TWI495911B - Coupled polarizing plate set and blue phase liquid crystal mode liquid crystal display including the same - Google Patents

Description

Coupling polarizing plate group and blue phase liquid crystal mode liquid crystal display including the same

The present invention relates to a liquid crystal display in which a specific coupled polarizing plate group can be used in a blue phase liquid crystal mode to ensure a wide viewing angle.

Since the technical problems in the initial development stage have been almost solved, liquid crystal displays (LCDs) are currently widely used as public image displays. The LCD includes a liquid crystal display panel and a backlight combination that provides light to the liquid crystal display panel.

The liquid crystal display applies a voltage to the field generating electrode to generate an electric field in the liquid crystal layer, thereby determining the alignment of the liquid crystal molecules of the liquid crystal layer and displaying the image by controlling the polarization of the incident light.

Since the alignment state of the liquid crystal layer determines the transmittance of light, a liquid crystal layer having a fast reaction speed is required to rapidly change the alignment state.

Liquid crystal displays using so-called blue phase liquid crystals have been developed with a liquid crystal state between a nematic mode and an isotropic mode. Since there is optical anisotropy when no electric field is applied and an anisotropic property when an electric field is applied, the blue phase liquid crystal has a relatively fast reaction speed of about 3 microseconds.

A coupled polarizing plate set of an in-plane switching liquid crystal display is used to ensure a wide viewing angle of the blue phase liquid crystal display. The coupled polarizing plate group includes a co-directional protective film and two kinds of compensation films having different optical properties (at least one of the compensation films may have retardation). The co-directional protective film and the two compensation films are each located between the blue phase liquid crystal and any of the polarizers.

However, when a coupled polarizing plate group of a planar conversion liquid crystal display is used, since two kinds of compensation films are required, the thickness of the blue phase liquid crystal display cannot be reduced and manufactured at a low cost as compared with the conventional liquid crystal display using different liquid crystal modes. Also, since the thickness of the two sides of the liquid crystal is uneven, it is likely to be bent due to a change in temperature or humidity.

The invention provides a coupled polarizing plate group for a blue phase liquid crystal display, has a simple structure and is mass-produced at a low price, and can provide a wide viewing angle equal to or better than a previously coupled polarizing plate group, especially a coupled polarizing plate group of a planar conversion liquid crystal display. .

The present invention also provides a blue phase liquid crystal display comprising the coupled polarizing plate group of the present invention.

According to the aspect of the present invention, a coupled polarizing plate set is provided, comprising: a first coupling polarizing plate; and a second coupling polarizing plate, wherein the first coupling polarizing plate and the second coupling polarizing plate are sequentially processed from the liquid crystal by a compensation film, a polarizer, The protective film is composed of a first coupling polarizer compensation film having a plane retardation (R0) of 50 to 140 nm, a refractive index ratio (NZ) of 1.1 to 7.0, a slow axis perpendicular to an absorption axis of the adjacent polarizer, and a second coupling polarizer The compensation film has a plane retardation (R0) of 0 to 10 nm and a thickness retardation (Rth) of -330 to -80 nm.

According to another aspect of the present invention, a blue phase liquid crystal display comprising a coupled polarizing plate group is provided, comprising a first coupling polarizing plate and a second coupling polarizing plate as upper and lower polarizing plates of a blue phase liquid crystal mode.

According to an embodiment of the present invention, a coupled polarizing plate group of a blue phase liquid crystal display has a simple configuration and is mass-produced at a low price, and can provide a wide viewing angle equal to or better than that of the previously coupled polarizing plate group, especially a coupling of a planar conversion liquid crystal display. Polarized plate set.

In accordance with an embodiment of the present invention, a blue phase liquid crystal display provides a wide viewing angle equal to or better than previous planar conversion liquid crystal displays.

The invention relates to a coupled polarizing plate group including a first coupling polarizing plate and a second coupling polarizing plate, in which compensation films having special optical properties are respectively stacked. In detail, the first coupled polarizing plate and the second coupled polarizing plate of the coupled polarizing plate group are respectively composed of a compensation film, a polarizing plate and a protective film from the liquid crystal.

The first coupling polarizer compensation film has a plane retardation (R0) of 50 to 140 nm, a refractive index ratio (NZ) of 1.1 to 7.0, and a second coupling polarizing plate compensation film having a plane retardation (R0) of 0 to 10 nm and a thickness delay ( Rth) is -330 to -80 nm. At this time, the slow axis of the first coupling polarizer compensation film is perpendicular to the absorption axis of the adjacent polarizer.

The compensation film optical properties of the present invention are defined by the following formulas 1 to 3 with respect to all wavelengths in the visible light region.

If the wavelength of the light source is not specifically stated, the optical properties at 589 nm are described. Herein, Nx is the refractive index of the axis of the light having the maximum refractive index in the plane direction, Ny is the refractive index of the light oscillating in the Nx direction of the plane in the plane direction, and Nz is the refractive index of the light oscillating in the thickness direction, as shown in FIG. as follows.

[Formula 1]

Rth=[(Nx+Ny)/2-Nz]×d

(where Nx and Ny are the refractive indices of the light oscillating in the plane direction and Nz is the refractive index of light oscillating in the film thickness direction, and d is the film thickness).

[Formula 2]

R0=(Nx-Ny)×d

(where Nx and Ny are the refractive indices of light oscillating in the plane direction, and d is the film thickness, ).

