KR20040052100A - Liquid crystal display device and fabricating method thereof - Google Patents

Abstract

PURPOSE: An LCD(Liquid Crystal Display) and a method for manufacturing the LCD are provided to increase a cell gap of the central part of an LCD panel to prevent liquid crystal from being moved to the edge of the LCD panel at a high temperature. CONSTITUTION: An LCD includes a thin film transistor substrate, a color filter substrate(200), and a plurality of column spacers(320). The thin film transistor substrate and the color filter substrate are attached to each other having a liquid crystal layer interposed between the two substrates. The plurality of column spacers are formed on one of the thin film transistor substrate and the color filter substrate to maintain a cell gap between the two substrates. The spacers(322) formed at the center of the substrate have larger areas than the areas of the spacers(324) formed at the edge of the substrate.

Description

Liquid crystal display and its manufacturing method {LIQUID CRYSTAL DISPLAY DEVICE AND FABRICATING METHOD THEREOF}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display, and more particularly, to a liquid crystal display which prevents poor gravity when maintaining a cell gap using a column spacer.

The manufacturing process of the liquid crystal display device includes a series of processes in which a thin film transistor (TFT) substrate and a color filter substrate, which are completed through different manufacturing processes, are bonded together with a liquid crystal interposed therebetween.

In more detail, the manufacturing process of the liquid crystal display device starts with an alignment film coating and rubbing process for arranging liquid crystal molecules in a predetermined direction with respect to the TFT substrate and the color filter substrate, respectively. Usually, a short pattern is formed in a TFT substrate for sealing pattern printing for injecting liquid crystal and a short for connecting a common electrode terminal of the color filter substrate to a bonding pad of the TFT substrate. A spacer is formed in the cell to maintain a constant cell gap. The liquid crystal layer is formed in the cell gap held by the spacer.

The liquid crystal is a liquid substance. 1) When the liquid crystal is filled in the liquid crystal panel more than the prescribed amount, 2) The thermal expansion ratio of the liquid crystal is larger than that of the TFT substrate and the color filter substrate. 3) The spacer inside the liquid crystal panel. When the thermal expansion rate of the liquid crystal display is greater than that of the liquid crystal, when the liquid crystal display is operated at a high temperature, the heated liquid crystal expands and is driven to the edge of the liquid crystal display. Such a phenomenon will be defined as a gravity failure.

The spacer has two types, a ball shape and a patterned shape. Ball-shaped spacers have a disadvantage in that the adhesion to the substrate and the dispersion density is not easy to control, and thus, patterned spacers are frequently used. The ball spacer is referred to as a ball spacer, and the patterned spacer is referred to as a column spacer. The column spacer is formed by a process of depositing, developing, and etching an organic polymer material. The column spacer has an advantage of having a wider contact area with the substrate, better distribution density control, and better adhesion with the substrate than the ball spacer. In particular, as the liquid crystal display device becomes larger, column spacers are mainly used. However, in the case of the column spacer, the thermal expansion rate is smaller than that of the ball spacer, which causes a problem of gravity failure when the liquid crystal display device having the column spacer is driven at a high temperature.

The reason why the gravity failure occurs will be described with reference to FIG. 1.

1 is a side sectional view showing a conventional liquid crystal panel.

In the related art, the column spacer 120 is uniformly formed on the color filter substrate 100 with the same size. However, when the column spacer 120 is used as described above, the column spacer 120 is formed by the pressure applied when the TFT substrate 110 and the color filter substrate 100 are bonded together and the pressure applied when vacuum is injected into the liquid crystal. When pressed, the cell gap of the central portion of the liquid crystal panel 150 is reduced. In particular, the above phenomenon occurs when a large area liquid crystal display device is manufactured.

A seal pattern 130 is formed at an edge of the liquid crystal panel 150, and the seal pattern 130 includes glass fibers to maintain an initial cell gap. The cell gap of the edge region is larger than that of the center portion. When the liquid crystal display is operated at a high temperature in this state, the volume of the liquid crystal expands, causing the liquid crystal to rush to the edge of the liquid crystal panel 150 which is a large area, resulting in poor gravity. When gravity failure occurs and the liquid crystal is driven to the edge of the liquid crystal panel 150, the transmittance of the liquid crystal is changed in this portion, and the screen display characteristics are deteriorated. That is, even when the black state is shown, the portion where the liquid crystal is concentrated appears slightly white.

In addition, when the liquid crystal is vacuum-injected in a state where the cell gap of the central portion of the liquid crystal panel 150 is small, the central portion of the substrate is rubbed by the liquid crystal in the injection process, thereby causing a circular stain.

In order to solve the above problems, the present invention provides a method for preventing a circular defect caused by friction between the liquid crystal when the liquid crystal layer is formed at the edge of the liquid crystal display and the formation of the liquid crystal layer even when the liquid crystal display is driven at a high temperature. An object of the present invention is to provide a liquid crystal display device having an increased cell gap of a portion.

Other features and objects of the present invention will be described in detail in the configuration and claims of the invention below.

