KR102667952B1 - Liquid crystal display device - Google Patents

Abstract

A liquid crystal display device is provided. A liquid crystal display device includes a first substrate on which a plurality of pixels are defined, a pixel electrode disposed for each pixel on the substrate, a second substrate disposed opposite to the first substrate, and the second substrate facing the first substrate. A plurality of optical patterns disposed on one side, an overcoat layer disposed on one side of the optical pattern facing the first substrate, and a liquid crystal layer disposed between the pixel electrode and the overcoat layer, wherein the pixel is one Has a domain.

Description

Liquid crystal display device {LIQUID CRYSTAL DISPLAY DEVICE}

The present invention relates to liquid crystal display devices.

A liquid crystal display device consists of two substrates on which electric field generating electrodes, such as a pixel electrode and a common electrode, are formed, and a liquid crystal layer injected between the two substrates. A voltage is applied to the electric field generating electrodes to form an electric field in the liquid crystal layer. And through this, the orientation of the liquid crystal contained in the liquid crystal layer is determined and the polarization of the incident light is controlled to display the image.

Among these liquid crystal display devices, a vertically aligned mode liquid crystal display device in which the long axis of the liquid crystal is aligned perpendicularly with respect to the upper and lower substrates in a state in which an electric field is not applied is being developed.

A vertical alignment mode liquid crystal display device may have poor side visibility compared to front visibility. Specifically, the liquid crystal display device can be viewed brighter when viewed from the side than when viewed from the front, and the greater the difference in brightness between the front and the side, the worse visibility becomes.

Therefore, a structure that can improve visibility by minimizing the difference in brightness between the front and the side in a vertical alignment mode liquid crystal display device is required.

The problem to be solved by the present invention is to provide a liquid crystal display device with improved visibility.

The problems of the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the description below.

A liquid crystal display device according to an embodiment of the present invention to solve the above problem includes a first substrate on which a plurality of pixels are defined, a pixel electrode disposed for each pixel on the substrate, and a second substrate disposed opposite to the first substrate. 2 substrates, a plurality of optical patterns disposed on one side of the second substrate facing the first substrate, an overcoat layer disposed on one side of the optical pattern facing the first substrate, between the pixel electrode and the overcoat layer and a liquid crystal layer disposed on the pixel, wherein the pixel has one domain.

In addition, the pixel includes an active area, which is an area in which light transmittance is controlled, and the pixel electrode includes a stem electrode extending along a first direction and a second direction perpendicular to the first direction, and a plurality of stem electrodes extending from the stem electrode. It may further include branch electrodes.

Additionally, the plurality of branch electrodes may extend in the same direction in an area of 80% or more of the active area.

Additionally, from a plan view, each of the plurality of optical patterns may be formed in the form of a plurality of bars arranged in parallel and spaced apart from each other.

Additionally, the direction in which the optical pattern extends may be perpendicular to the direction in which the branch electrode extends.

Additionally, an interior angle formed between the sidewall of the optical pattern and the second substrate may be 90 degrees or less.

Additionally, the direction in which the optical pattern extends may be the same as the direction in which the branch electrode extends.

Additionally, an interior angle formed between the sidewall of the optical pattern and the second substrate may be 90 degrees or more.

Additionally, from a plan view, the plurality of optical patterns may be formed as island patterns spaced apart from each other.

Additionally, the optical pattern may have any one of the shapes of a circle, ellipse, and polygon.

In addition, it further includes a data line disposed on the first substrate and extending along at least one of the first direction and the second direction, wherein the data line is disposed to overlap a portion of the stem electrode. You can.

Additionally, the refractive index of the optical pattern may be greater than the refractive index of the overcoat layer.

Additionally, one side of the overcoat layer facing the first substrate may be substantially flat.

Additionally, the plurality of optical patterns may be disposed over the entire surface of the second substrate.

Additionally, a gate line disposed on the first substrate and extending along a first direction, disposed on the first substrate, extending along a second direction perpendicular to the first direction and insulated from the gate line. It may further include a data line, and one gate line and at least two data lines may be disposed in each pixel.

In addition, it further includes a base layer disposed between the second substrate and the optical pattern, and the base layer may be made of the same material as the optical pattern.

Additionally, each pixel includes an active area, which is an area in which light transmittance is controlled, and the pixel electrode includes a stem electrode extending along a first direction and a second direction perpendicular to the first direction, and extending from the stem electrode. It may further include a plurality of branch electrodes.

In addition, from a planar view, each optical pattern is formed in the form of a plurality of rods arranged parallel to the tongue and spaced apart, the direction in which the optical pattern extends is perpendicular to the direction in which the branch electrode extends, and the side wall of the optical pattern and the interior angle formed by the second substrate may exceed 90 degrees.

In addition, from a plan view, each of the optical patterns is formed in the shape of a plurality of bars arranged in parallel and spaced apart from each other, the direction in which the optical pattern extends is perpendicular to the direction in which the branch electrode extends, and the sidewall of the optical pattern and the interior angle formed by the second substrate may be 90 degrees or less.

Additionally, the refractive index of the optical pattern may be greater than the refractive index of the overcoat layer.

Specific details of other embodiments are included in the detailed description and drawings.

According to embodiments of the present invention, a liquid crystal display device with improved visibility can be provided.

Effects according to embodiments of the present invention are not limited to the contents exemplified above, and further various effects are included in the present specification.

