KR20060128416A - Mva mode liquid crystal display device and method of fabrication thereof - Google Patents

Abstract

An MVA(Multi-domain Vertical Alignment) mode LCD and a fabricating method thereof are provided to form additional common electrodes in the shape of slit patterns, which is formed in main common electrodes, thereby obtaining a narrow viewing angle by applying a same signal to the both common electrodes and obtaining a wide viewing angle by applying the signal to the main common electrodes. An MVA mode LCD includes first and second substrates facing each other and joined with each other with a predetermined distance for forming a liquid crystal layer. TFTs(Thin Film Transistors) are formed on intersections between gate and data lines(102,120) formed on the first substrate. Pixel electrodes(126) are formed on pixel areas(P) and have slit patterns(S1). First common electrodes(202) are formed on a surface of the second substrate and have slit patterns(S2) at a position apart from the slit patterns of the pixel electrodes. Second common electrodes(206) are formed at an upper or lower part of the first common electrodes in the same shape with the slit patterns of the first common electrodes.

Description

Multi-domain vertical alignment mode liquid crystal display and a method of manufacturing the same {MVA mode liquid crystal display device and method of fabrication

1 is a perspective view schematically showing a general liquid crystal display device.

FIG. 2 is an enlarged plan view illustrating a simplified enlarged display of one pixel of a conventional MVA mode liquid crystal display; FIG.

3 is an enlarged cross-sectional view taken along the line II-II of FIG. 2;

FIG. 4 is an enlarged plan view illustrating an enlarged view of one pixel of the MVA mode LCD according to the present invention; FIG.

FIG. 5A illustrates the movement of liquid crystal when a common signal is applied to only the first common electrode. FIG. 5B illustrates the movement of liquid crystal when a common signal is simultaneously applied to the first common electrode and the second common electrode. One drawing.

6A through 6D are cross-sectional views of an array substrate for a multi-domain mode liquid crystal display device taken along the line IV-IV of FIG. 4 in accordance with the process sequence of the present invention.

7A to 7B are process cross-sectional views of the color filter substrate for the MVA mode liquid crystal display device taken along the line VV of FIG. 4 according to the process sequence of the present invention.

8 is an enlarged cross-sectional view schematically illustrating an enlarged pixel of an MVA mode liquid crystal display according to another exemplary embodiment of the present invention.

<Brief description of the main parts of the drawing>

102 gate wiring 104 gate electrode

108,110 semiconductor layer 116 source electrode

118: drain electrode 120: data wiring

126: pixel electrode 202: first common electrode

206: second common electrode S1, S2: slit pattern

The present invention relates to a liquid crystal display device, and a multi-domain vertical alignment (MVA) mode liquid crystal display device capable of realizing both a wide viewing angle and a narrow viewing angle, and a manufacturing method thereof.

In general, the driving principle of the liquid crystal display device uses the optical anisotropy and polarization of the liquid crystal. Since the liquid crystal is thin and long in structure, the liquid crystal has directivity in the arrangement of molecules, and the direction of the molecular arrangement can be controlled by artificially applying an electric field to the liquid crystal.

Accordingly, when the molecular arrangement direction of the liquid crystal is arbitrarily adjusted, the molecular arrangement of the liquid crystal is changed, and the polarization state of light is changed in the molecular arrangement direction of the liquid crystal by optical anisotropy, thereby representing image information.

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

1 is a perspective view schematically illustrating a general liquid crystal display device.

As shown in the drawing, a general liquid crystal display device 51 includes a black matrix 6 and color filters 7a, 7b, and 7c, and is disposed below the black matrix and color filters 6,7a, 7b, and 7c. An upper substrate 5 on which the common electrode 9 is formed, and a lower substrate on which the array wirings 12 and 24 including the pixel region P and the pixel electrode 17 and the switching element T formed on the pixel region are formed. 22) and a liquid crystal (11) is filled between the upper substrate (5) and the lower substrate (22).

The lower substrate 22 is also referred to as an array substrate. The thin film transistor T, which is a switching element, is positioned in a matrix type, and the gate wiring 12 and the data wiring 24 passing through the plurality of thin film transistors cross each other. ) Is formed.

The pixel area P is an area defined by the gate wiring 12 and the data wiring 24 intersecting with each other. The pixel electrode 17 formed on the pixel region P uses a transparent conductive metal having relatively high light transmittance, such as indium-tin-oxide (ITO).

