KR20080038606A - Liquid crystal display apparatus - Google Patents

Abstract

An LCD device is provided to control the alignment direction of liquid crystal properly, thereby widening a viewing angle and display an image of high definition. An LCD(Liquid Crystal Display) device comprises a first substrate(100), a second substrate(200), liquid crystal, a pixel electrode(160) and a common electrode(240). A pixel area is defined on the first substrate, and the second substrate faces the first substrate. The liquid crystal is arranged between the first and second substrates. The pixel electrode is formed on the first substrate has plural sub pixel electrodes(161,162,163). The common electrode is formed on the second substrate. Each of the sub pixel electrodes has a cut pattern(10) formed from each edge part to a center in each edge part.

Description

Liquid crystal display device {Liquid Crystal Display Apparatus}

1 is a plan view of a liquid crystal display according to an exemplary embodiment of the present invention.

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

3A to 3C are plan views illustrating an operation process of the liquid crystal display of FIG. 1.

4 is a plan view of a liquid crystal display according to another exemplary embodiment of the present invention.

FIG. 5 is a cross-sectional view taken along the line II-II ′ of FIG. 4.

* Description of the symbols for the main parts of the drawings *

10-incision pattern 100-first substrate

160-pixel electrode 200-second substrate

240-common electrode 250-second domain discrimination means

260-Spacer 300-Liquid Crystal Layer

310,310 '-Liquid Crystal

The present invention relates to a display device, and more particularly, to a liquid crystal display device using a liquid crystal.

A liquid crystal display device is a display device using a liquid crystal having an intermediate state property of a liquid and a solid. The liquid crystal display device includes two substrates, and a liquid crystal layer having the liquid crystal is interposed between the two substrates.

The liquid crystal has an arrangement direction changed when an electric field is applied, and the transmittance of light varies depending on the arrangement direction. Accordingly, the liquid crystal display displays a corresponding image while adjusting the transmittance of light according to the alignment direction of the liquid crystal.

In most display devices for displaying an image, the image quality in the front direction perpendicular to the display device is superior to the image quality in the side direction inclined with respect to the front direction. In this case, when an angle at which an image of an appropriate image quality is displayed is a viewing angle, the viewing angle of the liquid crystal display is narrow. This is because the liquid crystals have different transmittances to the light depending on the arrangement direction, and the image quality of the liquid crystals decreases from the front side toward the side depending on the viewing angle of the liquid crystal display.

An object of the present invention is to provide a liquid crystal display device having a wide viewing angle and displaying a high quality image.

The liquid crystal display according to the exemplary embodiment of the present invention includes a first substrate, a second substrate, a liquid crystal, a pixel electrode, and a common electrode. The pixel region is defined in the first substrate. The second substrate faces the first substrate. The liquid crystal is arranged between the first and second substrates. The pixel electrode is formed on the first substrate and has a plurality of subpixel electrodes. The common electrode is formed on the second substrate. Each of the subpixel electrodes has an incision pattern formed toward each center from each corner portion at each corner portion.

In the above liquid crystal display, the cutting pattern has a sawtooth shape.

In the above liquid crystal display, the subpixel electrodes are disposed along a length direction of the pixel electrode. Here, the subpixel electrodes have the same rectangular shape, and the incision patterns positioned at four corners of the rectangular shape may be linear or point symmetrical to each other.

The liquid crystal display device further includes domain division means formed on the common electrode to divide the pixel region into a plurality of domains according to an arrangement direction of the liquid crystal. The domain dividing means may be a protrusion formed on the common electrode, and the protrusion is in contact with each of the subpixel electrodes to maintain a gap between the first and second substrates.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein and may be applied and modified in various forms. Rather, the following embodiments are provided to clarify the technical spirit disclosed by the present invention, and furthermore, to fully convey the technical spirit of the present invention to those skilled in the art having an average knowledge in the field to which the present invention belongs. Therefore, the scope of the present invention should not be construed as limited by the embodiments described below. In addition, in the drawings presented in conjunction with the following examples, the size of layers and regions are simplified or somewhat exaggerated to emphasize clarity, and like reference numerals in the drawings indicate like elements.

