KR20230158244A - Dual cell liquid crystal display apparatus - Google Patents

Abstract

A polarizer for the first cell including a first cell, a second cell disposed below the first cell, and a laminate of a positive C plate and a positive A plate laminated on one surface of the first cell; and a polarizer for a second cell that is laminated on one side of the second cell and includes a laminate of a positive C plate and a positive A plate, wherein the polarizer for the first cell and the polarizer for the second cell are formed between the first cell and the first cell. placed between 2 cells; Alternatively, a dual cell liquid crystal display device is provided, wherein the polarizer for the first cell is disposed on the upper surface of the first cell and the polarizer for the second cell is disposed on the lower surface of the second cell.

Description

Dual cell liquid crystal display device {DUAL CELL LIQUID CRYSTAL DISPLAY APPARATUS}

The present invention relates to a dual cell liquid crystal display device.

A liquid crystal display device typically includes one liquid crystal cell and is driven by displaying a screen by transmitting light from a backlight unit. However, liquid crystal displays have problems such as chronic low contrast ratio, low color volume, and low response speed. In particular, a liquid crystal display device equipped with an IPS (in plane switch) liquid crystal cell in which the liquid crystal is tilted in a certain direction had a particularly low viewing angle and side contrast ratio in the left, right, and top and bottom directions.

As a method to solve the above problems, a dual cell liquid crystal display device is being considered. A dual cell liquid crystal display device has two liquid crystal cells. One of these is a cell (mono cell) that is located adjacent to the backlight unit and maximizes the contrast ratio, and the other is a cell (color cell) that is located adjacent to the viewer's viewing side and realizes the same color as a conventional liquid crystal cell. . The mono cell filters the light coming from the backlight unit and then transmits it to the color cell, so the dual cell liquid crystal display device can further improve the contrast ratio compared to the liquid crystal display device with one liquid crystal cell.

However, even in a dual-cell liquid crystal display device, when the liquid crystal layer is tilted, the viewing angle and side contrast ratio are still low, and there is a problem of light leakage.

The background technology of the present invention is disclosed in Korean Patent Publication No. 10-2013-0103595, etc.

The purpose of the present invention is to provide a dual cell liquid crystal display device that improves the decrease in contrast ratio at the front and side and provides a wide viewing angle.

Another object of the present invention is to provide a dual cell liquid crystal display device with improved color shift according to viewing angle in black mode.

Another object of the present invention is to provide a dual cell liquid crystal display device that provides an improvement in light leakage.

One aspect of the present invention is a dual cell liquid crystal display device.

1. A dual cell liquid crystal display device includes a first cell, a second cell disposed below the first cell, and a stack of a positive C plate and a positive A plate stacked on one surface of the first cell. polarizer; and a polarizer for a second cell that is laminated on one side of the second cell and includes a laminate of a positive C plate and a positive A plate, wherein the polarizer for the first cell and the polarizer for the second cell are formed between the first cell and the first cell. It is disposed between two cells, or the polarizer for the first cell is disposed on the upper surface of the first cell and the polarizer for the second cell is disposed on the lower surface of the second cell.

In 2.1, the positive A plate among the polarizers for the first cell is disposed adjacent to the first cell relative to the positive C plate, and the positive A plate among the polarizers for the second cell is disposed adjacent to the second cell relative to the positive C plate. Can be placed adjacent to each other.

In 3.1-2, in the polarizer for the first cell and the polarizer for the second cell, the positive C plate may be disposed between the positive A plate and the polarizer.

In 4.1-3, the polarizer for the first cell is stacked in the order of the positive A plate, the positive C plate, and the polarizer from the first cell, and the polarizer for the second cell is the positive A plate from the second cell, The positive C plate and the polarizer may be laminated in that order.

In 5.1-4, the first cell may be disposed on the light emission surface of the second cell.

In 6.1-5, the liquid crystal orientation direction of the liquid crystal layer of the first cell may be 175° to 185° compared to the liquid crystal orientation direction of the liquid crystal layer of the second cell.

In 7.1-6, the liquid crystal orientation direction of the liquid crystal layer of the first cell may be 0°, 90°, 180°, or 270°, assuming that the long side direction of the first cell is 0°.

In 8.1-7, the first cell and the second cell may each include an IPS mode liquid crystal layer.

In 9.1-8, the tilt angle of the liquid crystal in the liquid crystal layer of the first cell and the second cell may be 1° to 5°, respectively.

In 10.1-9, the slow axis of the positive A plate of the polarizer for the first cell may be -5° to +5° compared to the slow axis of the positive A plate of the polarizer for the second cell.

In 11.1-10, the light absorption axis of the polarizer in the polarizer for the first cell may be -5° to +5° compared to the light absorption axis of the polarizer in the polarizer for the second cell.

In 12.1-11, the slow axis of the positive A plate of the polarizer for the first cell and the liquid crystal orientation direction of the liquid crystal layer of the first cell are 85° to 95°, and the slow axis of the positive A plate of the polarizer for the second cell is 85° to 95°. The axis and the liquid crystal alignment direction of the liquid crystal layer of the second cell may be 85° to 95°.

13.1-12, the light absorption axis of the polarizer in the polarizer for the first cell and the liquid crystal orientation direction of the liquid crystal layer of the first cell are 85° to 95°, and the light absorption axis of the polarizer in the polarizer for the second cell and the second cell are The liquid crystal orientation direction of the liquid crystal layer of the two cells may be 85° to 95°.

14.1-13, the positive A plate can satisfy Equations 1 and 2 below:

[Equation 1]

Re(450)/Re(550) ≥ Re(650)/Re(550),

[Equation 2]

Rth(450)/Rth(550) ≥ Rth(650)/Rth(550)

(In Equations 1 and 2 above, Re(450), Re(550), and Re(650) are the in-plane retardation, Rth(450), Rth(550) at the wavelengths of 450nm, 550nm, and 650nm of the positive A plate, respectively. Rth (650) is the thickness direction phase difference at the wavelengths of 450 nm, 550 nm, and 650 nm of the positive A plate, respectively).

15.1-14, the positive A plate may have an in-plane retardation of 100 nm to 160 nm at a wavelength of 550 nm, and the positive C plate may have a thickness direction retardation of -120 nm to -60 nm at a wavelength of 550 nm.

