KR20020002669A - In plane field switching mode lcd and method for manufactring the same - Google Patents

Abstract

The present invention discloses an IPS-LCD and a method of manufacturing the same, which can prevent color shift even in a halftone state. The disclosed invention is disposed at a predetermined distance, the upper and lower substrates the unit pixel is limited; A liquid crystal layer comprising several liquid crystal molecules interposed between the upper and lower substrates; A counter electrode formed on each unit pixel of the lower substrate; A pixel electrode which generates an inflen field together with the counter electrode to operate most liquid crystal molecules in a unit pixel; A first horizontal alignment layer formed on an inner surface of the lower substrate and having a predetermined alignment axis; And a second horizontal alignment layer formed on an inner surface of the upper substrate, the second horizontal alignment layer having an alignment axis that is non-parallel to the alignment axis of the first horizontal alignment layer, wherein the counter electrode and the pixel electrode are formed in two directions symmetrical in the unit pixel. A first alignment layer portion of the region where the first influenza field and the second inflation field are formed, the first alignment layer portion of the region in which the first influenza field is formed has a first axis of orientation, and the first in the region where the second inflation field is formed. The alignment layer portion has a second alignment axis that is symmetrical with the first alignment axis, and either one of the first alignment axis and the second alignment axis forms a predetermined angle with the first influenza field.

Description

INFLNE FIELD SWITCHING MODE LCD AND METHOD FOR MANUFACTRING THE SAME}

The present invention relates to an in-plane field switching mode LCD (hereinafter referred to as IPS-LCD) and a method of manufacturing the same. More specifically, the present invention relates to an IPS-LCD having a perfectly symmetrical viewing angle even in a medium gray scale state. And to a method for producing the same.

In recent years, LCDs have characteristics such as light weight, thinness, and low power consumption, and are used in terminals or video equipment of various information equipment. Typical driving methods of such LCDs include TN (twist nematic) and STN (super twist nematic) modes. However, although TN-LCD and STN-LCD have been put to practical use, there is a problem that the viewing angle is very narrow.

In order to solve this problem, a conventional IPS-LCD has been proposed.

As shown in FIG. 1, a plurality of gate bus lines 11 are arranged on the lower insulating substrate 10 in parallel with each other in the x direction of the drawing, and the plurality of data bus lines 15 are substantially in the x direction. It is arranged parallel to each other in the vertical y direction, thereby defining the unit pixel space. In this case, a pair of gate bus lines 11 and a pair of data bus lines 15 are illustrated to show one unit pixel space. Here, the gate bus line 11 and the data bus line 15 are insulated with a gate insulating film (not shown) interposed therebetween.

The counter electrodes 12 are formed in the unit pixel space so as to have a rectangular frame shape, for example. The counter electrode 12 is disposed on the same plane as the gate bus line 11.

The pixel electrode 14 is formed in each unit pixel space in which the counter electrode 12 is formed. The pixel electrode 14 is connected to one end of the web portion 14a for dividing the region surrounded by the square-shaped counter electrode 12 in the y direction and one end of the web portion 14a, and has a counter electrode in the x direction ( 12) a first flange portion 14b overlapping the portion and a second flange portion 14c parallel to the first flange portion 14b and connected to the other end of the web portion 14a. That is, the pixel electrode 14 is shaped like the letter "I". Here, the counter electrode 12 and the pixel electrode 14 are formed of an opaque metal film. The width of the counter electrode 12 and the pixel electrode 14 is preferably about 5 to 10 µm in order to obtain an electric field of an appropriate intensity.

The pixel electrode 14 and the counter electrode 12 are insulated by a gate insulating film (not shown).

The thin film transistor 16 is disposed at the intersection of the gate bus line 11 and the data bus line 12. The thin film transistor 16 includes a gate electrode extending from the gate bus line 11, a drain electrode extending from the data bus line 15, a source electrode extending from the pixel electrode 14, and a channel formed on the gate electrode. Layer 17. The storage capacitor Cst is formed at a portion where the counter electrode 12 and the pixel electrode 14 overlap each other.

