KR20120132214A - Liquid crystal display panel - Google Patents

Abstract

PURPOSE: A liquid crystal display panel is provided to maintain liquid crystalline orientation while improving DC afterimages through a first photo-aligning layer. CONSTITUTION: A liquid crystal display panel comprises: a color filter substrate which comprises a color filter, a black matrix, and a common electrode; a thin film transistor board which comprises a pixel electrode and a thin film transistor and is bind with the color filter substrate around a liquid crystal; and photo-aligning layers consisting of a first photo-aligning layer and a second photo-aligning layer(134,154) and formed on the color filter substrate and the thin film transistor substrate respectively. The first photo-aligning layer comprises a compound indicated in chemical formula 1.

Description

Liquid crystal display panel {LIQUID CRYSTAL DISPLAY PANEL}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display panel, and more particularly, to a liquid crystal display panel capable of increasing surface energy to solve an afterimage of an optical alignment layer.

Display devices for displaying images include cathode ray tubes, liquid crystal displays (LCDs), plasma display panels (PDPs), electroluminescent display devices (ELDs), organic There are various types, such as a light emitting display device.

In general, a liquid crystal display (LCD) displays an image by allowing each of the liquid crystal cells arranged in a matrix form on a liquid crystal display panel to adjust light transmittance according to a video signal.

Here, the liquid crystal display panel includes a thin film transistor substrate and a color filter substrate that are bonded by a binder with a liquid crystal interposed therebetween.

In the color filter substrate, a black matrix for preventing light leakage, a color filter for implementing color, a common electrode forming a vertical electric field with the pixel electrode, and an upper alignment layer coated for liquid crystal alignment are formed thereon.

The thin film transistor substrate includes a gate line and a data line intersecting each other on a lower substrate, a thin film transistor (TFT) formed at an intersection thereof, a pixel electrode connected to the thin film transistor, and a liquid crystal alignment thereon. The applied lower alignment layer is formed.

The upper and lower alignment layers use a rubbing orientation method to make the surface of the alignment layer have a constant orientation. The rubbing orientation method is a method of aligning an organic polymer in a predetermined direction by coating the organic polymer on a substrate in the form of a thin film and then rotating the rubbing roll wound with a rubbing cloth to rub the organic polymer. However, this rubbing orientation method has a bad effect such as rubbing of thin film transistor elements due to the generation of dirt and static electricity during rubbing in a mechanical contact with the substrate. In addition, as the panel sizes are opposed, the rubbing method makes it difficult to apply a uniform alignment agent on the surface of the panel and adversely affects high definition.

In order to solve such a problem, the photo-alignment method by the linearly polarized light irradiation of an ultraviolet range has attracted attention as an orientation method of the liquid crystal which does not perform a rubbing process in recent years. Here, the photo-alignment method uses the principle that when the ultraviolet rays are irradiated perpendicularly to the surface of the alignment layer using a specific linear polarization for a predetermined period of time, the functional groups on the surface of the alignment layer undergo structural changes through reactions such as polymerization and decomposition to align the liquid crystals. . By using this method, unlike the existing rubbing orientation method, the process time is short, the orientation is possible regardless of the size of the mother glass, and the pretilt angle of the alignment layer is easily adjusted, and thus it can be applied to various modes. However, the photo-alignment method has a lower surface energy (anchoring energy) than the rubbing alignment method, which becomes the afterimage source. Accordingly, there is a need for a photo-alignment film capable of raising the surface energy to solve the afterimage.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and in particular, to provide a liquid crystal display panel having an optical alignment film that can solve the afterimage of the optical alignment film by increasing the surface energy.

의 화합물을 포함하여 이루어진 것을 특징으로 한다. (여기서, n= 0 이상의 자연수, m= 1 이상의 자연수)To this end, the liquid crystal display panel according to the present invention includes an R, G, B color filter for realizing color, a black matrix for dividing a pixel region in which the color filter is to be formed, a color filter substrate including a common electrode, and A first light is formed on each of the color filter substrate and the thin film transistor substrate, the thin film transistor substrate including a thin film transistor and a pixel electrode connected to the color filter substrate and a liquid crystal interposed therebetween, and formed on each of the color filter substrate and the thin film transistor substrate. An alignment film comprising an alignment film and a second optical alignment film for improving surface anisotropy of the alignment film, wherein the first optical alignment film

It characterized by comprising a compound of. Where n = 0 or more natural, m = 1 or more natural)

In addition, the substituent R in [Formula 1] may be formed of a macrocyclic compound consisting of at least two or more rings of the following compounds B-1 to B-5, wherein the macrocyclic compound is a ring compound containing a hetero atom It is characterized by that.

