KR101948172B1 - In-Plane switching mode liquid crystal display device - Google Patents

Abstract

The present invention provides a liquid crystal display comprising: a first substrate in which a common electrode and a pixel electrode are alternately arranged in a pixel region; A second substrate facing the first substrate; A liquid crystal layer interposed between the first and second substrates; And a color filter layer formed on an inner surface of the first substrate or the second substrate and consisting of red, green, and blue color filter patterns sequentially formed on the inner surface of the first substrate or the second substrate, And a liquid crystal display device having a liquid crystal display device having a liquid crystal display device.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a liquid crystal display (LCD)

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device and, more particularly, to a liquid crystal display device capable of suppressing a color shift phenomenon which is different in color by a viewing angle by controlling dispersion characteristics of a color filter layer, ≪ / RTI >

Generally, the driving principle of a liquid crystal display device utilizes the optical anisotropy and polarization properties of a liquid crystal. Since the liquid crystal has a long structure, it has a directionality in the arrangement of molecules, and the direction of the molecular arrangement can be controlled by artificially applying an electric field to the liquid crystal.

Therefore, when the molecular alignment direction of the liquid crystal is arbitrarily adjusted, the molecular arrangement of the liquid crystal is changed, and light is refracted in the molecular alignment direction of the liquid crystal by optical anisotropy, so that image information can be expressed.

An active matrix liquid crystal display (AM-LCD: hereinafter abbreviated as a liquid crystal display) in which a thin film transistor Tr and pixel electrodes connected to the thin film transistor Tr are arranged in a matrix manner, It has got the most attention because it has excellent implementation ability.

The liquid crystal display device includes a color filter substrate on which a common electrode is formed, an array substrate on which pixel electrodes are formed, and a liquid crystal interposed between the two substrates. In such a liquid crystal display device, The liquid crystal is driven to have excellent properties such as transmittance and aperture ratio.

However, liquid crystal driving by an electric field that is applied up and down has a drawback that the viewing angle characteristic is not excellent.

Therefore, a transverse electric field type liquid crystal display device having excellent viewing angle characteristics has been proposed to overcome the above disadvantages.

Hereinafter, a general transverse electric field type liquid crystal display device will be described in detail with reference to FIG.

1 is a cross-sectional view of a general transverse electric field type liquid crystal display device.

As shown in the figure, the upper substrate 9, which is a color filter substrate, and the lower substrate 10, which is an array substrate, are spaced apart from each other and face each other. A liquid crystal layer 11 is interposed between the upper and lower substrates 9, . Although not shown in the drawing, the outer surfaces of the lower and upper substrates 170 are provided with first and second polarizers having mutually perpendicular transmission axes.

The common electrode 17 and the pixel electrode 30 are alternately formed in each pixel region on the inner surface of the lower substrate 10. The inner surface of the upper substrate 9 is coated with red, And a color filter layer having a shape in which the color filter patterns representing the color filter patterns are sequentially and repeated. At this time, the liquid crystal layer 11 operates by the horizontal electric field L by the common electrode 17 and the pixel electrode 30, thereby realizing an image.

2A and 2B are cross-sectional views respectively showing the on and off states of a general transverse electric field type liquid crystal display device.

2A showing the alignment state of the liquid crystal in the ON state to which the voltage is applied, the phase of the liquid crystal 11a at the position corresponding to the common electrode 17 and the pixel electrode 30 is The liquid crystal 11b located between the common electrode 17 and the pixel electrode 30 is formed by a horizontal electric field L formed by applying a voltage between the common electrode 17 and the pixel electrode 30, And arranged in the same direction as the horizontal electric field (L). That is, in the transverse electric field type liquid crystal display device, since the liquid crystals 11a and 11b operate by the horizontal electric field, the viewing angle becomes wide.

Therefore, when viewing the transverse electric-field liquid crystal display device from the front, the display image can be viewed without difficulty even in the direction of about 80 to 89 degrees in the up / down / left / right directions.

