KR100989165B1 - In-Plane Switching Mode Liquid Crystal Display device and method for fabricating the same - Google Patents

Abstract

The present invention relates to a transverse electric field type liquid crystal display device and a manufacturing method for increasing the aperture ratio and preventing crosstalk due to the coupling phenomenon, the transverse electric field type liquid crystal display device of the present invention is formed in the first direction on the lower substrate A gate line; A common line formed on the lower substrate and insulated from the gate line in the first direction; A common electrode extending from the common line on the lower substrate and formed in a second direction perpendicular to the first direction; At least a portion of the adjacent common electrode overlaps the gate insulating film formed on the front surface of the lower substrate including the gate line, the common line, and the common electrode, and crosses the gate line in the second direction to define a pixel region. A data line formed; A thin film transistor formed at a portion where the gate line and the data line cross each other and formed of a gate electrode, a semiconductor layer, a source and a drain electrode; A pixel electrode corresponding to each of the pixel regions, the pixel electrode being connected to the drain electrode of the thin film transistor on the gate insulating layer, and alternately formed to be parallel to the common electrode; And a transparent conductive metal contacting the common electrode adjacent to the gate line in the second direction or the contact hole formed in the common line, and the common electrode or the common line adjacent to the gate line in the second direction. It is configured to include a common line connection electrically connecting each other.

 Common line, common line connection, common electrode

Description

In-Plane Switching Mode Liquid Crystal Display device and method for fabricating the same}

1 is a perspective view schematically showing a typical TN liquid crystal panel

2A and 2B are schematic perspective views showing shapes of liquid crystal molecules when voltage is applied to a TN liquid crystal panel;

3 is a cross-sectional view schematically showing a general transverse electric field type liquid crystal display device

4A and 4B are views illustrating a change in arrangement of liquid crystal molecules upon voltage on / off in a transverse electric field type liquid crystal display device.

5A and 5B are plan views schematically illustrating liquid crystal molecules according to electric field applied to a common electrode and a pixel electrode in a transverse electric field type liquid crystal display device;

6 is a plan view of a transverse electric field type liquid crystal display device according to the prior art;

FIG. 7 is a cross-sectional view taken along line II ′ of FIG. 6;

8 is a plan view schematically showing a transverse electric field type liquid crystal display device of the related art

9 is a plan view of a transverse electric field type liquid crystal display device according to the present invention;

10 is a cross-sectional view taken along line II-II 'of FIG.

11 is a plan view schematically showing a transverse electric field type liquid crystal display device of the present invention.

Explanation of symbols for main parts of the drawings                 

50: lower substrate 51: gate line

52: data line 53: pixel electrode

54 common line 55 common electrode

55a: contact hole 56: common line connection

58 gate insulating film 59 protective film

63a, 63b: first and second alignment layers 64: black matrix layer

65 color filter layer 66 liquid crystal layer

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transverse electric field type liquid crystal display device, and more particularly, to include a common electrode overlapping a data line to increase an aperture ratio, and to connect a common electrode or a common line adjacent to a gate line in a direction parallel to the data line. The present invention relates to a transverse electric field type liquid crystal display device and a manufacturing method capable of reducing a coupling phenomenon including a common line connection part.

Recently, due to the rapid development of the information and communication field, the importance of the display industry for displaying desired information is increasing day by day. To date, the CRT (Cathode Ray Tube) among the information display devices can display various colors, and the brightness of the screen is increased. It has also enjoyed steady popularity so far because of its superiority.

However, due to the desire for large, portable and high resolution displays, development of flat panel displays is urgently needed instead of CRTs, which are bulky and bulky. These flat panel displays have a wide range of applications from computer monitors to displays used in aircraft and spacecraft.

Currently produced or developed flat panel displays include Liquid Crystal Display (LCD), Electro Luminescent Display (ELD), Field Emission Display (FED), Plasma Display Panel (PDP), etc. In order to achieve an ideal flat panel display, light weight, high brightness, high efficiency, high resolution, high speed response characteristics, low driving voltage, low power consumption, low cost, and color display characteristics are required. Among such flat panel displays, the LCD is in the spotlight because of its desire, durability, and portability.

