KR100820785B1 - Liquid crystal display - Google Patents

Abstract

A liquid crystal display for improving the viewing angle while alleviating gray level inversion is disclosed. The liquid crystal display device includes a lower substrate including a first alignment layer stacked with a first rubbing pattern extending in a row direction (column direction) on a first substrate, and extending in a column direction (row direction) on a second substrate. An upper substrate including a second alignment layer laminated with a second rubbing pattern, a liquid crystal layer injected between the lower substrate and the upper substrate, and disposed on the upper substrate in a state where a plurality of holes are formed, And a porous film for reflecting a portion of the first light incident on the sidewall surface defining the hole among the first light emitted and outputting the second light having the compensated luminance distribution. Therefore, the liquid crystal display can improve the viewing angle while alleviating the gray level inversion.

Description

Liquid crystal display {LIQUID CRYSTAL DISPLAY}

1 is an exploded perspective view illustrating a general liquid crystal display device.

2 is an exploded perspective view of a liquid crystal display according to an exemplary embodiment of the present invention.

3 is a cross-sectional view of the liquid crystal display shown in FIG. 2.

4 is a view illustrating the display unit illustrated in FIG. 2 in detail.

FIG. 5 is a view illustrating viewing angle characteristics of the first and second alignment layers illustrated in FIG. 4 according to a rubbing direction.

6 is a view showing a process of changing the light path by the porous film shown in FIG.

7A is a cross-sectional view of a liquid crystal display according to another exemplary embodiment of the present invention.

FIG. 7B is a perspective view illustrating the display unit illustrated in FIG. 7A in detail.

8 is a cross-sectional view of a liquid crystal display according to another exemplary embodiment of the present invention.

9A to 9C are graphs showing simulation results of Experimental Example 1 according to the present invention.

10A to 10C are graphs showing simulation results of Experimental Example 2 according to the present invention.

11A to 11C are graphs showing simulation results according to Comparative Example 1. FIG.

12A to 12C are graphs showing simulation results according to Comparative Example 2. FIG.

 <Explanation of symbols for the main parts of the drawings>

500: display unit 510: liquid crystal display panel

512 TFT substrate 513 first alignment layer

514: color filter substrate 515: second alignment layer

516 liquid crystal layer 560 porous film

570: lower polarizing plate 580: upper polarizing plate

600: backlight unit 900: liquid crystal display device

The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device for improving a viewing angle while alleviating gray level inversion.

 In general, the liquid crystal display includes a first substrate on which a first electrode is formed, a first substrate facing the first substrate, a second substrate on which a second substrate is formed, and a liquid crystal injected between the first substrate and the second substrate. The liquid crystal display displays an image by applying a voltage to the first and second electrodes, respectively, and adjusting the amount of light transmitted by the liquid crystals arranged by the first and second electric fields.                         

Here, a twisted nematic liquid crystal (TN) liquid crystal in which the long axis of the liquid crystal is continuously twisted 90 ° toward the second electrode from the first electrode is mainly used for the liquid crystal.

Although the TN liquid crystals are not regularly arranged in position, the TN liquid crystals have a constant order assuming the axis of the liquid crystals. In this case, the liquid crystal has optical anisotropy with different physical properties in the major axis direction and the minor axis direction.

The conventional TN type liquid crystal display device which displays an image using the TN liquid crystal which has such a characteristic is demonstrated.

1 is an exploded perspective view illustrating a general liquid crystal display device.

Referring to FIG. 1, a general liquid crystal display device 400 may include a display unit 100 for displaying an image, a backlight unit 200 for generating light, the backlight unit 200, and a display unit 100. ) Is made of a mold flame 250 and a top chassis 300 for receiving.

The display unit 100 forms a screen of the liquid crystal display device 500 to display an image, and drive printing for providing driving signals and image data signals to the liquid crystal display panel 110. A circuit board 120 and 140 and a tape carrier package (hereinafter referred to as TCP) 130 and 150 are provided.

The liquid crystal display panel 110 is provided to face the TFT substrate 112 and the TFT substrate 112 on which a thin film transistor (hereinafter, referred to as TFT) and a pixel electrode (not shown) are formed. A color filter substrate 114 having a filter and a common electrode formed therein, and a liquid crystal (not shown) injected between the TFT substrate 112 and the color filter substrate 114.

