KR20110123543A - Liquid crystal display - Google Patents

Abstract

PURPOSE: A liquid crystal display apparatus is provided to offer high quality liquid crystal display by reducing residual images which are generated by the movement of a foreign matter. CONSTITUTION: A first insulation board(110) includes plural pixel areas(PA). The pixel areas include plural rows and plural lines. Pixel electrodes(PE) is included in the pixel areas. A first alignment layer(AL2) covers the pixel electrodes and is extended according to the lines. A first alignment area faces to a first direction. A second alignment area faces to a second direction in which is inverse way from the first direction.

Description

[0001] LIQUID CRYSTAL DISPLAY [0002]

The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device with improved display quality.

The liquid crystal display is classified into a twisted nematic liquid crystal display, a horizontal electric field liquid crystal display, or a vertical alignment liquid crystal display according to the characteristics of the liquid crystal layer.

The vertically aligned liquid crystal display device is aligned in a predetermined direction without an electric field applied thereto, and the long axis of the liquid crystal molecules is arranged perpendicular to the substrate surface. Thus, the viewing angle is wide and the contrast ratio is large.

As a method for aligning the liquid crystal molecules in a predetermined direction without an electric field applied, there is a rubbing method or a light alignment method.

It is an object of the present invention to provide a high quality liquid crystal display device which secures a wide viewing angle and reduces line afterimages.

According to an aspect of the present invention, a liquid crystal display device includes a first insulating substrate, pixel electrodes provided on the insulating substrate, a first alignment layer covering the pixel electrodes, a second insulating substrate facing the first substrate, A common electrode provided on the second insulating substrate, a second alignment layer covering the common electrode, and a liquid crystal layer provided between the first alignment layer and the second alignment layer.

The first insulating substrate has a plurality of pixel regions including a plurality of columns and a plurality of rows, and the pixel electrodes are provided in the pixel regions.

The first alignment layer includes a plurality of first alignment regions extending along the column and oriented in a first direction, and a plurality of first alignment regions alternately provided in the first alignment regions and oriented in a second direction opposite to the first direction. And a second alignment region of.

The second alignment layer includes a plurality of third alignment regions extending along the row and oriented in a third direction perpendicular to the first direction, and alternately provided to the third alignment regions and opposite to the third direction. And a plurality of fourth alignment regions oriented in the fourth direction.

Each of the first and second alignment regions overlaps a portion of two adjacent pixel regions disposed in the same row on a plane, and each of the third and fourth alignment regions includes two adjacent pixels disposed in the same column on a plane. Overlap some of the areas.

The liquid crystal layer includes a first domain in which the first and third alignment regions overlap, a second domain in which the first and fourth alignment regions overlap, and a third domain in which the second and third alignment regions overlap. And a fourth domain in which the second and fourth alignment regions overlap. The liquid crystal layer is oriented in different directions in each of the domains.

Each pixel area includes the first to fourth domains, and an arrangement order of the first to fourth domains in one pixel area among the pixel areas is the first in the pixel areas adjacent to the one pixel area. And the arrangement order of the fourth domains.

A pixel area in which the orientation directions of the first to fourth domains circulate in a clockwise or counterclockwise direction in each of the pixel areas is referred to as a cyclic pixel area, and the orientation direction of the first and fourth domains or the second And when the pixel regions in which the alignment directions of the third domains face each other or face in opposite directions are referred to as convergent pixel regions, the cyclic pixel regions and the convergent pixel regions alternate along the rows and the columns. It is provided with.

The liquid crystal mode of the liquid crystal display may be a vertical alignment liquid crystal mode or a twisted nematic liquid crystal mode. In the vertical alignment liquid crystal mode, the vertical alignment liquid crystal mode has a pretilt angle of 88 ° to 89 °.

According to an embodiment of the present invention, there is provided a high-quality liquid crystal display device having reduced line afterimages generated by movement of ionic impurities.

1 is an exploded perspective view of a liquid crystal display according to a first exemplary embodiment of the present invention.
FIG. 2 is an enlarged plan view illustrating a part of the liquid crystal display shown in FIG. 1.
3 is a cross-sectional view taken along line II ′ of FIG. 2.
4A and 4B are perspective views illustrating a light alignment method of varying the alignment direction between adjacent regions using a mask.
5A is a plan view illustrating an alignment direction of the first substrate in the liquid crystal display according to the first exemplary embodiment of the present invention.
5B is a plan view illustrating an alignment direction of the second substrate in the liquid crystal display according to the first exemplary embodiment of the present invention.
5C is a cross-sectional view illustrating the alignment of the liquid crystal layer when the first substrate of FIG. 5A and the second substrate of FIG. 5B are combined.
FIG. 6 is a plan view illustrating a liquid crystal display in which the pixel areas of FIG. 5C are repeated in the same manner. FIG.
7 is an enlarged plan view illustrating a part of a liquid crystal display according to a second exemplary embodiment of the present invention.
8 is an enlarged plan view illustrating a portion of a liquid crystal display according to a second exemplary embodiment of the present invention.

As the inventive concept allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to the specific disclosed form, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

Like reference numerals are used for like elements in describing each drawing. In the accompanying drawings, the dimensions of the structures are shown in an enlarged scale than actual for clarity of the invention. The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component. Singular expressions include plural expressions unless the context clearly indicates otherwise.