1 is a plan view of a liquid crystal display according to an exemplary embodiment of the present invention.

Referring to FIG. 1, a first substrate 100 and a second substrate 200 facing each other are provided. The gate line 110 and the data line 140 are formed on the first substrate 100. Gate line 110 extends generally parallel to the row direction. The data line 140 generally extends parallel to the column direction and crosses the gate line 110 in an insulated manner. The gate line 110 and the data line 140 are formed in plural and define a plurality of pixel areas PA that are the minimum units displaying the image while crossing each other.

The plurality of pixel areas PA have the same repetitive structure, and the structure in any one pixel area PA is equally applied to the others.

The pixel area PA includes the thin film transistor Tr and the pixel electrode 160. The thin film transistor Tr includes a gate electrode 111, a source electrode 141, and a drain electrode 142. The gate electrode 111 is branched from the gate line 110. The source electrode 141 branches off from the data line 140. The drain electrode 142 is spaced apart from the source electrode 141 and is electrically connected to the pixel electrode 160 through the contact hole 151.

The pixel electrode 160 is positioned to correspond to the pixel area PA and includes a plurality of subpixel electrodes. The plurality of subpixel electrodes are arranged in a line along the column direction. Hereinafter, the subpixel electrodes are classified according to their positions as a first subpixel electrode 161, a second subpixel electrode 162, and a third subpixel electrode 163. The first subpixel electrode 161 is electrically connected to the drain electrode 160. The first to third subpixel electrodes 161, 162 and 163 are electrically connected to each other through the connection electrode 170.

The first to third subpixel electrodes 161, 162 and 163 have the same rectangular shape. The pixel area PA may be set to have a column length of about three times the row length, and in this case, the first to third subpixel electrodes 161, 162, 163 may be arranged in the column direction in the pixel area PA. Each of the third subpixel electrodes 161, 162, and 163 has a square shape. However, the number of subpixel electrodes provided in the pixel area PA is not limited to three, and may be provided more or less.

Each of the first to third subpixel electrodes 161, 162, and 163 has a cutout pattern 10 formed toward the center from each corner portion at each corner portion. The common electrode 240 is formed on the second substrate 200. The common electrode 240 has domain distinguishing means 250 formed at the center of the first to third subpixel electrodes 161, 162, and 163. Detailed descriptions related to the operation of the cutting pattern 10 and the domain distinguishing means 250 will be described later.

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

2, the first and second substrates 100 and 200 face each other with the liquid crystal layer 300 therebetween. The gate electrode 111 is formed on the first substrate 100. The gate insulating layer 120 is formed on the gate electrode 111. The gate insulating layer 120 is formed by depositing an inorganic layer such as silicon nitride and covers the entire surface of the first substrate 100. The semiconductor film pattern 130 is formed on the gate insulating film 120.

The semiconductor film pattern 130 includes an active pattern 131 and an ohmic contact pattern 132. The active pattern 131 is formed of amorphous silicon and has a channel region in which a channel is formed during the operation of the thin film transistor Tr. The ohmic contact pattern 132 is formed to be separated into two parts by using amorphous silicon containing impurity ions as a material. The source electrode 141 and the drain electrode 142 are formed to face each other along the separated portion.

The source electrode 141 and the drain electrode 142 are covered with a passivation layer 150 covering the entire surface of the first substrate 100. The passivation layer 150 is formed of the same inorganic layer as the gate insulating layer 120, and a thick organic layer may be added on the inorganic layer as necessary. The passivation layer 150 has a contact hole 151 exposing the drain electrode 142. A pixel electrode 160 is formed on the passivation layer 150 to be in contact with the drain electrode 142.

