KR101272329B1 - Liquid crystal display - Google Patents

Abstract

The liquid crystal display according to the present invention includes a first substrate, a gate line formed on the first substrate, a data line crossing the gate line, a thin film transistor connected to the gate line and the data line, and a first small electrode. And a pixel electrode including a second small electrode and partially overlapping the data line, a storage electrode line formed on the first substrate and disposed between the first small electrode and the second small electrode and having a portion overlapping the pixel electrode. A second substrate facing the first substrate and a second substrate, the liquid crystal layer formed between the common electrode, the common electrode, and the pixel electrode having a cutout corresponding to the first small electrode and the second small electrode; The first small electrode and the second small electrode are rectangular with rounded corners.

Transmittance, Liquid Crystal Display, Small Electrode

Description

[0001] LIQUID CRYSTAL DISPLAY [0002]

1 is a layout diagram of a liquid crystal display according to an embodiment of the present invention.

FIG. 2 is a layout view of a thin film transistor array panel for the liquid crystal display of FIG. 1.

FIG. 3 is a layout view of a common electrode display panel for the liquid crystal display of FIG. 1.

4 is a cross-sectional view taken along the line IV-IV of FIG. 1.

5 is a cross-sectional view taken along the line V-V of FIG. 1.

* Description of Drawing Key Codes *

3: liquid crystal layer 9a, 9b: small electrode

11, 21: Orientation film 12, 22: Polarizing plate

31: liquid crystal molecule 27:

81, 82: contact assistant member 85: connecting member

100: thin film transistor array panel 110, 210: insulating substrate

121 and 129: gate line 124: gate electrode

131: sustain electrode line 137: extension portion

140: gate insulating film 151, 154, 157: semiconductor

163 and 165: ohmic contact member

171 and 179: data line 173: source electrode

175: drain electrode 180: protective film

181, 182, 185: contact hole

191: pixel electrode 200: common electrode display panel

210: insulating substrate 220: light blocking member

230: color filter 250: overcoat

270: common electrode

The present invention relates to a liquid crystal display device.

Liquid crystal display (LCD) is one of the most widely used flat panel display devices. Currently, two display panels are provided with a field generating electrode and a polarizer and the liquid crystal contained therebetween. Layer.

The liquid crystal molecules of the liquid crystal layer change their orientation according to the electric field generated in the liquid crystal layer due to the voltage applied to the field generating electrode, and thus the polarization of the light passing through the liquid crystal layer changes, and the polarizing plate emits the light polarization. Convert to transmittance of. Accordingly, the liquid crystal display may display a desired image by adjusting the voltage applied to the electrode generating electrode. At this time, the transmittance of light is determined by phase retardation caused by birefringence of the liquid crystal layer, and the phase retardation is determined by the difference between the refractive anisotropy of the liquid crystal layer and the gap between the two panels. Given by the product.

Among the liquid crystal display devices, one of the two display panels currently used includes a plurality of pixel electrodes, which are a kind of field generating electrodes, and a thin film transistor (TFT) for switching a voltage applied to the pixel electrodes. The other is a liquid crystal display provided with a common electrode and a color filter, which are different types of field generating electrodes.

Since the liquid crystal display is a light-receiving display device that does not emit light by itself, the light emitted from a backlight lamp provided at the rear of the liquid crystal display passes through the liquid crystal layer or receives light from outside such as natural light. The image is displayed by passing the liquid crystal layer and then reflecting the liquid crystal layer.

In the liquid crystal display, when the alignment of the liquid crystal layer is misaligned, light leakage may occur. Light leakage occurs mainly near data lines between neighboring pixel electrodes and requires a black matrix or the like.

Accordingly, an object of the present invention is to provide a liquid crystal display device capable of minimizing a decrease in transmittance due to a black matrix.

