Liquid crystal display

Provided is a liquid crystal display including: a first substrate; a first subpixel electrode which is positioned on the first substrate, to which a first voltage is configured to be applied, and which includes first and second subregions; a second subpixel electrode which is positioned on the first substrate, to which a second voltage is configured to be applied, and which includes a third, fourth, and fifth subregions; an insulating layer which is positioned on the first subregion and the third subregion and positioned below the second subregion and the fourth and fifth subregions; a second substrate facing the first substrate; a common electrode which is positioned on the second substrate and to which a common voltage is configured to be applied; and a liquid crystal layer positioned between the first substrate and the second substrate, in which the first subregion and the fourth subregion overlap with each other.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean Patent Application No. 10-2014-0158847 filed in the Korean Intellectual Property Office on Nov. 14, 2014, the entire contents of which are incorporated herein by reference.

BACKGROUND

(a) Technical Field

The present application relates to a liquid crystal display.

(b) Description of the Related Art

A liquid crystal display which is one of the most common types of flat panel displays currently in use, includes two display panels with field generating electrodes such as a pixel electrode, a common electrode, and the like and a liquid crystal layer interposed therebetween.

The liquid crystal display generates an electric field in the liquid crystal layer by applying voltage to the field generating electrodes, and determines the alignment of liquid crystal molecules of the liquid crystal layer by the generated electric field, thus controlling polarization of incident light so as to display images.

The liquid crystal display includes a switching element connected to each pixel electrode, and a plurality of signal lines such as a gate line and a data line for applying voltages to the pixel electrode by controlling the switching element.

Among the liquid crystal displays, a vertically aligned mode liquid crystal display, in which liquid crystal molecules are aligned so that long axes thereof are vertical to display panels while the electric field is not applied, has been in the limelight due to a large contrast ratio and a wide reference viewing angle. Here, the reference viewing angle means a viewing angle having a contrast ratio of 1:10 or a luminance reversion limit angle between grays.

In the case of the vertically aligned mode liquid crystal display, in order to approximate side visibility to front visibility, a method of varying transmittance by dividing one pixel into two subpixels and applying different voltages of the two subpixels is proposed.

However, as such, in the case of approximating the side visibility to the front visibility by dividing one pixel into two subpixels and varying the transmittance, luminance is increased at a low gray or a high gray and thus a gray expression at the side is difficult, and as a result, there is a problem in that image quality deteriorates.

SUMMARY

Embodiments have been made in an effort to provide a liquid crystal display having features of approximating side visibility to front visibility and implementing an accurate color at the side.

An exemplary embodiment provides a liquid crystal display including: a first substrate; a first subpixel electrode which is positioned on the first substrate, to which a first voltage is configured to be applied, and which includes a first subregion and a second subregion; a second subpixel electrode which is positioned on the first substrate, to which a second voltage is configured to be applied, and which includes a third subregion, a fourth subregion, and a fifth subregion; an insulating layer which is positioned on the first subregion of the first subpixel electrode and the third subregion of the second subpixel electrode and positioned below the second subregion of the first subpixel electrode and the fourth subregion and the fifth subregion of the second subpixel electrode; a second substrate facing the first substrate; a common electrode which is positioned on the second substrate and to which a common voltage is configured to be applied; and a liquid crystal layer positioned between the first substrate and the second substrate, in which the first subregion of the first subpixel electrode and the fourth subregion of the second subpixel electrode overlap with each other.

A difference between the first voltage and the common voltage may be larger than a difference between the second voltage and the common voltage.

The liquid crystal display may further include a plurality of pixels, in which the pixels may include a first region in which the second subregion of the first subpixel electrode is positioned, a second region in which the first subregion of the first subpixel electrode and the fourth subregion of the second subpixel electrode overlap with each other, a third region in which the fifth subregion of the second subpixel electrode is positioned, and a fourth region in which the third subregion of the second subpixel electrode is positioned.

Luminance of the first region, the second region, the third region, and the fourth region may be different.

The luminance of the second region may be lower than the luminance of the first region, the luminance of the third region may be lower than the luminance of the second region, and the luminance of the fourth region may be lower than the luminance of the third region.