In 16.1-15, the positive A plate and the positive C plate may be a non-liquid crystal layer or a liquid crystal layer, respectively.

In 17.1-16, the positive A plate and the positive C plate may each have a refractive index of 1.4 or more and 1.6 or less.

In 18.1-17, an auxiliary polarizer for a first cell may be further laminated on the other side of the first cell, and an auxiliary polarizer for a second cell may be further laminated on the other side of the second cell.

In 19.18, the light absorption axis of the polarizer in the auxiliary polarizer for the first cell and the light absorption axis of the polarizer in the polarizer for the first cell form 85° to 95°, and the light absorption axis of the polarizer in the auxiliary polarizer for the second cell and the first cell Among two-cell polarizers, the light absorption axis of the polarizer may be 85° to 95°.

In 20.18-19, the auxiliary polarizer for the first cell and the auxiliary polarizer for the second cell may not include a positive A plate and a positive C plate, respectively.

The present invention provides a dual cell liquid crystal display device that improves contrast ratio deterioration at the front and side and provides a wide viewing angle.

The present invention provides a dual cell liquid crystal display device with improved color shift according to viewing angle in black mode.

The present invention provides a dual cell liquid crystal display device that provides an improvement in light leakage.

1 is a cross-sectional view of a dual cell liquid crystal display device according to an embodiment of the present invention.
Figure 2 is a cross-sectional view of a dual cell liquid crystal display device according to another embodiment of the present invention.
Figure 3 is a conceptual diagram explaining angles in this specification.
Figure 4 is a cross-sectional view of the dual cell liquid crystal display device of Comparative Example 2.
Figure 5 is a cross-sectional view of the dual cell liquid crystal display device of Comparative Example 3.
Figure 6 shows the light leakage evaluation results of Example 1 (A) and Comparative Example 1 (B).
Figure 7 shows the color shift evaluation results of Example 1 (A), Comparative Example 1 (B), and Comparative Example 2 (C).

With reference to the attached drawings, the present invention will be described in detail through examples so that those skilled in the art can easily practice it. The present invention may be implemented in many different forms and is not limited to the embodiments described herein.

In order to clearly explain the present invention in the drawings, parts not related to the description are omitted, and the same names are used for identical or similar components throughout the specification. The length and size of each component in the drawings are for illustrative purposes only, and the present invention is not limited to the length and size of each component depicted in the drawings.

In this specification, “upper” and “lower” are defined based on the drawings, and “upper” may be changed to “lower” and “lower” may be changed to “upper” depending on the viewing angle.

In this specification, “in-plane retardation (Re)” can be expressed by the following formula A, and “thickness direction retardation (Rth)” can be expressed by the following formula B:

[Formula A]

Re = (nx - ny) x d

[Formula B]

Rth = ((nx + ny)/2 - nz) x d

(In the above equations A to B, nx, ny, and nz are the refractive indexes in the slow axis direction, fast axis direction, and thickness direction of the optical element at the measurement wavelength, respectively, and d is the thickness of the optical element. (Unit: nm). In Equations A to B, the measurement wavelength may be 450 nm, 550 nm, or 650 nm. The slow axis and fast axis refer to the axis with the highest and lowest refractive index among the in-plane directions, respectively.

In this specification, “positive A plate” is a plate that satisfies nx>ny=nz (nx, ny, and nz are refractive indices in the slow axis direction, fast axis direction, and thickness direction, respectively, at a wavelength of 550 nm).

In this specification, “positive C plate” is a plate that satisfies nz>nx=ny (nx, ny, and nz are refractive indices in the slow axis direction, fast axis direction, and thickness direction, respectively, at a wavelength of 550 nm).

In this specification, “substantially parallel” means that the angle between objects is not only 0° but also -5° to +5°, preferably -3° to +3°, and more preferably -1° to +1°. may include.

As used herein, “substantially perpendicular” may include cases where the angle between objects is not only 90° but also 85° to 95°, preferably 87° to 93°, and more preferably 89° to 91°.

In this specification, “refractive index” means the value at a wavelength of 550 nm.

In this specification, when indicating a numerical range, “X to Y” means greater than X and less than or equal to Y (X≤ and ≤Y).

The present invention provides a dual cell liquid crystal display device that increases contrast ratio from the front and sides and provides a wide viewing angle. The present invention provides a dual cell liquid crystal display device that reduces color shift depending on viewing angle in black mode. The present invention provides a dual cell liquid crystal display device that provides an improvement in light leakage.

The present invention applies a laminate of a positive C plate and a positive A plate, and the arrangement of each laminate is adjusted in a dual cell liquid crystal display device.

The dual cell liquid crystal display device of the present invention includes a first cell; a second cell disposed below the first cell; A polarizer for a first cell that is laminated on one surface of the first cell and includes a laminate of a positive C plate and a positive A plate; and a polarizer for a second cell that is laminated on one side of the second cell and includes a laminate of a positive C plate and a positive A plate, wherein the polarizer for the first cell and the polarizer for the second cell are formed between the first cell and the first cell. placed between 2 cells; Alternatively, the polarizer for the first cell is disposed on the upper surface of the first cell and the polarizer for the second cell is disposed on the lower surface of the second cell.

The positive A plate among the polarizers for the first cell may be disposed adjacent to the first cell relative to the positive C plate, and the positive A plate among the polarizers for the second cell may be disposed adjacent to the second cell relative to the positive C plate. Through this, it may be easier to implement the effects of the present invention.

In each of the polarizer for the first cell and the polarizer for the second cell, the positive C plate may be disposed between the positive A plate and the polarizer. Through this, it may be easier to implement the effects of the present invention.

The polarizer for the first cell may be stacked in the order of the positive A plate, positive C plate, and polarizer from the first cell, and the polarizer for the second cell may be stacked in the order of the positive A plate, positive C plate, and polarizer from the second cell. there is. Through this, it may be easier to implement the effects of the present invention.

Preferably, in a dual cell liquid crystal display device, the effect of the present invention can be further improved by adjusting the liquid crystal orientation direction of the liquid crystal layer of each cell. The first cell and the second cell each include a liquid crystal layer, and the liquid crystal orientation direction of the liquid crystal layer of the first cell may be substantially parallel but opposite to the liquid crystal orientation direction of the liquid crystal layer of the second cell. For example, the liquid crystal orientation direction of the liquid crystal layer of the first cell and the liquid crystal orientation direction of the liquid crystal layer of the second cell may be 175° to 185°, and preferably 180°. Through this, it may be easier to implement the effects of the present invention. The 'liquid crystal orientation direction' may be measured by measuring box axo and calculating based on Mueller Matrix, but is not limited to this.