On the other hand, the liquid crystal display device is an image display device using the optical anisotropy characteristics of the liquid crystal, and when the light is irradiated to the liquid crystal exhibiting polarization characteristics according to the voltage applied state of the liquid crystal display device according to the alignment state of the liquid crystal You can adjust the amount to express the image.

In order to configure the liquid crystal display device, a liquid crystal panel including the liquid crystal layer and a circuit disposed around the liquid crystal panel to apply a signal to the liquid crystal panel and control the signal are further required.

Hereinafter, a schematic configuration of a general liquid crystal display device will be described with reference to the drawings.

1 is a perspective view schematically showing a typical TN liquid crystal panel.                         

As shown in FIG. 1, a general TN liquid crystal display device includes a liquid crystal 9 formed between an upper substrate 4 and a lower substrate 8 and upper and lower substrates 4 and 8.

The upper substrate 4 includes a black matrix layer 1 for blocking light at portions other than the pixel region 5, a color filter layer 2 formed at each pixel region to implement color RGB, A common electrode 3 is formed on the color filter 2 to apply a common voltage.

The lower substrate 8 is formed in a plurality of gate lines 10 and data lines 11 arranged in a direction perpendicular to each other to define a pixel region 5, and in each pixel region Pixel 5. Pixel electrodes 6 and a plurality of thin film transistors 7 which apply image signals of the data lines to the pixel electrodes 6 by driving signals of the gate lines 10.

Although not shown, the gate line 10 and the data line 11 are formed to cross each other with a gate insulating layer interposed therebetween, and the common electrode 3 and the pixel electrode 6 are indium-tin-oxide. -Tin-Oxide (ITO) is formed of a transparent conductive metal.

In the TN liquid crystal display device configured as described above, a vertical electric field is generated according to the voltage applied to the pixel electrode 6 and the common electrode 3, and the liquid crystal layer 9 is oriented by the vertical electric field, and the liquid crystal According to the degree of alignment of the layer 9, the image may be expressed by adjusting the amount of light passing through the liquid crystal layer 9. Such a TN liquid crystal display device has excellent characteristics such as transmittance and aperture ratio, and the common electrode 3 of the upper substrate 4 serves as a ground to prevent destruction of the liquid crystal cell due to static electricity.

2A and 2B are schematic perspective views illustrating shapes of liquid crystal molecules when voltage is applied to the TN liquid crystal panel.

First, as shown in FIG. 2A, when no voltage is applied, the TN liquid crystal molecules 9a are horizontally arranged so that the upper and lower liquid crystal molecules 9a extend from the lower substrate 8 to the upper substrate 4. The azimuth is twisted 90 degrees (Twist). In this case, the liquid crystal molecules 9a have positive dielectric anisotropy and use chiral dopants to make the liquid crystal molecules 9a twist.

On the other hand, as shown in FIG. 2B, when the voltage V is applied to the pixel electrode 6 and the common electrode 3 of the upper and lower substrates 4 and 8, the liquid crystal molecules 9a are in the direction of the electric field. The polar angles of the liquid crystal molecules 9a are perpendicular to each other between the two substrates 4 and 8 by 90 degrees.

Accordingly, the TN liquid crystal display device has a problem in that the wide viewing angle cannot be realized because the C / R (contrast ratio) and the brightness are severely changed according to the viewing angle.

In order to solve the viewing angle problem caused by the vertical electric field, a transverse electric field type liquid crystal display device has been proposed.

3 is a cross-sectional view schematically illustrating a general transverse electric field type liquid crystal display device.

In the transverse electric field type liquid crystal display device, the pixel electrode 21 and the common electrode 22 are formed on the lower substrate 20 at a predetermined distance. Accordingly, when a voltage is applied to the pixel electrode 21 and the common electrode 22, a lateral electric field is generated, and the liquid crystal molecules 23a are formed between the pixel electrode 21 and the common electrode 22. Works by).

The driving of the transverse electric field type liquid crystal display will be described in detail as follows.

4A and 4B illustrate a change in arrangement of liquid crystal molecules when voltage is turned on and off in a typical transverse electric field type liquid crystal display device.

First, as shown in FIG. 4A, when no voltage is applied to the pixel electrode 21 and the common electrode 22, the liquid crystal molecules 23a are aligned side by side with the pixel electrode 21 and the common electrode 22. It can be seen.

