KR100750925B1 - A liquid crystal display - Google Patents

Abstract

The pixel region is divided into a plurality of small domains by the opening pattern of the lower substrate and the opening pattern of the upper substrate. At this time, small domains can be classified into vertically elongated (vertical domains) and horizontally elongated ones (horizontal domains), both of which are odd. In this way, the width of the domain and the width of the domain dividing means can be optimized.

LCD, Pixel Area, Domain, Odd

Description

Liquid crystal display device {A LIQUID CRYSTAL DISPLAY}

FIG. 1A is a layout view of a thin film transistor substrate of a liquid crystal display according to a first exemplary embodiment of the present invention, and shows one pixel region.

FIG. 1B is a cross-sectional view taken along line Ib-Ib 'of FIG. 1A;

FIG. 2A is a layout view of a color filter substrate of a liquid crystal display according to a first exemplary embodiment of the present invention, and illustrates one pixel area; FIG.

FIG. 2B is a cross sectional view taken along the line IIb-IIb ′ of FIG. 2A;

3 is a layout view of a liquid crystal display according to a first exemplary embodiment of the present invention, and shows one pixel area.

FIG. 4 is a layout view of a thin film transistor substrate of a liquid crystal display according to a second exemplary embodiment of the present invention, and shows four adjacent pixel regions.

FIG. 5 is a layout view of a color filter substrate of a liquid crystal display according to a second exemplary embodiment of the present invention, and shows four adjacent pixel regions.

6 is a layout view of a liquid crystal display according to a second exemplary embodiment of the present invention, showing four adjacent pixel areas.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display, and more particularly, to a vertically aligned liquid crystal display that divides a pixel region into a plurality of small domains in order to obtain a wide viewing angle.

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

As a method of forming the opening pattern, an opening pattern is formed in each of the pixel electrode and the common electrode, and the viewing angle is widened by adjusting the direction in which the liquid crystal molecules lie down using a fringe field formed by the opening patterns. .

The method of forming the protrusions is a method of controlling the lying direction of the liquid crystal molecules by using the electric field distorted by the protrusions by forming the protrusions on the pixel electrode and the common electrode formed on the upper and lower substrates, respectively.                         

In another method, an opening pattern is formed on the pixel electrode formed on the lower substrate, and a protrusion is formed on the common electrode formed on the upper substrate, so that the liquid crystal lies down using the fringe field formed by the opening pattern and the protrusion. By regulating the formation of domains.

However, when this method is applied, the portion where the opening pattern or the projection is formed appears as a dark portion that does not pass light. Therefore, when the area occupied by the opening pattern and the projection is too large, the luminance decreases. On the contrary, if the opening pattern or projections are formed very rarely, the effect of regulating the tilting direction of the liquid crystal may be deteriorated. As a result, the texture generated when the liquid crystals are arranged unevenly occupies a large area, thereby causing luminance and luminance. Together, the picture quality will be degraded.

The technical problem to be achieved by the present invention is to improve the image quality of the liquid crystal display by optimizing the arrangement interval of the domain dividing means such as the opening pattern and the projection.

In order to solve this technical problem, the present invention forms an odd number of each directional domain included in one pixel area.

Specifically, an insulating first substrate, a first wiring formed on the first substrate in a first direction, and a second wiring formed on the first substrate in a second direction and insulated from and intersecting the first wiring. And a thin film transistor connected to the first wiring and the second wiring, each pixel region connected to the thin film transistor and having a first domain dividing means and defined by the first wiring and the second wiring crossing each other. A pixel electrode, an insulating second substrate facing the first substrate, and a common electrode formed on the second substrate and having a second domain dividing means, wherein the first domain dividing means and the second domain dividing are included. The means divides one of the pixel electrodes into M first direction small domains and N second direction small domains, wherein one of M and N is an odd liquid crystal table. Arrange the device.

In this case, both M and N may be odd, and the first and second domain dividing means may be openings formed in the pixel electrode and the common electrode, respectively. And a third wiring formed on the first substrate and including a portion overlapping with the first domain dividing means and a portion formed on both sides of the second wiring in parallel with the second wiring. It is preferable. In addition, when both M and N are odd, the first and second domain dividing means included in two pixel regions neighboring in the first direction are mirror-symmetric with each other, and within two pixel regions neighboring in the second direction. The first and second domain dividing means included in each other are point-symmetrical with respect to an intersection point of a second direction straight line dividing two pixel regions neighboring in the second direction and a boundary line between two pixel region neighboring in the second direction. It is preferable.

