WO2017183499A1 - Liquid crystal display device - Google Patents

Liquid crystal display device Download PDF

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Publication number
WO2017183499A1
WO2017183499A1 PCT/JP2017/014641 JP2017014641W WO2017183499A1 WO 2017183499 A1 WO2017183499 A1 WO 2017183499A1 JP 2017014641 W JP2017014641 W JP 2017014641W WO 2017183499 A1 WO2017183499 A1 WO 2017183499A1
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WO
WIPO (PCT)
Prior art keywords
liquid crystal
display device
polarizer
crystal display
optical compensation
Prior art date
Application number
PCT/JP2017/014641
Other languages
French (fr)
Japanese (ja)
Inventor
勝則 高田
映子 末房
▲吉▼紹 北村
木村 啓介
梅本 清司
Original Assignee
日東電工株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from JP2017030729A external-priority patent/JP2017194672A/en
Application filed by 日東電工株式会社 filed Critical 日東電工株式会社
Priority to US15/766,084 priority Critical patent/US11079624B2/en
Priority to CN201780004045.8A priority patent/CN108351551A/en
Priority to EP17785839.6A priority patent/EP3447569A4/en
Priority to KR1020187013354A priority patent/KR20180127305A/en
Publication of WO2017183499A1 publication Critical patent/WO2017183499A1/en

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    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00Optical elements other than lenses
    • G02B5/30Polarising elements
    • GPHYSICS
    • G02OPTICS
    • G02FOPTICAL 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
    • G02F1/00Devices 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
    • G02F1/01Devices 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 
    • G02F1/13Devices 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
    • G02F1/133Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333Constructional arrangements; Manufacturing methods
    • GPHYSICS
    • G02OPTICS
    • G02FOPTICAL 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
    • G02F1/00Devices 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
    • G02F1/01Devices 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 
    • G02F1/13Devices 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
    • G02F1/133Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333Constructional arrangements; Manufacturing methods
    • G02F1/1335Structural association of cells with optical devices, e.g. polarisers or reflectors
    • GPHYSICS
    • G02OPTICS
    • G02FOPTICAL 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
    • G02F1/00Devices 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
    • G02F1/01Devices 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 
    • G02F1/13Devices 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
    • G02F1/133Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333Constructional arrangements; Manufacturing methods
    • G02F1/1335Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/13363Birefringent elements, e.g. for optical compensation

Definitions

  • the present invention relates to a liquid crystal display device.
  • Liquid crystal display devices are used in a wide range of applications, including televisions, smartphones, personal computer monitors, and digital cameras, and their applications are expanding. As a result, depending on the application of the liquid crystal display device, a configuration in which the liquid crystal display device is embedded in various structures is employed. Specific examples of such applications include operation information screens in railway vehicles (for example, next station guidance display for passenger vehicles), display units such as various instruments and navigation systems arranged on the instrument panel and console of automobiles, There are various instruments in airplane cockpits and monitors installed in hospitals, guard rooms or battle command centers.
  • a cover sheet having a transmissive portion corresponding to the display area of the liquid crystal display device is disposed on the viewing side of the liquid crystal display device as necessary in order to protect and / or design the liquid crystal display device. Can be done.
  • there is a step between the display screen and the outermost surface of the portion in which the liquid crystal display device is embedded for example, the outermost surface of a housing, a wall, a monitor desk, or a cover sheet arranged as necessary.
  • the level difference may affect the visibility depending on the application and / or situation.
  • Patent Document 1 proposes a technique of arranging a neutral density filter on the viewing side.
  • this technique has a problem that the display screen itself becomes dark although the step is difficult to recognize.
  • the present invention has been made to solve the above-described conventional problems, and the object of the present invention is to have a step between the display screen and the outermost surface, and the step is difficult to recognize and has a bright display.
  • An object of the present invention is to provide a liquid crystal display device capable of realizing the above.
  • the liquid crystal display device of the present invention includes a liquid crystal cell; a first polarizer disposed on the back side of the liquid crystal cell; and a position corresponding to the display area of the liquid crystal cell disposed on the viewing side of the liquid crystal cell.
  • the absorption axis direction of the first polarizer and the absorption axis direction of the second polarizer are substantially perpendicular to each other.
  • the liquid crystal display device further includes a first optical compensation layer having Re (550) of 100 nm to 180 nm between the cover sheet and the second polarizer, and A second optical compensation layer having Re (550) of 100 nm to 180 nm is further provided between the cover sheet and the liquid crystal cell.
  • the angle formed by the slow axis direction of the first optical compensation layer and the absorption axis of the second polarizer is 35 ° to 55 ° or 125 ° to 145 °, and The slow axis direction of the first optical compensation layer and the slow axis direction of the second optical compensation layer are substantially perpendicular to each other.
  • the first optical compensation layer and the second optical compensation layer satisfy a relationship of Re (450) ⁇ Re (550).
  • the transmission part of the cover sheet is an opening, and the opening is filled with an adhesive.
  • the adhesive has a refractive index of 1.30 to 1.70.
  • the polarizer on the viewing side is arranged on the viewing side from the step, thereby maintaining the brightness of the display screen, Visibility can be improved by making it difficult to recognize the step.
  • the difficulty of recognizing a step can be further remarkably improved by further arranging so-called ⁇ / 4 plates on both sides of the step.
  • FIG. 1 is a schematic cross-sectional view of a liquid crystal display device according to an embodiment of the present invention. It is a schematic sectional drawing of the liquid crystal display device by another embodiment of this invention. It is a schematic sectional drawing of the liquid crystal display device by another embodiment of this invention. It is a schematic sectional drawing of the liquid crystal display device by another embodiment of this invention. It is a schematic sectional drawing of the liquid crystal display device by another embodiment of this invention. It is a schematic sectional drawing of the liquid crystal display device by another embodiment of this invention. It is a schematic sectional drawing of the liquid crystal display device by another embodiment of this invention. It is a schematic sectional drawing of the liquid crystal display device by another embodiment of this invention. It is a schematic sectional drawing of the liquid crystal display device by another embodiment of this invention. It is a schematic sectional drawing of the liquid crystal display device by another embodiment of this invention. It is a schematic sectional drawing of the liquid crystal display device by another embodiment of this invention. It is a schematic sectional drawing of the liquid crystal display device by another
  • Refractive index (nx, ny, nz) “Nx” is the refractive index in the direction in which the in-plane refractive index is maximum (ie, the slow axis direction), and “ny” is the direction orthogonal to the slow axis in the plane (ie, the fast axis direction). “Nz” is the refractive index in the thickness direction.
  • Refractive index (nx, ny, nz) “Nx” is the refractive index in the direction in which the in-plane refractive index is maximum (ie, the slow axis direction), and “ny” is the direction orthogonal to the slow axis in the plane (ie, the fast axis direction). “Nz” is the refractive index in the thickness direction.
  • In-plane retardation (Re) “Re ( ⁇ )” is an in-plane retardation measured with light having a wavelength of ⁇ nm at 23 ° C.
  • Re (550) is an in-plane retardation measured with light having a wavelength of 550 nm at 23 ° C.
  • Thickness direction retardation (Rth) is a retardation in the thickness direction measured with light having a wavelength of ⁇ nm at 23 ° C.
  • Rth (550) is a retardation in the thickness direction measured with light having a wavelength of 550 nm at 23 ° C.
  • Substantially orthogonal or parallel include the case where the angle between the two directions is 90 ° ⁇ 10 °, preferably 90 ° ⁇ 7 °. And more preferably 90 ° ⁇ 5 °.
  • substantially parallel and “substantially parallel” include the case where the angle between two directions is 0 ° ⁇ 10 °, preferably 0 ° ⁇ 7 °, more preferably 0 ° ⁇ 5 °.
  • orthogonal or “parallel” may include a substantially orthogonal state or a substantially parallel state.
  • A. 1 is a schematic sectional view of a liquid crystal display device according to an embodiment of the present invention.
  • the liquid crystal display device 100 includes a liquid crystal cell 10, a first polarizer 20 disposed on the back side of the liquid crystal cell 10, a cover sheet 40 disposed on the viewing side of the liquid crystal cell 10, and the viewing side of the cover sheet 40. And a second polarizer 60 disposed on the surface.
  • the cover sheet 40 has a transmission part 42 at a position corresponding to the display area of the liquid crystal cell 10.
  • the transmission part includes a physical transmission part (for example, an opening) and an optical transmission part (for example, a transparent part). In the illustrated example, an opening is shown.
  • the second polarizer 60 is disposed so as to cover the transmission part 42 of the cover sheet 40.
  • the second polarizer is disposed on the outermost surface side so as to cover the transmission part of the cover sheet, thereby making it difficult to recognize the step between the outermost surface of the apparatus and the display screen.
  • the visibility of the liquid crystal display device can be improved.
  • the step can be made difficult to recognize due to the transmittance specific to the polarizer, and the polarizer can efficiently transmit polarized light in a predetermined direction, so that the light is reduced overall.
  • the brightness of the display screen can be maintained as compared with the neutral density filter.
  • the transmission part of a cover sheet is an opening part, it can make it difficult to recognize a level
  • “to make it difficult to recognize a level difference” may be referred to as “to reduce a visual level difference”.
  • the absorption axis direction of the first polarizer 20 and the absorption axis direction of the second polarizer 60 are substantially orthogonal or parallel, typically substantially. Are orthogonal.
  • the liquid crystal display device may be in a so-called O mode or in a so-called E mode.
  • the “O-mode liquid crystal display device” refers to a device in which the absorption axis direction of a polarizer disposed on the light source side of the liquid crystal cell and the initial alignment direction of the liquid crystal cell are substantially parallel.
  • the “E mode liquid crystal display device” refers to a device in which the absorption axis direction of a polarizer disposed on the light source side of the liquid crystal cell and the initial alignment direction of the liquid crystal cell are substantially orthogonal to each other.
  • “Initial alignment direction of liquid crystal cell” refers to the direction in which the in-plane refractive index of the liquid crystal layer that is the result of alignment of liquid crystal molecules contained in the liquid crystal layer is maximized in the absence of an electric field (ie, the slow axis direction) Say.
  • FIG. 2 is a schematic cross-sectional view of a liquid crystal display device according to another embodiment of the present invention.
  • the liquid crystal display device 101 further includes a first optical compensation layer 50 between the cover sheet 40 and the second polarizer 60, and a second optical compensation layer between the cover sheet 40 and the liquid crystal cell 10. 70 is further provided.
  • Re (550) is typically 100 nm to 180 nm, preferably 110 nm to 170 nm, more preferably 120 nm to 160 nm.
  • the angle formed between the slow axis direction of the first optical compensation layer 50 and the absorption axis direction of the second polarizer 60 is typically 35 ° to 55 °, preferably 38 ° to 52 °.
  • the angle is typically 125 ° to 145 °, preferably 128 ° to 142 °, more preferably 132 ° to 138 °, and even more preferably about 135 °. If the angle is in such a range, an excellent circular polarization function and antireflection function can be realized by a combination of the first optical compensation layer and the second polarizer. As a result, it is possible to remarkably reduce the visual step while maintaining the brightness of the display screen that is practically acceptable. That is, for example, the visual step can be reduced without reducing the transmittance as compared with the case where the visual step is reduced by reducing the transmittance using a neutral density filter.
  • the first optical compensation layer and the second polarizer may be introduced into the liquid crystal display device as separate members, and the first optical compensation layer and the second optical compensation layer may be introduced.
  • the slow axis direction of the first optical compensation layer 50 and the slow axis direction of the second optical compensation layer 70 are preferably substantially orthogonal.
  • the absorption axis direction of the second polarizer 60 is 0 °
  • the absorption axis direction of the first polarizer 20 is 90 °
  • the slow axis direction of the first optical compensation layer 50 is 45 °.
  • the slow axis direction of the second optical compensation layer 70 may be set to ⁇ 45 °.
  • the constituent materials, optical characteristics, thickness, and the like of the first optical compensation layer and the second optical compensation layer may be the same or different.
  • the first optical compensation layer and the second optical compensation layer each satisfy a relationship of Re (450) ⁇ Re (550).
  • Re (450) ⁇ Re (550)
  • the optical compensation layer satisfies such a relationship, an excellent antireflection function is realized, and as a result, the visual step can be reduced.
  • FIG. 3 is a schematic cross-sectional view of a liquid crystal display device according to still another embodiment of the present invention.
  • the adhesive fills the opening of the cover sheet 40.
  • the pressure-sensitive adhesive may fill only the opening, or may be a part of the pressure-sensitive adhesive layer 80 provided between the cover sheet 40 and the second polarizer 60.
  • the air layer formed by the openings is eliminated, and reflection and / or refraction at the layer interface can be suppressed.
  • the brightness of the display screen can be further improved and the visual level difference can be further significantly reduced.
  • the said transparent part may be comprised with an adhesive.
  • the refractive index of the pressure-sensitive adhesive is preferably 1.30 to 1.70, more preferably 1.40 to 1.60, and still more preferably 1.45 to 1.55.
  • FIG. 5 is a schematic sectional view of a liquid crystal display device according to still another embodiment of the present invention.
  • the cover sheet 40 is curved, and the second polarizer 60 is curved along the cover sheet 40.
  • the cover sheet 40 may be curved in any suitable form. Specifically, the viewing side may be curved so as to be convex, or the viewing side may be curved so as to be concave. Further, any direction in the plane of the cover sheet 40 may be curved as an axis.
  • the liquid crystal cell 10 and the first polarizer 20 may be curved along the cover sheet 40 as in the liquid crystal display device 105 shown in FIG.
  • the liquid crystal display devices 104 and 105 of the present embodiment in which the cover sheet is curved have a wide range of design choices and great commercial value.
  • FIG. 7 is a schematic cross-sectional view of a liquid crystal display device according to still another embodiment of the present invention.
  • the adhesive fills the opening of the cover sheet 40.
  • the pressure-sensitive adhesive may fill only the opening, or may be a part of the pressure-sensitive adhesive layer 80 provided between the cover sheet 40 and the second polarizer 60.
  • the cover sheet 40 is curved, and the pressure-sensitive adhesive fills a gap between the cover sheet 40 and the liquid crystal cell 10 that is generated when the cover sheet 40 is curved. If it is such a structure, the fall of the mechanical strength by the cover sheet 40 curving can be suppressed.
  • FIG. 8 is a schematic cross-sectional view of a liquid crystal display device according to still another embodiment of the present invention.
  • the liquid crystal display device 107 includes a liquid crystal cell 10A, a first polarizer 20A disposed on the back side of the liquid crystal cell 10A, a liquid crystal cell 10B, and a first polarizer 20B disposed on the back side of the liquid crystal cell 10B. And a cover sheet 40 disposed on the viewing side of the liquid crystal cell 10A and the liquid crystal cell 10B, and a second polarizer 60 disposed on the viewing side of the cover sheet 40.
  • the cover sheet 40 of the liquid crystal display device 107 includes a first transmission part 42A at a position corresponding to the display area of the liquid crystal cell 10A, and a second transmission part 42B at a position corresponding to the display area of the liquid crystal cell 10B.
  • the liquid crystal display device 107 has two display screens corresponding to each liquid crystal cell, and arranges the second polarizer on the outermost surface side so as to cover the two transmission portions of the cover sheet, thereby providing the outermost surface of the device. It is difficult to recognize the step between the two display screens and the visibility on the two display screens can be improved.
  • the liquid crystal display device having two display screens and corresponding two liquid crystal cells has been described as an example, the liquid crystal display device of the present invention has three or more display screens and corresponding liquid crystal cells. May be.
  • FIG. 9 is a schematic cross-sectional view of a liquid crystal display device according to still another embodiment of the present invention.
  • the liquid crystal display device 108 of the present embodiment has two display screens as with the liquid crystal display device 107.
  • the cover sheet 40 is bent at a bent portion 90 between the transmissive portion 42A and the transmissive portion 42B, and the second polarizer 60 is bent along the cover sheet 40. Accordingly, the liquid crystal display device 108 can display images in different directions using the two display screens.
  • the cover sheet may have a plurality of bent portions, and may have three or more display screens and corresponding liquid crystal cells sandwiching each bent portion.
  • the liquid crystal display device can be used by being incorporated (typically embedded) in various structures, for example.
  • structures include building structures (e.g., guard room and battle command center walls), railroad vehicles (e.g., walls above doors), automobiles (e.g., instrument panels, consoles), airplanes (e.g., Cockpit), home appliances and AV equipment.
  • the liquid crystal display device further includes a backlight unit (not shown) practically.
  • the backlight unit typically includes a light source and a light guide plate.
  • the backlight unit may further include any appropriate other member (for example, a diffusion sheet, a prism sheet).
  • the liquid crystal display device may further include any appropriate other member.
  • another optical compensation layer (retardation film) may be further disposed.
  • the optical characteristics, number, combination, arrangement position, and the like of another optical compensation layer can be appropriately selected depending on the purpose and desired optical characteristics.
  • various surface treatment layers may be disposed on the outermost surface. Specific examples of the surface treatment layer include an antiglare layer, an antireflection layer, and a hard coat layer.
  • a plurality of surface treatment layers may be disposed. The type, number, combination, and the like of the surface treatment layer can be appropriately selected depending on the purpose.
  • the above embodiments may be combined as appropriate, and the configuration in the above embodiment may be replaced with an optically equivalent configuration.
  • the embodiment of FIG. 2 may be combined with the embodiment of FIG.
  • the liquid crystal display device 103 of FIG. 4 includes a combination of the first optical compensation layer 50 and the second optical compensation layer 70 and an adhesive that fills the opening of the cover sheet.
  • the opening of the cover sheet in the illustrated example may be replaced with a transparent portion.
  • the embodiment of FIG. 6 may be combined with the embodiment of FIG.
