KR20070024785A - Liquid-crystal display - Google Patents

Abstract

A liquid crystal display device is provided to obtain high contrast characteristics at inclination angles and minimize color change in a dark state according to a viewing angle, thereby improving the viewing angle characteristics. A liquid crystal display device includes upper and lower glass substrates, polarization plates(110,100) positioned between the glass substrates with absorption axes perpendicular to each other, and a vertically aligned panel(200) positioned between the polarization plates and having a negative or positive dielectric anisotropy value. A film layer is positioned between the polarization plates and has phase difference compensating characteristics of a positive value, wherein the film layer satisfies a formula 3. Directors of liquid crystal molecules of the vertically aligned panel have a pretilt angle in the range from 75‹ to 90‹, preferably in the range from 89‹ to 90‹ between the upper and lower glass substrates when no voltage is applied thereto. The film layer is formed of one or more selected from a group including A-plate and -C-plate. A-plate satisfies a formula 1, is positioned between the polarization plates, and has an optical axis perpendicular to the absorption axis of an adjacent one of the polarization plates, wherein a phase difference value thereof increases inverse wavelength dispersion characteristics as a wavelength in visible ray range is increased. -C-plate satisfies a formula 2, is positioned between the polarization plates, and has an optical axis perpendicular to the absorption axis of an adjacent one of the polarization plates. The above formulas are as follows: 1) n_x>n_y=n_z, 2) n_x=n_y>n_z, and 3) 50nm<=R_-C+R_VA<=150nm, wherein n_x represents a refractive index in x-axis direction on a surface phase of the film, n_y represents a refractive index in y-axis direction, n_z represents a refractive index in a thickness direction of the film, R_-C represents a phase difference value of -C-plate, and R_VA represents a phase difference value of the vertically aligned panel.

Description

Liquid crystal display with improved wide viewing angle characteristics {Liquid-crystal display}

1 is a perspective view of a VA-LCD cell including a film layer according to Example 1 of the present invention.

2 is a perspective view of a VA-LCD cell including a film layer according to Example 2 of the present invention.

3 is a perspective view of a VA-LCD cell including a film layer according to Example 3 of the present invention.

4 is a perspective view of a VA-LCD cell including a film layer according to Example 4 of the present invention.

5 is a perspective view of a VA-LCD cell including a film layer according to Example 5 of the present invention.

6 is a perspective view of a VA-LCD cell including a film layer according to Example 6 of the present invention.

7 is a perspective view of a VA-LCD cell including a film layer according to Example 7 of the present invention.

8 is a ratio (R _{-C, 400} / R _{-C, 550} ) of the retardation value in the thickness direction of the second retardation film at 400 nm wavelength and the retardation value in the thickness direction of the second retardation film at ₅₅₀ nm wavelength and at 550 nm wavelength. It is a graph showing the relationship between the phase difference values (R _{VA , 550} ) in the thickness direction of the VA-LCD cell.

FIG. 9 is a simulation result of contrast ratio when white light is used for a tilt angle in a range of 0 ° to 80 ° at all the mirror angles in a VA-LCD cell including the film layers according to Examples 1 to 4 of the present invention. It is a graph.

10 is a white light is used in the VA-LCD cell including the film layer according to Examples 1 to 4 of the present invention, while changing the inclination angle in the range of 0 ° to 80 ° from 2 ° intervals at a 45 ° Tokyo angle. This is a graph that simulates the color change of the black state.

FIG. 11 is a simulation of contrast ratio when white light is used for a tilt angle in a range of 0 ° to 80 ° at all Tokyo angles in a VA-LCD cell including the film layers according to Examples 5 to 8 of the present invention. The result graph.

12 is a white light is used in the VA-LCD cell including the film layer according to Examples 5 to 8 of the present invention, while changing the inclination angle in the range of 0 ° to 80 ° from 2 ° intervals at a 2 ° interval. This is a graph showing the simulation of the color change of the black state of the black.

