KR100646796B1 - A liquid crystal display - Google Patents

Abstract

In a liquid crystal display substrate, a color filter is formed on a transparent substrate, a transparent electrode is formed on the color filter, and a black matrix is formed on the transparent electrode. At this time, the black matrix is formed in a shape that can serve as a protrusion. On the black matrix, the photoresist used in the formation of the black matrix is left to function as a main protrusion. In this case, since the photoresist pattern used in the process of forming the black matrix is used as a projection, a separate process for forming the projection is not required.

LCD, Black Matrix, Redundant Wiring, Projection, Conductive Particles

Description

Liquid crystal display device {A LIQUID CRYSTAL DISPLAY}

1 is a cross-sectional view of a liquid crystal display device according to a first embodiment of the present invention;

2 is a cross-sectional view of a liquid crystal display device according to a second embodiment of the present invention;

FIG. 3 is an electro-optical simulation showing the change in arrangement of liquid crystals over time when the protrusion is conductive (left) and the ideal insulator (right).

4A to 4C are cross-sectional views sequentially illustrating a process of manufacturing an upper substrate of a liquid crystal display according to a second exemplary embodiment of the present invention.

5 is a layout view of a liquid crystal display according to a third exemplary embodiment of the present invention.

FIG. 6 is a cross-sectional view taken along line VI-VI ′ of FIG. 5;

7 is a layout view of a liquid crystal display according to a fourth exemplary embodiment of the present invention.

FIG. 8 is a cross-sectional view taken along line VII-VII 'of FIG. 7.

The present invention relates to a liquid crystal display device, and more particularly, to a thin film transistor substrate for a liquid crystal display device.

In general, a liquid crystal display device injects a liquid crystal material between an upper substrate on which a common electrode and a color filter are formed, and a lower substrate on which a thin film transistor and a pixel electrode are formed. By applying different potentials to form an electric field to change the arrangement of the liquid crystal molecules, and through this to control the light transmittance is an apparatus that represents the image.

However, it is an important disadvantage that the liquid crystal display device has a narrow viewing angle. In order to overcome these disadvantages, various methods for widening the viewing angle have been developed. Among them, liquid crystal molecules are oriented vertically with respect to the upper and lower substrates, and a method of forming a constant opening pattern or forming protrusions on the pixel electrode and the common electrode opposite thereto is performed. Alternatively, a method of forming the opening pattern and the projection together is influential. These methods are described in A New Design to Improve Performance and Simplify the Manufacturing Process of High-Quality MVA TFT-LCD Panels (Y. Tanaka et al., 1999 SID, 16.5L) and Ridge and Fringe-Field Multi-Domain Homeotropic LCD (A. Lien et al., 1999 SID, 44.1L) (hereinafter referred to as " SID ").

However, when a process is added to form an opening pattern and a protrusion, there is a problem of lowering productivity. Therefore, it is necessary to find a method that can form protrusions without adding a process. In addition, it should be possible to form a projection that can fulfill the necessary functions for forming the projection, that is, to secure a wide viewing angle.

On the other hand, the thin film transistor substrate is provided with a gate line for transmitting a scan signal and a data line for transmitting an image signal. These wirings are often disconnected during the manufacturing process of the thin film transistor substrate. To prevent this, redundant wiring is formed. In the case of data wiring, redundant data wiring is formed by forming a transparent electrode layer pattern along the data line at the time of pixel electrode formation. The redundant data line is connected to the data line through a contact hole formed on the data line at the time of forming the contact hole for connecting the drain electrode and the pixel electrode.

However, when the conductive particles are positioned between the exposed redundant data line and the common electrode of the upper substrate, the short-circuiting of the conductive particles may be caused. This problem also exists in the case of forming an opening pattern or forming a projection in order to secure a wide viewing angle.

The technical problem to be achieved by the present invention is to prevent a short circuit between the upper and lower substrates.

In order to solve this problem, the present invention uses a black matrix as a projection.

Specifically, a transparent electrode is formed on the insulating substrate, and a black matrix is formed on the transparent electrode so as to have a function that can also function.

