KR101609313B1 - A laminated polarizer set and blue phase liquid crystal mode liquid crystal display comprising the same - Google Patents

Abstract

The present invention relates to a multi-component polarizing plate set comprising a first multi-component polarizing plate and a second multi-component polarizing plate each having a specific retardation film laminated thereon, To a liquid crystal display device capable of securing a wide viewing angle equal to or greater than that of the liquid crystal mode and facilitating mass production of a composite polarizing plate.

Liquid crystal display, blue liquid crystal, compound polarizer set

Description

TECHNICAL FIELD [0001] The present invention relates to a composite polarizing plate and a blue liquid crystal mode liquid crystal display including the same,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a liquid crystal display device capable of securing a wide viewing angle by applying a specific complex compound polarizing plate set to a blue liquid crystal mode.

BACKGROUND ART [0002] A liquid crystal display (LCD) has solved various technical problems at the beginning of development and is now widely used as a popular image display device. Such a liquid crystal display device includes a liquid crystal display panel for displaying an image and a backlight assembly for providing light to the liquid crystal display panel.

The liquid crystal used in the liquid crystal display panel includes NEMATIC liquid crystal, SMECTIC liquid crystal, and CHOLESTERIC liquid crystal, and a nematic liquid crystal is mainly used. Such a nematic liquid crystal has its inclination angle adjusted according to the electric field formed between the pixel electrode and the common electrode, and the liquid crystal layer controls the light transmittance according to the inclination angle of the nematic liquid crystal. Accordingly, the brightness of the liquid crystal display panel is determined by the thickness of the liquid crystal layer, that is, the cell gap of the liquid crystal display panel and the anisotropic refractive index of the liquid crystal.

A liquid crystal display panel having a blue liquid crystal has been proposed to overcome the anisotropic refractive index problem that causes a decrease in dependence of the cell gap and a viewing angle [US Pat. No. 4,767,149]. The blue liquid crystal has a characteristic that the anisotropic refractive index changes to an isotropic shape according to the magnitude of the applied voltage, thereby improving the viewing angle and response speed of the liquid crystal display panel.

On the other hand, it is general to apply a pixel electrode, a common electrode, and a composite polarizer for a planar switching liquid crystal display device which is easy to secure a wide viewing angle when a blue liquid crystal is implemented as a normal black [Korean Patent Laid-Open No. 2008-67041].

The compound polarizing plate for planar switching liquid crystal displays is provided on both sides of the liquid crystal cell and includes an isotropic protective film between one liquid crystal cell and the polarizer and two compensations with different optical characteristics between the liquid crystal cell and the polarizer Layer or thickness-oriented film (or three-dimensional retardation film) is placed.

However, since two compensating layers having different optical properties are used in the composite polarizing plate, the thickness and the thickness of the liquid crystal cell are different from those of conventional liquid crystal display devices. There is a high possibility of occurrence. In particular, since the shrinking process of applying the shrink film is necessarily required in the production of the thickness direction film, there is a problem that the price is considerably high.

Therefore, a liquid crystal display device for a blue liquid crystal device which is simple in structure and easy to mass-produce because of its simple structure and price is desperately required, since a wide viewing angle equal to or larger than that of a plane switching liquid crystal display device can be realized.

The present invention provides a composite polarizing plate set which is simple in structure and can be mass-produced with ease and a wide viewing angle equal to or larger than that of a conventional liquid crystal display device, And to provide a blue liquid crystal mode liquid crystal display capable of being cost-competitive.

The first composite polarizing plate and the second composite polarizing plate each include a retardation film, a polarizer, and a protective film, and the retardation film of the first complex polarizing plate and the second composite polarizing plate, And the refractive index ratio (NZ) is -6.0 to -0.1, the retardation film of the second complex-constituting polarizing plate is disposed such that the slow axis is parallel to the absorption axis of the adjacent polarizer, And has a front retardation value (R0) of 0 to 10 nm and a thickness direction retardation (Rth) of 80 to 310 nm.

In addition, the present invention is further characterized in that a liquid crystal display device comprising a composite polarizing plate set including the first complex polarizing plate and the second complex polarizing plate as a top plate and a bottom plate polarizing plate in a blue liquid crystal mode.

The present invention provides a complex polarizing plate set and a liquid crystal display device using the same, which are advantageous in that they are simple in structure and are easy to manufacture because of easy manufacturing process and mass production, and compared with the conventional liquid crystal display apparatus, It is possible to realize a wide viewing angle.

The present invention relates to a complex composition polarizing plate set comprising a first complex polarizer plate and a second complex polarizer plate laminated with a retardation film having specific optical properties. Specifically, the first composite polarizing plate and the second composite polarizing plate of the complex-composition polarizing plate set are composed of a retardation film, a polarizer, and a protective film, respectively.

Wherein the retardation film of the first complex polarizing plate has a front retardation value R0 of 50 to 150 nm and a refractive index ratio NZ of -6.0 to -0.1 and the retardation film of the second complex polarizing plate has a retardation value R0, Is 0 to 10 nm and the thickness direction retardation (Rth) is 80 to 310 nm. At this time, the retardation film of the first complex polarizing plate is arranged so that the slow axis is parallel to the absorption axis of the adjacent polarizer.