Explanation of symbols in the drawings

100: polarizer

110: polarizing plate having an absorption axis perpendicular to the polarizing plate of 100

200: vertical alignment panel

300: A-Plate

310: A-Plate having an absorption axis perpendicular to A-Plate of 300

400: -C-Plate

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device having improved wide viewing angle characteristics in a liquid-crystal display (hereinafter referred to as LCD).

The present invention relates to the dark state of a liquid crystal display (LCD), specifically a vertically aligned liquid-crystal display (VA-LCD) filled with liquid crystals having negative or positive dielectric anisotropy. The present invention relates to a vertically aligned liquid crystal display device (hereinafter referred to as "VA-LCD") having a film layer using A-Plate and -C-Plate to minimize color change and improve wide viewing angle characteristics at front and inclined angles.

One of the biggest weaknesses of liquid crystal displays (LCDs), which are widely used in the field of flat panel displays, is that the viewing angle is narrow. The reason why the image looks different depending on the viewing angle of the liquid crystal display device is the problem due to the anisotropy of the liquid crystal. And second, the imperfection of the polarizer.

In order to improve the wide viewing angle, which is one of the weak points of the liquid crystal display, a completely dark state and uniform brightness are required. In particular, unlike the TN mode, the VA- which has the initial orientation of the liquid crystal in the vertical direction is used. In the case of LCD, there are two major problems of deteriorating the viewing angle characteristics. The first is the viewing angle dependence of the orthogonal polarizer, and the second is the viewing angle dependency of the birefringence characteristic of the VA-LCD panel. .

According to these requirements and problems, various attempts have been made to improve the wide viewing angle of the liquid crystal display, and the specific improvement method is to compensate for the narrow viewing angle due to the change of Δnd (the product of birefringence and specimen spacing) according to the angle. A multi-domain (MULTIDOMAIN) method of dividing a pixel into multiple domains and improving a viewing angle is used.

As a specific example of improving the wide viewing angle of the VA-LCD using the viewing angle compensation film, a -C-Plate compensation film (in the plane direction) is used to compensate for the dark state of the VA-LCD without voltage applied. A VA-LCD using n _x = n _y > n _z ) is disclosed in US Pat. No. 4,889,412 when the _x- axis refractive index is n _x , the y-axis refractive index is n _y , and the Z-axis refractive index is n _z . , VA-LCD containing only -C-Plate compensation film has the disadvantage that light leakage occurs at the inclination angle because it is not completely compensated.

In addition, an example of a compensation film including a -C-Plate compensation film and an A-Plate compensation film is shown in US Pat. No. 6,141,075. In this case, however, the minimum contrast at 70 degrees of inclination at DARK STATE is only 20: 1, so that the contrast at front and inclination angles can be improved to improve the viewing angle. The change of the color of the state was in need of improvement.

SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid crystal display device that can obtain high contrast characteristics at the front and inclination angles of a VA-LCD and to improve the viewing angle characteristics of a VA-LCD by minimizing the color change of the dark state at the inclination angle. .

In order to achieve the above object, the present invention provides a liquid crystal display device comprising: two upper and lower glass substrates; A polarizing plate having two absorption axes orthogonal to each other, positioned between the two glass substrates; A vertical alignment panel having a negative or positive dielectric anisotropy and positioned between the two polarizing plates; It is an A-Plate that satisfies the condition of Equation 1 below, and is located between the two polarizing plates, and the optical axis is perpendicular to the absorption axis of the adjacent polarizing plate, and the phase difference value increases as the wavelength increases within the visible light range. A-Plate increases with reverse wavelength dispersion; And -C-Plate satisfying the condition of Equation 2 below, positioned between the two polarizing plates, and having an optical axis perpendicular to an absorption axis of an adjacent polarizing plate; A film layer having a + value retardation compensation characteristic, selected from the group consisting of 1 or more, satisfies the condition of Equation 3 below, and the director of the liquid crystal molecules of the vertical alignment panel does not apply a voltage between the two glass substrates. A film layer having a pretilt angle of 75 to 90 degrees in a non-state state; It provides a liquid crystal display comprising a.

