KR101652866B1 - Liquid crystal display device - Google Patents

Liquid crystal display device Download PDF

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KR101652866B1
KR101652866B1 KR1020090095996A KR20090095996A KR101652866B1 KR 101652866 B1 KR101652866 B1 KR 101652866B1 KR 1020090095996 A KR1020090095996 A KR 1020090095996A KR 20090095996 A KR20090095996 A KR 20090095996A KR 101652866 B1 KR101652866 B1 KR 101652866B1
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South Korea
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liquid crystal
pixel
common electrode
formed
viewing angle
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KR1020090095996A
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Korean (ko)
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KR20110038827A (en
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이승희
이준호
김영식
박경호
김진호
임영진
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엘지디스플레이 주식회사
전북대학교 산학협력단
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Abstract

The present invention provides a liquid crystal display device in which a pixel region is divided into a main pixel region and a sub pixel region, the liquid crystal display device comprising: a first common electrode formed in the main pixel region of the array substrate; A first pixel electrode formed on the first common electrode; A second common electrode formed on the auxiliary pixel region of the array substrate; 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 counter substrate and configured to form a vertical electric field with the second pixel electrode; And a liquid crystal positioned between the array substrate and the counter substrate. The liquid crystal located in the main pixel region is initially horizontally aligned, and the liquid crystal located in the auxiliary pixel region is initially hybrid-aligned .

Description

[0001] Liquid crystal display device [0002]

The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device capable of adjusting a viewing angle.

2. Description of the Related Art [0002] As an information-oriented society develops, demands for a display device for displaying an image have increased in various forms. Recently, a liquid crystal display (LCD), a plasma display panel (PDP) Various flat display devices such as an organic light emitting diode (OLED) have been utilized.

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

The liquid crystal display device is an apparatus that displays information by adjusting the amount of light passing through, utilizing the electro-optical characteristics of the liquid crystal and the polarization property of the polarizer.

Generally, a liquid crystal used in a liquid crystal display device has a different refractive index anisotropy in liquid crystal orientation in the front and viewing angle directions. As a result, there is a difference in the phase delay value, so that the displayed image is not completely visible in the viewing angle direction. As described above, 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 the wide viewing angle characteristics can be achieved.

Recently, however, as the use of portable displays has increased, problems have arisen concerning 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 a viewing angle controllability, and various research results have been reported. On the other hand, on the other hand, it is also true that a liquid crystal display device having a wide viewing angle characteristic is required for sharing information of various people.

In accordance with these demands, a method of adding a narrow viewing angle characteristic to a liquid crystal display device having a wide viewing angle characteristic has been studied. In a liquid crystal display device having such characteristics, the viewing angle can be adjusted by dividing one pixel into a main pixel for displaying image information and a sub-pixel for adjusting the viewing angle. As one of such techniques, the electrode pattern of the auxiliary pixel for adjusting the viewing angle is made different from the electrode pattern of the main pixel, and the liquid crystal in the auxiliary pixel which is the viewing angle adjusting region is tilted so that the light leakage in the right- And the like.

However, in such a technique, there is a problem that an additional process is required because the electrode pattern is different between the main pixel and the auxiliary pixel. Further, since only the characteristic that the liquid crystal is tilted is used, the light in the auxiliary pixel region does not come out to the front, which is a problem in terms of the transmittance.

As described above, the conventional viewing angle adjusting liquid crystal display device 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 capable of improving the manufacturing process and optical characteristics.

According to an aspect of the present invention, there is provided a liquid crystal display device comprising a pixel region divided into a main pixel region and a sub pixel region, the liquid crystal display comprising: a first common electrode formed on the main pixel region of the array substrate; A first pixel electrode formed on the first common electrode to form a common electrode and a fringe electric field; A second common electrode formed on the auxiliary pixel region of the array substrate; 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 counter substrate and configured to form a vertical electric field with the second pixel electrode; And a liquid crystal positioned between the array substrate and the counter substrate. The liquid crystal located in the main pixel region is initially horizontally aligned, and the liquid crystal located in the auxiliary pixel region is initially hybrid-aligned .