Although not shown in FIG. 1, an upper substrate (not shown) having a color filter (not shown) is disposed to face the lower substrate 10 at a predetermined distance. Here, the distance between the lower substrate 10 and the upper substrate is narrower than the distance between the y-direction portion of the counter electrode 12 and the web portion of the pixel electrode to form a parallel field parallel to the substrate surface. In addition, a liquid crystal layer (not shown) including liquid crystal molecules is interposed between the lower substrate 10 and the upper substrate (not shown).

In addition, a horizontal alignment layer (not shown) is formed on the inner surface of the upper substrate and the upper substrate, respectively, and the liquid crystal molecules 19 before the electric field is formed between the counter electrode 12 and the pixel electrode 14. They are arranged in parallel with the substrate to determine the alignment direction of the liquid crystal molecules. In the figure, the "R" direction is a rubbing axis direction of the horizontal alignment layer formed on the lower substrate.

A first polarizing plate (not shown) is disposed on the outer surface of the lower substrate 10, and a second polarizing plate (not shown) is disposed on the outer surface of the upper substrate (not shown). Here, the polarization axis of the first polarizing plate is arranged to be parallel to the "P" direction in the figure. That is, the rubbing axis direction R and the polarization axis P of the alignment film are parallel to each other. On the other hand, the polarization axis of the second polarizing plate is disposed substantially perpendicular to the polarization axis of the first polarizing plate.

When the scan signal is applied to the selected gate bus line 11 and the display signal is applied to the data bus line 15, the IPS-LCD has the gate bus line 11 to which the scan signal is applied and the data to which the display signal is applied. The thin film transistor 16 near the intersection of the bus lines 15 is turned on. Then, the display signal of the data bus line 15 is transmitted to the pixel electrode 14 through the thin film transistor 16. Therefore, an electric field E is generated between the counter electrode 12 and the pixel electrode 14 to which the common signal is applied. At this time, since the electric field E is in the "x" direction as shown in the drawing, the electric field E has a predetermined angle with the rubbing axis R.

Accordingly, the molecules in the liquid crystal layer are arranged such that the major axis of the substrate surface and the liquid crystal molecules are parallel while the major axis of the rubbing direction R coincides with each other before the electric field is formed. Accordingly, the light passing through the first polarizing plate and the liquid crystal layer does not pass through the second polarizing plate, and the screen is dark.

On the other hand, when the electric field E is formed, the long axis (or optical axis) of the liquid crystal molecules is rearranged in parallel with the electric field E, and the incident light passes through the second polarizing plate. Thus, the screen is in a white state.

In this case, since the liquid crystal molecules change only the direction in which the long axes of the liquid crystal molecules are aligned in accordance with the electric field, and the liquid crystal molecules themselves are arranged parallel to the surface of the substrate, the user sees the long axes of the liquid crystal molecules in any direction, and thus the viewing angle of the liquid crystal display device. This is improved.

However, the liquid crystal display of the IPS mode described above has the following problems.

As is known, the liquid crystal molecules in the liquid crystal have refractive index anisotropy (Δn) due to different lengths of the long axis and the short axis, and the refractive index anisotropy (Δn) changes depending on the viewing direction. As a result, a predetermined color appears even though the polar angle is near 0 ° and the azimuth is near white at 0 °, 90 °, 180 °, and 270 °. This phenomenon is called color shift, and the color shift is explained in more detail by the following equation (1).

T ≒ T ₀ sin ² (2χ) · sin ² (π · Δnd / λ) .............. (Equation 1)

T: transmittance

T ₀ : transmittance for incident light

χ: angle formed between the optical axis of the liquid crystal molecules and the polarization axis of the polarizer

Δn: refractive index anisotropy of the liquid crystal

d: distance or gap between the upper and lower substrates (thickness of the liquid crystal layer)

λ: incident light wavelength

According to Equation 1, in order to obtain the maximum transmittance T, χ should be π / 4 or Δnd / λ should be π / 2. At this time, when Δnd is changed (because the refractive index anisotropy value of the liquid crystal molecules changes depending on the viewing direction), the λ value is changed to satisfy π / 2. Accordingly, the color corresponding to the changed light wavelength [lambda] is displayed on the screen.

