KR100387230B1 - Method for manufacturing liquid crystal display panel - Google Patents

Abstract

PURPOSE: A method for manufacturing a liquid crystal display panel is provided to improve luminance and contrast characteristics by making the thickness of a liquid crystal layer uniform. CONSTITUTION: Spacers are dispensed on a lower substrate(11') on which a lower electrode(13'), an alignment film(14'), a black matrix(15) and a color filter(16) are formed. The edge of the substrate is seal-printed. An upper substrate(11) on which an active circuit part(12), a transparent electrode(13) and an alignment film(14) are formed is placed on the seal-printed lower substrate, and then the two substrates are attached to each other, to form a panel having a gap between the two substrates. Liquid crystal(17) and a liquid crystal composition including a polymer precursor are injected into the gap, and the polymer precursor is polymerized.

Description

LCD panel and manufacturing method thereof

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display panel and a method of manufacturing the same, and more particularly, to a liquid crystal display panel and a method of manufacturing the same, which are excellent in thickness uniformity of the liquid crystal layer interposed between substrates and can be maintained for a long time.

Liquid crystal displays (hereinafter referred to as LCDs) have the advantages of low leakage current of the liquid crystal itself, no need for large accumulation capacity, and low power consumption. Twisted Nematic (STN) and Super Twisted Nematic (STN) type LCDs are mainstream.

The liquid crystal display device uses a principle of blocking and transmitting light incident from a light source, and as an essential element therefor, there are a liquid crystal display panel and two polarizing plates provided at both sides thereof. Among these, the present invention relates to a liquid crystal display panel.

FIG. 1 is a block diagram of a general liquid crystal display device panel employing a TFT element, and includes an upper circuit 1 having an active circuit (thin film transistor and capacitor) 2, a transparent electrode 3, and an alignment layer 4. And a lower substrate 1 'having a lower electrode 3', an alignment layer 4 ', a black matrix 5, and a color filter 6. The liquid crystal layer 8 in which the liquid crystal 7 is arranged is interposed between the upper substrate 1 and the lower substrate 1 ′. In addition, the edges of the substrates 1 and 1 'are bonded to each other using a sealing material (not shown), and the sealing material also serves to prevent liquid crystals from flowing out.

On the other hand, since the liquid crystal display element is an image display element, it is necessary to have excellent characteristics such as brightness and contrast. This requires efficient transmission and blocking of light depending on whether an electric field is applied, and for this purpose, the thickness of the liquid crystal layer must be uniform.

However, according to the conventional method, it is difficult to manufacture a liquid crystal display panel having a uniform thickness of the liquid crystal layer, and there is a problem that the thickness of the formed liquid crystal layer may be deformed.

Referring to FIG. 1, the upper substrate 1 and the lower electrode 3 ′ provided with the active circuit unit 2, the transparent electrode 3, the alignment layer 4, and the like for manufacturing a liquid crystal display device panel, A lower substrate 1 'provided with an alignment film 4', a black mattress 5, a color filter 6, and the like is prepared. Subsequently, a spacer (not shown) is coated on the lower substrate 1 ', the edge of the substrate is sealed printed, and then the upper substrate is placed on the lower substrate and pressed to bond. At this time, a gap is formed between the substrates to fill the liquid crystal material. Therefore, in order to have the liquid crystal layer 8 of uniform thickness, it is necessary to form the gap of uniform thickness.

However, a liquid crystal display panel in which only the edge portion of the substrate is bonded has a problem in that the thickness of the liquid crystal layer may become uneven over time or the liquid crystal material may leak out. This is because the sealant that bonds the edges of the substrate may drop over time. In the case of a large panel, even if the sealing material is not dropped, the thickness may be uneven because the substrate is deformed and the gap between the center portions thereof is widened. As described above, the liquid crystal display device panel manufactured according to the conventional method has a problem in that the thickness of the liquid crystal layer is nonuniform, so that characteristics such as brightness and contrast of the screen are not good.

On the other hand, with the development of office equipment, it has become common for liquid crystal display devices to adopt a pen input function. In this case, when the liquid crystal display is directly stimulated by a pen or the like, an array of liquid crystals having high fluidity is scattered, and the scattered array takes a long time to recover. In particular, in a display element employing a ferroelectric liquid crystal, the display performance itself may be difficult to recover due to an impact, and thus there is a problem in that a pen input means must be formed on a separate glass.

