KR20100119969A - A laminated polarizer set and blue phase liquid crystal mode liquid crystal display comprising the same - Google Patents

Abstract

PURPOSE: A laminated polarizer set and a blue phase liquid crystal mode liquid crystal display comprising the same are provided to implement mass product through an easy manufacturing process. CONSTITUTION: A blue phase liquid crystal mode liquid crystal display comprises a first composite configuration polarizer(20) and a second composition polarizer(10). The first composite configuration polarizer and the second composite configuration polarizer are comprised of phase difference films(14,24) and protection film(13,23). The phase difference films of the first composite configuration polarizer have a front phase difference of 50-140nm and a refractive index ratio of 1.1-7.0. The phase difference film of the first composite configuration polarizer is crossed at right angles of the absorption axis of the polarizer.

Description

A set of a composite polarizer and a blue phase liquid crystal display device including the same {A LAMINATED POLARIZER SET AND BLUE PHASE LIQUID CRYSTAL MODE LIQUID CRYSTAL DISPLAY COMPRISING THE SAME}

The present invention relates to a liquid crystal display device capable of securing a wide viewing angle by applying a specific composite polarizer set to a blue phase liquid crystal mode.

Liquid crystal displays (LCDs) solve various technical difficulties in the early stage of development and are now widely used as popular image display devices. The liquid crystal display includes a liquid crystal display panel for displaying an image and a backlight assembly for providing light to the liquid crystal display panel.

The liquid crystals used in the liquid crystal display panel include nematic liquid crystals, smectic liquid crystals and cholesteric liquid crystals, and nematic liquid crystals are mainly used. Such a nematic liquid crystal adjusts the inclination angle according to the electric field formed between the pixel electrode and the common electrode, and the liquid crystal layer adjusts the light transmittance according to the inclination angle of the nematic liquid crystal. Accordingly, the luminance of the liquid crystal display panel is determined by the thickness of the liquid crystal layer, that is, the cell gap of the liquid crystal display panel and the anisotropic refractive index of the liquid crystal.

In order to overcome the anisotropic refractive index problem that causes the dependence of the cell gap and the viewing angle, a liquid crystal display panel having a blue phase liquid crystal has been proposed [US Pat. No. 4,767,149]. The blue phase liquid crystal has an characteristic that the anisotropic refractive index is isotropically changed according to the magnitude of the applied voltage, thereby improving the viewing angle and response speed of the liquid crystal display panel.

On the other hand, when the blue phase liquid crystal is implemented as a normal black, it is common to apply a pixel electrode, a common electrode, and a composite polarizing plate for a plane switching liquid crystal display device to secure a wide viewing angle (Korean Patent No. 2008-67041).

The composite polarizing plate for the planar switching liquid crystal display device is located on both sides of the liquid crystal cell, and includes an isotropic protective film between one liquid crystal cell and the polarizer and two compensations having different optical characteristics between the other liquid crystal cell and the polarizer. A layer or thickness oriented film (or three-dimensional retardation film) is located.

However, since two compensation layers with different optical properties are used in the composite polarizer, the unit price is higher than the conventional liquid crystal display device using other liquid crystal modes, the thickness is difficult, and the thickness of both sides of the liquid crystal cell is nonuniform, resulting in warpage due to temperature or humidity changes. It is likely to occur. In particular, the thickness orientation film has a problem that the price is quite high because the shrinkage process to apply the shrink film is required during manufacturing.

Accordingly, while a wide viewing angle equivalent to that of a planar switching liquid crystal display device can be realized, a blue liquid crystal display device having a simple structure and low price and easy to mass production is urgently needed.

According to the present invention, a complex polarizer set having a simple structure and easy mass production, and a composite polarizer set, are applied to the multi-component polarizer set to realize a wide viewing angle equal to or greater than that of a planar switching liquid crystal display device. The present invention proposes a blue phase liquid crystal mode liquid crystal display device capable of this and excellent price competitiveness.

The present invention includes a first composite polarizer and a second composite polarizer, wherein the first composite polarizer and the second composite polarizer are each composed of a phase difference film, a polarizer, and a protective film, and a phase difference film of the first composite polarizer. The front phase difference value R0 is 50 to 140 nm, the refractive index ratio NZ is 1.1 to 7.0, and the slow axis is disposed to be orthogonal to the absorption axis of the adjacent polarizer, and the phase difference film of the second composite polarizing plate has the front phase difference. It is characterized by a composite polarizer set having a value R0 of 0 to 10 nm and a thickness direction phase difference Rth of -330 to -80 nm.

In addition, the present invention has another feature in a liquid crystal display device including a composite polarizer set including the first composite polarizer and the second composite polarizer as an upper plate and a lower plate polarizer in a blue upper liquid crystal mode.

The present invention has a simple structure, which is advantageous in thinning and easy to manufacture, so that the mass-produced composite polarizing plate set and the liquid crystal display device using the same are comparable to the conventional liquid crystal display device, which is easier to secure a wide viewing angle. The wide viewing angle can be implemented.

