KR20170135100A - Liquid Crystal Display Device And Method Of Fabricating The Same - Google Patents

Abstract

The present invention relates to a liquid crystal display device and a manufacturing method thereof. The liquid crystal display device comprises: a first alignment layer disposed on an inner surface of a first substrate; a second alignment layer disposed on an inner surface of a second substrate and including a polymer network; and a liquid crystal layer disposed between the first alignment layer and the second alignment layer. The manufacturing method of the liquid crystal display device comprises: a step of forming a first alignment layer on an upper portion of a first substrate; a step of forming a liquid crystal layer between first and second substrates; and a step of forming a second alignment layer on an inner surface of the second substrate by emitting ultraviolet rays onto a light-induced alignment agent. Since the alignment layer is formed by using the light-induced alignment agent, afterimage is prevented, reliability is improved, manufacturing processes are simplified, and manufacturing costs are reduced.

Description

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

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 including an alignment film formed by using an optical director.

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.

A liquid crystal display device includes two substrates spaced apart from each other and facing each other, and a liquid crystal layer formed between the two substrates, wherein pixel electrodes and a first alignment film, and a common electrode and a second alignment film are sequentially And the first and second polarizing plates are formed on the outer surfaces of the two substrates, respectively.

However, when the method of driving the liquid crystal layer by the vertical electric field in the vertical direction generated between the pixel electrodes and the common electrode in a direction perpendicular to each other is used, there is an advantage in that the characteristics such as the transmittance and the aperture ratio are excellent, There is a disadvantage that the viewing angle characteristic is not excellent.

In order to overcome such disadvantages, an in-plane switching mode (IPS mode) or a fringe field switching mode (common mode switching mode) using a horizontal electric field generated between a common electrode and a pixel electrode formed on the same substrate, FFS mode) liquid crystal display device has been proposed.

On the other hand, in a liquid crystal display device, an orientation film is used to give an initial directionality to a liquid crystal layer. The orientation film is completed by coating polyimide (PI) and rubbing.

The initial orientation by such an orientation film will be described with reference to the drawings.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a view for explaining the interaction between a liquid crystal layer and an alignment film of a conventional liquid crystal display device, showing an alignment film and a liquid crystal layer of a second substrate of the liquid crystal display device.

As shown in FIG. 1, polyimide is coated on first and second substrates (not shown) constituting a liquid crystal display device, and a rubbing process is performed to form an alignment film including a polymer chain 54 having a specific directionality (52).

Then, the first and second substrates having the alignment film formed thereon are attached to each other, and a liquid crystal layer 70 is formed between the first and second substrates.

At this time, a director of the liquid crystal molecules 72 is identified by a strong interaction (I) between the polymer chain 54 of the alignment layer 52 and the liquid crystal molecules 72 of the liquid crystal layer 70 Direction so that the liquid crystal layer 70 has an initial directionality.

Since the alignment layer 52 formed of polyimide as described above imparts initial orientation to the liquid crystal layer 70, many processes such as cleaning, coating, pre-baking, post-baking, and rubbing must be performed. , There is a disadvantage in that the manufacturing cost is increased due to consumption of the material, and in particular, the foreign matter generated in the rubbing process causes a residual image or causes a decrease in reliability.

In order to solve this disadvantage, a method of forming an alignment layer by irradiating a reactive liquid crystal monomer (reactive mesogen (RM)) with ultraviolet (UV) light in a vertically aligned mode (VA mode) liquid crystal display device has been proposed.

Here, the alignment layer of the vertical alignment mode liquid crystal display device formed using the reactive liquid crystal monomer has a relatively small anchoring energy so that the adjacent liquid crystal molecules have a relatively large pretilt angle, And has a specific directionality before and after.

For example, an alignment layer of a vertical alignment mode liquid crystal display device formed using a reactive liquid crystal monomer has a relatively small fixing energy, so that adjacent liquid crystal molecules have a pretilt angle of about 88 degrees or more.