The backlight unit 200 includes a lamp unit 210 for generating a first light and a light guide plate 220 for guiding the first light to the liquid crystal display panel 110. The lamp unit 210 includes a lamp 211 generating the first light and a lamp reflecting plate 213 reflecting the first light to the light guide plate 220. The light guide plate 220 includes an incident surface to which the first light is incident, an emission surface to emit the first light, and a reflection surface to reflect the first light to the emission surface, thereby providing the first light. It guides to the liquid crystal display panel 110 side.

The lower portion of the light guide plate 220 is provided with a reflecting plate 240 for reflecting the light leaking from the light guide plate 220 to the emission surface, the upper optical films for uniform brightness distribution of the light emitted from the emission surface 230 is provided.

Since the general liquid crystal display device 400 having such a structure uses a TN liquid crystal having optical anisotropy, the color and contrast ratio (C / R) values vary depending on the viewing angle. Therefore, a problem arises in that the range of the viewing angle at which the user can accurately recognize the information displayed on the screen is narrowed.

Although not shown in the drawings, in order to solve such a problem, a conventional compensation film is formed with a discotic layer. However, the compensation film may improve the viewing angle to some extent, but there is a problem in that gray scale inversion occurs when the viewing angle becomes more than a specific value.

That is, when the liquid crystal display panel 110 is viewed from the front, the normal gray level may be checked, but as the lower or upper side is lower than the front, the abnormal gray level may be confirmed. When the liquid crystal display panel 110 is observed at a threshold angle or more, a problem of gray level inversion in which white gray is inverted to black gray and white gray is inverted occurs.

SUMMARY OF THE INVENTION An object of the present invention for solving the above problems is to provide a liquid crystal display device that can improve the viewing angle while alleviating gray level inversion.

According to an aspect of the present invention, a liquid crystal display device includes a plurality of switching elements formed in a matrix form on a first substrate, a first electrode coupled to the switching element, and a row direction (column). A lower substrate including a first alignment layer stacked on the first substrate and having a first rubbing pattern extending in a direction; A color filter formed on a second substrate, a second electrode formed on the color filter, and a second alignment layer stacked on the second electrode with a second rubbing pattern extending in a column direction (row direction); An upper substrate; A liquid crystal layer injected between the lower substrate and the upper substrate; And a luminance distribution disposed on the upper substrate in a state where a plurality of holes are formed, and having a luminance distribution compensated by reflecting a portion of the first light emitted from the upper substrate to a sidewall surface defining the hole. And a light path changing member for emitting light.

In addition, the liquid crystal display according to another feature for achieving the above object of the present invention, a plurality of switching elements formed in a matrix form on the first substrate, the first electrode coupled to the switching element, and the row direction ( A lower substrate having a first rubbing pattern extending in a column direction) and including a first alignment layer stacked on the first substrate; A color filter formed on a second substrate, a second electrode formed on the color filter, and a second alignment layer stacked on the second electrode with a second rubbing pattern extending in a column direction (row direction); An upper substrate; A liquid crystal layer injected between the lower substrate and the upper substrate; A first polarizing member disposed under the lower substrate to polarize the first light provided to the lower substrate; And a second polarizing member disposed on the upper substrate to polarize the second light emitted from the upper substrate, and to emit a third light having a compensated luminance by reflecting a portion of the second light.

According to the liquid crystal display, a lower substrate having a first alignment layer having a first rubbing pattern extending in a row direction and an upper substrate having a second alignment layer having a second rubbing pattern extending in a column direction are provided. The liquid crystal layer injected between the lower substrate and the upper substrate is injected, and a porous film having a plurality of holes is disposed on the upper substrate. Therefore, the liquid crystal display may improve the viewing angle while alleviating the gray level inversion.

Hereinafter, with reference to the accompanying drawings, it will be described in detail an embodiment of the present invention.

FIG. 2 is an exploded perspective view illustrating a liquid crystal display according to an exemplary embodiment of the present invention, and FIG. 3 is a cross-sectional view of the liquid crystal display panel illustrated in FIG. 2.

2 and 3, the liquid crystal display 900 according to the exemplary embodiment of the present invention includes a display unit 500 for displaying an image and a backlight unit 600 for generating light. In detail, the backlight unit 600 generates the first light and provides the first light toward the display unit 500. The display unit 500 receives the first light and displays an image.

The display unit 500 includes a liquid crystal display panel 510 for implementing a screen, driving printed circuit boards 520 and 540 for providing driving signals and image data signals to the liquid crystal display panel 510, and a liquid crystal display panel ( TCP 530 and 550 for electrically connecting the 510 and the driving printed circuit boards 520 and 540, a lower polarizing plate 570 provided below the liquid crystal display panel 510, and a liquid crystal display panel 510. The upper polarizing plate 580 provided on the upper side, and the porous film 560 provided on the upper side of the upper polarizing plate 580.