In addition, as shown in FIG. 4B, when a voltage is applied to the pixel electrode 21 and the common electrode 22, a transverse electric field is formed between the pixel electrode 21 and the common electrode 22 and along the transverse electric field. It can be seen that the liquid crystal molecules 23a are aligned in the horizontal direction.

At this time, since the liquid crystal molecules 23a adjacent to the upper substrate 25 and the lower substrate 20 are constrained by an alignment film (not shown) formed on the two substrates 20 and 25, the transverse electric field direction It is hard to be oriented.

That is, the above-described transverse electric field type liquid crystal display device will be described as follows.

5A and 5B are plan views schematically illustrating states of liquid crystal molecules according to an electric field applied to a common electrode and a pixel electrode in a general transverse electric field type liquid crystal display device.                         

As shown in FIG. 5A, when no voltage is applied to the common electrode 22 and the pixel electrode 21, the liquid crystal molecules 23a are aligned layers (not shown) on two substrates 20 and 25 of FIG. 4A. Is aligned parallel to the common electrode 22 and the pixel electrode 21 in the same direction as the initial oriented direction.

On the other hand, as shown in FIG. 5B, when voltage is applied to the pixel electrode 21 and the common electrode 22, the liquid crystal molecules 23a are formed between the pixel electrode 21 and the common electrode 22. It can be seen that it is oriented in the same direction as the transverse electric field.

As described above, an advantage of the transverse electric field type liquid crystal display device is that a wide viewing angle is possible because the change in the polar angle of each liquid crystal is small when a voltage is applied. That is, when the liquid crystal display device is viewed from the front, it may be visible up to about 70 degrees in the up / down / left / right directions.

6 is a plan view of a transverse electric field type liquid crystal display device according to the related art.

As shown in FIG. 6, in the conventional transverse electric field type liquid crystal display, a plurality of gate lines 31 and data lines 32 are arranged in a direction perpendicular to each other to define a pixel area (not shown). The common line 33 is arranged to be parallel to the gate line 31, and a plurality of common electrodes 34 are formed to be connected to the common line 33 and parallel to the data line 32.

In addition, the gate electrode 35, the gate insulating film (not shown), the semiconductor layer 36, and the source / drain electrodes 37a and 37b are formed at the intersection of the gate line 31 and the data line 32. The thin film transistor T is formed, and each pixel region is connected to the drain electrode 37b and the pixel electrode 38 is arranged between the common electrode 34.

In this case, the pixel electrode 38 and the common electrode 34 are formed in parallel with the data line 32 in the pixel region, and the pixel electrode 38 may be connected to the common line 33 to form a storage capacitor. It has an overlapping area.

Accordingly, in the conventional transverse electric field type liquid crystal display device, when a data voltage is applied through the thin film transistor T, a transverse electric field is formed between the common electrode 34 and the pixel electrode 38.

In this case, the relationship between the common electrode and the data line will be described.

FIG. 7 is a cross-sectional view taken along line II ′ of FIG. 6, and FIG. 8 is a plan view schematically illustrating a transverse electric field type liquid crystal display device according to the related art.

In the transverse electric field type liquid crystal display device according to the related art, as shown in FIG. 33) and a common electrode 34, and a gate insulating film 39 is formed on the entire surface of the substrate including the gate line and the common line, and a semiconductor layer (36 in FIG. 6) is formed on the gate insulating film above the gate electrode 35. ) Is formed. The data line 32, the source / drain electrodes (37a and 37b in FIG. 6) and the pixel electrode 38 are formed on the gate insulating layer 39 so as to be perpendicular to the gate line 31. A protective film 40 and a first alignment 42a film are sequentially formed on the entire substrate including 38.

The black matrix layer 43 is formed in a portion except for the pixel region on the upper substrate 25 facing the lower substrate 20, and the color filter layer 41 is formed in each pixel region. A second alignment layer 42b is formed on the entire upper substrate including the color filter layer 41. The liquid crystal layer 23 is formed between the upper and lower substrates 20 and 25.

Therefore, when a data voltage is applied to the pixel electrode 38, a transverse electric field is formed by the voltage difference between the pixel electrode 38 and the common electrode 34, and the liquid crystal may be aligned by the transverse electric field.