,

,

,

,

             B-1 B-2

,

,

,

,

             B-3 B-4

             B-5

The liquid crystal display panel according to the present invention includes an upper and lower alignment layer composed of a first optical alignment layer for resolving DC afterimage, and a second optical direction layer for improving surface anisotropy of the optical alignment layer.

In this case, the first photoalignment layer uses a photoalignment layer having a macrocyclic compound to realize π-electron delocalization between the liquid crystal molecules and the alignment layer to increase the surface energy and to resolve the afterimage due to the increase of the surface energy.

In addition, the second optical alignment layer maintains uniform liquid crystal alignment by using a material capable of improving the surface anisotropy of the optical alignment layer.

As described above, the present invention can maintain uniform liquid crystal alignment through the second photoalignment layer while resolving the DC afterimage through the first photoalignment layer.

1 is a perspective view illustrating a liquid crystal display panel according to an exemplary embodiment of the present invention.
FIG. 2 is a cross-sectional view of the liquid crystal display panel illustrated in FIG. 1.
FIG. 3 is a graph showing a trade off relationship between DC afterimage and surface anisotropy of an optical alignment layer.
4A to 4C are chemical formulas for explaining π electron delocalization according to the present invention, and FIGS. 4A and 4B show a chemical formula of a conventional photoalignment film, and FIG. 4C shows a chemical formula of a photoalignment film of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The configuration of the present invention and the operation and effect thereof will be clearly understood through the following detailed description. Before describing the present invention in detail, the same components are denoted by the same reference symbols as possible even if they are displayed on different drawings. In the case where it is judged that the gist of the present invention may be blurred to a known configuration, do.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to FIGS. 1 to 4C.

1 is a perspective view illustrating a liquid crystal display panel according to an exemplary embodiment of the present invention, and FIG. 2 is a cross-sectional view of the liquid crystal display panel illustrated in FIG. 1.

1 and 2, the liquid crystal display panel includes a color filter substrate 140 and a thin film transistor substrate 100 bonded together with a liquid crystal interposed therebetween.

The color filter substrate 140 includes a black matrix 142, a color filter 144, a planarization layer 146, a common electrode 148, and an upper alignment layer 150 formed on the upper substrate 141.

The color filter 144 includes red, green, and blue color filters R, G, and B to implement color. The red, green, and blue color filters R, G, and B each absorb or transmit light of a specific wavelength through the red, green, and blue pigments they contain, thereby making them red, green, and blue.

The black matrix 142 is formed to distinguish the pixel region in which the color filter 144 is to be formed and to overlap the gate line, the data line, and the thin film transistor of the thin film transistor substrate 100. The black matrix 142 blocks the transmitted light generated by the undesired liquid crystal array to improve the contrast of the liquid crystal display device and prevents light leakage current of the thin film transistor by blocking direct light irradiation to the thin film transistor.

The common electrode 176 supplies a common voltage as a reference when driving the liquid crystal to the transparent conductive layer. As shown in FIGS. 1 and 2, the display panel is provided with twisted nematics for installing electrodes 120, 322, and 176 on two substrates, arranging the liquid crystal directors to be twisted by 90 °, and then driving a liquid crystal director by applying voltage to the electrodes. -Nemaitc (TN) method, IPS (In-Plane Swiching) mode for forming two electrodes on one substrate and adjusting the director of the liquid crystal with a horizontal electric field generated between the two electrodes, forming two electrodes as transparent conductors While forming a narrow gap between the two electrodes to operate the liquid crystal molecules by the fringe field formed between the two electrodes can be used a method such as the FFS (Fringe Field Swiching) mode, but is not limited thereto.

