KR101331898B1 - In plane switching mode liquid crystal display device - Google Patents

Abstract

In the horizontal field type liquid crystal display device of the present invention, the twist angle and tilt of the liquid crystal molecules are reduced by changing the inclination angle of the data line and the outermost common electrode to improve the viewing angle crosstalk. A plurality of gate lines arranged in one direction on the first substrate; A plurality of data lines arranged to be inclined at a first angle with respect to the vertical direction to the one direction to define a plurality of pixel areas together with the gate lines; A switching element formed at an intersection of the gate line and the data line; A common electrode formed in the pixel area, the common electrode including a first common electrode formed in a center area of the pixel area and a second common electrode formed in an area adjacent to the data line; A pixel electrode formed in the pixel region and alternately arranged with the common electrode to generate a horizontal electric field; And a second substrate bonded to the first substrate, wherein one side of the second common electrode facing the data line is arranged to be inclined at the first angle while the other side of the second common electrode is inclined. Is arranged to be inclined at a second angle with respect to the vertical direction to the one direction, the first common electrode is arranged to be inclined at the second angle, the first angle is gentler than the second angle It is characterized by.

Horizontal electric field method, data line, common electrode, viewing angle crosstalk

Description

Horizontal electric field liquid crystal display device {IN PLANE SWITCHING MODE LIQUID CRYSTAL DISPLAY DEVICE}

1 is a plan view schematically illustrating a portion of an array substrate of a general horizontal field type liquid crystal display device;

2 is a cross-sectional view schematically illustrating a structure of a general horizontal field type liquid crystal display device.

3 is a plan view schematically illustrating a portion of an array substrate of a horizontal field type liquid crystal display device according to a first embodiment of the present invention;

4 is a cross-sectional view schematically showing the structure of a horizontal field type liquid crystal display device according to a first embodiment of the present invention.

FIG. 5 is an exemplary view schematically showing a slope of a data line and an outermost common electrode in the horizontal field type liquid crystal display device of the first embodiment shown in FIG.

6 is an exemplary view schematically illustrating a viewing angle compensation principle in a horizontal field type liquid crystal display device according to the present invention.

7 is a plan view schematically illustrating a portion of an array substrate of a horizontal field type liquid crystal display device according to a second exemplary embodiment of the present invention.

FIG. 8 is an exemplary view schematically showing a slope of a data line and an outermost common electrode in the horizontal field type liquid crystal display device of the second embodiment shown in FIG.

DESCRIPTION OF REFERENCE NUMERALS

8,108,108 ', 208,208': Common electrode 8l, 108l, 108l ', 208l, 208l': Common line

16,116,216: Gate line 17,117,217: Data line

18,118,218: pixel electrode 21,121,221: gate electrode

22,122,222 Source electrodes 23,123,223 Drain electrodes

118l, 118l ', 218l, 218l': Pixel electrode connection line

The present invention relates to a horizontal field type liquid crystal display device, and more particularly, to a horizontal field type liquid crystal display device in which the twist and tilt of liquid crystal molecules between the data line and the outermost common electrode are alleviated to improve viewing angle crosstalk. will be.

Recently, interest in information display has increased, and a demand for using portable information media has increased, and a light-weight flat panel display (FPD) that replaces a cathode ray tube (CRT) And research and commercialization are being carried out. Particularly, among such flat panel display devices, a liquid crystal display (LCD) is an apparatus for displaying an image using the optical anisotropy of a liquid crystal, and is excellent in resolution, color display and picture quality and is actively applied to a notebook or a desktop monitor have.

The liquid crystal display comprises a color filter substrate as a first substrate, an array substrate as a second substrate, and a liquid crystal layer formed between the color filter substrate and the array substrate.

At this time, the color filter substrate includes a color filter composed of a plurality of sub-color filters implementing colors of red (R), green (G), and blue (B) A black matrix for isolating light passing through the liquid crystal layer, and a transparent common electrode for applying a voltage to the liquid crystal layer.