However, in the in-plane switching mode or the fringe field switching mode liquid crystal display, since the liquid crystal molecules have to be arranged horizontally, the conventional reactive liquid crystal monomers having a relatively small fixed energy and accordingly a relatively large pre- There is a problem that it can not be applied to an alignment film of a liquid crystal display device using a horizontal electric field such as a switching mode or a fringe field switching mode liquid crystal display device.

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 and a manufacturing method thereof, in which afterimage is prevented and reliability is improved by forming an orientation film using an optical-

The present invention provides a liquid crystal display device and a method for manufacturing the same that simplify the manufacturing process and reduce the manufacturing cost by mixing an optical conduction aligning agent with a liquid crystal material to form a liquid crystal layer and then irradiating ultraviolet rays to form an alignment film .

According to an aspect of the present invention, there is provided a liquid crystal display device comprising: first and second substrates spaced apart from each other, a thin film transistor disposed on the inner surface of the first substrate, a pixel electrode and a common electrode disposed on the thin film transistor, A second alignment layer disposed on the inner surface of the second substrate, the second alignment layer including a polymer network of an optical conduction aligning agent, and a second alignment layer disposed between the first and second alignment layers, And a liquid crystal layer including liquid crystal molecules.

The liquid crystal molecules are present inside the polymer network, and the polymer network can fix the liquid crystal molecules inside the polymer network.

Also, the directors of the liquid crystal molecules of the liquid crystal layer adjacent to the second alignment layer may be arranged in a predetermined direction by interaction between the liquid crystal molecules in the polymer network and the liquid crystal molecules in the liquid crystal layer.

The liquid crystal molecules adjacent to the second alignment layer may have a pretilt angle of 0 to 5 degrees.

The light-oilability aligning agent may be a substance represented by the following chemical structural formulas 1 to 5.

[Chemical Formula 1]

[Chemical Formula 2]

[Chemical Formula 3]

[Chemical Formula 4]

[Chemical Formula 5]

The liquid crystal display device may further include a black matrix disposed on the inner surface of the first substrate and a color filter layer disposed on the black matrix.

According to another aspect of the present invention, there is provided a method of manufacturing a liquid crystal display, comprising: forming a thin film transistor on a first substrate; forming a pixel electrode and a common electrode on the thin film transistor; forming a first alignment film on the pixel electrode and the common electrode Forming a liquid crystal layer between the first and second substrates with a mixture of liquid crystal molecules and an optical path length aligning agent; And forming a second alignment layer on the inner surface of the second substrate, the second alignment layer including a polymer network of the optical conduction aligning agent.

The light-oil directing agent may have a range of more than 0 wt% and less than 10 wt% of the mixed material.

The light-oilability aligning agent may be a substance represented by the following chemical structural formulas 1 to 5.

[Chemical Formula 1]

[Chemical Formula 2]

[Chemical Formula 3]

[Chemical Formula 4]

[Chemical Formula 5]

The manufacturing method of the liquid crystal display may further include forming a black matrix on the inner surface of the first substrate and forming a color filter layer on the black matrix.

The forming of the second alignment layer may include irradiating the ultraviolet light to the optical flow-directing agent through the second substrate among the first and second substrates.

The present invention has an effect of preventing an afterimage and improving reliability by forming an alignment film using an optical conduction aligning agent.

The present invention has the effect of simplifying the manufacturing process and reducing manufacturing cost by forming an alignment film by irradiating ultraviolet rays after mixing a light-oil alignment agent with a liquid crystal material to form a liquid crystal layer.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a view for explaining the interaction between a liquid crystal layer and an alignment film of a conventional liquid crystal display device. Fig.
2 is a cross-sectional view illustrating a liquid crystal display device according to an embodiment of the present invention.
3A to 3E are views for explaining a method of manufacturing a liquid crystal display device according to an embodiment of the present invention.
4 is a view for explaining an interaction between a liquid crystal layer and an alignment layer of a liquid crystal display device according to an embodiment of the present invention.

