KR102108555B1 - Polarizing plate, polarizing set and liquid crystal display - Google Patents

Abstract

The present invention relates to a polarizing plate, a polarizing plate set, and a liquid crystal display device. The polarizing plate to the polarizing plate set of the present invention is excellent in optical properties such as light leakage characteristics in the viewing angle, it is possible to provide a planar switching mode liquid crystal display device capable of exhibiting a desired visual acuity.

Description

Polarizing plate, polarizing set and liquid crystal display

The present invention relates to a polarizing plate, a polarizing plate set, and a liquid crystal display device.

IPS-LCD refers to an LCD in which the initial liquid crystal orientation is horizontal to the glass substrate and is oriented at a constant angle to the electrode, and the direction of the electric field is formed parallel to the glass substrate. IPS-LCD shows a yellow color in the oblique direction depending on the characteristics of the panel, and thereby, there is a problem in that light leakage is large in the dark state (black state) and the visibility decreases.

United States Patent Registration Publication No. 3807831

In order to solve the above problem, it is necessary to improve luminance and color in the oblique direction. The present invention is to solve the above problems, and an object of the present invention is to provide a polarizing plate, a polarizing plate set, and a liquid crystal display device capable of realizing excellent optical characteristics and a desired viewing angle in a viewing angle.

The present invention relates to a polarizing plate set. The polarizing plate set may include an upper polarizing plate and a lower polarizing plate. The upper polarizing plate may include a first polarizing element and a first protective film stacked on one surface of the first polarizing element. The second polarizing element and a second protective film laminated on one surface of the second polarizing element may be included. The first and second protective films may be retardation films, respectively.

In this specification, the term polarizing element and the polarizing plate refer to objects that are distinguished from each other. The term polarizing element means a film, sheet, or element having a polarizing function itself, and the term polarizing plate means an object including the polarizing element and other elements laminated on one or both sides of the polarizing element. Other elements in the above may be exemplified by the retardation layer or a polarizing element protective film, but are not limited thereto.

The polarizing element is a functional element capable of extracting light oscillating in one direction from incident light oscillating in various directions. As the polarizing element, for example, a known absorption type linear polarizing element can be used. As such a polarizing element, a poly (vinyl alcohol) (PVA) polarizing element may be exemplified. In one example, the polarizing element included in the polarizing plate may be a PVA film or sheet in which a dichroic dye or iodine is adsorbed and oriented. The PVA can be obtained, for example, by gelling polyvinyl acetate. As polyvinyl acetate, a homopolymer of vinyl acetate; And copolymers of vinyl acetate and other monomers. In the above, as the other monomer copolymerized with vinyl acetate, an unsaturated carboxylic acid compound, an olefin compound, a vinyl ether compound, an unsaturated sulfonic acid compound, and an acrylamide compound having an ammonium group or the like may be exemplified. The degree of gelation of the polyvinyl acetate is generally about 85 mol% to about 100 mol% or 98 mol% to 100 mol%. The degree of polymerization of the polyvinyl alcohol in the linearly polarizing element may generally be about 1,000 to about 10,000 or about 1,500 to about 5,000.

In the present specification, the retardation film may mean an element capable of converting incident polarization by controlling birefringence as an optically anisotropic layer. In the present specification, the x-axis refers to a direction parallel to the in-plane slow axis of the retardation film, and the y-axis refers to a direction parallel to the in-plane true axis of the retardation film, unless otherwise specified while describing the x-axis, y-axis, and z-axis of the retardation film. Means, and the z-axis means the thickness direction of the retardation film. The x-axis and the y-axis may be orthogonal to each other in a plane. In the present specification, when the retardation film includes rod-shaped liquid crystal molecules, the slow axis may mean the long axis direction of the rod shape, and when the retardation film includes the disk-shaped liquid crystal molecule, the slow axis may mean the normal direction of the disc shape. . In this specification, the optical axis of the retardation film is described, and unless otherwise specified, it means the slow axis. In this specification, the refractive index of the retardation film is described, and unless otherwise specified, it means the refractive index for light having a wavelength of about 550 nm.

When using the terms vertical, horizontal, orthogonal or parallel while defining an angle herein, it means substantially vertical, horizontal, orthogonal or parallel in a range that does not impair the desired effect, for example. , Including errors in consideration of manufacturing errors or variations. For example, each of the above cases may include an error within about ± 15 degrees, an error within about ± 10 degrees, or an error within about ± 5 degrees.