At this time, a main protrusion made of a photosensitive film may be further formed on the black matrix.

A substrate for a liquid crystal display device having such a structure includes forming a transparent electrode, laminating a black matrix layer, laminating a photoresist film on the black matrix layer, patterning the photoresist film, and using the patterned photoresist film as an etching mask. It is prepared through a process comprising the step of etching the layer.

In order to solve the other problem of the present invention, a protrusion made of an insulating material is formed at a position corresponding to the redundant data wiring on the common electrode.

Specifically, a gate line for transmitting a scan signal is formed on the first substrate, is insulated from and crosses the data line gate line for transmitting an image signal, and a pixel electrode is formed in an area where the gate line and the data line cross each other. have. The redundant data line is formed on the same layer as the pixel electrode, and a switching element for transmitting or blocking the image signal to the pixel electrode in accordance with the scanning signal is connected to the gate line, the data line and the pixel electrode. A liquid crystal having a structure in which an insulating second substrate faces the first substrate, a common electrode is formed on the second substrate, and a projection pattern made of an insulating material is formed in at least a region corresponding to the redundant data line on the common electrode. Provide a display device.

In this case, the protrusion pattern may be an organic black matrix, and may further include a black matrix formed between the second substrate and the common electrode, and the pixel electrode may have an opening pattern. Preferably, the projection pattern and the opening pattern of the pixel electrode divide the pixel electrode into four domains, and the domain is preferably a polygon in which two longest sides are parallel to each other, and the domain is a first domain in which the longest two sides are the first direction. And a second domain which is a second direction, and the first direction and the second direction may form an angle between 85 ° and 95 °. The first direction may be an oblique direction with respect to the side of the pixel electrode, and the liquid crystal material injected between the first substrate and the second substrate may be a vertically aligned or twisted nematic liquid crystal.

Next, a structure of a thin film transistor substrate for a liquid crystal display according to an exemplary embodiment of the present invention will be described with reference to the drawings.

1 is a cross-sectional view of a liquid crystal display according to a first exemplary embodiment of the present invention.

The liquid crystal display device is largely composed of the upper substrate 200, the lower substrate 100, and the liquid crystal layer 300. In addition, a polarizing plate (not shown), a compensation plate (not shown), a light guide plate (not shown), and the like are also included, but description is omitted.

Although only the gate insulating layer 130, the data line 162, the protective insulating layer 180, and the pixel electrode 170 are illustrated on the lower substrate 100, all elements formed on the thin film transistor substrate such as a gate line and a thin film transistor are also shown. It contains them. Here, the opening 171 of a predetermined pattern is formed in the pixel electrode 170. The shape of the opening 171 may have various shapes as long as the pixel area may be divided into various types of micro domains together with protrusions of the upper substrate 200 to be described later. For example, chevron type, morning glory type, T type, etc. are mentioned. The types of the micro domains are classified according to the direction of the average director of the liquid crystal molecules contained therein.

The upper substrate 200 has red, green, and blue color filters 210 formed in each pixel area on the surface thereof. A common electrode 220 made of a transparent conductive material such as indium tin oxide (ITO) is formed on the color filter 210, and a photoresist such as a black dye (graphite powder) is added on the common electrode 220. The protrusions formed of the organic black matrix 230 are formed. The planar arrangement of the protrusions may also be variously changed, such as the shape of the opening 171 of the pixel electrode 170. However, it is preferable to arrange so that at least 4 types or more of micro domains can be formed in harmony with the shape of the opening part 171.

In the upper substrate 200 for the liquid crystal display device having such a structure, the protrusions are formed together in a process of forming a black matrix to prevent light leakage, and thus a separate process is not required to form the protrusions, and the lower substrate 100 may be used. The process of forming the opening 171 in the pixel electrode 170 may also proceed together in the process of forming the pixel electrode 170.

2 is a cross-sectional view of a liquid crystal display according to a second exemplary embodiment of the present invention.

The structure of the lower substrate 100 of the liquid crystal display according to the second embodiment of the present invention is the same as that of the first embodiment.