In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, action, component, part, or combination thereof described on the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, parts, or combinations thereof. In addition, when a part such as a layer, film, region, plate, etc. is said to be "on" another part, this includes not only when the other part is "right on" but also another part in the middle. Conversely, when a part such as a layer, film, region, plate, etc. is "below" another part, this includes not only the other part "below" but also another part in the middle.

1 is an exploded perspective view of a liquid crystal display according to a first exemplary embodiment of the present invention. FIG. 2 is an enlarged plan view illustrating a part of the liquid crystal display shown in FIG. 1. 3 is a cross-sectional view taken along line II ′ of FIG. 2.

1 to 3, the liquid crystal display device 10 according to the first exemplary embodiment of the present invention may include a first substrate 100, a second substrate 200, and the first substrate 100 and the first substrate. The liquid crystal layer 300 is interposed between the two substrates 200.

The first substrate 100 includes a first insulating substrate 110, gate lines GL, data lines DL, thin film transistors TFT, pixel electrodes PE, and a first alignment layer AL1. ).

The first insulating substrate 110 has a plurality of pixel areas PA. In FIGS. 2 and 3, only one pixel area PA is shown for convenience of description, and in reality, the pixel area PA is arranged in a matrix form having a plurality of columns and a plurality of rows.

Since the pixel areas PA have the same structure, only one pixel area PA will be described as an example for convenience of description. Here, the pixel area PA is illustrated as a rectangular shape extending in one direction, but is not limited thereto. The pixel area PA may have various shapes such as a V shape and a Z shape.

The pixel area PA includes a gate line GL, a data line DL, a thin film transistor TFT, and a pixel electrode PE.

The gate line GL extends in one direction on the first insulating substrate 110.

The data line DL intersects and is insulated from the gate line GL on the first insulating substrate 110.

The thin film transistor TFT is disposed adjacent to an intersection of the gate line GL and the data line DL. The thin film transistor TFT may include a gate electrode GE branched from the gate line GL, a source electrode SE branched from the data line DL, and a drain electrode DE spaced apart from the source electrode SE. ).

The pixel electrode PE is connected to the drain electrode DE.

3, the gate line GL and the gate electrode GE are provided in the pixel area PA on the first insulating substrate 110.

The semiconductor pattern SM is provided on the gate line GL with the first insulating layer 111 interposed therebetween. The data line DL, the source electrode SE, and the drain electrode DE are provided on the first insulating substrate 110 on which the semiconductor pattern SM and the like are formed. The semiconductor pattern SM forms a conductive channel between the source electrode SE and the drain electrode DE.

The second insulating layer 113 is provided on the first insulating layer 111 on which the source electrode SE, the drain electrode DE, and the like are formed. The passivation layer 115 is provided on the second insulating layer. The pixel electrode PE is disposed on the passivation layer 115 and electrically connected to the drain electrode DE through a contact hole CH formed through the second insulating layer 113 and the passivation layer 115. Is connected.

A first alignment layer AL1 is disposed on the pixel electrode PE to cover the pixel electrode PE.

The second substrate 200 is provided to face the first substrate 100. The second substrate 200 includes a second insulating substrate 210, color filters CF, a black matrix BM, a common electrode CE, and a second alignment layer AL2.

The color filters CF and the black matrix BM are provided on the second insulating substrate 210. The common electrode CE and the second alignment layer AL2 are sequentially provided on the color filters CF and the black matrix BM.

The color filters CF are provided to correspond to the pixel areas PA. Each color filter CF implements any one color of red, green, or blue. The black matrix BM is formed between the color filters CF and blocks the light passing through the liquid crystal layer 300 between the color filters CF. The common electrode CE is provided on the color filters CF and the black matrix BM. The second alignment layer AL2 is formed to cover the common electrode CE.

The liquid crystal layer 300 is provided between the first alignment layer AL1 and the second alignment layer AL2. The liquid crystal layer 300 is a vertical alignment liquid crystal mode. However, the present invention is not limited thereto and may be a twisted nematic liquid crystal mode.

When the thin film transistor TFT is turned on in response to a driving signal provided through the gate line GL, an image signal provided through the data line DL is transferred through the turned on thin film transistor TFT. It is provided to the pixel electrode PE. Accordingly, an electric field is formed between the pixel electrode PE and the common electrode CE to which the common voltage is applied. The liquid crystal molecules of the liquid crystal layer 300 are driven according to the electric field, and as a result, an image is displayed according to the amount of light passing through the liquid crystal layer 300.

The pretilt angles of the liquid crystal molecules included in the liquid crystal layer 300 vary according to the characteristics of the first alignment layer AL1 and the second alignment layer AL2. When the liquid crystal layer 300 is a vertical alignment liquid crystal mode, the vertical alignment liquid crystal mode has a pretilt angle of 88 ° to 89 °.

The alignment direction of the first alignment layer AL1 and the second alignment layer AL2 is determined by a photo alignment method. As said photo-alignment method, the method of irradiating the ultraviolet-ray from which a polarization direction differs, the method of irradiating light diagonally with respect to the surface of an oriented film, etc. are mentioned.

First, after briefly explaining the method of aligning the alignment film by the photo alignment method, the alignment direction of the first alignment film and the second alignment film according to the embodiment of the present invention will be described.

4A and 4B are perspective views schematically illustrating a light alignment method in which an orientation direction between adjacent areas is different using a mask.