In this specification, the in-plane retardation (Rin) and the thickness direction retardation (Rth) of the retardation film are calculated by Equation 1 and Equation 2, respectively.

[Equation 1]

Rin = d × (nx-ny)

[Equation 2]

Rth = d x (nz-ny)

In Equations 1 to 2, d is the thickness of the retardation film, and nx, ny, and nz are refractive indexes in the x-axis, y-axis, and z-axis directions defined above, respectively. In the present specification, the retardation of the retardation film refers to a refractive index for light having a wavelength of about 550 nm unless otherwise specified.

In the present invention, satisfying Equation 3 below may be defined as a + B film, satisfying Equation 4, a -B film, satisfying Equation 5, a + C plate, and satisfying Equation 6, as a -C plate.

[Equation 3]

nz> nx> ny

[Equation 4]

nx> ny> nz

[Equation 5]

nz> nx = ny

[Equation 6]

nx = ny> nz

The present invention has the advantage of arranging the first protective film on the upper polarizing plate and placing the second protective film on the lower polarizing plate, thereby maintaining the balance between the upper and lower portions. Maintaining the balance of the upper and lower portions may be advantageous in that it can prevent warping of the liquid crystal panel that occurs after the durability evaluation of the liquid crystal panel.

The first protective film may be a first retardation film having an in-plane retardation value of 90 nm to 200 nm and a thickness direction retardation value of 130 nm to 220 nm. The first retardation film may be classified as + B film. The in-plane retardation value of the first retardation film may be specifically 90 nm or more, 100 nm or more, or 110 nm or more, and may be 200 mm or less, 190 mm or less, 180 mm or less, or 170 mm or less. The thickness direction retardation value of the first retardation film may be specifically 130 nm or more, 140 nm or more, or 150 nm or more, and may be 220 nm or less, 210 nm or less, or 200 nm or less.

The second protective film is a second retardation film having a plane retardation value of 20 nm to 100 nm, a thickness retardation value of 20 nm to 140 nm, or a plane retardation value of 0 nm to 10 nm, and a thickness retardation value of 60 nm to 170 nm It may be a retardation film. The second retardation film may be classified as a + B film, and the third retardation film may be classified as a + C plate. The planar retardation value of the second retardation film may be specifically 20 nm or more, 30 nm or more, or 40 nm or more, and may be 100 nm or less, 90 nm or less, or 80 nm or less. The thickness direction retardation value of the second retardation film may be specifically 20 nm or more, 50 nm or more, or 60 nm or more, and may be 140 nm or less or 130 nm or less. The planar retardation value of the third retardation film may be specifically 0 nm or more, 10 nm or less, 8 nm or less, and 5 nm or less. The thickness direction retardation value of the third retardation film may be specifically 60 nm or more, 70 nm or more, 80 nm or more, 90 nm or more, or 100 nm or more, and 170 nm or less, 160 nm or less, 150 nm or less, or 140 nm or less. . When the in-plane retardation values or the thickness-direction retardation values of the first and second protective films are within the above ranges, it is possible to provide an in-plane switching mode liquid crystal display having improved optical and visual characteristics in an oblique direction.

In one example, the absorption axis of the first polarization element and the absorption axis of the second polarization element may be orthogonal to each other.

In one example, the absorption axis of the first polarizing element and the in-plane optical axis of the first retardation film may be parallel or orthogonal, and the absorption axis of the second polarizing element and the in-plane optical axis of the second retardation film may be parallel or orthogonal. Through such an arrangement, it is possible to provide an in-plane switching mode liquid crystal display having improved optical and visual characteristics in an oblique direction.

In one example, the first protective film and the second protective film may be located inside the first polarizing element and the second polarizing element, respectively. The first and second protective films may be inner protective films of the first and second polarizing elements, respectively. When the upper polarizing plate and the lower polarizing plate are applied to the liquid crystal display, the first protective film and the second protective film may be disposed adjacent to the liquid crystal panel, respectively.

In one example, the first and second protective films may be one retardation film. In order to implement the retardation values of the first to second retardation films, when a stacked structure of several retardation films is applied, it is not preferable because there is a problem in that manufacturing costs increase and thickness increases.

