KR20110016211A

KR20110016211A - Wideviewing vertical align liquid crystal display

Info

Publication number: KR20110016211A
Application number: KR1020090073806A
Authority: KR
Inventors: 김봉춘
Original assignee: 동우 화인켐 주식회사
Priority date: 2009-08-11
Filing date: 2009-08-11
Publication date: 2011-02-17

Abstract

The present invention relates to a wide viewing angle vertical alignment mode liquid crystal display device, and more particularly, a vertical alignment liquid crystal cell and a liquid crystal cell having different cell gaps according to wavelength regions of red, green, and blue. A vertical alignment mode liquid crystal display device comprising a negative biaxial A plate designed to have specific optical properties on upper and lower polarizing plates. In the vertical alignment mode liquid crystal display according to the present invention, the contrast ratio (CR, white luminance / black luminance) on the inclined surface is improved by controlling the phase difference path of the optical element to secure a wide viewing angle. Improvement effect is remarkably excellent, the actual mass production and implementation is easy, there is an effect that can be mass-produced.

Description

Wide viewing angle vertical alignment mode liquid crystal display {WIDEVIEWING VERTICAL ALIGN LIQUID CRYSTAL DISPLAY}

The present invention relates to a wide viewing angle vertical alignment mode liquid crystal display device including a vertical alignment liquid crystal cell having a different cell gap according to a wavelength region and a negative biaxial A plate designed to have specific optical characteristics on upper and lower polarizing plates of the liquid crystal cell. will be.

Liquid crystal display (LCD) is widely used as a popular image display device. However, despite its many excellent features, a narrow viewing angle is pointed out as a representative disadvantage.

In the early stages of development, liquid crystal displays showed a distorted image on the inclined surface rather than the front due to the narrow viewing angle. However, the present invention can realize a certain degree of image quality even on the inclined surface by applying a phase difference film. In addition, the development of the liquid crystal mode technology has emerged a liquid crystal mode capable of realizing a wide viewing angle technology without using a retardation film.

A liquid crystal display device having a retardation film combined with a liquid crystal mode can realize a good image quality that is not comparable with that of an early liquid crystal display device. However, since the phase difference of the optical elements used in the liquid crystal display has different phase difference values depending on the wavelength, it is difficult to realize perfect black according to the viewing angle. In addition, when the optical device is applied to the large-size liquid crystal display device which is a current trend, there is a problem that the screen of the liquid crystal display device looks like a stain. The most representative optical elements associated with this problem are liquid crystals and retardation films.

Optical devices have been developed to control the wavelength dispersion to have the same phase difference (unit: wavelength, flat wavelength dispersion) according to the wavelength in the visible light region. However, until now, the method of controlling the wavelength dispersion of an optical device has a method of orthogonal overlapping the slow axis of a film having different dispersibility, a method of controlling a polymer array, and blending a polymer having heterogeneous optical properties. The method of showing wavelength dispersion is proposed. That is, it is difficult to control the wavelength dispersion of an optical device in a conventional single polymer state commercially available. Even if control is possible, the reality is that it has various limitations such as technical and economic to apply to actual mass production.

Meanwhile, the vertical alignment mode (VA Mode) is a representative wide viewing angle liquid crystal driving mode. In the vertical alignment mode, liquid crystals having negative dielectric anisotropy are injected between upper and lower substrates, and black is formed by arranging them vertically in an unapplied state of an electric field. White is realized by laying down a liquid crystal having negative dielectric anisotropy by applying an electric field vertically and vertically. In the vertical alignment mode, there is little effect of the phase difference caused by the liquid crystal in the black state in the front, so that a full black can be realized. Therefore, the LCD having the highest front contrast ratio is the highest. However, since the change in polarization state due to liquid crystal is severe on the inclined surface, a retardation film (compensation film) for securing a wide viewing angle is required.

In the vertical alignment mode liquid crystal display, compensation for polarization state on an inclined surface is required to secure a wide viewing angle. However, a compensation method for controlling wavelength dispersion of optical elements, which is difficult to mass-produce, is currently used. Therefore, there is an urgent need for the development of a liquid crystal display device that can be substantially mass-produced and implemented and manufactured by a roll-to-roll process.

The present invention includes a negative biaxial A plate designed to have specific optical characteristics in a vertical alignment liquid crystal cell and a top plate and a bottom polarizer having different cell gaps according to wavelengths of red, green, and blue. To improve the contrast ratio (CR, white luminance / black luminance) on the inclined surface by controlling the phase difference path of the optical element, and to provide a vertical alignment mode liquid crystal display device that can be easily mass-produced and implemented and can be mass-produced. do.

The present invention comprises a polarizing plate laminated in the order of a negative biaxial A plate, a polarizer and a protective film in the upper and lower plates, respectively, from the liquid crystal cell side, wherein the liquid crystal cell has a red (R) cell gap ≥ green (G) cell gap ≥ blue (B) satisfies the cell gap (except when red (R) cell gap = green (G) cell gap = blue (B) cell gap), and either of the negative biaxial A plates of the upper and lower polarizers is ground The negative biaxial A plate, whose axis is arranged parallel to the absorption axis of the adjacent polarizer, the other slow axis is perpendicular to the absorption axis of the adjacent polarizer, and the slow axis is disposed parallel to the absorption axis of the adjacent polarizer, A negative biaxial A plate having a front retardation value of 50 to 90 nm, a refractive index ratio of 1 <NZ ≤ 3, and a slow axis disposed perpendicular to the absorption axis of the adjacent polarizer has a front retardation value of 60 to 100 nm and a refractive index ratio of 3 ≤ NZ. ≤5 It said, provides that each polarization state is based on the angle formed puang curry sphere origin in the immediately preceding pass through the polarizer of the upper polarizing plate 380nm and 780nm wavelength of 30 ° or less vertically aligned mode liquid crystal display device.

The vertical alignment mode liquid crystal display according to the present invention has a low luminance in a black state in an oblique direction (θ = 60 °, Φ = 45 °), thereby achieving a contrast ratio (white luminance / black luminance) of 100: 1 or more. It is possible to secure a wide viewing angle because it is clear and the front viewing angle is excellent. In addition, since the vertical alignment mode liquid crystal display device does not require a specific optical element whose wavelength dispersion is difficult to be actually produced and implemented, the mass production process can be easily performed.

The present invention provides a negative biaxiality designed to have specific optical characteristics in a vertical alignment liquid crystal cell having a cell gap different according to a wavelength region of red, green, and blue, and upper and lower polarizing plates of the liquid crystal cell. A vertical alignment mode liquid crystal display including an A plate.

The vertical alignment mode liquid crystal display device of the present invention includes an upper polarizing plate, a vertical alignment liquid crystal cell, and a lower polarizing plate. Each upper and lower polarizing plate is laminated in the order of a negative biaxial A plate, a polarizer, and a protective film from the liquid crystal cell side.