The upper substrate 200 has red, green, and blue color filters 210 formed in each pixel area on the surface thereof. The common electrode 220 made of a transparent conductive material such as indium tin oxide (ITO) is formed on the color filter 210, and inorganic materials such as chromium oxide (CrOx) and chromium (Cr) are formed on the common electrode 220. A black matrix 230 made of an organic material such as a photosensitizer added with a black pigment is formed. In this case, when the black matrix 230 is formed of a conductor such as chromium, there is an additional advantage of reducing the sheet resistance of the common electrode 220. In addition, when the black matrix is formed of a double layer of chromium and chromium oxide, the reflection of light may be reduced to improve image quality. When the black matrix 230 is formed as a double layer, chromium has a thickness of 0.05 μm to 0.3 μm and chromium oxide is preferably 0.03 μm to 0.2 μm. A projection pattern formed of the photosensitive film 250 is formed on the black matrix 230. The projection pattern is disposed between the opening patterns 171 of the pixel electrode 170.

As described above, when the protrusion pattern is formed of the photoresist film 250, the protrusion pattern may be formed together in the process of forming the black matrix 230, so that a process may not be added to form the protrusion. In addition, since the photoresist film 250 has excellent insulation properties, it can faithfully function as a projection for domain division. If the projection has low insulation, that is, the projection is conductive, the electric field formed around the pixel electrode 170 and the common electrode 220 does not function properly as an insulation protrusion when the voltage is applied, thereby distorting the image quality of the liquid crystal display device. You will lose your talent. For reference, the resistivity of the photosensitive agent is 1013 Ωcm or more.

3 shows the results of simulating the equipotential lines and the arrangement of the liquid crystal molecules according to the case where the protrusion is a conductor and the ideal insulator. Figure 6 also shows a curve showing the change in light transmittance with time after voltage application.

As shown in FIG. 3, in the insulation protrusion (right), the light transmittance is low only in the protruding portion and a high transmittance in the other portion after a predetermined time after voltage application. However, in the conductor protrusion (left), a portion having low transmittance appears in a large area around the protrusion in addition to the protrusion even after a certain time passes after the voltage is applied. That is, the texture will appear.

A method of manufacturing the upper substrate in the liquid crystal display device having such a structure will be described with reference to the drawings.

4A to 4C are cross-sectional views sequentially illustrating a process of manufacturing an upper substrate of a liquid crystal display according to a second exemplary embodiment of the present invention.

First, as shown in FIG. 4A, the color filter 210 is formed on a transparent insulating substrate 200 such as glass by using screen printing or the like.

Next, as illustrated in FIG. 4B, a transparent conductive material such as ITO is deposited on the color filter 210 to form a common electrode 220. Although not illustrated, an overcoat layer may be formed on the color filter 210, and then the common electrode 220 may be formed on the overcoat layer. Subsequently, the black matrix 230 is laminated by depositing a single layer of chromium or a double layer of chromium and chromium oxide, or by applying a photosensitive agent to which black pigment is added, and then applying a photosensitive film 250 thereon.

Next, as shown in FIG. 4C, the photoresist film 250 is exposed and developed to form a necessary pattern, and the black matrix 230 below is etched using the photoresist 250 pattern as an etch mask. Therefore, the projection pattern formed of the black matrix 230 and the photosensitive film 250 has the same layout. That is, the black matrix 230 and the photosensitive film 250 are self aligned.

As described above, in the second embodiment of the present invention, since the photosensitive film 250 pattern used in the process of forming the black matrix 230 is used as a protrusion, a separate process for forming the protrusion is not required.

FIG. 5 is a layout view of a liquid crystal display according to a third exemplary embodiment of the present invention, and FIG. 6 is a cross-sectional view taken along line VI-VI ′ of FIG. 5.