Accordingly, the present invention is to solve the above problems to provide a liquid crystal display panel with a uniform thickness of the liquid crystal layer is excellent in brightness and contrast characteristics, the scattering phenomenon of the liquid crystal array is greatly reduced.

In the present invention to solve the above problems,

An upper substrate having a transparent electrode and an alignment layer;

A lower substrate having a black matrix, a color filter, a projection electrode, and an alignment layer; And

In the liquid crystal display device panel comprising a liquid crystal layer interposed between the upper and lower substrates,

A liquid crystal display panel is provided in the liquid crystal layer, wherein the polymer spheres adhering the two substrates are dispersed.

Another object of the present invention is to provide a method for producing a liquid crystal liquid crystal display device panel having the above characteristics.

In order to achieve the above another object, in the present invention,

Manufacturing an upper substrate having a transparent electrode and an alignment layer;

Manufacturing a lower substrate having a black matrix, a color filter, and a transparent electrode;

Bonding the two substrates prepared in the step to form a cell gap therebetween;

Injecting a liquid crystal layer composition comprising a liquid crystal and a polymer precursor into the cell gap; And

Provided is a method of manufacturing a liquid crystal display device panel, comprising curing the polymer precursor.

2A and 2B are cross-sectional views schematically illustrating a manufacturing process of a liquid crystal display device panel according to an exemplary embodiment of the present invention. The present invention will be described in detail with reference to the drawings.

In the present invention, the step of joining two substrates to form a gap 18 is performed through a general method. That is, a spacer (not shown) is coated on the lower substrate 11 'provided with the lower electrode 13', the alignment layer 14 ', the black matrix 15, the color filter 16, and the like, and the edge of the substrate is applied. After sealing printing, a panel having a gap 18 is formed by placing the upper substrate 11 provided with the active circuit unit 12, the transparent electrode 13, the alignment layer 14, and the like on it. (Figure 2A).

Subsequently, a liquid crystal layer composition including a liquid crystal and a polymer precursor is injected into the gap 18, and then the polymer precursor is polymerized. The polymerization reaction is carried out by irradiating heat or ultraviolet rays into the panel, and the polymer component to be polymerized is phase separated from the liquid crystal. At this time, the polymer component is in the form of quadrature due to the difference in the interfacial tension with the liquid crystal.

In the present invention, the liquid crystal is not particularly limited as long as it is commonly used, nematic liquid crystal, smectic liquid crystal, ferroelectric liquid crystal, cholesteric liquid crystal and the like can be used alone or in combination.

According to the present invention, the polymer precursor added to the composition for the liquid crystal layer is an ultraviolet curable material, and is well mixed with the liquid crystal material in an uncured state and mixed well. Those that can be completely phase separated are used. In addition, it should be possible to use a polymer that reacts itself by irradiation with heat or light, or a reaction that can be initiated by a curing initiator. As the polymer precursor that satisfies these characteristics, there are an acrylic compound, an epoxy compound, and the like, and a mixture of several monomers and oligomers is preferably used.

The polymer precursor is dissolved in the liquid crystal before being uncured, and then phase-separated from the liquid crystal while gradually polymerizing by ultraviolet irradiation or heating. After the polymerization reaction is completed, the polymer 19 is spherically dispersed in the liquid crystal layer 20. The spherical polymer provides strong adhesion between the upper and lower substrates 11 and 11 ', thereby preventing the middle portion of the substrate from being convex. In addition, it serves to complement the adhesion of the sealing material is applied only to the substrate edge.

On the other hand, while the polymer precursor is polymerized and phase-separated, the liquid crystal 17 exhibits its original properties and is arranged according to the type of the alignment film and the rubbing direction (FIG. 2B).

According to the present invention, the content of the polymer precursor added for this purpose is preferably 1 to 20% by weight based on the composition for the liquid crystal layer. If the amount is less than 1% by weight, the effect of the present invention is insignificant, and if it exceeds 20% by weight, it is because the driving characteristics of the liquid crystal are lowered due to the excessive polymer.

In addition, the curing initiator is determined by the polymer precursor used, and generally azobisisobutyronitrile (AIBN) is preferable.

Hereinafter, the effects of the present invention will be described in more detail with reference to Examples, but the present invention is not necessarily limited thereto.