1 is a perspective view of a liquid crystal display device according to an embodiment.
FIG. 2 is a schematic layout diagram of the pixel shown in FIG. 1.
FIG. 3 is a cross-sectional view taken along the line indicated as Ⅰ-Ⅰ' in FIG. 2.
FIG. 4 is a schematic layout diagram of an optical layer disposed in the pixel shown in FIG. 2.
Figure 5 is a schematic cross-sectional view taken along the line indicated as II-II' in Figure 4.
FIG. 6 is a graph showing the brightness of the liquid crystal display device according to the embodiment shown in FIGS. 1 to 5 at each observation position.
FIG. 7 is a graph showing brightness at each observation position of a liquid crystal display device according to a comparative example.
8 to 10 are diagrams for explaining a method of manufacturing a liquid crystal display device according to the embodiment shown in FIGS. 1 to 5.
FIG. 11 is a cross-sectional view taken along a line corresponding to the line Ⅰ-Ⅰ′ in FIG. 2 of a liquid crystal display device according to another embodiment.
Figure 12 is a schematic layout diagram of an optical layer disposed in one pixel of a liquid crystal display device according to another embodiment.
FIG. 13 is a cross-sectional view of the liquid crystal display device according to the embodiment related to FIG. 12 taken along a line corresponding to line Ⅰ-Ⅰ′ in FIG. 2 .
FIG. 14 is a graph showing the brightness of the liquid crystal display device according to the embodiment shown in FIGS. 12 and 13 at each observation position.
FIG. 15 is a cross-sectional view taken along a line corresponding to the line Ⅰ-Ⅰ′ in FIG. 2 of a liquid crystal display device according to another embodiment.
Figure 16 is a schematic layout diagram of an optical layer disposed in one pixel of a liquid crystal display device according to another embodiment.
Figures 17 and 18 are cross-sectional views taken along the line Ⅰ-Ⅰ' in Figure 2 for different embodiments related to Figure 16.
19 to 23 are schematic layout diagrams of optical layers disposed in one pixel of a liquid crystal display device according to different embodiments.

The advantages and features of the present invention and methods for achieving them will become clear by referring to the embodiments described in detail below along with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below and will be implemented in various different forms. The present embodiments only serve to ensure that the disclosure of the present invention is complete and that common knowledge in the technical field to which the present invention pertains is not limited. It is provided to fully inform those who have the scope of the invention, and the present invention is only defined by the scope of the claims.

When an element or layer is referred to as “on” another element or layer, it includes instances where the element or layer is directly on top of or intervening with the other element. Like reference numerals refer to like elements throughout the specification.

Although first, second, etc. are used to describe various components, these components are of course not limited by these terms. These terms are merely used to distinguish one component from another. Therefore, it goes without saying that the first component mentioned below may also be a second component within the technical spirit of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the attached drawings.

1 is a perspective view of a liquid crystal display device according to an embodiment.

Referring to FIG. 1, a liquid crystal display device 1000 according to an embodiment includes a display panel 10, a gate driver (GD), a data driver (DD), a printed circuit board (PCB), and a backlight unit (BLU). do. The display panel 10 and the backlight unit BLU may have a rectangular shape with long sides in the first direction DR1 and short sides in the second direction DR2 that intersects the first direction DR1.

The backlight unit (BLU) generates light and provides the generated light to the display panel 10. The display panel 10 generates an image using light provided from a backlight unit (BLU) and emits light to provide an image.

The display panel 10 is disposed between a first display substrate 100, a second display substrate 300 facing the first display substrate 100, and between the first display substrate 100 and the second display substrate 300. It includes a liquid crystal layer 200. A plurality of pixels PX, a plurality of gate lines GL1 to GLm, and a plurality of data lines DL1 to DLn are disposed on the first display substrate 100. m and n are natural numbers. For convenience of explanation, only one pixel PX is shown in FIG. 1 , but in reality, a plurality of pixels PX may be defined on the first display substrate 100 .

The gate lines (GL1 to GLm) and data lines (DL1 to DLn) are insulated from each other and arranged to cross each other. The gate lines GL1 to GLm extend in the first direction DR1 and are connected to the gate driver GD. The data lines DL1 to DLn extend in the second direction DR2 and are connected to the data driver DD.

The pixels PX are arranged to be electrically connected to the gate lines GL1 to GLm and the data lines DL1 to DLn that intersect each other. Pixels PX may be arranged in a matrix form, but is not limited thereto.

The gate driver GD is disposed in a predetermined area adjacent to at least one of the short sides of the first display substrate 100 . The gate driver (GD) is formed simultaneously with the manufacturing process of the transistors of the pixels (PX) and is attached to the first display substrate 100 in the form of an amorphous silicon TFT gate driver circuit (ASG) or an oxide silicon TFT gate driver circuit (OSG). It can be installed.

However, the gate driver (GD) is not limited to this, and is formed of a plurality of driving chips, mounted on a flexible printed circuit board, and connected to the first display substrate 100 in a tape carrier package (TCP: Tape Carrier Package) method. You can. Additionally, the gate driver GD may be formed of a plurality of driving chips and mounted on the first display substrate 100 using a chip on glass (COG) method.

The data driver DD includes a plurality of source driver chips DIC. The source driving chips (DIC) are mounted on flexible circuit boards (FPC) and connected to a predetermined area adjacent to one of the long sides of the first display substrate 100 and a printed circuit board (PCB). That is, the data driver DD is connected to the first display substrate 100 and the printed circuit board (PCB) using a tape carrier package (TCP) method. However, the present invention is not limited to this, and the source driving chips DIC of the data driver DD may be mounted on the first display substrate 100 using a chip-on-glass method.

A timing controller (not shown) is disposed on a printed circuit board (PCB). The timing controller may be mounted on a printed circuit board (PCB) in the form of an integrated circuit chip and connected to the gate driver (GD) and the data driver (DD). The timing controller outputs a gate control signal, data control signal, and image data.

The gate driver (GD) receives a gate control signal from the timing controller through a control line (not shown). The gate driver (GD) may generate a gate signal in response to the gate control signal and sequentially output the generated gate signals. The gate signal is provided to the pixels PX in row units through the gate lines GL1 to GLm. As a result, the pixels PX can be driven row by row.

The data driver DD receives image data and data control signals from the timing controller. The data driver DD generates and outputs analog data voltages corresponding to image data in response to the data control signal. Data voltages are provided to the pixels PX through the data lines DL1 to DLn.

