JPH08271715A - Color filter, its production and liquid crystal display device - Google Patents

Abstract

PURPOSE: To obtain a color filter free from color mixing, mottle, decoloration and having excellent flatness by forming ink dots around a picture element part in a color filter having the picture element part composed of a coloring member on a base material. CONSTITUTION: The color filter for liquid crystal is composed of a transparent substrate 2, a black matrix 3, a protective film 5 and the colored picture element part 14. The colored picture element part 14 is formed by coloring the picture element part by pigment dispersion method or ink jet method. Next, the flatness of the color filter surface is improved by providing the ink dots 15 around the colored picture element part 14. At this time, water repellent property is sometimes given to the vicinity of the colored picture element part 14 to impart color mixing preventive function. In such a case, though the ink to be used is properly selected from hydrophobic ones to hydrophilic ones, the ink dots excellent in flatness is formed by using a hydrophilic ink <40dyn/cm in surface tension to form the ink dots.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a color filter for a color liquid crystal display used in a color television, an in-vehicle television, a personal computer, a pachinko game table, etc., and particularly to a liquid crystal color filter utilizing an ink jet recording technology. The manufacturing method is related.

[0002]

2. Description of the Related Art In recent years, the development of personal computers,
In particular, with the development of portable personal computers, the demand for liquid crystal displays, especially color liquid crystal displays, is increasing, and the demand for cost reduction of color filters with a high cost ratio is increasing for further widespread use.

Various methods have hitherto been attempted to meet the above-mentioned requirements while satisfying the required characteristics of the color filter, but a method satisfying all the required characteristics has not been established. Each method will be described below.

The first method is a dyeing method. The dyeing method consists of first forming a water-soluble polymer material, which is the material to be dyed, on the glass substrate and then patterning it into the desired shape by the photolithography process. Get the pattern. By repeating this process three times, R, G, and B color filter layers are formed.

The second method is a pigment dispersion method. In the pigment dispersion method, first, a photosensitive resin layer in which a pigment is dispersed is formed on a glass substrate, and this is patterned to obtain a monochromatic pattern. By repeating this process three times, R,
The G and B color filter layers are formed.

The third method is an electrodeposition method. In the electrodeposition method, a transparent electrode is first patterned on a glass substrate and immersed in an electrodeposition coating solution containing a pigment, a resin, an electrolytic solution and the like to electrodeposit the first color. By repeating this process three times, R, G,
The color filter layer of B is formed and finally fired.

The fourth method is a printing method. In the printing method, a pigment is dispersed in a thermosetting resin, printing is repeated three times to form R, G, and B color filter layers, and then the resin is thermoset to form a colored layer. .

In any of these methods, a protective layer is generally formed on the colored layer.

The common points of these methods are R,
It is necessary to repeat the same process three times in order to color the three colors of G and B, which is costly. Further, there is a problem that the yield decreases as the number of processes increases.
Further, in the electrodeposition method, since the pattern shape that can be formed is limited, the current technology cannot be applied to TFTs. In addition, since the printing method has poor resolution, a fine pitch pattern cannot be formed.

[0010]

In order to make up for these drawbacks, a method of manufacturing a color filter using an ink jet method is disclosed in JP-A-59-75205 and JP-A-6-75205.
There are proposals disclosed in Japanese Patent Application Laid-Open No. 3-235901, Japanese Patent Application Laid-Open No. 1-217302, etc., but they are still insufficient. This is particularly remarkable in flatness.

Therefore, an object of the present invention is to solve the problems of the required characteristics such as heat resistance, solvent resistance, and resolution that the conventional methods have, and to provide an inexpensive color filter manufacturing method with a short process and the method thereof. An object is to provide a highly reliable color filter that is manufactured.

In particular, it is required to prevent color mixture and color loss when arranging colorants by ejecting ink by an ink jet system and to have flatness of 0.1 μm level.
It is an object of the present invention to provide a method of manufacturing a color filter having flatness that can be sufficiently used for a TN liquid crystal display device.

Another object of the present invention is to provide a liquid crystal panel (liquid crystal display device) having such a color filter and capable of displaying a high-definition image.

[0014]

This object can be achieved by the means shown below.

That is, according to the present invention, in a color filter having a pixel portion made of a coloring member on a substrate, ink dots (hereinafter referred to as "pixel portion surrounding ink dots") are formed around the pixel portion. A color filter, in particular, a color filter in which the pixel portion is formed by coloring with colored ink dots (hereinafter, referred to as “pixel portion ink dots”); In a color filter having a part,
Ink dots are formed around the pixel portion, and a protective film is formed on the substrate, and in particular, a color filter in which the pixel portion is formed by coloring with colored ink dots. And a color filter and a substrate at a position facing the color filter, and a liquid crystal layer is formed between the substrates.

