BACKGROUND ART Recently, demands for display devices having high resolution, high quality and large size have increased, so that a lot of developments of such display devices have proceeded. The most widely used one out of the display devices is a thin film transistor liquid crystal display (TFT LCD) device. In the TFT LCD device, color display is implemented by passing white light emitted from a backlight through liquid crystal cells for adjustment of transmittance and mixing light passing though adjacent R, G, and B color filters on a color filter substrate. The color filter substrate comprises a plurality of R, G, and B color filters for implementing colors and black matrix patterns for shielding light, and transparent electrodes for

applying voltages on the liquid crystal cells. The transparent electrodes are made of indium tin oxide (ITO).

The method of manufacturing the color filters is classified into a dye method and a pigment method according to types of organic materials used. In addition, the method of manufacturing the color filters is also classified into a dying method, a dispersing method, and an electro- depositing method.

The most widely used method of manufacturing the color filters used for the TFT LCD device is the pigment dispersing method. R, G, and B color patterns necessary for manufacturing the color filters are formed with a photolithography process. In the photolithography process, the same mask is used for the R, G, and B color patterns.

While the mask is shifted by pixel pitch, an exposure process is performed on the R, G, and B color patterns. In general, a negative photoresist is used as a color photoresist. Therefore, a non-exposed portion is removed during a developing process, so that a pattern is completed.

In order to protect the R, G, and B color patterns, a planarization process is performed on surfaces of the color filters during a formation of a common pixel electrode.

Out of the planarization processes, there is a spin coating method using a polymer resin. Although the photolithography process of the conventional method results

in a uniform shape and thickness of printed ink, the conventional method has a problem in that the associated processes are very complicated and expensive.

Instead of the conventional method using the photolithography process, much attention has been paid on a method of manufacturing color filters used for display devices by using a printing method of printing inexpensive color patterns on a transparent substrate with simple processes.

In general, printing patterns for color filters used for LCD and PDP devices need to have a high accuracy, a uniform printing shape, and a uniform thickness. In a case where the conventional printing method is used to manufacture a color filter substrate, since the substrate is made of a transparent glass or resin, it is difficult to fix inks on the substrate. Therefore, in the color filter manufactured by using the conventional printing method, there are large variations in printing shape and thickness, so that highly accurate patterns cannot be obtained. As a result, it is difficult to manufacture the color filters used for LCD and PDP devices by using the conventional printing method.

FIG. 5 is a schematic cross-sectional view for explaining steps of a conventional printing method of printing a predetermined pattern on a substrate. Firstly,

an ink 130 is applied on a mold 120 having convex and concave portions. The Ink 130 remaining on surfaces of the convex portions is removed by using a doctor blade 150. A substrate 140 is pressed on the mold 120. The ink 130 filled in the concave portions of the mold 120 is transferred to the substrate 140 in a predetermined pattern.

However, according to the printing method, the ink 130 filled in the concave portions is not entirely transferred to the substrate 140, but some of the ink (a residual ink 130b) is remained at the corners of the concave portions.

In addition, due to surface tension of the ink transferred on the substrate 140, flatness of the printed ink is not good. If the color filters used for the LCD or PDP devices are manufactured with the ink having bad flatness, the transmitting direction of light is varied and the transmittance of the color filters are lowered, so that the product quality may be lowered.

SUMMARY OF THE INVENTION In order to solve the problems, an object of the present invention is to provide a method of printing R, G, and B color patterns on a substrate with a high accuracy.

Another object of the present invention is to provide a method of manufacturing color filters used for display devices by using a printing method of printing inexpensive

color patterns on a transparent substrate with simple processes.

According to an aspect of the present invention, there is provided a printing method comprising steps of: preparing a mold; applying an ink to a surface of the mold having concave portions; transferring the ink applied to the surface of the mold to a substrate and curing the ink; and separating the mold from the substrate.

The step of transferring and curing the ink may comprise a step of curing the ink in a state that the surface of the mold is closely contacted with the substrate.

The ink may be a photo-curable ink, and the step of curing the ink may comprise a step of illuminating light to the ink. The ink may be a thermo-setting ink, and the step of curing the ink may comprise a step of heating the ink.

The ink may be a conductive ink.

The step of applying the ink to the surface of the mold having the concave portions may be performed by using a doctor blade.

The step of preparing the mold may comprise steps of: preparing a master on which a predetermined pattern is formed; filling a resin on the master; curing the resin on the master; and separating the mold from the master.

The resin may be a siloxane resin. The siloxane resin may be a polydimethyl siloxane resin.

The master may be manufactured by using a photolithography process.

The substrate may be a transparent substrate, and the pattern including a black matrix pattern may be formed on the transparent substrate. The substrate may be a transparent substrate, and the patterns including R, G, and B color patterns may be formed on the substrate. And then, it may be repeated the above-steps which are printing method comprising steps.

The R, G, and B color patterns may be disposed in a delta array. The R, G, and B color patterns may be disposed in a mosaic array.

According to another aspect of the present invention, there is provided a substrate printed by using the aforementioned printing method.

