KR20070077677A - Flatness method with height gap of color filter in tft-lcd and color filter board - Google Patents

Abstract

A color filter and a manufacturing method thereof are provided to control and to flat the step between the color filters when implementing the color filter by an ink jet printing manner. Black matrix partitions(22) are formed on a substrate. Color ink is injected on a pixel area between the black matrix partitions so that plural color filters(23) are formed. A planarization process is formed so that the difference of height is generated between plural color filters. A compression process is performed at each color filter and a step between filters is generated. The compression process is performed by a compression roller(24) and a compression plate for compressing the surface of the color filter. Plural compression bars with different length are formed at the surface of the compression roller and the compression plate. The compression bar is made of materials with the low surface tension.

Description

Flatness method with height gap of color filter in TFT-LCD and color filter board}

1 is a view showing a state in which a color filter substrate is formed by the step planarization according to an embodiment of the present invention.

Figure 2 is a diagram showing a process of the step planarization according to an embodiment of the present invention.

Figure 3 is a figure showing a flattened state with a step.

Figure 4 is a perspective view showing the appearance of the compression roller according to an embodiment of the present invention.

Figure 5 is a perspective view showing the appearance of the compression plate according to another embodiment of the present invention.

* Description of the symbols for the main parts of the drawings *

21: glass substrate 22: black matrix bulkhead

23: Color filter 24: Compression roller

25: compression bar

The present invention relates to a method for flattening by adjusting the step between the color filters when the color filter of the liquid crystal display device is implemented by the inkjet printing method. Each color filter sprayed by the inkjet printing method is uniformly fixed using a compression roller. It is characterized in that it is prepared by flattening to have a step.

A color screen implemented in a liquid crystal display device such as a TFT-LCD includes a TFT for controlling the transmittance of white light of a back light (B / L), an operation of a liquid crystal cell, and a color filter of red / green / blue ( C / F; Color Filter (C / F) is achieved through additive mixing of three primary colors that pass through the substrate. Conventional methods for forming the color filter substrate include an electrodeposition method, a printing method, a dyeing method, a dispersion method, an inkjet printing method, and the like, wherein the electrodeposition method is performed by placing a glass substrate on which an ITO is attached in an electrodeposition tank and using electrophoresis. As a method of forming a layer, it belongs to inferior technology in terms of smoothness, but has been put to practical use after dyeing, and the main problems are the complexity of the process and difficulty in managing the process during mass production. The printing method is a method of forming a black matrix and an R, G, B pattern by sequentially printing an ink dispersed with an pigment in an organic vehicle on a glass substrate, thereby simultaneously reducing film formation and patterning, thereby reducing costs. However, high quality graphics such as large TVs have disadvantages that are inadequate manufacturing techniques.

On the other hand, the inkjet printing method is a method of filling ink into a black matrix partition fabricated by photolithography, and a color filter substrate manufacturing technology using the inkjet printing method simplifies the color filter manufacturing process and thus costs. In addition, the high quality graphic can be easily realized, and is being spotlighted as an innovative technology.

However, the inkjet printing method in which ink is filled in the organic black matrix (BM) partition walls has problems such as poor pixel internal uniformity, overflow of RGB ink on organic BM, and color mixing. In particular, the problem of poor uniformity inside the pixel may result in problems such as poor alignment of the alignment film and poor liquid crystal driving due to poor color filter (C / F) planarization.

One of the proposed methods to solve the planarization problem is to planarize the entire surface by polishing the entire surface, but in this case, the R, G, and B color filters all have the same height, so that the visibility of the gamma curve can be optimized. It was difficult to maintain the B> G> R thickness step, and there were problems such as spectral characteristics management before and after polishing and glass staining.

The present invention has been made to solve the above problems, but in the prior art, the entire color filter is polished in a batch to achieve a leveling operation without a step, but in the present invention, the leveling is performed while the leveling is performed for each color filter. It is done. In addition, it is characterized by using a predetermined compression roller in order to achieve a flattening having a step for each color filter as described above.

In order to achieve the above object, the present invention provides a process for forming a black matrix partition on a substrate, forming a plurality of color filters by spraying color ink on a pixel region between the black matrix partitions, and the plurality of color filters. It includes the process of performing the planarization that a constant height difference occurs between each other. The present invention also includes a black matrix partition formed on the substrate at a predetermined interval and a plurality of color filters formed between the black matrix partitions, wherein the plurality of color filters have different heights for each color and the same color color filters have a height. It is characterized by the same planarization.

Hereinafter, the detailed description of the preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various forms, and only the embodiments are intended to complete the disclosure of the present invention, and the scope of the invention to those skilled in the art. It is provided for complete information.

1 is a view sequentially showing the entire manufacturing process of the color filter substrate of the inkjet printing method according to an embodiment of the present invention.

