KR20050025780A - Liquid crystal display - Google Patents

Abstract

An LCD(Liquid Crystal Display) is provided to reduce light leakage occurring around a data line by reducing an electrostatic capacity caused due to a coupling between the data line and a common electrode. An LCD comprises a first insulation substrate, a gate line(121), a data line(171), a pixel electrode, a thin film transistor, a second insulation substrate, a black matrix, a color filter, a first common electrode, and a second common electrode. The gate line is formed on the first insulation substrate. The data line is formed on the first insulation substrate in such a manner that the data line is insulated from the gate line and intersects the gate line. The pixel electrode is formed in each pixel region defined by the gate line and the data line, and has a first domain dividing element. The thin film transistor is connected to the gate line, data line, and the pixel electrode. The second insulation substrate is opposed to the first insulation substrate. The black matrix is formed on the second insulation substrate. The color filter is formed on the second insulation substrate, and partially superimposed with the black matrix. The first common electrode is formed on the color filter. The second common electrode is formed on the second insulation substrate, and has a second domain dividing element cooperating with the first domain dividing element so as to divide the pixel electrode into a plurality of small domains, and a data line cut portion superimposed with the data line. The black matrix is disposed in the region corresponding to the gap formed between two adjacent pixel electrodes.

Description

Liquid crystal display

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display, and more particularly, to a liquid crystal display capable of preventing light leakage from occurring around a data line.

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, a plurality of wirings are formed on the thin film transistor substrate of the liquid crystal display, such as a gate line for transmitting a scan signal and a data line for transmitting an image signal, and these wirings are formed by coupling a resistor with a common electrode of a peripheral wiring or an upper substrate. Has a capacitance. This self-resistance and capacitance act as a load on each wiring and distort the signal transmitted through the wiring through RC delay. In particular, the coupling between the data line and the common electrode drives the liquid crystal molecules positioned between the two to affect the electric field around the data line.

As a result, the arrangement of the liquid crystal molecules is changed, which leads to unwanted transmission of light, which is called light leakage. In order to prevent such light leakage, a method of covering the boundary of the pixel region with a black matrix is provided, but light leakage still exists due to multiple reflections between the black matrix wiring and the black matrix. In addition, since the black matrix must be formed wide to cover the boundary of the pixel region with the black matrix, it becomes a cause of lowering the aperture ratio.

An object of the present invention is to reduce the light leakage around the data line by reducing the capacitance caused by the coupling between the data line and the common electrode.

Another technical object of the present invention is to reduce the size of the black matrix to improve the aperture ratio.

In order to solve this problem, the present invention provides the following liquid crystal display device.

More specifically, a first insulating substrate, a gate line formed on the first insulating substrate, a data line formed on the first insulating substrate and insulated from and intersecting with the gate line, and a pixel region defined by crossing the gate line and the data line. A thin film transistor connected to the pixel electrode, the gate line, the data line, and the pixel electrode formed in each of the plurality of small domains by the first domain dividing means, the second insulating substrate facing the first insulating substrate, and 2 a black matrix formed on the insulating substrate, a color filter formed on the second insulating substrate and partially overlapping with the black matrix, a common electrode formed on the color filter, a second electrode formed on the second insulating substrate and partitioning the first domain Second domain dividing means for dividing the pixel electrode into a plurality of small domains together with the means; A liquid crystal display device including a common electrode having a data line cutout overlapping an emitter line and having a black matrix disposed in a region corresponding to two adjacent pixel electrodes is provided.

The storage electrode line may further include a storage electrode line formed on the first insulating substrate in the same layer as the gate line and including the storage electrode.

In addition, the first domain dividing means and the second domain dividing means are preferably formed in a cut pattern.

In addition, the sustain electrode is formed to partially overlap the first domain dividing means, and it is preferable that the side adjacent to the first domain dividing means is formed side by side along the first domain dividing means in the overlapping portion.

In addition, the second domain dividing means includes a horizontal incision pattern formed in the horizontal direction at a position that divides the pixel electrode up and down and a diagonal incision pattern formed in the diagonal direction in the upper and lower portions of the half divided pixel electrode, respectively, The incision is preferably connected to the end of the oblique incision pattern.