As used herein, the term “negative biaxial A plate” refers to a positive biaxial optical element whose refractive index distribution satisfies Nx> Ny> Nz, and is also referred to as a “negative B plate”. Positive biaxial optical elements are optical elements whose refractive index increases in the stretching direction.

The slow axes of the negative biaxial A plates included in the upper and lower polarizing plates are arranged parallel to each other. In either of the negative biaxial A plates of the upper and lower polarizing plates, the slow axis is disposed in parallel with the absorption axis of the adjacent polarizer. The other is that the slow axis is disposed perpendicular to the absorption axis of another adjacent polarizer.

In addition, the polarizer absorption axis of an upper polarizing plate and the polarizer absorption axis of a lower polarizing plate are comprised so that they may mutually orthogonally cross.

The negative biaxial A plate, in which the absorption axis and the slow axis of adjacent polarizers are parallel, has a front phase difference value (RO) of 50 to 90 nm, a refractive index ratio (NZ) of 1 <NZ≤3, and an absorption axis and a slow axis of adjacent polarizers. This orthogonal negative biaxial A plate has an optical characteristic whose front retardation value RO is 60-100 nm.

Optical characteristics of the retardation film is a range that can be easily implemented without incurring a large process cost.

The negative biaxial A plate of the upper and lower polarizing plates can be used regardless of the forward wavelength dispersion or the reverse wavelength dispersion. However, it is not easy to manufacture a plate having a perfect reverse wavelength dispersion in a practical negative biaxial A plate. Therefore, the negative biaxial A plate of the present invention has a front phase difference value (wavelength 380 nm, phase difference unit is nm) / front phase difference value (wavelength 780 nm, phase difference unit is nm) [RO (380 nm) / RO (780 nm)]> 0.5 Can be used.

The negative biaxial A plate of the upper plate and the lower plate polarizing plate can be applied without being limited to the material as long as the optical properties defined in the present invention are satisfied. Specifically, triacetyl cellulose (TAC), cycloolefin polymer (COP), cycloolefin copolymer (COC), polyethylene terephthalate (PET), polypropylene (PP), polycarbonate (PC), polysulfone (PSF) and poly Methyl methacrylate (PMMA) can be used that is prepared from the one selected from the group consisting of.

The optical characteristics of the negative biaxial A plate used for the phase difference control of the liquid crystal display device are defined by Equations 1 to 3 for all wavelengths in the visible light region. In general, the optical properties of the retardation film are represented by the optical properties of 589.3 nm which can be most easily obtained when there is no mention of the wavelength of the light source. 3 is a schematic diagram for explaining the refractive index of the retardation film, where Nx is the refractive index of the axis having the largest refractive index in the in-plane direction, Ny is the vertical direction of Nx in the in-plane direction, and Nz represents the refractive index in the thickness direction. The magnitude of this refractive index determines the optical properties. The negative biaxial A plate has two optical axes in which the phase difference does not occur when the refractive indices of the three axial directions are different from each other.

Rth = [(Nx + Ny) / 2-Nz] × d

(Where Nx and Ny are plane refractive indices Nx ≧ Ny, Nz represents the thickness direction refractive index of the film, and d represents the thickness of the film)

R0 = (Nx-Ny) × d

(Where Nx and Ny are planar refractive indices Nx ≧ Ny, and d represents the thickness of the film)

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

(Where Nx and Ny are planar refractive indices and Nx ≧ Ny and Nz represent the thickness direction refractive indices of the film)

Rth of Equation 1 is a thickness retardation value representing the difference in refractive index in the thickness direction with respect to the in-plane average refractive index, R0 of Equation 2 is a front phase that is a substantial phase difference when light passes through the normal direction (vertical direction) of the film Phase difference value. In addition, NZ in Equation 3 is a refractive index ratio to distinguish the type of plate used as a retardation film accordingly.

In the vertically aligned liquid crystal cell of the present invention, when the electric field is not applied, the long axis of the liquid crystal is arranged in the vertical orientation (thickness direction). When the electric field is applied, the long axis of the liquid crystal is laid in the in-plane direction to display an image. When the liquid crystal is negative dielectric anisotropy, the direction of the applied electric field is vertical (thickness direction). In the case of positive dielectric constant anisotropy, the direction of the electric field is applied in the in-plane direction.

The liquid crystal cell maintains the thickness direction retardation value Rth at -250 to -350 nm, preferably at -290 to -320 nm at a wavelength of 589.3 nm when no electric field is applied. The thickness direction retardation value Rth of the vertically aligned liquid crystal cell is determined by the refractive index anisotropy of the liquid crystal and the cell gap. This affects the transmittance, color, and response speed of the liquid crystal display, so it is better to select an appropriate range.

The liquid crystal cell sets different cell gaps according to red, green, and blue, which is commonly referred to as a 'multi-cell gap'. The multi-cell gap may have a step according to red, green, and blue to represent a difference in cell gap. Since the multi-cell gap differs in step according to each wavelength, the path of the phase difference, especially the length of the phase difference can be adjusted on the Puan Karegu.

The liquid crystal cell satisfies a red (R) cell gap ≥ green (G) cell gap ≥ blue (B) cell gap. In this case, the red (R) cell gap, the green (G) cell gap, and the blue (B) cell gap are the same. Specifically, the red (R) cell gap: the green (G) cell gap: the blue (B) cell gap maintains a range of 1.2 to 1: 1: 0.8 to 1, and the red (R) cell with respect to the green (G) cell gap. In the case where the ratio of the gap exceeds 0.8 and the ratio of the blue (B) cell gap to the green (G) cell gap is less than 0.8, dispersibility may increase, so it is preferable to maintain the above range.

The polarization state due to the liquid crystal on the inclined surface of the liquid crystal display device depends on the thickness direction retardation value Rth of the liquid crystal cell. The change of polarization state is the thickness of each red (R) cell gap, green (G) cell gap and blue (B) cell gap of the liquid crystal cell and the front phase difference value which is the optical property of the negative biaxial A plate located on both sides of the liquid crystal cell. Compensation is possible by optimizing R0 and the refractive index ratio NZ.

The liquid crystal display of the present invention includes aligning liquid crystals into multi-domains or dividing the liquid crystals into multiple regions by a voltage applied thereto. The liquid crystal display is classified into a multi-domain vertical alignment (MVA), a patterned vertical alignment (PVA), a super PVA (SPVA), and the like according to a mode of an active matrix driving electrode including an electrode pair. They are included in the vertical alignment mode liquid crystal display device of the present invention because the liquid crystal alignment state of the black state is the same.

In the polarizers of the lower polarizing plate and the upper polarizing plate of the liquid crystal display according to the present invention, a polyvinyl alcohol (PVA) layer, which is a polarizer provided with a polarizing function through stretching and dyeing, is positioned. In the polyvinyl alcohol (PVA) layer of the lower polarizing plate and the polyvinyl alcohol (PVA) layer of the upper polarizing plate, protective films are positioned on opposite sides of the liquid crystal cell. The protective film of the lower polarizing plate and the protective film of the upper polarizing plate are not particularly limited in the present invention because the optical properties due to the difference in refractive index do not affect the viewing angle.

