KR100983577B1 - Liquid crystal display device - Google Patents

Abstract

The present invention relates to a liquid crystal display device which improves the contrast ratio by further providing a light shielding layer to prevent light leakage at the lip periphery. Particularly, the liquid crystal display device according to the present invention includes upper and lower substrates, and a lower substrate. A gate wiring and a data wiring vertically intersecting on the substrate; a thin film transistor formed at an intersection point of the gate wiring and a data wiring; a pixel electrode connected to the thin film transistor and having a slit formed thereon; A lip forming a domain, a black matrix layer formed on the upper substrate of a portion corresponding to the lip, gate wiring, data wiring, and thin film transistor, and a liquid crystal layer formed between the upper and lower substrates. It is done.

VA mode, field distortion means, contrast ratio, light leakage

Description

Liquid crystal display device {LIQUID CRYSTAL DISPLAY DEVICE}

1 is a plan view of a conventional MVA mode liquid crystal display device.

FIG. 2 is a cross-sectional view taken along line II ′ of FIG. 1. FIG.

FIG. 3 is a layout view of a black matrix layer of the MVA mode liquid crystal display of FIG. 1. FIG.

4A is a cross-sectional view illustrating an off state of the MVA mode liquid crystal display of FIG. 1.

4B is a cross-sectional view illustrating an on state of the MVA mode liquid crystal display of FIG. 1.

5 is a plan view of an ASV mode liquid crystal display device according to the prior art.

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

7 is a plan view of an MVA mode liquid crystal display device according to a first embodiment of the present invention.

8A is a cross-sectional view taken along line III-III ′ of FIG. 7 illustrating an off state of a liquid crystal display according to a first exemplary embodiment of the present invention.

8B is a cross-sectional view taken along line III-III ′ of FIG. 7 showing an on state of a liquid crystal display according to a first embodiment of the present invention.

9 is a layout view of the black matrix layer according to the first embodiment of the present invention.

10 is a plan view of a liquid crystal display device according to a second embodiment of the present invention.

11 is a layout view of a black matrix layer according to a second embodiment of the present invention.

* Explanation of symbols on the main parts of the drawings                 

110: liquid crystal layer 110a: liquid crystal molecules

111: lower substrate 112: gate wiring

115: data wiring 117: pixel electrode

121: upper substrate 122: black matrix layer

123: color filter layer 124: common electrode

131: second field distortion means 133: first field distortion means

231: protrusion 233: depression

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a VA alignment liquid crystal display device, and more particularly, to a liquid crystal display device for improving contrast-ratio characteristics.

One of the liquid crystal display devices currently used is a liquid crystal display device in twisted nematic (TN) mode.

The TN mode liquid crystal display device forms electrodes on two substrates, and the liquid crystal molecules filled therebetween are parallel to the substrate, twisted in a spiral with a constant pitch, and then a voltage is applied to the electrodes to drive the liquid crystal director. That's the way it is.

Although the TN mode liquid crystal display is spotlighted for providing excellent color reproducibility, the contrast ratio is not good because the light is not completely blocked in the off state, and the contrast ratio changes with the angle. It is difficult to obtain a stable image such as the brightness of the halftone is reversed as it changes.

In order to solve this problem, various new concepts of the liquid crystal display device have been proposed.

For example, IPS (In-Plane Switching) mode in which two electrodes are placed in one plane to apply a transverse electric field, Film-compensated mode in which the viewing angle is compensated with a compensation film, and negative dielectric anisotropy VA (Vertical Alignment) mode using a type liquid crystal and a vertical alignment film.

Among them, the VA mode controls the liquid crystal direction by a multi-domain vertical alignment (MVA) mode in which a plurality of domains are formed to change liquid crystal directions in each domain, and a lip at the center of the pixel electrode divided into small pixel electrodes. ASV (Advanced Super-V) mode.

In the MVA mode and the ASV mode liquid crystal display, the liquid crystal directors face each other, and a viewing angle is compensated for, thereby realizing a wide viewing angle.

Hereinafter, a liquid crystal display of the prior art will be described with reference to the accompanying drawings.

1 is a plan view of a conventional MVA mode liquid crystal display device, FIG. 2 is a cross-sectional view taken along line II ′ of FIG. 1, and FIG. 3 is a layout view of a black matrix layer of the MVA mode liquid crystal display device of FIG. 1.                         