Therefore, in the direction (ⓐ, ⓒ) facing the short axis of the liquid crystal molecules, as Δn is relatively decreased, the wavelength of the incident light for reaching the maximum transmittance is relatively shortened. Accordingly, the user sees blue having a wavelength shorter than that of white.

On the other hand, in the directions (?, Ⓓ) facing the short axis of the liquid crystal molecules, as? N is relatively increased, the wavelength of the incident light becomes relatively long. Accordingly, the user sees yellow with a wavelength longer than that of white.

For this reason, the image quality characteristic of IPS-LCD falls.

In order to solve this color shift problem, a technique for generating an electric field parallel to the gate bus line and an electric field parallel to the data bus line in one pixel has been filed in Korean Patent Application No. 1998-19605. However, this technique can achieve color shift after the electric field is formed and the liquid crystal molecules are completely twisted parallel to the electric field, but the liquid crystal molecules are not symmetrically twisted in the halftone state, which perfectly improves the color shift. Difficult to do That is, in the above technique, although the electric fields in two directions are formed, the alignment layer is rubbed in a single direction, and thus the symmetry is not completely symmetric in the halftone state.

Accordingly, an object of the present invention is to provide an IPS-LCD and a method of manufacturing the same, which can prevent color shift even in a halftone state.

1 is a schematic view showing a conventional inflation switching mode liquid crystal display device.

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

3 is a view showing an alignment axis of an alignment film according to the present invention when using a liquid crystal having a negative dielectric anisotropy.

4 is a view showing an alignment axis of an alignment film according to the present invention when using a liquid crystal having a positive dielectric anisotropy.

5A illustrates an arrangement of liquid crystal molecules when an electric field is not formed in the inflation field driving liquid crystal display according to the present invention.

FIG. 5B is a view showing an arrangement of liquid crystal molecules in a half gray scale state of an inflen field driven liquid crystal display according to the present invention; FIG.

FIG. 5C is a view showing an arrangement of liquid crystal molecules when an electric field is formed in the inflation field driving liquid crystal display according to the present invention. FIG.

FIG. 6A is a view illustrating liquid crystal molecules and a polarization state when no electric field is formed in the inflation field driving liquid crystal display according to the present invention. FIG.

6B is a diagram illustrating liquid crystal molecules and a polarization state in a halftone state of an inflation field driving liquid crystal display according to the present invention;

6C is a view showing liquid crystal molecules and a polarization state when an electric field is formed in the influenza field driving liquid crystal display according to the present invention.

7 is a graph showing transmittance according to a viewing angle direction of a general IPS-LCD.

8 is a graph showing transmittance in the viewing angle direction of the IPS-LCD according to the present invention;

Explanation of symbols on main parts of drawing

20-counter electrode 25-pixel electrode

30-alignment layer

In order to achieve the above object of the present invention, the present invention, the upper and lower substrates are arranged at a predetermined distance, the unit pixel is limited; A liquid crystal layer comprising several liquid crystal molecules interposed between the upper and lower substrates; A counter electrode formed on each unit pixel of the lower substrate; A pixel electrode which generates an inflen field together with the counter electrode to operate most liquid crystal molecules in a unit pixel; A first horizontal alignment layer formed on an inner surface of the lower substrate and having a predetermined alignment axis; And a second horizontal alignment layer formed on an inner surface of the upper substrate, the second horizontal alignment layer having a non-parallel or parallel alignment axis with the alignment axis of the first horizontal alignment layer, wherein the counter electrode and the pixel electrode are in two directions symmetrical in the unit pixel. A first alignment layer portion of the region in which the first influenza field and the second inflation field are formed, the first alignment layer portion of the region in which the first influenza field is formed, has a first axis of orientation, The first alignment layer portion has a second alignment axis that is symmetrical with the first alignment axis, and either one of the first alignment axis and the second alignment axis forms a predetermined angle with the first influenza field.