1 is a side cross-sectional view showing a conventional liquid crystal panel.

2 is a plan view showing a color filter substrate used in the liquid crystal display according to the embodiment of the present invention;

3 is a side cross-sectional view schematically showing a liquid crystal display device according to an embodiment of the present invention.

4A through 4D are cross-sectional views illustrating a process of manufacturing a color filter substrate of a liquid crystal display according to an exemplary embodiment of the present invention.

*** Explanation of symbols for the main parts of the drawing ***

100, 300: color filter substrate 110, 310: TFT substrate

120, 320, 322, 324: column spacer 130, 330: seal pattern

150, 350: liquid crystal panel 200, 520: color filter

500: transparent substrate 510: black matrix

530: planarization film

The present invention to achieve the above object is a thin film transistor substrate; A color filter substrate bonded to the thin film transistor substrate with a liquid crystal layer interposed therebetween; And a plurality of column spacers formed on a wider area toward a central portion of any one of the thin film transistor substrate and the color filter substrate to maintain a cell gap between the two substrates. .

In addition, to achieve the above object, the present invention comprises the steps of forming a black matrix for separating each pixel on a transparent substrate; Forming red, green, and blue color filters on the transparent substrate and the black matrix; And forming a column spacer on the color filter, the column spacer having a wider area toward the center portion of the color filter.

The forming of the column spacer may include applying an acrylic resin on the color filter; And patterning the acrylic resin.

According to the embodiment of the present invention configured as described above it is possible to prevent the poor gravity caused by the liquid crystal is concentrated to the edge of the liquid crystal panel, it is possible to prevent the occurrence of circular stains appeared by the friction of the central portion of the liquid crystal panel when forming the liquid crystal layer have.

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

2 is a plan view illustrating a color filter substrate used in a liquid crystal display according to an exemplary embodiment of the present invention.

A plurality of red (R), green (G), and blue (B) color filters 200 are sequentially arranged on the color filter substrate, and the color filters 200 of R, G, and B are gathered to form one pixel. do. Colors are realized through additive color mixing of light passing through the R, G, and B color filters 200. Although not shown in the figure, a black matrix (BM) is formed between the color filters 200 representing each color to prevent leakage of light.

The column spacer 320 is formed at a uniform density on the entire color filter substrate 300 on the BM. The density of the column spacer 320 is determined in consideration of the area of the liquid crystal panel to be manufactured. As shown in the drawing, the column spacer 320 is formed to gradually increase its area toward the center of the color filter substrate 300. That is, the column spacer 322 located in the center of the color filter substrate 300 has the maximum area, and the column spacer 322 located in the outermost part of the color filter substrate 300 has the minimum area.

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

As described above, the liquid crystal panel 350 is formed by bonding the color filter substrate 300 and the TFT substrate 310 by the seal pattern 330. As described above, when the plurality of column spacers 320 are formed on the color filter substrate 300 and the two substrates 300 and 310 are bonded to each other, a cell gap is formed by the column spacers 320. The height of the column spacer 320 is the same and the area increases toward the center portion of the liquid crystal panel 350 as shown in the drawing.

As the area where the column spacer 320 contacts the substrates 300 and 310 increases, the stress increases. The stress refers to a reaction force generated in the object when the object receives a force from the outside. The stress increases in proportion to the size of the area under stress.

According to the exemplary embodiment of the present invention, since the area of the column spacer 320 formed at the center of the liquid crystal panel 350 is larger than the area of the column spacer 320 formed at the periphery, the stress is also increased. Therefore, even when pressure is applied to the liquid crystal panel 350 when vacuum is injected into the liquid crystal panel 350, the cell gap of the center portion of the liquid crystal panel 350 is greatly reduced by the high stress column spacer 320. Will not. In addition, due to the stress difference caused by the column spacer 320, the cell gap in the center portion is the largest except for the edge of the liquid crystal panel 350 in which the seal pattern is formed. That is, a wider space is secured in the central portion of the liquid crystal panel 350 than in the prior art.

In this state, when the liquid crystal panel 350 according to the exemplary embodiment of the present invention is heated, the substrate expands and the space of the center part becomes wider. Therefore, the liquid crystal expanded in volume due to the heating of the liquid crystal panel 350 and the liquidity is actively collected in the central portion of the liquid crystal panel 350 having a relatively large space. The liquid crystal is concentrated the most to the center portion of the liquid crystal panel 350 and gradually decreases toward the edge. In addition, since the column spacer 320 having a large area is formed at the center portion of the liquid crystal panel 350, it also serves to prevent the liquid crystal from flowing to the edge. Unlike the conventional liquid crystal display device, in the liquid crystal panel 350 according to the exemplary embodiment of the present invention, the liquid crystal is concentrated to the center portion, and thus the transmittance of the portion is changed, but the amount of liquid crystal is gradually increased by gradually changing the area of the column spacer. Change the transmittance to reduce the change of transmittance so that the user does not recognize it.

