KR20220012421A - Liquid Crystal Display Device - Google Patents

Abstract

A liquid crystal display device having a level difference between a display screen and an outermost surface, which is difficult to recognize, and capable of realizing bright display. A liquid crystal display device of the present invention includes a liquid crystal cell; a first polarizer disposed on the rear side of the liquid crystal cell; a second polarizer disposed on the viewing side of the liquid crystal cell; a cover sheet having a transmissive portion at a position corresponding to the display area of the liquid crystal cell disposed on the viewer side of the second polarizer; a first optical compensation layer having a Re (550) of 100 nm to 180 nm arranged to cover the transmissive part on the viewing side of the cover sheet; and a third polarizer disposed on the viewing side of the first optical compensation layer. An angle between the slow axis direction of the first optical compensation layer and the absorption axis direction of the third polarizer is 35° to 55° or 125° to 145°.

Description

Liquid Crystal Display Device

The present invention relates to a liquid crystal display device.

BACKGROUND ART Liquid crystal displays are used in a wide range of applications including TVs, smart phones, PC monitors, and digital cameras, and the uses are further expanding. As a result, depending on the purpose of the liquid crystal display device, the liquid crystal display device is incorporated in various structures is adopted. Specific examples of such uses include operation information screens in rail vehicles (for example, information on the next station of passenger vehicles), display units of various instruments and navigation systems installed on the dashboard or console of automobiles, various instruments in the cockpit of airplanes and hospitals; A monitor installed in a guard room or a battle command post may be mentioned. In such a form, a cover sheet having a transmissive portion corresponding to the display area of the liquid crystal display device may be disposed on the viewing side of the liquid crystal display device as necessary for protection and/or design of the liquid crystal display device. In such a form, there is a difference in level between the uppermost surface of the portion incorporating the liquid crystal display device (for example, the outermost surface of the case, wall, monitor desk, or cover sheet arranged as necessary) and the display screen. , and depending on the use and/or the situation, the level difference may affect the visibility. In order to make it difficult to recognize the level difference, a technique for disposing a photosensitive filter on the viewer side has been proposed (Patent Document 1). However, in this technology, although it is difficult to recognize a step, there is a problem in that the display screen itself becomes dark.

Japanese Patent No. 5877433 Specification

The present invention has been made in order to solve the above conventional problems, and an object thereof is a liquid crystal display having a level difference between the display screen and the outermost surface, the level difference being difficult to recognize and capable of realizing a bright display. to provide the device.

A liquid crystal display device of the present invention includes a liquid crystal cell; a first polarizer disposed on the rear side of the liquid crystal cell; a second polarizer disposed on the viewer side of the liquid crystal cell; a cover sheet having a transmissive portion at a position corresponding to the display area of the liquid crystal cell disposed on the viewer side of the second polarizer; a first optical compensation layer having a Re (550) of 100 nm to 180 nm disposed to cover the transmission part on the viewing side of the cover sheet; and a third polarizer disposed on the viewer side of the first optical compensation layer. An angle between the slow axis direction of the first optical compensation layer and the absorption axis direction of the third polarizer is 35° to 55° or 125° to 145°.

In one embodiment, the liquid crystal display device further includes a second optical compensation layer having Re(550) of 100 nm to 180 nm between the cover sheet and the second polarizer.

In one embodiment, the polarization direction of the circularly polarized light obtained from the said 1st optical compensation layer and the said 3rd polarizer and the polarization direction of the circularly polarized light obtained from the said 2nd polarizer and the said 2nd optical compensation layer are the same direction.

In one embodiment, the first optical compensation layer and the second optical compensation layer satisfy the relation Re(450)<Re(550).

In one embodiment, the permeable portion of the cover sheet is an opening, and the opening is filled with an adhesive.

In one embodiment, the refractive index of the said adhesive is 1.30-1.70.

According to the present invention, in a liquid crystal display having a step difference between the display screen and the outermost surface, by arranging a polarizer and a so-called λ/4 plate on the viewing side of the step, it is difficult to recognize the step while maintaining the brightness of the display screen. Thus, visibility can be improved.

1 is a schematic cross-sectional view of a liquid crystal display device according to an embodiment of the present invention.
2 is a schematic cross-sectional view of a liquid crystal display device according to another embodiment of the present invention.
3 is a schematic cross-sectional view of a liquid crystal display device according to still another embodiment of the present invention.
4 is a schematic cross-sectional view of a liquid crystal display device according to still another embodiment of the present invention.
5 is a schematic cross-sectional view of a liquid crystal display device according to still another embodiment of the present invention.
6 is a schematic cross-sectional view of a liquid crystal display device according to still another embodiment of the present invention.
7 is a schematic cross-sectional view of a liquid crystal display device according to still another embodiment of the present invention.
8 is a schematic cross-sectional view of a liquid crystal display device according to still another embodiment of the present invention.
9 is a schematic cross-sectional view of a liquid crystal display device according to still another embodiment of the present invention.
10 is a schematic cross-sectional view of a liquid crystal display device according to still another embodiment of the present invention.

EMBODIMENT OF THE INVENTION Hereinafter, although embodiment of this invention is described with reference to drawings, this invention is not limited to these embodiment.

(Definition of terms and symbols)

Definitions of terms and symbols in the present 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, slow axis direction), "ny" is the refractive index in the direction orthogonal to the slow axis in the plane (ie, fast axis direction), "nz" is It is the refractive index in the thickness direction.

(2) In-plane phase difference (Re)

"Re(λ)" is the in-plane retardation measured with light having a wavelength of λ nm at 23°C. Re(λ) can be obtained from the formula: Re=(nx-ny)×d when the thickness of the layer (film) is d(nm). For example, "Re(550)" is the in-plane retardation measured with light having a wavelength of 550 nm at 23°C.

