KR20110038827A - Liquid crystal display device - Google Patents

Abstract

PURPOSE: An LCD(Liquid Crystal Display) device is provided to adjust a view angle to improve optical characteristics. CONSTITUTION: A first common electrode(4) is formed is a main pixel domain on an array substrate, and a first pixel electrode(5) is formed on the first common electrode to form a fringe electronic field and the first common electrode. A second common electrode(6) is formed on a sub pixel domain on the array substrate, and a second pixel electrode(7) is formed on the second common electrode to form the second common electrode and the fringe electric field. First and second switching elements are formed on the array substrate and connected to the first and second pixel electrodes. A third common electrode(8) is formed in the sub pixel domain on an opposed substrate and forms an electric field vertical to the second pixel electrode.

Description

Liquid crystal display device

The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device that can adjust the viewing angle.

As the information society develops, the demand for display devices for displaying images is increasing in various forms. Recently, liquid crystal displays (LCDs), plasma display panels (PDPs), and organic light emitting diodes Various flat display devices such as organic light emitting diodes (OLEDs) are being utilized.

Among these flat panel display devices, liquid crystal display devices are widely used because they have advantages of miniaturization, light weight, thinness, and low power driving.

A liquid crystal display device is a device that displays information by adjusting the amount of light passing through using the electro-optical properties of the liquid crystal and the polarization properties of the polarizing plate.

Generally, the liquid crystal used for a liquid crystal display device differs in liquid crystal refractive index anisotropy in a front direction and a viewing angle direction. As a result, a difference in the phase delay value is generated, so that the displayed image is completely invisible in the viewing angle direction. Thus, the liquid crystal display device has a problem that the viewing angle is narrow.

In order to solve such a problem, a method of forming a multi-domain in a liquid crystal and a method of using a compensation film have been proposed. By such a method, the image distortion phenomenon in the viewing angle direction can be improved, and wide viewing angle characteristics can be achieved.

However, with the recent increase in the use of portable displays, there is a problem related to the exposure of personal privacy information in public places. Accordingly, there is a need for a liquid crystal display device having a narrow viewing angle characteristic and capable of adjusting a viewing angle, and various research results have been reported. On the other hand, on the contrary, it is true that a liquid crystal display device having a wide viewing angle characteristic is required for sharing information among various people.

In accordance with these demands, a method of adding a narrow viewing angle characteristic to a liquid crystal display having a wide viewing angle characteristic has been studied. In the liquid crystal display having the above characteristics, the viewing angle can be adjusted for one pixel by dividing it into a main pixel for displaying video information and an auxiliary pixel for adjusting the viewing angle. As one of such techniques, the electrode pattern of the auxiliary pixel for adjusting the viewing angle is different from that of the main pixel, and the liquid crystal in the auxiliary pixel as the viewing angle adjusting region is tilted, thereby causing light leakage in the left and right or up and down viewing angle directions. There is a technique proposed to cause.

However, in such a technique, since the electrode patterns are different between the main pixel and the auxiliary pixel, an additional process is required. In addition, since only the liquid crystal is tilted, the light in the subpixel region does not come to the front, and thus has a problem in terms of transmittance.

As described above, the conventional viewing angle adjusting liquid crystal display has problems in terms of manufacturing process and optical characteristics.

The present invention has a problem to provide a viewing angle control liquid crystal display device that can improve the manufacturing process and optical characteristics.

In order to achieve the above object, the present invention provides a liquid crystal display device in which a pixel region is divided into a main pixel region and an auxiliary pixel region, the first common electrode formed in the main pixel region of the array substrate, and the first common electrode. A first pixel electrode formed on the first common electrode to form a first common electrode and a fringe electric field; A second common electrode formed in the auxiliary pixel region of the array substrate, and a second pixel electrode formed on the second common electrode to form a fringe electric field with the second common electrode; First and second switching elements formed on the array substrate and connected to the first and second pixel electrodes, respectively; A third common electrode formed in the auxiliary pixel region of the opposing substrate and configured to form a vertical electric field with the second pixel electrode; A liquid crystal positioned between the array substrate and the counter substrate, the liquid crystal positioned in the main pixel region is initially horizontally aligned, and the liquid crystal positioned in the auxiliary pixel region initially provides a hybrid aligned liquid crystal display device. .

The first and second pixel electrodes may have a lattice shape, respectively, and the first and second common electrodes may have a planar shape or a lattice shape, respectively.

The liquid crystal is a negative type of nematic liquid crystal, the long axis direction of the lattice window of the first pixel electrode and the rubbing direction of the array substrate of the liquid crystal located in the main pixel region form an angle of 45 to 90 degrees, and the second pixel. The long axis direction of the lattice window of the electrode and the rubbing direction of the array substrate of the liquid crystal positioned in the auxiliary pixel region may form an angle of 45 to 90 degrees.

