Radiation imagery chemistry: process – composition – or product th – Radiation modifying product or process of making – Screen other than for cathode-ray tube
Patent
1998-06-30
2000-05-16
McPherson, John A.
Radiation imagery chemistry: process, composition, or product th
Radiation modifying product or process of making
Screen other than for cathode-ray tube
427164, G02B 520, G02F 11335
Patent
active
060635274
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The invention relates to a color filter for use in a liquid crystal display panel or the like, and a method of making the same.
BACKGROUND ART
Methods of making a color filter for a liquid crystal display panel or the like include dyeing method, pigment dispersion method, printing method, and electrodeposition method.
In the dyeing method, a photosensitive material is added to the water-soluble polymer material which is the dye material, sensitizing it to light, and after this has been patterned by a lithographic process, it is steeped in a dye solution, to obtain the colored pattern.
For example, first an opaque portion (generally black and referred to as a "black matrix", hereinafter abbreviated to BM) is formed on a glass substrate. Then the dye material, which is made by adding photosensitive material to water-soluble polymer material so that when exposed to light the solubility in a solvent is reduced, is coated on the substrate on which the BM is formed. Next a part only of the dye material is exposed to light through a mask and then developed, thus carrying out patterning so that the dye material remains only in the areas of the first color. Next the dye material is steeped in dye solution to be dyed and then set to form the first color layer. This process is repeated three times, to form a three-color filter.
Whereas a color filter made by the dyeing method has a high transmissivity and bright colors, it is characterized by inferiority with respect to light-resistance, heat-resistance and hygroscopicity.
Next, in the pigment dispersion method, a photosensitive resin in which pigment has been dispersed is coated on a substrate, and this is patterned to obtain a single-color pattern; this process is then repeated. In the above dyeing method, the dyeing is carried out after patterning the dye material, whereas with the pigment dispersion method a photosensitive resin which has already been colored is coated on the substrate. A color filter made by the pigment dispersion method is characterized by high durability, but is somewhat reduced transmissivity.
Furthermore, of the layer of photosensitive resin, at least more than 70% of the amount applied must be removed and disposed of, producing a big problem in the efficiency of use of the material. in the printing method, paint made by dispersing pigment in thermosetting resin is applied by repeated printing to form three colors respectively, and the resin is heat-cured to form the color layer. While the printing method is simple, it is inferior in flatness.
In the electrodeposition method, a patterned transparent electrode is provided on a substrate, and then this is immersed in an electrodeposition fluid containing pigment, resin, electrolyte and so forth, for electrodeposition of the first color. This process is repeated three times, and then finally baking is applied. The electrodeposition method provides excellent flatness, and is effective for color arrangement in a striped pattern, but is difficult to form a color arrangement in a mosaic pattern.
Of the above methods of fabrication, the printing method has a drawback with respect to accuracy, and the electrodeposition method has a drawback of restrictions of patterning, and for this reason conventionally the dyeing method and pigment dispersion method have been most widely used.
However, the dyeing method and the pigment dispersion method require a lithography step for forming the pixel regions of each of the first color, second color and third color, and this is a big obstacle to improve the mass production efficiency of the color filter. One method for forming pixels without a lithography step for each color is an inkjet method of making a color filter, which is disclosed in a number of publications, for example, Japanese Patent Application Laid-Open No. 59-75205 and Japanese Patent Application Laid-Open No. 61-245106. By using an inkjet method to form the pixels, the efficiency of use of material improves, and the process is made shorter, and moreover a color filter of high br
REFERENCES:
patent: 4430666 (1984-02-01), Nakatsui et al.
patent: 5157527 (1992-10-01), De Keyzer et al.
patent: 5201268 (1993-04-01), Yamamoto et al.
English Language Translation of JP 6-167608, "Method for Manufacturing Color Filter", Sawazaki et al. (Jun. 1994).
Kiguchi Hiroshi
Kojima Masaru
Nishikawa Takao
Takakuwa Atsushi
McPherson John A.
Seiko Epson Corporation
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