4A is a cross-sectional view illustrating an off state of the MVA mode liquid crystal display of FIG. 1, and FIG. 4B is a cross-sectional view illustrating an on state of the MVA mode liquid crystal display of FIG. 1.

First, referring to FIG. 1 and FIG. 2 with reference to the conventional MVA mode liquid crystal display device, in the liquid crystal display device composed of upper and lower substrates 21 and 11 and a liquid crystal layer formed therebetween, the lower substrate ( 11, a gate wiring 12 and a data wiring 15 intersecting in a row to define a pixel region, a pixel electrode 17 formed in the pixel region, the gate wiring 12 and a data wiring 15. A thin film transistor (TFT) and a pixel electrode 17 which are formed at the intersection points of the gate line 12 and are selectively switched by the scan signal of the gate line 12 to apply the data signal of the data line to the pixel electrode. A plurality of first electric field distortion means (33) is formed at a predetermined portion of and controls the liquid crystal director by electric field distortion.

In FIG. 1, the first electric field distortion means 33 is represented by a slit formed by selectively removing the pixel electrode.

The thin film transistor TFT may include a gate electrode branched from the gate line 12, a gate insulating layer stacked on the gate electrode, a semiconductor layer formed in an island shape on the gate electrode, It is composed of a source / drain electrode branched from the data line 15 formed on the semiconductor layer.

Although not shown, a storage capacitor parallel to the gate wiring is further formed on the lower substrate to maintain the voltage charged in the liquid crystal layer in the turn-off period of the thin film transistor, thereby preventing deterioration in image quality due to parasitic capacitance. Do it.

Meanwhile, the upper substrate 21 includes a black matrix layer 22 for preventing light leakage and a color filter layer 23 of R, G, and B formed between the black matrix layer 22 to express colors on the screen. ), A common electrode 24 stacked on the color filter layer 23 to face the pixel electrode 17 of the lower substrate 11, and formed on a predetermined portion of the common electrode 24 to form a liquid crystal by electric field distortion. A plurality of second field distortion means 31 for controlling the director is provided.

In FIG. 1, the second field distortion means 31 is illustrated as a rib formed by depositing a separate dielectric material on the common electrode 24.

The first field distortion means 33 and the second field distortion means 31 shown in the drawing are alternately arranged in parallel diagonal lines to form a multi-domain.

On the other hand, since light leakage occurs in an area where an electric field is unstable and it is difficult to control the alignment of the liquid crystal, the black matrix layer is positioned at the positions of the gate wiring 12, the data wiring 15, and the thin film transistor TFT as shown in FIG. 1. Overlap.

The black matrix layer 22 formed at the position as described above is the same as in FIG. 3.

The black matrix layer 22 is mainly formed of a metal such as Cr or CrOx having a high reflectance.

Although not shown, a vertical alignment layer is further provided on the inner surfaces of the pixel electrode 17 and the common electrode 24 to control the arrangement of liquid crystal molecules.

The liquid crystal layer 10 is formed between the upper and lower substrates 11 and 21. In the liquid crystal display of the VA mode, a negative liquid crystal having a negative dielectric anisotropy is used, and the long axis of the liquid crystal molecules is initially perpendicular to the substrate plane. Be sure to

The liquid crystal display device thus formed is divided into four regions (Fig. 2) by one first field distortion means 33 on the lower substrate and two second field distortion means 31 on the upper substrate for one pixel region. It becomes a multi-domain divided into ii, ⅲ, ⅳ).

In the case of the MVA mode liquid crystal display device, the liquid crystal molecules 10a when no voltage is applied are arranged perpendicular to the surface of the substrate as shown in FIG. 4A. ) Has a constant radius of curvature, inclined to the center of the second field distortion means (31). In this case, the black level is turned off.

Subsequently, when a voltage is applied, as shown in FIG. 4B, the liquid crystal molecules 10a are tilted according to the intensity of the electric field. Since the electric field is formed perpendicular to the substrate, the tilt azimuth angle of the liquid crystal molecules 10a by the electric field is applied. Has a rotational direction of 360 °. This case is on-state and is at white level.

At this time, the direction of the liquid crystal molecules inclined about the second field distortion means 31 is also controlled by the azimuth angle of the liquid crystal molecules in contact with the surface of the second field distortion means 31.

This is because when there are pretilted liquid crystal molecules around the liquid crystal molecules, the liquid crystal molecules around the liquid crystal tilt in that direction.