4A and 4B, an insulating substrate SUB having an alignment layer AL made of a photosensitive polymer is prepared. The insulating substrate SUB has a first region A1 and a second region A2 to be aligned in different alignment directions.

As the photosensitive polymer, a polymer obtained by blending a cinnamate-based photosensitive polymer and a polyimide-based polymer may be used as an example. The cinnamate-based photosensitive polymers include polyvinyl cinnamate (PVCN) or polysiloxane cinnamate (PSCN), cellulose cinnamate (CelCN), and the like. When the photosensitive polymers are irradiated with light such as an ultraviolet ray, a dimerization reaction, a cis-trans isomerization reaction, or a light-decomposition reaction is performed. Happens. Thereby, the said photosensitive polymer is provided with orientation according to the direction to which light was irradiated or the polarization direction by the above reaction.

First, as shown in FIG. 4A, a first mask MASK1 is disposed on the insulating substrate SUB. The first mask MASK1 includes an opening R1 through which light passes and a shielding part R2 through which light is shielded. The opening part R1 and the shielding part R2 are respectively located corresponding to the first area A1 and the second area A2.

Next, light is irradiated through the first mask MASK1. Accordingly, light is irradiated through the opening R1 in the first region A1, and light is shielded by the shield R2 in the second region A2. The light may be polarized light or tilted light. For example, it may be polarized ultraviolet light.

Thus, by irradiating light to the surface of the alignment film AL, the alignment film AL has directivity in a predetermined direction.

Next, as shown in FIG. 4B, a second mask MASK2 is disposed on the insulating substrate SUB. The second mask MASK2 also includes an opening R1 through which light passes and a shielding part R2 through which light is shielded. The opening part R1 and the shielding part R2 are respectively positioned to correspond to the second area A2 and the first area A1.

Next, the light irradiated to the first mask MASK1 through the second mask MASK2 is irradiated with light having a different polarization direction or different inclination. Accordingly, the second area A2 is irradiated with light through the opening R1, and the first area A1 is shielded by the shielding part R2.

As a result, the alignment film of the second region A2 has a direction in another direction different from the alignment film of the first region.

Hereinafter, the liquid crystal alignment of the liquid crystal display according to the exemplary embodiment of the present invention will be described with reference to FIGS. 5A to 5C.

FIG. 5A is a plan view illustrating an alignment direction of the first substrate 100 in the liquid crystal display according to the first exemplary embodiment of the present invention, and is illustrated using a photo alignment method for the first alignment layer AL1. FIG. 11 is a diagram illustrating a state in which liquid crystal molecules are aligned in an arrow direction.

FIG. 5B is a plan view illustrating an alignment direction of the second substrate 200 in the liquid crystal display according to the first exemplary embodiment of the present invention, and is shown using a photo alignment method for the second alignment layer AL2. FIG. 11 is a diagram illustrating a state in which liquid crystal molecules are aligned in an arrow direction.

FIG. 5C is a cross-sectional view illustrating an orientation of the liquid crystal layer 300 when the first substrate 100 of FIG. 5A and the second substrate 200 of FIG. 5B are combined with each other. 2 shows an orientation direction in which the orientation directions of the substrates 200 are combined. The alignment direction of FIG. 5C corresponds to the vector sum of the alignment direction of the first substrate 100 and the alignment direction of the second substrate 200.

5A to 5C, four pixel areas P11 and P12 forming a 2 × 2 matrix form among the plurality of pixel areas PA to display the alignment direction of each pixel area PA and the pixel area PA adjacent thereto. , P21 and P22 and corresponding regions are shown. Here, the boundary by the solid line represents the boundary of each pixel area PA, and the boundary by the dotted line represents the boundary of the alignment area.

In addition, in the description of the present embodiment, the four pixel areas PA are formed in the form of a 2 × 2 matrix. However, the four pixel areas PA may be referred to as four sub pixel areas instead of the name of the four pixel areas PA. In this case, four sub-pixel regions form a 2 × 2 matrix, and the four sub-pixel regions form one pixel region. Here, even when each pixel region is referred to as a sub-pixel region, the name is used differently, but the arrangement of each pixel region is the same as that of FIGS. 5A to 5C.

In addition, in FIG. 5A to FIG. 5C, each pixel area PA is disclosed as a rectangular shape that is narrow in the row direction and long in the column direction, but is not limited thereto. Each pixel area PA may be provided in a rectangular shape that is narrow in the column direction and long in the row direction.

Referring to FIG. 5A, pixel regions in a 2 × 2 matrix form, that is, a first pixel region P11 in a first row and a first column, and a second pixel region P12 in a first row and a second column, may be formed in the first substrate 100. The third pixel region P21 in the first row of the second row and the fourth pixel region P22 in the second column of the second row are provided.

The first alignment layer AL1 may include a first alignment region AN1 and a first alignment region AN1 to align the liquid crystal layer 300 in directions opposite to each other on the first to fourth pixel regions P11, P12, P21, and P22. It has 2 orientation area | region AN2. The first alignment area AN1 is an area to align the liquid crystal layer 300 in the first direction D1, and the second alignment area AN2 is a second direction opposite to the first direction D1. The liquid crystal layer 300 is oriented in the direction D2. The first direction D1 and the second direction D2 correspond to extension directions of the column. Each of D3 and D4 not described is a third direction and a fourth direction corresponding to the extending direction of the row.