According to still another aspect of the present invention, there is provided a color filter manufactured by using the printing method.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which: FIG. 1 is a schematic cross-sectional view for

explaining steps of a method of manufacturing a mold according to the present invention; FIG. 2 is a perspective view for explaining steps of a method of manufacturing a mold according to the present invention; FIG. 3 is a schematic cross-sectional view for explaining steps of a method of printing a predetermined pattern by transferring an ink on a substrate and curing the ink according to the present invention; FIG. 4 is a perspective view for explaining steps of a method of printing a predetermined pattern by transferring an ink on a substrate and curing the ink according to the present invention; and FIG. 5 is a schematic cross-sectional view for explaining steps of a conventional printing method of printing a predetermined pattern on a substrate.

BEST MODE FOR CARRYING OUT THE INVENTION The present invention and operational advantages thereof can be fully understood by referring to the accompanying drawings and explanations thereof.

Now, exemplary embodiments of the present invention will be described with reference to the accompanying drawings to explain the present invention in detail. In the drawings, the same reference numerals indicate the same

elements.

FIGS. 1 and 2 are a schematic cross-sectional view and a perspective view for explaining steps of a method of manufacturing a mold according to the present invention, respectively.

Firstly, a master 100 on which a predetermined pattern is engraved with a photolithography method is prepared.

The master 100 is inserted within a mold frame 110. Next, a siloxane resin 125, for example, a polydimethyl siloxane resin, is applied on the master 100 within the mold frame 110. The siloxane resin 125 within the mold frame is kept at a horizontal level at a normal temperature for 5 to 7 hours in order to eliminate bubbles in the siloxane resin.

Next, the siloxane resin 125 is subjected to a curing process at a temperature of 30 to 100 °C for 2 to 10 hours.

When the cured siloxane resin 125 is separated from the master 110, the siloxane mold 120a is obtained. The siloxane mold 120a is a transparent polymer resin mold.

Now, a method of printing a pattern by using the siloxane mold 120a will be described. FIGS. 3 and 4 are a schematic cross-sectional view and a perspective view for explaining steps of a method of printing a predetermined pattern by transferring an ink on a substrate and curing the ink according to the present invention, respectively.

Firstly, a photo-curable ink 130a is applied on the

siloxane mold 120a. The photo-curable ink 130a is made of a polymer resin. Here, the siloxane mold 120a has convex and concave portions. The ink applied on the surfaces of the convex portions is removed with a doctor blade 150.

Instead of the aforementioned doctor blade method, various methods such as a spin coating method may be used. The siloxane mold 120a is covered with a substrate 140. Next, light is illuminated on the siloxane mold 120a. Since the siloxane mold 120a is transparent, the photo-curable ink 130a is cured by the light passing through the siloxane mold 120a. Alternatively, if the substrate 140 is transparent, light may be illuminated on the substrate 140 instead of the siloxane mold 130a. After the photo-curable ink 130a is cured, the siloxane mold 120a is separated from the substrate 140, so that the photo-curable ink 130a is printed in the same pattern as the master 110.

Alternatively, the substrate 140 may be pressed on the siloxane mold 120a while the photo-curable ink 130a is cured. As a result, the ink on the surfaces of the convex portions can be flown into the concave portions of the siloxane mold 120a or outside thereof.

The most important steps of the method are the step of applying the photo-curable ink 130a on the siloxane mold 120a and the step of illuminating light while the siloxane mold 120a is covered with the substrate 140.

The photo-curable ink 130a is a polymer material obtained by mixing a color filter pigment with a photo- curable polymer resin such as a negative photoresist in a predetermined mixing ratio. Alternatively, various inks such as thermo-setting ink may be used instead of the photo-curable ink.

The substrate 140 is a glass substrate on which black matrix patterns for shielding light are formed. R, G, and B color patterns are printed on the substrate 140 with the aforementioned printing method, so that a color filter used for a display unit can be obtained. The R, G, and B color patterns may be disposed in a stripe array, a delta array, or a mosaic array. In addition, the black matrix pattern may be also printed with the aforementioned printing method.

In addition, the aforementioned printing method using a conductive ink can be adapted to a printed circuit board, so that it is possible to obtain finer wiring patterns than a conventional one.

In addition, the Korean Patent Application No. 10- 2003-0041231 filed by the inventor of the present invention on 24 June, 2003, is incorporated into the present invention.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art

that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. The exemplary embodiments should be considered in descriptive sense only and not for purposes of limitation. Therefore, the scope of the invention is defined not by the detailed description of the invention but by the appended claims, and all differences within the scope will be construed as being included in the present invention.

INDUSTRIAL APPLICABILITY In case of a color filter manufactured by using a printing method according to the present invention, printed patterns are so uniform that light can be transmitted in a uniform transmitting direction with uniform transmittance.

As a result, color burring and specks are prevented, so that it is possible to obtain clear and bright display.

According to the present invention, color filters, which are conventionally expensive, can be easily manufactured in a mass production process with a high accuracy, so that it is possible to reduce costs of a TFT LCD, which is a digital display apparatus, using the color filters.

The siloxane mold manufactured by using the printing method according to the present invention can be subsequently used to manufacture color filters quickly with

very simple processes. The color pattern size can be obtained in a very wide range of nanometer to micrometer.

In addition, excellent uniformity and flatness of color patterns can be obtained.

In addition, a printing method using a conductive ink according to the present invention can be adapted to various semiconductor processes such as a fine-wiring process.