Optical: systems and elements – Glare or unwanted light reduction
Reexamination Certificate
1999-02-10
2002-02-05
Sikder, Mohammad (Department: 2872)
Optical: systems and elements
Glare or unwanted light reduction
C359S603000, C359S608000, C359S609000, C359S613000
Reexamination Certificate
active
06343865
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a non-glare film and a polarizing device to be preferably used on the surface of a high-resolution image display such as a cathode ray tube (CRT), a liquid crystal panel and the like to be used in an image display of a word processor, a computer, a television and the like, and a display device using the same non-glare film or polarizing device.
2. Related Art
In a display as described above, when a light emitted mainly from the inside comes straight on without diffusing on the display surface, a viewer of the display surface feels dazzling. In order to prevent this, the display surface is provided with a non-glare film for diffusing a light emitted from the inside to some degree. Such a non-glare film is formed by coating the surface of a transparent base film with a resin containing a filler such as silicon dioxide (silica) and the like, as disclosed, for example, in Japanese Patent Laid-Open Publication No. Hei 6-18706, Japanese Patent Laid-Open Publication No. Hei 10-20103 and the like.
These non-glare films include a type of forming a rugged shape on the surface of a non-glare layer by cohesion of particles of cohesive silica and the like, a type of forming a rugged shape on the surface of a layer by adding into a resin an organic filler having a particle diameter larger than the thickness of a coating film, and a type of transferring a rugged shape by laminating a rugged film onto the surface of a layer.
Any type of conventional non-glare films as described above obtains a light diffusing and glare preventing action by action of the surface shape of a non-glare layer and in order to enhance its glare preventing ability it is necessary to enlarge said rugged shape, but there is a problem that enlarging the ruggedness raises the haze value of a coating film and this causes deterioration in sharpness of an image.
As a film similar to the films described above, a light diffusion film obtaining a light dispersion effect by dispersing fine particles inside a layer has been disclosed in Technical Report MD-96-48 (1996), pp.277 to 282, of The Illuminating Engineering Institute of Japan, for example, as a film for a reflection-type liquid crystal display device.
In order to obtain a sufficient light diffusion effect from an internal scattering effect of a light diffusion film used here, the diameter of particles used needs to be made large, and doing so causes a problem that an area having a high haze value of the surface of a reflection-type liquid crystal display device is very poor in sharpness of an image.
And in case of using such a non-glare film obtaining a light diffusion effect by an internal scattering effect as said light diffusion film on the surface of a display, there is also a problem that it is not possible to prevent an external light from being reflected in the surface of the display due to a fact that the surface of it is almost flat.
Furthermore, a non-glare film of a conventional type as described above has a problem that the visibility of a display screen is degraded due to occurrence of glittering called face-glare (scintillation) on the surface of a, film.
A haze value is used as one of criteria for evaluating such a non-glare film, and there is a problem that lowering the haze value of a surface makes glare feeling called face-glare stronger and raising the haze value to solve this makes an image whitish as a whole and lowers it in black density and thereby degrades the image in contrast. On the other hand, when lowering the haze value to remove the whitishness, a problem happens that what is called reflecting-in and glare feeling result in increasing.
SUMMARY OF THE INVENTION
The present invention has been performed in consideration of the above-mentioned existing problems, and an object of the invention is to provide a non-glare film capable of suppressing degradation of contrast and preventing face-glare, reflecting-in and whitening when it is attached onto a display surface, and a polarizing device using the same film and a display device using the same non-glare film or polarizing device.
The present invention is based on the knowledge that in case of forming a non-glare film by laminating a non-glare layer composed of a light transmissive resin containing a light transmissive diffusing material having a refractive index different from the light transmissive resin, when the surface haze value to of the rugged surface of the non-glare layer meets “7<hs<30” and the internal haze value hi by internal diffusion of said non-glare layer meets “1<hi<15”, it is possible to make small the particle diameter of the light transmissive diffusing material and make better the display quality of, for example, a liquid crystal display and the like.
The present invention attains the above-mentioned object by a non-glare film which has a non-glare layer laminated onto at least one of the surfaces of a light transmissive base film, said non-glare layer comprising a light transmissive resin containing a light transmissive diffusing material being different in refractive index from the light transmissive resin, wherein the surface haze value hs on a rugged surface of this non-glare layer meets “7<hs<30” and the internal haze value hi by internal diffusion of said non-glare layer meets “1<hi<15”.
And said non-glare layer may have further a low refractive index layer laminated onto said non-glare layer, said low refractive index layer being lower in refractive index than said non-glare layer.
Moreover, said low refractive index layer may be formed out of a silicon-containing vinylidene fluoride copolymer.
And said silicon-containing vinylidene copolymer may be a polymer composed of a fluorine-containing copolymer which is a copolymer of vinylidene fluoride and hexafluoropropylene and whose fluorine content is 60 to 70 wt %, and a polymeric compound having an ethylene-unsaturated group.
And furthermore, said low refractive index layer may be formed by being coated with a coating film composed of at least said fluorine-containing copolymer and a polymeric compound having said ethylene unsaturated group and then being irradiated with an active energy beam or being heated.
And said low refractive index layer may be formed out of a silicon oxide film have a contamination preventing layer formed on it.
The sum of the surface haze value hs of the rugged surface of the non-glare layer in said non-glare film and the internal haze value hi caused by internal diffusion in said non-glare layer may be equal to or less than 30.
And the difference &Dgr;n in refractive index between the light transmissive resin and the light transmissive diffusing material in said non-glare layer may meet “0.01≦&Dgr;n≦0.5” and the average particle diameter d of the light transmissive diffusing material may meet “0.1 &mgr;m≦d≦5 &mgr;m”.
And the light transmissive resin in said non-glare layer may be at least one of a thermosetting resin and an ionizing-radiation hardening resin, and said light transmissive diffusing material may be a type of organic fine particles.
And said organic fine particles may be styrene beads.
The transparent base film in said non-glare film may be formed out of one of a triacetate cellulose film and a polyethylene terephthalate film.
And a transparent conductive layer may be put between the transparent base film and the non-glare layer, and a conductive material may be contained in the non-glare layer.
The present invention related to a polarizing device attains the above-mentioned object by a polarizing device comprising one of said non-glare films and a polarizing plate which is laminated onto the opposite surface of said transparent base film to said non-glare layer of this non-glare film so as to direct its observe surface face to the said opposite surface to said non-glare layer side.
And it is allowable to apply a saponification process to the opposite surface of said transparent base film to said non-glare layer and the surface of said non-glare layer an
Dai Nippon Printing Co. Ltd.
Oliff & Berridg,e PLC
Sikder Mohammad
LandOfFree
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