The liquid crystal display panel 510 includes a TFT substrate 512, a color filter substrate 514, and a liquid crystal (not shown). The TFT substrate 512 is a substrate on which a TFT (not shown), a pixel electrode (not shown), and a first alignment layer (not shown) are formed, and the color filter substrate 514 is provided to face the TFT substrate 512. , A substrate including a color filter (not shown), a common electrode (not shown), and a second alignment layer (not shown). Liquid crystal is formed between the TFT substrate 512 and the color filter substrate 514. As the liquid crystal, TN liquid crystal is mainly used, which forms an arrangement in which the long axis of the liquid crystal is continuously twisted by 90 degrees from the pixel electrode toward the common electrode.

The lower polarizer 570 polarizes the first light incident from the backlight unit 600 and provides it to the liquid crystal display panel 510. The first light is incident on the liquid crystal display panel 510, and the optical axis is deflected in a predetermined direction by the liquid crystal whose alignment angle is changed by a power source applied from the outside, and is emitted as the second light. In this case, the second light includes image information. The second light is incident on the upper polarizing plate 580, and the upper polarizing plate 580 adjusts the amount of the second light and improves the viewing angle to emit the light.

The backlight unit 600 includes a lamp unit 610 for generating first light and a light guide plate 620 for guiding the first light to the liquid crystal display panel 510. The lamp unit 610 includes a lamp 611 that generates the first light and a lamp reflector 613 that reflects the first light to the light guide plate 620. The light guide plate 620 includes an incident surface on which the first light is incident, an emission surface on which the first light is emitted, and a reflective surface on which the first light is reflected on the emission surface, so that the first light is reflected on the liquid crystal display panel 510. Guide to the side.

The lower portion of the light guide plate 620 is provided with a reflecting plate 640 reflecting the light leaking from the light guide plate 620 to the emission surface, the upper optical film 630 for uniformizing the luminance distribution of the light emitted from the emission surface It is provided.

4 is a view illustrating the display unit illustrated in FIG. 2 in detail.

Referring to FIG. 4, the TFT substrate 512 includes a plurality of gate lines 512a extending in the column direction (hereinafter, referred to as a first direction) D1 and extending in a row direction (hereinafter referred to as a second direction) D2. Multiple data lines 512b are formed. In the TFT substrate 512, a plurality of TFTs 512c are formed in a matrix form. That is, the source electrode of the TFT 512c is connected to the data line 512b, the gate electrode of the TFT 512c is connected to the gate line 512a, and the drain electrode of the TFT 512c is connected to the pixel electrode 512d. Connected.

The first alignment film 513 is entirely stacked on the TFT substrate 512 on which the TFT 512c and the pixel electrode 512d are formed. The first alignment layer 513 is a film on which a first rubbing pattern (not shown) that is rubbed in the first direction D1 is formed after the polyimide organic film is coated.

In the drawing, an example in which the direction in which the first rubbing pattern extends is exactly coincident with the first direction D1 is illustrated. However, the direction in which the first rubbing pattern extends includes a range deviating from the first direction D1 at a predetermined angle. Here, it is preferable that a predetermined angle is an angle of the grade which can be generally called 1st direction D1.

On the other hand, the color filter substrate 514 is provided to face the TFT substrate 512. The color filter substrate 514 is a substrate on which a color filter (not shown), a common electrode (not shown), and a second alignment layer 515 are formed. In this case, the second alignment layer 515 is a film having a second rubbing pattern (not shown) that is rubbed in a second direction D2 orthogonal to the first direction D1 after applying the polyimide-based organic film. .

As illustrated, a first rubbing pattern extending in the first direction D1 is formed in the first alignment layer 513, and a second rubbing pattern extending in the second direction D2 is formed in the second alignment layer 515. Once formed, the process of rubbing the first and second alignment layers 513 and 515 is simplified. That is, since the rubbing length is shorter than rubbing in the diagonal direction of the screen implemented by the liquid crystal display device 900, the rubbing process of the first and second alignment layers 513 and 515 is simplified.

When the TFT substrate 512 and the color filter substrate 514 are completed, the liquid crystal layer 516 is injected between the TFT substrate 512 and the color filter substrate 514.

On the other hand, the lower polarizing plate 570 is provided below the TFT substrate 512, and the upper polarizing plate 580 is provided above the color filter substrate 514. The lower polarizer 570 is provided on the first and second surfaces of the first polarization layer 571 and the first polarization layer 571 to perform the polarization function, respectively, to support the first polarization layer 571. It consists of two support layers 572 and 573.

