Electricity: conductors and insulators – Anti-inductive structures – Conductor transposition
Reexamination Certificate
1999-12-30
2001-07-17
Dinkins, Anthony (Department: 2831)
Electricity: conductors and insulators
Anti-inductive structures
Conductor transposition
C174S034000, C361S816000, C361S818000, C428S203000, C428S204000
Reexamination Certificate
active
06262364
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an electromagnetic-wave shielding and light transmitting plate and, more particularly, to an electromagnetic-wave shielding and light transmitting plate suitable for a front filter for a PDP (plasma display panel), which has good electromagnetic-wave shielding efficiency and light transparency.
BACKGROUND OF THE INVENTION
Recently, with the spread of electronic appliances including office automation apparatuses and communication instruments, electromagnetic wave emission from these appliances have come into a problem. That is, adverse effect of electromagnetic wave to the human body is feared and it is also a problem that the electromagnetic wave affects precision apparatus to operate in a wrong way.
In particular, a PDP, which is merchandised as a flat large display in current years, has large electromagnetic wave emission due to its operating mechanism.
Therefore, plates having good electromagnetic-wave shielding efficiency and light transparency have developed and come into practical use. Such plates are also used as windows of a place where a precision apparatus is installed, such as a hospital or a laboratory.
A conventional electromagnetic-wave shielding and light transmitting plate typically comprises transparent plates such as acrylic boards and a conductive mesh member like a wire netting and is formed by interposing the conductive mesh member between the transparent base plates and by integrating them.
The conductive mesh member conventionally used in the electromagnetic-wave shielding and light transmitting plate is a wire netting typically having a wire diameter between 30 and 500 &mgr;m and an open area ratio between about 30% and about 60%.
In the conventional electromagnetic-wave shielding and light transmitting plate using the conductive mesh member, however, the mesh member must be designed to have significantly small mesh size in order to provide sufficient electromagnetic-wave shielding efficiency. Since this means that a net is disposed in front of the PDP of an office automation apparatus, for example an image blurring phenomenon occurs so that distinct pictures can not be provided. Further, a phenomenon that the dots of the PDP and the grids of the mesh member produce interference fringes (so-called “moiré”) also occurs and this phenomenon also makes the pictures unseemly.
The conventional electromagnetic-wave shielding and light transmitting plate has a disadvantages in that reflection of light on a display makes the pictures unseemly and in that the angle of visibility is small so that images on the display are not visible due to lateral incident light. Moreover, there is a problem that heat from the main body of an office automation apparatus results in overheating of the display.
OBJECT AND SUMMARY OF THE INVENTION
It is an object of the present invention to solve the above conventional problems and to provide an electromagnetic-wave shielding and light transmitting plate suitable for an electromagnetic-wave shielding filter for a PDP, which has good electromagnetic-wave shielding efficiency and light transparency, can provide distinct pictures, and can yet be easily made.
It is another object of the present invention to solve the above conventional problems and to provide an electromagnetic-wave shielding and light transmitting plate suitable for an electromagnetic-wave shielding filter for a PDP, which has good electromagnetic-wave shielding efficiency and has large angle of visibility.
It is yet another object of the present invention to solve the above conventional problems and to provide an electromagnetic-wave shielding and light transmitting plate suitable for an electromagnetic-wave shielding filter for a PDP, which has good electromagnetic-wave shielding efficiency and light transparency, can provide distinct pictures, and has adiathermancy.
An electromagnetic-wave shielding and light transmitting plate of a first aspect comprises two transparent base plates and an adhesive layer made of resin in which conductive particles are dispersed and mixed, wherein the base plates are integrally bonded by the adhesive layer.
In the electromagnetic-wave shielding and light transmitting plate of the first aspect, since the conductive particles are dispersed in the adhesive layer, adjusting the particle size and the dispersed amount of the conductive particles can be made to enable, the manufacture of plates having desired electromagnetic-wave shielding efficiency, in addition, good light transparency, without moiréphenomenon.
The electromagnetic-wave shielding and light transmitting plate of the first aspect can be easily made by interposing the adhesive sheet, which is formed by mixing the conductive particles into ethylene-vinyl acetate copolymer (EVA), between the two transparent base plates and bonding them.
In the first aspect, the particle size of the conductive particles is preferably less than 0.5 mm and the ratio of the conductive particles relative to the resin is preferably in a range from 0.1 to 50% by weight.
In addition, the resin is preferably ethylene-vinyl acetate copolymer.
In the electromagnetic-wave shielding and light transmitting plate of the first aspect, a conductive mesh member may be also used.
The electromagnetic-wave shielding and light transmitting plate of the first aspect has the following effects so that it is industrially useful, for example, as an electromagnetic-wave shielding filter for a PDP.
1. Adjusting the particle size and the dispersed amount of the conductive particles provides desired electromagnetic-wave shielding efficiency and good light transparency.
2. The moiré phenomenon due to the use of a conductive mesh member can be prevented so as to provide distinct pictures.
3. The plate can be easily made only by using a normal bonding process.
An electromagnetic-wave shielding and light transmitting plate of a second aspect includes a transparent base plate having a conductive layer which is bonded to a surface of the transparent base plate by resin wherein the conductive layer is a conductive foil which is pattern etched.
The use of pattern etching allows the metallic foil to be etched in any pattern configuration so that the line width, space, and opening configuration can be selected freely as compared with a conductive mesh member. Therefore, the aforementioned electromagnetic-wave shielding and light transmitting plate is made possible by using such a metallic foil which has both good electromagnetic-wave shielding efficiency and good light transparency and which never cause moiré phenomenon.
In the second aspect, the conductive layer may be interposed between two transparent base plates. Further, the conductive layer may be disposed on one of surfaces of one transparent base plate.
It is preferable that the metallic foil is formed in a predetermined pattern by steps of coating with photoresist, pattern exposure, and etching.
In the second aspect, the resin for bonding the conductive layer is preferably ethylene-vinyl acetate copolymer (EVA).
The electromagnetic-wave shielding and light transmitting plate of the second aspect has the following effects so that it is industrially useful, for example, as an electromagnetic-wave shielding filter for a PDP.
1. Selecting the configuration of the pattern etching of conductive foil provides desired electromagnetic-wave shielding efficiency and good light transparency.
2. The moiré phenomenon due to the use of a conductive mesh member can be prevented so as to provide distinct pictures.
An electromagnetic-wave shielding and light transmitting plate of a third aspect includes a transparent base plate having a conductive layer which is formed on a surface of the transparent base plate wherein in that the conductive layer is a conductive film which is pattern etched.
The use of pattern etching allows the conductive film to be etched in any pattern configuration so that the line width, space, and opening configuration can be selected freely as compared with a conductive mesh member. Therefore, the electromagnetic-
Morimura Yasuhiro
Saito Shinji
Yoshikawa Masato
Bridgestone Corporation
Dinkins Anthony
Kanesaka & Takeuchi
Walkenhorst W. David
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