Another liquid crystal display device according to the related art is as follows.

FIG. 5 is a plan view of a conventional ASV mode liquid crystal display device, and FIG. 6 is a cross-sectional view taken along line II-II 'of FIG. 5.

The liquid crystal display device to be described below relates to an ASV mode liquid crystal display device, and is composed of upper and lower substrates 321 and 311 and a liquid crystal layer 310 formed therebetween, as shown in FIGS. 5 and 6, and the lower substrate 311. ) Includes a gate wiring 312 and a data wiring 315 that divide a unit pixel region, a thin film transistor TFT formed at an intersection of the gate wiring 312 and the data wiring 315, and within the unit pixel region. The pixel electrode 317 is formed of a plurality of unit pixel electrodes that are partially connected to each other, and is connected to the thin film transistor TFT with an insulating layer interposed therebetween.

In addition, the upper substrate 321 includes a black matrix layer 322 overlapped with a corresponding area to prevent light leakage from the gate wiring 312, the data wiring 315, and the thin film transistor TFT, and a color implementation. The color filter layer 323, a common electrode 324 facing the pixel electrode 317 to apply an electric field to the liquid crystal, and an island-shaped protrusion 331 formed at a central position of the unit pixel electrode of the pixel electrode 317. ) Is formed.

At this time, the black matrix layer has the arrangement structure as shown in FIG. 3, and light is transmitted through the open area of the black matrix layer.

Although not shown, a vertical alignment layer is selectively coated on upper and lower substrate inner surfaces on which the structure is formed, and a negative liquid crystal controlled by a vertical alignment layer is enclosed between the upper and lower substrates.

In the ASV mode liquid crystal display device configured as described above, the alignment of the liquid crystal is controlled by the depression 333 between the unit pixel electrode and the unit pixel electrode and the protrusion 331 at the central position of the unit pixel electrode, and the liquid crystal is also controlled by the vertical alignment layer. The orientation of is controlled.

In this case, the depression 333 serves as a slit between the unit pixel electrode and the unit pixel electrode formed by selectively removing the pixel electrode, and the protrusion 331 has a hemispherical shape in the center of the unit pixel electrode. Formed and acts as a lip.

The depression may be formed in the lower substrate and the protrusion may be formed in the upper substrate. However, it is common to form depressions in the pixel electrode of the lower substrate for process reasons.

When a voltage above the threshold is applied to the liquid crystal display device, the liquid crystal molecules that were initially vertically aligned are inclined so that their major axes become horizontal. In this case, electric field is induced by electric field distortion means such as the depression 333 and the protrusion 331. This distortion causes the liquid crystal molecules to tilt in different directions about the field distortion means.

However, the field distortion means, that is, the ribs and the protrusions of the MVA and ASV mode liquid crystal display devices have a constant curvature.

This is because the protrusions are formed of a photo acryl-based dielectric material because the edge portions of the ribs and the protrusions are over-etched or arbitrarily formed in a hemispherical shape during etching.

As such, when the curvature of the lip and the protrusion is generated, the liquid crystal molecules around it are not completely aligned in the initial state, and thus light leakage occurs in the black level when the black level is realized, resulting in an increase in the black level and a decrease in the contrast ratio. A problem occurs.                         

This problem becomes more pronounced as the ratio of the area occupied by the field distortion means such as the lip and the protrusion in the opening region where the pixel electrode is formed is large.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a liquid crystal display device having an improved contrast ratio by overlapping a portion around the protrusion with a black matrix layer to prevent light leakage from the portion around the protrusion.

The liquid crystal display device of the present invention for achieving the above object is at the intersection of the upper and lower substrates, the gate wiring and data wiring crossing the lower substrate to form a unit pixel region, and the intersection of the gate wiring and the data wiring. A formed thin film transistor, a first transparent conductive film connected to the thin film transistor and having a slit formed therein, a lip formed on the upper substrate to form a constant domain with the slit, a light shielding layer overlapping the lip position, and the image It is characterized in that it comprises a liquid crystal layer formed between the lower substrate.

