KR20090071082A - In plane switching mode liquid crystal display device having optical compensation film - Google Patents

Abstract

An in-plane switching mode LCD including an optically compensatory film for preventing the light leakage to the diagonal viewing angle direction light source in a dark state is provided to improve the contrast ratio of a diagonal viewing angle and reduce the luminance of a dark state. A first polarizing plate(105) is positioned in the lower part of an LCD(Liquid Crystal Display) panel(110). The first polarizing plate includes a first supporter, a second supporter and a first polarizing device positioned between the first supporter and the second supporter. A second polarizing plate is positioned in the upper part of the LCD panel. The second polarizing plate includes a third supporter, first and second optical compensation films and a second azimuth rotator positioned between the third supporter and the second optically compensatory film. The first optically compensatory film is made of the positive biaxial film.

Description

Transverse electric field liquid crystal display device including optical compensation film {IN PLANE SWITCHING MODE LIQUID CRYSTAL DISPLAY DEVICE HAVING OPTICAL COMPENSATION FILM}

The present invention relates to a transverse electric field type liquid crystal display device, and more particularly, to a transverse electric field type liquid crystal display device including an optical compensation film for improving contrast ratios in up, down, left, and right directions.

Recently, with increasing interest in information display and increasing demand for using a portable information carrier, a lightweight flat panel display (FPD), which replaces a conventional display device, a cathode ray tube (CRT), is used. The research and commercialization of Korea is focused on. In particular, the liquid crystal display (LCD) of the flat panel display device is an image representing the image using the optical anisotropy of the liquid crystal, is excellent in resolution, color display and image quality, and is actively applied to notebooks or desktop monitors have.

The liquid crystal display is largely composed of a color filter substrate as a first substrate, an array substrate as a second substrate, and a liquid crystal layer formed between the color filter substrate and the array substrate.

In this case, the color filter substrate is formed between a color filter composed of a plurality of sub-color filters that implements red (R), green (G), and blue (B) colors and the sub-color filter. A black matrix for dividing and blocking light passing through the liquid crystal layer, and a transparent common electrode for applying a voltage to the liquid crystal layer.

The array substrate may include a plurality of gate lines and data lines arranged vertically and horizontally to define a plurality of pixel regions, thin film transistors (TFTs), which are switching elements formed at intersections of the gate lines and data lines, and the The pixel electrode is formed on the pixel region.

The color filter substrate and the array substrate configured as described above are joined to face each other by sealants formed on the outer side of the image display area to form a liquid crystal display panel. The color filter substrate and the array substrate are bonded to each other by the color filter substrate or the substrate. It is made through a bonding key formed on the array substrate.

In this case, the above-described liquid crystal display device represents a twisted nematic (TN) type liquid crystal display device which drives the nematic liquid crystal molecules in a direction perpendicular to the substrate, and the liquid crystal display device of the type has a viewing angle of 90 degrees. It has the disadvantage of being too narrow. This is due to the refractive anisotropy of the liquid crystal molecules because the liquid crystal molecules oriented horizontally with the substrate are oriented almost perpendicular to the substrate when a voltage is applied to the liquid crystal display panel.

Accordingly, there is an in-plane switching (IPS) type liquid crystal display device in which a liquid crystal molecule is driven in a horizontal direction with respect to a substrate to improve the viewing angle to 170 degrees or more. Hereinafter, the transverse field type liquid crystal display device will be described with reference to the accompanying drawings. It will be described in detail.

1 is a plan view schematically illustrating a portion of an array substrate of a general transverse electric field type liquid crystal display device. In an actual liquid crystal display device, N gate lines and M data lines intersect to present MxN pixels, but the description will be simplified. For the sake of illustration, one pixel is shown.

FIG. 2 is an exemplary view illustrating a cross section taken along line II ′ of the array substrate illustrated in FIG. 1, and illustrates the array substrate illustrated in FIG. 1 and the color filter substrate bonded together corresponding to the array substrate. .

1 and 2, a gate line 16 and a data line 17 are formed on the transparent array substrate 10 to be arranged on the array substrate 10 vertically and horizontally to define a pixel area. The thin film transistor T, which is a switching element, is formed at the intersection of the gate line 16 and the data line 17.

In this case, the thin film transistor T may include a pixel electrode 18 through a gate electrode 21 connected to the gate line 16, a source electrode 22 connected to the data line 17, and a pixel electrode line 18l. It is composed of a drain electrode 23 connected to. In addition, the thin film transistor may be formed by the first insulating layer 15a for insulation between the gate electrode 21 and the source / drain electrodes 22 and 23 and the source electrode by a gate voltage supplied to the gate electrode 21. And an active pattern 24 for forming a conductive channel between the 22 and the drain electrode 23.

For reference, reference numeral 25 denotes an ohmic contact layer for ohmic contact between the source / drain region of the active pattern 24 and the source / drain electrodes 22 and 23.

At this time, the common line 8l and the storage electrode 18s are arranged in a direction parallel to the gate line 16 in the pixel region, and a transverse electric field 90 is generated in the pixel region to generate liquid crystal molecules (not shown). A plurality of common electrodes 8 and pixel electrodes 18 for switching the light source) are arranged in a direction parallel to the data line 17.

In this case, the storage electrode 18s overlaps a portion of the common line 8l below the first insulating layer 15a to form a storage capacitor Cst.

In addition, the transparent color filter substrate 5 implements the black matrix 6 and red, green and blue colors that prevent light leakage from the thin film transistor T, the gate line 16 and the data line 17. The color filter 7 for this is formed.

On the opposite surface of the array substrate 10 and the color filter substrate 5 configured as described above, an alignment film (not shown) for determining the initial alignment direction of the liquid crystal molecules is formed, and the array substrate ( 10) and a polarizing plate (not shown) are disposed on the outer surface of the color filter substrate 5 so that the light transmission axes are perpendicular to each other.

In the general transverse electric field type liquid crystal display device having the above structure, the common electrode 8 and the pixel electrode 18 are disposed on the same array substrate 10 to generate a transverse electric field, and the liquid crystal molecules are formed on the array substrate 10. Since it is arranged in parallel with the transverse electric field parallel to the has a merit that can improve the viewing angle.

However, such a transverse electric field type liquid crystal display has a problem in that light leakage occurs in a diagonal direction when displaying a black state, thereby showing a low contrast ratio.

3A is a diagram illustrating a result of simulating a luminance viewing angle characteristic in a dark state in a general transverse electric field type liquid crystal display device, and FIG. 3B is a diagram illustrating a result of measuring luminance viewing angle characteristics in a dark state.

3A and 3B illustrate a luminance viewing angle characteristic of a dark state when a 0-RT (Tri-acetyl cellulose (TAC) film in which Rth is close to 0 nm) is applied between a PVA (polyvinyl acetate) layer and a liquid crystal layer of a polarizing plate. For example.

In addition, the lower polarizer and the upper polarizer are arranged such that the light absorption axes are perpendicular to each other, and the optical axis of the liquid crystal layer is in a state parallel to the light absorption axis of the lower polarizer.