The width of the first grating extending along the major axis of the grating window of the first pixel electrode is 1 to 10 μm, the spacing between neighboring first gratings is 1 to 20 μm, and the grating window of the second pixel electrode is The width of the second lattice extending along the long axis of may be 1 ~ 10㎛, the spacing between the adjacent second lattice may be 1 ~ 20㎛.

First and second data wires disposed on both sides of the pixel region and connected to the first and second switching transistors, respectively; The display device may further include a gate line crossing the first and second data lines and commonly connected to the first and second switching transistors.

A data line disposed on one side of the pixel area and commonly connected to the first and second switching transistors; The semiconductor device may further include first and second gate wires crossing the data wires and connected to the first and second switching transistors, respectively.

In another aspect, the present invention provides a liquid crystal display device in which an image display unit region is divided into three image display regions for displaying image information and a viewing angle adjustment region for adjusting a viewing angle, wherein each of the image display regions of an array substrate is provided. A first common electrode formed on the first common electrode to form a fringe electric field with the first common electrode; A second common electrode formed in the viewing angle control region of the array substrate, and a second pixel electrode formed on the second common electrode to form a fringe electric field with the second common electrode; First and second switching elements formed on the array substrate and connected to the first and second pixel electrodes, respectively; A third common electrode formed in the viewing angle adjusting region of the opposing substrate and configured to form a vertical electric field with the second pixel electrode; A liquid crystal positioned between the array substrate and the opposite substrate, wherein the liquid crystal positioned in the image display area is initially horizontally aligned, and the liquid crystal positioned in the viewing angle control area is initially hybrid-aligned. .

The first and second pixel electrodes may have a lattice shape, respectively, and the first and second common electrodes may have a planar shape or a lattice shape, respectively.

The liquid crystal is a negative type of nematic liquid crystal, the long axis direction of the lattice window of the first pixel electrode and the rubbing direction of the array substrate of the liquid crystal located in the image display area form an angle of 45 to 90 degrees, and the second pixel. The long axis direction of the grating window of the electrode and the rubbing direction of the array substrate of the liquid crystal positioned in the viewing angle adjusting region may be at an angle of 45 to 90 degrees.

The width of the first grating extending along the major axis of the grating window of the first pixel electrode is 1 to 10 μm, the spacing between neighboring first gratings is 1 to 20 μm, and the grating window of the second pixel electrode is The width of the second lattice extending along the long axis of may be 1 ~ 10㎛, the spacing between the adjacent second lattice may be 1 ~ 20㎛.

An R color filter, a G color filter, and a B color filter may be formed in each of the image display regions of the opposing substrate, and the viewing angle adjusting region of the opposing substrate may have a transparent state.

In the viewing angle adjusting region of the counter substrate, a transparent organic thin film may be formed corresponding to a layer on which an R color filter, a G color filter, and a B color filter are formed.

In the present invention, in the pixel for adjusting the viewing angle, not only the degree of tilt of the liquid crystal can be adjusted but also the liquid crystal can be rotated. Therefore, in the case of the narrow viewing angle driving, the transmittance is generated from the front surface, and thus it is possible to have a high transmittance characteristic. Furthermore, in the case of wide viewing angle driving, it is possible to have a high contrast ratio characteristic.

Further, in the present invention, the electrode pattern of the pixel for displaying the video information and the pixel for adjusting the viewing angle can be configured in the same manner. As a result, the manufacturing process can be simplified.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

<First Embodiment>

1 is a plan view schematically illustrating a viewing angle adjusting liquid crystal display device according to a first example of a first embodiment of the present invention.

As shown, in the viewing angle adjusting liquid crystal display according to the first example of the first embodiment of the present invention, the pixel region P composed of the main pixel region MP and the auxiliary pixel region SP is defined. Pixels having such a structure are arranged in a matrix form in a liquid crystal display device.

In the case where the liquid crystal display displays a full color image, the image display unit is composed of, for example, R (red) pixels, G (green) pixels, B (blue) pixels, or R pixels, G pixels, B Pixels and W (white) pixels are used to represent unit images of the full-color image. Here, the pixel illustrated in FIG. 1 corresponds to one pixel constituting the image display unit when displaying a full color image.

The liquid crystal display device according to the first embodiment of the present invention includes an array substrate and an opposing substrate (see AS and OS in FIG. 3) facing each other, and a liquid crystal layer (see LC in FIG. 3) positioned between the two substrates. Include.

In the array substrate, a gate wiring 1 and first and second data wirings 2 and 3 intersecting the gate wiring 1 are formed on an inner surface of a first substrate (see 80 in FIG. 3), which is a lower substrate. In the first embodiment of the present invention, the pixel region P is defined between the first and second data wirings 2 and 3. The gate wiring 1 is sandwiched between the main pixel region MP and the auxiliary pixel region SP.

The first switching element T1 is formed at the intersection of the gate wiring 1 and the first data wiring 2. The second switching element T2 is formed at the intersection of the gate wiring 1 and the second data wiring 3.

