Stock material or miscellaneous articles – Structurally defined web or sheet – Including components having same physical characteristic in...
Reexamination Certificate
1999-07-22
2001-11-20
Jones, Deborah (Department: 1775)
Stock material or miscellaneous articles
Structurally defined web or sheet
Including components having same physical characteristic in...
C428S428000, C428S432000, C428S448000, C428S697000, C428S699000, C428S701000, C359S382000, C359S385000, C359S386000, C359S388000
Reexamination Certificate
active
06319598
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an electromagnetic wave attenuating transparent member, and it is preferably related to an electromagnetic wave attenuating transparent member having an antireflection effect, in particular.
In recent years, there have been doubts that electromagnetic waves emitted from office automation equipment, cathode-ray tubes of television sets and other electronic equipment might have an influence on the human body, and a growing interest in this matter is now taken.
A method which was taken frequently in the past to avoid the influence of these electromagnetic waves was to cover with a conductive member capable of looking through like a wire net.
However, when a cathode-ray tube is covered with the conductive member, a screen becomes hard to be observed, resulting in fatigue of eyes of a user, which has been a problem.
In view of the foregoing, there has been proposed a technology wherein a layered body representing a light-transmitting thin film is provided on the surface of a screen in place of a net of metal fine wires, in order to obtain not only an effect of attenuating electromagnetic waves but also an effect of preventing reflection. For example, in the technology disclosed in TOKKAIHEI No. 6-34801, there is used a three-phase layered body which has a layer of indium tin oxide (ITO) as a transparent and conductive layer, a layer of silicon oxide as a low refractive index layer, and a layer of titanium oxide as a high refractive index layer in this order from the base material. In this technology, however, the transparent and conductive layer is as thin as 300 Å in thickness and an effect of shielding electromagnetic waves is small, resulting in insufficient effects, although the screen became easy to see due to the effect of preventing reflection.
In the technology disclosed in TOKKAIHEI No. 11-73119, on the other hand, a high refractive index layer contains indium tin oxide as a material and its thickness is made to be 1000 Å or more to serve as a transparent and conductive layer in the layer structure of a light-transmitting low refractive index layer and a light-transmitting high refractive index layer.
Owing to a conductive layer which has been made thick, sheet resistivity has been lowered, and an effect of shielding electromagnetic waves has been improved, resulting in efficiency which is sufficient in practical use. However, when stored under the environmental conditions of high temperature and high humidify, a coated layer tended to have color unevenness and to be floated off, which have been problems of resistance to surroundings. In particular, when the coat mentioned above was formed on the transparent plastic base material, these problems were noticeable.
With regard to the coat representing a thin film having the effect of shielding electromagnetic waves stated above, an occasion where it is provided on a transparent member having a curved surface like a lens is also considered in addition to an occasion where it is provided on a flat transparent base material or on a transparent base film material. When coating a thin layer having the effect of shielding electromagnetic waves mentioned above on a positive meniscus type lens, it was normal to coat on the concave surface. This was to prevent occurrence of scratches and to prevent dirt. However, in the case of a coat for electromagnetic wave attenuation and for prevention of reflection which has a transparent and conductive layer with a thickness of 1000 Å or more and is coated on a concave surface, there has been a problem that exfoliation of the coat and color unevenness of the coat color were caused by expansion and contraction of the lens base material when the coat was left for one week under the conditions of high temperature of 60° C. and high humidity of 90%.
When coating a thin layer having an effect of shielding electromagnetic waves on a positive meniscus lens and coating it on a negative meniscus lens, the direction of deformation of the lens is changed. It was therefore found that it is necessary to determine whether to coat on the convex surface of the lens or to coat on the concave surface of the lens, taking the direction of deformations in each lens into consideration.
SUMMARY OF THE INVENTION
An object of the invention is to obtain an electromagnetic wave attenuating transparent member which can intercept electromagnetic waves emitted from office automation equipment, cathode-ray tubes of television sets and from other equipment, disturbs no field of vision, lessens fatigue of eyes, and is highly resistant to surroundings.
The object of the invention can be attained by either one of the following structures.
Structure 1: An electromagnetic wave attenuating transparent member comprising;
a transparent base material, and
a plurality of structural layers including at least one transparent and conductive layer,
wherein sheet resistivity of the electromagnetic wave attenuating transparent member is 100 &OHgr;/cm
2
or less, and a plurality of structural layers include therein the first layer and the second layer which is provided to be farther than the first layer in terms of the distance from the transparent base material, and has density which is higher than that of the first layer.
Structure 2: The electromagnetic wave attenuating transparent member according to Structure 1, wherein the plural structural layers include;
the first high refractive index layer,
the first low refractive index layer,
the second high refractive index layer, and
the second low refractive index layer,
which are arranged in this order from one that is closest to the transparent base material, and the second high refractive index layer is the transparent and conductive layer mentioned above.
Structure 3: The electromagnetic wave attenuating transparent member according to Structure 2, wherein the third low refractive index layer is provided between the transparent base material and the first high refractive index layer.
Structure 4: The electromagnetic wave attenuating transparent member according to Structure 3, wherein the first low refractive index layer, the second low refractive index layer and the third low refractive index layer are made of silicon oxide.
Structure 5: The electromagnetic wave attenuating transparent member according to Structure 2, wherein sheet resistivity of the transparent and conductive layer is 100 &OHgr;/cm
2
or less.
Structure 6: The electromagnetic wave attenuating transparent member according to Structure 1, wherein the first layer and the second layer which has density higher than that of the first layer are not adjoining layers each other.
Structure 7: The electromagnetic wave attenuating transparent member according to Structure 6, wherein both the first layer and the second layer represent a low refractive index layer.
Structure 8: The electromagnetic wave attenuating transparent member according to Structure 7, wherein the first layer is the low refractive index layer closest to the transparent base plate among the low refractive index layers, and the second layer is the low refractive index layer farthest from the transparent base plate among the low refractive index layers.
Structure 9: The electromagnetic wave attenuating transparent member according to Structure 8, wherein the plural structural layers include;
the first high refractive index layer,
the first low refractive index layer,
the second high refractive index layer, and
the second low refractive index layer,
which are arranged in this order from one that is closest to the transparent base material, and the second high refractive index layer is the transparent and conductive layer mentioned above, the first low refractive index layer is the first layer, and the second low refractive index layer is the second layer having density higher than that of the first layer.
Structure 10: The electromagnetic wave attenuating transparent member according to Structure 8, wherein the plural structural layers include;
the first high refractive index layer,
the fi
Nakamura Shingo
Nakano Satoshi
Ohta Tatsuo
Tokuhiro Setsuo
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Jones Deborah
Konica Corporation
Savage Jason
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