Materials for forming the protective film of the upper plate and the lower plate polarizing plate may be applied to those commonly used in the art independently of each other. Specifically, triacetyl cellulose (TAC), cycloolefin polymer (COP), cycloolefin copolymer (COC), polyethylene terephthalate (PET), polypropylene (PP), polycarbonate (PC), polysulfone (PSF) and poly Any one prepared from the group consisting of materials including methyl methacrylate (PMMA) and the like can be used.

As described above, the viewing angle compensation of the present invention is not a concept of controlling wavelength dispersion of the liquid crystal display using an optical device having a conventional reverse wavelength dispersion. The present invention considers each characteristic of the optical elements, and optimally adjusts the paths of the Poang Kare spherical phases by these optical elements to realize viewing angle compensation. That is, it is possible to manufacture a vertical alignment mode liquid crystal display having excellent viewing angle compensation effect without applying an optical element having reverse wavelength dispersion, which is difficult to mass produce and implement.

The wavelength dispersion of the liquid crystal display according to the present invention will be described as a change in the polarization state of the Pohang Care sphere.

When viewed in an inclined direction (θ = 60 °, Φ = 45 °), the polarization state at the wavelength of 380 nm and 780 nm of the liquid crystal display is represented by two points on the surface of the Poincare Sphere. If the two points and the origin are connected in the Poang Karé sphere, it is represented by the figure as shown in FIG. At this time, the distance between the two points means the difference in polarization state according to the wavelength, and the distance between the two points is widened just before passing through the polarizer of the upper polarizing plate in the oblique direction (θ = 60 °, Φ = 45 °). Image quality is poor.

Specifically, the polarization state of the wavelength 380nm on the Pangareg sphere is represented by the x, y, z rectangular coordinate system, and the polarization state of the wavelength 780nm is represented by the x ', y', z 'rectangular coordinate system. Since the Poincare Sphere has a radius of 1, half of the distance between two points representing the polarization state of wavelength 380nm and wavelength 780nm (1/2), and half of the angle connecting the two points with the origin of the coordinate system (1). / 2) is expressed by Equation 4 below. At this time, the angle represented by the following Equation 5 represents the degree of wavelength dispersion and becomes larger as it passes through each optical element, and becomes maximum just before passing through the polarizer of the upper plate.

The 380 nm and 780 nm correspond to the maximum and minimum values of the visible light region and are wavelengths most clearly showing dispersion characteristics of the optical device. The angle between any two wavelengths present between the 380 nm and 780 nm wavelengths is always smaller than the angle formed at the 380 nm and 780 nm wavelengths so that the angle formed at the 380 nm and 780 nm wavelengths is the maximum of the angles in the visible range. Therefore, it is possible to clearly present the optical characteristics of the liquid crystal display only by the angle between 380nm and 780nm.

The angle formed between the wavelengths of 380 nm and 780 nm on the Pohang Care sphere of the present invention is preferably 30 ° or less (0 to 30 °), preferably 27 ° or less.

In addition, the liquid crystal display according to the present invention satisfies the compensation relationship of the visibility transmittance of 0.05% or less, preferably 0.03% or less in the inclination direction (θ = 60 °, Φ = 45 °). The contrast ratio (CR, white luminance / black luminance) is maintained at 100: 1 or more, preferably 150: 1 or more, and more preferably 200: 1 or more at (θ = 60 ° and Φ = 45 °). As described above, the liquid crystal display according to the present invention has a contrast ratio of 100: 1 or more in the inclined direction (θ = 60 °, Φ = 45 °). : It shows an improved effect compared to 1 or more, and can be confirmed to have an improvement effect of up to 3 times or more.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 and 2 are perspective views illustrating the basic structure of a vertical alignment mode liquid crystal display according to the present invention.

In the vertical alignment mode liquid crystal display according to the present invention, the backlight unit 40, the lower polarizer 10, the liquid crystal cell 30, and the upper polarizer 20 are stacked. The lower and upper polarizing plates are formed by laminating the negative biaxial A plates 14 and 24, the polarizers 11 and 21, and the protective films 13 and 23 from the liquid crystal cell.

The optical properties of the negative biaxial A plate are determined by the relationship between the absorption axis of the adjacent polarizer and the slow axis of the negative biaxial A plate. Specifically, FIG. 1 shows that the absorption axis 22 of the polarizer 21 of the upper polarizer 20 and the slow axis 25 of the negative biaxial A plate 24 are parallel to each other, and the polarizer 11 of the lower polarizer 10 is parallel. The absorption axis 12 of and the slow axis 15 of the negative biaxial A plate 14 are configured to be orthogonal. 2 shows that the absorption axis 22 of the polarizer 21 of the upper polarizing plate 20 and the slow axis 25 of the negative biaxial A plate 24 are perpendicular to each other, and the absorption of the polarizer 11 of the lower polarizing plate 10 is performed. The axis 12 and the slow axis 15 of the negative biaxial A plate 14 are configured to be parallel.

The negative biaxial A plate, in which the absorption axis and the slow axis of the adjacent polarizers are orthogonal, has a front phase difference value RO of 60 to 100 nm and a refractive index ratio NZ of 3 ≦ NZ ≦ 5. The negative biaxial A plate, in which the absorption axis and the slow axis of the adjacent polarizers are parallel, has a front retardation value RO of 50 to 90 nm, and a refractive index ratio NZ maintains 1 <

The absorption axis 12 of the lower polarizing plate 10 and the absorption axis 22 of the upper polarizing plate 20 are arranged perpendicular to each other.

The polyvinyl alcohol (PVA) layers 11 and 21 are positioned on the lower polarizer 10 and the upper polarizer 20, and the polyvinyl alcohol (PVA) layer 11 of the lower polarizer and the polyvinyl alcohol of the upper polarizer ( In the PVA layer 21, protective films 13 and 23 are positioned on opposite sides of the liquid crystal cell 30. At this time, the protective film 13 of the lower polarizing plate 10 and the protective film 23 of the upper polarizing plate 20 are not particularly limited in the present invention because the optical properties according to the refractive index does not affect the viewing angle.

The upper polarizing plate and the lower polarizing plate of the present invention are manufactured by applying a roll to roll method which is easy to mass produce. 4 is a schematic diagram illustrating an MD direction in a roll-to-roll manufacturing process, which will be described below with reference to this.

The upper and lower polarizing plates are manufactured in the form of a polarizing plate by combining a polarizer, a retardation film and a film having various optical functions. In this case, each optical film exists in a roll state before being bonded to the composite polarizing plate. The direction in which the film is unwound or wound in the roll is called MD direction. In the polarizer, the protective layer does not affect the optical properties, so roll to roll bonding is possible. The polarizer aligns the PVA in the MD direction and dyes iodine through the MD direction drawing in the PVA fabric used as the material of the polarizer to give the polarization function, so that the absorption direction of the light becomes the MD direction.

