Optical: systems and elements – Absorption filter
Reexamination Certificate
2001-09-27
2003-07-22
Juba, Jr., John (Department: 2872)
Optical: systems and elements
Absorption filter
C359S359000, C313S582000, C313S586000, C313S587000, C349S106000
Reexamination Certificate
active
06597525
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an optical filter fitted to an image display such as a plasma display panel (PDP), a liquid crystal display (LCD), an electroluminescence display (ELD), a cathode ray tube display (CRT), a fluorescent display tube or a field emission type display for preventing a reflection of external light, and an image display on a surface of which the optical filter is affixed.
BACKGROUND OF THE INVENTION
An image display such as a plasma display panel (PDP), a liquid crystal display (LCD), an electroluminescence display (ELD), a cathode ray tube display (CRT), a fluorescent display tube or a field emission type display has originally a flat screen, or progresses in flat panel formation. Although the distortion at screen edges is decreased by flat panel formation, the reflection of external light on a surface of the screen still presents a problem. The enlargement of the screen further magnifies the problem.
Further, these displays indicate color images by light combinations of three primary colors of red, blue and green. However, it is very difficult, substantially impossible to use ideal three primary colors as light for indication. For example, in the plasma display panel (PDP), it is known that light emitted from a three primary color luminescent material contains excess light (having a wavelength ranging from 500 nm to 620 nm).
Then, for correcting the color balance of display colors, it is proposed that color correction is carried out by using a filter absorbing light having a specific wavelength. The color correction using the filters are described in JP-A-58-153904 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”), JP-A-61-188501, JP-A-3-231988, JP-A-5-205643, JP-A-9-145918, JP-A-9-306366 and JP-A-10-26704.
Further, electromagnetic waves are emitted from display faces of electronic displays such as a PDP, an LCD, an ELD and a CRT, so that it is necessary to shield them. As a method therefor, a method of affixing metal meshes to front plates of CRTs is known to provide high electromagnetic shielding properties, and proposed in JP-A-62-150282, JP-A-4-48507, JP-A-10-75087, JP-A-11-119669 and JP-A-11-204046.
However, this method has the effect of preventing electromagnetic waves, but has the problem that geometric patterns formed by pixels of the displays interferes with geometric patterns formed by the meshes to cause a moire phenomenon.
Still further, the problem is reported that infrared rays (mainly having a wavelength of 750 nm to 1100 nm) emitted from displays causes the faulty operation of remote controllers. For solving this problem, infrared absorption filters are used. Dyes used in the infrared absorption filters are described in U.S. Pat. No. 5,945,209. However, they are not sufficient.
In addition, in PDPs, the glass thickness of display faces of main bodies is only about 3 mm, so that tempered glass plates called “front glass plates” are attached, apart from the main bodies, for preventing damage (JP-A-8-55581). This poses the problems of increasing the total weight and raising the cost.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide an optical filter preventing a reflection of external light, reducing the intensity of infrared rays emitted from an image display, being able to improve the color purity, and causing no moiré phenomenon, when it is applied to the image display.
Another object of the invention is to provide an optical filter making a front glass plate removable while maintaining the damage prevention of a screen of an image display and safety in damage, and being able to realize a decrease in weight of a main body of the image display and cost reduction.
A still another object of the invention is to provide an image display which is provided with the optical filter excellent in the above-mentioned characteristics, and from which a front glass plate is removed while maintaining the damage prevention of a screen of an image display and safety in damage.
As a result of intensive investigation by the present inventors, the objects of the invention have been attained by an optical filter and an image display having the following constitution:
1. An optical filter comprising: a laminate (A) comprising: a first transparent support; and at least one of an antireflection layer, an antiglare layer, a soil-resistant layer, a hard coat layer and an antistatic layer; a transparent support (B); and at least one of a visible light absorption layer and an infrared shield layer, the infrared shield layer absorbing near infrared rays having a wavelength of 750 nm to 1200 nm, wherein the at least one of a visible light absorption layer and an infrared shield layer is provided on the first transparent support at the opposite side to that the at least one of an antireflection layer, an antiglare layer, a soil-resistant layer, a hard coat layer and an antistatic layer are provided, or on the transparent support (B).
2. The optical filter described in 1 above, wherein the laminate (A) is disposed on a viewer side and the transparent support (B) is disposed on a front side of an image display, and the laminate (A) comprises the antireflection layer as an outermost layer.
3. The optical filter described in 2 above, which comprises: (a) at least one transparent support other than the transparent support (B) between the laminate (A) and a front face of the image display, wherein one transparent selected from the group consisting of the first transparent support, the transparent support (B), and the at least one transparent support other than the transparent support (B) has a thickness of 225 &mgr;m or more, and the total thickness of the first transparent support, the transparent support (B), and the at least one transparent support other than the transparent support (B) is within the range of 300 &mgr;m to 1000 &mgr;m, and (b) at least one adhesive layer, wherein the total thickness of the at least one adhesive layer is within the range of 30 &mgr;m to 150 &mgr;m.
4. The optical filter described in 1 above, which has an elastic modulus of 3.5 GPa or less.
5. The optical filter described in 1 above, wherein a conductive layer having a surface resistivity of 500 &OHgr;/square or less is provided on a transparent support other than the first transparent support.
6. The optical filter described in 5 above, wherein the conductive layer comprises one of a metal film and a laminate of a metal film and a metal oxide film.
7. The optical filter described in 1 above, wherein the infrared shield layer comprises a dye having an absorption in the infrared region.
8. The optical filter described in 1 above, wherein the infrared shield layer comprises a dye having a transmittance of 20% or less in each of the ranges of 750 nm to 850 nm, 851 nm to 950 nm and 951 nm to 1100 nm.
9. The optical filter described in 1 above, wherein the visible light absorption layer comprises a dye.
10. The optical filter described in 9 above, wherein the dye is a cyanine dye.
11. The optical filter described in 1 above, wherein the visible light absorption layer has an absorption maximum in the wavelength region of 560 nm to 620 nm.
12. The optical filter described in 1 above, wherein the half-value width of a light absorption band of the visible light absorption layer is 50 nm or less.
13. An image display in which the optical filter described in 1 above is affixed to a front face of the image display.
14. The image display described in 13 above, wherein the image display is a plasma display panel.
DETAILED DESCRIPTION OF THE INVENTION
The invention will be further illustrated in greater detail with reference to the following embodiments, which are, however, not to be construed, of course, as limiting the invention.
The optical filter of the invention is a laminate comprising at least a laminate (A) in which at least one of an antireflection layer, an antiglare layer, a soil-resistant layer, a hard coat layer and an antistatic layer is provided on one face of a transparent support, and a tr
Burns Doane , Swecker, Mathis LLP
Fuji Photo Film Co. , Ltd.
Jr. John Juba
LandOfFree
Optical filter and image display does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Optical filter and image display, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Optical filter and image display will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3078912