A first contact hole extending to at least a part of the first subregion of the first subpixel electrode may be formed in the insulating layer, and the second subregion of the first subpixel electrode may be connected with the first subregion of the first subpixel electrode through the first contact hole.

A second contact hole extending to at least a part of the third subregion of the second subpixel electrode may be formed in the insulating layer, and the fourth subregion of the second subpixel electrode may be connected with the third subregion of the first subpixel electrode through the second contact hole.

The third subregion of the second subpixel electrode may include a plurality of first branch electrodes extending in two different directions and a first outer electrode connecting edges of the plurality of first branch electrodes.

The second subregion of the first subpixel electrode may include a cross stem and a plurality of second branch electrodes extending from the cross stem in four different directions.

The fourth subregion of the second subpixel electrode may include a plurality of third branch electrodes extending in two different directions and a second outer electrode connecting edges of the plurality of third branch electrodes.

Some of the third branch electrodes may be extended in the fifth subregion of the second subpixel electrode.

The second outer electrode of the fourth subregion of the second subpixel electrode may be extended to overlap with the first outer electrode.

The second outer electrode and the first outer electrode may be connected to each other.

The first subregion of the first subpixel electrode may have a planar shape.

The first subregion of the first subpixel electrode and the fourth subregion of the second subpixel electrode may be positioned to surround the second subregion of the first subpixel electrode, and the third and fifth subregions of the second subpixel electrode may be positioned to surround the fourth subregion of the second subpixel electrode.

The first subpixel electrode and the second subpixel electrode may be physically and electrically separated from each other.

The first subregion of the first subpixel electrode may be positioned on the same layer as the third subregion of the second subpixel electrode and physically and electrically separated from the third subregion of the second subpixel electrode.

The second subregion of the first subpixel electrode may be positioned on the same layer as the fourth subregion and the fifth subregion of the second subpixel electrode and physically and electrically separated from the fourth subregion and the fifth subregion of the second subpixel electrode.

The liquid crystal display may further include a plurality of pixels, in which the pixels may include a first region in which the second subregion of the first subpixel electrode is positioned, a second region in which the first subregion of the first subpixel electrode and the fourth subregion of the second subpixel electrode overlap with each other, a third region in which the fifth subregion of the second subpixel electrode is positioned, and a fourth region in which the third subregion of the second subpixel electrode is positioned.

The luminance of the second region may be lower than the luminance of the first region, the luminance of the third region may be lower than the luminance of the second region, and the luminance of the fourth region may be lower than the luminance of the third region.

According to the exemplary embodiment, it is possible to approximate side visibility to front visibility and implement an accurate color at the side.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Next, a liquid crystal display according to an exemplary embodiment will be described with reference toFIGS. 1 to 11.

FIG. 1is a layout view of a liquid crystal display according to an exemplary embodiment.FIG. 2is a cross-sectional view of the liquid crystal display ofFIG. 1taken along line II-II.FIG. 3is a layout view of a part of a first subpixel electrode and a part of a second subpixel electrode of the liquid crystal display ofFIG. 1.FIG. 4is a layout view of the other part of the first subpixel electrode and the other part of the second subpixel electrode of the liquid crystal display ofFIG. 1.FIG. 5is an enlarged layout view illustrating a partial region ofFIG. 3.FIG. 6is an enlarged layout view illustrating a partial region ofFIG. 4.FIG. 7is a cross-sectional view taken along line VII-VII ofFIG. 1.FIG. 8is a cross-sectional view taken along line VIII-VIII ofFIG. 1.FIG. 9is a cross-sectional view taken along line IX-IX ofFIG. 1.FIG. 10is a cross-sectional view taken along line X-X ofFIG. 1.FIG. 11is a cross-sectional view taken along line XI-XI ofFIG. 1.

First, referring toFIGS. 1 and 2, a liquid crystal display according to the exemplary embodiment includes a lower panel100and an upper panel200facing each other, and a liquid crystal layer3interposed between the two panels100and200.

First, the lower panel100will be described.

A gate line121, a reference voltage line131, and a storage electrode135are formed on an insulation substrate110made of transparent glass or plastic. The gate line121mainly extends in a horizontal direction and transfers a gate signal.

