KR20050049726A - In-plane switching mode liquid crystal display device and method thereof - Google Patents

Abstract

A transverse electric field liquid crystal display device according to the present invention comprises: a first substrate; A gate line and a data line crossing the first substrate to define a pixel region; A thin film transistor connected to the gate line and the data line; A pixel electrode formed on the pixel region, connected to the thin film transistor, and having a plurality of vertical patterns; A common electrode having a plurality of vertical patterns arranged to be alternate with each vertical pattern of the pixel electrode; A color filter formed under the pixel electrode and the common electrode on the pixel area; A black matrix formed on the thin film transistor; A transparent second substrate disposed below the first substrate at predetermined intervals; And a liquid crystal layer formed between the first and second substrates.

According to the present invention, the back light passes through the liquid crystal layer first and then passes through the TFT or the color filter layer, thereby preventing the scattering of the light generated when passing through the layer or the changed light is delayed. / R is improved, and the lower substrate can be made of bare glass, which simplifies the process, reduces the material cost, and improves the yield.

Description

Transverse electric field type liquid crystal display device and method for manufacturing the same {In-Plane Switching mode Liquid Crystal Display Device and method

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and in particular, to form a thin film transistor (TFT) on an upper substrate to improve the C / R (Contrast Ratio) of the liquid crystal display device and a manufacturing method thereof. It is about.

In general, a liquid crystal display device is formed by bonding an upper substrate and a lower substrate and injecting a liquid crystal between the lower substrates. In addition, a polarizer, a retardation film, and the like are attached to the outer surfaces of the upper and lower substrates, and by selectively configuring such a plurality of components, the light propagation direction or the refractive index is changed to be high. A liquid crystal display device having brightness and contrast characteristics is formed.

The liquid crystal cell used in recent years as a liquid crystal display device generally adopts a Twisk nematic (TN) mode, and the TN mode has a characteristic that the light transmittance in the gray scale display varies depending on the viewing angle, thereby limiting its large area. have.

In order to solve this problem, an In-Plane-Switching (IPS) mode using a parallel electric field has contrast, gray inversion, and color shift compared to the conventional TN mode. There is an advantage that can improve the viewing angle characteristics such as (shift).

In the IPS mode, a pixel electrode and a common electrode are formed on the same plane on a thin film transistor (TFT) array substrate, that is, a lower substrate provided with a TFT, and a liquid crystal is formed on the same substrate. It is operated by a horizontal electric field.

1 is a partial plan view of a lower substrate of a conventional IPS mode LCD.

Referring to FIG. 1, a gate line 111 and a data line 113 cross each other on a lower substrate, and a thin film transistor T, which is a switching element, is formed at a point where the gate line 111 and the data line 113 cross each other. ) Is configured. The thin film transistor T includes a gate electrode 119, a source electrode 121, and a drain electrode 123.

The common electrode 115 and the pixel electrode 117 are formed in a finger shape on the pixel region P defined by the intersection of the gate line 111 and the data line 113, respectively. 115 includes a plurality of vertical patterns of the first common electrode 115a and a second common electrode 115b of a horizontal pattern that integrates the plurality of first common electrodes into one, and is spaced apart from the gate line 111 by a predetermined distance. It is formed spaced apart.

In addition, the pixel electrode 117 formed to be engaged with the common electrode 115 is also a horizontal pattern that integrates the plurality of vertical patterns of the first pixel electrode 117a and the plurality of first pixel electrodes 117a into one. It consists of two pixel electrodes 117b.

In this case, the first common electrode 115a formed at both ends of the single pixel region P may be formed to overlap the data line 113 on the data line 113 to increase the aperture ratio.

2A to 2C are cross-sectional views of the manufacturing process taken along the lines II and II of FIG. 1.

First, as illustrated in FIG. 2A, a conductive metal is deposited and patterned on the substrate 109 to form a gate line 111 and a gate electrode 119.

Next, an inorganic insulating material such as silicon nitride (SiNx) and silicon oxide (SiO ₂ ), or an acrylic resin, benzocyclobutene (BCB), etc., on the entire surface of the substrate 109 on which the gate line 111 is formed. The same organic insulating material is deposited to form the gate insulating layer 118.