As the first and second switching elements T1 and T2, thin film transistors may be used. The first switching element T1 may include a first gate electrode, a first semiconductor layer 51 on the first gate electrode, and a first source and drain electrode 52 spaced apart from each other on the first semiconductor layer 51. , 53). The second switching element T2 may include a second gate electrode, a second semiconductor layer 61 on the second gate electrode, and a second source and drain electrode spaced apart from each other on the second semiconductor layer 61. (62, 63). Here, each of the first and second source electrodes 52 and 62 may be formed to extend from the first and second data wires 2 and 3. As the first and second gate electrodes, a part of the gate wiring 1 may be used.

The first and second common wirings 9 and 10 extend in parallel with the gate wiring 1. For example, the first and second common wirings 9 and 10 are located opposite to each other with the gate wiring 1 interposed therebetween.

In the main pixel area MP, the first common electrode 4 and the first pixel electrode 5 are formed on the first substrate. The first common electrode 4 may be formed in a planar shape, that is, in a plate shape. The first common electrode 4 is connected to the first common line 9 to receive the voltage applied to the first common line 9.

The first pixel electrode 5 is formed on the first common electrode 4 and may have a lattice shape. As such, the first pixel electrode 5 having a lattice shape may include first and second lattice teeth 5a and 5b defining a lattice shape. The first grating 5a extends along the major axis direction of the first grating window LW1, and the second grating 5b extends along the short axis direction of the first grating window LW1. The first pixel electrode 5 is connected to the first drain electrode 53.

A fringe electric field is generated between the first common electrode 4 and the first pixel electrode 5, and thus the liquid crystal of the main pixel is driven to display an image. Such a liquid crystal drive method is called a fringe field switching mode (FFS mode) (hereinafter, referred to as an FFS mode for convenience of description). As such, the main pixel is driven in the FFS mode to display an image.

In the auxiliary pixel area SP, the second common electrode 6 and the second pixel electrode 7 are formed on the first substrate. The second common electrode 6 may be formed in a planar shape, that is, in a plate shape. In contrast, the second common electrode 6 may be formed in a lattice form. The second common electrode 6 is connected to the second common wiring 10 to receive the voltage applied to the second common wiring 10.

The second pixel electrode 7 is formed on the second common electrode 6 and may have a lattice shape. As such, the second pixel electrode 7 having a lattice shape may include third and fourth lattice teeth 7a and 7b defining a lattice shape. The third grating 7a extends along the major axis direction of the second grating window LW2, and the fourth grating 7b extends along the short axis direction of the second grating window LW2. The second pixel electrode 7 is connected to the second drain electrode 63.

As described above, the electrode structure in the array substrate of the auxiliary pixel may have a structure similar to that of the electrode structure in the array substrate of the main pixel, that is, the FFS mode electrode structure.

On the other hand, in the opposing substrate, a third common electrode 8 is formed on the inner surface of the second substrate (see 90 in FIG. 3) which is the upper substrate. The third common electrode 8 is positioned in the auxiliary pixel area SP and is formed in a planar shape, that is, in a plate shape.

Here, as the liquid crystal constituting the liquid crystal layer, a negative type liquid crystal having negative dielectric anisotropy may be used. As the liquid crystal constituting the liquid crystal layer, a nematic liquid crystal may be used. The liquid crystal positioned in the main pixel area MP may be horizontally aligned, and the liquid crystal positioned in the auxiliary pixel area SP may be hybridly aligned. Here, when a hybrid alignment nematic liquid crystal is used in the auxiliary pixel area SP, such a liquid crystal may be referred to as a HAN mode liquid crystal.

Although not shown, an alignment film is formed on each of the array substrate and the counter substrate to align the liquid crystal. Thus, in order to orientate a liquid crystal, a rubbing process advances at the time of manufacture with respect to an oriented film. Here, with respect to the rubbing direction of the array substrate, the rubbing direction R1 of the main pixel and the rubbing direction R2 of the auxiliary pixel are both the same as the vertical direction, that is, the extending direction of the data wirings 2 and 3. This can be done, but is not limited thereto. Meanwhile, for convenience of description, the rubbing direction R1 of the main pixel and the rubbing direction R2 of the auxiliary pixel may be referred to as first and second rubbing directions R1 and R2, respectively.

On the other hand, the lattice direction L1 of the first pixel electrode 5, that is, the major axis direction of the first lattice window LW1 (or the extension direction of the first lattice 5a) is the first rubbing direction R1 and the first. Angle α1 can be achieved. Here, it is preferable that the 1st angle (alpha) 1 has the range of 45-90 degree. On the other hand, it is more preferable that the first angle α1 is approximately 80 degrees.

