KR20210154994A - 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 comprises: 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 an opening at a position corresponding to the display area of the liquid crystal cell disposed on the viewer side of the second polarizer; The 3rd polarizer arrange|positioned so that an opening part may be covered by the visual recognition side of a cover sheet is provided. The opening of the cover sheet is filled with an adhesive.

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 their 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 configuration, a cover sheet having an opening corresponding to a 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.

Patent Document 1: Japanese Patent No. 5877433 Specification

The present invention has been made in order to solve the above-mentioned conventional problems, and an object thereof is a liquid crystal display device 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. is to provide

A liquid crystal display device of the present invention comprises: 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 an opening at a position corresponding to the display area of the liquid crystal cell disposed on the viewer side of the second polarizer; A third polarizer is provided so as to cover the opening on the viewing side of the cover sheet. The opening of the cover sheet is filled with an adhesive.

In one embodiment, the said adhesive is a part of the adhesive layer provided between the said cover sheet and the said 3rd polarizer.

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

In one embodiment, the difference between the refractive index of the said adhesive and the refractive index of the layer adjacent to the said adhesive is 0.2 or less.

According to the present invention, in a liquid crystal display device having a step difference between the display screen and the outermost surface by a cover sheet having an opening, a polarizer is arranged on the visual side of the step, and the opening is filled with an adhesive to protect the display screen. Visibility can be improved by making it difficult to recognize a step while maintaining brightness.

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.

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

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 a cover sheet 40 disposed on the viewer side of the second polarizer 30 , and a third polarizer 60 disposed on the viewer side of the cover sheet 40 . The cover sheet 40 has an opening at a position corresponding to the display area of the liquid crystal cell 10 . The third polarizer 60 is disposed so as to cover the opening of the cover sheet 40 . According to the embodiment of the present invention, the third polarizer is disposed on the outermost surface side to cover the opening of the cover sheet, thereby making it difficult to recognize the step caused by the cover sheet (opening), and as a result, the visibility of the liquid crystal display device is improved can do. More specifically, in addition to making it difficult to recognize a level difference by making the outermost surface flat by covering the opening part of a cover sheet, it originates in the transmittance|permeability peculiar to a polarizer, and it can make it more difficult to recognize a level difference. In addition, since the polarizer can efficiently transmit polarized light in a predetermined direction, the brightness of the display screen can be maintained compared to a photosensitive filter that reduces light as a whole. Hereinafter, "making it difficult to recognize a level difference" is sometimes referred to as "reducing a visual level difference".

In the embodiment of the present invention, the pressure-sensitive adhesive fills the opening of the cover sheet 40 . The adhesive may fill only the opening part, and may be a part of the adhesive layer 80 provided between the cover sheet 40 and the 3rd polarizer 60. With such a configuration, since the air layer formed by the opening is excluded, reflection and/or refraction at the stair surface can be suppressed. As a result, it is possible to further significantly reduce the visual step while maintaining the brightness of the display screen. 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 on the stair surface can be further suppressed, and the balance between the brightness of the display screen and the visual level difference can be further improved.

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. The absorption axis direction of the second polarizer 30 and the absorption axis direction of the third polarizer 60 are typically substantially perpendicular or parallel, and preferably substantially parallel. With such a configuration, it is possible to reduce the visual step while maintaining the brightness of the display screen. In addition, 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. In the present specification, the expressions "substantially orthogonal" and "approximately orthogonal" include a case where the angle formed by two directions is 90°±10°, preferably 90°±7°, and more preferably 90°±10°. °±5°. The expressions "substantially parallel" and "approximately parallel" include the case where the angle between the two directions is 0°±10°, preferably 0°±7°, more preferably 0°±5° to be. In addition, when simply referring to "orthogonal" or "parallel" in the present specification, it shall include a substantially orthogonal or substantially parallel state.

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. In the liquid crystal display device 101 , the cover sheet 40 is curved, and the third polarizer 60 is curved along the cover sheet 40 . Preferably, the adhesive fills the gap between the cover sheet 40 and the 2nd polarizer 30 which arises when the cover sheet 40 curves. 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. Further, like the liquid crystal display device 102 shown in FIG. 3 , 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 101 and 102 of the present embodiment in which the cover sheet is curved have a wide range of design choices and a large commercial value.

4 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 103 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. A liquid crystal cell 10B, a first polarizer 20B disposed on the rear side of the liquid crystal cell 10B, a second polarizer 30B disposed on a viewing side of the liquid crystal cell 10B, and a second polarizer The cover sheet 40 arranged on the visual recognition side of 30A and 30B and the third polarizer 60 arranged on the visual recognition side of the cover sheet 40 are provided. The cover sheet 40 of the liquid crystal display device 103 includes a first transmission portion 42A at a position corresponding to the display area of the liquid crystal cell 10A, and a second transmission portion 42A 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 103 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.

5 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 104 of this embodiment has two display screens similarly to the liquid crystal display device 103 . 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 third polarizer 60 is bent along the cover sheet 40 , have. Accordingly, the liquid crystal display 104 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), railroad 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 practically further includes a backlight unit (not shown). 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, a so-called λ/4 plate is disposed between the second polarizer 30 and the cover sheet 40 and/or between the cover sheet 40 (actually the pressure-sensitive adhesive layer 80 ) and the third polarizer 60 . it may be With such a configuration, the visual step difference can be further reduced. Note that the λ/4 plate may be substituted with a laminate of a λ/4 plate and a λ/2 plate. Further, for example, an optical compensation layer (retardation film) different from the λ/4 plate 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. Moreover, for example, various surface treatment layers may be arrange|positioned 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.