Since the direction of the slow axis varies according to the manufacturing method of the negative biaxial A plate of the present invention, the film fabric of the negative biaxial A plate is prepared in consideration of this. Specifically, the negative biaxial A plate of the present invention has a positive refractive index characteristic of increasing refractive index with respect to the stretching direction, and can be implemented through two stretching in a plane perpendicular to the MD direction and the MD direction. The negative biaxial A plate is manufactured by stretching the retardation film fabric more in the planar vertical direction in the MD direction than in the MD direction when the absorption axis and the slow axis of the adjacent polarizer are orthogonal. On the contrary, when the absorption axis and the slow axis of the adjacent polarizers are parallel to each other, the fabric of the retardation film may be prepared by stretching more in the MD direction than in the plane vertical direction in the MD direction. The negative biaxial A plate manufactured as described above may apply a roll to roll process in manufacturing a polarizing plate.

In the present invention, the absorption axis of the polarizer of the lower polarizing plate should be located in the vertical direction when viewed from the viewer side. Specifically, when the absorption axis of the lower polarizing plate close to the backlight unit is in the vertical direction, light passing through the lower polarizing plate is polarized in the horizontal direction. When the voltage of the panel passes through the liquid crystal cell to which the voltage is applied, the light is in the vertical direction, and the light passes through the upper polarizing plate on the viewer's side where the absorption axis is horizontal. The light passed in this way can be perceived by a person wearing polarized sunglasses (usually the absorption axis is horizontal) on the viewer's side, so that the image is visible. However, when the absorption axis of the lower polarizing plate close to the backlight unit is in the horizontal direction, a person wearing polarized sunglasses has a problem in that the image is not visible to him.

The large liquid crystal display is manufactured in the form of 4: 3 or 16: 9 except for a special case in order to make the image visible from the viewer side. This considers that the human field of view is wider in the horizontal direction than in the vertical direction.

In the vertical alignment mode liquid crystal display according to the present invention, the phase difference is controlled by using the change of the polarization state on the Poincare Sphere of the liquid crystal cell and the negative biaxial A plate. Poincare Sphere is a very useful way of expressing the change in polarization state at a particular point of view. This may indicate a change in polarization state when light traveling at a specific time passes through each optical element in the liquid crystal display device in a liquid crystal display device displaying an image by using Poincare Sphere polarization. In the present invention, the specific time is in the inclination direction in the range of θ = 60 °, Φ = 45 ° in the circular coordinate system shown in FIG. 5, the wavelength 380nm, the wavelength 780nm, and the brightest wavelength 550nm that humans feel are defined. The degree of wavelength dispersion can be confirmed based on 3 wavelengths.

In the following, the effect on the realization of the dark state at the viewing angle when the voltage is not applied by the above configuration is summarized in Examples and Comparative Examples. The invention can be better understood by the following examples, which are intended to illustrate the invention and are not intended to limit the scope of protection as defined by the appended claims.

Example

In Examples 1 to 5 and Comparative Examples 1 to 6, the effect was applied to the LCD simulation program TECH WIZ LCD 1D (man system, KOREA) to compare the wide viewing angle effect.

Example 1

Measurement data of each optical film, a liquid crystal cell, and a backlight according to the present invention were stacked on a TECH WIZ LCD 1D (man system, KOREA) with a structure as shown in FIG. 1. Referring to the structure of Figure 1 in detail.

The backlight unit 40 , the lower polarizing plate 10, the liquid crystal cell 30, and the upper polarizing plate 20 are sequentially stacked. The lower polarizing plate 10 is a negative biaxial A plate 14 and a polarizer from the liquid crystal cell side. (11) and the protective film 13 in this order. The absorption axis 12 of the polarizer 11 and the slow axis 15 of the negative biaxial A plate 14 were orthogonal to each other. The upper polarizing plate 20 is configured in the order of the negative biaxial A plate 24, the polarizer 21, and the protective film 23 from the liquid crystal cell side, and the absorption axis 22 and the negative biaxial A of the polarizer 21. The slow axis 25 of the plate 24 became parallel. The absorption axis 12 of the polarizer 11 of the lower plate polarizing plate 10 was positioned in the vertical direction when viewed from the viewing side.

At this time, the polarizer imparts the function of the polarizer through stretching and dyeing, and the absorption axes are arranged perpendicular to each other on both sides of the 46-inch vertically aligned liquid crystal cell.

As for the liquid crystal cell, a red (R) cell gap: a green (G) cell gap: a blue (B) cell gap had a ratio of 1.19: 1: 0.81, and a cell gap of G was 3.8 µm.

Each optical film and backlight used in the examples of the present invention was used to have the optical properties as follows.

First, the upper plate lower polarizer imparts a polarizer function by dyeing iodine on the stretched PVA, and the polarization performance of the polarizer is at least 99.9% visibility and at least 41% visibility in the visible region of 370 to 780 nm. The visibility polarization and the visibility single transmittance are the TD (λ) transmittance of the transmission axis according to the wavelength, and the transmittance correction of the absorption axis according to the wavelength of MD (λ) and the visibility correction value defined in JIS Z 8701: 1999.

Is defined by the following equations (6) to (10).

The optical characteristics caused by the difference in the internal refractive index according to the direction of each film is the negative biaxial A plate 14 of the lower polarizing plate 10 at a wavelength of 589.3 nm, the front retardation value (R0) is 80nm, the refractive index ratio (NZ) is 4 For the negative biaxial A plate 24 of the upper polarizing plate 20, a front retardation value R0 of 70 nm and a refractive index ratio NZ of 1.6 were used.

The negative biaxial A plate applied to the bottom plate used triacetyl cellulose (TAC). The front retardation wavelength dispersion was 0.862 with the front retardation value (wavelength 380 nm) / front retardation value (wavelength 780 nm) and used as the wavelength dispersion degree shown in FIG. The negative biaxial A plate applied to the top plate used a cycloolefin polymer (COP, Zeonor, Zeon, Japan). The front retardation wavelength dispersion of the front phase retardation value (wavelength 380 nm) / front phase retardation value (wavelength 780 nm) is 1.006 and used as the wavelength dispersion of the wavelength shown in FIG.

As the outer protective film of the upper and lower polarizers, triacetyl cellulose (TAC) having an optical characteristic of 50 nm in thickness direction retardation value (Rth) with respect to incident light 589.3 nm was used. As the backlight unit, actual spectrum data of the backlight mounted in the 46-inch LCD TV PAVV (LTA460HR0) of Samsung Electronics was used.