Here, the first influenza field is parallel to the minor axis direction of the unit pixel, the second inflen field is parallel to the major axis direction of the unit pixel, and the counter electrode and the pixel electrode are formed in a predetermined axis of the unit pixel. And a branch parallel to the minor axis direction of the unit pixel formed in the remaining area of the unit pixel, and the counter electrode and the branch of the pixel electrode are alternately arranged to be parallel to each other. In addition, when the dielectric anisotropy of the liquid crystal molecules is negative, the first alignment axis is rubbed to form ± 0 to ± 45 ° with respect to the minor axis direction of the unit pixel, and when the dielectric anisotropy of the liquid crystal molecules is positive, the first region reference Thus, the first alignment axis is rubbed to form ± 45 ° to ± 90 ° with a short axis direction of the unit pixel.

In addition, according to another aspect of the present invention, there is provided a lower substrate having a limited unit pixel and having a driving electrode forming first and second influenza fields in two symmetrical directions for driving liquid crystal molecules; Forming a horizontal alignment layer on the lower substrate, optically aligning the horizontal alignment layer in a region in which the first influenza field is formed in a first direction at a predetermined angle with the first inflation field, and the second And optically aligning the horizontal alignment layer in the region forming the influenza field in a second direction perpendicular to the first direction.

(Example)

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a plan view of a liquid crystal display according to an exemplary embodiment of the present invention, and FIG. 3 is a view showing an alignment axis of an alignment layer according to the present invention when a liquid crystal having a negative dielectric anisotropy is used, and FIG. 4 is a positive dielectric anisotropy. When using a liquid crystal, it is a figure which shows the orientation axis of the alignment film which concerns on this invention. In addition, FIG. 5A illustrates an arrangement of liquid crystal molecules when an electric field is not formed in the inflation field driving liquid crystal display according to the present invention, and FIG. 5B illustrates an intermediate gray scale of the inflation field driving liquid crystal display according to the present invention. 5C is a view showing an arrangement of liquid crystal molecules when an electric field is formed in the inflation field driving liquid crystal display according to the present invention. In addition, Figure 6a is a view showing the liquid crystal molecules and the polarization state when no electric field is formed in the inflation field-driven liquid crystal display according to the present invention, Figure 6b is the middle of the inflation field-driven liquid crystal display device according to the present invention FIG. 6C is a view illustrating liquid crystal molecules and a polarization state in a gray scale state, and FIG. 6C is a diagram showing liquid crystal molecules and polarization states when an electric field is formed in the inflation field driving liquid crystal display according to the present invention. FIG. 7 is a diagram illustrating transmittance along a viewing angle direction of a general IPS-LCD, and FIG. 8 is a diagram illustrating transmittance along a viewing angle direction of an IPS-LCD according to the present invention.

2 schematically shows only the counter electrode and the pixel electrode of the active matrix type IPS-LCD, and the arrangement of the upper substrate structure, the gate bus line, the data bus line, the thin film transistor, and the common electrode line is a conventional active matrix type IPS- LCD. Since it is the same as the LCD, description thereof will be omitted. 2 illustrates only one unit pixel of the plurality of unit pixels. In addition, the x direction of FIG. 2 is generally a direction in which the gate bus line extends, that is, a short axis direction of the unit pixel, and a y direction is a direction in which the data bus line perpendicular to the gate bus line extends, that is, the long axis direction of the unit pixel. .

Referring to FIG. 2, the counter electrode 20 is formed on a lower substrate (not shown) for each unit pixel, and has excellent conductivity such as MoW and AlNd, which are materials forming gate bus lines (not shown). It is formed of a metal film. The counter electrode 20 includes a first electrode 20a having a rectangular frame shape and a second electrode 20b extending parallel to the x direction to bisect the first electrode 20a. Here, the space defined by the second electrode 20b as the first electrode 20a is divided into a first region B1 and a second region B2. In addition, the counter electrode 20 includes at least one third electrode 20c parallel to the y direction that partitions the first region B1 in the y direction, and the x direction that partitions the second region B2 in the x direction. At least one fourth electrode 20d parallel to the. Here, as the counter electrode 20 is formed in a frame, that is, a loop shape, signal distortion can be prevented from adjacent data bus lines.