Said embodiment may be combined suitably, and the structure in said embodiment may be substituted by the optically same structure. For example, as shown in FIG. 6 , the embodiment of FIG. 3 and the embodiment of FIG. 4 may be combined. Specifically, in Fig. 6, the liquid crystal display device 105 includes a liquid crystal cell 10A and a liquid crystal cell 10B, each configuration is curved, and the cover sheet 40 is disposed in the display area of the liquid crystal cell 10A. The first transmissive part 42A is provided at a corresponding position, and the second transmissive part 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, 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 this switching element are provided signal lines, 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. The "liquid crystal molecules aligned in a homeotropic arrangement" refers to a state in which the alignment vectors of the liquid crystal molecules are 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 or 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 employing a V-shaped electrode or a zigzag electrode, or an ultra fringe field switching (U-FFS) mode.

C. Polarizer

Any appropriate polarizer may be employed as the first polarizer, the second polarizer, and the third polarizer (hereinafter, collectively referred to simply as 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, iodine or a dichroic dye is added to a hydrophilic polymer film such as a polyvinyl alcohol (PVA)-based film, a partially formalized PVA-based film, or an ethylene/vinyl acetate copolymer-based partially saponified film. Polyene-type oriented films, such as the thing to which the dyeing process and extending|stretching process by the dichroic substance were given, the dehydration-processed material of PVA, and the dehydrochloric acid-treated material of polyvinyl chloride, etc. are mentioned. Preferably, since it is excellent in an optical characteristic, the polarizer obtained by dyeing|staining a PVA-type film with iodine and uniaxial stretching is used.

The dyeing with iodine is made by, for example, immersing a PVA-based film in an aqueous iodine solution. The draw ratio of the said uniaxial stretching becomes like this. Preferably it is 3 to 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 to not only wash the surface of the PVA-based film from contamination or an anti-blocking agent, but also to expand 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 may 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 be included in the liquid crystal display device as a polarizing plate, respectively.

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, glassy 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 the protective layer is the thickness including the thickness of the 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 for 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 an opening corresponding to the display area of the liquid crystal cell so as not to interfere with the display function of the liquid crystal display.

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, polyaryletherketone, 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.

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 significantly reduced.

E. Adhesive layer

In the embodiment of the present invention, as described above, the opening of the cover sheet 40 is filled with an adhesive. As a result, since the air layer formed by the opening is excluded, reflection and/or refraction at the stair surface 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 on the stair surface 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 can be further promoted when the refractive index of the pressure-sensitive adhesive is within a predetermined range.

As described above, 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 third polarizer 60 . 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 90%

B: luminance ratio 80% to 90%

C: luminance ratio of 70% to 80%

D: luminance ratio less than 70%

[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) 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.

(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 affixed on the upper and lower sides of the liquid crystal cell was further removed, and the optical film removal surface was washed. The liquid crystal cell thus obtained was used.

(iv) manufacture of liquid crystal display device

The polarizing plate (2nd polarizer) of said (i), the cover sheet of said (ii), and the polarizing plate (3rd polarizer) of said (i) were pasted together on one side of a liquid crystal cell 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 third polarizer and the cover sheet were bonded together with an adhesive (manufactured by Nitto Denko Corporation, product name "CS99110", thickness 250 µm, storage elastic modulus G' = 120 KPa), and the opening of the cover sheet was filled with the adhesive. In the present Example, this adhesive was overlapped in 4 layers, and the opening part was filled. 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 a 1st polarizer and the absorption axis of a 2nd polarizer were orthogonal, it was made so that the absorption axis of a 2nd polarizer and the absorption axis of a 3rd polarizer might become parallel, and each optical film was bonded together. In addition, a liquid crystal display device was manufactured by including the backlight unit taken out from "plus one" in (iii) on the outside of the first polarizer. The obtained liquid crystal display device was used for evaluation of said (1)-(3). A result is shown in Table 1.

[Comparative Example 1]

A liquid crystal display device was produced in the same manner as in Example 1 except that the third polarizer was 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]

A liquid crystal display device was produced in the same manner as in Example 1 except that a commercially available photosensitive filter (manufactured by Fujifilm, product name "neutral density filter ND-0.2", transmittance 64%) was attached instead of the third polarizer. 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 Example 1 except that the third polarizer and the cover sheet were bonded together with a normal acrylic pressure-sensitive adhesive, and the opening portion of the cover sheet was not filled. 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 3rd polarizer/cover sheet (with opening filling) radish A A(90)
Comparative Example 1 cover sheet you D A(100) Comparative Example 2 Photosensitive filter/cover sheet radish C D(64) Comparative Example 3 3rd polarizer/cover sheet (no opening filling) radish C C(79)

In parentheses of the brightness, the 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 was eliminated, and the balance between the visual step and the brightness of the display screen 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 level difference was not resolved and the visual level difference 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 of Comparative Example 3 in which the opening of the cover sheet was not filled, the brightness was improved compared to Comparative Example 2, but the visual difference was poor.

[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
60: third polarizer
80: adhesive layer
100: liquid crystal display device

Claims (1)

liquid crystal display.

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