n _x > n _y = n _z

(Wherein n _x is the refractive index in the x-axis direction on the plane of the film, n _y is the refractive index in the y-axis direction on the plane of the film, and n _z is the refractive index in the thickness direction of the film)

n _x = n _y > n _z

(Wherein n _x is the refractive index in the x-axis direction on the plane of the film, n _y is the refractive index in the y-axis direction on the plane of the film, and n _z is the refractive index in the thickness direction of the film)

50nm≤R _-C + R _VA ≤150nm

(The R _-C is a phase difference value of -C-Plate, the R _VA is a phase difference value of the vertical alignment panel)

The pretilt angle is 87 to 90 degrees. More preferably, it may be 89-90 degrees.

The retardation value of the liquid crystal layer of the vertical alignment panel may be 80 nm to 400 nm, more preferably 80 nm to 300 nm at a wavelength of 550 nm.

When voltage is applied, the director of the liquid crystal molecules of the vertical alignment panel may form 45 degrees with the absorption axis of the polarizer.

Retardation values R _{A , 400} , R _{A, 550} , R _{A , 700} of the A-Plate at wavelengths of 400 nm, 550 nm, and 700 nm may satisfy the conditions of Equations 4 and 5 below.

0.6≤R _{A , 400} / R _{A , 550} ≤0.9

1.1≤R _{A , 700} / R _{A , 550} ≤1.5

At 550 nm wavelength, the retardation value in the thickness direction of the -C-Plate may have a value ranging from -100 nm to -400 nm.

Relative retardation values (R _{-C, 400} / R _{-C, 550} ) at 400nm and 550nm of the -C-Plate are greater than the relative retardation values of the vertical alignment panel, and relative retardation values (R _- at 550nm and 700nm). _{C, 700} / R _{-C, 550} may be smaller than the relative phase difference value of the vertical alignment panel.

The relative phase difference value (R _{-C, 400} / R _{-C, 550} ) in the thickness direction at 400 nm and 550 nm of -C-Plate has a value ranging from 1.1 to 1.3, and the relative phase difference in the thickness direction at 550 nm and 700 nm. The value R _{-C, 700} / R _{-C, 550} may range from 0.8 to 0.9.

The A-Plate may have a phase difference value of 130 nm to 200 nm, more preferably 130 nm to 160 nm at a wavelength of 550 nm.

The objects, features and advantages of the present invention will be more readily understood by reference to the accompanying drawings and the following detailed description.

Hereinafter, the configuration and operation of the present invention with reference to the accompanying drawings in detail as follows.

1 to 7 illustrate a VA-LCD that can be implemented by the present invention, two polarizing plates 100 and 110 having absorption axes perpendicular to each other, and a vertical alignment panel 200 disposed between the two polarizing plates. And a film layer disposed between the two polarizers and the vertical alignment panel, wherein the film layer comprises a structure including one or more A-Plates (300, 310) and -C-Plate (400). Have Here, the polarizing plate may include a protective film having a TAC (triacetate cellulose) protective film having a unique retardation value in the thickness direction or having no retardation value in the thickness direction.

1 to 4 show the vertical alignment panel 200 and two upper and lower polarizers 100 and 110 orthogonal to each other using one A-Plate 300 or 310 and one -C-Plate 400, respectively. A structure of a VA-LCD cell according to Embodiments 1 to 4 arranged to maintain a cell gap of 3-8 μm, and FIG. 1 shows the A-Plate 300 with the vertical alignment panel 200 and the lower polarizing plate 100. The C-Plate 400 is disposed between the vertical alignment panel 200 and the upper polarizer 110, and the optical axis of the A-Plate 300 is the lower polarizer 100. It is arranged perpendicular to the absorption axis of.