The gate line121includes a first gate electrode124a,a second gate electrode124b,a third gate electrode124c,and a wide end portion (not illustrated) for connection with another layer or an external driving circuit.

The reference voltage line131may extend in parallel with the gate line121and has an extension136, and the extension136is connected with a third drain electrode175cto be described below.

The reference voltage line131includes the storage electrode135surrounding a pixel area.

A gate insulating layer140is formed on the gate line121, the reference voltage line131, and the storage electrode135.

A first semiconductor154a,a second semiconductor154b,and a third semiconductor154c,which may be made of amorphous or crystalline silicon, are formed on the gate insulating layer140.

A plurality of ohmic contacts163a,163b,163c,165a,165b,and165care formed on the first semiconductor154a,the second semiconductor154b,and the third semiconductor154c.When the semiconductors154a,154b,and154care oxide semiconductors, the ohmic contacts163a,163b,163c,165a,165b,and165cmay be omitted.

A data conductor171,173a,173b173c,175a,175b,and175cincluding a data line171including a first source electrode173aand a second source electrode173b,a first drain electrode175a,a second drain electrode175b,a third source electrode173c,and the third drain electrode175cis formed on the ohmic contacts163a,163b,163c,165a,165b,and165cand the gate insulating layer140.

The second drain electrode175bis connected with the third source electrode173c.

The first gate electrode124a,the first source electrode173a,and the first drain electrode175aform a first thin film transistor Qa together with a first semiconductor154a,and a channel of the first thin film transistor Qa is formed in the first semiconductor154abetween the first source electrode173aand the first drain electrode175a.Similarly, the second gate electrode124b,the second source electrode173b,and the second drain electrode175bform a second thin film transistor Qb together with the second semiconductor154b,and a channel of the second thin film transistor Qb is formed in the second semiconductor154bbetween the second source electrode173band the second drain electrode175b.Further, the third gate electrode124c,the third source electrode173c,and the third drain electrode175cform a third thin film transistor Qc together with the third semiconductor154c,and a channel of the third thin film transistor Qc is formed in the third semiconductor154cbetween the third source electrode173cand the third drain electrode175c.

A first passivation layer180amade of an inorganic insulating material such as silicon nitride or silicon oxide is formed on the data conductor171,173a,173b,173c,175a,175b,175cand the exposed portions of the semiconductors154a,154b,and154c.

A color filter230is positioned on the first passivation layer180a.

A light blocking member (not illustrated) may be positioned on a region where the color filter230is not positioned. The light blocking member is called a black matrix and blocks light leakage.

A capping layer80is positioned on the color filter230. The capping layer80may prevent the color filter230from being lifted and suppress the contamination of the liquid crystal layer3due to an organic material such as a solvent flowing in from the color filter230, thereby preventing defects such as an afterimage which may be caused when a screen is driven.

A part of a first subpixel electrode191aand a part of a second subpixel electrode191bare formed on the capping layer80. A second passivation layer180bis formed on the capping layer80, the part of a first subpixel electrode191a,and the part of a second subpixel electrode191b.The other part of the first subpixel electrode191aand the other part of the second subpixel electrode191bare formed on the second passivation layer180b.The first subpixel electrode191aand the second subpixel electrode191bdefine a pixel electrode191and may be made of transparent metal oxide such as indium tin oxide (ITO) and indium zinc oxide (IZO).

InFIG. 3, a plane shape of the part of the first subpixel electrode191aand the part of the second subpixel electrode191bpositioned below the second passivation layer180bis illustrated, and inFIG. 4, a plane shape of the other part of the first subpixel electrode191aand the other part of the second subpixel electrode191bpositioned on the second passivation layer180bis illustrated.

The first subpixel electrode191aincludes a first subregion191a1and a second subregion191a2, and the second subpixel electrode191bincludes as third subregion191b3, a fourth subregion191b4, and a fifth subregion191b5.

As illustrated inFIG. 3, the first subregion191a1of the first subpixel electrode191a,the third subregion191b3of the second subpixel electrode191b,and a connection electrode195are positioned below the second passivation layer180b.

