range not impairing the effects of the present invention. (For example, 15 degrees or less) is included, and the case where it is parallel is the most preferable.
  • substantially parallel to the transmission axis of the second polarizing plate means that the transmission axis is parallel to the transmission axis of the second polarizing plate and within a range not impairing the effects of the present invention. The meaning includes the case of having an angle (for example, 15 ° or less), and the case of being parallel is the most preferable.
  • the light diffusing film 7 in FIG. 1 includes a light transmissive resin 721 and light transmissive fine particles 722 dispersed in the light transmissive resin on one surface side of a base film 71, and a light diffusing layer 72 having a flat surface. Are laminated.
  • the translucent fine particles 722 used here have an average particle size of 0.5 ⁇ m or more and less than 20 ⁇ m, and the blending amount in the translucent resin 721 is 25 parts by weight or more and 60 parts by weight with respect to 100 parts by weight of the translucent resin. Or less.
  • the average particle size and blending amount of the translucent resin 721 within the above ranges, excellent light diffusibility can be obtained without causing a decrease in front contrast.
  • high transparency of the transmitted image can be obtained.
  • the preferable average particle diameter of the light-transmitting fine particles 722 is 4 to 8 ⁇ m, and the preferable blending amount is 30 to 40 parts by weight.
  • the translucent fine particles 722 used in the present invention are not particularly limited as long as they have the above average particle diameter and translucency, and conventionally known ones can be used.
  • organic fine particles such as acrylic resin, melamine resin, polyethylene, polystyrene, organic silicone resin, acrylic-styrene copolymer, and calcium carbonate, silica, aluminum oxide, barium carbonate, barium sulfate, titanium oxide, glass, etc.
  • Inorganic fine particles and the like Each of these may be used alone or in combination with one or more other.
  • Organic polymer balloons and glass hollow beads can also be used.
  • the shape of the translucent fine particles may be any of a spherical shape, a flat shape, a plate shape, a needle shape, etc., but a spherical shape is particularly desirable.
  • the refractive index of the translucent fine particles 722 is set larger than the refractive index of the translucent resin 721, and the difference is 0.04 or more and 0.2 or less, and the range of 0.04 to 0.15 is set. preferable.
  • the difference in refractive index between the translucent fine particles 722 and the translucent resin 721 within the above range, the translucent fine particles 722 and the translucent resin 721 are made of light incident on the light diffusion layer 72. Internal scattering due to the difference in refractive index can be expressed, and the occurrence of scintillation can be suppressed.
  • the translucent resin 721 used in the present invention is not particularly limited as long as it has translucency.
  • ionizing radiation curable resins such as ultraviolet curable resins and electron beam curable resins, and thermosetting types. Resins, thermoplastic resins, metal alkoxides, and the like can be used. Of these, plastic resins are used as they are.
  • curable resins such as ionizing radiation curable resins and thermosetting resins such as ultraviolet curable resins and electron beam curable resins
  • curable resins are ionized radiation, heat, etc.
  • the metal alkoxide is used after being converted into a cured product by hydrolysis, dehydration condensation or the like.
  • ionizing radiation curable resins are preferably used from the viewpoint of high hardness and imparting sufficient scratch resistance to the light diffusion film provided on the display surface.
  • ionizing radiation curable resins are polyfunctional acrylates such as polyhydric alcohol acrylic esters or methacrylic esters, and polyfunctional compounds synthesized from diisocyanates and polyhydric alcohols and hydroxy esters of acrylic acid or methacrylic acid.
  • polyfunctional acrylates such as polyhydric alcohol acrylic esters or methacrylic esters
  • urethane acrylate polyether resins having an acrylate functional group, polyester resins, epoxy resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol polyene resins, and the like can also be used.
  • a photopolymerization initiator when an ultraviolet curable resin is used, a photopolymerization initiator is added. It is preferable to use a photopolymerization initiator suitable for the resin used.
  • a photopolymerization initiator radiation polymerization initiator
  • benzoin such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzyl methyl ketal, and alkyl ethers thereof are used.
  • the amount of the photopolymerization initiator used is usually 0.5 to 20 parts by mass with respect to 100 parts by mass of the resin. The amount is preferably 1 to 5 parts by mass.
  • thermosetting resin examples include thermosetting urethane resin composed of acrylic polyol and isocyanate prepolymer, phenol resin, urea melamine resin, epoxy resin, unsaturated polyester resin, and silicone resin.
  • thermoplastic resin examples include cellulose derivatives such as acetylcellulose, nitrocellulose, acetylbutylcellulose, ethylcellulose and methylcellulose, vinyl acetate and copolymers thereof, vinyl chloride and copolymers thereof, vinylidene chloride and copolymers thereof and the like.
  • Resin, acetal resin such as polyvinyl formal, polyvinyl butyral, acrylic resin and its copolymer, acrylic resin such as methacrylic resin and its copolymer, polystyrene resin, polyamide resin, linear polyester resin, polycarbonate resin, etc. it can.
  • a silicon oxide matrix made of a silicon alkoxide material can be used. Specific examples include tetramethoxysilane and tetraethoxysilane, and a cured product in which an inorganic or organic-inorganic composite matrix is formed by hydrolysis and dehydration condensation can be used.
  • the translucent resin 721 When an ionizing radiation curable resin is used as the translucent resin 721, it is necessary to irradiate the base film 71 with ionizing radiation such as ultraviolet rays and electron beams after being applied and dried.
  • ionizing radiation such as ultraviolet rays and electron beams
  • the substrate film 71 may be heated after being applied and dried.
  • the layer thickness of the light diffusion layer 72 is 1 to 3 times the average particle diameter of the translucent fine particles 722.
  • the texture of the light diffusion film 7 to be obtained becomes rough and scintillation easily occurs and the visibility of the display surface decreases. To do.
  • the layer thickness of the light diffusion layer 72 is thicker than three times the average particle diameter of the light-transmitting fine particles 722, the light diffusion becomes too strong and the contrast is lowered, so that the display quality is lowered.
  • the layer thickness of the light diffusion layer 72 is usually preferably 5 to 25 ⁇ m. When the thickness of the light diffusion layer 72 is less than 5 ⁇ m, sufficient scratch resistance sufficient to be provided on the display surface may not be obtained. On the other hand, when the thickness of the light diffusion layer 72 is greater than 25 ⁇ m, the light diffusion layer 72 is manufactured. The degree of curling of the light diffusing film 7 is increased, and the handleability may be deteriorated.
  • any material may be used as long as it is translucent.
  • glass or plastic film can be used.
  • the plastic film only needs to have appropriate transparency and mechanical strength. Examples include cellulose acetate resins such as TAC (triacetyl cellulose), acrylic resins, polycarbonate resins, and polyester resins such as polyethylene terephthalate.
  • the light diffusion film 7 of the present invention can be produced, for example, as follows.
  • a solvent liquid such as an ionizing radiation curable resin, a thermosetting resin, a thermoplastic resin, or a metal alkoxide, in which the light transmitting fine particles 722 are dispersed, is formed on the base film 71.
  • the light diffusion layer 72 having a flat surface is formed on the surface of the base film 71 so that the light-transmitting fine particles 722 do not appear on the surface of the coating film by adjusting the coating thickness.
  • the dispersion of the translucent fine particles 722 in the resin liquid is preferably isotropic dispersion.
  • the resin may be used as it is without adding a solvent. it can.
  • a method of performing a surface treatment on the light diffusion layer 72 using a roll having a mirror mold surface is used in the manufacturing process of the light diffusion layer 72. Can do.
  • the degree of flatness of the light diffusion layer 72 can be represented by external haze, and is preferably 1% or less, more preferably 0.5% or less.
  • the solvent used for the resin liquid examples include alcohols such as ethanol, glycol ethers such as propylene glycol monomethyl ether, esters such as ethyl acetate and propylene glycol monomethyl ether acetate, ketones such as methyl ethyl ketone, and carbonization such as toluene.
  • alcohols such as ethanol
  • glycol ethers such as propylene glycol monomethyl ether
  • esters such as ethyl acetate and propylene glycol monomethyl ether acetate
  • ketones such as methyl ethyl ketone
  • carbonization such as toluene.
  • Including hydrogen and alkyl halides such as methylene chloride.
  • the base film 71 may be subjected to a surface treatment before application of the resin liquid in order to improve coatability and adhesiveness with the light diffusion layer.
  • a surface treatment include corona discharge treatment, glow discharge treatment, acid treatment, alkali treatment, and ultraviolet irradiation treatment.
  • the base film 71 and the polarizer 61 are effectively used.
  • the base film 71 is hydrophilized by acid treatment or alkali treatment.
  • a gravure coating method for example, a gravure coating method, a micro gravure coating method, a roll coating method, a rod coating method, a knife coating method, an air knife coating method, a kiss coating method, and a die coating method. Etc. can be used.
  • the solvent is dried by heating if necessary.
  • ionizing radiation curable resin, thermosetting resin, metal alkoxide, or the like is used, the coating film is further cured by ionizing radiation and / or heat.
  • the ionizing radiation species can be appropriately selected from ultraviolet rays, electron beams, near ultraviolet rays, visible light, near infrared rays, infrared rays, X-rays, etc., depending on the type of translucent resin 721, preferably ultraviolet rays and electron beams.
  • ultraviolet rays are preferable because they are easy to handle and high energy can be easily obtained.
  • any light source that generates ultraviolet light can be used.
  • a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, or the like can be used.
  • An ArF excimer laser, a KrF excimer laser, an excimer lamp, synchrotron radiation, or the like can also be used.
  • an ultrahigh pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a carbon arc, a xenon arc, and a metal halide lamp can be preferably used.
  • an electron beam can be used in the same manner.
  • the electron beam is usually 50 to 1000 keV, preferably 100, emitted from various electron beam accelerators such as cockroft walton type, bandegraph type, resonance transformer type, insulated core transformer type, linear type, dynamitron type, and high frequency type.
  • An electron beam having an energy of ⁇ 300 keV can be mentioned.
  • the base film 71 wound in a roll shape is used. Winding the light diffusion film 7 on which the cured light diffusion layer 72 is formed, the step of applying and drying the resin solution in which the translucent fine particles 722 are dispersed, the step of curing the coating film, It is preferable to use a manufacturing method having a step of taking.
  • a curable resin such as an ionizing radiation curable resin or an electron beam curable resin
  • FIG. 2 Another embodiment of the light diffusion film of the present invention is shown in FIG.
  • the light diffusing film 7 shown in FIG. 2 is obtained by further laminating a light transmissive resin layer 73 on a light diffusing layer 72 in which light transmissive fine particles 722 are dispersed and mixed in a light transmissive resin 721.
  • the light diffusion film of the present invention preferably further has an antireflection layer on the side surface opposite to the base film of the light diffusion layer.
  • the antireflection layer is a layer that is given a function by controlling the refractive index and thickness of each layer, such as by increasing the refractive index of the hard coat layer and providing a thin film of low refractive index on the hard coat layer. By making it as low as possible, it is possible to prevent external objects from being reflected on the display screen.
  • FIG. 3 An example of a polarizing plate using the light diffusion film of the present invention is shown in FIG.
  • a general polarizing plate has a structure in which a support film 62 is bonded to both sides of a polarizer 61.
  • the polarizing plate shown in FIG. 3 uses the light diffusion film 7 of the present invention as one support film. It is a multifunctional film having a polarizing function and an antiglare (light diffusion) function. That is, the support film 62 is attached to one surface of the polarizer 61, and the light diffusion film 7 in which the light diffusion layer 72 is formed on the base film 71 is attached to the other surface.
  • the polarizing plate having such a configuration is attached to the liquid crystal display device, the polarizing plate is attached to a glass substrate of the liquid crystal display panel so that the light diffusion film 7 is on the light emitting side.
  • the base film 71 and the polarizer 61 may be bonded together via an adhesive layer, it is preferable to directly bond them without using an adhesive layer.
  • FIG. 4 is a schematic view showing an example of a liquid crystal display device according to the present invention.
  • the liquid crystal display device of FIG. 4 is a normally white mode TN liquid crystal display device, which includes a backlight device 2, a light diffusing plate 3, two prism films 4a and 4b as light deflecting means, and a first polarized light.
  • the liquid crystal cell 1 in which the liquid crystal layer 12 is provided between the plate 5 and the pair of transparent substrates 11a and 11b, the second polarizing plate 6, and the light diffusion film 7 are arranged in this order.
  • the 1st polarizing plate 5 and the 2nd polarizing plate 6 are arrange
  • Each of the two prism films 4a and 4b has a flat surface on the light incident side, and a plurality of linear prism portions 41a and 41b formed in parallel on the surface on the light emitting side. 41a and 41b have ridge lines 42a and 42b on the light emitting side.
  • the prism film 4a is arranged so that the ridge line of the linear prism part 41a is substantially parallel to the transmission axis direction of the first polarizing plate 5, and the prism film 4b is ridge line of the linear prism part 41b.
  • the cross-sectional shape in the vertical cross section orthogonal to the ridge lines of the linear prism portions 41a and 41b is a triangle, and the apex angle ⁇ of the apex corresponding to the ridge line among the apexes of the triangle is 90 ° to 110 °.
  • a range is preferable.
  • this triangle may have either an equal side or an unequal side, and when concentrating in the front direction (normal direction of the display surface of the liquid crystal display device), It is preferable that the two sides are equal isosceles triangles.
  • a plurality of linear prism portions 41a and 42a having such an isosceles triangular cross section are sequentially arranged such that the bases corresponding to the apex angle ⁇ of the triangle are adjacent to each other, and a plurality of linear prisms are arranged.
  • the ridgelines 42a and 42b of the prism portions 41a and 42a are arranged so as to be substantially parallel to each other.
  • the triangles of the cross-sectional shapes of the linear prism portions 41a and 42a may have a curved shape at each vertex.
  • the distance between the vertices is usually in the range of 10 ⁇ m to 500 ⁇ m, and preferably in the range of 30 ⁇ m to 200 ⁇ m.
  • the light emitted from the backlight device 2 is diffused by the light diffusion plate 3 and then enters the prism film 4a.