FIG. 2 is a form of Embodiment 2, wherein the A-Plate 310 is disposed between the vertical alignment panel 200 and the upper polarizing plate 110, and the -C-Plate 400 is disposed between the vertical alignment panel 200 and the lower portion. The polarizer 100 is disposed between the polarizers 100, and the optical axis of the A-Plate 310 is disposed perpendicular to the absorption axis of the upper polarizer 110.

FIG. 3 illustrates a form of Embodiment 3 in which A-Plate 310 and -C-Plate 400 are disposed in succession between the vertical alignment panel 200 and the upper polarizer 110, wherein A The optical axis of the plate 310 is disposed perpendicular to the absorption axis of the upper polarizer 110.

4 is a form of Embodiment 4, in which the positions of the A-Plate 310 and the -C-Plate 400 of FIG. 3 are alternately arranged between the vertical alignment panel 200 and the upper polarizer 110. The optical axis of the A-Plate 310 is disposed perpendicular to the absorption axis of the upper polarizer 110.

5 and 6 show the vertical alignment panel 200 and two upper and lower polarizers 110 and 100 perpendicular to each other using two A-Plates 310 and 300 and one -C-Plate 400. The structure of the VA-LCD cell by Example 5 and 6 arrange | positioned each so that it may maintain the cell gap of 3-8 micrometers is shown.

5 is a form of Embodiment 5, wherein the A-Plate 300 is disposed between the vertical alignment panel 200 and the lower polarizing plate 100 and the A-Plate 310 and -C-Plate 400 are vertically aligned. The panel 200 and the upper polarizer 110 are arranged in succession, wherein the A-Plate 300 disposed between the vertical alignment panel 200 and the lower polarizer 100 has an optical axis of which is lower than the lower polarizer. A-Plate 310 is disposed perpendicular to the absorption axis of the (100), and disposed between the vertical alignment panel 200 and the upper polarizing plate 110, the optical axis is on the absorption axis of the upper polarizing plate (110). It is arranged vertically.

FIG. 6 shows a form of Embodiment 6 in which an A-Plate 310 is disposed between the vertical alignment panel 200 and the upper polarizer 110, and the A-Plate 300 and the -C-Plate 400 are vertically aligned. It illustrates that arranged in succession between the panel 200 and the lower polarizing plate 100, wherein the A-Plate (310) disposed between the vertical alignment panel 200 and the upper polarizing plate 110, the optical axis of the upper polarizing plate The A-Plate 300 disposed perpendicular to the absorption axis of the 110 and disposed between the vertical alignment panel 200 and the lower polarizer 100 has an optical axis perpendicular to the absorption axis of the lower polarizer 100. It is arranged.

7 is disposed between the vertical alignment panel 200 and the two upper and lower polarizers 110 and 100 perpendicular to each other using two A-Plates 310 and 300 and two -C-Plates 400, respectively. As a structure of a VA-LCD cell according to Example 7 configured to maintain a cell gap of 3-8 μm, the A-Plate 300 and the -C-Plate 400 are vertically aligned panel 200 and a lower polarizing plate ( A-Plate 310 and another -C-Plate 400 are arranged in succession between the vertical alignment panel 200 and the upper polarizing plate 110. Here, the A-Plate 300 disposed between the vertical alignment panel 200 and the lower polarizer 100 has an optical axis perpendicular to the absorption axis of the lower polarizer 100, and the vertical alignment panel 200. The A-Plate 310 disposed between the upper polarizers 110 has its optical axis perpendicular to the absorption axis of the upper polarizer 110.

8 is a ratio of the phase difference value in the thickness direction at 400 nm wavelength of -C-Plate applied to the film layer according to the present invention and the phase difference value in the thickness direction at 550 nm wavelength (R _{-C (400)} / R _{-C (550)} ) And a phase difference value (R _{VA 550) in} the thickness direction of the VA-LCD cell at a wavelength of 550 nm.

