Electric lamp and discharge devices – With optical device or special ray transmissive envelope – Polarizer or special ray transmission
Reexamination Certificate
1999-09-24
2001-12-25
Patel, Vip (Department: 2879)
Electric lamp and discharge devices
With optical device or special ray transmissive envelope
Polarizer or special ray transmission
C313S110000
Reexamination Certificate
active
06333592
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a filter for a plasma display panel (hereinafter abbreviated to ‘PDP’) disposed on the front surface of a PDP in order to simultaneously cut electromagnetic waves and near infrared rays generated from the PDP, and a PDP display unit with this filter stuck thereto.
The present application is based on Japanese Patent Applications No. Hei. 10-273043. which is incorporated herein by reference.
2. Description of the Related Art
A PDP is charged with gas mainly consisting of inert gas, particularly neon. In the PDP, electrons discharged from a cathode are accelerated so as to have a collision with gas moleculars and make their way to an anode while being exited or ionized. Positive ions generated in the anode also collide against the cathode so that electrons are emitted so as to commence electrical discharge. At this time, electromagnetic waves and near infrared rays are emitted with the transition procedure of neon atoms.
The emitted near infrared rays have a wavelength in a range of from 850 to 1,200 nm. On the other hand, the light sensitivities of remote controllers for household appliances, KARAOKE equipments, audio/video systems, etc. are in a range of from 700 to 1,300 nm. Therefore, there has arisen a problem that the near infrared rays emitted from the PDP cause erroneous operations in the remote controllers. However, the near infrared rays are generated on the principle of the PDP, and they cannot be prevented in the PDP itself.
Therefore, a filter for cutting electromagnetic waves and near infrared rays generated from the PDP has been investigated. In the background art, for example, there was employed a method in which a plate in which an acrylic sheet with low-resistance metal meshes or etched meshes buried therein and an acrylic sheet mixed with a dye material absorbing near infrared rays are stuck or thermally fused with each other, a plate in which a film including a near infrared ray absorber is stuck to a glass sheet having a silver thin film or the like formed directly by a sputtering process, or a plate in which a sheet having a silver thin film or the like formed by a sputtering process is stuck to an acrylic sheet mixed with a dye material absorbing near infrared rays, is set on the front side of the PDP through an air layer.
The above-mentioned mesh type can obtain a low resistance value, but it has drawbacks that a filter for cutting near infrared rays is necessary otherwise, and a moire phenomenon is produced due to the display pattern intervals of the PDP so that the display quality deteriorates. In the filter produced by a dry process represented by the sputtering process, no moire phenomenon is seen, but there has been no filter which can satisfy at the same time the properties of low resistance, visible light transparency, cutting of near infrared rays of 850 to 1,200 nm, and low visible light reflection, and which can be formed in a comparatively simple laminated configuration. Further, since the filter is set on the front side of the PDP through an air layer in such a method, the visibility is reduced and the features of the PDP, that is, lightness in weight and thinness in thickness, are spoiled.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a PDP filter which can satisfy at the same time the properties necessary for a PDP such as electromagnetic wave shielding properties, near infrared ray cutting properties, low visible light reflection properties, and so on, in a comparatively simple laminated configuration, and which is superior in visibility, light in weight and thin in thickness. It is another object of the present invention to provide a PDP display unit having this PDP filter.
In order to solve the above problem, according to the present invention, a filter for a plasma display panel is constituted by a laminated body in which n units (3≦n≦10) each consisting of a metallic oxide film and a silver transparent electric-conductor film are successively laminated unit after unit on a surface of a transparent film base, and a metallic oxide film is formed on the units as an outermost layer of the laminated body. Each metallic oxide film has optical transparency of a refractive index of 1.5 to 2.7, and each silver transparent electric-conductor film has a thickness set substantially to a fixed value in a range of from 5 to 20 nm. Each of the metallic oxide film put directly on the surface of the base and the outermost-layer metallic oxide film has a thickness 5/2 (1±0.15) times as large as the thickness of each silver transparent electric-conductor film. Each of the other metallic oxide films located halfway between the metallic oxide film put directly on the surface of the base and the outermost-layer metallic oxide film has a thickness 5 (1±0.15) times as large as the thickness of each silver transparent electric-conductor film.
Further, according to the present invention, when a hard-coat layer is formed on the surface of the outermost metallic oxide film and when the refractive index of the hard coat layer exceeds 1.45, the objects of the present invention can be attained by the laminated body in which an anti-reflection and anti-contamination layer 0.001 to 1 &mgr;m thick is further formed on the hard coat layer. Preferably, the hard coat layer is a coating film having a refractive index of 1.45 or less, a thickness of 0.05 to 10 &mgr;m, and an angle of contact with water of 90° or more.
In another aspect, the objects are attained by the laminated body in which a film in which a hard coat layer, an anti-reflection layer and an anti-contamination layer are formed on one surface of another transparent film base is prepared, and the film is stuck to the surface of the outermost metallic oxide film through a transparent adhesive layer formed on the other surface of the other transparent film base.
Further, in the laminated body, it is preferable that an undercoat layer with a refractivity of 1.5 or less and a thickness of 0.05 to 1 &mgr;m is formed between the surface of the transparent film base and the metallic oxide film provided on the surface of the film base.
Further, according to the present invention, the laminated body in which a transparent adhesive layer 10 to 500 &mgr;m thick is formed on the back surface of the transparent film base is stuck to a front display glass portion of a PDP through the transparent adhesive layer (FIG.
7
), or the laminated body is stuck, through the transparent adhesive layer, to the other surface side of a transparent molded body which is attached at its on surface side to the front side of a PDP through an air layer (FIG.
8
). Thus, the expected objects of electromagnetic wave shielding properties, near infrared ray cutting properties and low visible light reflection properties necessary to a PDP can be attained by a comparatively simple laminated configuration.
In addition, it is also possible to provide a PDP display unit having a PDP front filter which is superior in visibility, light in weight and thin in thickness.
Features and advantages of the invention will become understood from the following detailed description of the preferred embodiments described in conjunction with the attached drawings.
REFERENCES:
patent: 4234654 (1980-11-01), Yatabe et al.
patent: 4859532 (1989-08-01), Oyama et al.
patent: 5071206 (1991-12-01), Hood et al.
patent: 0 698 585 A1 (1996-02-01), None
patent: 0 810 452 A2 (1997-12-01), None
patent: 10-217380 (1998-08-01), None
patent: 10-264287 (1998-10-01), None
Nakamura Toshitaka
Sasa Kazuaki
McGinn & Gibb,PLLC
Nitto Denko Corporation
Patel Vip
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