KR20180047549A - Liquid Crystal Display Device - Google Patents

Abstract

The present invention provides a liquid crystal display device. The liquid crystal display device includes first and second substrates facing each other and spaced apart from each other; a liquid crystal layer disposed between the first and second substrates; first and second polarizing plates respectively disposed on the outer surfaces of the first and second substrates; and a polarizing layer disposed on the inner surface of the first substrate and having the same transmission axis as the first polarizing plate. By arranging the polarizing layer on the inner surface of the substrate close to a backlight unit, light leakage in the edge region due to a stress is reduced, and the contrast ratio and the display quality of an image are improved.

Description

[0001] The present invention relates to a liquid crystal display device,

The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device in which a light leakage in an edge region due to stress is minimized by forming a polarizing layer on the inner surface of a substrate.

Recently, as the age of the information society has progressed rapidly, a display field for processing and displaying a large amount of information has been developed. In order to respond to the era of thinning, lightweighting and low power consumption, a flat panel display ) Has emerged.

Accordingly, a thin film transistor liquid crystal display (TFT-LCD) having excellent color reproducibility and being thin has been developed. The liquid crystal display displays an image using the optical anisotropy and the polarization property of liquid crystal molecules.

Such a liquid crystal display device will be described with reference to the drawings.

1 is a cross-sectional view showing a conventional liquid crystal display device.

1, the conventional liquid crystal display device 10 includes first and second substrates 20 and 50 which are spaced apart from each other and disposed between the first and second substrates 20 and 50 And a backlight unit (60) disposed under the first substrate (60).

A common wiring 22 is formed in each pixel region P on the inner surface of the first substrate 20 and a gate insulating layer 24 is formed on the common wiring 22. [

A data line consisting of a lower layer 26 of semiconductor material and an upper layer 28 of a metal material is formed on the boundary of the pixel region P above the gate insulating layer 24 and a protective layer 30 is formed on the data line .

A color filter layer 32 is formed in each pixel region P on the protection layer 30 and a planarization layer 34 is formed on the color filter layer 32.

A common electrode 36 is formed on the boundary between the pixel region P and the pixel region P on the planarization layer 34 and a common electrode 36 is formed on the pixel region P above the planarization layer 34 The pixel electrode 38 is formed.

A column spacer 52 is formed on the inner surface of the second substrate 50.

The first and second polarizers 60 and 62 are formed on the outer surfaces of the first and second substrates 20 and 50, respectively.

A liquid crystal layer 70 is formed between the first and second substrates 20 and 50.

The liquid crystal display device 10 displays images by controlling the retardation of the liquid crystal layer 70 by an electric field generated between the common electrode 36 and the pixel electrode 38. The first polarizer plate 60 passes through the liquid crystal layer 70 and has a different polarization state according to the phase retardation of the liquid crystal layer 70 and passes through the second polarizing plate 62 or absorbed by the second polarizing plate 62, .

Here, the first and second substrates 20 and 50 have a phase delay of about 2 nm to about 10 nm, but do not have an optical axis and thus do not function optically while the liquid crystal display device 110 displays an image.

However, when stress is applied to the first and second substrates 20 and 50, the first and second substrates 20 and 50 have an undesirable amount of phase delay variation, which will be described with reference to the drawings .

2 is a cross-sectional view showing a change amount of stress of a conventional liquid crystal display device.

2, the conventional liquid crystal display device 10 includes first and second substrates 20 and 50 which are spaced apart from each other and first and second substrates 20 and 50 which are interposed between the first and second substrates 20 and 50, And the first and second substrates 20 and 50 are attached together by the seal pattern 72 of the edge portion.

The first and second substrates 20 and 50 are bent in a concave curved shape when the external pressure is applied to the central region A1 of the liquid crystal display device 10 from the upper side to the lower side. A tensile stress is applied to the outer surface of the first substrate 20 and the inner surface of the second substrate 50 and a compressive stress is applied to the inner surface of the first substrate 20 and the outer surface of the second substrate 50 Can be interpreted.

Since the inner edge portions of the first and second substrates 20 and 50 are fixed by the seal pattern 72 in the central region A1 of the liquid crystal display device 10, The tensile stress and the compressive stress of the inner and outer surfaces of the first substrate 20 are the same while the magnitude of the tensile stress of the outer surface of the first substrate 20 in the edge region A2 of the liquid crystal display device 10 is the same. And the magnitude of the compressive stress on the outer surface of the second substrate 50 is greater than the magnitude of the tensile stress on the inner surface of the second substrate 50. [

That is, the first and second center lines C1 and C2 of the first and second substrates 20 and 50 move from the central area A1 to the edge area A2 of the liquid crystal display device 10, respectively, And tensile stress and compressive stress are largely applied to the outer surfaces of the first and second substrates 20 and 50. As a result,

Since the phase delay of each of the first and second substrates 20 and 50 is determined by the product of the photoelastic coefficient, the thickness and the stress, in the steady state, each of the first and second substrates 20 and 50 does not have an optical axis, With a phase retardation of about 10 nm and with a tensile stress and a compressive stress applied, the first and second substrates 20 and 50 each have an optical axis and have a phase delay greater than about 2 nm to about 10 nm.