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

FIG. 1A is a layout view of a thin film transistor substrate of a liquid crystal display according to a first exemplary embodiment of the present invention, and shows one pixel area, and FIG. 1B is a cross-sectional view taken along line Ib-Ib 'of FIG. 1A.

First, a gate made of a metal or a conductor such as aluminum (Al) or aluminum alloy (Al alloy), molybdenum (Mo) or molybdenum-tungsten (MoW) alloy, chromium (Cr), tantalum (Ta) or the like on the insulating substrate 10. Wiring is formed. The gate wire is connected to the scan signal line or the gate line 20 and the gate line 20 which extend in the horizontal direction, and receives a scan signal from the outside and transfers the gate signal to the gate line 20 (not shown). And a gate electrode 21 of the thin film transistor that is part of the gate line 20.

A storage capacitor wiring made of the same material as the gate wiring is formed on the insulating substrate 10. The storage capacitor wiring has a slight curvature and is connected to the storage capacitor line 30 extending in the horizontal direction, the first storage electrode 31 vertically extending and connected to the storage capacitor line 30, and the first storage electrode of the neighboring pixel. A second storage electrode 32 connected to the 31 and vertically extending, the third and fourth storage electrodes 33 and 34 connected to the second storage electrode 32 and extending in the horizontal direction; And a fifth storage electrode 35 connected to the fourth storage electrodes 33 and 34 and extending in the vertical direction. At this time, the storage capacitor wiring forms a capacitance between the pixel electrode 90 to increase the charge retention capability of the pixel electrode 90, and also includes domains such as openings 91 and 92 formed in the pixel electrode. By overlapping with the dividing means, it also serves to prevent light leakage and to strengthen the fringe field. The storage capacitor wirings can be variously modified in arrangements to the extent that they can achieve the functions described above.

The gate wiring and the storage capacitor wiring may be formed in a single layer, but may be formed in a double layer or a triple layer. In the case of forming more than two layers, it is preferable that one layer is formed of a material having a low resistance and the other layer is formed of a material having good contact properties with other materials, and a double layer of Cr / Al (or Al alloy) or Bilayers are an example.

A gate insulating film 40 made of silicon nitride (SiN _x ) is formed on the gate wiring and the storage capacitor wiring to cover the entire screen display, particularly the gate line 20 and the gate electrode 21. However, the gate insulating film 40 does not cover the gate pad of the peripheral portion.

A semiconductor layer pattern 50 made of a semiconductor such as hydrogenated amorphous silicon is formed on the gate insulating layer 40, and the semiconductor layer pattern 50 is heavily doped with n-type impurities such as phosphorus (P). An ohmic contact layer pattern or an intermediate layer pattern 61, 62 made of amorphous silicon or silicide is formed.

On the contact layer patterns 61 and 62, a data line made of a conductive material such as Mo or MoW alloy, Cr, Al or Al alloy, Ta is formed. First, the data line is connected to a data line 70 formed in a vertical direction, a data pad (not shown) connected to one end of the data line 70 to receive an image signal from the outside, and the data line 70. A source electrode 71 of the thin film transistor, which is a branch, is separated from the source electrode 71, and includes a drain electrode 72 of the thin film transistor positioned opposite to the source electrode 71 with respect to the gate electrode 21.

The data line may be formed of a single layer like the gate line, but may be formed of a double layer or a triple layer. Of course, when forming more than two layers, it is preferable that one layer is made of a material having a low resistance and the other layer is made of a material having good contact properties with other materials.

On the other hand, the contact layer patterns 61 and 62 lower the contact resistance between the semiconductor layer pattern 50 below and the data wirings above. The semiconductor layer pattern 50 is formed around the source electrode 71 and the drain electrode 72 in the form of an island, and is also disposed at a portion where the storage capacitor wiring and the data line 70 cross each other.

On the data line, a protective film 80 having a contact hole 81 exposing the drain electrode 72 is formed. The passivation layer 80 also has a contact hole (not shown) that exposes the gate pad and the data pad. The passivation layer 80 may cover and protect at least a portion of the semiconductor layer pattern 50 that is positioned between the source electrode 71 and the drain electrode 72. The passivation layer 80 may be made of an organic insulating material such as silicon nitride or acrylic.