<Example>

Polymer precursor consisting of Merck's nematic liquid crystals ZLI-3417 and 2-ethylhexyl acrylate, 2-ethoxybisphenol-A diacrylate and EB-230 (urepandiacrylate oligomer) of UCB (7/3 / Weight ratio 3) was mixed at a weight ratio of 100: 5. The mixture was heated to 40 ° C. to make a homogeneous solution, and then dissolved by adding 1% by weight of AIBN to the solution to obtain a liquid crystal layer composition. The obtained composition was injected into the gap formed between the board | substrates using the vacuum injection method. Subsequently, the panel was maintained at 80 ° C. for 2 hours, and then cooled to room temperature to prepare a liquid crystal display device panel having a liquid crystal layer.

The electro-optical characteristics of the manufactured panels were evaluated, with threshold voltages of 2.3 Vrms, response speed of 55 ms, and contrast ratio of 100: 1 or more. In addition, a pressure cooking test was performed under conditions of 1.2 atm and a relative humidity of 100%, but the sealing part dropped after 2 hours.

Comparative Example

Only ZLI-3417 containing no polymer precursor and AIBN was injected into the gap in the same manner as in Example to prepare a liquid crystal display panel having a liquid crystal layer.

The electro-optical characteristics of the manufactured panels were evaluated, with threshold voltages of 2.3 Vrms, response speed of 45 ms, and contrast ratio of 100: 1 or more. In addition, the pressure resistance and moisture resistance evaluations were performed under conditions of 1.2 atm and a relative humidity of 100%, but the sealing portion fell after 1 hour.

From the examples and the comparative examples, it can be seen that the liquid crystal display panel in which the polymer precursor is formed in the liquid crystal layer has similar electro-optic characteristics as compared to the panel manufactured according to the conventional method, but has about twice the adhesive strength between the substrates. have. Therefore, the liquid crystal display device panel manufactured according to the present invention has the advantage that the uniformity of the liquid crystal layer thickness is maintained for a long time, so that its life is long. In addition, since the scattering phenomenon of the liquid crystal array is greatly reduced by the polymer spheres, and the problem of damage to the liquid crystal array due to external impact is greatly reduced, there is an advantage that it is advantageous to employ the pen input means.

1 is a configuration diagram of a general liquid crystal display element panel employing a TFT element.

2A and 2B are cross-sectional views schematically illustrating a manufacturing process of a liquid crystal display device panel according to an exemplary embodiment of the present invention.

* Explanation of symbols for the main parts of the drawings

1,1 ', 11,11'. Substrate 2,12. Active circuit

3,3 ', 13,13'. Transparent electrodes 4,4 ', 14,14'. Alignment film

5,15. Black Matrix 6,16 '. Color filter

7,17. Liquid crystal 8,20. Liquid crystal layer

18. Gap 19. Polymer sphere

Claims (9)

An upper substrate having a transparent electrode and an alignment layer; A lower substrate having a black matrix, a color filter, a projection electrode, and an alignment layer; And In the liquid crystal display device panel comprising a liquid crystal layer interposed between the upper and lower substrates, And a polymer sphere for adhering the two substrates is dispersed in the liquid crystal layer. The liquid crystal display device panel according to claim 1, wherein the liquid crystal display panel is at least one selected from the group consisting of nematic liquid crystals, smectic liquid crystals, ferroelectric liquid crystals, and cholesteric liquid crystals. The liquid crystal display device panel as claimed in claim 1, wherein the polymer sphere is at least one polymer selected from the group consisting of an acrylic compound and an epoxy compound. The liquid crystal display device panel according to claim 1, wherein the polymer sphere is 1 to 20% by weight based on the total weight of the liquid crystal layer. Manufacturing an upper substrate having a transparent electrode and an alignment layer; Manufacturing a lower substrate having a black matrix, a color filter, and a transparent electrode; Bonding the two substrates prepared in the step to form a cell gap therebetween; Injecting a liquid crystal layer composition comprising a liquid crystal and a polymer precursor into the cell gap; And Method of manufacturing a liquid crystal display device panel comprising the step of curing the polymer precursor. The method for manufacturing a liquid crystal display device panel according to claim 5, wherein the liquid crystal layer composition comprises a photocuring initiator. The method of claim 5, wherein the polymer precursor is at least one selected from the group consisting of an epoxy compound and an acrylic compound. The method of claim 5, wherein the polymer precursor is 1 to 20% by weight based on the composition for the liquid crystal layer. The method of claim 5, wherein the curing of the polymer precursor is performed by irradiating the composition for the liquid crystal layer with ultraviolet rays.