In addition, the diagonal cut pattern preferably has an inclination angle between 40 and 50 with the gate line or the date line.

DETAILED DESCRIPTION Embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

In the drawings, the thickness of layers, films, panels, regions, etc., are exaggerated for clarity. Like parts are designated by like reference numerals throughout the specification. When a part of a layer, film, region, plate, etc. is said to be "on" another part, this includes not only the other part being "right over" but also another part in the middle. On the contrary, when a part is "just above" another part, there is no other part in the middle.

Next, a liquid crystal display according to an exemplary embodiment of the present invention will be described with reference to the drawings.

1 is a layout view of a thin film transistor substrate for a liquid crystal display according to a first embodiment of the present invention, FIG. 2 is a layout view of a color filter substrate for a liquid crystal display according to a first embodiment of the present invention, and FIG. 4A to 4C are cross-sectional views of lines IVa-IVa ', IVb-IVb', and IVc-IVc 'of FIG. 3 according to the present invention.

The liquid crystal display device is a liquid crystal molecule that is injected between the lower substrate 110 and the upper substrate 210 facing the lower substrate 110 and the lower substrate 110 and the upper substrate 210 and vertically aligned with respect to the substrates 110 and 210. It consists of a liquid crystal layer 3 comprising a.

First, a thin film transistor substrate 100 for a liquid crystal display device according to a first embodiment of the present invention will be described in detail with reference to FIGS. 1 and 4A to 4C.

A plurality of gate lines 121 and a plurality of storage electrode lines 131 are formed on the insulating substrate 110. The gate line 121 and the storage electrode line 131 mainly extend in the horizontal direction and are separated from each other.

The gate line 121 transmits a gate signal, and a part of each gate line 121 protrudes up and down to form a plurality of gate electrodes 124.

The storage electrode line 131 receives a predetermined voltage such as a common voltage, and a protrusion 137 having a 45 ° inclination angle with respect to the storage electrode line 131 that protrudes to one side and protrudes to one side, and a plurality of storage electrodes. 133a to 133d and the sustain electrode connection line 137. In addition, the storage electrodes 133a to 133f are connected to the first vertical portion 133a extending downward from the storage electrode line 131 in the vertical direction, and the ends of the first vertical portion 133a, and the storage electrode line 131. A first diagonal portion 133b having a 45 ° inclination angle with respect to the second diagonal portion 133b, a second vertical portion 133c extending in a direction perpendicular to the sustain electrode line 131, and connected to an end of the first diagonal portion 133b; It is connected to the end of the second vertical portion 133c and has a second oblique portion 133d that forms an inclination angle of 45 ° with respect to the storage electrode line 131. In addition, the storage electrode line 131 has a rotational symmetry of 180 ° with the second diagonal portion 133d and forms a 45 ° inclination angle with respect to the storage electrode line 131. It is connected to the end portion, and further includes a horizontal portion 133f parallel to the storage electrode line 131. At this time, the second diagonal portion 133d and the third diagonal portion 133e are connected to the same end of the sustain electrode connection line 137.

Here, the gate line 121, the storage electrode line 131, and the storage electrodes 133a to 133f may be formed of a silver-based metal such as silver (Ag) or a silver alloy having low resistivity, or an aluminum-based metal such as aluminum (Al) or an aluminum alloy. Or a conductive film made of copper (Cu) or a copper alloy, and in addition to the conductive film, chromium (Cr), titanium (Ti), tantalum ( It may have a multilayer film structure including other conductive films made of Ta), molybdenum (Mo) and alloys thereof (eg, molybdenum-tungsten (MoW) alloys). An example of the combination of the lower layer and the upper layer is chromium / aluminum-neodymium (Nd) alloy.

Side surfaces of the gate line 121 and the storage electrode line 131 are inclined, and the inclination angle is in a range of about 30-80 ° with respect to the surface of the substrate 110.

A gate insulating layer 140 made of silicon nitride (SiNx) is formed on the gate line 121 and the storage electrode line 131.