As shown in the drawing, in the dark state, large light leakage occurs at 45 degrees, 135 degrees, 225 degrees, and 315 degrees corresponding to the diagonal direction of the liquid crystal display panel, thereby increasing the brightness, and accordingly the contrast of the liquid crystal display device. It can be seen that the contrast ratio is lowered. For example, at 45 degrees in the diagonal direction, the luminance is measured as about 8 nits, and the maximum transmittance of the diagonal viewing angle in the dark state corresponds to about 0.001920 when the inclination angle and the east angle are (60, 45).

However, such a problem is not a problem of the transverse electric field type liquid crystal display itself but a problem due to a polarizing plate which is generally used. That is, in general, diagonal light leakage has a greater effect due to the polarizing plate than the effect due to the liquid crystal layer. Like the transverse electric field type liquid crystal display, the transverse electric field mode can determine the initial alignment state so as not to be affected by the liquid crystal in all directions. In this case, light leakage is entirely due to the polarizer.

This is because even if the light absorption axes of the polarizing plates are orthogonal to each other, as shown in FIGS. 4A and 4B, the orthogonality of the two polarizing plates is broken along the viewing angle direction. At this time, the solid lines shown in FIGS. 4A and 4B represent, for example, the light absorption axis direction of the upper polarizing plate, and the dotted line represents the light absorption axis direction of the lower polarizing plate.

As shown in FIG. 4A, when the LCD panel is viewed from the front, the light absorption axes of the upper and lower polarizers form 90 degrees to realize a dark state. However, as shown in FIG. 4B, the LCD displays in a diagonal direction. When looking at the panel, light leakage occurs because the light absorption axis of the upper and lower polarizers is 90 degrees or more, and the orthogonality of the two polarizers is broken.

As described above, the transverse electric field type liquid crystal display device is a method in which a transverse electric field is applied to the liquid crystal layer, so that the change in phase retardation of the liquid crystal is small according to voltage and the optical axis of the upper and lower polarizers is vertical in the up, down, left, and right directions. Although excellent in the optical axis of the upper and lower polarizers, light leakage occurs in a diagonal direction in which the vertical state is broken, causing deterioration of image quality.

In order to improve such deterioration of image quality in a diagonal direction, a compensation film should be applied, but compensation is limited in current optical compensation films that protect the PVA layer of the polarizer. At this time, the PVA layer is a polarizing element that determines the polarization characteristics of the polarizing plate, so it is generally vulnerable to moisture, so it is generally protected by using a film such as TAC or 0-RT. This is because the breakage of the condition cannot be compensated for.

An object of the present invention is to provide a transverse electric field type liquid crystal display device including an optical compensation film to prevent light leakage in a diagonal direction in a dark state.

Another object of the present invention is to provide a transverse electric field type liquid crystal display including an optical compensation film to reduce color shift.

Other objects and features of the present invention will be described in the configuration and claims of the invention described below.

In order to achieve the above object, a transverse electric field type liquid crystal display device including the optical compensation film of the present invention comprises a liquid crystal display panel comprising a liquid crystal layer; A first polarizer disposed under the liquid crystal display panel, the first polarizer including a first support and a second support and a first polarizer disposed between the first support and the second support; And a second polarizer positioned on an upper portion of the liquid crystal display panel and including a third support, a first and a second optical compensation film, and a second polarizer disposed between the third support and the first and second optical compensation films. Wherein the first optical compensation film is defined as −1.0 <Nz <0 (where Nz = Rth / Re, Re = (nx-ny) · d and Rth = (nx-nz) · d, nx, ny, and nz denote refractive indices in the x direction, the y direction, and the z direction, respectively, and d means the thickness of the film), and the second optical compensation film is 1.0 <Nz < It is made of a negative biaxial film of 3.0, the positive biaxial film is characterized in that located between the negative biaxial film and the liquid crystal display panel.

Another transverse field type liquid crystal display device including the optical compensation film of the present invention comprises a liquid crystal display panel including a liquid crystal layer; A first polarizer disposed under the liquid crystal display panel, the first polarizer including a first support and a second support and a first polarizer disposed between the first support and the second support; And a second polarizer positioned on an upper portion of the liquid crystal display panel and including a third support, a first and a second optical compensation film, and a second polarizer disposed between the third support and the first and second optical compensation films. It includes, wherein the first optical compensation film is made of a positive biaxial film and the second optical compensation film is characterized in that made of a negative biaxial film.

As described above, the transverse electric field type liquid crystal display device including the optical compensation film according to the present invention provides an effect of improving the contrast ratio of the diagonal viewing angle by reducing the luminance of the dark state by 90% or more.

In addition, the horizontal field type liquid crystal display device including the optical compensation film according to the present invention provides an effect of improving the image quality by improving the color shift according to the viewing angle.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of a transverse electric field type liquid crystal display device including an optical compensation film according to the present invention.

5 is a cross-sectional view schematically illustrating a transverse electric field type liquid crystal display device including an optical compensation film according to a first embodiment of the present invention.

As shown in the drawing, the transverse electric field type liquid crystal display device 100 according to the first exemplary embodiment of the present invention includes a liquid crystal display panel 110 for outputting an image and a lower portion of the liquid crystal display panel 110. The first polarizer 105 and the second polarizer 115 are disposed on the liquid crystal display panel 110. Here, the upper and lower portions of the liquid crystal display panel 110 do not limit a specific position. Therefore, the first polarizing plate 105 is positioned on the upper portion of the liquid crystal display panel 110 and the lower portion of the liquid crystal display panel 110. The second polarizer 115 may be located.

In this case, although not shown in detail in the drawing, the liquid crystal display panel 110 is largely composed of a color filter substrate and an array substrate and a liquid crystal layer formed between the color filter substrate and the array substrate.

In this case, the liquid crystal layer may include a homogeneous oriented homogeneous liquid crystal in the absence of an electric field, and the liquid crystal layer may exhibit a refractive index distribution of nx> ny = nz (in-plane The refractive index is set to nx and ny, and the refractive index in the thickness direction is set to nz). At this time, in this specification, ny = nz includes not only the case where ny and nz are completely the same, but also the case where ny and nz are substantially the same.

As a drive mode which uses the liquid crystal layer which shows such refractive index distribution, a transverse electric field system, a fringe field switching (FFS) mode, etc. are mentioned, for example.

The transverse electric field method uses a voltage controlled birefringence (ECB) effect to drive a homogeneously oriented nematic liquid crystal in the absence of an electric field through a transverse electric field formed of a pixel electrode and a common electrode. to be.

In addition, the FFS mode is driven in the same manner as the transverse electric field method. The lateral electric field of the FFS mode is called a fringe field, and the fringe field has a gap between the upper and lower substrates between the pixel electrode and the common electrode formed of a transparent conductive material. It can form by setting narrower than the space | interval.

In the case of the first embodiment of the present invention, a transverse electric field type liquid crystal display device is described as an example, but the present invention is not limited thereto, and the present invention may be applied to the FFS mode liquid crystal display device.

The color filter substrate distinguishes between a color filter composed of a plurality of sub-color filters for implementing red (R), green (G), and blue (B) colors and the sub-color filter. It consists of a black matrix (blocking light) passing through the liquid crystal layer (black matrix).

The array substrate may include a plurality of gate lines and data lines arranged vertically and horizontally to define a plurality of pixel regions, a thin film transistor which is a switching element formed at an intersection of the gate lines and data lines, and a transverse electric field formed on the pixel region. It consists of a pixel electrode and a common electrode for generating a.