In one example, each of the first protective film and the second protective film may be a polymer film. As the polymer film, for example, a polyolefin film such as a polyethylene film or a polypropylene film, a cycloolefin polymer (COP) film such as a polynorbornene film, a polyvinyl chloride film, a polyacrylonitrile film, poly A cellulose ester polymer film such as a sulfone film, a polyacrylate film, a polyvinyl alcohol film, or a triacetyl cellulose (TAC) film, or a copolymer film of two or more monomers among the monomers forming the polymer may be exemplified.

In one example, as the polymer film, a cyclic olefin polymer film or an acrylic film can be used. As the cyclic olefin polymer, a ring-opening polymer of a cyclic olefin such as norbornene or a hydrogenated product thereof, an addition polymer of a cyclic olefin, a copolymer of a cyclic olefin and another comonomer such as alpha-olefin, or the polymer Or a graft polymer obtained by modifying a copolymer with an unsaturated carboxylic acid or a derivative thereof, or the like can be exemplified. According to an embodiment of the present invention, the polymer film may be an acrylic film. The present invention has an advantage that the retardation film can be provided as a single film through an acrylic film. When the acrylic film is stretched or contracted under appropriate conditions, birefringence is imparted, and the retardation film can be used.

In one example, the polymer film may use a resin containing a substituted or unsubstituted styrene group in the main chain and / or a blend containing the resin. More specifically, as the resin containing the substituted or unsubstituted styrene group, styrene-acrylonitrile copolymer (SAN), methyl methacrylate-styrene (MS), styrene-maleic anhydride (SMA), styrene-maleic anhydride- Resins comprising methyl methacrylate copolymers can be used. More specifically, the polymer film may include an acrylic resin containing a resin containing a substituted or unsubstituted styrene group. As the acrylic resin, an acrylic resin composed of methacrylic acid ester and acrylic acid ester may be used. The acrylic resin may include an acrylic copolymer resin containing a ring structure such as N-substituted maleimide, lactone ring, glutimide, maleic anhydride. The glass transition temperature of the resin contained in the polymer film may be 100 ° C or higher, preferably 110 ° C or higher. The thickness of the polymer film may be 80 μm or less. The polymer film may be manufactured through extrusion or casting, and may be manufactured through biaxial stretching (simultaneous or sequential).

Each of the first and second protective films may have a phase difference deviation within 5% from the center value, and the optical axis is preferably ± 0.5 degrees. When the phase difference and the optical axis are within the above ranges, it is advantageous in terms of preventing deterioration of front contrast and improving viewing angle.

Each of the first and second protective films may have a phase difference deviation within 5% from the center value, and the optical axis is preferably ± 0.5 degrees. When the phase difference and the optical axis are within the above range, it is advantageous in terms of improving optical properties in front contrast and viewing angle.

In one example, the first and second protective films may each have positive, reverse, or flat dispersion properties. The normal dispersion characteristic may mean the following Equation 7, the reverse dispersion characteristic may mean the following Equation 8, and the flat dispersion characteristic may mean the following Equation 9. When the first and second protective films each have a normal wavelength dispersion characteristic, it may be more advantageous to provide an in-plane switching mode liquid crystal display having improved optical and visual characteristics in an oblique direction. The values of the dispersion properties R (450) / R (550) of the first and second protective films may be 1.04 to 1.08, respectively.

[Equation 7]

R (450) / R (550)> 1

[Equation 8]

R (450) / R (550) <1

[Equation 9]

R (450) / R (550) = 1

In Equations 7 to 9, R (λ) is the planar phase difference of the phase difference film for λnm light.

In one example, the second protective film may be the second retardation film. In this case, the Nz coefficient of the second retardation film may be -1.5 to 0.7. In another example, the second protective film may be a third retardation film. In this case, the Nz coefficient of the third retardation film may be greater than -16. The upper limit of the Nz coefficient of the third retardation film has an infinity (∞) value. In this specification, the Nz coefficient may be calculated by Equation 10 below. When the Nz coefficients of the second to third retardation films are within the above range, it may be more advantageous to provide an in-plane switching mode liquid crystal display having improved optical and visual characteristics in an oblique direction.

[Equation 10]

Nz = 1-Rth / Rin

In Equation 10, Rin is an in-plane retardation value of the retardation film calculated by Equation 1, and Rth is a thickness direction retardation value of the retardation film calculated by Equation 2.