The sum of the phase difference values in the thickness direction of the vertical alignment panel and the -C-Plate (R _VA + R _-C > 0) according to the present invention always has a positive value, which is required to compensate for the VA-LCD. The phase difference value (R _{-C, 550} ) in the thickness direction of the plate can be obtained from the following equation.

R _{VA (550)} + R _{-C (550)} = 100 to 130 nm (115 nm average)

Here, R _{VA (550)} = (dΔn ₅₅₀ ) _VA is a phase difference value in the thickness direction of the vertically aligned panel at a wavelength of 550 nm, and R _{-C (550)} is a phase difference value in the thickness direction of -C-Plate at a wavelength of 550 nm. to be.

Regarding the phase difference value of -C-Plate, the required wavelength dispersion value (Δn _λ / Δn ₅₅₀ ) _-C can be calculated by the following equation.

_{(△ n λ / △ n 550} ) VA × R VA (550) + (△ n λ / △ n 550) -C × R -C (550) = 115㎚

Here, ( _Δnλ / _Δn550 ) _VA is a phase difference value in the thickness direction of the VA-LCD.

In particular, for any wavelength (λ = 400 nm),

_{(△ n 400 / △ n 550} ) VA × R VA (550) + (△ n 400 / △ n 550) -C × R -C (550) = 115㎚

Retardation value in a thickness direction of the -C-Plate for _{R VA (550) R -C (} 400) / R -C (550) = (△ n 400 / △ n 550) - the result of calculating a relative value of _C is It is shown in FIG.

The optimum condition for the retardation value R _λ = 0.25 × λ on the plane of the A-Plate should be a λ / 4 retardation film (Achromatic Quarter Wave Film) having colorless properties.

Therefore, the relative phase difference value is

R ₄₀₀ / R ₅₅₀ = 400/550 = 0.727, R ₇₀₀ / R ₅₅₀ = 700/550 = 1.273.

The film layer of the VA-LCD according to the present invention has the following characteristics.

A-Plate, in which the refractive index (n _x , n _y ) on the plane of the film and the refractive index (n _z ) in the thickness direction are n _x > n _y = n _z , or -C-Plate with n _x = n _y > n _z Among them, at least one film layer is disposed between the vertical alignment panel and the upper and lower polarizing plates to form a VA-LCD cell having a phase difference compensation characteristic of + value, wherein the A-Plate has an increased wavelength within the visible light range. Reversed wavelength dispersion characteristic that the phase difference value increases as the optical axis is arranged perpendicular to the absorption axis of the adjacent polarizer, the thickness direction including the -C-Plate and the vertical alignment panel The sum of the phase difference values (R _-C + R _VA ) has a positive value in the range of 50 nm to 150 nm, which is constant within the range of visible light.

The liquid crystal molecules of the vertical alignment panel in a state in which no voltage is applied may have a pretilt angle in the range of 75 to 90 degrees between upper and lower glass substrates of the vertical alignment panel. Preferably, the pretilt angle is 87 to 90 degrees, or the pretilt angle is 89 to 90 degrees.

In addition, the phase difference value of the liquid crystal layer formed on the vertical alignment panel may have a range of 80 nm to 400 nm at a wavelength of 550 nm, preferably the phase difference value of the liquid crystal layer formed on the vertical alignment panel has a value of 80 nm to 300 nm at a wavelength of 550 nm. To have.

And the rubbing direction of the liquid crystal injected into the vertical alignment panel forms 45 degrees with the absorption axis of the polarizing plate.

The A-Plate has a phase difference value of 130 to 200 nm or less at a wavelength of 550 nm, and preferably, the A-Plate has a phase difference value of 130 to 160 nm at a wavelength of 550 nm.