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

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

Wherein a width of the first lattice pattern extending along the major axis of the lattice window of the first pixel electrode is 1 to 10 mu m and a spacing distance between neighboring first lattice patterns is 1 to 20 mu m, The width of the second lattice extending along the long axis of the first lattice constant is 1 to 10 mu m and the spacing distance between the neighboring second lattice constant may be 1 to 20 mu m.

First and second data lines arranged on both sides of the pixel region and connected to the first and second switching transistors, respectively; And a gate wiring intersecting the first and second data wirings and commonly connected to the first and second switching transistors.

A data line disposed at one side of the pixel region and connected in common to the first and second switching transistors; And first and second gate wirings crossing the data wirings and connected to the first and second switching transistors, respectively.

According to another aspect of the present invention, there is provided a liquid crystal display device in which an image display unit area is divided into three image display areas for displaying image information and a viewing angle control area for adjusting a viewing angle, 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 on the viewing angle control region of the array substrate; 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 control region of the counter substrate and configured to form a vertical electric field with the second pixel electrode; And a liquid crystal positioned between the array substrate and the counter substrate. The liquid crystal positioned in the image display region is initially horizontally aligned, and the liquid crystal positioned in the viewing angle control region is initially hybrid-aligned .

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

Wherein the liquid crystal is a nematic liquid crystal of negative type and the long axis direction of the lattice window of the first pixel electrode and the rubbing direction of the liquid crystal array substrate located in the image display region form an angle of 45 to 90 degrees, The longitudinal axis direction of the lattice window of the electrode and the rubbing direction of the liquid crystal array substrate located in the viewing angle control region can be set at an angle of 45 to 90 degrees.

Wherein a width of the first lattice pattern extending along the major axis of the lattice window of the first pixel electrode is 1 to 10 mu m and a spacing distance between neighboring first lattice patterns is 1 to 20 mu m, The width of the second lattice extending along the long axis of the first lattice constant is 1 to 10 mu m and the spacing distance between the neighboring second lattice constant may be 1 to 20 mu m.

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

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

In the present invention, not only the degree of tilt of the liquid crystal can be controlled but also the liquid crystal can be rotated in a pixel for adjusting the viewing angle. Therefore, when narrow-angle driving is performed, transmittance is generated at the front surface, and high transmittance characteristics can be obtained. Furthermore, in the case of driving the wide viewing angle, it becomes possible to have high contrast ratio characteristics.

Further, in the present invention, the pixel for displaying the image information and the electrode pattern for the pixel for adjusting the viewing angle can be made the same. Thus, the manufacturing process can be simplified.

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

≪ Embodiment 1 >

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

As shown in the drawing, the viewing angle control liquid crystal display according to the first example of the first embodiment of the present invention defines a pixel region P composed of a main pixel region MP and a sub pixel region SP. 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 device displays a full color image, the image display unit may be composed of, for example, R (red) pixel, G (green) Pixel, and W (white) pixel to represent a unit image of the entire color image. Here, the pixel shown in Fig. 1 corresponds to one pixel constituting an image display unit when a full color image is displayed.

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

A gate wiring 1 and first and second data wirings 2 and 3 intersecting the gate wiring 1 are formed on the inner surface of a first substrate (see 80 in Fig. 3) as a lower substrate. In the first embodiment of the present invention, the pixel region P is defined between the first and second data lines 2 and 3. The main pixel region MP and the auxiliary pixel region SP are separated by the gate wiring 1 therebetween.