The optical components were stacked as shown in FIG. 1 and subjected to simulation of visibility omnidirectional transmittance. As a result, the results as shown in FIG. 9 were obtained. The change in polarization state at the reference time (θ = 60 °, Φ = 45 °) of the present invention is shown in FIG. 10. The polarization state is 1 when passing through the lower polarizer 11 on Poincare Sphere, the polarization state is 2 when passing through the negative biaxial A plate 14, and the polarization state is 3, when passing through the liquid crystal cell. When it passes through the negative biaxial A plate 24, the polarization state is polarized to four. Due to the liquid crystal cell and the retardation film having the constant wavelength dispersion, the wavelength with the longest path is 380 nm and the wavelength with the shortest path is 780 nm on Poincare Sphere.

FIG. 9 illustrates the visibility of an omnidirectional permeability distribution when the arm (BLACK) is displayed on the screen. The visibility of the omnidirectional transmittance ranges from 0% to 0.1% of the transmittance on the scale, and when the cancer is displayed, the area exceeding 0.1% is indicated in red, and the area of low transmittance is indicated in blue. In this case, the wider the range of blue in the center, the wider the viewing angle.

This is because the polarization state of the Poang Curé sphere as shown in FIG. 10 is shown in the inclined direction (θ = 60 °, Φ = 45 °). In the LCD, the polarization state 4 is represented as (0.886851, -0.38415, -0.25676) at a wavelength of 380 nm and (0.996131, -0.06442, 0.059775) at a wavelength of 380 nm in the Cartesian coordinate system on the Puan Curé sphere. The polarization state 4 at the wavelength of 380 nm and the wavelength of 780 nm was 26.77047 °.

Example 2

In the same manner as in Example 1, the lower polarizing plate 10 is parallel to the absorption axis 12 of the polarizer 11 and the slow axis 15 of the negative biaxial A plate 14, the upper polarizing plate 20 The absorption axis 22 of the silver polarizer 21 and the slow axis 25 of the negative biaxial A plate 24 were laminated in the configuration of FIG. 2 so as to be perpendicular to each other. The absorption axis 12 of the polarizer 11 of the lower plate polarizing plate 10 was positioned in the vertical direction when viewed from the viewing side.

At a wavelength of 589.3 nm, the negative biaxial A plate 14 of the lower plate polarizer 10 was applied with a TAC having a front retardation value R0 of 70 nm and a refractive index ratio NZ of 1.6. In the negative biaxial A plate 24 of the upper polarizing plate 20, a vertical alignment mode liquid crystal display device was manufactured by applying a COP having a front phase difference value R0 of 80 nm and a refractive index ratio NZ of 4.

At this time, the front retardation wavelength dispersion of the negative biaxial A plate 14 of the lower polarizing plate 10 has a front retardation value (wavelength 380 nm) / front phase retardation value (wavelength 780 nm) of 0.862, and the negative biaxial property of the upper polarizing plate 20. The front retardation wavelength dispersion of the A plate 24 used a front retardation value (wavelength 380 nm) / front phase retardation value (wavelength 780 nm) of 1.006.

The simulation results of the visibility of the vertical alignment mode LCD were obtained as shown in FIG. 11. This is because the polarization state of the Poang Curé sphere as shown in FIG. 12 is shown in the inclined direction (θ = 60 °, Φ = 45 °). In the LCD, the polarization state 4 is represented by (0.40347, -0.88682, 0.22529) at a wavelength of 380 nm and (0.13975, -0.97972, -0.14361) at a wavelength of 380 nm. It can be seen that the angle at which the polarization state 4 at the wavelength of 380 nm and the wavelength of 780 nm is based on the origin of the Poangaregu is 26.76424 °.

Example 3

In the same manner as in Example 1, the lower polarizing plate 10 is the absorption axis 12 of the polarizer 11 and the slow axis 15 of the negative biaxial A plate 14 is orthogonal, and the upper polarizing plate 20 The absorption axis 22 of the silver polarizer 21 and the slow axis 25 of the negative biaxial A plate 24 were laminated in the configuration of FIG. 1 so as to be parallel. The absorption axis 12 of the polarizer 11 of the lower plate polarizing plate 10 was positioned in the vertical direction when viewed from the viewing side.

The negative biaxial A plate 14 of the lower plate polarizing plate 10 used COP (Zeonor, ZEON, Japan) having a front retardation value R0 of 80 nm and a refractive index ratio NZ of 4 at a wavelength of 589.3 nm. In the negative biaxial A plate 24 of the upper polarizing plate 20, a TAC having a front retardation value R0 of 81 nm and a refractive index ratio NZ of 2 was disposed to manufacture a vertical alignment mode liquid crystal display device.

At this time, the front retardation wavelength dispersion of the negative biaxial A plate 14 of the lower polarizing plate 10 has a front retardation value (wavelength 380 nm) / front retardation value (wavelength 780 nm) of 1.006, and negative biaxiality of the upper polarizing plate 20. The front retardation wavelength dispersion of the A plate 24 used that the front retardation (wavelength 380 nm) / front retardation (wavelength 780 nm) is 0.862.

The simulation results of the visibility of the vertical alignment mode liquid crystal display were obtained as shown in FIG. 13. This is because the polarization state of the Poang Curé sphere as shown in Fig. 14 is changed in the inclined direction (θ = 60 °, Φ = 45 °). In the LCD, the polarization state 4 is represented as (0.88568, -0.44814, -0.12147) at a wavelength of 380 nm and (0.97598, -0.10536, 0.190714) at a wavelength of 380 nm in the Cartesian coordinate system on the Puan Cureg sphere. It can be seen that the angle at which the polarization state 4 at the wavelength of 380 nm and the wavelength of 780 nm is based on the origin of the Poang Karegu is 27.3215746 °.

Example 4

The negative biaxial A plate 14 of the lower polarizing plate 10 at a wavelength of 589.3 nm used COP (Zeonor, ZEON, Japan) having a front retardation R0 of 69 nm and a refractive index ratio NZ of 4. The negative biaxial A plate 24 of the upper polarizing plate 20 uses a vertical alignment mode liquid crystal display using COP (Zeonor, ZEON, Japan) having a front phase difference (R0) of 70 nm and a refractive index ratio (NZ) of 2. Prepared.

At this time, the front retardation wavelength dispersion of the negative biaxial A plate 14 of the lower polarizing plate 10 has a front retardation (wavelength 380 nm) / front retardation (wavelength 780 nm) of 1.006, and a negative biaxial A plate of the upper polarizing plate 20. Front phase difference wavelength dispersion of (24) used that the front phase difference (wavelength 380 nm) / front phase difference (wavelength 780 nm) is 1.006.

The simulation results of the visibility of the vertical alignment mode liquid crystal display were obtained as shown in FIG. 15. This is because the polarization state of the Poang Curé sphere as shown in Fig. 16 is changed in the inclined direction (θ = 60 °, Φ = 45 °). In the LCD, the polarization state 4 is represented as (0.9612338, -0.2340703, -0.1457419) at a wavelength of 380 nm and (0.99406331, 0.10572257, 0.0250738) at a wavelength of 380 nm. It can be seen that the angle at which the polarization state 4 at the wavelength of 380 nm and the wavelength of 780 nm is based on the origin of the Poang Karegu is 22.0228922 °.

