KR101897749B1 - Liquid crystal display device having wide viewing angle - Google Patents

Abstract

The present invention relates to a liquid crystal display device for preventing light leakage in a diagonal direction, comprising: a substrate including a plurality of pixels defined by a plurality of gate lines and data lines; A thin film transistor formed on each of the pixels; And a common electrode formed on the pixel and forming an electric field and a pixel electrode, wherein the common electrode arranged in the pixel is arranged to be symmetrically bent and bent in the pixel, and the common electrode arranged in the pixel adjacent to the pixel is arranged in the pixel And bent directions of the common electrodes formed in the pixels adjacent to each other are opposite to each other.

Description

TECHNICAL FIELD [0001] The present invention relates to a liquid crystal display (LCD)

BACKGROUND OF THE INVENTION 1. Field of the Invention [0002] The present invention relates to a liquid crystal display device, and more particularly to a wide viewing angle liquid crystal display device having a compensation film and improved viewing angle characteristics.

2. Description of the Related Art Recently, various portable electronic devices such as a mobile phone, a PDA, and a notebook computer have been developed. Accordingly, there is a growing need for a flat panel display device for a light and small size. As such flat panel display devices, a liquid crystal display (LCD), a plasma display panel (PDP), a field emission display (FED) and a vacuum fluorescent display (VFD) have been actively studied. However, Because of its implementation, liquid crystal display devices (LCDs) are now spotlighted.

Although these liquid crystal display devices have various display modes depending on the arrangement of liquid crystal molecules, liquid crystal display devices of TN mode are mainly used because of their advantages of easy monochrome display, quick response speed and low driving voltage. In such a TN mode liquid crystal display element, liquid crystal molecules aligned horizontally with the substrate are oriented substantially perpendicular to the substrate when a voltage is applied. Therefore, there is a problem that the viewing angle is narrowed when the voltage is applied due to the refractive index anisotropy of the liquid crystal molecules.

In order to solve such a viewing angle problem, liquid crystal display devices of various modes having a wide viewing angle characteristic have been proposed. Among them, liquid crystal display devices of a transverse electric field mode (In Plane Switching Mode) . The IPS mode liquid crystal display element forms at least one pair of electrodes arranged in parallel in a pixel to form a transversal electric field substantially parallel to the substrate, thereby aligning the liquid crystal molecules in a plane.

In particular, in recent years, in order to improve the contrast ratio, which is a disadvantage of the IPS mode liquid crystal display device, and to improve the switching speed, the initial liquid crystal molecules are oriented perpendicularly to the substrate, and the liquid crystal molecules are aligned horizontally A vertical IPS mode liquid crystal display element has been proposed.

FIG. 1 is a plan view of a general IPS mode liquid crystal display device, and FIG. 1 (b) is a sectional view taken along the line I-I 'of FIG. 1 (a).

As shown in Fig. 1 (a), the pixels of the liquid crystal panel 1 are defined by the gate line 3 and the data line 4 arranged vertically and horizontally. Although only the (n, m) -th and (n, m + 1) -th pixels are shown in the drawing, the actual liquid crystal panel 1 is provided with n gate lines 3 and data lines 4, m, and n x m pixels are formed over the entire liquid crystal panel 1. A thin film transistor 10 is formed in a crossing region of the gate line 3 and the data line 4 in the pixel. The thin film transistor 10 includes a gate electrode 11 to which a scanning signal is applied from a gate line 3 and a semiconductor layer which is formed on the gate electrode 11 and is activated by a scanning signal to form a channel layer And a source electrode 13 and a drain electrode 14 formed on the semiconductor layer 12 and to which an image signal is applied through the data line 4. The liquid crystal layer 40 .

In the pixel, a plurality of common electrodes 5 and pixel electrodes 7 arranged substantially in parallel with the data lines 4 are arranged. A common line 16 connected to the common electrode 5 is disposed in the middle of the pixel and a pixel electrode line 18 connected to the pixel electrode 7 is disposed on the common line 16, And overlaps with the common line 16. A storage capacitance is formed in the transverse electric field mode liquid crystal display element by overlapping the common line 16 and the pixel electrode line 18. [

The common electrode 5 and the pixel electrode 7 are bent once around the horizontal direction in the pixel. Thus, as the common electrode 5 and the pixel electrode 7 are bent once, the extension direction of the common electrode 5 and the pixel electrode 7 in the lower and upper regions with respect to the center of the pixel becomes the reference As shown in FIG.