A first switching element T1 is formed at an intersection of the gate wiring 1 and the first data wiring 2. A 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, a thin film transistor may be used. The first switching element T1 includes a first gate electrode, a first semiconductor layer 51 over the first gate electrode, and first and second source and drain electrodes 52 and 52 spaced from each other above the first semiconductor layer 51. [ , 53). The second switching element T2 includes a second gate electrode, a second semiconductor layer 61 above the second gate electrode, and a second source and drain electrode (62, 63). Here, each of the first and second source electrodes 52, 62 may be formed extending from the first and second data lines 2, 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 parallel to the gate wiring 1 and spaced apart from each other. For example, the first and second common wirings 9 and 10 are positioned opposite to each other with the gate wiring 1 therebetween.

In the main pixel region MP, a first common electrode 4 and a first pixel electrode 5 are formed on a first substrate. The first common electrode 4 may be formed in a planar shape, i.e., a plate shape. The first common electrode 4 is connected to the first common wiring 9 and receives the voltage applied to the first common wiring 9.

The first pixel electrode 5 is formed on the first common electrode 4 and may have a lattice shape. The first pixel electrode 5 having such a lattice shape may include first and second lattice suicides 5a and 5b defining a lattice shape. The first grids 5a extend along the major axis direction of the first grating LW1 and the second grids 5b extend along the minor axis direction of the first grids 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 so that the liquid crystal of the main pixel is driven to display an image. Such a liquid crystal driving method is called a fringe field switching mode (FFS mode) (hereinafter referred to as an FFS mode for convenience of explanation). As described above, the main pixel is driven in the FFS mode to display an image.

In the auxiliary pixel region SP, a second common electrode 6 and a second pixel electrode 7 are formed on a first substrate. The second common electrode 6 may be formed in a planar shape, i.e., a plate shape. On the other hand, 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 and receives 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. The second pixel electrode 7 having such a lattice shape may include third and fourth lattice suicides 7a and 7b defining a lattice shape. The third grids 7a extend along the major axis direction of the second grating LW2 and the fourth grids 7b extend along the minor axis direction of the second grids LW2. The second pixel electrode 7 is connected to the second drain electrode 63.

As described above, the electrode structure on the array substrate of the auxiliary pixel may have the same structure as the electrode structure on the array substrate of the main pixel, that is, the FFS mode electrode structure.

On the other hand, on the opposing substrate, a third common electrode 8 is formed on the inner surface of a second substrate (refer to 90 in Fig. 3) which is an upper substrate. The third common electrode 8 is located in the auxiliary pixel region SP and is formed in a planar shape, i.e., a plate shape.

Here, as the liquid crystal constituting the liquid crystal layer, a negative type liquid crystal having a negative dielectric anisotropy can be used. As the liquid crystal constituting the liquid crystal layer, a nematic liquid crystal may be used. The liquid crystal located in the main pixel region MP can be aligned horizontally and the liquid crystal located in the auxiliary pixel region SP can be aligned in a hybrid manner. Here, when a hybrid alignment nematic liquid crystal is used for the auxiliary pixel region 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. As described above, in order to align the liquid crystal, the rubbing process is carried out at the time of manufacturing for the alignment film. Here, regarding 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 the same as the extending directions of the data wirings 2 and 3, for example, But is not limited thereto. On the other hand, for convenience of explanation, the rubbing direction R1 of the main pixel and the rubbing direction R2 of the auxiliary pixel can be referred to as the first and second rubbing directions R1 and R2, respectively.

On the other hand, the grating direction L1 of the first pixel electrode 5, that is, the longitudinal direction of the first lattice window LW1 (or the extending direction of the first grating slit 5a) The angle? 1 can be obtained. Here, it is preferable that the first angle alpha 1 has a range of 45 to 90 degrees. On the other hand, it is more preferable that the first angle? 1 is approximately 80 degrees.

The grating direction L2 of the second pixel electrode 7, that is, the major axis direction of the second grating window LW2 (or the extending direction of the third grating slit 7a) is the second rubbing direction R2, The angle? 2 can be obtained. Here, the second angle alpha 2 preferably has a range of 45 to 90 degrees. On the other hand, in order to more effectively control the viewing angle through the auxiliary pixels, it is more preferable that the second angle alpha 2 be approximately 80 degrees. If the second angle [alpha] 2 does not have such a preferable angle due to an error in the rubbing process and a shift occurs, light leakage may occur at the front surface.