In the liquid crystal display configured as described above, the thin film transistor T and the pixel electrode 17 connected to the thin film transistor are present in a matrix to display an image.

The gate wiring 12 transmits a pulse voltage driving the gate electrode 30, which is the first electrode of the thin film transistor T, and the data wiring 24 includes a source and a source of the thin film transistor T. The data signal is transmitted to the pixel electrode 17 through the drain electrodes 34 and 36.

In this case, a drain electrode 36 spaced apart from the source electrode 34 and connected to the pixel electrode 17 is formed, and an active layer 32 is formed under the source and drain electrodes 34 and 36.

In the liquid crystal display device fabricated as described above, various studies have been conducted to implement a wide viewing angle and high brightness.

The method of widening the viewing angle includes a multi-domain technique and a phase difference in which a pixel is divided into several regions so that the orientation of liquid crystal molecules is changed in each region so that the characteristics of the pixels become the average of the characteristics of the various regions contained therein. Phase compensation technology to reduce the phase difference change with the change of viewing direction by using film And a vertical alignment mode using a liquid crystal (negative LC).

Among the above-described methods, a multidomain technique using liquid crystals having negative dielectric anisotropy will be described with reference to the drawings below.

FIG. 2 is an enlarged plan view schematically illustrating an enlarged pixel of a typical MVA mode liquid crystal display device.

As illustrated, the MVA mode liquid crystal display 40 includes a gate line 42 and a data line 52 crossing the first substrate (not shown) to define the pixel region P. As shown in FIG.

The thin film transistor T including the gate electrode 44, the semiconductor layer 46, the source electrode 48, and the drain electrode 50 is formed at the intersection point of the gate wiring 42 and the data wiring 52. .

In the pixel region P, a pixel electrode 54 in contact with the drain electrode 50 is configured. In this case, the pixel electrode 54 is a slit S1 having a square shape << for the purpose of distorting an electric field. The pixel electrode is removed).

The second substrate (not shown) spaced apart from the first substrate (not shown) configured as described above corresponds to the pixel electrode 54 having the slits S1 formed therein, and the square slits S2 are formed. The configured common electrode 70 is configured.

In this case, the slit S2 of the common electrode 70 may be configured to correspond to the pixel electrode 54 in which the slit S1 does not exist, and the slit S1 of the pixel electrode 54 may be planarly formed. The shapes are spaced parallel to the same shape.

In this manner, a region between the pixel electrode 54 and the slit S2 patterned on the common electrode 70 forms one domain.

Therefore, as the number of slits S1 and S2 formed in the pixel electrode and the common electrode 54 and 70 increases, regions may be further divided to form a multi-domain, thereby realizing a wide viewing angle. do.

This will be described below with reference to FIG. 3.

3 is a cross-sectional view taken along the line II-II of FIG. 2.

As illustrated, the MVA mode liquid crystal display device 50 includes a pixel electrode 54 having a slit S1 patterned on a first substrate G1, and a second spaced apart from the first substrate G1. The common electrode 70 in which the slit S2 is formed on the substrate G2 is configured.

In this case, the slit S1 patterned on the pixel electrode 54 and the slit S2 patterned on the common electrode 70 are configured to be spaced apart in parallel in a plane.

In this case, distortion of an electric field occurs symmetrically around each of the slits S1 and S2, and the liquid crystal LC positioned in the same region of the electric field distortion has the characteristic of being oriented in the same direction.

Therefore, since the light passing through the liquid crystal located in the areas A1 and A2 symmetrical to each other is compensated for each other, color inversion does not appear during side observation, thereby realizing a wide viewing angle.

However, in recent years, it is required not only to implement a wide viewing angle but also to have a narrow viewing angle (narrow viewing angle) function that allows only a user to see it when dealing with privacy protection or confidential documents.

The present invention has been proposed to meet such a demand, and an object of the present invention is to manufacture an MVA mode liquid crystal display device capable of simultaneously implementing a wide viewing angle and a narrow viewing angle.

According to an aspect of the present invention, there is provided a multi-domain vertical alignment mode liquid crystal display device including: a first substrate and a second substrate, each of which includes a plurality of pixel regions and is bonded to be spaced apart from each other; Gate wiring and data wiring intersecting on said first substrate; A thin film transistor configured at an intersection point of the gate line and the data line; A pixel electrode positioned in the pixel area and including a slit pattern; A first common electrode formed on one surface of the second substrate and including a slit pattern planarly spaced from the slit pattern of the pixel electrode; And a second common electrode having the same shape as the slit pattern of the first common electrode.