That is, in the central region A1 of the liquid crystal display device 10, the phase delays due to tensile stress and compressive stress in the same size and different directions of the inner and outer surfaces of the first and second substrates 20, The amount of change in phase delay due to the stress of each of the first and second substrates 20 and 50 is substantially zero.

On the other hand, in the edge region A2 of the liquid crystal display device 10, the amount of change in the phase delay due to the stress of the first substrate 20 due to the tensile stress of the outer surface larger than the compressive stress of the inner surface becomes a value larger than 0 , The amount of change in the phase delay due to the stress of the second substrate 50 due to the compressive stress of the outer surface larger than the inner surface tensile stress is greater than zero. ("+, -" indicates the direction of tensile stress and compressive stress, respectively)

The amount of change in the phase delay caused by the stress of the first and second substrates 20 and 50 and the increase in the total phase delay cause the light leakage in the edge region A2 of the liquid crystal display device 10, This will be described with reference to the drawings.

Fig. 3 is a diagram showing the phase delay at a cross-section of an edge region of a conventional liquid crystal display device and at a plurality of positions on multiple surfaces.

3, tensile stress and compressive stress are respectively applied to the outer surface and the inner surface of the first substrate 20 in the edge region (A2 in Fig. 2) of the first and second substrates 20 and 50 And tensile and compressive stresses are applied to the inner and outer surfaces of the first and second substrates 50 and 50, respectively, the first and second substrates 20 and 50 have a variation in phase delay due to a stress greater than zero, The total phase delay of the first and second substrates 20 and 50 increases and light incident from the backlight unit 80 of the lower portion of the first substrate 20 is incident on the first and second polarizers 60 and 62, The polarization state is changed while passing through the first and second substrates 20 and 50 and the liquid crystal layer 70.

That is, the incident light passes through the first polarizing plate 60 and becomes a linearly polarized light state corresponding to the equatorial A point of the Poincare sphere at the first position P1 corresponding to the outer surface of the first substrate 20 Corresponds to the first point of the upper half of the Poincare sphere through the total phase delay of the first substrate 20 at the second position P2 corresponding to the inner surface of the first substrate 20 after passing through the first substrate 20 Polarized state.

The phase retardation of the liquid crystal layer 70 at the third position P3 corresponding to the inner surface of the second substrate 50 after passing through the liquid crystal layer 70 causes an ellipse corresponding to the first point of the lower half of the Poincare sphere The phase of the second substrate 50 is shifted to the polarization state and after passing through the second substrate 50 by the total phase delay of the second substrate 50 at the fourth position P4 corresponding to the outer surface of the second substrate 50, The second point is a point farther from the point A than the first point.

Since the first and second polarizing plates 60 and 62 each have mutually perpendicular transmission axes corresponding to the A point and B point of the equator of the Poincare sphere, the absorption axis of the second polarizer 62 is the A point of the equator of the Poincare sphere .

Therefore, the light passing through the second substrate 50 has an elliptically polarized state corresponding to the second point of the lower half of the equator of the equator of the Poincare sphere. Therefore, the light is not completely absorbed by the second polarizer 62, And appears as light leakage in the edge area A2 of the display device 10. [

Fig. 4 is a photograph of luminance of the central region and the edge region of the conventional liquid crystal display device.

4, when a heavy rod F is placed on the conventional liquid crystal display device 10 to apply an external pressure, the central region A1 remote from the seal pattern (72 in FIG. 2) The amount of change in the phase delay due to the stress of the substrate 20 becomes 50 and the total phase delay does not increase so that no light leakage occurs. However, in the edge region A2 close to the seal pattern 72, The amount of change in the phase delay due to the stress in the center region (20, 50 in FIG. 1) becomes larger than 0, and the total phase delay increases to generate light leakage, and as a result, the central region A1 and the edge region A2 show different brightness .

For example, in the case where the external pressure is not applied, the central area A1 and the edge area A2 of the liquid crystal display device 10 displaying black all have a brightness of about 0.4 nit, while about 200 g, about 400 g, The central area A1 of the liquid crystal display device 10 displaying black has a brightness of about 0.4 nit and the liquid crystal display device 10 displaying black The edge region A2 has a luminance of about 0.91 nit, about 1.31 nit, and about 1.82 nit, respectively.

That is, as the external pressure or stress increases, the light leakage in the edge region A2 of the liquid crystal display device 10 increases.

This light leakage has a problem that the contrast ratio of the liquid crystal display device 10 is lowered and the quality of the image displayed by the liquid crystal display device 10 is lowered.