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

The image data voltage is applied to the first pixel electrode 5 in the main pixel region MP so that the first pixel electrode 5 and the first common electrode 4 A fringe electric field is generated. Accordingly, the horizontally aligned liquid crystal located in the main pixel region MP rotates in accordance with the fringe electric field to display a desired image.

On the other hand, in the auxiliary pixel region SP for adjusting the viewing angle, a voltage is applied to the second pixel electrode 7, and a fringe electric field is generated between the second pixel electrode 7 and the second common electrode 6 . A vertical electric field is generated between the second pixel electrode 7 and the third common electrode 8 located on the counter substrate. Such a vertical electric field causes the hybrid aligned liquid crystal 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, due to the influence of the fringe electric field and the vertical electric field, the liquid crystal of the auxiliary pixel is rotated while being pressed. In other words, the liquid crystal of the auxiliary pixel operates like the FFS mode, similar to the liquid crystal of the main pixel driven in the FFS mode.

By the above-described operation, light is transmitted through the front surface, and a wide viewing angle characteristic and a high contrast ratio characteristic can be realized.

On the other hand, when the liquid crystal display device is driven to have a narrow viewing angle characteristic, in the main pixel region MP, the video data voltage is applied to the first pixel electrode 5, A fringe electric field is generated between the electrodes (4). Accordingly, the liquid crystal located in the main pixel region MP rotates in accordance with the fringe electric field to display a desired image.

On the other hand, in the auxiliary pixel region 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, a vertical electric field is not generated between the second pixel electrode 7 and the third common electrode 8. Thereby, only the fringe electric field is used to drive the hybrid aligned liquid crystal. In such a case, the liquid crystal of the auxiliary pixel is rotated in the hybrid alignment state without being laid down. Thus, for example, light leakage occurs in the right and left viewing angle directions.

On the other hand, when the second common electrode 6 of the auxiliary pixel is patterned so as to have a lattice shape, if a voltage is applied to the second common electrode 6 in a lattice form with a time difference, Stripes may occur. This can cause image distortion in the viewing angle direction.

2 is a plan view schematically showing a viewing angle adjusting liquid crystal display according to a second example of the first embodiment of the present invention. The liquid crystal display device according to the second example corresponds to the modification example of the first example described above. In the following, description of the same components as those in the first example can be omitted.

As shown in the drawing, in the viewing angle-controlled liquid crystal display device 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 with one data wiring 2 do. A first switching device T1 is formed at the intersection of the first gate wiring 1 and the data wiring 2. [ A second switching element T2 is formed at an intersection of the second gate wiring 16 and the data wiring 2.

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

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

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

It is preferable that the first angle? 1 formed by the first lattice direction L1 of the first pixel electrode 5 and the first rubbing direction R1 has a range of 45 to 90 degrees. Here, it is more preferable that the first angle alpha 1 is approximately 80 degrees.

On the other hand, it is preferable that the second angle? 2 formed by the second grating direction L2 of the second pixel electrode 7 and the second rubbing direction R2 is in the range of 45 to 90 degrees. Here, it is more preferable that the second angle alpha 2 is approximately 80 degrees.

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

The image data voltage is applied to the first pixel electrode 5 in the main pixel region MP so that the first pixel electrode 5 and the first common electrode 4 A fringe electric field is generated. Accordingly, the horizontally aligned liquid crystal located in the main pixel region MP rotates in accordance with the fringe electric field to display a desired image.

On the other hand, in the auxiliary pixel region SP for adjusting the viewing angle, a voltage is applied to the second pixel electrode 7, and a fringe electric field is generated between the second pixel electrode 7 and the second common electrode 6 . A vertical electric field is generated between the second pixel electrode 7 and the third common electrode 8 located on the counter substrate. Such a vertical electric field causes the hybrid aligned liquid crystal to lie down. Here, the liquid crystal of the auxiliary pixel can be switched from the hybrid alignment state to the horizontally aligned state depending on the magnitude of the vertical electric field.