  • liquid crystal cell 10 includes a liquid crystal cell 10A and a liquid crystal cell 10B, each configuration is curved, and the cover sheet 40 is first positioned at a position corresponding to the display area of the liquid crystal cell 10A. 42A, and a second transmissive portion 42B is provided at a position corresponding to the display area of the liquid crystal cell 10B.
  • the liquid crystal cell 10 includes a pair of substrates 11 and 11 'and a liquid crystal layer 12 as a display medium sandwiched between the substrates.
  • a color filter and a black matrix are provided on one substrate, a switching element that controls the electro-optical characteristics of the liquid crystal on the other substrate, and a scanning line that supplies a gate signal to the switching element.
  • a signal line for supplying a source signal, a pixel electrode, and a counter electrode are provided.
  • the distance between the substrates (cell gap) is controlled by a spacer or the like.
  • an alignment film made of polyimide can be provided on the side of the substrate in contact with the liquid crystal layer.
  • the liquid crystal layer includes liquid crystal molecules aligned in a homeotropic alignment in the absence of an electric field.
  • “Liquid crystal molecules aligned in homeotropic alignment” means a state in which the alignment vector of the liquid crystal molecules is aligned perpendicularly to the substrate plane as a result of the interaction between the aligned substrate and the liquid crystal molecules. .
  • a typical example of the drive mode using such a liquid crystal layer exhibiting a three-dimensional refractive index is a vertical alignment (VA) mode.
  • the VA mode includes a multi-domain VA (MVA) mode.
  • the liquid crystal layer includes liquid crystal molecules aligned in a homogeneous alignment in the absence of an electric field.
  • “Liquid crystal molecules aligned in a homogeneous arrangement” means a state in which the alignment vector of the liquid crystal molecules is aligned in parallel and uniformly with respect to the substrate plane as a result of the interaction between the aligned substrate and the liquid crystal molecules.
  • Typical examples of drive modes using such a liquid crystal layer exhibiting a three-dimensional refractive index include an in-plane switching (IPS) mode and a fringe field switching (FFS) mode.
  • IPS in-plane switching
  • FFS fringe field switching
  • the IPS mode includes a super-in-plane switching (S-IPS) mode and an advanced super-in-plane switching (AS-IPS) mode using a V-shaped electrode or a zigzag electrode.
  • the FFS mode includes an advanced fringe field switching (A-FFS) mode and an ultra fringe field switching (U-FFS) mode employing a V-shaped electrode or a zigzag electrode.
  • the resin film forming the polarizer may be a single-layer resin film or a laminate of two or more layers.
  • polarizers composed of a single-layer resin film include hydrophilic polymer films such as polyvinyl alcohol (PVA) films, partially formalized PVA films, and ethylene / vinyl acetate copolymer partially saponified films.
  • PVA polyvinyl alcohol
  • polyene-based oriented films such as those subjected to dyeing treatment and stretching treatment with dichroic substances such as iodine and dichroic dyes, PVA dehydrated products and polyvinyl chloride dehydrochlorinated products.
  • a polarizer obtained by dyeing a PVA film with iodine and uniaxially stretching is used because of excellent optical properties.
  • the dyeing with iodine is performed, for example, by immersing a PVA film in an aqueous iodine solution.
  • the stretching ratio of the uniaxial stretching is preferably 3 to 7 times.
  • the stretching may be performed after the dyeing treatment or may be performed while dyeing. Moreover, you may dye
  • the PVA film is subjected to swelling treatment, crosslinking treatment, washing treatment, drying treatment and the like. For example, by immersing the PVA film in water and washing it before dyeing, not only can the surface of the PVA film be cleaned of dirt and anti-blocking agents, but the PVA film can be swollen to cause uneven staining. Can be prevented.
  • the thickness of the polarizer is preferably 1 ⁇ m to 80 ⁇ m, more preferably 10 ⁇ m to 50 ⁇ m, still more preferably 15 ⁇ m to 40 ⁇ m, and particularly preferably 20 ⁇ m to 30 ⁇ m. If the thickness of the polarizer is in such a range, durability under high temperature and high humidity can be excellent.
  • the polarizer preferably exhibits absorption dichroism at any wavelength between 380 nm and 780 nm.
  • the single transmittance of the polarizer is preferably 40.0% to 46.0%, more preferably 41.0% to 44.0%.
  • the polarization degree of the polarizer is preferably 97.0% or more, more preferably 99.0% or more, and further preferably 99.9% or more.
  • Each of the first polarizer 20 and the second polarizer 60 may be provided with a protective layer (not shown) on at least one surface. That is, each of the first polarizer 20 and the second polarizer 60 may be incorporated in a liquid crystal display device as a polarizing plate. The second polarizer 60 may be incorporated in the liquid crystal display device as a circularly polarizing plate as described above.
  • the protective layer is formed of any appropriate film that can be used as a protective layer for the polarizer.
  • the material as the main component of the film include cellulose resins such as triacetyl cellulose (TAC), polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, polyimide-based, polyethersulfone-based, and polysulfone-based materials.
  • transparent resins such as polystyrene, polynorbornene, polyolefin, (meth) acryl, and acetate.
  • thermosetting resins such as (meth) acrylic, urethane-based, (meth) acrylurethane-based, epoxy-based, and silicone-based or ultraviolet curable resins are also included.
  • a glassy polymer such as a siloxane polymer is also included.
  • a polymer film described in JP-A-2001-343529 (WO01 / 37007) can also be used.
  • a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and nitrile group in the side chain for example, a resin composition having an alternating copolymer of isobutene and N-methylmaleimide and an acrylonitrile / styrene copolymer can be mentioned.
  • the polymer film can be, for example, an extruded product of the resin composition.
  • the thickness of the protective layer is typically 5 mm or less, preferably 1 mm or less, more preferably 1 ⁇ m to 500 ⁇ m, and even more preferably 5 ⁇ m to 150 ⁇ m.
  • the thickness of the protective layer is a thickness including the thickness of the surface treatment layer.
  • the inner protective layer is optically isotropic. It is preferable. “Optically isotropic” means that the in-plane retardation Re (550) is 0 nm to 10 nm and the thickness direction retardation Rth (550) is ⁇ 10 nm to +10 nm.
  • the inner protective layer can be composed of any suitable material as long as it is optically isotropic. The material can be appropriately selected from the materials described above with respect to the protective layer, for example.
  • the thickness of the inner protective layer is preferably 5 ⁇ m to 200 ⁇ m, more preferably 10 ⁇ m to 100 ⁇ m, and still more preferably 15 ⁇ m to 95 ⁇ m.
  • the cover sheet 40 may be provided for protection and / or design requirements of the liquid crystal display device when the liquid crystal display device is incorporated into a structure. Therefore, the cover sheet 40 typically has a transmissive portion 42 corresponding to the display area of the liquid crystal cell so as not to hinder the display function of the liquid crystal display device.
  • the transmission part includes a physical transmission part (for example, an opening) and an optical transmission part (for example, a transparent part).
  • the cover sheet can be composed of any suitable material.
  • a typical example of the constituent material is a resin. This is because it has an appropriate strength as a cover sheet and is easy to be molded into a desired shape and to form an opening.
  • Specific examples of the resin include polyarylate, polyamide, polyimide, polyester, polyaryletherketone, polyamideimide, polyesterimide, polyvinyl alcohol, polyfumaric acid ester, polyethersulfone, polysulfone, norbornene resin, polycarbonate resin, cellulose resin and A polyurethane is mentioned. These resins may be used alone or in combination.
  • the cover sheet has light shielding properties in one embodiment.
  • the light shielding property can be imparted by blending a light shielding material (for example, carbon black) with the resin when the cover sheet is formed.
  • a light shielding material for example, carbon black
  • the cover sheet typically has light shielding properties except for the opening.
  • the cover sheet typically has light shielding properties except for the transparent portion. In this case, what is necessary is just to use resin which mix
  • the thickness of the cover sheet is preferably 0.1 mm to 5 mm, more preferably 0.3 mm to 3 mm. If it is such thickness, suitable intensity
  • the first optical compensation layer 50 has an in-plane retardation Re (550) of 100 nm to 180 nm, preferably 110 nm to 170 nm, more preferably 120 nm to 160 nm. . If the in-plane retardation of the first optical compensation layer is within such a range, the slow axis direction of the first optical compensation layer is set to 35 ° with respect to the absorption axis direction of the second polarizer as described above. By setting an angle of ⁇ 55 ° (particularly about 45 °) or 125 ° -145 ° (particularly about 135 °), an excellent circular polarization function and antireflection function can be realized. As a result, the visual level difference can be remarkably reduced while maintaining the brightness of the display screen that is practically acceptable.
  • Re in-plane retardation Re
  • the first optical compensation layer typically shows a relationship in which the refractive index characteristic is nx> ny ⁇ nz or nx> nz> ny.
  • the Nz coefficient of the first optical compensation layer is preferably 0.3 to 2.0, more preferably 0.5 to 1.5, and still more preferably 0.5 to 1.3. By satisfying such a relationship, more excellent antireflection characteristics can be achieved.
  • the first optical compensation layer may exhibit a reverse dispersion wavelength characteristic in which the retardation value increases according to the wavelength of the measurement light, and has a positive chromatic dispersion characteristic in which the retardation value decreases according to the wavelength of the measurement light. It may also be possible to show a flat chromatic dispersion characteristic in which the phase difference value hardly changes depending on the wavelength of the measurement light.
  • the first optical compensation layer preferably exhibits reverse dispersion wavelength characteristics. By exhibiting such characteristics, an antireflection function can be realized over a predetermined wavelength band by only using a combination of the first optical compensation layer and the second polarizer without further using a so-called ⁇ / 2 plate.
  • the in-plane retardation of the first optical compensation layer satisfies the relationship of Re (450) ⁇ Re (550).
  • Re (450) / Re (550) is preferably 0.8 or more and less than 1, and more preferably 0.8 or more and 0.95 or less.
  • the in-plane retardation of the first optical compensation layer preferably satisfies the relationship Re (550) ⁇ Re (650).
  • Re (550) / Re (650) is preferably 0.8 or more and less than 1, and more preferably 0.8 or more and 0.95 or less.
  • the first optical compensation layer is typically a retardation film formed of any appropriate resin capable of realizing the above characteristics.
  • the resin that forms the retardation film include polyarylate, polyamide, polyimide, polyester, polyaryletherketone, polyamideimide, polyesterimide, polyvinyl alcohol, polyfumaric acid ester, polyethersulfone, polysulfone, and norbornene resin.
  • a polycarbonate resin, a cellulose resin, and a polyurethane are mentioned. These resins may be used alone or in combination. Polyarylate, norbornene resin or polycarbonate resin is preferable.
  • the polyarylate is preferably represented by the following formula (I).
  • a and B each represent a substituent, which is a halogen atom, an alkyl group having 1 to 6 carbon atoms, or a substituted or unsubstituted aryl group, and A and B are the same or different. Also good. a and b represent the corresponding numbers of substitutions of A and B, and are integers of 1 to 4, respectively.
  • D is a covalent bond, CH 2 group, C (CH 3 ) 2 group, C (CZ 3 ) 2 group (where Z is a halogen atom), CO group, O atom, S atom, SO 2 group, Si (CH 2 CH 3 ) 2 groups and N (CH 3 ) groups.
  • R1 is a linear or branched alkyl group having 1 to 10 carbon atoms, or a substituted or unsubstituted aryl group.
  • R2 is a linear or branched alkyl group having 2 to 10 carbon atoms, or a substituted or unsubstituted aryl group.
  • R3, R4, R5 and R6 are each independently a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms, and R3, R4, R5 and R6 may be the same or different.
  • p1 is an integer of 0 to 3
  • p2 is an integer of 1 to 3
  • n is an integer of 2 or more.
  • the norbornene-based resin is a resin that is polymerized using a norbornene-based monomer as a polymerization unit.
  • Examples of the norbornene-based monomer include norbornene and alkyl and / or alkylidene substituted products thereof such as 5-methyl-2-norbornene, 5-dimethyl-2-norbornene, 5-ethyl-2-norbornene, and 5-butyl.
  • polar group-substituted products such as halogens; dicyclopentadiene, 2,3-dihydrodicyclopentadiene, etc .; dimethanooctahydronaphthalene, its alkyl and / or alkylidene Substituents and polar group substituents such as halogen such as 6-methyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6- Ethyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-oct Hydronaphthalene, 6-ethylidene-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-chloro-1,4: 5,8-dimethan
  • the polycarbonate resin any appropriate polycarbonate resin can be used as long as the effects of the present invention can be obtained.
  • the polycarbonate resin includes a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, an alicyclic diol, an alicyclic dimethanol, di, tri, or polyethylene glycol, and an alkylene.
  • the polycarbonate resin is derived from a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, a structural unit derived from an alicyclic dimethanol and / or a di-, tri- or polyethylene glycol. More preferably, a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and a structural unit derived from di, tri, or polyethylene glycol.
  • the polycarbonate resin may contain structural units derived from other dihydroxy compounds as necessary. Details of the polycarbonate resin that can be suitably used in the present invention are described in, for example, Japanese Patent Application Laid-Open Nos. 2014-10291 and 2014-26266, and the description is incorporated herein by reference. The
  • the glass transition temperature of the polycarbonate resin is preferably 110 ° C. or higher and 180 ° C. or lower, more preferably 120 ° C. or higher and 165 ° C. or lower. If the glass transition temperature is excessively low, the heat resistance tends to deteriorate, there is a possibility of causing a dimensional change after film formation, and the image quality of the obtained liquid crystal display device may be lowered. If the glass transition temperature is excessively high, the molding stability at the time of film molding may deteriorate, and the transparency of the film may be impaired.
  • the glass transition temperature is determined according to JIS K 7121 (1987).
  • the molecular weight of the polycarbonate resin can be represented by a reduced viscosity.
  • the reduced viscosity is measured using a Ubbelohde viscometer at a temperature of 20.0 ° C. ⁇ 0.1 ° C., using methylene chloride as a solvent, precisely adjusting the polycarbonate concentration to 0.6 g / dL.
  • the lower limit of the reduced viscosity is usually preferably 0.30 dL / g, more preferably 0.35 dL / g or more.
  • the upper limit of the reduced viscosity is usually preferably 1.20 dL / g, more preferably 1.00 dL / g, still more preferably 0.80 dL / g.
  • the reduced viscosity is less than the lower limit, there may be a problem that the mechanical strength of the molded product is reduced.
  • the reduced viscosity is larger than the upper limit, the fluidity at the time of molding is lowered, and there may be a problem that productivity and moldability are lowered.
  • the retardation film is typically produced by stretching a resin film in at least one direction.
  • any appropriate method can be adopted as a method for forming the resin film.
  • a melt extrusion method for example, a T-die molding method
  • a cast coating method for example, a casting method
  • a calendar molding method for example, a hot press method, a co-extrusion method, a co-melting method, a multilayer extrusion method, an inflation molding method, etc. It is done.
  • a T-die molding method, a casting method, and an inflation molding method are used.
  • the thickness of the resin film can be set to any appropriate value depending on desired optical characteristics, stretching conditions described later, and the like.
  • the thickness is preferably 50 ⁇ m to 300 ⁇ m.
  • Any appropriate stretching method and stretching conditions may be employed for the stretching.
  • various stretching methods such as free end stretching, fixed end stretching, free end contraction, and fixed end contraction can be used singly or simultaneously or sequentially.
  • the stretching direction can also be performed in various directions and dimensions such as a horizontal direction, a vertical direction, a thickness direction, and a diagonal direction.
  • the stretching temperature is preferably Tg-30 ° C. to Tg + 60 ° C., more preferably Tg-10 ° C. to Tg + 50 ° C. with respect to the glass transition temperature (Tg) of the resin film.
  • a retardation film having the desired optical characteristics (for example, refractive index characteristics, in-plane retardation, Nz coefficient) can be obtained by appropriately selecting the stretching method and stretching conditions.
  • the retardation film is produced by continuously stretching a long resin film obliquely in the direction of an angle ⁇ with respect to the longitudinal direction.
  • a long stretched film having an orientation angle of ⁇ with respect to the longitudinal direction of the film (slow axis in the direction of angle ⁇ ) can be obtained.
  • the angle ⁇ is equal to the absorption axis of the second polarizer and the first optical compensation layer. It may be an angle formed with the slow axis.
  • Examples of the stretching machine used for the oblique stretching include a tenter type stretching machine capable of adding feed forces, pulling forces, or pulling forces at different speeds in the lateral and / or longitudinal directions.
  • the tenter type stretching machine includes a horizontal uniaxial stretching machine, a simultaneous biaxial stretching machine, and the like, but any suitable stretching machine can be used as long as a long resin film can be continuously stretched obliquely.
  • the thickness of the retardation film is preferably 20 ⁇ m to 100 ⁇ m, more preferably 20 ⁇ m to 80 ⁇ m, and further preferably 20 ⁇ m to 65 ⁇ m. With such a thickness, the desired in-plane retardation and Nz coefficient can be obtained.
  • Second Optical Compensation Layer Optical characteristics, constituent materials, thicknesses, and the like of the second optical compensation layer are as described in the above section E for the first optical compensation layer.
  • the second optical compensation layer may be the same as or different from the first optical compensation layer.
  • the first optical compensation layer may be a laminate of the first optical compensation layer and a so-called ⁇ / 2 plate.
  • the second optical compensation layer may be a laminate of the second optical compensation layer and a ⁇ / 2 plate.
  • the ⁇ / 2 plate preferably exhibits a relationship in which the refractive index characteristic is nx> ny ⁇ nz.
  • the in-plane retardation Re (550) of the ⁇ / 2 plate is preferably 190 nm to 360 nm, and more preferably 220 nm to 330 nm.