The common electrode 5 and the common electrode 5 and the pixel electrode 7 of the pixel electrode 7 and the (n, m + 1) -th pixel of the adjacent (n, m) And the common electrode 5 and the pixel electrode 7 of all the pixels are bent in the same direction over the entire liquid crystal display element.

In the vertical IPS mode liquid crystal display device constructed as described above, the liquid crystal molecules are aligned substantially parallel to the common electrode 5 and the pixel electrode 7. [ A horizontal electric field substantially parallel to the liquid crystal panel 1 is generated between the common electrode 5 and the pixel electrode 7 when the thin film transistor 10 is operated and a signal is applied to the pixel electrode 7. [ The liquid crystal molecules are rotated in parallel with the liquid crystal panel 1 along the transverse electric field, so that the grayscale inversion due to the refractive index anisotropy of the liquid crystal molecules can be prevented.

At this time, since the common electrode 5 and the pixel electrode 7 of the pixel are bent, the directions of the transverse electric fields in the upper and lower regions are symmetrical with respect to the central region of the pixel, And symmetrically arranged in the lower region. As the liquid crystal molecules are symmetrically arranged in one pixel, the viewing angle directions in the one pixel are formed symmetrically and the viewing angles are compensated each other, thereby improving the viewing angle characteristics.

A conventional IPS mode liquid crystal display device having the above structure will be described in more detail with reference to the sectional view of FIG. 1 (b).

1 (b), a gate electrode 11 is formed on the first substrate 20, and a gate insulating layer 22 is laminated over the entire first substrate 20. A semiconductor layer 12 is formed on the gate insulating layer 22 and a source electrode 13 and a drain electrode 14 are formed thereon. A passivation layer 24 is formed on the entire surface of the first substrate 20 and a first alignment layer (not shown) is formed on the first substrate 20 to align the liquid crystal molecules in a specific direction 28a are formed.

A plurality of common electrodes 5 are formed on the first substrate 20 and a pixel electrode 7 and a data line 4 are formed on the gate insulating layer 22. The common electrode 5, A transverse electric field E is generated between the pixel electrodes 7.

On the second substrate 30, a black matrix 32 and a color filter layer 34 are formed. The black matrix 32 serves to prevent light from leaking into a region where the liquid crystal molecules do not operate. As shown in the figure, the black matrix 32 is formed between the pixel region and the pixel (that is, the gate line and the data line Region). The color filter layer 34 is formed of R (Red), B (Blue), and G (Green) to realize actual colors. An overcoat layer 36 for protecting the color filter layer 34 and improving the flatness of the substrate is formed on the color filter layer 34 and a second alignment layer 28b having an alignment direction is formed thereon have.

A liquid crystal layer 40 is formed between the first substrate 20 and the second substrate 30 to complete the liquid crystal panel 1.

As described above, in the IPS mode liquid crystal display element, a transverse electric field is generated inside the liquid crystal layer 40 by the common electrode 5 and the pixel electrode 7 formed on the substrate 20 and the gate insulating layer 22 The liquid crystal molecules in the liquid crystal layer 40 are rotated in a planar state with respect to the substrates 20 and 30, so that the grayscale inversion due to the refractive index anisotropy of the liquid crystal molecules can be prevented.

However, the IPS mode liquid crystal display device has the following problems. That is, in the IPS mode liquid crystal display element, the liquid crystal molecules rotate in parallel with the plane of the substrate along the transverse electric field, so that it is possible to prevent the grayscale inversion due to the refractive index anisotropy of the liquid crystal molecules and to improve the viewing angle characteristics in the vertical direction and in the left- But the viewing angle characteristics in the diagonal direction of the screen are not improved.

An object of the present invention is to provide a liquid crystal display element capable of minimizing light leakage in a diagonal direction by disposing the common electrodes and pixel electrodes of adjacent pixels in opposite directions to each other .

