Liquid crystal display and manufacturing method thereof

A liquid crystal display may include a first substrate, a second substrate facing the first substrate, a liquid crystal layer comprising liquid crystal molecules that are interposed between the first substrate and the second substrate, a first electrode disposed on the first substrate, an insulating layer disposed on the first electrode, a second electrode disposed on the insulating layer, a third electrode disposed on the second substrate, and an alignment layer disposed on any one of the second electrode and the third electrode. The second electrode comprises a fine slit structure, and at least one of the liquid crystal layer and the alignment layer comprises a sub-alignment substance.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean Patent Application No. 10-2010-0112002, filed on Nov. 11, 2010, which is hereby incorporated by reference for all purposes as if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Exemplary embodiments of the present invention relate to a liquid crystal display and a manufacturing method thereof.

2. Discussion of the Background

Liquid crystal displays, which are a popular type of flat panel display, are composed of two panels with field generating electrodes such as a pixel electrode and a common electrode and have a liquid crystal layer therebetween.

Liquid crystal displays display images by controlling the transmission of light through the display from a light source. To control the light transmission, the display generates an electric field in a liquid crystal layer by applying voltages to the field generating electrodes. The electric field determines the alignment of the liquid crystal molecules in the liquid crystal layer, which controls the polarization of light from the light source.

The liquid crystal displays may also have a switching element connected to the pixel electrodes and a plurality of signal lines such as gate lines or data lines, which apply voltage to the pixel electrodes by controlling the switching element.

In the liquid crystal displays, a vertically-aligned mode liquid crystal display arranges the long axes of the liquid crystal molecules perpendicular to the display panel when an electric field is not applied is interesting because this display may have a large contrast ratio and wide viewing angle.

The vertically-aligned mode liquid crystal display may arrange the liquid crystal molecules in various directions using a fringe electric field; however, the display's light transmittance may be reduced by the horizontal component of the electric field in the fringe electric field.

The above information disclosed in this section is only for enhancement of understanding of the background of the invention and may contain information that does not form the prior art.

SUMMARY OF THE INVENTION

Exemplary embodiments of the present invention provide a liquid crystal display and a method of manufacturing the liquid crystal display that may prevent transmittance from being reduced by a horizontal component of the electric field.

An exemplary embodiment of the present invention provides a liquid crystal display including: a first substrate; a second substrate facing the first substrate; a liquid crystal layer including liquid crystal molecules and interposed between the first substrate and the second substrate; a first electrode disposed on the first substrate; an insulating layer disposed on the first electrode; a second electrode disposed on the insulating layer; a third electrode disposed on the second substrate; and an alignment layer disposed on at least one of the second electrode and the third electrode, in which the second electrode includes a fine slit structure and at least one of the liquid crystal layer and the alignment layer includes a sub-alignment substance.

The liquid crystal display further may include: a gate line disposed on the second substrate; a data line crossing the gate line and disposed on the second substrate; and a thin film transistor connected to the gate line and the data line, in which the thin film transistor may be connected with the third electrode.

The first electrode and the third electrode may be plates.

The first electrode may be configured to receive a first voltage, the second electrode may be configured to receive a second voltage, the third electrode may be configured to receive a third voltage, the second voltage and the third voltage being different from each other, and at least one of the liquid crystal layer and the alignment layer may be exposed to radiation from a light source

The liquid crystal display may be configured so that, during operation, a vertical electric field is generated by a difference between the first voltage and the third voltage.

The liquid crystal display may be configured so that, during operation, the second electrode is floated, and first voltage and the third voltage are different from each other.

The liquid crystal display may be configured so that, during operation, the first voltage and the second voltage are identical, and both the first voltage and the second voltage are different from the third voltage.

The liquid crystal display may be configured so that, during operation, the first voltage, the second voltage, and the third voltage are different from each other.

The thickness of the insulating layer may be less than or equal to 3.5 μm.

The dielectric constant of the insulating layer may ranges from 1.5 to 8.5.