In another exemplary embodiment, a liquid crystal display device includes an upper and a lower substrate, a gate wiring and a data wiring intersecting on the lower substrate to form a unit pixel region, and a plurality of unit pixel electrodes in the unit pixel region. A pixel electrode formed at an intersection point of the gate line and the data line, and connected to the pixel electrode, a common electrode formed on the upper substrate to face the pixel electrode, and positioned at the center of the unit pixel electrode. A protrusion formed on the common electrode, a black matrix layer formed on the upper substrate of a portion corresponding to the protrusion, gate wiring, data wiring, and thin film transistor, and a liquid crystal layer formed between the upper and lower substrates. It is characterized in that the configuration.

That is, the present invention is characterized by overlapping the light blocking layer at the position of the protrusion to remove light leakage in the off state caused by the liquid crystal is not vertically aligned by the protrusion having the curvature.

The light shielding layer may be formed of chromium, chromium oxide, or the like having high reflectivity, and may be simultaneously formed when forming a black matrix layer.

At this time, since the protrusions are formed in the same manner as in the related art, the electric field distortion effect does not change and there is no need to add a separate process by forming the light shielding layer as a black matrix layer.

Hereinafter, a liquid crystal display according to the present invention will be described in detail with reference to the accompanying drawings.

7 is a plan view of an MVA mode liquid crystal display device according to a first embodiment of the present invention, and FIG. 8A is a line III-III 'of FIG. 7 showing an off state of the liquid crystal display device according to the first embodiment of the present invention. 8B is a cross-sectional view taken along line III-III ′ of FIG. 7 showing an on state of a liquid crystal display according to a first embodiment of the present invention.

9 is a layout view of the black matrix layer according to the first embodiment of the present invention.

As shown in FIGS. 7 and 8A, the liquid crystal display according to the present invention further includes a lower substrate 111 having the first electric field distortion means 133 and the first electric field distortion means 133 so as to divide a plurality of domains. To vertically distort the liquid crystal molecules in an arbitrary direction, and when the liquid crystal display is in an off state, the upper substrate 121 having the second substrate distortion means 131 is formed, and the liquid crystal is vertically aligned between the upper and lower substrates 121 and 111. The black matrix layer overlapping the layer 110 and the first or second field distortion means to shield light leakage caused by the curvature of the first or second field distortion means 133 and 131 due to the curvature of the liquid crystals not being vertically aligned. 122).

The liquid crystal layer 110 is formed of a liquid crystal having a negative dielectric anisotropy, and initially causes the long axis of the liquid crystal molecules to be perpendicular to the substrate plane.

In addition, vertical alignment layers are further provided on inner surfaces of the upper and lower substrates having the structure as described above.

In detail, the lower substrate 111 may include a gate wiring 112 and a data wiring 115 defining a plurality of intersecting pixel regions, and an ITO material that applies a signal voltage to the liquid crystal layer as a light transmitting region. A pixel electrode 117 which is a transparent conductive film, first field distortion means 133 formed on the pixel electrode 117 to distort the direction of the liquid crystal molecules, the gate wirings, the data wirings 112 and 115 and the pixel electrodes 117 And a switching element for selectively applying and blocking voltage to the pixel electrode 117 by a signal flowing through the wires.

In this case, the first electric field distortion means 133 may be a structure or a slit such as a side electrode or a rib, but in FIG. 7, an oblique shape is formed by removing a predetermined portion of the pixel electrode. Slit of.                     

In addition, the switching element is a thin film transistor (TFT), and a silicon nitride (SiNx) or a silicon oxide (SiOx) that insulates and protects the gate electrode of a low-resistance conductive material formed simultaneously with the gate wiring and the upper layer. A gate insulating film of a material), an amorphous silicon semiconductor layer formed on the gate insulating film on the gate electrode, an ohmic contact layer formed by ion implanting impurities into the semiconductor layer to improve contact characteristics between the semiconductor layer and the upper layer, It consists of a laminated film of a source / drain electrode of a low resistivity conductive material formed simultaneously with the data line.

A passivation layer 116 made of BCB (Benzocyclobutene), acryl, and polyimide material having a low dielectric constant is further provided between the switching element and the pixel electrode.

Although not shown, the lower substrate is provided with a storage capacitor for reducing the level-shift voltage and maintaining pixel information during the non-selection period.

The upper substrate 121 includes a common electrode 124, which is a transparent conductive film of ITO material, which applies a voltage to the liquid crystal layer 110a by a voltage difference from the pixel electrode 117, and the common electrode 124. A second field distortion means 131 formed on the lower substrate and dividing the domain together with the first field distortion means 133 of the lower substrate, a color filter layer 123 for expressing color and selectively transmitting light, and a liquid crystal array Are overlapped at positions where the control cannot be controlled, i.e., the gate wiring 112, the data wiring 115, the switching element, and the first or second electric field distortion means 133 and 131 which have curvature and do not completely vertically align the liquid crystal molecules. The black matrix layer 122 is provided to prevent light leakage.