SUMMARY OF THE INVENTION The present invention has been made in order to solve such problems, and it is an object of the present invention to provide a liquid crystal display device in which the light leakage in the edge region due to stress is reduced by arranging the polarizing layer on the inner surface of the substrate, do.

Another object of the present invention is to provide a liquid crystal display device in which a color shift in an oblique viewing angle is minimized by disposing a polarizing layer on an inner surface of a substrate disposed close to a backlight unit.

Further, according to the present invention, the stability and reliability of the polarizing plate are improved by forming the thin film transistor and the color filter layer on the inner surface of the first substrate and forming the polarizing layer on the inner surface of the second substrate disposed close to the backlight unit, The liquid crystal display device of the present invention is minimized.

According to an aspect of the present invention, there is provided a liquid crystal display device including first and second substrates spaced apart from each other, a liquid crystal layer disposed between the first and second substrates, And a polarizing layer disposed on the inner surface of the first substrate and having a transmission axis which is the same as the transmission axis of the first polarizing plate.

The liquid crystal display may further include a backlight unit disposed under the first substrate.

The polarizing layer may be of the E type in which the optical axis and the transmission axis are parallel.

The polarizing layer may be formed by a coating method.

The liquid crystal display device may further include: a gate wiring and a data wiring which are arranged above the polarizing layer and which define pixel regions intersecting with each other; a thin film transistor connected to the gate wiring and the data wiring; And a column spacer disposed at a boundary between the pixel region and the first and second substrates, the pixel electrode being disposed in the pixel region, the common electrode being disposed in the pixel region and spaced apart from the pixel electrode, .

The liquid crystal display device may further include a color filter layer disposed on the pixel electrode and the common electrode, and a planarization layer disposed on the color filter layer.

The liquid crystal display device further includes a gate wiring and a data wiring which are arranged on the inner surface of the second substrate and define a pixel region intersecting with each other, a thin film transistor connected to the gate wiring and the data wiring, A common electrode which is arranged in the pixel region and is spaced apart from the pixel electrode and a column spacer which is arranged at a boundary between the pixel region and the first and second substrates, .

The liquid crystal display may further include a color filter layer disposed under the pixel electrode and the common electrode, and a planarization layer disposed under the color filter layer.

According to the present invention, by arranging the polarizing layer on the inner surface of the substrate, the light leakage in the edge region due to the stress is reduced, and the contrast ratio and the display quality of the image are improved.

Further, the present invention has an effect that the color shift in the oblique viewing angle is minimized by disposing the polarizing layer on the inner surface of the substrate disposed close to the backlight unit.

Further, according to the present invention, the stability and reliability of the polarizing layer are improved by forming the thin film transistor and the color filter layer on the inner surface of the first substrate and forming the polarizing layer on the inner surface of the second substrate disposed close to the backlight unit, So that the mutation is minimized.

1 is a cross-sectional view showing a conventional liquid crystal display device.
BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a liquid crystal display device.
3 is a view showing a phase delay at a cross-section of an edge region of a conventional liquid crystal display device and at a plurality of positions on multiple surfaces.
4 is a photograph of luminance of a central region and an edge region of a conventional liquid crystal display device.
5 is a cross-sectional view illustrating a liquid crystal display device according to a first embodiment of the present invention.
6 is a view showing a phase delay at a cross-section of an edge region and at a plurality of positions on multiple surfaces of a liquid crystal display device according to a first embodiment of the present invention.
7 is a cross-sectional view illustrating a liquid crystal display device according to a second embodiment of the present invention.
8 is a view showing a phase delay at a cross-section of an edge region and at a plurality of positions on multiple surfaces of a liquid crystal display device according to a second embodiment of the present invention.
9 is a photograph of the luminance of the center region and the edge region of the liquid crystal display device according to the second embodiment of the present invention.

Hereinafter, a liquid crystal display device according to the present invention will be described with reference to the accompanying drawings.

5 is a cross-sectional view illustrating a liquid crystal display device according to a first embodiment of the present invention.

5, the liquid crystal display device 110 according to the first embodiment of the present invention includes first and second substrates 120 and 150 which are spaced apart from each other and first and second substrates 120 and 150, A liquid crystal layer 170 disposed between the first substrate 120 and the second substrate 120 and a backlight unit 180 disposed under the first substrate 120.

An in-cell type polarizing layer 164 is formed on the inner surface of the first substrate 120. The polarizing layer 164 of the in-cell type may be formed by a coating method.

For example, the polarizing layer 164 of the in-cell type may be of an E (extraordinary) type in the form of a disc consisting of a supramolecular complex or a plurality of organic compounds, And may have an absorption axis perpendicular to the optical axis and a transmission axis parallel to the optical axis.

A common wiring 122 is formed in each pixel region P above the polarizing layer 164 and a gate insulating layer 124 is formed over the common wiring 122.