According to an aspect of the present invention, there is provided a liquid crystal display device including: a substrate including a plurality of pixels defined by a plurality of gate lines and data lines; A thin film transistor formed on each of the pixels; And a common electrode formed on the pixel and forming an electric field and a pixel electrode, wherein the common electrode arranged in the pixel is arranged to be symmetrically bent and bent in the pixel, and the common electrode arranged in the pixel adjacent to the pixel is arranged in the pixel And bent directions of the common electrodes formed in the pixels adjacent to each other are opposite to each other.

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The pixel electrodes are formed on the substrate over the entire pixel, and a plurality of common electrodes are formed in a strip shape so as to overlap the pixel electrodes with the insulating layer interposed therebetween. In this case, The common electrodes are arranged in opposite directions to each other in the pixels arranged symmetrically and adjacent to each other.

In the present invention, the arrangement of the common electrode and the pixel electrode of the adjacent pixels in the mutually opposite directions can minimize the light leakage in the diagonal direction. Further, in the present invention, since the light leakage is minimized without the addition of a compensation film or structure, it is possible to prevent the manufacturing cost from being increased or the manufacturing process from being complicated.

1A and 1B are diagrams showing the structure of a conventional liquid crystal display element.
3A is a diagram showing the absorption axes of the upper and lower polarizing plates when the liquid crystal display element is viewed from the front;
Fig. 3B is a diagram showing the absorption axes of the upper and lower polarizing plates when the liquid crystal display element is viewed diagonally. Fig.
4A and 4B are diagrams showing the structure of a liquid crystal display element according to a first embodiment of the present invention.
5 is a diagram showing a pixel structure of a liquid crystal display according to a first embodiment of the present invention.
FIG. 6 conceptually shows prevention of light leakage in the diagonal direction in the liquid crystal display according to the first embodiment of the present invention. FIG.
7A and 7B are diagrams showing the results of simulating the luminance viewing angle characteristics of the conventional liquid crystal display element and the liquid crystal display element according to the present invention in the normally white mode.
8A and 8B are diagrams showing the results of simulating the luminance viewing angle characteristics of the conventional liquid crystal display element and the liquid crystal display element according to the present invention in the normally black mode, respectively.
9A and 9B are diagrams showing results of simulating contrast ratio characteristics of a conventional liquid crystal display device and a liquid crystal display device according to the present invention, respectively.
10 is a view showing a pixel structure of a liquid crystal display element according to a second embodiment of the present invention.
11A and 11B are diagrams showing the structure of a liquid crystal display element according to a third embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the accompanying drawings.

The reason why the viewing angle characteristic is lowered in the diagonal viewing angle direction of the IPS mode liquid crystal display element is because the light leakage occurs in the diagonal direction of the IPS mode liquid crystal display element. 2, a first polarizing plate 162 and a second polarizing plate 164 are attached to upper and lower portions of a liquid crystal panel 101 in a general IPS mode liquid crystal display device, .

In the normally black mode, the polarization axes of the first polarizing plate 162 and the second polarizing plate 164 attached to the upper and lower substrates are perpendicular to each other. Therefore, the light transmitted through the first polarizing plate 162 is linearly polarized in the x-axis direction and input to the liquid crystal display element. When no signal is applied to the liquid crystal panel, the liquid crystal molecules 142 of the liquid crystal panel 101 are arranged in the x-axis direction, so that light incident on the liquid crystal panel 101 is linearly polarized along the x- Through the liquid crystal panel 101 as shown in Fig. On the other hand, the polarization axis of the second polarizing plate 164 attached to the upper substrate is absorbed entirely by the polarizing plate of the upper substrate perpendicular to the polarizing direction of the light transmitted through the liquid crystal layer, And the screen is displayed in black.

However, when the above liquid crystal display element is viewed diagonally, the polarization directions of the first polarizing plate 162 and the second polarizing plate 164 are not arranged substantially vertically. In other words, when viewed from the front of the liquid crystal display element 101, the polarization axes of the first polarizing plate 162 and the second polarizing plate 164 are vertically aligned with each other, but perpendicular to the diagonal direction.

3A shows the arrangement of the polarization axes of the first polarizing plate 162 and the second polarizing plate 164 in the light path passing through the liquid crystal display element in the front view, that is, in the direction perpendicular to the screen of the liquid crystal display element, The polarization axis of the first polarizing plate 162 and the polarizing axis of the second polarizing plate 164 in the path of the light passing through the screen of the liquid crystal display element at a constant polar angle and azimuthal angle when viewed in a diagonal direction Layout. Here, the dotted line in the figure is the direction of the polarization axis (i.e., the light absorption axis) in the first polarizing plate 162 and the solid line is the direction of the light absorption axis in the second polarizing plate 164.