The light blocking film pattern 210, the color filter 220, the overcoat film 230, and the common electrode 240 are formed on the second substrate 200. The light blocking layer pattern 210 covers a boundary between the region corresponding to the thin film transistor Tr and the pixel region PA, and blocks light transmission in the region. The light blocking layer pattern 210 is opened in the pixel area PA, and the color filter 220 is formed in the open portion. The color filter 220 includes red, green, and blue filters corresponding to three primary colors of light, and the three primary colors are alternately disposed for each pixel area PA. A color image is displayed according to the combination of the three primary colors of the color filter 220.

An overcoat layer 230 is formed on the color filter 220. The overcoat layer 230 serves to planarize the surface of the second substrate 200. The common electrode 240 is formed on the overcoat layer 230. An insulator protrusion is formed in a predetermined region on the common electrode 240 to define a domain dividing means 250.

Hereinafter, an operation process of the liquid crystal display will be described.

3A to 3C are plan views illustrating an operation process of the liquid crystal display of FIG. 1.

1, 2, and 3A to 3C, the liquid crystal 310 has an elliptic shape having a different length between the major axis and the minor axis, and the arrangement direction is defined as the major axis. The electric field is not applied to the liquid crystal layer 300 in the off state during the operation of the liquid crystal display, but is applied to the liquid crystal layer 300 in the on state.

As shown in FIG. 3A, no electric field is formed in the liquid crystal layer 300 in the off state, and the liquid crystal 310 is arranged in a direction perpendicular to the first and second substrates 100 and 200. Polarizers (not shown) in which absorption axes are disposed perpendicular to each other are attached to the outside of the first and second substrates 100 and 200. Light is provided from the lower portion of the first substrate 100 during the operation of the liquid crystal display, and the light is linearly polarized while passing through the polarizing plate attached to the outside of the first substrate 100. The linearly polarized light passes through the liquid crystal layer 300. In the arrangement state of the liquid crystal 310, the light is maintained in phase. Therefore, the light passing through the liquid crystal layer 300 does not pass through the polarizer attached to the outside of the second substrate 200, and the liquid crystal display is in a black state.

In the on state, different voltages are applied to the pixel electrode 160 and the common electrode 240, respectively. When the gate-on signal is transmitted along the gate line 110 and the thin film transistor Tr is turned on, the data signal is transmitted along the data line 140 and a corresponding data voltage is applied to the pixel electrode 160. do. The data voltage corresponds to the image information to be displayed, and a constant common voltage is applied to the common electrode 240.

An electric field is formed in the liquid crystal layer 300 due to the difference between the data voltage and the common voltage. The liquid crystal 310 has negative dielectric anisotropy, and the liquid crystal 310 is arranged in a direction inclined with respect to the first and second substrates 100 and 200 by the electric field. In this arrangement state, the liquid crystal 310 causes a phase change with respect to light passing therethrough. The phase change value depends on the degree of inclination of the liquid crystal 310, and the degree of inclination is adjusted according to the intensity of the electric field.

Light is provided from the lower portion of the first substrate 100, and the light is linearly polarized by passing through the polarizer attached to the first substrate 100. The linearly polarized light is changed in phase while passing through the liquid crystal layer 300 to transmit the polarizing plate attached to the outside of the second substrate 200. An image is displayed on the outside by the transmitted light.

In the above operation, since the insulator protrudes from the domain dividing means 250, a common voltage cannot be applied to the region where the protrusion is formed. As a result, the intensity or direction of the electric field is changed in the region where the domain dividing means 250 is formed. Here, the domain dividing means 250 does not necessarily need to be formed as a protrusion, and may be formed by other means as long as the common voltage is not applied. For example, the domain dividing means 250 may be formed by cutting a region where the protrusion is formed instead of the protrusion in the common electrode 240.

As described above, the direction of action of the electric field changed by the domain dividing means 250 depends on the position of the domain dividing means 250 or the shape of the pixel electrode 160.