Further, the present invention includes at least a step of coloring the pixel portion formed on the substrate and a step of ejecting ink to the peripheral portion of the pixel portion to form ink dots (ink dots around the pixel portion). And a method for manufacturing a color filter, in which a pixel portion is colored by an inkjet method.

Further, the present invention has the above-mentioned color filter and a substrate at a position facing the color filter,
Provided is a liquid crystal display device in which a liquid crystal layer is formed.

[0018]

The present invention will be described in detail below.

FIG. 1 shows an example of the structure of a color filter for liquid crystal according to the present invention. In this figure, 2 is a transparent substrate, 3 is a black matrix, 5 is a protective film, and 14 is a colored pixel portion.

Although glass is generally used as the transparent substrate in the color filter of FIG. 1, plastic may be used as long as it has necessary properties such as transparency and strength as a color filter for liquid crystal, and is not limited to the glass substrate. Not something.

The colored pixel portion can be formed by coloring the pixel portion by a pigment dispersion method or an inkjet method.

When the colored pixel portion is formed by the ink jet method, a droplet of a coloring liquid is jetted from an ink jet head to a predetermined portion of the transparent substrate, and the formed ink dot of the pixel portion is dried to form each colored layer. To form. At this time, as a receiving layer for receiving the coloring liquid, a receiving layer made of an ink absorbing resin or the like may be provided in advance in the colored portion for the purpose of improving the fixing property of the coloring liquid. As the ink-absorbing resin, polyvinyl alcohol, polyvinylpyrrolidone, cellulose derivatives such as hydroxypropylcellulose, water-soluble acrylic resin, etc. are preferably used, and they may be formed in a matrix at the colored portion or on the entire surface of the substrate 2. it can.

Further, in the present invention, as shown in FIGS. 3 and 5, ink dots 15 are provided around the colored pixel portion to enhance the flatness of the color filter surface. At this time, water repellency may be given to the periphery of the colored pixel portion for the purpose of imparting a color mixing prevention function. In that case, the ink to be used can be appropriately selected from hydrophobic to hydrophilic ones. However, when ink dots are formed using a hydrophilic ink having a surface tension of 40 dyne / cm or less, flatness as shown at 15 in FIG. 3 is obtained. It is possible to form ink dots of high quality, which is preferable.

On the other hand, FIG. 4 schematically shows a color filter obtained by a conventional protective film forming method in which a protective film is formed on the entire surface. In this way, when the protective film is formed on the entire surface, a step difference between the black matrix portion and the colored pixel portion is remarkable.

Considering the characteristics desired for the color filter, the desired flatness is defined as the difference between the distance between the ink dots in the pixel area and the upper surface of the substrate and the distance between the ink dots surrounding the pixel area and the upper surface of the substrate. However, it is desirable that it be 0.5 μm or less. In the color filter obtained by the present invention, such flatness is realized.

Further, in the color filter of the present invention, after forming the ink dots around the pixel portion, by applying a protective film on the substrate by a method such as spin coating, the flatness is further enhanced, and the distance difference is 0.2 μm or less. It is possible to obtain a very good color filter of.

When forming ink dots around the pixel portion, the ink dot may reach the colored pixel portion. Therefore, in order to prevent a decrease in the transmittance of the colored pixel portion in that case, it is preferable that the ink used for forming the ink dots around the pixel portion be translucent.

A protective film 5 may be formed, if necessary, on the transparent substrate or the underlayer on which the colored layer is formed. As the protective film, photo-curing type, heat-curing type or heat
A resin material that can be used with light, an inorganic film formed by vapor deposition, sputtering, etc. can be used, and it can be used as long as it has transparency when used as a color filter and can withstand the alignment film formation process. Is.

FIG. 2 shows an example of a liquid crystal panel of a liquid crystal display device using the color filter of the present invention. In the figure, 1 is a polarizing plate, 2 is a transparent substrate such as glass, 3 is a black matrix, 4 is a base layer (receptive layer), 5 is a protective film, 6 is a common electrode, 7 is an alignment film, 8 is a liquid crystal compound, 9 is an alignment film, 10
Is a pixel electrode, 11 is a transparent substrate, 12 is a polarizing plate, 13 is backlight light, and 14 is a colored portion.