In this case, as shown in FIG. 8, the common line 33 connecting the common electrode 34 of FIG. 7 is formed to be parallel to the gate line 31 and connected to each other at an edge of the active region 30.

Therefore, when a data voltage is applied to the data line 32 in consideration of the resistance of the common line 33, the common electrode 34 and the data line (eg, to reduce a coupling phenomenon to the common electrode 34). 32) is formed to be spaced apart by a predetermined interval.

Accordingly, the black matrix 43 is adjacent to the data line 32 as well as the data line to prevent light leakage from the edges of the data line 32 and the common electrode 34 on the upper substrate 25. It is formed wide so as to correspond to the upper part of the electrode 34.

That is, the black matrix layer 43 is disposed to correspond to the center of the common electrode 34 adjacent to the data line 32 to block light leaking between the data line 32 and the common electrode 34. Had to be widely formed.

However, the conventional transverse electric field type liquid crystal display device has the following problems.                         

First, the transverse electric field type liquid crystal display of the prior art has a disadvantage in that the aperture ratio is lowered because the black matrix layer must be formed to correspond to the common electrode portion of the edge of the data line.

Second, in the transverse electric field type liquid crystal display device of the related art, a coupling phenomenon may occur on the common electrode or the common line overlapping the data line, thereby causing a screen defect.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems of the prior art, and improves the aperture ratio by overlapping a common electrode adjacent to a data line with the data line. It is an object of the present invention to provide a transverse electric field type liquid crystal display device which can reduce the coupling phenomenon due to overlap between the data line and the common line.

In accordance with one aspect of the present invention, a transverse electric field type liquid crystal display device includes: a gate line formed in a first direction on a lower substrate; A common line formed on the lower substrate and insulated from the gate line in the first direction; A common electrode extending from the common line on the lower substrate and formed in a second direction perpendicular to the first direction; At least a portion of the adjacent common electrode overlaps the gate insulating film formed on the front surface of the lower substrate including the gate line, the common line, and the common electrode, and crosses the gate line in the second direction to define a pixel region. A data line formed; A thin film transistor formed at a portion where the gate line and the data line cross each other and formed of a gate electrode, a semiconductor layer, a source and a drain electrode; A pixel electrode corresponding to each of the pixel regions, the pixel electrode being connected to the drain electrode of the thin film transistor on the gate insulating layer, and alternately formed to be parallel to the common electrode; And a transparent conductive metal contacting the common electrode adjacent to the gate line in the second direction or the contact hole formed in the common line, and the common electrode or the common line adjacent to the gate line in the second direction. It is characterized in that it comprises a common line connection to electrically connect to each other.

The common line connection part may be formed on the gate insulating layer.

The common line connection part may be formed in the second direction.

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The common line and the common line connection is characterized in that it is formed in a net shape.

Such a transverse electric field type liquid crystal display device according to the present invention can increase the aperture ratio by forming a black matrix to correspond to the data line by forming the data line to overlap the common electrode, and the common electrode or the common line adjacent to the gate line are mutually increased. By forming a common line connecting unit electrically connecting the common electrode and the common electrode, the coupling phenomenon generated in the common electrode and the data line can be reduced.

 Hereinafter, a transverse electric field type liquid crystal display device and a method of manufacturing the same according to the present invention having the above characteristics will be described in detail with reference to the accompanying drawings.