The first subregion191a1of the first subpixel electrode191aincludes a rod-shaped connection portion positioned at the center of the pixel area and extending in a horizontal direction, and a planar portion positioned around the rod-shaped connection portion and surrounding the rod-shaped connection portion. An extension193is positioned around the center of the rod-shaped connection portion. Further, a protrusion, e.g., vertical rod shaped portions, extending upward and downward from the planar portion is positioned. The planar portion has a plane shape in which four parallelograms are connected to each other. Planar means in a planar shape which is not split as a whole plate. As such, the first subregion191a1of the first subpixel electrode191ais positioned at a part of the pixel area.

The third subregion191b3of the second subpixel electrode191bis positioned below the planar portion of the first subregion191a1of the first subpixel electrode191aon a plan view and includes a plurality of first branch electrodes196b3. The first branch electrodes196b3extend in two directions. Further, the third subregion191b3of the second subpixel electrode191bfurther includes a first outer electrode197b3connecting edges of the first branch electrodes196b3.

The first subregion191a1of the first subpixel electrode191aand the third subregion191b3of the second subpixel electrode191bare formed on the same layer and are electrically separated from each other.

The connection electrode195is electrically separated from the first subpixel electrode191aand the second subpixel electrode191b.The connection electrode195overlaps with the extension136of the reference voltage line131and overlaps with the third drain electrode175c.

As illustrated inFIG. 4, the second subregion191a2of the first subpixel electrode191a,the fourth subregion191b4and the fifth subregion191b5of the second subpixel electrode191bare positioned on the second passivation layer180b.

The second subregion191a2of the first subpixel electrode191ais positioned at the center of the pixel and an overall shape thereof is a rhombus. The second subregion191a2of the first subpixel electrode191aincludes a cross stem having a horizontal portion and a vertical portion and a plurality of second branch electrodes196a2extending from the cross stem. The second branch electrodes196a2extend in four directions.

The fourth subregion191b4and the fifth subregion191b5of the second subpixel electrode191binclude a plurality of third branch electrodes196b4positioned on the same extension line as the first branch electrodes196b3. The third branch electrodes196b4extend in four directions. The second branch electrodes196a2of the second subregion191a2of the first subpixel electrode191aand the third branch electrodes196b4of the fourth subregion191b4and the fifth subregion191b5of the second subpixel electrode191bare spaced apart from each other at predetermined intervals. The fourth subregion191b4and the fifth subregion191b5of the second subpixel electrode191bfurther include a second outer electrode197b4connecting edges of the third branch electrodes196b4.

The fourth subregion191b4of the second subpixel electrode191boverlaps with the first subregion191a1of the first subpixel electrode191a.Particularly, the fourth subregion191b4of the second subpixel electrode191boverlaps with the planar portion of the first subregion191a1of the first subpixel electrode191a.An insulating layer, particularly, the second passivation layer180bis positioned between the fourth subregion191b4of the second subpixel electrode191band the first subregion191a1of the first subpixel electrode191a.

The fourth subregion191b4of the second subpixel electrode191bis positioned at the center of the pixel area. The third branch electrodes196b4positioned at the fourth subregion191b4of the second subpixel electrode191bextend in four directions.

The fifth subregion191b5of the second subpixel electrode191bdoes not overlap with the first subregion191a1of the first subpixel electrode191a.The fifth subregion191b5of the second subpixel electrode191bis positioned above the fourth subregion191b4of the second subpixel electrode191bon a plan view. The third branch electrodes196b4positioned at the fifth subregion191b5extend in two directions. The fifth subregion191b5of the second subpixel electrode191bis disposed on the same extension line as the fourth subregion191b4of the second subpixel electrode191b.A boundary between the fifth subregion191b5and the fourth subregion191b4of the second subpixel electrode191bcorresponds to a boundary between a second region R2and a third region R3.

The second subregion191a2of the first subpixel electrode191aand the fourth subregion191b4and the fifth subregion191b5of the second subpixel electrode191bare formed on the same layer. The second subregion191a2of the first subpixel electrode191ais electrically separated from the fourth subregion191b4and the fifth subregion191b5of the second subpixel electrode191b.The fourth subregion191b4and the fifth subregion191b5of the second subpixel electrode191bare electrically connected to each other.