Although not shown, a gate electrode is formed in each pixel region P on the inner surface of the first substrate 120, and a gate wiring connected to the gate electrode is formed in the boundary of the pixel region P on the inner surface of the first substrate 120 , The gate insulating layer 124 may be formed on the gate electrode and the gate wiring.

A data line is formed at the boundary of the pixel region P above the gate insulating layer 124 and includes a lower layer 126 of a semiconductor material and an upper layer 128 of a metal material and crosses the gate line to define the pixel region P. And a protective layer 130 is formed on the data line.

Although not shown, an active layer of a semiconductor material is formed in each pixel region above the gate insulating layer 124, and a source electrode of a metal material connected to the data line and a drain electrode spaced from the source electrode are formed on both ends of the active layer And the protective layer 130 may be formed on the active layer, the source electrode, and the drain electrode.

The gate electrode, the active layer, the source electrode, and the drain electrode constitute a thin film transistor arranged in each pixel region P.

A color filter layer 132 is formed on each pixel region P on the protection layer 130 and a planarization layer 134 is formed on the color filter layer 132. The color filter layer 132 is formed on the pixel region P, Red, green, and blue color filters that are arranged separately.

A common electrode 136 is formed on the boundary between the pixel region P and the pixel region P on the planarization layer 134 and a common electrode 136 is formed on the pixel region P above the planarization layer 134 The pixel electrode 138 is formed.

Although not shown, the common electrode 136 may be connected to the common line 122, and the pixel electrode 138 may be connected to the drain electrode of the thin film transistor.

A column spacer 152 is disposed between the first and second substrates 120 and 150. The column spacer 152 is formed on the common electrode 136 at the boundary of the pixel region P of the first substrate 120 Or may be formed under the second substrate 150.

First and second polarizers 160 and 162 are formed on the outer surfaces of the first and second substrates 120 and 150, respectively.

The transmissive axes of the first and second polarizers 160 and 162 may be perpendicular to each other (in the case of the normally black mode) or parallel to each other (in the case of the normally white mode) 164 may be the same as the transmission axis of the first polarizer 160 on the outer surface of the first substrate 120.

A liquid crystal layer 170 is formed between the first and second substrates 120 and 150.

The liquid crystal display device 110 displays an image by controlling the retardation of the liquid crystal layer 170 by an electric field generated between the common electrode 136 and the pixel electrode 138 according to an applied voltage The first polarizing plate 160 and the polarizing layer 164 pass through the liquid crystal layer 170 and have a different polarization state according to the phase delay of the liquid crystal layer 170 and pass through the second polarizing plate 162 Or can be absorbed by the second polarizing plate 162 to display the gradation.

Here, in a state where no stress is applied, the total phase delay of each of the first and second substrates 120 and 150 is maintained unchanged by the amount of phase delay due to the substantially zero stress, In the applied state, the total phase delay of each of the first and second substrates 120 and 150 is maintained unchanged by the amount of change of the phase delay due to the substantially zero stress in the central region (A1 in FIG. 2) (A2 in FIG. 2), the total phase delay of each of the first and second substrates 120 and 150 increases due to the amount of change in the phase delay due to the stress substantially greater than zero.

The polarization state of the backlight unit 180 after the light of the backlight unit 180 has passed through the first polarizing plate 160 is shifted from the first substrate 120 to the stress of the first substrate 120 of the edge area A2 The polarizing plate 164 of the inner surface of the first substrate 120 having the same transmission axis as that of the first polarizing plate 160 again passes through the first polarizing plate 160 Polarized state.

 That is, the polarizing layer 164 of the incel type restores the polarization state of the light changed by the amount of change of the phase delay due to the stress of the first substrate 120 to the original state. As a result, the backlight unit 180 It is possible to prevent the light leakage due to the phase delay of the edge region A2 of the first substrate 120 near.

The light leakage reduction by the polarizing layer 164 will be described with reference to the drawings.

6 is a view showing a phase delay at a cross section of an edge region and a plurality of positions on a multi-plane of a liquid crystal display device according to the first embodiment of the present invention.

6, tensile stress and compressive stress are respectively applied to the outer surface and the inner surface of the first substrate 120 in the edge region (A2 in Fig. 2) of the first and second substrates 120 and 150 The first and second substrates 120 and 150 have a variation in the phase delay due to a stress greater than zero when the tensile stress and the compressive stress are respectively applied to the inner and outer surfaces of the first and second substrates 150 and 150, The total phase delay of the first and second substrates 120 and 150 increases and the light incident from the backlight unit 180 of the lower portion of the first substrate 120 is reflected by the first and second polarizers 160 and 162, The polarization state is changed while passing through the polarizing layer 164, the first and second substrates 120 and 150, and the liquid crystal layer 170.

That is, the incident light passes through the first polarizing plate 160 and becomes a linearly polarized light state corresponding to the equatorial A point of the Poincare sphere at the first position P1 corresponding to the outer surface of the first substrate 120 , Corresponds to the first point of the upper half of the Poincare sphere by the total phase delay of the first substrate 120 at the second position P2 corresponding to the inner surface of the first substrate 120 after passing through the first substrate 120 Polarized state.