9 is a plan view of a transverse electric field liquid crystal display device according to the present invention, FIG. 10 is a structural cross-sectional view along the line II-II 'of FIG. 9, and FIG. It is flatness.
As shown in FIG. 9, the transverse electric field liquid crystal display according to the present invention includes a plurality of gate lines 51 and pixel regions defined in a first direction on a lower substrate (not shown). A plurality of data lines 52 formed to cross each of the gate lines 51 in a second direction perpendicular to one direction, and formed at portions where the gate lines 51 and each data line 52 intersect. A thin film transistor T, a plurality of common lines 54 formed to be insulated from the gate line in the first direction, and extend from the common line 54 corresponding to each pixel area to be formed in the second direction The common electrode 55 and the pixel electrode 53 corresponding to each pixel area, which are electrically connected to the drain electrode 62b of the thin film transistor T and are alternately formed with the common electrode 55 in the second direction. ) And the crab The common electrode 55 adjacent to the trench line 51 or the transparent conductive metal contacting the contact hole 55a formed in the common line 54, respectively, is formed of a common electrode 55 adjacent to each of the gate lines 51. Or a common line connection 56 for electrically connecting the common lines 54 to each other. In this case, the transparent conductive wire metal may include indium tin oxide (ITO), or the like.
The plurality of gate lines 51, the plurality of common lines 54, and the common electrode 55 are simultaneously formed on the lower substrate (not shown), and the plurality of gate lines 51 and the plurality of common lines ( 54 is insulated from each other, and the plurality of common lines 54 and the common electrode 55 are connected to each other. The plurality of data lines 52 and the pixel electrodes 53 may include the lower substrate including the plurality of gate lines 51, the plurality of common lines 54, and the common electrodes 55 (not illustrated). It is formed simultaneously on the gate insulating film (not shown) formed in the front surface.
Each of the data lines 52 is formed to overlap the adjacent common electrode 55, thereby increasing the aperture ratio by reducing light leakage around the data line 52.

The common line connector 56 is formed in the same second direction as the data line 52. Therefore, when a data voltage is applied to the data line 52, the coupling charge induced in the common electrode 55 may be reduced.

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The transverse electric field type liquid crystal display device according to the present invention will be described in detail as follows.
As shown in FIG. 10, on the lower substrate 50, a plurality of gate lines 51 of FIG. 9 and a plurality of common lines 54 of FIG. 9 are spaced apart from each other at regular intervals. At the same time, the gate line 51 of FIG. 9 and the data line 52 to be described later cross each other to correspond to each of the pixel regions defined by the gate line 51. 51a) is formed. In addition, a plurality of pixels corresponding to each of the pixel areas may extend from each of the plurality of common lines (54 of FIG. 9) in a direction perpendicular to the plurality of common lines (54 of FIG. 9) on the lower substrate 50. Common electrodes 55 are formed.
A gate insulating layer 58 is formed on an entire surface of the lower substrate 50 including the plurality of gate lines 51 of FIG. 9, a plurality of common lines 54 of FIG. 9, and a plurality of common electrodes 55.
A semiconductor layer (51b in FIG. 9, not shown in FIG. 10) is formed on the gate insulating layer 58.
In addition, the gate insulating layer 58 may cross the plurality of gate lines 51 in a direction perpendicular to the plurality of gate lines 51 to define the pixel area, and may be adjacent to the common electrode 55. Overlapping data lines 52 are formed. At the same time, a pixel electrode 53 corresponding to the pixel area is formed on the gate insulating layer 58 to be alternated with the common electrode 55. In this case, a source electrode 52a of FIG. 9 is formed in the data line 51 so as to protrude in the direction of the semiconductor layer, and the pixel electrode 53 is opposite to the source electrode 52a of FIG. 9. The drain electrode is formed to protrude on one side.
A passivation layer 59 is formed on an entire surface of the lower substrate 50 including the data line 52 and the pixel electrode 53.
Next, a contact hole 55a is formed in the common electrode 55 or the common line 54 formed in the pixel region adjacent to the gate line 51. In addition, all of the contact holes 55a formed in the common line 54 or the common electrode 55 adjacent to the gate line 51 are contacted with the gate line 51 on the passivation layer 59. A common line connection 56 is formed to electrically connect adjacent common electrodes 55 or common lines 54 to each other. In this case, the common line connection part 56 is formed in a direction parallel to the data line 52. In addition, the common line connector 56 is formed of a transparent conductive metal such as ITO.
In addition, a first alignment layer 63a is formed on the lower substrate 50 including the common line connector 56.

In addition, a black matrix layer 64 is formed on the upper substrate 57 to block light in portions corresponding to the gate line 51 and the data line 52 except for the pixel region. R, G, and B color filter layers 65 are formed on the corresponding portions to implement color. A second alignment layer 63b is formed over the entire upper substrate including the color filter layer 65.

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Herein, since the data line 52 formed on the lower substrate 50 and the common electrode 55 adjacent to the data line 52 overlap each other, the amount of light flowing out through the periphery of the data line 52 is increased. Because of this small size, the width of the black matrix 64 corresponding to the data line 52 can be reduced so that the width of the black matrix layer can be reduced as compared with the related art.