Hereinafter, a liquid crystal display device and a method of manufacturing the same according to the present invention will be described with reference to the accompanying drawings, taking an in-plane switching mode (IPS mode) liquid crystal display device as an example.

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

2, a liquid crystal display device 110 according to an embodiment of the present invention includes first and second substrates 120 and 150 that are spaced apart from each other, first and second substrates 120 and 120, And a backlight unit (not shown) under the first substrate 120. The liquid crystal layer 170 is formed between the first substrate 120 and the second substrate 150,

Specifically, a gate electrode 122 is formed in each pixel region on the inner surface of the first substrate 120, and a gate insulating layer 124 is formed on the entire surface of the first substrate 120 above the gate electrode 122.

A semiconductor layer 126 is formed on the gate insulating layer 124 corresponding to the gate electrode 122 and a source electrode 128 and a drain electrode 130 are formed on upper portions of both ends of the semiconductor layer 126 do.

Here, the gate electrode 122, the semiconductor layer 126, the source electrode 128, and the drain electrode 130 constitute the thin film transistor T.

Although not shown, a gate wiring connected to the gate electrode 122 is formed on the top surface of the first substrate 120, a data wiring connected to the source electrode 128 is formed on the gate insulating layer 124, And the data line cross each other to define the pixel region.

A protective layer 132 is formed on the entire surface of the first substrate 120 above the thin film transistor T and a thin film transistor T corresponding to a gate wiring and a data wiring A black matrix 134 is formed.

A color filter layer 136 including red, green and blue color filters corresponding to the respective pixel regions is formed on the black matrix 134. The color filter layer 136 and the passivation layer 132 are formed on the drain electrode 130 And has drain contact holes to be exposed.

2, the black matrix 134 is formed as a layer different from the color filter layer 136. However, in another embodiment, two or more of the red, green, and blue color filters of the color filter layer 136 are overlapped, (134).

A pixel electrode 138 connected to the drain electrode 130 through the drain contact hole and a common electrode 140 separated from the pixel electrode 138 are formed in each pixel region above the color filter layer 136.

The pixel electrode 138 and the common electrode 140 have a bar shape and are made of a metal material or a transparent conductive material and can be arranged alternately in the pixel region.

2, the pixel electrode 138 and the common electrode 140 are formed in the same layer. However, in another embodiment, the pixel electrode 138 and the common electrode 140 are formed as different layers with an insulating layer interposed therebetween .

A first alignment layer 142 is formed on the entire surface of the first substrate 120 above the pixel electrode 138 and the common electrode 140.

A second alignment layer 152 is formed on the entire inner surface of the second substrate 150.

Here, the first alignment layer 142 is formed to include a polymer chain through the application, firing, and rubbing processes of polyimide (PI), and the second alignment layer 152 is formed of a photo-induced aligning agent (154 in FIG. 4) through an ultraviolet light irradiation process on the first alignment film (174 in FIG. 3D), in which some liquid crystal molecules 172 are fixed by the polymer network 154, Polymeric network 154 of polymeric material 152.

The light-oil directing agent 174 may be a 4- (3-acryloyloxypropyloxy) -benzoate 2-methyl-1,4-phenyl ester represented by the following chemical structural formula 1, (2-methylbenzene-1, 4-diylbis {4- [3- (acryloyloxy) propoxy] benzoate] 4-diyl bis {4- [3- (acryloyloxy) propoxy] benzoate} or a substance containing an oxygen (O) double bond such as a substance represented by the following chemical formulas 2 to 5.

[Chemical Formula 1]

[Chemical Formula 2]

[Chemical Formula 3]

[Chemical Formula 4]

[Chemical Formula 5]

The liquid crystal layer 170 including the liquid crystal molecules 172 is formed between the first and second substrates 120 and 150 and the first and second substrates 120 and 150 are formed on the outer surfaces of the first and second substrates 120 and 150, Two polarizing plates 160 and 162 are formed.