The second electrode may include a cross stem including a transverse stem and a longitudinal stem intersecting the transverse stem, and a plurality of fine branches extending from the cross stem.

The second electrode may include a plurality of regions corresponding to groups of fine branches that extend in different directions from the cross stem.

The second electrode may include a cross opening including a transverse opening and a longitudinal opening, and a plurality of fine opening patterns extending from the cross opening.

The second electrode may include fine branches disposed between the fine opening patterns, and an edge pattern connecting ends of the fine branches.

The alignment layer may comprise the sub-alignment substance, and the sub-alignment substance has a negative dielectric anisotropy.

The alignment layer may include a main-chain and a side-chain connected to the main-chain, and the sub-alignment substance may be connected to the side-chain.

Another exemplary embodiment of the present invention provides a method of manufacturing a liquid crystal display, including: forming a first electrode on a first substrate; forming an insulating layer on the first electrode; forming a second electrode on the insulating layer; forming a third electrode on a second substrate facing the first substrate; forming an alignment layer on at least one of the second electrode and the third electrode; assembling the first substrate with the second substrate; disposing a liquid crystal layer between the first substrate and the second substrate; applying different voltages to the second electrode and the third electrode; and radiating light to the liquid crystal layer while applying the different voltages to the second electrode and the third electrode, in which the second electrode comprises formed in a fine slit structure, and at least one of the liquid crystal layer and the alignment layer includes a sub-alignment substance.

The method of manufacturing a liquid crystal display may further include forming a gate line on the second substrate, forming a data line crossing the gate line and disposed on the second substrate, and forming a thin film transistor connected to the gate line and the data line, in which the thin film transistor may be connected to the third electrode.

The method of manufacturing a liquid crystal display may further include applying a first voltage (V1) to the first electrode, wherein applying different voltages to the second electrode and the third electrode comprises: applying a second voltage (V2) to the second electrode; and applying a third voltage (V3) to the third electrode, wherein the first voltage, the second voltage, and the third voltage satisfy the condition that |V2−V3|≧|V1−V3|

The applying different voltages to the second electrode and the third electrode may include changing the second voltage while maintaining the first voltage and the third voltage.

The method of manufacturing a liquid crystal display may further include increasing the first voltage after beginning the change in the second voltage.

The method of manufacturing a liquid crystal display may further include radiating light to the liquid crystal layer, without an electric field, after radiating light to the liquid crystal layer.

The forming of a first electrode, an insulating layer, and a second electrode on the first substrate may include sequentially forming a first transparent electrode layer, an insulating material layer, and a second transparent electrode layer on the first substrate, forming a photoresist pattern on the second transparent electrode layer, etching the second transparent electrode layer, using the photoresist pattern as a mask, and etching the insulating material layer, using the photoresist pattern as a mask.

Another exemplary embodiment of the present invention provides a liquid crystal display, comprising: a first panel comprising a first electrode; and a second panel facing the first panel and comprising: a substrate; a second electrode disposed on the substrate; an insulating layer disposed on the second electrode; and a third electrode comprising slits and disposed on the insulating layer, wherein the first electrode is configured to receive a first voltage (V1), the second electrode is configured to receive a second voltage (V2), the third electrode is floated, and the first voltage and the third voltage satisfy the condition that V1≠V2.

The liquid crystal display may be configured so that, during operation, a vertical electric field is generated by a difference between the first voltage and the second voltage.

The third electrode may be disposed in a pixel region.

Exemplary embodiments of the present invention also provide a liquid crystal display with high transmittance and high response for alignment of liquid crystal molecules.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

It will be understood that when an element or layer is referred to as being “on,” “connected to,” or “coupled to” another element or layer, it can be directly on, directly connected to, directly coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly connected to,” or “directly coupled to” another element or layer, there are no intervening elements or layers present. Further, the thickness of layers and regions may be exaggerated for clarity in the drawings.

FIG. 1is a layout view showing a liquid crystal display according to an exemplary embodiment of the present invention.FIG. 2is a cross-sectional view taken along line II-II′ ofFIG. 1.