The slow axis of the positive A plate among the polarizers for the first cell may be substantially parallel to the slow axis of the positive A plate among the polarizers for the second cell, for example, -5° to +5°, 0°. Through this, it may be easier to implement the effects of the present invention.

The light absorption axis of the polarizer in the polarizer for the first cell is substantially parallel to the light absorption axis of the polarizer in the polarizer for the second cell and may be, for example, -5° to +5° or 0°. Through this, it may be easier to implement the effects of the present invention.

Preferably, in a dual cell liquid crystal display device, the effect of the present invention can be further improved by adjusting the angle between the liquid crystal orientation direction of the liquid crystal layer of each cell and the slow axis of the positive A plate. In one embodiment, the slow axis of the positive A plate in the polarizer for the first cell and the liquid crystal orientation direction of the liquid crystal layer of the first cell are substantially perpendicular, for example, 85° to 95°, 90°, and in the polarizer for the second cell, The slow axis of the positive A plate and the liquid crystal orientation direction of the liquid crystal layer of the second cell may be substantially perpendicular, for example, 85° to 95° or 90°. Through this, it may be easier to implement the effects of the present invention.

The slow axis of the positive A plate among the polarizers for the first cell and the light absorption axis of the polarizer may be substantially parallel, and the slow axis of the positive A plate among the polarizers for the second cell and the light absorption axis of the polarizer may be substantially parallel. Through this, it may be easier to implement the effects of the present invention. For example, the slow axis of the positive A plate and the light absorption axis of the polarizer may be -5° to +5° or 0°.

Preferably, in a dual cell liquid crystal display device, the effect of the present invention can be further improved by adjusting the angle between the liquid crystal alignment direction of the liquid crystal layer of each cell and the light absorption axis of the polarizer. In one embodiment, the light absorption axis of the polarizer in the polarizer for the first cell and the liquid crystal orientation direction of the liquid crystal layer of the first cell are substantially perpendicular, for example, 85° to 95°, 90°, and the polarizer in the polarizer for the second cell The light absorption axis and the liquid crystal alignment direction of the liquid crystal layer of the second cell may be substantially perpendicular, for example, 85° to 95° or 90°. Through this, it may be easier to implement the effects of the present invention.

The positive A plate may have an in-plane retardation of 100 nm to 160 nm at a wavelength of 550 nm. Within the above range, it can be easy to implement the effects of the present invention.

The positive A plate can satisfy Equation 1 and Equation 2 below: Through this, it can be easy to implement the effect of the present invention:

[Equation 1]

Re(450)/Re(550) ≥ Re(650)/Re(550)

[Equation 2]

Rth(450)/Rth(550) ≥ Rth(650)/Rth(550)

(In Equations 1 and 2 above, Re(450), Re(550), and Re(650) are the in-plane retardation, Rth(450), Rth(550) at the wavelengths of 450nm, 550nm, and 650nm of the positive A plate, respectively. Rth (650) is the thickness direction phase difference at the wavelengths of 450 nm, 550 nm, and 650 nm of the positive A plate, respectively).

For example, a positive A plate may have Re(450)/Re(550) greater than 1 and less than 2, 1.01 to 1.2, and Re(650)/Re(550) may be greater than 0.5 but less than 1, 0.8 to 0.99. Positive A plate may have Rth(450)/Rth(550) greater than 1 but less than 2, 1.01 to 1.3, and Rth(650)/Rth(550) may be greater than 0.5 but less than 1, 0.8 to 0.99.

Positive A plate can have a refractive index of 1.4 or more and 1.6 or less at a wavelength of 550 nm.

The positive C plate may have a thickness direction retardation of -120 nm to -60 nm at a wavelength of 550 nm. Within the above range, it can be easy to implement the effects of the present invention.

Positive C plate can have a refractive index of 1.4 or more and 1.6 or less at a wavelength of 550 nm.

Hereinafter, a dual cell liquid crystal display device of an embodiment of the present invention will be described with reference to FIGS. 1 to 3.

The liquid crystal display device may include a first cell 100, a second cell 200, a polarizer 110 for the first cell, and a polarizer 210 for the second cell.

First cell 100 and second cell 200

The first cell 100 may be disposed on the light emission surface of the second cell 200. A backlight unit (not shown in FIGS. 1 and 2 ) including a light source may be disposed below the second cell 200 . Although not particularly limited, light emitted from the second cell 200 (internal light, light emitted from the backlight unit) may be incident on the first cell 100 and then emitted.

The first cell 100 is a main cell in a dual cell liquid crystal display device and may function as a color cell. The first cell 100 can display a color screen by including an RGB color filter, as in a typical LCD device.

The second cell 200 is a sub cell in a dual cell liquid crystal display device and may function as a light modulating cell or a mono cell. The second cell 200 can further increase the contrast ratio by filtering the light emitted from the backlight unit and emitting it to the first cell 100.

The first cell 100 and the second cell 200 each include a pair of transparent substrates facing each other at a predetermined distance and a liquid crystal layer interposed between the transparent substrates. The liquid crystal layer is not particularly limited, but may preferably include liquid crystal in IPS mode.

In one embodiment, in each liquid crystal layer of the first cell 100 and the second cell 200, the tilt angle of the liquid crystal may be 1° to 5°, for example, 1° to 3°.

The first cell 100 and the second cell 200 may each include a color filter or a TFT. Preferably, the first cell 100 may include a color filter.

The liquid crystal layer of the first cell and the liquid crystal layer of the second cell each have a liquid crystal orientation direction at a predetermined angle. The liquid crystal alignment direction of the liquid crystal layer of the first cell may be substantially parallel but opposite to the liquid crystal alignment direction of the liquid crystal layer of the second cell. When the first cell is rubbed along the X-axis, a pre-tilt is generated in the has an offsetting effect. The liquid crystal orientation direction in the liquid crystal layer of the first cell may be 175° to 185°, preferably 180°, compared to the liquid crystal orientation direction in the liquid crystal layer of the second cell.