The first polarizer 105 includes a first support 102 and a second support 104, and a first polarizer 103 disposed between the first support 102 and the second support 104. In addition, the second polarizer 115 may include a third support 112, first and second optical compensation films 120 and 130, and the third support 112 and first and second optical compensation films 120 and 120. And a second polarizer 113 positioned between 130. In this case, in the transverse electric field type liquid crystal display device 100 according to the first embodiment of the present invention, the first optical compensation film 120 and the second optical compensation film 130 are sequentially disposed on the liquid crystal display panel 110. It is characterized by being located.

In this case, the first polarizing element 103 and the second polarizing element 113 may be made of polyvinyl alcohol (PVA), and the first support 102 and the third support 112 may be phase delayed. It may be made of a general protection film without retardation, for example, tri-acetyl cellulose (TAC). In addition, the second support 104 may be formed of a general protective film without phase delay to protect the PVA layer, for example, 0-RT (Rth means a modified TAC close to 0nm, 0 (Also called -TAC) or COP (Cyclo-olefin-Polymer). For reference, the expression that there is no phase delay means that Re is 0. The TAC is a protective film where Re is 0 and Rth is not 0. The 0-RT is a protective film where Re is 0 and Rth is close to 0. Corresponds to

In addition, the first polarizing device 103 and the second polarizing device 113 refers to a film that can be converted from natural light or polarized light into any polarized light. At this time, when the incident light is divided into two orthogonal polarization components, the first polarization element 103 and the second polarization element 113 have a function of allowing one polarization component to pass therethrough, and the other polarization component. One having at least one function selected from the functions of absorbing, reflecting and scattering components can be used.

The optical film used for the first polarizing element 103 and the second polarizing element 113 is not particularly limited, but is, for example, a polymer film containing, as a main component, a PVA-based resin containing iodine or a dichroic dye. The O type polarizing element which orientated the oriented film, the liquid crystalline composition containing a dichroic substance, and a liquid crystalline compound to a fixed direction, and the E type polarizing element which orientated a lyotropic liquid crystal to a fixed direction, etc. are mentioned.

The first polarization element 103 is disposed such that its absorption axis is substantially orthogonal to the absorption axis of the second polarization element 113 facing each other, and the optical axis of the liquid crystal axis is the first polarization element 103. It is in a state parallel to the light absorption axis of. In this case, as described above, when the first polarizing plate 105 is positioned above the liquid crystal display panel 110 and the second polarizing plate 115 is positioned below the liquid crystal display panel 110, the optical axis of the liquid crystal axis is It becomes a state parallel to the light absorption axis of the second polarizing element 113.

In the case of the first embodiment of the present invention, the first optical compensation film 120 and the second optical compensation are disposed between the second polarizing element 113 and the liquid crystal display panel 110 to improve the viewing angle characteristic in the diagonal direction. The film 130 is disposed, wherein the first optical compensation film 120 is formed of a positive biaxial film having −1.0 <Nz <0 while the second optical compensation film 130 is It is characterized by forming a negative biaxial film (negative biaxial film) of 1.0 <Nz <3.0.

At this time, the definition of Re and Rth and Nz used in the present invention is as shown in Equation 1 below.

Re = (nx-ny) d

Rth = (nx-nz)

Nz = Rth / Re

In this case, nx, ny, and nz refer to FIGS. 6A, 6B, and 6C, respectively, and refer to refractive indexes in the x, y, and z directions, respectively, and d represents the thickness of the film. 6A, 6B, and 6C are diagrams illustrating refractive indices for a positive biaxial film, a negative biaxial film, and a negative C plate-like film, respectively.

Accordingly, Re denotes an in-plane phase delay value, and Rth denotes a phase delay value in the thickness direction. In addition, Nz means an index indicating the degree of biaxiality of the biaxial retardation film.

The positive biaxial film is an optical film having Nz less than 0, and in the present invention, may have a value of about -1.0 to 0, and Re and Rth may have values of 40 to 160 nm and -50 to 0 nm, respectively. . In addition, the positive biaxial film has a relationship of nz> nx> ny so that an optical axis is located between nz and ny.

In addition, the negative biaxial film is an optical film having an Nz greater than 1.0, and in the present invention, may have a value of about 1.0 to 3.0, and Re and Rth may have values of 30 to 100 nm and 60 to 150 nm, respectively. . In addition, as the negative biaxial film has a relationship of nx> ny> nz, the optical axis is positioned between nz and nx.

Here, the phase delay values of all the films applied to the present invention may have an error of approximately ± 10 nm due to the process variation or external influences.

In this case, the films usable as the positive biaxial film and the negative biaxial film may be uniaxially stretched TAC (uniaxial stretched TAC), uniaxially stretched polycarbonate (PNB), biaxially stretched PC (polycarbonate), biaxially stretched COP, and the like. , Biaxial LC film, and the like.

The first optical compensation film 120 and the second optical compensation film 130 according to the first embodiment of the present invention having such optical conditions are formed in the diagonal direction of the first and second polarizing plates 105 and 115. By compensating for breaking of orthogonality, it is possible to reduce light leakage in the diagonal direction, which will be described in detail using a Poincare sphere representation.

In order to geometrically interpret the optical properties of transparent media such as liquid crystals, we use the Poangkar sphere representation of the polarization state.

First, the Jones vector may represent only fully polarized light, and a Stokes parameter defined as in Equation 2 below is used to express a more general partial polarized light.

는 시간평균을 나타내며, 이 네 변수 사이에는

의 부등식이 성립하는데, 등식은 완전편광에서만 적용된다.At this time,

Represents the time average, and between these four variables

The inequality of holds, which applies only to complete polarization.

In the case of fully polarized light, the relationship of Equation 3 is established between the standardized variables s ₁ , s _2, and s ₃ obtained by dividing S ₁ , S _2, and S ₃ by the brightness S ₀ of light.

This is the equation of a sphere of radius 1 in three-dimensional space, where a sphere composed of points with (s ₁ , s ₂ , s ₃ ) as Cartesian coordinates is a Poangare sphere.

In this case, all the points on the equator line in the Poangkar sphere correspond to linear polarization, the polar point corresponds to the right hand circular polarization, and the south pole corresponds to the left hand circular polarization. And all the points in the northern hemisphere correspond to the right hand ellipse polarization, and all the points in the southern hemisphere correspond to the left hand ellipse polarization.

7A and 7B are diagrams illustrating an arbitrary elliptical polarization and a corresponding poang curry vector in a rectangular coordinate system.

이다. 이 점이 북반구에 있으면 전기장 벡터의 회전방향이 시계방향이고 남반구에 있으면 반시계방향이다. 뽀앙카레 구 위의 대척점들은 서로 직교하는 편광 상태를 나타낸다.As shown in the figure, the latitude angle of the Poangcurry vector P corresponding to the elliptically polarized light having an azimuthal angle Ψ and an ellipse angle x of the long axis of the polarized ellipse is 2x, the azimuth is 2Ψ, and the Cartesian coordinate Is

to be. If this point is in the northern hemisphere, the direction of rotation of the electric field vector is clockwise; in the southern hemisphere, it is counterclockwise. The opposite points on the Poangcurry sphere represent polarization states orthogonal to each other.