In one example, the first protective film and the second protective film may satisfy Equation 11 or 12 below. When the first protective film and the second protective film satisfy the following formulas 11 or 12, it may be more advantageous to provide a planar switching mode liquid crystal display device with improved optical and visual characteristics in an oblique direction. In particular, it is preferable to satisfy Equation 11 in order to implement the luminance value described below to 1.10 or less, and it may be desirable to satisfy Equation 12 to implement the luminance value described below in the range of 1.11 to 1.50.

[Equation 11]

│ △ Re│> │ △ Rth│-5

[Equation 12]

│ △ Re│ ≤ │ △ Rth│ + 5

In Equations 11 to 12, │ΔRe│ is the absolute value of the difference in the plane retardation values of the first protective film and the second protective film, and │ΔRth│ is the phase difference in the thickness direction between the first protective film and the second protective film. The absolute value of the difference in values.

Each of the retardation film and the polarizing element may be attached to each other by an appropriate adhesive or adhesive, for example, to form an optical film. The retardation film and the polarizing element may be directly attached through the adhesive layer or the adhesive layer, or may be attached by further including a primer layer, if necessary.

The method of attaching the retardation film and the polarizing element is not particularly limited. For example, the adhesive or pressure-sensitive adhesive composition is coated on one surface of a polarizing element or retardation film, and after lamination, the adhesive composition is cured, or the polarizing element or retardation film is formed by a dropping method using the adhesive or pressure-sensitive adhesive composition. A method of laminating and curing the composition may be used. In the above, curing of the composition may be performed by irradiating an active energy ray of an appropriate intensity with an appropriate amount of light, for example, taking into account the components included in the composition.

The present invention relates to an upper polarizing plate. The upper polarizing plate is an upper polarizing plate including a first polarizing element and a first protective film stacked on one surface of the first polarizing element, and a second polarizing element and a second protective film stacked on one surface of the second polarizing element are provided. It may be used with a lower polarizing plate.

The first protective film may have a plane phase difference value of 90 nm to 200 nm, and a thickness direction phase difference value of 130 nm to 220 nm.

The second protective film is a second retardation film having a plane retardation value of 20 nm to 100 nm, a thickness retardation value of 20 nm to 140 nm, or a plane retardation value of 0 nm to 10 nm, and a thickness retardation value of 50 nm to 170 nm It may be a retardation film.

The present invention relates to a lower polarizing plate. The lower polarizing plate is a lower polarizing plate including a second polarizing element and a second protective film laminated on one surface of the second polarizing element, and the first polarizing element and the first protective film laminated on one surface of the first polarizing element are It can be used with an upper polarizing plate.

The first protective film may have a plane phase difference value of 90 nm to 200 nm, and a thickness direction phase difference value of 130 nm to 220 nm.

The second protective film is a second retardation film having a plane retardation value of 20 nm to 100 nm, a thickness retardation value of 20 nm to 140 nm, or a plane retardation value of 0 nm to 10 nm, and a thickness retardation value of 50 nm to 170 nm It may be a retardation film.

The details of the upper polarizing plate and the lower polarizing plate may be the same as described in the polarizing plate set.

The present invention relates to a liquid crystal display device. The liquid crystal display device may include the polarizing plate set and the liquid crystal panel. The liquid crystal display device includes an upper polarizing plate including a first polarizing element and a first protective film stacked on one surface of the first polarizing element; Planar switching mode liquid crystal panel; And a second polarizing element and a lower polarizing plate including a second protective film stacked on one surface of the second polarizing element.

The first protective film may have a plane phase difference value of 90 nm to 200 nm, and a thickness direction phase difference value of 130 nm to 220 nm.

The second protective film is a second retardation film having a plane retardation value of 20 nm to 100 nm, a thickness retardation value of 20 nm to 140 nm, or a plane retardation value of 0 nm to 10 nm, and a thickness retardation value of 50 nm to 170 nm It may be a retardation film.

Details of the upper polarizing plate and the lower polarizing plate including the phase difference value may be the same as described in the polarizing plate set.

The liquid crystal panel may be an in-plane switching (IPS) mode, a fringe field switching (FSF) mode, or a liquid crystal panel in a plane to line switching (PLS) mode. The liquid crystal panel may include an upper substrate, a liquid crystal layer, and a lower substrate. The upper and lower substrates may be glass substrates or plastic substrates, respectively. According to an embodiment of the present invention, the liquid crystal panel may be an IPS mode (plane switching mode) liquid crystal panel.