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

As described above, by driving the auxiliary pixel, light is transmitted through 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 region MP, the video data voltage is applied to the first pixel electrode 5, A fringe electric field is generated between the electrodes (4). Accordingly, the liquid crystal located in the main pixel region MP rotates in accordance with the fringe electric field to display a desired image.

On the other hand, in the auxiliary pixel region 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, a vertical electric field is not generated between the second pixel electrode 7 and the third common electrode 8. Thus, only the fringe electric field is used to drive the liquid crystal of the hybrid-aligned auxiliary pixel. In such a case, the liquid crystal of the auxiliary pixel is rotated in the hybrid alignment state without being laid down. Thus, for example, light leakage occurs in the right and left viewing angle directions.

On the other hand, when the second common electrode 6 of the auxiliary pixel is patterned so as to have a lattice shape, if a voltage is applied to the second common electrode 6 in a lattice form with a time difference, Stripes may occur. This can cause image distortion in the viewing angle direction.

As described in the first and second examples, 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 a sub-pixel for adjusting a viewing angle .

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 in the range of 1 to 10 mu m, d1), that is, the first distance d1 preferably ranges from 1 to 20 mu m. In the lattice pattern structure of the second pixel electrode 7, the width w2 of the electrode, that is, the second width w2 may be in the range of 1 to 10 mu m, and the interelectrode distance d2, (d2) is preferably in the range of 1 to 20 mu m. Here, each of the first and second widths w1 and w2 may correspond to the widths of the first and third giblets 5a and 7a. Each of the first and second distances d1 and d3 is set so that the distance between the neighboring first divide-by suicide 5a (or the width of the first lattice window LW1) and the neighboring third divide- 7a (or the width of the second lattice window LW2). In such a case, the vertical electric field can be strongly formed in the auxiliary pixel region SP, thereby increasing the torsional or tilt change of the liquid crystal. Thereby, the viewing angle adjustment can be effectively performed.

3 is a cross-sectional view schematically showing the main pixel region and the auxiliary pixel region of the liquid crystal display device according to the first embodiment of the present invention, and is a cross-sectional view along the cutting lines A-A and B-B in Fig. A cross-sectional view (A-A) of the upper part and a cross-sectional view (B-B) of the lower part respectively show the initial alignment state of the liquid crystal (LS) of the liquid crystal (LM) and the auxiliary pixel area (SP) of the main pixel area (MP).

As shown in the figure, the liquid crystal display device includes an array substrate and an opposing substrate AS and OS facing each other and a liquid crystal layer LC positioned therebetween.

In the main pixel region MP, a first common electrode 4 and a first pixel electrode 5 are formed on a first substrate 80, and an insulating layer 300 is formed therebetween.

A second common electrode 6 and a second pixel electrode 7 are formed on the first substrate 80 in the auxiliary pixel region SP and an insulating layer 300 is formed between the second common electrode 6 and the second pixel electrode 7 . A third common electrode 8 is formed on the second substrate 90.

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

A cross-sectional view (A-A) of the main pixel shows 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 becomes parallel to the substrate surface. The liquid crystal 100 horizontally aligned in this way is rotated in the 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, in 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 oriented in a hybrid form. That is, the liquid crystal LS is arranged so that the tilt angle formed by the director of the liquid crystal LS with the substrate surface changes from 0 degrees to 90 degrees along the direction perpendicular to the substrate surface.

In the liquid crystal LS thus hybridized, when the vertical electric field is generated, the liquid crystal LS is laid down toward the substrate surface. Here, the degree of the liquid crystal lying down, i.e., the degree of change of the tilt depends on the magnitude of the vertical electric field. On the other hand, according to the fringe electric field, the liquid crystal LS is rotated. Accordingly, by controlling the vertical electric field and the fringe electric field appropriately, it is possible to control the operation (tilt degree and degree of rotation) of the liquid crystal (LS) of the auxiliary pixel. Thus, the auxiliary pixel can perform the function of adjusting the viewing angle and the transmittance.