2B, a horizontal electric field is not formed between the common electrode 17 and the pixel electrode 30 because the liquid crystal display device is in an off state in which no voltage is applied to the liquid crystal display device. Therefore, The array status does not change.

However, in the transverse electric field type liquid crystal display device having the above-described configuration, a color shift phenomenon occurs in which the hue is reversed at a specific viewing angle due to the positive (or reverse) dispersion characteristic of the liquid crystal.

A compensating film is further provided between the first polarizing plate and the lower substrate or between the second polarizing plate and the upper substrate in order to suppress the color shift phenomenon due to the positive (or reverse) dispersion characteristics of the liquid crystal.

When the compensating film is provided, the transverse electric field liquid crystal display device can reduce the color shift phenomenon due to a change in the viewing angle to some extent. Even if the compensating film is further included, the compensation film itself has a dispersion characteristic for light The effect is very small. Therefore, a means for effectively suppressing the color shift phenomenon due to the viewing angle change is needed.

Disclosure of the Invention The present invention has been conceived to solve the problems of such a conventional transverse electric field liquid crystal display device, and it is an object of the present invention to provide a transverse electric field liquid crystal display device capable of fundamentally suppressing a color shift phenomenon due to a positive And an object thereof is to provide a device.

According to an aspect of the present invention, there is provided a transverse electric field type liquid crystal display comprising: a first substrate having a common electrode and a pixel electrode arranged alternately in a pixel region; A second substrate facing the first substrate; A liquid crystal layer interposed between the first and second substrates; And a color filter layer formed on an inner surface of the first substrate or the second substrate and consisting of red, green, and blue color filter patterns sequentially formed on the inner surface of the first substrate or the second substrate, wherein the color filter layer has a thickness of from -30 to -5 nm or +5 to + .

When the liquid crystal layer has a positive dispersion characteristic, the color filter layer has a retardation value of -30 to -5 nm so as to have a reverse dispersion characteristic, and when the liquid crystal layer has a reverse dispersion characteristic, And has a retardation value of +5 to +30 nm.

Further, the color filter layer has a retardation value different for each of the red, green and blue color filter patterns.

The outer surfaces of the first and second substrates are provided with first and second polarizers having transmission axes perpendicular to each other. At this time, a compensation film is provided between the first substrate and the first polarizing plate or between the second substrate and the second polarizing plate.

When the liquid crystal layer and the compensation film have a positive dispersion characteristic, the color filter layer has a retardation value of -30 to -5 nm so as to have a reverse dispersion characteristic, and the liquid crystal layer and the compensation film have a reverse dispersion characteristic The color filter layer has a retardation value of +5 to +30 nm so as to have a positive dispersion property.

When the liquid crystal layer and the compensating film have a positive dispersion characteristic, the color filter layer has a reverse dispersion characteristic or a mixed dispersion characteristic in which a normal dispersion and a reverse dispersion are mixed, and the liquid crystal layer and the compensation film have a reverse dispersion characteristic The color filter layer has a mixed dispersion characteristic in which a normal dispersion characteristic or a normal dispersion and a reverse dispersion are mixed. At this time, the reason why the color filter layer forms the mixed dispersion characteristic is that the color filter layer The color filter pattern of at least one color has a retardation value of -30 to -5 nm and the color filter pattern of the remaining color has a retardation value of +5 to +30 nm.

The color filter layer may be formed of a color filter material including a coloring pigment, a binder, and an additive. The binder may be formed of an acrylate-based material, and the additive may be a silicone or florine-based material. to be.

The transverse electric field type liquid crystal display device according to the present invention is characterized in that each of the red, green and blue color filter patterns of the color filter layer formed in the liquid crystal panel has a retardation value of about -30 nm to +30 nm, By offsetting the dispersion characteristics, it is possible to stabilize the dispersion characteristics of the entire transverse electric field liquid crystal display device and to suppress the color shift phenomenon at a specific viewing angle.

In addition, there is an effect of minimizing light leakage that unwanted light leaks due to stabilization of dispersion characteristics.