  • a vertical cross section perpendicular to the transmission axis direction of the first polarizing plate 5 light incident obliquely with respect to the lower surface of the prism film 4a is emitted with its path changed in the front direction.
  • the prism film 4b in the vertical cross section perpendicular to the transmission axis direction of the second polarizing plate 6, the light incident obliquely with respect to the lower surface of the prism film 4b changes its course in the front direction as described above. Is emitted. Therefore, the light passing through the two prism films 4a and 4b is condensed in the front direction in any vertical cross section, and the luminance in the front direction is improved.
  • the light having directivity in the front direction is changed from circularly polarized light to linearly polarized light by the first polarizing plate 5 and enters the liquid crystal cell 1.
  • the light incident on the liquid crystal cell 1 is emitted from the liquid crystal cell 1 with its polarization plane controlled for each pixel by the orientation of the liquid crystal layer 12 controlled by the electric field.
  • the light emitted from the liquid crystal cell 1 is imaged by the second polarizing plate 6, passes through the light diffusion film 7, and exits to the display surface side.
  • the light diffusing film is disposed so that the light diffusing layer is closer to the light emitting side than the base film.
  • the directivity of the light incident on the liquid crystal cell 1 in the front direction is higher than before by the two prism films 4a and 4b.
  • the brightness in the front direction is improved as compared with the conventional apparatus.
  • the above-mentioned light diffusion film 7 is used, excellent light diffusibility and high transmitted image definition can be obtained without causing a decrease in front contrast.
  • a liquid crystal is sealed between a pair of transparent substrates 11a and 11b arranged to face each other at a predetermined distance by a spacer (not shown), and the pair of transparent substrates 11a and 11b.
  • the liquid crystal layer 12 is provided.
  • a transparent electrode and an alignment film are laminated on each of the pair of transparent substrates 11a and 11b, and the liquid crystal is formed by applying a voltage based on display data between the transparent electrodes.
  • the display method of the liquid crystal cell 1 is the TN method, but a display method such as an IPS method or a VA method may be adopted.
  • the backlight device 2 includes a rectangular parallelepiped case 21 having an upper surface opening, and a plurality of cold cathode tubes 22 serving as linear light sources arranged in parallel in the case 21.
  • the case 21 is formed from a resin material or a metal material, and at least the case inner peripheral surface is preferably white or silver from the viewpoint of reflecting the light emitted from the cold cathode tube 22 on the case inner peripheral surface.
  • a light source in addition to a cold cathode tube, a hot cathode tube, a linearly arranged LED, and the like can be used.
  • the number of the linear light sources to be arranged is not particularly limited, but the distance between the centers of the adjacent linear light sources is in a range of 15 to 150 mm from the viewpoint of suppressing luminance unevenness on the light emitting surface. It is preferable to do so.
  • the backlight device 2 used in the present invention is not limited to the direct type shown in FIG. 4, but is a side-ride type in which a linear light source or a point light source is arranged on the side surface of the light guide plate, or a light source.
  • the light diffusing plate 3 includes a base material in which a diffusing agent is dispersed and mixed.
  • a base material polycarbonate, methacrylic resin, methyl methacrylate-styrene copolymer resin, acrylonitrile-styrene copolymer resin, methacrylic acid- Styrene copolymer resins, polyolefins such as polystyrene, polyvinyl chloride, polypropylene, polymethylpentene, cyclic polyolefins, polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyamide resins, polyarylate, polyimide, etc. Can be used.
  • the diffusing agent mixed and dispersed in the base material is fine particles made of a material having a refractive index different from that of the base material, and specific examples include acrylic resins and melamine resins of a different type from the base material.
  • Organic fine particles such as polyethylene, polystyrene, organic silicone resin, acrylic-styrene copolymer, and inorganic fine particles such as calcium carbonate, silica, aluminum oxide, barium carbonate, barium sulfate, titanium oxide, and glass. One of them is used alone or in combination with one or more other.
  • Organic polymer balloons and glass hollow beads can also be used as the diffusing agent.
  • the average particle diameter of the diffusing agent is preferably in the range of 0.5 to 30 ⁇ m. Further, the shape of the diffusing agent may be not only spherical but also flat, plate-like, and needle-like.
  • the light incident surface side is a flat surface, and a plurality of linear prisms having a triangular cross section are formed in parallel on the light output surface side.
  • the material of the prism films 4a and 4b include polycarbonate resin, ABS resin, methacrylic resin, methyl methacrylate-styrene copolymer resin, polystyrene resin, acrylonitrile-styrene copolymer resin, polyolefin resin such as polyethylene / polypropylene, Alternatively, ionizing radiation curable resins such as ultraviolet curable resins and electron beam curable resins can be used.
  • the prism film can be produced by a known method such as a profile extrusion method, a press molding method, an injection molding method, a roll transfer method, a laser ablation method, a mechanical cutting method, a mechanical grinding method, or a photopolymer process method. It can. Each of these methods may be used alone, or two or more methods may be combined. Further, a light diffusing agent may be dispersed in these prism sheets.
  • the thickness of the prism films 4a and 4b is usually 0.1 to 15 mm, preferably 0.5 to 10 mm.
  • polarizers are those obtained by adsorbing and orienting dichroic dyes or iodine on polarizer substrates such as polyvinyl alcohol resins, polyvinyl acetate resins, ethylene / vinyl acetate (EVA) resins, polyamide resins, and polyester resins. And a polyvinyl alcohol / polyvinylene copolymer containing an oriented molecular chain of a dichroic dehydrated product of polyvinyl alcohol (polyvinylene) in a molecularly oriented polyvinyl alcohol film.
  • a polarizer substrate made of polyvinyl alcohol resin obtained by adsorbing and orienting a dichroic dye or iodine is preferably used as the polarizer.
  • the thickness of the polarizer is not particularly limited, but is generally preferably 100 ⁇ m or less, more preferably 10 to 50 ⁇ m, still more preferably 25 to 35 ⁇ m for the purpose of reducing the thickness of the polarizing plate.
  • a film made of a polymer having low birefringence, excellent transparency, mechanical strength, thermal stability, moisture shielding property and the like is preferable.
  • films include cellulose acetate resins such as TAC (triacetyl cellulose), acrylic resins, fluorine resins such as tetrafluoroethylene / hexafluoropropylene copolymers, polycarbonate resins, polyethylene terephthalate, etc.
  • a triacetyl cellulose film or a norbornene-based thermoplastic resin film whose surface is saponified with an alkali or the like can be preferably used from the viewpoints of polarization characteristics and durability.
  • the norbornene-based thermoplastic resin film is particularly suitable because the film is a good barrier from heat and wet heat, so the durability of the polarizing plate is greatly improved and the dimensional stability is greatly improved due to its low moisture absorption rate.
  • a conventionally known method such as a casting method, a calendar method, or an extrusion method can be used.
  • the thickness of the support film is not limited, but is usually preferably 500 ⁇ m or less, more preferably 5 to 300 ⁇ m, still more preferably 5 to 150 ⁇ m from the viewpoint of thinning the polarizing plate.
  • FIG. 6 shows another embodiment of the liquid crystal display device of the present invention.
  • the liquid crystal display device of FIG. 6 is different from the liquid crystal display device of FIG. 4 in that a phase difference plate 8 is disposed between the first polarizing plate 5 and the liquid crystal cell 1.
  • This phase difference plate 8 has a substantially zero phase difference in a direction perpendicular to the surface of the liquid crystal cell 1, has no optical effect from the front, and has a phase difference when viewed from an oblique direction. It is intended to compensate for the phase difference that occurs and occurs in the liquid crystal cell 1. As a result, a wider viewing angle can be obtained, and better display quality and color reproducibility can be obtained.
  • the phase difference plate 8 can be disposed between the first polarizing plate 5 and the liquid crystal cell 1 and at one or both between the second polarizing plate 6 and the liquid crystal cell 1.
  • phase difference plate 8 examples include those obtained by using a polycarbonate resin or a cyclic olefin polymer resin as a film and further biaxially stretching the film, or a liquid crystal monomer having a molecular arrangement fixed by a photopolymerization reaction. Since the phase difference plate 8 optically compensates the alignment of the liquid crystal, the retardation plate 8 having a refractive index characteristic opposite to that of the liquid crystal alignment is used.
  • a TN mode liquid crystal display cell for example, “WV film” (manufactured by Fuji Film Co., Ltd.), and for an STN mode liquid crystal display cell, for example, “LC film” (manufactured by Nippon Oil Corporation), IPS
  • a biaxial retardation film for a mode liquid crystal cell, and for a VA mode liquid crystal cell for example, a retardation plate combining an A plate and a C-plate, a biaxial retardation film, a ⁇ cell mode liquid crystal cell
  • “OCV WV film” manufactured by Fuji Film Co., Ltd.
  • Example 1 Production of mirror surface mold Industrial chrome plating is performed on the surface of a 200 mm diameter iron roll (STKM13A by JIS), and then the surface of the mold is mirror polished using this iron roll to produce a mirror mold. did.
  • the Vickers hardness of the chromium plating surface of the obtained mold was 1000.
  • the Vickers hardness was measured according to JIS Z 2244 using an ultrasonic hardness tester MIC10 (manufactured by Krautkramer) (the measurement method of Vickers hardness is the same in the following examples).
  • Pentaerythritol triacrylate 60 parts by mass
  • polyfunctional urethanized acrylate reaction product of hexamethylene diisocyanate and pentaerythritol triacrylate, 40 parts by mass
  • pentaerythritol triacrylate 40 parts by mass
  • the refractive index of the cured product after removing propylene glycol monomethyl ether from the composition and curing with ultraviolet rays was 1.53.
  • polystyrene particles having a weight average particle diameter of 12.0 ⁇ m (SBX-12 manufactured by Sekisui Plastics Co., Ltd.) are used as translucent fine particles.
  • 30 parts by mass 5 parts by mass of “Lucirin TPO” (manufactured by BASF Corp., chemical name: 2,4,6-trimethylbenzoyldiphenylphosphine oxide) as a photopolymerization initiator is added, and the solid content is 60% by mass.
  • a coating solution was prepared by diluting with propylene glycol monomethyl ether.
  • This coating solution was coated on a 80 ⁇ m thick triacetyl cellulose (TAC) film (base film) and dried for 1 minute in a dryer set at 80 ° C.
  • TAC triacetyl cellulose
  • the dried base film was brought into close contact with the mirror surface of the mold produced in (1) above with a rubber roll so that the ultraviolet curable resin composition layer was on the mold side.
  • light from a high-pressure mercury lamp with an intensity of 20 mW / cm 2 is irradiated from the base film side so as to be 300 mJ / cm 2 in terms of the amount of h-ray to cure the ultraviolet curable resin composition layer
  • Example 2 A light diffusing film was produced in the same manner as in Example 1 except that 35 parts by mass of polystyrene-based particles (SBX-6 manufactured by Sekisui Plastics Co., Ltd.) having a weight average particle size of 6.0 ⁇ m were used as the translucent fine particles. did.
  • SBX-6 polystyrene-based particles manufactured by Sekisui Plastics Co., Ltd.
  • Comparative Example 1 A light diffusion film was produced in the same manner as in Example 1 except that 10 parts by mass of polystyrene-based particles having a weight average particle size of 6.0 ⁇ m (SBX-6 manufactured by Sekisui Plastics Co., Ltd.) were used as the light-transmitting fine particles. did.
  • Comparative Example 2 A light diffusion film was prepared in the same manner as in Example 1 except that 80 parts by mass of polystyrene-based particles having a weight average particle size of 6.0 ⁇ m (SBX-6 manufactured by Sekisui Plastics Co., Ltd.) were used as the light-transmitting fine particles. did.
  • Comparative Example 3 Light diffusion in the same manner as in Example 1 except that 40 parts by mass of styrene-methyl methacrylate copolymer particles (manufactured by Sekisui Plastics Co., Ltd.) having a weight average particle size of 6.0 ⁇ m were used as translucent fine particles. A film was prepared.
  • Weight average particle diameter of translucent fine particles The weight average particle diameter of the light-transmitting fine particles used in Examples 1 and 2 and Comparative Examples 1 to 3 was measured using a Coulter Multisizer (manufactured by Beckman Coulter, Inc.) based on the Coulter principle (pore electrical resistance method). did.
  • the layer thicknesses of the light diffusion films obtained in Examples 1 and 2 and Comparative Examples 1 to 3 were measured using DIGIMICRO MH-15 (main body) and ZC-101 (counter) manufactured by NIKON. The thickness of the light diffusion layer was determined by subtracting the material thickness of 80 ⁇ m.
  • the sample In order to prevent the sample from warping, it was bonded to a glass substrate using an optically transparent adhesive so that the second light diffusion layer was on the surface, and the total haze was measured in that state.
  • the measurement of the internal haze was performed in the same manner as the measurement of the total haze by sticking a triacetyl cellulose film having a haze of almost 0 to the film surface with glycerin to eliminate the influence of the outside of the film.
  • the direction is arranged so that the direction is substantially parallel to the transmission axis of the first polarizing plate, and the other prism film is arranged so that the direction of the ridge line of the linear prism is substantially parallel to the transmission axis of the second polarizing plate.
  • the polarizing plate on the light emitting surface side of the liquid crystal cell was peeled off, and an iodine-based normal polarizing plate “TRW842AP7” (manufactured by Sumitomo Chemical Co., Ltd.) was bonded so as to be crossed Nicol. 2 and Comparative Examples 1 to 3 were bonded together to produce a liquid crystal display device.
  • the front contrast was measured using the luminance meter "BM5A” type
  • the display quality as viewed from the direction in which the viewing angle (angle formed with the front direction of the liquid crystal display device) is 40 °, 50 °, and 60 ° was evaluated.
  • Table 2 shows the measurement results of the front contrast
  • Table 3 shows the evaluation results of the viewing angles for the liquid crystal display devices using the light diffusion films of Examples 1 and 2 and Comparative Examples 1 to 3.