  • the relationship between the slow axis of the ⁇ / 2 plate and the slow axis of the first optical compensation layer or the slow axis of the second optical compensation layer is as follows. It is preferable to adjust the angle formed with the slow axis of the optical compensation layer or the second optical compensation layer to be appropriate. For example, when the slow axis of the ⁇ / 2 plate is positioned clockwise (0 ° to + 180 °) with respect to the absorption axis of the second polarizer, the axis of the slow axis of the first optical compensation layer The angle is preferably + 40 ° to + 50 °, more preferably + 43 ° to + 47 °, and further preferably + 45 ° with respect to the polarization direction after passing through the ⁇ / 2 plate.
  • the slow axis of the first optical compensation layer Is preferably ⁇ 40 ° to ⁇ 50 °, more preferably ⁇ 43 ° to ⁇ 47 °, and still more preferably ⁇ 45 with respect to the polarization direction after passing through the ⁇ / 2 plate. °.
  • + x ° means that x ° is clockwise with respect to the reference direction
  • ⁇ x ° is that x ° is counterclockwise with respect to the reference direction.
  • the ⁇ / 2 plate is typically a stretched film of a resin film, similar to the first optical compensation layer and the second optical compensation layer.
  • transmission part of the cover sheet 40 is an opening part, and the said opening part is filled with the adhesive.
  • the refractive index of the pressure-sensitive adhesive is preferably 1.30 to 1.70, more preferably 1.40 to 1.60, and still more preferably 1.45 to 1.55.
  • the difference between the refractive index of the pressure-sensitive adhesive and the refractive index of the layer adjacent to the pressure-sensitive adhesive is preferably 0.20 or less, more preferably 0 to 0.15.
  • the adhesive may fill only the opening, and is provided between the cover sheet 40 and the second polarizer 60 (or the first optical compensation layer 50 if present).
  • a part of the pressure-sensitive adhesive layer 80 may be used.
  • the thickness of the pressure-sensitive adhesive layer (thickness other than the portion corresponding to the opening of the cover sheet) can be appropriately set according to the purpose, adhesive force, and the like.
  • the thickness of the pressure-sensitive adhesive layer is preferably 1 ⁇ m to 500 ⁇ m, more preferably 1 ⁇ m to 200 ⁇ m, and still more preferably 1 ⁇ m to 100 ⁇ m.
  • the pressure-sensitive adhesive layer can be composed of any appropriate pressure-sensitive adhesive having the above characteristics.
  • pressure sensitive adhesives based on acrylic polymers, silicone polymers, polyesters, polyurethanes, polyamides, polyethers, fluorine polymers, rubber polymers, and the like.
  • it is an adhesive (acrylic adhesive) having an acrylic polymer as a base polymer. It is because it is excellent in excellent optical transparency, moderate pressure-sensitive adhesive properties (wetting properties, cohesiveness and adhesiveness), and excellent weather resistance and heat resistance.
  • the present invention will be specifically described by way of examples, but the present invention is not limited to these examples.
  • the measuring method of each characteristic is as follows.
  • step difference About the liquid crystal display device obtained by the Example and the comparative example, the presence or absence of the unevenness
  • Visual step The step was visually confirmed in a state where an image was actually displayed on the liquid crystal display devices obtained in Examples and Comparative Examples. Evaluation was made according to the following criteria.
  • C The level difference in which the visual recognition of the image is uncomfortable.
  • D The level difference is clearly recognized so as to greatly affect the visual recognition of the image.
  • Example 1 (I) Polarizing plate Two commercially available polarizing plates (manufactured by Nitto Denko Corporation, product name “CWQ1463VCUHC”) were prepared and used as a first polarizing plate (polarizer) and a second polarizing plate (polarizer).
  • Example 2 Example 1 except that a first optical compensation layer is further provided between the second polarizer and the cover sheet, and a second optical compensation layer is further provided between the cover sheet and the liquid crystal cell.
  • a liquid crystal display device was produced. Specifically, two retardation films prepared as described below were used as the first optical compensation layer and the second optical compensation layer.
  • the angle formed by the slow axis of the first optical compensation layer and the absorption axis of the second polarizer is 45 °, and the slow axis of the first optical compensation layer and the second axis
  • the optical compensation layer was bonded so that the slow axis thereof was substantially orthogonal.
  • the obtained liquid crystal display device was subjected to the same evaluation as in Example 1. The results are shown in Table 1.
  • a retardation film was obtained by a method according to Example 1 of JP-A-2014-26266.
  • Re (550) of the obtained retardation film was 147 nm, the Nz coefficient was 1.0, Re (450) / Re (550) was 0.89, and the thickness was 40 ⁇ m.
  • Example 3 A liquid crystal display device was produced in the same manner as in Example 1 except that the opening of the cover sheet was filled with the adhesive. The obtained liquid crystal display device was subjected to the same evaluation as in Example 1. The results are shown in Table 1.
  • Example 4 A liquid crystal display device was produced in the same manner as in Example 2 except that the opening of the cover sheet was filled with the adhesive. The obtained liquid crystal display device was subjected to the same evaluation as in Example 1. The results are shown in Table 1.
  • Example 1 A liquid crystal display device was produced in the same manner as in Example 1 except that the second polarizer was disposed between the cover sheet and the liquid crystal cell, that is, the cover sheet was the outermost layer. The obtained liquid crystal display device was subjected to the same evaluation as in Example 1. The results are shown in Table 1.
  • Comparative Example 2 Liquid crystal as in Comparative Example 1, except that a commercially available neutral density filter (product name “Neutral Density Filter ND-0.5”, transmittance 36%, manufactured by FUJIFILM Corporation) was further provided on the viewing side of the cover sheet. A display device was produced. The obtained liquid crystal display device was subjected to the same evaluation as in Example 1. The results are shown in Table 1.
  • a commercially available neutral density filter product name “Neutral Density Filter ND-0.5”, transmittance 36%, manufactured by FUJIFILM Corporation
  • Example 3 A liquid crystal display device was produced in the same manner as in Comparative Example 1 except that a third polarizer was further provided on the viewing side of the cover sheet. Note that the same polarizer as the first polarizer (polarizer) and the second polarizer (polarizer) was used as the third polarizer (polarizer). Further, the third polarizer was bonded so that the absorption axis thereof was substantially parallel to the absorption axis of the second polarizer. The obtained liquid crystal display device was subjected to the same evaluation as in Example 1. The results are shown in Table 1.
  • the liquid crystal display device of the example of the present invention was excellent in the balance between the visual step and the brightness of the display screen, while eliminating the physical step.
  • the liquid crystal display device of Comparative Example 1 in which the cover sheet is the outermost layer on the viewing side, although the display screen is bright, the physical level difference is not eliminated, and the visual level difference is poor enough to affect the visibility. .
  • the liquid crystal display device of Comparative Example 2 using the neutral density filter although the physical level difference is eliminated, both the brightness of the display screen and the visual level difference are poor, and the brightness of the display screen is particularly poor. there were.
  • the liquid crystal display device of Comparative Example 3 in which a polarizer was further provided between the cover sheet and the liquid crystal cell the brightness of the display screen was poor. Further, as is apparent from a comparison between Example 1 and Example 3 and Example 2 and Example 4, it can be seen that the brightness can be further improved by filling the opening with an adhesive.
  • the liquid crystal display device of the present invention includes portable information terminals (PDAs), mobile phones, watches, digital cameras, portable game devices such as portable game machines, OA devices such as personal computer monitors, notebook computers, copy machines, video cameras, liquid crystal televisions, Home appliances such as microwave ovens and AV equipment, back monitors, monitors for car navigation systems, in-vehicle devices such as car audio, display equipment such as information monitors for commercial stores, security equipment such as monitoring monitors, nursing care It can be used for various applications such as nursing care and medical equipment such as monitors and medical monitors.
  • the liquid crystal display device of the present invention can be suitably used in a form embedded in a structure.

Abstract

A liquid crystal display device is provided which has a step between a display screen and the topmost surface, in which said step is not readily apparent, and which can achieve a bright display. This liquid crystal display device is provided with: a liquid crystal cell; a first polarizer arranged on the back side of said liquid crystal cell; a cover sheet arranged on the visible side of said liquid crystal cell and having a transmissive portion in a position corresponding to the display region of said liquid crystal cell; and a second polarizer arranged on the visible side of said cover sheet so as to cover the transmissive portion. The absorption axis of the first polarizer and the absorption axis of the second polarizer are substantially perpendicular to each other.

Description

液晶表示装置Liquid crystal display
 本発明は、液晶表示装置に関する。 The present invention relates to a liquid crystal display device.
 液晶表示装置は、テレビ、スマートフォン、パソコンモニター、デジタルカメラをはじめとした幅広い用途に使用されており、その用途はさらに広がりを見せている。その結果、液晶表示装置の用途によっては、液晶表示装置が各種構造物に埋め込まれた形態が採用されている。そのような用途の具体例としては、鉄道車両における運行情報画面(例えば、客車両の次駅案内表示)、自動車のインストルメントパネルやコンソールに配設された各種計器やナビゲーションシステム等の表示部、飛行機のコックピットの各種計器、ならびに、病院、警備室または戦闘指揮所等に配設されるモニターが挙げられる。このような形態においては、液晶表示装置の保護および/またはデザイン上の要請から、液晶表示装置の表示領域に対応した透過部を有するカバーシートが、必要に応じて液晶表示装置の視認側に配置され得る。このような形態においては、液晶表示装置を埋め込んだ部分の最表面(例えば、筐体、壁、モニターデスク、あるいは必要に応じて配置されたカバーシートの最表面)と表示画面との間に段差が生じており、用途および/または状況によっては当該段差が視認性に影響を与える場合がある。当該段差を認識しにくくするために、視認側に減光フィルタを配置する技術が提案されている(特許文献1)。しかし、この技術では、段差は認識しにくくなるものの、表示画面自体が暗くなってしまうという問題がある。 Liquid crystal display devices are used in a wide range of applications, including televisions, smartphones, personal computer monitors, and digital cameras, and their applications are expanding. As a result, depending on the application of the liquid crystal display device, a configuration in which the liquid crystal display device is embedded in various structures is employed. Specific examples of such applications include operation information screens in railway vehicles (for example, next station guidance display for passenger vehicles), display units such as various instruments and navigation systems arranged on the instrument panel and console of automobiles, There are various instruments in airplane cockpits and monitors installed in hospitals, guard rooms or battle command centers. In such a form, a cover sheet having a transmissive portion corresponding to the display area of the liquid crystal display device is disposed on the viewing side of the liquid crystal display device as necessary in order to protect and / or design the liquid crystal display device. Can be done. In such a form, there is a step between the display screen and the outermost surface of the portion in which the liquid crystal display device is embedded (for example, the outermost surface of a housing, a wall, a monitor desk, or a cover sheet arranged as necessary). The level difference may affect the visibility depending on the application and / or situation. In order to make it difficult to recognize the level difference, a technique of arranging a neutral density filter on the viewing side has been proposed (Patent Document 1). However, this technique has a problem that the display screen itself becomes dark although the step is difficult to recognize.
特許第5877433号明細書Japanese Patent No. 5877433
 本発明は上記従来の課題を解決するためになされたものであり、その目的とするところは、表示画面と最表面との間に段差を有し、当該段差が認識されにくく、かつ、明るい表示を実現し得る液晶表示装置を提供することにある。 The present invention has been made to solve the above-described conventional problems, and the object of the present invention is to have a step between the display screen and the outermost surface, and the step is difficult to recognize and has a bright display. An object of the present invention is to provide a liquid crystal display device capable of realizing the above.
 本発明の液晶表示装置は、液晶セルと;該液晶セルの背面側に配置された第1の偏光子と;該液晶セルの視認側に配置された、該液晶セルの表示領域に対応した位置に透過部を有するカバーシートと;該カバーシートの視認側に該透過部を覆うように配置された第2の偏光子と、を備える。該第1の偏光子の吸収軸方向と該第2の偏光子の吸収軸方向とは実質的に直交している。
 1つの実施形態においては、上記液晶表示装置は、上記カバーシートと上記第2の偏光子との間に、Re(550)が100nm~180nmである第1の光学補償層をさらに備え、かつ、該カバーシートと上記液晶セルとの間に、Re(550)が100nm~180nmである第2の光学補償層をさらに備える。
 1つの実施形態においては、上記第1の光学補償層の遅相軸方向と上記第2の偏光子の吸収軸とのなす角度は35°~55°または125°~145°であり、かつ、該第1の光学補償層の遅相軸方向と上記第2の光学補償層の遅相軸方向とが実質的に直交している。
 1つの実施形態においては、上記第1の光学補償層および上記第2の光学補償層は、Re(450)<Re(550)の関係を満たす。
 1つの実施形態においては、上記カバーシートの上記透過部は開口部であり、該開口部は粘着剤で充填されている。
 1つの実施形態においては、上記粘着剤の屈折率は1.30~1.70である。
The liquid crystal display device of the present invention includes a liquid crystal cell; a first polarizer disposed on the back side of the liquid crystal cell; and a position corresponding to the display area of the liquid crystal cell disposed on the viewing side of the liquid crystal cell. A cover sheet having a transmissive part; and a second polarizer disposed on the viewing side of the cover sheet so as to cover the transmissive part. The absorption axis direction of the first polarizer and the absorption axis direction of the second polarizer are substantially perpendicular to each other.
In one embodiment, the liquid crystal display device further includes a first optical compensation layer having Re (550) of 100 nm to 180 nm between the cover sheet and the second polarizer, and A second optical compensation layer having Re (550) of 100 nm to 180 nm is further provided between the cover sheet and the liquid crystal cell.
In one embodiment, the angle formed by the slow axis direction of the first optical compensation layer and the absorption axis of the second polarizer is 35 ° to 55 ° or 125 ° to 145 °, and The slow axis direction of the first optical compensation layer and the slow axis direction of the second optical compensation layer are substantially perpendicular to each other.
In one embodiment, the first optical compensation layer and the second optical compensation layer satisfy a relationship of Re (450) <Re (550).
In one embodiment, the transmission part of the cover sheet is an opening, and the opening is filled with an adhesive.
In one embodiment, the adhesive has a refractive index of 1.30 to 1.70.
 本発明によれば、表示画面と最表面との間に段差を有する液晶表示装置において、視認側の偏光子を段差よりも視認側に配置することにより、表示画面の明るさを維持しつつ、段差を認識しにくくして視認性を改善することができる。1つの実施形態においては、いわゆるλ/4板を段差の両側にさらに配置することにより、段差の認識しにくさをさらに顕著に改善することができる。 According to the present invention, in the liquid crystal display device having a step between the display screen and the outermost surface, the polarizer on the viewing side is arranged on the viewing side from the step, thereby maintaining the brightness of the display screen, Visibility can be improved by making it difficult to recognize the step. In one embodiment, the difficulty of recognizing a step can be further remarkably improved by further arranging so-called λ / 4 plates on both sides of the step.
本発明の1つの実施形態による液晶表示装置の概略断面図である。1 is a schematic cross-sectional view of a liquid crystal display device according to an embodiment of the present invention. 本発明の別の実施形態による液晶表示装置の概略断面図である。It is a schematic sectional drawing of the liquid crystal display device by another embodiment of this invention. 本発明のさらに別の実施形態による液晶表示装置の概略断面図である。It is a schematic sectional drawing of the liquid crystal display device by another embodiment of this invention. 本発明のさらに別の実施形態による液晶表示装置の概略断面図である。It is a schematic sectional drawing of the liquid crystal display device by another embodiment of this invention. 本発明のさらに別の実施形態による液晶表示装置の概略断面図である。It is a schematic sectional drawing of the liquid crystal display device by another embodiment of this invention. 本発明のさらに別の実施形態による液晶表示装置の概略断面図である。It is a schematic sectional drawing of the liquid crystal display device by another embodiment of this invention. 本発明のさらに別の実施形態による液晶表示装置の概略断面図である。It is a schematic sectional drawing of the liquid crystal display device by another embodiment of this invention. 本発明のさらに別の実施形態による液晶表示装置の概略断面図である。It is a schematic sectional drawing of the liquid crystal display device by another embodiment of this invention. 本発明のさらに別の実施形態による液晶表示装置の概略断面図である。It is a schematic sectional drawing of the liquid crystal display device by another embodiment of this invention. 本発明のさらに別の実施形態による液晶表示装置の概略断面図である。It is a schematic sectional drawing of the liquid crystal display device by another embodiment of this invention.
 以下、図面を参照して本発明の実施形態について説明するが、本発明はこれらの実施形態には限定されない。 Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments.
(用語および記号の定義)
 本明細書における用語および記号の定義は下記の通りである。
(1)屈折率(nx、ny、nz)
 「nx」は面内の屈折率が最大になる方向(すなわち、遅相軸方向)の屈折率であり、「ny」は面内で遅相軸と直交する方向(すなわち、進相軸方向)の屈折率であり、「nz」は厚み方向の屈折率である。
(2)面内位相差(Re)
 「Re(λ)」は、23℃における波長λnmの光で測定した面内位相差である。Re(λ)は、層(フィルム)の厚みをd(nm)としたとき、式:Re=(nx-ny)×dによって求められる。例えば、「Re(550)」は、23℃における波長550nmの光で測定した面内位相差である。
(3)厚み方向の位相差(Rth)
 「Rth(λ)」は、23℃における波長λnmの光で測定した厚み方向の位相差である。Rth(λ)は、層(フィルム)の厚みをd(nm)としたとき、式:Rth=(nx-nz)×dによって求められる。例えば、「Rth(550)」は、23℃における波長550nmの光で測定した厚み方向の位相差である。
(4)Nz係数
 Nz係数は、Nz=Rth/Reによって求められる。
(5)実質的に直交または平行
 「実質的に直交」および「略直交」という表現は、2つの方向のなす角度が90°±10°である場合を包含し、好ましくは90°±7°であり、さらに好ましくは90°±5°である。「実質的に平行」および「略平行」という表現は、2つの方向のなす角度が0°±10°である場合を包含し、好ましくは0°±7°であり、さらに好ましくは0°±5°である。さらに、本明細書において単に「直交」または「平行」というときは、実質的に直交または実質的に平行な状態を含み得るものとする。
(Definition of terms and symbols)
The definitions of terms and symbols in this specification are as follows.