The second alignment area AN2 is provided between the first alignment area AN1.

The second alignment area AN2 is disposed in the same row and overlaps a part of two adjacent pixel areas. That is, in the first pixel area P11 and the second pixel area P12 adjacent to each other in the first row, the second alignment area AN2 is a portion of the first pixel area P11 and the first pixel area. A part of the two pixel area P12 is covered. In addition, in the third pixel area P21 and the fourth pixel area P22 adjacent to each other in the second row, the second alignment area AN2 may be a part of the third pixel area P21 and the first pixel area. A portion of the four pixel region P22 is covered.

In the present exemplary embodiment, an area in which the second alignment area AN2 overlaps each of two adjacent pixel areas provided in the same row is the same but is not limited thereto. For example, an area of the portion where the second alignment region AN2 and the first pixel region P11 overlap is larger than an area where the second alignment region AN2 and the second pixel region P12 overlap. It can be large or small. Accordingly, the area of the alignment region in each pixel region can be adjusted in various ways.

For convenience of description, FIG. 5B illustrates a second substrate 200 having pixel regions in the form of a 2 × 2 matrix corresponding to each pixel region of the first substrate 100. Referring to FIG. 5B, the second substrate 200 may include a first pixel area P11 in a first row and a first column, a second pixel area P12 in a first row and a second column, and a third in the second row and the first column. A pixel area P21 and a fourth pixel area P22 in a second row and a second column.

The second alignment layer AL2 may be formed on the first to fourth pixel areas P11, P12, P21, and P22 so that the liquid crystal layer 300 is aligned in directions opposite to each other. It has a 4th orientation area | region AN4. The third alignment area AN3 is an area for allowing the liquid crystal layer 300 to be aligned in a third direction D3, and the fourth alignment area AN4 is a fourth direction opposite to the third direction D3. The liquid crystal layer 300 is oriented in the direction D4. The third direction D3 and the fourth direction D4 correspond to the extending direction of the row, and may be perpendicular to the first direction D1 and the second direction D2.

Here, the fourth alignment region AN4 is provided between the third alignment region AN3.

The fourth alignment area AN4 is provided in the same column and overlaps a part of two adjacent pixel areas. That is, in the first pixel area P11 and the third pixel area P21 adjacent to each other in the first column, the fourth alignment area AN4 is part of the first pixel area P11 and the third. A portion of the pixel region P21 is covered. Further, in the second pixel area P12 and the fourth pixel area P22 adjacent to each other in the second column, the fourth alignment area AN4 is a part of the second pixel area P12 and the fourth pixel. A part of the pixel region P22 is covered.

In the present exemplary embodiment, the case where the fourth alignment region AN4 overlaps with each other adjacent two pixel regions provided in the same column is the same, but is not limited thereto. For example, an area of the portion where the fourth alignment region AN4 and the first pixel region P11 overlap is larger than an area where the fourth alignment region AN4 and the fourth pixel region P22 overlap. It can be large or small.

Referring to FIG. 5C, the liquid crystal layer 300 has an alignment direction of the first substrate 100 and the second substrate 200 according to the combination of the first substrate 100 and the second substrate 200. It has an orientation direction corresponding to the vector sum of the orientation directions of. Accordingly, the liquid crystal layer 300 is divided into a plurality of domains having an alignment direction corresponding to the vector sum of each alignment direction.

The plurality of domains may include a first domain DM1 in which the first alignment region AN1 and the third alignment region AN3 overlap, the first alignment region AN1, and the fourth alignment region AN4. The overlapping second domain DM2, the third domain DM3 overlapping the second alignment region AN2 and the third alignment region AN3, and the second alignment region AN2 and the fourth The alignment region AN4 includes an overlapping fourth domain DM4.

Here, the first to fourth domains DM1, DM2, DM3, and DM4 have different orientation directions. That is, the liquid crystal layer 300 has a different director in each domain.

The liquid crystal layer 300 is aligned in a fifth direction D5 defined as a vector sum of the first and third directions D1 and D3 in the first domain DM1. The liquid crystal layer 300 is aligned in a sixth direction D6 defined as a vector sum of the first and fourth directions D1 and D4 in the second domain DM2. The liquid crystal layer 300 is oriented in the seventh direction D7 defined as the vector sum of the second and third directions D2 and D3 in the third domain DM3. The liquid crystal layer 300 is oriented in an eighth direction D8 defined as a vector sum of the second and fourth directions D2 and D4 in the fourth domain DM4. The fifth to eighth directions D5, D6, D7, and D8 are respectively different directions.

Each of the pixel areas P11, P12, P21, and P22 includes the first to fourth domains DM1, DM2, DM3, and DM4. The arrangement order of the first to fourth domains DM1, DM2, DM3 and DM4 in each of the pixel regions P11, P12, P21, and P22 is as follows. In the first pixel area P11, the first to fourth domains DM1, DM2, DM3, and DM4 are clockwise in the first domain DM1, the third domain DM3, and the fourth domain. (DM4) and the second domain DM2 in this order. In the second pixel area P12, the first to fourth domains DM1, DM2, DM3, and DM4 are clockwise in the third domain DM3, the first domain DM1, and the second domain. (DM2) and the fourth domain DM4 in this order. In the third pixel area P21, the first to fourth domains DM1, DM2, DM3, and DM4 are clockwise in the second domain DM2, the fourth domain DM4, and the third domain. (DM3) and the first domain DM1 in this order. In the fourth pixel area P22, the first to fourth domains DM1, DM2, DM3, and DM4 are clockwise in the fourth domain DM4, the second domain DM2, and the third domain. (DM3) and the first domain DM1 in this order.