In the present invention, the optical characteristics of the retardation film are defined by the following equations (1) to (3) for the propagation field in the visible light region.

If there is no mention of the wavelength of the light source, it generally means that the optical characteristic is described when the wavelength is 589 nm. Here, Nx is the refractive index of the axis having the greatest refractive index in the in-plane direction, Ny is the vertical direction of Nx in the in-plane direction, and Nz is the refractive index in the thickness direction.

Rth = [(Nx + Ny) / 2 - Nz] xd

(Where Nx and Ny are surface refractive indices Nx > = Ny, Nz is refractive index in the thickness direction of the film, and d is the thickness of the film)

R0 = (Nx - Ny) xd

(Where Nx and Ny are the surface refractive indexes of the retardation film and d is the thickness of the film, where Nx > = Ny)

NZ = (Nx - Nz) / (Nx - Ny) = Rth / R0 + 0.5

(Where Nx and Ny are surface refractive indexes, Nx > = Ny, Nz is refractive index in the thickness direction of the film, and d is the thickness of the film)

Rth is a retardation in the thickness direction and is a reference value indicating a difference in the refractive index in the thickness direction with respect to the in-plane average refractive index, which is not a substantial retardation, R0 is a front retardation, and light passes through the normal direction Is a substantial phase difference.

In addition, NZ is a refractive index ratio and can discriminate the type of plate of the retardation film. In the case of the plate of the retardation film, when the optical axis which is a light path in the film, in which the retardation does not occur, exists in the in-plane direction of the film, the A plate; A C plate when the optical axis exists in a direction perpendicular to the surface; And when there are two optical axes, it is called a biaxial plate.

Specifically, when NZ = 1, the refractive index satisfies the relation of Nx> Ny = Nz and is referred to as a 'Positive A plate'; 1 &lt; NZ, the refractive index satisfies Nx &gt; Ny &gt; Nz and is referred to as a 'NEGATIVE BIAXIAL A PLATE'; When 0 <NZ <1, the refractive index has a relationship of Nx> Nz> Ny and is called a 'Z-axis oriented film'; When NZ = 0, the refractive index has a relationship of Nx = Nz &gt; Ny and is referred to as a 'negative A plate'; When NZ &lt; 0, the refractive index has a relationship of Nz &gt; Nx &gt; Ny and is referred to as a POSITIVE BIAXIAL A PLATE; In the case of NZ = ∞, the refractive index has a relation of Nx = Ny> Nz and is called a 'negative C plate'; In the case of NZ = -∞, the refractive index has a relationship of Nz> Nx = Ny and is referred to as a 'Positive C plate'.

However, it is practically impossible to make A plates and C plates that perfectly match the above theoretical definition. Therefore, in the general process, the approximate range of the refractive index ratio is set for the A plate, and the range of the front retardation for the C plate is set to any value. And its arbitrary numerical setting has a limit to apply to all materials having different refractive index developing properties in accordance with stretching. Therefore, in the present invention, the retardation films included in the first and second complex polarizers show numerical values of NZ, RO, and Rth, which are optical characteristics of the plate, not the plate type according to the shape of the refractive index anisotropy.

Such a retardation film is usually referred to as a film having a positive refractive index in a stretching direction and a film having a refractive index in a stretching direction as a negative refractive index, . The retardation film having positive refractive index characteristics specifically includes triacetylcellulose (TAC), cycloolefin polymer (COP), cycloolefin copolymer (COC), polyethylene terephthalate (PET), polypropylene (PP) (PS), polymethyl methacrylate (PMMA), and the like. The retardation film having a negative refractive index characteristic may be made of a material selected from the group consisting of modified polystyrene (PS) or Modified polycarbonate (PC).

The stretching method for imparting the optical characteristics of the retardation film is divided into fixed-end stretching and free-end stretching. The fixed-end stretching is a method of fixing a length other than a stretching direction during stretching of the film. A degree of freedom is given to a direction other than the stretching direction. Generally, when the film is stretched, the direction other than the stretching direction is shrunk, but the Z-axis oriented film requires a separate shrinking process in addition to the stretching.

FIG. 3 shows the direction of the film roll in the roll state. The direction in which the film in the roll state is unwound is referred to as the machine direction and is referred to as the MD (Machine Direction) direction. . At this time, stretching the film in the MD direction in the process is referred to as free-end stretching, and TD stretching is referred to as fixed-end stretching.

When the types of NZ and the plate according to the stretching method (only the first step is applied) are summarized, the positive A plate is free stretched in the film having positive refractive index characteristics; The negative biaxial A plate is subjected to fixed-end stretching of a film having a positive refractive index characteristic; The Z-axis oriented film is free-end-stretched and fixed-end-contracted after the film having positive (+) refractive index property or negative (-) refractive index property; The negative A plate is subjected to free-standing stretching a film having a negative refractive index characteristic; The positive biaxial A plate can be produced by stretching a film having a negative refractive index characteristic by a fixed end.

The direction of the slow axis, the retardation value, and the value of NZ can be controlled by an additional process other than the stretching method, and the additional process is not particularly limited to a process generally applied in the art.

The complex-composition polarizing plate set according to the present invention is composed of a first complex-composition polarizer and a second complex-composition polarizer, each of which is made of a retardation film, a polarizer and a protective film.