(3) retardation in thickness direction (Rth)

"Rth(λ)" is the phase difference in the thickness direction measured with light having a wavelength of λ nm at 23°C. Rth(λ) can be obtained from the formula: Rth=(nx-nz)×d when the thickness of the layer (film) is d(nm). For example, "Rth (550)" is the retardation in the thickness direction measured with light having a wavelength of 550 nm at 23°C.

(4) Nz coefficient

The Nz coefficient can be obtained from Nz=Rth/Re.

(5) substantially orthogonal or parallel

The expressions "substantially orthogonal" and "approximately orthogonal" include the case where the angle formed by two directions is 90°±10°, preferably 90°±7°, more preferably 90°±5° to be. The expressions "substantially parallel" and "approximately parallel" include the case where the angle between two directions is 0°±10°, preferably 0°±7°, more preferably 0°±5° to be. In addition, when simply referred to as "orthogonal" or "parallel" in the present specification, it shall include a substantially perpendicular or substantially parallel state.

A. Overall configuration of liquid crystal display device

1 is a schematic cross-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 rear side of the liquid crystal cell 10 , and a second polarizer 30 disposed on a viewer side of the liquid crystal cell 10 . and the cover sheet 40 disposed on the viewer side of the second polarizer 30 , the first optical compensation layer 50 disposed on the viewer side of the cover sheet 40 , and the first optical compensation layer 50 . and a third polarizer 60 disposed on the viewer side of The cover sheet 40 has a transmissive portion 42 at a position corresponding to the display area of the liquid crystal cell 10 . The transmissive portion includes a physically transmissive portion (eg, an opening) and an optically transmissive portion (eg, a transparent portion). In the illustrated example, an opening is shown. The first optical compensation layer 50 (and consequently the third polarizer 60 ) is arranged to cover the transmissive portion 42 of the cover sheet 40 . According to the embodiment of the present invention, the third polarizer is disposed on the outermost side so as to cover the transmissive portion of the cover sheet, thereby making it difficult to recognize the level difference between the device outermost surface and the display screen, and as a result, the liquid crystal display device visibility can be improved. In more detail, the level difference can be difficult to recognize due to the transmittance peculiar to the polarizer, and the polarizer can efficiently transmit polarized light in a predetermined direction, so that the brightness of the display screen compared to the photosensitive filter that reduces the light as a whole. can keep In addition, when the permeable portion of the cover sheet is an opening, the uppermost surface is flattened by covering the opening so that it is difficult to recognize the level difference. Hereinafter, "making it difficult to recognize a step" is sometimes referred to as "reducing a visual step".

The first optical compensation layer 50 has Re(550) of 100 nm to 180 nm, preferably 110 nm to 170 nm, and more preferably 120 nm to 160 nm. The angle between the slow axis direction of the first optical compensation layer 50 and the absorption axis direction of the third polarizer 60 is 35° to 55°, preferably 38° to 52°, more preferably 42° -48°, more preferably about 45°. Alternatively, the angle is 125° to 145°, preferably 128° to 142°, more preferably 132° to 138°, and still more preferably about 135°. If the angle is within such a range, an excellent circular polarization function and an antireflection function can be realized by the combination of the first optical compensation layer and the third polarizer. As a result, it is possible to significantly reduce the visual step while maintaining the practically acceptable brightness of the display screen. That is, compared to the case where the visual step is reduced by reducing the transmittance by using, for example, a photosensitive filter, the visual step may be reduced without lowering the transmittance. The first optical compensation layer and the third polarizer may be introduced into the liquid crystal display device as separate members, respectively, or may be introduced into the liquid crystal display device as a laminate of the first optical compensation layer and the third polarizer (that is, a circularly polarizing plate). .

In the liquid crystal display according to the embodiment of the present invention, the absorption axis direction of the second polarizer 30 and the absorption axis direction of the third polarizer 60 may have any suitable angle depending on the purpose. Further, 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 30 are substantially orthogonal or parallel, typically substantially orthogonal, have.

The liquid crystal display device according to the embodiment of the present invention may be a so-called O-mode or a so-called E-mode. "O-mode liquid crystal display device" means that the absorption axis direction of the polarizer arranged on the light source side of the liquid crystal cell and the initial alignment direction of the liquid crystal cell are substantially parallel. "E-mode liquid crystal display device" means that the absorption axis direction of the 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. The "initial alignment direction of the liquid crystal cell" refers to a direction in which the in-plane refractive index of the liquid crystal layer generated as a result of alignment of liquid crystal molecules included in the liquid crystal layer in the absence of an electric field (ie, slow axis direction) is maximized.

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 101 further includes a second optical compensation layer 70 between the second polarizer 30 and the cover sheet 40 . The second optical compensation layer 70 has Re(550) of 100 nm to 180 nm, preferably 110 nm to 170 nm, and more preferably 120 nm to 160 nm. The angle between the slow axis direction of the second optical compensation layer 70 and the absorption axis direction of the second polarizer 30 is 35° to 55°, preferably 38° to 52°, more preferably 42° -48°, more preferably about 45°. Alternatively, the angle is 125° to 145°, preferably 128° to 142°, more preferably 132° to 138°, and still more preferably about 135°. 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 circularly polarized light obtained by the first optical compensation layer 50 and the third polarizer 60 . The polarization direction and the polarization direction of the circularly polarized light obtained by the second polarizer 30 and the second optical compensation layer 70 may be set to be in the same direction. Specifically, when the circularly polarized light obtained by the first optical compensation layer 50 and the third polarizer 60 is left circularly polarized light, the degree of circular polarization obtained by the second polarizer 30 and the second optical compensation layer 70 is The angle of the slow axis is adjusted to be left circularly polarized; When the circularly polarized light obtained by the first optical compensation layer 50 and the third polarizer 60 is right circularly polarized light, the circularly polarized light obtained by the second polarizer 30 and the second optical compensation layer 70 is also right circularly polarized light The angle of the slow axis may be adjusted as much as possible. For example, when the absorption axis direction of the third polarizer 60 and the absorption axis direction of the second polarizer 30 are respectively 0° and the slow axis direction of the first optical compensation layer 50 is 45°, the second optical The direction of the slow axis of the compensation layer 70 may be set to -45°. By additionally providing such a second optical compensation layer, the balance between the brightness of the display screen and the visual step may be improved.

