KR20040060593A - Liquid crystal display panel and fabricating method thereof - Google Patents

Abstract

PURPOSE: A liquid crystal panel and its manufacturing method are provided to use second column spacers for adjusting the amount of filled liquid crystals as well as first column spacers for maintaining a cell gap of the liquid crystal panel, thereby preventing defects by gravity. CONSTITUTION: A TFT(Thin Film Transistor) substrate(210) is provided. A color filter substrate(200) is provided. A plurality of first column spacers(220) formed on one of the TFT substrate(210) and the color filter substrate(200) maintains a cell gap between the TFT substrate(210) and the color filter substrate(200). A plurality of second column spacers(230) formed on one of the TFT substrate(210) and the color filter substrate(200) to have a height smaller than the height of the first column spacers(220) adjusts the amount of liquid crystals filled between the TFT substrate(210) and the color filter substrate(200). The first and second column spacers(220,230) are formed of acryl type resin and arranged with uniform density.

Description

Liquid crystal panel and its manufacturing method {LIQUID CRYSTAL DISPLAY PANEL AND FABRICATING METHOD THEREOF}

TECHNICAL FIELD The present invention relates to a liquid crystal panel, and more particularly, to a liquid crystal panel including a column spacer for maintaining a cell gap of the liquid crystal panel.

The manufacturing process of the liquid crystal panel consists of 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 layer interposed therebetween.

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

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

The liquid crystal panel 170 is formed by bonding the TFT substrate 110 and the color filter substrate 100 to each other. A cell gap is maintained by the spacer 120, and a liquid crystal layer is formed therebetween.

When the liquid crystal is filled with more liquid than the amount set inside the liquid crystal panel when the liquid crystal panel is operated at a high temperature, the heated liquid crystal expands and the viscosity drops, and the liquid crystal is concentrated toward the edge of the liquid crystal panel having a relatively high cell gap.

Such a phenomenon will be defined as a gravity failure. When gravity failure occurs and the liquid crystal is driven to the edge of the liquid crystal panel, the transmittance of the liquid crystal is changed in this portion, and the display characteristics are deteriorated. That is, even when the black state is displayed, the portion where the liquid crystal is concentrated does not display the perfect black.

The spacer 120 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 panel becomes larger in area, column spacers are mainly used. However, in the case of the column spacer, the coefficient of thermal expansion is smaller than that of the ball spacer, and gravity failure occurs more seriously when driving the liquid crystal panel in which the column spacer is formed at a high temperature.

Therefore, the amount of liquid crystal filled in the liquid crystal panel is very important to prevent the gravity failure when the cell gap is maintained by the column spacer. In order to prevent gravity failure, a pressure encapsulation process is additionally performed in which liquid crystals are filled and pressurized the liquid crystal panel to discharge extra liquid crystals that cause gravity failure and seal the liquid crystal inlet, which increases the manufacturing cost of the liquid crystal panel. And delay the process time.

SUMMARY OF THE INVENTION In order to solve the above problems, an object of the present invention is to provide a liquid crystal panel and a manufacturing method thereof, in which a problem of gravity failure does not occur.

Moreover, it aims at shortening a process time and improving a yield by omitting a pressurized sealing process.

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 view schematically showing a conventional liquid crystal panel.

2A and 2B are side and plan views illustrating a liquid crystal panel according to an embodiment of the present invention.

3A to 3D are cross-sectional views showing a method of manufacturing a liquid crystal panel according to an embodiment of the present invention.

4 is a plan view of the diffraction mask used in FIG. 3B.

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

100, 200: color filter substrate 110, 210: TFT substrate

120: column spacer 170, 270: liquid crystal panel

220: first column spacer 230: second column spacer

250: color filter 300: photosensitive resin

310: diffraction mask 312: first pattern

314: second pattern

The present invention to achieve the above object is a thin film transistor substrate; Color filter substrates; A plurality of first column spacers formed on one of the thin film transistor substrate and the color filter substrate to maintain a cell gap between the two substrates; And a plurality of second column spacers formed on one of the thin film transistor substrate and the color filter substrate to be less than the height of the first column spacer to control the amount of liquid crystal filled between the two substrates. Provide a liquid crystal panel.

In addition, the present invention comprises the steps of applying a photosensitive resin on top of any one of a color filter substrate and a TFT substrate to achieve the above object; Patterning the photosensitive resin to form a plurality of first column spacers and a plurality of second column spacers having a height lower than that of the first column spacers; And bonding the color filter substrate and the TFT substrate to each other.

The forming of the first and second column spacers may include: irradiating the photosensitive resin with ultraviolet rays through a diffraction mask; And developing the photosensitive resin irradiated with ultraviolet rays.

Preferably, the first and second column spacers are formed on a color filter substrate.

Preferably, the first and second column spacers are distributed at a uniform density.