In the first passivation layer180aand the capping layer80, a first contact hole185aextending to and exposing a part of the first drain electrode175ais formed, a second contact hole185bextending to and exposing a part of the second drain electrode175bis formed, and a third contact hole185cextending to and exposing the extension136of the reference voltage line131and a part of the third drain electrode175cis formed.

The first subregion191a1of the first subpixel electrode191ais physically and electrically connected to the first drain electrode175athrough the first contact hole185a.The first subregion191a1of the first subpixel electrode191areceives a first voltage through the first drain electrode175a.The third subregion191b3of the second subpixel electrode191bis physically and electrically connected to the second drain electrode175bthrough the second contact hole185b.The third subregion191b3of the second subpixel electrode191breceives a second voltage through the second drain electrode175b.In this case, the first subpixel electrode191aand the second subpixel electrode191breceive different data voltages.

The connection electrode195is physically and electrically connected to the extension136of the reference voltage line131through the third contact hole185c,and physically and electrically connected to the third drain electrode175c.Accordingly, the third drain electrode175cis physically and electrically connected to the reference voltage line131.

A fourth contact hole186extending to and exposing an extension193of the exposing an first subregion191a1of the first subpixel electrode191ais formed in the second passivation layer180b.

The second subregion191a2of the first subpixel electrode191ais connected to the extension193of the first subregion191a1of the first subpixel electrode191athrough the fourth contact hole186. The second subregion191a2of the first subpixel electrode191areceives the first voltage through the first subregion191a1of the first subpixel electrode191a.

Referring toFIGS. 5 to 7, a partial region of the first outer electrode197b3of the third subregion191b3of the second subpixel electrode191bhas a larger width than other portions. Particularly, portions of the first outer electrode197b3positioned at both sides with the first subregion191a1of the first subpixel electrode191atherebetween have larger widths than other portions.

The second outer electrode197b4of the fourth subregion191b4of the second subpixel electrode191bconnects the third branch electrode196b4and is extended to overlap with the first outer electrode197b3.

The third subregion191b3of the second subpixel electrode191band the fourth subregion191b4of the second subpixel electrode191bpartially overlap with each other with the insulating layer, particularly, the second passivation layer180btherebetween. Particularly, the first outer electrode197b3of the third subregion191b3of the second subpixel electrode191band the second outer electrode197b4of the fourth subregion191b4of the second subpixel electrode191bpartially overlap with each other with the second passivation layer180btherebetween.

A fifth contact hole187and a sixth contact hole188extending to and exposing a part of the third subregion191b3of the second subpixel electrode191bare formed in the second passivation layer180b.The fifth contact hole187and the sixth contact hole188are formed to expose the portion of the first outer electrode197b3having a larger width than other portions. The fifth contact hole187and the sixth contact hole188are positioned at both sides with the first subregion191a1of the first subpixel electrode191atherebetween on a plan view. The fourth subregion191b4of the second subpixel electrode191bis physically and electrically connected to the third subregion191b3of the second subpixel electrode191bthrough the fifth contact hole187and the sixth contact hole188. The fourth subregion191b4of the second subpixel electrode191breceives a second voltage through the third subregion191b3of the second subpixel electrode191b.

Next, the upper panel200will be described.

A light blocking member220and a common electrode270are formed on an insulation substrate210made of transparent glass or plastic.

However, in the case of a liquid crystal display according to another exemplary embodiment, the light blocking member220may be positioned on the lower panel100, and in the case of the liquid crystal display according to another exemplary embodiment, a color filter may be positioned on the upper panel200.

Alignment layers (not illustrated) are formed on inner surfaces of the display panels100and200, and may be vertical alignment layers.

Polarizers (not illustrated) are provided on outer surfaces of the two panels100and200, and transmissive axes of the two polarizers are orthogonal to each other, and one transmissive axis thereof may be parallel to the gate line121. However, the polarizer may be disposed only on the outer side of any one of the two panels100and200.

The liquid crystal layer3has negative dielectric anisotropy, and the liquid crystal molecules of the liquid crystal layer3are aligned so that long axes thereof are vertical to the surfaces of the two panels100and200while the electric field is not applied. Accordingly, incident light does not pass through an orthogonal polarizer, but is blocked while the electric field is not applied.

At least one of the liquid crystal layer3and the alignment layer may include a photo-reactive material, in more detail, reactive mesogen.