Specifically, the first polarizing layer 571 adsorbs iodine or dichroic dye on a poly-vinyl alcohol (hereinafter referred to as "PVA") layer having a first axis D1 as a transmission axis. Is formed. The first polarization layer 571 absorbs the components vibrating in the first direction D1, that is, the transmission axis, and the components vibrating in the second direction D2 perpendicular to the first direction D1. Permeate. Meanwhile, the first and second support layers 572 and 573 are formed of durable tri-acetyl cellulose (hereinafter referred to as TAC), and the upper and lower surfaces of the first polarization layer 571. The first polarization layer 571 is protected by supporting.

Meanwhile, the upper polarizer 580 is provided on the upper and lower surfaces of the second polarization layer 581 and the second polarization layer 581 to perform the polarization function, respectively, to support the second polarization layer 581. And fourth support layers 582 and 583.

The second polarizing layer 581 is formed by adsorbing iodine or dichroic dye on the PVA layer having the second direction D2 as the transmission axis. The second polarization layer 581 absorbs components that vibrate in the second direction D2 of the incident light and transmits components that vibrate in the first direction D1. The third and fourth support layers 582 and 583 are formed of TAC to protect the second polarization layer 581 by supporting the upper and lower surfaces of the second polarization layer 581, respectively.                     

In this way, the transmission axis extended in the first direction D1 is formed in the first polarization layer 571, and the transmission axis extended in the second direction D2 is formed in the second polarization layer 581. Defects generated during cutting of the second polarization layers 571 and 581 may be prevented. Therefore, productivity of the lower and upper polarizing plates 570 and 580 is improved. In addition, the manufacturing cost of the lower and upper polarizers 570 and 580 may be reduced by reducing the fabric.

Although not shown in the drawings, the lower polarizer further includes a first compensation film for compensating the viewing angle of the liquid crystal display, and the upper polarizer further includes a second compensation film for compensating the viewing angle of the liquid crystal display. It can be provided. In this case, the rubbing direction of the discotic liquid crystal formed on the first compensation film is parallel to the first direction D1, and the rubbing direction of the discotic liquid crystal formed on the second compensation film is preferably parallel to the second direction D2. .

In the drawing, although the first rubbing pattern extends in the first direction D1 and the second rubbing pattern extends in the second direction D2, the structure of the present invention is not limited thereto. Specifically, assuming that the first and second rubbing patterns are orthogonal, each of the first and second rubbing patterns may be formed in a direction facing up, down, left, and right when the screen of the liquid crystal display is viewed from the front. have.

Meanwhile, when the first and second rubbing patterns are changed, the directions of the first and second transmission axes respectively formed on the first and second polarizing plates 570 and 580 are also changed correspondingly.

2 to 4, a porous film 560 having a size corresponding to that of the liquid crystal display panel 510 is disposed on the liquid crystal display panel 510. Here, the porous film 560 is formed of a polymer resin such as a transparent acrylic resin having a predetermined refractive index.

The porous film 560 has an incident surface 561 on which the second light emitted from the liquid crystal display panel 510 is incident, an exit surface 562 on which the second light is emitted, the incident surface 561, and an exit surface ( 562 connecting sides 563. The porous film 560 has a plurality of holes 565 formed from the incident surface 561 to the exit surface 562.

Accordingly, a plurality of sidewall surfaces 564 are formed in the porous film 560 to connect the incident surface 561 and the exit surface 562 and surround the plurality of holes 565. The plurality of sidewall surfaces 564 redirect the second light to emit third light having an extended viewing angle.

Although not shown in the drawings, a method of forming a plurality of holes 565 in the porous film 560 is formed by using silica particles, a method of drilling directly into the polymer film using a laser and a photo process. In general, methods applicable to forming a hole in a film may be applied. Since the methods of manufacturing the porous film 560 are general techniques, detailed description thereof will be omitted.

FIG. 5 is a view illustrating viewing angle characteristics according to a rubbing direction of the first and second alignment layers illustrated in FIG. 4, and FIG. 6 is a view illustrating a light path changing state according to a porous film. In FIG. 5, the left and right directions are represented by A and A ', respectively, and the up and down directions are represented by B and B', respectively, based on the front view of the drawings.