In one embodiment, the directions in which the liquid crystals of the liquid crystal layer of the first cell and the liquid crystal layer of the second cell are arranged are parallel to each other on a plane, and the tilt angle of the liquid crystal in the Z-axis direction with respect to the plane of each liquid crystal cell (tilt angle) can be opposite to each other.

In this specification, in a liquid crystal cell, liquid crystal panel, or liquid crystal layer, the in-plane direction is defined as the X-axis direction, which is the long side direction, and the Y-axis direction, which is the short side direction, and the direction floating from the in-plane direction is defined as the Z-axis direction.

In one embodiment, when the liquid crystal orientation direction in the first cell is 0°, the liquid crystal orientation direction in the second cell is 180°, and when the liquid crystal orientation direction in the first cell is 90°, the liquid crystal orientation direction in the second cell is 180°. The liquid crystal orientation direction may be 270°. In addition, when the liquid crystal orientation direction in the first cell is 180°, the liquid crystal orientation direction in the second cell is 0°, and when the liquid crystal orientation direction in the first cell is 270°, the liquid crystal orientation direction in the second cell is 0°. can be 90°.

In this specification, all "angles" refer to FIG. 3, when the liquid crystal panel has a long side direction (X-axis direction) and a short side direction (Y-axis direction), assuming that one axis of the long side direction is 0°, counterclockwise These values are defined as 90°, 180°, and 270° by rotating them by 90°.

The liquid crystal orientation direction of the liquid crystal layer of the first cell 100 may be 0°, 90°, 180°, or 270°, assuming that the long side direction of the first cell 100 is 0°. The liquid crystal orientation direction of the liquid crystal layer of the second cell 200 may be 0°, 90°, 180°, or 270°, assuming that the long side direction of the second cell 200 is 0°.

The liquid crystal alignment direction in each of the liquid crystal layer of the first cell and the liquid crystal layer of the second cell can be implemented by adjusting the rubbing direction of the liquid crystal or the photo-alignment direction of the liquid crystal when forming the liquid crystal layer. For example, the rubbing direction in the liquid crystal layer of the first cell and the liquid crystal layer of the second cell can be controlled by forming an alignment film on a transparent substrate and then rotating the roller, etc. in a physical way to align it, and controlling the rotation direction of the roller. You can. For example, the photo-alignment direction in the liquid crystal layer of the first cell and the liquid crystal layer of the second cell can be adjusted by applying the photo-alignment liquid crystal and then controlling the light irradiation direction.

In the present invention, optical compensation polarizers (polarizer for the first cell, polarizer for the second cell) having both a positive A plate and a positive C plate for each of the first and second cells were laminated on one surface, and the positions of the optical compensation polarizers were adjusted. .

In one embodiment, referring to FIG. 1, the polarizer 110 for the first cell is laminated on the lower surface of the first cell 100, and the polarizer 210 for the second cell is laminated on the upper surface of the second cell 200. are stacked. In another specific example, referring to FIG. 2, the polarizer 110 for the first cell is laminated on the upper surface of the first cell 100, and the polarizer 210 for the second cell is laminated on the lower surface of the second cell 200. are stacked.

Through this, it can be easy to implement the effects of the present invention, which increases the contrast ratio from the front and sides, provides a wide viewing angle, reduces color shift depending on the viewing angle in black mode, and improves light leakage.

Polarizer 110 for the first cell and polarizer 210 for the second shell

The polarizer 110 for the first cell includes a polarizer 111 and a laminate of a positive C plate 112 and a positive A plate 113 stacked on one surface of the polarizer 111. The polarizer 210 for the second cell includes a polarizer 211 and a laminate of a positive C plate 212 and a positive A plate 213 stacked on one surface of the polarizer 211.

In the polarizer 110 for the first cell and the polarizer 210 for the second cell, the positive A plate may be disposed adjacent to the cell compared to the positive C plate. Specifically, in the polarizer 110 for the first cell and the polarizer 210 for the second cell, a positive C plate may be disposed between the polarizer and the positive A plate, respectively. In this way, it may be easier to implement the effect of the present invention described above by compensating for the phase difference with respect to the light coming from the backlight unit.

The polarizer 110 for the first cell may be stacked in the order of the first cell 100, the positive A plate 113, the positive C plate 112, and the polarizer 111. The polarizer 210 for the second cell may be a positive A plate 213, a positive C plate 212, and a polarizer 211 stacked in that order from the second cell 200. In this way, it may be easier to implement the light leak improvement effect in the aspect of the present invention described above by compensating for the phase difference with respect to the light coming from the backlight unit.

The present invention increases the contrast ratio from the front and side and provides a wide viewing angle by adjusting the angle between the liquid crystal orientation direction of the liquid crystal layer of each of the first cell and the second cell, the slow axis of the positive A plate, and the light absorption axis of the polarizer, In black mode, color shift according to viewing angle is reduced and the effect of improving light leakage is further enhanced.

The slow axis of the positive A plate 113 of the first cell polarizer 110 and the liquid crystal orientation direction of the liquid crystal layer of the first cell 100 are substantially perpendicular, and the positive A plate 213 of the second cell polarizer 210 ) and the liquid crystal orientation direction of the liquid crystal layer of the second cell 200 may be substantially perpendicular. In this way, it may be easier to implement the effect of the present invention described above by compensating for the phase difference with respect to the light coming from the backlight unit.

The slow axis of the positive A plate 113 of the polarizer 110 for the first cell and the light absorption axis of the polarizer 111 are substantially parallel but have the same direction, and the positive A plate 213 of the polarizer 210 for the second cell The slow axis of and the light absorption axis of the polarizer 211 may be substantially parallel and have the same direction. In this way, it may be easier to implement the effect of the present invention described above by compensating for the phase difference with respect to the light coming from the backlight unit.

The light absorption axis of the polarizer 111 of the polarizer 110 for the first cell is substantially perpendicular to the liquid crystal orientation direction of the liquid crystal layer of the first cell 100, and the light absorption of the polarizer 211 of the polarizer 210 for the second cell is substantially perpendicular to the liquid crystal orientation direction of the liquid crystal layer of the first cell 100. The axis may be substantially perpendicular to the liquid crystal orientation direction of the liquid crystal layer of the second cell 200. In this way, it may be easier to implement the effect of the present invention described above by compensating for the phase difference with respect to the light coming from the backlight unit.

The light absorption axis of the polarizer 111 of the polarizer 110 for the first cell may be substantially parallel to the light absorption axis of the polarizer 211 of the polarizer 210 for the second cell.