After passing through the polarizing layer 164 having the same transmission axis as the first polarizing plate 160 and then passing through the third position P3 corresponding to the lower surface of the liquid crystal layer 170, a linearly polarized light state corresponding to the equatorial A point of the Poincare sphere .

Here, the degree of polarization of the polarizing layer 164 of the incense type is about 99%, which is somewhat lower than the degree of polarization of each of the first and second polarizing plates 160 and 162 of about 99.995%. As a result, The polarization state of the incident light after passing may correspond to a specific point slightly spaced from the equatorial A point of the Poincare sphere, but such a specific point may correspond to the first point of the first half of the Poincare sphere, which is the polarization state of the incident light after passing through the first substrate 120 It may be a point much closer to the equatorial A point of the Poincaré district than the point.

The phase retardation of the liquid crystal layer 170 at the fourth position P4 corresponding to the inner surface of the second substrate 150 after passing through the liquid crystal layer 170 causes an ellipse corresponding to the first point of the lower half of the Poincare sphere The second substrate 150 is polarized and passes through the second substrate 150 and is then moved in the fifth position P5 corresponding to the outer surface of the second substrate 150 by the total phase delay of the second substrate 150, The second point is a point farther from the point A than the first point.

Here, since the polarization state of the incident light before passing through the liquid crystal layer 170 by the polarization layer 164 corresponds to the equatorial A point of the Poincare sphere, the polarization state of the incident light after passing through the liquid crystal layer 170 corresponds to the corresponding Poincare sphere The first point of the lower half is closer to the point A of the equator of the Poincare sphere than the first point of the lower half of the Poincare sphere after the polarized state of the incident light after passing through the conventional liquid crystal layer 70 of Fig. The second point of the lower half of the Poincare sphere corresponding to the polarization state of the incident light after passing through the second substrate 50 of FIG. 3 is also the second point of the lower half of the Poincare sphere corresponding to the polarization state of the incident light after passing through the conventional second substrate 50 of FIG. Closer to the A point in the equator of the Poincaré district.

Since the first and second polarizing plates 160 and 162 each have mutually perpendicular transmission axes corresponding to the A point and the B point of the equator of the Poincare sphere, the absorption axis of the second polarizer 162 is the A point of the equator of the Poincare sphere .

Therefore, compared with the conventional liquid crystal display device (10 in Fig. 3), the light passing through the second substrate 150 has an elliptically polarized state corresponding to the second point of the lower half of the equator, which is closer to the A point of the equator The light is more absorbed in the second polarizing plate 162 and the light leakage in the edge region A2 of the liquid crystal display device 110 is minimized.

For example, since the change of the polarization state corresponding to the amount of change of the phase delay due to the stress of the first substrate 120 is removed and the change of the undesired polarization state occurs only by the phase delay of the second substrate 150, The light leakage of the liquid crystal display device 110 of one embodiment may be about 50% of the light leakage of the conventional liquid crystal display device 10 (Fig. 3).

Particularly, the general compensation film changes the polarization state by compensating the phase delay differently for each wavelength (color). On the other hand, the polarizing layer 164 of the first embodiment restores the polarization state regardless of the wavelength, Light glands can be minimized for all of the same colors.

The polarizing layer 164 may be formed on the inner surface of the second substrate 150. In the case of O (ordinary) mode, the polarizing layer 164 may be disposed on the inner surface of the second substrate 150, The liquid crystal display device 110 of the first embodiment formed on the inner surface of the first substrate 120 may be a liquid crystal display device of another embodiment in which the polarizing layer 164 is formed on the inner surface of the second substrate 150 disposed away from the backlight unit 180 The color shift in the oblique viewing angle may be smaller than in the device.

Specifically, in the O-mode liquid crystal display device, the absorption axis of the first polarizing plate 160 close to the backlight unit 180 and the alignment direction of the liquid crystal layer 170 are parallel to each other, and in the E-mode liquid crystal display device, Mode liquid crystal display device in which the polarizing layer 164 and the liquid crystal layer 170 are parallel to each other with an optical axis parallel to the absorption axis of the first polarizing plate 160 and the alignment direction of the liquid crystal layer 170, The phase delay is relatively small, and in the case of the E-mode liquid crystal display device, the polarizing layer 164 whose optical axis is parallel and the upper surface of the liquid crystal layer 170 are separated from each other, And more.

As described above, in the liquid crystal display device 110 according to the first embodiment of the present invention, the polarizing layer 164 of the in-cell type is formed on the inner surface of the first substrate 120, The polarization state of the first substrate 120 can be restored to the polarized state immediately after passing through the first polarizing plate 160 (the polarization state just before passing through the first substrate 120) The light leakage can be minimized and the contrast ratio and display quality can be improved.