The liquid crystal panel generally has a liquid crystal compound enclosed between the fitted color filter and the counter substrate, and the substrate 11 facing the color filter as shown in FIG.
The transparent pixel electrodes 10 are formed in a matrix inside. The color filter is provided so that the R, G, and B color materials are arranged at positions facing the pixel electrode 10.

Further, an alignment film 7 is formed inside both substrates, and by rubbing the alignment film 7, liquid crystal molecules can be aligned in a certain direction. A polarizing plate is adhered to the outside of each substrate, and the liquid crystal compound is filled between these substrates. A combination of a fluorescent lamp and a scattering plate (not shown) is generally used as the backlight, and a liquid crystal compound functions as an optical shutter that changes the transmittance of the backlight light 13 to perform display.

The ink jet recording head used for forming the color filter of the present invention may be a system utilizing thermal energy or a system utilizing mechanical energy, and any system can be preferably used.

[0033]

The present invention will be described below in detail with reference to examples.

Example 1 Formation of Black Matrix A 200 mm square chromium thin film was sputtered onto a glass substrate made of alkali-free glass whose surface had been polished by sputtering.
It is formed to a thickness of 2 μm and is subjected to photolithography, as shown in FIG.
Patterned into a shape like. At this time, in FIG. 5, W = 60 μm, L = 120 μm, d ₁ = 20 μm, d ₂
= 100 μm. Formation of Receptor Layer Next, on the glass substrate on which the above black matrix was formed, methyl methacrylate, hydroxyethyl methacrylate and N- were formed so as to have the composition shown in Table 1.
A photosensitive resin composition prepared by dissolving an acrylic copolymer formed from methylol acrylamide and triphenylsulfonium hexafluoroantimonate in ethyl cellosolve was spin-coated, dried at 90 ° C. for 10 minutes, and then exposed at a thickness of 2 μm. A resinous layer was formed and used as an ink receiving layer.

[0035]

[Table 1] Next, pattern exposure was performed with an exposure amount of 150 mJ / cm ² through a photomask having an opening portion narrower than the width of the black matrix, and development processing was performed to form a resist pattern as a color mixing prevention wall on the black matrix. . Preparation of Colored Inks R, G, and B color inks were prepared with the compositions shown in Table 2.

[0036]

[Table 2] ¹⁾ C.I. I. Pigment Red 168 and C.I. I. Pigment Orange 36 23: 8 mixture ²⁾ C.I. I. Acid Blue 9 and C.I. I. Acid Yellow 23 7: 2 mixture ³⁾ C.I. I. Pigment Blue 60 and C.I. I. Pigment Violet 23 9: 2 Mixture Furthermore, after the R, G, B matrix pattern of the openings was colored with the above ink using an inkjet head,
Dry at 0 ° C for 20 minutes and then at 230 ° C for 60 minutes.
The coloring composition layer was cured by performing heat treatment for 1 minute.

Ink dots are formed around the colored pixel portion thus formed with the translucent ink shown in Table 3 using an inkjet head, dried at 90 ° C. for 20 minutes, and then at 230 ° C. for 60 minutes. Was heat treated to cure.

[0038]

[Table 3] When the color filter for liquid crystal produced in this manner was observed with an optical microscope, there were no color mixture, color unevenness, or color loss, and the distance between the pixel area ink dots and the substrate upper surface and the distance between the pixel area surrounding ink dots and the substrate upper surface were Was 0.5 μm or less.

Further, when the liquid crystal panel shown in FIG. 2 was prepared by using this color filter and driven, a high contrast was obtained and a high-definition color display was possible.

(Example 2) After forming colored pixel portions and translucent ink dots in the same manner as in Example 1, a two-component thermosetting resin composition (Optomer SS6688 (manufactured by Japan Synthetic Rubber) and Optomer SSO688) was used. (A 3.7: 1 mixture of Japan Synthetic Rubber) was spin-coated to a film thickness of 1 μm, dried at 90 ° C. for 20 minutes, and then heat-treated at 230 ° C. for 60 minutes to be cured to form a protective film. , A color filter for liquid crystal was created.

When the color filter for liquid crystal thus produced was observed by an optical microscope, there was no color mixture, color unevenness, or color loss, and the ink dots in the pixel area and the ink dots around the pixel area were higher than the upper surface of the substrate. Difference is 0.
The range was 2 μm or less.

Further, when the liquid crystal panel shown in FIG. 2 was prepared using this color filter and driven, high contrast and high-definition color display were possible.

