KR100695296B1 - liquid crystal display - Google Patents

Abstract

On the lower plate, a pixel electrode in which the first opening pattern and the second opening pattern are alternately formed in each pixel area is formed. On the upper plate facing the lower plate, a color filter and a black matrix are formed, and a common electrode covering them is formed on the entire surface. Here, the first opening pattern and the second opening pattern are each formed by meeting the first diagonal line portion and the second diagonal line portion, the third diagonal line portion and the fourth diagonal line portion, wherein the angles at which the respective diagonal lines meet are 90 ° to 120 degrees. The first diagonal portion, the fourth diagonal portion, the second diagonal portion, and the third diagonal portion constitute 90 °, respectively. In this case, when voltage is applied to the pixel electrode and the common electrode, the liquid crystal molecules of each pixel region are oriented in four directions, and the liquid crystal molecules of the adjacent pixel regions are aligned in eight directions so that the viewing angle is uniformly obtained in any direction. have. In addition, the nonuniformity region of the liquid crystal molecular alignment becomes narrower than the case where the angle of inclination is 90 °, so that the response speed can be improved. In this case, instead of forming the first and second opening patterns on the pixel electrode, the protrusion pattern may be formed in the same shape as the opening pattern.

Viewing angle, response speed, orientation, aperture pattern, protrusion pattern

Description

Liquid crystal display

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

FIG. 2 is a cross-sectional view illustrating the top and bottom plates of the liquid crystal display according to the first embodiment of the present invention and the alignment of liquid crystals therebetween;

3 is a cross-sectional view illustrating an alignment of an upper plate and a lower plate of a liquid crystal display according to a second exemplary embodiment of the present invention with liquid crystals between them;

FIG. 4A illustrates the transmission axis (or absorption axis) of the liquid crystal and the polarizing plate after voltage is applied to the upper and lower plates of the liquid crystal display device.

4B illustrates the transmission axis (or absorption axis) of the liquid crystal and the polarizing plate when no voltage is applied to the upper and lower plates of the liquid crystal display device.

5A and 5B illustrate an alignment of liquid crystals according to a pattern shape of a common electrode.

6 is a plan view illustrating a pattern of a pixel electrode of a liquid crystal display according to another exemplary embodiment of the present invention.

The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device for improving a response speed.

In general, a liquid crystal display device injects a liquid crystal material between an upper substrate on which a common electrode and a color filter are formed, and a lower substrate on which a thin film transistor and a pixel electrode are formed, and applies a voltage between the pixel electrode and the common electrode. It is an apparatus that displays an image by forming an electric field therebetween to change the arrangement of liquid crystal molecules, and thereby control the amount of light transmitted therethrough.

Such liquid crystal displays are applied to portable devices having small monitors, to monitors and televisions of computers, and the like. In order to successfully apply liquid crystal displays in various fields, it is necessary to lower prices and improve narrow viewing angles and slow response speeds. .

One of the methods proposed to widen the viewing angle is a vertical alignment method having multiple regions, which uses a fringe field formed by forming opening patterns or protrusions on the pixel electrode and the common electrode. By dispersing the tilting direction of the molecules in four directions to secure a wide viewing angle.

However, in such a liquid crystal display, an organic insulating film (overcoat film) is coated on the color filter to prevent the color filter from being damaged when the common electrode is patterned, which causes a problem that the overcoat film is expensive. In addition, when the overcoat film is formed, the common electrode does not directly contact the black matrix formed of chromium or the like, which causes problems such as increased resistance and severe flicker defects. .

On the other hand, as an example of the prior art for forming a multi-region, there is a method of setting the angle of bending of the opening pattern to 90 °, the luminance is reduced and the response is reduced in the area where the two regions of the opposite direction of rotation of the liquid crystal molecules meet There is a problem that the speed is slow.

The technical problem to be achieved by the present invention is to improve the response speed.

Another technical problem to be achieved by the present invention is to improve the viewing angle.

In order to achieve the above object, the present invention forms an opening pattern or a projection pattern having an angle of 90 ° to 120 ° at the pixel electrode.