By forming the polarizing layer 164 of the in-cell type on the inner surface of the first substrate 120 closer to the backlight unit 180 than the second substrate 150, the color variation in the oblique viewing angle can be minimized .

7 is a cross-sectional view illustrating a liquid crystal display device according to a second embodiment of the present invention, and a description of the same portions as those of the first embodiment will be omitted.

7, the liquid crystal display device 210 according to the second embodiment of the present invention includes first and second substrates 250 and 220 spaced apart from each other and first and second substrates 250 and 220, And a backlight unit 280 disposed below the first substrate 250. The liquid crystal layer 270 is disposed between the first substrate 250 and the second substrate 250,

A polarizing layer 264 of an in-cell type is formed on the inner surface of the first substrate 250.

The polarizing layer 264 of the in-cell type may be formed by a coating method. For example, the polarizing layer 264 of the in-cell type may include a supramolecular complex or a disc composed of a plurality of organic compounds disc type and may have an optical axis parallel to the coating direction and an absorption axis perpendicular to the optical axis and a transmission axis parallel to the optical axis.

A column spacer 252 is disposed between the first and second substrates 220 and 250. The column spacer 252 is formed on the polarizing layer 264 of the first substrate 250 or on the second substrate 220, The common electrode 236 can be formed on the boundary of the pixel region P of FIG.

A common wiring 222 is formed in each pixel region P on the inner surface of the second substrate 220 and a gate insulating layer 224 is formed under the common wiring 222.

A data line consisting of a lower layer 226 of a semiconductor material and an upper layer 228 of a metal material is formed at the boundary of the pixel region P under the gate insulating layer 224 and a protective layer 230 is formed under the data line .

Although not shown, a gate wiring and a thin film transistor are formed on the inner surface of the second substrate 260. The gate wiring and the data wiring cross each other to define the pixel region P, and the thin film transistor can be connected to the gate wiring and the data wiring have.

A color filter layer 232 is formed in each pixel region P under the protective layer 230 and a planarization layer 234 is formed under the color filter layer 232. The color filter layer 232 includes a pixel region P, Red, green, and blue color filters that are arranged separately.

A common electrode 236 is formed on the boundary between the pixel region P and the pixel region P under the planarization layer 234 and a common electrode 236 is formed on the pixel region P below the planarization layer 234. [ The pixel electrode 238 is formed.

First and second polarizers 262 and 260 are formed on the outer surfaces of the first and second substrates 250 and 220, respectively.

The transmissive axes of the first and second polarizers 262 and 260 may be perpendicular (in the case of the normally black mode) or parallel to each other (in the case of the normally white mode) 264 may be the same as the transmission axis of the first polarizer 262 on the outer surface of the first substrate 250.

A liquid crystal layer 270 is formed between the first and second substrates 250 and 220.

The liquid crystal display device 210 displays an image by controlling the retardation of the liquid crystal layer 270 by an electric field generated between the common electrode 236 and the pixel electrode 238 according to the applied voltage The first polarizing plate 262 and the polarizing layer 264 pass through the liquid crystal layer 270 and have a different polarization state according to the phase delay of the liquid crystal layer 270 and pass through the second polarizing plate 260 Or can be absorbed by the second polarizer 260 to display the gradation.

Here, the first and second substrates 250 and 220 have a change amount of the phase delay due to the substantially zero stress in the state where no stress is applied, (A1 in Fig. 2) has a variation amount of the phase delay due to the stress of substantially zero and a variation amount of the phase delay due to the stress larger than zero in the edge region (A2 in Fig. 2).

The polarization state of the backlight unit 280 after the light of the backlight unit 280 passes through the first polarizer plate 262 is shifted from the first substrate 250 to the first substrate 250 in the edge area A2 But after passing through the first polarizing plate 262 again by the polarizing layer 264 of the inner surface of the inner surface of the first substrate 250 having the same transmission axis as that of the first polarizing plate 262 Polarized state.

 In other words, the polarizing layer 264 of the incel type restores the polarization state of light changed by the amount of phase delay due to the stress of the first substrate 250 to the original state. As a result, the backlight unit 280 It is possible to prevent light leakage due to the phase delay of the edge region A2 of the first substrate 250 in the vicinity.

The light leakage reduction by the polarizing layer 264 will be described with reference to the drawings.

8 is a view showing a phase delay at a cross-section of an edge region and at a plurality of positions on multiple surfaces of a liquid crystal display device according to a second embodiment of the present invention.

Tensile stress and compressive stress are respectively applied to the outer surface and the inner surface of the first substrate 250 in the edge region (A2 in Fig. 2) of the first and second substrates 250 and 220 The first and second substrates 250 and 220 have a phase delay as well as the liquid crystal layer 270 when tensile stress and compressive stress are respectively applied to the inner and outer surfaces of the first substrate 220 and the second substrate 220, The light incident from the backlight unit 180 (FIG. 5) under the substrate 250 passes through the first and second polarizing plates 262 and 260, the polarizing layer 264, the first and second substrates 250 and 220, The polarization state is changed while passing through the layer 270.