In accordance with an aspect of the present invention, a liquid crystal display device includes a first substrate, a gate line formed on the first substrate, a data line crossing the gate line, a gate line, and a thin film transistor connected to the data line. A pixel electrode connected to the transistor and including a first small electrode and a second small electrode, wherein the pixel electrode partially overlaps the data line, and is formed on the first substrate and is disposed between the first small electrode and the second small electrode, A storage electrode line having an overlapping portion, a second substrate facing the first substrate, and a common electrode formed on the second substrate and having a cutout corresponding to the first small electrode and the second small electrode; The first small electrode and the second small electrode are rectangular with rounded corners.

It may further include a light blocking member formed on the second substrate and corresponding to the thin film transistor.

The display device may further include a plurality of color filters formed under the common electrode.

The thin film transistor may include a gate electrode connected to the gate line, a semiconductor overlapping the gate electrode, a drain electrode formed on the semiconductor, and a source electrode facing the drain electrode on the semiconductor and connected to the data line.

The drain electrode may include an extension that overlaps the storage electrode line.

The first small electrode and the second small electrode are connected to each other by a connecting portion, and the connecting portion protrudes left and right from the vertical portion and the vertical portion connecting the first small electrode and the second small electrode in a line and is connected to the extension portion. It may be made of a protrusion.

The first small electrode and the second small electrode may have substantially the same area.

DETAILED DESCRIPTION Embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily practice the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

In the drawings, the thickness is enlarged to clearly represent the layers and regions. Like parts are designated with like reference numerals throughout the specification. It will be understood that when an element such as a layer, film, region, plate, or the like is referred to as being "on" another portion, it includes not only the element directly over another element, Conversely, when a part is "directly over" another part, it means that there is no other part in the middle.

Next, a liquid crystal display according to an exemplary embodiment of the present invention will be described in detail with reference to FIGS. 1 to 5.

1 is a layout view of a liquid crystal display according to an exemplary embodiment of the present invention, FIG. 2 is a layout view of a thin film transistor array panel for the liquid crystal display of FIG. 1, and FIG. 3 is a layout view of the common electrode display panel for the liquid crystal display of FIG. 1. 4 is a cross-sectional view taken along line IV-IV of FIG. 1.

1 to 5, a liquid crystal display according to an exemplary embodiment of the present invention includes a liquid crystal interposed between a thin film transistor array panel 100, a common electrode panel 200, and two display panels 100 and 200 facing each other. Layer 3.

First, the thin film transistor display panel 100 will be described.

1, 2, 4 and 5, a plurality of gate lines 121 are formed on an insulating substrate 110 made of transparent glass or plastic.

The gate line 121 transmits the gate signal and extends mainly in the horizontal direction. Each gate line 121 includes a plurality of gate electrodes 124 protruding upward and end portions 129 having a large area for connection with another layer or an external driving circuit. A gate driving circuit (not shown) for generating a gate signal may be mounted on a flexible printed circuit film (not shown) attached on the substrate 110, directly mounted on the substrate 110, And may be integrated on the substrate 110. When the gate driving circuit is integrated on the substrate 110, the gate line 121 may extend and be directly connected thereto.

The gate line 121 may be formed of a metal such as aluminum (Al), an aluminum alloy such as an aluminum alloy, a silver metal or a silver alloy, a copper metal such as copper (Cu) or a copper alloy, a molybdenum Molybdenum-based metals, chromium (Cr), tantalum (Ta), and titanium (Ti). However, they may have a multi-film structure including two conductive films (not shown) having different physical properties. One of the conductive films is made of a metal having a low resistivity, for example, an aluminum-based metal, a silver-based metal, or a copper-based metal to reduce signal delay and voltage drop. Alternatively, the other conductive film is made of a material having excellent physical, chemical and electrical contact properties with other materials, particularly indium tin oxide (ITO) and indium zinc oxide (IZO), such as molybdenum metal, chromium, tantalum and titanium. A good example of such a combination is a chromium bottom film, an aluminum (alloy) top film, an aluminum (alloy) bottom film and a molybdenum (alloy) top film. However, the gate line 121 and the storage electrode line 131 may be made of various other metals or conductors.

