Radiation imagery chemistry: process – composition – or product th – Radiation modifying product or process of making – Screen other than for cathode-ray tube
Patent
1998-04-01
1999-07-20
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
4302701, G02B 520, G02F 11335, G03F 700
Patent
active
059254840
DESCRIPTION:
BRIEF SUMMARY
SPECIFICATION
1. Technical Field
The present invention relates to a black photoresist composition, a color filter using the composition, and a method for preparing the color filter, and more particularly, to a material for preparing a color filter used in, for example, a liquid crystal display, and especially to a black photoresist composition used in forming a black matrix and a process for forming a black matrix.
2. Background Art
Color filters have come to be widely used in the prior art in the field of liquid crystal display apparatuses. These color filters normally consist of multi-colored picture elements, such as red, green and blue, arranged on a transparent substrate. Moreover, in order to obtain images having good contrast, a black matrix is formed between these picture elements. Moreover, this black matrix is also used for the purpose of preventing erroneous operation of the transistors used in TFT-driven liquid crystal displays.
There are many cases in which the above-mentioned black matrix is normally formed with a metal thin film composed of a fine pattern on a glass transparent substrate. A specific example of a method that is commonly employed comprises forming a thin film of a metal or metal compound such as chrome, nickel or aluminum and so forth using a vacuum deposition technique such as vapor deposition or sputtering, followed by forming a fine pattern by photolithography.
More specifically, a resist pattern is formed by coating a photoresist on a thin film of metal and so forth, drying the photoresist and irradiating with ultraviolet rays through a photomask to develop. Following this, a black matrix is formed after going through an etching step and resist removing step. However, the black matrix prepared in the above-mentioned process has an extremely high production cost due to the complexity of the process, while also having the disadvantage of the cost of the color filter in which it is used also being high.
In the case of installing a color filter using this metal thin film on a transmission-type liquid crystal display, the surface of the metal typically used for the metal thin film has high reflectance and the color filter is illuminated with intense external light, such as in the case of a chrome thin film, the reflected light becomes intense thus resulting in the problem of a remarkable decrease in display quality.
On the other hand, various methods have been examined for resolving the problems associated with a black matrix using metal thin film as described above. For example, a method for forming a black matrix has been proposed in which carbon black, and, as necessary, organic pigment are dispersed in a photoresist composition followed by using this to form the black matrix. However, a film thickness of approximately 1 .mu.m is required to obtain shield with carbon black. Consequently, the portions at which the black matrix overlaps with the multi-colored picture elements, which serve as the positioning margins, become protuberances that cause unevenness in the display.
Japanese Unexamined Patent Publication No. 6-59119 proposes a method and material for selectively providing a black matrix only between the gaps in the multi-colored picture elements by providing a black photoresist layer on and between the multi-colored picture elements, and then exposing the entire surface through a transparent substrate using the multi-colored picture elements as a mask.
The above-mentioned protuberances are not formed when this type of so-called back exposure method is used. However, in order to obtain adequate thickness of the black matrix while also not leaving any black layer on the multi-colored picture elements, the shield of the black photoresist composition of the multi-colored picture elements must be sufficiently high at the wavelength of the light used for exposure. In order to achieve this, an ultraviolet absorber such as titanium oxide, zinc oxide, benzotriazole compound or coumarin compound and so forth had to be added to the multi-colored picture elements serving as the m
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patent: 5055379 (1991-10-01), Bagchi et al.
patent: 5639579 (1997-06-01), Hayashi et al.
patent: 5782968 (1998-07-01), Hirayama et al.
patent: 5786042 (1998-07-01), Inoue et al.
Ando Nobuyuki
Ikeda Hayato
Shima Yasuhiro
Taguchi Takao
Tamura Akira
McPherson John A.
Nippon Shokubai Co. , Ltd.
Toppan Printing Co. Ltd.
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