The lattice direction L2 of the second pixel electrode 7, that is, the major axis direction of the second lattice window LW2 (or the extending direction of the third lattice 7a) is the second rubbing direction R2 and the second. Angle α2 can be achieved. Here, it is preferable that 2nd angle (alpha) 2 has the range of 45-90 degree. On the other hand, in order to more effectively perform the viewing angle adjustment through the auxiliary pixel, it is more preferable that the second angle α2 is approximately 80 degrees. If, due to an error in the rubbing process, the second angle α2 does not have the preferred angle as described above and a misalignment occurs, light leakage may occur from the front side.

A viewing angle adjusting method for a liquid crystal display device having the structure as described above will be described.

When the liquid crystal display device is driven to have a wide viewing angle characteristic, in the main pixel area MP, an image data voltage is applied to the first pixel electrode 5 so that the first pixel electrode 5 and the first common electrode 4 are driven. A fringe electric field is generated between Accordingly, the horizontally aligned liquid crystal positioned in the main pixel area MP rotates according to the fringe electric field, thereby displaying a desired image.

Meanwhile, in the auxiliary pixel area SP for adjusting the viewing angle, a voltage is applied to the second pixel electrode 7 to generate a fringe electric field between the second pixel electrode 7 and the second common electrode 6. . In addition, a vertical electric field is generated between the second pixel electrode 7 and the third common electrode 8 positioned on the opposite substrate. This vertical electric field causes the hybrid oriented liquid crystals to lie down. That is, according to the vertical electric field, the liquid crystal of the auxiliary pixel can be switched from the hybrid alignment state to the horizontal alignment state. Therefore, the liquid crystal of the auxiliary pixel rotates while being affected by the fringe electric field and the vertical electric field. In other words, the liquid crystal of the auxiliary pixel operates like the FFS mode, similarly to the liquid crystal of the main pixel driven in the FFS mode.

By the above operation, light transmission occurs in the front surface, thereby realizing a wide viewing angle characteristic and a high contrast ratio characteristic.

On the other hand, when the liquid crystal display device is driven to have a narrow viewing angle characteristic, in the main pixel area MP, an image data voltage is applied to the first pixel electrode 5 so that the first pixel electrode 5 and the first common pixel are in common. A fringe electric field is generated between the electrodes 4. Accordingly, the liquid crystal positioned in the main pixel area MP rotates according to the fringe electric field, thereby displaying a desired image.

On the other hand, in the auxiliary pixel area SP for adjusting the viewing angle, a fringe electric field is generated between the second pixel electrode 7 and the second common electrode 6. However, no vertical electric field is generated between the second pixel electrode 7 and the third common electrode 8. Accordingly, only the fringe electric field is used to drive the hybrid oriented liquid crystal. In such a case, the liquid crystal of the auxiliary pixel rotates in the hybrid alignment state without lying down. Thus, for example, light leakage is caused in the left and right viewing angle directions.

On the other hand, when the second common electrode 6 of the auxiliary pixel is patterned to have a lattice shape, when a voltage is applied to the second common electrode 6 of the lattice shape with a time difference, the image is expressed in the viewing angle direction. Streaks may occur. Accordingly, an image distortion phenomenon in the viewing angle direction can be generated.

2 is a plan view schematically illustrating a viewing angle adjusting liquid crystal display device according to a second example of the first embodiment of the present invention. The liquid crystal display according to the second example corresponds to a modification of the first example. In the following, descriptions of parts similar to those in the first example can be omitted.

As shown, in the viewing angle adjusting liquid crystal display according to the second example of the first embodiment of the present invention, the first gate wiring 1 and the second gate wiring 16 intersect one data wiring 2. do. The first switching element T1 is formed at the intersection of the first gate line 1 and the data line 2. The second switching element T2 is formed at the intersection of the second gate line 16 and the data line 2.

As described above, in the second example, the first and second switching transistors T1 and T2 are connected to one data line 2 in common, and are connected to different gate lines 1 and 16. That is, the main pixel and the auxiliary pixel are connected to one data line 2 in common, and have a structure connected to different gate lines 1 and 16.

In the auxiliary pixel area SP, a lattice-shaped second pixel electrode 7 and a planar or lattice-shaped second common electrode 6 are formed on the array substrate. In the counter substrate, a third common electrode 8 having a planar shape is formed.

The first common electrode 4 is disposed in parallel with the first gate wiring 1 and connected to the first common wiring 9 spaced apart from each other. The second common electrode 6 is connected in parallel with the second gate line 16 and connected to the second common line 10 spaced apart from each other.

It is preferable that the first angle α1 formed between the first lattice direction L1 and the first rubbing direction R1 of the first pixel electrode 5 has a range of 45 to 90 degrees. More preferably, the first angle α1 is set to approximately 80 degrees.

On the other hand, it is preferable that the second angle? 2 between the second lattice direction L2 and the second rubbing direction R2 of the second pixel electrode 7 has a range of 45 to 90 degrees. More preferably, the second angle α2 is set to approximately 80 degrees.

The viewing angle adjusting method for the liquid crystal display of the second example having the structure as described above is similar to the viewing angle adjusting method for the liquid crystal display of the first example.