(1) Refractive index (nx, ny, nz)
“Nx” is the refractive index in the direction in which the in-plane refractive index is maximum (ie, the slow axis direction), and “ny” is the direction orthogonal to the slow axis in the plane (ie, the fast axis direction). “Nz” is the refractive index in the thickness direction.
(2) In-plane retardation (Re)
“Re (λ)” is an in-plane retardation measured with light having a wavelength of λ nm at 23 ° C. Re (λ) is determined by the formula: Re = (nx−ny) × d, where d (nm) is the thickness of the layer (film). For example, “Re (550)” is an in-plane retardation measured with light having a wavelength of 550 nm at 23 ° C.
(3) Thickness direction retardation (Rth)
“Rth (λ)” is a retardation in the thickness direction measured with light having a wavelength of λ nm at 23 ° C. Rth (λ) is determined by the formula: Rth = (nx−nz) × d, where d (nm) is the thickness of the layer (film). For example, “Rth (550)” is a retardation in the thickness direction measured with light having a wavelength of 550 nm at 23 ° C.
(4) Nz coefficient The Nz coefficient is obtained by Nz = Rth / Re.
(5) Substantially orthogonal or parallel The expressions “substantially orthogonal” and “substantially orthogonal” include the case where the angle between the two directions is 90 ° ± 10 °, preferably 90 ° ± 7 °. And more preferably 90 ° ± 5 °. The expressions “substantially parallel” and “substantially parallel” include the case where the angle between two directions is 0 ° ± 10 °, preferably 0 ° ± 7 °, more preferably 0 ° ± 5 °. Further, in the present specification, the term “orthogonal” or “parallel” may include a substantially orthogonal state or a substantially parallel state.
A.液晶表示装置の全体構成
 図1は、本発明の1つの実施形態による液晶表示装置の概略断面図である。液晶表示装置100は、液晶セル10と、液晶セル10の背面側に配置された第1の偏光子20と、液晶セル10の視認側に配置されたカバーシート40と、カバーシート40の視認側に配置された第2の偏光子60と、を備える。カバーシート40は、液晶セル10の表示領域に対応した位置に透過部42を有する。透過部は、物理的透過部(例えば、開口部)および光学的透過部(例えば、透明部)を包含する。図示例では開口部が示されている。第2の偏光子60は、カバーシート40の透過部42を覆うように配置されている。本発明の実施形態によれば、カバーシートの透過部を覆うようにして第2の偏光子を最表面側に配置することにより、装置最表面と表示画面との間の段差を認識しにくくし、結果として、液晶表示装置の視認性を改善することができる。より詳細には、偏光子に特有の透過率に起因して段差を認識しにくくすることができ、かつ、偏光子は所定方向の偏光光を効率よく透過し得るので、光を全体的に減少させる減光フィルタに比べて表示画面の明るさを維持することができる。さらに、カバーシートの透過部が開口部である場合には、当該開口部を覆うことにより最表面を平坦とすることにより段差を認識しにくくすることができる。以下、「段差を認識しにくくする」ことを、「視覚的段差を減少させる」と称する場合がある。
A. 1 is a schematic sectional view of a liquid crystal display device according to an embodiment of the present invention. The liquid crystal display device 100 includes a liquid crystal cell 10, a first polarizer 20 disposed on the back side of the liquid crystal cell 10, a cover sheet 40 disposed on the viewing side of the liquid crystal cell 10, and the viewing side of the cover sheet 40. And a second polarizer 60 disposed on the surface. The cover sheet 40 has a transmission part 42 at a position corresponding to the display area of the liquid crystal cell 10. The transmission part includes a physical transmission part (for example, an opening) and an optical transmission part (for example, a transparent part). In the illustrated example, an opening is shown. The second polarizer 60 is disposed so as to cover the transmission part 42 of the cover sheet 40. According to the embodiment of the present invention, the second polarizer is disposed on the outermost surface side so as to cover the transmission part of the cover sheet, thereby making it difficult to recognize the step between the outermost surface of the apparatus and the display screen. As a result, the visibility of the liquid crystal display device can be improved. More specifically, the step can be made difficult to recognize due to the transmittance specific to the polarizer, and the polarizer can efficiently transmit polarized light in a predetermined direction, so that the light is reduced overall. The brightness of the display screen can be maintained as compared with the neutral density filter. Furthermore, when the transmission part of a cover sheet is an opening part, it can make it difficult to recognize a level | step difference by making the outermost surface flat by covering the said opening part. Hereinafter, “to make it difficult to recognize a level difference” may be referred to as “to reduce a visual level difference”.
 本発明の実施形態による液晶表示装置においては、第1の偏光子20の吸収軸方向と第2の偏光子60の吸収軸方向とは、実質的に直交または平行であり、代表的には実質的に直交している。 In the liquid crystal display device according to the embodiment of the present invention, the absorption axis direction of the first polarizer 20 and the absorption axis direction of the second polarizer 60 are substantially orthogonal or parallel, typically substantially. Are orthogonal.
 本発明の実施形態による液晶表示装置は、いわゆるOモードであってもよく、いわゆるEモードであってもよい。「Oモードの液晶表示装置」とは、液晶セルの光源側に配置された偏光子の吸収軸方向と、液晶セルの初期配向方向とが実質的に平行であるものをいう。「Eモードの液晶表示装置」とは、液晶セルの光源側に配置された偏光子の吸収軸方向と、液晶セルの初期配向方向とが実質的に直交するものをいう。「液晶セルの初期配向方向」とは、電界が存在しない状態で、液晶層に含まれる液晶分子が配向した結果生じる液晶層の面内屈折率が最大となる方向(すなわち、遅相軸方向)をいう。 The liquid crystal display device according to the embodiment of the present invention may be in a so-called O mode or in a so-called E mode. The “O-mode liquid crystal display device” refers to a device in which the absorption axis direction of a polarizer disposed on the light source side of the liquid crystal cell and the initial alignment direction of the liquid crystal cell are substantially parallel. The “E mode liquid crystal display device” refers to a device in which the absorption axis direction of a polarizer disposed on the light source side of the liquid crystal cell and the initial alignment direction of the liquid crystal cell are substantially orthogonal to each other. “Initial alignment direction of liquid crystal cell” refers to the direction in which the in-plane refractive index of the liquid crystal layer that is the result of alignment of liquid crystal molecules contained in the liquid crystal layer is maximized in the absence of an electric field (ie, the slow axis direction) Say.
 図2は、本発明の別の実施形態による液晶表示装置の概略断面図である。液晶表示装置101は、カバーシート40と第2の偏光子60との間に第1の光学補償層50をさらに備え、かつ、カバーシート40と液晶セル10との間に第2の光学補償層70をさらに備える。第1の光学補償層50および第2の光学補償層70は、それぞれ、Re(550)が代表的には100nm~180nmであり、好ましくは110nm~170nmであり、より好ましくは120nm~160nmである。第1の光学補償層50の遅相軸方向と第2の偏光子60の吸収軸方向とのなす角度は代表的には35°~55°であり、好ましくは38°~52°であり、より好ましくは42°~48°であり、さらに好ましくは約45°である。あるいは、当該角度は代表的には125°~145°であり、好ましくは128°~142°であり、より好ましくは132°~138°であり、さらに好ましくは約135°である。角度がこのような範囲であれば、第1の光学補償層と第2の偏光子との組み合わせにより、優れた円偏光機能および反射防止機能を実現することができる。その結果、実用上許容可能な表示画面の明るさを維持しつつ、視覚的段差を顕著に減少させることができる。すなわち、例えば減光フィルタを用いて透過率を低下させることにより視覚的段差を減少させる場合に比べて、透過率を低下させることなく視覚的段差を減少させることができる。第1の光学補償層が設けられる場合、第1の光学補償層および第2の偏光子は、それぞれ別個の部材として液晶表示装置に導入されてもよく、第1の光学補償層と第2の偏光子との積層体(すなわち、円偏光板)として液晶表示装置に導入されてもよい。第1の光学補償層50の遅相軸方向と第2の光学補償層70の遅相軸方向とは、好ましくは、実質的に直交している。例えば、第2の偏光子60の吸収軸方向が0°であり、第1の偏光子20の吸収軸方向が90°であり、第1の光学補償層50の遅相軸方向が45°である場合には、第2の光学補償層70の遅相軸方向は-45°に設定され得る。第1の光学補償層と第2の光学補償層とを組み合わせて設けることにより、液晶表示装置の黒表示が可能となる。 FIG. 2 is a schematic cross-sectional view of a liquid crystal display device according to another embodiment of the present invention. The liquid crystal display device 101 further includes a first optical compensation layer 50 between the cover sheet 40 and the second polarizer 60, and a second optical compensation layer between the cover sheet 40 and the liquid crystal cell 10. 70 is further provided. In the first optical compensation layer 50 and the second optical compensation layer 70, Re (550) is typically 100 nm to 180 nm, preferably 110 nm to 170 nm, more preferably 120 nm to 160 nm. . The angle formed between the slow axis direction of the first optical compensation layer 50 and the absorption axis direction of the second polarizer 60 is typically 35 ° to 55 °, preferably 38 ° to 52 °. More preferably, it is 42 ° to 48 °, and more preferably about 45 °. Alternatively, the angle is typically 125 ° to 145 °, preferably 128 ° to 142 °, more preferably 132 ° to 138 °, and even more preferably about 135 °. If the angle is in such a range, an excellent circular polarization function and antireflection function can be realized by a combination of the first optical compensation layer and the second polarizer. As a result, it is possible to remarkably reduce the visual step while maintaining the brightness of the display screen that is practically acceptable. That is, for example, the visual step can be reduced without reducing the transmittance as compared with the case where the visual step is reduced by reducing the transmittance using a neutral density filter. When the first optical compensation layer is provided, the first optical compensation layer and the second polarizer may be introduced into the liquid crystal display device as separate members, and the first optical compensation layer and the second optical compensation layer may be introduced. You may introduce | transduce into a liquid crystal display device as a laminated body (namely, circularly-polarizing plate) with a polarizer. The slow axis direction of the first optical compensation layer 50 and the slow axis direction of the second optical compensation layer 70 are preferably substantially orthogonal. For example, the absorption axis direction of the second polarizer 60 is 0 °, the absorption axis direction of the first polarizer 20 is 90 °, and the slow axis direction of the first optical compensation layer 50 is 45 °. In some cases, the slow axis direction of the second optical compensation layer 70 may be set to −45 °. By providing the first optical compensation layer and the second optical compensation layer in combination, the liquid crystal display device can display black.
 図2の実施形態においては、第1の光学補償層および第2の光学補償層の構成材料、光学特性および厚み等は、同一であってもよく、異なっていてもよい。1つの実施形態においては、第1の光学補償層および第2の光学補償層はそれぞれ、Re(450)<Re(550)の関係を満たす。光学補償層がこのような関係を満たすことにより、優れた反射防止機能が実現され、その結果、視覚的段差を減少させることができる。 In the embodiment of FIG. 2, the constituent materials, optical characteristics, thickness, and the like of the first optical compensation layer and the second optical compensation layer may be the same or different. In one embodiment, the first optical compensation layer and the second optical compensation layer each satisfy a relationship of Re (450) <Re (550). When the optical compensation layer satisfies such a relationship, an excellent antireflection function is realized, and as a result, the visual step can be reduced.
 図3は、本発明のさらに別の実施形態による液晶表示装置の概略断面図である。液晶表示装置102は、粘着剤がカバーシート40の開口部を充填している。粘着剤は、開口部のみを充填してもよく、カバーシート40と第2の偏光子60との間に設けられた粘着剤層80の一部であってもよい。このような構成であれば、開口部により形成される空気層が排除されるので、層界面における反射および/または屈折が抑制され得る。結果として、表示画面の明るさをさらに改善し、視覚的段差をさらに顕著に減少させることができる。なお、カバーシートが光学的透過部(透明部)を有する場合には、当該透明部が粘着剤で構成され得る。粘着剤の屈折率は、好ましくは1.30~1.70であり、より好ましくは1.40~1.60であり、さらに好ましくは1.45~1.55である。粘着剤の屈折率をこのような範囲とすることにより、層界面における反射および/または屈折をさらに抑制することができ、表示画面の明るさと視覚的段差とのバランスがさらに優れたものとなり得る。 FIG. 3 is a schematic cross-sectional view of a liquid crystal display device according to still another embodiment of the present invention. In the liquid crystal display device 102, the adhesive fills the opening of the cover sheet 40. The pressure-sensitive adhesive may fill only the opening, or may be a part of the pressure-sensitive adhesive layer 80 provided between the cover sheet 40 and the second polarizer 60. With such a configuration, the air layer formed by the openings is eliminated, and reflection and / or refraction at the layer interface can be suppressed. As a result, the brightness of the display screen can be further improved and the visual level difference can be further significantly reduced. In addition, when a cover sheet has an optical transmission part (transparent part), the said transparent part may be comprised with an adhesive. The refractive index of the pressure-sensitive adhesive is preferably 1.30 to 1.70, more preferably 1.40 to 1.60, and still more preferably 1.45 to 1.55. By setting the refractive index of the pressure-sensitive adhesive within such a range, reflection and / or refraction at the layer interface can be further suppressed, and the balance between the brightness of the display screen and the visual step can be further improved.
 図5は、本発明のさらに別の実施形態による液晶表示装置の概略断面図である。液晶表示装置104は、カバーシート40が湾曲しており、第2の偏光子60がカバーシート40に沿って湾曲している。カバーシート40は、任意の適切な形態で湾曲していてもよい。具体的には、視認側が凸となるように湾曲していてもよいし、視認側が凹となるように湾曲していてもよい。また、カバーシート40の面内のいずれの方向を軸として湾曲していてもよい。さらに、図6に示す液晶表示装置105のように、液晶セル10および第1の偏光子20がカバーシート40に沿って湾曲していてもよい。カバーシートが湾曲している本実施形態の液晶表示装置104および105は、デザインの選択幅が広く、商業的な価値が大きい。 FIG. 5 is a schematic sectional view of a liquid crystal display device according to still another embodiment of the present invention. In the liquid crystal display device 104, the cover sheet 40 is curved, and the second polarizer 60 is curved along the cover sheet 40. The cover sheet 40 may be curved in any suitable form. Specifically, the viewing side may be curved so as to be convex, or the viewing side may be curved so as to be concave. Further, any direction in the plane of the cover sheet 40 may be curved as an axis. Furthermore, the liquid crystal cell 10 and the first polarizer 20 may be curved along the cover sheet 40 as in the liquid crystal display device 105 shown in FIG. The liquid crystal display devices 104 and 105 of the present embodiment in which the cover sheet is curved have a wide range of design choices and great commercial value.
 図7は、本発明のさらに別の実施形態による液晶表示装置の概略断面図である。液晶表示装置106は、粘着剤がカバーシート40の開口部を充填している。粘着剤は、開口部のみを充填してもよく、カバーシート40と第2の偏光子60との間に設けられた粘着剤層80の一部であってもよい。さらに、液晶表示装置106は、カバーシート40が湾曲しており、粘着剤は、カバーシート40が湾曲していることによって生じるカバーシート40と液晶セル10との間の隙間を充填している。このような構成であれば、カバーシート40が湾曲していることによる機械的強度の低下を抑制し得る。 FIG. 7 is a schematic cross-sectional view of a liquid crystal display device according to still another embodiment of the present invention. In the liquid crystal display device 106, the adhesive fills the opening of the cover sheet 40. The pressure-sensitive adhesive may fill only the opening, or may be a part of the pressure-sensitive adhesive layer 80 provided between the cover sheet 40 and the second polarizer 60. Further, in the liquid crystal display device 106, the cover sheet 40 is curved, and the pressure-sensitive adhesive fills a gap between the cover sheet 40 and the liquid crystal cell 10 that is generated when the cover sheet 40 is curved. If it is such a structure, the fall of the mechanical strength by the cover sheet 40 curving can be suppressed.
 図8は、本発明のさらに別の実施形態による液晶表示装置の概略断面図である。液晶表示装置107は、液晶セル10Aと、液晶セル10Aの背面側に配置された第1の偏光子20Aと、液晶セル10Bと、液晶セル10Bの背面側に配置された第1の偏光子20Bと、液晶セル10Aおよび液晶セル10Bの視認側に配置されたカバーシート40と、カバーシート40の視認側に配置された第2の偏光子60と、を備える。液晶表示装置107のカバーシート40は、液晶セル10Aの表示領域に対応した位置に第1の透過部42Aを備え、液晶セル10Bの表示領域に対応した位置に第2の透過部42Bを備える。液晶表示装置107は、各液晶セルに対応する2つの表示画面を有し、カバーシートの2つの透過部を覆うようにして第2の偏光子を最表面側に配置することにより、装置最表面と2つの表示画面との間の段差を認識しにくくし、2つの表示画面における視認性を改善することができる。なお、2つの表示画面および対応する2つの液晶セルを有する液晶表示装置を例に挙げて説明したが、本発明の液晶表示装置は、3つ以上の表示画面および対応する液晶セルを有していてもよい。 FIG. 8 is a schematic cross-sectional view of a liquid crystal display device according to still another embodiment of the present invention. The liquid crystal display device 107 includes a liquid crystal cell 10A, a first polarizer 20A disposed on the back side of the liquid crystal cell 10A, a liquid crystal cell 10B, and a first polarizer 20B disposed on the back side of the liquid crystal cell 10B. And a cover sheet 40 disposed on the viewing side of the liquid crystal cell 10A and the liquid crystal cell 10B, and a second polarizer 60 disposed on the viewing side of the cover sheet 40. The cover sheet 40 of the liquid crystal display device 107 includes a first transmission part 42A at a position corresponding to the display area of the liquid crystal cell 10A, and a second transmission part 42B at a position corresponding to the display area of the liquid crystal cell 10B. The liquid crystal display device 107 has two display screens corresponding to each liquid crystal cell, and arranges the second polarizer on the outermost surface side so as to cover the two transmission portions of the cover sheet, thereby providing the outermost surface of the device. It is difficult to recognize the step between the two display screens and the visibility on the two display screens can be improved. Although the liquid crystal display device having two display screens and corresponding two liquid crystal cells has been described as an example, the liquid crystal display device of the present invention has three or more display screens and corresponding liquid crystal cells. May be.