Referring to FIG. 5, a first rubbing pattern rubbed in a right direction A ′ is formed on a first alignment layer, and a second rubbing pattern rubbed in a lower direction B ′ is formed on a second alignment layer. At this time, the liquid crystal 516 is arranged according to the first rubbing pattern. That is, the liquid crystal 516 is inclined toward the right direction A ′ by the first rubbing pattern, and is inclined toward the lower direction B1 by the second rubbing pattern. The part shown with the dot in the figure shows the direction of the liquid crystal 516.

When the user views the screen from the right side A ′, the liquid crystal 516 is inclined toward the right side A ′, so that the user sees the light passing through the long axis of the liquid crystal 516. On the other hand, when the user sees the screen from the left side, the user sees the light passing through the short axis of the liquid crystal 516. At this time, the light passing through the long axis of the liquid crystal 516 has a large decrease in the amount of light as compared with the light passing through the short axis of the liquid crystal 516. Thus, a luminance difference occurs between the right side A 'and the left side A. FIG.

In order to compensate for the luminance difference, the liquid crystal display 900 includes a porous film 560. This will be described with reference to FIG. 6. However, since the lower and upper polarizers are not illustrated in FIG. 6, the description of the lower and upper polarizers will be omitted.

Referring to FIG. 6, the liquid crystal display panel 510 includes a TFT substrate 512, a color filter substrate 514, and a liquid crystal layer 516. The TFT substrate 512 is a substrate on which the TFT 512c, the pixel electrode 512d, and the first alignment layer 513 are formed. The color filter substrate 514 is provided to face the TFT substrate 512. 514a, the common electrode 514b, and the second alignment layer 515 are formed on the substrate. The liquid crystal layer 516 is formed between the TFT substrate 512 and the color filter substrate 514.

When a voltage is applied to the pixel electrode 512d and the common electrode 514b to form an electric field between the two electrodes, the amount of light incident on the liquid crystal display panel 510 is adjusted by changing the arrangement angle of the liquid crystal 516. The second light L2 having the adjusted light amount is emitted. Thereafter, the second light L2 is incident to the porous film 560. 6 illustrates a state in which the second light L2 is incident on the sidewall surface 564 of the porous film 560 and reflected at a predetermined angle. The sidewall surface 564 reflects a group having a first angle of incidence greater than the critical angle of the porous film 560 of the second light L2.

At this time, the size of the plurality of holes 565 is preferably smaller than the size of the unit pixel formed in the TFT substrate 512.

In addition, the thickness t of the porous film 560 has a value in the range of 5 μm to 100 μm. However, the thickness t of the porous film 560 may be formed wide so that the light emitted from the liquid crystal display panel 510 may sufficiently contact the sidewall surface 564, but the thickness of the liquid crystal display device 900 may be reduced. In terms of implementation, an increase in the thickness t of the porous film 510 is preferably limited as described above by bringing an increase in the thickness of the liquid crystal display device 900.

As illustrated in FIG. 6, when an electric field is formed between the pixel electrode 512d and the common electrode 514b, the long axis of the liquid crystal 516 is inclined at a predetermined angle with respect to the first direction D1. In this state, when the first light L1 is provided to the liquid crystal display panel 510, the first light L1 is controlled by the tilted liquid crystal 516 so that the amount of light is adjusted to include the second light including image information. L2) is emitted.

Here, it is assumed that the tilted liquid crystal 516 is inclined to the right side of the first direction D1. In this case, the first group L21 reflected by the first sidewall surface 564a is light emitted through the long axis of the liquid crystal 516, and the second sidewall surface 564b facing the first sidewall surface 564a. The second group L22 reflected by) may be light emitted through a short axis of the liquid crystal 516.

In this case, the first group L21 has a relatively long distance passing through the liquid crystal 516, so that the amount of light lost while passing through the liquid crystal 516 is relatively large, whereas the second group L22 passes through the liquid crystal 516. Since the distance is relatively short, the amount of light lost while passing through the liquid crystal 516 is relatively small. Therefore, the first group L21 has a smaller amount of light than the second group L22.

Here, the first group L21 is reflected by the first sidewall surface 564a so that the path is changed in a direction parallel to the long axis of the liquid crystal 515. In addition, the second group L22 is reflected by the second sidewall surface 564b so that the path is changed in a direction parallel to the short axis of the liquid crystal 516. Therefore, the luminance difference between the left and the right can be reduced.