The retardation film of the first composite polarizing plate uses a retardation film having a front retardation (R0) of 50 to 150 nm and a refractive index ratio (NZ) of -6.0 to -0.1. In order to secure a better viewing angle, The frontal retardation value R0 becomes larger and the refractive index ratio becomes smaller as the absolute value thereof becomes smaller, so that the dispersibility of the polarized state becomes smaller and can be easily used as the retardation film of the present invention. Further, the front retardation value R0 ) Can be appropriately used in combination according to the refractive index ratio. If the refractive index ratio (NZ) is less than -6.0, the dispersibility, which refers to the difference in polarization state according to the wavelength after passing through the liquid crystal display device having the optimum viewing angle effect composed of the first retardation film, the liquid crystal cell and the second retardation film, If the refractive index ratio (NZ) exceeds -0.1, the slow axis of the retardation film is different from the MD direction, and thus, There is a problem that it is not easy to apply to a roll (roll to roll) process.

Further, the minimum retardation value for producing a retardation film having a uniform phase difference (within ± 5 nm of the target value) and a retardation angle (± 0.5 °) generally applied to the liquid crystal display device at present must be maintained at 40 nm or more And it is preferable that the minimum value of the retardation is maintained at 50 nm or more on the actual process.

Preferably, the retardation value (R0) is 80 to 150 nm and the refractive index ratio (NZ) is -2.0 to -0.1. Since the front retardation value R0 can be compensated by the second retardation layer according to the refractive index ratio NZ, the front retardation R0 according to NZ -2.0 to -0.1 ranges from 80 to 150 nm . More preferably, it is preferable to use one having a front retardation value (R0) of 100 to 150 nm and a refractive index ratio (NZ) of -1.0 to -0.1. The refractive index ratio is preferably in the range of Range. Since the front retardation value R0 can be compensated by the second retardation layer according to the refractive index ratio NZ, the range of the front retardation R0 according to NZ -1.0 to -0.1 ranges from 100 to 150 nm . In this case, the TD uniaxial stretching is easier than the biaxial stretching in that the manufacturing process is simplified because of the simple process.

The retardation film of such a first complex-constituting polarizing plate is disposed so that its slow axis is parallel to the absorption axis of the adjacent polarizer.

The retardation film of the second composite polarizing plate has a front retardation (R0) of 0 to 10 nm and a thickness retardation (Rth) of 80 to 310 nm. In consideration of the retardation film and the optical characteristics of the first composite polarizing plate A combination of easy to secure a wide viewing angle is used.

The preferred range of the second retardation layer according to the preferred range of the first retardation layer is that the front retardation R0 is 0 to 5 nm and the thickness direction retardation Rth is 80 to 200 nm, A more preferable range of the second retardation layer according to the preferable range is that the front retardation value R0 is 0 to 3 nm and the thickness direction retardation Rth is 80 to 140 nm. These ranges are also limited in consideration of the optical properties and easiness in the manufacturing process as well as the retardation film of the first composite polarizing plate, and the casting process or the complete biaxial stretching process can be easily applied to the production process.

The retardation film of such a second composite polarizing plate is disposed irrelevant to the absorption axis of the adjacent polarizer since there is no slow axis.

Generally, the retardation film has a different retardation value depending on the incident wavelength. The retardation film having a large retardation value at a short wavelength and a small retardation value at a long wavelength is called a retardation film having a regular wavelength dispersion property. A film having a small retardation value at a short wavelength and a large retardation value at a long wavelength is referred to as a retardation film having an inverse wavelength dispersibility. The present invention can be used without any limitation on the dispersibility of such a retardation film.

In the present invention, the dispersibility of the retardation film is represented by the ratio of the retardation value to the light source 380 nm to the retardation value for the light source of 780 nm generally used in the art. For reference, the value of [RO (380 nm) / RO (780 nm)] = 0.4872 for a retardation film having a perfect inverse wavelength dispersion property capable of changing to the same polarizing state for all wavelengths.

The polarizers of the first and second composite polarizers according to the present invention are each provided with a polyvinyl alcohol (PVA) layer as a polarizer imparted with a polarizing function by a process such as stretching and dyeing, and the polyvinyl alcohol (PVA) layer of the first complex-type polarizing plate and the polyvinyl alcohol (PVA) layer of the second complex-composition polarizing plate. The first and second composite polarizers may be manufactured using a process commonly used in the art, and specifically, a composite roll-to-roll process and a sheet-to-sheet process may be applied . Preferably, the roll-to-roll process is applied considering the yield and efficiency of the manufacturing process. In particular, since the direction of the absorption axis of the PVA polarizer is always fixed in the MD direction, its application is effective.

At this time, the protective film of the first and second composite polarizing plates does not affect the viewing angle by the optical characteristic depending on the refractive index difference, and thus the refractive index characteristic is not particularly limited in the present invention. The materials forming the protective films of the first and second composite polarizing plates may be independently used from those commonly used in the art, and specifically include triacetyl cellulose (TAC), cycloolefin polymer (COP), cyclo (PSA), polypropylene (PP), polycarbonate (PC), polysulfone (PSF) and polymethylmethacrylate (PMMA) .

