Optical: systems and elements – Having significant infrared or ultraviolet property – Having ultraviolet absorbing or shielding property
Reexamination Certificate
2000-05-31
2001-10-23
Chang, Audrey (Department: 2872)
Optical: systems and elements
Having significant infrared or ultraviolet property
Having ultraviolet absorbing or shielding property
C359S350000, C359S885000, C252S588000, C252S589000, C313S489000, C430S512000, C430S517000, C526S261000
Reexamination Certificate
active
06307671
ABSTRACT:
This application claims priority under 35 U.S.C. §§119 and/or 365 to 11-152823 and 11-252731 filed in Japan on May 31, 1999 and Sep. 7, 1999, respectively; the entire contents of which are hereby incorporated by reference.
FIELD OF THE INVENTION
The present invention relates to an optical filter comprising a transparent support and a filter layer. In more detail, the invention relates to an optical filter covering a display surface of a display device such as a liquid crystal display device (LCD), a plasma display panel (PDP), an electroluminescence display (ELD), a cathode-ray tube (CRT), a fluorescent indicator tube or a field emission display to improve the color reproducibility of the display.
BACKGROUND OF THE INVENTION
A display device such as a liquid crystal display device (LCD), a plasma display panel (PDP), an electroluminescence display (ELD), a cathode-ray tube (CRT), a fluorescent indicator tube or a field emission display displays a color image with a combination of the three primary colors (i.e., red, blue, green). However, it is very difficult (substantially impossible) to use the ideal three primary colors. For example, the plasma display panel uses phosphors of the three primary colors, which emit light containing an unnecessary component (in the wavelength region of 560 to 620 nm). Therefore, it has been proposed to correct the color balance of the displayed image by an optical filter absorbing the unnecessary component. The optical filter for the color correction is described in Japanese Patent Provisional Publication Nos. 58(1983)-53904, 60(1985)-118748, 60(1985)-18749, 61(1986)-188501, 3(1991)-231988, 5(1993)-203804, 5(1993)-205643, 7(1995)-307133, 9(1997)-145918, 9(1997)-306366 and 10(1998)-26704.
The display device needs prevention of reflection as well as the color collection. On the screen of the display device, the surrounding scene is often reflected to impair the contrast of the displayed image. Various anti-reflection films have been proposed to solve the problem of reflection. The known anti-reflection layers are categorized into two types, namely evaporating (and depositing) layers and coating layers. The evaporating layers are superior to the coating layers in view of optical characteristics, but the coating layers are easily formed compared with the evaporating layers.
The evaporating layers have been used as anti-reflection films for lenses of glasses or cameras. The layers are generally formed by a vacuum deposition process, a spattering method, an ion plating method, a CVD method or a PVD method.
The coating layers can be formed by coating a dispersion of fine particles and a binder. The coating layers are described in Japanese Patent Provisional Publication Nos. 59(1984)-49501, 59(1984)-50401, 60(1985)-59250 and 7(1995)-48527.
The anti-reflection layers can be introduced into the optical filters. The optical filters having the anti-reflection layers are disclosed in Japanese Patent Provisional Publication Nos. 61(1986)-188501, 5(1993)-205643, 9(1996)-145918, 9(1996)-306366 and 10(1997)-26704. The optical filter described in 61(1986)-188501, 5(1993)-205643, 9(1996)-145918 or 9(1996)-306366 has a transparent support containing a dye or a pigment so that the support functions as an optical filter. Further, the optical filter described in 10(1997)-26704 comprises a colored hard coating (surface hardening) layer provided between a support and an anti-reflection layer, so that the hard coating layer functions as an optical filter.
SUMMARY OF THE INVENTION
A colored transparent support or a colored hard coating layer can function as an optical filter. However, it is difficult to incorporate a dye or pigment into the support or the hard coating layer.
The transparent support is made of glass or plastics (usually, plastics). Therefore, the dye or pigment contained in the support must have enough heat resistance to a high temperature in the production process of the support.