  • Comparative Example 1 since the blending amount of the translucent particles in the light diffusion layer is small, the light diffusion is weak and the front contrast is high, but the viewing angle is narrow. In Comparative Example 2, the amount of translucent particles in the light diffusion layer is too large, so that the light diffusibility is too strong and the viewing angle is wide, but the front contrast is greatly reduced. In Comparative Example 3, since the difference in refractive index between the translucent resin used for the light diffusion layer and the translucent particles is small, the light diffusion is weak and the front contrast is high, but the viewing angle is narrow.
  • the liquid crystal display device including the light diffusion film of the present invention has little front scintillation, high front contrast, and wide viewing angle.

Abstract

Disclosed is a light diffusion film which comprises a base film and a light diffusion layer that has a flat surface and is composed of a light-transmitting resin and light-transmitting fine particles dispersed in the light-transmitting resin. The light diffusion film has high front contrast and wide viewing angle without suffering from scintillation. The light-transmitting fine particles have an average particle diameter of 0.5 μm or more but less than 20 μm, and are contained in an amount of 25-60 parts by weight (inclusive) per 100 parts by weight of the light-transmitting resin. The refractive index of the light-transmitting fine particles is larger than the refractive index of the light-transmitting resin, and the difference between the refractive index of the light-transmitting fine particles and the refractive index of the light-transmitting resin is 0.04-0.2 (inclusive). The thickness of the light diffusion layer is 1-3 times (inclusive) the average particle diameter of the light-transmitting fine particles. Also disclosed is a liquid crystal display device which is provided with the light diffusion film.

Description

光拡散フィルムおよびそれを含む液晶表示装置Light diffusion film and liquid crystal display device including the same
　本発明は光拡散フィルムおよびそれを含む液晶表示装置に関するものである。 The present invention relates to a light diffusion film and a liquid crystal display device including the same.
　近年、液晶表示装置は、その用途展開が急速に進んでおり、携帯電話、パソコン用モニタ、テレビ、液晶プロジェクタなどに使われている。 In recent years, the use of liquid crystal display devices is rapidly advancing and is used in mobile phones, personal computer monitors, televisions, liquid crystal projectors, and the like.
　一般に、液晶表示装置は、ＴＮ（Ｔｗｉｓｔｅｄ　Ｎｅｍａｔｉｃ）モード、ＶＡ（Ｖｅｒｔｉｃａｌ　Ａｌｉｇｎｍｅｎｔ）モード、ＩＰＳ（Ｉｎ−Ｐｌａｎｅ　Ｓｗｉｔｃｈｉｎｇ）モードなどの表示モードで液晶を動作させて、該液晶を通過する光を電気的に制御して明暗の違いを画面上に表すことで、文字や画像を表現する液晶表示装置である。 Generally, a liquid crystal display device operates a liquid crystal in a display mode such as a TN (Twisted Nematic) mode, a VA (Vertical Alignment) mode, an IPS (In-Plane Switching) mode, and electrically transmits light passing through the liquid crystal. This is a liquid crystal display device that expresses characters and images by controlling the difference between light and dark on the screen.
　液晶表示装置は、斜め方向から表示画面を見た場合に、コントラストの低下や階調表示で明るさが逆転する階調反転現象等による表示特性の悪化が生じるという視野角依存性の問題がある。 The liquid crystal display device has a viewing angle dependency problem in that when the display screen is viewed from an oblique direction, the display characteristics deteriorate due to a decrease in contrast or a gradation inversion phenomenon in which the brightness is reversed in gradation display. .
　上記問題点を解決するため、従来より、光拡散手段、例えば、光拡散層を設けて、視野角依存性の問題を改善する方法が提案されている。 In order to solve the above problems, conventionally, there has been proposed a method for improving the viewing angle dependency problem by providing a light diffusion means, for example, a light diffusion layer.
　微粒子を含む樹脂を透明基材に塗工して硬化した高ヘイズの光拡散層を有する光拡散フィルムが視野角を広げるために使用される（例えば、ＪＰ２００７−９４３６９−ＡおよびＪＰ２０００−３５２６０７−Ａ）。しかし、このような光拡散フィルムでは光拡散性が強すぎるため、表示画像のコントラストが低下する。 A light diffusing film having a high haze light diffusing layer obtained by coating a resin containing fine particles on a transparent substrate and curing is used to widen the viewing angle (for example, JP2007-94369-A and JP2000-352607-A). ). However, such a light diffusing film has too high light diffusibility, so that the contrast of the display image is lowered.
　樹脂被膜層に微粒子を含有し、かつ樹脂被膜層の表面に微細凹凸を有する光拡散フィルムも知られている（例えば、ＪＰ２００８−１５２２６８−ＡおよびＪＰ２０００−１２１８０９−Ａ）。しかし、このような光拡散フィルムでは光拡散性が弱く、十分に視野角を広げることができない。 A light diffusion film containing fine particles in the resin coating layer and having fine irregularities on the surface of the resin coating layer is also known (for example, JP2008-152268-A and JP2000-121809-A). However, such a light diffusing film has a low light diffusibility and cannot sufficiently widen the viewing angle.
　本発明は、シンチレーションが生じることなく正面コントラストが高く、且つ視野角の広い光拡散フィルム、および、当該光拡散フィルムが装着されている表示装置を提供することを目的とする。 An object of the present invention is to provide a light diffusion film having a high front contrast and a wide viewing angle without causing scintillation, and a display device equipped with the light diffusion film.
　本発明は、以下のものを含む。
［１］　基材フィルムと、透光性樹脂及び透光性樹脂中に分散された透光性微粒子からなり、表面が平坦な光拡散層とを有する光拡散フィルムであって、
　上記透光性微粒子の平均粒径が０．５μｍ以上２０μｍ未満であり、
　上記透光性微粒子の含有量が上記透光性樹脂１００重量部に対して２５重量部以上６０重量部以下であり、
　上記透光性微粒子の屈折率が上記透光性樹脂の屈折率よりも大きく、
　上記透光性微粒子の屈折率と上記透光性樹脂の屈折率との差が０．０４以上０．２以下であり、
　上記光拡散層の厚さは上記透光性微粒子の平均粒径の１倍以上３倍以下である光拡散フィルム。 The present invention includes the following.
[1] A light diffusing film comprising a base film, a translucent resin and a translucent fine particle dispersed in the translucent resin, and a light diffusing layer having a flat surface,
The translucent fine particles have an average particle size of 0.5 μm or more and less than 20 μm,
The content of the translucent fine particles is 25 parts by weight or more and 60 parts by weight or less with respect to 100 parts by weight of the translucent resin,
The refractive index of the translucent fine particles is larger than the refractive index of the translucent resin,
The difference between the refractive index of the translucent fine particles and the refractive index of the translucent resin is 0.04 or more and 0.2 or less,
The light diffusion layer has a thickness of 1 to 3 times the average particle diameter of the light-transmitting fine particles.
［２］　全ヘイズが４０％以上７０％以下であり、内部ヘイズが４０％以上７０％以下であり、外部ヘイズが１％未満である［１］に記載の光拡散フィルム。 [2] The light diffusion film according to [1], wherein the total haze is 40% to 70%, the internal haze is 40% to 70%, and the external haze is less than 1%.
［３］　前記光拡散層の基材フィルムとは反対側に、さらに反射防止層を有する［１］または［２］に記載の光拡散フィルム。 [3] The light diffusion film according to [1] or [2], further including an antireflection layer on the side opposite to the base film of the light diffusion layer.
［４］　バックライト装置と、光偏向手段と、第１偏光板と、一対の基板の間に液晶層が設けられてなる液晶セルと、第２偏光板と、光拡散フィルムとがこの順で配置され、第１偏光板と第２偏光板とは、それらの透過軸が直交ニコルの関係となるように配置された液晶表示装置であって、前記光拡散フィルムが、［１］~［３］のいずれかに記載の光拡散フィルムである液晶表示装置。 [4] A backlight device, light deflecting means, a first polarizing plate, a liquid crystal cell in which a liquid crystal layer is provided between a pair of substrates, a second polarizing plate, and a light diffusion film in this order. The first polarizing plate and the second polarizing plate are liquid crystal display devices arranged such that their transmission axes have a crossed Nicols relationship, wherein the light diffusion film is [1] to [3 ] The liquid crystal display device which is a light-diffusion film in any one of.
［５］　前記光拡散フィルムにおける光拡散層が、基材フィルムよりも光出射側となるように配置されている［４］に記載の液晶表示装置。 [5] The liquid crystal display device according to [4], wherein the light diffusing layer in the light diffusing film is disposed so as to be closer to the light emitting side than the base film.
［６］　前記光偏向手段は、光出射側に稜線を有する線状プリズム部を光出射面側に所定間隔で複数備えたプリズムフィルムを２枚有し、一方のプリズムフィルムは、その線状プリズム部の稜線の方向が第１偏光板の透過軸に対して実質的に平行となるように配置され、他方のプリズムフィルムは、その線状プリズムの稜線の方向が第２偏光板の透過軸に対して実質的に平行となるように配置されている［４］または［５］に記載の液晶表示装置。 [6] The light deflecting means includes two prism films each having a plurality of linear prism portions having ridge lines on the light emitting side at a predetermined interval on the light emitting surface side, and one prism film is the linear prism. The other prism film is arranged such that the direction of the ridgeline of the linear prism is substantially parallel to the transmission axis of the first polarizing plate, and the direction of the ridgeline of the linear prism is the transmission axis of the second polarizing plate. The liquid crystal display device according to [4] or [5], which is disposed so as to be substantially parallel to the surface.
［７］　前記線状プリズム部の稜線に直交する垂直断面において、稜線に相当する頂点の頂角が９０~１１０°である［４］~［６］のいずれかに記載の液晶表示装置。 [7] The liquid crystal display device according to any one of [4] to [6], wherein an apex angle corresponding to the ridge line is 90 to 110 ° in a vertical cross section orthogonal to the ridge line of the linear prism portion.
［８］　前記バックライト装置と前記光偏向手段との間に、さらに光拡散手段を有する［４］~［７］のいずれかに記載の液晶表示装置。 [8] The liquid crystal display device according to any one of [4] to [7], further including light diffusing means between the backlight device and the light deflecting means.
　なお、本発明において、透光性微粒子の平均粒径は、コールター原理（細孔電気抵抗法）に基づき、コールターマルチサイザー（ベックマンコールター社製）でもとめることができる重量平均粒径である。また、「光出射側」とは、光拡散フィルム等が液晶表示装置に設置された際に、バックライト等の光源から入射した光が出射される側（光源の反対側）であり、視認者に近い側である。反対に、バックライト等の光源から光が入射する側を「光入射側」ということがある。 In the present invention, the average particle diameter of the light-transmitting fine particles is a weight average particle diameter that can be stopped by Coulter Multisizer (manufactured by Beckman Coulter, Inc.) based on the Coulter principle (pore electrical resistance method). In addition, the “light emitting side” is a side from which light incident from a light source such as a backlight is emitted when a light diffusion film or the like is installed in a liquid crystal display device (opposite side of the light source). It is the side close to. Conversely, the side on which light is incident from a light source such as a backlight may be referred to as the “light incident side”.
　また、「第１偏光板の透過軸に対して実質的に平行」とは、第１偏光板の透過軸に平行である場合および本発明の効果を損なわない範囲で該透過軸に対して角度（例えば、１５°以下）を有している場合を包含する意味であり、平行である場合が最も好ましい。同様に、「第２偏光板の透過軸に対して実質的に平行」とは、第２偏光板の透過軸に平行である場合および本発明の効果を損なわない範囲で該透過軸に対して角度（例えば、１５°以下）を有している場合を包含する意味であり、平行である場合が最も好ましい。 In addition, “substantially parallel to the transmission axis of the first polarizing plate” means an angle with respect to the transmission axis when parallel to the transmission axis of the first polarizing plate and within a range not impairing the effects of the present invention. (For example, 15 degrees or less) is included, and the case where it is parallel is the most preferable. Similarly, “substantially parallel to the transmission axis of the second polarizing plate” means that the transmission axis is parallel to the transmission axis of the second polarizing plate and within a range not impairing the effects of the present invention. The meaning includes the case of having an angle (for example, 15 ° or less), and the case of being parallel is the most preferable.
本発明に係る光拡散フィルムの一例を示す概略図である。It is the schematic which shows an example of the light-diffusion film which concerns on this invention. 本発明に係る光拡散フィルムの他の例を示す概略図である。It is the schematic which shows the other example of the light-diffusion film which concerns on this invention. 本発明の光拡散フィルムを用いた偏光板の一例を示す概略図である。It is the schematic which shows an example of the polarizing plate using the light-diffusion film of this invention. 本発明に係る液晶表示装置の一例を示す概略図である。It is the schematic which shows an example of the liquid crystal display device which concerns on this invention. プリズムフィルムと偏光板との配置例を示す概略図である。It is the schematic which shows the example of arrangement | positioning of a prism film and a polarizing plate. 本発明に係る液晶表示装置の他の例を示す概略図である。It is the schematic which shows the other example of the liquid crystal display device which concerns on this invention.
　以下、本発明に係る光拡散フィルムおよび液晶表示装置について図に基づいて説明するが、本発明はこれらの実施形態に何ら限定されるものではない。 Hereinafter, although the light diffusion film and the liquid crystal display device according to the present invention will be described with reference to the drawings, the present invention is not limited to these embodiments.
　本発明に係る光拡散フィルムの一実施形態を、図１を用いて説明する。図１の光拡散フィルム７は、基材フィルム７１の一方面側に、透光性樹脂７２１及び透光性樹脂中に分散された透光性微粒子７２２からなり、表面が平坦な光拡散層７２が積層されてなる。 An embodiment of a light diffusion film according to the present invention will be described with reference to FIG. The light diffusing film 7 in FIG. 1 includes a light transmissive resin 721 and light transmissive fine particles 722 dispersed in the light transmissive resin on one surface side of a base film 71, and a light diffusing layer 72 having a flat surface. Are laminated.