Referring back to FIGS. 5 and 6, the first and second rubbing patterns 513a and 515a formed on the first and second alignment layers 513 and 515 rub in the first and second directions D1 and D2, respectively. As a result, the viewing angle of the liquid crystal display device 900 is expanded. Specifically, the left and right viewing angles of the liquid crystal display 900 are extended as the luminance in the white mode of the liquid crystal display 900 is increased, and the upper and lower viewing angles are decreased in the black mode of the liquid crystal display 900. It is improved by being.                     

According to this principle, since the liquid crystal display 900 includes the first and second rubbing patterns 513a and 515a facing the right side A ′ and the bottom side B ′, the luminance in the white mode is increased. In addition, since the light leakage phenomenon in the black mode of the liquid crystal display device 900 can be prevented, the luminance in the black mode is reduced. Thus, the left and right viewing angles and the up and down viewing angles of the liquid crystal display device 900 are extended.

FIG. 7A is a cross-sectional view of a liquid crystal display according to another exemplary embodiment. FIG. 7B is a perspective view of the display unit illustrated in FIG. 7A in detail.

Referring to FIG. 7A, the liquid crystal display 910 includes a display unit 500 for displaying an image and a backlight unit 600 for generating light.

The backlight unit 600 includes a lamp unit 610 for generating first light and a light guide plate 620 for guiding the first light toward the liquid crystal display panel 510. The display unit 500 includes upper and lower polarizers 590 and 570 provided at upper and lower portions of the liquid crystal display panel 510 and the liquid crystal display panel 510, respectively.

On the other hand, the liquid crystal display panel 510 is composed of a liquid crystal (not shown) injected between the TFT substrate 512, the color filter substrate 514, and the TFT substrate 512 and the color filter substrate 514.

As shown in FIG. 7B, a plurality of gate lines 512a extending in the first direction D1 and a plurality of data lines 512b extending in the second direction D2 are formed in the TFT substrate 512. do. In the TFT substrate 512, a plurality of TFTs 512c are formed in a matrix form. That is, the source electrode of the TFT 512c is connected to the data line 512b, the gate electrode of the TFT 512c is connected to the gate line 512a, and the drain electrode of the TFT 512c is the pixel electrode 512d. Is connected to.

The first alignment film 513 is entirely stacked on the TFT substrate 512 on which the TFT 512c and the pixel electrode 512d are formed. The first alignment layer 513 is a film on which a first rubbing pattern (not shown) that is rubbed in the first direction D1 is formed after the polyimide organic film is coated.

On the other hand, the color filter substrate 514 is provided to face the TFT substrate 512. The color filter substrate 514 is a substrate on which a color filter (not shown), a common electrode (not shown), and a second alignment layer 515 are formed. In this case, the second alignment layer 515 is a film having a second rubbing pattern (not shown) that is rubbed in a second direction D2 orthogonal to the first direction D1 after applying the polyimide-based organic film. .

When the TFT substrate 512 and the color filter substrate 514 are completed, the liquid crystal layer 516 is injected between the TFT substrate 512 and the color filter substrate 514.

In this case, a lower polarizing plate 570 is provided between the TFT substrate 512 and the optical sheet 630, and an upper polarizing plate 580 is provided above the color filter substrate 514.

The lower polarizer 570 is provided on the first and second surfaces of the first polarization layer 571 and the first polarization layer 571 to perform the polarization function, respectively, to support the first polarization layer 571. It consists of two support layers 572 and 573. The first polarization layer 571 is formed by adsorbing iodine or dichroic dye on the PVA layer having the first direction D1 as a transmission axis.

Meanwhile, the upper polarizer 590 includes a second polarization layer 591 which performs a polarization function, a third support layer 592 provided on the lower surface of the second polarization layer 581, and a second polarization layer 591. It has a porous layer 593 provided on the upper surface of the. The porous layer 593 is a layer in which a plurality of holes 593a are formed. The porous layer has sidewall surfaces 593b defined by a plurality of holes 593a, and the sidewall surfaces 593b are light having an extended viewing angle by partially changing the path of light incident on the upper polarizer 590. Let go.

As such, the upper polarizer 590 includes the porous layer 593 on the second polarization layer 591, thereby improving the viewing angle of the polarized light after polarizing the third light. However, the porous layer 593 may be provided on the lower surface of the second polarization layer 591. This will be described with reference to FIG. 8.

In FIG. 7B, the first rubbing pattern extends in the first direction D1 and the second rubbing pattern extends in the second direction D2, but the structure of the present invention is not limited thereto. Specifically, assuming that the first and second rubbing patterns are orthogonal, each of the first and second rubbing patterns may be formed in a direction facing up, down, left, and right when the screen of the liquid crystal display is viewed from the front. have.