After the first and second substrates 120 and 150 are bonded together, a liquid crystal layer 170 may be formed by an injection process or a liquid crystal layer 170 may be formed on one of the first and second substrates 120 and 150 by a dispensing process. The first and second substrates 120 and 150 may be bonded together after the first and second substrates 170 and 170 are formed.

The directors of the liquid crystal molecules 172 are arranged in a specific direction by strong interaction between the polymer chains of the first alignment layer 142 and the liquid crystal molecules 172 of the liquid crystal layer 170 The liquid crystal layer 170 adjacent to the first alignment layer 142 has an initial directionality.

In addition, due to strong interaction between the liquid crystal molecules 172 of the second alignment layer 152 fixed by the polymer network 154 and the liquid crystal molecules 172 of the liquid crystal layer 170, the liquid crystal layer 170 adjacent to the second alignment layer 152 has an initial directionality.

The second alignment layer 152 formed using the optical conduction aligner 174 has a relatively large anchoring energy so that the adjacent liquid crystal molecules 172 have relatively small pretilt angles And increases the response speed, and has no directionality before ultraviolet ray irradiation but has a specific directionality after ultraviolet ray irradiation.

For example, the second alignment layer 152, which is formed using the optical conduction aligner 174, has a relatively small fixed energy so that the liquid crystal molecules 172 can be rearranged in parallel with the horizontal electric field, The liquid crystal molecules 172 of the layer 170 may have a pretilt angle of about 0 degrees or more and about 5 degrees or less. If the pretilt angle is larger than 5 degrees, the liquid crystal molecules 172 are not reordered along the horizontal electric field The gradation can not be displayed smoothly and the display quality is degraded.

In this liquid crystal display device 110, when the thin film transistor T is turned on according to the gate voltage of the gate line, the data voltage of the data line is applied to the pixel electrode 138 .

A horizontal electric field is generated between the pixel electrode 138 to which the data voltage is applied and the common electrode 140 to which the common voltage is applied and the liquid crystal molecules 172 of the liquid crystal layer 170 are rearranged according to the generated horizontal electric field Display the image.

In particular, by forming the second alignment layer 152 including the polymer network through the ultraviolet light irradiation process for the optical-oil alignment agent, coating, firing, and rubbing processes of polyimide can be omitted. As a result, after- The manufacturing process is simplified, and the manufacturing cost is reduced.

A manufacturing method of a liquid crystal display device including an alignment film using such an optical conduction aligning agent will be described with reference to the drawings.

3A to 3E are views for explaining a method of manufacturing a liquid crystal display device according to an embodiment of the present invention, and will be described with reference to FIG.

A gate electrode 122, a gate insulating layer 124, a semiconductor layer 126, a source electrode 128, and a drain electrode 130 are sequentially formed on the first substrate 120 A thin film transistor T is completed and a protective layer 132 is formed on the thin film transistor T. A black matrix 134 and a color filter layer 136 are sequentially formed on the protective layer 132, A pixel electrode 138 and a common electrode 140 are formed on the color filter layer 136.

3B, polyimide is coated on the first substrate 120 on which the thin film transistor T, the color filter layer 136, the pixel electrode 138, and the common electrode 140 are formed, (rubbing process using a rubbing cloth 144) is carried out after pre-baking (post-baking), and the first alignment layer 142 is completed.

Although not shown, the completed first alignment layer 142 includes a polymer chain.

The second substrate 150 is bonded to the first substrate 120 on which the first alignment layer 142 is formed and the liquid crystal molecules 172 are mixed with the optical flow directing agent 174 A liquid crystal layer 170 is formed between the first and second substrates 120 and 150 that are bonded together.

After the first and second substrates 120 and 150 are bonded to each other, a liquid crystal layer 170 is formed by a process of injecting a mixed material of the liquid crystal molecules 172 and the optical path length aligning material 174, After the liquid crystal layer 170 is formed by dropping the mixed material of the liquid crystal molecules 172 and the optical path control agent 174 on one of the substrates 120 and 150 and then the first and second substrates 120 and 150 It can be cemented.