4 is a graph showing transmittance at a polar angle according to a voltage applied to the third common electrode of the auxiliary pixel region in the viewing angle adjusting liquid crystal display device according to the first embodiment of the present invention. FIG. 4 shows light leakage in the case where a voltage is applied at 0 V and an interval of 2 V from 1 V to 9 V on the third common electrode (refer to 8 in FIGS. 1 and 2). Here, the increase in the voltage applied to the third common electrode means that the magnitude of the vertical electric field applied to the auxiliary pixel increases.

When 0 V is applied to the third common electrode, light leakage of about 16% occurs at around 60 degrees of polar angle. On the other hand, when voltage of 9 V or more is applied to the third common electrode, the degree of light leakage according to the polar angle is saturated to nearly 0%. As described above, it can be seen that the light leakage in the viewing angle can be controlled by controlling the voltage applied to the third common electrode, that is, by adjusting the vertical electric field of the auxiliary pixel.

FIG. 5 is a simulation result showing light gaps occurring according to the viewing angle control in the viewing angle-adjusting liquid crystal display device according to the first embodiment of the present invention.

In this simulation, a liquid crystal display device having a liquid crystal cell gap of 4 mu m, a liquid crystal refractive index of 0.09, a dielectric anisotropy of -4 and a phase delay of 0.36 mu m was used. Furthermore, the optical axes of the polarizers located at the upper and lower sides are perpendicular to each other at 0 degree and 90 degrees, respectively, and a liquid crystal display device having a transmittance of 0.353556 for two polarizers is used. Here, the upper and lower polarizers are on the outer surface of the counter substrate and the array substrate (see OS and AS in Fig. 3), respectively, and are parallel to each other.

Fig. 5 (A) shows a light state of dark state when the liquid crystal display device is driven in the wide viewing angle mode. Here, the maximum light leakage is numerically expressed as 0.024806.

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

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

In the wide viewing angle mode, a region of 70% appears at a viewing angle of about 50 degrees or more. In contrast, in the narrow viewing angle mode, it can be seen that the viewing angle of 70% appears at a viewing angle of about 15 degrees or more.

It can be seen that the light leakage in the wide viewing angle mode occurs in a small area in the direction of 45 degrees of the transmission axis of the polarizing plate. It can be seen that the light leakage in the narrow viewing angle mode changes as the liquid crystal phase tilts in the rubbing direction as the liquid crystal is tilted, resulting in a large area.

≪ Embodiment 2 >

In the second embodiment of the present invention, the image display unit is divided into four pixels, and three R, G, and B pixels for representing a unit image, for example, are used as the three pixels. As the remaining one pixel, a viewing angle controlling pixel is used. An R color filter, a G color filter, and a B color filter are formed in the R pixel, the G pixel, and the B pixel, respectively, to realize color. On the other hand, the color filter is not formed in the viewing angle control pixel, and accordingly, the function of the W pixel that emits white light is also performed.

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

6 is a plan view schematically showing a viewing angle adjusting liquid crystal display according to a second embodiment of the present invention. In the following description, the same description as in the first embodiment can be omitted.

As shown in the drawing, the liquid crystal display device according to the second embodiment constitutes one viewing angle adjusting pixel V having the structure of the auxiliary pixel for adjusting the viewing angle in the first embodiment. In the first embodiment, three image display pixels (R, G, B) having a structure of a main pixel for displaying an image are formed. 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 a corresponding one of the gate wirings and the data wirings 1 and 2. Further, these pixels are connected to one common wiring 9 corresponding thereto. In such a case, the number of signal wirings can be reduced as compared with the first embodiment in which a data wiring or a gate wiring is additionally required and a common wiring is additionally required. On the other hand, the R pixel, the G pixel, the B pixel, and the V pixel can be configured so that the electrode pattern on the array substrate is the same. That is, these pixels can be configured to have an FFS mode electrode pattern.