The present invention also includes a complex composition polarizing plate set comprising a blue liquid crystal and a first composite polarizing plate and a second composite polarizing plate in which a retardation film having a specific optical property is respectively disposed on an upper plate and a lower plate polarizing plate of a liquid crystal, And a liquid crystal display device. The liquid crystal display device may have a first composite polarizer plate as a top plate polarizer and a second composite polarizer plate as a lower plate polarizer, or a second composite polarizer plate as a top plate polarizer and a bottom plate polarizer. And the absorption axis of the first complex-constituting polarizing plate is orthogonal to the absorption axis of the second complex-constituting polarizing plate.

The blue phase liquid crystal of the present invention changes refractive index from isotropic to isotropic depending on whether an electric field is applied or not. Such a liquid crystal forms an array of cylinders in which molecules are twisted in a three-dimensional spiral manner, and this alignment structure is referred to as a double twist cylinder (hereinafter referred to as DTC) structure. The blue liquid crystal molecules are arranged to be gradually twisted from the central axis of the DTC toward the outer side. That is, the blue liquid crystal molecules are arranged so as to be twisted along two mutually orthogonal twist axes in the DTC, and are oriented in the DTC with respect to the central axis of the DTC.

These blue liquid crystals have a first blue phase, a second blue phase and a third blue phase, and the arrangement structure thereof varies depending on the type of blue phase in the DTC. The first blue phase is arranged in a body-centered cubic structure in which the DTCs are one of the lattice structures, and the second blue phase is arranged in a simple cubic structure. Since the DTCs are arranged in a lattice structure, the blue phase causes a line defect in a portion where three adjacent DTCs meet. The line defect forms a line defect line as a part where the liquid crystals have irregular arrangement because they do not have regular directionality.

The blue liquid crystal changes its anisotropic refractive index in proportion to the square of the applied voltage depending on the magnitude of the applied voltage. When an electric field is applied to an isotropic polar material, the optical effect in which the refractive index is proportional to the square of the applied voltage is called a Kerr effect, and the liquid crystal display displays an image using the Kerr effect of the blue liquid crystal, .

In addition, the refractive index of the blue liquid crystal is determined by the region where the electric field is formed. If the area in which the electric field is formed is uniform, the display characteristics of the liquid crystal display device can be improved because the uniform brightness is achieved regardless of the cell gap uniformity.

The liquid crystal display device constituted by the optical conditions of the present invention satisfies the compensation relationship of the maximum transmittance of the visual sensitivity omnidirectional in the black state of 0.05% or less, preferably 0.02% or less. The front brightness of the currently produced brightest liquid crystal display device is about 10000 nits using the VA mode, and the brightness is about 10000 nits × cos 60 ° at a view angle of 60 ° slope, and 0.05% is 2.5 nits to be. Therefore, the present invention intends to realize a visibility omnidirectional transmittance equal to or greater than that of a liquid crystal display device using a vertical alignment mode.

1 is a perspective view illustrating a basic structure of a blue-liquid crystal liquid crystal display device according to the present invention.

The liquid crystal display device for a blue liquid crystal according to the present invention comprises a second protective film 13, a second polarizer 11, a second retardation film 14, a blue phase liquid crystal cell The first polarizing film 30, the first retardation film 24, the first polarizer 21, and the first protective film 23 are laminated in this order. The absorption axes 12 and 22 of the first polarizer 21 and the second polarizer 11 are arranged orthogonally to each other as viewed from the viewer side and the slow axis of the first retardation film and the absorption axis of the first polarizer 11 are parallel to each other Respectively. Specifically, FIG. 1 (a) shows a case where the first composite polarizing plate is disposed on the upper plate polarizer and the slow axis 25 of the first retardation film 24 and the absorption axis 22 of the first polarizer 21 are parallel to each other 1 (b) shows a case in which the slow axis 25 of the first retardation film 24 and the absorption axis 22 of the first polarizer 21 are arranged so that the first complex polarizer is disposed on the lower polarizer, And are arranged so as to be parallel to each other.

The first complex-compound polarizer 20 and the second complex polarizer 10 of the present invention are manufactured by applying a roll-to-roll method which is easy to mass-produce. FIG. 3 is a schematic view for explaining the direction of the MD in the normal roll-to-roll manufacturing process. Referring to FIG.

The first composite polarizing plate 20 and the second composite polarizing plate 10 are made of a combination of various optical films, and each optical film is in a roll state before being bonded to the composite polarizing plate. The direction in which the film is unwound or wound in this roll is referred to as the MD (Machine Direction) direction. In the case of the second complex polarizing plate 10, the directions of the second protective film 13 and the second retardation film 14 do not affect the optical performance and roll-to-roll production is possible, In the case of the constituent polarizing plate 20, there is no relation with the direction of the first protective film 23, and if only the MD direction of the first polarizer 21 and the first retardation film 24 is matched, roll-to- This is possible.