In the embodiment of FIG. 2 , the constituent materials, optical properties, and thicknesses 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 satisfy the relationship of Re(450)<Re(550), respectively. When the optical compensation layer satisfies such a relationship, an excellent antireflection function can be realized, and as a result, a visual step can be reduced.

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 , an 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 first optical compensation layer 50 . With such a configuration, since the air layer formed by the opening is excluded, reflection and/or refraction at the layer interface can be suppressed. As a result, it is possible to further improve the brightness of the display screen and further significantly reduce the visual step. In addition, when the cover sheet has an optically transmissive portion (transparent portion), the transparent portion may be composed of an adhesive. Preferably the refractive index of an adhesive is 1.30-1.70, More preferably, it is 1.40-1.60, More preferably, it is 1.45-1.55. 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 level difference can be further improved.

5 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 104 , the cover sheet 40 is curved, and the first optical compensation layer 50 and the third polarizer 60 are curved along the cover sheet 40 . The cover sheet 40 may be curved in any suitable shape. Specifically, the curve may be curved so that the viewer side is convex, or the curve may be curved so that the viewer side is concave. Further, the cover sheet 40 may be curved in any direction in the plane as an axis. In addition, the whole may be curving, and only a part may be curving. Further, like the liquid crystal display device 105 shown in FIG. 6 , the liquid crystal cell 10 , the first polarizer 20 , and the second polarizer 30 may be curved along the cover sheet 40 . 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 a large commercial value.

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 , an 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 first optical compensation layer 50 . In addition, in the liquid crystal display device 106 , the cover sheet 40 is curved, and the adhesive fills the gap between the cover sheet 40 and the second polarizer 30 generated by the curved cover sheet 40 . is charging If it is such a structure, the fall of the mechanical strength accompanying the curvature of the cover sheet 40 can be suppressed.

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 rear side of the liquid crystal cell 10A, and a second polarizer 30A disposed on the viewer side of the liquid crystal cell 10A, and , the liquid crystal cell 10B and the first polarizer 20B disposed on the rear side of the liquid crystal cell 10B, the second polarizer 30B disposed on the viewer side of the liquid crystal cell 10B, and the second polarizer 30A and 30B), the cover sheet 40 disposed on the viewer side, the first optical compensation layer 50 disposed on the viewer side of the cover sheet 40, and the first optical compensation layer 50 disposed on the viewer side A third polarizer 60 is provided. The cover sheet 40 of the liquid crystal display device 107 is provided with a first transmission portion 42A at a position corresponding to the display area of the liquid crystal cell 10A, and is disposed at a position corresponding to the display area of the liquid crystal cell 10B. 2 The transmission part 42B is provided. The liquid crystal display device 107 has two display screens corresponding to each liquid crystal cell, and arranges the third polarizer on the outermost surface side so as to cover the two transmissive portions of the cover sheet, so that the device outermost surface and the two display screens are formed. By making it difficult to recognize the level difference between , visibility on the two display screens can be improved. In addition, although a 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 may have three or more display screens and corresponding liquid crystal cells.

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 this embodiment has two display screens similarly to the liquid crystal display device 107 . Further, in the present embodiment, the cover sheet 40 is bent at the bent portion 90 between the transmission portion 42A and the transmission portion 42B, and the first optical compensation layer 50 and the third polarizer 60 are It is bent along the cover sheet 40 . Accordingly, the liquid crystal display 108 can display images in different directions using the two display screens. Further, 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 with each bent portion therebetween.

The liquid crystal display according to the embodiment of the present invention may be included (typically, built-in) in various structures to be used. Specific examples of structures include architectural structures (e.g., walls of guard rooms or combat command posts), rail vehicles (e.g., walls above doors), automobiles (e.g., dashboards, consoles), airplanes (e.g., cockpits), consumer electronics and AV equipment. can

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 suitable other member (eg, a diffusion sheet, a prism sheet).

The liquid crystal display device according to the embodiment of the present invention may further include any appropriate other members. For example, another optical compensation layer (retardation film) may be further disposed. The optical properties, number, combination, arrangement position, and the like of the other optical compensation layers can be appropriately selected depending on the purpose and desired optical properties and the like. Further, 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 layers may be appropriately selected depending on the purpose.

The above embodiments may be appropriately combined, and the structures in the above embodiments may be substituted with optically equivalent structures. For example, as shown in FIG. 4 , the embodiment of FIG. 2 and the embodiment of FIG. 3 may be combined. Specifically, the liquid crystal display 103 of FIG. 4 includes a combination of the second optical compensation layer 70 and an adhesive filling the opening of the cover sheet. Note that, for example, the opening of the cover sheet in the illustrated example may be replaced with a transparent portion. Further, for example, as shown in FIG. 10 , the embodiment of FIG. 6 and the embodiment of FIG. 8 may be combined. 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 a display area of the liquid crystal cell 10A. A first transmitting portion 42A is provided at a position corresponding to , and a second transmitting portion 42B is provided at a position corresponding to the display area of the liquid crystal cell 10B.

For matters not described in this specification, a configuration of a liquid crystal display device that is well-known and commonly used in the art may be employed.

Hereinafter, each member and optical film which comprise a liquid crystal display device are demonstrated.