The pixel electrode 25 overlaps the counter electrode 20. That is, an insulating film is interposed on the surface of the counter electrode 20, and a pixel electrode 25 is formed on the counter electrode 20. In this case, the pixel electrode 25 is formed of a material forming a data bus line (not shown), for example, a material such as Mo / Al / Mo or MoW. The pixel electrode 25 is disposed between the first branch 25a disposed on both sides of the third electrode 20c in the first region B1, and between the fourth electrode 20d in the second region B2, respectively. The second branch 25b to be connected, the third branch 25c connecting the first branch 25a and the second branch 25b, and the fourth branch 25d connecting one end of the first branch 25a. ) And a fifth branch 25e connecting one end of the second branch 25b. Here, the third to fifth branches 25c to 25e overlap with the counter electrode 20 to generate a storage capacitor.

The pixel electrode 25 is parallel to the x-axis so that an inflation field in the x-axis direction (hereinafter referred to as a horizontal inflation field) and an y-axis inflation field (hereinafter referred to as a vertical inflation field) are simultaneously generated in the unit pixel. A plurality of first branches 25a and a plurality of second branches 25b substantially perpendicular to the first branches 25a are included. In this case, the first branches 25a and the second branches 25b may be spaced at equal intervals, respectively, and the ratio of the width to the interval between the branches may be 1 or less. Here, the first branches 25a are disposed in an area A (hereinafter, referred to as a first area) corresponding to one half of the counter electrode 20, and the second branches 25b are disposed in the counter electrode 20. The pixel electrode 25 is formed of an opaque conductive material similarly to the counter electrode, and is disposed in the region B corresponding to the remaining part of the pixel B. The pixel electrode 25 and the counter electrode 20 are similar to the counter electrode. An insulating film is interposed between them to insulate each other.

As such, the upper substrate (not shown) is opposed to the lower substrate (not shown) on the lower substrate (not shown) on which the electrodes 20 and 25 are disposed. In this case, the distance between the upper and lower substrates is preferably smaller than the distances d1 and d2 of the counter electrode 20 and the pixel electrode 25.

A liquid crystal layer (not shown) having several liquid crystal molecules 50a and 50b is interposed between the lower substrate and the upper substrate. In this case, the liquid crystal layer may use a material having negative or positive dielectric anisotropy. In addition, the phase retardation value (the product of the cell gap and the refractive index anisotropy) of the liquid crystal layer is preferably 0.2 to 0.4 mu m so as to satisfy the maximum transmittance.

An alignment film (not shown) is formed between the lower substrate inner surface and the liquid crystal layer and between the upper substrate inner surface and the liquid crystal layer, respectively. As the alignment film, a horizontal alignment film having a pretilt angle of 5 ° or less is used. In addition, the alignment layer of the present embodiment is oriented in two directions symmetrical per unit pixel, so that perfect symmetry can be achieved even in the halftone state. That is, the orientation direction of the 1st area | region B1 and the 2nd area | region B2 is made orthogonal, and it twists, making it exactly symmetrical even in the halftone state. In this case, the direction of orientation should be 90 ° symmetrical between the first region B1 and the second region B2, and the direction is specified in consideration of the dielectric anisotropy so as to satisfy the maximum transmittance. Here, when the dielectric anisotropy of the liquid crystal molecules is negative, in order to satisfy the maximum transmittance, as shown in FIG. 3, the liquid crystal molecules correspond to the first region B1 of the alignment layer (hereinafter, referred to as the first alignment layer 30) formed on the lower substrate. The portion to be rubbed has a first alignment axis R1 that is ± 0 to ± 45 °, preferably ± 12 ° from the x-axis, and the portion corresponding to the second area B2 is the first alignment axis ( And a second alignment axis R2 perpendicular to R1). In addition, an alignment layer (hereinafter, referred to as a second alignment layer 31) formed on the upper substrate may have a portion corresponding to the first region A, which is non-parallel or parallel with the first alignment axis R1. The portion oriented to have the third alignment axis r1 and corresponding to the second region B is aligned to have the fourth alignment axis r2 that is non-parallel to or parallel to the second alignment axis R2. do. On the other hand, in the case of using a liquid crystal having a positive dielectric anisotropy, as shown in FIG. 4, the portion corresponding to the first region A of the first alignment layer 30 is ± 45 to ± 90 ° from the x-axis, preferably. Preferably, it is oriented to have a first alignment axis R1 forming ± 78 °, and a portion corresponding to the second area B has a second alignment axis R2 perpendicular to the first alignment axis R1. Oriented. In addition, an alignment layer (hereinafter, referred to as a second alignment layer 31) formed on the upper substrate may have a portion corresponding to the first 0 region A in a non-parallel or parallel manner with the first alignment axis R1. Oriented to have a third alignment axis (r1), the portion corresponding to the second region (B) is aligned to have a fourth alignment axis (r2) that is non-parallel or parallel to the second alignment axis (R2). do. At this time, the alignment of the alignment film 30 proceeds with the photo alignment method in order to prevent damage to the alignment film and to improve accuracy. In this way, when the unit pixel space is rubbed with two alignment axes due to the optical alignment, damage of the alignment layer is largely prevented because the rubbing process does not proceed a plurality of times, and the alignment axes are exactly symmetrical.