Hereinafter, the polarizers 111 and 211, positive A plates 113 and 213, and positive C plates 112 and 212 of the first cell polarizer 110 and the second cell polarizer 210 will be described in detail.

The polarizers 111 and 211 may convert incident light into linearly polarized light in a specific direction and then emit it. The polarizer can be manufactured from a polymer film containing polyvinyl alcohol-based resin as a main component. Specifically, the polarizer 110 can be manufactured by dyeing the polymer film with iodine or a dichroic dye and stretching it in MD (machine direction). Specifically, it can be manufactured through a swelling process, a dyeing step, a stretching step, and a crosslinking step. The polarizer may have a light absorption axis (MD) and a light transmission axis (TD, transverse direction) in an in-plane direction.

The polarizers 111 and 211 may have a light transmittance of 40% or more, for example, 40% to 46%, and a polarization degree of 95% or more, for example, 95% to 99.9%. In the above range, screen quality can be excellent.

The polarizers 111 and 211 may have a thickness of 2㎛ to 30㎛, specifically 4㎛ to 25㎛, and can be used in the polarizing plate within this range.

Positive A plates 113 and 213 may satisfy Equation 1 and Equation 2 above. Preferably, the positive A plate has constant wavelength dispersion (Re(450)/Re(550) > Re(650)/Re(550), Rth(450)/Rth(550) in both in-plane phase difference and thickness direction phase difference. > It can be Rth(650)/Rth(550). Through this, the positive A plate can help improve side contrast ratio and color shift according to viewing angle in the dual cell liquid crystal display device of the present invention.

The positive A plates 113 and 213 may have an in-plane retardation of 100 nm to 160 nm at a wavelength of 550 nm. Within the above range, the lateral contrast ratio can be improved and the color shift according to the viewing angle in black mode can be improved. Preferably, the positive A plate may have an in-plane retardation of 120 nm to 150 nm at a wavelength of 550 nm.

The positive A plates 113 and 213 may have a thickness direction retardation of 50 nm to 80 nm, preferably 60 nm to 75 nm, at a wavelength of 550 nm. Within the above range, the lateral contrast ratio can be improved and the color shift according to the viewing angle in black mode can be improved.

The positive A plates 113 and 213 may have a refractive index of 1.4 or more and 1.6 or less at a wavelength of 550 nm, preferably 1.46 or more and 1.59 or less.

The positive A plates 113 and 213 may be non-liquid crystal layers or liquid crystal layers.

In one embodiment, the positive A plates 113 and 213 may be non-liquid crystal layers. For example, the positive A plate may be an optically transparent polymer stretched film or an optically transparent polymer coating layer. The polymer is cellulose-based including triacetylcellulose, polyester-based including polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate (PET), polybutylene naphthalate, cyclic polyolefin (COP)-based, Cyclic olefin copolymer (COC)-based, polycarbonate-based, polyethersulfone-based, polysulfone-based, polyamide-based, polyimide-based, polyolefin-based, polyarylate-based, polyvinyl alcohol-based, polyvinyl chloride-based, polychlorinated It may include, but is not limited to, one or more of vinylidene-based and acrylic-based.

In another embodiment, the positive A plates 113 and 213 may be a liquid crystal layer. For example, the positive A plate can be formed by forming an alignment film on a base film or positive C plate, rubbing it, applying a liquid crystal, and solidifying or curing it.

The positive A plates 113 and 213 may have a thickness of 0.1 ㎛ to 90 ㎛, for example, 0.5 ㎛ to 10 ㎛, 20 ㎛ to 90 ㎛, 30 ㎛ to 70 ㎛, and can be used in the polarizer within the above range. .

The positive C plates 112 and 212 may have a thickness direction retardation of -120 nm to -60 nm at a wavelength of 550 nm. Within the above range, it can help improve lateral contrast ratio and color shift according to viewing angle in the liquid crystal display device of the present invention. Preferably, the positive C plate may have a thickness direction retardation of -110 nm to -60 nm at a wavelength of 550 nm.

The positive C plates 112 and 212 may have an in-plane retardation of -20 nm to 20 nm, preferably -10 nm to 10 nm at a wavelength of 550 nm. Within the above range, it may be easy to implement the thickness direction phase difference.

The positive C plates 112 and 212 may have a refractive index of 1.4 or more and 1.6 or less at a wavelength of 550 nm, preferably 1.46 or more and 1.59 or less.

Positive C plates 112 and 212 may be non-liquid crystal layers or liquid crystal layers.

In one embodiment, positive C plates 112, 212 may be non-liquid crystal layers. For example, the positive C plate may be an optically transparent polymer stretched film or an optically transparent polymer coating layer. The polymer is a cellulose ester-based, polyester-based polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate (PET), polybutylene naphthalate, cyclic polyolefin (COP)-based, cyclic olefin copolymer ( COC)-based, polycarbonate-based, polyethersulfone-based, polysulfone-based, polyamide-based, polyimide-based, polyolefin-based, polyarylate-based, polyvinyl alcohol-based, polyvinyl chloride-based, polyvinylidene chloride-based, and acrylic-based. It may include, but is not limited to, one or more. Preferably, the positive C plate can be formed directly on the positive A plate as a cellulose-based coating layer.

In another embodiment, the positive C plates 112 and 212 may be a liquid crystal layer. For example, a positive C plate can be formed by forming an alignment film on a base film or positive A plate, then rubbing it, applying a liquid crystal, and solidifying or curing it. The positive C plate may be formed by applying photo-alignment liquid crystal and then irradiating and curing it with light, but is not limited thereto.

The polarizer 110 for the first cell and the polarizer 210 for the second cell may each further include a transparent protective layer as long as it does not cancel out the effect of the present invention. The transparent protective layer is different from the positive A plate and positive C plate.

In one embodiment, the polarizer 110 for the first cell has a transparent protective layer further on the lower surface of the polarizer 111, between the polarizer 111 and the positive C plate 112, or on the upper surface of the positive A plate 113. Can be laminated.

In one embodiment, the polarizer 210 for the second cell has a transparent protective layer further on the upper surface of the polarizer 211, between the polarizer 211 and the positive C plate 212, or on the lower surface of the positive A plate 213. Can be stacked.