The planarization layer 146 is formed on the color filter 144 and the black matrix 142 to planarize the surface of the upper substrate 141.

The thin film transistor substrate 100 includes a thin film transistor (TFT), a pixel electrode 122, and a lower alignment layer 130 formed in each pixel region defined by the intersection of the gate line 106 and the data line 104 on the lower substrate 101. Include.

The thin film transistor supplies the video signal of the data line to the pixel electrode 122 in response to the scan signal supplied to the gate line 106. To this end, the thin film transistor TFT is positioned to face the gate electrode 102 connected to the gate line 106, the source electrode 108 connected to the data line 104, and the source electrode 108 to face the pixel electrode ( An active layer 114 which is formed to overlap the gate electrode 102 with the drain electrode 110 and the gate insulating layer 112 connected to the 122, and forms a channel between the source electrode 108 and the drain electrode 110. ) And an ohmic contact layer 116 formed on the active layer except for the channel region for ohmic contact with the source electrode 108 and the drain electrode 110.

The pixel electrode 122 is connected to the drain electrode 110 of the main thin film transistor TFT through the contact hole 120 and is formed on the passivation layer 118. The pixel electrode 122 is formed of a transparent conductive layer. Here, when the video signal is supplied through the main thin film transistor TFT, the pixel electrode 122 generates an electric field together with the common electrode 148 supplied with the common voltage, thereby forming the liquid crystal molecules 160 between the two electrodes 122 and 148. The direction of the array is changed and thus the light transmittance passing through the liquid crystal molecules 160 is changed, thereby gray scale is realized.

The passivation layer 118 protects the data line 104 and the thin film transistor TFT formed between the thin film transistor TFT and the pixel electrode 122. The protective layer 118 may be formed of a double layer of an inorganic and an organic protective layer or a single layer in which only one of them is formed.

The upper and lower photoalignment layers 130 and 150 determine the alignment direction of the liquid crystal 160 formed between the thin film transistor substrate 100 and the color filter substrate 140. That is, the liquid crystal 160 is a core material of driving the liquid crystal to uniformly align the liquid crystal in one direction so that the liquid crystal 160 can perform a role of a polarizer of the light well. The characteristics influence the display quality of the liquid crystal display panel. The upper alignment layer 150 is formed on the upper substrate 141 on which the black matrix 142, the color filter 144, and the common electrode 148 are formed, and the lower alignment layer 130 is a thin film transistor TFT and a pixel electrode ( 122 is formed on the formed lower substrate 101.

Here, the upper and lower alignment layers 130 and 150 are formed using a photoalignment material. The photo-alignment material includes a polymer having a photoreactor, and irradiates polarized ultraviolet rays to the polymer film to induce a photoreaction, thereby making the polymer film anisotropic. Each of the upper and lower photo-alignment films 130 and 150 is DC. First optical alignment layers 132 and 152 for resolving afterimages and second optical alignment layers 134 and 154 for improving surface anisotropy of the optical alignment layers.

The first photoalignment layers 132 and 152 may use a photoalignment material represented by the following [Formula 1].

)은 벤젠(bezene)일 수 있으며, 헤테로 원자(Hetero atom)가 치환된 고리 화합물일 수도 있으며, 다수개의 고리 화합물이 연속으로 직접 또는 간접적으로 연결된 화합물일 수 있다. 고리 화합물과 고리 화합물 사이는 하나 또는 다수 개의 알킬기 사슬(alkyl chain)로 이어져 있을 수 있으며, 알킬기 사슬(alkyl chain) 사이에는 헤테로 원자(hetero atom)로 치환될 수 있다. Ring part represented by R in [Formula 1] (

) May be benzene, may be a ring compound substituted with a hetero atom, a plurality of ring compounds may be a compound directly or indirectly connected in series. The ring compound and the ring compound may be connected to one or more alkyl chains, and may be substituted with a hetero atom between the alkyl chains.

In [Formula 1] n, m is one or more natural numbers, n may be 0, but m may not be 0.

)은 하기 화합물(A-1 내지 A-5) 중 어느 하나일 수 있다. In addition, a ring portion (R) represented by R in [Formula 1] (

) May be any one of the following compounds (A-1 to A-5).

