Compositions – Electrically conductive or emissive compositions – Free metal containing
Reexamination Certificate
2002-04-05
2003-02-25
Kopec, Mark (Department: 1751)
Compositions
Electrically conductive or emissive compositions
Free metal containing
C252S512000, C252S514000, C106S001050, C106S001130, C106S001150, C106S001190, C106S001210, C106S001230, C106S001240, C106S001280, C438S434000, C438S444000, C423S022000, C423S023000, C345S003100, C345S005000
Reexamination Certificate
active
06524499
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates to a transparent conductive film and a display device in which this transparent conductive film is formed on a display screen, and more particularly, to a transparent conductive film having superior anti-static effects and electromagnetic wave shielding effects using a display screen such as a cathode ray tube or plasma display, high contrast by demonstrating black color in which dark areas are tinted with a blue hue for which the human eye most strongly senses black coloring when viewing transmitted images, and superior chemical stability, as well as a display device in which this transparent conductive film is formed on a display screen.
2. Background Art
Since cathode ray tubes, which are one kind of display device used for the displays of television picture tubes, computers and so forth, depict characters and images on a display screen by bombarding an electron beam onto a fluorescent screen that emits red, green and blue colors, in addition to dust becoming adhered due to static electricity generated on this display screen and lowering visibility, there is also the risk of radiation of electromagnetic waves that have a detrimental effect on the environment.
In addition, plasma displays for which applications have progressed for use as wall-mounted televisions have also been pointed out as having the potential to generate static electricity and radiate electromagnetic waves.
In order to solve these problems, Japanese Unexamined Patent Application, First Publication No. 8-77832, for example, proposes an invention comprising a transparent metal thin film made of fine metal particles at least containing silver and having a mean particle size of 2-200 nm, and a transparent thin film having a different refractive index than said transparent metal thin film, for use as a transparent conductive film having superior electromagnetic wave shielding effects and anti-reflection effects.
However, in these methods of the prior art, although electromagnetic wave shielding effects can be anticipated, the problem of absorbance of transmitted light at 400-500 nm occurring dependent on the optical transmission spectrum of silver, yellowing of the conductive film, and the hue of transmitted images being tinted with a yellow color thereby preventing the display of deep black color and resulting in decreased image contrast, as well as the problem of the surface resistance value of the conductive film rising when immersed in a chemical solution due to its low chemical stability resulting in a decrease in electromagnetic wave shielding effects and requiring that caution be used during handling, were not solved.
In order to solve the above problems, the object of the present invention is to provide a transparent conductive film having superior electromagnetic wave shielding effects and anti-reflection effects, black color tinted with blue color for which the hue of transmitted images is generally considered to have a deep black color, and high chemical stability, as well as a display device in which this transparent conductive film is formed on a display screen.
DISCLOSURE OF THE INVENTION
In order to solve the above problems, the present invention provides a transparent conductive film having a conductive layer at least containing ruthenium fine particles and gold fine particles or ruthenium fine particles, gold fine particles and silver fine particles.
The inventors of the present invention found that as a result of a conductive layer at least containing ruthenium fine particles, and gold fine particles or ruthenium fine particles, gold fine particles and silver fine particles, the transparent conductive film has sufficient electrical conductivity for demonstrating anti-static effects and electromagnetic wave shielding effects, has satisfactory weather resistance as exemplified by salt water resistance, and when this transparent conductive film is formed on the display screen of a display device, the color tone of transmitted images are black tinted with blue resulting in natural hue and high image contrast, thereby enabling the obtaining of a display device having satisfactory visibility.
The weight ratio of the ruthenium fine particles to gold fine particles in the above conductive layer is preferably within the range of 40:60 to 99:1. In addition, silver fine particles are preferably contained at 1-70 wt % relative to the total amount of ruthenium fine particles and gold fine particles.
If the ratio of gold fine particles exceeds the above ratio, the refractive index of the conductive layer changes resulting in poor reflection characteristics, while if the ratio is lower than the above ratio, the problem of decreased electrical conductivity occurs.
In addition, the above conductive layer is preferably formed by applying a coating containing at least ruthenium fine particles and gold fine particles or a coating containing at least ruthenium fine particles, gold fine particles and silver fine particles.
As a result of containing a conductive layer formed using the above coating (to be hereinafter referred to as the “conductive layer forming coating”), the transparent conductive film of the present invention has superior anti-static effects and electromagnetic wave shielding effects, satisfactory weather resistance as exemplified by salt water resistance, and a coated film is obtained having extremely few film defects caused by aggregates of coating components and so forth.
The transparent conductive film of the present invention may also contain a colorant.
Although the transparent conductive film of the present invention improves contrast as a result of the conductive layer containing ruthenium fine particles and gold fine particles which cause the color tone of transmitted images to become black tinted with blue, by containing a colorant in the above conductive layer or at least any one of the other layers, the transparent conductive film can be imparted with the function of a selective absorption filter, thereby making transmitted images of the transparent conductive film extremely vivid.
At least one transparent layer having a refractive index different from that of the above conductive layer is preferably laminated for the upper layer and/or lower layer of the above conductive layer.
As a result of laminating the above transparent layer, the anti-reflection performance of the transparent conductive film is improved, and entrance of external light and haze become extremely low.
In addition, the present invention provides a display device in which any of the above-mentioned transparent conductive films is formed on a display screen.
As a result of having the above transparent conductive film formed on a display screen, this display device has superior anti-static effects and electromagnetic wave shielding effects, satisfactory weather resistance as exemplified by salt water resistance, high contrast as a result of the color tone of transmitted images demonstrating black color tinted with blue, and in the case of the conductive layer being formed by applying the above conductive layer forming coating, the appearance of the coated film is smooth with extremely few film defects caused by aggregates of coating components and so forth. In addition, in the case of the transparent conductive film containing a colorant, transmitted images become extremely vivid. Moreover, if the transparent conductive film has the previously mentioned transparent layer, visibility can be further improved by improving anti-reflection effects.
BEST MODE FOR CARRYING OUT THE INVENTION
The following provides an explanation of modes for carrying out the invention using preferable specific examples.
As a result of conducting earnest research on a transparent conductive film formed by applying a coating containing metal fine particles to as to impart superior visibility and electromagnetic wave shielding effects to the display screen of a display device, the inventors of the present invention found that a transparent conductive film, in which a t
Horikoshi Hideki
Mori Kazutomo
Neya Tadashi
Takamiya Naoki
Kopec Mark
Ostrolenk Faber Gerb & Soffen, LLP
Sumitomo Osaka Cement Co. Ltd.
Vijayakumar Kallambella
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