The array substrate may include a plurality of gate lines and data lines arranged vertically and horizontally to define a plurality of pixel regions, thin film transistors (TFTs), which are switching elements formed at intersections of the gate lines and data lines, and the The pixel electrode is formed on the pixel region.

The color filter substrate and the array substrate are adhered to each other so as to face each other with a sealant formed on the outer periphery of the image display area to constitute a liquid crystal display panel, And a joining key formed on the array substrate.

In this case, the above-described liquid crystal display device is a twisted nematic (TN) type liquid crystal display device in which nematic liquid crystal molecules are driven in a direction perpendicular to the substrate. The liquid crystal display device of the above- As shown in Fig. This is due to the refractive anisotropy of the liquid crystal molecules because the liquid crystal molecules oriented horizontally with the substrate are oriented almost perpendicular to the substrate when a voltage is applied to the liquid crystal display panel.

Accordingly, there is a horizontal field type (IPS) type liquid crystal display device in which the liquid crystal molecules are driven in a horizontal direction with respect to the substrate to improve the viewing angle to 170 degrees or more. This will be described in detail.

FIG. 1 is a plan view schematically illustrating a part of an array substrate of a general horizontal field type liquid crystal display device. In an actual liquid crystal display device, N gate lines and M data lines cross each other to provide MxN pixels, but the description is simplified. For the sake of illustration, one pixel is shown.

FIG. 2 is an exemplary view illustrating a cross section taken along line II ′ of the array substrate illustrated in FIG. 1, and illustrates the array substrate illustrated in FIG. 1 and the color filter substrate bonded together corresponding to the array substrate. .

1 and 2, a gate line 16 and a data line 17 are formed on the transparent array substrate 10 to be arranged on the array substrate 10 vertically and horizontally to define a pixel area. The thin film transistor T, which is a switching element, is formed at the intersection of the gate line 16 and the data line 17.

In this case, the thin film transistor T may include a pixel electrode 18 through a gate electrode 21 connected to the gate line 16, a source electrode 22 connected to the data line 17, and a pixel electrode line 18l. It is composed of a drain electrode 23 connected to. In addition, the thin film transistor is connected to the source electrode by the first insulating film 15a for insulating the gate electrode 21 and the source / drain electrodes 22 and 23 and the gate voltage supplied to the gate electrode 21. And an active pattern 24 for forming a conductive channel between the 22 and the drain electrode 23.

For reference, reference numeral 25 denotes an ohmic contact layer for ohmic contact between the source / drain region of the active pattern 24 and the source / drain electrodes 22 and 23.

At this time, the common line 8l and the storage electrode 18s are arranged in a direction parallel to the gate line 16 in the pixel region, and a horizontal electric field 90 is generated in the pixel region to form the liquid crystal molecules 30. The plurality of common electrodes 8 and the pixel electrodes 18 for switching) are arranged in substantially the same direction as the data line 17.

The plurality of common electrodes 8 are formed of the same conductive material as the gate line 16 and are connected to the common line 8l, and the plurality of pixel electrodes 18 have the same conductivity as the data line 17. It is formed of a material and is connected to the pixel electrode line 18l and the storage electrode 18s.

In this case, the pixel electrode 18 connected to the pixel electrode line 18l is electrically connected to the drain electrode 23 of the thin film transistor T through the pixel electrode line 18l.

In addition, the storage electrode 18s overlaps a portion of the common line 8l below the first insulating layer 15a with the first insulating layer 15a therebetween to form a storage capacitor Cst.

In addition, the transparent color filter substrate 5 includes black matrix 6 and red, green and blue colors that prevent light from leaking to the thin film transistor T, the gate line 16 and the data line 17. A color filter 7 is formed to implement.

An alignment film (not shown) for determining the initial alignment direction of the liquid crystal molecules 30 is coated on opposite surfaces of the array substrate 10 and the color filter substrate 5 configured as described above.