Example 5

In the same manner as in Example 1, the liquid crystal cell has a ratio of red (R) cell gap: green (G) cell gap: blue (B) cell gap is 1: 1: 0.81, and the cell gap of G is 3.8. A micrometer was used.

The simulation results of the visibility of the vertical alignment mode liquid crystal display were obtained as shown in FIG. 17. This is because the polarization state of the Poang Curé sphere as shown in Fig. 18 is shown in the inclined direction (θ = 60 °, Φ = 45 °). In the LCD, the polarization state 4 is represented by (0.88685, -0.38415, -0.25676) at a wavelength of 380 nm and (0.981530, -0.10403, 0.16055) at a wavelength of 380 nm. It was confirmed that the angle at which the polarization state 4 at the wavelength of 380 nm and the wavelength of 780 nm is based on the origin of the Poang Karegu is 29.633 °.

Comparative Example 1

As for the liquid crystal cell, a red (R) cell gap: a green (G) cell gap: a blue (B) cell gap was 3.8 µm in the same manner.

The negative biaxial A plate 14 of the lower polarizing plate 10 has a front phase difference R0 of 80 nm and a refractive index ratio NZ of 4, and the negative biaxial A plate 24 of the upper polarizing plate 20 has a front phase difference ( R0) is 70 nm and refractive index ratio (NZ) is two.

The negative biaxial A plate is a cycloolefin polymer (COP, Zeonor, Optes, Japan) was used, the front phase difference wavelength dispersion is front phase difference (wavelength 380nm) / front phase difference (wavelength 780nm) is 1.006, as shown in Figure 8 The one showing the degree of full-wave wavelength dispersion was used.

As a result of performing the visibility omnidirectional transmittance simulation in the above configuration, the results as shown in FIG. 19 were obtained. In the results of FIG. 20, the transmittance in the dark state was not very high, but the dispersion angle was 35.6294 °.

Comparative Example 2

In the same manner as in Example 1, the lower polarizing plate 10 is the absorption axis 12 of the polarizer 11 and the slow axis 15 of the negative biaxial A plate 14 is orthogonal, and the upper polarizing plate 20 The absorption axis 22 of the silver polarizer 21 and the slow axis 25 of the negative biaxial A plate 24 were laminated in the configuration of FIG. 21 so as to be perpendicular to each other.

The absorption axis 12 of the polarizer 11 of the lower plate polarizing plate 10 was positioned in the vertical direction when viewed from the viewing side. This is most commonly used in the vertical alignment mode liquid crystal display [Samsung Electronics (Korea) and Sharp (Japan) as of 2008].

In the above configuration, the negative biaxial A plates 14 and 24 of the upper plate and the lower plate polarizing plate are used to show the wavelength dispersion of the wavelengths as shown in FIG. 7, and the front phase difference (wavelength 380 nm) / front phase difference (wavelength 780 nm) is used. 0.862 was used.

The negative biaxial A plate 14 of the lower polarizing plate 10 had a front phase difference R0 of 50 nm and a refractive index ratio NZ of 3 at a wavelength of 589.3 nm. The negative biaxial A plate 24 of the upper polarizing plate 20 was disposed such that the front phase difference R0 was 50 nm and the refractive index ratio NZ was 3 to manufacture a vertical alignment mode liquid crystal display device.

As a result of performing the visibility omnidirectional transmittance simulation in the above configuration, the results as shown in FIG. 22 were obtained. The change in polarization state at the reference time of the present invention is shown in FIG. 23. When the polarization state passes through the lower polarizer 11 on the Poincare Sphere, the polarization state passes through 1 and the negative biaxial A plate 14. When the polarization state passes through 2, the liquid crystal cell passes through the polarization state passes through 3, and the negative biaxial A plate 24 passes through, the polarization state becomes polarized into 4. Due to the liquid crystal cell having the forward wavelength dispersion and the retardation film having the reverse wavelength dispersion, the wavelength of the longest path is 380 nm, the shortest path is 780 nm and the intermediate wavelength is 550 nm on Poincare Sphere. Is expressed.

In the LCD, the polarization state 4 is represented by (0.669751, -0.65325, -0.35313) at a wavelength of 380 nm, and is represented by (0.997032, 0.030001, -0.0709) at a wavelength of 780nm in the Cartesian coordinate system on the Puan Cureg sphere. It can be seen that the angle at which the polarization state 4 at the wavelength of 380 nm and the wavelength of 780 nm is based on the origin of the Poang Karegu is 47.68528 °.

In Example 1 and Comparative Example 2, the angles of the polarization state 4 at the wavelength of 380 nm and the wavelength of 780 nm based on the origin of the Pangaregu are 26.77047 ° and 47.68528 °, respectively. It can be seen that is small.

In particular, FIG. 24 shows the transmittance at Φ = 45 ° in the diagonal direction in the liquid crystal display of Example 1 and Comparative Example 2. FIG. In Example 1 and Comparative Example 2, the transmittance in the white state is almost similar, so the contrast ratio in the inclination direction (θ = 60 °, Φ = 45 °) is more than twice as sharp as that of Comparative Example 2 in Example 1 It can be seen that can provide. Specifically, when the inclination direction (θ = 60 °, Φ = 45 °) contrast ratio of Comparative Example 1 is about 80, the inclination direction (θ = 60 °, Φ = 45 °) contrast of Example 1 is numerically calculated. It can be seen that the ratio is about 160.

Further, in Example 1 and Comparative Example 2, the omnidirectional transmittance in the black state is the same as that of FIGS. 9 and 22, respectively. In general, when the blue in the central part is wide, it means that the viewing angle is wide. However, the central blue area of FIG. 9 is wider than that in FIG.

Comparative Example 3

Conducted in the same manner as in Comparative Example 2, but the full-wavelength wavelength dispersion of the negative biaxial A plate (14), (24) of the upper and lower polarizing plate is as shown in Figure 8 and RO (wavelength 380nm, unit nm) / RO (wavelength 780nm) , Unit nm) was used as 1.006.

As a result of performing the visibility omnidirectional transmittance simulation in the above configuration, results as shown in FIG. 25 were obtained. The change in polarization state at the reference time of the present invention is shown in FIG. 26. When the polarization state passes through the lower polarizer 11 on the Poincare Sphere, the polarization state passes through 1 and the negative biaxial A plate 14. When the polarization state passes through 2, the liquid crystal cell passes through the polarization state passes through 3, and the negative biaxial A plate 24 passes through, the polarization state becomes polarized into 4. Due to the liquid crystal cell and the retardation film having the constant wavelength dispersion, the wavelength with the longest path is 380 nm and the wavelength with the shortest path is 780 nm on Poincare Sphere. In the LCD, the polarization state 4 is represented as (0.594173, -0.75149, -0.28674) at a wavelength of 380 nm and (0.985953, 0.0021, -0.16701) at a wavelength of 380 nm. Therefore, it could be seen that the angle at which the polarization state 4 at the wavelength of 380 nm and the wavelength of 780 nm is based on the origin of the Poang Karegu is 50.79211 °.