 図9は、本発明のさらに別の実施形態による液晶表示装置の概略断面図である。本実施形態の液晶表示装置108は、液晶表示装置107と同様に2つの表示画面を有する。さらに、本実施形態では、カバーシート40が、透過部42Aと透過部42Bとの間の屈曲部90で屈曲しており、第2の偏光子60がカバーシート40に沿って屈曲している。これにより、液晶表示装置108は、2つの表示画面を用いて異なる方向に向けて画像を表示することができる。なお、本発明の液晶表示装置は、カバーシートが複数の屈曲部を有し、各屈曲部を挟んで3つ以上の表示画面および対応する液晶セルを有していてもよい。 FIG. 9 is a schematic cross-sectional view of a liquid crystal display device according to still another embodiment of the present invention. The liquid crystal display device 108 of the present embodiment has two display screens as with the liquid crystal display device 107. Furthermore, in the present embodiment, the cover sheet 40 is bent at a bent portion 90 between the transmissive portion 42A and the transmissive portion 42B, and the second polarizer 60 is bent along the cover sheet 40. Accordingly, the liquid crystal display device 108 can display images in different directions using the two display screens. In the liquid crystal display device of the present invention, the cover sheet may have a plurality of bent portions, and may have three or more display screens and corresponding liquid crystal cells sandwiching each bent portion.
 本発明の実施形態による液晶表示装置は、例えば、各種構造物に組み込まれて(代表的には、埋め込まれて)用いられ得る。構造物の具体例としては、建築構造物(例えば、警備室や戦闘指揮所の壁)、鉄道車両(例えば、ドア上部の壁)、自動車(例えば、インストルメントパネル、コンソール)、飛行機(例えば、コックピット)、家電およびAV機器が挙げられる。 The liquid crystal display device according to the embodiment of the present invention can be used by being incorporated (typically embedded) in various structures, for example. Specific examples of structures include building structures (e.g., guard room and battle command center walls), railroad vehicles (e.g., walls above doors), automobiles (e.g., instrument panels, consoles), airplanes (e.g., Cockpit), home appliances and AV equipment.
 本発明の実施形態による液晶表示装置は、実用的には、バックライトユニット(図示せず)をさらに備える。バックライトユニットは、代表的には光源と導光板とを含む。バックライトユニットは、任意の適切なその他の部材(例えば、拡散シート、プリズムシート)をさらに備え得る。 The liquid crystal display device according to the embodiment of the present invention further includes a backlight unit (not shown) practically. The backlight unit typically includes a light source and a light guide plate. The backlight unit may further include any appropriate other member (for example, a diffusion sheet, a prism sheet).
 本発明の実施形態による液晶表示装置は、任意の適切なその他の部材をさらに備えていてもよい。例えば、別の光学補償層(位相差フィルム)がさらに配置されていてもよい。別の光学補償層の光学特性、数、組み合わせ、配置位置等は、目的および所望の光学特性等に応じて適切に選択され得る。また例えば、最表面に各種の表面処理層が配置されてもよい。表面処理層の具体例としては、アンチグレア層、反射防止層、ハードコート層が挙げられる。複数の表面処理層が配置されてもよい。表面処理層の種類、数、組み合わせ等は、目的に応じて適切に選択され得る。 The liquid crystal display device according to the embodiment of the present invention may further include any appropriate other member. For example, another optical compensation layer (retardation film) may be further disposed. The optical characteristics, number, combination, arrangement position, and the like of another optical compensation layer can be appropriately selected depending on the purpose and desired optical characteristics. For example, various surface treatment layers may be disposed on the outermost surface. Specific examples of the surface treatment layer include an antiglare layer, an antireflection layer, and a hard coat layer. A plurality of surface treatment layers may be disposed. The type, number, combination, and the like of the surface treatment layer can be appropriately selected depending on the purpose.
 上記の実施形態は適宜組み合わせてもよく、上記の実施形態における構成を光学的に等価な構成で置き換えてもよい。例えば、図4のように、図2の実施形態と図3の実施形態とを組み合わせてもよい。具体的には、図4の液晶表示装置103は、第1の光学補償層50および第2の光学補償層70とカバーシートの開口部を充填する粘着剤とを組み合わせて備える。また例えば、図示例のカバーシートの開口部を透明部で置き換えてもよい。また例えば、図10のように、図6の実施形態と図8の実施形態とを組み合わせてもよい。具体的には、図10の液晶表示装置109は、液晶セル10Aおよび液晶セル10Bを備え、各構成が湾曲しており、カバーシート40が、液晶セル10Aの表示領域に対応した位置に第1の透過部42Aを備え、液晶セル10Bの表示領域に対応した位置に第2の透過部42Bを備える。 The above embodiments may be combined as appropriate, and the configuration in the above embodiment may be replaced with an optically equivalent configuration. For example, as shown in FIG. 4, the embodiment of FIG. 2 may be combined with the embodiment of FIG. Specifically, the liquid crystal display device 103 of FIG. 4 includes a combination of the first optical compensation layer 50 and the second optical compensation layer 70 and an adhesive that fills the opening of the cover sheet. Further, for example, the opening of the cover sheet in the illustrated example may be replaced with a transparent portion. For example, as shown in FIG. 10, the embodiment of FIG. 6 may be combined with the embodiment of FIG. Specifically, the liquid crystal display device 109 of FIG. 10 includes a liquid crystal cell 10A and a liquid crystal cell 10B, each configuration is curved, and the cover sheet 40 is first positioned at a position corresponding to the display area of the liquid crystal cell 10A. 42A, and a second transmissive portion 42B is provided at a position corresponding to the display area of the liquid crystal cell 10B.
 本明細書に記載されていない事項は、当業界で周知慣用されている液晶表示装置の構成が採用され得る。 As for matters not described in the present specification, a configuration of a liquid crystal display device well known and commonly used in the industry can be adopted.
 以下、液晶表示装置を構成する各部材および光学フィルムについて説明する。 Hereinafter, each member and optical film constituting the liquid crystal display device will be described.
B.液晶セル
 液晶セル10は、一対の基板11、11’と、当該基板間に挟持された表示媒体としての液晶層12とを有する。一般的な構成においては、一方の基板に、カラーフィルター及びブラックマトリクスが設けられており、他方の基板に、液晶の電気光学特性を制御するスイッチング素子と、このスイッチング素子にゲート信号を与える走査線及びソース信号を与える信号線と、画素電極及び対向電極とが設けられている。上記基板の間隔(セルギャップ)は、スペーサー等によって制御されている。上記基板の液晶層と接する側には、例えば、ポリイミドからなる配向膜等を設けることができる。
B. Liquid Crystal Cell The liquid crystal cell 10 includes a pair of substrates 11 and 11 'and a liquid crystal layer 12 as a display medium sandwiched between the substrates. In a general configuration, a color filter and a black matrix are provided on one substrate, a switching element that controls the electro-optical characteristics of the liquid crystal on the other substrate, and a scanning line that supplies a gate signal to the switching element. In addition, a signal line for supplying a source signal, a pixel electrode, and a counter electrode are provided. The distance between the substrates (cell gap) is controlled by a spacer or the like. For example, an alignment film made of polyimide can be provided on the side of the substrate in contact with the liquid crystal layer.
 1つの実施形態においては、液晶層は、電界が存在しない状態でホメオトロピック配列に配向させた液晶分子を含む。「ホメオトロピック配列に配向させた液晶分子」とは、配向処理された基板と液晶分子の相互作用の結果として、上記液晶分子の配向ベクトルが基板平面に対し、垂直に配向した状態のものをいう。このような液晶層(結果として、液晶セル)は、代表的には、nz>nx=nyの3次元屈折率を示す。このような3次元屈折率を示す液晶層を用いる駆動モードの代表例としては、バーティカル・アライメント(VA)モードが挙げられる。VAモードは、マルチドメインVA(MVA)モードを包含する。 In one embodiment, the liquid crystal layer includes liquid crystal molecules aligned in a homeotropic alignment in the absence of an electric field. “Liquid crystal molecules aligned in homeotropic alignment” means a state in which the alignment vector of the liquid crystal molecules is aligned perpendicularly to the substrate plane as a result of the interaction between the aligned substrate and the liquid crystal molecules. . Such a liquid crystal layer (as a result, a liquid crystal cell) typically exhibits a three-dimensional refractive index of nz> nx = ny. A typical example of the drive mode using such a liquid crystal layer exhibiting a three-dimensional refractive index is a vertical alignment (VA) mode. The VA mode includes a multi-domain VA (MVA) mode.
 別の実施形態においては、液晶層は、電界が存在しない状態でホモジニアス配列に配向させた液晶分子を含む。「ホモジニアス配列に配向させた液晶分子」とは、配向処理された基板と液晶分子の相互作用の結果として、上記液晶分子の配向ベクトルが基板平面に対し、平行かつ一様に配向した状態のものをいう。このような液晶層(結果として、液晶セル)は、代表的には、nx>ny=nzの3次元屈折率を示す。このような3次元屈折率を示す液晶層を用いる駆動モードの代表例としては、インプレーンスイッチング(IPS)モード、フリンジフィールドスイッチング(FFS)モード等が挙げられる。なお、上記のIPSモードは、V字型電極又はジグザグ電極等を採用した、スーパー・インプレーンスイッチング(S-IPS)モードや、アドバンスド・スーパー・インプレーンスイッチング(AS-IPS)モードを包含する。また、上記のFFSモードは、V字型電極又はジグザグ電極等を採用した、アドバンスド・フリンジフィールドスイッチング(A-FFS)モードや、ウルトラ・フリンジフィールドスイッチング(U-FFS)モードを包含する。 In another embodiment, the liquid crystal layer includes liquid crystal molecules aligned in a homogeneous alignment in the absence of an electric field. “Liquid crystal molecules aligned in a homogeneous arrangement” means a state in which the alignment vector of the liquid crystal molecules is aligned in parallel and uniformly with respect to the substrate plane as a result of the interaction between the aligned substrate and the liquid crystal molecules. Say. Such a liquid crystal layer (as a result, a liquid crystal cell) typically exhibits a three-dimensional refractive index of nx> ny = nz. Typical examples of drive modes using such a liquid crystal layer exhibiting a three-dimensional refractive index include an in-plane switching (IPS) mode and a fringe field switching (FFS) mode. The IPS mode includes a super-in-plane switching (S-IPS) mode and an advanced super-in-plane switching (AS-IPS) mode using a V-shaped electrode or a zigzag electrode. The FFS mode includes an advanced fringe field switching (A-FFS) mode and an ultra fringe field switching (U-FFS) mode employing a V-shaped electrode or a zigzag electrode.
C.偏光子
 第1の偏光子および第2の偏光子(以下、まとめて単に偏光子と称する場合がある)としては、任意の適切な偏光子が採用され得る。例えば、偏光子を形成する樹脂フィルムは、単層の樹脂フィルムであってもよく、二層以上の積層体であってもよい。
C. Polarizer Any appropriate polarizer may be adopted as the first polarizer and the second polarizer (hereinafter, sometimes simply referred to as a polarizer). For example, the resin film forming the polarizer may be a single-layer resin film or a laminate of two or more layers.
 単層の樹脂フィルムから構成される偏光子の具体例としては、ポリビニルアルコール(PVA)系フィルム、部分ホルマール化PVA系フィルム、エチレン・酢酸ビニル共重合体系部分ケン化フィルム等の親水性高分子フィルムに、ヨウ素や二色性染料等の二色性物質による染色処理および延伸処理が施されたもの、PVAの脱水処理物やポリ塩化ビニルの脱塩酸処理物等ポリエン系配向フィルム等が挙げられる。好ましくは、光学特性に優れることから、PVA系フィルムをヨウ素で染色し一軸延伸して得られた偏光子が用いられる。 Specific examples of polarizers composed of a single-layer resin film include hydrophilic polymer films such as polyvinyl alcohol (PVA) films, partially formalized PVA films, and ethylene / vinyl acetate copolymer partially saponified films. In addition, there may be mentioned polyene-based oriented films such as those subjected to dyeing treatment and stretching treatment with dichroic substances such as iodine and dichroic dyes, PVA dehydrated products and polyvinyl chloride dehydrochlorinated products. Preferably, a polarizer obtained by dyeing a PVA film with iodine and uniaxially stretching is used because of excellent optical properties.
 上記ヨウ素による染色は、例えば、PVA系フィルムをヨウ素水溶液に浸漬することにより行われる。上記一軸延伸の延伸倍率は、好ましくは3~7倍である。延伸は、染色処理後に行ってもよいし、染色しながら行ってもよい。また、延伸してから染色してもよい。必要に応じて、PVA系フィルムに、膨潤処理、架橋処理、洗浄処理、乾燥処理等が施される。例えば、染色の前にPVA系フィルムを水に浸漬して水洗することで、PVA系フィルム表面の汚れやブロッキング防止剤を洗浄することができるだけでなく、PVA系フィルムを膨潤させて染色ムラなどを防止することができる。 The dyeing with iodine is performed, for example, by immersing a PVA film in an aqueous iodine solution. The stretching ratio of the uniaxial stretching is preferably 3 to 7 times. The stretching may be performed after the dyeing treatment or may be performed while dyeing. Moreover, you may dye | stain after extending | stretching. If necessary, the PVA film is subjected to swelling treatment, crosslinking treatment, washing treatment, drying treatment and the like. For example, by immersing the PVA film in water and washing it before dyeing, not only can the surface of the PVA film be cleaned of dirt and anti-blocking agents, but the PVA film can be swollen to cause uneven staining. Can be prevented.
 偏光子の厚みは、好ましくは1μm~80μmであり、より好ましくは10μm~50μmであり、さらに好ましくは15μm~40μmであり、特に好ましくは20μm~30μmである。偏光子の厚みがこのような範囲であれば、高温高湿下の耐久性が優れたものとなり得る。 The thickness of the polarizer is preferably 1 μm to 80 μm, more preferably 10 μm to 50 μm, still more preferably 15 μm to 40 μm, and particularly preferably 20 μm to 30 μm. If the thickness of the polarizer is in such a range, durability under high temperature and high humidity can be excellent.
 偏光子は、好ましくは、波長380nm~780nmのいずれかの波長で吸収二色性を示す。偏光子の単体透過率は、好ましくは40.0%~46.0%であり、より好ましくは41.0%~44.0%である。偏光子の偏光度は、好ましくは97.0%以上であり、より好ましくは99.0%以上であり、さらに好ましくは99.9%以上である。 The polarizer preferably exhibits absorption dichroism at any wavelength between 380 nm and 780 nm. The single transmittance of the polarizer is preferably 40.0% to 46.0%, more preferably 41.0% to 44.0%. The polarization degree of the polarizer is preferably 97.0% or more, more preferably 99.0% or more, and further preferably 99.9% or more.
 第1の偏光子20および第2の偏光子60は、それぞれ、少なくとも一方の面に保護層(図示せず)が設けられてもよい。すなわち、第1の偏光子20および第2の偏光子60は、それぞれ、偏光板として液晶表示装置に組み込まれてもよい。なお、第2の偏光子60は、上記のとおり円偏光板として液晶表示装置に組み込まれてもよい。 Each of the first polarizer 20 and the second polarizer 60 may be provided with a protective layer (not shown) on at least one surface. That is, each of the first polarizer 20 and the second polarizer 60 may be incorporated in a liquid crystal display device as a polarizing plate. The second polarizer 60 may be incorporated in the liquid crystal display device as a circularly polarizing plate as described above.
 保護層は、偏光子の保護層として使用できる任意の適切なフィルムで形成される。当該フィルムの主成分となる材料の具体例としては、トリアセチルセルロース(TAC)等のセルロース系樹脂や、ポリエステル系、ポリビニルアルコール系、ポリカーボネート系、ポリアミド系、ポリイミド系、ポリエーテルスルホン系、ポリスルホン系、ポリスチレン系、ポリノルボルネン系、ポリオレフィン系、(メタ)アクリル系、アセテート系等の透明樹脂等が挙げられる。また、(メタ)アクリル系、ウレタン系、(メタ)アクリルウレタン系、エポキシ系、シリコーン系等の熱硬化型樹脂または紫外線硬化型樹脂等も挙げられる。この他にも、例えば、シロキサン系ポリマー等のガラス質系ポリマーも挙げられる。また、特開2001-343529号公報(WO01/37007)に記載のポリマーフィルムも使用できる。このフィルムの材料としては、例えば、側鎖に置換または非置換のイミド基を有する熱可塑性樹脂と、側鎖に置換または非置換のフェニル基ならびにニトリル基を有する熱可塑性樹脂を含有する樹脂組成物が使用でき、例えば、イソブテンとN-メチルマレイミドからなる交互共重合体と、アクリロニトリル・スチレン共重合体とを有する樹脂組成物が挙げられる。当該ポリマーフィルムは、例えば、上記樹脂組成物の押出成形物であり得る。 The protective layer is formed of any appropriate film that can be used as a protective layer for the polarizer. Specific examples of the material as the main component of the film include cellulose resins such as triacetyl cellulose (TAC), polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, polyimide-based, polyethersulfone-based, and polysulfone-based materials. And transparent resins such as polystyrene, polynorbornene, polyolefin, (meth) acryl, and acetate. Further, thermosetting resins such as (meth) acrylic, urethane-based, (meth) acrylurethane-based, epoxy-based, and silicone-based or ultraviolet curable resins are also included. In addition to this, for example, a glassy polymer such as a siloxane polymer is also included. Further, a polymer film described in JP-A-2001-343529 (WO01 / 37007) can also be used. As a material for this film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and nitrile group in the side chain For example, a resin composition having an alternating copolymer of isobutene and N-methylmaleimide and an acrylonitrile / styrene copolymer can be mentioned. The polymer film can be, for example, an extruded product of the resin composition.
