JPH01248128A - Color filter - Google Patents

Abstract

PURPOSE:To enhance the image quality of an MIM color liquid crystal display element by using a specified organometallic compound as the second layer of a protective film. CONSTITUTION:The multicolor layer is formed on a transparent base 21, on this layer a transparent organic material layer 23 is formed as the first layer of the protective film, on this layer 23 as the second layer of the organic film is formed the organometallic oxide layer 24 obtained by dehydrating and condensing the main constituent of the organometallic compound represented by structural formula M(OR)nR'm-n (each of R and R' is an organic chain containing H; (m) is the number of the valence of the metal M; and (n) is an integer), further on this layer 24 as the third layer of the protective film is formed an oxide layer 25 by sputtering, and on the 3 layers of the protective film a transparent electrode having a specified pattern is formed, and finally, an orienting film 27 is formed by coating, thus permitting the color liquid crystal display element of the MIM (metal-insulator-metal) active matrix system to be obtained.

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a color filter used in liquid crystal display elements such as liquid crystal color televisions. [Prior art] Color filters are made of red (R) on a transparent substrate such as glass.
The three primary colors of , green (G), and blue (B) are colored in a mosaic or stripe pattern. Depending on the case, monochrome or bicolor ones may also be used. Conventionally, color filters used in MIM (metal-insulator-metal) active matrix type color liquid crystal display devices are transparent filters that usually have a stripe-like pattern on a transparent substrate such as glass, as shown in Figure 1. An electrode is formed, and then dyed layers in multiple colors are formed using proteins such as gelatin or acrylic resin as substrates, and after an organic protective layer is applied, an alignment film is formed. In addition to dyeing methods, there are printing methods, electrodeposition methods, and other methods for forming layers, but the olfactory structure itself can be said to be the same. However, when color filters with these structures are combined with a counter substrate to form a panel, the applied voltage is lost in the colored layer, which reduces the effective voltage that drives the liquid crystal, resulting in a decrease in display image quality ( especially contrast)
The problem was that it invited Therefore, in order to improve image quality, an ideal color filter structure would be to first form a colored layer on a transparent substrate, and then form a transparent electrode with a predetermined pattern on this colored layer. That is, the structure is such that the liquid crystal is sandwiched between the color filter side electrode and the counter substrate electrode with only an alignment film having a thickness of about 1,000 layers interposed therebetween. For this purpose, it is essential to form a protective film that satisfies at least the following conditions on the colored layer for the purpose of protecting the colored layer before forming the transparent electrode in the color filter. 1. The transparent electrode can be wet-etched into a predetermined pattern without damaging the colored layer.
In other words, chemical resistance) 2. The transparent electrode can be patterned cleanly without over-etching. 3. The patterned transparent electrode should not be disconnected during rubbing, which is an alignment process. (Since the colored layer is soft, the protective film has a certain degree of hardness, and cannot cover the softness of the colored layer when pressure is applied during rubbing.) The transparent electrode is easily cut, while the colored layer is uneven to some extent.
(Also, unless leveling is done with a protective film, the electrodes formed on top will be easily cut during rubbing.) 4. Impurity ions should not be eluted into the liquid crystal. However, because it has been difficult to find a highly reliable protective film material and protective film structure that satisfies the above conditions, it has not been possible to provide an MIM active matrix type liquid crystal display element with good image quality. [Problems to be Solved by the Invention] As mentioned above, in the conventional technology, in the structure of a color filter, it is necessary to form a transparent electrode with a predetermined pattern (usually in the form of a stripe) on a colored layer. There has been a problem in that a highly reliable protective film material and protective film structure cannot be secured, and therefore a high-quality MIM active matrix type color liquid crystal display element cannot be provided. The present invention is intended to solve these problems, and its purpose is to form colored layers of multiple colors on a transparent substrate, and then to form a first layer of a protective film on the colored layers. A transparent organic layer is formed, and then a second layer of a protective film is formed using an organometallic compound (the structural formula is M (OR)nR'm-n, M represents a metal, and R and R' are organic chains containing hydrogen). , m is an integer and m is the valence of the metal M), an organic metal oxide layer is formed by dehydration and condensation reaction of the component, and further a protective film is formed on the second protective film layer. As the third layer, a three-layer protective layer is provided by forming an oxide layer by sputtering, a transparent electrode with a predetermined pattern (usually striped) is formed on this protective layer, and finally an alignment film is formed. As mentioned above, unlike conventional color filters, when a zero-line color filter is used, when combined with an MIM substrate to form a panel, only an alignment film is interposed between the two substrates. Since the liquid crystal is sandwiched in this manner, the effective voltage for driving the liquid crystal increases, and it is possible to improve the image quality of the MIM active matrix type color display element. FIG. 2 shows a sectional view of the color filter of the present invention. [Means for Solving the Problems] The color filter of the present invention is provided by forming colored layers of multiple colors on a transparent substrate, and then forming a transparent organic layer (protective film No.-N) and an organometallic compound layer on the colored layer. After sequentially forming an organic metal oxide [(second protective film layer) by dehydration condensation and an oxide layer (third protective film layer) by sputtering to form a protective film of one colored layer, a predetermined pattern is formed on the protective film. It is characterized by forming a transparent electrode and an alignment film layer having the following characteristics. The colored layer can be formed by dyeing gelatin or acrylic resin as a dyeing substrate, by a printing method using ink containing organic pigments as a main component, or by an electrodeposition method. However, there are no particular restrictions. Next, regarding the formation of the protective film layer, the three layers described above are formed as follows. The transparent organic layer, which is the first layer of the protective film, is a type of primer that increases the adhesion between the colored layer and the second layer of the protective film, and also ensures the chemical resistance of the colored layer. It also plays the role of alleviating applied strain due to volume shrinkage that occurs when forming the second layer and preventing cracks from forming in the second layer of the protective film. The material should preferably be one that has low absorption of visible light in the range of 400 to 700 mm and is highly heat resistant.For example, acrylic resin, polyether salion resin, polyvinyl alcohol resin, nylon resin, polyester resin, phenoxy resin. , epoxy resin, etc., and may be either a thermosetting type or a photocuring type. The film thickness is preferably about 0.1 to 2 μm. The second layer of the protective film, an organic metal oxide layer created by dehydration and condensation of an organic metal compound, covers the softness of the colored layer and levels the unevenness of the colored layer, so that the transparent electrode to be formed later can be aligned. The main purpose is to prevent wire breakage during rubbing, and also to ensure the chemical resistance of the colored layer. The organometallic compound has a structural formula of M (OR)nR'm-n, and is hardened and formed by hydrolysis, dehydration, and condensation reaction. Metals M include silicon, titanium, tantalum, chromium,
