JPH04310902A - Manufacture of color filter - Google Patents

Abstract

PURPOSE:To manufacture the color filter superior in display quality at low cost without any limitation of the formation area. CONSTITUTION:A shielding plate 4 provided with a picture element pattern as an opening hole part is put on a transparent electrode 2 formed on a transparent substrate 1 and dipped in a solution which contains a monomer of colored conductive macromolecules and anion together with a counter electrode 6 and a voltage is applied between the transparent electrode 2 and counter electrode 6 to polymerizing the macromolecules electrolytically at a position on the transparent electrode corresponding to the opening hole part of the shielding plate 4, thereby forming a colored layer of the colored conductive macromolecules on the transparent electrode 2 in the shape of the specific picture element pattern.

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] [Object of the Invention] [Industrial Field of Application] The present invention relates to a method of manufacturing a color filter used in liquid crystal display devices and the like. [0003] Demand for liquid crystal display devices has increased significantly in recent years, and fluorescent discharge tubes forming the pixels of large display devices used outdoors are used to enable color display of these devices. Color filters are used. FIG. 3 shows a color liquid crystal display device (three terminal type T
An example of a color filter used in the FT active matrix method is shown below. In the same figure, this color filter 31 includes a black matrix 33 provided in a portion separating individual pixels on one surface of a transparent substrate 32, and a colored layer 34 formed in the pixel portion formed by this black matrix 33. It has a structure in which a transparent protective film 35, a transparent electrode 36, and an alignment film 37 are laminated in this order on these. In the color liquid crystal display device, the color filter 31 is disposed facing an array substrate 40 in which display electrodes 39 are formed on a transparent substrate 38 at positions corresponding to individual pixels, and a liquid crystal composition 41 is placed between them. It has a structure in which polarizing plates 42 and 43 are integrally laminated on both sides of the polarizing plates 42 and 43. In the figure, 44 is a sealing material. [0005] Conventionally, the color filter 31
A glass substrate or the like is used as the transparent substrate 32, and the black matrix 33 is formed by pattern etching a Cr thin film formed by sputtering, or by exposing a thin film formed by coating a black dye containing a photosensitizer. The pattern is formed using a method such as a method of creating a pattern using a method. Also,
In the colored layer 34, three types of pigments corresponding to the three primary colors of R (red), G (green), and B (blue) are arranged in each pixel area, one type each, and as a method of arranging each pigment in the pixel area. Methods such as dyeing, dye dispersion, pigment dispersion, printing, and electrodeposition are used. Furthermore, acrylic resin, epoxy resin, etc. are used for the transparent protective film 35, and the transparent electrode 36
I. T. O. (Indium Tin Oxide)
A polyimide thin film is generally used as the alignment film 37. [0006] However, there are still many points that need to be improved in the technology related to conventional color filters, and among them, the process of arranging the pigments has a large impact on the characteristics and manufacturing cost of the resulting color filter. As mentioned above, various methods are known, but each has its advantages and disadvantages. That is, the dyeing method results in a colored layer that is poor in water resistance, chemical resistance, especially alkali resistance, and heat resistance. For this reason, for example, in order to reduce the resistivity when forming a transparent electrode, I. T. O. After forming a thin film such as, heat treatment is performed, but the treatment temperature cannot be raised high, making it impossible to obtain a transparent electrode with sufficiently low resistivity, resulting in a decrease in display quality. In the dye dispersion method, water resistance and chemical resistance are improved compared to the dyeing method, but heat resistance is not improved because it depends on the inherent properties of the dye, and in addition, the number of steps is large, and expensive dispersion is required. The disadvantage is that the manufacturing cost is high because of the use of chemicals. Although the pigment dispersion method has sufficient heat resistance and does not have the above-mentioned problems, it uses expensive organic pigments, and
Since this pigment goes through a process of once applying it to areas other than pixel areas, a large amount of pigment is required and the manufacturing cost is extremely high. [0010] In the printing method, as the size of the color filter increases, the accuracy for accurately placing the dye in the pixel area becomes poor, so there is a limit to the printing size, and the surface smoothness of the printed pixels is inferior. There are some difficulties. [0011] In principle, in the electrodeposition method, a transparent electrode is provided on a transparent substrate, and a colored layer is formed by disposing a dye on this electrode, so the heat resistance requirements are higher than those of the above-mentioned methods. On the other hand, when driving a liquid crystal display device, a colored layer must be sandwiched between a transparent electrode and an opposing electrode, and a voltage applied to it. Since the colored layer has extremely low conductivity, the voltage applied to the liquid crystal layer becomes low, resulting in a disadvantage that the display quality deteriorates. In order to solve this difficulty, we