 保護層の厚みは、代表的には5mm以下であり、好ましくは1mm以下、より好ましくは1μm~500μm、さらに好ましくは5μm~150μmである。なお、表面処理が施されている場合、保護層の厚みは、表面処理層の厚みを含めた厚みである。 The thickness of the protective layer is typically 5 mm or less, preferably 1 mm or less, more preferably 1 μm to 500 μm, and even more preferably 5 μm to 150 μm. In addition, when the surface treatment is performed, the thickness of the protective layer is a thickness including the thickness of the surface treatment layer.
 第1の偏光子20および/または第2の偏光子60の液晶セル側に保護層(以下、内側保護層と称する)が設けられる場合、当該内側保護層は、光学的に等方性であることが好ましい。「光学的に等方性である」とは、面内位相差Re(550)が0nm~10nmであり、厚み方向の位相差Rth(550)が-10nm~+10nmであることをいう。内側保護層は、光学的に等方性である限り、任意の適切な材料で構成され得る。当該材料は、例えば、保護層に関して上記した材料から適切に選択され得る。 When a protective layer (hereinafter referred to as an inner protective layer) is provided on the liquid crystal cell side of the first polarizer 20 and / or the second polarizer 60, the inner protective layer is optically isotropic. It is preferable. “Optically isotropic” means that the in-plane retardation Re (550) is 0 nm to 10 nm and the thickness direction retardation Rth (550) is −10 nm to +10 nm. The inner protective layer can be composed of any suitable material as long as it is optically isotropic. The material can be appropriately selected from the materials described above with respect to the protective layer, for example.
 内側保護層の厚みは、好ましくは5μm~200μm、より好ましくは10μm~100μm、さらに好ましくは15μm~95μmである。 The thickness of the inner protective layer is preferably 5 μm to 200 μm, more preferably 10 μm to 100 μm, and still more preferably 15 μm to 95 μm.
D.カバーシート
 カバーシート40は、代表的には、液晶表示装置が構造物に組み込まれて用いられる場合、当該液晶表示装置の保護および/またはデザイン上の要請から設けられ得る。したがって、カバーシート40は、代表的には、液晶表示装置の表示機能を妨げないよう、液晶セルの表示領域に対応した透過部42を有する。透過部は、上記のとおり、物理的透過部(例えば、開口部)および光学的透過部(例えば、透明部)を包含する。
D. Cover Sheet Typically, the cover sheet 40 may be provided for protection and / or design requirements of the liquid crystal display device when the liquid crystal display device is incorporated into a structure. Therefore, the cover sheet 40 typically has a transmissive portion 42 corresponding to the display area of the liquid crystal cell so as not to hinder the display function of the liquid crystal display device. As described above, the transmission part includes a physical transmission part (for example, an opening) and an optical transmission part (for example, a transparent part).
 カバーシートは、任意の適切な材料で構成され得る。構成材料の代表例としては、樹脂が挙げられる。カバーシートとして適切な強度を有し、かつ、所望の形状への成形および開口部の形成が容易だからである。樹脂の具体例としては、ポリアリレート、ポリアミド、ポリイミド、ポリエステル、ポリアリールエーテルケトン、ポリアミドイミド、ポリエステルイミド、ポリビニルアルコール、ポリフマル酸エステル、ポリエーテルサルフォン、ポリサルフォン、ノルボルネン樹脂、ポリカーボネート樹脂、セルロース樹脂およびポリウレタンが挙げられる。これらの樹脂は、単独で用いてもよく組み合わせて用いてもよい。 The cover sheet can be composed of any suitable material. A typical example of the constituent material is a resin. This is because it has an appropriate strength as a cover sheet and is easy to be molded into a desired shape and to form an opening. Specific examples of the resin include polyarylate, polyamide, polyimide, polyester, polyaryletherketone, polyamideimide, polyesterimide, polyvinyl alcohol, polyfumaric acid ester, polyethersulfone, polysulfone, norbornene resin, polycarbonate resin, cellulose resin and A polyurethane is mentioned. These resins may be used alone or in combination.
 カバーシートは、1つの実施形態においては、遮光性を有する。遮光性は、カバーシートを成形する際に上記樹脂に遮光性材料(例えば、カーボンブラック)を配合することにより付与され得る。カバーシートが開口部を有する実施形態においては、カバーシートは、代表的には、開口部以外の全体が遮光性を有する。カバーシートが透明部を有する実施形態においては、カバーシートは、代表的には、透明部以外の全体が遮光性を有する。この場合、透明部以外の部分に遮光性材料を配合した樹脂を用いればよい。 The cover sheet has light shielding properties in one embodiment. The light shielding property can be imparted by blending a light shielding material (for example, carbon black) with the resin when the cover sheet is formed. In the embodiment in which the cover sheet has an opening, the cover sheet typically has light shielding properties except for the opening. In the embodiment in which the cover sheet has a transparent portion, the cover sheet typically has light shielding properties except for the transparent portion. In this case, what is necessary is just to use resin which mix | blended the light-shielding material in parts other than a transparent part.
 カバーシートの厚みは、好ましくは0.1mm~5mmであり、より好ましくは0.3mm~3mmである。このような厚みであれば、液晶表示装置の保護部材として適切な強度が実現され得る。本発明によれば、上記のとおり、カバーシートのこのような厚みに起因して生じ得る物理的段差を解消し、かつ、視覚的段差を顕著に減少させることができる。 The thickness of the cover sheet is preferably 0.1 mm to 5 mm, more preferably 0.3 mm to 3 mm. If it is such thickness, suitable intensity | strength as a protective member of a liquid crystal display device may be implement | achieved. According to the present invention, as described above, it is possible to eliminate the physical level difference that may be caused by such a thickness of the cover sheet and to significantly reduce the visual level difference.
E.第1の光学補償層
 第1の光学補償層50は、上記のとおり、面内位相差Re(550)が100nm~180nmであり、好ましくは110nm~170nmであり、より好ましくは120nm~160nmである。第1の光学補償層の面内位相差がこのような範囲であれば、第1の光学補償層の遅相軸方向を第2の偏光子の吸収軸方向に対して上記のように35°~55°(特に、約45°)または125°~145°(特に、約135°)の角度をなすよう設定することにより、優れた円偏光機能および反射防止機能を実現することができる。その結果、実用上許容可能な表示画面の明るさを維持しつつ、視覚的段差を顕著に減少させることができる。
E. First Optical Compensation Layer As described above, the first optical compensation layer 50 has an in-plane retardation Re (550) of 100 nm to 180 nm, preferably 110 nm to 170 nm, more preferably 120 nm to 160 nm. . If the in-plane retardation of the first optical compensation layer is within such a range, the slow axis direction of the first optical compensation layer is set to 35 ° with respect to the absorption axis direction of the second polarizer as described above. By setting an angle of ˜55 ° (particularly about 45 °) or 125 ° -145 ° (particularly about 135 °), an excellent circular polarization function and antireflection function can be realized. As a result, the visual level difference can be remarkably reduced while maintaining the brightness of the display screen that is practically acceptable.
 第1の光学補償層は、代表的には、屈折率特性がnx>ny≧nzまたはnx>nz>nyの関係を示す。第1の光学補償層のNz係数は、好ましくは0.3~2.0であり、より好ましくは0.5~1.5であり、さらに好ましくは0.5~1.3である。このような関係を満たすことにより、より優れた反射防止特性を達成し得る。 The first optical compensation layer typically shows a relationship in which the refractive index characteristic is nx> ny ≧ nz or nx> nz> ny. The Nz coefficient of the first optical compensation layer is preferably 0.3 to 2.0, more preferably 0.5 to 1.5, and still more preferably 0.5 to 1.3. By satisfying such a relationship, more excellent antireflection characteristics can be achieved.
 第1の光学補償層は、位相差値が測定光の波長に応じて大きくなる逆分散波長特性を示してもよく、位相差値が測定光の波長に応じて小さくなる正の波長分散特性を示してもよく、位相差値が測定光の波長によってもほとんど変化しないフラットな波長分散特性を示してもよい。第1の光学補償層は、好ましくは逆分散波長特性を示す。このような特性を示すことにより、いわゆるλ/2板をさらに用いることなく第1の光学補償層と第2の偏光子との組み合わせのみで所定の波長帯域にわたって反射防止機能を実現し得る。この場合、第1の光学補償層は、その面内位相差がRe(450)<Re(550)の関係を満たす。Re(450)/Re(550)は、好ましくは0.8以上1未満であり、より好ましくは0.8以上0.95以下である。さらに、第1の光学補償層の面内位相差は、好ましくはRe(550)<Re(650)の関係を満たす。Re(550)/Re(650)は、好ましくは0.8以上1未満であり、より好ましくは0.8以上0.95以下である。 The first optical compensation layer may exhibit a reverse dispersion wavelength characteristic in which the retardation value increases according to the wavelength of the measurement light, and has a positive chromatic dispersion characteristic in which the retardation value decreases according to the wavelength of the measurement light. It may also be possible to show a flat chromatic dispersion characteristic in which the phase difference value hardly changes depending on the wavelength of the measurement light. The first optical compensation layer preferably exhibits reverse dispersion wavelength characteristics. By exhibiting such characteristics, an antireflection function can be realized over a predetermined wavelength band by only using a combination of the first optical compensation layer and the second polarizer without further using a so-called λ / 2 plate. In this case, the in-plane retardation of the first optical compensation layer satisfies the relationship of Re (450) <Re (550). Re (450) / Re (550) is preferably 0.8 or more and less than 1, and more preferably 0.8 or more and 0.95 or less. Furthermore, the in-plane retardation of the first optical compensation layer preferably satisfies the relationship Re (550) <Re (650). Re (550) / Re (650) is preferably 0.8 or more and less than 1, and more preferably 0.8 or more and 0.95 or less.
 第1の光学補償層は、代表的には、上記特性を実現し得る任意の適切な樹脂で形成された位相差フィルムである。この位相差フィルムを形成する樹脂としては、例えば、ポリアリレート、ポリアミド、ポリイミド、ポリエステル、ポリアリールエーテルケトン、ポリアミドイミド、ポリエステルイミド、ポリビニルアルコール、ポリフマル酸エステル、ポリエーテルサルフォン、ポリサルフォン、ノルボルネン樹脂、ポリカーボネート樹脂、セルロース樹脂およびポリウレタンが挙げられる。これらの樹脂は、単独で用いてもよく組み合わせて用いてもよい。好ましくは、ポリアリレート、ノルボルネン樹脂またはポリカーボネート樹脂である。 The first optical compensation layer is typically a retardation film formed of any appropriate resin capable of realizing the above characteristics. Examples of the resin that forms the retardation film include polyarylate, polyamide, polyimide, polyester, polyaryletherketone, polyamideimide, polyesterimide, polyvinyl alcohol, polyfumaric acid ester, polyethersulfone, polysulfone, and norbornene resin. A polycarbonate resin, a cellulose resin, and a polyurethane are mentioned. These resins may be used alone or in combination. Polyarylate, norbornene resin or polycarbonate resin is preferable.
 ポリアリレートは、好ましくは下記式(I)で表される。
Figure JPOXMLDOC01-appb-C000001
 式(I)において、AおよびBは、それぞれ、置換基を表し、ハロゲン原子、炭素原子数1~6のアルキル基、置換若しくは無置換のアリール基であり、AおよびBは同一でも異なっていてもよい。aおよびbは、対応するAおよびBの置換数を表し、それぞれ、1~4の整数である。Dは、共有結合、CH基、C(CH基、C(CZ基(ここで、Zはハロゲン原子である)、CO基、O原子、S原子、SO基、Si(CHCH基、N(CH)基である。R1は、炭素原子数1~10の直鎖若しくは分岐のアルキル基、置換若しくは無置換のアリール基である。R2は、炭素原子数2~10の直鎖若しくは分岐のアルキル基、置換若しくは無置換のアリール基である。R3、R4、R5およびR6は、それぞれ独立して、水素原子、炭素原子数1~4の直鎖若しくは分岐のアルキル基であり、R3、R4、R5およびR6は同一でも異なっていてもよい。p1は、0~3の整数であり、p2は、1~3の整数であり、nは、2以上の整数である。
The polyarylate is preferably represented by the following formula (I).
Figure JPOXMLDOC01-appb-C000001
In the formula (I), A and B each represent a substituent, which is a halogen atom, an alkyl group having 1 to 6 carbon atoms, or a substituted or unsubstituted aryl group, and A and B are the same or different. Also good. a and b represent the corresponding numbers of substitutions of A and B, and are integers of 1 to 4, respectively. D is a covalent bond, CH 2 group, C (CH 3 ) 2 group, C (CZ 3 ) 2 group (where Z is a halogen atom), CO group, O atom, S atom, SO 2 group, Si (CH 2 CH 3 ) 2 groups and N (CH 3 ) groups. R1 is a linear or branched alkyl group having 1 to 10 carbon atoms, or a substituted or unsubstituted aryl group. R2 is a linear or branched alkyl group having 2 to 10 carbon atoms, or a substituted or unsubstituted aryl group. R3, R4, R5 and R6 are each independently a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms, and R3, R4, R5 and R6 may be the same or different. p1 is an integer of 0 to 3, p2 is an integer of 1 to 3, and n is an integer of 2 or more.
 上記ノルボルネン系樹脂は、ノルボルネン系モノマーを重合単位として重合される樹脂である。当該ノルボルネン系モノマーとしては、例えば、ノルボルネン、およびそのアルキルおよび/またはアルキリデン置換体、例えば、5-メチル-2-ノルボルネン、5-ジメチル-2-ノルボルネン、5-エチル-2-ノルボルネン、5-ブチル-2-ノルボルネン、5-エチリデン-2-ノルボルネン等、これらのハロゲン等の極性基置換体;ジシクロペンタジエン、2,3-ジヒドロジシクロペンタジエン等;ジメタノオクタヒドロナフタレン、そのアルキルおよび/またはアルキリデン置換体、およびハロゲン等の極性基置換体、例えば、6-メチル-1,4:5,8-ジメタノ-1,4,4a,5,6,7,8,8a-オクタヒドロナフタレン、6-エチル-1,4:5,8-ジメタノ-1,4,4a,5,6,7,8,8a-オクタヒドロナフタレン、6-エチリデン-1,4:5,8-ジメタノ-1,4,4a,5,6,7,8,8a-オクタヒドロナフタレン、6-クロロ-1,4:5,8-ジメタノ-1,4,4a,5,6,7,8,8a-オクタヒドロナフタレン、6-シアノ-1,4:5,8-ジメタノ-1,4,4a,5,6,7,8,8a-オクタヒドロナフタレン、6-ピリジル-1,4:5,8-ジメタノ-1,4,4a,5,6,7,8,8a-オクタヒドロナフタレン、6-メトキシカルボニル-1,4:5,8-ジメタノ-1,4,4a,5,6,7,8,8a-オクタヒドロナフタレン等;シクロペンタジエンの3~4量体、例えば、4,9:5,8-ジメタノ-3a,4,4a,5,8,8a,9,9a-オクタヒドロ-1H-ベンゾインデン、4,11:5,10:6,9-トリメタノ-3a,4,4a,5,5a,6,9,9a,10,10a,11,11a-ドデカヒドロ-1H-シクロペンタアントラセン等が挙げられる。上記ノルボルネン系樹脂は、ノルボルネン系モノマーと他のモノマーとの共重合体であってもよい。 The norbornene-based resin is a resin that is polymerized using a norbornene-based monomer as a polymerization unit. Examples of the norbornene-based monomer include norbornene and alkyl and / or alkylidene substituted products thereof such as 5-methyl-2-norbornene, 5-dimethyl-2-norbornene, 5-ethyl-2-norbornene, and 5-butyl. -2-norbornene, 5-ethylidene-2-norbornene, etc., polar group-substituted products such as halogens; dicyclopentadiene, 2,3-dihydrodicyclopentadiene, etc .; dimethanooctahydronaphthalene, its alkyl and / or alkylidene Substituents and polar group substituents such as halogen such as 6-methyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6- Ethyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-oct Hydronaphthalene, 6-ethylidene-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-chloro-1,4: 5,8-dimethano -1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-cyano-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a -Octahydronaphthalene, 6-pyridyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-methoxycarbonyl-1,4: 5 8-Dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene and the like; Tripentamers of cyclopentadiene such as 4,9: 5,8-dimethano-3a, 4 4a, 5,8,8a, 9,9a-Octahydro-1H-benzoin 4,11: 5,10: 6,9-trimethano-3a, 4,4a, 5,5a, 6,9,9a, 10,10a, 11,11a-dodecahydro-1H-cyclopentanthracene and the like It is done. The norbornene-based resin may be a copolymer of a norbornene-based monomer and another monomer.