The polarizer is disposed on the outer surface of the lower substrate, and the decomposer is disposed on the outer surface of the upper substrate. At this time, the polarization axis P of the polarizer is parallel to the first alignment axis R1 or the second alignment axis R2, and the absorption axis A of the decomposer is perpendicular to the polarization axis.

The operation of the inflation field driving liquid crystal display device of the present invention will be described with reference to FIGS. 5A to 5C and 6A to 6C. 5A through 5C illustrate the movement of the counter electrode 20, the pixel electrode 25, and the liquid crystal molecules 50a and 50b in which an electric field is substantially formed, and FIGS. 6A through 6C illustrate liquid crystal molecules 50a. 50b) and the polarization direction are shown only.

First, as shown in FIG. 5A, when no electric field is formed between the counter electrode 20 and the pixel electrode 25, the liquid crystal molecules 50a in the first region B1 may have first and third alignment axes. The major axes (R1, r1) are arranged side by side, and the liquid crystal molecules 50b in the second region (B2) are arranged side by side with the second and fourth alignment axes (R2, r2). In this case, as shown in FIG. 6A, the polarization axis P of the polarizer is arranged to be parallel to the first alignment axis R1, and the absorption axis A of the decomposer is arranged to be perpendicular to the polarization axis P. Therefore, the light passing through the polarizer and the liquid crystal layer from the backlight is absorbed by the decomposer.

Thereafter, as shown in FIG. 5B, when a voltage difference is generated between the counter electrode 20 and the pixel electrode 25, the branch between the counter electrode 20 and the branches 25a and 25b of the pixel electrode 25 is formed. The plen field E is generated. Then, the liquid crystal molecules 50a and 50b are twisted such that the inflen field and the long axis (when a material having positive dielectric anisotropy is used) are parallel. In this figure, the liquid crystal molecules 50a and 50b are arranged at a predetermined angle (from the initial arrangement). When moving by an angle of 45 degrees or less, that is, the middle gray scale is displayed. At this time, the liquid crystal molecules 50a of the first region B1 are twisted by a predetermined angle, for example, 10.5 ° in a counterclockwise direction so as to be parallel to the influenza field E, and the liquid crystal molecules of the second region B2 ( 50b) is twisted by a predetermined angle clockwise, for example 10.5 °. Here, since the first region B1 and the second region B2 are rubbed to be symmetrical with each other, the first region B1 and the second region B2 are rubbed at the same angle even in the mid-gradation state when the electric field is applied, thereby achieving a perfect 90 ° symmetry even in the middle gradation as shown in FIG. . At this time, since the optical axis of the liquid crystal molecules 50a and 50b forms a predetermined angle with the polarization axis P of the polarizer and the absorption axis A of the decomposer, light passing through the polarization axis P and the liquid crystal layer from the backlight is absorbed. Pass through axis A.

Next, as shown in FIG. 5C, when the liquid crystal molecules 50a and 50b are arranged to be completely parallel to the long axis of the influenza field E, the liquid crystal molecules in the first region B1 and the second region B2. They are symmetrical with each other as shown in FIG. 6C, and are twisted by 45 ° with the polarization axis P and the absorption axis A, respectively. Accordingly, the light incident from the backlight passes through the polarization axis P, the liquid crystal layer, and the absorption axis A.