As shown in Japanese Patent No. 984, a method has been proposed in which a polymer film is formed on a transparent electrode by electrolytic polymerization, and then immersed in a solution containing a dye and a voltage is applied to dye the polymer film. However, this method requires two steps: polymer membrane formation and polymer membrane dyeing, resulting in high costs. [0012] As described above, each of the conventional colored layer forming methods for color filters has its drawbacks, and therefore, the color filters obtained by such methods also have poor characteristics and The reality is that nothing satisfactory has yet been achieved in terms of manufacturing costs. [0013] By the way, if we summarize and examine the above-mentioned methods for forming colored layers, in the dyeing method, dye dispersion method, pigment dispersion method, and printing method, transparent electrodes are formed after forming a colored layer on a transparent substrate. There is. On the other hand, in the electrodeposition method, a colored layer is formed after forming a transparent electrode on a transparent substrate. The transparent electrode can be formed by any method such as I.D. using a sputtering method or the like. T. O. After forming a thin film such as, heat treatment is performed to lower the resistivity. therefore,
The former dyeing method requires heat resistance that can withstand the heat treatment temperature to obtain a transparent electrode with sufficiently low resistivity, but methods that use dyes do not allow the heat treatment temperature to be raised;
Display quality deteriorates because a transparent electrode with sufficiently low resistivity cannot be obtained. When a pigment is used, the heat resistance is sufficient, but as mentioned above, the manufacturing cost increases. In the printing method, there is a limit to the print size and the surface smoothness is poor. On the other hand, in the latter electrodeposition method, a colored layer is formed after forming the transparent electrode, so there is no problem in obtaining a transparent electrode with sufficiently low resistivity, but there is a colored layer that is an insulator on the transparent electrode. Therefore, the effective voltage applied to the liquid crystal layer decreases, and the display quality deteriorates. Further, in the polymer membrane dyeing method which is an improvement on this electrodeposition method, the problem of manufacturing cost remains. [0014] To summarize the above, it is desirable that the formation of the transparent electrode be performed before the formation of the colored layer, and
It is desirable that the colored layer formed on the transparent electrode does not reduce the effective voltage applied to the liquid crystal layer. Moreover,
It is desirable not to limit the formation area or increase manufacturing costs. [0015] The present invention was made based on such knowledge, and the transparent electrode is formed before the colored layer is formed.
In addition, the above-mentioned problems of the prior art can be solved by making the colored layer formed on the transparent electrode so as not to reduce the effective voltage applied to the liquid crystal layer without restricting the formation area or increasing the manufacturing cost. It is an object of the present invention to provide a method for solving the problems and manufacturing a color filter with high display quality at low cost even if it has a large area. [Structure of the Invention] [Means for Solving the Problems] A method for manufacturing a color filter according to the present invention includes forming colored conductive conductors in the shape of a predetermined pixel pattern on a transparent electrode formed on a transparent substrate. To form a colored layer made of a conductive polymer, a shielding plate having the pixel pattern as an aperture is placed on the transparent electrode, and a solution containing monomers and anions of the colored conductive polymer is placed on top of the transparent electrode. After being immersed together with a counter electrode in the liquid, a voltage is applied between these transparent electrodes and the counter electrode, and the colored conductive polymer is placed on the transparent electrode at a position corresponding to the opening of the shielding plate. It is characterized by electrolytic polymerization. The colored conductive polymer monomer used in the present invention includes thiophene and its derivatives such as polythiophene, poly3-methylthiophene, and poly2-benzothiophene, polyfuran, and polybenzofuran. 5-membered heterocyclic compounds such as furan and its derivatives, aniline and its derivatives such as polyaniline, aromatic amino compounds such as diphenylamine such as polydiphenylamine, aromatic carbonization such as polypyrene, polyazulene, polyfluorene, etc. Examples include hydrogen compounds, vinyl compounds constituting polyvinylcarbazole, aromatic halogen compounds constituting polybrompyridine, polytetrabromoxylene, etc., and other monomers with double or triple bonds in their molecules. If it is a polymer with a structure that has heavy bonds and has a color,
It is not particularly limited to the above. Further, as the anion used in the present invention, it is preferable to select one type from those represented by chemical formulas such as ClO4 -, BF4 -, PF4 -, etc., but the anion is not particularly limited to these. It is not something that will be done. Furthermore, propylene carbonate, acetonitrile, water, etc. are used as a solvent for dissolving the colored conductive polymer monomer and anion.
It is not particularly limited to these. [0021] The absorption spectrum of the above-mentioned colored conductive polymer changes reversibly as it undergoes redox. Therefore, a conductive polymer having a desired color in either redox state is selected from among various conductive polymers, and the monomers constituting it are electrolytically polymerized. A layer colored in a desired color may be formed by bringing the conductive polymer into an oxidized or reduced state. [0022] Table 1 shows the colors that various colored conductive polymers have in the redox state, taking as an example a polymer containing a thiophene derivative and an aniline derivative as monomers.
[Table 1]
monomer
polymer color