The liquid crystal layer may include a liquid crystal whose dielectric anisotropy is positive or negative. The dielectric anisotropy of the liquid crystal layer may be appropriately selected according to a desired mode of the liquid crystal panel. In one example, the in-plane retardation value of the liquid crystal layer is 270 nm to 330 nm, and the thickness direction retardation value may be 0 nm to -40 nm.

In one example, the first and second protective films may be disposed adjacent to the top and bottom of the liquid crystal panel. In one example, the liquid crystal display device may further include a backlight under the lower polarizing plate.

In one example, the alignment direction of the liquid crystal of the liquid crystal layer may be parallel to each other or perpendicular to the absorption axis of the second polarizing element. When the angle is parallel, it can be defined as an O-mode liquid crystal panel, and when orthogonal, it can be defined as an E-mode liquid crystal panel.

In one example, when the liquid crystal display includes an O mode liquid crystal panel, a backlight may be disposed on one surface of the lower polarizing plate. In another example, when the liquid crystal display includes an E-mode panel, a backlight may be disposed on one surface of the upper polarizing plate.

The upper and lower substrates of the liquid crystal panel may further include an alignment layer toward the liquid crystal layer. The alignment direction of the liquid crystal may be determined by the alignment layer. The alignment layer may be a horizontal alignment layer. As the alignment layer, a rubbing alignment layer or a photo alignment layer may be used.

1 and 2 exemplarily show a liquid crystal display device according to the first and second embodiments of the present invention.

According to FIG. 1, the liquid crystal display device sequentially includes an upper polarization element 1, a first retardation film 2, a liquid crystal panel 3, a second retardation film 4A, and a lower polarization element 5.

 According to FIG. 2, the liquid crystal display device sequentially includes the upper polarization element 1, the first retardation film 2, the liquid crystal panel 3, the third retardation film 4B, and the lower polarization element 5.

In FIG. 1 and FIG. 2, ↔ and ⊙ mean the in-plane optical axis of the retardation film, the absorption axis of the polarizing element, and the liquid crystal alignment direction of the liquid crystal panel. ⊙ means the direction perpendicular to the ground.

The planar switching mode liquid crystal display device of the present invention can exhibit optical characteristics and a desired viewing angle in an oblique direction. In one example, the luminance at an inclination angle of 60 degrees and an azimuth angle of the liquid crystal display device may be 1.5 or less. Specifically, the luminance may be 1.4 or less, 1.3 or less, 1.2 or less, 1.1 or less, 1.0 or less, 0.9 or less, 0.8 or less, 0.7 or less, 0.6 or less. The lower the luminance value, the better the optical characteristics in the oblique direction, and the lower limit thereof may be, for example, 0.5 or more.

According to the present invention, the light leakage characteristic can be improved by improving the luminance in the oblique direction. In one example, the yellow luminous properties may not be exhibited at a 60-degree inclination angle and a 45-degree azimuth angle of the liquid crystal display device, and particularly, a bluish luminous property may be exhibited. In one example, the liquid crystal display may have smaller values of x and y in the CIE xy color coordinates at an inclination angle of 60 degrees and an azimuth angle of 45 degrees, compared to a liquid crystal display device that does not include the first and second protective films. have. In one example, the liquid crystal display may have an x value and a y value of 0.36 or less in the CIE xy color coordinates at an inclination angle of 60 degrees and an azimuth angle of 45 degrees.

The present invention relates to a polarizing plate, a polarizing plate set, and a liquid crystal display device. The polarizing plate to the polarizing plate set of the present invention is excellent in optical properties such as light leakage characteristics in the viewing angle, it is possible to provide a planar switching mode liquid crystal display device capable of exhibiting a desired visual acuity.

1 exemplarily shows a liquid crystal display device of the present application.
2 exemplarily shows a liquid crystal display device of the present application.
3 is a simulation result of Comparative Example 1-2 and Example 1-9.
4 is a simulation result of Examples 10-15.
5 is a simulation result of Examples 16-19.
6 is a simulation result of Examples 20-26.
7 is a simulation result of Examples 27-34.

Hereinafter, the present application will be described in detail through examples, but the scope of the present application is not limited by the following examples.

Example  One

For a planar switching mode liquid crystal display having the structures of FIGS. 1 to 2 using Techwiz LCD 1D, optical characteristics and visual acuity were simulated at all inclination angles, particularly at an inclination angle of 60 degrees and an azimuth angle of 45 degrees. The simulation conditions are as follows.