The pixels PX receive data voltages through the data lines DL1 through DLn in response to gate signals provided through the gate lines GL1 through GLm. The pixels PX display gray levels corresponding to data voltages, so that an image can be displayed.

The backlight unit (BLU) may be an edge type backlight unit or a direct type backlight unit.

Hereinafter, the specific structure of the pixel PX and the display panel 10 will be described.

FIG. 2 is a schematic layout diagram of the pixel shown in FIG. 1, FIG. 3 is a cross-sectional view taken along the line Ⅰ-Ⅰ' in FIG. 2, and FIG. 4 is an optical diagram disposed in the pixel shown in FIG. 2. It is a schematic layout diagram of the layer, and FIG. 5 is a schematic cross-sectional view taken along the line indicated as II-II' in FIG. 4.

More specifically, FIG. 2 shows a layout diagram of the pixel area PA, which is an area defined in the display panel 10 so that one pixel PX is arranged.

The pixel area PA includes an active area AA, which is an area that controls light provided from the backlight unit BLU to pass through the display panel 10 and exit.

Referring to FIGS. 2 to 5 , the display panel 10 according to one embodiment includes a first display substrate 100, a second display substrate 300, and a liquid crystal layer 200 disposed between them. In addition, it may further include a pair of polarizers (not shown) attached to the outer surfaces of the first display substrate 100 and the second display substrate 300 or disposed between them.

A switching element, for example, a thin film transistor 167, for changing the arrangement of liquid crystals (LC) included in the liquid crystal layer 200 is disposed on the first display substrate 100. The second display substrate 300 is a substrate disposed opposite to the first display substrate 100 .

The liquid crystal layer 200 is interposed between the first display substrate 100 and the second display substrate 300 and may include liquid crystal (LC) having dielectric anisotropy. When an electric field is applied between the first display substrate 100 and the second display substrate 300, the liquid crystal (LC) rotates in a specific direction between the first display substrate 100 and the second display substrate 300 to emit light. It can be transmitted or blocked. Here, the term rotation may mean not only that the liquid crystal (LC) actually rotates, but also that the arrangement of the liquid crystal (LC) changes due to the electric field.

Hereinafter, the first display substrate 100 will be described.

The first display substrate 100 includes a first base substrate 110 . The first base substrate 110 may be a transparent insulating substrate. For example, the first base substrate 110 may be made of a glass substrate, a quartz substrate, or a transparent resin substrate.

In some embodiments, the first base substrate 110 may be curved along one direction. In some other embodiments, the first base substrate 110 may have flexibility. That is, the first base substrate 110 may be deformed by rolling, folding, bending, etc.

A gate line 122, a gate electrode 124, and a maintenance line 126 are disposed on the first base substrate 110.

The gate line 122 transmits a gate signal that controls the thin film transistor 167. The gate line 122 may have a shape extending in the first direction DR1. Whether the thin film transistor 167 is turned on or off may be controlled in response to the voltage level of the gate signal.

The gate electrode 124 is formed in a shape that protrudes from the gate line 122 and may be physically connected to the gate line 122. The gate electrode 124 may be one component of the thin film transistor 167, which will be described later.

The maintenance line 126 is arranged to non-overlap each gate line 122. The maintenance line 126 generally extends along the second direction DR2, but when extending along the edge of the active area AA, it may also extend along the first direction DR1. The maintenance line 126 may be disposed adjacent to or partially overlaps the edge of the pixel electrode 180, which will be described later, and a predetermined capacitance may be formed between the pixel electrode 180 and the maintenance line 126. Accordingly, a sudden drop in the voltage level provided to the pixel electrode 180 can be prevented. However, if the degree of drop in the voltage level provided to the pixel electrode 180 does not adversely affect display quality or is at an acceptable level even without the maintenance line 126, the maintenance line 126 may be omitted.

The gate line 122, the gate electrode 124, and the maintenance line 126 may be made of the same material. Exemplarily, the gate line 122, the gate electrode 124, and the maintenance line 126 are made of an aluminum-based metal such as aluminum (Al) or an aluminum alloy, a silver-based metal such as silver (Ag) or a silver alloy, or copper (Cu). It may include gold-based metals such as copper alloys, molybdenum-based metals such as molybdenum (Mo) or molybdenum alloys, chromium (Cr), tantalum (Ta), and titanium (Ti). The gate line 122, the gate electrode 124, and the maintenance line 126 may have a single-layer structure, or may have a multi-layer structure including at least two conductive films with different physical properties.

A gate insulating layer 130 is disposed on the gate line 122, the gate electrode 124, and the maintenance line 126. The gate insulating layer 130 may be made of an insulating material, for example, silicon nitride or silicon oxide. The gate insulating layer 130 may have a single-layer structure, or may have a multi-layer structure including two insulating films with different physical properties.

A first semiconductor pattern 142 and a second semiconductor pattern 144 are disposed on the gate insulating layer 130.

The first semiconductor pattern 142 may at least partially overlap the gate electrode 124 . A channel may be formed in the first semiconductor pattern 142 to electrically connect the source electrode 165 and the drain electrode 166, which will be described later.

Although not shown in the drawing, an ohmic contact member may be additionally disposed on the first semiconductor pattern 142 in some embodiments. The ohmic contact member may be formed of n+ hydrogenated amorphous silicon doped with n-type impurities at a high concentration, or may be formed of silicide. The ohmic contact members may be arranged in pairs on the first semiconductor pattern 142 . The ohmic contact member may have ohmic contact characteristics between the source electrode 165, the drain electrode 166, and the first semiconductor pattern 142. When the first semiconductor pattern 142 includes an oxide semiconductor, the ohmic contact member may be omitted.

The second semiconductor pattern 144 is formed to overlap the source electrode 165 and drain electrode 166 of the data line 162, which will be described later. The second semiconductor pattern 144, the data line 162, the source electrode 165, and the drain electrode 166 may be formed using the same mask process.