B. Liquid crystal cell

The liquid crystal cell 10 has 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, and a switching element for controlling the electro-optical properties of the liquid crystal is provided on the other substrate, and a scanning line and a source signal for giving a gate signal to the switching element. A signal line to be applied, a pixel electrode, and a counter electrode are provided. The gap (cell gap) of the substrate is controlled by a spacer or the like. An alignment film made of, for example, polyimide may be provided on the side of the substrate in contact with the liquid crystal layer.

In one embodiment, the liquid crystal layer includes liquid crystal molecules aligned in a homeotropic arrangement in the absence of an electric field. "Liquid crystal molecules aligned in a homeotropic arrangement" refers to a state in which the alignment vector of the liquid crystal molecules is aligned perpendicular to the plane of the substrate as a result of the interaction between the alignment-treated 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 a driving mode using a liquid crystal layer exhibiting such a three-dimensional refractive index is a vertical alignment (VA) mode. The VA mode includes a multi-domain VA (MVA) mode.

In another embodiment, the liquid crystal layer contains liquid crystal molecules aligned in a homogeneous arrangement in the absence of an electric field. "Liquid crystal molecules aligned in a homogeneous arrangement" refers to a state in which alignment vectors of liquid crystal molecules are parallel and uniformly aligned with respect to the substrate plane as a result of the interaction between the alignment-treated substrate and liquid crystal molecules. Such a liquid crystal layer (as a result, a liquid crystal cell) typically exhibits a three-dimensional refractive index of nx>ny=nz. Representative examples of the driving mode using the liquid crystal layer exhibiting such a three-dimensional refractive index include an in-plane switching (IPS) mode, a fringe field switching (FFS) mode, and the like. In addition, the IPS mode includes a super-in-plane switching (S-IPS) mode and an advanced super-in-plane switching (AS-IPS) mode employing a V-shaped electrode or a zigzag electrode or the like. In addition, 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 or the like.

C. Polarizer

Any suitable polarizer may be employed as the first polarizer, the second polarizer, and the third polarizer (hereinafter, collectively referred to as simply a polarizer). For example, a single-layered resin film may be sufficient as the resin film which forms a polarizer, and the laminated body of two or more layers may be sufficient as it.

As a specific example of a polarizer composed of a single-layer resin film, a polyvinyl alcohol (PVA)-based film, a partially formalized PVA-based film, an ethylene/vinyl acetate copolymer-based partially saponified film, etc. polyene-based oriented films, such as those subjected to the dyeing treatment and stretching treatment with the dichroic substance, dehydration treatment products of PVA, and dehydrochloric acid treatment products of polyvinyl chloride. Preferably, a polarizer obtained by dyeing a PVA-based film with iodine and uniaxially stretching from the viewpoint of excellent optical properties is used.

The dyeing with iodine is made by, for example, immersing a PVA-based film in an aqueous iodine solution. Preferably the draw ratio of the said uniaxial stretching is 3-7 times. Extending|stretching may be performed after a dyeing process, and may be performed, dyeing|staining. Moreover, you may dye|dye after extending|stretching. A swelling process, a crosslinking process, a washing process, a drying process, etc. are given to a PVA-type film as needed. For example, by immersing the PVA-based film in water and washing with water before dyeing, it is possible not only to wash the surface of the PVA-based film from contamination and anti-blocking agent, but also to swell the PVA-based film to prevent staining of dyeing.

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 within such a range, it can be excellent in durability under high temperature and high humidity.

The polarizer preferably exhibits absorption dichroism at any wavelength of 380 nm to 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 still more preferably 99.9% or more.

A protective layer (not shown) may be provided on at least one surface of each of the first polarizer 20 , the second polarizer 30 , and the third polarizer 60 . That is, the first polarizer 20 , the second polarizer 30 , and the third polarizer 60 may each be incorporated in the liquid crystal display device as a polarizing plate. In addition, the third polarizer 60 may be included in the liquid crystal display device as a circularly polarizing plate as described above.

The protective layer is formed of any suitable film that can be used as a protective layer of a polarizer. Specific examples of the material used as the main component of the film include cellulose resins such as triacetyl cellulose (TAC), polyester, polyvinyl alcohol, polycarbonate, polyamide, polyimide, polyethersulfone, and polysulfone. Transparent resins, such as a phone type, polystyrene type, polynorbornene type, polyolefin type, (meth)acrylic type, acetate type, etc. are mentioned. Moreover, thermosetting resins, such as (meth)acrylic type, a urethane type, a (meth)acryl urethane type, an epoxy type, a silicone type, or ultraviolet curable resin, etc. are mentioned. In addition, for example, glass-type polymers, such as a siloxane-type polymer, are mentioned. Moreover, the polymer film of Unexamined-Japanese-Patent No. 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 a nitrile group in the side chain can be used, for example, isobutene and N- and a resin composition comprising an alternating copolymer composed of methylmaleimide and an acrylonitrile/styrene copolymer. The polymer film may be, for example, an extrusion molding of the resin composition.

The thickness of the protective layer is typically 5 mm or less, preferably 1 mm or less, more preferably 1 µm to 500 µm, still more preferably 5 µm to 150 µm. In addition, when surface treatment is performed, the thickness of a protective layer is the thickness including the thickness of a surface treatment layer.

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 , the second polarizer 30 and/or the third polarizer 60 , the inner protective layer is optically It is preferably isotropic. "It is optically isotropic" means that the in-plane retardation Re(550) is 0 nm to 10 nm, and the retardation Rth(550) in the thickness direction is -10 nm to +10 nm. The inner protective layer may be made of any suitable material as long as it is optically isotropic. The material may be appropriately selected, for example, from the materials described above with respect to the protective layer.

The thickness of the inner protective layer is preferably 5 µm to 200 µm, more preferably 10 µm to 100 µm, still more preferably 15 µm to 95 µm.