Next, a driving method of the liquid crystal display according to the exemplary embodiment will be briefly described.

When a gate-on signal is applied to the gate line121, the gate-on signal is applied to the first gate electrode124a,the second gate electrode124b,and the third gate electrode124c,and as a result, the first switching element Qa, the second switching element Qb, and the third switching element Qc are turned on. Accordingly, the data voltages applied to the data line171are applied to the first subpixel electrode191aand the second subpixel electrode191bthrough the turned-on first switching element Qa and second switching element Qb, respectively. In this case, the voltages having the same magnitude are applied to the first subpixel electrode191aand the second subpixel electrode191b.However, the voltage applied to the second subpixel electrode191bis divided through the third switching element Qc which is connected with the second switching element Qb in series. Accordingly, the voltage applied to the second subpixel electrode191bis smaller than the voltage applied to the first subpixel electrode191a.

Referring back toFIGS. 1, 3, and 4, one pixel area of the liquid crystal display according to the exemplary embodiment is configured by a first region R1in which the second subregion191a2of the first subpixel electrode191ais positioned, the second region R2in which the first subregion191a1of the first subpixel electrode191aand the fourth subregion191b4of the second subpixel electrode191boverlap with each other the third region R3in which the fifth subregion191b5of the second subpixel electrode191bis positioned, and a fourth region R4in which the third subregion191b3of the second subpixel electrode191bis positioned.

The first region R1and the second region R2are divided into four portions in directions of the branch electrodes, and the third region R3and the fourth region R4are divided into two portions in directions of the branch electrodes.

Next, the first region R1, the second region R2, the third region R3, and the fourth region R4included in one pixel area of the liquid crystal display of the exemplary embodiment will be described with reference toFIGS. 8 to 11.

Referring toFIG. 8, in the first region R1of one pixel area of the liquid crystal display of the exemplary embodiment, an electric field is generated between the second subregion191a2of the first subpixel electrode191apositioned on the lower panel100and the common electrode270positioned on the upper panel200. The second subregion191a2of the first subpixel electrode191ais connected to the extension193of the first subregion191a1of the first subpixel electrode191ato receive the first voltage and a common voltage is applied to the common electrode270. In this case, the second subregion191a2of the first subpixel electrode191aincludes a cross stem and a plurality of second branch electrodes196a2extending in four different directions. The plurality of second branch electrodes196a2may be tilted at about 40° to about 45° based on the gate line121. By a fringe field generated by the edges of the plurality of second branch electrodes196a2, liquid crystal molecules of the liquid crystal layer3positioned in the first region R1are reclined in four different directions. In more detail, since a horizontal component of the fringe field by the plurality of second branch electrodes196a2is substantially horizontal to the side of the plurality of second branch electrodes196a2, the liquid crystal molecules are tilted in a parallel direction to the length direction of the plurality of second branch electrodes196a2.

Referring toFIG. 9, in the second region R2of one pixel area of the liquid crystal display of the exemplary embodiment, the fourth subregion191b4of the second subpixel electrode191band the first subregion191a1of the first subpixel electrode191aoverlap with each other. The liquid crystal molecules of the liquid crystal layer3are aligned by electric fields in addition to the electric field generated between the fourth subregion191b4of the second subpixel electrode191bpositioned on the lower panel and the common electrode270positioned on the upper panel200. More particularly, by an electric field generated between the first subregion191a1of the first subpixel electrode191apositioned between the plurality of third branch electrodes196b4of the fourth subregion191b4of the second subpixel electrode191band the common electrode270, and an electric field generated between the fourth subregion191b4of the second subpixel electrode191band the first subregion191a1of the first subpixel electrode191a,the liquid crystal molecules of the liquid crystal layer3are additionally aligned. The fourth subregion191b4of the second subpixel electrode191bis connected to the third subregion191b3of the second subpixel electrode191bto receive the second voltage. In this case, the fourth subregion191b4of the second subpixel electrode191bincludes the plurality of third branch electrodes196b4extending in four different directions. The plurality of third branch electrodes196b4may be tilted at about 40° to about 45° based on the gate line121. By a fringe field generated by the edges of the plurality of third branch electrodes196b4, liquid crystal molecules of the liquid crystal layer3positioned in the second region R2are reclined in four different directions. In detail, the liquid crystal molecules are tilted in a parallel direction to the length direction of the plurality of third branch electrodes196b4.