As described above, the arrangement order of the first to fourth domains DM1, DM2, DM3, and DM4 in the first to fourth pixel areas P11, P12, P21, and P22 is different.

Here, the orientation directions of the entire domains of the first pixel area P11 and the fourth pixel area P22 among the first to fourth pixel areas P11, P12, P21, and P22 may be described. The orientation direction cycles clockwise or counterclockwise. Here, a pixel area that is circulated as a whole, such as the first pixel area P11 or the fourth pixel area P22, is referred to as a circular pixel area.

Among the first to fourth pixel areas P11, P12, P21, and P22, the second pixel area P12 and the third pixel area P21 are the first pixel area P11 and the fourth. Unlike the pixel region P22, the orientation direction of the entire domain does not cycle. Rather, in one pixel, the alignment direction of the first domain DM1 and the alignment direction of the fourth domain DM4 face each other and converge inwardly or face in the opposite direction and diverge outward. The orientation direction of the second domain DM2 and the orientation direction of the third domain DM3 are also facing or diverging outward. Accordingly, although the alignment directions of the second pixel area P12 and the third pixel area P21 are bent as a whole, they are directed toward the first direction D1 or the second direction D2. Here, a pixel region in which the direction of the entire domain faces or faces outwardly, such as the second pixel region P12 or the third pixel region P21, will be referred to as a convergent diverging pixel region.

Referring to FIG. 5C, a converging divergent pixel region is disposed in pixel regions adjacent to the cyclic pixel region, and a circulating pixel region is disposed in pixel regions adjacent to the convergent pixel region.

FIG. 6 is a plan view illustrating a liquid crystal display in which the pixel areas of FIG. 5C are repeated in the same manner, and illustrates a case in which the pixel areas have a 3 × 5 matrix form. FIG.

Referring to FIG. 6, the first alignment region AN1 and the second alignment region AN2 are provided to extend along a column. The first alignment region AN1 and the second alignment region AN2 are alternately disposed. The first alignment area AN1 and the second alignment area AN2 overlap some of two adjacent pixel areas in the same row.

 The third alignment area AN3 and the fourth alignment area AN4 are provided to extend along a row, respectively. The third alignment area AN3 and the fourth alignment area AN4 are alternately disposed. The third alignment area AN3 and the fourth alignment area AN4 overlap some of two adjacent pixel areas in the same column.

Accordingly, the domains belonging to different pixel areas among the first to fourth domains DM1, DM2, DM3, and DM4 and adjacent to each other are oriented in the same direction.

In FIG. 6, each of the pixel areas includes the first to fourth domains DM1, DM2, DM3, and DM4, and the first to fourth domains in one pixel area of the pixel areas. The arrangement order of the DM1, DM2, DM3, and DM4 is different from the arrangement order of the first to fourth domains DM1, DM2, DM3, and DM4 in the pixel areas adjacent to the one pixel area.

The circular pixel area and the convergent pixel area are alternately arranged along rows and columns. Accordingly, when any one pixel area is circular, all four pixel areas adjacent in the row and column directions correspond to convergent divergence pixel areas. In contrast, when one pixel area is a convergent diverging pixel area, all four pixel areas adjacent in the row and column directions correspond to the circular pixel area.

The liquid crystal display having the above structure has a wide side visibility because a plurality of domains having different alignment directions are formed in one pixel area. In addition, in the liquid crystal display device having the above-described structure, a line afterimage, which is a defect appearing in an image visually recognized by a user, is reduced.

The reason why the line afterimage decreases is as follows.

Ionic impurities exist in the liquid crystal layer of a general liquid crystal display. The ionic impurities may be present at the time of manufacture or may be generated later from an electric field repeatedly applied by electrodes provided at both ends of the liquid crystal layer. The ionic impurities that occur later are frequently found in the pixel region where the same gray level is continuously displayed for a long time.

When a voltage is applied to the electrodes of each pixel region, the ionic impurities move toward the electrodes by electrical attraction. Accordingly, leakage current is generated due to the movement of the ionic impurities. Liquid crystal molecules at the point where the leakage current occurs are misaligned by the leakage current. As a result, a defect occurs in which the luminance at the point where the leakage current occurs is reduced or increased than the luminance at another point.

The mobility of the ionic impurities is affected by the electric field, the shape of the liquid crystal molecules, and the orientation direction of the liquid crystal molecules. The ionic impurities easily move near the edge of the electric field because the influence of the electric field is minimized and can move to electrical attraction without the influence of the electric field.

In addition, the ionic impurities move relatively easily along the long axis direction rather than the short axis direction of the liquid crystal molecules due to the shape of the liquid crystal molecules. In addition, when the liquid crystal molecules are aligned in the same direction in regions adjacent to each other, the ionic impurities are easily moved from one region to the adjacent region.