D. Cover sheet

Typically, when a liquid crystal display device is included in a structure and used, the cover sheet 40 may be installed to protect the liquid crystal display device and/or according to a design request. Accordingly, the cover sheet 40 typically has the transmissive portion 42 corresponding to the display area of the liquid crystal cell so as not to interfere with the display function of the liquid crystal display device. The transmissive part includes a physically transmissive part (eg, an opening) and an optically transmissive part (eg, a transparent part) as described above.

The cover sheet may be constructed of any suitable material. A typical example of the constituent material is resin. This is because it has suitable strength as a cover sheet, and it is easy to form into a desired shape and form an opening. Specific examples of the resin include polyarylate, polyamide, polyimide, polyester, polyarylether ketone, polyamideimide, polyesterimide, polyvinyl alcohol, polyfumaric acid ester, polyethersulfone, polysulfone, norbornene resin, poly A carbonate resin, a cellulose resin, and a polyurethane are mentioned. These resins may be used independently and may be used in combination.

The cover sheet has light-shielding properties in one embodiment. Light-shielding property can be imparted by blending a light-shielding material (eg, carbon black) with the resin at the time of molding the cover sheet. In the embodiment in which the cover sheet has an opening, typically the entire cover sheet except for the opening has light-shielding properties. In the embodiment in which the cover sheet has a transparent portion, typically the entire cover sheet except for the transparent portion has light-shielding properties. In this case, it is good to use the resin which mix|blended the light-shielding material in parts other than a transparent part.

The thickness of the cover sheet is preferably 0.1 mm to 5 mm, more preferably 0.3 mm to 3 mm. With such a thickness, strength suitable as a protective member of a liquid crystal display device can be realized. According to the present invention, as described above, a physical step that may occur due to such a thickness of the cover sheet can be eliminated, and a visual step can be remarkably reduced.

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, and more preferably 120 nm to 160 nm. If the in-plane retardation of the first optical compensation layer is within this range, the slow axis direction of the first optical compensation layer is 35° to 55° (in particular, about 45°) or 125° with respect to the absorption axis direction of the third polarizer as described above. Excellent circular polarization function and antireflection function can be realized by setting the angle to form an angle of ° to 145 ° (in particular, about 135 °). As a result, it is possible to significantly reduce the visual step while maintaining the practically acceptable brightness of the display screen.

The first optical compensation layer typically has a refractive index characteristic of 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, still more preferably 0.5 to 1.3. By satisfying such a relationship, more excellent antireflection properties can be achieved.

The first optical compensation layer may exhibit an inverse dispersion wavelength characteristic in which the phase difference value increases with the wavelength of the measurement light, or a positive wavelength dispersion characteristic in which the phase difference value decreases with the wavelength of the measurement light, and the phase difference value is at the wavelength of the measurement light You may exhibit flat wavelength dispersion characteristic which hardly changes even by this. The first optical compensation layer preferably exhibits an anti-dispersion wavelength characteristic. By exhibiting such a characteristic, the antireflection function can be realized over a predetermined wavelength band only with the first optical compensation layer without additionally using a so-called λ/2 plate. In this case, the in-plane retardation of the first optical compensation layer satisfies the relation 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. In addition, the in-plane retardation of the first optical compensation layer preferably satisfies the relation 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 suitable resin capable of realizing the above properties. Examples of the resin for forming the retardation film include polyarylate, polyamide, polyimide, polyester, polyarylether ketone, polyamideimide, polyesterimide, polyvinyl alcohol, polyfumaric acid ester, polyethersulfone, polysulfone. , norbornene resin, polycarbonate resin, cellulose resin, and polyurethane. These resins may be used independently and may be used in combination. Preferably, it is a polyarylate, norbornene resin, or a polycarbonate resin.

The polyarylate is preferably represented by the following formula (I).

In formula (I), A and B each represent a substituent, and are a halogen atom, a C1-C6 alkyl group, and a substituted or unsubstituted aryl group, A and B may be same or different. a and b represent the corresponding substitution numbers of A and B, and are an integer of 1-4, respectively. D is a covalent bond, a CH ₂ group, a C(CH ₃ ) ₂ group, a C(CZ ₃ ) ₂ group (wherein Z is a halogen atom), a CO group, an O atom, an S atom, an SO ₂ group, Si(CH ₂ CH ₃ ) ₂ group, N(CH ₃ ) group. R1 is a C1-C10 linear or branched alkyl group, or a substituted or unsubstituted aryl group. R2 is a C2-C10 linear or branched alkyl group, 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.

The norbornene-based resin is a resin polymerized using a norbornene-based monomer as a polymerization unit. Examples of the norbornene-based monomer include norbornene and its alkyl and/or alkylidene substituents, such as 5-methyl-2-norbornene, 5-dimethyl-2-norbornene, 5-ethyl-2-norbornene, 5 -Butyl-2-norbornene, 5-ethylidene-2-norbornene, etc. polar group substitution products, such as these halogens; dicyclopentadiene, 2,3-dihydrodicyclopentadiene, and the like; Dimethanooctahydronaphthalene, its alkyl and/or alkylidene substituents and polar group substituents such as halogen, for example, 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-octahydronaphthalene, 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; tetramers of cyclopentadiene, such as 4,9:5,8-dimethano-3a,4,4a,5,8,8a,9,9a-octahydro-1H-benzoindene, 4, 11:5,10:6,9-trimethano-3a,4,4a,5,5a,6,9,9a,10,10a,11,11a-dodecahydro-1H-cyclopentaanthracene, etc. can The norbornene-based resin may be a copolymer of a norbornene-based monomer and another monomer.