The gate line 122 and the storage electrode line 127 extend in the horizontal direction on the lower substrate 100. The gate insulating layer 130 is formed on the gate line 122 and the storage electrode line 127. A semiconductor layer 142 of a thin film transistor as a switching element is formed on the gate insulating layer 130, and a contact layer (not shown) is formed on the semiconductor layer 142. The data line 162 is formed in the vertical direction on the gate insulating layer 130. A source electrode 165 is formed in the data line 162 as a branch, and a drain electrode 166 facing the source electrode 165 is formed separately from the source electrode 165. The source electrode 165 and the drain electrode 166 extend over the contact layer. A protection having a contact hole 181 exposing the drain electrode 166 and a contact hole 182 exposing the data line 162 on the data line 162, the source electrode 165, the drain electrode 166, and the like. An insulating film 180 is formed. The redundant data line 172 is formed along the data line 162 and the pixel electrode 170 having the opening pattern 171 on the passivation insulating layer 180 and connected to the data line 162 through the contact hole 182. ) Is formed. The redundant data line 172 is formed of the same material as the pixel electrode 170. The opening pattern 171 of the pixel electrode 170 is formed in a cross shape (+). However, as described below, the opening pattern 171 may be formed in various shapes.

The red, green, and blue color filters 210 are formed on the lower surface of the upper substrate 200, and the common electrode 220 is formed on the entire surface of the substrate 200 on the color filters 210. The common electrode 220 is made of a transparent conductive material such as indium tin oxide (ITO). The black matrix 230 is formed on the common electrode 220. At this time, the black matrix 230 is formed in at least both of the redundant data lines 172 and the corresponding regions. The black matrix 230 serves to block leakage of light as an insulating layer and to prevent short circuit between the redundant data line 172 and the common electrode 220 together with a function of a projection affecting the alignment of the liquid crystal molecules. The black matrix 230 is formed of an insulating material with a thickness between 0.1 μm and 3 μm.

In this case, the color filter 210 may be formed on the lower substrate 100 instead of the upper substrate 200.

The liquid crystal material is injected between the upper and lower substrates 100 and 200 to form the liquid crystal layer 300. The liquid crystal molecules of the liquid crystal layer 300 are aligned such that their major axes are perpendicular to the substrates 100 and 200 without an electric field applied thereto.

When the liquid crystal display is manufactured, an electric field is formed between the upper and lower substrates 100 and 200 by a protrusion formed by the opening pattern 171 of the lower substrate 100 and the black matrix 230 of the upper substrate 200. It has a certain direction with respect to (100, 200). At this time, the projections contribute to the deformation of the electric field due to the difference in dielectric constant with the liquid crystal layer 300. The projections also affect the initial alignment state of the liquid crystal molecules, so that the liquid crystal molecules near the projections are inclined to some extent even when the electric field is not applied.

The direction in which the liquid crystal molecules are inclined has a certain direction in each domain formed by overlapping the opening pattern 171 and the black matrix 230. When domains are classified based on the average long axis direction of liquid crystal molecules in each domain, the domains are classified into four types, one for each of four directions. Due to the orientation of the liquid crystal molecules in the domain, a wide viewing angle is secured in all four directions.

In addition, since the black matrix 230, which is an insulating material, is formed at a portion corresponding to the redundant data line 172, even when the conductive particles P are placed on the redundant data line 172, the black matrix 230 is a redundant data line ( The short circuit of 172 and the common electrode 220 is blocked.

FIG. 7 is a layout view of a liquid crystal display according to a fourth exemplary embodiment of the present invention, and FIG. 8 is a cross-sectional view taken along the line 'VIII' of FIG. 7.

The arrangement of the lower substrate 100 is almost the same as the lower substrate 100 of the third embodiment of the present invention. However, the shape of the opening pattern 171 formed in the pixel electrode 170 is different as will be described later.

The black substrate 230 is formed on the surface of the upper substrate 200, and the red, green, and blue color filters 210 are formed in the pixel area partitioned by the black matrix 230. The common electrode 220 made of a transparent conductive material such as indium tin oxide (ITO) is formed on the black matrix 230 and the color filter 210, and the protrusion pattern 240 made of an insulating material is formed on the common electrode 220. ) Is formed. The protruding pattern 240 is formed in all regions corresponding to the redundant data line 172 and is formed of an organic or inorganic insulating material.