On the glass substrate 11 for a liquid crystal display device, a light blocking black matrix partition 12 is formed by patterning an organic material having a thickness of about 2000 to 4000 angstroms by a photolithography process. Thereafter, R, G, and B color inks are sprayed on the pixel areas between the black matrix barrier ribs to form respective color filters 13 as shown in FIG. The color filter formed between the black matrix partitions 12 hardens the surface after baking for 90 seconds on a hot plate of 80 to 110 degrees. The reason for the surface curing process is that, when the operation of pressing the surface of the color filter with the compression roller for the RGB flattening, the appropriate temperature and time (for example, 80 ~ 110) to prevent the ink from being transferred to the compression roller For 90 seconds) to cure the color filter surface. In this case, if there is no problem in the subsequent compression process, the surface curing process may be omitted.

After the surface hardening operation for the R, G, and B color filters is completed as described above, the flattening operation using the compression roller is performed so that the color filter has a step. In the prior art, the entire color filter was polished in a batch, and a flattening operation without a step was made, but in the present invention, the flattening operation is performed as shown in FIG. 1 (b) to have a step having a different height for each color filter by a compression roller.

After the flattening operation with the step difference is completed as described above, in order to protect the black matrix bulkhead 12 (BM) and the color filter 13 from external impact, the surface hardness is high and the light transmittance is excellent, for example, polyimide, polyacryl After forming a transparent resin such as a rate or a polyurethane to a thickness of about 0.5 ~ 3㎛ and heated for 5 minutes at 150 ~ 120 degrees hot plate to form a protective film 14 (Over Coat Layer) as shown in Figure 2 (c) do. Thereafter, the transparent electrode film 15 of ITO to which the voltage for driving the liquid crystal is applied is formed on the entire surface of the protective film 14 to a thickness of about 500 to 1300 angstroms to complete the color filter substrate.

As a result, the present invention is a color filter substrate of the inkjet printing technique is completed through the process as shown in Figure 1, in particular, the present invention, unlike the prior art that the planarization operation is performed by the entire polishing, in particular, Figure 1 (b) As shown in FIG. 1, the flattening operation is performed while the height of each color filter has a different level for each R, G, and B color. That is, the present invention can flatten the surface of the color filter by adjusting the step of each RGB color filter by the inkjet printing method. As a result, the visibility of the color filter substrate manufactured by the photolithographic method can be ensured and the process margin can be sufficiently secured in the process proceeding after the color filter.

In order to clearly show the technical features as described above of the present invention will be described in more detail in conjunction with FIG.

2 is a flowchart illustrating a process of planarizing the color filter so that the color filter has a step by a compression roller according to an exemplary embodiment of the present invention.

First, a black matrix partition patterned by photolithography or the like is formed on the glass substrate 21 to serve as a boundary other than the pixel region where the pixel is formed (S21). That is, a predetermined material such as a metal film such as Cr or a black resin film is coated on a glass substrate with a predetermined thickness, and then exposed to ultraviolet (UV) light using a photomask, as shown in FIG. 2 (a). The black matrix partition wall 22 is formed. The black matrix partition 22 serves as a black matrix to increase contrast ratio by preventing light from leaking into the thin film transistor, gate wiring, and data wiring regions of the liquid crystal display.

As a material used for forming the black matrix partition wall 22, a material having a high repulsive force against ink injected into the pixel region between the black matrix partition walls is used. The reason why the black matrix bulkhead material is used as a material with high repulsive force against ink as described above is to have a concave shape due to the repulsive force with the black matrix formed by the color filter formed by the ink jet. Therefore, in the present embodiment, the organic black matrix (BM) is used.

After forming the black matrix partition wall as shown in FIG. 2A, a predetermined ink is sprayed on the pixel region between the black matrix partition walls 22 to form the RGB color filter 23 as shown in FIG. That is, red (R), green (G), and blue (B) inks are injected into the pixel region defined by the transparent openings between the black matrix barrier ribs by the inkjet printing method, thereby causing red (R), green (G), and blue (blue) ink. The color filter 23 of (B) is formed.

The color filter 23 is formed by spraying each color ink of RGB into a pixel region between black matrices according to a predetermined arrangement (for example, a stripe arrangement, a mosaic arrangement, and a delta arrangement). The inkjet injection method may be a thermal method or a piezoelectric method. In the piezoelectric method, the inkjet jetting apparatus is constituted by an inkjet jetting apparatus, and the inkjet jetting apparatus includes a container containing ink to be jetted, and an inkjet head for jetting ink from the container.

After the color filter 23 is formed as shown in FIG. 2 (b), as shown in FIG. 2 (c), baking is performed on a hot plate for a predetermined time to advance surface hardening. The reason for the surface curing process is to have a baking process to prevent ink from being transferred to the compression roller when the color filter 23 is pressed by the compression roller for RGB flattening.