The present invention relates to a composite polarizer set including a first composite polarizer and a second composite polarizer on which a retardation film having specific optical properties is laminated. Specifically, the first composite polarizing plate and the second composite polarizing plate of the composite polarizing plate set each include a retardation film, a polarizer, and a protective film.

The phase difference film of the first composite polarizing plate has a front phase difference value (R0) of 50 to 140 nm, the refractive index ratio (NZ) of 1.1 to 7.0, and the phase difference film of the second composite polarizing plate has a front phase difference value (R0) of 0. 10 nm and thickness direction phase difference (Rth) are -330-80 nm. At this time, the retardation film of the second composite polarizing plate is arranged so that the slow axis is perpendicular to the absorption axis of the adjacent polarizer.

In the present invention, the optical properties of the retardation film is defined by the following Equations 1 to 3 for the electric field in the visible light region.

In the absence of a reference to the wavelength of the light source it is generally meant to describe the optical properties when the wavelength is 589 nm. Where Nx is the refractive index of the axis having the largest refractive index in the in-plane direction, Ny is the vertical direction of Nx in the in-plane direction, and Nz is the refractive index in the thickness direction, as shown in FIG. 2.

Rth = [(Nx + Ny) / 2-Nz] × d

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

R0 = (Nx-Ny) × d

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

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

Where Nx and Ny are planar refractive indices, where Nx ≥ Ny and Nz are the thickness direction refractive indices of the film, and d is the thickness of the film.

The Rth is the thickness retardation, the difference in refractive index in the thickness direction with respect to the in-plane average refractive index is a reference value which cannot be called the actual retardation, R0 is the front phase difference, and light passes through the normal direction (vertical direction) of the film. It is the actual phase difference.

In addition, NZ is a refractive index ratio and can distinguish the kind of plate of retardation film. The type of the plate of the retardation film is an A plate when an optical axis, which is an optical path in the film, in which retardation does not occur is present in the in-plane direction of the film; A C plate when the optical axis is present in the vertical direction of the plane; And when there are two optical axes, it is called a biaxial plate.

Specifically, when NZ = 1, the refractive index satisfies the relationship Nx> Ny = Nz and is called 'Positive A Plate'; When 1 <NZ, the refractive index satisfies Nx> Ny> Nz and is called 'NEGATIVE BIAXIAL A PLATE'; When 0 <NZ <1, the refractive index has a relationship of Nx> Nz> Ny and is called “Z-axis oriented film”; When NZ = 0, the refractive index has a relationship of Nx = Nz> Ny, and is called 'NEGATIVE A PLATE'; When NZ <0, the refractive index has a relationship of Nz> Nx> Ny and is called a “POSITIVE BIAXIAL A PLATE”; When NZ = ∞, the refractive index is called 'NEGATIVE C PLATE' with the relationship Nx = Ny> Nz; In the case of NZ = -∞, the refractive index has a relationship of Nz> Nx = Ny and is called a `` positive C plate ''.

However, it is practically impossible to make A plate and C plate in perfect agreement with the above theoretical definition. In the general process, in the case of A plate, the approximate range of refractive index ratio is set, and in the case of C plate, the range of the front phase difference is set to an arbitrary value. Its arbitrary numerical setting is limited to apply to all materials having different refractive index expression characteristics due to stretching. Therefore, in the present invention, the retardation film included in the first and second composite polarizing plates has numerical values indicating NZ, RO, and Rth, which are optical properties of the plate, not the type of plate according to the form of refractive anisotropy.

Such retardation film is usually referred to as 'positive refractive index characteristics' in the stretching direction to impart retardation through stretching, and a film having a small refractive index in the stretching direction is referred to as 'negative refractive index characteristic'. It is called. Retardation films having positive refractive index characteristics are specifically triacetyl cellulose (TAC), cycloolefin polymer (COP), cycloolefin copolymer (COC), polyethylene terephthalate (PET), polypropylene (PP), poly Retardation film may be prepared from the group consisting of carbonate (PC), polysulfone (PSF) and polymethyl methacrylate (PMMA), and has a negative refractive index characteristic is specifically modified polystyrene (PS) or It can be produced by modified polycarbonate (PC).

In addition, the stretching method for imparting the optical characteristics of the retardation film is divided into fixed-end stretching and free-end stretching, fixed-end stretching is a method of fixing the length other than the stretching direction while stretching the film, free-end stretching the film During this process, the degree of freedom is given to a direction other than the stretching direction. In general, when the film is drawn, directions other than the drawing direction shrink, but the Z-axis oriented film requires a separate shrinking process in addition to drawing.

3 shows the direction of the film fabric in the roll state, and the direction in which the film is unrolled in the roll state is called a machine direction (MD) direction as a machine direction, and a direction perpendicular thereto is a TD (Transverse Direction) direction. It is called. At this time, stretching the film in the MD direction in the process is called free end stretching, and TD stretching is called fixed end stretching.