 上記ポリカーボネート樹脂としては、本発明の効果が得られる限りにおいて、任意の適切なポリカーボネート樹脂を用いることができる。好ましくは、ポリカーボネート樹脂は、フルオレン系ジヒドロキシ化合物に由来する構造単位と、イソソルビド系ジヒドロキシ化合物に由来する構造単位と、脂環式ジオール、脂環式ジメタノール、ジ、トリまたはポリエチレングリコール、ならびに、アルキレングリコールまたはスピログリコールからなる群から選択される少なくとも1つのジヒドロキシ化合物に由来する構造単位と、を含む。好ましくは、ポリカーボネート樹脂は、フルオレン系ジヒドロキシ化合物に由来する構造単位と、イソソルビド系ジヒドロキシ化合物に由来する構造単位と、脂環式ジメタノールに由来する構造単位ならびに/あるいはジ、トリまたはポリエチレングリコールに由来する構造単位と、を含み;さらに好ましくは、フルオレン系ジヒドロキシ化合物に由来する構造単位と、イソソルビド系ジヒドロキシ化合物に由来する構造単位と、ジ、トリまたはポリエチレングリコールに由来する構造単位と、を含む。ポリカーボネート樹脂は、必要に応じてその他のジヒドロキシ化合物に由来する構造単位を含んでいてもよい。なお、本発明に好適に用いられ得るポリカーボネート樹脂の詳細は、例えば、特開2014-10291号公報、特開2014-26266号公報に記載されており、当該記載は本明細書に参考として援用される。 As the polycarbonate resin, any appropriate polycarbonate resin can be used as long as the effects of the present invention can be obtained. Preferably, the polycarbonate resin includes a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, an alicyclic diol, an alicyclic dimethanol, di, tri, or polyethylene glycol, and an alkylene. A structural unit derived from at least one dihydroxy compound selected from the group consisting of glycol or spiroglycol. Preferably, the polycarbonate resin is derived from a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, a structural unit derived from an alicyclic dimethanol and / or a di-, tri- or polyethylene glycol. More preferably, a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and a structural unit derived from di, tri, or polyethylene glycol. The polycarbonate resin may contain structural units derived from other dihydroxy compounds as necessary. Details of the polycarbonate resin that can be suitably used in the present invention are described in, for example, Japanese Patent Application Laid-Open Nos. 2014-10291 and 2014-26266, and the description is incorporated herein by reference. The
 前記ポリカーボネート樹脂のガラス転移温度は、110℃以上180℃以下であることが好ましく、より好ましくは120℃以上165℃以下である。ガラス転移温度が過度に低いと耐熱性が悪くなる傾向にあり、フィルム成形後に寸法変化を起こす可能性があり、又、得られる液晶表示装置の画像品質を下げる場合がある。ガラス転移温度が過度に高いと、フィルム成形時の成形安定性が悪くなる場合があり、又フィルムの透明性を損なう場合がある。なお、ガラス転移温度は、JIS K 7121(1987)に準じて求められる。 The glass transition temperature of the polycarbonate resin is preferably 110 ° C. or higher and 180 ° C. or lower, more preferably 120 ° C. or higher and 165 ° C. or lower. If the glass transition temperature is excessively low, the heat resistance tends to deteriorate, there is a possibility of causing a dimensional change after film formation, and the image quality of the obtained liquid crystal display device may be lowered. If the glass transition temperature is excessively high, the molding stability at the time of film molding may deteriorate, and the transparency of the film may be impaired. The glass transition temperature is determined according to JIS K 7121 (1987).
 前記ポリカーボネート樹脂の分子量は、還元粘度で表すことができる。還元粘度は、溶媒として塩化メチレンを用い、ポリカーボネート濃度を0.6g/dLに精密に調製し、温度20.0℃±0.1℃でウベローデ粘度管を用いて測定される。還元粘度の下限は、通常0.30dL/gが好ましく、より好ましくは0.35dL/g以上である。還元粘度の上限は、通常1.20dL/gが好ましく、より好ましくは1.00dL/g、更に好ましくは0.80dL/gである。還元粘度が前記下限値より小さいと成形品の機械的強度が小さくなるという問題が生じる場合がある。一方、還元粘度が前記上限値より大きいと、成形する際の流動性が低下し、生産性や成形性が低下するという問題が生じる場合がある。 The molecular weight of the polycarbonate resin can be represented by a reduced viscosity. The reduced viscosity is measured using a Ubbelohde viscometer at a temperature of 20.0 ° C. ± 0.1 ° C., using methylene chloride as a solvent, precisely adjusting the polycarbonate concentration to 0.6 g / dL. The lower limit of the reduced viscosity is usually preferably 0.30 dL / g, more preferably 0.35 dL / g or more. The upper limit of the reduced viscosity is usually preferably 1.20 dL / g, more preferably 1.00 dL / g, still more preferably 0.80 dL / g. If the reduced viscosity is less than the lower limit, there may be a problem that the mechanical strength of the molded product is reduced. On the other hand, if the reduced viscosity is larger than the upper limit, the fluidity at the time of molding is lowered, and there may be a problem that productivity and moldability are lowered.
 位相差フィルムは、代表的には、樹脂フィルムを少なくとも一方向に延伸することにより作製される。 The retardation film is typically produced by stretching a resin film in at least one direction.
 上記樹脂フィルムの形成方法としては、任意の適切な方法が採用され得る。例えば、溶融押出し法(例えば、Tダイ成形法)、キャスト塗工法(例えば、流延法)、カレンダー成形法、熱プレス法、共押出し法、共溶融法、多層押出し、インフレーション成形法等が挙げられる。好ましくは、Tダイ成形法、流延法およびインフレーション成形法が用いられる。 Any appropriate method can be adopted as a method for forming the resin film. For example, a melt extrusion method (for example, a T-die molding method), a cast coating method (for example, a casting method), a calendar molding method, a hot press method, a co-extrusion method, a co-melting method, a multilayer extrusion method, an inflation molding method, etc. It is done. Preferably, a T-die molding method, a casting method, and an inflation molding method are used.
 樹脂フィルム(未延伸フィルム)の厚みは、所望の光学特性、後述の延伸条件などに応じて、任意の適切な値に設定され得る。好ましくは50μm~300μmである。 The thickness of the resin film (unstretched film) can be set to any appropriate value depending on desired optical characteristics, stretching conditions described later, and the like. The thickness is preferably 50 μm to 300 μm.
 上記延伸は、任意の適切な延伸方法、延伸条件(例えば、延伸温度、延伸倍率、延伸方向)が採用され得る。具体的には、自由端延伸、固定端延伸、自由端収縮、固定端収縮などの様々な延伸方法を、単独で用いることも、同時もしくは逐次で用いることもできる。延伸方向に関しても、水平方向、垂直方向、厚さ方向、対角方向等、様々な方向や次元に行なうことができる。延伸の温度は、樹脂フィルムのガラス転移温度(Tg)に対し、Tg-30℃~Tg+60℃であることが好ましく、より好ましくはTg-10℃~Tg+50℃である。 Any appropriate stretching method and stretching conditions (for example, stretching temperature, stretching ratio, stretching direction) may be employed for the stretching. Specifically, various stretching methods such as free end stretching, fixed end stretching, free end contraction, and fixed end contraction can be used singly or simultaneously or sequentially. The stretching direction can also be performed in various directions and dimensions such as a horizontal direction, a vertical direction, a thickness direction, and a diagonal direction. The stretching temperature is preferably Tg-30 ° C. to Tg + 60 ° C., more preferably Tg-10 ° C. to Tg + 50 ° C. with respect to the glass transition temperature (Tg) of the resin film.
 上記延伸方法、延伸条件を適宜選択することにより、上記所望の光学特性(例えば、屈折率特性、面内位相差、Nz係数)を有する位相差フィルムを得ることができる。 A retardation film having the desired optical characteristics (for example, refractive index characteristics, in-plane retardation, Nz coefficient) can be obtained by appropriately selecting the stretching method and stretching conditions.
 1つの実施形態においては、位相差フィルムは、長尺状の樹脂フィルムを長手方向に対して角度θの方向に連続的に斜め延伸することにより作製される。斜め延伸を採用することにより、フィルムの長手方向に対して角度θの配向角(角度θの方向に遅相軸)を有する長尺状の延伸フィルムが得られ、例えば、偏光子との積層に際してロールツーロールが可能となり、製造工程を簡略化することができる。偏光子の吸収軸は、その製造方法に起因して長尺状フィルムの長手方向または幅方向に発現するので、上記角度θは、第2の偏光子の吸収軸と第1の光学補償層の遅相軸とのなす角度であり得る。 In one embodiment, the retardation film is produced by continuously stretching a long resin film obliquely in the direction of an angle θ with respect to the longitudinal direction. By adopting oblique stretching, a long stretched film having an orientation angle of θ with respect to the longitudinal direction of the film (slow axis in the direction of angle θ) can be obtained. For example, when laminating with a polarizer Roll-to-roll is possible, and the manufacturing process can be simplified. Since the absorption axis of the polarizer is expressed in the longitudinal direction or the width direction of the long film due to the manufacturing method thereof, the angle θ is equal to the absorption axis of the second polarizer and the first optical compensation layer. It may be an angle formed with the slow axis.
 斜め延伸に用いる延伸機としては、例えば、横および/または縦方向に、左右異なる速度の送り力もしくは引張り力または引き取り力を付加し得るテンター式延伸機が挙げられる。テンター式延伸機には、横一軸延伸機、同時二軸延伸機等があるが、長尺状の樹脂フィルムを連続的に斜め延伸し得る限り、任意の適切な延伸機が用いられ得る。 Examples of the stretching machine used for the oblique stretching include a tenter type stretching machine capable of adding feed forces, pulling forces, or pulling forces at different speeds in the lateral and / or longitudinal directions. The tenter type stretching machine includes a horizontal uniaxial stretching machine, a simultaneous biaxial stretching machine, and the like, but any suitable stretching machine can be used as long as a long resin film can be continuously stretched obliquely.
 位相差フィルム(延伸フィルム、すなわち第1の光学補償層)の厚みは、好ましくは20μm~100μmであり、より好ましくは20μm~80μmであり、さらに好ましくは20μm~65μmである。このような厚みであれば、上記所望の面内位相差およびNz係数が得られ得る。 The thickness of the retardation film (stretched film, that is, the first optical compensation layer) is preferably 20 μm to 100 μm, more preferably 20 μm to 80 μm, and further preferably 20 μm to 65 μm. With such a thickness, the desired in-plane retardation and Nz coefficient can be obtained.
F.第2の光学補償層
 第2の光学補償層の光学特性、構成材料、厚み等は、第1の光学補償層に関して上記E項で説明したとおりである。第2の光学補償層は、第1の光学補償層と同一であってもよく、異なっていてもよい。
F. Second Optical Compensation Layer Optical characteristics, constituent materials, thicknesses, and the like of the second optical compensation layer are as described in the above section E for the first optical compensation layer. The second optical compensation layer may be the same as or different from the first optical compensation layer.
G.第1の光学補償層および第2の光学補償層の光学的に等価な変形例
 第1の光学補償層は、第1の光学補償層といわゆるλ/2板との積層体であってもよい。同様に、第2の光学補償層は、第2の光学補償層とλ/2板との積層体であってもよい。このような構成であれば、広い波長帯域にわたって優れた円偏光機能および反射防止機能を実現することができる。
G. Optically equivalent modification of the first optical compensation layer and the second optical compensation layer The first optical compensation layer may be a laminate of the first optical compensation layer and a so-called λ / 2 plate. . Similarly, the second optical compensation layer may be a laminate of the second optical compensation layer and a λ / 2 plate. With such a configuration, an excellent circular polarization function and antireflection function can be realized over a wide wavelength band.
 λ/2板は、好ましくは、屈折率特性がnx>ny≧nzの関係を示す。λ/2板の面内位相差Re(550)は、好ましくは190nm~360nmであり、より好ましくは220nm~330nmである。 The λ / 2 plate preferably exhibits a relationship in which the refractive index characteristic is nx> ny ≧ nz. The in-plane retardation Re (550) of the λ / 2 plate is preferably 190 nm to 360 nm, and more preferably 220 nm to 330 nm.
 λ/2板の遅相軸と第1の光学補償層の遅相軸または第2の光学補償層の遅相軸との関係は、λ/2板を通過した後の偏光方向と第1の光学補償層または第2の光学補償層の遅相軸とのなす角度が適切になるように調整されることが好ましい。例えば、第2の偏光子の吸収軸に対して、λ/2板の遅相軸が右回り側(0°~+180°)に位置する場合、第1の光学補償層の遅相軸の軸角度は、λ/2板を通過した後の偏光方向に対して、好ましくは+40°~+50°であり、より好ましくは+43°~+47°であり、さらに好ましくは+45°である。また例えば、第2の偏光子の吸収軸に対して、λ/2板の遅相軸が左回り側(-180°~0°)に位置する場合、第1の光学補償層の遅相軸の軸角度は、λ/2板を通過した後の偏光方向に対して、好ましくは-40°~-50°であり、より好ましくは-43°~-47°であり、さらに好ましくは-45°である。第2の光学補償層および第1の偏光子に関しても、同様の関係が適用され得る。ここで、+x°とは、基準となる方向に対して時計回りにx°となることを意味し、-x°とは、基準となる方向に対して反時計回りにx°となることを意味する。 The relationship between the slow axis of the λ / 2 plate and the slow axis of the first optical compensation layer or the slow axis of the second optical compensation layer is as follows. It is preferable to adjust the angle formed with the slow axis of the optical compensation layer or the second optical compensation layer to be appropriate. For example, when the slow axis of the λ / 2 plate is positioned clockwise (0 ° to + 180 °) with respect to the absorption axis of the second polarizer, the axis of the slow axis of the first optical compensation layer The angle is preferably + 40 ° to + 50 °, more preferably + 43 ° to + 47 °, and further preferably + 45 ° with respect to the polarization direction after passing through the λ / 2 plate. Also, for example, when the slow axis of the λ / 2 plate is located counterclockwise (−180 ° to 0 °) with respect to the absorption axis of the second polarizer, the slow axis of the first optical compensation layer Is preferably −40 ° to −50 °, more preferably −43 ° to −47 °, and still more preferably −45 with respect to the polarization direction after passing through the λ / 2 plate. °. A similar relationship can be applied to the second optical compensation layer and the first polarizer. Here, + x ° means that x ° is clockwise with respect to the reference direction, and −x ° is that x ° is counterclockwise with respect to the reference direction. means.
 λ/2板は、代表的には、第1の光学補償層および第2の光学補償層と同様、樹脂フィルムの延伸フィルムである。 The λ / 2 plate is typically a stretched film of a resin film, similar to the first optical compensation layer and the second optical compensation layer.
H.粘着剤
 1つの実施形態においては、上記のとおり、カバーシート40の透過部は開口部であり、当該開口部は粘着剤により充填されている。その結果、開口部により形成される空気層が排除されるので、層界面における反射および/または屈折が抑制され得る。結果として、表示画面の明るさを維持しつつ、視覚的段差をさらに顕著に減少させることができる。
H. Adhesive In one embodiment, as above-mentioned, the permeation | transmission part of the cover sheet 40 is an opening part, and the said opening part is filled with the adhesive. As a result, since the air layer formed by the opening is excluded, reflection and / or refraction at the layer interface can be suppressed. As a result, the visual level difference can be further remarkably reduced while maintaining the brightness of the display screen.
 粘着剤の屈折率は、上記のとおり、好ましくは1.30~1.70であり、より好ましくは1.40~1.60であり、さらに好ましくは1.45~1.55である。粘着剤の屈折率をこのような範囲とすることにより、層界面における反射および/または屈折をさらに抑制することができ、表示画面の明るさと視覚的段差とのバランスがさらに優れたものとなり得る。 As described above, the refractive index of the pressure-sensitive adhesive is preferably 1.30 to 1.70, more preferably 1.40 to 1.60, and still more preferably 1.45 to 1.55. By setting the refractive index of the pressure-sensitive adhesive within such a range, reflection and / or refraction at the layer interface can be further suppressed, and the balance between the brightness of the display screen and the visual step can be further improved.
 粘着剤の屈折率と該粘着剤に隣接する層の屈折率との差は、好ましくは0.20以下であり、より好ましくは0~0.15である。粘着剤の屈折率と隣接する層の屈折率との差をこのような範囲とすることにより、粘着剤の屈折率を所定の範囲とする場合の上記効果がさらに促進され得る。 The difference between the refractive index of the pressure-sensitive adhesive and the refractive index of the layer adjacent to the pressure-sensitive adhesive is preferably 0.20 or less, more preferably 0 to 0.15. By setting the difference between the refractive index of the pressure-sensitive adhesive and the refractive index of the adjacent layer in such a range, the above-described effect when the refractive index of the pressure-sensitive adhesive is set within a predetermined range can be further promoted.
 上記のとおり、粘着剤は、開口部のみを充填してもよく、カバーシート40と第2の偏光子60(または、存在する場合には第1の光学補償層50)との間に設けられた粘着剤層80の一部であってもよい。後者の場合、粘着剤層の厚み(カバーシートの開口部に対応する部分以外の厚み)は、目的、接着力等に応じて適切に設定され得る。粘着剤層の厚みは、好ましくは1μm~500μmであり、より好ましくは1μm~200μmであり、さらに好ましくは1μm~100μmである。 As described above, the adhesive may fill only the opening, and is provided between the cover sheet 40 and the second polarizer 60 (or the first optical compensation layer 50 if present). A part of the pressure-sensitive adhesive layer 80 may be used. In the latter case, the thickness of the pressure-sensitive adhesive layer (thickness other than the portion corresponding to the opening of the cover sheet) can be appropriately set according to the purpose, adhesive force, and the like. The thickness of the pressure-sensitive adhesive layer is preferably 1 μm to 500 μm, more preferably 1 μm to 200 μm, and still more preferably 1 μm to 100 μm.