　ここで使用する透光性微粒子７２２は、平均粒径が０．５μｍ以上２０μｍ未満であり、透光性樹脂７２１への配合量が透光性樹脂１００重量部に対して２５重量部以上６０重量部以下である。透光性樹脂７２１の平均粒径および配合量を上記範囲とすることによって、正面コントラストの低下を招くことなく、優れた光拡散性が得られる。また高い透過画像鮮明度も得られる。透光性微粒子７２２の好ましい平均粒径は４~８μｍであり、好ましい配合量は３０~４０重量部である。 The translucent fine particles 722 used here have an average particle size of 0.5 μm or more and less than 20 μm, and the blending amount in the translucent resin 721 is 25 parts by weight or more and 60 parts by weight with respect to 100 parts by weight of the translucent resin. Or less. By setting the average particle size and blending amount of the translucent resin 721 within the above ranges, excellent light diffusibility can be obtained without causing a decrease in front contrast. In addition, high transparency of the transmitted image can be obtained. The preferable average particle diameter of the light-transmitting fine particles 722 is 4 to 8 μm, and the preferable blending amount is 30 to 40 parts by weight.
　本発明で使用する透光性微粒子７２２としては、上記の平均粒径と透光性を有するものであれば特に限定はなく従来公知のものが使用できる。その例は、アクリル樹脂、メラミン樹脂、ポリエチレン、ポリスチレン、有機シリコーン樹脂、アクリル−スチレン共重合体等の有機微粒子、および、炭酸カルシウム、シリカ、酸化アルミニウム、炭酸バリウム、硫酸バリウム、酸化チタン、ガラス等の無機微粒子等を含む。これらの１種それぞれを単独で使用してもよく、他の１種類以上と混合して使用してもよい。また、有機重合体のバルーンやガラス中空ビーズも使用できる。透光性微粒子の形状は、球状、偏平状、板状、針状等いずれであってもよいが、特に球状が望ましい。 The translucent fine particles 722 used in the present invention are not particularly limited as long as they have the above average particle diameter and translucency, and conventionally known ones can be used. Examples thereof are organic fine particles such as acrylic resin, melamine resin, polyethylene, polystyrene, organic silicone resin, acrylic-styrene copolymer, and calcium carbonate, silica, aluminum oxide, barium carbonate, barium sulfate, titanium oxide, glass, etc. Inorganic fine particles and the like. Each of these may be used alone or in combination with one or more other. Organic polymer balloons and glass hollow beads can also be used. The shape of the translucent fine particles may be any of a spherical shape, a flat shape, a plate shape, a needle shape, etc., but a spherical shape is particularly desirable.
　また、透光性微粒子７２２の屈折率は、透光性樹脂７２１の屈折率よりも大きく設定され、その差は０．０４以上０．２以下であり、０．０４~０．１５の範囲が好ましい。透光性微粒子７２２と透光性樹脂７２１との屈折率の差を上記範囲とすることによって、光拡散層７２に入射した光に対して、透光性微粒子７２２と透光性樹脂７２１との屈折率差による内部散乱を発現させることができ、シンチレーションの発生を抑制できる。 Further, the refractive index of the translucent fine particles 722 is set larger than the refractive index of the translucent resin 721, and the difference is 0.04 or more and 0.2 or less, and the range of 0.04 to 0.15 is set. preferable. By setting the difference in refractive index between the translucent fine particles 722 and the translucent resin 721 within the above range, the translucent fine particles 722 and the translucent resin 721 are made of light incident on the light diffusion layer 72. Internal scattering due to the difference in refractive index can be expressed, and the occurrence of scintillation can be suppressed.
　本発明で使用する透光性樹脂７２１としては、透光性を有するものであれば特に限定はなく、例えば、紫外線硬化型樹脂、電子線硬化型樹脂などの電離放射線硬化型樹脂や熱硬化型樹脂、熱可塑性樹脂、金属アルコキシドなどが使用できる。このうち、可塑性樹脂についてはそのまま使用され、紫外線硬化型樹脂、電子線硬化型樹脂などの電離放射線硬化型樹脂や熱硬化型樹脂等の硬化型樹脂については、硬化型樹脂を電離放射線、熱等により、金属アルコキシドについては、金属アルコキシドを加水分解、脱水縮合等により、それぞれ硬化物に変換後使用される。この中でも、高い硬度を有し、ディスプレイ表面に設ける光拡散フィルムに十分な耐傷性を付与する観点からは、電離放射線硬化型樹脂が好適に使用される。 The translucent resin 721 used in the present invention is not particularly limited as long as it has translucency. For example, ionizing radiation curable resins such as ultraviolet curable resins and electron beam curable resins, and thermosetting types. Resins, thermoplastic resins, metal alkoxides, and the like can be used. Of these, plastic resins are used as they are. For curable resins such as ionizing radiation curable resins and thermosetting resins such as ultraviolet curable resins and electron beam curable resins, curable resins are ionized radiation, heat, etc. Thus, the metal alkoxide is used after being converted into a cured product by hydrolysis, dehydration condensation or the like. Among these, ionizing radiation curable resins are preferably used from the viewpoint of high hardness and imparting sufficient scratch resistance to the light diffusion film provided on the display surface.
　電離放射線硬化性樹脂の例は、多価アルコールのアクリル酸エステルまたはメタクリル酸エステル等の多官能性のアクリレート、及びジイソシアネートと多価アルコールおよびアクリル酸またはメタクリル酸のヒドロキシエステル等から合成される多官能のウレタンアクリレートを含む。またこれらの他にも、アクリレート系の官能基を有するポリエーテル樹脂、ポリエステル樹脂、エポキシ樹脂、アルキッド樹脂、スピロアセタール樹脂、ポリブタジエン樹脂、ポリチオールポリエン樹脂等も使用することができる。 Examples of ionizing radiation curable resins are polyfunctional acrylates such as polyhydric alcohol acrylic esters or methacrylic esters, and polyfunctional compounds synthesized from diisocyanates and polyhydric alcohols and hydroxy esters of acrylic acid or methacrylic acid. Of urethane acrylate. Besides these, polyether resins having an acrylate functional group, polyester resins, epoxy resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol polyene resins, and the like can also be used.
　電離放射線硬化型樹脂のうち、紫外線硬化型樹脂を用いる場合、光重合開始剤を加える。光重合開始剤は、用いる樹脂にあったものを用いることが好ましい。光重合開始剤（ラジカル重合開始剤）としては、ベンゾイン、ベンゾインメチルエーテル、ベンゾインエチルエーテル、ベンゾインイソプロピルエーテル、ベンジルメチルケタールなどのベンゾインとそのアルキルエーテル類等が用いられる。光重合開始剤の使用量は、樹脂１００質量部に対して、通常０．５~２０質量部である。好ましくは１~５質量部である。 Among the ionizing radiation curable resins, when an ultraviolet curable resin is used, a photopolymerization initiator is added. It is preferable to use a photopolymerization initiator suitable for the resin used. As the photopolymerization initiator (radical polymerization initiator), benzoin such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzyl methyl ketal, and alkyl ethers thereof are used. The amount of the photopolymerization initiator used is usually 0.5 to 20 parts by mass with respect to 100 parts by mass of the resin. The amount is preferably 1 to 5 parts by mass.
　また、熱硬化型樹脂の例は、アクリルポリオールとイソシアネートプレポリマーとからなる熱硬化型ウレタン樹脂、フェノール樹脂、尿素メラミン樹脂、エポキシ樹脂、不飽和ポリエステル樹脂及びシリコーン樹脂を含む。 Also, examples of the thermosetting resin include thermosetting urethane resin composed of acrylic polyol and isocyanate prepolymer, phenol resin, urea melamine resin, epoxy resin, unsaturated polyester resin, and silicone resin.
　熱可塑性樹脂としては、アセチルセルロース、ニトロセルロース、アセチルブチルセルロース、エチルセルロース、メチルセルロース等のセルロース誘導体、酢酸ビニルおよびその共重合体、塩化ビニルおよびその共重合体、塩化ビニリデンおよびその共重合体等のビニル系樹脂、ポリビニルホルマール、ポリビニルブチラール等のアセタール樹脂、アクリル樹脂およびその共重合体、メタクリル樹脂およびその共重合体等のアクリル系樹脂、ポリスチレン樹脂、ポリアミド樹脂、線状ポリエステル樹脂、ポリカーボネート樹脂等が使用できる。 Examples of the thermoplastic resin include cellulose derivatives such as acetylcellulose, nitrocellulose, acetylbutylcellulose, ethylcellulose and methylcellulose, vinyl acetate and copolymers thereof, vinyl chloride and copolymers thereof, vinylidene chloride and copolymers thereof and the like. Resin, acetal resin such as polyvinyl formal, polyvinyl butyral, acrylic resin and its copolymer, acrylic resin such as methacrylic resin and its copolymer, polystyrene resin, polyamide resin, linear polyester resin, polycarbonate resin, etc. it can.
　金属アルコキシドとしては、珪素アルコキシド系の材料を原料とする酸化珪素系マトリックス等を使用することができる。具体的には、テトラメトキシシラン、テトラエトキシシランを例示することができ、加水分解、脱水縮合により無機系または有機無機複合系マトリックスが形成された硬化物とすることができる。 As the metal alkoxide, a silicon oxide matrix made of a silicon alkoxide material can be used. Specific examples include tetramethoxysilane and tetraethoxysilane, and a cured product in which an inorganic or organic-inorganic composite matrix is formed by hydrolysis and dehydration condensation can be used.
　透光性樹脂７２１として電離放射線硬化型樹脂を用いる場合は、例えば基材フィルム７１に、塗布、乾燥した後に紫外線や電子線等の電離放射線照射する必要がある。また、透光性樹脂７２１として熱硬化型樹脂、金属アルコキシド等を用いる場合は、例えば基材フィルム７１に、塗布、乾燥した後に加熱を要することがある。 When an ionizing radiation curable resin is used as the translucent resin 721, it is necessary to irradiate the base film 71 with ionizing radiation such as ultraviolet rays and electron beams after being applied and dried. When a thermosetting resin, a metal alkoxide, or the like is used as the translucent resin 721, for example, the substrate film 71 may be heated after being applied and dried.
　また、光拡散層７２の層厚は、透光性微粒子７２２の平均粒径に対して１倍以上３倍以下である。光拡散層７２の層厚が、透光性微粒子７２２の平均粒径の１倍より薄い場合、得られる光拡散フィルム７の質感が粗くなると共に、シンチレーションが生じやすくなり表示面の視認性が低下する。また、光拡散層７２の層厚が、透光性微粒子７２２の平均粒径の３倍より厚い場合、光拡散が強くなりすぎ、コントラストが低下するため、表示品位が低下する。 Further, the layer thickness of the light diffusion layer 72 is 1 to 3 times the average particle diameter of the translucent fine particles 722. When the layer thickness of the light diffusion layer 72 is thinner than 1 times the average particle diameter of the light-transmitting fine particles 722, the texture of the light diffusion film 7 to be obtained becomes rough and scintillation easily occurs and the visibility of the display surface decreases. To do. Further, when the layer thickness of the light diffusion layer 72 is thicker than three times the average particle diameter of the light-transmitting fine particles 722, the light diffusion becomes too strong and the contrast is lowered, so that the display quality is lowered.
　光拡散層７２の層厚としては、通常、５~２５μｍが好ましい。光拡散層７２の層厚が５μｍより薄いと、ディスプレイ表面に設けられるだけの十分な耐擦傷性が得られないことがある一方、光拡散層７２の層厚が２５μｍより厚いと、作製された光拡散フィルム７のカールの度合いが大きくなってしまい、取り扱い性が悪くなることがある。 The layer thickness of the light diffusion layer 72 is usually preferably 5 to 25 μm. When the thickness of the light diffusion layer 72 is less than 5 μm, sufficient scratch resistance sufficient to be provided on the display surface may not be obtained. On the other hand, when the thickness of the light diffusion layer 72 is greater than 25 μm, the light diffusion layer 72 is manufactured. The degree of curling of the light diffusing film 7 is increased, and the handleability may be deteriorated.
　本発明で使用する基材フィルム７１としては透光性のものであればよく、例えばガラスやプラスチックフィルムなどを用いることができる。プラスチックフィルムとしては適度の透明性、機械強度を有していればよい。その例は、ＴＡＣ（トリアセチルセルロース）などのセルロースアセテート系樹脂やアクリル系樹脂、ポリカーボネート樹脂及びポリエチレンテレフタレート等のポリエステル系樹脂を含む。 As the base film 71 used in the present invention, any material may be used as long as it is translucent. For example, glass or plastic film can be used. The plastic film only needs to have appropriate transparency and mechanical strength. Examples include cellulose acetate resins such as TAC (triacetyl cellulose), acrylic resins, polycarbonate resins, and polyester resins such as polyethylene terephthalate.
　本発明の光拡散フィルム７は例えば次のようにして作製できる。
　透光性微粒子７２２を分散させた、電離放射線硬化型樹脂、熱硬化型樹脂、熱可塑性樹脂、金属アルコキシドなどの溶媒液（以下、樹脂液と記す場合がある。）を、基材フィルム７１上に塗布し、塗布膜厚を調整して透光性微粒子７２２が塗布膜表面に現れないようにして、平坦な表面を有する光拡散層７２を基材フィルム７１の表面に形成する。この場合、樹脂液中の透光性微粒子７２２の分散は等方分散であることが好ましい。尚、電離放射線硬化型樹脂や熱硬化型樹脂が流動性を有する液状で、透光性微粒子７２２を等方分散可能である場合には、溶媒を添加することなく、樹脂をそのまま使用することもできる。また、平坦な表面を有する光拡散層７２を形成するためには、光拡散層７２の作製工程において、鏡面金型面を有するロールを用いて光拡散層７２に表面処理行う方法等を用いることができる。光拡散層７２の平坦の程度は外部ヘイズで表すことができ、好ましくは１％以下、より好ましくは０．５％以下である。
　前記樹脂液に用いられる溶媒の例は、エタノールなどのアルコール類、プロピレングリコールモノメチルエーテルなどのグリコールエーテル類、酢酸エチル、プロピレングリコールモノメチルエーテルアセテートなどのエステル類、メチルエチルケトンなどのケトン類、トルエンなどの炭化水素類及び塩化メチレンなどのアルキルハライド類を含む。 The light diffusion film 7 of the present invention can be produced, for example, as follows.