In addition, the A-Plate has a ratio (R _{A, 400} / R _{A, 550} ) of thickness in the direction of thickness at two wavelengths of 400 nm and 550 nm in a range of 0.6 to 0.9, and a phase difference in the relative thickness direction at two wavelengths of 700 nm and 550 nm. It is preferable to use a ratio (R _{A , 700} / R _{A , 550} ) in the range of 1.1 to 1.5.

In addition, the -C-Plate has a phase difference value in the thickness direction in the range of -100 nm to -400 nm at a wavelength of 550 nm, and the relative phase difference values of the two wavelengths of the -C-Plate at 400 nm and 550 nm (R _{-C, 400} / R _{-C, 550} is greater than the relative phase difference value of the vertical alignment panel, and the relative phase difference value (R _{-C, 700} / R _{-C, 550} ) at the two wavelengths of 550 nm and 700 nm is smaller than the relative phase difference value of the vertical alignment panel. In particular, the relative phase difference value (R _{-C, 400} / R _{-C, 550} ) in the thickness direction at the two wavelengths 400nm and 550nm of the -C-Plate has a value in the range of 1.1 to 1.3, and at the two wavelengths of 550nm and 700nm. Relative phase difference value (R _{-C, 700} / R _{-C, 550} ) in the thickness direction of is preferably used in the range of 0.8 ~ 0.9.

9 to 12 illustrate simulation results that can be obtained through each embodiment of the present invention, and FIGS. 9 and 11 show tilt angles ranging from 0 ° to 80 ° at 2 ° intervals at all azimuth angles. The simulation results of the contrast ratio values obtained from the VA-LCDs of the respective embodiments of the present invention when white light is used while changing them to are shown in FIG. 10 and FIG. The simulation result of the dark state with respect to is shown by the color coordinate, respectively.

The retardation compensation characteristic of the liquid crystal display according to the present invention will be described in detail with reference to Examples 1 to 7 below. However, the present invention is provided to more easily understand the present invention, and the present invention is not limited to these examples.

[Examples 1-3]

VA-LCDs were manufactured in the order shown in FIGS. 1 to 3, and the vertical alignment panels used herein used a vertical alignment panel having a 3 μm cell gap. A VA-LCD having a pretilt angle of 89 °, a dielectric anisotropy of Δε = -4.9, a refractive index anisotropy of Δn = 0.0979 and a wavelength dispersion characteristic of Δn ₄₀₀ / Δn ₅₅₀ = 1.0979 was used.

Therefore, the retardation value in the thickness direction of the vertical alignment panel is R _{VA (550)} = 297 nm.

The -C-Plate was made of a liquid crystal film, and the retardation value in the thickness direction was R _{-C (550)} = -190 nm, and the wavelength dispersion characteristic was R _{-C (400)} / R _{-C (550)} = 1.31.

A-Plate was made of cured nematic liquid crystal, and the retardation value in in-plane was R _{A (550)} = 145 nm and the wavelength dispersion characteristic was R _{A (400)} / R _{A (550)} = 0.72.

The simulation results of the contrast ratio for the inclination angle in the range of 0 ° to 80 ° at all azimuth angles are shown in FIG. 9, and the VA-LCD arm for the inclination angle in the range of 0 ° to 80 ° at 45 ° east angle. The result of having expressed the simulation about the state by the xy color coordinate is shown in FIG.

Example 4

A VA-LCD was manufactured in the order shown in FIG. 4, and the vertical alignment panel used herein used a vertical alignment panel having a 4 μm cell gap.

A VA-LCD having a pretilt angle of 89 °, dielectric anisotropy Δε = -4.9, refractive index anisotropy Δn = 0.0979 and a wavelength dispersion characteristic of Δn ₄₀₀ / Δn ₅₅₀ = 1.0979 was used.

Therefore, the retardation value in the thickness direction of the vertical alignment panel is R _{VA (550)} = 396 nm.

-C-Plate was made of liquid crystal, and the retardation value in the thickness direction was R _{-C (550)} = -279 nm. The wavelength dispersion characteristic of -C-Plate is R _{-C (400)} / R _{-C (550)} = 1.21.