As the polycarbonate resin, any suitable polycarbonate resin can be used as long as the effect of the present invention can be obtained. Preferably, the polycarbonate resin has a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and an alicyclic diol, alicyclic dimethanol, di, tri or polyethylene and a structural unit derived from at least one dihydroxy compound selected from the group consisting of glycol, and alkylene glycol or spiroglycol. Preferably, the polycarbonate resin has 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 alicyclic dimethanol and/or di; a structural unit derived from 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 are included. Polycarbonate resin may contain the structural unit derived from another dihydroxy compound as needed. In addition, the detail of the polycarbonate resin which can be preferably used for this invention is described in, for example, Japanese Unexamined-Japanese-Patent No. 2014-10291 and Unexamined-Japanese-Patent No. 2014-26266, The said description is taken in here as a reference.

It is preferable that the glass transition temperature of the said polycarbonate resin is 110 degreeC or more and 180 degrees C or less, More preferably, they are 120 degrees C or more and 165 degrees C or less. When the glass transition temperature is excessively low, heat resistance tends to deteriorate, there is a possibility of causing a dimensional change after film forming, and the image quality of the obtained liquid crystal display device may be lowered. When the glass transition temperature is excessively high, the molding stability at the time of film forming may deteriorate, and the transparency of the film may be impaired. In addition, a glass transition temperature can be calculated|required according to JISK7121 (1987).

The molecular weight of the polycarbonate resin may be expressed as reduced viscosity. The reduced viscosity is measured by using methylene chloride as a solvent, precisely preparing the polycarbonate concentration to 0.6 g/dL, and using an Uberode viscosity tube at a temperature of 20.0 ° C ± 0.1 ° C. As for the lower limit of reduced viscosity, 0.30 dL/g is preferable normally, More preferably, it is 0.35 dL/g or more. As for the upper limit of reduced viscosity, 1.20 dL/g is preferable normally, More preferably, it is 1.00 dL/g, More preferably, it is 0.80 dL/g. When the reduced viscosity is smaller than the lower limit, a problem may arise in which the mechanical strength of the molded article becomes small. On the other hand, when a reduced viscosity is larger than the said upper limit, the fluidity|liquidity at the time of shaping|molding may fall, and the problem that productivity and a moldability fall may arise.

The retardation film is typically produced by stretching a resin film in at least one direction.

Any suitable method may be employed as a method for forming the resin film. For example, a melt extrusion method (eg, T-die molding method), a cast coating method (eg, a casting method), a calender molding method, a hot press method, a co-extrusion method, a co-melt method, a multilayer extrusion method, an inflation molding method, etc. are mentioned. Preferably, the T-die forming method, the casting method and the inflation forming method are used.

The thickness of the resin film (unstretched film) may be set to any appropriate value depending on desired optical properties, stretching conditions described later, and the like. Preferably it is 50 micrometers - 300 micrometers.

For the above stretching, any suitable stretching method and stretching conditions (eg, stretching temperature, stretching ratio, stretching direction) may be employed. Specifically, various stretching methods such as free-end stretching, fixed-end stretching, free-end contraction, fixed-end contraction, etc. may be used alone or simultaneously or sequentially. The stretching direction can also be carried out in various directions or dimensions, such as a horizontal direction, a vertical direction, a thickness direction, and a diagonal direction. It is preferable that the temperature of extending|stretching is Tg-30 degreeC - Tg+60 degreeC with respect to the glass transition temperature (Tg) of a resin film, More preferably, they are Tg-10 degreeC - Tg+50 degreeC.

By appropriately selecting the stretching method and stretching conditions, a retardation film having the desired optical properties (eg, refractive index characteristic, in-plane retardation, Nz coefficient) can be obtained.

In one embodiment, retardation film is produced by diagonally extending|stretching a long resin film continuously in the direction of angle (theta) with respect to a longitudinal direction. By employing oblique stretching, an elongated stretched film having an orientation angle of an angle θ (slow axis in the direction of angle θ) with respect to the longitudinal direction of the film is obtained, for example, roll-to-roll at the time of lamination with a polarizer. -Roll is possible, so 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 may be an angle between the absorption axis of the third polarizer and the slow axis of the first optical compensation layer. .

As a stretching machine used for diagonal stretching, for example, a tenter type stretching machine capable of applying a feeding force or a tensile force or a pulling force at different speeds in the transverse and/or longitudinal directions is mentioned. Although there are a horizontal uniaxial stretching machine, a simultaneous biaxial stretching machine, etc. as a tenter type stretching machine, any suitable stretching machine can be used as long as it can diagonally stretch a long resin film continuously.

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, still more preferably 20 µm to 65 µm. With such a thickness, the desired in-plane retardation and Nz coefficient can be obtained.

F. Second Optical Compensation Layer

The optical properties, constituent materials, thickness, etc. of the second optical compensation layer are the same as those described in Section E above with respect to the first optical compensation layer. The second optical compensation layer may be the same as or different from the first optical compensation layer.

G. Optically Equivalent Modifications 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 the λ/2 plate. With such a configuration, an excellent circular polarization function and an antireflection function can be realized over a wide wavelength band.

The λ/2 plate preferably exhibits a relation 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, more preferably 220 nm to 330 nm.

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 the polarization direction after passing the λ/2 plate and that of the first optical compensation layer or the second optical compensation layer. It is preferable to adjust so that the angle formed by the slow axis becomes appropriate. For example, when the slow axis of the λ/2 plate is located on the right rotation side (0° to +180°) with respect to the absorption axis of the third polarizer, the axial angle of the slow axis of the first optical compensation layer is the λ/2 plate. With respect to the polarization direction after passing, it is preferably +40° to +50°, more preferably +43° to +47°, still more preferably +45°. Further, for example, when the slow axis of the λ/2 plate is located on the left rotation side (-180° to 0°) with respect to the absorption axis of the third polarizer, the axial angle of the slow axis of the first optical compensation layer is the λ/2 plate. The polarization direction after passing through is preferably -40° to -50°, more preferably -43° to -47°, and still more preferably -45°. The same relation can be applied to the second optical compensation layer and the second polarizer. Here, +x° means that it becomes x° in a clockwise direction with respect to the reference direction, and -x° means that it becomes x° counterclockwise with respect to the reference direction.