A solvent liquid (hereinafter also referred to as a resin liquid in some cases) such as an ionizing radiation curable resin, a thermosetting resin, a thermoplastic resin, or a metal alkoxide, in which the light transmitting fine particles 722 are dispersed, is formed on the base film 71. The light diffusion layer 72 having a flat surface is formed on the surface of the base film 71 so that the light-transmitting fine particles 722 do not appear on the surface of the coating film by adjusting the coating thickness. In this case, the dispersion of the translucent fine particles 722 in the resin liquid is preferably isotropic dispersion. In the case where the ionizing radiation curable resin or the thermosetting resin is a liquid having fluidity and the translucent fine particles 722 can be isotropically dispersed, the resin may be used as it is without adding a solvent. it can. Further, in order to form the light diffusion layer 72 having a flat surface, a method of performing a surface treatment on the light diffusion layer 72 using a roll having a mirror mold surface is used in the manufacturing process of the light diffusion layer 72. Can do. The degree of flatness of the light diffusion layer 72 can be represented by external haze, and is preferably 1% or less, more preferably 0.5% or less.
Examples of the solvent used for the resin liquid include alcohols such as ethanol, glycol ethers such as propylene glycol monomethyl ether, esters such as ethyl acetate and propylene glycol monomethyl ether acetate, ketones such as methyl ethyl ketone, and carbonization such as toluene. Including hydrogen and alkyl halides such as methylene chloride.
　基材フィルム７１については、塗工性の改良や光拡散層との接着性の改良などのために、樹脂液の塗布前に表面処理を施してもよい。表面処理の具体的方法としては、コロナ放電処理やグロー放電処理、酸処理、アルカリ処理、紫外線照射処理などが挙げられる。 The base film 71 may be subjected to a surface treatment before application of the resin liquid in order to improve coatability and adhesiveness with the light diffusion layer. Specific examples of the surface treatment include corona discharge treatment, glow discharge treatment, acid treatment, alkali treatment, and ultraviolet irradiation treatment.
　また、本発明の光拡散フィルム７を、後述する偏光板の支持フィルムとして使用する場合には（図３に図示）、基材フィルム７１と偏光子６１（図３に図示）とを効果的に接着させる観点から、基材フィルム７１を酸処理またはアルカリ処理によって親水化処理しておくのが好ましい。 Moreover, when using the light-diffusion film 7 of this invention as a support film of the polarizing plate mentioned later (illustrated in FIG. 3), the base film 71 and the polarizer 61 (illustrated in FIG. 3) are effectively used. From the viewpoint of bonding, it is preferable that the base film 71 is hydrophilized by acid treatment or alkali treatment.
　基材フィルム７１上に樹脂液を塗布する方法に限定はなく、例えば、グラビアコート法、マイクログラビアコート法、ロールコート法、ロッドコート法、ナイフコート法、エアーナイフコート法、キスコート法、ダイコート法などを用いることができる。 There is no limitation on the method of applying the resin liquid on the base film 71. For example, a gravure coating method, a micro gravure coating method, a roll coating method, a rod coating method, a knife coating method, an air knife coating method, a kiss coating method, and a die coating method. Etc. can be used.
　基材フィルム７１上に直接または他の層を介して樹脂液を塗布した後、必要により加熱して溶媒を乾燥する。電離放射線硬化型樹脂や熱硬化型樹脂、金属アルコキシド等を用いる場合には、さらに電離放射線および／または熱により塗膜を硬化させる。
　電離放射線種は、透光性樹脂７２１の種類に応じて、紫外線、電子線、近紫外線、可視光、近赤外線、赤外線、Ｘ線などから適宜選択することができ、紫外線、電子線が好ましく、特に取り扱いが簡便で高エネルギーが容易に得られるという点で紫外線が好ましい。 After applying the resin liquid on the base film 71 directly or through another layer, the solvent is dried by heating if necessary. When ionizing radiation curable resin, thermosetting resin, metal alkoxide, or the like is used, the coating film is further cured by ionizing radiation and / or heat.
The ionizing radiation species can be appropriately selected from ultraviolet rays, electron beams, near ultraviolet rays, visible light, near infrared rays, infrared rays, X-rays, etc., depending on the type of translucent resin 721, preferably ultraviolet rays and electron beams. In particular, ultraviolet rays are preferable because they are easy to handle and high energy can be easily obtained.
　紫外線硬化型樹脂を光重合させる紫外線の光源としては、紫外線を発生する光源であれば何れも使用できる。例えば、低圧水銀灯、中圧水銀灯、高圧水銀灯、超高圧水銀灯、カーボンアーク灯、メタルハライドランプ、キセノンランプ等を用いることができる。また、ＡｒＦエキシマレーザ、ＫｒＦエキシマレーザ、エキシマランプまたはシンクロトロン放射光等も用いることができる。このうち、超高圧水銀灯、高圧水銀灯、低圧水銀灯、カーボンアーク、キセノンアーク、メタルハライドランプを好ましく利用できる。 As the ultraviolet light source for photopolymerizing the ultraviolet curable resin, any light source that generates ultraviolet light can be used. For example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, or the like can be used. An ArF excimer laser, a KrF excimer laser, an excimer lamp, synchrotron radiation, or the like can also be used. Among these, an ultrahigh pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a carbon arc, a xenon arc, and a metal halide lamp can be preferably used.
　また、電子線も同様に使用できる。電子線としては、コックロフトワルトン型、バンデグラフ型、共振変圧型、絶縁コア変圧器型、直線型、ダイナミトロン型、高周波型等の各種電子線加速器から放出される通常５０~１０００ｋｅＶ、好ましくは１００~３００ｋｅＶのエネルギーを有する電子線を挙げることができる。 Also, an electron beam can be used in the same manner. The electron beam is usually 50 to 1000 keV, preferably 100, emitted from various electron beam accelerators such as cockroft walton type, bandegraph type, resonance transformer type, insulated core transformer type, linear type, dynamitron type, and high frequency type. An electron beam having an energy of ~ 300 keV can be mentioned.
　なお、本発明において電離放射線硬化型樹脂や電子線硬化型樹脂などの硬化型樹脂を用いて光拡散フィルム７を連続的に製造するためには、ロール状に巻付けられた基材フィルム７１上を連続的に送り出す工程、透光性微粒子７２２を分散させた樹脂溶液を塗布・乾燥する工程、塗膜を硬化する工程、および、硬化した光拡散層７２が形成された光拡散フィルム７を巻き取る工程を有する製造方法を用いることが好ましい。 In the present invention, in order to continuously manufacture the light diffusion film 7 using a curable resin such as an ionizing radiation curable resin or an electron beam curable resin, the base film 71 wound in a roll shape is used. Winding the light diffusion film 7 on which the cured light diffusion layer 72 is formed, the step of applying and drying the resin solution in which the translucent fine particles 722 are dispersed, the step of curing the coating film, It is preferable to use a manufacturing method having a step of taking.
　本発明の光拡散フィルムの他の実施形態を図２に示す。図２に示す光拡散フィルム７は、透光性樹脂７２１中に透光性微粒子７２２を分散混合した光拡散層７２に、さらに透光性樹脂層７３を積層したものである。 Another embodiment of the light diffusion film of the present invention is shown in FIG. The light diffusing film 7 shown in FIG. 2 is obtained by further laminating a light transmissive resin layer 73 on a light diffusing layer 72 in which light transmissive fine particles 722 are dispersed and mixed in a light transmissive resin 721.
　本発明の光拡散フィルムは、光拡散層の基材フィルムとは反対側面に、さらに反射防止層を有することが好ましい。反射防止層とは、ハードコート層を高屈折率化し、その上に低屈折率薄膜を設ける等、各層の屈折率や層厚を制御することで機能を付与される層であり、反射率を限りなく低くすることで、表示画面への外部の物の映りこみを防止することができる。 The light diffusion film of the present invention preferably further has an antireflection layer on the side surface opposite to the base film of the light diffusion layer. The antireflection layer is a layer that is given a function by controlling the refractive index and thickness of each layer, such as by increasing the refractive index of the hard coat layer and providing a thin film of low refractive index on the hard coat layer. By making it as low as possible, it is possible to prevent external objects from being reflected on the display screen.
　次に、本発明の光拡散フィルムを用いた偏光板の一例を図３に示す。一般的な偏光板は、偏光子６１の両面に支持フィルム６２が貼り合わされた構造をしているが、図３に示す偏光板は、一方の支持フィルムとして本発明の光拡散フィルム７を用いたものであって、偏光機能と防眩（光拡散）機能とを有する多機能フィルムである。すなわち、偏光子６１の一方の面に支持フィルム６２が貼着され、他方の面に、光拡散層７２を基材フィルム７１上に形成した光拡散フィルム７が貼着されている。このような構成の偏光板を液晶表示装置に取り付ける場合、光拡散フィルム７が光出射側となるように液晶表示パネルのガラス基板等に貼着する。なお、基材フィルム７１と偏光子６１との接合は、接着剤層を介して貼り合わせてもよいが、接着剤層を介さずに直接接合するのが好ましい。 Next, an example of a polarizing plate using the light diffusion film of the present invention is shown in FIG. A general polarizing plate has a structure in which a support film 62 is bonded to both sides of a polarizer 61. The polarizing plate shown in FIG. 3 uses the light diffusion film 7 of the present invention as one support film. It is a multifunctional film having a polarizing function and an antiglare (light diffusion) function. That is, the support film 62 is attached to one surface of the polarizer 61, and the light diffusion film 7 in which the light diffusion layer 72 is formed on the base film 71 is attached to the other surface. When the polarizing plate having such a configuration is attached to the liquid crystal display device, the polarizing plate is attached to a glass substrate of the liquid crystal display panel so that the light diffusion film 7 is on the light emitting side. In addition, although the base film 71 and the polarizer 61 may be bonded together via an adhesive layer, it is preferable to directly bond them without using an adhesive layer.
　次に、本発明に係る液晶表示装置について説明する。図４は、本発明に係る液晶表示装置の一例を示す概略図である。図４の液晶表示装置は、ノーマリホワイトモードのＴＮ方式の液晶表示装置であって、バックライト装置２、光拡散板３、光偏向手段としての２枚のプリズムフィルム４ａ，４ｂ、第１偏光板５、一対の透明基板１１ａ，１１ｂの間に液晶層１２が設けられてなる液晶セル１、第２偏光板６、および、光拡散フィルム７がこの順で配置されてなる。 Next, the liquid crystal display device according to the present invention will be described. FIG. 4 is a schematic view showing an example of a liquid crystal display device according to the present invention. The liquid crystal display device of FIG. 4 is a normally white mode TN liquid crystal display device, which includes a backlight device 2, a light diffusing plate 3, two prism films 4a and 4b as light deflecting means, and a first polarized light. The liquid crystal cell 1 in which the liquid crystal layer 12 is provided between the plate 5 and the pair of transparent substrates 11a and 11b, the second polarizing plate 6, and the light diffusion film 7 are arranged in this order.
　図５に示すように、第１偏光板５と第２偏光板６とは、それらの透過軸が直交ニコルの関係となるように配置されている。また、２枚のプリズムフィルム４ａ，４ｂはそれぞれ、光入射側の面が平坦面であり、光出射側の面に線状プリズム部４１ａ，４１ｂが平行に複数形成されており、線状プリズム部４１ａ，４１ｂは光出射側に稜線４２ａ，４２ｂを有している。そして、プリズムフィルム４ａは、その線状プリズム部４１ａの稜線が第１偏光板５の透過軸方向と実質的に平行となるように配置され、プリズムフィルム４ｂは、その線状プリズム部４１ｂの稜線が第２偏光板６の透過軸方向と実質的に平行となるように配置されている。 As shown in FIG. 5, the 1st polarizing plate 5 and the 2nd polarizing plate 6 are arrange | positioned so that those transmission axes may become a relationship of orthogonal Nicols. Each of the two prism films 4a and 4b has a flat surface on the light incident side, and a plurality of linear prism portions 41a and 41b formed in parallel on the surface on the light emitting side. 41a and 41b have ridge lines 42a and 42b on the light emitting side. The prism film 4a is arranged so that the ridge line of the linear prism part 41a is substantially parallel to the transmission axis direction of the first polarizing plate 5, and the prism film 4b is ridge line of the linear prism part 41b. Are arranged so as to be substantially parallel to the transmission axis direction of the second polarizing plate 6.
　図５において、線状プリズム部４１ａ，４１ｂの稜線に直交する垂直断面での断面形状は三角形であり、その三角形の頂点のうち稜線に相当する頂点の頂角θは、９０°~１１０°の範囲であることが好ましい。また、この三角形は、各辺が等辺、不等辺のいずれのものであってもよく、正面方向（液晶表示装置の表示面の法線方向）に集光しようとする場合は、光出射側の二辺が等しい二等辺三角形であることが好ましい。 In FIG. 5, the cross-sectional shape in the vertical cross section orthogonal to the ridge lines of the linear prism portions 41a and 41b is a triangle, and the apex angle θ of the apex corresponding to the ridge line among the apexes of the triangle is 90 ° to 110 °. A range is preferable. In addition, this triangle may have either an equal side or an unequal side, and when concentrating in the front direction (normal direction of the display surface of the liquid crystal display device), It is preferable that the two sides are equal isosceles triangles.
　上記プリズムフィルム４ａ，４ｂは、かかる二等辺三角形の断面を有する複数の線状プリズム部４１ａ，４２ａが、三角形の頂角θに相対した底辺が互いに隣接するように順次配置され、複数の線状プリズム部４１ａ，４２ａの稜線４２ａ，４２ｂが互いにほぼ平行になるように配列された構造を有することが好ましい。この場合、集光能力が著しく減退しない限り、線状プリズム部４１ａ，４２ａの断面形状の三角形は、その各頂点が曲線形状等となっていてもよい。各頂点間の距離は、通常、１０μｍ~５００μｍの範囲であり、好ましくは、３０μｍ~２００μｍの範囲である。 In the prism films 4a and 4b, a plurality of linear prism portions 41a and 42a having such an isosceles triangular cross section are sequentially arranged such that the bases corresponding to the apex angle θ of the triangle are adjacent to each other, and a plurality of linear prisms are arranged. It is preferable that the ridgelines 42a and 42b of the prism portions 41a and 42a are arranged so as to be substantially parallel to each other. In this case, as long as the light collecting ability is not significantly reduced, the triangles of the cross-sectional shapes of the linear prism portions 41a and 42a may have a curved shape at each vertex. The distance between the vertices is usually in the range of 10 μm to 500 μm, and preferably in the range of 30 μm to 200 μm.