At this time, directors of the liquid crystal molecules 172 are arranged in a specific direction by strong interaction between the polymer chains of the first alignment layer 142 and the liquid crystal molecules 172 of the liquid crystal layer 170 The liquid crystal layer 170 adjacent to the first alignment layer 142 has an initial directionality.

In the subsequent process, the light-oil aligning agent 174 may be added in an amount of more than 0 wt% to 10 wt% of the mixed material so that the second alignment film 152 can be selectively formed only on the interface between the second substrate 120 and the liquid crystal layer 170 % ≪ / RTI >

When the content of the optical-oil leveling agent 174 is larger than 10 wt%, a polymer network is generated in the liquid crystal layer 170 in a subsequent process, and the driving voltage of the liquid crystal layer 170 is increased or scattered, .

Such a light-oil directing agent is a substance containing an oxygen (O) double bond at the terminal, for example, 4- (3-acryloyloxypropyloxy) -benzoate 2-methyl- 4- (3-acryloyloxypropyloxy) -benzoesure 2-methyl-1,4-phenylester) or a substance represented by the above-described chemical structures 2 to 5.

In addition, in order to easily form the polymer network, acrylate or methacrylate may be added to the mixed material in addition to the optical oil directing agent, and a photoinitiator may be added to the mixed material as necessary It can also be added.

As shown in FIG. 3D, the liquid crystal layer 170 is irradiated with ultraviolet rays (UV) through the second substrate 150 of the first and second substrates 120 and 150, In the step 174, a polymerization reaction occurs to form a polymer network (154 in FIG. 4).

At this time, since the black matrix 134 and the color filter layer 136 are formed on the first substrate 120, ultraviolet rays can be irradiated to the liquid crystal layer 170 through the second substrate 150.

The polymer network (154 in FIG. 4) of the optical path length aligning agent 174 by the polymerization reaction is formed between the second substrate 150 and the liquid crystal layer 170 as the second alignment film 152 .

At this time, some of the liquid crystal molecules 172 are fixed by the polymer network 154 and exist in the second alignment layer 152, and the liquid crystal molecules 172 of the second alignment layer 152, which is fixed by the polymer network 154, A director of the liquid crystal molecules 172 is arranged in a specific direction due to a strong interaction between the liquid crystal molecules 172 of the liquid crystal layer 170 and the liquid crystal layer 170 adjacent to the second alignment film 152 It has an initial directionality.

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

The polymer network 154 of the second alignment layer 152 will be described with reference to the drawings.

Fig. 4 is a view for explaining the interaction between the liquid crystal layer and the alignment layer of the liquid crystal display device according to the embodiment of the present invention, showing the second alignment layer and the liquid crystal layer of the liquid crystal display device, and Figs. 2, Will be referred to together.

4, the light oiling aligning agent 174 mixed with the liquid crystal molecules 172 of the liquid crystal layer 170 forms a polymer network 154 by ultraviolet irradiation, and this polymer network 154 2 orientation layer 152 is formed.

Some liquid crystal molecules 172 are fixed in a specific direction by the polymer network 154 and the liquid crystal molecules 172 of the second alignment layer 152 fixed by the polymer network 154 and the liquid crystal molecules 172 of the liquid crystal layer 170 The directors of the liquid crystal molecules 172 are arranged in a specific direction due to strong interaction between the liquid crystal molecules 172 so that the liquid crystal layer 170 adjacent to the second alignment film 152 has an initial directionality.

The second alignment layer 152 formed using the optical conduction aligner 174 has a relatively large anchoring energy so that the adjacent liquid crystal molecules 172 have relatively small pretilt angles And increases the response speed, and has no directionality before ultraviolet ray irradiation but has a specific directionality after ultraviolet ray irradiation.

For example, the second alignment layer 152 formed using the optical conduction aligning material 174 has a relatively small fixed energy, and the liquid crystal molecules 172 of the adjacent liquid crystal layer 170 have a diameter of about 5 degrees or less It is possible to have a square.