3A, when the liquid crystal display element is viewed from the front (that is, when light is transmitted perpendicularly to the screen of the liquid crystal display element), the polarizing axes of the first polarizing plate 162 and the second polarizing plate 164 The first polarizing plate 162 and the second polarizing plate 162 of the liquid crystal display element when viewed in the diagonal direction (when transmitting the liquid crystal display element at a certain polar angle and azimuth angle with the screen of the liquid crystal display element) The polarization axes of the light guide plate 164 are arranged at a constant angle?

When the liquid crystal display element is viewed diagonally, the polarizing directions of the first polarizing plate 162 and the second polarizing plate 164 are not perpendicular to each other. Therefore, the first polarizing plate 162 linearly polarizes the liquid crystal panel 101, Is partially absorbed by the second polarizer plate 164 without being completely absorbed by the second polarizer plate 164. Therefore, when the liquid crystal display element is viewed in the diagonal direction even in the normally black state, a part of the light leaks and the black state can not be maintained completely.

The best way to prevent leakage of light in the diagonal direction is to improve the viewing angle characteristics in the diagonal direction by adding a separate compensation film. However, in this case, there is a problem that the cost increases due to the expensive compensation film and the thickness of the liquid crystal cell element increases.

The present invention improves viewing angle characteristics by changing the arrangement structure of the common electrode and the pixel electrode disposed in the pixel without adding a separate structure such as a compensation film or the like. Therefore, it is possible to realize a liquid crystal display device with a wide viewing angle without increasing the cost or complexity of the process.

4A and 4B are plan views showing a structure of a transverse electric field mode liquid crystal display device according to a first embodiment of the present invention. (N, m) -th pixel 150 and the (n, m + 1) -th pixel 152 adjacent to each other in the longitudinal direction for the sake of convenience of explanation Respectively.

As shown in Fig. 4A, in the transverse electric field mode liquid crystal display element 101, a plurality of gate lines 103 and data lines 104 are arranged to define a plurality of pixels. A thin film transistor 110 is formed in each pixel. The thin film transistor 110 includes a gate electrode 111 connected to the gate line 103 and receiving a scanning signal through the gate line 103 and a gate electrode 111 formed on the gate electrode 111, A source electrode 113 formed to face the semiconductor layer 112 and transmitting a signal inputted from the data line 104 through the channel, And a drain electrode 114.

In the pixel, a stripe-shaped or bar-shaped common electrode 105 having a set width and a pixel electrode 107 are arranged in parallel to form a transverse electric field parallel to the surface of the substrate. A common line 116 connected to the common electrode 105 is disposed at an upper end of the pixel and an external common signal is applied to the common electrode 105 through the common line 116. A pixel electrode line 118 electrically connected to the pixel electrode 107 is formed on the common line 116. The pixel electrode line 118 is connected to the common line 116, So that a storage capacitor is formed between the common line 116 and the pixel electrode line 118. An image signal is applied to the pixel electrode line 118 through the thin film transistor 110 and then applied to the pixel electrode 107 so that an electric field parallel to the substrate is formed between the common electrode 105 and the pixel electrode 107 .

Although not shown in the drawing, a liquid crystal layer is formed over the entire liquid crystal display element.

An electric field is formed between the common electrode 105 and the pixel electrode 107 by the voltage difference between the common voltage and the image signal applied to the common electrode 105 and the pixel electrode 107, respectively. At this time, the common electrode 105 and the pixel electrode 107 are bent once around the central region of the pixel, that is, in a direction parallel to the extending direction of the gate line 103. Accordingly, the first area 150a and the second area 150b, which are the upper area of the pixel 150 and the second area 150b, are formed symmetrically with respect to the center of the pixel to form the first area 150a and the second area 150b ) Are arranged symmetrically with respect to each other.