1 is a cross-sectional view schematically showing a part of a general transverse electric field type liquid crystal display device.
FIGS. 2A and 2B are cross-sectional views respectively showing the on and off states of a general transverse electric field liquid crystal display device;
3 is a cross-sectional view of a portion of a display region of a transverse electric field type liquid crystal display device according to an embodiment of the present invention.
4A, 4B and 4C are views showing positions of light passing through a liquid crystal display device according to an embodiment of the present invention on a porcelain sphere;
5A and 5B are cross-sectional views of a part of a display region of a transverse electric field type liquid crystal display device according to first and second modified examples of the embodiment of the present invention, respectively.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

3 is a cross-sectional view of a portion of a display region of a transverse electric field type liquid crystal display device according to an embodiment of the present invention. For convenience of description, a region in which the thin film transistor Tr as a switching element is formed in each pixel region P is defined as a switching region TrA.

The transverse electric field type liquid crystal display 100 according to the embodiment of the present invention has a plurality of pixel regions P defined therein and a common electrode 165 and a pixel electrode 162 are formed in each pixel region P Green, and blue color filter patterns 175a, 175b, and 175c are successively formed on each pixel region P corresponding to the lower substrate 102 having the thin film transistor Tr, A liquid crystal panel 103 including an upper substrate 170 provided with a color filter layer 175 having a repetitive shape and a liquid crystal layer 190 interposed between the two substrates; And first and second polarizers 193 and 195 having transmission axes perpendicular to each other are provided on the side surfaces.

Referring to the structure of the lower substrate 102, a gate wiring (not shown) extending in one direction is formed on a first substrate 101 made of a transparent insulating material forming a base, (Not shown) are formed so as to be spaced apart from each other in parallel with each other.

At this time, in the switching region TrA, the gate electrode 106, which is branched from the gate wiring (not shown) or is part of the gate wiring (not shown), is formed on the first substrate 101 .

An outermost common electrode 116 is formed in each pixel region P on the first substrate 101 by branching from the common wiring (not shown) and adjacent to the data wiring 130.

Next, an inorganic insulating material such as silicon oxide (SiO ₂ ) or silicon nitride (SiO ₂ ) is formed on the entire surface of the gate wiring (not shown), the gate electrode 106, the common wiring (not shown) and the outermost common electrode 116 A gate insulating film 119 made of SiNx is formed.

An active layer 120a made of pure amorphous silicon and a semiconductor layer 120 composed of an ohmic contact layer 120b made of impurity amorphous silicon are formed in the switching region TrA above the gate insulating layer 119. [

A data line 130 is formed on the gate insulating layer 119 to intersect the gate line (not shown) to define a pixel region P, and the semiconductor layer 120 is formed in the switching region TrA. A source electrode 133 branched from the data line 130 is formed and a drain electrode 136 is formed apart from the source electrode 133. [

At this time, the gate electrode 106, the gate insulating film 119, the semiconductor layer 120, and the source and drain electrodes 133 and 136, which are sequentially stacked in the switching region TrA, ).

Next, the data line 130 and the source and drain electrodes (133, 136) over the inorganic insulating material, such as silicon oxide (SiO ₂₎ or made or silicon nitride (SiNx), or an organic insulating material, for example, picture A protective layer 145 made of photo acryl or benzocyclobutene (BCB) is formed. In the drawing, a protective layer 145 having a flat surface is formed by an organic insulating material.

The protective layer 145 is formed with a common contact hole (not shown) exposing one end of the outermost common electrode 116 and a drain contact 136 exposing the drain electrode 136 of each thin film transistor Tr A hole 149 is formed.

Then, a transparent conductive material such as indium-tin-oxide (ITO) is formed on the passivation layer 145 having the common contact hole (not shown) and the drain contact hole 149 corresponding to the pixel regions P, ) Or indium-zinc-oxide (IZO), or a conductive material such as molybdenum (Mo) or molybdenum (MoTi), and is electrically connected to the outermost common electrode 116 through the common contact hole (Not shown) in parallel with the gate wiring (not shown), and is branched from the auxiliary common pattern (not shown) to be spaced apart from each other in parallel to the data wiring 130, A common electrode 165 is formed.