Examples include tungsten, molybdenum, and zirconium. Generally, R has a methyl group or an ethyl group, and the hydrogen-containing organic chain R' has various structures including a methyl group and an ethyl group, but is not particularly limited. It is sufficient if film formation is possible with respect to curing. The organometallic compound may be used alone, or may be used in combination with silica sol or the like to increase hardness. Application methods include spin cording, dipping, spraying, roller coating, screen printing, flexographic printing, and curtain coating. After coating, it is baked to undergo dehydration and condensation and harden to form a hard film. The firing temperature is preferably 15° C. or higher, and the upper limit may be within a range that does not discolor the colored layer. The film thickness is most preferably about 0.5 to 10 μm. Next, the third layer of the protective film is an oxide film formed by sputtering, and the material is preferably silicon oxide, titanium oxide, Kunkle oxide, chromium oxide, tungsten oxide, molybdenum oxide, zirconium oxide, etc. Along with the first and second layers, this layer ensures the chemical resistance of the colored layer, prevents the elution of impurity ions into the liquid crystal, and also increases buttering properties when forming transparent electrodes on top of this layer. . That is, the second layer of the protective film is usually 150 to 1
This is because the transparent electrode is baked at a relatively low temperature of 250° C., resulting in insufficient tightness, and therefore, if a transparent electrode is buttered directly thereon, side etching is likely to occur and good buttering cannot be achieved. The film thickness may be 500 to 2000 people. Through the above steps, a protective film is formed. Next, in forming a transparent electrode, a uniform film is formed by sputtering or vapor deposition, and then patterned into a predetermined pattern (usually in the form of stripes) by photolithography. At this time, the pattern is usually formed by etching using hydrochloric acid or the like. Transparent electrode materials include indium oxide, tin oxide,
Indium tin oxide (ITO) or the like is used. Finally, an alignment film is formed. The alignment film may be a commonly used polyimide film. The color filter of the present invention is completed through the above steps. Furthermore, before forming into a liquid crystal panel, the alignment film is subjected to a rubbing treatment, combined with a counter substrate (forming an MIM element) to form a cell, and liquid crystal is sealed to form a color liquid crystal display panel. [Example 1] A photocurable acrylic resin was formed on a glass substrate to a thickness of 2 um using a spin cord, and after forming into a predetermined pattern using a photolithography process, it was dyed red (R) using an acid dye. On top of this, a photocurable acrylic resin was again formed to a thickness of 3 μm using a spin cord, and a predetermined pattern was formed on the area other than the dyed layer using a photolithography process, followed by dyeing green (G) using an acidic dye. Furthermore, a photocurable resin was formed on this to a thickness of 1.5 μm using a spin cord, and after forming a predetermined pattern on the portion other than the dyed layer, this time it was dyed blue (B). Through the above steps, dyed layers of 83 colors of R and G were obtained on the glass substrate. Next, a thermosetting acrylic resin (manufactured by Japan Synthetic Rubber Co., Ltd., JSS-16) was applied as a first layer of a protective film on the dyed layer.
It was formed with a thickness of μm. The coating was done using a spin cord, and the firing conditions were 180°C and 30°C.
It was a minute. A second protective layer was then applied. As the organometallic compound, α-glydoxypropyltrimethoxysilane is the main component, and silica sol (manufactured by Catalysts & Chemicals Co., Ltd., 05CAL-1432) is used in a molar ratio of 1:3 (3 parts silica sol) to increase the hardness of the coating. It was added and used in the following proportions. 0.05μ to hydrolyze α-glydoxytrimethoxysilane
A small amount of hydrochloric acid was also added. Coating was carried out using a spin cord, and baking was carried out at 170° C. for 30 minutes to dehydrate and condense and harden. The film thickness was 2.5 μm. Further, as a third layer of a protective film, silicon oxide was formed to a thickness of 1000 nm by sputtering. Subsequently, IT]I was formed on the above protective film by sputtering and patterned into a predetermined pattern to form a transparent electrode. Furthermore, on top of this, a polyimide film of 80% is applied as an alignment film for the liquid crystal.
A desired color filter was obtained by forming a film with a thickness of 0. Furthermore, a rubbing process is performed, and the counter substrate on which the color filter and MIM elements are formed is placed in a cell gap 5.5a.
The panels were laminated together using m, and a liquid crystal was sealed to form a panel. Finally, the LCD panel was completed by pasting polarizing plates on the top and bottom of the panel. [Example 2] In the same manner as in Example 1, dyed layers in three colors of R, G and 8° were obtained on a glass substrate. Next, a photocurable acrylic resin (manufactured by Japan Synthetic Rubber Co., Ltd., JMC-25T) was applied as a first layer of a protective film on the dyed layer.
It was formed with a thickness of 2 μm. Application is done with Subi-coat,
Cured with UV light. Next, as the second layer of the protective film, an organic silicate compound, GCM-701 manufactured by Japan Synthetic Rubber Co., Ltd., was applied by roll coating method, and baked at 180°C for 60 minutes to form a 2 μm layer.
It was formed with a film thickness of . Subsequently, as a third layer of a protective film, an oxide tank was formed with a thickness of 1500 mm by spackling. Thereafter, a desired color filter was obtained in the same manner as in Example 1, and a panel was further formed in the same manner. [Example 3] Using ink containing organic pigment as the main component, R,
Colored layers of G and B were formed. Next, a polyether sulfone resin (Lithodite TN20OS-1, manufactured by Mitsui Toatsu Chemical Co., Ltd.) was formed with a thickness of 1 μm as a first layer of a protective film using a spin cord. Hardening was performed by baking at 180°C for 30 minutes. Next, as a second layer of the protective film, titanium-based Titacoat R-291 manufactured by Nippon Soda Co., Ltd. was applied using a flexible printing method.
It was baked at 0°C for 60 minutes. The film thickness was 2 μm. Subsequently, silicon oxide was formed as a third layer of a protective film by sputtering to a thickness of 2000 nm. Hereinafter, as in Example 1, a desired color filter is used,
It was also made into a panel.