,

,

,

,

,

,

         A-1 A-2, A-3

,

,

A-4 A-5

In addition, the substituent R in [Formula 1] may be formed of a macrocyclic compound consisting of at least two or more rings of the following compounds (B-1 to B-5), the macrocyclic compound includes all hetero atoms It may be a ring compound.

,

,

,

,

             B-1 B-2

,

,

,

,

             B-3 B-4

             B-5

As described above, the first photoalignment layers 132 and 152 of the present invention are represented by the above-mentioned [Formula 1], and DC residual image can be solved by introducing a macrocyclic compound in [Formula 1].

Specifically, in the photo-alignment method, a uniform orientation can be performed regardless of the size of the mother substrate, but an afterimage phenomenon affecting the image quality becomes a problem. The afterimage is caused by the direct current generated inside the panel and is associated with the material problem of the photoalignment film. That is, when a DC voltage is applied to the liquid crystal, impurities in the liquid crystal layer are ionized so that + ions are stacked on the alignment film of the-electrode, and-ions are stacked on the alignment film of the + electrode, and are adsorbed onto the alignment film over time. Even if the DC voltage applied from the outside is removed, the ions adsorbed on the alignment layer diffuse into the liquid crystal layer and combine with the ions having the opposite polarity to generate the residual DC voltage. In order to reduce the DC afterimage, the surface energy should be large. That is, the photo-alignment film has a low surface energy, which causes an afterimage problem.

Accordingly, the first photoalignment layers 132 and 152 of the present invention can introduce surface energy by introducing a macrocyclic compound having a plurality of π electrons in [Formula 1]. To explain this, by introducing a macrocyclic compound having a large number of π electrons in [Formula 1] to induce a strong π-π electron delocalization between the liquid crystal molecules and the alignment layer to increase the surface energy.

In other words, in the photo-alignment method, the orientation of the liquid crystal molecules is controlled only by the chemical interaction between the liquid crystal molecules and the alignment layer, thereby lowering the surface energy, which causes afterimages. The first photo-alignment layers 132 and 152 of the present invention form macrocyclic compounds. This induces strong π-π interaction between the liquid crystal molecules and the alignment layer, thereby increasing the surface energy. In this way, the problem of afterimage is solved by increasing the surface energy.

In addition, the first optical alignment layers 132 and 152 of the present invention are positioned under the second optical alignment layers 134 and 154. This is to subtract the DC afterimage to the bottom. That is, the DC afterimage is solved by pulling out the adsorbed ions downward. In addition, the first optical alignment layers 132 and 152 may increase the direction of the chain through a rigid property due to the structure of the macrocyclic compound. Accordingly, the liquid crystal array can be improved.

As described above, the first photoalignment layers 132 and 152 of the present invention may implement π electron delocalization by introducing a macrocyclic compound to increase surface energy and improve liquid crystal alignment.

4A to 4C, the π electron delocalization according to the present invention will be described. 4C is an embodiment of the first photoalignment layer to which the [Formula 1] of the present invention is applied, and is not limited to the compound including the chemical formula shown in FIG. 4C.

4B and 4C are chemical formulas showing conventional optical alignment layers. The chemical formula shown in FIG. 4A does not delocalize the benzene ring and the part (A region; not conjugated) connected to the benzene ring, and the chemical formula shown in FIG. 4B shows the part (B region; Partially conjugated) where the benzene ring and benzene ring are connected. Is partially delocalized by the introduction of oxygen between the benzene ring and the benzene ring. As such, the partial delocalization, as shown in the chemical formula of FIG. 4A, and the partial delocalization, as shown in the chemical formula of FIG. 4B, may not improve the afterimage property because of low surface energy of the photoalignment layer.

However, in the present invention, as shown in Fig. 4c, the benzene ring and the portion (C region; conjugated) to which the benzene ring is connected are? Electron delocalized. As described above, in the first photoalignment layers 132 and 152 of the present invention, the surface energy may be increased by delocalizing π electrons between the benzene ring and the benzene ring.