That is, the incident light passes through the first polarizer 262 and becomes a linearly polarized light state corresponding to the equatorial A point of the Poincare sphere at the first position P1 corresponding to the outer surface of the first substrate 250 The first substrate 250 and the first substrate 250. The first substrate 250 and the second substrate 250 are disposed on the first substrate 250 and the first substrate 250, Polarized state.

After passing through the polarizing layer 264 having the same transmission axis as that of the first polarizing plate 262, a linearly polarized light state corresponding to the equatorial A point of the Poincare sphere at the third position P3 corresponding to the lower surface of the liquid crystal layer 270 .

Here, the degree of polarization of the polarizing layer 264 of the incense type is about 99%, which is somewhat lower than the degree of polarization of each of the first and second polarizing plates 262 and 264 to about 99.995%. As a result, The polarization state of the incident light after passing may correspond to a specific point slightly spaced from the equatorial A point of the Poincare sphere, but this particular point may correspond to the first point of the first half of the Poincare sphere, which is the polarization state of the incident light after passing through the first substrate 250 It may be a point much closer to the equatorial A point of the Poincaré district than the point.

The phase retardation of the liquid crystal layer 270 at the fourth position P4 corresponding to the inner surface of the second substrate 220 after passing through the liquid crystal layer 270 causes an ellipse corresponding to the first point of the lower half of the Poincare sphere The phase of the second substrate 220 is shifted to the polarization state by the total phase delay of the second substrate 220 at the fifth position P5 corresponding to the outer surface of the second substrate 220 after passing through the second substrate 220, The second point is a point farther from the point A than the first point.

Here, since the polarization state of the incident light before passing through the liquid crystal layer 270 by the polarization layer 264 corresponds to the equatorial A point of the Poincare sphere, the polarization state of the incident light after passing through the liquid crystal layer 270 corresponds to the polarization state of the corresponding Poincare sphere The first point of the lower half is closer to the point A of the equator of the Poincare sphere than the first point of the lower half of the Poincare sphere after the polarized state of the incident light after passing through the conventional liquid crystal layer 70 of Fig. The second point of the lower half of the Poincare sphere corresponding to the polarization state of the incident light after passing through the second substrate 50 of FIG. 3, and the second point of the lower half of the Poincare sphere corresponding to the polarization state of the incident light after passing through the conventional second substrate 50 of FIG. Closer to the A point in the equator of the Poincaré district.

At this time, since the first and second polarizing plates 262 and 260 have mutually perpendicular transmission axes corresponding to the A point and the B point of the equator of the Poincare sphere, the absorption axis of the second polarizer 260 is the A point of the equator of the Poincare sphere .

3), the light passing through the second substrate 220 has an elliptically polarized state corresponding to the second point of the lower half closer to the point A of the equator of the Poincare sphere So that it is absorbed more in the second polarizer 260 and the light leakage in the edge area A2 of the liquid crystal display device 210 is minimized.

For example, since the change of the polarization state corresponding to the amount of change of the phase delay due to the stress of the first substrate 250 is removed and the change of the undesired polarization state occurs only by the phase delay of the second substrate 220, The light leakage of the liquid crystal display device 210 of the second embodiment may be about 50% of the light leakage of the conventional liquid crystal display device 10 (FIG. 3).

In particular, the general compensation film changes the polarization state by compensating the phase delay differently for each wavelength (color), whereas the polarizing layer 264 of the second embodiment restores the polarization state irrespective of the wavelength, It is possible to minimize light leakage for all colors, such as blue,

Alternatively, in another embodiment, the polarizing layer 264 may be formed on the inner surface of the second substrate 220. In the O (ordinary) mode, the polarizing layer 264 may be disposed near the backlight unit 280 The liquid crystal display device 210 of the first embodiment in which the polarizing layer 264 is formed on the inner surface of the second substrate 220 disposed away from the backlight unit 280, The color shift in the oblique viewing angle may be smaller than in the device.

Specifically, in the O-mode liquid crystal display device, the absorption axis of the first polarizer 260 close to the backlight unit 280 and the alignment direction of the liquid crystal layer 270 are parallel to each other, and in the E-mode liquid crystal display device, Mode liquid crystal display device, the polarizing layer 264 and the liquid crystal layer 270 having an optical axis parallel to each other are perpendicular to the absorption axis of the first polarizer 260 near the liquid crystal layer 270 and the alignment direction of the liquid crystal layer 270, The phase retardation is relatively small in the case of the E-mode liquid crystal display device, the polarizing layer 264 having the optical axis parallel to the upper surface of the liquid crystal layer 270 is separated from the upper surface of the liquid crystal layer 270, And more.