[Formula 3]

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

(where Nx and Ny are the refractive indices of the light oscillating in the plane direction and Nz is the refractive index of light oscillating in the film thickness direction, and d is the film thickness).

Rth is the thickness retardation, showing the phase difference of the average refractive index of the plane in the thickness direction, not the substantial phase difference, but the reference value, and R0 is the plane retardation, which is the substantial phase difference when the light passes through the film in the normal direction (vertical direction).

Furthermore, NZ is a refractive index ratio by which the type of the compensation film can be distinguished. The type of the compensation film is referred to as an A plate when the optical axis having no phase difference exists in the film plane direction, the C plate is present when the optical axis exists in the plane perpendicular direction, and the biaxial plate is present when the two optical axes exist.

In detail, the refractive index pair NZ=1 satisfies Nx>Ny=Nz, which is called positive A plate, and the refractive index pair 1<NZ satisfies Nx>Ny>Nz, which is called negative biaxial A plate, and the refractive index is 0<NZ <1 has a relationship of Nx>Nz>Ny, which is called a Z-axis alignment film. The refractive index has a relationship of Nx=Nz>Ny for NZ=0, which is called a negative A plate, and the refractive index pair NZ<0 has Nz>Nx>Ny. The relationship, called the positive biaxial A plate, the refractive index pair NZ=∞ has a relationship of Nx=Ny>Nz, which is called a negative C plate, and the refractive index pair NZ=-∞ has a relationship of Nz>Nx=Ny, which is called a positive C plate. .

However, it is not possible to perfectly manufacture the A and C plates in accordance with the theoretical definition in the real world process. Therefore, in the general process, the refractive index ratio of the A plate is set to an approximate range and the C plate is set to a predetermined value within the plane retardation range to distinguish the A plate from the C plate. The setting of the predetermined value is limited to the application of all other materials having different refractive indices due to the extension. Therefore, the compensation film included in the upper and lower polarizing plates of the present invention is represented by NZ, R0, Rth, and the like of the optical properties of the plate, and not according to the refractive index isotropic.

These compensation films have a phase difference due to the extension, wherein the film whose refractive index increases in the extending direction has a positive (+) refractive index property, and the film whose refractive index decreases in the extending direction has a negative (-) refractive index property. The compensation film with positive (+) refractive index properties can be selected from TAC (TriAcetyl Cellulose, cellulose triacetate), COP (Cyclo-Olefin Polymer, cycloolefin polymer), COC (Cyclo-Olefin Copolymer). , PET (Polyethylene Terephthalate, Polyethylene Terephthalate), PP (Polypropylene, Polypropylene), PC (Polycarbonate, Polycarbonate), PSF (Polysulfone, Polyfluorene), PMMA (Poly Methylmethacrylate, Polymethacrylic Acid) Among the group consisting of methyl esters, the compensation film having a negative (-) refractive index may be made of modified-PS (Polystyrene) or modified-PC (Polycarbonate, polycarbonate).

Furthermore, the method for providing optical properties of the compensation film is divided into a fixed end extension and a free end extension, wherein the fixed end extension is a length excluding the fixed extension direction when the film is extended, and the free end extension is a direction other than the extension direction when the film is extended. Provide freedom. In general, the film shrinks in a direction other than the direction of extension, but the Z-axis alignment film requires a specific shrinking process rather than an extension.

3 shows the direction in which the green film is wound, in which the unwound direction of the wound film is referred to as MD (Machine direction), and the direction perpendicular to the MD is referred to as TD (Transverse direction). Furthermore, in the process, the film extension in the MD is referred to as a free end extension, and the extension in the TD is referred to as a fixed end extension.

Summarizing the plate type and NZ according to the extension method (only when using the first process), the positive A plate can be manufactured by a film having a positive (+) refractive index property extending from the free end, and the negative biaxial A plate extending from the fixed end has a positive ( +) a film of refractive nature, the Z-axis alignment film is extended from the free end and then the fixed end shrinks a film having positive (+) refractive properties or negative (-) refractive properties, and the negative A plate has a negative (-) refractive extension from the free end. A film of a nature, a positive biaxial A plate extending from the fixed end with a film having negative (-) refractive properties.

Other processes other than the above processes can also control the slow axis direction, phase difference, and NZ value, and other processes are generally used to encompass the field of the present invention without particular limitation.

The coupled polarizing plate group according to the present invention includes a first coupling polarizing plate and a second coupling polarizing plate, each composed of a compensation film, a polarizing plate, and a protective film.

The first coupling polarizer compensation film has a plane retardation (R0) of 50 to 140 nm and a refractive index ratio (NZ) of 1.1 to 7.0. When the plane retardation (R0) increases within the above range and the absolute value of the refractive index ratio (NZ) decreases, the dispersion state of the polarization state tends to decrease. Thus, a better wide viewing angle can be ensured.

If the refractive index ratio (NZ) is greater than 7.0, the dispersion characteristic becomes too large, and the dispersion characteristic represents a difference in the polarization state after the liquid crystal display having the optimum viewing angle effect depending on the wavelength, and the liquid crystal display is composed of the first compensation film, the liquid crystal cell, The second compensation film is constructed, and although the reference wavelength is compensated, other wavelengths are generally not compensated. Therefore, it is difficult to achieve the effects of the present invention. If the refractive index ratio (NZ) is less than 1.1, the slow axis direction of the compensation film and the MD are different from each other. Therefore, it is not easy to apply to a roll-to-roll process.