The side surface of the gate line 121 is inclined with respect to the surface of the substrate 110, and the inclination angle is preferably about 30 ° to about 80 °.

A gate insulating layer 140 made of silicon nitride (SiNx) or silicon oxide (SiOx) is formed on the gate line 121 and the storage electrode line 131.

On the gate insulating layer 140, a plurality of island-like semiconductors 154 and 157 made of hydrogenated amorphous silicon (amorphous silicon is abbreviated a-Si), polycrystalline silicon, or the like are formed. The island-like semiconductor 154 is located above the gate electrode 124. The island semiconductor 157 overlaps with the storage electrode line 131.

On the semiconductor 154, island-like ohmic contacts 163 and 165 are formed. The resistive contact members 163 and 165 may be made of a material such as n + hydrogenated amorphous silicon, or may be made of silicide, which is heavily doped with phosphorous n-type impurities. The island-like resistive contact members 163 and 165 are arranged on the semiconductor 154 in pairs. An island-type ohmic contact (not shown) may also be formed on the island-like semiconductor 157 overlapping the storage electrode line 131.

Side surfaces of the semiconductors 154 and 157 and the ohmic contacts 163 and 165 are also inclined with respect to the surface of the substrate 110, and the inclination angle is about 30 ° to 80 °.

A plurality of data lines 171 and a plurality of drain electrodes 175 are formed on the ohmic contacts 163 and 165 and the gate insulating layer 140.

The data line 171 transmits a data signal and extends mainly in the vertical direction and crosses the gate line 121 and the sustain electrode line 131. Each data line 171 includes a plurality of source electrodes 173 extending toward the gate electrode 124 and an end portion 179 having a large area for connection with another layer or an external driving circuit. A data driving circuit (not shown) for generating a data signal is mounted on a flexible printed circuit film (not shown) attached to the substrate 110, directly mounted on the substrate 110, or integrated in the substrate 110. Can be. When the data driving circuit is integrated on the substrate 110, the data line 171 can extend and be directly connected thereto.

The drain electrode 175 is separated from the data line 171 and faces the source electrode 173 with the gate electrode 124 as a center. The drain electrode 175 is connected by an extension part 177 and a connection part 176 that overlap the storage electrode 133. One gate electrode 124, one source electrode 173 and one drain electrode 175 constitute one thin film transistor (TFT) together with the semiconductor 154, and the channel of the thin film transistor Is formed in the semiconductor 154 between the source electrode 173 and the drain electrode 175. [

The data line 171 and the drain electrode 175 are preferably made of a refractory metal such as molybdenum, chromium, tantalum, and titanium, or an alloy thereof, and include a refractory metal film (not shown) and a low resistance conductive film. It may have a multilayer structure including (not shown). Examples of the multilayer structure include a double film of a chromium or molybdenum (alloy) lower film and an aluminum (alloy) upper film, a molybdenum (alloy) lower film, an aluminum (alloy) intermediate film and a molybdenum (alloy) upper film. However, the data line 171 and the drain electrode 175 may be made of various other metals or conductors.

It is preferable that the data line 171 and the drain electrode 175 are also inclined at an inclination angle of about 30 DEG to 80 DEG with respect to the substrate 110 surface.

The resistive contact members 163 and 165 exist only between the semiconductor 154 under the resistive contact members 163 and 165 and the data line 171 and the drain electrode 175 thereon and lower the contact resistance therebetween. The island-like semiconductors 154 and 157 are widened at portions where they meet the gate line 121 and the storage electrode line 131, thereby softening the profile of the surface, thereby preventing the data line 171 from being disconnected. The semiconductor 154 is exposed between the source electrode 173 and the drain electrode 175 as well as between the data line 171 and the drain electrode 175.

A passivation layer 180 is formed on the data line 171, the drain electrode 175, and the exposed semiconductor 154.