As described above, in the liquid crystal display device 110 according to the embodiment of the present invention, the liquid crystal molecules 172 are mixed with the optical path length aligning agent 174 to form the liquid crystal layer 170, By forming the second alignment film 152 of the polymer network 154 that fixes the liquid crystal display panel 172, a residual image is prevented from being displayed on the liquid crystal display device 110 and reliability is improved.

Since the application, firing, and rubbing processes of the polyimide can be omitted, the manufacturing process is simplified and the manufacturing cost is reduced.

In the embodiment of FIGS. 2 and 3A to 3E, a color filter on thin film transistor (COT) type liquid crystal display device in which a thin film transistor T and a color filter layer 136 are sequentially formed on a first substrate 120 (TFT) type liquid crystal display device in which a color filter layer and a thin film transistor are sequentially formed on an upper portion of a first substrate, or a color filter layer is formed on a display panel In a field sequential color mode (FSC mode) liquid crystal display device in which red, green, and blue light sources are sequentially emitted to display a color without using a liquid crystal alignment layer, Formation can be applied.

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

110: liquid crystal display device 120: first substrate
150: second substrate 142: first alignment film
152: second alignment layer 170: liquid crystal layer

Claims (11)

First and second substrates spaced apart from each other;
A thin film transistor disposed on the inner surface of the first substrate;
A pixel electrode and a common electrode disposed on the thin film transistor;
A first alignment layer disposed above the pixel electrode and the common electrode;
A second alignment layer disposed on the inner surface of the second substrate, the second alignment layer including a polymer network of an optical conduction aligning agent;
A liquid crystal layer disposed between the first and second alignment films,
And the liquid crystal display device.
The method according to claim 1,
Wherein the liquid crystal molecules exist in the polymer network, and the polymer network fixes the liquid crystal molecules in the polymer network.
3. The method of claim 2,
Wherein a direction of the liquid crystal molecules of the liquid crystal layer adjacent to the second alignment layer is arranged in a predetermined direction by an interaction between the liquid crystal molecules in the polymer network and the liquid crystal molecules in the liquid crystal layer.
The method of claim 3,
Wherein the liquid crystal molecules adjacent to the second alignment layer have a pre-scan square of 0 degree or more and 5 degrees or less.
The method according to claim 1,
The light-
1. A liquid crystal display device comprising a material represented by any one of Chemical Formulas 1 to 5 below.
[Chemical Formula 1]

[Chemical Formula 2]

[Chemical Formula 3]

[Chemical Formula 4]

[Chemical Formula 5]

The method according to claim 1,
A black matrix disposed on the inner surface of the first substrate;
The color filter layer disposed on the black matrix
The liquid crystal display device further comprising:
Forming a thin film transistor on the first substrate;
Forming a pixel electrode and a common electrode on the thin film transistor;
Forming a first alignment layer on the pixel electrode and the common electrode;
Attaching a second substrate to the first substrate;
Forming a liquid crystal layer between the first and second substrates using a mixture of liquid crystal molecules and an optical director;
Forming a second alignment layer on the inner surface of the second substrate by irradiating ultraviolet light to the optical light-directing agent, the second alignment layer including a polymer network of the optical-
And the second electrode is electrically connected to the second electrode.
8. The method of claim 7,
Wherein the light oil directing agent has a range of more than 0 wt% and less than 10 wt% of the mixed material.
8. The method of claim 7,
The light-
A method for manufacturing a liquid crystal display device, which is a material represented by the following chemical structural formulas 1 to 5.
[Chemical Formula 1]

[Chemical Formula 2]

[Chemical Formula 3]

[Chemical Formula 4]

[Chemical Formula 5]

8. The method of claim 7,
Forming a black matrix on the inner surface of the first substrate;
Forming a color filter layer on the black matrix
The method comprising the steps of:
11. The method of claim 10,
Wherein the forming of the second alignment film comprises irradiating the ultraviolet light to the optical flow-directing agent through the second substrate among the first and second substrates attached together.

Images