[Comparative Example 1] A transparent conductive film was provided on a glass substrate, and then dyed layers of R1G and B were formed. A conventional color filter as shown in FIG. 1 was prepared, and a panel was formed by combining it with a substrate on which MIM elements were formed. [Comparative Example 2] In Example 1, an attempt was made to produce a filter without the first protective film layer, but cracks occurred when forming the second protective film layer (gold film compound layer), and the desired color filter could not be obtained. was not obtained. Comparative Example 31 In Example 1, an attempt was made to produce a filter without the second protective film layer, but many transparent electrodes were broken during rubbing during alignment treatment, and the desired color filter could not be obtained. [Comparative Example 4] In Example 1, an attempt was made to produce one without the third protective film layer, but over-etching occurred during transparent electrode patterning, resulting in a line pattern that became too thin, making it difficult to obtain the desired color filter. It didn't work out. The performance of the above-mentioned examples was evaluated. The evaluation was based on the relationship between the applied voltage to the liquid crystal panel and the light transmittance. FIG. 3 is a comparison of characteristics between the case of Example 1 and the conventional product of Comparative Example 1. As can be seen in the characteristic curve 31 in the figure, the rising curve of the characteristic curve of Example 1 is steep; This shows that the driving performance of the liquid crystal with respect to the applied voltage is improved, and suggests that the color filter of the present invention has higher image quality. Similar results were obtained in Example 2.3. Furthermore, as a reliability test based on comparison with conventional products, we conducted a humidity resistance test in which the panel was placed in an environment of 90% at 60°C for 300 hours with voltage applied to it, and
A heat shock test was conducted in which the temperature was alternately placed in a 60°C environment for 20 days.
Although 0 cycles were performed, no problems were observed compared to conventional products, and the results were rather good. [Effects of the Invention] As described above, the color filter of the present invention significantly improves the image quality of MIM color liquid crystal display elements compared to conventional products, and on the other hand, the film structure of the color filter of the present invention is It is also stable and can be produced at high yields. Furthermore, it has been found that the color filter of the present invention has a secondary effect in that the protective film is effective in preventing impurity ions from seeping out from the colored layer to the liquid crystal layer.

