Stock material or miscellaneous articles – Structurally defined web or sheet – Discontinuous or differential coating – impregnation or bond
Patent
1994-06-30
1996-09-24
Ryan, Patrick
Stock material or miscellaneous articles
Structurally defined web or sheet
Discontinuous or differential coating, impregnation or bond
428 1, 428207, 428323, 430 7, 359891, 359589, B32B 0900
Patent
active
055589278
DESCRIPTION:
BRIEF SUMMARY
FIELD OF TECHNOLOGY
This invention relates to colour filters employed in colour liquid crystal display apparatuses and to a film-forming apparatus suitable for the manufacture of such colour filters.
Background Art
A known method of colouring liquid crystal display devices is the employment of a display in which a colour filter layer (colour layer) is disposed within a cell which has a pair of transparent electrodes disposed in parallel. The known general compositions of colour filters are of the types illustrated in FIG. 4 and FIG. 5, for example.
The colour filter illustrated in FIG. 4 includes a colour layer 200 upon a supporting member 100 which is composed of a transparent ass substrate, a film or the like. The colour layer 200 consists of picture elements of three colours, red (R), green (G), and blue (B), 200a, 200b, and 200c, which form a specified pattern (such as mosaic type, triangular type, striped type, etc.) that corresponds to the area of the driven picture elements. A black matrix layer 300 is formed between the picture elements 200a, 200b, and 200c. Moreover, a protective layer 400 consisting of transparent resin or the like is formed upon the colour layer 200, while a transparent conductive layer 500 consisting of for example indium tin oxide(ITO) is formed upon the protective layer 400. Colour filters formed in such manner are commonly combined with substrates possessing thin film transistor(TFT) elements in order to form liquid crystal displays for colour displays.
FIG. 5 illustrates the structure of a colour filter that is employed in a liquid crystal display apparatus that employs the super-twisted nematic (STN) mode or alternatively the driver mode with metal-insulator-metal (MIM) elements. Such colour filter has a similar structure to the aforementioned colour filter, in a structure of a supporting member 100, a colour layer 200, a black matrix layer 300, and a protective layer 400. The transparent conductive layer (ITO layer) 500 possesses a pattern which corresponds to the picture elements 200a, 200b, and 200c which form the colour layer 200.
As the embodiments of colour filters described in the foregoing are formed of transparent conductive layers 500 upon colour layers 200, such embodiments are known as upper-ITO mode or alternatively ITO on Colour Filter (IOC) mode.
It is rather difficult to manufacture at low cost large-sized colour filters that employ such IOC mode, and more particularly the type of colour filter illustrated in FIG. 5, and which exceed 10 inches diagonally. This is because of problems with the formation of the patterns in the ITO layer which is formed upon the uppermost layer.
The ITO layer is normally etched with a composition consisting of a mixture of hydrochloric acid, nitric acid, and pure water at a composition temperature of approximately from 40.degree. C. to 60.degree. C., whereupon resist stripping is performed at a composition temperature of approximately from 40.degree. C. to 60.degree. C. by employing a stripping agent consisting of potassium hydroxide, an organic alkaline composition or the like in order to perform patterning. For this purpose, the protective layer 400 that is formed upon the colour layer 200 must have sufficient resistance to acidity and resistance to alkalinity. Moreover, the material of which the aforementioned protective layer 400 is formed must have a transmittance of at least 95% at all wavelengths and must be resistant to heat of at least 230.degree. C. The protective layer 400 is required to have high resistance to heat because the resistivity of the ITO layer 500 must be decreased as the display is made larger, such that a high temperature of at least approximately 230.degree. C. is required in order to form the film for the ITO layer. Thus the material that is employed in order to form the protective layer 400 is required to have excellent resistance to acidity, resistance to alkalinity, transparency, and resistance to heat, such that the selection of organic materials which meet such requirements is restricted.
Fu
REFERENCES:
patent: 5204739 (1993-04-01), Domenicali
patent: 5242558 (1993-09-01), Matsushima
patent: 5395678 (1995-03-01), Matsushima
Aruga Hisashi
Kobayashi Takashi
Sawata Ryuji
Takizawa Keiji
Jewik Patrick
Ryan Patrick
Seiko Epson Corporation
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