Next, as shown in FIG. 2B, pure amorphous silicon (a-Si) and amorphous silicon (n + a-Si) containing impurities are stacked on the substrate on which the gate insulating layer 118 is formed, and then patterned to form an active layer. The layer 125 and the ohmic contact layer 127 are formed, and a conductive metal is deposited and patterned on the substrate on which the ohmic contact layer 127 is formed, thereby forming the data line 113, the source electrode 121, and the drain electrode 123. ).

Thereafter, BCB or an acrylic resin, which is a low dielectric material 129, is deposited on the entire surface of the substrate on which the drain electrode 123 and the like are formed and patterned to form a drain contact hole 131 on the drain electrode 123.

FIG. 2C illustrates a process of forming a common electrode and a pixel electrode, and depositing and patterning a transparent conductive metal such as indium tin oxide (ITO), indium zinc oxide (IZO), and the like to be interdigitated at predetermined intervals. The common electrode 115 and the pixel electrode 117 are formed. (The figures are the vertical pattern 115a of the common electrode 115 and the vertical pattern 117a of the pixel electrode 117.)

3 is a cross-sectional view of a lower substrate cut along the lines II and II of FIG. 2 and an upper substrate corresponding thereto.

Referring to FIG. 3, the lower substrate is the same as that shown in FIG. 2C, and a description thereof will be omitted. In the upper substrate 140 formed corresponding to the lower substrate, each pixel region P formed on the lower substrate and Corresponding red, green, and blue color filter 144 patterns formed between the color filter patterns, and between the respective color filter patterns and a portion of the back light that do not penetrate the lower substrate and a portion of the upper substrate to prevent light leakage. A formed black matrix (hereinafter referred to as BM) 142 and an overcoat (OC) layer 146 formed on the color filter 144 pattern and the BM 142 as a whole are provided. Liquid crystals 148 and 148 'are provided in the region between the upper substrates.

Here, the liquid crystals 148 and 148 'are operated by horizontal electric fields of the pixel electrode and the common electrode formed on the lower substrate, and the light transmittance of the back light incident by linear polarization by the operation of the liquid crystals 148 and 148'. As a result, various images are displayed.

However, in the conventional IPS mode liquid crystal display device, the liquid crystal 148 'positioned on the TFT peripheral area formed on the lower substrate is different from the other liquid crystal 148 due to the protruding shape of the TFT. Accordingly, the back light passing through the TFT surrounding area collapses linearly polarized light so that a change in light occurs. As the light changes through the liquid crystal layer, the changed light is retarded and finally C / R of the liquid crystal display device. There is a disadvantage that the image quality is poor, such as a value.

The present invention forms a data line, a gate line, and the like including a thin film transistor on an upper substrate so that the linearly polarized back light passing through the lower substrate does not change and passes through the liquid crystal layer so that retardation does not occur. Accordingly, an object of the present invention is to provide a transverse electric field type liquid crystal display device and a method of manufacturing the same for improving image quality such as improving the C / R (Contrast Ratio) of the liquid crystal display device.

In order to achieve the above object, a transverse electric field type liquid crystal display device according to the present invention comprises: a first substrate; A gate line and a data line crossing the first substrate to define a pixel region; A thin film transistor connected to the gate line and the data line; A pixel electrode formed on the pixel region, connected to the thin film transistor, and having a plurality of vertical patterns; A common electrode having a plurality of vertical patterns arranged to be alternate with each vertical pattern of the pixel electrode; A color filter formed under the pixel electrode and the common electrode on the pixel area; A black matrix formed on the thin film transistor; A transparent second substrate disposed below the first substrate at predetermined intervals; And a liquid crystal layer formed between the first and second substrates.

Here, the pixel electrode and the common electrode formed on the first substrate are interviewed with the second substrate, and a liquid crystal layer is formed between the interviews, and the black matrix is an area including an upper portion of a gate line and a data line. Is also formed.

In addition, a polarizing plate is attached to the lower part of the second substrate, and the back light is incident to the lower part of the second substrate. That is, the first substrate is an upper substrate, and the second substrate is a lower substrate.