On the first insulating substrate of the liquid crystal display according to the present invention, a plurality of pixel electrodes are repeatedly formed in the first opening pattern and the second opening pattern for each of the plurality of pixel regions, and the second insulating substrate faces the first substrate. The common electrode is formed on the front surface. The liquid crystal layer is injected between the first substrate and the second substrate. Here, the first opening pattern includes a first opening formed in the first direction and a second opening connected to the first opening and formed in a second direction forming 90 ° to 120 ° with the first direction. The second opening pattern includes a third opening formed in the third direction and a fourth opening connected to the third opening and formed in the fourth direction forming 90 ° to 120 ° with the third direction.

In this case, the angle formed by the first opening portion and the fourth opening portion and the angle formed by the second opening portion and the third opening portion are each 90 °, and the first direction is oblique to the sides of the pixel electrode.

When voltage is applied to the pixel electrode and the common electrode of the liquid crystal display having such a structure, one pixel region is divided into four small domains, and the four domains are divided by the average long axis direction of the liquid crystal molecules in the domain. The two pixel areas are divided into eight small domains.

Here, first and second polarizing plates are formed outside the first and second substrates, respectively, and transmission axes of the first and second polarizing plates are perpendicular to each other, and absorption axes of the first and second polarizing plates are mutually different. It is preferable to make it vertical.

On the other hand, it may further include a plurality of projection patterns alternately formed with the first opening pattern and the second opening pattern, the angle of bending of the projection pattern is preferably 90 ° to 120 °.

According to another exemplary embodiment of the present invention, a plurality of pixel electrodes having a plurality of pixel electrodes repeatedly formed on the first insulating substrate and having a first protrusion pattern and a second protrusion pattern on each pixel area and facing the first substrate may include second insulation. The common electrode is formed on the front surface of the substrate. The liquid crystal layer is injected between the first substrate and the second substrate. Here, the first protrusion pattern includes a first protrusion formed in the first direction and a second protrusion connected to the first protrusion and formed in a second direction forming 90 ° to 120 ° with the first direction. The second protrusion pattern includes a third protrusion formed in the third direction and a fourth protrusion connected to the third protrusion and formed in a fourth direction forming 90 ° to 120 ° with the third direction.

Here, the angle formed by the first and fourth protrusions and the angle formed by the second and third protrusions are 90 °, respectively, and the first direction is oblique to the sides of the pixel electrode.

In this case, when a voltage is applied to the pixel electrode and the common electrode, one pixel region is divided into four small domains, and the four domains are divided by the average major axis direction of the liquid crystal molecules in the domain, and two neighboring pixel regions are It is divided into eight small domains.

In the present invention, when a voltage is applied to the pixel electrode and the common electrode, the liquid crystal molecules of each pixel region are aligned in four directions, and the liquid crystal molecules of the adjacent pixel regions are aligned in eight directions to obtain a uniform viewing angle in any direction. Can be. In addition, the nonuniformity region of the liquid crystal molecular alignment becomes narrower than the case where the angle of inclination is 90 °, so that the response speed can be improved.

Next, a liquid crystal display according to an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement the same.

First, the structure of a liquid crystal display according to an exemplary embodiment of the present invention will be described in detail with reference to FIGS. 1 to 5B.

1 is a plan view illustrating a pattern of pixel electrodes of a liquid crystal display according to an exemplary embodiment of the present invention, and FIG. 2 is a top and bottom plates of the liquid crystal display according to the first exemplary embodiment of the present invention and alignment of liquid crystals therebetween. 3 is a cross-sectional view illustrating the top and bottom plates of the liquid crystal display according to the second exemplary embodiment of the present invention and the alignment of the liquid crystal therebetween. Here, the pixel electrode has shown portions corresponding to two pixel regions.

First, as illustrated in FIG. 1, pixel electrodes 110 and 120 are formed in the pixel area P1 on the left side and the pixel area P2 on the right side, respectively, and the opening patterns 150 are formed in the pixel electrodes 110 and 120, respectively. , 160 are formed. Looking at this in more detail, the pixel electrode 110 is connected to the first diagonal portion 151 extending diagonally from the left to the right and the first diagonal portion 151 and extending diagonally from the left to the lower right. A first opening pattern 150 including a second diagonal line portion 152 is formed, and a third diagonal portion 161 extending in an oblique direction from the left to the upper right in the pixel electrode 120 and the third diagonal line portion 161. A second opening pattern 160 is formed, which is connected to the diagonal line 161 and includes a fourth diagonal line 162 extending in a diagonal direction from the left side to the lower right side. Here, although only two pixel regions P1 and P2 are shown, the first and second opening patterns 150 and 160 are repeatedly formed in all pixel regions.