In addition, the Unitary Jones matrix, which describes the change in polarization state when light passes through a transparent medium, can be interpreted as a rotational transformation on a Poangcurry sphere.

8A and 8B are views illustrating a Poangcurry sphere showing a polarization state of light passing through each optical element in the transverse electric field type liquid crystal display device according to the first embodiment of the present invention having the structure of FIG. 5. In this case, FIG. 8A is a view showing a poangcurry sphere when the liquid crystal display panel is viewed from the front, and FIG. 8B is a view showing a poangcurry sphere when the liquid crystal display panel is viewed from a diagonal direction.

9 is a diagram illustrating two-dimensionally the optical compensation mechanism according to the first embodiment of the present invention using the Poangcurry sphere shown in FIG. 8B. In this case, FIG. 9 corresponds to a view of the Poangcurry sphere shown in FIG. 8B from the front, and although before and after each change in the polarization state using the arrows in FIG. Even though the? Can be expressed on the Poangcurry sphere by rotation at a particular angle around a particular axis determined corresponding to each optical property.

At this time, as described above, the Poangcurry sphere represents all the polarization states of light on the spherical surface, and the polarization state can be easily predicted using the Poangcurry sphere when the optical axis and the phase delay value of the optical element are known. .

As shown in the figure, all of the points on the equator line in this Poangkar sphere represent linear polarization, the point at the North Pole S ₃ represents the right hand circular polarization, and the point at the South Pole -S ₃ represents the left hand circular polarization. In addition, the northern hemisphere of the remaining regions exhibits right-hand elliptical polarization and the southern hemisphere exhibits left-hand elliptical polarization.

In this case, as illustrated in FIG. 8A, points A and A 'represent absorption axes of the lower polarizer and transmission axes of the upper polarizer when the liquid crystal display is viewed from the front, and points B and B' correspond to the lower polarizer. The transmission axis and the absorption axis of the upper polarizing plate are shown. The polarization state of the upper polarizer and the lower polarizer is symmetrical with respect to the center O of the Poangcurry sphere, so that they are perpendicular to each other, thereby displaying an excellent dark state. That is, as described above, the opposite points A and B 'on the Poangcurry sphere exhibit polarization states orthogonal to each other.

However, as shown in FIG. 8B, when the liquid crystal display device is viewed from a diagonal direction, the transmission axis A ′ of the upper polarizer and the transmission axis B of the lower polarizer are moved a predetermined distance toward the S ₂ axis. The absorption axis B 'of the upper polarizer and the absorption axis A of the lower polarizer are moved a predetermined distance toward the -S ₂ axis. In this case, since the A point and the B 'point are not symmetrical with respect to the center O, the polarization states of the upper polarizer and the lower polarizer are not perpendicular to each other. Therefore, the optical axis of the light reaching the upper polarizing plate using the optical compensation film according to the first embodiment of the present invention should be made to coincide with the absorption axis of the upper polarizing plate.

8B and 9, the polarization state of incident light passing through the lower polarizer corresponds to point B, and the polarization state of the light absorbed and blocked by the absorption axis of the upper polarizer is blocked at the point B ′. Corresponding.

That is, after the incident light passes through the lower polarizing plate where the absorption axis is located at the point A on the Poangcurry sphere, it is linearly polarized and positioned at the point B. The linearly polarized light then passes through a homogeneous liquid crystal layer. Since the alignment direction of the liquid crystal layer is orthogonal to the polarization direction of the linearly polarized light, the linearly polarized light has no phase change in the liquid crystal layer. Therefore, the light passing through the liquid crystal layer maintains the same linear polarization state to have a polarization state corresponding to the point B.

As described above, in the transverse electric field type liquid crystal display device, light leakage off the axis in the diagonal direction is caused by a mismatch between the points B and B '. Therefore, the optical compensation film according to the first embodiment of the present invention is used to cause a change in the polarization state of incident light from point B to point B ', including a change in the polarization state of the liquid crystal layer.

Accordingly, when the transverse electric field type liquid crystal display device according to the first embodiment of the present invention is viewed from a diagonal direction, the polarization state of light passing through each optical element is first determined by the positive biaxial film as the first optical compensation film. It moves from point B to point C and moves from point C to point B 'by the negative biaxial film as the second optical compensation film. Therefore, the polarization state (B 'point) of the light reaching the upper polarizing plate coincides with the absorption axis of the upper polarizing plate, and the light is blocked, thereby indicating an excellent dark state.

That is, when the linearly polarized light passes through the positive biaxial film according to the first embodiment of the present invention in which the optical axis is located in a predetermined region between nz and ny, the linearly polarized light is transmitted through the optical axis of the positive biaxial film. By changing the effective phase delay value of the positive biaxial film clockwise by 2π times the value divided by 550nm, which is the wavelength of green, which affects the luminance, it is changed into elliptical polarized light at point C. The elliptical polarized light encounters a negative biaxial film, which is a second optical compensation film.

The negative biaxial film has an optical axis located in a predetermined region between nz and nx, and the elliptical polarized light is obtained by dividing the effective phase delay value of the negative biaxial film by 550 nm around the optical axis of the negative biaxial film. By rotating clockwise by 2π times, the light changes to linearly polarized light at B '. At this time, since the point B 'represents the absorption axis of the upper polarizing plate, the incident light is completely absorbed by the upper polarizing plate, thereby showing an excellent dark state.

As described above, in the first embodiment of the present invention, by controlling the polarization state by using the positive biaxial film and the negative biaxial film in order, the leakage of light and contrast can be prevented.

On the other hand, in the case of a transverse electric field type liquid crystal display device, a color shift phenomenon occurs according to a viewing angle due to dispersion characteristics of liquid crystals. This is compensated for, and light in all wavelength bands is collected at almost one point at the point B ', thereby improving the color shift.

FIG. 10 is a cross-sectional view schematically illustrating a transverse electric field liquid crystal display including an optical compensation film according to a second embodiment of the present invention, except that positions of the first optical compensation film and the second optical compensation film are changed. Is composed of the same components as the transverse electric field type liquid crystal display device of the first embodiment.

As shown in the figure, the transverse electric field type liquid crystal display device 200 according to the second embodiment of the present invention includes a liquid crystal display panel 210 for outputting an image and a lower portion of the liquid crystal display panel 210. The first polarizing plate 205 and the second polarizing plate 215 are disposed on the liquid crystal display panel 210.

The first polarizer 205 includes a first support 202 and a second support 204, and a first polarizer 203 positioned between the first support 202 and the second support 204. The second polarizer 215 may include a third support 212 and first and second optical compensation films 220 and 230, and the third support 212 and first and second optical compensation films 220 and 20. And a second polarizer 213 positioned between 230. In this case, the transverse electric field type liquid crystal display device 200 according to the second exemplary embodiment of the present invention sequentially rotates the second optical compensation film 230 and the first optical compensation film 220 on the liquid crystal display panel 210. It is characterized by being located.