When the types of NZ and plates according to the stretching method (when only the primary process is applied) are summarized, the positive A plate stretches the free end of the film having positive refractive index characteristics; Negative biaxial A plate is fixed-end stretched film having positive refractive index characteristics; The Z-axis oriented film is fixed-end shrinkage after free-end stretching the film having a positive (+) refractive index property or a negative (-) refractive index property; The negative A plate free-ends the film with negative refractive index characteristics; Positive biaxial A plates can be prepared by fixed end stretching a film having negative refractive index characteristics.

In addition to the stretching method, an additional process may be applied to control a direction of a slow axis, a phase difference value, and a value of NZ, and the additional process thereof is not particularly limited to a process generally applied in the art.

The composite polarizing plate set according to the present invention is composed of a first composite polarizing plate and a second composite polarizing plate each consisting of a retardation film, a polarizer and a protective film.

The phase difference film of the first composite constituent polarizing plate has a front phase difference value (R0) of 50 to 140 nm and a refractive index ratio (NZ) of 1.1 to 7.0, so that a better wide viewing angle is obtained by the front phase difference value (R0). The larger the refractive index ratio is, the easier the absolute value is. When the refractive index ratio NZ exceeds 7.0, the dispersibility of the polarization state according to the wavelength after passing through the liquid crystal display device having an optimal viewing angle effect composed of the first phase difference film, the liquid crystal cell, and the second phase difference film is too high. It is difficult to achieve the effect of the present invention because the compensation for the reference wavelength is large, even if the compensation for the reference wavelength is made, and if the refractive index ratio (NZ) is less than 1.1, the slow axis and the MD direction of the retardation film are different from the roll to roll ( There is a problem that it is not easy to apply to the Roll To Roll process.

The minimum retardation value for producing a retardation film having a uniform retardation value (within ± 5 nm of the target value) and a retardation angle (± 0.5 °) generally applied to current liquid crystal displays should be maintained at 40 nm or more. In the actual process, it is better to keep the minimum value of phase difference 50 nm or more.

Preferably, the front phase difference value R0 is 70 to 140 nm, and the refractive index ratio NZ is 1.1 to 3.0. It is preferable that the dispersion characteristics are small, so that the practical mass production is possible. Since the front phase difference value R0 is a value that can be compensated by the second phase difference layer according to the refractive index ratio NZ, the range of the front phase difference R0 according to NZ 1.1 to 3.0 is 70 nm to 140 nm. More preferably, the frontal phase difference value R0 is 80 to 140 nm, and the refractive index ratio NZ is 1.1 to 2.0, and the refractive index ratio is in a range in which the TD uniaxial stretching step in the actual process is easy. Since the front phase difference value R0 is a value that can be compensated by the second phase difference layer according to the refractive index ratio NZ, the range of the front phase difference R0 according to NZ 1.1 to 2.0 is 80 nm to 140 nm. At this time, TD uniaxial stretching is easier to reduce the production cost because the process is simpler than biaxial stretching.

The retardation film of the first composite polarizing plate is disposed such that the slow axis is orthogonal to the absorption axis of the adjacent polarizer.

The phase difference film of the second composite polarizing plate has a front phase difference value (R0) of 0 to 10 nm and a thickness direction phase difference (Rth) of -330 to -80 nm. Considering the characteristics, use a combination that is easy to secure a wide viewing angle.

The preferred range of the second phase difference layer according to the preferred range of the first phase difference layer is a front phase difference value R0 of 0 to 5 nm, a thickness direction phase difference Rth of -220 to -80 nm, and the first phase difference layer. The more preferable range of the second retardation layer according to the more preferable range is that the front phase difference value R0 is 0 to 3 nm, and the thickness direction phase difference Rth is preferably maintained at -160 to -80 nm.

In general, the retardation film has a retardation value different according to the incident wavelength. Usually, a retardation film having a large retardation value at a short wavelength and a small retardation value at a long wavelength is called a retardation film having a constant wavelength dispersion. In addition, a film having a small retardation value at a short wavelength and a large retardation value at a long wavelength is called a retardation film having reverse wavelength dispersion. The present invention can be used without any limitation on the dispersibility of such a retardation film.

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

In the polarizers of the first and second composite polarizing plates according to the present invention, a polyvinyl alcohol (PVA) layer, which is a polarizer imparted with a polarization function by stretching and dyeing, is positioned, and the polyvinyl alcohol of the first composite polarizing plate ( In the polyvinyl alcohol (PVA) layer of the PVA layer and the second composite polarizing plate, protective films are positioned on opposite sides of the liquid crystal cell. The first and second composite polarizers may be manufactured using a process generally used in the art, and specifically, a composite roll to roll process and sheet to sheet process may be applied. Can be. Preferably, it is preferable to apply a roll to roll process in consideration of yield and efficiency in the manufacturing process, and in particular, the application thereof is effective because the absorption axis of the PVA polarizer is always fixed in the MD direction.

In this case, since the optical properties of the protective films of the first and second composite polarizing plates do not affect the viewing angle, the refractive index characteristics are not particularly limited. Materials for forming the protective film of the first and second composite polarizing plate may be applied to those commonly used in the art independently of each other, specifically triacetyl cellulose (TAC), cycloolefin polymer (COP), cyclo Olefin copolymer (COC), polyethylene terephthalate (PET), polypropylene (PP), polycarbonate (PC), polysulfone (PSF) and polymethyl methacrylate (PMMA) can be used selected from the group consisting of have.