When the liquid crystal display device is driven to have a wide viewing angle characteristic, in the main pixel area MP, an image data voltage is applied to the first pixel electrode 5 so that the first pixel electrode 5 and the first common electrode 4 are driven. A fringe electric field is generated between Accordingly, the horizontally aligned liquid crystal positioned in the main pixel area MP rotates according to the fringe electric field, thereby displaying a desired image.

Meanwhile, in the auxiliary pixel area SP for adjusting the viewing angle, a voltage is applied to the second pixel electrode 7 to generate a fringe electric field between the second pixel electrode 7 and the second common electrode 6. . In addition, a vertical electric field is generated between the second pixel electrode 7 and the third common electrode 8 positioned on the opposite substrate. This vertical electric field causes the hybrid oriented liquid crystals to lie down. Here, the liquid crystal of the auxiliary pixel may be switched from the hybrid alignment state to the horizontal alignment state according to the size of the vertical electric field.

Therefore, by the influence of the fringe electric field and the vertical electric field, the liquid crystal of the auxiliary pixel can rotate while being pressed. Here, the liquid crystal of the auxiliary pixel can operate like the FFS mode, similarly to the liquid crystal of the main pixel driven in the FFS mode when the vertical electric field is strongly formed.

As the auxiliary pixel is driven as described above, light is transmitted from the front surface, thereby realizing a wide viewing angle characteristic and a high contrast ratio characteristic.

On the other hand, when the liquid crystal display device is driven to have a narrow viewing angle characteristic, in the main pixel area MP, an image data voltage is applied to the first pixel electrode 5 so that the first pixel electrode 5 and the first common pixel are in common. A fringe electric field is generated between the electrodes 4. Accordingly, the liquid crystal positioned in the main pixel area MP rotates according to the fringe electric field, thereby displaying a desired image.

On the other hand, in the auxiliary pixel area SP for adjusting the viewing angle, a fringe electric field is generated between the second pixel electrode 7 and the second common electrode 6. However, no vertical electric field is generated between the second pixel electrode 7 and the third common electrode 8. Accordingly, only the fringe electric field is used to drive the liquid crystal of the hybrid oriented auxiliary pixel. In such a case, the liquid crystal of the auxiliary pixel rotates in the hybrid alignment state without lying down. Thus, for example, light leakage is caused in the left and right viewing angle directions.

On the other hand, when the second common electrode 6 of the auxiliary pixel is patterned to have a lattice shape, when a voltage is applied to the second common electrode 6 of the lattice shape with a time difference, the image is expressed in the viewing angle direction. Streaks may occur. Accordingly, an image distortion phenomenon in the viewing angle direction can be generated.

As described in the first and second examples described above, in the liquid crystal display device according to the first embodiment of the present invention, one pixel is divided into a main pixel for displaying image information and an auxiliary pixel for adjusting the viewing angle. Will have

On the other hand, in the first embodiment, in the lattice pattern structure of the first pixel electrode 5, the width w1 of the electrode, that is, the first width w1, is to be in the range of 1 to 10 mu m, and the distance between electrodes ( d1) That is, it is preferable to make the 1st distance d1 have a range of 1-20 micrometers. In the lattice pattern structure of the second pixel electrode 7, the width w2 of the electrode, that is, the second width w2, is in the range of 1 to 10 μm, and the inter-electrode distance d2, that is, the second distance. It is preferable to make (d2) have a range of 1-20 micrometers. Here, each of the first and second widths w1 and w2 may correspond to the widths of the first and third gratings 5a and 7a. Each of the first and second distances d1 and d3 has a separation distance (or width of the first grating window LW1) of the first grating bar 5a adjacent to each other, and a third grating bar adjacent to each other ( 7a) may correspond to the separation distance (or the width of the second grating LW2). In this case, in the auxiliary pixel area SP, the vertical electric field can be strongly formed, thereby increasing the twist or tilt of the liquid crystal. Due to this, the viewing angle adjustment can be performed effectively.

3 is a cross-sectional view schematically illustrating a main pixel area and an auxiliary pixel area of a liquid crystal display according to a first exemplary embodiment of the present invention, and are taken along cut lines A-A and B-B of FIG. 1. Here, the upper sectional view A-A and the lower sectional view B-B show the initial alignment of the liquid crystal LM of the main pixel region MP and the liquid crystal LS of the auxiliary pixel region SP, respectively.

As shown, the liquid crystal display includes an array substrate and an opposite substrate AS and OS facing each other, and a liquid crystal layer LC disposed therebetween.

In the main pixel area MP, the first common electrode 4 and the first pixel electrode 5 are formed on the first substrate 80, and an insulating layer 300 is formed between them.

On the other hand, in the auxiliary pixel area SP, the second common electrode 6 and the second pixel electrode 7 are formed on the first substrate 80, and the insulating layer 300 is formed therebetween. . The third common electrode 8 is formed on the second substrate 90.