In Comparative Examples 2 and 3, the angles of the polarization state 4 at the wavelength of 380 nm and the wavelength of 780 nm based on the origin of the Phuang Karegu were 47.68528 ° and 50.79211, respectively. It was confirmed that the angle is increased. In addition, as the dispersion angle is increased, as shown in FIG. 25, the inclined plane transmittance is also increased, and the image quality is deteriorated at the inclined plane.

Comparative Example 4

In the same manner as in Example 1, the negative biaxial A plate 24 of the upper polarizing plate 20 has a front retardation value R0 of 80 nm, a refractive index ratio NZ of 4, and a negative polarization of the lower polarizing plate 10. As the biaxial A plate 14, a front phase difference value R0 of 70 nm and a refractive index ratio NZ of 1.6 were used.

The negative biaxial A plate applied to the top plate used triacetyl cellulose (TAC). The front retardation wavelength dispersion was 0.862 with the front retardation value (wavelength 380 nm) / front retardation value (wavelength 780 nm) and used as the wavelength dispersion degree shown in FIG.

The negative biaxial A plate applied to the bottom plate used a cycloolefin polymer (COP, Zeonor, Zeon, Japan). The front retardation wavelength dispersion of the front phase retardation value (wavelength 380 nm) / front phase retardation value (wavelength 780 nm) is 1.006 and used as the wavelength dispersion of the wavelength shown in FIG.

The simulation results of the visibility of the vertical alignment mode liquid crystal display were obtained as shown in FIG. 27. This indicates the change in the polarization state of the Poang Curé sphere as shown in FIG. 28 in the inclined direction (θ = 60 °, Φ = 45 °), and thus the viewing angle is narrow because there is almost no blue range in the center. = 60 °, Φ = 45 °), the contrast ratio was 34.6.

In Comparative Example 4, the angle between the polarization state 4 at the wavelength of 380 nm and the wavelength of 780 nm was about 16.96536 ° based on the origin of the Puan Cureg, but the transmittance in the oblique direction (θ = 60 °, Φ = 45 °) was high. The present invention did not satisfy the desired effect. In other words, the present invention must satisfy the wavelength dispersion at the same time as the viewing angle compensation.

Comparative Example 5

In the same manner as in Comparative Example 2, the lower polarizing plate 10 is the absorption axis 12 of the polarizer 11 and the slow axis 15 of the negative biaxial A plate 14 is orthogonal, and the upper polarizing plate 20 The absorption axis 22 of the silver polarizer 21 and the slow axis 25 of the negative biaxial A plate 24 were laminated in the configuration of FIG. 1 so as to be parallel. The absorption axis 12 of the polarizer 11 of the lower plate polarizing plate 10 was positioned in the vertical direction when viewed from the viewing side.

The negative biaxial A plate 14 of the lower polarizing plate 10 at a wavelength of 589.3 nm has a front retardation R0 of 59 nm and a refractive index ratio NZ of 3.8; The negative biaxial A plate 24 of the upper polarizing plate 20 was arranged such that the front phase difference R0 was 65 nm and the refractive index ratio NZ was 2 to manufacture a vertical alignment mode liquid crystal display device.

At this time, the front retardation wavelength dispersion of the negative biaxial A plate 14 of the lower polarizing plate 10 has a front retardation (wavelength 380 nm) / front retardation (wavelength 780 nm) of 1.006, and the negative biaxial A plate of the upper polarizing plate 20. Front phase difference wavelength dispersion of (24) used that the front phase difference (wavelength 380 nm) / front phase difference (wavelength 780 nm) is 1.006.

The simulation results of the visibility of the vertical alignment mode liquid crystal display were shown in FIG. 29.

This indicates a change in the polarization state of the Poang Curé sphere as shown in FIG. 30 in the inclination direction (θ = 60 °, Φ = 45 °), and thus, it was confirmed that the viewing angle was narrow due to the narrow blue range at the center. At this time, in Comparative Example 5, the angle between the polarization state 4 at the wavelength of 380 nm and the wavelength of 780 nm was 32.51208 ° based on the origin of the Pangaregu. However, the transmittance in the oblique direction (θ = 60 °, Φ = 45 °) was small. It did not satisfy | fill the aimed effect of this invention high. In other words, the present invention must satisfy the wavelength dispersion at the same time as the viewing angle compensation.

Comparative Example 6

In the same manner as in Comparative Example 2, the lower polarizing plate 10, the absorption axis 12 of the polarizer 11 and the slow axis 15 of the negative biaxial A plate 14 is orthogonal, and the upper polarizing plate 20 ) Is laminated in the configuration of FIG. 1 such that the absorption axis 22 of the polarizer 21 and the slow axis 25 of the negative biaxial A plate 24 are parallel to each other. The absorption axis 12 of the polarizer 11 of the lower plate polarizing plate 10 was positioned in the vertical direction when viewed from the viewing side.

At a wavelength of 589.3 nm, the negative biaxial A plate 14 of the lower plate polarizing plate 10 has a front phase difference R0 of 101 nm and a refractive index ratio NZ of 1; The negative biaxial A plate 24 of the upper polarizing plate 20 was disposed such that the front retardation R0 was 50 nm and the refractive index ratio NZ was 1.2, thereby manufacturing a vertical alignment mode liquid crystal display device.

At this time, the front retardation wavelength dispersion of the negative biaxial A plate 14 of the lower polarizing plate 10 has a front retardation (wavelength 380 nm) / front retardation (wavelength 780 nm) of 0.862, and the negative biaxial A plate of the upper polarizing plate 20. Front phase difference wavelength dispersion of (24) used that whose front phase difference (wavelength 380 nm) / front phase difference (wavelength 780 nm) is 0.862.

The simulation results of the visibility of the vertical alignment mode liquid crystal display were obtained as shown in FIG. 31.

This indicates a change in the polarization state of the Poang Curé sphere as shown in FIG. 32 in the inclination direction (θ = 60 °, Φ = 45 °), and thus it was confirmed that the viewing angle is narrow because the blue range of the central part is narrow. At this time, in Comparative Example 6, the angle at which the polarization state 4 at the wavelength of 380 nm and the wavelength of 780 nm was based on the origin of the Poang Cureg was 67.06955 °.

As described above, the vertical alignment mode liquid crystal display device according to the present invention can provide a wide viewing angle in front and inclined surfaces, and thus can be applied to a large screen liquid crystal display device requiring a high optical level.