When the absorption axis 12 of the second polarizer 11 close to the backlight unit is in the vertical direction, light passing through the second composite polarizer 10 is polarized in the horizontal direction, When the light passes through the cell and becomes a bright state, the light passes through the first composite polarizing plate 20 on the viewer side in which the absorption axis is in the horizontal direction. At this time, the person wearing the polarized sunglass having the absorption axis in the horizontal direction on the viewer side (the absorption axis of the polarized sunglasses is in the horizontal direction) can recognize light emitted from the liquid crystal display device. If the absorption axis 12 of the second polarizer 11 close to the backlight unit is in the horizontal direction, there is a problem that the image is not seen by the person wearing the polarized sunglasses. In addition, in the case of a large-sized liquid crystal display device, in order to make the image clearly visible from the viewer's view, considering that the human's field of view is wider than the vertical direction, the general liquid crystal display device except for the special- Since the main field of view is wider in the horizontal direction than in the vertical direction, it is produced in the form of 4: 3 or 16: 9. Therefore, the absorption axis of the second polarizer is vertical and the absorption axis of the first polarizer is parallel to the viewer side.

The effect of the viewing angle compensation of the present invention can be explained through the Poincare Sphere. Since the Poincare Sphere is a very useful method for expressing the change of the polarization state at a specific time, the light traveling at a specific time in the liquid crystal display device displaying an image using the polarized light passes through each optical element in the liquid crystal display A change in the polarization state can be indicated. In the present invention, the above-mentioned specific time is expressed in terms of θ = 60 ° and Φ = 45 ° in the semicircle coordinate system shown in FIG. 4, and the change in the polarization state of the light coming out in this direction will be described based on the wavelength 550 nm at which the human being feels the brightest. Specifically, the change in the polarization state with respect to the light emerging in the front direction when the surface in the direction of φ and the direction of φ + 90 ° in the front direction is rotated by θ to the viewer side is shown on the Pouincere diagram. When the coordinates of the S3 axis indicate positive (+) on the Poincare frame, the right circularly polarized light exhibits an arbitrary polarized horizontal component Ex and the polarized vertical component Ey, Is slower than phase 0 and less than half the wavelength.

Hereinafter, the effect of implementing the above-described configuration on the dark state at the full viewing angle when no voltage is applied is summarized in Examples and Comparative Examples. The present invention can be better understood by the following examples, and the following examples are intended to illustrate the present invention and are not intended to limit the scope of protection defined by the appended claims.

Example

In the following EXAMPLES 1 to 6 and COMPARATIVE EXAMPLES 1 to 6, simulation was performed by applying to an LCD simulation program TECH WIZ LCD 1D (MANAI SYSTEM, KOREA) to compare the optical viewing angle effects.

Example 1

Actual data such as each optical film, liquid crystal cell, and backlight according to the present invention were laminated on a TECH WIZ LCD 1D (MANAMA SYSTEM, KOREA) as shown in FIG. The structure of FIG. 1 (a) will be described in detail as follows.

A second polarizer 11, a second retardation film 14, a blue phase liquid crystal cell 30, a first retardation film 24, and a second retardation film 24 from the backlight unit 40 side, The absorption axis 12 of the second polarizer 11 is composed of the first polarizer 21 and the first protective film 23 and is perpendicular to the viewer side and is parallel to the absorption axis 22 of the first polarizer 21. [ The absorption axes 12 and 22 of the first and second polarizers 21 and 11 are orthogonal to each other in the horizontal direction when viewed from the viewer side, The absorption axes 22 of the first polarizer 21 are arranged so as to be parallel to each other.

The liquid crystal cell has a refractive index isotropic when the electric field is not applied, and when the electric field is applied, the refractive index increases in the direction of applying the electric field. The liquid phase mode of the liquid crystal mode uses a blue phase liquid crystal (Samsung Electronics, SID 2008) Respectively. When this is applied, the initial liquid crystal alignment is not necessary, and the manufacturing process of the liquid crystal cell is simplified.

On the other hand, each of the optical films and backlights used in Example 1 of the present invention had optical properties as described below.

라고 할 때 하기 수학식 4 내지 8에 의해 정의된다. 여기서 S(λ)는 광원스펙트럼이며 보통 C광원을 사용한다.First, the first and second polarizers 11 and 21 dyed iodine to the stretched PVA to impart a polarizer function. The polarizing performance of the polarizer is such that the visibility of the polarizer is 99.9% or more in the range of visible light of 370 to 780 nm, 41% or more. The transmittance of the transmission axis according to the wavelength is denoted by TD (λ), the transmittance of the absorption axis with respect to wavelength is denoted by MD (λ), and the visibility correction value defined in JIS Z 8701: 1999

Is defined by the following equations (4) to (8). Where S (λ) is the light source spectrum and usually a C source is used.

The optical characteristics of the second retardation film 14 of the lower plate at the wavelength of 589.3 nm and the retardation value Rth in the thickness direction of 90 nm , And the first retardation film 24 of the upper plate had a front retardation (R0) of 140 nm and a refractive index ratio (NZ) of -0.11.

The wavelength dispersion property of the second retardation film 14 is 0.862 in terms of front retardation (wavelength, 380 nm) / front retardation (wavelength, 780 nm) = [RO (380 nm) / RO (Wavelength: 380 nm) / front phase difference (wavelength, 780 nm) = [RO (380 nm) / RO (780 nm)], and the wavelength dispersion property of the first retardation film (24) ] Is 1.197 and shows the degree of wavelength dispersion of the propagation wavelength as shown in Fig.