As the liquid crystal positioned in the liquid crystal layer LC, a negative type liquid crystal may be used. And nematic liquid crystal can be used. Here, the orientation states in the main pixel and the auxiliary pixel are different from each other.

Looking at the cross-sectional view A-A of the main pixel, it can be seen that the liquid crystal LM of the main pixel is initially horizontally aligned. That is, the director of the liquid crystal LM of the main pixel is parallel to the substrate surface. The horizontally aligned liquid crystal 100 is rotated in a horizontal alignment state according to the fringe electric field generated by the first common electrode 4 and the first pixel electrode 5.

On the other hand, looking at the cross-sectional view (B-B) of the auxiliary pixel, it can be seen that the liquid crystal 110 of the auxiliary pixel is initially aligned in a hybrid form. That is, the liquid crystals LS are arranged in such a manner that the tilt angle of the director of the liquid crystal LS to the substrate surface is changed from 0 degrees to 90 degrees along the direction perpendicular to the substrate surface.

In the hybrid-oriented liquid crystal LS as described above, when a vertical electric field is generated, the liquid crystal LS is laid down toward the substrate surface. Here, the degree of lying down of the liquid crystal, that is, the degree of change of tilt, depends on the size of the vertical electric field. On the other hand, the liquid crystal LS rotates according to the fringe electric field. Therefore, by appropriately controlling the vertical electric field and the fringe electric field, it is possible to control the operation of the liquid crystal LS of the auxiliary pixel, that is, the degree of tilt and the degree of rotation. As a result, the auxiliary pixel can perform a function of adjusting the viewing angle and transmittance.

FIG. 4 is a view showing transmittance at a polar angle according to a voltage applied to a third common electrode of an auxiliary pixel region in the viewing angle adjusting liquid crystal display according to the first embodiment of the present invention. In FIG. 4, light leakage when a voltage is applied to the third common electrode (see 8 in FIGS. 1 and 2) at intervals of 2V from 0V and 1V to 9V is shown. Here, increasing the voltage applied to the third common electrode means that the size of the vertical electric field applied to the auxiliary pixel is increased.

When 0V is applied to the third common electrode, light leakage of about 16% is generated near the polar angle of 60 degrees. On the other hand, when a voltage of 9V or more is applied to the third common electrode, the degree of light leakage according to the polar angle is saturated to almost 0%. As such, it can be seen that light leakage at the viewing angle can be adjusted by adjusting the voltage applied to the third common electrode, that is, by adjusting the size of the vertical electric field of the auxiliary pixel.

FIG. 5 is a simulation result showing light leakage generated by adjusting the viewing angle in the viewing angle adjusting liquid crystal display according to the first exemplary embodiment of the present invention.

In this simulation, a liquid crystal display device having a gap of 4 μm, a refractive index of 0.09, a dielectric anisotropy of −4, and a phase delay value of 0.36 μm was used. In addition, liquid crystal displays in which the optical axes of the polarizing plates positioned at the top and the bottom thereof are perpendicular to each other at 0 degrees and 90 degrees, respectively, and the transmittances of the two polarizing plates are 0.353556 are used. Here, the upper and lower polarizers are located on the outer surface of the counter substrate and the array substrate (see OS and AS of FIG. 3), respectively, and are parallel to each other.

FIG. 5A illustrates light leakage in a dark state when the liquid crystal display is driven in the wide viewing angle mode. Here, the maximum light leakage is represented by 0.024806.

FIG. 5B shows light leakage when the liquid crystal display is driven in the narrow viewing angle mode. Here, the maximum light leakage value is 0.159483.

In FIG. 5, the red line, the yellow line, and the blue line represent areas where 70%, 50%, and 30% of light leakage occurs based on the maximum light leakage in the wide viewing angle mode, respectively. In this case, the 70% region corresponds to 0.017364, the 50% region corresponds to 0.012403, and the 30% region corresponds to 0.007442.

In the wide viewing angle mode, an area of 70% will appear at approximately 50 degrees or more. On the other hand, in the narrow viewing angle mode, it can be seen that the viewing angle appears at approximately 15 degrees or more in the region of 70%.

In addition, it can be seen that light leakage in the wide viewing angle mode occurs in a small area in the 45 degree direction of the polarizing plate transmission axis. It can be seen that light leakage in the narrow viewing angle mode causes the phase delay value of the liquid crystal to change in the rubbing direction as the liquid crystal is tilted, thereby generating a large area.

&Lt; Embodiment 2 >

In the second embodiment of the present invention, an image display unit is divided into four pixels, of which three pixels are used, for example, R pixels, G pixels, and B pixels for expressing a unit image. As the other pixel, a viewing angle adjusting pixel is used. The R color filter, the G pixel, and the B pixel respectively form an R color filter, a G color filter, and a B color filter to realize color. On the other hand, the color filter is not formed in the viewing angle control pixel, thereby also functioning as a W pixel for emitting white light.