The slit pattern of the pixel electrode, the first common electrode, and the second common electrode may have a square shape (<).

The first common electrode and the second common electrode are positioned with an insulating layer (color filter layer) interposed therebetween.

According to another aspect of the present invention, there is provided a method of manufacturing a multi-domain liquid crystal display device, comprising: preparing a first substrate and a second substrate; Forming a gate line and a data line crossing the first substrate to define a pixel area; Forming a thin film transistor at an intersection point of the gate line and the data line; Forming a pixel electrode including a slit pattern in the pixel region; Forming a first common electrode including a slit pattern at a position spaced apart from the slit pattern of the pixel electrode on one surface of the second substrate; And forming the second common electrode in the same shape as the slit pattern of the first common electrode.

The slit pattern of the pixel electrode, the first common electrode, and the second common electrode may be square.

An insulating film is further included between the first common electrode and the second common electrode.

Hereinafter, with reference to the drawings will be described a preferred embodiment according to the present invention.

Example

A feature of the present invention is to propose a second common electrode having a slit pattern patterned to realize both a wide viewing angle and a narrow viewing angle, and a dual common electrode structure constituting the first common electrode having the same shape in a portion corresponding to the slit. Characterized in that.

4 is an enlarged plan view schematically showing the configuration of one pixel of the MVA mode liquid crystal display according to the present invention.

As shown in the drawing, the multi-domain liquid crystal display device 99 according to the present invention forms a gate line 102 and a data line 120 that define a pixel region P across the first substrate (not shown). .

The gate electrode 104 and the semiconductor layer (active layer 108, ohmic contact layer 110), the source electrode 116 and the drain electrode 118 at the intersection of the gate wiring 102 and the data wiring 120 It constitutes a thin film transistor (T) consisting of.

A pixel electrode 126 in contact with the drain electrode 116 is formed in the pixel region P, and a slit pattern S1 having a square shape is formed in the pixel electrode 126.

The second substrate (not shown) spaced apart from the first substrate (not shown) has a square slit pattern S2 that is the same in a region spaced apart in parallel with the slit pattern S1 of the pixel electrode 126 in plan view. This constructed second common electrode 206 is constituted.

In addition, the first common electrode 202 is formed in the same shape as the slit pattern S2 of the second common electrode 206 above or below the second common electrode 206.

In this case, each of the common electrode and the pixel electrode is configured as a single body although not shown in the drawing.

In this configuration, when a signal is applied only to the second common electrode 206, a wide viewing angle can be realized, and a common signal is simultaneously applied to the first common electrode 202 and the second common electrode 206. This will allow you to implement the desired narrow viewing angle.

This will be described below with reference to FIGS. 5A and 5B.

5A is a diagram illustrating a liquid crystal movement when the common signal is applied only to the second common electrode including the slit, and FIG. 5B is a diagram when the common signal is simultaneously applied to the second common electrode and the first common electrode including the slit. , Which shows the motion of the liquid crystal.

As shown in FIG. 5A, in the multi-domain liquid crystal display 99 according to the present invention, a pixel electrode 126 having a slit S1 patterned on a first substrate 100 is formed, and the first substrate ( The first common electrode having the same shape corresponding to the second common electrode 206 having the slit S2 formed on the second substrate 200 spaced apart from the 100, and the slit S2 of the second common electrode 206. 202 is configured.

In this case, the slit S1 patterned in the pixel electrode 126 and the slit S2 patterned in the common electrode 206 are configured to be spaced apart in parallel in a plane.

In the above configuration, when the common signal is applied only to the second common electrode 206, the electric field 300 is generated only between the first common electrode 202 and the lower pixel electrode 126, and the electric field 300 is applied. Is symmetrically distorted around the slits S2 and S1 of the second common electrode and the pixel electrodes 206 and 126.

Accordingly, the liquid crystal LC is also aligned in a symmetrical direction with respect to the slits S2 and S1 of the second common electrode 206 and the pixel electrode 126.

However, as shown in FIG. 5B, when a common signal is applied to both the first common electrode 202 and the second common electrode 206, the slit S1 patterned on the first common electrode 202. Cannot function properly by the second common electrode 206.

That is, since the vertical electric field 310 is normally generated in the slit S2, the distortion of the electric field occurs only around the slit S1 formed in the pixel electrode 126.

As a result, the number of domains is reduced by the signal of the second common electrode 206, so that the viewing angle is also narrowed.