The λ/2 plate is typically a stretched film of a resin film like the first optical compensation layer and the second optical compensation layer.

H. Adhesive

In one embodiment, as mentioned above, the permeable part of the cover sheet 40 is an opening part, and the said opening part is filled with the adhesive body. 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, it is possible to further significantly reduce the visual step while maintaining the brightness of the display screen.

As mentioned above, the refractive index of an adhesive becomes like this. Preferably it is 1.30-1.70, More preferably, it is 1.40-1.60, More preferably, it is 1.45-1.55. 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 level difference can be further improved.

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 making the difference between the refractive index of the pressure-sensitive adhesive and the refractive index of the adjacent layer within such a range, the above effect when the refractive index of the pressure-sensitive adhesive is within a predetermined range can be further promoted.

As described above, the pressure-sensitive adhesive may fill only the opening portion, or may be a part of the pressure-sensitive adhesive layer 80 provided between the cover sheet 40 and the first optical compensation layer 50 . 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) may be appropriately set according to the purpose, adhesive strength, 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, still more preferably 1 µm to 100 µm.

The pressure-sensitive adhesive layer may be composed of any suitable pressure-sensitive adhesive having the above properties. As a specific example, the adhesive which uses an acrylic polymer, silicone polymer, polyester, polyurethane, polyamide, polyether, a fluorine-type polymer, a rubber-type polymer etc. as a base polymer is mentioned. Preferably, it is an adhesive (acrylic adhesive) which uses an acrylic polymer as a base polymer. It is because it is excellent in excellent optical transparency, moderate adhesive properties (wettability, cohesiveness, and adhesiveness), and excellent weather resistance and heat resistance.

[Example]

Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by these Examples. In addition, the measuring method of each characteristic is as follows.

(1) Physical step

About the liquid crystal display device obtained by the Example and the comparative example, the presence or absence of the unevenness|corrugation of the surface by the visual recognition side was confirmed.

(2) visual step

The level difference was visually confirmed in the state in which the image was actually displayed on the liquid crystal display device obtained by the Example and the comparative example. Evaluation was made on the basis of the following criteria.

A: The level difference is not recognized substantially, and there is no problem at all in visual recognition of an image.

B: The level difference is recognized, but there is substantially no influence on the visual recognition of an image.

C: A level difference such that a sense of incongruity occurs in the recognition of an image is recognized.

D: A level difference to such a degree that it has a large influence on the recognition of an image is clearly recognized.

(3) Brightness of the display screen

The luminance of the liquid crystal display devices obtained in Examples and Comparative Examples when the entire screen was displayed in white was measured. The following criteria evaluated using the luminance ratio when the luminance of Comparative Example 1 was 100%.

A: The luminance ratio exceeds 60%

B: luminance ratio of 40% to 60%

C: luminance ratio of 20% to 40%

D: luminance ratio less than 20%

[Example 1]

(i) Polarizer

Three commercially available polarizing plates (manufactured by Nitto Denko Corporation, product name "CWQ1463VCUHC") were prepared, and they were set as a 1st polarizing plate (polarizer), a 2nd polarizing plate (polarizer), and a 3rd polarizing plate (polarizer).

(ii) Fabrication of the first optical compensation layer

The retardation film was obtained by the method according to Example 1 of Unexamined-Japanese-Patent No. 2014-26266. Re(550) of the obtained retardation film was 147 nm, Nz coefficient was 1.0, Re(450)/Re(550) was 0.89, and the thickness was 40 micrometers.

(iii) cover sheet

A commercially available methacrylic resin sheet (manufactured by Nitto Resin Industries, Ltd., product name "Flat N-885", thickness 1.0 mm) was used to penetrate the portion corresponding to the display area of the liquid crystal cell described later to form an opening.

(iv) liquid crystal cells

The liquid crystal panel was taken out with the product name "plus one" (IPS mode) manufactured by Century, and the optical film affixed on the upper and lower sides of the liquid crystal cell was removed, and the optical film removal surface was washed. The liquid crystal cell thus obtained was used.

(v) manufacture of liquid crystal display device

On one side of the liquid crystal cell, the polarizing plate (second polarizer) of (i), the cover sheet of (iii), the retardation film (first optical compensation layer) of (ii), and the polarizing plate of (i) (third) on one side of the liquid crystal cell polarizer) was affixed in this order from the liquid crystal cell side. The cover sheet was bonded together so that an opening part might correspond to the display area of a liquid crystal cell. The retardation film (first optical compensation layer) and the cover sheet were bonded together with an ordinary acrylic adhesive, and the openings were not filled with the adhesive. Moreover, the polarizing plate (1st polarizer) of said (i) was pasted together on the other surface of a liquid crystal cell. Here, the absorption axis of the first polarizer and the absorption axis of the second polarizer are orthogonal to each other, the absorption axis of the second polarizer and the absorption axis of the third polarizer are parallel, and the slow axis of the first optical compensation layer and the absorption of the third polarizer Each optical film was bonded together so that the angle which an axis|shaft makes might be set to 45 degrees. In addition, a liquid crystal display was manufactured by embedding the backlight unit taken out in "plus one" of (iv) above the first polarizer. The obtained liquid crystal display device was used for evaluation of said (1)-(3). A result is shown in Table 1.

[Example 2]

A liquid crystal display device was manufactured in the same manner as in Example 1 except that a second optical compensation layer was additionally provided between the second polarizer and the cover sheet. Specifically, the same retardation film as in Example 1 (ii) was used as the second optical compensation layer, and was bonded between the second polarizer and the cover sheet. Here, it was bonded so that the slow axis of the first optical compensation layer and the slow axis of the second optical compensation layer were substantially orthogonal to each other. The obtained liquid crystal display device was subjected to the same evaluation as in Example 1. A result is shown in Table 1.