In the case of the first pixel 150, the common electrode 105 and the pixel electrode 107 are bent at an angle of? 1 to the left with respect to the horizontal direction. In the case of the adjacent second pixel 152, The pixel electrode 105 and the pixel electrode 107 are bent at an angle of? 2 to the right with respect to the horizontal direction. That is, the common electrode 105 and the pixel electrode 107 are bent to the left and right (or in opposite directions) at the same angle in the pixels adjacent to each other.

The common electrode 105 and the pixel electrode 107 are bent symmetrically with respect to the horizontal direction in the first region 152a and the second region 152b which are upper regions in the adjacent second pixel 152, Are arranged symmetrically with respect to each other.

The common electrode 105 of the first region 150a of the first pixel 150 and the pixel electrode 107 of the second pixel 152 adjacent to the direction of the pixel electrode 107 The direction of the common electrode 105 and the pixel electrode 107 of the second region 150b of the first pixel 150 and the direction of the common electrode 105 and the pixel electrode 107 of the first region 150b are parallel to the direction of the common electrode 105 and the pixel electrode 107 of the second region 152b, Is parallel to the direction of the common electrode 105 and the pixel electrode 107 of the first region 152a of the second pixel 152. [

That is, the directions of the common electrode 105 and the pixel electrode 107 arranged in the two adjacent regions 150b and 152a are parallel to each other with the gate line 103 sandwiched between the adjacent two pixels 150 and 152 .

As shown in Fig. 5, such a rule is repeated throughout the liquid crystal display element. That is, the common electrode 105 and the pixel electrode 107 are bent in the opposite directions at the same angle in the pixels adjacent to each other across the pixels adjacent to each other along the extending direction of the data line 104. Further, in the pixels adjacent to each other along the gate line 103, the common electrode 105 and the pixel electrode 107 are bent in the same direction

In other words, both the common electrode 105 and the pixel electrode 107 disposed on the entire pixels in the odd-numbered columns along the extending direction of the data line 104 are symmetrically bent (bent) at an angle of? And the common electrode 105 and the pixel electrode 107 disposed on the entire pixels of the even-numbered columns along the extending direction of the data line 104 are symmetrically bent at an angle of? 2 to the right with respect to the horizontal direction .

In addition, the common electrode 105 and the pixel electrode 107 arranged in the odd-numbered columns are bent in the right direction and the common electrode 105 and the pixel electrode 107 arranged in the pixels in the even-numbered columns are bent in the leftward direction It might be.

In the transverse electric field mode liquid crystal display device having the above-described structure, liquid crystal molecules are symmetrically arranged in one pixel to form two domains having different viewing angle directions, and liquid crystal molecules are arranged symmetrically in adjacent pixels, In this case, since the directions of the common electrode 103 and the pixel electrode 105 in the pixels adjacent to each other are opposite to each other, leakage of light in the diagonal viewing direction can be effectively prevented , Which will be described in more detail later.

4B is a cross-sectional view taken along line II-II 'of FIG. 4A. Referring to FIG. 4A, a cross-sectional structure of the transverse electric field mode liquid crystal display device according to the first embodiment of the present invention will be described.

As shown in FIG. 4B, a gate electrode 111 made of a conductive metal is formed on a first substrate 120 made of a transparent material such as glass or plastic. The gate electrode 111 is formed over the entire surface of the first substrate 120, A gate insulating layer 122 made of a material is stacked. A semiconductor layer 112 made of amorphous silicon or crystalline silicon is formed on the gate insulating layer 122 and a source electrode 113 and a drain electrode 114 made of metal are formed thereon.

In addition, a passivation layer 124 made of an organic material or an inorganic material is formed over the entire surface of the first substrate 120, and an orientation for orienting the liquid crystal molecules in a specific direction A first alignment layer 128a having a determined orientation is formed.

A plurality of common electrodes 105 are formed on the first substrate 120. A pixel electrode 107 is formed on the protective layer 124 to form a gap between the common electrode 105 and the pixel electrode 107. [ A transverse electric field is generated.

The common electrode 105 may be made of the same metal as the gate electrode 111 or may be made of another metal. The pixel electrode 107 may be formed of a metal having good conductivity, ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide) And the like.

The common electrode 105 may be formed on the gate insulating layer 122 or the protective layer 124 and the pixel electrode 107 may be formed on the gate insulating layer 122 or the substrate 120 .