The first semiconductor pattern 142 and the second semiconductor pattern 144 may be formed of amorphous silicon, polycrystalline silicon, or oxide semiconductor.

A first data line 162, a second data line 163, a source electrode 165, and a drain electrode 166 are formed on the first semiconductor pattern 142, the second semiconductor pattern 144, and the gate insulating layer 130. This is placed.

The first data line 162 and the second data line 163 may extend in the second direction DR2 and intersect the gate line 122. The first data line 162 and the second data line 163 described in this embodiment may correspond to any one of the data lines DL1 to DLn shown in FIG. 1.

The first data line 162 and the second data line 163 may be insulated from the gate line 122 and the gate electrode 124 by the gate insulating layer 130.

The first data line 162 may provide a data signal to the source electrode 165 of one pixel (PX). The second data line 162 may provide a data signal to the source electrode of another pixel (PX). The gray level of each pixel (PX) may change in response to the voltage level of the data signal.

The source electrode 165 may be branched from the first data line 162 and at least partially overlap the gate electrode 124 .

As shown in FIG. 2, the source electrode 165 is spaced apart from the drain electrode 166 at a certain distance, and the source electrode 165 may surround the drain electrode 166 in a 'U' shape. there is. However, the present invention is not limited thereto, and the source electrode 165 and the drain electrode 166 may have a rod shape arranged in parallel and spaced apart at regular intervals. That is, the source electrode 165 and the drain electrode 166 can be designed in any free shape if opposing sections are secured at a certain distance from each other.

The first data line 162, the second data line 163, the source electrode 165, and the drain electrode 166 may be made of the same material. Exemplarily, the first data line 162, the second data line 163, the source electrode 165, and the drain electrode 166 may be formed of aluminum, copper, silver molybdenum, chromium, titanium, tantalum, or an alloy thereof. You can. Additionally, they may have a multi-layer structure consisting of a lower film (not shown) made of refractory metal or the like and a low-resistance upper film (not shown) formed thereon, but are not limited to this.

The gate electrode 124, the first semiconductor pattern 142, the source electrode 165, and the drain electrode 166 may form a thin film transistor 167, which is a switching element.

A passivation layer 171 is disposed on the gate insulating layer 130 and the thin film transistor 167. The passivation layer 171 may be made of an inorganic insulating material and may be arranged to cover the thin film transistor 167. The passivation layer 171 protects the thin film transistor 167 and prevents the color filter layer 172, which will be described later, and materials contained on its top from flowing into the first semiconductor pattern 142 and the second semiconductor pattern 144. can do. In some embodiments, passivation layer 171 may be omitted.

A color filter layer 172 is disposed on the passivation layer 171. The color filter layer 172 may be a photosensitive organic composition containing a pigment for implementing color, and may include any one of red, green, or blue pigment. By way of example, the color filter layer 172 may include a plurality of color filters. Exemplarily, one of the plurality of color filters may display one of primary colors such as red, green, and blue. However, the present invention is not limited to this, and the plurality of color filters may display any one of cyan, magenta, yellow, and white colors.

A planarization layer 173 is disposed on the color filter layer 172. The planarization layer 173 may be made of an insulating material, and for example, may be an organic film made of an organic material. The planarization layer 173 can flatten local steps caused by components disposed between the planarization layer 173 and the first base substrate 110. In other words, the top surface of the planarization layer 173 may be substantially flat. However, in some embodiments, the upper part of the color filter layer 172 may be formed substantially flat, so that the separate planarization layer 173 may be omitted. Additionally, in some embodiments, components to be described later may be stacked without flattening the top of the color filter layer 172.

The passivation layer 171, the color filter layer 172, and the planarization layer 173 have a portion of the thin film transistor 167, more specifically, a portion of the drain electrode 166 perpendicular to the upper surface of the first base substrate 110. A contact hole (CNT) may be formed that is exposed upward along one direction. The contact hole (CNT) may be formed in a shape that penetrates the passivation layer 171, the color filter layer 172, and the planarization layer 174.

A pixel electrode 180 is disposed on the planarization layer 174. The pixel electrode 180 is physically connected to the drain electrode 166 through a contact hole (CNT), and can receive the data voltage from the drain electrode 166.

The pixel electrode 180 may be made of a transparent conductive material such as Indium Tin Oxide (ITO), Indium Zinc Oxide (IZO), Indium Tin Zinc Oxide (ITZO), or Al-doped Zinc Oxide (AZO).

The pixel electrode 180 may be generally disposed within the active area AA, but may include an area expanded to overlap the contact hole CNT for connection to the drain electrode 166.

The pixel electrode 180 includes a stem electrode 181, a branch electrode 182, and an expansion electrode 183. Furthermore, a slit SL is formed between the opposing branch electrodes 182 and is an opening in which no transparent conductive material is disposed. A regular pattern is formed on the pixel electrode 180 by the slit SL, and the direction and degree to which the liquid crystal 210, which is disposed to overlap the pixel electrode 180, is tilted according to the shape and pattern of the pixel electrode 180. can be controlled.

Each component constituting the pixel electrode 180 may be placed within the active area AA. However, as described above, as an exception, the expansion electrode 183 may be placed outside the active area AA.

The stem electrode 181 may include both a section extending along the first direction DR1 and a section extending along the second direction DR2. In this embodiment, the stem electrode 181 exemplifies a structure extending along the edge of the active area AA. In general, the liquid crystals (LC) are inclined toward the direction in which the stem electrodes are disposed, so collisions between the liquid crystals (LCs) may occur in the stem electrodes 181, creating a texture. Accordingly, by arranging the stem electrode 181 to extend along the edge of the active area AA rather than across the center, a decrease in transmittance due to the stem electrode 181 can be minimized.

Furthermore, in the case of some sections of the stem electrode 181, more specifically, some sections extending in the same direction as the direction in which the data lines 162 and 163 extend, the transmittance is increased by overlapping with the data lines 162 and 163. The reduction can be minimized. In the case of this embodiment, the stem electrode 181 is arranged to overlap a portion of the section extending along the second direction DR2 with the data line 162, thereby minimizing the decrease in transmittance due to the stem electrode 181. .