A first switching element T1, a first common electrode 4, and a first pixel electrode 5 are formed on an array substrate in each of R pixel, G pixel, and B pixel. The first switching element T1 is connected to the corresponding gate wiring and data wiring 1, 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 shape. The first pixel electrode 5 is formed on the first common electrode 4. The first pixel electrode 5 may be formed in a lattice pattern.

The first angle? 1 formed by 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 nm for each of the R pixel, G pixel, and B pixel, It is preferable to have a range of 90 degrees. Here, it is more preferable that the first angle alpha 1 is approximately 80 degrees.

On the other hand, in the V pixel, a second switching element T2, a second common electrode 6, and a second pixel electrode 7 are formed on the array substrate. Then, a third common electrode 8 is formed on the counter substrate. The second switching element T2 is connected to the corresponding gate wiring and data wiring 1, 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 the V pixel, the second grating direction L2 of the second pixel electrode 7 and the It is preferable that the second angle alpha 2 formed by the second rubbing direction R2 of the liquid crystal has a range of 45 to 90 degrees. Here, it is more preferable that the second angle alpha 2 is approximately 80 degrees.

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

As for the V pixel, in order to have a transparent state, a separate color filter is not formed on the counter substrate. For example, for the V pixel, a transparent organic thin film can be formed on the counter substrate. Such an organic thin film can be formed in 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 of the counter substrate which can occur by not forming the organic thin film. Needless to say, a separate organic thin film may not be formed on the same layer as the color filter.

As described above, color filters are formed in R pixels, G pixels, and B pixels to implement red, green, and blue. In the case of the V pixel which is the viewing angle control pixel, white can be implemented without using a separate color filter, and the intermediate gradation can be displayed by varying the voltage. Accordingly, when the screen is viewed in the left and right directions, characters and images can be prevented from being clearly seen. Further, since the transmittance at the front surface occurs, a high transmittance characteristic can be exhibited at the time of driving in the narrow viewing angle mode.

The embodiment of the present invention described above is an example of the present invention, and variations are possible within the spirit of the present invention. Accordingly, the invention includes modifications of the invention within the scope of the appended claims and equivalents thereof.

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

2 is a plan view schematically showing 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 region and an auxiliary pixel region of a liquid crystal display device according to a first embodiment of the present invention.

4 is a graph showing transmittance at a polar angle according to a voltage applied to a third common electrode of a sub pixel region in a viewing angle controlling liquid crystal display according to a first embodiment of the present invention.

5 is a view showing a simulation result showing light gaps occurring due to a viewing angle control in a viewing angle adjusting liquid crystal display device according to a first embodiment of the present invention.

6 is a plan view schematically showing a viewing angle adjusting liquid crystal display 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 grating direction L2: second grating direction

R1: first rubbing direction R2: second rubbing direction

alpha 1: first angle alpha 2: second angle

Claims (12)