However, according to the exemplary embodiment of the present invention, the liquid crystal molecules of the liquid crystal layer 300 are aligned in different directions for each domain in one pixel area. In addition, one pixel region and domains of other pixel regions adjacent to the one pixel region may have different arrangement orders so that the alignment directions of the liquid crystal molecules are not coincident or symmetrical. Accordingly, in one embodiment of the present invention, the mobility of the ionic impurities is reduced, and the afterimage defect due to the ionic impurities is also reduced.

Table 1 is a table of experimental results of the line residual image of the liquid crystal display device and the liquid crystal display device according to an embodiment of the present invention is not applied to the technology of the present invention.

In the liquid crystal display device to which the technique of the present invention is not applied, each pixel region is prepared to have a circular pixel region. Accordingly, in the liquid crystal display device to which the technology of the present invention is not applied, adjacent pixel areas all have the same circular pixel area. The liquid crystal display according to the exemplary embodiment of the present invention is prepared such that the cyclic pixel region and the convergent pixel region are alternately arranged as in the first exemplary embodiment.

In Table 1, afterimages are applied to the liquid crystal display for a predetermined time while all the conditions are kept the same except for the alignment direction, the afterimages are displayed when the voltage is applied to the entire grayscale. It means the gradation that starts to appear. The gray scale has 0G to 255G, and G represents a gray level. Here, 0G is black, 255G is white, and the gradation level in between is gray. The following table corresponds to a liquid crystal display having no afterimage as the gray level at which the afterimage is started to appear has a low gray level.

Alignment Film (Residual Pattern Application Time)  Gray level at which line afterimages start to appear in a liquid crystal display device to which the technique of the present invention is not applied. In the liquid crystal display according to the present invention, the gradation at which line afterimages start to be seen Alignment film 1 (504 hours) 180G 160G Alignment film 2 (24 hours) 180G 92G Alignment layer 3 (96 hours) 240G 220G

Referring to Table 1, it can be seen that the liquid crystal display according to the exemplary embodiment of the present invention has an effect of reducing an afterimage compared to the liquid crystal display device to which the technology of the present invention is not applied.

Table 2 is a table showing the results of experiments on the occurrence of line afterimages of the liquid crystal display device according to the embodiment of the present invention and the liquid crystal display device to which the technology of the present invention is not applied. The experimental conditions of Table 2 also apply the afterimage pattern to the liquid crystal display device for a predetermined time while maintaining all the same conditions except for the alignment direction as in the experimental conditions of Table 1, and then the voltage Authorized.

Alignment film  Time after which line persistence occurs in a liquid crystal display device to which the technique of the present invention is not applied Time after which line persistence occurs in the liquid crystal display according to the present invention Alignment film 1 268 hours 336 hours

Referring to Table 2 above, it can be seen that the liquid crystal display according to the exemplary embodiment of the present invention is significantly delayed in the time that a line afterimage occurs when compared to the liquid crystal display device to which the technology of the present invention is not applied.

Hereinafter, a liquid crystal display according to a second embodiment of the present invention will be described. In the second embodiment of the present invention, description will be made mainly on differences from the first embodiment in order to avoid redundant description. Parts not specifically described in the following embodiments are in accordance with the first embodiment. Like numbers refer to like elements and like numbers refer to like elements.

7 is an enlarged plan view illustrating a part of the liquid crystal display 10 according to the second exemplary embodiment of the present invention. Here, although the plurality of pixel areas PA exist in the liquid crystal display device 10, only one pixel area PA is described as an example for convenience of description. In the actual liquid crystal display 10, pixel regions having the same structure as the pixel region PA are arranged in a matrix form having a plurality of columns and a plurality of rows.

Referring to FIG. 7, a pixel electrode is formed by separating a first sub pixel electrode PE1 and a second sub pixel electrode PE2 in each pixel area PA of the present exemplary embodiment, and the first and second sub pixel electrodes. The first embodiment except for having a first thin film transistor TFT1 and a second thin film transistor TFT2, a first data line DL1, and a second data line DL2 respectively corresponding to the fields PE1 and PE2. It has a structure similar to the example.

Each pixel area includes a gate line GL, a first data line DL1, a second data line DL2, a first thin film transistor TFT1, a second thin film transistor TFT2, and a first sub pixel electrode PE1. ) And a second sub pixel electrode PE2.

The gate line GL extends in the first direction D1. The first data line DL1 and the second data line DL2 cross the gate line GL and extend in other directions.

The first thin film transistor TFT1 is provided at a position adjacent to an intersection of the gate line GL and the first data line DL1. The first thin film transistor TFT1 includes a first gate electrode GE1 branched from the gate line GL, a first source electrode SE1 branched from the first data line DL1, and the first source. The first drain electrode DE1 is provided to be spaced apart from the electrode SE1.

The second thin film transistor TFT2 is provided at a position adjacent to an intersection of the gate line GL and the second data line DL2. The second thin film transistor TFT2 includes a second gate electrode GE2 branched from the gate line GL, a second source electrode SE2 branched from the second data line DL2, and the second source. The second drain electrode DE2 is provided to be spaced apart from the electrode SE2.

The first sub pixel electrode PE1 and the second sub pixel electrode PE2 are disposed between the first data line DL1 and the second data line DL2.

The first sub pixel electrode PE1 is connected to the first drain electrode DE1 through a contact hole, and the second sub pixel electrode PE2 is connected to the second drain electrode DE2 through a contact hole. . The first sub pixel electrode PE1 and the second sub pixel electrode PE2 receive different voltages with respect to the same gray level through the first thin film transistor TFT1 and the second thin film transistor TFT2, respectively. .