A plurality of linear semiconductors 151 made of hydrogenated amorphous silicon (amorphous silicon is abbreviated a-Si) and the like are formed on the gate insulating layer 140. The linear semiconductor 151 extends mainly in the longitudinal direction, from which a plurality of extensions 154 extend toward the gate electrode 124.

A plurality of linear and island ohmic contacts 161 and 165 made of a material such as n + hydrogenated amorphous silicon doped with silicide or n-type impurities at a high concentration are formed on the semiconductor 151. have. The linear contact member 161 has a plurality of protrusions 163, and the protrusions 163 and the island contact members 165 are paired and positioned on the protrusions 154 of the semiconductor 151.

Side surfaces of the semiconductor 151 and the ohmic contacts 161 and 165 are also inclined, and the inclination angle is 30 to 80 degrees.

A plurality of data lines 171 and a plurality of drain electrodes 175 are formed on the ohmic contacts 161 and 165 and the gate insulating layer 140, respectively.

The data line 171 mainly extends in the vertical direction to cross the gate line 121 and transmit a data voltage. A plurality of branches extending from the data line 171 toward the drain electrode 175 forms a source electrode 173. The pair of source electrode 173 and the drain electrode 175 are separated from each other and positioned opposite to the gate electrode 124. The gate electrode 124, the source electrode 173, and the drain electrode 175 form a thin film transistor (TFT) together with the protrusion 154 of the semiconductor 151, and the channel of the thin film transistor is a source. A protrusion 154 is formed between the electrode 173 and the drain electrode 175.

The data line 171 and the drain electrode 175 may also include a conductive film made of a silver metal or an aluminum metal. In addition to the conductive film, chromium (Cr), titanium (Ti), tantalum (Ta), and molybdenum (Mo) may be used. ) And other conductive films made of alloys thereof. Sides of the data line 171 and the drain electrode 175 are also inclined, and the inclination angle is in the range of about 30-80 ° with respect to the horizontal plane.

The ohmic contacts 161 and 165 exist only between the semiconductor 151 below and the data line 171 and the drain electrode 175 above and serve to lower the contact resistance. The linear semiconductor 151 has an exposed portion between the source electrode 173 and the drain electrode 175 and is not covered by the data line 171 and the drain electrode 175, and in most places, the linear semiconductor 151 is provided. Is smaller than the width of the data line 171. The semiconductor 151 may increase in width at a portion where the semiconductor 151 meets the gate line 121 to enhance insulation between the gate line 121 and the data line 171.

On the data line 171, the drain electrode 175, and the exposed portion of the semiconductor 151, an organic material having excellent planarization characteristics and photosensitivity, and plasma enhanced chemical vapor deposition (PECVD), is formed. A passivation layer 180 made of a low dielectric constant insulating material such as a-Si: C: O, a-Si: O: F, or silicon nitride, which is an inorganic material, is formed.

The passivation layer 180 is provided with a plurality of contact holes 182 and 185 exposing the end portion 179 and the drain electrode 175 of the data line 171, respectively.

A plurality of pixel electrodes 190 and a plurality of contact assistants 82 are formed on the passivation layer 180 and have domain division means and are connected to the drain electrode 175 through the contact hole 185. It is.

The pixel electrode 190 is formed using a transparent conductor such as indium tin oxide (ITO) or indium zinc oxide (IZO), or an opaque conductor having excellent light reflection characteristics such as aluminum (Al). The first domain dividing means formed on the pixel electrode 190 has a horizontal cutout 192 formed in the horizontal direction at a position half-dividing the pixel electrode 190 and an upper and lower portions of the pixel electrode 190 half-divided. Includes diagonal cuts 191, 193 formed in the diagonal direction, respectively. At this time, the upper oblique cut 191 is perpendicular to the lower oblique cut 193. This is to evenly distribute the direction of the fringe field in four directions.

The contact auxiliary members 82 are connected to the end portions 179 of the data lines through the contact holes 182, respectively. The contact assistant 82 is not essential to serve to protect adhesion between the end portion of the data line 171 and an external device and to protect them, and application thereof is optional.