The hard coating layer generally comprises a cross-linked polymer. In forming the layer, the polymer is cross-linked after coating a polymer solution. The dye or pigment added in the solution often fades at the crosslinking reaction.
Many methine dyes have been researched in the field of silver halide photography. The methine dyes have various absorption spectra. The methine dye in an aggregated form has a sharp absorption peak (a narrow half width). The methine dyes have been developed to be contained in a photographic material (usually in a gelatin layer). If the methine dyes are incorporated into the support or the hard coating layer, the dyes usually have problems of fading.
The applicants have tried to add the methine dyes not to the support or the hard coating layer (which restricts the dyes or pigments), but in a polymer layer. The polymer layer can be formed under moderate conditions. Many photographic methine dyes can be contained in the polymer layer, which functions as an optical filter. However, the polymer layer does not protect the dyes, compared with the support and the hard coating layer. Therefore, the methine dyes in an aggregated form to be contained in the polymer layer are preferably improved in durability (particularly, light resistance). The methine dyes should be improved without disturbing the function (color correction) of the dye. The dyes should also be improved without absorbing light for an image emitted from the phosphors. Further, the dye should be improved without coloring the image display device when the image is not displayed.
An object of the present invention is to provide an optical filter having a function of correcting color appropriately.
Another object of the invention is to provide an optical filter which can advantageously be used with a plasma display panel.
The present invention provides an optical filter which comprises a transparent support and a filter layer containing a dye and a binder polymer, wherein the dye is a methine dye in an aggregated form, and wherein the transparent support, the filter layer or an optional layer further contains an ultraviolet absorbing agent represented by the formula (I), (II), (III), (IV), (V), (VI), (VII) or (VIII):
in which the benzene rings a and b may have a substituent group;
in which Ar
1
is an aryl group or an aromatic heterocyclic group; —L— is a single bond or —O—; and the benzene ring c may have a substituent group;
in which the benzene ring d and the triazine ring e may have a substituent group; and the benzene ring d may be condensed with another aromatic ring or a heterocyclic ring;
in which the benzene rings f and g may have a substituent group;
in which Ar
2
is an aryl group or an aromatic heterocyclic group; R
1
is hydrogen or an alkyl group; and each of R
2
and R
3
independently is cyano, —COR
13
, —COOR
14
, —CONR
15
R
16
, —SO
2
R
17
or —SO
2
NR
18
R
19
, wherein each of R
13
, R
14
, R
15
, R
16
, R
17
, R
18
and R
19
independently is hydrogen, an alkyl group, a substituted alkyl group or an aryl group, or R
2
and R
3
are combined to form a five-membered or six-membered ring;
in which each of R
4
and R
5
independently is hydrogen, an alkyl group or an aryl group, or R
4
and R
5
are combined to form a five-membered or six-membered ring; and each of R
6
and R
7
independently is cyano, —COR
20
, —COOR
21
, —CONR
22
R
23
, —SO
2
R
24
or —SO
2
NR
25
R
26
, wherein each of R
20
, R
21
, R
22
, R
23
, R
24
, R
25
and R
26
independently is hydrogen, an alkyl group, a substituted alkyl group or an aryl group, or R
6
and R
7
are combined to form a five-membered or six-membered ring;
in which R
8
is an alkyl group, a substituted alkyl group or an aryl group; each of R
9
and R
10
independently is cyano, —COR
27
, —COOR
28
, —CONR
29
R
30
, —SO
2
R
31
or —SO
2
NR
32
R
33
, wherein each of R
27
, R
28
, R
29
, R
30
, R
31
, R
32
and R
33
independently is hydrogen, an alkyl group, a substituted alkyl group or an aryl group, or R
9
and R
10
are combined to form a five-membered or six-membered ring; —X~Y— is —CR
34
R
35
—CR
36
R
37
— or —CR
38
═CR
39
—,
Burns Doane , Swecker, Mathis LLP
Chang Audrey
Fuji Photo Film Co. , Ltd.
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