In this case, the first polarizer 203 and the second polarizer 213 may be made of polyvinyl alcohol, and the first support 202 and the third support 212 may be a general protective film without phase delay. It may be made, for example, TAC. In addition, the second support 204 may be made of a general protective film without phase delay to protect the PVA layer, it may be made of 0-RT or COP as described above.

The first polarizing element 203 is disposed such that its absorption axis is substantially orthogonal to the absorption axis of the second polarizing element 213 facing each other, and the optical axis of the liquid crystal axis is the first polarizing element 203. It is in a state parallel to the light absorption axis of. In this case, as described above, when the first polarizing plate 205 is positioned above the liquid crystal display panel 210 and the second polarizing plate 215 is positioned below the liquid crystal display panel 210, the optical axis of the liquid crystal axis is It becomes a state parallel to the light absorption axis of the second polarizing element 213.

In the case of the second embodiment of the present invention, the first optical compensation film 220 and the second optical compensation between the second polarizing element 213 and the liquid crystal display panel 210 to improve the viewing angle characteristic in the diagonal direction. The film 230 is disposed, wherein the first optical compensation film 220 is formed of a positive biaxial film having −1.0 <Nz <0 while the second optical compensation film 230 is 1.0 <Nz <3.0. It is formed by the negative negative biaxial film. In addition, as described above, the transverse electric field type liquid crystal display device 200 according to the second exemplary embodiment of the present invention sequentially rotates the second optical compensation film 230 and the first optical compensation on the liquid crystal display panel 210. It is characterized in that the film 220 is located.

And, in the case of the second embodiment of the present invention as in the first embodiment described above, Nz has a value of about 1.0 to 3.0 as the negative biaxial film, and Re and Rth are values of 30 to 100 nm and 60 to 150 nm, respectively. Negative biaxial films can be used. In addition, as the positive biaxial film, Nz has a value of about -1.0 to 0, and Re and Rth may use a positive biaxial film having a value of 40 to 160 nm and -50 to 0 nm, respectively.

In this case, the films usable as the positive biaxial film and the negative biaxial film may be uniaxially stretched TAC (uniaxial stretched TAC), uniaxially stretched polycarbonate (PNB), biaxially stretched PC (polycarbonate), biaxially stretched COP, and the like. , Biaxial LC film, and the like.

The first optical compensation film 220 and the second optical compensation film 230 according to the second embodiment of the present invention having such an optical condition are formed of the first and second polarizing plates 205 and 215 in diagonal directions. By compensating for breaking of orthogonality, it is possible to reduce light leakage in the diagonal direction, which will be described in detail using the above-described Poangcurry phrase.

FIG. 11 is a view showing a Poangcurry sphere showing a polarization state of light passing through each optical element in the transverse electric field type liquid crystal display device according to the second embodiment of the present invention having the structure of FIG. Is a view showing a Poangcurry sphere when viewed from a diagonal direction.

FIG. 12 is a diagram two-dimensionally explaining the optical compensation mechanism according to the second embodiment of the present invention by using the Poangcurry sphere shown in FIG. 10. In this case, FIG. 12 corresponds to a view of the Poangcurry sphere shown in FIG. 11 from the front, and although before and after each change in polarization state using FIG. Even though the? Can be expressed on the Poangcurry sphere by rotation at a particular angle around a particular axis determined corresponding to each optical property.

11 and 12, when the transverse electric field type liquid crystal display device according to the second exemplary embodiment of the present invention is viewed in a diagonal direction, the polarization state of light passing through each optical element is first determined by the second optical compensation. It moves from point B to point C by the negative biaxial film which is a film, and moves from point C to B 'point by the positive biaxial film which is a 1st optical compensation film. Therefore, the polarization state (B 'point) of the light reaching the upper polarizing plate coincides with the absorption axis of the upper polarizing plate, and the light is blocked, thereby indicating an excellent dark state.

That is, when the linearly polarized light passes through the negative biaxial film according to the second embodiment of the present invention in which the optical axis is located at a predetermined region between nz and nx, the linearly polarized light is transmitted through the optical axis of the negative biaxial film. By changing the effective phase delay value of the negative biaxial film counterclockwise by 2π times the value divided by 550 nm, the elliptical polarized light is changed to the elliptical polarized light at point C. In positive biaxial film.

The positive biaxial film has an optical axis located in a predetermined region between nz and ny, and the elliptical polarized light is obtained by dividing the effective phase delay value of the positive biaxial film by 550 nm around the optical axis of the positive biaxial film. By rotating it counterclockwise by 2π times, it changes to linearly polarized light at B '. At this time, since the point B 'represents the absorption axis of the upper polarizing plate, the incident light is completely absorbed by the upper polarizing plate, thereby showing an excellent dark state.

As described above, in the second embodiment of the present invention, by adjusting the polarization state by using the negative biaxial film and the positive biaxial film in order, it is possible to prevent the leakage of light by preventing the light leakage.

In addition, in the case of the second embodiment of the present invention, as in the case of the first embodiment, the positional change for each wavelength is compensated, so that light of all wavelength bands is collected at almost one point at the B 'point, thereby improving the color shift. Will be.

FIG. 13 is a table illustrating conditions and transmittance characteristics of the optical compensation film used in the transverse electric field type liquid crystal display device according to the first and second embodiments of the present invention.

In this case, FIG. 13 sequentially shows values of 50 nm to 160 nm based on Re of the positive biaxial film, and accordingly, Rth of the positive biaxial film and Re and Rth of the negative biaxial film are the positive biaxial film. It is shown with Re of the film.

As shown in the figure, the maximum transmittance of each diagonal viewing angle measured in accordance with the optical conditions of the positive biaxial film and the negative biaxial film and the magnitude of the transmission relative to the reference conditions are shown.

The maximum transmittance of the diagonal viewing angle in the case of the reference conditions shown in FIGS. 3A and 3B described above corresponds to 0.001905. In the first and second embodiments of the present invention, the maximum transmittance of the diagonal viewing angle is compared with the reference conditions. It can be seen that it corresponds to about 4.5 ~ 44.7%.

Specifically, in the first and second embodiments of the present invention, Re of the positive biaxial film is 100 nm and Rth is -10 nm (Nz = -0.1), while Re and Rth of the negative biaxial film are 60 nm and When it corresponds to 96 nm (Nz = 1.6), the maximum transmittance of the diagonal viewing angle is 0.000085, which corresponds to about 4.5% of the reference condition, thereby minimizing light leakage in the diagonal direction.

In addition, when Re and Rth of the positive biaxial film are 50 nm and -30 nm, respectively, and when Re and Rth of the negative biaxial film correspond to 70 nm and 112.5 nm, respectively, the maximum transmittance of the diagonal viewing angle is 0.000317 compared to the reference condition. It can be seen that it corresponds to about 16.6%, the maximum transmittance of the diagonal viewing angle when the Re and Rth of the positive biaxial film is 60nm and -30nm, respectively, and the Re and Rth of the negative biaxial film correspond to 60nm and 90nm, respectively Is 0.000275, which corresponds to about 14.4% of the reference condition.

When the Re and Rth of the positive biaxial film are 70 nm and -35 nm, respectively, and the Re and Rth of the negative biaxial film correspond to 70 nm and 115 nm, respectively, the maximum transmittance of the diagonal viewing angle is 0.000133, which is about the reference condition. 7.0%, and when the Re and Rth of the positive biaxial film is 80nm and -50nm, respectively, and the Re and Rth of the negative biaxial film correspond to 80nm and 130nm, respectively, the maximum transmittance of the diagonal viewing angle is 0.000190 corresponds to about 10.0% of the reference conditions.