The plurality of branch electrodes 182 are inclined in both the first direction DR1 and the second direction DR2 from the stem electrode 181, that is, in both the first direction DR1 and the second direction DR2. Each may extend in a non-parallel direction.

In particular, each branch electrode 182 may extend in the same direction. In the case of this embodiment, a structure in which the branch electrodes 182 extend in a direction toward the bottom right from the viewpoint of FIG. 2 is illustrated. In this way, when the branch electrodes 182 are formed to extend in the same direction, the slits SL formed between the branch electrodes 182 are also formed to extend in one direction. Since the branch electrodes 182 are disposed over most of the active area AA, the liquid crystals LC in the active area AA may be inclined toward the same direction. In this embodiment, the liquid crystals disposed in the active area AA are generally parallel to the direction in which the branch electrodes 182 extend and face the direction in which the stem electrode 181 is disposed, that is, at the viewpoint of FIG. 2. , it can be tilted in a direction toward the upper left.

Here, the fact that each branch electrode 182 extends in the same direction means that within the active area AA, the branch electrode 182 disposed in 80% or more of the area where the branch electrode 182 is disposed is It will be defined as a case where they extend in the same direction. In particular, when the branch electrodes 182 extend in the same direction, the corresponding pixel PX may be defined as having one domain. That is, even if the direction in which the branch electrode 182 extends is partially different in a part of the branch electrode 182, eg, less than 20% of the area where the branch electrode 182 is disposed, the remaining 80% of the area is If the extension direction of the branch electrodes 182 disposed in the corresponding pixel area PA extends in the same direction, the corresponding pixel PX is one domain. It can be seen as having .

In this way, when the corresponding pixel (PX) has one domain, the liquid crystals (LC) are controlled to be tilted in one direction over most of the active area (AA), so collisions between liquid crystals (LC) are minimized and the texture is improved. Occurrence can be minimized. Accordingly, the transmittance of the corresponding pixel PX may be improved, and the transmittance of the liquid crystal display device 1000 may be improved.

The expansion electrode 183 is arranged to protrude outside the active area AA. The expansion electrode 183 may be connected to the stem electrode 181 or the branch electrode 182 and may be formed to polymerize with the contact hole (CNT). The expansion electrode 183 can be physically connected to the drain electrode 166 through a contact hole (CNT) and can receive a data signal. The data signal provided to the expansion electrode 183 may be transmitted to the stem electrode 181 and the branch electrode 182 constituting the pixel electrode 180 through the expansion electrode 183.

Meanwhile, a first alignment layer (not shown) may be additionally disposed on the pixel electrode 180. The first alignment layer can control the initial alignment angle of the liquid crystal (LC) included in the liquid crystal layer 200. In some embodiments, the first alignment layer may be omitted.

Hereinafter, the second display substrate 300 will be described.

The second display substrate 300 includes a second base substrate 310, an optical pattern 322, a first overcoat layer 324, a light blocking member 330, a second overcoat layer 340, and a common electrode 350. Includes.

The second base substrate 310 is disposed opposite to the first base substrate 110. The second base substrate 310 may be durable enough to withstand external shock. The second base substrate 310 may be a transparent insulating substrate. For example, the second base substrate 310 may be made of a glass substrate, a quartz substrate, or a transparent resin substrate. The second base substrate 310 may have a flat plate shape, but may also be curved in a specific direction.

A plurality of optical patterns 322 are disposed on one side of the second base substrate 310 facing the first display substrate 100, and a first overcoat layer ( 324) is placed.

The optical patterns 322 are disposed on the front surface of the first display substrate 100, and a plurality of optical patterns 322 may be formed in a direction from the first display substrate 100 to the second base substrate 310.

The first overcoat layer 324 can flatten the steps formed by the optical patterns 322. Accordingly, at the viewpoint of FIG. 3, the lower surface of the optical patterns 322 may be substantially flat.

By the optical patterns 322 and the first overcoat layer 324, the light provided from the backlight unit (BLU) incident from the bottom is diffused at the boundary between the optical patterns 322 and the first overcoat layer 324. The angle of exit of light is expanded more than the angle of incidence of light.

Light passing through the boundary between the optical patterns 322 and the first overcoat layer 324 may travel in various directions, thereby expanding the viewing angle and improving visibility.

As described above, in this embodiment, each pixel may include only one domain. In this case, the liquid crystal (LC) disposed in the active area (AA) may be controlled to be tilted generally along one direction, which may be detrimental to visibility. That is, differences in brightness may occur depending on the direction or angle from which the liquid crystal display device 1000 is viewed.

However, light may be diffused at the boundary between the optical patterns 322 and the first overcoat layer 324 due to the difference in refractive index between the two layers and the inclined sidewall of the optical pattern 322. Accordingly, visibility can be improved. As a result, each pixel PX includes only one domain, thereby improving transmittance and improving visibility by additionally disposing the optical patterns 322 and the first overcoat layer 324.

Here, the refractive index of the material constituting the optical patterns 322 may be relatively greater than the refractive index of the material constituting the first overcoat layer 324. Exemplarily, the refractive index of the optical patterns 322 may be 1.8 or more and 2.0 or less, and the refractive index of the first overcoat layer 324 may be 1.6 or less.

As shown in FIG. 4 , the optical patterns 322 may be arranged parallel to each other in the form of bars extending diagonally in the first direction DR1 and the second direction DR2. At the same time, the direction in which each optical pattern 322 extends may intersect the direction in which the branch electrodes 182 extend.

In particular, the direction in which each optical pattern 322 extends may be perpendicular to the direction in which the branch electrodes 182 extend. At the same time, as shown in FIG. 5, when the length dt1 of the upper side of the optical pattern 322 is longer than the length dt2 of the lower side, the effect of improving visibility by the optical patterns 322 can be maximized. In other words, when the taper angle θ1, which is an internal angle formed by the sidewall of the optical pattern 322 and the second base substrate 310, is 90 degrees or less, the effect of improving visibility can be maximized.