 粘着剤層は、上記のような特性を有する任意の適切な粘着剤で構成され得る。具体例としては、アクリル系重合体、シリコーン系ポリマー、ポリエステル、ポリウレタン、ポリアミド、ポリエーテル、フッ素系ポリマー、ゴム系ポリマーなどをベースポリマーとする粘着剤が挙げられる。好ましくは、アクリル系重合体をベースポリマーとする粘着剤(アクリル系粘着剤)である。優れた光学的透明性、適度な粘着特性(濡れ性と凝集性と接着性)、ならびに、優れた耐候性および耐熱性に優れるからである。 The pressure-sensitive adhesive layer can be composed of any appropriate pressure-sensitive adhesive having the above characteristics. Specific examples include pressure sensitive adhesives based on acrylic polymers, silicone polymers, polyesters, polyurethanes, polyamides, polyethers, fluorine polymers, rubber polymers, and the like. Preferably, it is an adhesive (acrylic adhesive) having an acrylic polymer as a base polymer. It is because it is excellent in excellent optical transparency, moderate pressure-sensitive adhesive properties (wetting properties, cohesiveness and adhesiveness), and excellent weather resistance and heat resistance.
 以下、実施例によって本発明を具体的に説明するが、本発明はこれら実施例によって限定されるものではない。なお、各特性の測定方法は以下の通りである。 Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples. In addition, the measuring method of each characteristic is as follows.
(1)物理的段差
 実施例および比較例で得られた液晶表示装置について、視認側表面の凹凸の有無を確認した。
(2)視覚的段差
 実施例および比較例で得られた液晶表示装置に実際に画像を表示させた状態で、段差を目視により確認した。以下の基準で評価した。
   A:段差は実質的に認識されず、画像の視認に全く問題がない
   B:段差は認識されるが、画像の視認に実質的に影響はない
   C:画像の視認に違和感が生じるような段差が認識される
   D:画像の視認に大きな影響を与えるほど段差が明確に認識される
(3)表示画面の明るさ
 実施例および比較例で得られた液晶表示装置を全画面白表示としたときの輝度を測定した。比較例1の輝度を100%としたときの輝度比を用いて以下の基準で評価した。
   A:輝度比が90%を超える
   B:輝度比が80%~90%
   C:輝度比が70%~80%
   D:輝度比が70%未満
(1) Physical level | step difference About the liquid crystal display device obtained by the Example and the comparative example, the presence or absence of the unevenness | corrugation of the visual recognition side surface was confirmed.
(2) Visual step The step was visually confirmed in a state where an image was actually displayed on the liquid crystal display devices obtained in Examples and Comparative Examples. Evaluation was made according to the following criteria.
A: The level difference is not substantially recognized, and there is no problem in the visual recognition of the image. B: The level difference is recognized, but the visual recognition of the image is not substantially affected. C: The level difference in which the visual recognition of the image is uncomfortable. D: The level difference is clearly recognized so as to greatly affect the visual recognition of the image. (3) Brightness of the display screen When the liquid crystal display devices obtained in the example and the comparative example are set to a full screen white display The brightness of was measured. Evaluation was made according to the following criteria using the luminance ratio when the luminance of Comparative Example 1 was 100%.
A: The luminance ratio exceeds 90% B: The luminance ratio is 80% to 90%
C: The luminance ratio is 70% to 80%
D: The luminance ratio is less than 70%
[実施例1]
(i)偏光板
 市販の偏光板(日東電工社製、製品名「CWQ1463VCUHC」)を2枚用意し、第1の偏光板(偏光子)および第2の偏光板(偏光子)とした。
[Example 1]
(I) Polarizing plate Two commercially available polarizing plates (manufactured by Nitto Denko Corporation, product name “CWQ1463VCUHC”) were prepared and used as a first polarizing plate (polarizer) and a second polarizing plate (polarizer).
(ii)カバーシート
 市販のメタクリル樹脂シート(日東樹脂工業社製、製品名「フラットN-885」、厚み1.0mm)を用い、後述の液晶セルの表示領域に対応する部分を打ち抜いて開口部とした。
(Ii) Cover sheet Using a commercially available methacrylic resin sheet (manufactured by Nitto Resin Kogyo Co., Ltd., product name “Flat N-885”, thickness 1.0 mm), a portion corresponding to the display area of the liquid crystal cell described later is punched out It was.
(iii)液晶セル
 Century社製、製品名「plus one」(IPSモード)から液晶パネルを取出し、さらに液晶セルの上下に貼り付けられていた光学フィルムを取り除き、光学フィルム除去面を洗浄した。このようにして得られた液晶セルを用いた。
(Iii) Liquid crystal cell The liquid crystal panel was taken out from the product name “plus one” (IPS mode) manufactured by Century, and the optical film attached to the top and bottom of the liquid crystal cell was removed, and the optical film removal surface was washed. The liquid crystal cell thus obtained was used.
(iv)液晶表示装置の作製
 液晶セルの一方の面に、上記(ii)のカバーシートおよび上記(i)の偏光板(第2の偏光子)を、液晶セル側からこの順に貼り合わせた。カバーシートは開口部が液晶セルの表示領域に対応するよう貼り合わせた。偏光板(第2の偏光子)とカバーシートとは通常のアクリル系粘着剤により貼り合わせ、開口部を粘着剤で充填はしなかった。さらに、液晶セルの他方の面に上記(i)の偏光板(第1の偏光子)を貼り合わせた。ここで、第1の偏光子の吸収軸と第2の偏光子の吸収軸とが直交するようにして、それぞれの光学フィルムを貼り合わせた。さらに、上記(iii)の「plus one」から取り出したバックライトユニットを第1の偏光子の外側に組み込み、液晶表示装置を作製した。得られた液晶表示装置を上記(1)~(3)の評価に供した。結果を表1に示す。
(Iv) Production of liquid crystal display device The cover sheet of (ii) and the polarizing plate (second polarizer) of (i) were bonded in this order from the liquid crystal cell side to one surface of the liquid crystal cell. The cover sheet was bonded so that the opening corresponded to the display area of the liquid crystal cell. The polarizing plate (second polarizer) and the cover sheet were bonded together with a normal acrylic adhesive, and the opening was not filled with the adhesive. Further, the above polarizing plate (i) (first polarizer) was bonded to the other surface of the liquid crystal cell. Here, each optical film was bonded together so that the absorption axis of the first polarizer and the absorption axis of the second polarizer were orthogonal to each other. Further, the backlight unit taken out from “plus one” in (iii) above was incorporated outside the first polarizer to produce a liquid crystal display device. The obtained liquid crystal display device was subjected to the evaluations (1) to (3) above. The results are shown in Table 1.
[実施例2]
 第2の偏光子とカバーシートとの間に第1の光学補償層をさらに設け、かつ、カバーシートと液晶セルの間に第2の光学補償層をさらに設けたこと以外は実施例1と同様にして液晶表示装置を作製した。具体的には、下記のようにして作製した位相差フィルムを2枚用いて、第1の光学補償層および第2の光学補償層とした。ここで、第1の光学補償層の遅相軸と第2の偏光子の吸収軸とのなす角度が45°となるようにして、かつ、第1の光学補償層の遅相軸と第2の光学補償層の遅相軸とが実質的に直交するように貼り合わせた。得られた液晶表示装置を実施例1と同様の評価に供した。結果を表1に示す。
(第1の光学補償層および第2の光学補償層の作製)
 特開2014-26266号公報の実施例1に準じた方法で位相差フィルムを得た。得られた位相差フィルムのRe(550)は147nmであり、Nz係数は1.0であり、Re(450)/Re(550)は0.89であり、厚みは40μmであった。
[Example 2]
Example 1 except that a first optical compensation layer is further provided between the second polarizer and the cover sheet, and a second optical compensation layer is further provided between the cover sheet and the liquid crystal cell. Thus, a liquid crystal display device was produced. Specifically, two retardation films prepared as described below were used as the first optical compensation layer and the second optical compensation layer. Here, the angle formed by the slow axis of the first optical compensation layer and the absorption axis of the second polarizer is 45 °, and the slow axis of the first optical compensation layer and the second axis The optical compensation layer was bonded so that the slow axis thereof was substantially orthogonal. The obtained liquid crystal display device was subjected to the same evaluation as in Example 1. The results are shown in Table 1.
(Production of first optical compensation layer and second optical compensation layer)
A retardation film was obtained by a method according to Example 1 of JP-A-2014-26266. Re (550) of the obtained retardation film was 147 nm, the Nz coefficient was 1.0, Re (450) / Re (550) was 0.89, and the thickness was 40 μm.
[実施例3]
 カバーシートの開口部を粘着剤で充填したこと以外は実施例1と同様にして液晶表示装置を作製した。得られた液晶表示装置を実施例1と同様の評価に供した。結果を表1に示す。
[Example 3]
A liquid crystal display device was produced in the same manner as in Example 1 except that the opening of the cover sheet was filled with the adhesive. The obtained liquid crystal display device was subjected to the same evaluation as in Example 1. The results are shown in Table 1.
[実施例4]
 カバーシートの開口部を粘着剤で充填したこと以外は実施例2と同様にして液晶表示装置を作製した。得られた液晶表示装置を実施例1と同様の評価に供した。結果を表1に示す。
[Example 4]
A liquid crystal display device was produced in the same manner as in Example 2 except that the opening of the cover sheet was filled with the adhesive. The obtained liquid crystal display device was subjected to the same evaluation as in Example 1. The results are shown in Table 1.
[比較例1]
 第2の偏光子をカバーシートと液晶セルとの間に配置したこと、すなわち、カバーシートを最外層としたこと以外は実施例1と同様にして液晶表示装置を作製した。得られた液晶表示装置を実施例1と同様の評価に供した。結果を表1に示す。
[Comparative Example 1]
A liquid crystal display device was produced in the same manner as in Example 1 except that the second polarizer was disposed between the cover sheet and the liquid crystal cell, that is, the cover sheet was the outermost layer. The obtained liquid crystal display device was subjected to the same evaluation as in Example 1. The results are shown in Table 1.
[比較例2]
 市販の減光フィルタ(富士フイルム社製、製品名「ニュートラルデンシティフィルター ND-0.5」、透過率36%)をカバーシートの視認側にさらに設けたこと以外は比較例1と同様にして液晶表示装置を作製した。得られた液晶表示装置を実施例1と同様の評価に供した。結果を表1に示す。
[Comparative Example 2]
Liquid crystal as in Comparative Example 1, except that a commercially available neutral density filter (product name “Neutral Density Filter ND-0.5”, transmittance 36%, manufactured by FUJIFILM Corporation) was further provided on the viewing side of the cover sheet. A display device was produced. The obtained liquid crystal display device was subjected to the same evaluation as in Example 1. The results are shown in Table 1.
[比較例3]
 第3の偏光子をカバーシートの視認側にさらに設けたこと以外は比較例1と同様にして液晶表示装置を作製した。なお、第3の偏光子(偏光板)として、第1の偏光子(偏光板)および第2の偏光子(偏光板)と同じ偏光板を用いた。さらに、第3の偏光子は、その吸収軸が第2の偏光子の吸収軸と実質的に平行となるようにして貼り合わせた。得られた液晶表示装置を実施例1と同様の評価に供した。結果を表1に示す。
[Comparative Example 3]
A liquid crystal display device was produced in the same manner as in Comparative Example 1 except that a third polarizer was further provided on the viewing side of the cover sheet. Note that the same polarizer as the first polarizer (polarizer) and the second polarizer (polarizer) was used as the third polarizer (polarizer). Further, the third polarizer was bonded so that the absorption axis thereof was substantially parallel to the absorption axis of the second polarizer. The obtained liquid crystal display device was subjected to the same evaluation as in Example 1. The results are shown in Table 1.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
 表1から明らかなように、本発明の実施例の液晶表示装置は、物理的段差が解消され、かつ、視覚的段差と表示画面の明るさとのバランスに優れていた。カバーシートを視認側最外層とした比較例1の液晶表示装置は、表示画面は明るいものの、物理的段差は解消されず、かつ、視覚的段差が視認性に影響を与えるほどに劣悪であった。減光フィルタを用いた比較例2の液晶表示装置は、物理的段差は解消されたものの、表示画面の明るさおよび視覚的段差のいずれもが不良であり、特に表示画面の明るさは劣悪であった。カバーシートと液晶セルとの間にさらに偏光子を設けた比較例3の液晶表示装置は、表示画面の明るさが不良であった。さらに、実施例1と実施例3、および、実施例2と実施例4を比較すると明らかなように、開口部を粘着剤で充填することにより明るさをさらに改善できることがわかる。 As is apparent from Table 1, the liquid crystal display device of the example of the present invention was excellent in the balance between the visual step and the brightness of the display screen, while eliminating the physical step. In the liquid crystal display device of Comparative Example 1 in which the cover sheet is the outermost layer on the viewing side, although the display screen is bright, the physical level difference is not eliminated, and the visual level difference is poor enough to affect the visibility. . In the liquid crystal display device of Comparative Example 2 using the neutral density filter, although the physical level difference is eliminated, both the brightness of the display screen and the visual level difference are poor, and the brightness of the display screen is particularly poor. there were. In the liquid crystal display device of Comparative Example 3 in which a polarizer was further provided between the cover sheet and the liquid crystal cell, the brightness of the display screen was poor. Further, as is apparent from a comparison between Example 1 and Example 3 and Example 2 and Example 4, it can be seen that the brightness can be further improved by filling the opening with an adhesive.
 本発明の液晶表示装置は、携帯情報端末(PDA),携帯電話,時計,デジタルカメラ,携帯ゲーム機などの携帯機器、パソコンモニター,ノートパソコン,コピー機などのOA機器、ビデオカメラ,液晶テレビ,電子レンジ、AV機器などの家庭用電気機器、バックモニター,カーナビゲーションシステム用モニター,カーオーディオなどの車載用機器、商業店舗用インフォメーション用モニターなどの展示機器、監視用モニターなどの警備機器、介護用モニター,医療用モニターなどの介護・医療機器などの各種用途に用いることができる。特に、本発明の液晶表示装置は、構造物に埋め込む形態で好適に用いることができる。 The liquid crystal display device of the present invention includes portable information terminals (PDAs), mobile phones, watches, digital cameras, portable game devices such as portable game machines, OA devices such as personal computer monitors, notebook computers, copy machines, video cameras, liquid crystal televisions, Home appliances such as microwave ovens and AV equipment, back monitors, monitors for car navigation systems, in-vehicle devices such as car audio, display equipment such as information monitors for commercial stores, security equipment such as monitoring monitors, nursing care It can be used for various applications such as nursing care and medical equipment such as monitors and medical monitors. In particular, the liquid crystal display device of the present invention can be suitably used in a form embedded in a structure.
 10  液晶セル
 20  第1の偏光子
 40  カバーシート
 50  第1の光学補償層
 60  第2の偏光子
 70  第2の光学補償層
 80  粘着剤層
100  液晶表示装置
 
DESCRIPTION OF SYMBOLS 10 Liquid crystal cell 20 1st polarizer 40 Cover sheet 50 1st optical compensation layer 60 2nd polarizer 70 2nd optical compensation layer 80 Adhesive layer 100 Liquid crystal display device

Claims (6)

  1.  液晶セルと、
     該液晶セルの背面側に配置された第1の偏光子と、
     該液晶セルの視認側に配置された、該液晶セルの表示領域に対応した位置に透過部を有するカバーシートと、
     該カバーシートの視認側に該透過部を覆うように配置された第2の偏光子と、を備え、
     該第1の偏光子の吸収軸方向と該第2の偏光子の吸収軸方向とが実質的に直交している、
     液晶表示装置。
    A liquid crystal cell;
    A first polarizer disposed on the back side of the liquid crystal cell;
    A cover sheet disposed on the viewing side of the liquid crystal cell and having a transmission part at a position corresponding to the display area of the liquid crystal cell;
    A second polarizer disposed on the viewing side of the cover sheet so as to cover the transmission part,
    The absorption axis direction of the first polarizer and the absorption axis direction of the second polarizer are substantially orthogonal,
    Liquid crystal display device.
  2.  前記カバーシートと前記第2の偏光子との間に、Re(550)が100nm~180nmである第1の光学補償層をさらに備え、かつ、該カバーシートと前記液晶セルとの間に、Re(550)が100nm~180nmである第2の光学補償層をさらに備える、請求項1に記載の液晶表示装置。 A first optical compensation layer having Re (550) of 100 nm to 180 nm is further provided between the cover sheet and the second polarizer, and between the cover sheet and the liquid crystal cell, Re The liquid crystal display device according to claim 1, further comprising a second optical compensation layer in which (550) is 100 nm to 180 nm.
  3.  前記第1の光学補償層の遅相軸方向と前記第2の偏光子の吸収軸とのなす角度が35°~55°または125°~145°であり、かつ、該第1の光学補償層の遅相軸方向と前記第2の光学補償層の遅相軸方向とが実質的に直交している、請求項2に記載の液晶表示装置。 The angle formed between the slow axis direction of the first optical compensation layer and the absorption axis of the second polarizer is 35 ° to 55 ° or 125 ° to 145 °, and the first optical compensation layer The liquid crystal display device according to claim 2, wherein a slow axis direction of the second optical compensation layer and a slow axis direction of the second optical compensation layer are substantially orthogonal to each other.
  4.  前記第1の光学補償層および前記第2の光学補償層が、Re(450)<Re(550)の関係を満たす、請求項2または3に記載の液晶表示装置。 4. The liquid crystal display device according to claim 2, wherein the first optical compensation layer and the second optical compensation layer satisfy a relationship of Re (450) <Re (550).
  5.  前記カバーシートの前記透過部が開口部であり、該開口部が粘着剤で充填されている、請求項1から4のいずれかに記載の液晶表示装置。 5. The liquid crystal display device according to claim 1, wherein the transmission part of the cover sheet is an opening, and the opening is filled with an adhesive.
  6.  前記粘着剤の屈折率が1.30~1.70である、請求項5に記載の液晶表示装置。
     
    6. The liquid crystal display device according to claim 5, wherein the adhesive has a refractive index of 1.30 to 1.70.
PCT/JP2017/014641 2016-04-18 2017-04-10 Liquid crystal display device WO2017183499A1 (en)

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EP17785839.6A EP3447569A4 (en) 2016-04-18 2017-04-10 Liquid crystal display device
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