　このような構成の液晶表示装置において、図４に示すように、バックライト装置２から放射された光は、光拡散板３によって拡散された後、プリズムフィルム４ａへ入射する。
第１偏光板５の透過軸方向に直交する垂直断面において、プリズムフィルム４ａの下面に対して斜めに入射した光は、正面方向に進路が変えられて出射する。次に、プリズムフィルム４ｂにおいて、第２偏光板６の透過軸方向に直交する垂直断面において、プリズムフィルム４ｂの下面に対して斜めに入射した光は、上記と同様に、正面方向に進路が変えられて出射する。したがって、２枚のプリズムフィルム４ａ，４ｂを通過した光は、いずれの垂直断面においても正面方向に集光されたものとなり、正面方向の輝度が向上する。 In the liquid crystal display device having such a configuration, as shown in FIG. 4, the light emitted from the backlight device 2 is diffused by the light diffusion plate 3 and then enters the prism film 4a.
In a vertical cross section perpendicular to the transmission axis direction of the first polarizing plate 5, light incident obliquely with respect to the lower surface of the prism film 4a is emitted with its path changed in the front direction. Next, in the prism film 4b, in the vertical cross section perpendicular to the transmission axis direction of the second polarizing plate 6, the light incident obliquely with respect to the lower surface of the prism film 4b changes its course in the front direction as described above. Is emitted. Therefore, the light passing through the two prism films 4a and 4b is condensed in the front direction in any vertical cross section, and the luminance in the front direction is improved.
　そして、正面方向に指向性が付与された光は、第１偏光板５によって円偏光から直線偏光とされて液晶セル１に入射する。液晶セル１に入射した光は、電場によって制御された液晶層１２の配向によって画素ごとに偏光面が制御されて液晶セル１から出射する。そして、液晶セル１から出射した光は第２偏光板６によって画像化され、光拡散フィルム７を通って表示面側に出射する。光拡散フィルムは、光拡散層が基材フィルムよりも光出射側になるように配置されている。 The light having directivity in the front direction is changed from circularly polarized light to linearly polarized light by the first polarizing plate 5 and enters the liquid crystal cell 1. The light incident on the liquid crystal cell 1 is emitted from the liquid crystal cell 1 with its polarization plane controlled for each pixel by the orientation of the liquid crystal layer 12 controlled by the electric field. The light emitted from the liquid crystal cell 1 is imaged by the second polarizing plate 6, passes through the light diffusion film 7, and exits to the display surface side. The light diffusing film is disposed so that the light diffusing layer is closer to the light emitting side than the base film.
　このように、本発明の液晶表示装置では、２枚のプリズムフィルム４ａ，４ｂによって、液晶セル１に入射する光の正面方向への指向性が従来よりも高くなる。これによって、従来の装置に比べて正面方向の輝度が向上するようになる。また、前述の光拡散フィルム７を使用しているので、正面コントラストの低下を招くことなく、優れた光拡散性と高い透過画像鮮明度が得られる。 Thus, in the liquid crystal display device of the present invention, the directivity of the light incident on the liquid crystal cell 1 in the front direction is higher than before by the two prism films 4a and 4b. Thereby, the brightness in the front direction is improved as compared with the conventional apparatus. Moreover, since the above-mentioned light diffusion film 7 is used, excellent light diffusibility and high transmitted image definition can be obtained without causing a decrease in front contrast.
　以下、本発明の液晶表示装置の各部材について説明する。まず、本発明で使用する液晶セル１は、不図示のスペーサにより所定距離を隔てて対向配置された一対の透明基板１１ａ，１１ｂと、この一対の透明基板１１ａ，１１ｂの間に液晶を封入されてなる液晶層１２とを備える。この図では図示していないが、一対の透明基板１１ａ，１１ｂには、それぞれ透明電極や配向膜が積層形成されており、透明電極間に表示データに基づいた電圧が印加されることによって液晶が配向する。液晶セル１の表示方式はここではＴＮ方式であるが、ＩＰＳ方式、ＶＡ方式などの表示方式を採用しても構わない。 Hereinafter, each member of the liquid crystal display device of the present invention will be described. First, in the liquid crystal cell 1 used in the present invention, a liquid crystal is sealed between a pair of transparent substrates 11a and 11b arranged to face each other at a predetermined distance by a spacer (not shown), and the pair of transparent substrates 11a and 11b. The liquid crystal layer 12 is provided. Although not shown in the figure, a transparent electrode and an alignment film are laminated on each of the pair of transparent substrates 11a and 11b, and the liquid crystal is formed by applying a voltage based on display data between the transparent electrodes. Orient. Here, the display method of the liquid crystal cell 1 is the TN method, but a display method such as an IPS method or a VA method may be adopted.
　バックライト装置２は、上面開口の直方体形状のケース２１と、ケース２１内に複数本並列配置された、線状光源としての冷陰極管２２とを備える。ケース２１は、樹脂材料や金属材料から成形されてなり、冷陰極管２２から放射された光をケース内周面で反射させる観点から、少なくともケース内周面は白色または銀色であるのが望ましい。光源としては、冷陰極管の他、熱陰極管、線状に配置されたＬＥＤなども使用できる。線状光源を用いる場合、配置する線状光源の本数に特に限定はないが、発光面の輝度ムラの抑制等の観点から、隣接する線状光源の中心間距離が１５~１５０ｍｍの範囲となるようにするのが好ましい。なお、本発明で使用するバックライト装置２は、図４に示す直下型のものに限定されるものではなく、導光板の側面に線状光源または点状光源を配置したサイドライド型、あるいは光源自体が平面状の平面光源型など従来公知のものを使用できる。 The backlight device 2 includes a rectangular parallelepiped case 21 having an upper surface opening, and a plurality of cold cathode tubes 22 serving as linear light sources arranged in parallel in the case 21. The case 21 is formed from a resin material or a metal material, and at least the case inner peripheral surface is preferably white or silver from the viewpoint of reflecting the light emitted from the cold cathode tube 22 on the case inner peripheral surface. As a light source, in addition to a cold cathode tube, a hot cathode tube, a linearly arranged LED, and the like can be used. When the linear light source is used, the number of the linear light sources to be arranged is not particularly limited, but the distance between the centers of the adjacent linear light sources is in a range of 15 to 150 mm from the viewpoint of suppressing luminance unevenness on the light emitting surface. It is preferable to do so. The backlight device 2 used in the present invention is not limited to the direct type shown in FIG. 4, but is a side-ride type in which a linear light source or a point light source is arranged on the side surface of the light guide plate, or a light source. A conventionally well-known thing, such as a planar light source type itself, can be used.
　光拡散板３は、基材に拡散剤が分散混合されてなり、その基材としては、ポリカーボネート、メタクリル樹脂、メタクリル酸メチル−スチレン共重合体樹脂、アクリロニトリル−スチレン共重合体樹脂、メタクリル酸−スチレン共重合体樹脂、ポリスチレン、ポリ塩化ビニル、ポリプロピレン、ポリメチルペンテン等のポリオレフィン、環状ポリオレフィン、ポリエチレンテレフタレート、ポリブチレンテレフタレート、ポリエチレンナフタレート等のポリエステル系樹脂、ポリアミド系樹脂、ポリアリレート、ポリイミド等が使用できる。また、基材に混合分散させる拡散剤としては、基材となる材料と屈折率が異なる物質からなる微粒子であって、具体例には、基材の材料とは異なる種類のアクリル樹脂、メラミン樹脂、ポリエチレン、ポリスチレン、有機シリコーン樹脂、アクリル−スチレン共重合体等の有機微粒子、および炭酸カルシウム、シリカ、酸化アルミニウム、炭酸バリウム、硫酸バリウム、酸化チタン、ガラス等の無機微粒子等が挙げられ、これらの中の１種をそれぞれ単独で、または他の１種類以上と混合して使用する。また、有機重合体のバルーンやガラス中空ビーズも拡散剤として使用できる。拡散剤の平均粒径は０．５~３０μｍの範囲が好適である。また、拡散剤の形状としては、球状のみならず偏平状、板状、針状等であってもよい。 The light diffusing plate 3 includes a base material in which a diffusing agent is dispersed and mixed. As the base material, polycarbonate, methacrylic resin, methyl methacrylate-styrene copolymer resin, acrylonitrile-styrene copolymer resin, methacrylic acid- Styrene copolymer resins, polyolefins such as polystyrene, polyvinyl chloride, polypropylene, polymethylpentene, cyclic polyolefins, polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyamide resins, polyarylate, polyimide, etc. Can be used. The diffusing agent mixed and dispersed in the base material is fine particles made of a material having a refractive index different from that of the base material, and specific examples include acrylic resins and melamine resins of a different type from the base material. Organic fine particles such as polyethylene, polystyrene, organic silicone resin, acrylic-styrene copolymer, and inorganic fine particles such as calcium carbonate, silica, aluminum oxide, barium carbonate, barium sulfate, titanium oxide, and glass. One of them is used alone or in combination with one or more other. Organic polymer balloons and glass hollow beads can also be used as the diffusing agent. The average particle diameter of the diffusing agent is preferably in the range of 0.5 to 30 μm. Further, the shape of the diffusing agent may be not only spherical but also flat, plate-like, and needle-like.
　プリズムフィルム４ａ，４ｂは、光入射面側が平坦面で、光出射面側に、断面三角形状の線状プリズムが平行に複数形成されている。プリズムフィルム４ａ，４ｂの材料としては、例えば、ポリカーボネート樹脂やＡＢＳ樹脂、メタクリル樹脂、メタクリル酸メチル−スチレン共重合体樹脂、ポリスチレン樹脂、アクリロニトリル−スチレン共重合体樹脂、ポリエチレン・ポリプロピレン等のポリオレフィン樹脂、あるいは、紫外線硬化型樹脂、電子線硬化型樹脂などの電離放射線硬化型樹脂などが挙げられる。プリズムフィルムの作製方法としては、異形押出法、プレス成形法、射出成形法、ロール転写法、レーザーアブレーション法、機械切削法、機械研削法、フォトポリマープロセス法などの公知の方法で製造することができる。これらの方法は、それぞれ単独で使用されてもよいし、あるいは２種以上の方法を組み合わせてもよい。また、これらプリズムシートに光拡散剤を分散してもよい。プリズムフィルム４ａ，４ｂの厚みとしては、通常は０．１~１５ｍｍであり、好ましくは０．５~１０ｍｍである。 In the prism films 4a and 4b, the light incident surface side is a flat surface, and a plurality of linear prisms having a triangular cross section are formed in parallel on the light output surface side. Examples of the material of the prism films 4a and 4b include polycarbonate resin, ABS resin, methacrylic resin, methyl methacrylate-styrene copolymer resin, polystyrene resin, acrylonitrile-styrene copolymer resin, polyolefin resin such as polyethylene / polypropylene, Alternatively, ionizing radiation curable resins such as ultraviolet curable resins and electron beam curable resins can be used. The prism film can be produced by a known method such as a profile extrusion method, a press molding method, an injection molding method, a roll transfer method, a laser ablation method, a mechanical cutting method, a mechanical grinding method, or a photopolymer process method. it can. Each of these methods may be used alone, or two or more methods may be combined. Further, a light diffusing agent may be dispersed in these prism sheets. The thickness of the prism films 4a and 4b is usually 0.1 to 15 mm, preferably 0.5 to 10 mm.
　本発明で使用する第１偏光板５および第２偏光板６としては、通常は、偏光子の両面に支持フィルムを貼り合わせたものが使用される。偏光子の例は、ポリビニルアルコール系の樹脂、ポリ酢酸ビニル樹脂、エチレン／酢酸ビニル（ＥＶＡ）樹脂、ポリアミド樹脂、ポリエステル樹脂等の偏光子基板に、二色性染料またはヨウ素を吸着配向させたもの及び分子的に配向したポリビニルアルコールフィルム中に、ポリビニルアルコールの二色性脱水生成物（ポリビニレン）の配向した分子鎖を含有するポリビニルアルコール／ポリビニレンコポリマーを含む。特に、ポリビニルアルコール系樹脂の偏光子基板に二色性染料またはヨウ素を吸着配向させたものが偏光子として好適に使用される。
　偏光子の厚さに特に限定はないが、一般には偏光板の薄型化等を目的に、１００μｍ以下が好ましく、より好ましくは１０~５０μｍ、さらに好ましくは２５~３５μｍである。 As the 1st polarizing plate 5 and the 2nd polarizing plate 6 which are used by this invention, what bonded the support film to the both surfaces of a polarizer normally is used. Examples of polarizers are those obtained by adsorbing and orienting dichroic dyes or iodine on polarizer substrates such as polyvinyl alcohol resins, polyvinyl acetate resins, ethylene / vinyl acetate (EVA) resins, polyamide resins, and polyester resins. And a polyvinyl alcohol / polyvinylene copolymer containing an oriented molecular chain of a dichroic dehydrated product of polyvinyl alcohol (polyvinylene) in a molecularly oriented polyvinyl alcohol film. In particular, a polarizer substrate made of polyvinyl alcohol resin obtained by adsorbing and orienting a dichroic dye or iodine is preferably used as the polarizer.
The thickness of the polarizer is not particularly limited, but is generally preferably 100 μm or less, more preferably 10 to 50 μm, still more preferably 25 to 35 μm for the purpose of reducing the thickness of the polarizing plate.