In this case, the case where a signal is simultaneously applied to the first and second common electrodes 202 and 206 and a case where the common signal can be applied to only the second common electrode 206 can be changed by a simple circuit.

For example, a switching element (not shown) is formed in the non-display area of the liquid crystal panel, and the first common electrode 202 and the second common electrode 206 are connected to each other.

When the switching element is in an off state, the common signal flows only to the first common electrode 202. When the switching element is in an on state, the common signal flows through the switching element. The first common electrode 202 and the second common electrode 206 may be connected to each other so that the same common signal may be applied to the two electrodes.

Alternatively, the first common electrode 202 and the second common electrode 206 may be connected to separate signal lines, and different sources may be applied to each electrode, and the source may be external to the system. You can use the switch to adjust.

With the above-described configuration, it is possible to manufacture an MVA mode liquid crystal display device capable of realizing a wide viewing angle and a narrow viewing angle.

Hereinafter, a method of manufacturing an array substrate and a color filter substrate of a multi-domain liquid crystal display according to the present invention will be described with reference to FIGS. 6 and 7.

6A through 6D are cross-sectional views of an array substrate for a multi-domain mode liquid crystal display device taken along the line IV-IV of FIG. 4 and in accordance with the process sequence of the present invention.

As shown in FIG. 6A, a conductive metal is deposited and patterned on the substrate 100 to form a gate wiring 102 (see FIG. 4) and a gate electrode 104 extending in one direction.

The conductive metal may be a low resistance conductive metal group including aluminum (Al), aluminum alloy (AlNd), chromium (Cr), copper (Cu), titanium (Ti), molybdenum (Mo), tungsten (W), and the like. In other words, one or more selected metals of the metal group may be deposited and patterned to form the gate wiring 102 (see FIG. 4) and the gate electrode 104.

At this time, a part of the gate wiring (FIG. 4, 102) or a portion protruding and extending from the gate wiring 102 is formed and is referred to as the gate electrode 104.

Next, a gate insulating layer 106 is formed on the entire surface of the substrate 100 on which the gate wirings and the gate electrodes 102 and 104 are formed.

The gate insulating layer 106 is formed by selectively depositing one or more materials from an inorganic insulating material group including silicon nitride (SiN _X ) and silicon oxide (SiO ₂ ).

Next, amorphous silicon (a-Si: H) and amorphous silicon (n + or p + a-Si: H) doped with impurities are deposited and patterned on the entire surface of the substrate 100 on which the gate insulating layer 106 is formed. The active layer 108 and the ohmic contact layer 110 are formed on the gate electrode 104.

In this case, the ohmic contact layer 110 may be formed by forming an amorphous silicon layer and then doping impurities on the surface of the amorphous silicon.

As shown in FIG. 6B, one or more materials selected from the aforementioned conductive metal groups are deposited and patterned on the entire surface of the substrate 100 on which the active layer 108 and the ohmic contact layer 110 are formed. The data line 118 and the drain electrode 118 spaced apart from each other on the ohmic contact layer 110 are formed, and the data line connected to the source electrode 116 and intersects the gate line 102 (see FIG. 4). 114).

As shown in FIG. 6C, silicon nitride (SiN _X ) and silicon oxide (SiO) are formed on the entire surface of the substrate 100 on which the source and drain electrodes 116 and 118, the data line (114 in FIG. 4) and the island-shaped metal layer are formed. _A protective film 122 is formed by depositing one or more materials selected from the group of inorganic insulating materials including ₂ ).

In this case, the protective layer may be formed by coating one or more materials selected from the group of organic insulating materials including benzocyclobutene (BCB) and acrylic resin (resin) as well as the inorganic insulating film described above. It may be.

Subsequently, a process of patterning the passivation layer 122 is performed to form a drain contact hole 124 exposing a part of the drain electrode 116.

As shown in FIG. 6D, indium tin oxide (ITO) and indium zinc oxide (IZO) are included on the entire surface of the substrate 100 on which the passivation layer 122 including the drain contact hole 124 is formed. A selected one of the transparent conductive metal groups is deposited and patterned to form the pixel electrode 126 in contact with the drain electrode 118.

At this time, the slits S1 having a square shape <are formed in a direction that is symmetrical with respect to the center of the pixel region P.

According to the above method, an array substrate for an MVA mode liquid crystal display device according to the present invention can be manufactured.