According to the present invention having the above configuration, there is an effect of preventing the liquid crystal from being tilted even if the pressure encapsulation step is omitted. In addition, it is possible to shorten the process time and improve the yield by eliminating the pressure encapsulation step.

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

2A and 2B illustrate a liquid crystal panel according to an embodiment of the present invention.

FIG. 2A is a side view of the liquid crystal panel, and FIG. 2B is a cross-sectional view taken along the line II-II of FIG. 2A.

As described above, the liquid crystal panel 270 is formed by combining the color filter substrate 200 and the TFT substrate 210.

As shown in FIG. 2B, a plurality of red (R), green (G), and blue (B) color filters 250 are sequentially arranged on the color filter substrate 200, and the colors of R, G, and B are sequentially arranged. The filters 250 gather to form one pixel. Colors are realized through additive mixing of light passing through the color filters 250 of R, G, and B. Although not shown in the drawing, a black matrix (BM) is formed between the color filters 250 representing each color. The BM serves to improve the contrast ratio of the liquid crystal panel by blocking light from passing through the liquid crystal in an uncontrolled portion of the pixel array of the TFT array. In addition, BM also serves to prevent light leakage current of the TFT by blocking direct light irradiation of the TFT.

The color filter 250 is formed using a photolithography technique, and uses a color photo resist (PR) containing pigment particles. In addition, an over coat layer (not shown) is formed on the surface of the color filter 250 in order to form a good step in forming the column spacers 220 and 230. The flattening layer may not be formed by patterning an edge of the color filter 250 at a gentle angle.

As described above, a plurality of first column spacers 220 and second column spacers 230 are formed on the planarization layer of the color filter substrate 200. When the color filter substrate 200 and the TFT substrate 210 are bonded to each other, a cell gap is formed by the first column spacer 220. The second column spacer 230 is formed lower than the height of the first column spacer 220 as shown in the figure.

The first column spacer 220 and the second column spacer 230 are formed to overlap the BM with a uniform density throughout the color filter substrate 200. Therefore, the liquid crystal is filled in the liquid crystal panel 270 with a uniform density. The second column spacer 230 is indicated by hatched lines.

The density of the column spacers 220 and 230 is determined in consideration of the area of the liquid crystal panel to be manufactured. As shown in the drawing, the column spacers 220 and 230 mix and arrange the first column spacer 220 and the second column spacer 230 evenly. In the drawing, the first column spacer 220 and the second column spacer 230 are alternately arranged in the lateral direction.

The second column spacer 230 adjusts the amount of liquid crystal filled in the liquid crystal panel 270. Since the second column spacer 230 occupies a certain volume in the liquid crystal panel 270, the liquid crystal is less filled in the liquid crystal panel 270 by the volume. That is, in the related art, the liquid crystal is filled in the liquid crystal panel, and then the extra liquid crystal is discharged through the pressure encapsulation process to prevent gravity generation. The column spacer 230 is formed to initially fill an appropriate amount of liquid crystal.

When the liquid crystal injection hole is sealed after filling only the appropriate amount of liquid crystal by the liquid crystal injection method without forming the second column spacer 230, the encapsulant is sucked into the liquid crystal panel due to the pressure inside the liquid crystal panel to fill the filled liquid crystal. The liquid crystal panel according to the exemplary embodiment of the present invention may be contaminated, and it may be prevented by using the second column spacer 230.

3A to 3D are cross-sectional views showing a method of manufacturing a liquid crystal panel according to an embodiment of the present invention.

First, as shown in FIG. 3A, a photosensitive resin 300 such as photo acryl, which is an acrylic resin, is uniformly coated on the color filter substrate 200 by a desired cell gap thickness.

Thereafter, as shown in FIG. 3B, the diffraction mask 310 in which the pattern of the column spacer is formed is aligned on the color filter substrate 200 to which the photosensitive resin 300 is applied. At this time, since the shrinkage and expansion of the substrate due to the temperature change causes misalignment, maintaining a constant temperature is very important.

Next, ultraviolet rays are irradiated to the photosensitive resin 300 through a pattern formed in the diffraction mask 310. The photosensitive resin has a positive type in which a region irradiated with ultraviolet rays reacts with a developer, and a negative type in which a region irradiated with ultraviolet rays does not react with a developer. In FIG. 3, a photosensitive resin having a positive type is used. The case is illustrated.

4 is a plan view illustrating a diffraction mask used in FIG. 3B.

The mask is made of a thin glass plate covered with a thin film of material such as chromium (Cr) or iron oxide. Layout data designed using a computer-aided design (CAD) is input to an electron beam lithography system, and the electron beam is scanned on a glass plate coated with a photosensitive film according to the data, thereby providing a transparent or opaque pattern. It is formed on the glass plate.