The general horizontal field type liquid crystal display having the above structure has the advantage of improving the viewing angle because the common electrode 8 and the pixel electrode 18 are disposed on the same array substrate 10 to generate a horizontal electric field. Have

The present invention improves the viewing angle crosstalk by reducing the electrical energy of liquid crystal molecules between the data line and the outermost common electrode by reducing the inclination angle of the data line and the outermost common electrode facing the data line. It is an object of the present invention to provide a liquid crystal display device.

Other objects and features of the present invention will be described in the following description of the invention and claims.

In order to achieve the above object, the horizontal field type liquid crystal display device of the present invention comprises a plurality of gate lines arranged in one direction on the first substrate; A plurality of data lines arranged to be inclined at a first angle with respect to the vertical direction to the one direction to define a plurality of pixel areas together with the gate lines; A switching element formed at an intersection of the gate line and the data line; A common electrode formed in the pixel area, the common electrode including a first common electrode formed in a center area of the pixel area and a second common electrode formed in an area adjacent to the data line; A pixel electrode formed in the pixel region and alternately arranged with the common electrode to generate a horizontal electric field; And a second substrate bonded to the first substrate, wherein one side of the second common electrode facing the data line is arranged to be inclined at the first angle while the other side of the second common electrode is inclined. Is arranged to be inclined at a second angle with respect to the vertical direction to the one direction, the first common electrode is arranged to be inclined at the second angle, the first angle is gentler than the second angle It is characterized by.

In addition, another horizontal field type liquid crystal display device of the present invention comprises a plurality of gate lines arranged in one direction on the first substrate; A plurality of data lines arranged to be inclined at a first angle with respect to an arbitrary vertical direction with respect to the gate line to define a plurality of pixel regions together with the gate lines; A switching element formed at an intersection of the gate line and the data line; At least one pair of common electrode and pixel electrode generating a horizontal electric field in the pixel region; And a second substrate joined to face the first substrate, wherein one side of the common electrode facing the data line is arranged to be inclined at the first angle, and the other side of the common electrode and the remaining common electrode and the pixel. The electrodes are characterized by being arranged inclined at a second angle.

Hereinafter, a preferred embodiment of a horizontal field type liquid crystal display device according to the present invention will be described in detail with reference to the accompanying drawings.

3 is a plan view schematically illustrating a portion of an array substrate of a horizontal field type liquid crystal display according to a first exemplary embodiment of the present invention.

At this time, although N gate lines and M data lines cross MxN pixels on the actual array substrate, one pixel is shown in the figure for simplicity of explanation.

4 is an exemplary view showing a section taken along the line III-III 'of the array substrate shown in FIG. 3, and together shows the array substrate illustrated in FIG. 3 and the color filter substrate bonded to correspond to the array substrate. have.

In this case, as shown in FIG. 3, when the common electrode and the pixel electrode have a bending structure, the liquid crystal molecules are arranged in two directions to form a 2-domain, thereby further improving the viewing angle as compared with the mono-domain. However, the present invention is not limited to the horizontal field type liquid crystal display device having the two-domain structure, and the present invention is applicable to the horizontal field type liquid crystal display device having a multi-domain structure of two or more domains. As described above, an IPS structure for forming a multi-domain of two or more domains is referred to as an S-IPS structure.

3 and 4, a gate line 116 and a data line 117 are formed on the array substrate 110 of the first embodiment to be arranged vertically and horizontally on the array substrate 110 to define a pixel region. The thin film transistor T, which is a switching element, is formed in an intersection region of the gate line 116 and the data line 117.

The thin film transistor T includes a gate electrode 121 constituting a portion of the gate line 116, a pair of source electrodes 122 connected to the data line 117, and a drain electrode connected to the pixel electrode 118. It consists of 123. In addition, the thin film transistor T is formed by the first insulating film 115a for insulating the gate electrode 121 and the source / drain electrodes 122 and 123 and the gate voltage supplied to the gate electrode 121. The active pattern 124 forms a conductive channel between the source electrode 122 and the drain electrode 123.