Although the desired retardation of the planar retardation (R0) may be less than 50 nm in the simulation, the minimum retardation value of the planar retardation (R0) of the first coupled polarizer compensation film should be 50 nm to be manufactured in an actual process. A compensation film of a constant or uniform retardation value (target value ± 5 nm) and a constant or uniform retardation angle (target value ± 0.5 °).

Preferably, the plane retardation (R0) is in the range of 70 to 140 nm, and the refractive index ratio (NZ) is in the range of 1.1 to 3.0. This is because the degree of dispersion is small within the above range, and thus mass production is possible. Since the plane retardation (R0) can be determined in consideration of the refractive index ratio (NZ), the first coupling polarizer compensates for the film plane retardation when the first coupling polarizer compensation film refractive index ratio (NZ) is in the range of 1.1 to 3.0 (R0) ) in the range of 70 to 140 nm. The optical properties of the second coupled polarizer compensation film should also be considered.

The planar retardation (R0) is in the range of 80 to 140 nm, and the refractive index ratio (NZ) is preferably in the range of 1.1 to 2.0 because the TD uniaxial stretching is particularly easy in the above range in the actual process. If the TD can be uniaxially extended, the production cost can be reduced. Since the plane retardation (R0) can be determined in consideration of the refractive index ratio (NZ), the first coupling polarizer compensates for the film plane retardation when the first coupling polarizer compensation film refractive index ratio (NZ) is in the range of 1.1 to 2.0 (R0) ) in the range of 80 to 140 nm. The optical properties of the second coupled polarizer compensation film should also be considered.

The slow axis of the first coupled polarizer compensation film is parallel to the absorption axis of the adjacent polarizer (the first coupled polarizer polarizer).

The second coupling polarizer compensation film has a plane retardation (R0) of 0 to 10 nm and a thickness retardation (Rth) of -330 to -80 nm. To ensure a wide viewing angle of the blue phase liquid crystal display, the optical properties of the first coupled polarizer compensation film can be considered.

When considering the preferred range of optical properties of the first coupling polarizer compensation film and industrial advantages from the preferred range, it is preferable that the second coupling polarizer compensates for a film having a plane retardation (R0) in the range of 0 to 5 nm, and the second coupled polarization The thickness compensation (Rth) of the plate compensation film is in the range of -220 to -80 nm. The second coupling polarizer compensates for a film having a plane retardation (R0) in the range of 0 to 3 nm, and the second coupling polarizing plate compensating film has a thickness retardation (Rth) preferably in the range of -160 to -80 nm.

Since the second coupling polarizer compensation film has no slow axis, the compensation film position is independent of the absorption axis direction of the adjacent polarizer (second coupling polarizer polarizer).

The compensation film of the present invention may have a normal wavelength dispersion characteristic or a reverse wavelength dispersion characteristic. In general, the compensation film phase difference will vary with the wavelength of the incident light. The phase difference is large at a short wavelength and small at a long wavelength, and a compensation film having these properties is called a compensation film having a normal wavelength dispersion characteristic. Further, a film having a small phase difference at a short wavelength and a large phase difference at a long wavelength is referred to as a compensation film having a reverse wavelength dispersion characteristic.

In the present invention, the compensation film dispersion characteristics are represented by the ratio of the phase difference of the 380 nm light source to the difference of the 780 nm light source, as is generally used in the field. [R0 (380 nm) / R0 (780 nm)] = 0.4872 in a compensation film having a complete reverse wavelength dispersion characteristic in which all wavelengths can achieve the same polarization state.

The polarizers of the first and second coupling polarizers may each have a polarizing functional layer, and are formed by stretching and dyeing PVA (Polyvinyl Alcohol, polyvinyl alcohol). The polarizers each have a protective film on the far side of the liquid crystal cell. The first and second coupled polarizers can be fabricated by methods commonly used in the art, and in particular, can be used in a shaft-to-axis process and a sheet-to-sheet process. Considering the yield and efficiency in the process, it is best to use the shaft-to-axis process. In detail, since the absorption axis direction of the PVA polarizer is always fixed in the MD, it is effective.

The protective film of the first and second coupling polarizers may be what is commonly used in this field. The protective film preferably has an optical property that does not affect the viewing angle as much as possible. The material of the protective film may be selected from TAC (TriAcetyl Cellulose, cellulose triacetate), COP (Cyclo-Olefin Polymer, cycloolefin polymer), COC (Cyclo-Olefin Copolymer), PET (Polyethylene Terephthalate). Ethylene terephthalate), PP (Polypropylene, polypropylene), PC (Polycarbonate, polycarbonate), PSF (Polysulfone, polyfluorene), PMMA (Poly Methylmethacrylate, polymethyl methacrylate).

Furthermore, the present invention relates to a liquid crystal display comprising a blue phase liquid crystal panel and a coupled polarizing plate group, the coupled polarizing plate group comprising a first coupling polarizing plate and a second coupling polarizing plate respectively serving as upper and lower polarizing plates. In the liquid crystal display, the first coupled polarizing plate can be used as an upper polarizing plate, the second coupled polarizing plate can be used as a lower polarizing plate, or the second coupled polarizing plate can be used as an upper polarizing plate, and the first coupled polarizing plate can be used as a lower polarizing plate. Polarizer. The absorption axis of the first coupling polarizer polarizer is perpendicular to the absorption axis of the second coupling polarizer polarizer.