However, the black matrix layer 122 overlaps only the field distortion means which is the neutral of the first or second field distortion means (133,131) (see FIG. 9).

In the case of the slit formed by removing the pixel electrode, since the step is low and a vertical alignment layer is further formed on the upper side, the influence of the initial alignment of the liquid crystal molecules due to the curvature of the pattern is insufficient. For reference, the lip has a step of about 1.3 μm and the slit has a step of about 0.05 μm.

The lip is formed of a negative type photo acryl-based or positive type novolac-based dielectric material, and the black matrix layer 122 has a width larger than that of the lip. Make it larger to about 4㎛ and overlap so that light does not leak.

The second field distortion means 131 may be a structure or a slit such as a side electrode or a rib, but in FIG. 7, a lip formed by patterning a low voltage conductive material on a common electrode As shown.

 The second field distortion means 131 is alternately arranged in parallel diagonal lines with the first field distortion means 133 to form a multi-domain in which one pixel region is formed of four regions.

The liquid crystal display device formed as described above uses a negative liquid crystal having a negative dielectric anisotropy and a vertical alignment layer, and in the off state where no voltage is applied, as shown in FIG. 8A, the long axis of the liquid crystal molecules is perpendicular to the alignment layer plane and attached to the substrate. The polarization axis of the polarizer is arranged perpendicular to the long axis of the liquid crystal molecules so as to display a normally black mode.

In this case, the liquid crystal molecules near the second electric field distortion means 131 are vertically arranged so that even if light leakage occurs, the black level may be lowered by the black mattress layer overlapping the portions.

On the other hand, in the on state where voltage is applied, as shown in FIG. 8B, the long axis of the liquid crystal molecules moves toward the alignment layer plane in the vertical direction of the alignment layer plane due to the property of being oriented obliquely with respect to the electric field of the negative liquid crystal molecule. Permeate.

Referring to the present invention according to another embodiment are as follows.

FIG. 10 is a plan view of a liquid crystal display device according to a second embodiment of the present invention, and FIG. 11 is a layout view of a black matrix layer according to the second embodiment of the present invention.

As described with reference to FIG. 10, an ASV mode liquid crystal display device according to an exemplary embodiment of the present invention includes a plurality of gate lines 212 and data lines 215 that cross a lower substrate to define a unit pixel area, and the gate lines. A TFT, which is a switching element formed at the intersection of the 212 and the data lines 215, a pixel electrode 217 partially patterned by a plurality of unit pixel electrodes in a defined unit pixel region, and formed by pixel electrode patterning A depression 233 is provided between the unit pixel electrode and the unit pixel electrode.

The upper substrate includes R, G, and B color filter layers (not shown) formed in a unit pixel region, a common electrode (not shown) that is a transparent conductive film facing the pixel electrode, and the unit pixel electrode ( An island-shaped protrusion 231 disposed at a central position of the 217 and a black matrix layer 222 overlapping the gate wiring 212, the data wiring 215, the TFT, and the protrusion 231 to prevent light leakage. It is provided.

Here, the protrusion 233 is formed in a hemispherical shape at the center of the unit pixel electrode to serve as a lip, and the depression 233 between the unit pixel electrode and the unit pixel electrode at the same distance to the center of the protrusion 231 is formed. It acts like a slit in MVA mode.

11, the black matrix layer 222 is formed only in the field distortion means, which is a protrusion, and does not overlap the depression, because the step difference of the depression formed by removing the pixel electrode is about 0.05 μm, so that the liquid crystal molecules are low. This is because the effect is insignificant even when lying in the slit direction of. However, since the protrusion has a step of about 1.4 μm and the liquid crystal molecules are more inclined toward the protrusion, a light shielding layer for shielding light leakage should be further provided.

In the present invention, the black matrix layer 222 has a width of about 0 μm to 4 μm and overlaps the light not to leak, and the protrusion 231 is a negative type photo acryl series or positive. It is formed of a positive material of Novolac family.

In addition, the dielectric anisotropy is formed as a negative liquid crystal between the upper and lower substrates so that the long axis of the liquid crystal molecules is initially vertically aligned.