The upper substrate 57 and the lower substrate 50 formed as described above are bonded to face each other with a predetermined space, and a liquid crystal layer 66 is formed between the upper substrate 57 and the lower substrate 50.

In FIG. 10, the common line connector 56 is formed on the passivation layer 59 after the passivation layer 59 is formed. However, the gate insulating layer 58 on which the data line 52 is formed is described. It can be formed on. That is, a metal layer for forming a data line is deposited on the gate insulating layer, the data line 52 and the pixel electrode 53 and the common line connector 56 are defined by an exposure and development process, and then the metal layer is selectively removed. The data line 52 and the pixel electrode 53 are formed, and the common line connector 56 is formed. In this case, the protective film 59 may not be formed.

Accordingly, in the transverse electric field type liquid crystal display device according to the present invention, the common electrode 55 may be formed to overlap the data line 52 to increase the aperture ratio. In addition, since both common electrodes or the common lines adjacent to the gate line 51 are electrically connected to each other to form a common line to form a mesh to reduce the resistance of the common line, the coupling between the common line and the data line Crosstalk can be prevented.

FIG. 11 illustrates that the common line 54 and the common line connecting portion 56 are formed in a mesh shape and grounded to the edge of the active region 67.

Therefore, by connecting the plurality of common lines 54 to each other using the common line connector 56, the coupling charge induced in the common electrode 55 by the data voltage applied to the data line 52 can be reduced. .

In the transverse electric field type liquid crystal display device according to the present invention as described above has the following advantages.

First, the transverse electric field type liquid crystal display device according to the present invention may form a common electrode adjacent to the data line to overlap the data line and relatively reduce the width of the black matrix layer, thereby increasing the aperture ratio of the liquid crystal display device.

Second, since common lines or common electrodes on both sides of the gate line are connected to each other to form a common line in a net shape, resistance of the common line can be reduced. Therefore, even if the common line or the common electrode and the data line overlap, crosstalk increase due to the change of the common voltage can be prevented.

Claims (7)

A gate line formed in a first direction on the lower substrate; A common line formed on the lower substrate and insulated from the gate line in the first direction; A common electrode extending from the common line on the lower substrate and formed in a second direction perpendicular to the first direction; At least a portion of the adjacent common electrode overlaps the gate line formed on the front surface of the lower substrate including the gate line, the common line, and the common electrode, and crosses the gate line in the second direction to define a pixel region. A data line formed; A thin film transistor formed at a portion where the gate line and the data line cross each other and formed of a gate electrode, a semiconductor layer, a source and a drain electrode; A pixel electrode corresponding to each pixel area, connected to the drain electrode of the thin film transistor on the gate insulating layer, and alternately formed in the second direction with the common electrode; And A transparent conductive metal contacting the common electrode adjacent to the gate line in the second direction or the contact hole formed in the common line, respectively, to form the common electrode or the common line adjacent to the gate line in the second direction; A transverse electric field type liquid crystal display device comprising a common line connection part electrically connected to each other. delete The method of claim 1, And the common line connection part is formed on the gate insulating film. The method of claim 1, And the common line connection part is formed in the second direction. The method of claim 1, And the common line and the common line connection part are formed in a net shape. Forming a plurality of common electrodes extending from each of the plurality of common lines in a direction perpendicular to the plurality of gate lines and the plurality of common lines parallel to each other on a lower substrate; Forming a gate insulating film on the lower substrate including the plurality of gate lines, the plurality of common lines, and the plurality of common electrodes; Forming a semiconductor layer on the gate insulating film; A plurality of data lines and a plurality of data lines overlapping the plurality of gate lines in a direction perpendicular to the plurality of gate lines and overlapping with the adjacent common electrode so as to define a pixel region on the gate insulating layer, Forming a plurality of pixel electrodes that alternate with the electrodes; Forming a contact hole in a common line or a common electrode adjacent to the gate line; And And forming a common line connection part connecting the common line or the common electrode adjacent to the gate line in a direction parallel to the data line through the contact hole. The method of claim 6, And forming a passivation film on the entire surface of the gate insulating film including the plurality of data lines and the plurality of pixel electrodes after the pixel electrode is formed.

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