Hereinafter, a second embodiment of the present invention will be described in detail with reference to the drawings.

6 is a plan view schematically illustrating a viewing angle adjusting liquid crystal display device according to a second embodiment of the present invention. In the following description, description of parts similar to those of the first embodiment can be omitted.

As shown in the figure, in the liquid crystal display device according to the second embodiment, one viewing angle control pixel V having the structure of the auxiliary pixel for adjusting the viewing angle is constructed in the first embodiment. Then, in the first embodiment, three image display pixels R, G, and B having the structure of the main pixel for displaying the image are configured. The four pixels R, G, B, and V constitute one image display unit.

Each of the R pixel, the G pixel, the B pixel, and the V pixel is connected to one corresponding gate wiring line and data wiring lines 1 and 2. In addition, these pixels are connected to one corresponding common wiring 9. In such a case, the number of signal wirings can be reduced compared with the first embodiment in which data wiring or gate wiring is additionally required and common wiring is additionally required. On the other hand, the R pixels, the G pixels, the B pixels, and the V pixels may be configured such that the electrode patterns on the array substrate are the same. That is, these pixels can be configured to have an FFS mode electrode pattern.

In each of the R, G, and B pixels, a first switching element T1, a first common electrode 4, and a first pixel electrode 5 are formed on the array substrate. The first switching element T1 is connected to the corresponding gate line and data line 1 and 2. The first common electrode 4 is connected to the corresponding common wiring 9 and may be formed in a planar shape or a lattice form. The first pixel electrode 5 is formed on the first common electrode 4. The first pixel electrode 5 may be formed in a lattice shape.

For each of the R pixels, the G pixels, and the B pixels, the first angle α1 formed between the first lattice direction L1 of the first pixel electrode 5 and the first rubbing direction R1 of the liquid crystal is 45 to 45 degrees. It is desirable to have a range of 90 degrees. More preferably, the first angle α1 is set to approximately 80 degrees.

On the other hand, in the V pixel, the second switching element T2, the second common electrode 6, and the second pixel electrode 7 are formed on the array substrate. A third common electrode 8 is formed on the counter substrate. The second switching element T2 is connected to the corresponding gate line and data line 1 and 2. The second common electrode 6 is connected to the corresponding common wiring 9 and may be formed in a planar shape or a lattice shape. The second pixel electrode 7 is formed on the second common electrode 6. The second pixel electrode 7 may be formed in a lattice shape.

With respect to such a V pixel, the second lattice direction L2 of the second pixel electrode 7 and the V pixel The second angle α2 formed by the second rubbing direction R2 of the liquid crystal is preferably in the range of 45 to 90 degrees. More preferably, the second angle α2 is set to approximately 80 degrees.

On the other hand, for each of the R pixels, the G pixels, and the B pixels, corresponding R color filters, G color filters, and B color filters can be formed on the counter substrate. Of course, such color filters may be formed on the array substrate.

For the V pixel, in order to have a transparent state, no separate color filter is formed on the counter substrate. For example, for V pixels, a transparent organic thin film can be formed on the counter substrate. Such an organic thin film may be formed on the same layer as the color filter. In the case where the organic thin film is formed on the same layer as the color filter, it is possible to eliminate the step difference of the opposing substrate which may occur by not forming the organic thin film. Of course, a separate organic thin film may not be formed on the same layer as the color filter.

As described above, color filters are formed on R pixels, G pixels, and B pixels to implement red, green, and blue colors. In the case of the V pixel as the viewing angle adjusting pixel, white may be implemented without using a separate color filter, and a halftone may be displayed by varying the voltage. Accordingly, when viewing the screen in the left and right directions, it is possible to prevent the letters or images from being clearly seen. In addition, since transmittance at the front surface is generated, high transmittance characteristics can be exhibited when driving in the narrow viewing angle mode.

Embodiment of the present invention described above is an example of the present invention, it is possible to change freely within the scope included in the spirit of the present invention. Accordingly, the invention includes modifications of the invention within the scope of the appended claims and their equivalents.

1 is a plan view schematically showing a viewing angle adjusting liquid crystal display device according to a first example of a first embodiment of the present invention;

2 is a plan view schematically illustrating a viewing angle adjusting liquid crystal display device according to a second example of the first embodiment of the present invention;

3 is a cross-sectional view schematically showing a main pixel area and an auxiliary pixel area of a liquid crystal display according to a first embodiment of the present invention;

FIG. 4 is a view illustrating transmittance at a polar angle according to a voltage applied to a third common electrode of an auxiliary pixel region in the viewing angle adjusting liquid crystal display according to the first embodiment of the present invention.

FIG. 5 is a view showing a simulation result showing light leakage generated according to the viewing angle control in the viewing angle adjusting liquid crystal display according to the first embodiment of the present invention. FIG.