In addition, on the passivation layer 180, a storage wiring connecting bridge 84 that connects the storage electrode 133f and the storage electrode line 131 across the gate line 121 is formed. The storage wiring connection bridge 84 is in contact with the storage electrode 133f and the storage electrode line 131 through the contact holes 183 and 184 formed over the passivation film 180 and the gate insulating film 140. The sustain wiring connection leg 84 overlaps the leg metal piece 172. The sustain wiring connection bridge 84 serves to electrically connect the entire sustain wiring on the lower substrate 110. This holding wiring can be used to repair the defect of the gate line 121 or the data line 171, if necessary, and the leg metal piece 172 is held with the gate line 121 when irradiating a laser for such repair. It is formed to assist the electrical connection of the wiring connection bridge (84).

Next, the color filter substrate 200 for the liquid crystal display according to the first embodiment of the present invention will be described in detail with reference to FIGS. 2 and 4A to 4B.

On the insulating substrate 210, a black matrix 220 made of a single layer of chromium, a double layer of chromium and chromium oxide, or an organic material to which black pigment is added is formed to prevent light leakage. In this case, the black matrix 220 overlaps the upper portion of the data line 171 and is formed so as not to overlap the upper portion of the adjacent pixel electrode 190 to improve the cutting rate.

The red, green, and blue color filters 230 are formed on the black matrix 220. In this case, one red, green, and blue color filter 230 is formed for each pixel area partitioned by the black matrix 220.

The overcoat film 250 covers the color filter 230 to protect the color filter 230.

The common electrode 270 made of a transparent conductor and having a second domain division means is formed on the overcoat layer 250. In this case, the second domain dividing means is formed in parallel with the first domain dividing means with the first domain dividing means of the pixel electrode 190 in the center. That is, the domain dividing means also has diagonal cutouts 271 and 273 and diagonal cutouts formed in the diagonal directions on the upper and lower portions of the common electrode 270 and extends therefrom, respectively. And a central incision 272 having a branch incision parallel to each other. At this time, the diagonal cutout 271 and the diagonal cutout 273 are perpendicular to each other, and both ends of the diagonal cutouts 271 and 273 are refracted to extend in the horizontal or vertical direction 271a, 271b, 273a, 273b). In particular, the data line cutouts 274a and 274b overlapping the black matrix 220 between the pixel area and the pixel area are connected to the end portions of the branch cutouts of the center cutout 272.

Aligning and combining the thin film transistor substrate 100 of FIG. 1 and the color filter substrate 200 of FIG. 2, injecting a liquid crystal material 3 between the two substrates, and vertically aligning the long axis of the liquid crystal molecules included therein. When the two polarizing plates 13 and 23 are disposed outside the two substrates 110 and 210 such that their polarization axes are perpendicular to each other, as shown in FIGS. 3, 4A, and 4B, the liquid crystal display according to the first embodiment is described. Is prepared.

When the two substrates 100 and 200 are aligned, the first domain dividing means 11, 92, 93 of the pixel electrode 190 of the thin film transistor substrate and the second domain dividing means of the common electrode 270 of the color filter substrate. (271, 272, 273) overlap to divide the pixel region into a plurality of small domains.

On the other hand, the data line cutouts 274a and 274b of the common electrode 270 are disposed to overlap the data line 171, so that the area of the common electrode 270 overlapping the data line 171 is greatly reduced. . As such, by reducing the area of the common electrode 270 overlapping with the data line 171, the load of the data line 171 is reduced, the amount of change in the liquid crystal capacitance applied to the data line 171 is reduced, and the data line 171 is reduced. ) Lateral light leakage due to cross talk of the signal is reduced. In addition, since light leakage is significantly reduced around the data line, the width of the black matrix 220 can be reduced, thereby improving the aperture ratio.

The effect of having the data line cutouts 274a and 274b will be described in more detail after describing the second embodiment of the present invention.

Next, a liquid crystal display according to a second exemplary embodiment of the present invention will be described with reference to the drawings.