Meanwhile, when the first and second rubbing patterns are changed, the directions of the first and second transmission axes respectively formed in the first and second polarization layers 571 and 591 are also changed.

8 is a cross-sectional view of a liquid crystal display according to another exemplary embodiment of the present invention.

Referring to FIG. 8, a lower polarizer 570 is provided between the TFT substrate 512 and the optical sheet 630, and an upper polarizer 595 is provided on the color filter substrate 514. The upper polarizer 595 includes a second polarization layer 596 that performs a polarization function, a porous layer 597 provided on a lower surface of the second polarization layer 596, and an upper surface of the second polarization layer 596. The third support layer 593 provided in the is provided.                     

As described above, since the porous layer 597 is provided on the lower surface of the second polarization layer 596, the third light emitted from the liquid crystal display panel 510 is expanded after the viewing angle is extended by the porous layer 597. The light is polarized by the polarizing layer 596 and emitted as the fourth light.

Hereinafter, the gray scale reversal characteristics of the liquid crystal display device 900 including the porous film 560 according to the viewing angle will be described in detail with reference to the simulation result.

9A to 9C are graphs showing simulation results of Experimental Example 1 according to the present invention, and FIGS. 10A to 10C are graphs showing simulation results of Experimental Example 2 according to the present invention. Here, Experimental Example 1 and Experimental Example 2 have a structure provided with a first and a second alignment layer having a rubbing pattern rubbed in a vertical or horizontal direction, and a porous film. Specifically, in Experimental Example 1, the pore size of the porous film is 5 μm and the thickness is 11 μm. On the other hand, in Experimental Example 2, the pore size of the porous film is 1 μm, and the thickness is 18 μm.

11A to 11C are graphs showing simulation results of Comparative Example 1, and FIGS. 12A to 12C are graphs showing simulation results of Comparative Example 2. FIGS. Here, Comparative Example 1 is a structure in which a rubbing pattern rubbed in a diagonal direction is formed on the first and second alignment layers, and Comparative Example 2 is a structure in which a rubbing pattern is formed in which the first and second alignment layers are rubbed in the vertical and horizontal directions, respectively. .

In FIGS. 9A, 10A, 11A, and 12A, the X axis represents a viewing angle [°] and the Y axis represents a contrast ratio. In addition, when the screen of the liquid crystal display device 900 is viewed from the front, it is divided into a vertical direction connecting the top and bottom, and a horizontal direction connecting the left and right. In this case, the thick solid line represents the contrast ratio according to the viewing angle in the vertical direction, and the thin solid line represents the contrast ratio according to the viewing angle in the horizontal direction.

Meanwhile, in FIGS. 9B, 9C, 10B, 10C, 11B, 11C, 12B, and 12C, the X axis is the viewing angle [°] and the Y axis is the luminance [cd / m 2]. . Specifically, FIGS. 9B, 10B, 11B, and 12B illustrate changes in luminance according to viewing angles in a horizontal direction, and FIGS. 9C, 10C, 11C, and 12C illustrate changes in luminance according to viewing angles in a vertical direction. It is shown. 9B to 12C show graphs in which 64 gray levels are divided into 8 gray levels from 1 gray level.

Referring first to FIGS. 11A and 12A, it can be seen that the contrast ratio varies depending on the viewing angle. That is, the contrast ratio is the highest at the front side, and the contrast ratio is remarkably reduced away from the front side. In particular, the farther from the front face in the vertical and horizontal directions, the lower the contrast ratio. This result causes a difference in contrast ratio in each direction.

However, referring to FIGS. 9A and 10A, the contrast ratio according to the viewing angle is almost constant, and there is almost no difference in contrast ratio between the vertical direction and the horizontal direction. In particular, in Experimental Example 2, since the pore size of the porous film is smaller than in Experimental Example 1, the contrast ratio appears more uniformly.

Referring to FIGS. 11B and 11C, not only the gray level inversion phenomenon occurs between the left side and the right side but also the left / right asymmetry does not occur. However, as the viewing angle moves away from the front, the luminance decreases despite the increase in the respective gradations, resulting in a gradation inversion phenomenon in which a high gradation has a higher luminance than a low gradation. In particular, in the vertical direction, the gray scale inversion phenomenon appears at about 24 degrees on the upper side, and the gray scale inversion phenomenon occurs at around -44 degrees on the lower side. Therefore, there is a problem that the viewing angle of the liquid crystal display device is narrowed.