Triacetyl cellulose (TAC) having an optical property with a retardation value (Rth) in the thickness direction of 50 nm to the incident light of 589.3 nm as the first and second protective films (13, 23) outside the first and second polarizers, respectively Respectively. As the backlight unit, we used the backlight actual spectrum data on the Samsung 46-inch LCD TV PAVV (LTA460HR0).

The above optical components were stacked as shown in FIG. 1 (a), and the visual sensitivity all-round transmission was simulated. As a result, the results shown in FIG. 7 were obtained. The change of the polarization state at the reference time (θ = 60 °, Φ = 45 °) of the present invention is shown in FIG. 8, and the change of the polarization state at 550 nm is shown in FIG. 8. When passing through the second polarizer 11 on the Poincare Sphere, The state is 1, the polarized state is 2 when the polarized light passes through the liquid crystal cell when the polarized light passes through the second retardation film 14, and the polarized state is 3 when the polarized light passes through the first polarized film 24.

FIG. 7 shows the distribution of the visual sensitivity omnidirectional transmittance when displaying the black on the screen. The transmittance in the range of scale is 0% to 0.05%. In the case where the degree of transparency is 0.05% , And areas with low permeability are indicated in blue. At this time, as the range of the blue color in the center becomes wider, it is possible to secure a wide viewing angle by showing a wide viewing angle.

This confirmed that the polarizing plate (I Plus Pol configuration, Dongwoo Fine-Chem, Korea) for the plane switching liquid crystal display exhibited a better viewing angle compensation effect than the case of FIG. 9 showing the visual sensitivity for all directions when applied to the liquid crystal mode of the present invention.

Example 2

The second retardation film 14 had a front retardation (R0) of 2.0 nm and a thickness retardation (Rth) of 300 nm at 589.3 nm, and the first retardation film (24) had a front retardation value (R0) of 55 nm and a refractive index ratio (NZ) of -5.9 to prepare a blue liquid crystal liquid crystal display device.

10 shows the distribution of the visual sensitivity omnidirectional transmittance when the black is displayed on the screen. In the range of scale, the transmittance is in the range of 0% to 0.05%, the portion in which the transmittance exceeds 0.05% Areas with low permeability are indicated in blue. At this time, as the range of the blue color in the center becomes wider, it is possible to secure a wide viewing angle by showing a wide viewing angle.

It was also confirmed that the polarizing plate (I Plus Pol configuration, Dongwoo Fine-Chem, Korea) for plane switching liquid crystal displays exhibits a viewing angle compensation effect which is equivalent to that of FIG. 9, which shows the visibility all-round transmission when the liquid crystal mode of the present invention is applied .

Fig. 11 shows the optical compensation principle of the second embodiment in a pouincure diagram, Fig. 8 of the first embodiment shows the optical compensation principle of the first embodiment on a pouincere diagram, And the optical characteristics are not improved by the first and second retardation films 14 and 24 alone. Optimum for the optical properties of the second retardation film 14 is not limited to the first retardation film 14, The optical characteristics of the light guide plate 24 are determined.

Example 3

1B, the first protective film 23, the first polarizer 21, the first retardation film 24, and the blue phase (FIG. 1B) blue phase liquid crystal cell 30, a second retardation film 14, a second polarizer 11 and a second protective film 13 are arranged. The absorption axis 22 of the first polarizer 21 is perpendicular to the viewing side and the absorption axis 12 of the second polarizer 11 is parallel to the viewing direction of the first and second polarizers The absorption axes 22 and 12 of the first polarizer 21 and the absorption axis 22 of the first polarizer 21 are orthogonal to each other so that the slow axis 25 of the first retardation film 24 and the absorption axis 22 of the first polarizer 21 are arranged parallel to each other Respectively.

The second retardation film 14 has a front retardation value R0 of 2 nm and a thickness retardation value Rth of 90 nm at the wavelength of 589.3 nm and the retardation value Rth at the thickness direction of 90 nm And the first retardation film 24 had a front retardation (R0) of 140 nm and a refractive index ratio (NZ) of -0.11.

The wavelength dispersion property of the second retardation film 14 is 0.862, which is the front retardation (wavelength 380 nm) / front retardation (wavelength 780 nm) = [RO (380 nm) / RO (Wavelength 380 nm) / front phase difference (wavelength 780 nm) = [RO (380 nm) / RO (780 nm)] is 1.197 and the wavelength dispersion of the first retardation film 24 is 6 shows the wavelength dispersion degree of the propagation field.

As shown in FIG. 12, the optical components were stacked as shown in FIG. 1 (b) and the visual sensitivity all-round transmission was simulated. The change of the polarization state at the reference time (θ = 60 °, Φ = 45 °) of the present invention is shown in FIG. 13, and the change of the polarization state at 550 nm is shown in FIG. The state is 1, the polarized state is 2 when the polarized light passes through the liquid crystal cell when the polarized light passes through the first retardation film 24, and the polarized state is 3 when the polarized light passes through the second polarized film 14.

12 shows the distribution of the visual sensitivity omnidirectional transmittance in the case of displaying on the screen the transmittance in the range of 0% to 0.05% in the scale, the portion in which the transmittance in excess of 0.05% Areas with low permeability are indicated in blue. At this time, as the range of the blue color in the center becomes wider, it is possible to secure a wide viewing angle by showing a wide viewing angle.