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

As shown in FIG. 5, the liquid crystal display according to the second exemplary embodiment has a different shape of the data line cutout in the liquid crystal display according to the first exemplary embodiment. Therefore, hereinafter, the description of other structures will be omitted and only the form of the second domain dividing means will be described.

 The data line cutouts 274a and 274b of the common electrode 270 extend parallel to the data line 171 from the branch cutouts of the central cutout 272, respectively, and are arranged between the pixel area and the pixel area. It overlaps with the matrix 220. That is, the data line cutouts 274a and 274b of the second embodiment are enlarged compared to the first embodiment, so that the area of the common electrode 270 overlapping the data line 171 can be further reduced, thereby surrounding the data line. Significantly reduces light leakage from

The above effects obtained by forming the data line cutouts 274a and 274b will now be described in more detail.

As described above, in the liquid crystal display according to the present invention, since the common electrode is removed in the upper region of the data line, the electric field formed between the data line and the common electrode is weakened. Accordingly, the lying angle of the liquid crystal driven by the influence of the signal flowing along the data line around the data line is reduced, thereby reducing the amount of light leakage around the data line. Look through the simulated graph.

6 is a graph showing the degree of light leakage around the data line according to the data line upper incision width in the liquid crystal display according to the exemplary embodiment of the present invention.

As shown in FIG. 6, it can be seen that the amount of light leakage decreases as the T value increases. This means that the incision of the common electrode can reduce side crosstalk.

Although the above has been described with reference to a preferred embodiment of the present invention, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concept of the present invention as defined in the following claims are also provided. It belongs to the scope of rights. In particular, the arrangement of the cutouts formed on the pixel electrode and the common electrode may be variously modified, and modifications such as placing protrusions instead of forming the cutout may be possible.

As described above, by removing the common electrode above the data line, it is possible to prevent light leakage caused by side crosstalk around the data line. Thereby, the size of the black matrix can be reduced and the aperture ratio can be increased.

1 is a layout view of a thin film transistor substrate for a liquid crystal display according to a first exemplary embodiment of the present invention.

2 is a layout view of a color filter substrate for a liquid crystal display device according to a first embodiment of the present invention;

3 is a layout view of a liquid crystal display according to a first exemplary embodiment of the present invention;

4A to 4C are cross-sectional views taken along the lines IVa-IVa ', IVb-IVb', and IVc-IVc 'of FIG. 3 of the present invention;

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

FIG. 6 is a graph illustrating a simulation result showing the degree of light leakage around a data line according to an upper cutting width of the data line in the liquid crystal display according to the exemplary embodiment of the present invention.

Claims (6)

First insulating substrate, A gate line formed on the first insulating substrate, A data line formed on the first insulating substrate and insulated from and intersecting the gate line; A pixel electrode formed in each pixel region defined by crossing the gate line and the data line and having a first domain dividing means; A thin film transistor connected to the gate line, the data line, and the pixel electrode; A second insulating substrate facing the first insulating substrate, A black matrix formed on the second insulating substrate, A color filter formed on the second insulating substrate and partially overlapping the black matrix; A common electrode formed on the color filter, A common electrode formed on the second insulating substrate and having second domain dividing means for dividing the pixel electrode into a plurality of small domains together with the first domain dividing means, and a common electrode having a data line cutout overlapping the data line; And the black matrix is disposed in a region corresponding to two adjacent pixel electrodes. In claim 1, And a storage electrode line formed on the first insulating substrate in the same layer as the gate line and including the storage electrode. In claim 1, And the first domain dividing means and the second domain dividing means are cut patterns. In claim 2, The sustain electrode is formed to partially overlap with the first domain dividing means, and the side adjacent to the first domain dividing means is formed along the first domain dividing means side by side in the overlapping portion. In claim 3, The second domain dividing means includes a horizontal incision pattern formed in a horizontal direction at a position that divides the pixel electrode up and down and a diagonal incision pattern formed in an oblique direction at upper and lower portions of the half divided pixel electrode, The data line cutout is connected to an end of an oblique cut pattern. In claim 5, The diagonal cut pattern has a 45 ° inclination angle with the gate line or the data line.