The present invention also includes a composite polarizing plate set including a blue upper liquid crystal, a first composite polarizing plate and a second composite polarizing plate on which a retardation film having specific optical properties is disposed, respectively, as an upper plate and a lower plate polarizing plate of the liquid crystal. It relates to a liquid crystal display device. In the liquid crystal display, the first composite polarizer may be disposed as the upper polarizer and the second composite polarizer may be disposed as the lower polarizer, or the second polarizer may be disposed as the lower polarizer. The absorption axis of the first composite polarizing plate is configured to be orthogonal to the absorption axis of the second composite polarizing plate.

The blue phase liquid crystal of the present invention changes the refractive index from anisotropic to isotropic depending on whether an electric field is applied. The liquid crystal forms an array of cylinders in which molecules are twisted in a three-dimensional spiral to form an array. The alignment structure is called a double twist cylinder (hereinafter referred to as a DTC) structure. The blue phase liquid crystals are gradually twisted toward the outside from the central axis of the DTC. That is, the blue phase liquid crystals are arranged to be twisted along two twisting axes that are orthogonal to each other in the DTC, and thus have directivity in the DTC with respect to the central axis of the DTC.

Such a blue phase liquid crystal has a first blue phase, a second blue phase, and a third blue phase, and its arrangement structure varies depending on the type of the blue phase in the DTC. The first blue phase is arranged in a body-centered cubic structure in which the DTCs are one of the lattice structures, and the second blue phase is arranged in a simple cubic structure. In the blue phase, since the DTCs are arranged in a lattice structure, DISCLINATION occurs at a portion where three adjacent DTCs meet. The predecessor is a portion in which the liquid crystals are irregularly arranged so that they do not have a regular direction, thereby forming a predefect line.

In the blue phase liquid crystal, the anisotropic refractive index changes in proportion to the square of the applied voltage according to the magnitude of the applied voltage. When the electric field is applied to an isotropic polar material, the optical effect whose refractive index is proportional to the square of the applied voltage is called the effect (KERR EFFECT), and the liquid crystal display displays an image using the Kerr effect of the blue phase liquid crystal. Is improved.

In addition, the blue phase liquid crystal has a refractive index determined for each region where an electric field is formed. When the region in which the electric field is formed is uniformly formed, the display device may improve display characteristics of the liquid crystal display since the display device may have uniform luminance regardless of cell gap uniformity.

The liquid crystal display device configured under the optical conditions of the present invention satisfies the compensating relationship of the luminous transmittance omnidirectional maximum transmittance of 0.05% or less, preferably 0.02% or less in a black state. The brightness of the brightest LCD currently produced is about 10000 nits using the vertical alignment mode (VA mode). The brightness is about 10000 nits × cos60 ° at a viewing angle of 60 °, and 0.05% of this is 2.5 nits. to be. Accordingly, the present invention is intended to implement the visibility of the omnidirectional transmittance equal to or greater than that of the liquid crystal display device to which the vertical alignment mode is applied.

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

In the liquid crystal display device for a blue phase liquid crystal according to the present invention, a second protective film 13, a second polarizer 11, a second phase difference film 14, and a blue phase liquid crystal cell are provided from the backlight unit 40 side. 30, the first phase difference film 24, the first polarizer 21, and the first protective film 23 are laminated in this order. As viewed from the viewer side, the absorption axes 12 and 22 of the first polarizer 21 and the second polarizer 11 are orthogonal to each other, and the slow axis of the first retardation film and the absorption axis of the first polarizer are orthogonal to each other. To be placed. Specifically, FIG. 1A illustrates that the first composite polarizing plate is disposed on the upper polarizing plate, and the slow axis 25 of the first retardation film 24 and the absorption axis 22 of the first polarizer 21 are perpendicular to each other. 1 (b) shows that the first composite polarizing plate is disposed on the lower plate polarizing plate, and the slow axis 25 of the first retardation film 24 and the absorption axis 22 of the first polarizer 21 are It is configured to be orthogonal to each other.

The first composite polarizing plate 20 and the second composite polarizing plate 10 of the present invention are manufactured by applying a roll to roll method that is easy to mass produce. Figure 3 is a schematic diagram illustrating the MD direction in the roll-to-roll manufacturing process with reference to this as described in the configuration of Figure 1 (a) as follows.

The first composite polarizer 20 and the second composite polarizer 10 are made of a combination of various optical films, and each optical film exists in a roll state before being bonded to the composite polarizer. The direction in which the film is unwound or wound in the roll is called MD (Machine Direction) direction. In the case of the second composite polarizing plate 10, the direction of the second protective film 13 and the second retardation film 14 have no influence on optical performance, so that roll to roll production is possible, and the first composite In the case of the constituent polarizing plate 20, it is irrelevant to the direction of the first protective film 23, and roll to roll is produced only by matching the MD directions of the first polarizer 21 and the first retardation film 24. This is possible.