The transparent protective layer is cellulose-based including triacetylcellulose, polyester-based including polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate (PET), polybutylene naphthalate, and cyclic polyolefin (COP)-based. , cyclic olefin copolymer (COC)-based, polycarbonate-based, polyethersulfone-based, polysulfone-based, polyamide-based, polyimide-based, polyolefin-based, polyarylate-based, polyvinyl alcohol-based, polyvinyl chloride-based, poly It may include, but is not limited to, a resin film containing one or more of vinylidene chloride-based and acrylic-based resins with an in-plane retardation of 10 nm or less at a wavelength of 550 nm.

The polarizer 110 for the first cell and the polarizer 210 for the second cell each have a light transmittance of 44% or more, preferably 44% to 50%, and a polarization degree of 99% or more, preferably 99.99% to 100%, more preferably. In other words, it may be 99.992% to 100%.

An auxiliary polarizer 120 for the first cell may be further stacked on the upper surface of the first cell 100, and an auxiliary polarizer 220 for the second cell may be further stacked on the lower surface of the second cell 200. The auxiliary polarizers 120 and 220 do not include a positive A plate or a positive C plate, but are provided with a polarizer, so that light can be polarized and transmitted.

The auxiliary polarizer 120 for the first cell and the auxiliary polarizer 220 for the second cell may include a polarizer and a protective layer laminated on at least one surface of the polarizer, respectively. The light absorption axis of the polarizer in the auxiliary polarizer 120 for the first cell may be substantially orthogonal to the light absorption axis of the polarizer in the polarizer 110 for the first cell. The light absorption axis of the polarizer in the auxiliary polarizer 220 for the second cell may be substantially orthogonal to the light absorption axis of the polarizer in the polarizer 210 for the second cell.

The polarizer 110 for the first cell and the auxiliary polarizer 120 for the first cell may be laminated to the first cell 100 by an adhesive layer or adhesive layer, respectively. The polarizer 210 for the second cell and the auxiliary polarizer 220 for the second cell may be laminated to the second cell 200 by an adhesive layer or an adhesive layer, respectively.

Table 1 below shows the liquid crystal orientation direction, light absorption axis, and slow axis when the polarizer for the first cell and the polarizer for the second cell are disposed between the first cell and the second cell in the dual cell liquid crystal display device of an embodiment of the present invention. It represents the angle.

Table 2 below shows the liquid crystal orientation direction and light when the polarizer for the first cell is disposed on the upper surface of the first cell and the polarizer for the second cell is disposed on the lower surface of the second cell in the dual cell liquid crystal display device of another embodiment of the present invention. It represents the angle between the absorption axis and the slow axis.

Although not shown in FIGS. 1 and 2, the dual cell liquid crystal display may further include an optical sheet such as a prism sheet between the first cell 100 and the second cell 200. A window, etc. may be further provided on the upper part of the first cell 100, and a reflective sheet, a backlight unit, etc. may be further provided on the lower part of the second cell 200.

Hereinafter, the configuration and operation of the present invention will be described in more detail through preferred embodiments of the present invention. However, this is presented as a preferred example of the present invention and should not be construed as limiting the present invention in any way.

Manufacturing Example 1: Polarizer 110 for the first cell and polarizer 210 for the second cell

A polyvinyl alcohol-based film (PS#60, Kuraray, Japan, thickness before stretching: 60㎛) was stretched six times in an iodine aqueous solution at 55°C to prepare a polarizer with a light transmittance of 45%.

A polarizing plate was manufactured in which a positive C layer and a positive A layer were sequentially laminated on one side of the prepared polarizer, and a triacetylcellulose film was laminated on the other side of the prepared polarizer. The laminate of the positive C layer and the positive A layer is coated with a composition for the positive C layer prepared by uniformly mixing a cellulose ester-based compound (Eastman, cellulose acetate-based) and solvent methyl ethyl ketone) on a cyclic olefin polymer film and cured. It was manufactured by

The positive A layer has a refractive index of 1.53, an in-plane retardation of 140 nm at a wavelength of 550 nm, Re(450)/Re(550) > Re(650)/Re(550), Rth(450)/Rth(550) > Rth(650). /Satisfies Rth(550). The positive C layer had a refractive index of 1.52 and a thickness direction retardation of -85 nm at a wavelength of 550 nm.

Manufacturing Example 2: Polarizer 110 for the first cell and polarizer 210 for the second cell

A polyvinyl alcohol-based film (PS#60, Kuraray, Japan, thickness before stretching: 60㎛) was stretched six times in an iodine aqueous solution at 55°C to prepare a polarizer with a light transmittance of 45%.

A polarizing plate was manufactured in which a positive C layer and a positive A layer were sequentially laminated on one side of the prepared polarizer, and a triacetylcellulose film was laminated on the other side of the prepared polarizer. It was manufactured in the same manner as in Preparation Example 1, except that the characteristics of the positive A layer and positive C layer were changed as follows. The positive A layer has a refractive index of 1.6, an in-plane retardation of 125 nm at a wavelength of 550 nm, Re(450)/Re(550) > Re(650)/Re(550), Rth(450)/Rth(550) > Rth(650). /Satisfies Rth(550). The positive C layer had a refractive index of 1.51 and a thickness direction retardation of -100 nm at a wavelength of 550 nm.

Manufacturing Example 3: Auxiliary polarizer 120 for the first cell and auxiliary polarizer 220 for the second cell

A polarizer was manufactured in the same manner as Preparation Example 1.

A polarizing plate was manufactured by laminating a triacetylcellulose film on one side of the prepared polarizer, and laminated a cyclic olefin polymer film on the other side of the prepared polarizer.

Example 1

A first cell and a second cell having an IPS liquid crystal layer with a liquid crystal tilt angle of 1.3° were prepared. The auxiliary polarizer of Preparation Example 3 was laminated on the upper surface of the first cell, the polarizer of Preparation Example 1 was laminated on the lower surface of the first cell, the polarizer of Preparation Example 1 was laminated on the upper surface of the second cell, and the polarizer of Preparation Example 1 was laminated on the upper surface of the second cell. A module having the structure of FIG. 1 was manufactured by laminating the polarizing plate of Preparation Example 3 to the lower surface and stacking them on each other. At this time, the rubbing direction, slow axis, and light absorption axis were adjusted as shown in Table 3 below.