(1) Liquid crystal panel: cell spacing 2.9 μm, pretilt angle 0 °, dielectric anisotropy Δε> 0, liquid crystal birefringence Δn = 0.1 at a wavelength of 550 nm. Rin (550): 290nm Rth (550): O mode IPS liquid crystal panel with 0nm

(2) Upper and lower polarization elements: PVA-based polarization elements having a polarization degree of 99.99% or more and a single transmittance of 42.5% for light having a wavelength of 380 nm to 780 nm

(3) Protective film of upper polarizing element and protective film of lower polarizing element: An acrylic film having dispersion characteristics R (450) / R (550) of 1.06 was prepared, and the phase difference value for light at a wavelength of 550 nm was adjusted as follows. Did.

Luminance is a value calculated by simulation, and visual acuity is predicted by simulation. The actual visual sensation is classified into Yellow, Bluish, Neutral, and Reddish as the color coordinate values at an inclination angle of 60 degrees and an azimuth angle of 45 degrees where light leakage is most vulnerable to the reference color coordinates.

Upper protective film Lower protective film Luminance Color coordinate Rin Rth Rin Rth x y Comparative example One 0 0 0 0 1.75 0.3601 0.3635 2 110 160 0 40 1.75 0.3109 0.3110 Example One 110 160 55 83 1.12 0.2408 0.2025 2 110 160 20 100 0.68 0.2380 0.1844 3 110 160 10 100 0.64 0.2486 0.1957 4 110 160 0 60 1.20 0.305 0.2959 5 110 160 0 80 0.84 0.2898 0.2637 6 110 160 0 100 0.60 0.2628 0.2122 7 110 160 0 120 0.52 0.2329 0.1612 8 110 160 0 140 0.51 0.2162 0.1383 9 110 160 0 160 0.68 0.2148 0.1426

Upper protective film Lower protective film Luminance Color coordinate Example Rin Rth Rin  Rth x y 10 130 150 30 45 1.10 0.3120 0.3092 11 120 150 30 45 1.26 0.3039 0.2985 12 110 130 20 30 1.45 0.3191 0.3225 13 110 130 30 45 1.20 0.3013 0.2950 14 130 150 55 83 0.78 0.2462 0.2103 15 120 150 55 83 0.92 0.2423 0.2054 16 150 173 55 83 0.60 0.2703 0.2343 17 170 196 55 83 0.56 0.3211 0.2969 18 170 170 55 83 0.51 0.2966 0.263 19 170 170 60 91 0.50 0.2751 0.2402

Upper protective film Lower protective film Luminance Color Rin Rth Rin Rth x y 20 90 130 55 83 1.40 0.2364 0.2024 21 100 140 55 83 1.24 0.2371 0.2012 22 100 170 55 83 1.40 0.2403 0.2023 23 100 140 20 30 1.85 0.3085 0.3088 24 105 155 55 83 1.20 0.2388 0.2009 25 110 130 55 83 1.06 0.2402 0.2076 26 130 150 40 60 0.90 0.2904 0.2750

Upper protective film Lower protective film Luminance Color Rin Rth Rin Rth x y 27 120 150 80 121 0.94 0.2121 0.1668 28 170 196 80 121 0.51 0.2349 0.1711 29 170 210 70 121 0.51 0.2666 0.1971 30 170 210 50 120 0.51 0.3252 0.2725 31 150 190 50 120 0.51 0.2413 0.1705 32 150 190 40 120 0.51 0.2613 0.1927 33 150 190 20 100 0.52 0.3384 0.3064 34 140 160 20 100 0.51 0.2668 0.2174

1: upper polarization element, 2: first retardation film, 3: liquid crystal panel, 4A: second retardation film, 4B: third retardation film, 5: lower polarization element

Claims (19)