The common electrodes 108 and 108 'and the pixel electrodes 118 are alternately formed in the pixel region to generate a horizontal electric field, and the common electrodes 108 and 108' are central regions of the pixel region. And a first common electrode 108 formed at the second common electrode 108 and a second common electrode 108 'formed at an area adjacent to the data line 117.

In this case, the common electrodes 108 and 108 ′ and the pixel electrode 118 are arranged in a direction substantially parallel to the data line 117.

Further, first common lines disposed at both ends of the common electrodes 108 and 108 ′ in a direction substantially parallel to the gate line 116 and connecting one side of the common electrodes 108 and 108 ′. A second common line 108l 'is formed to connect 108l to the other side of the common electrodes 108 and 108'.

In addition, a first pixel electrode connection is formed at both ends of the pixel electrode 118 to connect one side of the pixel electrode 118 and overlap the first common line 108l to form a first storage capacitor Cst1. A second pixel electrode connection line 118l 'connecting a line 118l to the other side of the pixel electrode 118 and overlapping the second common line 108l' to form a second storage capacitor Cst2. Is formed.

The first storage capacitor Cst1 and the second storage capacitor Cst2 serve to maintain a constant voltage applied to the liquid crystal capacitor until the next signal. The first storage capacitor Cst1 and the second storage capacitor Cst2 have effects such as stabilization of gray scale display, reduction of flicker, and afterimage in addition to signal retention.

The common electrodes 108 and 108 ′ are formed on the same layer as the gate line 116, and a second insulating film 115b is formed on the entire surface of the substrate including the data line 117, and the pixel electrode ( 118 is formed on the second insulating film 115b. In this case, the pixel electrode 118 is formed of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO). The pixel electrode 118 is electrically connected to the drain electrode 123 through the contact hole 140 formed in the second insulating layer 115b.

In this case, the pixel electrode 118 of the present invention has the advantage of improving the aperture ratio by forming a transparent conductive material.

3 and 5, in the case of the first embodiment, the data line 117, the common electrodes 108 and 108 ′, and the pixel electrode 118 may be connected to the gate line 116. It is designed to be inclined at an angle α of about 20 degrees with respect to the vertical direction. As a result, a strong electric field is formed between the data line 117 and the second common electrode 108 ′, which is the outermost common electrode, and the viewing angle when the liquid crystal molecules placed in the formed electric field are twisted or further tilted and viewed from the side. It may also cause crosstalk.

The transparent color filter substrate 105 bonded to the array substrate 110 configured as described above includes a black matrix for preventing light leakage from the thin film transistor T, the gate line 116, and the data line 117. 106 and a color filter 107 for realizing red, green and blue colors are formed.

In addition, a first alignment layer 109 and a second alignment layer 119 are formed on opposite surfaces of the color filter substrate 105 and the array substrate 110 to determine the initial alignment direction of the liquid crystal molecules. The liquid crystal layer 130 is formed between the first alignment layer 109 and the second alignment layer 119.

According to the present invention, the common electrodes 108 and 108 ', the pixel electrode 118, and the data line 117 are formed in a bent structure to form a multi-domain structure in which the driving directions of liquid crystal molecules are symmetrical. As a result, the abnormal light due to the birefringence characteristic of the liquid crystal cancels each other, thereby minimizing color shift. That is, due to the birefringence characteristic of the liquid crystal molecules, the color transition occurs according to the field of view of the liquid crystal molecules. In particular, yellow shift is observed in the short axis direction of the liquid crystal molecules, and blue shift (blue) in the long axis direction. shift) is observed. Therefore, when the short axis and the long axis of the liquid crystal branch are properly disposed, the color refraction can be reduced by compensating the birefringence value.

For example, in the case of 2-domain in which the liquid crystal molecules are symmetrical to each other, as shown in FIG. 6, the birefringence value of a1 of the first liquid crystal molecule 130a is opposite to the first liquid crystal molecule 130a. The birefringence value of a2 of the second liquid crystal molecules 130b taking the molecular alignment in the direction is compensated, and as a result, the birefringence value becomes about zero. In addition, the birefringence value of c1 is compensated by c2. Therefore, the color shift due to the birefringence characteristic of the liquid crystal molecules can be minimized to prevent deterioration of image quality according to the viewing angle.