This confirmed that the polarizing plate (I Plus Pol configuration, Dongwoo Fine-Chem, Korea) for the plane switching liquid crystal display exhibited a better viewing angle compensation effect than the case of FIG. 9 showing the visual sensitivity for all directions when applied to the liquid crystal mode of the present invention.

Example 4

The second retardation film 14 has a front retardation value R0 of 2.0 nm and a thickness retardation value Rth of 300 nm at a wavelength of 589.3 nm in the same manner as in Example 3, Nm and the first retardation film 24 had a front retardation value R0 of 55 nm and a refractive index ratio NZ of -5.9 to prepare a blue liquid crystal liquid crystal display device.

FIG. 14 shows the distribution of the visual sensitivity all-round transmission when displaying the black on the screen, and it was confirmed that it is possible to secure a wide viewing angle. Fig. 15 shows a change in the polarization state at a wavelength of 550 nm at the reference time (? = 60 deg.,? = 45 deg.) Of the present invention.

Example 5

The second retardation film 14 had a front retardation value R0 of 2.0 nm and a thickness retardation value Rth of 141 nm at 589.3 nm, (24) had a front retardation value (R0) of 99 nm and a refractive index ratio (NZ) of -1.0 to prepare a blue liquid crystal liquid crystal display device.

The forward visibility transmittance of the above configuration is shown in Fig. Fig. 17 shows a change in polarization state at a wavelength of 550 nm at the reference time (? = 60 deg.,? = 45 deg.) Of the present invention.

Example 6

The second retardation film 14 had a front retardation (R0) of 2 nm and a thickness retardation (Rth) of 110 nm at 589.3 nm, and the first retardation film (24) had a front retardation value (R0) of 110 nm and a refractive index ratio (NZ) of -0.5 to prepare a blue liquid crystal liquid crystal display device.

The visual sensitivity omnidirectional transmittance of the above configuration is shown in Fig. Fig. 19 shows a change in the polarization state at a wavelength of 550 nm at the reference time (? = 60 deg.,? = 45 deg.) Of the present invention.

Comparative Example 1

The optical characteristics of the second retardation film 14 and the first retardation film 24 were the same as those of the first embodiment except that the optical characteristics were normal TAC (front retardation value R0 = 2 nm, thickness retardation value Rth = 52 nm) were disposed to fabricate a blue liquid crystal liquid crystal display device.

The result of the visual sensitivity transmission test of the liquid crystal display device was shown in FIG. 20, and it was confirmed that the viewing angle was narrow due to the high inclined plane transmittance in the black state as shown in FIG.

Comparative Example 2

0-TAC, which is commonly used in a low-cost surface switching liquid crystal display device, is applied to the first and second retardation films 14 and 24 (the front retardation value R0 = 1 nm, the thickness retardation value (Rth) = 2 nm) to prepare a blue liquid crystal liquid crystal display device.

FIG. 21 shows the result of simulation of the visual sensitivity of the liquid crystal display device, and it was confirmed that the viewing angle was narrow due to the high inclined plane transmittance in the black state as shown in FIG.

Comparative Example 3

A blue liquid crystal display device was manufactured in the same manner as in Example 1 except that the slow axis 25 of the first retardation film 24 and the absorption axis 22 of the first polarizer 21 were orthogonal to each other .

The results of the visual sensitivity transmission of the liquid crystal display device were shown in FIG. 22, and it was confirmed that the viewing angle was narrow due to the high inclined plane transmittance in the black state as shown in FIG.

Comparative Example 4

The second retardation film 14 had a front retardation (R0) of 2 nm and a thickness retardation (Rth) of 50 nm at 589.3 nm, and the first retardation film (24) had a front retardation value (R0) of 55 nm and a refractive index ratio (NZ) of -2.1 to prepare a blue liquid crystal liquid crystal display device.

The result of simulation of the visual sensitivity transmission of the liquid crystal display device is shown in FIG. 23, and it was confirmed that the viewing angle was narrow due to the high inclined plane transmittance in the black state as shown in FIG. 23 below.

Comparative Example 5

The second retardation film 14 had a front retardation (R0) of 2 nm and a thickness retardation (Rth) of 50 nm at 589.3 nm, and the first retardation film (24) had a front retardation value (R0) of 55 nm and a refractive index ratio (NZ) of -8 to prepare a blue liquid crystal liquid crystal display device.

FIG. 24 shows the results of the visual sensitivity transmission test of the liquid crystal display device, and it was confirmed that the oblique plane transmittance was high in the black state as shown in FIG. 24, so that the viewing angle was narrow.

Comparative Example 6

The second retardation film 14 had a front retardation (R0) of 2 nm and a thickness retardation (Rth) of 350 nm at 589.3 nm, and the first retardation film (24) had a front retardation value (R0) of 170 nm and a refractive index ratio (NZ) of -0.3 to prepare a blue liquid crystal liquid crystal display device.

The results of the visual sensitivity transmission test of the liquid crystal display device are shown in FIG. 25, and it was confirmed that the oblique plane transmittance was high in the black state as shown in FIG. 25, so that the viewing angle was narrow.

As described above, the blue liquid crystal liquid crystal display device according to the present invention can provide a wide viewing angle and can be applied to a large-screen liquid crystal display device requiring a high optical level.