Referring to FIG. 3B, the domain dividing means 250 is positioned at the center of the first subpixel electrode 161 (or the second subpixel electrode 162 or the third subpixel electrode 163). For convenience, each side of the rectangular first subpixel electrode 161 is divided, and the upper side 1 in the row direction, the left side 2 in the column direction, the lower side 3 facing the upper side 1 and the left side 2 ) Is called the right side (4). The changed electric field is formed differently for each region according to the length direction of the upper side 1, the left side 2, the lower side 3, and the right side 4.

As a result, a first electric field is formed in the first region I formed by connecting the domain dividing means 250 and the upper side 1 to connect both ends of the domain dividing means 250 and the upper side 1. . In addition, a second electric field is formed in the second region II formed by connecting the domain dividing means 250 and the left side 2 to connect both ends of the domain dividing means 250 and the left side 2. In addition, a third electric field is formed in the third region III formed by connecting the domain dividing means 250 and the lower side 3 to connect both ends of the domain dividing means 250 and the lower side 3. In addition, a fourth electric field is formed in the fourth region IV formed by connecting the domain dividing means 250 and the right side 4 to connect both ends of the domain dividing means 250 and the right side 4.

As shown in FIG. 3B, the arrangement direction of the liquid crystal 310 in the first to fourth regions I, II, III, and IV varies according to the first to fourth electric fields. When the pixel area PA is divided according to the arrangement of the liquid crystal 310 and each divided area is named as one domain, the pixel area PA is divided into a plurality of domains by the domain distinguishing means 250. As the liquid crystals 310 are arranged in various directions in the plurality of domains, a viewing angle of the liquid crystal display is increased.

Referring to FIG. 3C, an incision pattern 10 is formed in a region where the upper side 1 and the left side 2 are adjacent to each other. The cutting pattern 10 is formed by cutting a predetermined region of the first subpixel electrode 161. Since the data voltage cannot be applied to a region where the cutout pattern 10 is formed, the cutout pattern 10 changes the electric field acting on the liquid crystal layer 300 like the domain dividing means 250. The changed electric field is symmetrical on both sides of the cutting pattern 10, and the liquid crystal 310 ′ adjacent to the cutting pattern 10 is arranged perpendicular to the cutting pattern 10 on a plane.

The incision pattern 10 controls the arrangement of the liquid crystal 310 ′ in a region where the upper side 1 and the left side 2 are adjacent to each other. If there is no incision pattern 10, the liquid crystal 310 ′ of the region where the upper side 1 and the left side 2 are adjacent are simultaneously affected by the first and second electric fields. As a result, the liquid crystal 310 'of the corresponding region is weakened and the arrangement of the liquid crystal 310' is disturbed, and a low quality image can be displayed. In order to prevent this, an incision pattern 10 is provided, and the incision pattern 10 operates to compensate for the control force on the liquid crystal 310 'in the region where the upper side 1 and the left side 2 are adjacent to display a high quality image. do.

The incision pattern 10 may have various shapes that may complement the restricting force on the liquid crystal 310 ′ by dividing an edge portion adjacent to the upper side 1 and the left side 2. For example, the cutout pattern 10 may have a sawtooth shape. Here, the sawtooth includes all whose hypotenuses have a straight or curved shape. In addition, the length of the hypotenuse and the number of teeth can also be formed in the plural in the singular as necessary. That is, the length of the hypotenuse or the number of teeth may increase according to the area of the first subpixel electrode 161.

As shown in FIG. 1, the cutout pattern 10 is formed at each corner portion of the first subpixel electrode 161. Since the first subpixel electrode 161 has a rectangular shape and the domain dividing means 250 is positioned at the center of the first subpixel electrode 160, the first to fourth electric fields are symmetrically formed. It is preferable that the cutout patterns 10 of the respective corner portions of the one subpixel electrode 160 also become line symmetry or point symmetry with each other.