12B and 12C, the upper and lower viewing angles are extended as compared with Comparative Example 1 shown in FIG. 11C. That is, it appears that the gray level inversion phenomenon in the upper and lower sides is alleviated. However, as shown in Fig. 12B, a luminance difference between left and right sides occurs. That is, left / right asymmetry occurs.

However, referring to FIGS. 9B, 9C, 10B, and 10C, even if the viewing angle is far from the front, the luminance is also increased as the gray level increases. As a result, the viewing angle of the liquid crystal display device is extended. In addition, as shown in Figs. 9B and 10B, the luminance between the left and the right becomes almost uniform, thereby appearing in left / right symmetry.

According to the liquid crystal display device described above, a lower substrate having a first alignment layer having a first rubbing pattern extending in a row direction (column direction) and a second alignment layer having a second rubbing pattern extending in a column direction (row direction) The formed upper substrate is provided. The liquid crystal layer injected between the lower substrate and the upper substrate is injected, and a porous film having a plurality of holes is disposed on the upper substrate.

Therefore, the viewing angles at the upper side and the lower side of the screen can be improved by the rubbing direction, and the luminance difference generated at the left side and the right side can be compensated.                     

Further, the rubbing length of the alignment film is shortened by forming a rubbing pattern in the alignment film in the row or column direction. Therefore, the manufacturing process of the liquid crystal display device is simplified and the manufacturing cost is reduced.

Although described with reference to the embodiments above, those skilled in the art will understand that the present invention can be variously modified and changed without departing from the spirit and scope of the invention as set forth in the claims below. Could be.

Claims (10)

A plurality of switching elements formed in a matrix form on the first substrate, a first electrode coupled to the switching elements, and a first rubbing pattern extending in a row direction (column direction) and stacked on the first substrate. A lower substrate including an alignment layer; A color filter formed on a second substrate, a second electrode formed on the color filter, and a second alignment layer stacked on the second electrode with a second rubbing pattern extending in a column direction (row direction); An upper substrate; A liquid crystal layer injected between the lower substrate and the upper substrate; And A second light disposed on the upper substrate in a state where a plurality of holes are formed, and having a luminance distribution compensated by reflecting a portion of the first light emitted from the upper substrate to the sidewall surface defining the hole; A liquid crystal display device comprising light path changing means for emitting light. The liquid crystal display of claim 1, wherein the liquid crystal is a nematic liquid crystal. The liquid crystal display device of claim 1, wherein A backlight assembly disposed under the lower substrate to generate third light; First polarization means disposed between the lower substrate and the backlight assembly to polarize the third light; And And second polarization means disposed between the upper substrate and the optical path changing means to polarize the first light. 4. The method of claim 3, wherein the first polarizing means comprises a first polarizing layer having a first transmission axis parallel to the column direction (row direction), and the second polarizing means is parallel to the row direction (column direction). And a second polarizing layer having one second transmission axis. The liquid crystal display of claim 1, wherein the optical path changing means is a porous film having a plurality of holes. The liquid crystal display of claim 5, wherein a size of each of the plurality of holes is smaller than a size of the pixel. A plurality of switching elements formed in a matrix form on the first substrate, a first electrode coupled to the switching elements, and a first rubbing pattern extending in a row direction (column direction) and stacked on the first substrate. A lower substrate including an alignment layer; A color filter formed on a second substrate, a second electrode formed on the color filter, and a second alignment layer stacked on the second electrode with a second rubbing pattern extending in a column direction (row direction); An upper substrate; A liquid crystal layer injected between the lower substrate and the upper substrate; First polarization means disposed under the lower substrate to polarize the first light provided to the lower substrate; And Liquid crystal display comprising second polarization means disposed on the upper substrate to polarize the second light emitted from the upper substrate and to emit a third light having a compensated luminance by reflecting a portion of the second light Device. The method of claim 7, wherein the first polarizing means comprises a first polarizing layer having a first transmission axis parallel to the column direction (row direction), And the second polarizing means comprises a second polarizing layer having a second transmission axis parallel to the row direction (column direction). The method of claim 8, wherein the second polarizing means, In the form of a number of holes A third light having a luminance compensated by being disposed on the second polarization layer and reflecting a part of the second light incident on the sidewall surface defining the hole after being polarized and emitted by the second polarization layer; Liquid crystal display further comprises a porous layer for exiting. The method of claim 8, wherein the second polarizing means, A plurality of holes are formed, and after reflecting a portion of the second light incident on the side wall surface defining the hole and exiting the third light having the compensated luminance, the third light is provided to the second polarizing layer. Liquid crystal display further comprises a porous layer for.

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