In addition, when the absorption axis 12 of the second polarizer 11 near the backlight unit is in the vertical direction, light passing through the second composite polarizing plate 10 is polarized in the horizontal direction, which is a liquid crystal to which a voltage of the panel is applied. When the light passes through the cell and becomes bright, the light passes in the vertical direction and passes through the first composite polarizing plate 20 on the side of the viewer whose absorption axis is in the horizontal direction. At this time, the person wearing the polarized sunglasses having the absorption axis in the horizontal direction (the absorption axis of the polarized sunglasses is in the horizontal direction) on the viewer side can recognize the light emitted from the liquid crystal display. If the absorption axis 12 of the second polarizer 11 near the backlight unit is in the horizontal direction, a problem occurs in that an image is not visible to a person wearing polarized sunglasses. In addition, in the case of a large liquid crystal display device, in order to make the image visible from the viewer side, in consideration of the fact that the human field of view is wider in the horizontal direction than the vertical direction, the general liquid crystal display device except for special purpose liquid crystal display devices such as advertisements is used. Since the field of view is wider in the horizontal direction than in the vertical direction, it is manufactured in the form of 4: 3 or 16: 9. Therefore, as viewed from the viewer side, the absorption axis of the lower polarizer is vertical and the absorption axis of the upper polarizer is parallel.

The effect of the viewing angle compensation of the present invention can be explained through Poincare Sphere. Poincare Sphere is a very useful way of expressing the change of polarization state at a certain time, so the light traveling at a certain time in the liquid crystal display that displays the image using polarization passes through each optical element in the liquid crystal display. It can show the change of polarization state. In the present invention, the specific time point is described based on a wavelength 550 nm in which the polarization state change of light emitted in this direction is θ = 60 ° and Φ = 45 ° in the semicircular coordinate system shown in FIG. 4. Specifically, when the surface of the Φ direction is rotated by θ to the viewer side with the axis in the Φ + 90 ° direction from the front side, the polarization state change with respect to the light coming out in the front direction is shown on the Pooh Karé sphere. When the coordinates of the S3 axis are positive (+) on the Poang Karegu, the right-handed polarized light represents the right-handed polarization.In this case, the right-handed polarization indicates that the arbitrary polarization horizontal component is Ex and the polarization vertical component is Ey. Compared to light, the slowness of phase is greater than zero and less than half wavelength.

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

Example

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

Example 1

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

From the backlight unit 40 side, the second protective film 13, the second polarizer 11, the second phase difference film 14, the blue phase liquid crystal cell 30, the first phase difference film 24, It consists of a first polarizer 21, the first protective film 23, the absorption axis 12 of the second polarizer 11 is a vertical direction when viewed from the viewing side and the absorption axis 22 of the first polarizer 21 The absorption axes 12, 22 of the first and second polarizers 21, 11 are configured to be orthogonal to each other in the horizontal direction when viewed from the viewer side, and the slow axis 25 and the first axis of the first phase difference film 24 The absorption axis 22 of the one polarizer 21 was comprised so that it may mutually orthogonally cross.

The liquid crystal cell exhibits isotropic refractive index when no electric field is applied, and the refractive index increases when the electric field is applied. The prototype of the liquid crystal mode uses a blue phase liquid crystal (Samsung Electronics, SID 2008). It was. In this case, the liquid crystal cell manufacturing process is simplified since no initial liquid crystal alignment is required.

On the other hand, each of the optical film and the backlight used in Example 1 of the present invention was used to have the optical properties as follows.

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

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

The optical characteristics caused by the difference in the internal refractive index according to the direction of each film is the second phase difference film 14 of the lower plate at a wavelength of 589.3 nm, the front phase difference value R0 is 2 nm and the thickness direction phase difference value Rth is -91 nm. The first phase difference film 24 of the upper plate was used having a front phase difference value R0 of 129 nm and a refractive index ratio (NZ) of 1.1.

The wavelength dispersion of the first retardation film 24 is 0.862 in front phase difference (wavelength, 380 nm) / front phase difference (wavelength, 780 nm) = [RO (380 nm) / RO (780 nm)], as shown in FIG. The wavelength dispersion of the second phase difference film 14 indicates the front phase difference (wavelength, 380 nm) / front phase difference (wavelength, 780 nm) = [RO (380 nm) / RO (780 nm). ] Is 1.197 and shows the degree of full-wave wavelength dispersion as shown in FIG.

Triacetyl cellulose (TAC) having an optical characteristic having a thickness direction phase difference value (Rth) of 50 nm with respect to the incident light of 589.3 nm to the outer first and second protective films 23 and 13, respectively, of the first and second polarizers. Used. As the backlight unit, backlight measurement spectrum data mounted on 46-inch LCD TV PAVV (LTA460HR0) of Samsung Electronics was used.

