Radiation imagery chemistry: process – composition – or product th – Radiation modifying product or process of making – Screen other than for cathode-ray tube
Patent
1986-09-19
1989-06-06
Michl, Paul R.
Radiation imagery chemistry: process, composition, or product th
Radiation modifying product or process of making
Screen other than for cathode-ray tube
430293, 430294, 430321, 430323, 430330, 430329, 430394, 350311, 350333, 350331R, 350339F, 350339R, G03C 500, G03F 900
Patent
active
048370983
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a color filter adapted to be arranged on a light-receiving surface in a color LCD device, a color video camera or the like, and more particularly to a color filter employing polyimide having various excellent resistances such as thermal resistance, chemical resistance and light resistance. The invention also relates to a method of producing such a color filter.
PRIOR ART
A color filter of this type comprises a substrate such as a light-transmitting glass plate, and a color filter layer formed on one surface of the substrate. The color filter layer has not less than two groups of filter picture elements which are different in spectral characteristics from each other, and generally has three groups of filter picture elements corresponding respectively to red, green and blue. Each group has a number of filter picture elements having a fine pattern such as a mosaic pattern and a stripe pattern.
It is already known to use polyimide for forming the color filter. For example, Japanese Patent Application Laid-Open No. 58-46326 discloses a technique of coating each group of filter picture elements with polyimide. Japanese Patent Application Laid Open No. 59-29225 discloses a method of forming groups of filter picture elements to form a color filter layer in which after a polyimide layer is subjected to patterning, the groups of filter picture elements thus patterned are dyed in predetermined colors.
FIG. 1 shows a flow chart of a method of producing a color filter using the latter technique which color filter has three groups of filter picture elements corresponding respectively to red, green and blue and light-intercepting layers of a black color each disposed at a boundary between each adjacent filter picture elements. As shown in this Figure, with the conventional technique using dye requires, dying steps and patterning steps are carried out separately, and therefore this method has an increased number of steps and is complicated. In addition, since the polyimide layer subjected to patterning is at least in a semi-cured condition, it is difficult to disperse the coloring material uniformly and sufficiently into the polyimide layer. Thus, this method has such disadvantages.
To overcome the above disadvantages, the inventors of the present invention have proposed a method in Japanese Patent Application No. 59-201319 in which a coating layer for forming one of the groups of filter picture elements is formed using a coating solution containing a polyimide precursor solution and a coloring agent, the coating layer being then subjected to patterning by means of photolithography. FIG. 2 shows a flow chart of this method, and it will be appreciated that this method is considerably simplified in comparison with the method of FIG. 1.
According to the above method proposed by the present inventors, each group of filter picture elements can be formed relatively easily. However, each time each group of filter picture elements are to be formed, an intermediate protective layer must be formed to protect the precedingly-formed group of picture element. The same procedure is also required for the conventional process of FIG. 1.
The formation of such an intermediate protective layer not only makes the production of the color filter complicated but also makes the overall thickness of the color filter greater. In addition, this adversely affects a flatness of a surface of the color filter, which affects display characteristics and thinnes of a flat panel display such as a color LCD device.
In order to overcome the above problems, the present inventors have aimed at eliminating the intermediate protective layer and made extensive study and found the following.
When the second group of filter picture elements are formed without coating the first group of the filter picture elements with the protective layer, each filter picture element of the first group is damaged when the coating solution for forming the second group of filter picture elements is applied, but is hardly damaged at
REFERENCES:
patent: 4425416 (1984-01-01), Ogawa
Furukawa Tadahiro
Haga Toshio
Murakami Akiyoshi
Shimamura Masayoshi
Hamilton Cynthia
Kyodo Printing Co., Ltd.
Michl Paul R.
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