　偏光子を支持・保護する支持フィルムとしては、低複屈折性で、透明性や機械的強度、熱安定性や水分遮蔽性などに優れるポリマーからなるフィルムが好ましい。このようなフィルムの例は、ＴＡＣ（トリアセチルセルロース）などのセルロースアセテート系樹脂やアクリル系樹脂、四フッ化エチレン／六フッ化プロピレン系共重合体等のフッ素系樹脂、ポリカーボネート樹脂、ポリエチレンテレフタレート等のポリエステル系樹脂、ポリイミド系樹脂、ポリスルホン系樹脂、ポリエーテルスルホン系樹脂、ポリスチレン系樹脂、ポリビニルアルコール系樹脂、ポリ塩化ビニル系樹脂、ポリオレフィン樹脂、ポリアミド系樹脂等の樹脂をフィルム状に成形加工したものを含む。これらの中でも、偏光特性や耐久性などの点から、表面をアルカリなどでケン化処理したトリアセチルセルロースフィルムやノルボルネン系熱可塑性樹脂フィルムが好ましく使用できる。ノルボルネン系熱可塑性樹脂フィルムは、フィルムが熱や湿熱からの良好なバリアーとなるので偏光板の耐久性が大幅に向上するとともに、吸湿率が少ないため寸法安定性が大幅に向上し、特に好適に使用できる。フィルム状への成形加工は、キャスティング法、カレンダー法、押出し法の従来公知の方法を用いることができる。支持フィルムの厚さに限定はないが、偏光板の薄型化等の観点から、通常は、５００μｍ以下が好ましく、より好ましくは５~３００μｍ、さらに好ましくは５~１５０μｍである。 As the support film for supporting and protecting the polarizer, a film made of a polymer having low birefringence, excellent transparency, mechanical strength, thermal stability, moisture shielding property and the like is preferable. Examples of such films include cellulose acetate resins such as TAC (triacetyl cellulose), acrylic resins, fluorine resins such as tetrafluoroethylene / hexafluoropropylene copolymers, polycarbonate resins, polyethylene terephthalate, etc. Polyester resin, polyimide resin, polysulfone resin, polyethersulfone resin, polystyrene resin, polyvinyl alcohol resin, polyvinyl chloride resin, polyolefin resin, polyamide resin, etc. were molded into a film. Including things. Among these, a triacetyl cellulose film or a norbornene-based thermoplastic resin film whose surface is saponified with an alkali or the like can be preferably used from the viewpoints of polarization characteristics and durability. The norbornene-based thermoplastic resin film is particularly suitable because the film is a good barrier from heat and wet heat, so the durability of the polarizing plate is greatly improved and the dimensional stability is greatly improved due to its low moisture absorption rate. Can be used. For forming into a film, a conventionally known method such as a casting method, a calendar method, or an extrusion method can be used. The thickness of the support film is not limited, but is usually preferably 500 μm or less, more preferably 5 to 300 μm, still more preferably 5 to 150 μm from the viewpoint of thinning the polarizing plate.
　図６に、本発明の液晶表示装置の他の実施形態を示す。図６の液晶表示装置が、図４の液晶表示装置と異なる点は、第１偏光板５と液晶セル１との間に位相差板８を配置した点である。この位相差板８は、液晶セル１の表面に対して垂直な方向に位相差がほぼゼロのものであり、真正面からは何ら光学的な作用を及ぼさず、斜めから見たときに位相差が発現し、液晶セル１で生じる位相差を補償しようというものである。これによって、より広い視野角が得られ、より優れた表示品位および色再現性が得られるようになる。位相差板８は、第１偏光板５と液晶セル１との間および第２偏光板６と液晶セル１との間の一方または両方に配置することができる。 FIG. 6 shows another embodiment of the liquid crystal display device of the present invention. The liquid crystal display device of FIG. 6 is different from the liquid crystal display device of FIG. 4 in that a phase difference plate 8 is disposed between the first polarizing plate 5 and the liquid crystal cell 1. This phase difference plate 8 has a substantially zero phase difference in a direction perpendicular to the surface of the liquid crystal cell 1, has no optical effect from the front, and has a phase difference when viewed from an oblique direction. It is intended to compensate for the phase difference that occurs and occurs in the liquid crystal cell 1. As a result, a wider viewing angle can be obtained, and better display quality and color reproducibility can be obtained. The phase difference plate 8 can be disposed between the first polarizing plate 5 and the liquid crystal cell 1 and at one or both between the second polarizing plate 6 and the liquid crystal cell 1.
　位相差板８の例は、ポリカーボネート樹脂や環状オレフィン系重合体樹脂をフィルムにし、このフィルムを更に二軸延伸したものや、液晶性モノマーを光重合反応で分子配列を固定化したものを含む。位相差板８は、液晶の配列を光学的に補償するものであるから、液晶配列と逆の屈折率特性のものを用いる。具体的にはＴＮモードの液晶表示セルには、例えば「ＷＶフィルム」（富士フィルム株式会社製）、ＳＴＮモードの液晶表示セルには、例えば「ＬＣフィルム」（新日本石油株式会社製）、ＩＰＳモードの液晶セルには、例えば二軸性位相差フィルム、ＶＡモードの液晶セルには、例えばＡプレートおよびＣ−プレートを組み合わせた位相差板、二軸性位相差フィルム、πセルモードの液晶セルには例えば「ＯＣＢ用ＷＶフィルム」（富士フィルム株式会社製）などが好適に使用できる。 Examples of the phase difference plate 8 include those obtained by using a polycarbonate resin or a cyclic olefin polymer resin as a film and further biaxially stretching the film, or a liquid crystal monomer having a molecular arrangement fixed by a photopolymerization reaction. Since the phase difference plate 8 optically compensates the alignment of the liquid crystal, the retardation plate 8 having a refractive index characteristic opposite to that of the liquid crystal alignment is used. Specifically, for a TN mode liquid crystal display cell, for example, “WV film” (manufactured by Fuji Film Co., Ltd.), and for an STN mode liquid crystal display cell, for example, “LC film” (manufactured by Nippon Oil Corporation), IPS For example, a biaxial retardation film for a mode liquid crystal cell, and for a VA mode liquid crystal cell, for example, a retardation plate combining an A plate and a C-plate, a biaxial retardation film, a π cell mode liquid crystal cell For example, “OCV WV film” (manufactured by Fuji Film Co., Ltd.) can be preferably used.
　以下、実施例を挙げて本発明をより詳細に説明するが、本発明はこれらに限定されるものではない。 Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.
　実施例１
　（１）鏡面金型の作製
　直径２００ｍｍの鉄ロール（ＪＩＳによるＳＴＫＭ１３Ａ）の表面に工業用クロムめっき加工を行い、次いで金型の表面をこの鉄ロールを用いて鏡面研磨して鏡面金型を作製した。得られた金型のクロムめっき面のビッカース硬度は１０００であった。なお、ビッカース硬度は、超音波硬度計ＭＩＣ１０（Ｋｒａｕｔｋｒａｍｅｒ社製）を用い、ＪＩＳ　Ｚ　２２４４に準拠して測定した（以下の例においてもビッカース硬度の測定法は同じ）。 Example 1
(1) Production of mirror surface mold Industrial chrome plating is performed on the surface of a 200 mm diameter iron roll (STKM13A by JIS), and then the surface of the mold is mirror polished using this iron roll to produce a mirror mold. did. The Vickers hardness of the chromium plating surface of the obtained mold was 1000. The Vickers hardness was measured according to JIS Z 2244 using an ultrasonic hardness tester MIC10 (manufactured by Krautkramer) (the measurement method of Vickers hardness is the same in the following examples).
　（２）光拡散層と基材フィルムとからなる光拡散フィルムの調製
　ペンタエリスリトールトリアクリレート（６０質量部）および多官能ウレタン化アクリレート（ヘキサメチレンジイソシアネートとペンタエリスリトールトリアクリレートの反応生成物、４０質量部）をプロピレングリコールモノメチルエーテル溶液に混合し、固形分濃度６０質量％となるように調整して紫外線硬化性樹脂組成物を得た。尚、該組成物からプロピレングリコールモノメチルエーテルを除去して紫外線硬化した後の硬化物の屈折率は１．５３であった。 (2) Preparation of light diffusing film comprising light diffusing layer and substrate film Pentaerythritol triacrylate (60 parts by mass) and polyfunctional urethanized acrylate (reaction product of hexamethylene diisocyanate and pentaerythritol triacrylate, 40 parts by mass ) Was mixed with a propylene glycol monomethyl ether solution and adjusted to a solid content concentration of 60% by mass to obtain an ultraviolet curable resin composition. The refractive index of the cured product after removing propylene glycol monomethyl ether from the composition and curing with ultraviolet rays was 1.53.
　次に、上記紫外線硬化性樹脂組成物の固形分１００質量部に対して、透光性微粒子として重量平均粒径が１２．０μｍのポリスチレン系粒子（積水化成品工業株式会社製　ＳＢＸ−１２）を３０質量部、光重合開始剤である「ルシリン　ＴＰＯ」（ＢＡＳＦ社製、化学名：２，４，６−トリメチルベンゾイルジフェニルフォスフィンオキサイド）を５質量部添加し、固形分率が６０質量％になるようにプロピレングリコールモノメチルエーテルで希釈して塗布液を調製した。 Next, with respect to 100 parts by mass of the solid content of the ultraviolet curable resin composition, polystyrene particles having a weight average particle diameter of 12.0 μm (SBX-12 manufactured by Sekisui Plastics Co., Ltd.) are used as translucent fine particles. 30 parts by mass, 5 parts by mass of “Lucirin TPO” (manufactured by BASF Corp., chemical name: 2,4,6-trimethylbenzoyldiphenylphosphine oxide) as a photopolymerization initiator is added, and the solid content is 60% by mass. A coating solution was prepared by diluting with propylene glycol monomethyl ether.
　この塗布液を、厚さ８０μｍのトリアセチルセルロース（ＴＡＣ）フィルム（基材フィルム）上に塗布し、８０℃に設定した乾燥機中で１分間乾燥させた。乾燥後の基材フィルムを、上記（１）で作製した金型の鏡面に、紫外線硬化性樹脂組成物層が金型側となるようにゴムロールで押し付けて密着させた。この状態で基材フィルム側より、強度２０ｍＷ／ｃｍ２の高圧水銀灯からの光をｈ線換算光量で３００ｍＪ／ｃｍ２となるように照射して、紫外線硬化性樹脂組成物層を硬化させ、平坦な表面を有する光拡散層と基材フィルムとからなる、図１に示す構造の光拡散フィルムを作製した。 This coating solution was coated on a 80 μm thick triacetyl cellulose (TAC) film (base film) and dried for 1 minute in a dryer set at 80 ° C. The dried base film was brought into close contact with the mirror surface of the mold produced in (1) above with a rubber roll so that the ultraviolet curable resin composition layer was on the mold side. In this state, light from a high-pressure mercury lamp with an intensity of 20 mW / cm 2 is irradiated from the base film side so as to be 300 mJ / cm 2 in terms of the amount of h-ray to cure the ultraviolet curable resin composition layer, A light diffusing film having a structure shown in FIG. 1, comprising a light diffusing layer having a rough surface and a base film, was prepared.
　実施例２
　透光性微粒子として重量平均粒径が６．０μｍのポリスチレン系粒子（積水化成品工業株式会社製　ＳＢＸ−６）を３５質量部使用した以外は上記実施例１と同様にして光拡散フィルムを作製した。 Example 2
A light diffusing film was produced in the same manner as in Example 1 except that 35 parts by mass of polystyrene-based particles (SBX-6 manufactured by Sekisui Plastics Co., Ltd.) having a weight average particle size of 6.0 μm were used as the translucent fine particles. did.
　比較例１
　透光性微粒子として重量平均粒径が６．０μｍのポリスチレン系粒子（積水化成品工業株式会社製ＳＢＸ−６）を１０質量部使用した以外は上記実施例１と同様にして光拡散フィルムを作製した。 Comparative Example 1
A light diffusion film was produced in the same manner as in Example 1 except that 10 parts by mass of polystyrene-based particles having a weight average particle size of 6.0 μm (SBX-6 manufactured by Sekisui Plastics Co., Ltd.) were used as the light-transmitting fine particles. did.
　比較例２
　透光性微粒子として重量平均粒径が６．０μｍのポリスチレン系粒子（積水化成品工業株式会社製ＳＢＸ−６）を８０質量部使用した以外は上記実施例１と同様にして光拡散フィルムを作製した。 Comparative Example 2
A light diffusion film was prepared in the same manner as in Example 1 except that 80 parts by mass of polystyrene-based particles having a weight average particle size of 6.0 μm (SBX-6 manufactured by Sekisui Plastics Co., Ltd.) were used as the light-transmitting fine particles. did.
　比較例３
　透光性微粒子として重量平均粒径が６．０μｍのスチレン−メタクリル酸メチル共重合系粒子（積水化成品工業株式会社製）を４０質量部使用した以外は上記実施例１と同様にして光拡散フィルムを作製した。 Comparative Example 3
Light diffusion in the same manner as in Example 1 except that 40 parts by mass of styrene-methyl methacrylate copolymer particles (manufactured by Sekisui Plastics Co., Ltd.) having a weight average particle size of 6.0 μm were used as translucent fine particles. A film was prepared.
　［透光性微粒子の重量平均粒径］
　実施例１、２および比較例１~３で使用した透光性微粒子の重量平均粒径は、コールター原理（細孔電気抵抗法）に基づき、コールターマルチサイザー（ベックマンコールター社製）を用いて測定した。 [Weight average particle diameter of translucent fine particles]
The weight average particle diameter of the light-transmitting fine particles used in Examples 1 and 2 and Comparative Examples 1 to 3 was measured using a Coulter Multisizer (manufactured by Beckman Coulter, Inc.) based on the Coulter principle (pore electrical resistance method). did.
　［光拡散層の膜厚］
　実施例１、２および比較例１~３で得られた光拡散フィルムの層厚をＮＩＫＯＮ社製　ＤＩＧＩＭＩＣＲＯ　ＭＨ−１５（本体）およびＺＣ−１０１（カウンター）を用いて測定し、この層厚から基材厚み８０μｍを差し引くことによって光拡散層の膜厚を求めた。 [Thickness of light diffusion layer]
The layer thicknesses of the light diffusion films obtained in Examples 1 and 2 and Comparative Examples 1 to 3 were measured using DIGIMICRO MH-15 (main body) and ZC-101 (counter) manufactured by NIKON. The thickness of the light diffusion layer was determined by subtracting the material thickness of 80 μm.