The optical components were laminated as shown in FIG. 1 (a) and subjected to simulation of visibility omnidirectional transmittance. As a result, the results as shown in FIG. 7 were obtained. The change in polarization state with a wavelength of 550 nm at the reference time (θ = 60 °, Φ = 45 °) of the present invention is shown in FIG. 8 and polarized when passing through the second polarizer 11 on the Poincare Sphere. When the state passes through the first and second retardation films 14, the polarization state passes through the polarization state and the liquid crystal cell passes through the polarization state, and when the state passes through the first phase difference film 24, the polarization state is represented by three.

FIG. 7 illustrates the distribution of visibility of permeability in the case of displaying the black on the screen, and the range on the scale ranges from 0% to 0.05% of the transmittance, and the portion exceeding 0.05% of the transmittance when displaying the cancer is red, Low permeability areas are indicated in blue. At this time, it was confirmed that the wider the range of blue in the center, the wider the viewing angle.

It was confirmed that the viewing angle compensation effect was superior to that of FIG. 9 showing the visibility and omnidirectional transmittance when the polarizing plate (I Plus Pol configuration, Dongwoo Finechem, Korea) for an area switching liquid crystal display device was applied to the liquid crystal mode of the present invention.

Example 2

In the same manner as in Example 1, the second phase difference film 14 at 589.3nm was used that the front phase difference value (R0) is 2nm and the thickness direction phase difference value (Rth) is -328nm, the first phase difference The film 24 was arranged such that the front phase difference value R0 was 51 nm and the refractive index ratio NZ was 6.9 to manufacture a blue phase liquid crystal display device.

FIG. 10 illustrates the distribution of visibility of permeability in the case of displaying the black on the screen. The scale ranges from 0% to 0.05% of the transmittance, and the area exceeding 0.05% of the transmittance when displaying the cancer is red, Low permeability areas are indicated in blue. At this time, it was confirmed that the wider the range of blue in the center, the wider the viewing angle.

In addition, it was confirmed that the viewing angle compensation effect equivalent to that shown in Fig. 9 showing the visibility and omnidirectional transmittance when the polarizing plate (I Plus Pol configuration, Dongwoo Finechem, Korea) for the area switching liquid crystal display device was applied to the liquid crystal mode of the present invention.

FIG. 11 illustrates the optical compensation principle of Example 2 on the Pou Caer sphere, and FIG. 8 of the first example illustrates the optical compensation principle of Example 1 on the Puan Caer sphere, and a compensable path between the two paths of the Puan Caer sphere. It can be seen that there are many times, and the optical characteristics of the second retardation film 14 are not improved by the first and second retardation films 14 and 24 alone. It can be seen that the optical characteristic of (24) is determined.

Example 3

In the same manner as in Example 1, the first protective film 23, the first polarizer 21, the first retardation film 24, the blue image (from the backlight unit 40 side as shown in Fig. 1 (b)) blue phase) It consists of a liquid crystal cell 30, a second phase difference film 14, a second polarizer 11, a second protective film 13, the absorption axis 22 of the first polarizer 21 is on the viewing side When viewed from the viewing side, the absorption axis 12 of the second polarizer 11 is perpendicular to each other and the absorption axes 22 and 12 of the first and second polarizers 21 and 11 are orthogonal to each other in the horizontal direction. The slow axis 25 of the first retardation film 24 and the absorption axis 22 of the first polarizer 21 were configured to be orthogonal to each other.

The optical characteristics caused by the difference in internal refractive index according to the direction of each film is that the second phase difference film 24 has a front phase difference value R0 of 2.0 nm and a thickness direction phase difference value of Rth of -91 nm at a wavelength of 589.3 nm. As the first phase difference film 14, a front phase difference value R0 of 129 nm and a refractive index ratio NZ of 1.1 were used.

The wavelength dispersion of the first retardation film 24 has a front phase difference (wavelength 380 nm) / front phase difference (wavelength 780 nm) (RO (380 nm) / RO (780 nm)) of 0.862 and a wavelength field wavelength as shown in FIG. 5. The wavelength dispersion of the second retardation film 14 is a front phase difference (wavelength 380 nm) / front phase difference (wavelength 780 nm) (RO (380 nm) / RO (780 nm)) is 1.197, and FIG. Indicates the degree of dispersion of the full-wavelength wavelength as shown in FIG.

The optical components were stacked as shown in FIG. 1 (b) and subjected to simulation of visibility omnidirectional transmittance. As a result, the results as shown in FIG. 12 were obtained. The change in polarization state with a wavelength of 550 nm at the reference time (θ = 60 °, Φ = 45 °) of the present invention is shown in FIG. 13 and polarized when passing through the first polarizer 21 on the Poincare Sphere. The state is 1, the polarization state when passing through the first retardation film 24, and the polarization state when passing through the liquid crystal cell 2, the polarization state is expressed as 3 when passing through the second phase difference film 14.

FIG. 12 illustrates the distribution of visibility of permeability in the case of displaying the black on the screen. The scale ranges from 0% to 0.05% of the transmittance, and the area exceeding 0.05% of the transmittance when displaying the cancer is red, Low permeability areas are indicated in blue. At this time, it was confirmed that the wider the range of blue in the center, the wider the viewing angle.