FIG. 8 is a plan view illustrating a liquid crystal display in which pixel regions are identically repeated in the same manner as in FIG. 6, and illustrates the case where the pixel regions are arranged in a 3 × 5 matrix form.

Referring to FIG. 8, the first alignment region AN1 and the second alignment region AN2 are provided to extend along a column. The first alignment region AN1 and the second alignment region AN2 are alternately disposed. The first alignment area AN1 and the second alignment area AN2 overlap with a portion of two adjacent sub-pixel areas provided in the same row. The third alignment area AN3 and the fourth alignment area AN4 are provided to extend along a row, respectively. The third alignment area AN3 and the fourth alignment area AN4 are alternately disposed, and overlap with some of two adjacent sub-pixel areas. At this time, in the third alignment area AN3, one of the sub-pixel areas adjacent to each other in the column direction overlaps the second sub-pixel electrode PE2 and the first of the other one of the adjacent pixel areas. It overlaps with the sub pixel electrode PE1. The fourth alignment area AN4 also overlaps the second sub pixel electrode PE2 in one of the sub-pixel areas adjacent to each other, and the second sub pixel electrode PE2 in the other one of the pixel areas adjacent to each other. Overlap.

In addition, similar to the first embodiment, each of the sub-pixel regions includes the first to fourth domains DM1, DM2, DM3, and DM4, and the first sub-pixel region includes one of the sub-pixel regions. The arrangement order of the fourth to fourth domains DM1, DM2, DM3, and DM4 may be based on the arrangement of the first to fourth domains DM1, DM2, DM3, and DM4 in subpixel areas adjacent to the one subpixel area. It is all different from the order. The circular pixel area and the convergent pixel area are alternately arranged along rows and columns. Accordingly, when any one pixel area is circular, all four sub-pixel areas adjacent in the row and column directions correspond to convergent divergence pixel areas. In contrast, when any one sub-pixel region is a convergent diverging pixel region, all four sub-pixel regions adjacent in the row and column directions correspond to the cyclic pixel region.

In the liquid crystal display having the above structure, the alignment of the liquid crystal layer 300 may be differently controlled by the first sub pixel electrode PE1 and the second sub pixel electrode PE2 while displaying the same gray level, thereby improving side visibility. There is an advantage to this. In addition, since the first sub pixel electrode PE1 and the second sub pixel electrode PE2 correspond to different alignment regions in one pixel region, mobility of the ionic impurities in one pixel may be reduced. have. The ionic impurities easily move near an edge of an electric field, and the third and fourth alignment regions AN3 and AN4 are disposed between the first sub pixel electrode PE1 and the second sub pixel electrode PE2. This is because the alignment direction of the liquid crystal layer 300 is different from each other, so that ionic impurities cannot easily move.

In the present exemplary embodiment, the first sub pixel electrode PE1 and the second sub pixel electrode PE2 are arranged in a column direction, but the present invention is not limited thereto. That is, the subpixel electrodes of various numbers and shapes may be provided, and the arrangement of each subpixel electrode may also be arranged in various directions. For example, the first sub pixel electrode PE1 and the second sub pixel electrode PE2 may be arranged in a row direction. In addition, the first sub pixel electrode PE1 may be divided into two regions. In this case, the second sub pixel electrode PE2 may be disposed between the divided first sub pixel electrodes PE1.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood that various modifications and changes may be made thereto without departing from the scope of the present invention.

For example, each of the above embodiments of the present invention has been described only that the shape of the pixel area is a rectangular shape, for example, may have a pixel area of various shapes, and may also vary the shape or number of pixel electrodes. Of course.

Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

100: first substrate PA: pixel region
P11: first pixel region P12: second pixel region
P21: third pixel region P22: fourth pixel region
110: first insulating substrate GL: gate line
DL: data line TFT: thin film transistor
PE: pixel electrode AL1: first alignment layer
AN1: first alignment region AN2: second alignment region
200: second substrate CF: color filter
BM: Black Matrix CE: Common Electrode
AL2: 2nd alignment film AN3: 3rd alignment area
AN4: fourth alignment region 300: liquid crystal layer
D1 to D8: first to eighth directions
DM1-DM4: 1st-4th domain

Claims (20)