The protective film 180 is made of an inorganic insulating material or an organic insulating material, and its surface may be flat. Examples of the inorganic insulating material include silicon nitride and silicon oxide. The organic insulating material may have photosensitivity and its dielectric constant is preferably about 4.0 or less. However, the passivation layer 180 may have a double layer structure of the lower inorganic layer and the upper organic layer so as not to damage the exposed portion of the semiconductor 154 while maintaining excellent insulating properties of the organic layer.

In the passivation layer 180, a plurality of contact holes 182 and 185 exposing the end portion 179 and the drain electrode 175 of the data line 171 are formed, respectively, and the passivation layer 180 and the gate insulating layer are formed. A plurality of contact holes 181 exposing the end portion 129 of the gate line 121 are formed at 140.

On the passivation layer 180, a plurality of pixel electrodes 191 made of indium zinc oxide (IZO) or indium tin oxide (ITO), a plurality of connection members 85, and a plurality of contact assistants ( 81 and 82 are formed.

Each pixel electrode 191 includes a first rectangle 9a and a second rectangle 9b having rounded corners, and the first rectangle 9a and the second rectangle 9b are connected by a connection member 85. It is.

The connecting member 85 includes a vertical portion connecting the first rectangle 9a and the second square 9b and protrusions protruding left and right from the vertical portion.

The protrusion is physically and electrically connected to the extended portion 177 through the contact hole 185 and receives the data voltage from the drain electrode 175 and transfers the data voltage to the pixel electrode 191.

The pixel electrode 191 to which the data voltage is applied generates an electric field together with a common electrode 270 of the common electrode panel 200 to which a common voltage is applied to thereby apply a voltage between the two electrodes 191 and 270 The direction of the liquid crystal molecules of the liquid crystal layer 3 of the liquid crystal layer 3 is determined. The polarization of light passing through the liquid crystal layer 3 varies according to the direction of the liquid crystal molecules determined as described above. The pixel electrode 191 and the common electrode 270 form a capacitor (hereinafter referred to as a " liquid crystal capacitor ") to maintain the applied voltage even after the thin film transistor is turned off.

The interval between neighboring pixel electrodes 191 may be 4 μm to 7 μm. When the interval between the pixel electrodes 191 is 4um or more, light leakage due to disclination due to fringe fields between the pixel electrodes is reduced.

The contact assistants 81 and 82 are connected to the end portion 129 of the gate line 121 and the end portion 179 of the data line 171 through the contact holes 181 and 182, respectively. The contact assistants 81 and 82 complement and protect the adhesion between the end portion 129 of the gate line 121 and the end portion 179 of the data line 171 and the external device.

Next, the common electrode display panel 200 will be described.

1 and 3 to 5, a light blocking member 220 is formed on an insulating substrate 210 made of transparent glass, plastic, or the like. The light blocking member 220 is also called a black matrix and corresponds to the thin film transistor. A plurality of color filters 230 is also formed on the substrate, and the color filters 230 may extend in the vertical direction along the pixel electrode 191 to form a stripe. Each color filter 230 may display one of primary colors such as three primary colors of red, green, and blue.

An overcoat 250 is formed on the color filter 230. The overcoat 250 may be made of an (organic) insulator, protects the color filter 230, prevents the color filter 230 from being exposed, and provides a flat surface.

A common electrode 270 is formed on the lid 250. The common electrode 270 is preferably made of a transparent conductive conductor such as ITO or IZO.

A plurality of circular cutouts 27 are formed in the common electrode 270, and each cutout 27 corresponds to a central portion of the small electrodes 9a and 9b.

Alignment layers 11 and 21 are applied to the inner surfaces of the display panels 100 and 200, and they may be vertical alignment layers. Polarizers 12 and 22 are provided on outer surfaces of the display panels 100 and 200, and polarization axes of the two polarizers 12 and 22 are orthogonal to each other.

The liquid crystal display may further include a phase retardation film (not shown) for compensating for the delay of the liquid crystal layer 3. The liquid crystal display may also include a polarizer 12 and 22, a phase retardation film, display panels 100 and 200, and a backlight unit (not shown) for supplying light to the liquid crystal layer 3.