It was confirmed that the viewing angle compensation effect was superior to that of FIG. 9 showing the visibility and omnidirectional transmittance when the polarizing plate (I Plus Pol configuration, Dongwoo Finechem, Korea) for an area switching liquid crystal display device was applied to the liquid crystal mode of the present invention.

Example 4

In the same manner as in Example 3, lamination was carried out in the configuration shown in FIG. 1 (b), but at 589.3 nm, the second phase difference film 14 had a front phase difference value R0 of 2.0 nm and a thickness direction phase difference value Rth of -328. Nm was used, and the first phase difference film 24 was disposed such that the front phase difference value R0 was 51 nm and the refractive index ratio NZ was 6.9 to manufacture a blue phase liquid crystal display device.

FIG. 14 illustrates the distribution of visibility and permeability in the case of displaying the arm on the screen, and it was confirmed that a wide viewing angle can be secured. FIG. 15 shows a change in polarization state with a wavelength of 550 nm at a reference time (θ = 60 °, Φ = 45 °) of the present invention.

Example 5

In the same manner as in Example 1, the second phase difference film 14 at 589.3nm was used that the front phase difference value (R0) is 2nm and the thickness direction phase difference value (Rth) is -210nm, the first phase difference The film 24 was arranged such that the front phase difference value R0 was 80 nm and the refractive index ratio NZ was 2.9 to manufacture a blue phase liquid crystal display device.

FIG. 16 illustrates the distribution of visibility and permeability in the case of displaying the arm on the screen, and it was confirmed that wide viewing angles can be secured. FIG. 17 shows a change in polarization state with a wavelength of 550 nm at a reference time (θ = 60 °, Φ = 45 °) of the present invention.

Example 6

In the same manner as in Example 1, the second phase difference film 14 at 589.3nm, the front phase difference value (R0) is 2.0nm and the thickness direction phase difference value (Rth) is -150nm, the first phase difference The film 24 was arranged such that the front phase difference value R0 was 90 nm and the refractive index ratio NZ was 1.9 to manufacture a blue phase liquid crystal display device.

FIG. 18 illustrates the distribution of visibility of permeability in the case of displaying the arm on the screen, and it was confirmed that a wide viewing angle can be secured. FIG. 19 shows a change in polarization state with a wavelength of 550 nm at the reference time (θ = 60 °, Φ = 45 °) of the present invention.

Comparative Example 1

In the same manner as in Example 1, the optical characteristics of the second phase difference film 14 and the first phase difference film 24 is a general TAC (front phase difference value (R0) = 2 nm, thickness direction phase difference value (Rth) = 52 nm) to prepare a liquid crystal display device for a blue phase liquid crystal.

The simulation results of the visibility of the liquid crystal display were shown in FIG. 20, and as shown in FIG. 20, it was confirmed that the viewing angle was narrow due to high transmittance of the inclined plane in the black state.

Comparative Example 2

In the same manner as in Example 1, the first and second phase difference films 14 and 24 (the front phase difference value R0 = 1 nm and the thickness direction phase difference value) are used for 0-TAC, which is frequently used in low-cost, planar switching liquid crystal displays. (Rth) = 2 nm) was disposed to prepare a liquid crystal display device for a blue phase liquid crystal.

The results of the simulation of the visibility of the liquid crystal display in the omnidirectional transmittance are shown in FIG. 21, and as shown in FIG. 21, it was confirmed that the inclined plane permeability had a narrow viewing angle in the black state.

Comparative Example 3

In the same manner as in Example 1, the slow axis 25 of the first retardation film 24 and the absorption axis 22 of the first polarizer 21 were arranged to be perpendicular to each other to manufacture a blue phase liquid crystal display device. .

The results of the simulation of the visibility of the liquid crystal display in the omnidirectional transmittance are shown in FIG. 22, and as shown in FIG. 22, it was confirmed that the inclined plane permeability had a narrow viewing angle in the black state.

Comparative Example 4

In the same manner as in Example 1, the second phase difference film 14 at 589.3nm was used that the front phase difference value (R0) is 2nm and the thickness direction phase difference value (Rth) is -90nm, the first phase difference The film 24 was arranged such that the front phase difference value R0 was 150 nm and the refractive index ratio NZ was 1.8 to manufacture a blue phase liquid crystal display device.

The results of the simulation of the visibility of the liquid crystal display in the omnidirectional transmittance are shown in FIG. 23, and as shown in FIG. 23, it was confirmed that the inclined plane permeability had a narrow viewing angle in the black state.

Comparative Example 5

In the same manner as in Example 1, the second phase difference film 14 at 589.3nm was used that the front phase difference value (R0) is 2nm and the thickness direction phase difference value (Rth) is -50nm, the first phase difference The film 24 was arranged such that the front phase difference value R0 was 150 nm and the refractive index ratio NZ was 3.0 to manufacture a blue phase liquid crystal display device.

The results of the simulation of the visibility of the liquid crystal display in the omnidirectional transmittance are shown in FIG. 24, and as shown in FIG. 24, it was confirmed that the inclined plane permeability had a narrow viewing angle in the black state.