A thin film transistor (not shown) and a color filter layer 232 are formed on the second substrate 220 and a polarizing layer 264 is formed on the inner surface of the first substrate 250 on which the thin film transistor and the color filter layer 232 are not formed It is possible to prevent the polarizing layer 264 from being deteriorated by the high temperature process for forming the thin film transistor (not shown) and the color filter layer 232 and as a result, to improve the stability and reliability of the polarizing layer 264 can do.

9 is a photograph of the luminance of the center region and the edge region of the liquid crystal display device according to the second embodiment of the present invention.

9, when a heavy rod F is placed on the liquid crystal display device 210 according to the second embodiment of the present invention to apply external pressure, a central region A1 (FIG. 2) farther from the seal pattern The amount of change in the phase delay due to the stress of the first and second substrates 250 and 220 becomes zero and the total phase delay does not increase so that light leakage does not occur but the edge area A2 close to the seal pattern 72, The amount of change in the phase delay due to the stress of the first and second substrates 250 and 220 increases to be greater than zero so that the total phase delay increases. The polarization layer formed on the inner surface of the first substrate 250 The polarization state change corresponding to the amount of change in the phase delay due to the stress of the first substrate 250 is removed to minimize the light leakage and the central region A1 and the edge region A2 exhibit similar brightness.

For example, in the case where no external pressure is applied, the central area A1 and the edge area A2 of the liquid crystal display device 210 displaying black all have a brightness of about 0.3 nit, while about 200 g, about 400 g, The central area A1 of the liquid crystal display device 210 for displaying black has a luminance of about 0.3 nit and the liquid crystal display device 210 for displaying black The edge region A2 has a luminance of about 0.64 nit, about 0.74 nit, and about 0.91 nit, respectively.

That is, the luminance values (about 0.64 nit, about 0.91 nit) of the edge area A1 when applying the external pressure are the luminance values of the conventional edge area A1 when applying the external pressure (about 0.91 nit, About 1.31 nits, about 1.82 nit), about 70%, about 56%, about 50%, and light leakage is minimized.

As described above, in the liquid crystal display device 210 according to the second embodiment of the present invention, the polarizing layer 264 of the in-cell type is formed on the inner surface of the first substrate 250, The polarized state immediately after passing through the first polarizer 262 can be restored to the polarized state immediately after passing through the first polarizer 262 (the polarization state just before passing through the first substrate 250) The light leakage can be minimized and the contrast ratio and display quality can be improved.

By forming the polarizing layer 264 of the in-cell type on the inner surface of the first substrate 250 closer to the backlight unit 280 than the second substrate 220, the color variation in the oblique viewing angle can be minimized .

In addition, by forming the polarizing layer 264 of the in-cell type on the inner surface of the first substrate 250 on which the thin film transistor and the color filter layer 232 are not formed, deterioration of the polarizing layer 264 by the high- It is possible to improve the stability and the reliability of the battery 264.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention as defined in the appended claims. It can be understood that

210: liquid crystal display device 250: first substrate
220: second substrate 270: liquid crystal layer
262: first polarizing plate 260: second polarizing plate
264: Polarizing layer

Claims (8)

First and second substrates spaced apart from each other;
A liquid crystal layer disposed between the first and second substrates;
First and second polarizers respectively disposed on outer surfaces of the first and second substrates;
A polarizing layer disposed on the inner surface of the first substrate and having a transmission axis identical to the transmission axis of the first polarizing plate,
And the liquid crystal display device.
The method according to claim 1,
And a backlight unit disposed below the first substrate.
The method according to claim 1,
Wherein the polarizing layer is an E-type in which an optical axis and a transmission axis are parallel to each other.
The method according to claim 1,
Wherein the polarizing layer is formed by a coating method.
The method according to claim 1,
A gate wiring and a data wiring arranged on the polarizing layer and defining a pixel region intersecting with each other;
A thin film transistor connected to the gate wiring and the data wiring;
A pixel electrode connected to the thin film transistor and disposed in the pixel region;
A common electrode disposed in the pixel region and spaced apart from the pixel electrode;
A column spacer disposed between the first and second substrates;
The liquid crystal display device further comprising:
6. The method of claim 5,
A color filter layer disposed above the pixel electrode and the common electrode;
A planarization layer disposed above the color filter layer,
The liquid crystal display device further comprising:
The method according to claim 1,
A gate wiring and a data wiring arranged on the inner surface of the second substrate and defining a pixel region intersecting with each other;
A thin film transistor connected to the gate wiring and the data wiring;
A pixel electrode connected to the thin film transistor and disposed in the pixel region;
A common electrode disposed in the pixel region and spaced apart from the pixel electrode;
A column spacer disposed between the first and second substrates;
The liquid crystal display device further comprising:
8. The method of claim 7,
A color filter layer disposed below the pixel electrode and the common electrode;
A planarization layer disposed under the color filter layer,
The liquid crystal display device further comprising:

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