The liquid crystal includes a chiral dopant.

When the polarization axis of the polarizing plate is disposed perpendicular to the long axis of the liquid crystal molecules in the liquid crystal display device to display normally black mode, the long axis of the liquid crystal molecules is perpendicular to the alignment layer plane in the off state where no voltage is applied. As a result, black levels are achieved.

In this case, even if light leakage occurs because the liquid crystal molecules near the protrusions are not vertically aligned, the black matrix layer is shielded by the overlapped black matrix layer, thereby reducing the black level and improving the contrast ratio.

On the other hand, when a voltage greater than or equal to the threshold is applied to the liquid crystal display device, the long axis of the liquid crystal molecules, which were initially vertically aligned, is inclined in all directions, such as a fan, to the center of the protrusion of the unit pixel electrode, thereby allowing light to pass through. This is implemented.

On the other hand, the present invention described above is not limited to the above-described embodiment and the accompanying drawings, it is possible that various substitutions, modifications and changes within the scope without departing from the technical spirit of the present invention. It will be apparent to those of ordinary skill in Esau.

That is, since the liquid crystal molecules initially vertically aligned are not completely vertical due to the curvature of the protrusion, all of them may be applicable when light leakage occurs.

In addition, the light shielding layer overlapped to shield light leakage from the protrusion may be separately formed in addition to the black matrix layer.

The liquid crystal display of the present invention as described above has the following effects.

First, the light shielding layer is overlapped to the periphery of the protrusion for distorting the liquid crystal molecules by the electric field, thereby preventing light leakage from the periphery of the protrusion generated when the black level is implemented. As a result, the black level of the liquid crystal display device is increased and the contrast ratio characteristic is improved.

Thus, a liquid crystal display device having excellent image quality can be obtained.

Second, since a black matrix layer is available as a light shielding layer to prevent light leakage, no additional process is required.

Claims (14)

Upper and lower substrates; Gate and data lines vertically intersecting on the lower substrate to define a pixel area; A pixel electrode having a slit formed in the pixel region; A thin film transistor formed at an intersection point of the gate line and the data line and connected to the pixel electrode; A hemispherical lip formed on the upper substrate to form a constant domain with the slit; A black matrix layer formed on the upper substrate so as to overlap the lip, the gate wiring, the data wiring and the thin film transistor; And a liquid crystal layer formed between the upper and lower substrates. The liquid crystal display device of claim 1, wherein the upper substrate further includes a color filter layer and a common electrode. The liquid crystal display of claim 2, wherein the lip is formed on the common electrode. The liquid crystal display device of claim 1, wherein the lip and the slit have an alternating diagonal shape. 2. The liquid crystal display device according to claim 1, wherein the width of the black matrix layer overlapping the lip is larger than the width of the lip by 0 µm to 4 µm. The liquid crystal display of claim 1, further comprising a vertical alignment layer on inner surfaces of the upper and lower substrates. The liquid crystal display device according to claim 1, wherein the liquid crystal layer is a liquid crystal having negative dielectric anisotropy. Upper and lower substrates; Gate and data lines crossing the lower substrate to form a unit pixel area; A pixel electrode having a plurality of unit pixel electrodes formed in the unit pixel area; A thin film transistor formed at an intersection point of the gate line and the data line and connected to the pixel electrode; A hemispherical protrusion formed on the upper substrate to be positioned at the center of each unit pixel electrode; A black matrix layer formed on the upper substrate so as to overlap the protrusion, the gate wiring, the data wiring, and the thin film transistor; And a liquid crystal layer formed between the upper and lower substrates. 10. The liquid crystal display device according to claim 8, wherein the pixel electrode has a slit between the unit pixel electrode and the unit pixel electrode. The liquid crystal display device according to claim 8, wherein the protrusion is formed in an island form. 9. The liquid crystal display device according to claim 8, wherein the width of the black matrix layer overlapping the protrusions is 0 mu m to 4 mu m greater than the width of the protrusions. The liquid crystal display device of claim 8, wherein a vertical alignment layer is further provided on inner surfaces of the upper and lower substrates. The liquid crystal display device according to claim 8, wherein the liquid crystal layer is a liquid crystal having negative dielectric anisotropy. The liquid crystal display device of claim 8, wherein the upper substrate further comprises a color filter layer and a common electrode.

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