7 is a plan view schematically illustrating a portion of an array substrate of a horizontal field type liquid crystal display according to a second exemplary embodiment of the present invention.

At this time, although N gate lines and M data lines cross MxN pixels on the actual array substrate, one pixel is shown in the figure for simplicity of explanation.

As shown in the figure, a gate line 216 and a data line 217 are formed in the array substrate 210 of the second embodiment, which are arranged horizontally and horizontally on the array substrate 210 to define a pixel region. The thin film transistor T, which is a switching element, is formed at the intersection of the gate line 216 and the data line 217.

The thin film transistor T includes a gate electrode 221 constituting a portion of the gate line 216, a pair of source electrodes 222 connected to the data line 217, and a drain electrode connected to the pixel electrode 218. It consists of 223. In addition, the thin film transistor T is formed by a first insulating film (not shown) for insulating the gate electrode 221 and the source / drain electrodes 222 and 223 and a gate voltage supplied to the gate electrode 221. The active pattern 224 forms a conductive channel between the source electrode 222 and the drain electrode 223.

The common electrodes 208 and 208 'and the pixel electrodes 218 are alternately formed in the pixel region, and the common electrodes 208 and 208' are formed at the center of the pixel region. The first common electrode 208 formed in the region and the second common electrode 208 'formed in the region adjacent to the data line 217 are formed.

In this case, first ends of the common electrodes 208 and 208 'are disposed in a direction substantially parallel to the gate line 216 and connect one side of the common electrodes 208 and 208'. A second common line 208l 'is formed which connects 208l and the other side of the common electrodes 208 and 208'.

In addition, a first pixel electrode connection is formed at both ends of the pixel electrode 218 to connect one side of the pixel electrode 218 and overlap the first common line 208l to form a first storage capacitor Cst1. A second pixel electrode connection line 218l 'connecting the line 218l to the other side of the pixel electrode 218 and overlapping the second common line 208l' to form a second storage capacitor Cst2. Is formed.

The common electrodes 208 and 208 'are formed on the same layer as the gate line 216, and a second insulating layer (not shown) is formed on the entire surface of the substrate including the data line 217. 218 is formed on the second insulating film. In this case, the pixel electrode 218 is formed of a transparent conductive material such as indium tin oxide or indium zinc oxide. The pixel electrode 218 is electrically connected to the drain electrode 223 through the contact hole 240 formed in the second insulating layer.

In this case, the pixel electrode 218 of the present invention has the advantage of improving the aperture ratio by forming a transparent conductive material. However, the present invention is not limited thereto, and the pixel electrode 218 may be made of an opaque conductive material such as aluminum, copper, molybdenum, or the like.

Here, in the case of the second embodiment, the inclination of the data line 217 and the second common electrode 208 'is different from that of the first embodiment described above, so that the first common electrode 208 and the pixel electrode 218 are inclined. Compared to FIG. 8, the present invention has a gentler shape than in FIG. 8.

FIG. 8 is an exemplary view schematically showing slopes of a data line and an outermost common electrode in the horizontal field type liquid crystal display device of the second embodiment shown in FIG. 7.

As shown in the figure, in the case of the second embodiment, one side of the data line 217 and the second common electrode 208 'is about 10 to about any vertical direction with respect to the gate line 216. It is designed to be inclined at an angle α ′ of 15 degrees, and the other side of the second common electrode 208 ′ is at an angle α of about 20 degrees with respect to any vertical direction with respect to the gate line 216. It is designed to tilt. In this case, the first common electrode 208 and the pixel electrode 218 are inclined at an angle of about 20 degrees as in the case of the first embodiment.