When the Re and Rth of the positive biaxial film are 90 nm and -27 nm, respectively, and the Re and Rth of the negative biaxial film correspond to 65 nm and 104 nm, respectively, the maximum transmittance of the diagonal viewing angle is 0.000093, which is about the reference condition. 4.9%, and when the Re and Rth of the positive biaxial film is 110nm and -11nm, respectively, and the Re and Rth of the negative biaxial film correspond to 50nm and 90nm, respectively, the maximum transmittance of the diagonal viewing angle is 0.000138 corresponds to about 7.2% of the reference condition.

When the Re and Rth of the positive biaxial film are 120 nm and -12 nm, respectively, and the Re and Rth of the negative biaxial film correspond to 40 nm and 84 nm, respectively, the maximum transmittance of the diagonal viewing angle is 0.000217, which is about the reference condition. It can be seen that 11.4%, and when the Re and Rth of the positive biaxial film is 130nm and -13nm respectively and the Re and Rth of the negative biaxial film correspond to 50nm and 100nm respectively, the maximum transmittance of the diagonal viewing angle is 0.000297 corresponds to about 15.6% of the reference conditions.

When the Re and Rth of the positive biaxial film are 140 nm and -14 nm, respectively, and the Re and Rth of the negative biaxial film correspond to 50 nm and 110 nm, respectively, the maximum transmittance of the diagonal viewing angle is 0.000478, which is about the reference condition. 25.1%, and the maximum transmittance of the diagonal viewing angle is when Re and Rth of the positive biaxial film are 150 nm and -15 nm, respectively, and Re and Rth of the negative biaxial film correspond to 50 nm and 100 nm, respectively. 0.000713, which corresponds to about 37.4% of the reference conditions.

When the Re and Rth of the positive biaxial film are 160 nm and -16 nm, respectively, and the Re and Rth of the negative biaxial film correspond to 40 nm and 96 nm, respectively, the maximum transmittance of the diagonal viewing angle is 0.000851, which is about the reference condition. 44.7%.

14 and 15 show simulation results of the viewing angle characteristics in the dark state in the transverse electric field type liquid crystal display device according to the first and second embodiments of the present invention having such a structure.

14 and 15 are diagrams showing, for example, the result of simulating the luminance viewing angle characteristic in the dark state in the transverse electric field type liquid crystal display device according to the first and second embodiments of the present invention.

Here, the lower polarizer and the upper polarizer are arranged such that the light absorption axes are perpendicular to each other, and the optical axis of the liquid crystal layer is in a state parallel to the light absorption axis of the lower polarizer.

14 and 15 show the optical compensation film according to the first and second embodiments of the present invention at an inclination angle in the range of 0 to 80 degrees with respect to all the mirror angles (or azimuth angles) when white light is used. The contrast ratio of the transverse electric field liquid crystal display device is included. In addition, in FIG. 14 and FIG. 15, the center of the circle is a case where the inclination angle is 0, and the inclination angle increases as the radius of the circle increases.

In addition, FIG. 14 shows the results of simulating the brightness characteristics of the dark state when Re and Rth of the negative biaxial film are 70 nm and 105 nm, respectively, and Re and Rth of the positive biaxial film correspond to 70 nm and -35 nm, respectively. FIG. 15 shows the results of simulating the brightness characteristics of the dark state when Re and Rth of the negative biaxial film are 70 nm and 105 nm, respectively, and Re and Rth of the positive biaxial film correspond to 67 nm and -33.5 nm, respectively. have.

As shown in the figure, it can be seen that the light leakage is significantly reduced at 45 degrees, 135 degrees, 225 degrees and 315 degrees corresponding to the diagonal direction of the liquid crystal display panel in the dark state. Accordingly, it can be seen that the brightness of the liquid crystal display is reduced and the contrast ratio is improved in the dark state. For example, referring to FIG. 14, it can be seen that the maximum transmittance of the diagonal viewing angle in the dark state corresponds to about 0.000102 at an omnidirectional angle. Referring to FIG. 15, the maximum transmission of the diagonal viewing angle in the dark state is about 0.000135 at anterior angle. It can be seen that. This means that the luminance of the dark state is reduced by 90% or more at a value corresponding to 5% and 7%, respectively, compared to the maximum transmittance of the conventional liquid crystal display shown in FIG. 3B.

FIG. 16 is a cross-sectional view schematically illustrating a transverse electric field type liquid crystal display device including an optical compensation film according to a third embodiment of the present invention, wherein a negative C plate-like film is added between the second polarizing element and the second optical compensation film. Except for that, the same components as those of the transverse electric field type liquid crystal display device of the first embodiment are used.

As shown in the figure, the transverse electric field type liquid crystal display device 300 according to the third embodiment of the present invention includes a liquid crystal display panel 310 for outputting an image and a lower portion of the liquid crystal display panel 310. The first polarizing plate 305 and the second polarizing plate 315 are disposed on the liquid crystal display panel 310.

At this time, although not shown in detail in the drawing, the liquid crystal display panel 310 is largely composed of a color filter substrate and an array substrate and a liquid crystal layer formed between the color filter substrate and the array substrate.

The first polarizer 305 includes a first support 302 and a second support 304 and a first polarizer 303 positioned between the first support 302 and the second support 304. The second polarizer 315 may include a third support 312 and first, second and third optical compensation films 320, 330, and 340, and the third support 312 and the first, second, The second polarizer 313 is disposed between the third optical compensation films 320, 330, and 340. In this case, the transverse electric field type liquid crystal display device 300 according to the third exemplary embodiment of the present invention sequentially rotates the first optical compensation film 320 and the second optical compensation film 330 on the liquid crystal display panel 310. And a third optical compensation film 340 is located.

In this case, the first polarizer 303 and the second polarizer 313 may be made of PVA, and the first support 302 and the third support 312 are made of a general protective film without phase delay. For example, it may be made of TAC. In addition, the second support 304 may be made of a general protective film without phase delay to protect the PVA layer, for example, may be made of 0-RT or COP.

In the third exemplary embodiment of the present invention, the first optical compensation film 320 and the second optical compensation are disposed between the second polarizing element 313 and the liquid crystal display panel 310 to improve the viewing angle characteristic in the diagonal direction. The film 330 and the third optical compensation film 340 are disposed, wherein the first optical compensation film 320 is formed of a positive biaxial film having −1.0 <Nz <0 while the second optical compensation film 330 is formed of a negative biaxial film having 1.0 <Nz <3.0. In addition, the third optical compensation film 340 is formed of a negative C plate-like film of Re = 0 and Rth = 20 ~ 80nm.

In the third embodiment of the present invention as in the first to second embodiments described above, Nz has a value of about 1.0 to 3.0 as the negative biaxial film, and Re and Rth are 30 to 100 nm, respectively. Negative biaxial films with values between 60 and 150 nm can be used. In addition, as the positive biaxial film, Nz has a value of about -1.0 to 0, and Re and Rth may use a positive biaxial film having a value of 40 to 160 nm and -50 to 0 nm, respectively.