[Brief explanation of the drawing]

Figure 1: Cross-sectional view of a conventional color filter. FIG. 2 is a sectional view of the color filter of the present invention. Figure 3: Liquid crystal panel characteristic curve diagram. 11...Transparent substrate 12...Transparent electrode 13...Colored layer 14...Transparent organic layer 15...Alignment film 21...Transparent substrate 22...Colored layer 23...Protective film No. Single layer (transparent organic layer) 24... Second protective film layer (organometallic compound layer 25... Third protective film layer (oxide layer formed by sputtering) 26... Transparent electrode 27... Alignment film 31 ...Characteristic curve 32 of the liquid crystal panel produced in Example 1...Characteristic curve of the liquid crystal panel produced in Comparative Example 1 and above Applicant: Seiko Epson Corporation

Claims (1)

[Claims] After forming colored layers of multiple colors on a transparent substrate, a transparent organic layer is formed on the colored layer as a first layer of a protective film for the colored layer, and then an organometallic compound layer is formed as a second layer of a protective film. (The structural formula is M(OR)nR'm-n, M represents a metal, R,
R' is an organic chain containing hydrogen, n and m are integers, and m is the valence of the metal M. ) as the main component, a protective layer is formed by dehydration and condensation reaction of the component, and an oxide layer is formed by sputtering as a third protective film layer on the second protective film layer, and further these protective layers 1. A color filter comprising: a transparent electrode having a predetermined pattern thereon; and an alignment film formed on the transparent electrode.