As described above, in the case of the second embodiment, the electrode angle of the side surface of the second common electrode 208 ′, which is the outermost common electrode facing the data line 217 and the data line 217, is measured at 20 degrees of the first embodiment. By gentle to 10 to 15 degrees it is possible to reduce the electrical energy due to the electric field formed between the data line 217 and the second common electrode 208 '. As a result, the degree of twist or tilt of the liquid crystal molecules placed on the formed electric field can be reduced to alleviate the viewing angle crosstalk when viewed from the side.

In addition, in the horizontal field type liquid crystal display device of the second embodiment, as the inclination angle of the data line 217 is changed from 20 degrees to 10 to 15 degrees, the resistance is reduced compared to the data lines of the first embodiment at the same line width. Since the signal delay and charging characteristics of the data line can be improved, there is an advantage.

The array substrate configured as described above is bonded to the color filter substrate (not shown) by a sealant formed on the outside of the image display area, wherein the color filter substrate leaks light to the thin film transistor, the gate line, and the data line. The black matrix to prevent the color and the color filter to implement the colors of red, green and blue are formed.

At this time, the color filter substrate and the array substrate are bonded together through a covalent key formed on the color filter substrate or the array substrate.

The present invention can be used not only in liquid crystal display devices, but also in other display devices fabricated using thin film transistors, for example, organic light emitting display devices in which organic light emitting diodes (OLEDs) are connected to driving transistors.

While a great many are described in the foregoing description, it should be construed as an example of preferred embodiments rather than limiting the scope of the invention. Therefore, the invention should not be construed as limited to the embodiments described, but should be determined by equivalents to the appended claims and the claims.

As described above, the horizontal field type liquid crystal display according to the present invention can obtain the effect of improving the viewing angle crosstalk by changing the inclination angles of the data line and the outermost common electrode.

In addition, in the horizontal field type liquid crystal display device according to the present invention, by smoothing the inclination angle of the data line, the signal delay and charging characteristics can be improved by reducing the resistance of the data line.

Claims (14)

A plurality of gate lines arranged in one direction on the first substrate; A plurality of data lines arranged to be inclined at a first angle with respect to the vertical direction to the one direction to define a plurality of pixel areas together with the gate lines; A switching element formed at an intersection of the gate line and the data line; A common electrode formed in the pixel area, the common electrode including a first common electrode formed in a center area of the pixel area and a second common electrode formed in an area adjacent to the data line; A pixel electrode formed in the pixel region and alternately arranged with the common electrode to generate a horizontal electric field; And A second substrate is bonded to face the first substrate, One side of the second common electrode facing the data line is arranged to be inclined at the first angle, while the other side of the second common electrode is inclined at a second angle with respect to the vertical direction with respect to the one direction. Arranged, The first common electrode is arranged to be inclined at the second angle, And wherein the first angle has a gentler slope than the second angle. The horizontal field type liquid crystal display of claim 1, wherein the common electrode and the pixel electrode have a bending structure. The horizontal field type liquid crystal display of claim 2, wherein the data line has a bending structure corresponding to the common electrode and the pixel electrode. The horizontal field type liquid crystal display device according to claim 1, wherein the first angle is 10 to 15 degrees with respect to the vertical direction with respect to the one direction. The horizontal field type liquid crystal display of claim 4, wherein the second angle is about 20 degrees with respect to the vertical direction with respect to the one direction. delete The horizontal field type liquid crystal display of claim 1, wherein the pixel electrodes are arranged to be inclined at the second angle. The horizontal field type liquid crystal display of claim 1, wherein the pixel electrode is made of a transparent conductive material of indium tin oxide or indium zinc oxide. The horizontal field type liquid crystal display of claim 1, further comprising a common line arranged in a direction parallel to the gate line and connecting one end of the common electrode to each other. 10. The method of claim 9, further comprising a pixel electrode connection line arranged in a direction parallel to the gate line to connect one end of the pixel electrode to each other and overlapping the common line to form a storage capacitor. Horizontal field type liquid crystal display device. delete delete delete delete

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