6 is a plan view schematically showing a viewing angle adjusting liquid crystal display device according to a second embodiment of the present invention;

Description of the Related Art

1: gate wiring 2: first data wiring

3: second data line 4: first common electrode

5: first pixel electrode 6: second common electrode

7 second pixel electrode 8 third common electrode

9: first common wiring 10: second common wiring

T1: first switching element T2: second switching element

L1: first lattice direction L2: second lattice direction

R1: first rubbing direction R2: second rubbing direction

α1: first angle α2: second angle

Claims (12)

In a liquid crystal display device in which a pixel area is divided into a main pixel area and an auxiliary pixel area, A first common electrode formed in the main pixel region of the array substrate, and a first pixel electrode formed on the first common electrode to form a fringe electric field with the first common electrode; A second common electrode formed in the auxiliary pixel region of the array substrate, and a second pixel electrode formed on the second common electrode to form a fringe electric field with the second common electrode; First and second switching elements formed on the array substrate and connected to the first and second pixel electrodes, respectively; A third common electrode formed in the auxiliary pixel region of the opposing substrate and configured to form a vertical electric field with the second pixel electrode; A liquid crystal positioned between the array substrate and the opposite substrate, The liquid crystal positioned in the main pixel region is initially horizontally aligned, and the liquid crystal positioned in the auxiliary pixel region is initially hybrid-oriented. LCD display device. The method of claim 1, The first and second pixel electrodes each have a lattice shape, The first and second common electrodes each have a planar shape or a lattice shape. LCD display device. The method of claim 2, The liquid crystal is a negative type of nematic liquid crystal, The long axis direction of the lattice window of the first pixel electrode and the rubbing direction of the array substrate of the liquid crystal located in the main pixel region form an angle of 45 to 90 degrees. The long axis direction of the lattice window of the second pixel electrode and the rubbing direction of the array substrate of the liquid crystal located in the auxiliary pixel region form an angle of 45 to 90 degrees. LCD display device. The method of claim 2, The width of the first lattice extending along the long axis of the lattice window of the first pixel electrode is 1 ~ 10㎛, the spacing between neighboring first lattice is 1 ~ 20㎛, The width of the second lattice extending along the long axis of the lattice window of the second pixel electrode is 1 ~ 10㎛, the spacing between neighboring second lattice is 1 ~ 20㎛ LCD display device. The method of claim 1, First and second data wires disposed on both sides of the pixel region and connected to the first and second switching transistors, respectively; A gate wiring crossing the first and second data wirings and commonly connected to the first and second switching transistors; Liquid crystal display further comprising. The method of claim 1, A data line disposed on one side of the pixel area and commonly connected to the first and second switching transistors; First and second gate lines intersecting the data lines and connected to the first and second switching transistors, respectively. Liquid crystal display further comprising. In the liquid crystal display device in which the image display unit area is divided into three image display areas for displaying image information and a viewing angle adjustment area for adjusting the viewing angle, A first common electrode formed on each of the image display regions of the array substrate, and a first pixel electrode formed on the first common electrode to form a fringe electric field with the first common electrode; A second common electrode formed in the viewing angle control region of the array substrate, and a second pixel electrode formed on the second common electrode to form a fringe electric field with the second common electrode; First and second switching elements formed on the array substrate and connected to the first and second pixel electrodes, respectively; A third common electrode formed in the viewing angle adjusting region of the opposing substrate and configured to form a vertical electric field with the second pixel electrode; A liquid crystal positioned between the array substrate and the opposite substrate, The liquid crystal positioned in the image display area is initially horizontally aligned, and the liquid crystal positioned in the viewing angle control area is initially hybrid-oriented. LCD display device. The method of claim 7, wherein The first and second pixel electrodes each have a lattice shape, The first and second common electrodes each have a planar shape or a lattice shape. LCD display device. The method of claim 8, The liquid crystal is a negative type of nematic liquid crystal, The long axis direction of the lattice window of the first pixel electrode and the rubbing direction of the array substrate of the liquid crystal positioned in the image display area form an angle of 45 to 90 degrees. The long axis direction of the lattice window of the second pixel electrode and the rubbing direction of the array substrate of the liquid crystal positioned in the viewing angle adjusting region form an angle of 45 to 90 degrees. LCD display device. The method of claim 8, The width of the first lattice extending along the long axis of the lattice window of the first pixel electrode is 1 ~ 10㎛, the spacing between neighboring first lattice is 1 ~ 20㎛, The width of the second lattice extending along the long axis of the lattice window of the second pixel electrode is 1 ~ 10㎛, the spacing between neighboring second lattice is 1 ~ 20㎛ LCD display device. The method of claim 7, wherein An R color filter, a G color filter, and a B color filter are formed in each of the image display regions of the opposing substrate. The viewing angle adjusting region of the opposing substrate has a transparent state LCD display device. The method of claim 11, In the viewing angle adjusting region of the opposing substrate, a transparent organic thin film is formed corresponding to a layer on which an R color filter, a G color filter, and a B color filter are formed. LCD display device.

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