In other words, the formation positions of the common electrode 105 and the pixel electrode 107 may not be formed only on a specific layer but may be formed on the substrate 120, the gate insulating layer 122 and the protective layer 124 . At this time, the common electrode 105 and the pixel electrode 107 may be formed in the same layer or in different layers. The common electrode 105 and the pixel electrode 107 may be formed of a metal or a transparent metal oxide and one of the common electrode 105 and the pixel electrode 107 may be formed of a metal, Or may be formed of a metal oxide.

The second substrate 130 is formed with a black matrix 132 made of Cr or CrOx or the like and a color filter layer 134 for outputting only light having a specific wavelength among incident light. The black matrix 132 prevents leakage of light to regions where liquid crystal molecules do not operate. As shown in the figure, the black matrix 132 is formed between the pixel region and the pixel (that is, the gate line and the data line Region). When the common electrode 105 and / or the pixel electrode 107 is made of metal, the common electrode 105 and / or the pixel electrode 107 can be formed in the region where the metal is formed. The color filter layer 134 is composed of R (Red), B (Blue), and G (Green) to realize actual colors. On the color filter layer 134, a second alignment film 128b whose alignment direction is determined is formed. Although not shown in the drawing, an overcoat layer may be formed on the color filter layer 134 to protect the color filter layer 134 and improve the flatness of the substrate.

A liquid crystal layer 140 is formed between the first substrate 120 and the second substrate 130 to complete the liquid crystal panel 101.

As described above, in the present invention, the common electrode 105 and the pixel electrode 107 are symmetrically bent in the pixel, and the direction in which the common electrode 105 and the pixel electrode 107 are bent is opposite to that of the adjacent pixel, Leakage can be prevented.

FIG. 6 conceptually shows prevention of light leakage in the diagonal direction in the transverse electric field mode liquid crystal display of the present invention. In FIG. 6, the liquid crystal display element has a polar angle and azimuthal angle, The dotted line in the drawing indicates the direction of the polarization axis (i.e., the light absorption axis) in the first polarizing plate, and the solid line indicates the arrangement of the light absorption axis in the second polarizing plate Direction.

6, when the liquid crystal display element is viewed diagonally, since the polarization directions of the first polarizing plate and the second polarizing plate attached to the lower portion and the upper portion of the liquid crystal display element are not perpendicular to each other in the pixels of odd rows, 1 light polarized in the first polarizer and transmitted through the liquid crystal panel is not completely absorbed by the second polarizer but partially transmitted through the second polarizer. Therefore, when light is leaked in the diagonal direction and the pixels in the odd-numbered columns are viewed in the viewing angle direction, the viewing angle characteristic becomes a trapezoid shape having a short upper-side length.

On the other hand, since the polarization directions of the first polarizing plate and the second polarizing plate attached to the lower portion and the upper portion of the liquid crystal display element are not perpendicular to each other even in the pixels in the even-numbered columns, light transmitted through the liquid- The entirety is not absorbed, and a part thereof is transmitted through the second polarizing plate. Therefore, when the light is leaked in the diagonal direction and the pixels in the even-numbered columns are viewed in the viewing angle direction, the viewing angle characteristic becomes a trapezoid shape having a shorter lower side.

Since the viewing angle characteristics in the pixels in the odd columns and the viewing angle characteristics in the pixels in the even columns are different from each other, the viewing angle characteristics are compensated for when viewing the liquid crystal display device, Is the same as viewed from the front.

7A and 7B are simulation results of luminance viewing angle characteristics of a conventional liquid crystal display device and a liquid crystal display device according to the present invention in a normally white mode, FIG. 9A and FIG. 9B are graphs showing simulation results of the contrast ratio characteristics of the conventional liquid crystal display device and the liquid crystal display device according to the present invention, respectively. FIG. 9A and FIG. 9B are simulation results of the luminance viewing angle characteristics in the normally black mode of the liquid crystal display device, Fig.

Here, the lower polarizer and the upper polarizer are arranged such that the light transmission axes thereof are orthogonal to each other, and the optical axis of the liquid crystal layer is parallel to the light transmission axis of the lower polarizer. In this case, when the white light is used, the result of simulating the characteristics of the conventional liquid crystal display device and the liquid crystal display device according to the present invention at an inclination angle in the range of 0 to 80 degrees with respect to all the long axis angles (or azimuth angles).