At this time, the angle formed by the first diagonal portion 151 and the second diagonal portion 152 and the angle formed by the third diagonal portion 161 and the fourth diagonal portion 162 are 90 ° to 120 °, respectively. An angle formed by the diagonal portion 151 and the fourth diagonal portion 162 and an angle formed by the second diagonal portion 152 and the third diagonal portion 161 are each 90 °.

In addition, although not shown here, a color filter, a black matrix, and a common electrode are formed in the upper plate corresponding to the lower plate. Red, green, and blue color filters are formed in portions corresponding to the pixel regions, and a black matrix is formed between the color filters, and a common electrode covering the color filter and the black matrix is formed on the front surface of the upper plate.

As such, when the lower plate on which the pixel electrodes 110 and 120 having the opening patterns 150 and 160 are formed is aligned with the upper plate on which the common electrode is formed on the front surface, a voltage is applied between the two substrates. By the fringe field, the alignment of the liquid crystal molecules 40 is as shown in FIG. This will be described in detail with reference to FIGS. 1 and 2.

FIG. 2 is a cross-sectional view taken along line II-II of FIG. 1 after aligning the upper and lower plates of the liquid crystal display, and the cut line is perpendicular to the opening pattern 150. Here, among the components formed on the upper and lower plates, those not directly related to the contents of the present invention are omitted in the drawings.

As shown in FIG. 2, the common electrode 120 is formed on the front surface of the upper plate 12, and the pixel electrode 110 having the opening pattern 150 is formed on the lower plate 11.

Before the voltage is applied between the upper plate 12 and the lower plate 11, the liquid crystal molecules are oriented perpendicular to the two substrates 11 and 12, and when a voltage is applied between the two substrates 11 and 12, the upper plate and the lower plate are separated. An electric field is formed in the electric field, and the electric field is bent by the opening pattern 150 formed in the pixel electrode of the lower plate 11, which is called a fringe field f. The liquid crystal molecules 40 are arranged in a direction perpendicular to the fringe field f as shown in FIG. 2. When the arrangement of the liquid crystal molecules 40 is viewed from the upper side (arrow direction) of the upper plate 12, as shown in FIG. 1, the liquid crystal molecules 40 are oriented in both directions about the opening patterns 150 and 160 so that the pixel region P1 is aligned. , P2) is divided into four small domains, and the four small domains are divided by the average long axis direction of the liquid crystal molecules in the domain.

Next, the arrangement of the liquid crystals before and after applying voltage to the upper and lower plates of the liquid crystal display will be described in detail with reference to FIGS. 4A and 4B. FIG. 4A illustrates the liquid crystal and the polarizer after applying voltage to the upper and lower plates of the liquid crystal display, and FIG. 4B illustrates the liquid crystal and the polarizer when the voltage is not applied to the upper and lower plates of the liquid crystal display. will be.

Although not shown here, a polarizing plate is positioned outside the upper plate 12 and the lower plate 11, respectively, and the transmission axes (or absorption axes) 51 and 61 of the upper and lower polarizing plates are horizontal (0 °) and vertical, respectively. (90 degrees) or vertically and vertically so that it may become a horizontal direction.

As shown in FIG. 4A, the transmission axes (or absorption axes) 51 and 61 of the two polarizing plates are perpendicular to each other, and the orientation of the liquid crystal molecules 41 in one pixel region is divided into four divisions into four small domains. The four domains are formed by the alignment region, and are divided by the average long axis direction of the liquid crystal molecules 41 in the domain. In consideration with the adjacent pixel regions, the two pixel regions are divided into eight divisional alignment regions divided into eight small domains. In this case, the long axis of the liquid crystal molecules 41 in one pixel region forms ± 30 ° with the transmission axis (or absorption axis) 61 of the polarizer located outside the upper plate, and the long axis of the liquid crystal molecules 41 in the other pixel region. Is ± 60 °. Therefore, even when a voltage is applied to the upper plate 12 and the lower plate 11, a uniform viewing angle can be obtained in the white state when viewed from any direction.