oxidant
Reduced thiophene
Blue Red 3-methylthiophene
deep blue red
2-benzothiophene colorless
blue aniline green
[Operation] In the method of the present invention, a shielding plate having predetermined openings is superimposed on a transparent electrode formed on a transparent substrate, and a colored conductive polymer monomer and an anion are layered on top of the transparent electrode. The colored conductive polymer is electrolytically polymerized at the position corresponding to the opening on the transparent electrode by immersing it together with a counter electrode in a solution containing the transparent electrode and applying a voltage between the transparent electrode and the counter electrode. Since a colored layer made of a colored conductive polymer is provided on a transparent electrode in the shape of a predetermined pixel pattern, a color filter with excellent display quality can be obtained with a small number of steps. Furthermore, the formation area is not limited. That is,
Even if the area is large, a color filter with high display quality can be manufactured at low cost. [Embodiment] Next, an embodiment of the present invention will be explained with reference to the drawings. FIG. 1 is a diagram showing a color filter in the process of being manufactured according to this example and an apparatus used in the process, and FIG. 2 is a sectional view showing the structure of the color filter obtained according to this example. . In this embodiment, first, as shown in FIG. 2, a glass substrate is used as the transparent substrate 1, and an I.D. T. O. A film with a thickness of 0.1 μm is formed by a sputtering method, and a transparent electrode 2 with low resistivity is formed by heat treatment. Next, a Cr thin film with a thickness of 0.1 μm is formed on the transparent electrode 2 by sputtering, and a positive resist (PMER P-
400 (manufactured by Tokyo Ohka Co., Ltd.) was applied to a thickness of 1 μm using a spinner, and exposed, developed, etched, and resist removed in order to form a predetermined black pattern 3. Subsequently, as shown in FIG. 1, a shielding plate 4 having openings at required positions corresponding to a part of the non-forming part of the black pattern 3 was superimposed and fixed on top of this. Thereafter, the shield plate 4 is immersed in the electrolytic polymerization liquid tank 5 of the electrolytic polymerization apparatus so that the shielding plate 4 faces the platinum electrode and the lithium electrode that have been placed in advance therein as a counter electrode 6 and a reference electrode 7, respectively. The electropolymerization liquid tank 5 contains an electropolymerization liquid in which 0.1 mol/dm 3 of thiophene as a monomer for forming a conductive polymer and ClO4 − as an anion as Li salt are dissolved in propylene carbonate as a solvent. In this state, the transparent electrode potential between the transparent electrode 2 and the counter electrode 6 is +0.75VvsLi/Li.
A thin film of polythiophene with a thickness of 0.5 μm was formed on the transparent electrode 2 by applying a voltage so that
A transparent conductive polymer film of No. 1 is obtained. After that, the glass substrate 1 on which the conductive polymer film has been formed is taken out from the electrolytic polymerization liquid tank 1, and the shielding plate 5 is removed, thereby forming a predetermined area on the transparent electrode 3 where the black pattern 4 is not formed. A red colored layer 8a made of a thin film of a transparent conductive polymer colored red is formed at the position. Similarly, a green colored layer 8b and a blue colored layer 8c made of green and blue transparent conductive polymer films are placed at predetermined positions on the transparent electrode 2 in the area where the black pattern 3 is not formed. Form. In addition, in order to form a green transparent conductive polymer film, aniline was used as a monomer to form a conductive polymer in propylene carbonate as a solvent, and ClO4 − was used as an anion as a Li salt in an amount of 0.1 mol/each. After forming a thin film using a solution containing dm3, it is brought into an oxidized state and colored green. The conductivity of this thin film is 10 Scm-1. In addition, to form a blue transparent conductive polymer film, 2-benzothiophene as a monomer to form a conductive polymer and Cl as an anion are used as an electrolytic polymerization solution in propylene carbonate as a solvent.