In this case, the negative C plate-like film refers to a negative uniaxial optical device having a refractive index distribution of nx = ny> nz, wherein Re is 0 and Rth is greater than 0, and the refractive index distribution is nx = ny> nz. The negative monoaxial optical element that satisfies has an optical axis in the normal direction.

In this case, the negative C plate-like film used in the third embodiment of the present invention may include a polymer film mainly composed of a thermoplastic resin, and the thermoplastic resin is a polymer film mainly composed of an amorphous polymer and the amorphous polymer. Has the advantage of excellent transparency.

As said thermoplastic resin, polyolefin resin, cycloolefin resin, polyvinyl chloride resin, cellulose resin, styrene resin, acrylonitrile butadiene styrene resin, acrylonitrile styrene resin, polymethacrylic acid General-purpose plastics such as methyl, polyvinyl acetate, and polyvinylidene chloride-based resins; General-purpose engineering plastics such as polyamide resin, polyacetal resin, polycarbonate resin, modified polyphenylene ether resin, polybutylene terephthalate resin and polyethylene terephthalate resin; Polyphenylene sulfide resin, polysulfone resin, polyether sulfone resin, polyether ether ketone resin, polyallylate resin, liquid crystalline resin, polyamideimide resin, polyimide resin, polytetrafluoro Super engineering plastics, such as ethylene resin, etc. are mentioned. In this case, the thermoplastic resins may be used alone or in combination of two or more thereof. In addition, said thermoplastic resin can also be used by performing arbitrary appropriate polymer modifications, and examples of the polymer modification include modification such as copolymerization, crosslinking, molecular terminal, stereoregularity and the like.

In addition, the negative C plate-like film may include a stretched film of a polymer film mainly containing a thermoplastic resin.

The negative C plate-like film may include a retardation film using a liquid crystal composition.

The first optical compensation film 320, the second optical compensation film 330 and the third optical compensation film 340 according to the third embodiment of the present invention having such optical conditions are the first, By compensating for breaking the orthogonality of the second polarizing plates 305 and 315, light leakage in the diagonal direction can be reduced.

FIG. 17 is a cross-sectional view schematically illustrating a transverse electric field type liquid crystal display device including an optical compensation film according to a fourth embodiment of the present invention, wherein a negative C plate-like film is added between the second polarizing element and the first optical compensation film. Except for that, the same components as those of the transverse electric field type liquid crystal display device of the second embodiment are used.

As shown in the figure, the transverse electric field type liquid crystal display device 400 according to the fourth embodiment of the present invention includes a liquid crystal display panel 410 for outputting an image and a lower portion of the liquid crystal display panel 410. The first polarizer 405 and the second polarizer 415 are disposed on the liquid crystal display panel 410.

The first polarizer 405 includes a first support 402 and a second support 404, and a first polarizer 403 positioned between the first support 402 and the second support 404. The second polarizer 415 may include a third support 412, first, second, and third optical compensation films 420, 430, and 440, and the third support 412 and first, second, The second polarizer 413 is disposed between the third optical compensation films 420, 430, and 440. In this case, the transverse electric field type liquid crystal display device 400 according to the fourth exemplary embodiment of the present invention sequentially rotates the second optical compensation film 430 and the first optical compensation film 420 on the liquid crystal display panel 410. And a third optical compensation film 440 is located.

In this case, the first polarizer 403 and the second polarizer 413 may be made of PVA, the first support 402 and the third support 412 is made of a general protective film without phase delay For example, it may be made of TAC. In addition, the second support 404 may be made of a general protective film without phase delay to protect the PVA layer, for example, may be made of 0-RT or COP.

In the case of the fourth exemplary embodiment of the present invention, the first optical compensation film 420 and the second optical compensation between the second polarizing element 413 and the liquid crystal display panel 410 in order to improve the viewing angle characteristic in the diagonal direction. The film 430 and the third optical compensation film 440 are disposed, wherein the first optical compensation film 420 is formed of a positive biaxial film having −1.0 <Nz <0 while the second optical compensation film 430 may be formed of a negative biaxial film having 1.0 <Nz <3.0. In addition, the third optical compensation film 440 may be formed of a negative C plate-like film having Re = 0 and Rth = 20 to 80 nm. In addition, as described above, the transverse electric field type liquid crystal display device 400 according to the fourth exemplary embodiment of the present invention sequentially rotates the second optical compensation film 430 and the first optical compensation on the liquid crystal display panel 410. The film 420 and the third optical compensation film 440 is characterized in that located.

In the fourth embodiment of the present invention as in the first to third embodiments described above, Nz has a value of about 1.0 to 3.0 as the negative biaxial film, and Re and Rth are 30 to 100 nm, respectively. Negative biaxial films with values between 60 and 150 nm can be used. In addition, as the positive biaxial film, Nz has a value of about -1.0 to 0, and Re and Rth may use a positive biaxial film having a value of 40 to 160 nm and -50 to 0 nm, respectively.

Many details are set forth in the foregoing description but should be construed as illustrative of preferred embodiments rather than to limit the scope of the invention. Therefore, the invention should not be defined by the described embodiments, but should be defined by the claims and their equivalents.

1 is a plan view schematically illustrating a portion of an array substrate of a general transverse electric field type liquid crystal display device;

FIG. 2 is an exemplary view showing a cross section taken along line II ′ of the array substrate shown in FIG. 1. FIG.

FIG. 3A is a view showing a result of simulating a luminance viewing angle characteristic in a dark state in a general transverse electric field type liquid crystal display device. FIG.

3B is a view showing the results of measuring luminance viewing angle characteristics in a dark state in a general transverse electric field liquid crystal display device;

4A is an exemplary view schematically showing a light transmission axis of an orthogonal upper and lower polarizing plate when viewed from the front.

4B is an exemplary view schematically showing the light transmission axes of the upper and lower polarizing plates that are perpendicular to each other when viewed in a diagonal direction.

5 is a cross-sectional view schematically showing a transverse electric field type liquid crystal display device including an optical compensation film according to a first embodiment of the present invention.

6A, 6B and 6C are diagrams for defining Re, Rth and Nz used in the present invention.

7A and 7B are diagrams showing arbitrary elliptical polarizations and corresponding poangkare vectors in a rectangular coordinate system.

8A and 8B are views illustrating a Poangcurry sphere showing polarization states of light passing through each optical element in the transverse electric field type liquid crystal display device according to the first embodiment of the present invention having the structure of FIG.

FIG. 9 is a diagram two-dimensionally illustrating an optical compensation mechanism according to a first embodiment of the present invention using the Poangcurry sphere shown in FIG. 8;

10 is a cross-sectional view schematically showing a transverse electric field type liquid crystal display device including an optical compensation film according to a second embodiment of the present invention.

FIG. 11 is a view showing a Poangcurry sphere showing a polarization state of light passing through each optical element in the transverse electric field type liquid crystal display device according to the second embodiment of the present invention having the structure of FIG. 10.

FIG. 12 is a two-dimensional illustration of an optical compensation mechanism according to a second embodiment of the present invention using the Poangcurry sphere shown in FIG. 10;

FIG. 13 is a table illustrating conditions and transmittance characteristics of optical compensation films used in the transverse electric field type liquid crystal display device according to the first and second embodiments of the present invention. FIG.