 In addition, when the electric field is not applied, as shown in FIG. 4B, the liquid crystal molecules 42 are vertically oriented with respect to the two substrates, so that they are perpendicular to the transmission axes (or absorption axes) 52 and 62 of the polarizing plates, and thus excellent black state does not leak light. Can be obtained.

Here, the first diagonal portion 151, the second diagonal portion 152, the third diagonal portion 161, and the fourth forming the first opening pattern 150 and the second opening pattern 160 of the pixel electrode, respectively. The angles formed between the diagonal portions 162 are 90 ° to 120 °, and the response speed of the liquid crystal molecules may be reduced in the bending portions of the opening patterns 150 and 160, thereby reducing the response speed. . This will be described with reference to FIGS. 5A and 5B.

FIG. 5A illustrates an angle formed between the first diagonal portion 151 and the second diagonal portion 152 or the third diagonal portion 161 and the fourth diagonal portion 162 at 90 °, and FIG. 5B illustrates the first diagonal portion. This is when the angle formed by 151 and the second diagonal portion 152 or the third diagonal portion 161 and the fourth diagonal portion 162 is 120 °.

As shown in FIG. 5A, in the curved portion D1 where the first diagonal portion 151 and the second diagonal portion 152 meet, the torsional motions of the liquid crystal molecules 45 are opposite to each other. Interfering with the torsional motion of the liquid crystal molecules will slow down. For this reason, when a voltage is applied between the upper plate and the lower plate, and when it is not applied, the liquid crystal does not operate quickly, which causes a slow response time.

Accordingly, in order to solve this problem, as shown in FIG. 5B, an angle formed by the first diagonal portion 151, the second diagonal portion 152, the third diagonal portion 161, and the fourth diagonal portion 162, that is, the opening pattern, is formed. Increase the angle of inclination of (150, 160) to 90 ° to 120 °. In this case, the degree of disturbance of the twisting operation of the other region in the bent portion D2 of the opening patterns 150 and 160 becomes smaller than the case described above, so that the non-uniform region of the alignment of the liquid crystal molecules 46 is narrowed. Can improve the response speed. However, when the angle of inclination is set to 120 ° or more, the long axis of the liquid crystal molecules approaches the transmission axis or absorption axis of the polarizing plate when the electric field is applied, so that the luminance may be lowered. Therefore, the angle is preferably set to 90 ° to 120 °.

Meanwhile, instead of forming the opening patterns 150 and 160 in the lower pixel electrodes 110 and 120, protrusions are formed in the same shape as the opening patterns 150 and 160 to improve the response speed as described above. Can be. This will be described as a second embodiment of the present invention with reference to FIG.

As shown in FIG. 3, the common electrode 120 is formed on the front surface of the upper plate 12, and the protrusion pattern 130 is formed on the lower plate 11, and the pixel electrode 110 is formed thereon. The protrusion pattern 130 may be formed in the same planar shape as the opening patterns 150 and 160 described above. The protrusion pattern 130 may be formed in various ways, and may be formed in a process prior to forming the pixel electrode 110. When a voltage is applied to the upper plate 12 and the lower plate 11 by the protrusion pattern 130, a fringe field f is formed, and the arrangement of the liquid crystal molecules 48 is divided into four pixel regions as shown in FIG. 3. Since the alignment region is formed, and the quadrant alignment region is formed in the remaining pixel regions, the eight division alignment regions are formed in the two pixel regions, and thus the same effects as in the case of forming the opening patterns 150 and 160 described above can be obtained.

In addition, as shown in FIG. 6, an opening pattern and a projection pattern may be simultaneously formed in one pixel area.