Comparative Example 6

In the same manner as in Example 1, the second phase difference film 14 at 589.3nm was used that the front phase difference value (R0) is 2nm and the thickness direction phase difference value (Rth) is -350nm, the first phase difference The film 24 was arranged such that the front phase difference value R0 was 40 nm and the refractive index ratio NZ was 7.0 to manufacture a blue phase liquid crystal display device.

The results of the simulation of the visibility of the liquid crystal display in the omnidirectional transmittance are shown in FIG. 25. As shown in FIG. 25, it was confirmed that the inclined plane permeability had a narrow viewing angle in the black state.

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

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

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

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

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

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

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

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

FIG. 8 illustrates a change in polarization state of light emitted in an inclined plane (θ = 60 ° and Φ = 45 °) in Example 1 of the present invention on a Poincare Sphere.

9 is a result of simulating the visibility and omnidirectional transmittance when the composite polarizing plate set for a planar switching liquid crystal display device is applied to the liquid crystal mode of the present invention.

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

FIG. 11 illustrates a change in polarization state of light emitted in an inclined plane (θ = 60 ° and Φ = 45 °) in Example 2 of the present invention on a Poincare Sphere.

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

FIG. 13 illustrates a change in polarization state of light emitted in an inclined plane (θ = 60 ° and Φ = 45 °) in Example 3 of the present invention on a Poincare Sphere.

14 is a simulation result of the visibility of the visibility of Example 4 according to the present invention,

FIG. 15 illustrates a change in polarization state of light emitted in an inclined plane (θ = 60 °, Φ = 45 °) in Example 4 of the present invention on a Poincare Sphere.

16 is a simulation result of the visibility of omnidirectional transmittance of Example 5 according to the present invention;

FIG. 17 illustrates a change in polarization state of light emitted in an inclined plane (θ = 60 ° and Φ = 45 °) in Example 5 on a Poincare Sphere.

18 is a simulation result of the visibility of the omnidirectional transmittance of Example 6 according to the present invention,

FIG. 19 illustrates a change in polarization state of light emitted in an inclined plane (θ = 60 °, Φ = 45 °) in Example 6 on a Poincare Sphere.

20 is a simulation result of the visibility of the omnidirectional transmittance of Comparative Example 1 of the present invention,

21 is a simulation result of the visibility of the omnidirectional transmittance of Comparative Example 2 of the present invention,

22 is a result of simulating the visibility of omnidirectional transmittance of Comparative Example 3 of the present invention,

23 is a result of simulating the visibility of omnidirectional transmittance of Comparative Example 4 of the present invention,

24 is a result of simulating the visibility of omnidirectional transmittance of Comparative Example 5 of the present invention,

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

Claims (9)

A first composite polarizing plate and a second composite polarizing plate, The first composite polarizing plate and the second composite polarizing plate are each composed of a retardation film, a polarizer, and a protective film, The phase difference film of the first composite polarizing plate has a front phase difference value (R0) of 50 to 140 nm, a refractive index ratio (NZ) of 1.1 to 7.0, and a slow axis is disposed orthogonal to an absorption axis of adjacent polarizers, The phase difference film of the second composite polarizing plate has a composite phase polarizing plate having a front phase difference value (R0) of 0 to 10 nm and a thickness direction phase difference (Rth) of -330 to -80 nm. The composite polarizing plate set according to claim 1, wherein the retardation film of the first composite polarizing plate has a front phase difference value (R0) of 70 to 140 nm and a refractive index ratio (NZ) of 1.1 to 3.0. The composite polarizing plate set according to claim 1, wherein the retardation film of the first composite polarizing plate has a front phase difference value (R0) of 80 to 140 nm and a refractive index ratio (NZ) of 1.1 to 2.0. The composite polarizing plate set according to claim 1, wherein the retardation film of the second composite polarizing plate has a front phase difference value (R0) of 0 to 5 nm and a thickness direction phase difference (Rth) of -220 to -80 nm. The composite polarizing plate set according to claim 1, wherein the retardation film of the second composite polarizing plate has a front phase difference value (R0) of 0 to 3 nm and a thickness direction phase difference (Rth) of -160 to -80 nm. The method of claim 1, wherein the retardation film and the protective film of the first composite polarizing plate and the second composite polarizing plate are independently of each other triacetyl cellulose (TAC), cycloolefin polymer (COP), cycloolefin copolymer (COC), polyethylene A composite polarizing plate set made of one selected from the group consisting of terephthalate (PET), polypropylene (PP), polycarbonate (PC), polysulfone (PSF), and polymethyl methacrylate (PMMA). A liquid crystal display device comprising a composite polarizing plate set including a first composite polarizing plate and a second composite polarizing plate of claim 1 as an upper plate and a lower plate polarizing plate in a blue phase liquid crystal mode. The liquid crystal display of claim 7, wherein the blue phase liquid crystal mode forms a cylindrical array in which blue phase liquid crystal molecules are aligned in a three-dimensional spiral. The liquid crystal display device according to claim 7, wherein the visibility transmittance satisfies a compensation relationship of 0.05% or less at an inclination angle (θ = 60 °, Φ = 45 °).

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