　［ヘイズ値の測定］
　実施例１、２および比較例１~３で得られた光拡散フィルムについて、ヘイズ値を測定した。測定結果を表１に示す。なお、フィルムに光を照射して透過した光線の全量を表す全光線透過率（Ｔｔ）と、フィルムにより拡散されて透過した拡散光線透過率（Ｔｄ）との比から下記式（１）：
　ヘイズ（％）＝（Ｔｄ／Ｔｔ）×１００　　　　　（１）
によりヘイズ値を求める。ここで、全光線透過率（Ｔｔ）は、入射光と同軸のまま透過した平行光線透過率（Ｔｐ）と拡散光線透過率（Ｔｄ）との和である。全光線透過率（Ｔｔ）および拡散光線透過率（Ｔｄ）は、ＪＩＳ　Ｋ　７３６１に準拠し、ヘイズ透過率計（株式会社村上色彩技術研究所製　ＨＭ−１５０）を用いて測定した。 [Measurement of haze value]
The haze values of the light diffusion films obtained in Examples 1 and 2 and Comparative Examples 1 to 3 were measured. The measurement results are shown in Table 1. In addition, from the ratio of the total light transmittance (Tt) representing the total amount of light transmitted through irradiation of the film and the diffused light transmittance (Td) diffused and transmitted by the film, the following formula (1):
Haze (%) = (Td / Tt) × 100 (1)
To obtain the haze value. Here, the total light transmittance (Tt) is the sum of the parallel light transmittance (Tp) and the diffused light transmittance (Td) transmitted coaxially with the incident light. Total light transmittance (Tt) and diffused light transmittance (Td) were measured using a haze transmittance meter (HM-150 manufactured by Murakami Color Research Laboratory Co., Ltd.) in accordance with JIS K 7361.
　サンプルの反りを防止するため、光学的に透明な粘着剤を用いて第２光拡散層が表面となるようにガラス基板に貼合し、その状態で全ヘイズを測定した。 In order to prevent the sample from warping, it was bonded to a glass substrate using an optically transparent adhesive so that the second light diffusion layer was on the surface, and the total haze was measured in that state.
　内部ヘイズの測定は、フィルム表面にヘイズがほぼ０のトリアセチルセルロースフィルムをグリセリンで貼り付けて、フィルム外側の影響を消去することにより、全ヘイズの測定と同様にして行った。 The measurement of the internal haze was performed in the same manner as the measurement of the total haze by sticking a triacetyl cellulose film having a haze of almost 0 to the film surface with glycerin to eliminate the influence of the outside of the film.
　外部ヘイズは、上記全ヘイズおよび内部ヘイズの測定値から下式により求めた。
　外部ヘイズ（％）＝全ヘイズ（％）−内部ヘイズ（％） The external haze was determined from the measured values of the total haze and internal haze according to the following formula.
External haze (%) = Total haze (%)-Internal haze (%)
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　［液晶表示装置での評価］
　ＩＰＳモードの３２型液晶テレビ「ＶＩＥＲＡ　ＴＨ−３２ＬＺ８５」（パナソニック株式会社製）のバックライト装置に、正面方向（表示面の法線方向）に対して７０°方向の輝度値が１０％である光拡散板と、稜線に直交する垂直断面における稜線に相当する頂点の頂角が９５°である線状プリズム部を有するプリズムフィルムを２枚使用し、一方のプリズムフィルムはその線状プリズムの稜線の方向が第１偏光板の透過軸に略平行となるように配置され、他方のプリズムフィルムは、その線状プリズムの稜線の方向が第２偏光板の透過軸に略平行となるように配置した。そして、液晶セルの光出射面側の偏光板を剥がして、沃素系通常偏光板「ＴＲＷ８４２ＡＰ７」（住友化学株式会社製）をクロスニコルとなるように貼合し、その上に、実施例１、２および比較例１~３で作製した光拡散フィルムを貼合して、液晶表示装置を作製した。 [Evaluation with liquid crystal display]
Light having a luminance value of 10% in the 70 ° direction relative to the front direction (normal direction of the display surface) on the backlight device of the 32-inch LCD TV “VIERA TH-32LZ85” (manufactured by Panasonic Corporation) in the IPS mode Two prism films having a diffuser plate and a linear prism portion having an apex angle corresponding to a ridge line in a vertical cross section perpendicular to the ridge line of 95 ° are used, and one prism film is a ridge line of the linear prism. The direction is arranged so that the direction is substantially parallel to the transmission axis of the first polarizing plate, and the other prism film is arranged so that the direction of the ridge line of the linear prism is substantially parallel to the transmission axis of the second polarizing plate. . Then, the polarizing plate on the light emitting surface side of the liquid crystal cell was peeled off, and an iodine-based normal polarizing plate “TRW842AP7” (manufactured by Sumitomo Chemical Co., Ltd.) was bonded so as to be crossed Nicol. 2 and Comparative Examples 1 to 3 were bonded together to produce a liquid crystal display device.
　作製した液晶表示装置について、（株）トプコン製の輝度計”ＢＭ５Ａ”型を用いて正面コントラストの測定を行った。また、視野角（液晶表示装置の正面方向とのなす角度）が４０°、５０°および６０°である方向から見た表示品位の評価を行った。実施例１、２、比較例１~３のそれぞれの光拡散フィルムを用いた液晶表示装置についての正面コントラストの測定結果を表２に、視野角の評価結果を表３に示す。 About the produced liquid crystal display device, the front contrast was measured using the luminance meter "BM5A" type | mold by Topcon Co., Ltd. type | mold. In addition, the display quality as viewed from the direction in which the viewing angle (angle formed with the front direction of the liquid crystal display device) is 40 °, 50 °, and 60 ° was evaluated. Table 2 shows the measurement results of the front contrast and Table 3 shows the evaluation results of the viewing angles for the liquid crystal display devices using the light diffusion films of Examples 1 and 2 and Comparative Examples 1 to 3.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
　表２、３に示されるように、実施例１および実施例２の光拡散フィルムを用いた液晶表示装置の正面コントラストは、比較例１および比較例３と比べてもあまり低下せず、ほぼ同等と言えるレベルを維持しつつ、いずれも６０°以上の広い視野角を有していた。 As shown in Tables 2 and 3, the front contrast of the liquid crystal display devices using the light diffusing films of Example 1 and Example 2 did not decrease much as compared with Comparative Example 1 and Comparative Example 3, and was almost the same. All of them had a wide viewing angle of 60 ° or more while maintaining a level that could be said.
　これに対して、比較例１では、光拡散層中の透光性粒子の配合量が少ないため、光拡散性が弱く、正面コントラストは高いものの、視野角が狭い。また、比較例２では、光拡散層中の透光性粒子の配合量が多すぎるため、光拡散性が強すぎて、視野角は広いものの、正面コントラストが大きく低下している。比較例３では、光拡散層に用いた透光性樹脂と透光性粒子の屈折率差が小さいため、光拡散性が弱く、正面コントラストは高いものの、視野角が狭くなっている。 On the other hand, in Comparative Example 1, since the blending amount of the translucent particles in the light diffusion layer is small, the light diffusion is weak and the front contrast is high, but the viewing angle is narrow. In Comparative Example 2, the amount of translucent particles in the light diffusion layer is too large, so that the light diffusibility is too strong and the viewing angle is wide, but the front contrast is greatly reduced. In Comparative Example 3, since the difference in refractive index between the translucent resin used for the light diffusion layer and the translucent particles is small, the light diffusion is weak and the front contrast is high, but the viewing angle is narrow.
　本発明の光拡散フィルムを含む液晶表示装置は、シンチレーションをほとんど生じることなく、正面コントラストが高く視野角も広い。 The liquid crystal display device including the light diffusion film of the present invention has little front scintillation, high front contrast, and wide viewing angle.
　１：液晶セル、１１ａ，１１ｂ　透明基板、
　１２：液晶層、
　２：バックライト装置、
　２１：ケース、
　２２：冷陰極管、
　３：光拡散板（光拡散手段）、
　４ａ，４ｂ：プリズムフィルム（光偏向手段）、
　４１ａ，４１ｂ：線状プリズム部、
　４２ａ，４２ｂ：稜線、
　５：第１偏光板、
　６：第２偏光板、
　７：光拡散フィルム、
　７１：基材フィルム、
　７２：光拡散層、
　７２１：透光性樹脂、
　７２２：透光性微粒子、
　７３：透光性樹脂層、
　８：位相差板 1: liquid crystal cell, 11a, 11b transparent substrate,
12: Liquid crystal layer,
2: Backlight device,
21: Case,
22: Cold cathode tube,
3: Light diffusion plate (light diffusion means),
4a, 4b: Prism film (light deflection means),
41a, 41b: linear prism portion,
42a, 42b: ridge line,
5: First polarizing plate,
6: Second polarizing plate,
7: light diffusion film,
71: base film,
72: a light diffusion layer,
721: translucent resin,
722: Translucent fine particles,
73: Translucent resin layer,
8: Retardation plate

Claims (8)

  1. 　基材フィルムと、透光性樹脂及び透光性樹脂中に分散された透光性微粒子からなり、表面が平坦な光拡散層とを有する光拡散フィルムであって、
    　前記透光性微粒子の平均粒径が０．５μｍ以上２０μｍ未満であり、
    　前記透光性微粒子の含有量が前記透光性樹脂１００重量部に対して２５重量部以上６０重量部以下であり、
    　前記透光性微粒子の屈折率が前記透光性樹脂の屈折率よりも大きく、
    　前記透光性微粒子の屈折率と前記透光性樹脂の屈折率との差が０．０４以上０．２以下であり、
    　前記光拡散層の厚さは前記透光性微粒子の平均粒径の１倍以上３倍以下である光拡散フィルム。     A light diffusing film comprising a base film, a translucent fine particle dispersed in the translucent resin and the translucent resin, and a light diffusing layer having a flat surface,
    The translucent fine particles have an average particle size of 0.5 μm or more and less than 20 μm,
    The content of the translucent fine particles is 25 parts by weight or more and 60 parts by weight or less with respect to 100 parts by weight of the translucent resin,
    The refractive index of the translucent fine particles is larger than the refractive index of the translucent resin,
    The difference between the refractive index of the translucent fine particles and the refractive index of the translucent resin is 0.04 or more and 0.2 or less,
    The light diffusing film has a thickness of 1 to 3 times the average particle diameter of the translucent fine particles.
  2. 　全ヘイズが４０％以上７０％以下であり、内部ヘイズが４０％以上７０％以下であり、外部ヘイズが１％未満である請求の範囲１に記載の光拡散フィルム。 The light diffusing film according to claim 1, wherein the total haze is from 40% to 70%, the internal haze is from 40% to 70%, and the external haze is less than 1%.
  3. 　前記光拡散層の基材フィルムとは反対側に、さらに反射防止層を有する請求の範囲１または２に記載の光拡散フィルム。 The light diffusing film according to claim 1 or 2, further comprising an antireflection layer on the side opposite to the base film of the light diffusing layer.
  4. 　バックライト装置と、光偏向手段と、第１偏光板と、一対の基板の間に液晶層が設けられてなる液晶セルと、第２偏光板と、光拡散フィルムとがこの順で配置され、第１偏光板と第２偏光板とは、それらの透過軸が直交ニコルの関係となるように配置された液晶表示装置であって、
    　前記光拡散フィルムが、請求の範囲１~３のいずれかに記載の光拡散フィルムである液晶表示装置。     A backlight device, a light deflecting means, a first polarizing plate, a liquid crystal cell in which a liquid crystal layer is provided between a pair of substrates, a second polarizing plate, and a light diffusion film are arranged in this order, The first polarizing plate and the second polarizing plate are liquid crystal display devices arranged such that their transmission axes have a crossed Nicols relationship,
    A liquid crystal display device, wherein the light diffusion film is the light diffusion film according to any one of claims 1 to 3.
  5. 　前記光拡散フィルムにおける光拡散層が、基材フィルムよりも光出射側となるように配置されている請求の範囲４に記載の液晶表示装置。 The liquid crystal display device according to claim 4, wherein the light diffusion layer in the light diffusion film is disposed so as to be closer to the light emission side than the base film.
  6. 　前記光偏向手段は、光出射側に稜線を有する線状プリズム部を光出射側に所定間隔で複数備えたプリズムフィルムを２枚有し、
    　一方のプリズムフィルムは、その線状プリズム部の稜線の方向が前記第１偏光板の透過軸に対して実質的に平行となるように配置され、他方のプリズムフィルムは、その線状プリズムの稜線の方向が第２偏光板の透過軸に対して実質的に平行となるように配置されている請求の範囲４または５に記載の液晶表示装置。     The light deflecting means has two prism films each having a plurality of linear prism portions having ridge lines on the light emitting side at predetermined intervals on the light emitting side,
    One prism film is arranged such that the direction of the ridgeline of the linear prism portion is substantially parallel to the transmission axis of the first polarizing plate, and the other prism film is the ridgeline of the linear prism. 6. The liquid crystal display device according to claim 4, wherein the liquid crystal display device is disposed so that the direction is substantially parallel to the transmission axis of the second polarizing plate.
  7. 　前記線状プリズム部の稜線に直交する垂直断面において、稜線に相当する頂点の頂角が９０~１１０°である請求の範囲４~６のいずれかに記載の液晶表示装置。 The liquid crystal display device according to any one of claims 4 to 6, wherein an apex angle corresponding to the ridge line is 90 to 110 ° in a vertical cross section perpendicular to the ridge line of the linear prism portion.
  8. 　前記バックライト装置と前記光偏向手段との間に、さらに光拡散手段を有する請求の範囲４~７のいずれかに記載の液晶表示装置。 The liquid crystal display device according to any one of claims 4 to 7, further comprising a light diffusing means between the backlight device and the light deflecting means.
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CN114114496B (en) * 2020-08-31 2023-03-21 宁波激智科技股份有限公司 Polarization-maintaining optical film and preparation method thereof

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CN102472841A (en) 2012-05-23
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TW201113560A (en) 2011-04-16
TWI507740B (en) 2015-11-11

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