When no electric field is applied, the blue phase liquid crystal has optical anisotropy characteristics, and when an electric field is applied, it has optical anisotropy characteristics. The liquid crystal forms a cylindrical array in which the molecules are twisted and arranged in a 3D spiral. This alignment structure is called a double twist cylinder (hereinafter, referred to as 'DTC'). The blue phase liquid is further twisted from the DTC central axis to the outside. That is, the blue phase liquid crystals are arranged in a twisted state in which the two torsion axes are perpendicular to each other in the DTC, and the directivity in the DTC depends on the DTC central axis.

The blue phase liquid crystal contains a first blue phase, a second blue phase, and a third blue phase. The alignment structure depends on the blue phase species in the DTC. In the first blue phase, the DTCs are arranged in a body-centered cubic structure, which is a lattice structure, and in the second blue phase, the DTCs are arranged in a simple cubic structure. Since the DTCs are arranged in a lattice structure in the blue phase, disclination occurs in the portion where three adjacent DTCs meet. The disclination is a portion in which the liquid crystals are irregularly arranged and have irregular directionality and form a disclination line.

The change in the isotropic refractive index of the blue phase liquid crystal is proportional to the square of the applied voltage, depending on the applied voltage strength. When an electric field is applied to a co-polar material, the optical effect of the refractive index proportional to the square of the applied voltage is called the Kerr effect. Since the liquid crystal display is developed using the Kerr effect of the blue phase liquid crystal, the reaction speed is increased.

Further, the refractive index of the blue phase liquid crystal is determined for each region where the electric field is formed. When the electric field forming region is continuously formed, the liquid crystal display has uniform brightness regardless of the uniformity of the cell gap, thereby enhancing the display characteristics of the liquid crystal display.

In the liquid crystal display under the optical conditions of the present invention, the maximum transmittance from all light directions satisfies a compensation relationship of 0.05% or less in the black mode, and preferably a compensation relationship of 0.02% or less. Using the vertical alignment (VA) mode, the highest front luminance of currently produced liquid crystal displays is approximately 10,000 nits. The viewing angle of the brightness at a tilt angle of 60° is about 10000 nits × cos 60°, and the brightness corresponding to 0.05% brightness is 2.5 nits. Therefore, the present invention makes the transmittance from all light directions equal to or larger than that of the liquid crystal display employing the VA mode.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view showing the basic structure of a liquid crystal display of a blue phase liquid crystal according to the present invention, which will be described below.

In the liquid crystal display of the blue phase liquid crystal, the second protective film 13, the second polarizer 11, the second compensation film 14, the blue phase liquid crystal cell 30, the first compensation film 24, and the first polarizer 21 are sequentially stacked from the backlight unit 40. The first protective film 23. When viewed from the viewer of the display, the absorption axes 12 and 22 of the first polarizer 21 and the second polarizer 11 are perpendicular to each other, and the slow axis of the first compensation film is parallel to the absorption axis of the first polarizer. In FIG. 1(a), the first coupling polarizer is located on the upper portion of the coupled polarizing plate group as an upper polarizing plate, and the slow axis 25 of the first compensation film 24 is perpendicular to the absorption axis 22 of the first polarizing plate 21, FIG. 1(b) The first coupling polarizer is located in the lower region of the coupled polarizing plate group as a lower polarizing plate, and the slow axis 25 of the first compensation film 24 is perpendicular to the absorption axis 22 of the first polarizing plate 21.

The first coupling polarizing plate 20 and the second coupling polarizing plate 10 can be manufactured by a shaft-to-axis method that is easy to mass-produce. Figure 3 is a schematic diagram showing the MD of the shaft-to-shaft process. Referring to Figure 3, the configuration of Figure 1 (a) is explained below.

The combination of the various optical films is made into a first coupled polarizing plate 20 and a second coupled polarizing plate 10, each of which is in a wound state before being attached to the coupled polarizing plate. The direction from the drum or the unwound or wound film thereon is referred to as the machine direction (MD). In the case of the second coupling polarizing plate 10, the directions of the second protective film 13 and the second compensation film 14 have no influence on optical properties, and can be produced shaft-to-axis, in the case of the first coupling polarizing plate 20, only when the first polarizing light When the MDs of the sheet 21 and the first compensation film 24 coincide with each other regardless of the direction of the first protective film 23, the shaft can be produced.

Further, when the absorption axis 12 of the second polarizer 11 close to the backlight unit is in the vertical direction, the light passing through the second coupling polarizing plate 10 is polarized in the horizontal direction. In this case, when the light passes through the liquid crystal cell to which the panel voltage is applied in the bright mode, the light passes through the first coupling polarizing plate 20 in the vertical direction on the display side having the horizontal absorption axis. At this time, the light emitted from the liquid crystal display can also be seen by the polarized sunglasses on the display side with the horizontal absorption axis (the absorption axis of the polarized sunglasses is in the horizontal direction). If the absorption axis 12 of the second polarizer 11 close to the backlight unit is in the horizontal direction, the image cannot be seen with the polarized sunglasses. Furthermore, in the case of a large-sized liquid crystal display, in order to see the image well on the display side, since the main viewing range of the person is wider in the horizontal direction than in the vertical direction, in addition to the special-purpose liquid crystal display for advertising a liquid crystal display or the like, a general liquid crystal is generally used. The display is made in a 4:3 or 16:9 form. Therefore, when viewed from the display viewer, the second polarizer absorption axis is in the vertical direction, and the first polarizer absorption axis is in the horizontal direction.