In addition, in the related art, when the liquid crystal is injected after the color filter substrate 300 and the TFT substrate 310 are bonded together as described above, the liquid crystal display device may be caused by friction between the liquid crystals injected between the two substrates due to a narrow cell gap in the center portion. There was a problem in that circular stains were observed, but in the embodiment of the present invention, this problem can be solved by increasing the cell gap in the center portion.

4A to 4D are cross-sectional views illustrating a process of manufacturing a color filter substrate of a liquid crystal display according to an exemplary embodiment of the present invention.

First, as illustrated in FIG. 4A, a BM 510 is formed at a boundary of each pixel on a transparent substrate 500 such as a glass substrate. The BM 510 serves to improve the contrast ratio of the liquid crystal display by blocking light from passing through the liquid crystal in an uncontrolled portion of the pixel array of the TFT array. In addition, the BM 510 serves to prevent light leakage current of the TFT by blocking direct light irradiation of the TFT. The TFT channel portion has a structure in which light shielding is performed by the gate electrode and the BM 510. As the material of the BM 510, a metal thin film such as chromium (Cr) or a carbon-based resin is mainly used.

Thereafter, as shown in FIG. 4B, the color filter 520 is formed on the transparent substrate and the BM. The color filter 520 for implementing color is formed by using photolithography technology. The order of forming the color filters 520 is typically formed in the order of R, G, and B. The R, G, and B patterns are formed by shift exposure by pixel interval using one mask. As the color filter 520, a color photo resist (PR) containing pigment particles is used.

Next, as shown in FIG. 4C, a spin coating method of an acrylic resin or the like with an overcoat 530 on the surface of the color filter 520 to protect and planarize the color filter 520. To form. The planarization film may not be formed.

After forming the planarization layer 530, an acrylic resin such as photoacryl having photosensitive thereon is uniformly applied to the desired thickness of the cell gap, and then the column spacer 320 is formed by photolithography using a mask having a pattern of column spacers formed thereon. ). In this case, the column spacer 320 is formed to have a larger area toward the central portion of the color filter substrate. The position of the column spacer 320 is formed to overlap the BM 510 on the planarization layer 530 as shown in FIG. 4D so that the aperture ratio does not decrease due to the column spacer 320, and the color filter substrate is bonded to the TFT substrate. The column column spacer 320 is positioned above the wiring (gate wiring, data wiring, common wiring) of the TFT substrate. The common electrode and the pixel electrode are both formed on the TFT substrate when the liquid crystal display is driven by the transverse electric field method. However, when the TN (twisted nematic) method is used, the common electrode is formed on the color filter substrate. The common electrode should be formed at. The column spacer 320 is formed on the gate wiring, the data wiring or the common wiring.

Subsequently, although not shown in the drawings, a liquid crystal display device according to an exemplary embodiment of the present invention is manufactured by injecting a liquid crystal after bonding the color filter substrate and the TFT substrate manufactured as described above. The liquid crystal layer may also be formed by a liquid crystal dropping method in which a liquid crystal is dropped on a substrate of a color filter substrate or a TFT substrate and then formed by bonding.

4A to 4D illustrate the process of forming the column spacer on the color filter substrate, but the column spacer may also be formed on the TFT substrate. When the column spacer is formed on the TFT substrate, the column spacer may be formed at a position corresponding to the BM of the color filter substrate after the TFT array process is completed. However, since the manufacturing process of the color filter substrate is simpler than the manufacturing process of the TFT substrate, and the color filter substrate is simpler in structure, it is preferable to form the column spacer on the color filter substrate.

While many details are set forth in the foregoing description, it should be construed as an illustration of preferred embodiments rather than to limit the scope of the invention. Therefore, the scope of the invention should not be defined by the described embodiments, but should be defined by the claims and the equivalents of the claims.

According to the present invention has the following effects.

First, the cell gap of the central portion of the liquid crystal panel is enlarged to prevent the liquid crystal from moving to the edge of the liquid crystal panel at a high temperature. Therefore, it is possible to prevent the occurrence of unevenness due to the change in transmittance of the liquid crystal panel.

Second, when the cell gap of the central portion of the liquid crystal panel is increased, friction generated in the central portion when the liquid crystal layer is formed can be reduced, thereby preventing the occurrence of circular spots.

Claims (6)

A thin film transistor substrate; A color filter substrate bonded to the thin film transistor substrate with a liquid crystal layer interposed therebetween; And And a plurality of column spacers formed in a wider area toward a central portion of any one of the thin film transistor substrate and the color filter substrate to maintain a cell gap between the two substrates. The liquid crystal display of claim 1, wherein the column spacer is formed on a color filter substrate. The liquid crystal display of claim 1, wherein the column spacer is formed of an acrylic resin. Forming a black matrix for dividing each pixel on the transparent substrate; Forming red, green, and blue color filters on the transparent substrate and the black matrix; And And forming a column spacer having a larger area toward the center of the color filter. The method of claim 4, wherein the forming of the column spacers comprises: Applying an acrylic resin on the color filter; And And patterning the acrylic resin. The method of claim 4, further comprising forming a planarization layer on the color filter.