As described above, the IPS-LCD of the present invention arranges a counter electrode and a pixel electrode so as to form an electric field in two directions that are symmetric in one pixel, and aligns one unit pixel region in two directions by light alignment. Accordingly, color shifts can be prevented because the liquid crystal molecules are arranged symmetrically even in the halftones.

7 is a view showing the transmittance according to the viewing angle direction of a general IPS-LCD, Figure 8 is a view showing the transmittance along the viewing angle direction of the IPS-LCD according to the present invention. 7 and 8, it can be seen that the IPS-LCD of the present invention exhibits more uniform transmittance than the general IPS-LCD in the entire viewing angle direction.

This invention is not limited only to the above-mentioned embodiment. In the present embodiment, a liquid crystal display in which a horizontal direction (gate bus line direction) and a vertical direction (data bus line direction) are simultaneously formed in a unit pixel has been described. However, the present invention is not limited thereto, and two directions are symmetrical to one unit pixel. The present invention can be applied to any liquid crystal display device in which an electric field is formed.

As described in detail above, according to the present invention, in the IPS-LCD, the pixel electrode and the counter electrode are arranged so that the horizontal inflation field and the vertical inflation field are formed in the unit pixel, and the alignment film is formed with the horizontal inflation field. The region to be formed and the region in which the longitudinal influenza field is formed are rubbed so as to have an alignment axis 90 ° symmetric with each other. Accordingly, even in the halftone state, the liquid crystal molecules may be twisted while forming 90 ° symmetry, thereby preventing the color shift phenomenon even in the halftone state.

In addition, this invention can be implemented in various changes within the range which does not deviate from the summary.

Claims (7)

Upper and lower substrates disposed at a predetermined distance and having unit pixels defined therein; A liquid crystal layer comprising several liquid crystal molecules interposed between the upper and lower substrates; A counter electrode formed on each unit pixel of the lower substrate; A pixel electrode which generates an inflen field together with the counter electrode to operate most liquid crystal molecules in a unit pixel; A first horizontal alignment layer formed on an inner surface of the lower substrate and having a predetermined alignment axis; And A second horizontal alignment layer formed on an inner surface of the upper substrate and having a non-parallel or parallel alignment axis with an alignment axis of the first horizontal alignment layer, The counter electrode and the pixel electrode are disposed to form first and second inflation fields in two directions symmetrically within a unit pixel. The first alignment layer portion of the region where the first influenza field is formed has a first alignment axis, and the first alignment layer portion of the region where the second inflen field is formed has a second alignment axis that is symmetric to the first alignment axis. , Wherein either the first orientation axis or the second orientation axis is at an angle to the first influenza field. 2. The IPS-LCD of claim 1, wherein the first inflen field is parallel to the minor axis direction of the unit pixel, and the second inflen field is parallel to the major axis direction of the unit pixel. The display device of claim 1, wherein the counter electrode and the pixel electrode each include a branch parallel to a long axis direction formed in a predetermined region of the unit pixel, and a branch parallel to a short axis direction of the unit pixel formed in the remaining region of the unit pixel. And the branches of each counter electrode and pixel electrode are alternately arranged to be parallel to each other. 2. The IPS-LCD of claim 1, wherein when the dielectric anisotropy of the liquid crystal molecules is negative, the first alignment axis is rubbed to have a uniaxial direction of ± 0 to ± 45 ° of the unit pixel. The IPS-LCD of claim 1, wherein when the dielectric anisotropy of the liquid crystal molecules is positive, the first alignment axis is rubbed to form ± 45 ° to ± 90 ° with respect to the minor axis direction of the unit pixel. The IPS-LCD according to claim 1, wherein the phase retardation value of the liquid crystal layer is 0.2 to 0.4 mu m. Providing a lower substrate having a unit pixel defined therein, and having a driving electrode forming first and second inflation fields in two symmetrical directions for driving the liquid crystal molecules; Forming a horizontal alignment layer on the lower substrate; Optically aligning a horizontal alignment layer of a region forming the first inflation field in a first direction at a predetermined angle with the first inflation field; And And optically aligning a horizontal alignment layer in a region forming the second influenza field in a second direction perpendicular to the first direction.