The viewing angle compensation effect of the present invention can be illustrated by a Bangka ball. Since the Bangka ball is a useful tool for expressing the change in the polarization state of the predetermined angle, the Bangka ball can express the polarization state change when the light irradiated at a predetermined angle of view passes through the optical element of the liquid crystal display which is developed using the polarized pole. . In the present invention, the predetermined viewing angle is in the direction of θ=60° and Φ=45° of the semicircular coordinate system of Fig. 4, and the polarization state of the light emitted in this direction is changed according to the wavelength of 550 nm which the person thinks is the brightest. In detail, the polarization state change on the ball of the state of the light that exits in front when the surface of the Φ direction is rotated θ around the Φ+90° axis to the viewer direction is presented. When the coordinates of the S3 axis are positive (+) on the Bangka ball, the right circular pole appears. When the horizontal component of a bias is Ex and the vertical component is Ey, the right circular bias implies the Ex component. The optical phase delay relative to the Ey component is greater than zero and less than half wavelength.

Hereinafter, in the above configuration, the effects of realizing the black state at all viewing angles when no voltage is applied are explained by way of examples and comparative examples. While the invention is more readily apparent from the following examples, the following examples are merely illustrative of the invention, and are not intended to limit the scope of the invention claimed.

Instance

The wide viewing angle effect was compared by simulation using TECH WIZ LCD 1D (Sanayi System Co., Korea), which are the LCD simulation systems of the first to sixth examples and the first to sixth comparative examples below.

First instance

The actual measurement data of the optical film, the liquid crystal cell, and the backlight according to the present invention is used for TECH WIZ LCD 1D (Sanayi System Co., Korea), and has the stacked structure of FIG. The structure of Figure 1 (a) is detailed below.

From the backlight unit 40, a second protective film 13, a second polarizer 11, a second compensation film 14, a blue phase liquid crystal cell 30, a first compensation film 24, a first polarizer 21, and a first protective film 23 are provided. When the side is viewed, the absorption axis 12 of the second polarizer 11 is in the vertical direction, and the absorption axis 22 of the first polarizer 21 is in the horizontal direction. Therefore, the absorption axes 12 and 22 of the first and second polarizers 21 and 11 are perpendicular to each other, and the slow axis 25 of the first compensation film 24 and the absorption axis 22 of the first polarizer 21 are perpendicular to each other.

When the electric field is not applied to the liquid crystal cell, the refractive index of the liquid crystal cell is in the same direction, and when the electric field is applied to the liquid crystal cell, the refractive index increases in the direction in which the electric field is applied. Blue phase liquid crystal (Samsung Electronics, SID 2008) is used as a sample product for the liquid crystal mode. When the liquid crystal is used, it is not necessary to initiate liquid crystal alignment, thereby simplifying the liquid crystal cell process.

The optical film and the backlight unit used in the first example each have the following optical properties.

First, the extended PVA is dyed with iodine so that the first and second polarizers 11 and 21 have a polarization function, and the polarizer has a polarization degree of 99.9% or more in the visible light region of 370 to 780 nm (luminance). Degree of polarization) and brightness group transmittance of 41% or more. When the transmittance of the transmission axis with wavelength is TD(λ), the transmittance of the absorption axis with wavelength is MD(λ), and the luminance compensation value defined by JIS Z 8701:1999 is The degree of polarization and the luminance group transmittance are defined by the following formulas 4 to 8, where S(λ) is the source spectrum and the source is the C source.

[Formula 4]

[Formula 5]

[Formula 6]

[Formula 7]

[Formula 8]

At a wavelength of 589.3 nm, a second coupling polarizer second compensation film 14 having a plane retardation (R0) of 2 nm and a thickness retardation (Rth) of -91 nm, and a plane retardation (R0) of 129 nm and a refractive index ratio (NZ) of 1.1 were used. The first coupling polarizer first compensation film 24.

The wavelength dispersion characteristics of the entire range of wavelengths of the second compensation film 14 are shown in Fig. 5. The ratio of the plane retardation (380 nm wavelength) / plane retardation (780 nm wavelength) = [R0 (380 nm) / R0 (780 nm)] was 0.862. The wavelength dispersion characteristic of the full range wavelength of the first compensation film 24 is shown in Fig. 6. The ratio of the plane retardation (380 nm wavelength) / plane retardation (780 nm wavelength) = [R0 (380 nm) / R0 (780 nm)] was 1.197.

A TAC (TriAcetyl Cellulose) film having an optical property of 50 nm thickness retardation (Rth) with respect to 589.3 nm incident light is used for the first and second protective films 23 and 13 to protect the first and second polarizers. The actual measured spectral data of the 46-inch LCD TV PAVV (LTA460HR0) model (Samsung Electronics Co., Ltd.) is used for the backlight unit.

The transmittance simulation from all light directions was performed after stacking the optical components, as shown in Fig. 1 (a), and the results of Fig. 7 were obtained. The change in the polar state of the 550 nm wavelength at the reference viewing angle (θ = 60° and Φ = 45°) is shown in Fig. 8. 1 represents the state of the pole when passing through the second polarizer 11 on the Bangka ball, and 2 represents the passage. The biasing state of the second compensation film 14 and the polarization state when passing through the liquid crystal cell, and 3 represents the polarization state when passing through the first compensation film 24.