Referring toFIG. 1andFIG. 2, a liquid crystal display according to the exemplary embodiment includes a lower panel100and an upper panel200, which are opposite to each other, a liquid crystal layer3disposed between the display panels100and200, and a pair of polarizers (now shown) attached to the outer sides of the display panels100and200.

The upper panel200has a light blocking member220on a transparent and insulating upper substrate210, which is a first substrate. The light blocking member220is also called a black matrix and prevents light leakage between pixel electrodes191on the lower display panel100, which is described below. The light blocking member220has a plurality of openings having substantially the same shapes as those of the pixel electrodes191and arranged opposite of the pixel electrodes191. The light blocking member220, however, may be composed of a portion corresponding to a gate line121and a data line171and a portion corresponding to a thin film transistor.

A plurality of color filters230is further on the substrate210. Most of the color filters230are in the region surrounded by the light blocking member220and may longitudinally extend along the column of the pixel electrodes191. The color filter230may be colored as one of the primary colors, e.g., red, green and blue. However, the color filter230is not limited to the three primary colors of red, green and blue and may also have one of a cyan-based, a magenta-based, a yellow-based, and a white-based color.

At least one of the light blocking member220and the color filter230may be formed on the lower substrate110.

An overcoat250may be arranged on the color filter230and the light blocking member220. The overcoat250may be made of an insulating material and may prevent the color filter230from being exposed and provides a flat surface. The overcoat250may be omitted.

A common electrode270may be arranged on the overcoat250. The common electrode270may be formed as a plate in a pixel region. The common electrode, when formed as a plate, may be a non-split whole plate.

An insulating layer280may be disposed on the common electrode270. The insulating layer280may have a thickness of less than or equal to 3.5 μm and may have a dielectric constant from about 1.5 to about 8.5.

A fine slit electrode300including a transverse stem320, a longitudinal stem330, a fine branch340is disposed on the insulating layer280. The fine slit electrode300may be electrically connected with the common electrode270or may be floated. The fine slit electrode300is described in detail below.

The lower panel100is described next.

A plurality of gate lines121is disposed on the insulating lower substrate110, which corresponds to a second substrate. The gate lines121may extend transversely, transmitting gate signals. The gate lines121include a gate electrode124protruding upward and a wide end129for connecting with another layer or a gate driver (not shown). The gate drivers (not shown) may be disposed on the lower substrate110, and the gate lines121may extend to be connected to them.

A gate insulating layer140made of an insulating material, such as silicon nitride, is disposed on the gate lines121.

A plurality of semiconductor layers151may be made of hydrogenated amorphous silicon or polysilicon is disposed on the gate insulating layer140. The semiconductor layer151may extend longitudinally and includes a plurality of projections154protruding due to the height of the gate electrode124.

A plurality of ohmic contact stripes161and ohmic contact islands165are disposed on the protrusion154of the semiconductor layer151. The ohmic contact stripe161has a plurality of protrusions163, and the protrusions163and the ohmic contact islands165are arranged in pairs on the projections154of the semiconductor layer151.

Data conductors171and175including a plurality of data lines171and a plurality of drain electrodes175are disposed on the ohmic contacts161and165and the gate insulating layer140.

The data lines171transmit data signals and may extend longitudinally to cross with the gate lines121. The gate lines121and the data lines171are insulated from each other by the gate insulating layer140. Each data lines171includes a plurality of source electrodes173that extend in a U-shape toward the gate electrode124and a wide end179having a large area for connecting with another layer or the data driver (not shown).

The drain electrode175is separated from the data line171and the source electrode173and extends upward in the middle of the U-shape of the source electrode173.

Data conductors171and175, semiconductor layers151and154, and ohmic contacts161,163, and165under the data conductors may be simultaneously formed using one mask.