Here, the length (dt1) of the upper side of the optical pattern 322 refers to the width of the upper surface measured in the direction perpendicular to the extending direction of each optical pattern 322, and the length of the lower side of the optical pattern 322 (dt2) may mean the width of the lower surface measured in a direction perpendicular to the direction in which each optical pattern 322 extends.

For example, the length dt1 of the upper side of the optical pattern 322 may be 2㎛ to 10㎛, and the length dt2 of the lower side of the optical pattern 322 is within a range smaller than the length dt1 of the upper side. can be decided. Additionally, the height dt3 of the optical pattern 322 may be 0.5 μm to 5 μm, and the distance dt4 between the optical patterns 322 may be 0.3 μm to 3 μm.

The optical patterns 322 may be formed of an inorganic insulating material, such as silicon nitride (SiNx) or silicon oxide (SiOx). However, the material is not limited to this, and of course, if it can form the shape of the optical pattern 322 and has the property of transmitting light, it can be used as a constituent material of the optical patterns 322.

The first overcoat layer 324 may be formed of an organic insulating material capable of flattening steps formed in the optical patterns 322 .

A light blocking member 330 is disposed on one side of the first overcoat layer 324 facing the first display substrate 100. The light blocking member 330 is disposed to overlap the gate line 122, data lines 162, 163, thin film transistor 167, and contact hole (CNT), that is, to overlap areas other than the active area (AA). and can block the transmission of light in areas other than the active area (AA).

A second overcoat layer 340 is disposed on one surface of the light blocking member 330 facing the first display substrate 100 . The second overcoat layer 340 can alleviate the level difference caused by the light blocking member 330. In some embodiments, the second overcoat layer 340 may be omitted.

A common electrode 350 is disposed on one surface of the overcoat layer 340 facing the first display substrate 100 .

The common electrode 350 may be made of a transparent conductive material such as indium tin oxide (ITO), indium zinc oxide (IZO), indium tin zinc oxide (ITZO), or Al-doped zinc oxide (AZO).

The common electrode 350 may be formed as a solid plate over the entire surface of the second base substrate 310 . A common signal provided from the outside is applied to the common electrode 350 to form an electric field in the liquid crystal layer 200 together with the pixel electrode 180.

Here, the difference between the voltage levels of the common signal and the data signal can be controlled as intended. Accordingly, an electric field that controls the slope of the liquid crystal (LC) may be formed in the space between the pixel electrode 180 and the common electrode 350 arranged to overlap each other.

Meanwhile, a second alignment layer (not shown) may be additionally disposed on one side of the common electrode 350 facing the first display substrate 100. The second alignment layer can control the initial alignment angle of the liquid crystal (LC) included in the liquid crystal layer 200. In some embodiments, the second alignment layer may be omitted.

Hereinafter, the liquid crystal layer 200 will be described.

The liquid crystal layer 200 includes a plurality of liquid crystals (LC) having dielectric anisotropy and refractive index anisotropy. The liquid crystal LC may be arranged in a direction perpendicular to the first display substrate 100 and the second display substrate 300 in a state in which an electric field is not formed in the liquid crystal layer 200. When an electric field is formed between the first display substrate 100 and the second display substrate 300, the liquid crystal (LC) rotates or tilts in a specific direction between the first display substrate 100 and the second display substrate 300. This can change the polarization of light.

Hereinafter, the visibility and transmittance improvement effects of the liquid crystal display device according to the present invention will be described.

FIG. 6 is a graph showing the brightness at each observation position of the liquid crystal display device according to the embodiment shown in FIGS. 1 to 5, and FIG. 7 is a graph showing the brightness at each observation position of the liquid crystal display device according to the comparative example. .

The comparative example shown in FIG. 7 is a liquid crystal display device in which optical patterns (322 in FIG. 3 ) are omitted from each configuration of the liquid crystal display device according to the embodiment shown in FIGS. 1 to 5 .

In the graphs of FIGS. 6 and 7, angles of 0 degrees to 360 degrees indicated along the outside of the outermost circle indicated by a dotted line mean the observation direction of the liquid crystal display devices, and angles of 0 degrees to 360 degrees indicated to correspond to each circle indicated by a dotted line. Angles of 90 degrees refer to the observation angle of the liquid crystal display device. In addition, in the graphs of FIGS. 6 and 7, if the maximum value of brightness observed after displaying a specific image on the liquid crystal display device is assumed to be 100%, the first area A1 is observed with a brightness of 75 to 100%. The second area (A2) refers to the area observed with a brightness of 50 to 75%, the third area (A3) refers to the area observed with a brightness of 25 to 50%, and the fourth area (A3) refers to the area observed with a brightness of 25 to 50%. The area shall mean the area observed with a brightness of 0 to 25%.

When comparing the graphs of FIGS. 6 and 7, each of the first to fourth areas shown in FIG. 6 (A1 to A4 in FIG. 6) is the same as each of the first to fourth areas shown in FIG. 7 (A1 to A4 in FIG. 6). It can be seen that it is closer to the original shape than A1~A4) in . In other words, in the case of the liquid crystal display device 1000 according to an embodiment of the present invention, which is an embodiment related to the graph shown in FIG. 6, the observation direction is better than the liquid crystal display device according to the comparative embodiment related to the graph shown in FIG. 7. It can be seen that the brightness deviation for each observation angle is small. That is, it can be confirmed that the liquid crystal display device 1000 according to an embodiment of the present invention including optical patterns (322 in FIG. 3) has better visibility than the liquid crystal display device according to the comparative example.

Hereinafter, a method of manufacturing the optical patterns 322 of the liquid crystal display device 1000 according to the embodiment shown in FIGS. 1 to 5 will be described.