Fig. 7 shows a transmittance distribution from all light directions when the black state is displayed on the screen, wherein the transmittance is 0% to 0.05%, the red portion exhibits a transmittance exceeding 0.05%, and the blue portion exhibits a low transmittance portion in a black state. In this case, it can be seen that the wider the blue portion is at the center, the easier it is to ensure a wider viewing angle.

Therefore, the viewing angle compensation effect is better than that of FIG. 9, which shows the transmittance from all light directions when the plane conversion liquid crystal display polarizing plate (I Plus Pol configuration, Korea Dongyou Fine Chemical Co., Ltd.) is used in the liquid crystal mode of the present invention. .

Second instance

Although the configuration is the same as the first example, the liquid crystal display of the blue phase liquid crystal uses the second compensation film 14 having a plane retardation (R0) of 2 nm and a thickness retardation (Rth) of 2328 nm at a wavelength of 589.3 nm and having a plane retardation (R0) of 51 nm. And a first compensation film 24 having a refractive index ratio (NZ) of 6.9.

Fig. 10 shows a transmittance distribution from all light directions when the black state is displayed on the screen, wherein the transmittance is 0% to 0.05%, the red portion exhibits a transmittance exceeding 0.05%, and the blue portion exhibits a low transmittance portion in a black state. In this case, it can be seen that the wider the blue portion is at the center, the easier it is to ensure a wider viewing angle.

Therefore, it is seen that the viewing angle compensation effect is equivalent to FIG. 9, which shows the transmittance from all light directions when the plane conversion liquid crystal display polarizing plate (I Plus Pol configuration, Korea Dongyou Fine Chemical Co., Ltd.) is used in the liquid crystal mode of the present invention. .

Figure 11 presents the optical compensation principle of the second example on the Bangka ball, and Figure 8 presents the optical compensation principle of the first example on the Bangka ball. In the figure, it can be seen that there are numerous compensable paths between the two paths on the Bangka ball, the first and second compensation films 14 and 24 not only enhance the optical properties, but the optical properties of the second compensation film 14 also determine the first compensation. The optimal optical properties of film 24.

Third instance

Although the configuration is the same as the first example, from the backlight unit 40, the first protective film 23, the first polarizer 21, the first compensation film 24, the blue phase liquid crystal cell 30, the second compensation film 14, and the second polarizer are disposed. 11. The second protective film 13 is as shown in Fig. 1(b). When viewed from the display side, the absorption axis 22 of the first polarizer 21 is in the vertical direction, and when viewed from the display side, the absorption axis 12 of the second polarizer 11 is in the horizontal direction. Therefore, the absorption axes 22 and 12 of the first and second polarizers 21 and 11 are perpendicular to each other, and the slow axis 25 of the first compensation film 24 and the absorption axis 22 of the first polarizer 21 are perpendicular to each other.

Based on the optical properties produced by the difference in internal refractive index in the direction of each film, a second compensation film 14 having a plane retardation (R0) of 2.0 nm and a retardation (Rth) of -91 nm and a plane retardation of 129 nm were used at a wavelength of 589.3 nm ( The first compensation film 24 of R0) and 1.1 refractive index ratio (NZ).

The wavelength dispersion characteristics of the entire range of wavelengths of the second compensation film 14 are shown in Fig. 5. The ratio of the plane retardation (380 nm wavelength) / plane retardation (780 nm wavelength) = [R0 (380 nm) / R0 (780 nm)] was 0.862. The wavelength dispersion characteristic of the full range wavelength of the first compensation film 24 is shown in Fig. 6. The ratio of the plane retardation (380 nm wavelength) / plane retardation (780 nm wavelength) = [R0 (380 nm) / R0 (780 nm)] was 1.197.

The transmittance simulation from all light directions is performed after stacking the optical components, as shown in Fig. 1(b), and the results of Fig. 12 are obtained. The change in the polar state of the 550 nm wavelength at the reference viewing angle (θ = 60° and Φ = 45°) is shown in Fig. 13. 1 represents the polarization state when passing the first polarizer 21 on the Bangka ball, and 2 represents the passage. The polarization state at the time of compensating the film 24 and the polarization state when passing through the liquid crystal cell, and 3 represents the polarization state when passing through the second compensation film 14.

Figure 12 shows a transmittance distribution from all light directions when the black state is displayed on the screen, wherein the transmittance is 0% to 0.05%, the red color exhibits a portion exceeding 100% of the transmittance, and the blue color exhibits a low transmittance portion at the black state. In this case, it can be seen that the wider the blue portion is at the center, the easier it is to ensure a wider viewing angle.

Therefore, the viewing angle compensation effect is better than that of FIG. 9, which shows the transmittance from all light directions when the plane conversion liquid crystal display polarizing plate (I Plus Pol configuration, Korea Dongyou Fine Chemical Co., Ltd.) is used in the liquid crystal mode of the present invention. .

Fourth instance

Although the components of FIG. 1(b) are stacked in the same manner as the third example, the liquid crystal display of the blue phase liquid crystal uses a second compensation film having a plane retardation (R0) of 2.0 nm and a thickness retardation (Rth) of -328 nm at a wavelength of 589.3 nm. 14 and a first compensation film 24 having a plane retardation (R0) of 51 nm and a refractive index ratio (NZ) of 6.9.

Figure 14 shows the transmittance distribution from all light directions when the black state is displayed on the screen. In this picture, you can see that a wide viewing angle is ensured. Figure 15 presents the change in the polar state of the 550 nm wavelength at the reference viewing angle (θ = 60° and Φ = 45°) of the present invention.