A passivation layer180is on the data conductors171and175and the exposed semiconductor layer154. The passivation layer180may be made of an inorganic insulating material such as silicon nitride and silicon oxide, or the passivation layer180may be made of an organic insulating material and may attain a flat surface. When made of an organic insulating material, the passivation layer180may have photosensitivity and may have a dielectric constant of less than or about 5.0. The passivation layer180may also have a double layer structure of an upper organic layer and a lower inorganic layer to protect the exposed portion of the semiconductor154from damage while maintaining high electrical insulation, characteristic of insulating organic materials.

A contact hole185that exposes the drain electrode175is formed in the passivation layer180.

A plurality of pixel electrodes191and a plurality of contact assistants81and82are disposed on the passivation layer180and may be made of transparent conductive materials, such as indium tin oxide (ITO) or indium zinc oxide (IZO), or a reflective metal, such as aluminum, silver, chromium, or alloys of them.

The pixel electrode191may be formed in a plate for each unit pixel region.

Alignment layers11and21are disposed on the inner sides of the lower and upper panels100and200, respectively, and may be vertical mode type of alignment layers.

Polarizers (not shown) may be disposed on the outer sides of the lower and upper panels100and200and may have their polarization axes orthogonal to each other with one of the polarizer's polarization axis parallel to the gate line121. One of the polarizers may be omitted if the display is a reflective liquid crystal display.

A liquid crystal layer3is interposed between the upper and lower panels100and200and includes liquid crystal molecules310having a negative dielectric anisotropy. The liquid crystal molecules310in the liquid crystal layer3may have a pretilt such that the long axes are substantially parallel to the longitudinal direction of the fine branch340of the fine slit electrode300and may be aligned to be perpendicular to the surfaces of the display panels100and200when an electric field is not applied. Further, the liquid crystal layer3further includes a sub-alignment substance50containing at least one reactive mesogen, such that the liquid crystal molecules310may have the pretilt such that the long axes are substantially parallel with the longitudinal direction of the fine branch340of the fine slit electrode300by the sub-alignment substance50.

In another exemplary embodiment of the present invention, the sub-alignment substance50may be included in the alignment layers11and21instead of within the liquid crystal layer3. In this case, the constituent compounds of the alignment layers11and21may include a main-chain and a side-chain so that the sub-alignment substance50may connect with the side-chain and may have negative dielectric anisotropy. As an additional exemplary embodiment, the sub-alignment substance50may be included in both the liquid crystal layer3and the alignment layers11and21.

The sub-alignment substance50with negative dielectric anisotropy and connected with the side-chain of the alignment layers11and21may have the structure shown in Formula I below. The sub-alignment substance50with negative dielectric anisotropy may be more easily aligned by an electric field than a sub-alignment substance50that has a neutral dielectric anisotropy. This is because the sub-alignment substance50with neutral dielectric anisotropy has very little internal energy permutation in the presence of an electric field, as compared with the sub-alignment substance50that may connect with the side-chain of the alignment layers11and21.

The fine slit electrode300is described below with reference toFIG. 3.

FIG. 3is a layout view showing the fine slit electrode300of the exemplary embodiment shown inFIG. 1.

Referring toFIG. 3, the shape of the fine slit electrode300is a quadrangle and includes a cross stem composed of a transverse stem320and a longitudinal stem330intersecting the transverse stem320. Further, four sub-regions are defined by the transverse stem320and the longitudinal stem330, and each of the sub-regions includes a plurality of fine branches340.

Ones of the fine branches340of the fine slit electrode300extend at an angle to the left upper side from the transverse stem320or the longitudinal stem330and other fine branches340extend at an angle to the right upper side from the transverse stem320or the longitudinal stem330. Further, ones of the fine branches340extend at an angle to the left lower side from the transverse stem320or the longitudinal stem330and the other fine branches340extend at an angle to the right lower side from the transverse stem320or the longitudinal stem330. The fine branches340of two adjacent sub-regions may be perpendicular to each other. Further, the fine branches340of two adjacent sub-regions may not be perpendicular but may form obtuse or acute angles with respect to each other, and the distribution of angles between neighboring sub-regions may not be constant. Though not shown, the width of the fine branch340may gradually increase either away or toward the longitudinal and transverse stems330and320.