8 to 10 are diagrams for explaining a method of manufacturing a liquid crystal display device according to the embodiment shown in FIGS. 1 to 5.

For convenience of explanation, the manufacturing method of the optical pattern 322 is explained in FIGS. 8 to 10 using cross-sections corresponding to the cross-section of the line shown as II-II' in FIG. 4.

First, referring to FIG. 8, a second base substrate 310 is prepared. An optical pattern material layer 325 is disposed on the prepared second base substrate 310. As described above, the optical pattern material layer 325 may be formed of an inorganic insulating material such as silicon nitride (SiNx) or silicon oxide (SiOx). Next, a photoresist material layer 326 is applied on the optical pattern material layer 325.

Next, referring to FIG. 9, after placing a photo mask (MA) on the photoresist material layer 326, the area corresponding to the space between the optical patterns (322 in FIG. 3) to be formed later is exposed. . Here, the photosensitive resin used to form a pattern on the photoresist material layer 326 may be a positive type. However, of course, it may not be limited thereto.

Next, referring to FIG. 10, the exposed photoresist material layer 326 is removed using a developer, and the optical pattern material layer 325 exposed at the top is removed through a dry etching process, thereby forming the optical pattern 322. ) is formed. Here, the inclination of the sidewall of the optical pattern 322 can be adjusted by controlling the time required for the dry etching process. For example, as the time required for the dry etching process increases, the sidewalls of the optical pattern 322 may be formed closer to a direction perpendicular to the plane on which the second base substrate 310 is disposed.

Furthermore, if the process is continued even after the sidewalls of the optical pattern 322 are removed perpendicular to the plane on which the second base substrate 310 is disposed, the sidewalls of the optical pattern 322 may be formed to have a reverse slope. The optical pattern 322 of this shape will be described later.

Finally, the optical pattern 322 is formed by removing the remaining photoresist material layer 326, and the first overcoat layer 324 is applied on top of the optical pattern 322 to form a pattern that diffuses light. You can.

FIG. 11 is a cross-sectional view taken along a line corresponding to the line Ⅰ-Ⅰ′ in FIG. 2 of a liquid crystal display device according to another embodiment.

Hereinafter, among the descriptions of configurations and reference numerals overlapping with those described in FIGS. 1 to 5 in each drawing, different features will be newly described, but identical features will be omitted.

Referring to FIG. 11 , the display panel 10 according to this embodiment includes a first display substrate 100, a liquid crystal layer 200, and a third display substrate 300. However, unlike the embodiments shown in FIGS. 1 to 5 , the third display substrate 300 further includes a base layer 323 made of the same material as the optical pattern 322.

FIG. 12 is a schematic layout diagram of an optical layer disposed in one pixel of a liquid crystal display device according to another embodiment, and FIG. 13 shows the liquid crystal display device according to the embodiment related to FIG. 12 as Ⅰ-Ⅰ′ of FIG. 2. It is a cross-sectional view cut along the line corresponding to the drawn line.

Referring to FIGS. 12 and 13 , the display panel 10 according to this embodiment includes a first display substrate 100, a liquid crystal layer 200, and a third display substrate 300. However, unlike the embodiments shown in FIGS. 1 to 5 , the third display substrate 300 includes optical patterns 322 with a taper angle θ1 greater than 90 degrees.

That is, based on the viewpoint of FIG. 13, the length of the upper side of the optical pattern 322 is shorter than the length of the lower side.

At the same time, the direction in which each optical pattern 322 extends may be the same as the direction in which the branch electrodes 182 extend.

When this condition is satisfied, in other words, the taper angle θ1 of the optical patterns 322 is greater than 90 degrees, and the direction in which the optical patterns 322 extend is the same as the direction in which the branch electrodes 182 extend. In the same case, the visibility improvement effect can be maximized. Additional reference is made to FIG. 14 for explanation of this effect.

FIG. 14 is a graph showing the brightness of the liquid crystal display device according to the embodiment shown in FIGS. 12 and 13 at each observation position.

When comparing the graph of FIG. 14 and FIG. 7, which is data according to the above-described comparative example, each of the first to fourth areas (A1 to A4 in FIG. 14) shown in FIG. It can be seen that it is closer to a circular shape than the first to fourth areas (A1 to A4 in FIG. 7). Therefore, in the case of the liquid crystal display device 1000 according to the embodiment shown in FIGS. 12 and 13, the brightness deviation by observation direction and observation angle is higher than that of the liquid crystal display device according to the comparative embodiment related to the graph shown in FIG. 7. You can check small things. That is, it can be confirmed that the liquid crystal display device 1000 according to the embodiment shown in FIGS. 12 and 13 has better visibility than the liquid crystal display device according to the comparative example.

Furthermore, compared to the graph shown in FIG. 6, it can be seen that the first area (A1 in FIG. 14) occupies a larger proportion compared to the entire area. Accordingly, compared to the liquid crystal display device 1000 according to the embodiment shown in FIGS. 1 to 5, it can be confirmed that the transmittance of the liquid crystal display device 1000 according to the embodiment shown in FIGS. 12 and 13 is relatively improved. You can.

FIG. 15 is a cross-sectional view taken along a line corresponding to the line Ⅰ-Ⅰ′ in FIG. 2 of a liquid crystal display device according to another embodiment.

Referring to FIG. 15 , the display panel 10 according to this embodiment includes a first display substrate 100, a liquid crystal layer 200, and a third display substrate 300. However, unlike the embodiment according to FIGS. 12 and 13, the third display substrate 300 further includes a base layer 323 made of the same material as the optical pattern 322.

FIG. 16 is a schematic layout diagram of an optical layer disposed in one pixel of a liquid crystal display device according to another embodiment, and FIGS. 17 and 18 are indicated by Ⅰ-Ⅰ′ of FIG. 2 for other embodiments related to FIG. 16, respectively. This is a cross-sectional view cut along the line shown.