  1. Wherein each pixel region is divided into a main pixel region and a sub pixel region,
    A first common electrode formed on the main pixel region of the array substrate; 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 on the auxiliary pixel region of the array substrate; and a second common electrode formed on the second common electrode to form a fringe electric field in the same direction as the fringe electric field formed on the second common electrode and the main pixel region, A pixel 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 counter substrate and configured to form a vertical electric field with the second pixel electrode;
    And a negative type nematic liquid crystal positioned between the array substrate and the counter substrate,
    The liquid crystal located in the main pixel region is initially horizontally oriented, the liquid crystal located in the auxiliary pixel region is initially hybrid-
    The vertical electric field is formed between the second pixel electrode and the third common electrode when the wide viewing angle is driven and the vertical electric field is not formed when the narrow viewing angle is driven
    Liquid crystal display device.
  2. The method according to claim 1,
    Wherein the first and second pixel electrodes have a lattice shape,
    Wherein the first and second common electrodes have a planar shape or a lattice shape, respectively,
    Liquid crystal display device.
  3. 3. The method of claim 2,
    The major axis direction of the lattice window of the first pixel electrode and the rubbing direction of the liquid crystal array substrate 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 liquid crystal array substrate located in the auxiliary pixel region are 45 to 90 degrees
    Liquid crystal display device.
  4. 3. The method of claim 2,
    Wherein the width of the first lattice extending along the long axis of the lattice window of the first pixel electrode is 1 to 10 占 퐉 and the spacing distance between the neighboring first lattice constant is 1 to 20 占 퐉,
    Wherein a width of the second lattice extending along the long axis of the lattice window of the second pixel electrode is 1 to 10 mu m and a spacing distance between adjacent second lattice gates is 1 to 20 mu m
    Liquid crystal display device.
  5. The method according to claim 1,
    First and second data lines arranged on both sides of the pixel region and connected to the first and second switching elements, respectively;
    A gate wiring which intersects with the first and second data wirings and is commonly connected to the first and second switching elements,
    The liquid crystal display device further comprising:
  6. The method according to claim 1,
    A data line disposed on one side of the pixel region and commonly connected to the first and second switching elements;
    First and second gate wirings crossing the data lines and connected to the first and second switching elements, respectively,
    The liquid crystal display device further comprising:
  7. 1. A liquid crystal display (LCD) device comprising: an image display unit area divided into three image display areas for displaying image information; and a viewing angle control area for adjusting a viewing angle,
    A first common electrode formed on each of the image display regions of the array substrate; a first pixel electrode formed on the first common electrode to form a fringe electric field with the first common electrode;
    And a second common electrode formed on the second common electrode so as to form a fringe electric field in the same direction as the fringe electric field formed on the second common electrode and the image display region, A pixel 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 control region of the counter substrate and configured to form a vertical electric field with the second pixel electrode;
    And a negative type nematic liquid crystal positioned between the array substrate and the counter substrate,
    The liquid crystal located in the image display region is initially horizontally oriented, the liquid crystal located in the viewing angle control region is initially hybrid-
    The vertical electric field is formed between the second pixel electrode and the third common electrode when the wide viewing angle is driven and the vertical electric field is not formed when the narrow viewing angle is driven
    Liquid crystal display device.
  8. 8. The method of claim 7,
    Wherein the first and second pixel electrodes have a lattice shape,
    Wherein the first and second common electrodes have a planar shape or a lattice shape, respectively,
    Liquid crystal display device.
  9. 9. The method of claim 8,
    The long axis direction of the lattice window of the first pixel electrode and the rubbing direction of the liquid crystal array substrate located in the image display region form an angle of 45 to 90 degrees,
    Wherein the long axis direction of the lattice window of the second pixel electrode and the rubbing direction of the liquid crystal array substrate located in the viewing angle control region form an angle of 45 to 90 degrees
    Liquid crystal display device.
  10. 9. The method of claim 8,
    Wherein the width of the first lattice extending along the long axis of the lattice window of the first pixel electrode is 1 to 10 占 퐉 and the spacing distance between the neighboring first lattice constant is 1 to 20 占 퐉,
    Wherein a width of the second lattice extending along the long axis of the lattice window of the second pixel electrode is 1 to 10 mu m and a spacing distance between adjacent second lattice gates is 1 to 20 mu m
    Liquid crystal display device.
  11. 8. The method of claim 7,
    An R color filter, a G color filter, and a B color filter are formed in each of the image display regions of the counter substrate,
    Wherein the viewing angle control region of the counter substrate has a transparent state
    Liquid crystal display device.
  12. 12. The method of claim 11,
    In the viewing angle control region of the counter substrate, a transparent organic thin film is formed in correspondence with the layer on which the R color filter, the G color filter, and the B color filter are formed
    Liquid crystal display device.
KR1020090095996A 2009-10-09 2009-10-09 Liquid crystal display device KR101652866B1 (en)

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