14 and 15 are diagrams showing, for example, the result of simulating the luminance viewing angle characteristic in the dark state in the transverse electric field type liquid crystal display device according to the first and second embodiments of the present invention.

16 is a cross-sectional view schematically showing a transverse electric field type liquid crystal display device including an optical compensation film according to a third embodiment of the present invention.

FIG. 17 is a cross-sectional view schematically illustrating a transverse electric field liquid crystal display device including an optical compensation film according to a fourth embodiment of the present invention. FIG.

** Explanation of symbols for main parts of drawings **

100 to 400: liquid crystal display 110 to 410: liquid crystal display panel

102 to 402: first support 103 to 403: first polarizer

104-404: 2nd support body 105-405: 1st polarizing plate

112 to 412: third support body 113 to 413: second polarizer

115 to 415: second polarizing plate 120 to 420: first optical compensation film

130 to 430: second optical compensation film 340,440: third optical compensation film

Claims (25)

A liquid crystal display panel including a liquid crystal layer; A first polarizer disposed under the liquid crystal display panel, the first polarizer including a first support and a second support and a first polarizer disposed between the first support and the second support; And A second polarizing plate disposed on the liquid crystal display panel, the second polarizing plate including a third support, a first and a second optical compensation film, and a second polarization element disposed between the third support and the first and second optical compensation films; Include, The first optical compensation film is defined as −1.0 <Nz <0 (where Nz = Rth / Re, Re = (nx-ny) · d and Rth = (nx-nz) · d, and the nx, ny and nz means a refractive index in the x direction, y direction and z direction, respectively, d means the thickness of the film) and the second optical compensation film is negative 2 with 1.0 <Nz <3.0 It is made of a axial film, wherein the positive biaxial film is a transverse electric field liquid crystal display device comprising an optical compensation film, characterized in that located between the negative biaxial film and the liquid crystal display panel. A liquid crystal display panel including a liquid crystal layer; A first polarizer disposed under the liquid crystal display panel, the first polarizer including a first support and a second support and a first polarizer disposed between the first support and the second support; And A second polarizing plate disposed on the liquid crystal display panel, the second polarizing plate including a third support, a first and a second optical compensation film, and a second polarization element disposed between the third support and the first and second optical compensation films; Include, The first optical compensation film is defined as −1.0 <Nz <0 (where Nz = Rth / Re, Re = (nx-ny) · d and Rth = (nx-nz) · d, and the nx, ny and nz means a refractive index in the x direction, y direction and z direction, respectively, d means the thickness of the film) and the second optical compensation film is negative 2 with 1.0 <Nz <3.0 It is made of a axial film, the negative biaxial film is a transverse electric field type liquid crystal display device comprising an optical compensation film, characterized in that located between the positive biaxial film and the liquid crystal display panel. The transverse electric field liquid crystal display device of claim 1, wherein the absorption axis of the first polarizer and the absorption axis of the second polarizer are perpendicular to each other. The transverse electric field liquid crystal display device of claim 3, wherein an optical axis of the liquid crystal layer is parallel to an absorption axis of the first polarizer. 4. The transverse electric field liquid crystal display device according to claim 3, wherein the optical axis of the liquid crystal layer is parallel to the absorption axis of the second polarizing element. 4. The transverse electric field liquid crystal of claim 3, wherein the first support and the third support are made of a protective film without phase delay, such as tri-acetyl cellulose (TAC). Display. The transverse electric field liquid crystal display device according to claim 3, wherein the second support is made of a protective film without phase delay. The transverse electric field liquid crystal of claim 7, wherein the protective film comprises 0-RT (modified TAC in which Rth is close to 0 nm), cyclo-olefin-polymer (COP), or the like. Display. The transverse electric field liquid crystal display device according to claim 3, wherein the positive biaxial film has a phase delay value of about 40 to 160 nm. The transverse electric field liquid crystal display device of claim 3, wherein the positive biaxial film has a phase delay value of about -50 nm to about 0 nm. The transverse electric field liquid crystal display device of claim 3, wherein the negative biaxial film has a phase delay value of about 30 to 100 nm. 4. The transverse electric field liquid crystal display device according to claim 3, wherein the negative biaxial film has a phase delay value of about 60 to 150 nm in Rth. 4. The positive biaxial film has a phase delay value of Re and Rth of 100 nm and -10 nm, respectively, and the negative biaxial film has Re of 60 and Rth of 96 nm of phase delay value. Transverse electric field type liquid crystal display device comprising an optical compensation film. The optical compensation of claim 1, wherein the light passing through the positive biaxial film and the negative biaxial film sequentially through the liquid crystal display panel has a polarization state coinciding with an absorption axis of the second polarizer. Transverse electric field type liquid crystal display device comprising a film. 3. The optical compensation of claim 2, wherein the light passing through the negative biaxial film and the positive biaxial film sequentially through the liquid crystal display panel has a polarization state coinciding with an absorption axis of the second polarizing element. Transverse electric field type liquid crystal display device comprising a film. 4. The transverse electric field liquid crystal display of claim 3, further comprising a negative C plate-like film positioned between the second polarizer and the first and second optical compensation films. Device. The transverse electric field liquid crystal display device of claim 16, wherein the negative C plate-like film has a phase delay value of Re of 0 and Rth of about 20 to 80 nm. A liquid crystal display panel including a liquid crystal layer; A first polarizer disposed under the liquid crystal display panel, the first polarizer including a first support and a second support and a first polarizer disposed between the first support and the second support; And A second polarizing plate disposed on the liquid crystal display panel, the second polarizing plate including a third support, a first and a second optical compensation film, and a second polarization element disposed between the third support and the first and second optical compensation films; Include, And the first optical compensation film is made of a positive biaxial film, and the second optical compensation film is made of a negative biaxial film. 19. The method of claim 18, wherein the positive biaxial film is defined as -1.0 < Nz < 0, wherein Nz = Rth / Re, Re = (nx-ny) d and Rth = (nx-nz) d, The nx, ny and nz means the refractive index in the x direction, y direction and z direction, respectively, d means the thickness of the film), the negative biaxial film is 1.0 <Nz <3.0 Transverse electric field type liquid crystal display device comprising an optical compensation film, characterized in that to satisfy the conditions. 19. The transverse electric field liquid crystal display device according to claim 18, wherein the positive biaxial film has a phase delay value of about 40 to 160 nm. 19. The transverse electric field liquid crystal display of claim 18, wherein the positive biaxial film has a phase delay value of about -50 nm to about 0 nm. 19. The transverse electric field liquid crystal display device according to claim 18, wherein the negative biaxial film has a phase delay value of about 30 to 100 nm. 19. The transverse electric field liquid crystal display device according to claim 18, wherein the negative biaxial film has a phase delay value of about 60 to 150 nm in Rth. 19. The transverse electric field liquid crystal display of claim 18, further comprising a negative C plate-like film positioned between the second polarizer and the first and second optical compensation films. Device. 25. The transverse electric field liquid crystal display device according to claim 24, wherein the negative C plate-like film has a phase delay value of Re of 0 and Rth of about 20 to 80 nm.

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