The pixel electrode 90 made of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO) is formed on the passivation layer 80. The pixel electrode 90 is connected to the drain electrode 72 through the contact hole 81. The pixel electrode 90 has an opening pattern which is a domain dividing means, and the opening pattern has a first opening 91 formed in the horizontal direction under the pixel electrode 90 and a second opening formed in the vertical direction. 92). At this time, the second opening portion 92 is positioned away from one side without being equidistant from both data lines 70. The first opening 91 and the second opening 92 overlap the third storage electrode 33 and the fifth storage electrode 35, respectively.

An auxiliary data pad (not shown) covering the data pad and an auxiliary gate pad (not shown) covering the gate pad are also formed on the passivation layer 80.

The color filter substrate facing the thin film transistor substrate shown in Figs. 1A and 1B will be described.

FIG. 2A is a layout view of a color filter substrate of a liquid crystal display according to a first exemplary embodiment of the present invention, and shows one pixel area, and FIG. 2B is a cross-sectional view taken along line IIb-IIb 'of FIG. 2A.

A black matrix 120 made of an organic material containing a black layer or a double layer of chromium and chromium oxide is formed on the substrate 110, and red, green, and blue colors are formed in each pixel region defined by the black matrix 120. The color filters 130 are alternately arranged. The common electrode 140 made of a transparent conductive material such as ITO or IZO is formed on the color filter 130. The common electrode 140 has an opening pattern which is a domain dividing means, and the opening pattern has upper first and third openings 141 and 143 which are elongated in the horizontal direction and upper second and elongated in the vertical direction. The fourth openings 142 and 144 are formed. At this time, the opening pattern of the common electrode 140 is not symmetrical in both up, down, left and right.

3 is a layout view of a liquid crystal display according to a first exemplary embodiment of the present invention, and shows one pixel area. That is, FIG. 3 shows a state in which the thin film transistor substrate (lower substrate) of FIG. 1A and the color filter substrate (upper substrate) of FIG. 2A are combined.

The thin film transistor substrate and the color filter substrate are coupled side by side with a predetermined interval therebetween, and a liquid crystal material is injected between the thin film transistor substrate and the color filter substrate. The liquid crystal material is oriented such that its long axis is perpendicular to the substrate without an electric field applied.

The pixel region is divided into a plurality of small domains by the opening pattern of the lower substrate and the opening pattern of the upper substrate. At this time, small domains can be classified into vertically elongated (vertical domains) and horizontally elongated ones (horizontal domains), both of which are odd. Here, it is preferable that the width of each small domain is 20 ± 5 μm. If the width of the small domain is too narrow, the aperture ratio decreases, and if the width of the small domain is too wide, the fringe field is weakly formed, making it difficult to control the tilt direction of the liquid crystal molecules. Because it becomes. In the present invention, the width of the small domain can be optimized by forming an odd number of vertical domains and horizontal domains.

However, when the vertical domain and the horizontal domain are formed in an odd number as in the first embodiment of the present invention, there is a problem in that the viewing angles on the left and right or up and down of the liquid crystal display are asymmetric. That is, since the number of domains inclined to the left and the number of domains inclined to the right do not coincide with each other, the image quality may be different from left to right, and the same may be applied to the upper and lower sides. A solution for solving this problem is presented in the second embodiment.

4 is a layout view of a thin film transistor substrate of a liquid crystal display according to a second exemplary embodiment of the present invention, and illustrates four adjacent pixel regions.

The pixel region on the left of the four pixel regions of FIG. 4 has the same structure as the pixel regions shown in FIGS. 1A and 1B. In the pixel region of the upper right, the pixel region of the upper left and the openings 91 and 92 of the pixel electrode 90 are mirror-symmetric with each other. The arrangement of the sustain electrodes 31, 32, 33, 34, and 35 is asymmetrical to each other, but basically overlaps with the openings 91 and 92, and it is common to include portions parallel to and adjacent to both data lines 70. to be. The shape of the thin film transistor is also slightly different in both pixel areas, which is different in order to improve the aperture ratio with respect to the arrangement of the sustain electrodes 31, 32, 33, 34, and 35.

In FIG. 4, the openings 91 and 92 of the pixel electrodes are also mirror-symmetrically symmetric with each other in the lower left and lower right pixel areas. The arrangement of the sustain electrodes 31, 32, 33, 34, and 35 is asymmetrical to each other, but basically overlaps with the openings 91 and 92, and it is common to include portions parallel to and adjacent to both data lines 70. to be. The shape of the thin film transistor is also slightly different in both pixel areas, which is different in order to improve the aperture ratio with respect to the arrangement of the sustain electrodes 31, 32, 33, 34, and 35.