The protrusion patterns 240 of the upper substrate 200 are disposed on upper and lower portions of the horizontal and half pixel electrodes 170 that are formed in the horizontal direction at positions half of the lower and upper pixel electrodes 170 of the lower substrate 100. Each includes an oblique line portion formed in an oblique direction. At this time, the upper and lower diagonal portions are perpendicular to each other. This is to evenly distribute the inclined direction of the electric field in four directions.

The opening pattern 171 formed in the pixel electrode 170 includes an oblique portion of the protrusion pattern 240 in the center and includes a diagonal opening parallel to the left and a vertical opening parallel to the left and right sides of the pixel electrode 170.

The protrusion pattern 240 and the opening pattern 171 of the pixel electrode 170 overlap each other to divide the pixel electrode 170 into a plurality of domains. At this time, each domain forms a polygon in which the two longest sides are parallel to each other. This is for shortening the response time of the liquid crystal molecules. That is, the direction in which the liquid crystal molecules are arranged by the inclined electric field formed by the protrusion pattern 240 and the opening pattern 171 is in a state where the liquid crystal molecules are parallel to each other. In this case, the response time is shortened because the operation of the liquid crystal molecules is completed by only one step operation.

Since the projection pattern 240, which is an insulating material, is formed at a portion corresponding to the redundant data line 172, the projection pattern 240 may be formed on the redundant data line 172 even if the conductive particles P are placed on the redundant data line 172. ) And the common electrode 220 are blocked from being shorted.

In the second embodiment, an insulating film is formed separately from the protrusion pattern 240, but as in the first embodiment, the black matrix 230 is formed on the common electrode 220 to replace the protrusion pattern. In addition, the shape of the protrusion pattern 240 and the opening pattern 171 may be variously modified.

The third and fourth embodiments describe a vertical alignment mode liquid crystal display in which liquid crystal molecules are vertically aligned with respect to the upper and lower substrates, but a black matrix or a separate insulating material is formed along a portion corresponding to the redundant data line on the common electrode. The present invention, which forms a short circuit between the redundant data line and the common electrode, can be applied to a twisted nematic (TN) mode liquid crystal display device.

As described above, since the photosensitive film pattern used in the process of forming the black matrix is used as a projection, a separate process for forming the projection is not required. Further, by forming a projection pattern made of a black matrix or a separate insulating material along a portion corresponding to the redundant data line on the common electrode, a wide viewing angle is ensured and a short circuit between the redundant data line and the common electrode is prevented.

Claims (10)

Insulating first substrate, A gate line formed on the first substrate and transmitting a scan signal; A data line insulated from and intersecting the gate line and transferring an image signal; A pixel electrode formed in an area where the gate line and the data line cross each other; Redundant data lines formed on the same layer as the pixel electrode; A switching element connected to the gate line, the data line, and the pixel electrode and configured to transfer or block the image signal to the pixel electrode according to the scan signal; An insulating second substrate facing the first substrate, A common electrode formed on the second substrate, A projection pattern formed of an insulating material and formed in at least a region corresponding to the redundant data line on the common electrode. Liquid crystal display comprising a. In claim 1, The protrusion pattern is an organic black matrix. In claim 1, And a black matrix formed between the second substrate and the common electrode. In claim 1, The pixel electrode has an opening pattern. In claim 4, The projection pattern and the opening pattern of the pixel electrode divide the pixel electrode into four domains. In claim 5, The domain has a polygonal shape, and the two longest sides of the polygon are parallel to each other. In claim 6, The domain includes a first domain and a second domain, The first domain has two longest sides in a first direction, The second domain has two longest sides in a second direction, And the first direction and the second direction form an angle between 85 ° and 95 °. In claim 7, And the first direction is a diagonal direction with respect to the side of the pixel electrode. In claim 1, And a liquid crystal material injected between the first substrate and the second substrate and oriented perpendicular to the first and second substrates without an electric field applied thereto. In claim 1, And a twisted nematic liquid crystal material injected between the first substrate and the second substrate.

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