The auxiliary common pattern (not shown) is formed on the passivation layer 145 in each pixel region P and is electrically connected to the drain electrode 136 through the drain contact hole 149. (Not shown) extending in parallel with the plurality of central common electrodes 165. The auxiliary pixel patterns 161 extend in parallel with the gate lines (not shown) And a plurality of pixel electrodes 162 are alternately formed.

Although not shown in the figure, the data lines 130 and the plurality of common electrodes 116 and 165 and the pixel electrodes 162 formed in parallel with the data lines 130 are formed in the pixel region P The center portion may be formed to be bent and to be symmetrical up and down, or may be formed to have a linear bar shape.

When the data line 130, the pixel electrode 162, and the common electrodes 116 and 165 are formed so as to be offset from the center of each pixel region P, each pixel region P forms a double domain And is more effective in suppressing a color shift phenomenon due to a change in viewing angle than in the case of forming a single domain.

A first polarizer 193 having a first transmission axis is attached to the outer surface of the lower substrate 102 having such a configuration.

The structure of the upper substrate 170 corresponding to the lower substrate 102 having the above-described structure will be described. In the inner surface of the second substrate 171 having a transparent and insulating characteristic, And a black matrix 173 corresponding to the black matrix 173 is provided.

The red, green, and blue color filter patterns 175a and 175b and 175c are provided corresponding to the pixel regions P captured by the black matrix 173 on the black matrix 173 And a color filter layer 175 are formed.

The color filter layer 175 is characterized by having a retardation value of about -30 to -5 nm or about +5 to +30 nm in the transverse electric field type liquid crystal display device 100 according to the embodiment of the present invention to be.

At this time, the red, green and blue color filter patterns 175a, 175b and 175c of the color filter layer 175 have different retardation values in the range of -30 to -5 nm or +5 to +30 nm, More preferably, This is because the red, green, and blue lights have different wavelengths, and when they pass through the color filter layer 175, they have different retardation values due to differences in wavelength values.

In order to make the color filter layer 175 have a retardation value of about -30 to -5 nm or +5 to +30 nm, it is possible to adjust the content ratio of the constituent elements of the color filter layer 175.

The color filter material constituting the color filter layer comprises a pigment, a binder, and an additive, which are largely colored. In the characteristics of the present invention, the retardation value is from -30 to - 5 nm or +5 to +30 nm, the binder is made of acrylate, and the additive is preferably a silicon or flourine-based material.

If the liquid crystal layer 190 has a positive dispersion characteristic in the liquid crystal display device 100 according to another exemplary embodiment of the present invention, the color filter layer 175 may have a reverse dispersion characteristic And the retardation value has a retardation value of about -30 to -5 nm. When the liquid crystal layer 190 has a reverse dispersion characteristic, the color filter layer 175 has the retardation value And has a retardation value of +5 to +30 nm.

In this case, the red, green, and blue color filter patterns 175a and 175b and 175c may be formed to have different retardation values.

The constant dispersion characteristic is a characteristic that the refractive index gradually decreases as the wavelength becomes longer in inverse proportion to the wavelength of the light. Conversely, the reverse dispersion characteristic means that as the wavelength becomes longer in proportion to the wavelength of the light, And the refractive index gradually increases in size.

Next, an overcoat layer 180 covering the color filter layer 175 having the above-described structure and having a flat surface is formed.

A second polarizer 195 having a second transmission axis perpendicular to the first transmission axis is provided on the outer surface of the upper substrate 170 having the above-described structure.

Although the color filter layer 175 is formed on the inner surface of the upper substrate 170 in the drawing, the color filter layer 175 may be formed on the lower substrate 102. In this case, The color filter layer 175 may be formed on the passivation layer 145 and the center common electrode 165 and the pixel electrode 162 may be formed on the color filter layer 175.