A-Plate used a cured nematic liquid crystal and a phase difference value in in-plane used R _{A (550)} = 147 nm. The wavelength dispersion characteristic of A-Plate is R _{A (400)} / R _{A (550)} = 0.72.

The results of simulating the contrast ratio for the inclination angle in the range of 0 ° to 80 ° at all azimuth angles are shown in FIG. 9, and the VA-LCD for the inclination angle in the range of 0 ° to 80 ° at 45 ° east angle. The results of expressing the simulation of the cancer state in xy color coordinates are shown in FIG. 10.

[Examples 5 to 6]

The VA-LCDs were manufactured in the order shown in FIGS. 5 to 6, respectively, and the VA-LCDs shown in FIGS. 5 and 6 include a vertical alignment panel having a 3 μm cell gap. Pre-tilt angle is 89 °, a dielectric anisotropy △ ε = -4.9, a refractive index anisotropy △ n = 0.0979, and the wavelength dispersion property _{(△ n 400 / △ n 550} ) was used in the liquid crystal _VA = 1.0979.

Therefore, the retardation value R _{VA (550)} = 297 nm in the thickness direction of the vertical alignment panel.

-C-Plate is made of a liquid crystal film, the retardation value in the thickness direction is R _{-C (550)} = -130nm, the wavelength dispersion characteristic is R _{-C (400)} / R _{-C (550)} = 1.31.

Two sheets of A-Plate were made of a cured liquid crystal film, and the retardation value in in-plane was R _{A (550)} = 90 nm, respectively. The wavelength dispersion characteristic of A-Plate is R _{A (400)} / R _{A (550)} = 0.72.

The results of simulation of the contrast ratio in the range of 0 ° to 80 ° at all azimuth angles are shown in FIG. 11, and the results of xy color coordinates of the simulation of the VA-LCD arm state at 45 ° Tokyo inclination angle. Shown at 12.

Example 7

The VA-LCD shown in FIG. 7 includes a vertical alignment panel having a 3 μm cell gap. The pre-tilt angle is 89 ° (Pretilt Angle), the dielectric anisotropy is △ ε = -4.9, a refractive index anisotropy △ n = 0.0979, wavelength dispersion property was used for the liquid crystal _{△ n 400 / △ n 550 =} 1.0979.

Therefore, the retardation value in the thickness direction of the VA-panel is R _{VA (550)} = 297 nm.

Two sheets of -C-Plate were made of liquid crystal film, and the retardation value in the thickness direction was R _{-C (550)} = -65nm and the wavelength dispersion characteristic was R _{-C (400)} / R _{-C (550)} = 1.31 to be.

Two sheets of A-Plate were made of cured liquid crystal film. The retardation value in in-plane was R _{A (550)} = 90 nm and the wavelength dispersion was R _{A (400)} / R _{A (550 )} = 0.72.

The results of simulation of the contrast ratio for tilt angles ranging from 0 ° to 80 ° at all azimuth angles are shown in FIG. 11, and simulations of VA-LCD arm states at 45 ° tilt angles are expressed in xy color coordinates. The results are shown in FIG.

9 and 11, in the case of the liquid crystal display device according to the present invention, it was confirmed that the display panel had high contrast characteristics at all angles of view. According to FIGS. 10 and 12, the liquid crystal display device according to the present invention was used. In this case, it was confirmed that the color change of the dark state at the inclination angle is minimized.

As described above, the liquid crystal display according to the present invention can completely compensate for the dark state at the inclination angle, and minimize the color change in the dark state, the white state, and the RGB state to reduce the viewing angle characteristics. It is a useful invention to provide this improved liquid crystal display device.

Although the present invention has been described in detail with reference to the described embodiments, various modifications and changes are possible by those skilled in the art within the scope and spirit of the present invention, as well as such modifications and modifications belong to the appended claims. It is natural.