The second photoalignment layers 134 and 154 may be made of a material capable of maintaining uniform liquid crystal alignment of the photoalignment layer. In general, the photo-alignment film has a trade-off relationship as shown in FIG. 3. Referring to the graph illustrated in FIG. 3, surface anisotropy becomes a problem as the DC afterimage is solved, and DC afterimage becomes a problem as the surface anisotropy is solved. According to such a characteristic, the first optical alignment layers 132 and 152 of the present invention solve the DC afterimage, and the second optical alignment layers 134 and 154 are formed of a material having good liquid crystal alignment property to maintain uniform liquid crystal alignment.

In this case, each of the upper and lower photoalignment layers 130 and 150 is composed of two layers, the first and second photoalignment layers 132, 134, 152 and 154, wherein each of the upper and lower alignment layers 130 and 150 is coated with one layer and then UV is applied. The first and second optical alignment layers 132, 134, 152 and 154 may be separated into two layers, and the second light having a good liquid crystal orientation and a material of the first optical alignment layers 132 and 152 having a macrocyclic compound in [Formula 1]. The materials of the alignment layers 134 and 154 may be coated, respectively, to form two layers. That is, after applying the material of the first photoalignment layer (132,152), the second photoalignment layer (134,154) may be applied thereon to form the upper and lower alignment layer (130,150) consisting of two layers.

Accordingly, the upper and lower photoalignment layers 130 and 150 of the present invention may maintain uniform liquid crystal alignment through the second photoalignment layers 134 and 154 while resolving DC afterimages through the first photoalignment layers 132 and 152.

The foregoing description is merely illustrative of the present invention, and various modifications may be made by those skilled in the art without departing from the spirit of the present invention. Accordingly, the embodiments disclosed in the specification of the present invention are not intended to limit the present invention. The scope of the present invention should be construed according to the following claims, and all the techniques within the scope of equivalents should be construed as being included in the scope of the present invention.

101: lower substrate 102: gate electrode
104: data line 106: gate line
108: source electrode 110: drain electrode
112 gate insulating film 114 active layer
116: ohmic contact layer 118: protective film
122: pixel electrode 130: upper alignment layer
132,152: first alignment layer 134,154: second alignment layer
141: upper substrate 142: black matrix
144: color filter 146: planarization layer
150: upper alignment layer

Claims (7)

A color filter substrate including an R, G, B color filter for realizing color, a black matrix separating a pixel region in which the color filter is to be formed, and a common electrode;
A thin film transistor substrate bonded to the color filter substrate with a liquid crystal therebetween, the thin film transistor substrate including a thin film transistor and a pixel electrode connected thereto;
An alignment layer formed on each of the color filter substrate and the thin film transistor substrate, the alignment layer including a first photoalignment layer for resolving DC afterimage, and a second photoalignment layer for improving surface anisotropy of the alignment layer,
The first optical alignment layer is a liquid crystal display panel, characterized in that comprises a compound represented by the following [Formula 1].
[Formula 1]

Where n = 0 or more natural, m = 1 or more natural) The method of claim 1,
Ring part represented by R in [Formula 1] ( ) Is benzene (bezene) characterized in that the liquid crystal display panel. The method of claim 1,
Ring part represented by R in [Formula 1] (

) Is a ring compound in which a hetero atom is substituted. The method of claim 1,
Ring part represented by R in [Formula 1] (

) Is a compound in which a plurality of ring compounds are connected directly or indirectly in series. 5. The method of claim 4,
The cyclic compound and the cyclic compound may be connected to one or a plurality of alkyl chains (alkyl chain), and the liquid crystal display panel, characterized in that can be substituted by a hetero atom between the alkyl chains. The method of claim 1,
Ring part represented by R in [Formula 1] (

) Selects any one of the following Compounds A-1 to A-5.

,

,

,

A-1 A-2, A-3

,

A-4 A-5 The method of claim 1,
Substituent R in [Formula 1] may be formed of a macrocyclic compound consisting of at least two or more rings of the following compounds B-1 to B-5, wherein the macrocyclic compound is a ring compound containing a hetero atom Characteristic liquid crystal display panel.

,

,
B-1 B-2

,

,
B-3 B-4

B-5

Images