7A and 8A are compared with those of the liquid crystal display according to the present invention shown in FIGS. 7B and 8B. In the conventional liquid crystal display device, The luminance is asymmetrical at 45 degrees, 135 degrees, 225 degrees and 315 degrees, whereas the luminance is symmetrical at 45 degrees, 135 degrees, 225 degrees and 315 degrees in the liquid crystal display of the present invention, The light leakage phenomenon can be prevented.

9A and the liquid crystal display device according to the present invention shown in FIG. 9B are compared with each other, the light leakage at 45 degrees, 135 degrees, 225 degrees and 315 degrees corresponding to the diagonal direction of the liquid crystal display panel And the light leakage phenomenon becomes symmetrical with the other direction.

10 is a view showing a structure of a transverse electric field mode liquid crystal display element according to a second embodiment of the present invention.
As shown in Fig. 10, in the transverse electric field mode liquid crystal display element of this embodiment, the gate lines and the data lines are formed in the extending direction (i.e., the horizontal direction) of the gate lines in the pixels 250 and 252, Two regions 150a, 150b, 152a and 152b in which the common electrode and the pixel electrode are bent symmetrically with each other are formed in the horizontal direction of the gate line to compensate the viewing angle in each pixel, The common electrode and the pixel electrode of the pixel are bent in opposite directions to prevent light leakage in the diagonal direction.

In comparison with the structure of the liquid crystal display element according to the first embodiment shown in Fig. 4A of the liquid crystal display element of this structure, in the first embodiment, the common electrode and the pixel electrode are arranged in the vertical direction (i.e., the data line direction) In the present embodiment, the common electrodes and the pixel electrodes are arranged in the horizontal direction (i.e., the gate line direction) and the adjacent pixels are adjacent to each other in the horizontal direction Numbered columns and even-numbered columns are bent in different directions.

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11A and 11B are views showing a liquid crystal display according to a third embodiment of the present invention, in which FIG. 11A is a plan view and FIG. 11B is a sectional view taken along line III-III '.

11A, the liquid crystal display elements of this embodiment include a plurality of gate lines 203 and data lines 204 arranged so as to cross each other vertically and defining a plurality of pixels, a gate line 203 and data A thin film transistor 210 arranged in an intersection region of the line 204 and a pixel electrode 207 arranged at a predetermined distance from the gate line 203 and the data line 204 on the entire surface of the pixel, And a plurality of transparent common electrodes 205 disposed on the pixel electrodes 207 so as to overlap with the pixel electrodes 207 with no intervening layer therebetween.

The thin film transistor 210 includes a gate electrode 211 to which a scanning signal is applied from the outside as a part of the gate line 203, a semiconductor layer 212 formed on the gate electrode, And a source electrode 213 and a drain electrode 214 for transmitting a signal through the channel formed in the layer 212 to the inside of the pixel.
At this time, the source electrode 213 and the drain electrode 214 are disposed on the gate line 203 to minimize a drop in aperture ratio due to the source electrode 213 and the drain electrode 214. At this time, the pixel electrode 207 is electrically connected to the drain electrode 214 by the pixel electrode connection pattern 29b connected thereto.

11B, the gate electrode 211 is formed on a transparent substrate 220 such as glass, a gate insulating layer 222 is formed thereon, and a gate insulating layer 222 is formed on the gate electrode 211, A source electrode 213 and a drain electrode 214 are formed on the semiconductor layer 222 and a protective layer 224 is formed thereon.

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The pixel electrode 207 is formed over the entire pixel on the substrate 220 and the common electrode 205 is formed in a plurality of strips or rods on the protective layer 224, Drain electrode 214 and the pixel electrode connection pattern 29b connected thereto.

When an image signal is supplied to the pixel electrode 207 through the thin film transistor 210 in the liquid crystal display device having such a configuration, an electric field (this is referred to as a fringe field) is generated between the edge of the pixel electrode 207 and the common electrode 205, (hereinafter referred to as a fringe field), and the liquid crystal molecules arranged in the horizontal direction between the TFT substrate and the color filter substrate (not shown) are rotated by dielectric anisotropy.

