Electric lamp and discharge devices – Cathode ray tube – Envelope
Reexamination Certificate
1997-09-10
2001-02-13
Thibodeau, Paul (Department: 1773)
Electric lamp and discharge devices
Cathode ray tube
Envelope
C313S313000, C427S306000, C427S403000, C428S209000, C428S441000, C428S457000, C428S461000, C428S515000
Reexamination Certificate
active
06188174
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a transparent electromagnetic radiation shield panel, more particularly to a transparent electromagnetic radiation shield panel for placement in front of a TV display device or other such source of electromagnetic radiation to shield the viewer from electromagnetic radiation, and to a method of producing the same. The electromagnetic radiation shield panel according the invention is especially suitable for use with a large plasma display panel.
2. Description of the Background Art
An electromagnetic radiation shield material for placement in front of a display device or other source of electromagnetic radiation is required to have excellent visibility and transparency and a wide viewing angle in addition to excellent electromagnetic radiation shielding capability. Japanese Patent Application Laid-Open No. 5-16281 (JP5-16281) teaches an electromagnetic radiation shield material meeting these requirements.
According to the disclosed invention, a transparent plastic sheet is coated with cellulose acetate propionate to form a hydrophilic transparent resin layer thereon. After being air-dried, the coated sheet is soaked in hydrochloric acid palladium colloid catalyst solution to form electroless plating nuclei in the hydrophilic transparent resin, washed with water and subjected to electroless copper plating. The electroless plating is then patterned by etching by the resist method using ferric chloride. The surface of the electroless plating exhibits metallic luster while the hydrophilic transparent resin layer under the patterned electroless plating exhibits black patterning.
This prior-art invention (JP5-16281), however, requires the hydrophilic transparent resin to be formed with electroless plating nucleus catalyst by soaking in hydrochloric acid palladium colloid catalyst solution before the electroless plating step.
Since electroless plating nuclei are adsorbed on both surfaces of the substrate and both surfaces are plated by this method, however, the plating cost is high. An attempt to reduce the plating cost by plating only the coated surface is ineffective, however, since it requires the opposite surface to be treated to prevent plating, which increases the number of processing steps and increases production cost. Another problem with the method is that the soaking of the substrate in the catalyst solution markedly degrades adhesion between the-coating and the substrate.
Moreover, since the impregnation of the coating with catalyst is effected by soaking the substrate in a catalyst solution, uniform catalyst distribution in the thickness direction of the coating is hard to achieve. The blackening of the coating by plating is therefore difficult to conduct stably and efficiently. The method is also poor in product yield because defects tend to arise during patterning of the plating owing to the unevenness of the plating adhesion.
In addition, the popularity of large television sets with plasma displays has increased rapidly in recent years. When the prior-art electromagnetic radiation shield material is used in panels for the large plasma displays of such TVs, the cutting etc. of panels of different sizes from the material cannot be conducted so as to avoid defective portions since the electromagnetic radiation shielding layer is formed directly on a transparent substrate of a size matched to the plasma display. Therefore, if the panel includes a defect, even though at only one place and no matter how small relative to the total surface area, the whole panel must be discarded as defective. This lowers the product yield.
SUMMARY OF THE INVENTION
The present invention overcomes this problem to enable high-yield, economical production of electromagnetic radiation shield panels by cutting sheets of different sizes from a continuous web (roll) of transparent electromagnetic radiation shield film while avoiding inclusion of defective portions in the sheets and laminating the cut sheets to display panels and/or transparent substrates. Since the roll film can be produced by a continuous process, its productivity is higher than unit substrates. Owing to its flexibility, moreover, the film can also be used to produce curved shield panels.
Specifically, this invention provides an electromagnetic radiation shield panel comprising a transparent electromagnetic radiation shield film, a transparent adhesive layer on the transparent electromagnetic radiation shield film and a display panel or a transparent substrate having the transparent electromagnetic radiation shield film laminated thereto by the transparent adhesive layer.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The transparent electromagnetic radiation shield film of the electromagnetic radiation shield panel of this invention can be produced by the method invented earlier by the same inventor and taught by the same assignee's Japanese Patent Application No. 8-191677.
This method comprises using a transparent film as the base material, forming a transparent resin coating including a plating catalyst on at least one surface of the transparent film, forming a layer of plated metal (electromagnetic radiation shielding) on the coated surface by electroless plating while simultaneously blackening the coating, forming a desired resist pattern on the electroless plating layer, and removing portions of the layer of plated metal where no resist is present and blackened portions of the coating thereunder by selective etching.
The transparent film is preferably one constituted as a continuous web that can be continuously processed into a roll. Such films include plastic films having a thickness in the approximate range of 5-300 &mgr;m made of polyethylene terephthalate (PET), polyimide (PI), polyethersulfone (PES), polyether-etherketone (PEEK), polycarbonate (PC), polypropylene (PP), polyamide, acrylic resin, cellulose propionate (CP), and cellulose acetate (CA).
A plasma display produces a relatively large amount of heat and also emits infrared rays that may cause nearby infrared ray devices to malfunction. When the electromagnetic radiation shield panel is used in a plasma display panel, therefore, an infrared ray cut film is preferably used as the transparent film.
The resin contained in the resin solution for coating the base material may be of any type insofar as it exhibits the required transparency as well as good solubility or good dispersibility in metallic salt or metal complex to become the plating catalyst after reduction or reduced metal particles.
For impregnation of the resin with the plating solution so that the reduced metal particles (plating catalyst) form nuclei and react to cause blackening by deposition of the plating metal, the resin used is preferably a hydrophilic transparent resin. Preferable hydrophilic transparent resins include vinyl acetal resins, vinyl alcohol resins, acrylic resins, cellulose resins and the like. Among these, vinyl acetal resins such as polyvinyl butyral and cellulose resins such as cellulose acetate butylate are particularly preferred.
The thickness of the dried coating is preferably about 0.5-5 &mgr;m. When the coating is too thin, blackening of the coating during electroless plating is insufficient and the visibility, an extremely important factor in television applications, is degraded. The problem with an excessively thick coating is difficulty of handling. The plating catalyst contained in the resin coating is reduced metal particles. The reduced metal particles can be directly incorporated in the resin coating or be incorporated therein by reducing a metallic salt or a metal complex contained in the resin coating.
The metallic salt or metal complex used in this invention is preferably an organic or inorganic metallic salt or complex, more preferably an inorganic salt or complex, easily reducible to a metal by a reducing agent (described later), exhibiting plating catalytic activity and solubility in a common solvent (described later) with the resin. Specific examples include sulfates, nitrates,
Nisshinbo Insustries, Inc.
Rickman Holly C
Thibodeau Paul
Wenderoth , Lind & Ponack, L.L.P.
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