[Example 3]

A liquid crystal display device was produced in the same manner as in Example 1 except that the opening portion of the cover sheet was filled with an adhesive. The obtained liquid crystal display device was subjected to the same evaluation as in Example 1. A result is shown in Table 1.

[Example 4]

A liquid crystal display was manufactured in the same manner as in Example 2, except that the opening of the cover sheet was filled with an adhesive. The obtained liquid crystal display device was subjected to the same evaluation as in Example 1. A result is shown in Table 1.

[Comparative Example 1]

A liquid crystal display device was manufactured in the same manner as in Example 1 except that the third polarizer and the first optical compensation layer were not provided, that is, the cover sheet was used as the outermost layer. The obtained liquid crystal display device was subjected to the same evaluation as in Example 1. A result is shown in Table 1.

[Comparative Example 2]

Liquid crystal display was carried out in the same manner as in Example 1, except that a commercially available photosensitive filter (manufactured by Fujifilm, product name "Neutral Density Filter ND-0.5", transmittance 36%) was attached instead of the third polarizer and the first optical compensation layer. The device was fabricated. The obtained liquid crystal display device was subjected to the same evaluation as in Example 1. A result is shown in Table 1.

[Comparative Example 3]

A liquid crystal display device was produced in the same manner as in Comparative Example 2 except that the Fujifilm company make and product name “Neutral Density Filter ND-0.8” (transmittance 18%) was used as the photosensitive filter. The obtained liquid crystal display device was subjected to the same evaluation as in Example 1. A result is shown in Table 1.

[Comparative Example 4]

A liquid crystal display was manufactured in the same manner as in Example 1 except that the first optical compensation layer was not provided. The obtained liquid crystal display device was subjected to the same evaluation as in Example 1. A result is shown in Table 1.

composition of the poet physical step visual difference brightness Example 1 Third polarizer/first optical compensation layer/cover sheet radish A B(40) Example 2 Third polarizer/first optical compensation layer/cover sheet/second optical compensation layer radish A A(71) Example 3 Third polarizer/first optical compensation layer/cover sheet (opening filling) radish A B(46)
Example 4 Third polarizer/first optical compensation layer/cover sheet (opening filling)/second optical compensation layer radish A A(79) Comparative Example 1 cover sheet you D A(100) Comparative Example 2 Photosensitive filter/cover sheet radish C C(36) Comparative Example 3 Photosensitive filter/cover sheet radish B D(18) Comparative Example 4 Third Polarizer/Cover Sheet radish C A(79)

* Brightness in parentheses is luminance ratio (%) when the luminance of Comparative Example 1 is 100% As is clear from Table 1, in the liquid crystal display of the embodiment of the present invention, the physical step is eliminated, and the visual step and the display screen The balance with the brightness was excellent. In the liquid crystal display device of Comparative Example 1 in which the cover sheet was used as the outermost layer on the viewing side, the display screen was bright, but the physical step was not resolved, and the visual step was so poor that the visibility was affected. In the liquid crystal display of Comparative Example 2 using the photosensitive filter, although the physical step was resolved, both the brightness and the visual step of the display screen were poor. In the liquid crystal display device of Comparative Example 3 in which the optical compensation layer (λ/4 plate) was not provided, the display screen was bright, but the visual step was poor. In addition, it can be seen that the brightness can be further improved by filling the opening with an adhesive, as is clear from a comparison of Example 1 and Example 3 and Examples 2 and 4 .

[Industrial Applicability]

The liquid crystal display device of the present invention is a portable device such as a personal digital assistant (PDA), a mobile phone, a watch, a digital camera, and a portable game machine; Home electrical equipment such as appliances, back monitors, car navigation system monitors, car audio equipment, display equipment such as information monitors for commercial stores, security equipment such as monitoring monitors, nursing monitors, medical monitors, etc. It can be used for various purposes such as nursing and medical equipment. In particular, the liquid crystal display of the present invention can be preferably used in a built-in form in a structure.

10: liquid crystal cell
20: first polarizer
30: second polarizer
40: cover sheet
50: first optical compensation layer
60: third polarizer
70: second optical compensation layer
80: adhesive layer
100: liquid crystal display device

Claims (6)

liquid crystal cell,
a first polarizer disposed on the rear side of the liquid crystal cell;
a second polarizer disposed on the viewer side of the liquid crystal cell;
a cover sheet having a transmissive portion at a position corresponding to the display area of the liquid crystal cell disposed on the viewer side of the second polarizer;
A first optical compensation layer having a Re (550) of 100 nm to 180 nm disposed to cover the transmission part on the viewing side of the cover sheet;
and a third polarizer disposed on the viewer side of the first optical compensation layer,
An angle between the slow axis direction of the first optical compensation layer and the absorption axis direction of the third polarizer is 35° to 55° or 125° to 145°,
liquid crystal display. The method of claim 1,
and a second optical compensation layer having Re (550) of 100 nm to 180 nm between the cover sheet and the second polarizer. 3. The method of claim 2,
A liquid crystal display device, wherein the polarization direction of the circularly polarized light obtained by the first optical compensation layer and the third polarizer is the same as the polarization direction of the circularly polarized light obtained by the second polarizer and the second optical compensation layer. 3. The method of claim 2,
and the first optical compensation layer and the second optical compensation layer satisfy the relation Re(450)<Re(550). 5. The method according to any one of claims 1 to 4,
The liquid crystal display device, wherein the transmission portion of the cover sheet is an opening, and the opening is filled with an adhesive. 6. The method of claim 5,
The refractive index of the pressure-sensitive adhesive is 1.30 to 1.70, a liquid crystal display.

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