1 is a perspective view showing a structure of a liquid crystal display device according to the present invention,

FIG. 2 is a schematic view for explaining the refractive index of the retardation film according to the present invention,

3 is a schematic view showing the MD direction in the manufacturing process for explaining the stretching direction of the retardation film and the polarizing plate according to the present invention,

FIG. 4 is a schematic view for explaining the expression of? And? In the coordinate system of the present invention,

5 is a graph showing the propagation wavelength dispersion of the second retardation film used in Example 1,

6 is a graph showing the propagation wavelength dispersion of the first retardation film used in Example 1,

FIG. 7 is a simulation result of the visual sensitivity of the first embodiment according to the present invention,

8 shows the change in the polarization state of light coming out in the direction of the inclined plane (? = 60 °,? = 45 °) in Embodiment 1 of the present invention on the Poincare Sphere,

9 is a result of simulating the visual sensitivity all-round transmission when the compound polarizing plate set for a planar switching liquid crystal display is applied to the liquid crystal mode of the present invention,

10 is a simulation result of the visual sensitivity of the second embodiment according to the present invention,

11 shows the change in the polarization state of light coming out in the direction of the inclined plane (? = 60 占? = 45 占) according to Embodiment 2 of the present invention on a Poincare Sphere,

12 is a simulation result of the visual sensitivity of the third embodiment according to the present invention,

13 shows the change in polarization state of light coming out in the direction of the inclined plane (? = 60 占? = 45 占) according to Embodiment 3 of the present invention on a Poincare Sphere,

14 is a simulation result of the visual sensitivity of the fourth embodiment according to the present invention,

Fig. 15 shows the change in polarization state of light coming out in the direction of the inclined plane ([theta] = 60 DEG, [phi] = 45 DEG) in the fourth embodiment of the present invention on the Poincare Sphere,

16 is a simulation result of the visual sensitivity of the fifth embodiment according to the present invention,

FIG. 17 shows the change in the polarization state of light in the direction of the inclined plane (? = 60 占? = 45 占 in the fifth embodiment of the present invention on the Poincare Sphere,

18 is a result of simulating the visual sensitivity of the sixth embodiment according to the present invention,

19 shows the change in polarization state of light coming out in the direction of the inclined plane (? = 60 占? = 45 占) according to Embodiment 6 of the present invention on a Poincare Sphere,

20 is a simulation result of the visual sensitivity all-round transmission of Comparative Example 1 of the present invention,

21 is a simulation result of the visual sensitivity all-round transmission of Comparative Example 2 of the present invention,

22 is a result of simulating the visibility all-round transmission of Comparative Example 3 of the present invention,

23 is a result of simulating the visual sensitivity all-round transmission of Comparative Example 4 of the present invention,

24 is a result of simulating the visual sensitivity all-round transmission of Comparative Example 5 of the present invention,

25 shows the result of simulating the visibility omnidirectional transmittance of Comparative Example 6 of the present invention.

Claims (9)

A first composite polarizing plate, a second composite polarizing plate, and a blue liquid crystal cell interposed therebetween, The first complex polarizer plate and the second complex polarizer plate each comprise a retardation film, a polarizer, and a protective film, The retardation film of the first composite polarizing plate has a front retardation (R0) of 50 to 150 nm at a wavelength of 589 nm and a refractive index ratio (NZ) of -6.0 to -0.1, and the slow axis is parallel to the absorption axis of the adjacent polarizer Lt; / RTI & The retardation film of the second composite polarizing plate has a front retardation (R0) of 0 to 10 nm and a thickness retardation (Rth) of 80 to 310 nm at a wavelength of 589 nm and no slow axis. The liquid crystal display of claim 1, wherein the retardation film of the first complex polarizing plate has a front retardation (R0) of 80 to 150 nm and a refractive index ratio (NZ) of -2.0 to -0.1. The liquid crystal display of claim 1, wherein the retardation film of the first complex polarizing plate has a front retardation (R0) of 100 to 150 nm and a refractive index ratio (NZ) of -1.0 to -0.1. The liquid crystal display of claim 1, wherein the retardation film of the second composite polarizing plate has a front retardation (R0) of 0 to 5 nm and a thickness retardation (Rth) of 80 to 200 nm. The liquid crystal display of claim 1, wherein the retardation film of the second composite polarizing plate has a front retardation (R0) of 0 to 3 nm and a thickness retardation (Rth) of 80 to 140 nm. The method of claim 1, wherein the retardation film and the protective film of the first and second complex polarizers are independently selected from the group consisting of triacetylcellulose (TAC), cycloolefin polymer (COP), cycloolefin copolymer (COC) Wherein the liquid crystal display device is one selected from the group consisting of polyethylene terephthalate (PET), polypropylene (PP), polycarbonate (PC), polysulfone (PSF), and polymethylmethacrylate (PMMA) . delete The liquid crystal display of claim 1, wherein the blue liquid crystal cell is an array of cylinders in which blue liquid crystal molecules are twisted in a three-dimensional spiral shape. The liquid crystal display of claim 1, wherein the blue liquid crystal mode liquid crystal display device satisfies a compensation relationship of visible transmittance of 0.05% or less at an oblique angle (? = 60 °,? = 45 °).

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