For example, the cutting patterns 10 formed at both ends of the upper side 1 are linearly symmetrical with respect to the column direction. In addition, the incision pattern 10 formed at the corner where the upper side 1 and the left side 2 meet is the incision pattern 10 formed at the corner where the lower side 3 and the right side 4 meet the domain distinguishing means 250. This results in point symmetry between them.

4 is a plan view of a liquid crystal display according to another exemplary embodiment of the present invention, and FIG. 5 is a cross-sectional view taken along the line II-II 'of FIG. 4.

4 and 5, the first and second substrates 100 and 200 facing each other and the liquid crystal layer 300 interposed therebetween are provided. The pixel area PA is defined on the first substrate 100 while the gate line 110 and the data line 140 cross each other insulated from each other. The pixel area PA includes the thin film transistor Tr and the pixel electrode 160.

The thin film transistor Tr includes a gate electrode 111, a source electrode 141, and a drain electrode 142. The pixel electrode 160 is electrically connected to the drain electrode 142 and positioned to correspond to the pixel area PA. The pixel electrode 160 includes first and second subpixel electrodes 161 and 162 arranged in a line along the column direction. The first subpixel electrode 161 is electrically connected to the drain electrode 142 of the thin film transistor Tr. The second subpixel electrode 162 is electrically connected to the first subpixel electrode 161 through the connection electrode 170.

Each of the first and second subpixel electrodes 161 and 162 has a cutting pattern 10 formed toward the center from each corner portion. The cutting pattern 10 serves to prevent the arrangement of the liquid crystals in each corner portion. The incision pattern 10 has a different shape than that of the previous embodiment.

The light blocking film pattern 210, the color filter 220, the overcoat film 230, the common electrode 240, and the spacer 260 are formed on the second substrate 200. The spacer 260 is positioned at the center of the first and second subpixel electrodes 161 and 162. The spacer 260 is formed of an insulator protruding to contact the surface of the pixel electrode 160 on the common electrode 240.

As described above, since the spacer 260 is made of an insulator, the common voltage may not be applied in the region where the spacer 260 is formed. Therefore, the spacer 260 acts as a domain dividing means similarly to the projection of the previous embodiment. At the same time, the spacer 260 is in contact with the first substrate 100 to maintain a constant gap between the first and second substrates 100 and 200.

According to the embodiments described above, proper control of the arrangement direction of the liquid crystal is performed, and thus the viewing angle is widened and a high quality image is displayed.

However, the above several embodiments are presented by way of example, and those skilled in the art can vary the present invention without departing from the spirit and scope of the present invention as set forth in the claims below. It will be understood that modifications and changes can be made.

Claims (9)

A first substrate on which a pixel region is defined; A second substrate facing the first substrate; Liquid crystal arranged between the first and second substrates; A pixel electrode formed on the first substrate and having a plurality of subpixel electrodes; And A common electrode formed on the second substrate, And each of the subpixel electrodes has an incision pattern formed toward each center from each corner portion at each corner portion. The method of claim 1, The incision pattern is a liquid crystal display, characterized in that the sawtooth. The method of claim 1, And the subpixel electrodes are disposed along a length direction of the pixel electrode. The method of claim 3, wherein And a connection electrode connecting the subpixel electrodes adjacent to each other along the length direction. The method of claim 3, wherein And the subpixel electrodes have the same rectangular shape. The method of claim 5, And the cutout patterns positioned at four corners of the rectangle are line symmetrical or point symmetrical to each other. The method of claim 1, And a domain dividing unit formed on the common electrode and dividing the pixel region into a plurality of domains according to an arrangement direction of the liquid crystal. The method of claim 7, wherein And the domain dividing means is a protrusion formed on the common electrode and positioned in a region corresponding to the center of each of the subpixel electrodes. The method of claim 8, And the protrusion is in contact with each of the subpixel electrodes to maintain a gap between the first and second substrates.

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