After the surface curing process is completed, the flattening operation is performed using the compression roller 24 so that the flattening is performed with the step between the color filters 23 as shown in FIG. The flattening operation having the step is performed by a compression roller 24. The surface of the compression roller is provided with a compression bar 25 which is designed to have a different height for adhering and compressing the color filter. That is, the heights of the respective compression bars 25 (the R compression bar, the G compression bar, and the B compression bar) of the compression roller are differently patterned so that a step between the color filters 23 occurs. For example, in order to implement the height of the color filter 23 to have a R <G <B step, the height of the compression bar 25 of the compression roller is implemented in the order of R> G> B. At this time, each color filter 23 formed on the glass substrate and the compression bar 25 corresponding thereto are precisely aligned to obtain a color filter 23 having a desired height for each RGB color. As shown in FIG. 2E, a cross-sectional view of the color filter in which the flattening step is made by the compression roller is shown. As a result, through the process of FIG. 2, a color filter having a desired height for each of R, G, and B colors is manufactured in each unit pixel including the R, G, and B color filters. The color filters having different heights are repeatedly uniformly distributed over the entire display area as shown in FIG. 3 to achieve flattening with step adjustment. At this time, it is preferable to have the same height between each R color filter in the color filter substrate. Similarly, it is preferable to have the same height between each G color filter in the color filter substrate, and preferably to have the same height between each B color filter.

As shown in FIG. 3, the height difference of each color filter is generated in the order of R <G <B, so that the visibility of the liquid crystal display may be improved. In general, in the case of a display device implemented with an RGB color filter, the visibility is improved as the R <G <B height difference occurs, so that the flattening is performed with a difference in the height of the R, G, and B color filters according to the present invention. The visibility can be improved.

On the other hand, in Figure 2d is shown a simple planarization of the shape of the compression roller 24, the actual implementation of the compression roller has a cylindrical shape as shown in FIG. Along the surface of the cylindrical compression roller 24, the compression bars 25a, 25b, 25c pressing the color filters formed between the black matrix partition walls are patterned by varying their heights. That is, the compression bar is the R compression bar (25a) pressing the R color filter, the G compression bar (25b) pressing the G color filter, the B compression bar (25c) pressing the B color filter, the height of the compression roller 24 Repeatedly formed on the surface of the. Each of the gaps 41, 42, and 43 between the R compression bar 25a, the G compression bar 25b, and the B compression bar 25c can accurately press the color filters formed between the black matrix partitions on the glass substrate. It should be formed at the same interval as that between the color filters formed on the glass substrate.

In addition, the flattening of the color filter may be performed by the compression roller as described above. As another embodiment of the present invention, the present invention may be implemented by using the compression plate 51 shown in FIG. 5. In order to make the spacing of the compression bar formed on the surface of the compression roller equal to the distance between the color filters, it is necessary to have a spacing of micrometers. There may be difficulty in manufacturing the compression bar when implementing the compression bar on the compression roller. Therefore, flattening of the color filter is performed by using the compression plate 51 shown in FIG. The compression plate is repeatedly formed with R, G, B compression bars of different lengths.

Meanwhile, the inside of the compression bar patterned on the surface of the compression roller 24 or the compression plate 51 is made of a rigid material such as metal so that the compression force can be transmitted, and the surface material of the compression bar is RGB ink and In consideration of the relationship, the material having a low surface tension (for example, silicon rubber) is used.

In the foregoing description of the present invention, specific embodiments have been described, but various modifications may be made without departing from the scope of the present invention. Therefore, the scope of the present invention is not to be determined by the embodiments described above, but will be apparent in the claims as well as equivalent scope.

As described above, the present invention provides a method of flattening the surface of the liquid crystal display device by the inkjet printing method with a different level of height of each color filter. There is an effect that can solve the problem of visibility impairment generated during the planarization, the problem of staining the glass substrate, and the like.

Claims (11)

Forming a black matrix bulkhead on the substrate, Forming a plurality of color filters by spraying color ink on the pixel area between the black matrix partition walls; A process of performing planarization in which a constant height difference occurs between the plurality of color filters. Method of manufacturing a color filter of the liquid crystal display comprising a. The method of claim 1, further comprising baking the color filter at a predetermined temperature to perform surface curing of the color filter before performing the compression operation. The color filter of claim 1, wherein the predetermined height difference between the plurality of color filters is generated by performing a compression operation for each color filter to generate a step between the color filters. How to manufacture. The method of claim 1, wherein the black matrix partition includes ink sprayed between the black matrix partition and a material having high repulsive force. The method of manufacturing a color filter of a liquid crystal display device according to claim 3, wherein the compression operation is performed by a compression roller and a compression plate capable of compressing the surface of each color filter. The color filter of claim 5, wherein the compression roller and the compression plate include a plurality of compression bars having different lengths on the surfaces of the compression roller and the compression plate so as to generate height differences between the color filters. Way. The method of claim 6, wherein the compression bar comprises a material having a low surface tension in order to closely compress the color filter. The method of claim 6, wherein the compression bar has a length that is inversely proportional to the height of the corresponding color filter when the step is flattened. As a color filter substrate of a liquid crystal display device, A black matrix partition wall formed spaced apart at regular intervals on the substrate, And a plurality of color filters formed between the black matrix partition walls, wherein the plurality of color filters have different heights for each color, and color filters of the same color have the same height. 10. The color filter substrate of claim 9, wherein the black matrix partition wall is formed of a material having high repulsive force and ink sprayed between the black matrix partition walls. The color filter substrate of claim 9, wherein the color filter is flattened to have a height difference in an order of R <G <B.

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