In addition, in order to achieve the above object, a method of manufacturing a transverse electric field type liquid crystal display device according to the present invention comprises the steps of: providing a first and a second substrate; Forming a gate line and a data line intersecting an upper portion of the first substrate and a thin film transistor connected to the gate line and the data line; Forming a color filter on the gate line, the data line, and the thin film transistor; Forming a pixel electrode connected to the thin film transistor on the color filter and having a plurality of vertical patterns, and a common electrode having a plurality of vertical patterns arranged to be alternate with each vertical pattern of the pixel electrode; Forming a black matrix on the thin film transistor; And flipping the first substrate, arranging a second substrate at a predetermined interval below the inverted first substrate, and forming a liquid crystal layer between the first and second substrates.

The black matrix may be formed in a region including the upper portion of the gate line and the data line, and the second substrate may be a transparent glass substrate.

According to the present invention, the back light passes through the liquid crystal layer first and then passes through the TFT or the color filter layer, thereby preventing the scattering of the light generated when passing through the layer or the changed light is delayed. / R is improved, and the lower substrate can be made of bare glass, which simplifies the process, reduces the material cost, and improves the yield.

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

4 is a cross-sectional view of a specific part of the transverse electric field type liquid crystal display device according to the present invention. However, this is a sectional view of the same portion as the cross section of the conventional liquid crystal display shown in FIG.

According to the present invention, a thin film transistor (TFT) formed on a lower substrate and a gate line, a data line, a pixel electrode, and a common electrode corresponding to the pixel electrode are formed on the upper substrate. Accordingly, the lower substrate is composed of a transparent glass substrate, that is, bare glass. As a result, the back light passing through the lower substrate does not pass through another layer such as TFT before passing through the liquid crystal layer, so that the linearly polarized light remains as it is. It is characterized by that the light does not feel retardation (retardation) in the liquid crystal layer.

Referring to FIG. 4, the lower substrate 300 is formed of a transparent glass substrate, and on the upper substrate 209 a TFT (S) in addition to the color filter 228, a BM (not shown), and an OC layer (not shown). The gate line / data line 213, the pixel electrode 217a, the common electrode 215a, and the like may be formed.

In more detail, the upper substrate 209 includes a plurality of gate lines (not shown) defining pixel regions 233 crossing each other on the substrate in the same manner as forming an array pattern on a conventional lower substrate. A data line 213, a TFT (S) formed at an intersection of the gate / data line, a pixel electrode 217a formed on the pixel area and connected to the TFT, and having a plurality of vertical patterns, and the The common electrode 215a is provided with a plurality of vertical patterns arranged alternately with each vertical pattern of the pixel electrode.

In addition, a BM (not shown), a color filter 228, and the like, which are formed on a conventional upper substrate, are also formed on the upper substrate.

Here, the color filter 228 has three colors of red, green, and blue arranged in sequence, and are manufactured by a method such as pigment dispersion, dyeing, electrodeposition, or printing, which correspond to each pixel area 233. It is formed below the pixel electrode 215a and the common electrode 217a on the pixel area.

In addition, the BM is formed in a predetermined region on the upper substrate such as an area including an upper TFT area and an upper gate / data line to prevent light leakage between the respective color filter patterns.

When all the components are formed on the upper substrate 209 as described above, the pixel electrode 217a, the common electrode 215a, and the like formed on the upper substrate are spaced apart from the upper substrate 209 by a predetermined interval. The lower substrate 300 is interviewed, and a liquid crystal layer 310 is provided therebetween.

According to the present invention, as shown, the arrangement of the liquid crystal 310 positioned on the lower substrate 300 is constant, unlike in the conventional case, so that the back light is linearly polarized in the lower portion of the lower substrate 300. (Back Light) can pass through the liquid crystal 310 layer without changing scattering or the like to overcome the occurrence of phase retardation. At this time, a polarizing plate (not shown) is attached to the lower portion of the lower substrate 300, whereby the back light incident from the lower portion of the lower substrate 300 is linearly polarized.

This lowers the brightness of black in Normally Black mode, which improves overall C / R.