FIG. 4is a cross-sectional view showing an electric field direction within the portion indicated by “A” of the exemplary embodiment shown inFIG. 3.

Referring toFIG. 4, a fringe field is generated, when voltage is applied to the fine slit electrode300and the pixel electrode191. Within the electric field, the liquid crystal molecules310align toward the outside of the pixel region, i.e., in a direction shown by arrow D1inFIG. 3andFIG. 4. In detail, the liquid crystal molecules310are arranged in a predetermined direction because only strong fringe fields exist at areas corresponding to non-electrodes between the fine branches340of the fine slit electrode300. The final domain direction of the whole liquid crystal molecules is determined by the internal energy among the liquid crystal molecules310aligned in the predetermined direction by means of a vertical electric field established by the fine branches340.

Hereinafter, a liquid crystal display according to another exemplary embodiment of the present invention is described with reference toFIG. 5,FIG. 6, andFIG. 7.FIG. 5is a layout view showing a liquid crystal display according to another exemplary embodiment of the present invention.FIG. 6a layout view showing a fine slit electrode of the exemplary embodiment shown inFIG. 5.

Referring toFIG. 5andFIG. 6, a liquid crystal display according to the exemplary embodiment has a structure similar to that of the liquid crystal display of the exemplary embodiment shown inFIG. 2. The descriptions for the similar parts may not be repeated.

The liquid crystal display according to the exemplary embodiment has a different structure for the fine slit electrode from the liquid crystal display according to the exemplary embodiment shown inFIG. 1andFIG. 2. The liquid crystal display according to the exemplary embodiment includes a cross opening composed of a transverse opening420and a longitudinal opening430intersecting the transverse opening420. Further, four sub-regions are defined by the transverse opening420and the longitudinal opening430, and each sub-region includes a plurality of fine branches440. A plurality of fine opening patterns extending from the cross opening is formed between the fine branches440. In the exemplary embodiment, the fine slit electrode400includes a quadrangular edge pattern450connecting the fine branches440. That is, the edge pattern450connects the fine branches440at one end of each of the fine branches440.

Many characteristics of the liquid crystal display according to the exemplary embodiment shown inFIG. 1andFIG. 2may be applied to the liquid crystal display according to the exemplary embodiment shown inFIG. 5andFIG. 6.

FIG. 7is a cross-sectional view showing an electric field direction of the exemplary embodiment shown inFIG. 6. In detail,FIG. 7shows an electric field direction at the portion indicated by “A” inFIG. 6.

Referring toFIG. 7, a fringe field is generated, when voltage is applied to the fine slit electrode400and the pixel electrode191, such that the liquid crystal molecules310align their long axes toward the inside of the pixel region (as indicated by the arrows D2inFIG. 6andFIG. 7). In detail, the liquid crystal molecules310are arranged, i.e., aligned, in a predetermined direction because only strong fringe electric fields exist at the interface between regions of non-electrode portions and the fine branches440of the fine slit electrode400. The final domain direction of ensembles of liquid crystal molecules in the sub-regions is determined by the strength of the perturbation of the internal energy among the liquid crystal molecules310aligned in the predetermined direction by means of the vertical electric field established by the pixel electrode191and the fine branches440.

Hereinafter, a method of manufacturing a liquid crystal display according to another exemplary embodiment of the present invention is described with reference toFIG. 1,FIG. 2, andFIG. 8.FIG. 8is a cross-sectional view showing a liquid crystal display according to another exemplary embodiment of the present invention.

Referring toFIG. 1andFIG. 2, the manufacture of the first display panel100and the second display panel200are described first.

The upper panel200may be manufactured as follows.