Examples 2 to 4

In Example 1, a module was manufactured in the same manner as Example 1, except that the rubbing direction, slow axis, and light absorption axis were changed as shown in Table 1 below.

Example 5

A first cell and a second cell each equipped with an IPS liquid crystal layer with a liquid crystal tilt angle of 1.3° were prepared. The polarizer of Preparation Example 2 was laminated on the upper surface of the first cell, the polarizer of Preparation Example 3 was laminated on the lower surface of the first cell, and the polarizer of Preparation Example 3 was laminated on the upper surface of the second cell. A module having the structure of FIG. 2 was manufactured by laminating the polarizing plate of Preparation Example 2 on the lower surface and stacking them on each other. At this time, the rubbing direction, slow axis, and light absorption axis were adjusted as shown in Table 3 below.

Examples 6 to 8

In Example 5, a module was manufactured in the same manner as Example 5, except that the rubbing direction, slow axis, and light absorption axis were changed as shown in Table 2 below.

Comparative Example 1

A first cell and a second cell each equipped with an IPS liquid crystal layer with a liquid crystal tilt angle of 1.3° were prepared. The polarizing plates of Preparation Example 3 were laminated on the upper and lower surfaces of the first cell, respectively, and the polarizing plates of Preparation Example 3 were laminated on the upper and lower surfaces of the second cell, respectively, and these were stacked together to manufacture a module. At this time, the rubbing direction and light absorption axis were adjusted as shown in Table 3 below. In Table 3 below, '-' means that the corresponding layer is not included.

Comparative Example 2

A first cell and a second cell each equipped with an IPS liquid crystal layer with a liquid crystal tilt angle of 1.3° were prepared. The polarizer of Preparation Example 3 was laminated on the upper surface of the first cell, the polarizer of Preparation Example 1 was laminated on the lower surface of the first cell, and the polarizer of Preparation Example 3 was laminated on the upper surface of the second cell. The polarizing plate of Preparation Example 1 was laminated on the lower surface, and the modules having the structure of FIG. 4 were manufactured by stacking them on each other. At this time, the rubbing direction and light absorption axis were adjusted as shown in Table 3 below.

Comparative Example 3

A first cell and a second cell each equipped with an IPS liquid crystal layer with a liquid crystal tilt angle of 1.3° were prepared. The polarizer of Preparation Example 1 was laminated on the upper surface of the first cell, the polarizer of Preparation Example 3 was laminated on the lower surface of the first cell, and the polarizer of Preparation Example 1 was laminated on the upper surface of the second cell. The polarizing plate of Preparation Example 3 was laminated on the lower surface, and the modules having the structure of FIG. 5 were manufactured by stacking them on each other. At this time, the rubbing direction and light absorption axis were adjusted as shown in Table 3 below.

The following physical properties were evaluated using the dual liquid crystal display modules of Examples and Comparative Examples and are shown in Tables 1 to 3 and Figures 6 and 7 below.

(1) Light leakage: The liquid crystal modules manufactured in Examples and Comparative Examples were simulated using EZ-Contrast XL-88 equipment and Techwiz. The light transmittance at the diagonal (θ, Ψ) = (60°, 45°) was measured. If the light leak suppression effect was excellent, it was evaluated as ◎, if the light leak suppression effect was ○, if the light leak suppression effect was minimal, it was evaluated as △, and if there was no light leak suppression effect, it was evaluated as x.

(2) Color shift: The liquid crystal modules manufactured in Examples and Comparative Examples were simulated using EZ-Contrast XL-88 equipment and Techwiz. If the liquid crystal alignment direction is 0°, 180°, calculate the distance △(x, y) between the color coordinates x and color coordinates y between (45°, 60°) and (135°, 60°), and if the liquid crystal alignment direction is 90° In the case of 270°, △(x, y) was calculated between (45°, 60°) and (315°, 60°). If △(x, y) is less than 0.0003, it is very good ◎, if it is more than 0.0003 but less than 0.1, it is effective ○, if it is more than 0.1 but less than 0.2, the effect is insignificant △, if it is more than 0.2, it is evaluated as x.

Example 1 Example 2 Example 3 Example 4 Auxiliary polarizer for first cell Light absorption axis of polarizer 0° 90° 0° 90° 1st cell Rubbing direction (liquid crystal orientation direction) 0° 90° 180° 270° Polarizer for first cell Ground axis of positive A plate 90° 0° 90° 0° Light absorption axis of polarizer 90° 0° 90° 0° Polarizer for second cell Light absorption axis of polarizer 90° 0° 90° 0° Ground axis of positive A plate 90° 0° 90° 0° 2nd cell Rubbing direction (liquid crystal orientation direction) 180° 270° 0° 90° Auxiliary polarizer for second cell Light absorption axis of polarizer 0° 90° 0° 90° light source ◎ ◎ ◎ ◎ color shift ◎ ◎ ◎ ◎

Example 5 Example 6 Example 7 Example 8 Polarizer for first cell Light absorption axis of polarizer 90° 0° 90° 0° Ground axis of positive A plate 90° 0° 90° 0° 1st cell Rubbing direction (liquid crystal orientation direction) 0° 90° 180° 270° Auxiliary polarizer for first cell Light absorption axis of polarizer 0° 90° 0° 90° Auxiliary polarizer for second cell Light absorption axis of polarizer 0° 90° 0° 90° 2nd cell Rubbing direction (liquid crystal orientation direction) 180° 270° 0° 90° Polarizer for second cell Ground axis of positive A plate 90° 0° 90° 0° Light absorption axis of polarizer 90° 0° 90° 0° light source ◎ ◎ ◎ ◎ color shift ◎ ◎ ◎ ◎

Comparative Example 1 Comparative Example 2 Comparative Example 3 Polarizer for first cell Light absorption axis of polarizer - - 90° Ground axis of positive A plate - - 90° Auxiliary polarizer for first cell Light absorption axis of polarizer 90° 0° - 1st cell Rubbing direction (liquid crystal orientation direction) 0° 0° 0° Polarizer for first cell Ground axis of positive A plate - 90° - Light absorption axis of polarizer - 90° - Auxiliary polarizer for first cell Light absorption axis of polarizer 0° - 0° Polarizer for second cell Light absorption axis of polarizer - - 90° Ground axis of positive A plate - - 90° Auxiliary polarizer for second cell Light absorption axis of polarizer 0° 0° - 2nd cell Rubbing direction (liquid crystal orientation direction) 180° 180° 180° Polarizer for second cell Ground axis of positive A plate - 90° - Light absorption axis of polarizer - 90° - Auxiliary polarizer for second cell Light absorption axis of polarizer 90° - 0° light source X △ △ color shift ○ △ △

As shown in Table 1, Table 2, and Figures 6 and 7, the dual cell liquid crystal display device of the present invention had excellent color shift and light leak improvement effects depending on the viewing angle in black mode.