In this case, the overcoat layer 180 covering the color filter layer 175 on the upper substrate 170 is omitted.

In the transverse electric field type liquid crystal display device 100 according to the embodiment of the present invention having the above-described structure, the color filter layer 175 is formed on the liquid crystal layer 190 -30 to -5 nm or +5 to +30 nm in order to have a dispersion characteristic in the direction of canceling the dispersibility of the liquid crystal layer 190, There is an effect of essentially canceling the color shift phenomenon that occurs.

4A, 4B, and 4C are views showing positions of light passing through a liquid crystal display device according to an exemplary embodiment of the present invention on a porcelain sphere, and are shown for each of red, green, and blue, and a color filter layer has a retardation value Green, and blue as a comparative example. At this time, in each drawing, target positions where red, green, and blue are ideally implemented are also shown.

Referring to FIG. 4A, the red color filter of the transverse electric field type liquid crystal display device according to the present invention, based on the red target position (the position of the red light in the corrugation that is ideally represented when there is no dispersion characteristic of the component) The red light passing through the pattern of the comparative example having the general color filter layer not having the retardation value is reflected at the first interval Lt; RTI ID = 0.0 > second < / RTI >

4B and 4C, the rust and blue light passing through the transverse electric field type liquid crystal display device according to the embodiment of the present invention on the porcelain sphere is also mixed with the rust and blue light passing through the transverse electric field liquid crystal display device according to the comparative example It can be seen that each of the light contrasts is located closer to the target position (the position on the Poincare sphere of green and blue light ideally appearing when there is no dispersion characteristic of the component).

Therefore, in the transverse electric field type liquid crystal display device according to the embodiment of the present invention, light of red, green, and blue having different wave lengths from each other on a Poincare sphere is generated through a transverse electric field type liquid crystal display It can be seen that the generation of light leakage is reduced by being formed close to ideal target positions of red, green, and blue light contrasts, and that the light leakage of each red, green and blue light is reduced, Therefore, it is possible to effectively suppress other color shifts due to changes in the viewing angle.

5A and 5B are cross-sectional views of a portion of a display region of a transverse electric field type liquid crystal display device according to the first and second modified examples of the embodiment of the present invention, wherein the same constituent elements as those of the embodiment are given the same reference numerals. In the description of the components of the first and second modified examples, the same components as those of the first embodiment and the second modified example are not described, and the differences will be mainly described.

In the transverse electric field type liquid crystal display devices 200 and 300 according to the first and second modified examples, the first polarizing plate 193, the lower substrate 102 or the upper substrate 170 and the second polarizing plate And a compensating film 210 is further provided between the two films 195.

The compensation film 210 may be formed of, for example, a quater wave plate (QWP) phase plate, a quartz wave plate (QWP) Or a half wave plate (HWP) phase plate.

The compensating film 210 is provided between the lower substrate 102 and the first polarizing plate 193 and the compensating film 210 is provided between the upper substrate 170 and the second polarizing plate 193. In this case, 195).

In the transverse electric field type liquid crystal display devices 200 and 300 according to the first and second modified examples having such a configuration, the color filter layer 175 formed inside the liquid crystal panel 103 is not only the liquid crystal layer 190, Is formed to have a retardation value of -30 to -5 nm or +5 to +30 nm in consideration of the dispersion characteristic of the compensation film 210.

In this case, when the dispersion characteristics of the liquid crystal layer 190 and the compensating film 210 have a reverse dispersion characteristic, the color filter layer 175 is formed to have a retardation value of +5 to +30 nm so as to have a positive dispersion characteristic, When the dispersion characteristics of the liquid crystal layer 190 and the compensating film 210 have a positive dispersion characteristic, the color filter layer 175 is formed to have a retardation value of -30 to -5 nm.

Considering the dispersion characteristics of the liquid crystal layer 190 and the compensating film 210, the liquid crystal layer 190 and the compensating film 210 are entirely (or reversely) reversed by changing the wavelength band of red, ) Dispersion characteristic, an inverse (or positive) dispersion characteristic may be obtained for light of a specific color.