The light blocking member220and the color filters230are formed on the first substrate210, and then an overcoat250is formed thereon. The common electrode270is formed on the overcoat250, and then the insulating layer280is formed thereon. The fine slit electrode300including the transverse stem320, the longitudinal stem330, and the fine branches340is formed on the insulating layer280. Subsequently, the alignment layer21is formed on the fine slit electrode300.

The lower panel100may be manufactured as follows.

The gate line121including the gate electrode124, the gate insulating layer140, the semiconductor layers151and154, the data line171including the source electrode173, the drain electrode175, and the passivation layer180are formed on the second substrate110by disposing and patterning a plurality of thin layers.

The pixel electrode191is formed by disposing and patterning a conductive layer made of ITO or IZO on the passivation layer180. Next, the alignment layer11is disposed on the pixel electrode191.

Thereafter, the lower panel100and the upper panel200, which have been made as described above, are coupled, and the liquid crystal layer3is formed by injecting a mixture of the liquid crystal molecules310and the sub-alignment substance50between the lower and upper panels100and200. Alternatively, the liquid crystal layer3may be formed by applying a mixture of the liquid crystal molecules310and the sub-alignment substance50on the lower panel100or the upper panel200. Although the sub-alignment substance50may be contained in the liquid crystal layer3in the exemplary embodiment, the sub-alignment substance50may be contained in the alignment layers11and12instead of the liquid crystal layer3as another exemplary embodiment.

Thereafter, referring toFIG. 8, a voltage is applied to the pixel electrode191and the fine slit electrode300. A first voltage V1may be applied to the common electrode270; a second voltage V2may be applied to the fine slit electrode300, and a third voltage V3may be applied to the pixel electrode191. The second voltage V2and the third voltage V3may be different, but under some conditions these voltages may be the same.

Generally, a voltage may be applied to the electrodes191,270, and300such that the first voltage V1, the second voltage V2, and the third voltage V3satisfy the following condition (1).
|V2−V3|≧|V1−V3|  (1).

That is, a fringe field E is generated when the magnitude of the difference between the second voltage V2and the third voltage V3is greater than magnitude of the difference of the first voltage V1and the third voltage V3.

Next, with the fringe field E ofFIG. 8generated, light is radiated to the liquid crystal display according to the exemplary embodiment. Accordingly, the liquid crystal molecule310may be provided with a pretilt.

FIG. 9is a graph showing voltage applied under electric field exposure in the method of manufacturing a liquid crystal display according to another exemplary embodiment of the present invention.FIG. 10is an optical microscopy picture of a fine slit electrode in a liquid crystal display of the exemplary embodiment ofFIG. 9.

Referring toFIG. 9, when an electric field is present and light is radiated, the second voltage V2is gradually increased as the first voltage V1and the third voltage V3are kept constant so that texture may not be generated by the fringe field between the upper substrate210and the lower substrate110. In this manner, the liquid crystal direction may be controlled.

FIG. 11is a graph showing voltage applied under electric field exposure in the method of manufacturing a liquid crystal display according to another exemplary embodiment.FIG. 12is an optical microscopy picture of a fine silt electrode in a liquid crystal display manufactured by the exemplary embodiment ofFIG. 11.

Referring toFIG. 11, uniform control of the pretilt of the liquid crystal molecules may be established at the portions of the fine slit electrode by additionally increasing the first voltage V1after a predetermined time. This may be accomplished in the method of applying voltage with electric field exposure as described with reference to the exemplary embodiment shown inFIG. 9.FIG. 11shows the time when the first voltage V1increases (in a step function manner) occurs when the second voltage V2becomes constant, which is an exemplary embodiment of the present invention. The time when the first voltage V1increases may be earlier or later than the time when the second voltage V2becomes constant in another exemplary embodiment.

ComparingFIG. 10withFIG. 12, dark portions (e.g., the dark stripes) generated at the non-electrodes of the fine slit electrode decreased more in the liquid crystal display manufactured by the exemplary embodiment shown inFIG. 11than for the liquid crystal display manufactured by the exemplary embodiment shown inFIG. 9.