In Fig. 4, the openings 91 and 92 of the upper left and lower left pixel regions are point symmetrical with respect to the intersection of the gate line and the line that vertically divides the two pixel regions. The openings 91 and 92 in the upper right and lower right pixel regions also have point symmetry with respect to the intersection of the gate lines and the line that vertically divides the two pixel regions.

FIG. 5 is a layout view of a color filter substrate of a liquid crystal display according to a second exemplary embodiment of the present invention, showing four adjacent pixel areas.

The openings 141, 142, 143, and 144 of the color filter substrate are also mirror-symmetrically formed in two pixel areas of the upper left and the upper right and two pixel areas of the lower left and the lower right, and the two pixel areas of the upper left and lower left and the upper and lower right In the two pixel regions, a point symmetry is achieved at a point where a straight line that divides these pixels vertically and the boundary line between the upper pixel region and the lower pixel region cross each other.

6 is a layout view of a liquid crystal display according to a second exemplary embodiment of the present invention, showing four adjacent pixel areas.

FIG. 6 illustrates an overlap between FIGS. 4 and 5, and the lower openings 91 and 92 and the upper openings 141, 142, 143 and 144 combine to divide each pixel area into a plurality of domains. At this time, since the lower openings 91, 92 and the upper openings 141, 142, 143, and 144 all have mirror image symmetry (between left and right pixels) and point symmetry (between top and bottom pixels), each domain also has mirror image symmetry between left and right pixels. In addition, there is a point symmetry between the upper and lower pixels. Accordingly, the odd vertical and horizontal domains are formed in each pixel area, thereby solving the problem of asymmetrical viewing angles on the left and right or top and bottom of the liquid crystal display. That is, the two left and right pixel regions in which the openings are mirror-symmetrically compensate for the asymmetry of the vertical domains, and the horizontal domains in the two upper and lower pixel regions in which the openings are point-symmetrical complement each other. Therefore, in the whole liquid crystal display, the viewing angle is symmetrical from the top and the left and right.

In the above, the opening is taken as an example for dividing the domain, but the present invention can be applied even when the dielectric protrusion is used as the domain dividing means.

In addition, although both the horizontal domain and the vertical domain are formed in odd numbers, only one of them may be formed in an odd number when necessary for the optimization of the domain spacing. In this case, in order to ensure symmetrical viewing angles in the up, down, left, and right sides, the domain dividing means may have only one of left and right mirror image symmetry or top and bottom point symmetry. For example, in the case where only the longitudinal domain is formed in an odd number, by forming the domain dividing means so as to be symmetrical to the left and right, it is possible to secure symmetrical viewing angles in the vertical and horizontal directions.

As described above, in the present invention, the width of the domain and the width of the domain dividing means can be optimized by forming the domain dividing means so that the number of the horizontal domain and the vertical domain included in each pixel area is odd.

Claims (5)

Insulating first substrate, First wiring formed on the first substrate in a first direction, A second wiring formed on the first substrate in a second direction and insulated from and intersecting the first wiring; A thin film transistor connected to the first wiring and the second wiring, A pixel electrode connected to the thin film transistor and having a first domain dividing means and formed in each pixel region defined by the first wiring and the second wiring crossing each other; An insulating second substrate facing the first substrate, A common electrode formed on the second substrate and having a second domain dividing means Wherein the first domain dividing means and the second domain dividing means divide one pixel electrode into M first direction domains and N second direction domains, and at least one of M and N Odd liquid crystal display. In claim 1, And M and N are both odd numbers. The method of claim 1 or 2, And the first and second domain dividing means are openings formed in the pixel electrode and the common electrode, respectively. The method of claim 1 or 2, And a third wiring formed on the first substrate and including a portion overlapping with the first domain dividing means and a portion formed on both sides of the second wiring in parallel with the second wiring. Device. In claim 2, The first and second domain division means included in two pixel regions neighboring in the first direction are mirror-symmetric with each other, and the first and second domain division means included in two pixel regions neighboring in the second direction. And the means is point symmetrical with respect to an intersection of a second straight line dividing two pixel regions neighboring in the second direction and a boundary line between two pixel region neighboring in the second direction.

Images