Fifth instance

Although the configuration is the same as the first example, the liquid crystal display of the blue phase liquid crystal uses the second compensation film 14 having a plane retardation (R0) of 2 nm and a thickness retardation (Rth) of a wavelength of 589.3 nm and having a plane retardation (R0) of 80 nm. And a first compensation film 24 having a refractive index ratio (NZ) of 2.9.

The transmittance of this configuration from all light directions is shown in FIG. Figure 17 presents the change in the polar state of the 550 nm wavelength at the reference viewing angle (θ = 60° and Φ = 45°) of the present invention.

Sixth instance

Although the configuration is the same as the first example, the liquid crystal display of the blue phase liquid crystal uses the second compensation film 14 having a plane retardation (R0) of 2.0 nm and a thickness retardation (Rth) of a wavelength of 589.3 nm and having a plane retardation of 90 nm (R0). And the first compensation film 24 of 1.9 refractive index ratio (NZ).

The transmittance of this configuration from all light directions is shown in FIG. Figure 19 presents a change in the polar state of the 550 nm wavelength at the reference viewing angle (θ = 60° and Φ = 45°) of the present invention.

First comparative example

Although the configuration is the same as the first example, the liquid crystal display of the blue phase liquid crystal uses the second compensation film 14 and the first compensation film 24 having the general TAC optical properties (2 nm plane retardation (R0) and 52 nm thickness retardation (Rth)). .

The results of the transmittance simulation of the liquid crystal display from all light directions are shown in FIG. As shown in Fig. 20, it can be seen that since the transmittance of the inclined surface is high in the black state, the viewing angle is narrow.

Second comparative example

Although the configuration is the same as the first example, the liquid crystal display of the blue phase liquid crystal uses the first and second compensation films 14 and 24 having 0-TAC for a low-cost planar conversion liquid crystal display (1 nm plane retardation (R0) and 2 nm) Thickness delay (Rth)).

The results of the transmittance simulation of the liquid crystal display from all light directions are shown in FIG. As shown in Fig. 21, it can be seen that since the transmittance of the inclined surface is high in the black state, the viewing angle is narrow.

Third comparative example

Although the configuration is the same as that of the first example, the slow axis 25 of the first compensation film 24 and the absorption axis 22 of the first polarizer 21 are made perpendicular to each other to form a blue phase liquid crystal display.

The results of the transmittance simulation of the liquid crystal display from all light directions are shown in FIG. As shown in Fig. 22, it can be seen that since the transmittance of the inclined surface is high in the black state, the viewing angle is narrow.

Fourth comparative example

Although the configuration is the same as the first example, the liquid crystal display of the blue phase liquid crystal uses the second compensation film 14 having a plane retardation (R0) of 2 nm and a thickness retardation (Rth) at a wavelength of 589.3 nm and having a plane retardation (R0) of 150 nm. And a first compensation film 24 having a refractive index ratio (NZ) of 1.8.

The results of the transmittance simulation of the liquid crystal display from all light directions are shown in FIG. As shown in Fig. 23, it can be seen that since the transmittance of the inclined surface is high in the black state, the viewing angle is narrow.

Fifth comparative example

Although the configuration is the same as the first example, the liquid crystal display of the blue phase liquid crystal uses the second compensation film 14 having a plane retardation (R0) of 2 nm and a thickness retardation (Rth) of 58 nm at a wavelength of 589.3 nm and having a plane retardation (R0) of 150 nm. And a first compensation film 24 having a refractive index ratio (NZ) of 3.0.

The results of the transmittance simulation of the liquid crystal display from all light directions are shown in FIG. As shown in Fig. 24, it can be seen that since the transmittance of the inclined surface is high in the black state, the viewing angle is narrow.

Sixth comparative example

Although the configuration is the same as the first example, the liquid crystal display of the blue phase liquid crystal uses the second compensation film 14 having a plane retardation (R0) of 2 nm and a thickness retardation (Rth) of a wavelength of 589.3 nm and having a plane retardation (R0) of 40 nm. And a first compensation film 24 having a refractive index ratio (NZ) of 7.0.

The results of the transmittance simulation of the liquid crystal display from all light directions are shown in FIG. As shown in Fig. 25, it can be seen that since the transmittance of the inclined surface is high in the black state, the viewing angle is narrow.

As described above, since the liquid crystal display of the blue phase liquid crystal according to the present invention can provide a wide viewing angle, it can be used for a large screen liquid crystal display requiring high optical level.

10‧‧‧Second coupled polarizer

11‧‧‧Second polarizer

12‧‧‧Absorption axis

13‧‧‧Second protective film

14‧‧‧Second compensation film

20‧‧‧First coupled polarizer

21‧‧‧First polarizer

22‧‧‧Absorption axis

23‧‧‧First protective film

24‧‧‧First compensation film

25‧‧‧ slow axis

30‧‧‧Blue phase liquid crystal cell

40‧‧‧Backlight unit

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

Figure 2 is a schematic view showing the refractive index of the compensation film according to the present invention;

Figure 3 is a schematic view showing the MD in the process to illustrate the unwinding direction of the compensation film and the polarizing plate according to the present invention;

Figure 4 is a schematic view showing the representation of Φ and θ in the coordinate system of the present invention;

5 is a diagram showing wavelength dispersion characteristics of a full range of wavelengths of a second compensation film used in the first example of the present invention;