In this case, among the red, green, and blue color filter patterns 175a, 175b, and 175c, a color filter pattern corresponding to light having a positive (or inverse) dispersion characteristic with respect to the liquid crystal layer 190 and the compensation film 210 (Or reverse) dispersion characteristics with respect to light having an inverse (or positive) dispersion characteristic, the color filter layer 175 has a positive dispersion characteristic and a reverse dispersion characteristic as a whole, Characteristics may be designed to have mixed dispersion characteristics.

For example, when it is assumed that the dispersion characteristics of the liquid crystal layer 190 and the compensation film 210 have a static dispersion characteristic for light in the red and green wavelength ranges and a reverse dispersion characteristic for the light in the blue wavelength range, The patterns 175a and 175b are configured to have a retardation value of -30 to -5 nm so as to obtain a reverse dispersion characteristic and a retardation value of +5 to +30 nm is formed to have a positive dispersion characteristic for the blue color filter pattern 175c The color filter layer 175 may be formed to have mixed dispersion characteristics.

The components other than the color filter layer and the compensating film described above are the same as those of the transverse electric field type liquid crystal display device according to the first embodiment described above, and the description thereof will be omitted.

The present invention is not limited to the above-described embodiments and modifications, and various modifications may be made without departing from the gist of the present invention.

100: transverse electric field type liquid crystal display device 101: first substrate
102: lower substrate 103: liquid crystal panel
106: gate electrode 116: outermost common electrode
119: Gate insulating film 120: Semiconductor layer
120a: active layer 120b: ohmic contact layer
130: data line 133: source electrode
136: drain electrode 145: protective layer
149: drain contact hole 161: auxiliary pixel pattern
162: pixel electrode 165: central common electrode
170: upper substrate 171: second electrode
173: Black matrix 175: Color filter layer
175a, 175b, and 175c: red, green, and blue color filter patterns
180: overcoat layer 190: liquid crystal layer
193: first polarizer 195: second polarizer
P: pixel region Tr: thin film transistor
TrA: switching area

Claims (9)

A first substrate having a common electrode and a pixel electrode arranged alternately in a pixel region;
A second substrate facing the first substrate;
A liquid crystal layer interposed between inner surfaces of the first and second substrates;
A color filter layer formed on an inner surface of the first substrate or the second substrate and having a red, green, and blue color filter pattern sequentially formed thereon;
First and second polarizers respectively disposed on outer surfaces of the first and second substrates;
And a compensation film disposed on at least one side between the first substrate and the first polarizer, and between the second substrate and the second polarizer,
When the liquid crystal layer and the compensating film have a positive dispersion characteristic, the color filter layer has a mixed dispersion characteristic in which a reverse dispersion characteristic or a mixture of normal dispersion and reverse dispersion is mixed, and the liquid crystal layer and the compensation film have a reverse dispersion characteristic, Wherein the color filter layer has a mixed dispersion characteristic in which a static dispersion property or a mixture of a normal dispersion and a reverse dispersion is mixed.
delete delete delete delete The method according to claim 1,
When the liquid crystal layer and the compensating film have a positive dispersion characteristic, the color filter layer has a retardation value of -30 to -5 nm so as to have antistatic properties,
And the color filter layer has a retardation value of +5 to +30 nm so as to have a positive dispersion characteristic when the liquid crystal layer and the compensation film have a reverse dispersion property.
delete The method according to claim 1,
Wherein the color filter pattern of at least one of the red, green and blue color filter patterns has a retardation value of -30 to -5 nm and the color filter pattern of the remaining color has a retardation value of +5 to +5 nm, And has a retardation value of 30 nm.
The method according to claim 1,
Wherein the color filter layer comprises a color filter material comprising a coloring pigment, a binder and an additive, wherein the binder is comprised of an acrylate-based material and the additive is a silicone or florine-based material Electric field type liquid crystal display device.

Images