Referring to FIGS. 16 and 17 , the display panel 10 according to this embodiment includes a first display substrate 100, a liquid crystal layer 200, and a third display substrate 300. However, unlike the embodiments according to FIGS. 1 to 5, the embodiments of FIGS. 1 to 5 have a bar shape in that the optical patterns 322 have a dot-shaped arrangement separated from each other. It has differences from the optical patterns 322 according to .

More specifically, the optical patterns 322 may each have a separate circular shape, and they may be arranged in a matrix form. Additionally, each of the optical patterns 322 may have a curved cross section with a taper angle θ1 less than 90 degrees.

Next, referring to FIGS. 16 and 18 , each of the optical patterns 322 may have a curved cross section with a taper angle θ1 greater than 90 degrees.

19 to 23 are schematic layout diagrams of optical layers disposed in one pixel of a liquid crystal display device according to different embodiments.

Referring to FIG. 19 , the optical patterns 322 may be the same as the embodiment shown in FIG. 16 in that each of the optical patterns 322 has a separate circular shape. However, the optical patterns 322 according to the embodiment shown in FIG. 19 are different from the embodiment shown in FIG. 16 in that they are not arranged in a matrix form, but in a staggered form. In this case, since the spacing between each optical pattern 322 is constant, light can be diffused more uniformly, thereby maximizing the effect of improving visibility.

Referring to FIG. 20, each of the optical patterns 322 has an oval shape, which is different from the embodiment shown in FIG. 16.

Referring to FIG. 21 , each of the optical patterns 322 may be the same as the embodiment shown in FIG. 20 in that each has an elliptical shape. However, the optical patterns 322 according to the embodiment shown in FIG. 21 are different from the embodiment shown in FIG. 20 in that they are not arranged in a matrix form, but in a staggered form. In this case, since the spacing between each optical pattern 322 is constant, light can be diffused more uniformly, thereby maximizing the effect of improving visibility.

Referring to FIG. 22, each of the optical patterns 322 has a polygonal shape, which is different from the embodiment shown in FIG. 16. In particular, the optical patterns 322 according to the embodiment shown in FIG. 22 may have a regular octagonal shape.

Referring to FIG. 23, each of the optical patterns 322 may be the same as the embodiment shown in FIG. 22 in that each has a polygonal shape. However, the optical patterns 322 according to the embodiment shown in FIG. 23 are different from the embodiment shown in FIG. 22 in that they are not arranged in a matrix form, but in a staggered form. In this case, since the spacing between each optical pattern 322 is constant, light can be diffused more uniformly, thereby maximizing the effect of improving visibility.

Although embodiments of the present invention have been described above with reference to the attached drawings, those skilled in the art will understand that the present invention can be implemented in other specific forms without changing its technical idea or essential features. You will be able to understand it. Therefore, the embodiments described above should be understood in all respects as illustrative and not restrictive.

1000: liquid crystal display device
10: Display panel
100: first display substrate
180: Pixel electrode
200: liquid crystal layer
300: second display substrate
322: Optical pattern
324: Overcoat layer

Claims (20)

first substrate;
a data line located on the first substrate and extending in one direction;
a pixel electrode disposed on the substrate;
a second substrate disposed opposite the first substrate;
a plurality of optical patterns disposed on one surface of the second substrate facing the first substrate;
an overcoat layer disposed on one side of the optical pattern facing the first substrate;
A liquid crystal layer disposed between the pixel electrode and the overcoat layer,
The pixel has one domain,
The pixel electrode includes a stem electrode extending along a first direction and a second direction perpendicular to the first direction, and a plurality of stem electrodes extending from the stem electrode and extending in a third direction different from the first direction and the second direction. It includes two electrodes,
Each of the plurality of optical patterns extends in an inclined direction with respect to the extension direction of the data line,
A liquid crystal display device in which each of the plurality of optical patterns extends in the same direction as the third direction or in a direction perpendicular to the third direction. According to claim 1,
The pixel is a liquid crystal display device including an active area, which is an area where light transmittance is controlled. According to clause 2,
The plurality of branch electrodes extend in the same direction in an area of 80% or more of the active area. According to clause 2,
A liquid crystal display device in which, when viewed from a plan view, each of the plurality of optical patterns is formed in the form of a bar arranged in parallel and spaced apart from each other. delete According to clause 4,
An interior angle formed between a sidewall of the optical pattern and the second substrate is 90 degrees or less. delete According to clause 4,
An interior angle formed between a sidewall of the optical pattern and the second substrate is greater than 90 degrees. delete delete According to clause 2,
The data line extends along at least one of the first direction and the second direction,
The data line is arranged to overlap a portion of the stem electrode. According to claim 1,
A liquid crystal display device wherein the refractive index of the optical pattern is greater than the refractive index of the overcoat layer. According to claim 1,
A liquid crystal display device wherein one side of the overcoat layer facing the first substrate is substantially flat. According to claim 1,
The plurality of optical patterns are disposed over the entire surface of the second substrate. According to claim 1,
a gate line disposed on the first substrate and extending along a first direction; It further includes,
The data line extends along a second direction perpendicular to the first direction and is insulated from the gate line,
A liquid crystal display device in which one gate line and at least two data lines are disposed in each pixel. According to claim 1,
Further comprising a base layer disposed in a layer between the second substrate and the optical pattern,
The base layer is a liquid crystal display device made of the same material as the optical pattern. delete According to claim 16,
From a planar view, each of the optical patterns is formed in the form of a plurality of bars arranged in parallel and spaced apart from each other,
A liquid crystal display device wherein an interior angle formed between a sidewall of the optical pattern and the second substrate exceeds 90 degrees. According to claim 16,
From a planar view, each of the optical patterns is formed in the form of a plurality of bars arranged in parallel and spaced apart from each other,
An interior angle formed between a sidewall of the optical pattern and the second substrate is 90 degrees or less. According to claim 16,
A liquid crystal display device wherein the refractive index of the optical pattern is greater than the refractive index of the overcoat layer.

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