An upper polarizing plate including a first polarizing element and a first protective film laminated on one surface of the first polarizing element; Planar switching mode liquid crystal panel; And a second polarizing element and a lower polarizing plate comprising a second protective film laminated on one surface of the second polarizing element, in order,
Further comprising a backlight under the lower polarizing plate,
The first protective film and the second protective film are located inside the first polarizing element and the second polarizing element, respectively,
The first protective film is a first phase difference film having a plane phase difference value of 90 nm to 200 nm, and a thickness direction phase difference value of 130 nm to 220 nm,
The second protective film is a second retardation film having an in-plane retardation value of 20 nm to 100 nm, and a thickness direction retardation value of 20 nm to 140 nm,
The planar switching mode liquid crystal display device in which the thickness direction retardation (Rth) of the retardation film is calculated by Equation 2:
[Equation 2]
Rth = dx (nz-ny)
In Equation 2, d is the thickness of the retardation film, ny and nz are the refractive indices in the y-axis and z-axis directions of the retardation film, respectively, the y-axis means a direction parallel to the in-plane true axis of the retardation film, and the z-axis is the retardation film. It means the thickness direction. An upper polarizing plate including a first polarizing element and a first protective film laminated on one surface of the first polarizing element; Planar switching mode liquid crystal panel; And a second polarizing element and a lower polarizing plate comprising a second protective film laminated on one surface of the second polarizing element, in order,
Further comprising a backlight under the lower polarizing plate,
The first protective film and the second protective film are located inside the first polarizing element and the second polarizing element, respectively,
The first protective film is a first phase difference film having a plane phase difference value of 90 nm to 200 nm, and a thickness direction phase difference value of 130 nm to 220 nm,
The second protective film is a third retardation film having an in-plane retardation value of 0 nm to 10 nm and a thickness direction retardation value of 50 nm to 170 nm,
The planar switching mode liquid crystal display device in which the thickness direction retardation (Rth) of the retardation film is calculated by Equation 2:
[Equation 2]
Rth = dx (nz-ny)
In Equation 2, d is the thickness of the retardation film, ny and nz are the refractive indices in the y-axis and z-axis directions of the retardation film, respectively, the y-axis means a direction parallel to the in-plane true axis of the retardation film, and the z-axis is the retardation film. It means the thickness direction. The liquid crystal display device of claim 1, wherein the absorption axis of the first polarization element and the absorption axis of the second polarization element are orthogonal to each other. The absorption axis of the first polarizing element and the in-plane optical axis of the first retardation film are parallel or orthogonal, and the absorption axis of the second polarizing element and the in-plane optical axis of the second retardation film are parallel or orthogonal. Planar switching mode liquid crystal display device. The planar switching mode liquid crystal display device according to claim 1 or 2, wherein the first and second protective films are each one retardation film. The planar switching mode liquid crystal display device according to claim 1 or 2, wherein the first and second protective films are acrylic films, respectively. The planar switching mode liquid crystal display device according to claim 1 or 2, wherein the first and second protective films each have a constant dispersion characteristic. The planar switching mode liquid crystal display device of claim 1, wherein the Nz coefficient of the second retardation film is -1.5 to 0.7. The planar switching mode liquid crystal display device of claim 2, wherein the Nz coefficient of the third phase difference film is greater than -16. The planar switching mode liquid crystal display device of claim 1 or 2, wherein the first protective film and the second protective film satisfy the following Equation 11 or Equation 12:
[Equation 11]
│ △ Re│> │ △ Rth│-5
[Equation 12]
│ △ Re│ ≤ │ △ Rth│ + 5
In Equation 11 to Equation 12, │ΔRe│ is the absolute value of the difference between the in-plane retardation values of the first protective film and the second protective film, and │ΔRth│ is the thickness direction retardation between the first protective film and the second protective film. The absolute value of the difference in values. delete delete delete The planar switching mode liquid crystal display device according to claim 1 or 2, wherein the planar retardation value of the planar switching mode liquid crystal panel is 270 nm to 330 nm, and the retardation value in the thickness direction is 0 nm to -40 nm. The planar switching mode liquid crystal display device according to claim 1 or 2, wherein the first and second protective films are adjacent to upper and lower portions of the planar switching mode liquid crystal panel. delete The planar switching mode liquid crystal display device according to claim 1 or 2, wherein the alignment direction of the liquid crystal of the planar switching mode liquid crystal panel is parallel to or perpendicular to the absorption axis of the second polarizing element. The planar switching mode liquid crystal display device according to claim 1 or 2, wherein a luminance at an inclination angle of 60 degrees and an azimuth angle of the plane switching mode liquid crystal display device is 1.50 or less. The CIE xy of claim 1 or 2, wherein the planar switching mode liquid crystal display does not include the first and second protective films, compared to a planar switching mode liquid crystal display that does not include the first and second protective films. A planar switching mode liquid crystal display device with smaller x and y values in color coordinates.

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