The diffraction mask used in the embodiment of the present invention includes two types of first pattern 312 and second pattern 314. In the drawings, parts indicated by hatched parts represent opaque parts and other parts indicate transparent parts. Ultraviolet rays are irradiated through the transparent part. The use of a negative photosensitive resin causes the transparent and opaque portions of the mask to be interchanged.

The first pattern 312 is for forming the first column spacer 220, and the second pattern 314 is for forming the second column spacer 230. The areas of the first pattern 312 and the second pattern 314 coincide with the areas of the column spacers 220, 230. The second pattern is formed in a slit shape as shown in the figure. Although ultraviolet light does not pass through the first pattern 312, it partially passes through the second pattern 314 to irradiate the photosensitive resin. The amount of ultraviolet light emitted through the second pattern 314 may be adjusted at intervals between the slits.

When the ultraviolet ray is irradiated to the color filter substrate 200 coated with the photosensitive resin 300 using the mask 310 as described above and reacted with a developer, the first column spacer 220 and the second column spacer ( 230 is formed. The height of the second column spacer 230 may be adjusted by the slit interval of the second pattern 314 formed on the mask 310. The height of the second column spacer 230 is determined in consideration of the volume corresponding to the extra liquid crystal causing the gravity failure.

The position of the column spacers 220 and 230 is formed to overlap the BM of the color filter substrate 200 so that the aperture ratio does not decrease due to the column spacers 220 and 230, and the color filter substrate 200 is the TFT substrate 210. ), The column spacers 220 and 230 may be positioned above the wirings (gate wirings, data wirings, common wirings, etc.) of the TFT substrate 210.

3A to 3C illustrate the process of forming the column spacers 220 and 230 on the color filter substrate 200, but the column spacers 220 and 230 may also be formed on the TFT substrate 210. When the column spacers 220 and 230 are formed on the TFT substrate 210, the column spacers 220 and 230 may be formed at positions corresponding to the BMs of the color filter substrate 200 after the TFT array process is completed. However, since the manufacturing process of the color filter substrate 200 is simpler than the manufacturing process of the TFT substrate 210 and the structure color filter substrate 200 is simpler, the column spacers 220 and 230 may be formed on the color filter substrate 200. It is preferable to form.

After the column spacers 220 and 230 are formed on the color filter substrate 200, the color filter substrate 200 is bonded to the TFT substrate 210 as shown in FIG. 3D. The liquid crystal may be filled by vacuum injection after the two substrates 200 and 210 are bonded, or may be filled by dropping before the two substrates are bonded. The dropping method is introduced to shorten the filling time of the liquid crystal and is mainly applied to a large area liquid crystal panel. The dropping method is a method of dropping and dispensing a liquid crystal onto the color filter substrate 200 or the TFT substrate 210 and uniformly applying the liquid crystal to the entire image display area by the pressure of bonding the two substrates.

Although many details are set forth in the foregoing description, it should not be construed as limiting the scope of the invention but as interpreted as a preferred embodiment. Therefore, the scope of the invention should not be defined by the described embodiments, but should be defined by the claims and their equivalents.

According to the present invention, it is possible to prevent the failure of gravity by using the second column spacer for adjusting the amount of liquid crystal filled in addition to the first column spacer for maintaining the cell gap of the liquid crystal panel. That is, by forming the second column spacer having a volume corresponding to the liquid crystal discharged by the pressure encapsulation process, it is possible to prevent the failure of gravity even if the pressure encapsulation process is omitted. In addition, since the pressure encapsulation step is omitted, there is an effect of shortening the manufacturing process time and improving the yield.

Claims (8)

A thin film transistor substrate; Color filter substrates; A plurality of first column spacers formed on one of the thin film transistor substrate and the color filter substrate to maintain a cell gap between the two substrates; And And a plurality of second column spacers formed on one of the thin film transistor substrate and the color filter substrate to be lower than the height of the first column spacer to control the amount of liquid crystal filled between the two substrates. panel. The liquid crystal panel of claim 1, wherein the first and second column spacers are formed of an acrylic resin. The liquid crystal panel of claim 1, wherein the first and second column spacers are formed on a color filter substrate. The liquid crystal panel of claim 1, wherein the first and second column spacers are distributed at a uniform density. Applying a photosensitive resin on top of any one of a color filter substrate and a TFT substrate; Patterning the photosensitive resin to form a plurality of first column spacers and a plurality of second column spacers having a height lower than that of the first column spacers; And And bonding the color filter substrate to the TFT substrate. The method of claim 5, wherein the forming of the first and second column spacers, Irradiating ultraviolet light to the photosensitive resin through a diffraction mask; And And developing the photosensitive resin irradiated with ultraviolet rays. The method of manufacturing a liquid crystal panel according to claim 5, wherein first and second column spacers are formed on the color filter substrate. The method of manufacturing a liquid crystal panel according to claim 5, wherein the first and second column spacers are formed at a uniform density.