In this case, the opening pattern 157 is formed between the protrusion patterns 155, 156, and 158 in the pixel region P1, and the positions of the protrusion patterns 155, 156, and 158 and the opening pattern 157 are changed to be formed. There may be. An opening pattern 166 is formed between the protrusion patterns 165 and 167 in the pixel region P2, and positions of the protrusion patterns 165 and 167 and the opening pattern 166 may be changed. At this time, the angle formed by the projection patterns 155 and 156 and the angle of bending of the center of the plurality of patterns 157, 158, 165, 166 and 167 are 90 ° to 120 °.

As described above, in the present invention, a pixel electrode in which the first opening pattern and the second opening pattern are alternately formed in each pixel area is formed, and the first diagonal portion and the second forming the first opening pattern and the second opening pattern, respectively, are formed. The angle between the diagonal line portion and the portion where the third diagonal line portion and the fourth diagonal portion meet is 90 ° to 120 °, and the first opening pattern and the second opening pattern are 90 °, so that when the electric field is applied, The liquid crystal molecules are aligned in four directions, and are aligned in eight directions together with the liquid crystal molecules in adjacent pixel regions to obtain a uniform viewing angle in any direction. In addition, the nonuniformity region of the liquid crystal molecular alignment becomes narrower than the case where the angle of inclination is 90 °, so that the response speed can be improved.

Claims (13)

First insulating substrate, A plurality of pixel electrodes in which a first opening pattern and a second opening pattern are repeatedly formed on each of the plurality of pixel areas on the first substrate; A second insulating substrate facing the first substrate, A common electrode formed on the entire surface of the second substrate; A liquid crystal layer injected between the first substrate and the second substrate Including; The first opening pattern includes a first opening formed in a first direction and a second opening connected to the first opening and formed in a second direction forming 90 ° to 120 ° with the first direction. The second opening pattern may include a third opening formed in a third direction and a fourth opening connected to the third opening and formed in a fourth direction forming 90 ° to 120 ° with the third direction. Liquid crystal display. In claim 1, And an angle formed by the first opening portion and the fourth opening portion, and an angle formed by the second opening portion and the third opening portion is 90 °, respectively. In claim 1, And the first direction is a diagonal direction with respect to the side of the pixel electrode. In claim 1, When a voltage is applied to the pixel electrode and the common electrode, one pixel area is divided into four small domains, and the four domains are divided by an average long axis direction of liquid crystal molecules in the domain. In claim 4, And two voltage regions adjacent to each other when the voltage is applied to the pixel electrode and the common electrode. In claim 1, And first and second polarizing plates positioned outside the first substrate and the second substrate, respectively, wherein transmission axes of the first and second polarizing plates are perpendicular to each other and absorption axes of the first and second polarizing plates. The liquid crystal display device perpendicular to each other. In claim 1, And a plurality of protrusion patterns alternately formed with the first opening pattern and the second opening pattern, wherein the bent angle of the protrusion pattern is 90 ° to 120 °. First insulating substrate, A plurality of pixel electrodes on which the first projection pattern and the second projection pattern are repeatedly formed on each of the plurality of pixel regions on the first substrate; A second insulating substrate facing the first substrate, A common electrode formed on the entire surface of the second substrate; Liquid crystal layer injected between the first substrate and the second substrate Including; The first protrusion pattern may include a first protrusion formed in a first direction and a second protrusion connected to the first protrusion and formed in a second direction forming 90 ° to 120 ° with the first direction. The second protrusion pattern may include a third protrusion formed in a third direction and a fourth protrusion connected to the third protrusion and formed in a fourth direction forming 90 ° to 120 ° with the third direction. Liquid crystal display. In claim 8, And an angle between the first protrusion and the fourth protrusion and an angle between the second protrusion and the third protrusion is 90 °, respectively. In claim 8, And the first direction is a diagonal direction with respect to the side of the pixel electrode. In claim 8, When a voltage is applied to the pixel electrode and the common electrode, one pixel area is divided into four small domains, and the four domains are divided by an average long axis direction of liquid crystal molecules in the domain. In claim 11, And two voltage regions adjacent to each other when the voltage is applied to the pixel electrode and the common electrode. In claim 8, And first and second polarizing plates positioned outside the first substrate and the second substrate, respectively, wherein transmission axes of the first and second polarizing plates are perpendicular to each other and absorption axes of the first and second polarizing plates. The liquid crystal display device perpendicular to each other.

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