Comparative Example 1 A color filter was prepared in the same manner as in Example 1 except that the translucent ink dots were not formed around the colored pixel portion.

Comparative Example 2 A color filter was prepared in the same manner as in Example 2 except that the translucent ink dots were not formed around the colored pixel portion. Evaluation (Evaluation of flatness of color filter upper surface) The flatness of the color filter upper surface prepared in the above Examples 1 and 2 and Comparative Examples 1 and 2 was evaluated by the stylus type film thickness meter (P
-10 Profiler: manufactured by Tencor Co., Ltd.). The measurement was performed on the portion shown in FIG. 3 or FIG. The results are shown in Table 4.

[0045]

[Table 4] As is clear from the results in Table 4, the color filter obtained by the method of the present invention has higher flatness than the conventional one.

[0046]

According to the present invention, it is possible to inexpensively manufacture a color filter having no color mixture, color unevenness, color loss, and good flatness, and using the color filter,
A liquid crystal display device capable of high-definition image display can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of one embodiment of a color filter according to the present invention.

FIG. 2 is a schematic cross-sectional view of an example of a liquid crystal panel having a color filter according to the present invention.

FIG. 3 is a color filter 1 of the present invention in which a hydrophilic translucent ink dot containing a surfactant is provided around a colored pixel portion.
It is a typical sectional view of an example.

FIG. 4 is a schematic cross-sectional view of an example of a conventional color filter in which hydrophilic translucent ink dots are not provided around a colored pixel portion.

FIG. 5 is a plan view showing a pixel configuration of a color filter of Example 1.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Polarizing plate 2 Transparent substrate 3 Black matrix 4 Receptive layer 5 Protective film layer 6 Common electrode 7 Alignment film 8 Liquid compound 9 Alignment film 10 Pixel electrode 11 Transparent substrate 12 Polarizing plate 13 Backlight 14 Coloring part 15 Ink dots

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koichiro Nakazawa 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (14)

[Claims] 1. A color filter having a pixel portion made of a coloring member on a substrate, wherein ink dots (ink dots surrounding the pixel portion) are formed around the pixel portion. . 2. The color filter according to claim 1, wherein the difference between the distance between the ink dots in the pixel area and the upper surface of the substrate and the distance between the ink dots around the pixel area and the upper surface of the substrate is 0.5 μm or less. 3. A color filter having a pixel portion made of a coloring member on a substrate, ink dots (ink dots around the pixel portion) are formed around the pixel portion, and a protective film is formed on the substrate. A color filter characterized by being formed. 4. The difference between the distance between the protective film surface on the ink dots of the pixel portion and the upper surface of the substrate and the distance between the protective film surface on the ink dots around the pixel portion and the upper surface of the substrate is 0.2 μm or less. The color filter according to claim 3, wherein 5. A pixel section is formed in a predetermined region of a photosensitive resin layer formed on a substrate, and a color mixing prevention wall obtained by photocuring the photosensitive resin layer surrounds the pixel section. The color filter according to any one of claims 1 to 4, wherein the ink dots around the pixel portion are formed on the color mixing prevention wall. 6. The color filter according to claim 1, wherein the pixel portion is formed by coloring by a pigment dispersion method. 7. The color filter according to claim 1, wherein the pixel portion is formed by coloring with colored ink dots (pixel portion ink dots). 8. The color filter according to claim 1, wherein the ink dots around the pixel portion are translucent. 9. A liquid crystal display device comprising a color filter according to claim 1, a substrate at a position facing the color filter, and a liquid crystal layer formed between the substrates. 10. A method comprising at least a step of coloring a pixel portion formed on a substrate and a step of ejecting ink to a peripheral portion of the pixel portion to form ink dots (ink dots around the pixel portion). Method for manufacturing color filter. 11. A photosensitive resin layer is formed on a substrate, a pixel portion is formed in a predetermined region of the resin layer, and the photosensitive resin layer around the pixel portion is photo-cured to form a color mixing prevention wall. 11. The manufacturing method according to claim 10, wherein the ink dots around the pixel portion are formed on the color mixing prevention wall. 12. The manufacturing method according to claim 10, wherein the method is a pigment dispersion method for the pixel portion. 13. The manufacturing method according to claim 10, wherein the pixel portion is colored by an inkjet method. 14. The manufacturing method according to claim 13, wherein the ink dots around the pixel portion are formed by using an ink whose surface tension is adjusted to 40 dyne / cm or less.