Referring toFIG. 10, in the third region R3of one pixel area of the liquid crystal display of the exemplary embodiment, an electric field is generated between the fifth subregion191b5of the second subpixel electrode191bpositioned on the lower panel100and the common electrode270positioned on the upper panel200. The fifth subregion191b5of the second subpixel electrode191bis connected to the fourth subregion191b4of the second subpixel electrode191bto receive the second voltage. The fifth subregion191b5of the second subpixel electrode191bincludes a plurality of third branch electrodes196b4extending in two different directions. The third branch electrodes196b4in two directions among the third branch electrodes196b4in the four directions positioned in the fourth subregion191b4of the second subpixel electrode191bare extended up to the fifth subregion191b5of the second subpixel electrode191b.

Referring toFIG. 11, in the fourth region R4of one pixel area of the liquid crystal display of the exemplary embodiment, an electric field is generated between the third subregion191b3of the second subpixel electrode191bpositioned on the lower panel100and the common electrode270positioned on the upper panel200. The second voltage is applied to the third subregion191b3of the second subpixel electrode191b.The third subregion191b3of the second subpixel electrode191bincludes a plurality of first branch electrodes196b3extending in two different directions. The first branch electrode196b3extends in the same direction as the directions of some of the third branch electrodes196b4positioned in the fourth subregion191b4of the second subpixel electrode191band extends in a different direction to the directions of the third branch electrodes196b4positioned in the fifth subregion191b5of the second electrode191b.By a fringe field generated by the edges of the plurality of first branch electrodes196b3, liquid crystal molecules of the liquid crystal layer3positioned in the fourth region R4are reclined in two different directions. In detail, the liquid crystal molecules are tilted in a parallel direction to the length direction of the plurality of first branch electrodes196b3.

As described above, the magnitude of the second voltage applied to the second subpixel electrode191bis smaller than the magnitude of the first voltage applied to the first subpixel electrode191a.

In the exemplary embodiment, the intensity of the electric field applied to the liquid crystal layer3positioned in the first region R1is largest, and the intensity of the electric field applied to the liquid crystal layer3positioned in the second region R2is smaller than the intensity of the electric field applied to the liquid crystal layer3positioned in the first region R1. The intensity of the electric field applied to the liquid crystal layer3positioned in the third region R3is smaller than the intensity of the electric field applied to the liquid crystal layer3positioned in the second region R2and smaller than the intensity of the electric field applied to the liquid crystal layer3positioned in the fourth region R4.

In the second region R2, since an influence by the electric field of the first subpixel electrode191apositioned below the second subpixel electrode191bexists, the intensity of the electric field applied to the liquid crystal layer3positioned in the second region R2is smaller than the intensity of the electric field applied to the liquid crystal layer3positioned in the first region R1and larger than the intensity of the electric field applied to the liquid crystal layer3positioned in the third region R3.

In the fourth region R4, since an insulation layer is further interposed between the two electrodes generating the electric fields as compared with the third region R3, the intensity of the electric field in the fourth region R4is smaller than the intensity of the electric field applied to the liquid crystal layer3positioned in the third region R3. In the third region R3, the fifth subregion191b5of the second subpixel electrode191bis formed on the second passivation layer180b,and in the fourth region R4, the third subregion191b3of the second subpixel electrode191bis formed below the second passivation layer180b.Even though the same second voltage is applied to the fifth subregion191b5and the third subregion191b3of the second subpixel electrode191b,the intensity of the electric field applied to the liquid crystal layer3is relatively decreased in the fourth region R4due to the influence by the second passivation layer180b.