FIG. 13is a cross-sectional view showing an electric field direction when activating a liquid crystal display manufactured by the exemplary embodiment shown inFIG. 8.

The liquid crystal display according to the exemplary embodiment may operate in one of the following conditions (2), (3), and (4).
V1≠V3(fine slit electrode floated)  (2).
V1=V2≠V3  (3).
V1≠V2≠V3  (4).

In the exemplary embodiment, the liquid crystal molecules may be aligned between the common electrode270and the pixel electrode191by the vertical electric field E in any of the above conditions (2), (3), and (4). That is, as shown inFIG. 13, the vertical electric field E is generated between the common electrode270and the pixel electrode191.

Therefore, the liquid crystal molecules are usually aligned by only the vertical electric field while the liquid crystal display operates so the reduction of transmittance due to the vertical electric field may be minimized and high-speed response may be implemented.

Hereinafter, a method of manufacturing a liquid crystal display according to another exemplary embodiment of the present invention is described with reference toFIG. 14andFIG. 15.FIG. 14is a cross-sectional view showing an electric field direction under electric field exposure in the method of manufacturing a liquid crystal display according to another exemplary embodiment of the present invention.FIG. 15is a cross-sectional view showing an electric field direction when activating a liquid crystal display manufactured by the exemplary embodiment shown inFIG. 14.

Referring toFIG. 14andFIG. 15, a fine slit electrode300is formed in the liquid crystal display with a pixel electrode191and an insulating layer280therebetween, unlike the liquid crystal display according to the exemplary embodiment shown inFIG. 8andFIG. 13.

Referring toFIG. 14, voltage is applied to a common electrode270and the fine slit electrode300for electric field exposure. A first voltage V1is applied to the common electrode270; a second voltage V2is applied to the fine slit electrode300, and a third voltage V3is applied to the pixel electrode191. An electric field is established between the common electrode270and the fine slit electrode300when the first voltage V1and the second voltage V2are different.

In detail, a voltage is applied to the electrodes191,270, and300such that the first voltage V1, the second voltage V2and the third voltage V3satisfy the following condition (5).
|V2−V1|≧|V3−V1|  (5).

That is, a fringe field E is generated when the magnitude of the difference between the second voltage V2and the first voltage V1is greater than the magnitude of the difference between the third voltage V3and the first voltage V1.

Next, light is radiated (as indicated by arrows1) to the liquid crystal display according to the exemplary embodiment with the fringe field E ofFIG. 14generated. Accordingly, the liquid crystal molecule310may be pretilted.

Many characteristics of the method of manufacturing the liquid crystal display according to the exemplary embodiment shown inFIG. 8may be applied to the exemplary embodiment shown inFIG. 14.

Referring toFIG. 15, the liquid crystal display manufactured by the exemplary embodiment show inFIG. 14may operate, within any one of the following conditions (6), (7), and (8).
V1≠V3(fine slit electrode floated)  (6).
V2=V3≠V1  (7).
V1≠V2≠V3  (8).

In the exemplary embodiment, the liquid crystal molecules may move (e.g., rotate) in their positions between the common electrode270and the pixel electrode191by exertion of the vertical electric field E with any one of the conditions (6), (7), and (8) being satisfied. That is, as shown inFIG. 15, the vertical electric field E is generated between the common electrode270and the pixel electrode191.

Therefore, the liquid crystal molecules may move due to the vertical electric field when the liquid crystal display operates so that reduction of transmittance due to the vertical electric field may be decreased, and the display may exhibit a high-speed response.

FIG. 16is a graph showing transmittance as a function of voltage applied to the liquid crystal layer in a liquid crystal display according to an exemplary embodiment of the present invention.FIG. 17is a graph showing transmittance as a function of time in a liquid crystal display according to an exemplary embodiment of the present invention. The voltage applied to the liquid crystal layer is given by the difference between the voltage applied to the common electrode and data applying voltage inFIG. 16.FIG. 16andFIG. 17also include the transmittance values for a comparative example.