Hereinafter, the manufacturing process of the color filter substrate bonded to the array substrate produced by the above-mentioned process is demonstrated with reference to a process drawing.

7A to 7B are cross-sectional views illustrating a color filter substrate for a multi-domain mode liquid crystal display device taken along the line VV of FIG. 4 and in accordance with the process sequence of the present invention.

As illustrated in FIG. 7A, the pixel region P is defined on the insulating substrate 200, and a first common electrode 202 having at least two spaced apart squares is formed to correspond to the pixel region.

Next, a color filter 204 is formed corresponding to the pixel region P in which the second common electrode 202 is formed.

The color filter uses red, green, and blue color filters, and may be formed in a stripe or mosaic shape.

As illustrated in FIG. 7B, a second common electrode 206 having a slit pattern S2 having the same shape is formed on the color filter 204 to correspond to the first common electrode 202.

In this case, preferably, the first common electrode 202 is formed of a transparent electrode in the same manner as the second common electrode 206.

According to the above-described process, a color filter substrate for a multi-domain mode liquid crystal display device according to the present invention can be manufactured.

In this case, the first first common electrode 202 may be formed on the substrate 200 or may be formed later.

In addition, an insulating film layer may be further configured between the first and second common electrodes.

8 is a cross-sectional view illustrating a part of a multi-domain mode liquid crystal display according to another exemplary embodiment of the present invention.

As illustrated, the pixel electrode 302 having the slit pattern S1 is formed on the first substrate 300. As mentioned above, the slit pattern S1 is formed in a square shape (<) in a plane.

A first common electrode on one surface of the second substrate 400 facing the first substrate 300 includes a square slit pattern S2 having the same planar shape as the square formed on the pixel electrode 302. 402 is configured.

The color filter layer 404 is formed on the first common electrode 402, and the slit pattern S2 is disposed below the slit pattern S2 of the first common electrode 402 on the color filter layer 404. The second common electrode 406 having the same shape as) is formed.

As described above, when a signal is applied only to the first common electrode 402 having the slit pattern S2 as described above, a wide viewing angle may be realized, but as shown in FIG. When the common signal is simultaneously applied to the second common electrode 406, the viewing angle is narrowed because the vertical electric field 500 is also generated at the portion corresponding to the slit S2 by the second common electrode 406. Can be obtained.

Therefore, when the MVA mode liquid crystal display device is manufactured according to the present invention, the following effects can be obtained.

First, a separate common electrode having the same shape as the slit pattern is further formed to correspond to the slit pattern of the common electrode on which the slit pattern is formed, and when the same signal is applied to the two electrodes, a narrow viewing angle can be obtained. When the common signal is applied only to the patterned common electrode, the liquid crystal display device having a wide viewing angle can be obtained.

Second, since it has a wide viewing angle and narrow viewing angle function, it can increase the competitiveness of the product.

Third, since the viewing angle can be adjusted by controlling whether voltage is applied to the common electrode, a separate structure is not required for each unit pixel, so the structure has a simple effect.

Claims (6)

A first substrate and a second substrate, each of which includes a plurality of pixel regions and is bonded to each other; Gate wiring and data wiring intersecting on said first substrate; A thin film transistor configured at an intersection point of the gate line and the data line; A pixel electrode positioned in the pixel area and including a slit pattern; A first common electrode formed on one surface of the second substrate and including a slit pattern planarly spaced from the slit pattern of the pixel electrode; A second common electrode having the same shape as the slit pattern of the first common electrode Multi-domain vertical alignment mode liquid crystal display comprising a. The method of claim 1, And a slit pattern of the pixel electrode, the first common electrode, and the second common electrode are square (<). The method of claim 1, And the first common electrode and the second common electrode are disposed with an insulating layer (color filter layer) interposed therebetween. Preparing a first substrate and a second substrate; Forming a gate line and a data line crossing the first substrate to define a pixel area; Forming a thin film transistor at an intersection point of the gate line and the data line; Forming a pixel electrode including a slit pattern in the pixel region; Forming a first common electrode including a slit pattern at a position spaced apart from the slit pattern of the pixel electrode on one surface of the second substrate; Forming a second common electrode in the same shape corresponding to the slit pattern of the first common electrode; Method of manufacturing a multi-domain vertical alignment mode liquid crystal display comprising a. The method of claim 4, wherein And a slit pattern of the pixel electrode, the first common electrode, and the second common electrode are in the shape of a square. The method of claim 4, wherein And manufacturing an insulating layer between the first common electrode and the second common electrode.

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