On the other hand, as shown in Table 1, Table 2, Figures 6 and 7, Comparative Example 1, which does not include the polarizer for the first cell and the polarizer for the second cell of the present invention, and the polarizer for the first cell and the second polarizer of the present invention Comparative Examples 2 and 3, which included a polarizer for cells but were located at different positions among the liquid crystal display devices, had weak light leak improvement and color shift improvement effects compared to the Example.

Simple modifications or changes to the present invention can be easily implemented by those skilled in the art, and all such modifications or changes can be considered to be included in the scope of the present invention.

Claims (20)

1st cell,
a second cell disposed below the first cell,
A polarizer for a first cell that is laminated on one surface of the first cell and includes a laminate of a positive C plate and a positive A plate; and
A polarizing plate for the second cell is laminated on one surface of the second cell and includes a laminate of a positive C plate and a positive A plate,
The polarizer for the first cell and the polarizer for the second cell are disposed between the first cell and the second cell; or
A dual cell liquid crystal display device, wherein the polarizer for the first cell is disposed on an upper surface of the first cell and the polarizer for the second cell is disposed on a lower surface of the second cell.
The method of claim 1, wherein the positive A plate of the polarizer for the first cell is disposed adjacent to the first cell relative to the positive C plate,
Among the polarizers for the second cell, the positive A plate is disposed adjacent to the second cell compared to the positive C plate.
The dual cell liquid crystal display device of claim 1, wherein in the polarizer for the first cell and the polarizer for the second cell, the positive C plate is disposed between the positive A plate and the polarizer.
The method of claim 1, wherein the polarizer for the first cell is stacked in the order of the positive A plate, the positive C plate, and the polarizer, starting from the first cell,
The polarizer for the second cell is a dual cell liquid crystal display device in which the positive A plate, the positive C plate, and the polarizer are stacked in that order from the second cell.
The dual cell liquid crystal display device of claim 1, wherein the first cell is disposed on a light exit surface of the second cell.
The dual cell liquid crystal display device of claim 1, wherein the liquid crystal alignment direction of the liquid crystal layer of the first cell is 175° to 185° compared to the liquid crystal alignment direction of the liquid crystal layer of the second cell.
The dual cell liquid crystal of claim 1, wherein the liquid crystal orientation direction of the liquid crystal layer of the first cell is 0°, 90°, 180°, or 270°, assuming that the long side direction of the first cell is 0°. Display device.
The dual cell liquid crystal display device of claim 1, wherein the first cell and the second cell each have a tilt angle of the liquid crystal in the liquid crystal layer of 1° to 5°.
The dual cell liquid crystal display device of claim 1, wherein the first cell and the second cell each include an IPS mode liquid crystal layer.
The dual cell liquid crystal display device of claim 1, wherein the slow axis of the positive A plate among the polarizers for the first cell is -5° to +5° relative to the slow axis of the positive A plate among the polarizers for the second cell. .
The dual cell liquid crystal display device of claim 1, wherein the light absorption axis of the polarizer in the polarizer for the first cell is -5° to +5° compared to the light absorption axis of the polarizer in the polarizer for the second cell.
The method of claim 1, wherein the slow axis of the positive A plate of the polarizer for the first cell and the liquid crystal orientation direction of the liquid crystal layer of the first cell are 85° to 95°,
A dual cell liquid crystal display device, wherein the slow axis of the positive A plate of the polarizer for the second cell and the liquid crystal orientation direction of the liquid crystal layer of the second cell are 85° to 95°.
The method of claim 1, wherein the light absorption axis of the polarizer in the polarizer for the first cell and the liquid crystal alignment direction of the liquid crystal layer of the first cell are 85° to 95°,
A dual cell liquid crystal display device, wherein the light absorption axis of the polarizer of the polarizer for the second cell and the liquid crystal alignment direction of the liquid crystal layer of the second cell are 85° to 95°.
The dual cell liquid crystal display device of claim 1, wherein the positive A plate satisfies the following equations 1 and 2:
[Equation 1]
Re(450)/Re(550) ≥ Re(650)/Re(550),
[Equation 2]
Rth(450)/Rth(550) ≥ Rth(650)/Rth(550)
(In Equations 1 and 2 above, Re(450), Re(550), and Re(650) are the in-plane retardation, Rth(450), Rth(550) at the wavelengths of 450nm, 550nm, and 650nm of the positive A plate, respectively. Rth (650) is the thickness direction phase difference at the wavelengths of 450 nm, 550 nm, and 650 nm of the positive A plate, respectively).
The method of claim 1, wherein the positive A plate has an in-plane retardation of 100 nm to 160 nm at a wavelength of 550 nm,
The positive C plate is a dual cell liquid crystal display device in which the thickness direction phase difference is -120nm to -60nm at a wavelength of 550nm.
The dual cell liquid crystal display device of claim 1, wherein the positive A plate and the positive C plate are each a non-liquid crystal layer or a liquid crystal layer.
The dual cell liquid crystal display device of claim 1, wherein the positive A plate and the positive C plate each have a refractive index of 1.4 or more and 1.6 or less.
The method of claim 1, wherein an auxiliary polarizer for the first cell is further laminated on the other side of the first cell,
A dual cell liquid crystal display device in which an auxiliary polarizer for the second cell is further laminated on the other side of the second cell.
The method of claim 18, wherein the light absorption axis of the polarizer in the auxiliary polarizer for the first cell and the light absorption axis of the polarizer in the polarizer for the first cell form 85° to 95°,
A dual cell liquid crystal display device, wherein the light absorption axis of the polarizer among the auxiliary polarizers for the second cell and the light absorption axis of the polarizer among the polarizers for the second cell form 85° to 95°.
The dual cell liquid crystal display device of claim 18, wherein the auxiliary polarizer for the first cell and the auxiliary polarizer for the second cell do not include a positive A plate and a positive C plate, respectively.