As such, in the liquid crystal display according to the exemplary embodiment, one pixel area is divided into the first region R1in which the first subpixel electrode191ato which the relatively high first voltage is applied is positioned, the second region R2in which a part of the first subpixel electrode191aand a part of the second subpixel electrode191bto which the relatively low second voltage is applied overlap with each other with the insulating layer therebetween, the third region R3in which the second subpixel electrode191bto which the relatively low second voltage is applied is positioned, and the fourth region R4in which the second subpixel electrode191bis covered by the insulating layer. The intensities of the electric fields applied to the liquid crystal molecules corresponding to the first region R1, the second region R2, the third region R3, and the fourth region R4are different from each other, the tilted angles of the liquid crystal molecules are different from each other, and as a result, luminance of each region varies. As such, one pixel area is divided into four regions having different luminance to gradually control a change in transmittance according to a gray and thus the transmittance according to a gray change even in the low gray and the high gray is prevented from being rapidly changed at the side, and as a result, even while the side visibility is approximated to the front visibility, accurate grays can be expressed even in the low gray and the high gray.

Hereinafter, an appearance of actually manufacturing the liquid crystal display according to the exemplary embodiment will be described with reference toFIG. 12.

FIG. 12is a plane photograph of the liquid crystal display according to the exemplary embodiment.

As illustrated inFIG. 12, the portion positioned at the most central part is the first region in which the largest electric field is generated and has the highest luminance. The second region surrounding the first region has luminance which is relatively lower than the first region. The third region and the fourth region positioned at the outside of the second region have luminance which is lower than the second region. When comparing the third region positioned above the second region with the fourth region positioned below the second region, it can be seen that the fourth region has luminance which is lower than that of the third region. As such, one pixel is configured by four regions having different transmittance and as a result, the side visibility may be controlled to be approximated to the front visibility.

Hereinafter, side visibility of the liquid crystal display according to the exemplary embodiment will be described with reference toFIG. 13.

FIG. 13is a graph illustrating luminance according to a gray of the liquid crystal display according to the exemplary embodiment. InFIG. 13, luminance (front side) according to a gray when viewing the liquid crystal display from the front side and luminance (exemplary embodiment) according to a gray when viewing the liquid crystal display at the side are illustrated. In this case, luminance (reference example) according to a gray when viewing a liquid crystal display according to a reference example configured by a different structure from the exemplary embodiment from the side is illustrated together. As a graph at the side is close to a graph at the front side, the side visibility is high.

In the liquid crystal display according to the exemplary embodiment, one pixel is configured by four regions having different luminance. The four regions are configured by a first region, a second region having lower luminance than first region, a third region having lower luminance than the second region, and a fourth region having lower luminance than the third region. In this case, an area ratio of the first region, the second region, the third region, and the fourth region may be 1:2:3:3. Further, a voltage ratio of the first region, the second region, the third region, and the fourth region may be 1:0.8:0.65:0.59.

In the liquid crystal display according to the reference example, one pixel is configured by three regions having different luminance. The three regions are configured by a first region, a second region having lower luminance than the first region, and a third region having lower luminance than the second region. In this case, an area ratio of the first region, the second region, and the third region may be 1:2:6. Further, a voltage ratio of the first region, the second region, and the third region may be 1:0.8:0.65.

It can be seen that a graph of a change in side luminance of the liquid crystal display according to the exemplary embodiment is closer to a graph of a change in front luminance than a graph of a change in side luminance of the liquid crystal display according to the reference example. Accordingly, in the liquid crystal display according to the exemplary embodiment, it can be seen that one pixel is configured by four regions having different luminance, and as a result the side visibility may be improved.

Further, when describing the graph of the change in side luminance of the liquid crystal display according to the exemplary embodiment, it can be seen that a period in which a variation rate of luminance according to a change in grays is rapidly changed is decreased as compared with the reference example. As a result, accurate grays can be expressed and image quality may be improved.

<Description of symbols>100: Lower panel110, 210: Insulation substrate121: Gate line131: Reference voltage line135: Storage electrode136: Extension of reference voltage line171: Data line180a: First passivation layer180b: Second passivation layer191a: First subpixel electrode191a1: First subregion of first subpixel electrode191a2: Second subregion of first subpixel electrode191b: Second subpixel electrode191b3: Third subregion of second subpixel electrode191b4: Fourth subregion of second subpixel electrode191b5: Fifth subregion of second subpixel electrode196b3: First branch electrode196a2: Second branch electrode196b4: Third branch electrode197b3: First outer electrode197b4: Second outer electrode200: Upper panel270: Common electrode