The comparative example ofFIG. 16andFIG. 17has a liquid crystal display with a fine slit electrode and a corresponding common electrode, an electric field exposure with voltage applied to the fine slit electrode and the common electrode, and a voltage applied to the fine slit electrode and the common electrode while in operation. However, an exemplary embodiment of the present invention uses the fine slit electrode only during the electric field exposure for pretilting the liquid crystal molecules and uses the common electrode and the pixel electrode, which have no pattern, in operation such that the liquid crystal molecules are moved only by the vertical electric field.

Therefore, as shown inFIG. 16, there is no reduction in light transmittance due to the vertical electric field in the exemplary embodiment as compared with the comparative example, i.e., light transmission is enhanced in the exemplary embodiment as compared to the comparative example at increasing field strengths.

Further, in the comparative example, the sides of the fine branches distort the electric field so that vertical components of the electric field which are perpendicular to the sides of the fine branches are generated, and the inclination direction of the liquid crystal molecules is determined by the vertical components of the electric field. Therefore, the liquid crystal molecules initially tend to incline perpendicular to the sides of the fine branches (Step 1). However, since the horizontal components of the electric field due to the adjacent fine branches is opposite and the gap between the fine branches is small, the liquid crystal molecules that tend to align in opposite directions begin to incline parallel with the longitudinal direction of the fine branches (Step 2). That is, the liquid crystal molecules move in accordance with Step 1 and Step 2 in the comparative example, whereas the liquid crystal molecules are moved only by the vertical electric field, without being influenced by the fringe field according to the fine slit electrode in an exemplary embodiment of the present invention.

Therefore, as shown inFIG. 17, in some cases, the exemplary embodiment has a faster response time than the comparative example so that a display made according to the exemplary embodiment may have a faster response time.

FIG. 18is an optical microscopy picture showing a pixel region in a liquid crystal display of the related art.FIG. 19is an optical microscopy picture showing a pixel region in a liquid crystal display according to an exemplary embodiment of the present invention. In detail,FIG. 18shows the pixel region of the comparative example described with reference toFIG. 16andFIG. 17, andFIG. 19shows the pixel region of the exemplary embodiment described with reference toFIG. 16andFIG. 17.

Referring toFIG. 18, it can be seen that dark portions were generated in areas corresponding to non-electrodes between the fine branches due to the horizontal component of the electric field's fringe field in the comparative example. In contrast, referring toFIG. 19, there is no reduction in transmittance due to the horizontal component of the electric field because the liquid crystal molecules are moved only by the vertical electric field such that most of the dark portions do not occur in the non-electrodes areas between the fine branches in the exemplary embodiment.

FIG. 20,FIG. 21,FIG. 22,FIG. 23,FIG. 24, andFIG. 25are cross-sectional views showing liquid crystal displays according to other exemplary embodiments of the present invention. In detail,FIG. 20,FIG. 21,FIG. 22,FIG. 23,FIG. 24, andFIG. 25show a method of forming a short point around fine slit electrodes for electric field exposure and a common electrode for operation.

Referring toFIG. 20, a common electrode270, an insulating layer280, and a transparent conductive layer300pare formed on a substrate210. The common electrode270may be made of ITO.

A photoresist PR is disposed on the transparent conductive layer300p.

Referring toFIG. 21,FIG. 22, andFIG. 23, a slit mask (Mask) is disposed on the photoresist PR and light is radiated to the structure. Thereafter, the region of the photoresist PR that has been exposed to the irradiated light may be removed, and the exposed portion of the transparent conductive layer300pmay be removed by, for example, wet etching.

Referring toFIG. 24, a portion of the insulating layer280is removed by, for example, dry etching, and the photoresist PR may be maintained during the dry etch.

Finally, referring toFIG. 25, the photoresist PR is removed. In this process, the fine slit electrode300is formed, and the short point SP is formed. The short points SP are the portion where a pattern for applying voltage to the common electrode270or the fine slit electrode300may be formed.

Manufacturing cost and time for each step may be reduced by using one mask.