5A to 5E are cross-sectional views showing the manufacturing process of the transverse electric field type liquid crystal display device according to the present invention. However, this is sectional drawing of the manufacturing process cut along the cross section of the part shown in FIG.

First, an upper substrate 209 and a lower substrate 300 are prepared. In this case, a transparent glass substrate is used as the substrate. In the present invention, a plurality of components are formed on the upper substrate, and the lower substrate is bare glass.

As shown in FIG. 5A, a conductive metal is deposited and patterned on the upper substrate 209 to form a gate line (not shown) and a gate electrode 219.

Next, an inorganic insulating material such as silicon nitride (SiNx) and silicon oxide (SiO ₂ ), or an acrylic resin, benzocyclobutene (BCB), etc., on the entire surface of the substrate 209 on which the gate line 211 is formed. The same organic insulating material is deposited to form the gate insulating layer 218.

Next, as shown in FIG. 5B, pure amorphous silicon (a-Si) and amorphous silicon (n + a-Si) containing impurities are stacked on the substrate on which the gate insulating layer 218 is formed, and then patterned to form an active layer. The layer 225 and the ohmic contact layer 227 are formed, and a conductive metal is deposited and patterned on the substrate on which the ohmic contact layer 227 is formed to form a data line 213, a source electrode 221, and a drain electrode 223. ).

Thereafter, a low dielectric material is deposited on the entire surface of the substrate on which the data line 213 and the source / drain electrodes 221 and 223 are formed to form an organic insulating layer 229, and then patterned to form the drain contact hole 231. And a hole 233 is formed in a portion of the pixel area P.

In general, the organic insulating layer 229 is formed by an exposure method using a photo mask, but is not limited thereto.

Here, the pixel area P refers to an area defined by the intersection of the gate line 211 and the data line 213.

Next, as illustrated in FIG. 5C, a color filter 228 is formed in the hole 233 formed in a portion of the pixel area. As described above, in forming the color filter, a method such as a pigment dispersion method, a dyeing method, an electrodeposition method, or a printing method may be used. Hereinafter, the color filter formation by the printing method will be described as an example.

In this case, as the printing method, an ink jet printing method, a gravure printing method, or the like may be used.

In the inkjet printing method, a nozzle having an opening having a predetermined size is positioned in a portion of the pixel region P on which the hole is formed, and color filter pigment is ejected through the nozzle to be stacked in the region.

At this time, the nozzle is provided with a valve for controlling the amount of the color filter pigment is ejected, it is possible to laminate the desired amount of color filter pigment on the substrate. Since the nozzle proceeds at a constant speed on the substrate, it is possible not only to stack the color filter pigments throughout the substrate, but also to stack the color filter pigments only at desired positions by adjusting the valves.

In addition, gravure printing is a printing method in which an excess of ink is scraped off and printed on the cliché. Since gravure printing transfers color filter pigments onto a substrate using a transfer roll, a color filter pattern can be formed by one transfer even in the case of a large area substrate by using a transfer roll corresponding to the area of the substrate. .

When the color filter pattern is formed by a printing method such as inkjet or gravure, the cell spacer uniformity is excellent due to the planarization structure of the organic insulating layer and the color filter pattern. ), The occurrence of distortion of the liquid crystal array such as rubbing scratches or disclination is eliminated.

Next, FIG. 5D illustrates a process of forming the common electrode 215 and the pixel electrode 217 by depositing and patterning a transparent conductive metal such as indium tin oxide (ITO) and indium zinc oxide (IZO). The common electrode 215 and the pixel electrode 217 including the finger-shaped common electrode vertical pattern 215a and the pixel electrode vertical pattern 217a that are spaced apart from each other by a predetermined interval are formed.

Here, the pixel electrode 217 is formed on the pixel region P, and includes a plurality of vertical patterns 217a and a horizontal pattern 217b connecting the plurality of vertical patterns 217a to one, The common electrode 215 is disposed on the same layer as the pixel electrode 217, and the plurality of vertical patterns 215a and the plurality of vertical patterns that are alternately arranged with each vertical pattern 217a of the pixel electrode 217. It is formed to include a horizontal pattern 215b connecting the pattern 215a as one.