The liquid crystal layer 3 has a negative dielectric anisotropy and the liquid crystal molecules of the liquid crystal layer 3 are oriented such that their long axes are substantially perpendicular to the surfaces of the two display panels 100 and 200 when there is no electric field. Therefore, the incident light is blocked without passing through the orthogonal polarizers 12 and 22.

When a common voltage is applied to the common electrode 270 and a data voltage is applied to the pixel electrode 191, an electric field substantially perpendicular to the surfaces of the display panels 100 and 200 is generated. Liquid crystal molecules (not shown) attempt to change their directions so that their major axis is perpendicular to the electric field direction in response to the electric field.

The edges of the cutout portions 27 of the electric field generating electrodes 191 and 270 and the pixel electrode 191 distort the electric field to produce a horizontal component that determines the oblique direction of the liquid crystal molecules 31. [ The horizontal component of the electric field is almost perpendicular to the sides of the cutout portion 27 and the pixel electrode 191. [ Since the liquid crystal is inclined by the electric field formed by the four sides of the first small electrode 9a and the second small electrode 9b and the cutout portion 27, The diagonal direction of the liquid crystal molecules 31 increases the reference viewing angle of the liquid crystal display device.

In addition, in the exemplary embodiment of the present invention, the light blocking member is formed only at a portion corresponding to the thin film transistor, thereby increasing the transmittance of the liquid crystal display as shown in Table 1. The point divides the liquid crystal display into nine parts to represent nine measurement points, and point 5 is the center of the liquid crystal display.

Table 1 is a table showing a transmittance of a liquid crystal display according to the present invention having a pixel electrode composed of a light blocking member and a small electrode, and Table 2 is a transmittance of a liquid crystal display according to the present invention.

[Table 1]

[Table 2]

Referring to Table 1 and Table 2, when comparing the black luminance (luminance) at the point 5 it is 0.3 in the prior art or 0.31 in the present invention, it can be seen that compared with the white luminescence increased from 226 to 242.2. Therefore, it can be seen that the C / R also increased from 730.9 to 788.9.

As described above, the present invention increases the aperture ratio and transmittance of the liquid crystal display by forming the light blocking member only in a region corresponding to the thin film transistor.

In addition, the viewing angle of the liquid crystal display is increased by forming cutouts between the rectangular small electrode and the common electrode.

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

Claims (8)

The first substrate, A gate line formed on the first substrate, A data line formed on the first substrate, A thin film transistor electrically connected to the gate line and the data line, A pixel electrode connected to the thin film transistor and including a first small electrode and a second small electrode and partially overlapping the data line; A storage electrode line formed on the first substrate and disposed between the first small electrode and the second small electrode and having a portion overlapping with the pixel electrode; A second substrate facing the first substrate, A light blocking member formed on the second substrate, A common electrode formed on the second substrate and having a cutout corresponding to the first small electrode and the second small electrode, A liquid crystal layer formed between the common electrode and the pixel electrode, The thin film transistor may include a gate electrode connected to the gate line. A semiconductor overlapping the gate electrode; A drain electrode formed on the semiconductor, A source electrode facing the drain electrode on the semiconductor and connected to the data line; The drain electrode includes an extension that overlaps the sustain electrode line, The first small electrode and the second small electrode are connected to each other by a connecting portion, The connecting part includes a vertical part connecting the first small electrode and the second small electrode in a line and a protrusion part protruding left and right from the vertical part and connected to the extension part. Liquid crystal display device. In claim 1, The first small electrode and the second small electrode are rectangular with rounded corners. In claim 1, And a plurality of color filters formed under the common electrode. delete delete In claim 1, The light blocking member is positioned at a position corresponding to the gate line and the thin film transistor. In claim 1, And the first small electrode and the second small electrode have substantially the same area. In claim 1, The liquid crystal display device of which the spacing of the adjacent pixel electrode is 4-7 micrometers.

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