6 is a diagram showing the wavelength dispersion characteristics of the full range of wavelengths of the first compensation film used in the first example;

Figure 7 presents a simulation result of transmittance from all light directions in accordance with a first example of the present invention;

Figure 8 is a diagram showing the change in the polar state of light from the direction of the inclined surface (θ = 60° and Φ = 45°) on the Poincare Sphere of the first example of the present invention;

9 is a graph showing transmittance simulation results from all light directions when a planar conversion liquid crystal display coupled polarizing plate group is used in the liquid crystal mode of the present invention;

Figure 10 presents a simulation result of transmittance from all light directions in accordance with a second example of the present invention;

Figure 11 is a view showing a change in a polar state of light emitted from a slanted surface (θ = 60° and Φ = 45°) on a state ball of the second embodiment of the present invention;

Figure 12 presents a simulation result of transmittance from all light directions in accordance with a third example of the present invention;

Figure 13 is a view showing a change in a polar state of light emitted from a slanted surface (θ = 60° and Φ = 45°) on a state ball of the third example of the present invention;

Figure 14 presents simulation results of transmittance from all light directions in accordance with a fourth example of the present invention;

Figure 15 is a view showing a change in a polar state of light emitted from a slanted surface (θ = 60° and Φ = 45°) on a state ball of the fourth example of the present invention;

Figure 16 presents a simulation result of transmittance from all light directions in accordance with a fifth example of the present invention;

Figure 17 is a view showing a change in a polar state of light emitted from a slanted surface (θ = 60° and Φ = 45°) on a state ball of the fifth example of the present invention;

Figure 18 presents a simulation result of transmittance from all light directions in accordance with a sixth example of the present invention;

Figure 19 is a view showing a change in a polar state of light emitted from a slanted surface (θ = 60° and Φ = 45°) on a state ball of the sixth example of the present invention;

Figure 20 presents simulation results of transmittance from all light directions in accordance with a first comparative example of the present invention;

Figure 21 presents a simulation result of transmittance from all light directions in accordance with a second comparative example of the present invention;

Figure 22 presents simulation results of transmittance from all light directions in accordance with a third comparative example of the present invention;

Figure 23 presents simulation results of transmittance from all light directions in accordance with a fourth comparative example of the present invention;

Figure 24 is a graph showing the results of transmittance simulation from all light directions in accordance with a fifth comparative example of the present invention;

Figure 25 is a graph showing the results of transmission simulation from all light directions in accordance with a sixth comparative example of the present invention.

10. . . Second coupled polarizer

11. . . Second polarizer

12. . . Absorption axis

13. . . Second protective film

14. . . Second compensation film

20. . . First coupled polarizer

twenty one. . . First polarizer

twenty two. . . Absorption axis

twenty three. . . First protective film

twenty four. . . First compensation film

25. . . Slow axis

30. . . Blue phase liquid crystal cell

40. . . Backlight unit

Claims (8)

A blue phase mode liquid crystal display comprising: a first coupled polarizer; a second coupled polarizer; and a blue phase liquid crystal between the first coupled polarizer and the second coupled polarizer, wherein the first The coupling polarizing plate and the second coupling polarizing plate are respectively composed of a compensation film, a polarizing plate and a protective film from the liquid crystal. The compensation film of the first coupling polarizing plate is a negative biaxial A plate and its plane retardation (R0) is 50 to At 140 nm, the refractive index ratio (NZ) is 1.1 to 7.0, the slow axis is perpendicular to the absorption axis of the first coupling polarizing plate polarizer, and the second coupling polarizing plate compensation film has a plane retardation (R0) of 0 to 10 nm, and the thickness is delayed (Rth). ) is -330 to -80 nm. A blue phase mode liquid crystal display according to claim 1, wherein the first coupling polarizer compensation film has a plane retardation (R0) of 70 to 140 nm and a refractive index ratio (NZ) of 1.1 to 3.0. A blue phase mode liquid crystal display according to claim 1, wherein the first coupling polarizer compensation film has a plane retardation (R0) of 80 to 140 nm and a refractive index ratio (NZ) of 1.1 to 2.0. A blue phase mode liquid crystal display according to claim 1, wherein the second coupling polarizer compensation film has a plane retardation (R0) of 0 to 5 nm and a thickness retardation (Rth) of -220 to -80 nm. According to the blue phase mode liquid crystal display of claim 1, wherein the second coupling polarizer compensation film has a plane retardation (R0) of 0 to 3 nm and a thickness delay (Rth) It is -160 to -80 nm. According to the blue phase mode liquid crystal display of claim 1, wherein the compensation film and the protective film of the first coupling polarizer and the second coupling polarizer are independently selected from TAC (TriAcetyl Cellulose), COP (Cyclo- Olefin Polymer, cycloolefin polymer), COC (Cyclo-Olefin Copolymer), PET (Polyethylene Terephthalate), PP (Polypropylene), PC (Polycarbonate) Among the groups consisting of carbonate), PSF (Polysulfone), and PMMA (Poly Methylmethacrylate). According to the blue phase mode liquid crystal display of claim 1, in which the blue phase liquid crystal has optical anisotropy characteristics when no electric field is applied, and optical anisotropy characteristics when an electric field is applied. According to the blue phase mode liquid crystal display of claim 1, wherein the blue phase mode liquid crystal display has a maximum transmittance from the viewing direction of 0.05% or less at an inclination angle (θ = 60°, Φ = 45°).