In addition to the formation of the pixel electrode and the common electrode, a BM should be formed. The BM may also be formed by various methods such as the formation of a color filter.

The BM is formed in a predetermined region on the upper substrate, such as an area including a TFT upper region and an upper portion of the gate / data line, between each color filter pattern and to prevent light leakage. By forming the formed organic insulating layer 229 as a colored component, it can be used as a BM.

Next, as shown in 5e, the prepared upper substrate 209 is inverted, and the brae glass as the lower substrate 300 is disposed at a predetermined interval below the inverted upper substrate 209, and the upper portion The liquid crystal 310 layer is formed between the substrate 209 and the lower substrate 300.

According to the present invention, as shown, the liquid crystal 310 layer positioned on the lower substrate 300 has a constant arrangement, and thus back light is linearly polarized in the lower portion of the lower substrate 300. By passing through the liquid crystal layer 310 without changing the scattering or the like, it is possible to overcome the occurrence of phase retardation.

The embodiments of the present invention described above are merely illustrative for explaining the transverse electric field type liquid crystal display device and a method of manufacturing the same according to the present invention, and those skilled in the art have various and equivalent examples therefrom. I understand that it is possible. Therefore, the true scope of the present invention will be defined by the claims.

As described above, according to the transverse electric field type liquid crystal display device and a manufacturing method thereof, the light generated when the back light passes through the liquid crystal layer first and then passes through the TFT or color filter layer to pass through the layer There is an advantage to improve the C / R of the liquid crystal display by preventing the scattering of the light or the changed light is delayed.

In addition, since the lower substrate can be made of bare glass, the process can be simplified, and material cost reduction and yield can be improved.

1 is a partial plan view of a lower substrate of a conventional IPS mode LCD.

2A to 2C are cross-sectional views of the manufacturing process taken along the lines II and II of FIG. 1.

Figure 3 is a cross-sectional view of the lower substrate and the corresponding upper substrate cut along the II, II-II of FIG.

4 is a cross-sectional view of a specific portion of the transverse electric field type liquid crystal display device according to the present invention;

5A to 5E are cross-sectional views illustrating a manufacturing process of a transverse electric field type liquid crystal display device according to the present invention.

<Explanation of symbols for the main parts of the drawings>

209: upper substrate 300: lower substrate

310: liquid crystal

Claims (8)

The first substrate, A gate line and a data line crossing the first substrate to define a pixel area; A thin film transistor connected to the gate line and the data line; A pixel electrode formed on the pixel region, connected to the thin film transistor, and having a plurality of vertical patterns;  A common electrode having a plurality of vertical patterns arranged to be alternate with each vertical pattern of the pixel electrode; A color filter formed under the pixel electrode and the common electrode on the pixel area; A black matrix formed on the thin film transistor, A transparent second substrate disposed at a predetermined interval below the first substrate; And a liquid crystal layer formed between the first and second substrates. The method of claim 1, The pixel electrode and the common electrode formed on the first substrate are in contact with the second substrate, and a liquid crystal layer is formed between the interviews. The method of claim 1, And the black matrix is also formed in an area including the upper portion of the gate line and the data line. The method of claim 1, And a polarizing plate is attached to a lower portion of the second substrate. The method of claim 4, wherein And a rear light is incident on the lower portion of the second substrate. Providing first and second substrates, Forming a gate line and a data line intersecting an upper portion of the first substrate, and a thin film transistor connected to the gate line and the data line; Forming a color filter on the gate line, the data line, and the thin film transistor; Forming a pixel electrode connected to the thin film transistor on the top of the color filter and having a plurality of vertical patterns and a common electrode having a plurality of vertical patterns that are alternately arranged with each of the vertical patterns of the pixel electrode; Forming a black matrix on the thin film transistor; And flipping the first substrate, arranging a second substrate at a predetermined interval below the inverted first substrate, and forming a liquid crystal layer between the first and second substrates. Method of manufacturing a liquid crystal display device. The method of claim 6, And the black matrix is formed in a region including an upper portion of a gate line and a data line. The method of claim 6, And said second substrate is a transparent glass substrate.