Also, in the liquid crystal display device of this embodiment, as shown in FIG. 11A, one pixel is composed of two domains, and the common electrodes 205 arranged in the respective domains are symmetrically arranged at an angle to each other, Thereby improving the viewing angle characteristics. On the other hand, in the adjacent pixels, the common electrodes 205 constituted by two domains and arranged in the respective domains are symmetrically arranged at a certain angle to improve the viewing angle characteristics in one pixel. At this time, the arrangement of the common electrodes 205 of the pixels adjacent to each other is arranged in directions opposite to each other. That is, in the first pixel 250, the common electrode 205 of the first domain 250a is arranged in the right-upward direction with the common electrode being the center of the pixel, and the common electrode 205 of the second domain 250b is arranged in the right- The common electrode of the second pixel 252 adjacent to the first pixel 250 is formed in the shape of a gull which is arranged in the direction of the common electrode 252a of the first domain 252a with respect to the center of the pixel, And the common electrode 205 of the second domain 252b is arranged in a left-down direction and is formed into a gull-like shape where the left side is opened.

In other words, since the pixels 250 in the odd-numbered columns adjacent to each other and the common electrode 205 formed in the pixels 252 in the even-numbered columns are arranged in opposite directions to each other, leakage of light in the diagonal direction can be effectively prevented.

Although the thin film transistor having the specific structure and the common electrode and the pixel electrode in the specific arrangement are disclosed in the above detailed description, the present invention is not limited to this specific structure. An important feature of the present invention is that the odd-numbered columns and the even-numbered columns adjacent to each other when the common electrode and the pixel electrode are folded and arranged are arranged in opposite directions to each other is. Accordingly, liquid crystal display devices of any structure may be applied to the present invention, including the features of the present invention.

101: liquid crystal display element 103: gate line
104: data line 105: common electrode
107: pixel electrode 110: thin film transistor
150, 152: pixel

Claims (9)

A substrate including a plurality of pixels defined by a plurality of gate lines and a plurality of data lines perpendicular to the plurality of gate lines;
A thin film transistor formed on each of the plurality of pixels; And
A plurality of common electrodes and a plurality of pixel electrodes formed in each of the plurality of pixels to form an electric field;
A plurality of pixel electrode lines extending in the extending direction of the plurality of gate lines between the plurality of pixels and connected to each of the plurality of pixel electrodes; And
And a plurality of common electrode lines extending in the extending direction of the plurality of gate lines between the plurality of pixels and connected to each of the plurality of common electrodes and overlapping the plurality of pixel electrode lines under the plurality of pixel electrode lines Respectively,
Wherein each of the plurality of common electrodes disposed in each of the plurality of pixels has a first portion and a second portion that are at the same angle with respect to the extending direction of the plurality of gate lines or the plurality of data lines in the pixel, / RTI >
Wherein each of the plurality of common electrodes is connected such that the first portion and the second portion are in contact with each other and are bent based on the extension direction of the plurality of gate lines or the plurality of data lines,
The viewing angle of the first pixel of the plurality of pixels and the viewing angle of the second pixel adjacent to the first pixel are compensated for each other to improve the viewing angle of both the first pixel and the second pixel, Wherein a bending direction of the electrode and a bending direction of the common electrode formed on the second pixel are opposite to each other. The method according to claim 1,
Wherein the plurality of pixel electrodes are strip-shaped and arranged parallel to the plurality of common electrodes. delete 3. The method of claim 2,
And the direction of bending of the common electrode and the pixel electrode formed in the odd column pixels is opposite to the bending direction of the common electrode and the pixel electrode formed in the even column pixel. delete ◈ Claim 6 is abandoned due to the registration fee. 3. The method of claim 2,
Wherein the bending direction of the common electrode and the pixel electrode formed in the hole-performing pixel is opposite to the bending direction of the common electrode and the pixel electrode formed in the even-performing pixel. The method according to claim 1,
Wherein the plurality of pixel electrodes are formed over the plurality of pixels over the substrate,
Wherein the plurality of common electrodes are overlapped with the plurality of pixel electrodes with an insulating layer interposed therebetween in a strip shape. 8. The method of claim 7,
Wherein each of the plurality of common electrodes is arranged symmetrically with respect to a center line of the plurality of pixels at an angle with respect to the center line. 8. The method of claim 7,
And the plurality of common electrodes are arranged in directions opposite to each other in pixels adjacent to each other.

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