1 is a perspective view showing the structure of an exemplary vertical alignment mode liquid crystal display device according to the present invention;

2 is a perspective view showing the structure of another vertical alignment mode liquid crystal display device according to the present invention;

3 is a schematic diagram for explaining the refractive index of the retardation film according to the present invention,

Figure 4 is a schematic diagram 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,

5 is a schematic view for explaining what is represented by θ, Φ in the coordinate system of the present invention,

FIG. 6 is a schematic diagram for describing a difference in polarization states according to wavelengths as dispersion angles in the Pangaregu sphere of the present invention.

7 is a graph showing the full-wavelength wavelength dispersion of a negative biaxial A plate made of TAC,

8 is a graph showing the full-wavelength wavelength dispersion of negative biaxial A plate made of COP,

9 is a simulation result of the visibility of the omnidirectional transmittance of Example 1 according to the present invention,

FIG. 10 illustrates a change in polarization state of light emitted in an inclined direction (θ = 60 °, Φ = 45 °) in Example 1 of the present invention on Poincare Sphere.

11 is a simulation result of the visibility of the visibility of Example 2 according to the present invention,

FIG. 12 illustrates a change in polarization state of light emitted in an inclined direction (θ = 60 ° and Φ = 45 °) in Example 2 of the present invention on Poincare Sphere.

13 is a simulation result of the visibility of the visibility of Example 3 according to the present invention,

FIG. 14 illustrates a change in polarization state of light emitted in an inclined direction (θ = 60 ° and Φ = 45 °) in Example 3 of the present invention on a Poincare Sphere.

15 is a simulation result of the visibility of omnidirectional transmittance of Example 4 according to the present invention;

FIG. 16 illustrates a change in polarization state of light emitted in an inclined direction (θ = 60 ° and Φ = 45 °) in Example 4 of the present invention on a Poincare Sphere.

17 is a simulation result of the visibility of omnidirectional transmittance of Example 5 according to the present invention,

FIG. 18 illustrates a change in polarization state of light emitted in an inclined direction (θ = 60 ° and Φ = 45 °) in Example 5 of the present invention on a Poincare Sphere.

19 is a result of simulating the visibility omnidirectional transmittance of Comparative Example 1 according to the present invention,

FIG. 20 illustrates a change in polarization state of light emitted in an inclined direction (θ = 60 ° and Φ = 45 °) in Comparative Example 1 on Poincare Sphere.

21 is a perspective view showing the structure of an exemplary vertical alignment mode liquid crystal display device according to Comparative Example 2 according to the present invention;

22 is a result of simulating the visibility of omnidirectional transmittance of Comparative Example 2 according to the present invention,

FIG. 23 illustrates a change in polarization state of light emitted in an inclined direction (θ = 60 °, Φ = 45 °) in Comparative Example 2 of the present invention on Poincare Sphere.

24 shows transmittance in the inclination directions (0 ° <θ <180 °, Φ = 45 °) of Example 1 and Comparative Example 2 according to the present invention,

25 is a result of simulating the visibility omnidirectional transmittance of Comparative Example 3 according to the present invention,

FIG. 26 illustrates a change in polarization state of light emitted in an inclined direction (θ = 60 ° and Φ = 45 °) in Comparative Example 3 of the present invention on Poincare Sphere.

27 is a result of simulating the visibility omnidirectional transmittance of Comparative Example 4 according to the present invention,

FIG. 28 illustrates a change in polarization state of light emitted in an inclined direction (θ = 60 °, Φ = 45 °) in Comparative Example 4 on Poincare Spheres,

29 is a result of simulating the visibility of omnidirectional transmittance of Comparative Example 5 according to the present invention,

FIG. 30 illustrates a change in polarization state of light emitted in an inclined direction (θ = 60 °, Φ = 45 °) in Comparative Example 5 on Poincare Sphere,

31 is a result of simulating the visibility of omnidirectional transmittance of Comparative Example 6 according to the present invention,

FIG. 32 illustrates a change in polarization state of light emitted in an inclined direction (θ = 60 °, Φ = 45 °) in Comparative Example 6 on Poincare Sphere.

Claims

In the upper and lower plates, respectively, a polarizing plate laminated in the order of the negative biaxial A plate, the polarizer and the protective film from the liquid crystal cell side,

The liquid crystal cell satisfies a red (R) cell gap ≥ green (G) cell gap ≥ blue (B) cell gap, provided that red (R) cell gap = green (G) cell gap = blue (B) cell gap except),

One of the negative biaxial A plates of the upper and lower polarizers is arranged with the slow axis parallel to the absorption axis of the adjacent polarizer and the other with the slow axis perpendicular to the absorption axis of the adjacent polarizer,

The negative biaxial A plate, whose slow axis is disposed parallel to the absorption axis of the adjacent polarizer, has a front phase difference value of 50 to 90 nm, a refractive index ratio of 1 <NZ≤3,

The negative biaxial A plate, whose slow axis is disposed perpendicular to the absorption axis of the adjacent polarizer, has a front retardation value of 60 to 100 nm and a refractive index ratio of 3 ≦ NZ ≦ 5,

A vertical alignment mode liquid crystal display in which each polarization state at wavelengths of 380 nm and 780 nm immediately before passing through the polarizer of the upper polarizing plate is formed at an angle of 30 ° or less with respect to the origin of the Puan Cureg.

The liquid crystal display of claim 1, wherein the liquid crystal cell has a red cell gap: a green cell gap: a blue cell gap: 1 to 1.2: 1: 0.8 to 1.

The liquid crystal display device according to claim 1, wherein a negative biaxial A plate having a slow axis parallel to an absorption axis of adjacent polarizers has a front retardation value of 55 to 85 nm and a refractive index ratio of 1.5 ≦ NZ ≦ 2.5.

The liquid crystal display according to claim 1, wherein a negative biaxial A plate having a slow axis perpendicular to an absorption axis of adjacent polarizers has a front retardation value of 65 to 95 nm and a refractive index ratio of 3.5≤NZ≤4.5.

The liquid crystal display device according to claim 1, wherein an angle at which the polarization states at wavelengths of 380 nm and 780 nm immediately before passing through the flat plate of the upper polarizing plate is about 27 ° or less based on the origin of the Poang Karegu.

The liquid crystal display device according to claim 1, wherein the negative biaxial A plates of the upper and lower polarizing plates have a front phase difference value (wavelength 380 nm) / front phase difference value (wavelength 780 nm)> 0.5.

The liquid crystal display of claim 1, wherein the liquid crystal cell has a thickness direction retardation value Rth of from -350 to -250 nm at a wavelength of 589 nm.

The liquid crystal display device according to claim 1, wherein the visibility transmittance satisfies a compensation relationship of 0.05% or less in an inclined direction (θ = 60 °, Φ = 45 °).

The liquid crystal display device according to claim 1, wherein a contrast ratio (white luminance / black luminance) in an oblique direction (θ = 60 °, Φ = 45 °) is 100: 1 or more.