A first insulating substrate having a plurality of pixel regions composed of a plurality of columns and a plurality of rows;
Pixel electrodes provided in the pixel regions;
A plurality of first alignment regions covering the pixel electrodes and extending along the column and oriented in a first direction, and alternately provided in the first alignment regions and oriented in a second direction opposite to the first direction A first alignment layer including a plurality of second alignment regions;
A second insulating substrate facing the first insulating substrate;
A common electrode on the second insulating substrate and facing the pixel electrodes;
A plurality of third alignment regions covering the common electrode and extending along the row and oriented in a third direction perpendicular to the first direction, and alternately disposed in the third alignment regions and extending in the third direction; A second alignment layer including a plurality of fourth alignment regions oriented in a fourth direction opposite to the opposite direction; And
A liquid crystal layer interposed between the first alignment layer and the second alignment layer,
Each of the first and second alignment regions overlaps a portion of two adjacent pixel regions disposed in the same row on a plane, and each of the third and fourth alignment regions includes two adjacent pixels disposed in the same column on a plane. And a portion of the regions overlapping each other. The method of claim 1,
The liquid crystal layer includes a first domain in which the first and third alignment regions overlap, a second domain in which the first and fourth alignment regions overlap, and a third domain in which the second and third alignment regions overlap. And a fourth domain where the second and fourth alignment regions overlap each other, and are oriented in different directions in the respective domains. The method of claim 2,
And two domains which belong to different pixel areas among the first to fourth domains and are adjacent to each other, are oriented in the same direction. The method of claim 2,
The liquid crystal layer is oriented in a fifth direction defined as the vector sum of the first and third directions in the first domain, and a sixth direction defined as the vector sum of the first and fourth directions in the second domain. Oriented in a seventh direction defined as a vector sum of the second and third directions in the third domain, and an eighth direction defined as a vector sum of the second and fourth directions in the fourth domain It is oriented in the liquid crystal display device. The method of claim 4, wherein
Each pixel area includes the first to fourth domains, and an arrangement order of the first to fourth domains in one pixel area among the pixel areas is the first in the pixel areas adjacent to the one pixel area. And a sequence different from that of the fourth to fourth domains. The method of claim 5,
A pixel area in which the orientation directions of the first to fourth domains circulate in a clockwise or counterclockwise direction in each of the pixel areas is referred to as a cyclic pixel area, and the orientation direction of the first and fourth domains or the second And when the pixel regions in which the alignment directions of the third domains face each other or face in opposite directions are referred to as convergent pixel regions, the cyclic pixel regions and the convergent pixel regions alternate along the rows and the columns. Liquid crystal display device characterized in that provided. The method of claim 2,
And an area of the portion where each pixel area overlaps the first alignment area is equal to an area of a portion where each pixel area overlaps the second alignment area. The method of claim 7, wherein
And an area of the portion where each of the pixel regions overlap the third alignment region and an area of the portion of the pixel region overlapping the fourth alignment region are the same. The method of claim 2,
And an area in which each of the first to fourth alignment areas overlaps with one of two adjacent pixel areas is different from an area overlapping with the other one of the adjacent pixel areas. The method of claim 2,
And a plurality of gate lines extending in the extending direction of the row and arranged in the extending direction of the column on the first insulating substrate, and a plurality of data lines extending in the column direction and arranged in the extending direction of the row. A liquid crystal display device, characterized in that. The method of claim 10,
And each pixel area further comprises a thin film transistor connected to one of the gate lines and one of the data lines, wherein the thin film transistor is connected to a corresponding pixel electrode of the pixel electrodes. The method of claim 10,
Each pixel electrode is disposed between two adjacent data lines, and includes a first sub pixel electrode and a second sub pixel electrode configured to receive different voltages for the same gray level. The method of claim 12,
Each pixel area may include a first thin film transistor connected to one of the gate lines and one of two adjacent data lines, and one of the gate lines and the other one of the two data lines adjacent to each other. And a second thin film transistor connected to the first thin film transistor, wherein the first sub pixel electrode is connected to the first thin film transistor, and the second sub pixel electrode is connected to the second thin film transistor. The method of claim 12,
The first sub pixel electrode and the second sub pixel electrode in each pixel area are arranged in an extension direction of the column,
Wherein the first sub pixel electrode overlaps one of the first alignment region and the second alignment region, and the second sub pixel electrode overlaps the other of the first alignment region and the second alignment region. Liquid crystal display. The method of claim 12,
The first sub pixel electrode overlaps one of the third and fourth alignment regions, and the second sub pixel electrode overlaps the other of the third and fourth alignment regions. Liquid crystal display. The method of claim 1,
And the liquid crystal layer is a vertical alignment liquid crystal mode or a twisted nematic liquid crystal mode. The method of claim 16,
And the liquid crystal layer is provided in the vertical alignment liquid crystal mode, and the vertical alignment liquid crystal mode has a pretilt angle of 88 ° to 89 °. In the liquid crystal display device including a plurality of pixels, each pixel,
A first insulating substrate including four sub pixel regions arranged in the form of a row consisting of two rows and two columns;
Sub pixel electrodes provided in the sub pixel areas;
A first alignment layer covering the sub pixel electrodes and including a first alignment region and a second alignment region oriented in opposite directions to each other;
A second insulating substrate facing the first insulating substrate;
A common electrode on the second insulating substrate and facing the sub pixel electrodes;
A second alignment layer covering the common electrode and including a third alignment region and a fourth alignment region which are perpendicular to the alignment direction of the first alignment layer and oriented in opposite directions; And
A liquid crystal layer interposed between the first alignment layer and the second alignment layer,
The second alignment region is provided between the first alignment regions while overlapping portions of two adjacent sub pixel regions provided in the same row, and the fourth alignment region is a portion of two adjacent sub pixel regions arranged in the same column. And between the third alignment region while overlapping with each other. The method of claim 18,
And the liquid crystal layer includes a plurality of domains oriented in different directions according to two alignment regions corresponding to each other on a plane among the first to fourth alignment regions. 20. The method of claim 19,
The liquid crystal layer of each sub pixel region may include a first domain in which the first alignment region and the third alignment region overlap each other, a second domain in which the first and fourth alignment regions overlap, A third domain in which the second alignment region and the third alignment region overlap, and a fourth domain in which the second alignment region and the fourth alignment region overlap;
The arrangement order of the first to fourth domains may be different for each sub-pixel area.

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