O4 − as Li salt, 0.1 mol/d each
m3 Using the dissolved solution, after forming a thin film, bring it into a reduced state and color it blue. The conductivity of this thin film is 100 Scm-
It is 1. After forming the colored layer 8 made of conductive polymers in the three primary colors of red, green, and blue in this manner, a solution prepared by dissolving acrylic resin in an organic solvent is coated on top of the colored layer 8 using a spinner for transparent protection. A color filter is produced by forming a film 9 and then screen printing a polyimide resin thereon to form an alignment film 10. Using the color filter thus obtained, a three-terminal TFT active matrix color liquid crystal display device as shown in FIG. We evaluated the performance and compared it with the same type of color liquid crystal display device manufactured using conventional color filters (pigment dispersion method).
It was confirmed that it has the same or better characteristics. It should be noted that the present invention is not limited to the above embodiments; for example, an acrylic resin substrate can be used for the transparent substrate 1 in addition to a glass substrate. Moreover, the transparent electrode 2 is an I. T. O. In addition to forming a film using the sputtering method described above, a method of forming a film using a sputtering method, a vacuum evaporation method, or the like using tin oxide, indium oxide, or the like can be used. Furthermore, it goes without saying that the transparent protective film 9 and the alignment film 10 are not limited to the materials and methods described above. Effects of the Invention As explained above, according to the method for manufacturing a color filter of the present invention, a colored layer is formed by electrolytically polymerizing a colored conductive polymer on a transparent electrode on a transparent substrate. , it is possible to sufficiently heat-treat the transparent electrode,
A transparent electrode with low resistance can be formed. Furthermore, by directly forming colored conductive polymers in accordance with pattern shapes, large-area color filters with excellent display quality can be manufactured at low cost.

[Brief explanation of drawings]

FIG. 1 is a diagram illustrating a method for manufacturing a color filter according to the present invention.

FIG. 2 is a sectional view showing the structure of a color filter manufactured according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view showing an example of an active matrix liquid crystal display device using color filters.

[Explanation of symbols]

1... Transparent substrate 2... Transparent electrode 4... Shielding plate 5... Electrolytic polymerization liquid tank 6... Counter electrode 8... Colored layers 8a and 8b made of colored conductive polymer films.
, 8c... Red, green, and blue transparent conductive polymer films

Claims (1)

[Claims] 1. When forming a colored layer made of a colored conductive polymer in the shape of a predetermined pixel pattern on a transparent electrode formed on a transparent substrate, the pixel pattern is formed as an opening on the transparent electrode. After stacking the provided shielding plates and immersing them together with a counter electrode in a solution containing the colored conductive polymer monomer and anion, a voltage is applied between these transparent electrodes and the counter electrode. . A method for producing a color filter, comprising electrolytically polymerizing the colored conductive polymer at a position on the transparent electrode corresponding to the opening of the shielding plate.