Claims (12)

In the liquid crystal display device, Two upper and lower glass substrates; A polarizing plate having two absorption axes orthogonal to each other, positioned between the two glass substrates; A vertical alignment panel having a negative or positive dielectric anisotropy and positioned between the two polarizing plates; It is an A-Plate that satisfies the condition of Equation 1 below, and is located between the two polarizing plates, and the optical axis is perpendicular to the absorption axis of the adjacent polarizing plate, and the phase difference value increases as the wavelength increases within the visible light range. A-Plate increases with reverse wavelength dispersion; And -C-Plate satisfying the condition of Equation 2 below, positioned between the two polarizing plates, and having an optical axis perpendicular to an absorption axis of an adjacent polarizing plate; Is a film layer having one or more layers, each having a + value retardation compensation characteristic, satisfying the condition of Equation 3 below, and the director of the liquid crystal molecules of the vertical alignment panel is not applied with voltage between the two glass substrates. A film layer having a pretilt angle of 75 to 90 degrees in a non-state state; Liquid crystal display comprising a. [Equation 1] n _x > n _y = n _z N _x is the refractive index in the x-axis direction on the plane of the film, N _y is a refractive index in the y-axis direction on the plane of the film, N _z is a refractive index in the thickness direction of the film [Equation 2] n _x = n _y > n _z N _x is the refractive index in the x-axis direction on the plane of the film, N _y is a refractive index in the y-axis direction on the plane of the film, N _z is a refractive index in the thickness direction of the film [Equation 3] 50nm≤R _-C + R _VA ≤150nm R _-C is a phase difference value of -C-Plate, R _VA is a phase difference value of the vertical alignment panel. The method of claim 1, And a pretilt angle of 87 to 90 degrees. The method of claim 1 And the pretilt angle is 89 to 90 degrees. The method of claim 1, And a phase difference value of the liquid crystal layer of the vertical alignment panel is in a range of 80 nm to 400 nm at a wavelength of 550 nm. The method of claim 4, wherein Liquid crystal display device characterized in that the phase difference value of the liquid crystal layer of the vertical alignment panel is 80nm ~ 300nm at 550nm wavelength. The method of claim 1, The liquid crystal display device, characterized in that the director of the liquid crystal molecules of the vertical alignment panel when the voltage is applied to the absorption axis of the polarizing plate 45 degrees. The method of claim 1, Retardation values R _{A (400)} , R _{A (500)} , R _{A (550)} , and R _{A (700)} of A-Plate at wavelengths of 400 nm, 550 nm, and 700 nm, respectively _, are the conditions of Equations 4 and 5 below. Liquid crystal display characterized in that to satisfy. [Equation 4] 0.6≤R _{A (400)} / R _{A (550)} ≤0.9 [Equation 5] 1.1≤R _{A (700)} / R _{A (550)} ≤1.5 The method of claim 1, And a phase difference value in the thickness direction of -C-Plate at a wavelength of 550 nm, in the range of -100 nm to -400 nm. The method of claim 1, Relative phase difference values (R _{-C (400)} / R _{-C (550)} ) at 400nm and 550nm of the -C-Plate are greater than the relative phase difference values of the vertical alignment panel, and the relative phase difference values at 550nm and 700nm ( R _{-C (700)} / R _{-C (550)} ) is smaller than the relative phase difference value of the vertical alignment panel. The method of claim 9, Relative phase difference values (R _{-C (400)} / R _{-C (550)} ) in the thickness direction at 400nm, 550nm of the -C-Plate has a value in the range of 1.1 to 1.3, and in the thickness direction at 550nm, 700nm A relative phase difference value (R _{-C (700)} / R _{-C (550)} ) has a range of 0.8 ~ 0.9. The method of claim 1, The A-Plate has a phase difference value of 130nm ~ 200nm range at a wavelength of 550nm. The method of claim 11, Wherein the A-Plate has a retardation value in a range of 130 nm to 160 nm at a wavelength of 550 nm.

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